阅读说明：本技术 一种具有网格结构的双极功率晶体管 (Bipolar power transistor with grid structure ) 是由 黄宏嘉 林和 牛崇实 洪学天 于 2021-07-20 设计创作，主要内容包括：本发明公开了一种具有网格结构的双极功率晶体管,包括：具有第一掺杂第二电阻和第二掺杂第一电阻的N型第一导电类集电极区域；具有网格式结构的N型第一导电类发射极区域；具有第三掺杂第四电阻和第四掺杂第三电阻的P型相反导电类基极区域；发射极区域覆盖连接基极区域多个单个的基极元件,集电极区域通过基极-集电极p-n结与基极区域相连接；第一掺杂杂质剂含量高于第二掺杂杂质剂含量,第三掺杂杂质剂含量高于第四掺杂杂质剂含量,第一电阻阻值大于第二电阻阻值,第三电阻阻值大于第四电阻阻值；集电极区域、基极区域和发射极区域分别通过欧姆接触和金属母线相连接；增加二次击穿耐性,降低基极-发射极饱和电压值,安全工作区域显著扩大。(The invention discloses a bipolar power transistor with a grid structure, comprising: an N-type first conductive collector region having a first doped second resistance and a second doped first resistance; an N-type first conductive type emitter region having a lattice structure; a P-type opposite conductivity type base region having a third doped fourth resistor and a fourth doped third resistor; the emitter region overlying a plurality of individual base elements connecting the base region, the collector region being connected to the base region by a base-collector p-n junction; the first impurity doping agent content is higher than the second impurity doping agent content, the third impurity doping agent content is higher than the fourth impurity doping agent content, the first resistance value is larger than the second resistance value, and the third resistance value is larger than the fourth resistance value; the collector region, the base region and the emitter region are respectively connected with a metal bus through ohmic contact; the second breakdown tolerance is increased, the base-emitter saturation voltage value is reduced, and the safe working area is obviously enlarged.)

1. A bipolar power transistor having a mesh structure, comprising:

an N-type first conductive collector region having a first doped second resistance and a second doped first resistance; an N-type first conductive type emitter region having a lattice structure; a P-type opposite conductivity type base region having a third doped fourth resistor and a fourth doped third resistor; the emitter region overlying a plurality of individual base elements connecting the base region, the collector region being connected to the base region by a base-collector p-n junction; the first impurity doping agent content is higher than the second impurity doping agent content, the third impurity doping agent content is higher than the fourth impurity doping agent content, the first resistance value is larger than the second resistance value, and the third resistance value is larger than the fourth resistance value; the collector region, the base region and the emitter region are connected by ohmic contacts and metal busbars, respectively.

2. The bipolar power transistor with grid structure of claim 1, comprising:

the base region includes: the two parts with the P-type conductivity are respectively made of semiconductor materials containing two dopant contents, the third dopant impurity dosage is higher than the fourth dopant impurity dosage, and a fourth resistance value formed by the third dopant impurity dosage is smaller than a third resistance value formed by the fourth dopant impurity dosage; a third impurity-doped region highly doped with the base region is formed between the edge of the emitter region and the ohmic contact of the base region; a collector region ohmic contact and an emitter region ohmic contact are formed through the window in the dielectric material mask; the electrode areas are connected through metal buses, and the metal buses comprise strip-shaped metal buses; the strap metal bus bar includes: the emitter electrode strip-shaped metal bus, the base electrode metal total bus and the emitter electrode metal total bus; the selection of the width of the strip-shaped metal bus of the base electrode comprises the following steps: the ratio of the busbar width of the strip-shaped emitter to the busbar width of the base strip-shaped metal is equal to the ratio of the maximum current of the emitter to the maximum current of the base.

3. The bipolar power transistor with grid structure of claim 2, comprising:

the emitter region is made in the form of a continuous grid comprising: a plurality of panes having a regular geometric shape, an ohmic contact being located in the central portion of each pane, being formed through a window in the dielectric mask and being connected to a metal bus bar of the base through a strip-shaped metal bus bar, an ohmic contact to the emitter region being formed through a window in the dielectric mask at a distance equal to the nearest ohmic contact point of the base and being connected to the metal bus bar of the emitter through a strip-shaped metal bus bar, the emitter bus bar being located opposite the base metal bus bar;

the continuous lattice structure includes: in an N-type substrate having electron conductivity, a low-resistance N + region and a high-resistance N region are formed, the thickness dN of the high-resistance layer is 160 μm, the resistivity is 90ohm. A base region having a third doped fourth resistor and a fourth doped third resistor; the depth of the base-collector p-n junction of the base region with lower doping concentration is 23-26 μm; the metal ohmic contact of the collector region is formed on the back surface of the crystal and is in the N + region of the collector low-resistance region.

4. The bipolar power transistor with grid structure of claim 3, comprising:

the plurality of individual base members of the base region comprises: a plurality of geometries of unit elements forming a repeatable lattice structure, the geometries comprising: circular, square, octagonal, or geometrically symmetric shape;

the continuous mesh-shaped structure of the emitter region includes: the regular octagons are connected in two mutually perpendicular directions through square jumpers, and the side length of each regular octagon is equal to the distance between the nearest panes; the shape of the window pane on which the ohmic contact with the base region is formed is a regular octagon shape with the same side length;

the emitter and the base are formed by symmetrical single elements; forming discrete ohmic contacts to the emitter and base regions at the center of the regular octagon; in each octagon, the region from the contact to the emitter edge functions as a unit resistor, respectively, as an emitter resistor in the emitter grid extension, and as a base resistor in each pane;

the circumference of the emitter formed by the individual octagonal shapes is always greater than the circumference of the comb-shaped shape formed by the long rectangular teeth.

5. The bipolar power transistor with grid structure of claim 4, comprising:

the individual elements of the emitter and base are separated from each other by a region of increased resistance, completely excluding the flow of current between adjacent individual elements of the emitter and base; all the individual elements of the emitter and base are connected to the metal bus bars of the emitter and base, respectively, located at the opposite ends of the crystal, by strip-shaped metal bus bars;

the adopted arrangement of the metal bus bars of the emitter and the base, the bias voltage value deviation of the emitter-base p-n junction of the emitter single element at different distances from the metal bus bar of the emitter is equal to the voltage drop value along the strip-shaped metal bus bars of the emitter and the base; the metal contact of the collector is formed on the back side of the wafer;

the current in each individual element of the emitter region flows symmetrically in four directions in four discrete segments; the currents of adjacent discrete components are not overlapped and are separated by a deeper and heavily doped part of the base region, so that local overheating heat is discharged;

the resistor between the ohmic contact and the edge of the emitter is in the shape of a trapezoid, and the wide side of the resistor is the edge of the emitter; the resistance of the resistor decreases gradually from the contact point to the emitter edge.

6. The bipolar power transistor with grid structure of claim 4, comprising:

metal bus: the device is used for equalizing the potentials of all the single elements of the emitter and the base through the width of the strip-shaped metal bus; eliminating high-resistance voltage, base-emitter saturation voltage and base-emitter input voltage, reducing input resistance, and improving transistor frequency characteristic; the voltage drop V1 along the emitter strip metal bus can be calculated using the following equation:

V₁＝(I₁/n)*((n+1)/2)*ρ*(L₁/(W₁*h₁) Equation (1)

Wherein: i is₁Representing the emitter current portion flowing by a single strip-shaped metal busbar, n representing the number of single emitter elements connected by a single strip-shaped metal busbar, ρ representing the resistivity of the metal material of the strip-shaped metal busbar, L₁，W₁H1 denotes the length, width and thickness of the emitter strip metal busbar, respectively;

the width of the strip-shaped metal bus is selected to equalize the potentials of all the single elements of the emitter and the base; removing extra area and adopting a floating emitter; eliminating high resistance voltage, base-emitter saturation voltage, base-emitter input voltage and reducing input resistance.

7. The bipolar power transistor with grid structure of claim 6, comprising:

the emitter region includes: forming an N-type emitter region of an electron conductive type in the form of a continuous grid at a portion of the base region having a lower doping concentration by using photolithography and phosphorus impurity ion implantation and diffusion, a depth of the emitter-base p-N junction being 11 to 14 μm; a base region not doped with the emitter impurity has a regular octagonal shape, and forms an ohmic contact window lattice with the base region;

the voltage drop V2 along the base strip metal busbar can be calculated by the following equation:

V₂＝(I₂/n)*((n+1)/2)*ρ*(L₂/(W₂*h₂) Equation (2)

Wherein: i is₂Representing the base current portion flowing by a single strip-shaped metal busbar, n representing the number of single base elements connected by a single strip-shaped metal busbar, ρ representing the resistivity of the metal material of the strip-shaped metal busbar, L₂，W₂，h₂Respectively showing the length, width and thickness of the base electrode strip-shaped metal bus;

after the emitter region is formed, the plane of the crystal is protected by a dielectric mask of silicon oxide, wherein ohmic contacts for the base and emitter regions are formed by photolithography and silicon oxide etching;

emitter and base strap metal busbars connecting the split base ohmic contact regions to the base regions with the metal bus bars and the split emitter ohmic contact regions to the emitter regions with the metal bus bars are formed by metal deposition, photolithography and then plasma metal etching.

8. The bipolar power transistor with grid structure of claim 7, comprising:

emitter singles located at opposite edges of the transistor along the emitter strap metal bus will be subject to the same conditions in terms of bias voltage to the emitter-base p-n junction when the voltage drop values along the emitter and base strap metal buses are equal, as follows:

I₁/I₂＝W₁/W₂formula (3)

Wherein, I₁Representing the portion of emitter current, I, flowing by a single strap-like metal busbar₂The base current part flowing by the single strip-shaped metal bus is expressed, and the result obtained based on the formula (1) and the formula (2) is as follows: v₁＝V₂And L₂＝L₁，h₂＝h₁(ii) a And setting the width of the strip metal bus of the base according to the calculated ratio, so that the ratio of the bus width of the strip emitter to the width of the strip metal bus of the base is equal to the ratio of the maximum current of the emitter to the maximum current of the base.

9. The bipolar power transistor with grid structure of claim 1, comprising:

the emitter grid of the transistor structure has a periodic configuration, the number of the emitter strip-shaped metal buses is equal to that of the base strip-shaped metal buses, and the ratio of the emitter maximum current value Iemax to the base maximum current value Ibmax is calculated by the following formula:

Iemax/Ibmax＝W₁/W₂formula (4)

Wherein: iemax denotes the maximum emitter current value, Ibmax denotes the maximum base current value, W₁Width of emitter strip-shaped metal bus bar, W₂The width of the base strip-shaped metal bus is shown;

in the extreme operating mode of the transistor, the voltage drop along the strip-shaped metal bus of the emitter and base is compensated by selecting the width ratio between the emitter and the base by equation (4).

10. A method of using a bipolar power transistor having a mesh structure, comprising:

use of a silicon-based power bipolar transistor and integrated circuit, a metal insulator semiconductor field effect power device, a compound semiconductor power device and/or a power integrated circuit with a bipolar power transistor having a grid structure according to any of claims 1-9, in the following method steps:

step one, establishing a device model required by product application according to the power, breakdown voltage, switching frequency, turn-off current and characteristic frequency of a device andor an integrated circuit, and establishing a database of the device andor the integrated circuit and the model;

determining materials and device types required to be adopted and corresponding process flows according to the models of the devices and/or the integrated circuits; the materials and devices used include: silicon-based or compound semiconductor materials, metal oxide semiconductor field effect (DMOS) power devices, insulated gate bipolar transistors and or electron mobility transistors (HEMTs);

thirdly, performing parameter test of full power and frequency range on the device designed and produced based on the device model, and determining links of the device which need to be improved; the improvement links comprise: the distribution of the breakdown electric field of low breakdown voltage and/or the distribution of current density;

step four, improving the overall or local structure of the device and the corresponding process flow according to the links and weak links of the device and/or the integrated circuit which need to be improved; the method comprises the following steps: for low breakdown voltage, a new device structure is designed by adopting the bipolar power transistor with the grid structure to change the field intensity distribution of the breakdown voltage;

and step five, feeding back the improved test and analysis results of the device to the device model, and establishing a new database.

Technical Field

The present invention relates to the field of semiconductors, and more particularly, to a bipolar power transistor having a grid structure.

Background

One of the most important features of current power transistors is that in order to increase the endurance of the transistor against second breakdown in the Safe Operating Area (SOA), the emitter current must be distributed uniformly over the entire crystal area; known power bipolar transistors with a comb-like structure, in which the distance between the emitter fingers is variable, increasing in order from a minimum at the periphery to a maximum at the center; there are the following problems: the current density is not uniformly distributed in the whole crystal area; under the condition that the displacement modes of the emitter-base electrode p-n junction are different, the peripheral region of the transistor acts, and the peripheral region is positioned along and across the comb teeth of the emitter; due to the voltage drop along the teeth, the current is not uniformly distributed along the length of the emitter comb teeth: the area of the crystal is increased, and the economic index of production and the yield of qualified crystals are reduced; in known designs, the ratio of emitter perimeter to base area and the ratio of emitter area to base area are not optimal; in large signal mode, the use of the pinch resistor results in a reduction in current gain (h 21E); under certain conditions, local overheating of this region may result, and secondary breakdown may occur; therefore, there is a need for a bipolar power transistor having a grid structure to at least partially solve the problems of the prior art.

Disclosure of Invention

In this summary, concepts in a simplified form are introduced that are further described in the detailed description. This summary of the invention is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

To at least partially solve the above problems, the present invention provides a bipolar power transistor having a mesh structure, comprising:

the present invention provides a bipolar power transistor with a grid structure, comprising:

an N-type first conductive collector region having a first doped second resistance and a second doped first resistance; an N-type first conductive type emitter region having a lattice structure; a P-type opposite conductivity type base region having a third doped fourth resistor and a fourth doped third resistor; the emitter region overlying a plurality of individual base elements connecting the base region, the collector region being connected to the base region by a base-collector p-n junction; the first impurity doping agent content is higher than the second impurity doping agent content, the third impurity doping agent content is higher than the fourth impurity doping agent content, the first resistance value is larger than the second resistance value, and the third resistance value is larger than the fourth resistance value; the collector region, the base region and the emitter region are connected by ohmic contacts and metal busbars, respectively.

Preferably, the base region includes: the two parts with the P-type conductivity are respectively made of semiconductor materials containing two dopant contents, the third dopant impurity dosage is higher than the fourth dopant impurity dosage, and a fourth resistance value formed by the third dopant impurity dosage is smaller than a third resistance value formed by the fourth dopant impurity dosage; a third impurity-doped region highly doped with the base region is formed between the edge of the emitter region and the ohmic contact of the base region; a collector region ohmic contact and an emitter region ohmic contact are formed through the window in the dielectric material mask; the electrode areas are connected through metal buses, and the metal buses comprise strip-shaped metal buses; the strap metal bus bar includes: the emitter electrode strip-shaped metal bus, the base electrode metal total bus and the emitter electrode metal total bus; the selection of the width of the strip-shaped metal bus of the base electrode comprises the following steps: the ratio of the busbar width of the strip-shaped emitter to the busbar width of the base strip-shaped metal is equal to the ratio of the maximum current of the emitter to the maximum current of the base.

Preferably, the emitter region is made in the form of a continuous grid comprising: a plurality of panes having a regular geometric shape, an ohmic contact being located in the central portion of each pane, being formed through a window in the dielectric mask and being connected to a metal bus bar of the base through a strip-shaped metal bus bar, an ohmic contact to the emitter region being formed through a window in the dielectric mask at a distance equal to the nearest ohmic contact point of the base and being connected to the metal bus bar of the emitter through a strip-shaped metal bus bar, the emitter bus bar being located opposite the base metal bus bar;

the continuous lattice structure includes: in an N-type substrate having electron conductivity, a low-resistance N + region and a high-resistance N region are formed, the thickness dN of the high-resistance layer is 160 μm, the resistivity is 90ohm. A base region having a third doped fourth resistor and a fourth doped third resistor; the depth of the base-collector p-n junction of the base region with lower doping concentration is 23-26 μm; the metal ohmic contact of the collector region is formed on the back surface of the crystal and is in the N + region of the collector low-resistance region.

Preferably, the plurality of individual base members of the base region comprises: a plurality of geometries of unit elements forming a repeatable lattice structure, the geometries comprising: circular, square, octagonal, or geometrically symmetric shape;

the continuous mesh-shaped structure of the emitter region includes: the regular octagons are connected in two mutually perpendicular directions through square jumpers, and the side length of each regular octagon is equal to the distance between the nearest panes; the shape of the window pane on which the ohmic contact with the base region is formed is a regular octagon shape with the same side length;

the emitter and the base are formed by symmetrical single elements; forming discrete ohmic contacts to the emitter and base regions at the center of the regular octagon; in each octagon, the region from the contact to the emitter edge functions as a unit resistor, respectively, as an emitter resistor in the emitter grid extension, and as a base resistor in each pane;

the circumference of the emitter formed by the individual octagonal shapes is always greater than the circumference of the comb-shaped shape formed by the long rectangular teeth.

Preferably, the individual elements of the emitter and of the base are separated from each other by a region of increased resistance, completely excluding the flow of current between adjacent individual elements of the emitter and of the base; all the individual elements of the emitter and base are connected to the metal bus bars of the emitter and base, respectively, located at the opposite ends of the crystal, by strip-shaped metal bus bars;

the adopted arrangement of the metal bus bars of the emitter and the base, the bias voltage value deviation of the emitter-base p-n junction of the emitter single element at different distances from the metal bus bar of the emitter is equal to the voltage drop value along the strip-shaped metal bus bars of the emitter and the base; the metal contact of the collector is formed on the back side of the wafer;

the current in each individual element of the emitter region flows symmetrically in four directions in four discrete segments; the currents of adjacent discrete components are not overlapped and are separated by a deeper and heavily doped part of the base region, so that local overheating heat is discharged;

the resistor between the ohmic contact and the edge of the emitter is in the shape of a trapezoid, and the wide side of the resistor is the edge of the emitter; the resistance of the resistor decreases gradually from the contact point to the emitter edge.

Preferably, the metal bus bar: the device is used for equalizing the potentials of all the single elements of the emitter and the base through the width of the strip-shaped metal bus; eliminating high-resistance voltage, base-emitter saturation voltage and base-emitter input voltage, reducing input resistance, and improving transistor frequency characteristic; the voltage drop V1 along the emitter strip metal bus can be calculated using the following equation:

v1 ═ I1/n ((n +1)/2) × (L1/(W1 × h1)) formula (1)

Wherein:

i1 denotes the portion of the emitter current that a single strap metal bus bar flows,

n denotes the number of individual emitter elements connected by a single strip-shaped metal busbar,

ρ represents the resistivity of the metal material of the strip-shaped metal bus bar,

l1, W1, h1 denote the length, width and thickness of the emitter strip metal busbar, respectively.

The width of the strip-shaped metal bus is selected to equalize the potentials of all the single elements of the emitter and the base; removing extra area and adopting a floating emitter; eliminating high resistance voltage, base-emitter saturation voltage, base-emitter input voltage and reducing input resistance.

Preferably, the emitter region includes: forming an N-type emitter region of an electron conductive type in the form of a continuous grid at a portion of the base region having a lower doping concentration by using photolithography and phosphorus impurity ion implantation and diffusion, a depth of the emitter-base p-N junction being 11 to 14 μm; a base region not doped with the emitter impurity has a regular octagonal shape, and forms an ohmic contact window lattice with the base region;

the voltage drop V2 along the base strip metal busbar can be calculated by the following equation:

V₂＝(I₂/n)*((n+1)/2)*ρ*(L₂/(W₂*h₂) Equation (2)

Wherein: i is₂Representing the base current portion flowing by a single strip-shaped metal busbar, n representing the number of single base elements connected by a single strip-shaped metal busbar, ρ representing the resistivity of the metal material of the strip-shaped metal busbar, L₂，W₂，h₂Respectively showing the length, width and thickness of the base electrode strip-shaped metal bus;

after the emitter region is formed, the plane of the crystal is protected by a dielectric mask of silicon oxide, wherein ohmic contacts for the base and emitter regions are formed by photolithography and silicon oxide etching;

emitter and base strap metal busbars connecting the split base ohmic contact regions to the base regions with the metal bus bars and the split emitter ohmic contact regions to the emitter regions with the metal bus bars are formed by metal deposition, photolithography and then plasma metal etching.

Preferably, the emitter individual elements, which are located at opposite edges of the transistor along the strip-shaped metal bus of the emitter, will be subject to the same conditions in terms of bias voltage applied to the emitter-base p-n junction when the voltage drop values along the strip-shaped metal bus of the emitter and base are equal, and the formula is as follows:

I₁/I₂＝W₁/W₂formula (3)

Wherein, I₁Representing the portion of emitter current, I, flowing by a single strap-like metal busbar₂The base current part flowing by the single strip-shaped metal bus is expressed, and the result obtained based on the formula (1) and the formula (2) is as follows: v₁＝V₂And L₂＝L₁，h₂＝h₁(ii) a And setting the width of the strip metal bus of the base according to the calculated ratio, so that the ratio of the bus width of the strip emitter to the width of the strip metal bus of the base is equal to the ratio of the maximum current of the emitter to the maximum current of the base.

Preferably, the emitter grid of the transistor structure has a periodic configuration, the number of the emitter strip metal bus bars is equal to the number of the base strip metal bus bars, and a ratio of the emitter maximum current value Iemax to the base maximum current value Ibmax is calculated, where the formula is as follows:

Iemax/Ibmax＝W₁/W₂formula (4)

Wherein: iemax denotes the maximum emitter current value, Ibmax denotes the maximum base current value, W₁Width of emitter strip-shaped metal bus bar, W₂The width of the base strip-shaped metal bus is shown;

in the extreme operating mode of the transistor, the voltage drop along the strip-shaped metal bus of the emitter and base is compensated by selecting the width ratio between the emitter and the base by equation (4).

The use of a bipolar power transistor with a grid structure according to any of the preferred embodiments, comprising:

the application of a silicon-based power bipolar transistor and an integrated circuit, a metal insulator semiconductor field effect power device, a compound semiconductor power device and/or a power integrated circuit of a bipolar power transistor with a grid structure comprises the following steps:

step one, establishing a device model required by product application according to the power, breakdown voltage, switching frequency, turn-off current and characteristic frequency of a device andor an integrated circuit, and establishing a database of the device andor the integrated circuit and the model;

determining materials and device types required to be adopted and corresponding process flows according to the models of the devices and/or the integrated circuits; the materials and devices used include: silicon-based or compound semiconductor materials, metal oxide semiconductor field effect (DMOS) power devices, insulated gate bipolar transistors and or electron mobility transistors (HEMTs);

thirdly, performing parameter test of full power and frequency range on the device designed and produced based on the device model, and determining links of the device which need to be improved; the improvement links comprise: the distribution of the breakdown electric field of low breakdown voltage and/or the distribution of current density;

step four, improving the overall or local structure of the device and the corresponding process flow according to the links and weak links of the device and/or the integrated circuit which need to be improved; the method comprises the following steps: for low breakdown voltage, a new device structure is designed by adopting the bipolar power transistor with the grid structure to change the field intensity distribution of the breakdown voltage;

and step five, feeding back the improved test and analysis results of the device to the device model, and establishing a new database.

Compared with the prior art, the invention at least comprises the following beneficial effects:

a device with an extended safe operating region can be obtained without increasing the crystal size, the second breakdown resistance of the device is increased, and the base-emitter saturation voltage value is reduced; an N-type first conductive type collector region having a first doped second resistance and a second doped first resistance; an N-type first conductive type emitter region having a lattice structure; a P-type opposite conductivity type base region having a third doped fourth resistor and a fourth doped third resistor; the emitter region overlying a plurality of individual base elements connecting the base region, the collector region being connected to the base region by a base-collector p-n junction; the first impurity doping agent content is higher than the second impurity doping agent content, the third impurity doping agent content is higher than the fourth impurity doping agent content, the first resistance value is larger than the second resistance value, and the third resistance value is larger than the fourth resistance value; the collector region, the base region and the emitter region are respectively connected with a metal bus through ohmic contact; a collector and emitter region of the same conductivity type and a base region of the opposite conductivity type, formed by portions having different dopant contents, ohmic contacts to the base and emitter regions being formed through windows in the mask of dielectric material, the base region portion formed between the edge of the emitter region and the ohmic contact to the base region having a high dopant content; the use of the proposed design of a power bipolar transistor with a continuous grid-shaped emitter allows to reach lower voltage saturation values of the base-emitter junction on transistors smaller than the prototype, obtaining higher limit current values and maximum dissipation current values than the prototype, compared to the collector-emitter voltage saturation values of the prototype, thus allowing to produce devices with a significantly enlarged safe operating area compared to the prototype, obtaining devices with a much lower base-emitter saturation voltage and power density than the prototype on transistors of smaller dimensions.

Other advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:

fig. 1 is a top view of a mesh transistor of a bipolar power transistor having a mesh structure according to the present invention.

Fig. 2 is a cross-sectional view of a bipolar power transistor mesh transistor having a mesh structure according to the present invention at reference a.

Fig. 3 is a cross-sectional view of a bipolar power transistor mesh transistor having a mesh structure according to the present invention at reference B.

Fig. 4 is a diagram illustrating an application procedure of a bipolar power transistor with a grid structure according to the present invention.

Fig. 5 is a comparison of the technical parameters of a new power bipolar transistor with a grid-structured bipolar power transistor according to the present invention and a prototype transistor.

Detailed Description

The present invention is further described in detail below with reference to the drawings and examples so that those skilled in the art can practice the invention with reference to the description.

As shown in fig. 1-3, the present invention provides a bipolar power transistor having a lattice structure, comprising:

an N-type first conductive collector region having a first doped second resistance and a second doped first resistance; an N-type first conductive type emitter region having a lattice structure; a P-type opposite conductivity type base region having a third doped fourth resistor and a fourth doped third resistor; the emitter region overlying a plurality of individual base elements connecting the base region, the collector region being connected to the base region by a base-collector p-n junction; the first impurity doping agent content is higher than the second impurity doping agent content, the third impurity doping agent content is higher than the fourth impurity doping agent content, the first resistance value is larger than the second resistance value, and the third resistance value is larger than the fourth resistance value; the collector region, the base region and the emitter region are connected by ohmic contacts and metal busbars, respectively.

The working principle of the technical scheme is as follows: a collector and emitter region of the same conductivity type and a base region of the opposite conductivity type, formed by portions having different dopant contents, ohmic contacts to the base and emitter regions being formed through windows in the mask of dielectric material, the base region portion formed between the edge of the emitter region and the ohmic contact to the base region having a high dopant content; an N-type first conductive type collector region having a first doped second resistance and a second doped first resistance; an N-type first conductive type emitter region having a lattice structure; a P-type opposite conductivity type base region having a third doped fourth resistor and a fourth doped third resistor; the emitter region overlying a plurality of individual base elements connecting the base region, the collector region being connected to the base region by a base-collector p-n junction; the first impurity doping agent content is higher than the second impurity doping agent content, the third impurity doping agent content is higher than the fourth impurity doping agent content, the first resistance value is larger than the second resistance value, and the third resistance value is larger than the fourth resistance value; the collector region, the base region and the emitter region are respectively connected with a metal bus through ohmic contact; the use of the proposed design of a power bipolar transistor with a continuous grid-shaped emitter allows to reach lower voltage saturation values of the base-emitter junction on transistors smaller than the prototype, obtaining higher limit current values and maximum dissipation current values than the prototype, compared to the collector-emitter voltage saturation values of the prototype, thus allowing to produce devices with a significantly enlarged safe operating area compared to the prototype, obtaining devices with a much lower base-emitter saturation voltage and power density than the prototype on transistors of smaller dimensions.

The beneficial effects of the above technical scheme are that: a device with an extended safe operating region can be obtained without increasing the crystal size, the second breakdown resistance of the device is increased, and the base-emitter saturation voltage value is reduced; an N-type first conductive type collector region having a first doped second resistance and a second doped first resistance; an N-type first conductive type emitter region having a lattice structure; a P-type opposite conductivity type base region having a third doped fourth resistor and a fourth doped third resistor; the emitter region overlying a plurality of individual base elements connecting the base region, the collector region being connected to the base region by a base-collector p-n junction; the first impurity doping agent content is higher than the second impurity doping agent content, the third impurity doping agent content is higher than the fourth impurity doping agent content, the first resistance value is larger than the second resistance value, and the third resistance value is larger than the fourth resistance value; the collector region, the base region and the emitter region are respectively connected with a metal bus through ohmic contact; a collector and emitter region of the same conductivity type and a base region of the opposite conductivity type, formed by portions having different dopant contents, ohmic contacts to the base and emitter regions being formed through windows in the mask of dielectric material, the base region portion formed between the edge of the emitter region and the ohmic contact to the base region having a high dopant content; the use of the proposed design of a power bipolar transistor with a continuous grid-shaped emitter allows to reach lower voltage saturation values of the base-emitter junction on transistors smaller than the prototype, obtaining higher limit current values and maximum dissipation current values than the prototype, compared to the collector-emitter voltage saturation values of the prototype, thus allowing to produce devices with a significantly enlarged safe operating area compared to the prototype, obtaining devices with a much lower base-emitter saturation voltage and power density than the prototype on transistors of smaller dimensions.

In one embodiment, the method comprises the following steps:

the base region includes: the two parts with the P-type conductivity are respectively made of semiconductor materials containing two dopant contents, the third dopant impurity dosage is higher than the fourth dopant impurity dosage, and a fourth resistance value formed by the third dopant impurity dosage is smaller than a third resistance value formed by the fourth dopant impurity dosage; a third impurity-doped region highly doped with the base region is formed between the edge of the emitter region and the ohmic contact of the base region; a collector region ohmic contact and an emitter region ohmic contact are formed through the window in the dielectric material mask; the electrode areas are connected through metal buses, and the metal buses comprise strip-shaped metal buses; the strap metal bus bar includes: the emitter electrode strip-shaped metal bus, the base electrode metal total bus and the emitter electrode metal total bus; the selection of the width of the strip-shaped metal bus of the base electrode comprises the following steps: the ratio of the busbar width of the strip-shaped emitter to the busbar width of the base strip-shaped metal is equal to the ratio of the maximum current of the emitter to the maximum current of the base.

The working principle of the technical scheme is as follows: the two parts with different dopant contents have different resistances, the part with high dopant impurity dosage is a low-resistance part, and the part with low dopant impurity dosage is a high-resistance part; forming ohmic contacts to the collector region at the center of each pane through the windows of the dielectric mask and to the metal bus bar of the base through the strip-shaped metal bus bar, the ohmic contacts to the emitter region being formed through the windows in the dielectric mask at equal distances from the nearest ohmic contact of the collector and being connected to the metal bus bar of the emitter through the strip-shaped metal bus bar, the emitter bus bar being located opposite the metal bus bar of the base; the ratio of the width of the strip-shaped metal bus of the emitter to the width of the strip-shaped base bus is equal to the ratio of the maximum current of the emitter to the maximum current of the base.

The beneficial effects of the above technical scheme are that: the base region includes: the two parts with the P-type conductivity types are respectively made of semiconductor materials containing two dopant contents, the third dopant impurity dosage is higher than the fourth dopant impurity dosage, the fourth resistance formed by the third dopant impurity dosage is smaller than the third resistance formed by the fourth dopant impurity dosage, and the two parts with different dopant contents can form different resistances and have richer and superior electrical properties; a third impurity-doped region highly doped with the base region is formed between the edge of the emitter region and the ohmic contact of the base region; a collector region ohmic contact and an emitter region ohmic contact are formed through the window in the dielectric material mask; the electrode areas are connected through metal buses, and the metal buses comprise strip-shaped metal buses; the strap metal bus bar includes: the emitter electrode strip-shaped metal bus, the base electrode metal total bus and the emitter electrode metal total bus; the selection of the width of the strip-shaped metal bus of the base electrode comprises the following steps: the ratio of the bus width of the strip-shaped emitter to the bus width of the base strip-shaped metal is equal to the ratio of the maximum current of the emitter to the maximum current of the base, and the structure can enable the current ratio to be more suitable for improving the performance.

In one embodiment, the method comprises the following steps:

the emitter region is made in the form of a continuous grid comprising: a plurality of panes having a regular geometric shape, an ohmic contact being located in the central portion of each pane, being formed through a window in the dielectric mask and being connected to a metal bus bar of the base through a strip-shaped metal bus bar, an ohmic contact to the emitter region being formed through a window in the dielectric mask at a distance equal to the nearest ohmic contact point of the base and being connected to the metal bus bar of the emitter through a strip-shaped metal bus bar, the emitter bus bar being located opposite the base metal bus bar;

the continuous lattice structure includes: in an N-type substrate having electron conductivity, a low-resistance N + region and a high-resistance N region are formed, the thickness dN of the high-resistance layer is 160 μm, the resistivity is 90ohm. A base region having a third doped fourth resistor and a fourth doped third resistor; the depth of the base-collector p-n junction of the base region with lower doping concentration is 23-26 μm; the metal ohmic contact of the collector region is formed on the back surface of the crystal and is in the N + region of the collector low-resistance region.

The working principle of the technical scheme is as follows: the emitter region is made in the form of a continuous grid having a plurality of panes of regular geometric shape, the unilateral length of which is equal to the distance between the nearest panes in two mutually perpendicular directions; the continuous lattice structure includes: in an N-type substrate with electron conductivity, forming a low resistance (N +) and a high resistance (N) region, using a standard oxidation method, performing two times of photoetching, ion implantation doping and diffusion to form a base region with hole conductivity, wherein the base region comprises two parts with different doping concentrations: a base region having a third doped fourth resistor and a fourth doped third resistor; the metal ohmic contact of the collector region is formed on the back surface of the crystal and is positioned in the N + region of the low-resistance type collector region; the main steps of the production flow of the mesh-structure power transistor are as follows: in an N-type substrate having electron conductivity, low-resistance (N +) and high-resistance (N) regions are formed, the high-resistance layer has a thickness dN of 160 μm and a resistivity of 90ohm. The base-collector p-n junction depth of the base region with lower doping concentration is xjp ═ 23 to 26 mu m; for silicon devicesDoping concentration range of P-type silicon: 1E 13-1E 18/cm³Doping concentration range of N-type silicon: 1E 13-1E 19/cm³(ii) a Ohmic contacts are located in the center of each pane, formed through the windows of the dielectric mask and connected to the metal bus bars of the base via strip-shaped metal bus bars, and ohmic contacts to the emitter regions are formed through the windows in the dielectric mask at equal distances from the nearest ohmic contact of the base and connected to the metal bus bars of the emitter via strip-shaped metal bus bars, which are located opposite the base metal bus bars.

The beneficial effects of the above technical scheme are that: by making the emitter region in the form of a continuous grid, the main steps of the production flow of a mesh-structured power transistor are as follows: in an N-type substrate having electron conductivity, low-resistance (N +) and high-resistance (N) regions are formed, the high-resistance layer has a thickness dN of 160 μm and a resistivity of 90ohm. The base-collector p-n junction depth of the base region with lower doping concentration is xjp ═ 23 to 26 mu m; the grid has a plurality of panes of regular geometric shape, the length of one side of which is equal to the distance between the nearest panes in two mutually perpendicular directions; ohmic contacts are located in the center of each pane, formed through the windows of the dielectric mask and connected to the metal bus bars of the base via strip-shaped metal bus bars, and ohmic contacts to the emitter regions are formed through the windows in the dielectric mask at equal distances from the nearest ohmic contact of the base and connected to the metal bus bars of the emitter via strip-shaped metal bus bars, which are located opposite the base metal bus bars.

In one embodiment, the method comprises the following steps:

the plurality of individual base members of the base region comprises: a plurality of geometries of unit elements forming a repeatable lattice structure, the geometries comprising: circular, square, octagonal, or geometrically symmetric shape;

the continuous mesh-shaped structure of the emitter region includes: the regular octagons are connected in two mutually perpendicular directions through square jumpers, and the side length of each regular octagon is equal to the distance between the nearest panes; the shape of the window pane on which the ohmic contact with the base region is formed is a regular octagon shape with the same side length;

the emitter and the base are formed by symmetrical single elements; forming discrete ohmic contacts to the emitter and base regions at the center of the regular octagon; in each octagon, the region from the contact to the emitter edge functions as a unit resistor, respectively, as an emitter resistor in the emitter grid extension, and as a base resistor in each pane;

the circumference of the emitter formed by the individual octagonal shapes is always greater than the circumference of the comb-shaped shape formed by the long rectangular teeth.

The working principle of the technical scheme is as follows: all the individual elements of the emitter and the base take the form of regular octagons; ohmic contacts to each individual element are formed at a central portion thereof; a portion of the emitter region from the ohmic contact to the edge of the individual element is an additional distributed emitter resistor; the base region is composed of two portions having different dopant contents; ohmic contacts to each individual element in the pane are formed in a central portion thereof and are high in dopant content; part of the base single element from the ohmic contact to the emitter edge is an additional distributed base resistor; the resistance value of the resistor is controlled by the distance of the emitter edge to the interface between the base portions having different doping concentrations; when the cells of the grid have the shape of a regular octagon, the most symmetrical distribution of the current can be achieved;

fig. 5 is a table showing a comparison of the technical parameters of a power bipolar transistor and a prototype transistor according to the invention; it is easily derived from the table of fig. 5 by simple calculations that the power bipolar transistor with continuous grid-shaped emitter proposed by the present invention is reduced in size by 24% and the power density is increased by almost 40% compared to the prototype transistor with comb structure; the transistor structure provided by the invention has the advantages that the performance of a device is obviously improved and the production cost is greatly reduced through the novel grid-shaped transistor structure.

The beneficial effects of the above technical scheme are that: when the cells of the grid have the shape of a regular octagon, the most symmetrical distribution of the current can be achieved; the emitter and the base are formed by symmetrical single elements; due to the presence of the narrow part of the emitter grid, the influence of neighboring elements on each other is excluded in this design; the emitter and the base are formed by symmetrical single elements; forming discrete ohmic contacts to the emitter and base regions at the center of the regular octagon; in each octagon, the region from the contact to the emitter edge functions as a unit resistor, respectively, as an emitter resistor in the emitter grid extension, and as a base resistor in each pane; the problem that in the structure with the comb-shaped emitter, the voltage along the teeth is reduced due to the current flowing along the teeth can be solved; compared with the best similar device at present, the transistor structure provided by the invention can at least increase the power density by nearly 40% and reduce the transistor size by about 24% through a novel grid-shaped transistor structure, and the performance of the device is obviously improved and the production cost is greatly reduced.

In one embodiment, the method comprises the following steps:

the individual elements of the emitter and base are separated from each other by a region of increased resistance, completely excluding the flow of current between adjacent individual elements of the emitter and base; all the individual elements of the emitter and base are connected to the metal bus bars of the emitter and base, respectively, located at the opposite ends of the crystal, by strip-shaped metal bus bars;

the adopted arrangement of the metal bus bars of the emitter and the base, the bias voltage value deviation of the emitter-base p-n junction of the emitter single element at different distances from the metal bus bar of the emitter is equal to the voltage drop value along the strip-shaped metal bus bars of the emitter and the base; the metal contact of the collector is formed on the back side of the wafer;

the current in each individual element of the emitter region flows symmetrically in four directions in four discrete segments; the currents of adjacent discrete components are not overlapped and are separated by a deeper and heavily doped part of the base region, so that local overheating heat is discharged;

the resistor between the ohmic contact and the edge of the emitter is in the shape of a trapezoid, and the wide side of the resistor is the edge of the emitter; the resistance of the resistor decreases gradually from the contact point to the emitter edge.

The working principle of the technical scheme is as follows: by separating the individual elements of the emitter and base from each other by regions of increased resistance, the flow of current between adjacent individual elements of the emitter and base is completely excluded; all the individual elements of the emitter and base are connected to the metal bus bars of the emitter and base, respectively, located at the opposite ends of the crystal, by strip-shaped metal bus bars;

with the arrangement of the emitter and base metal bus bars, the bias voltage values of the emitter-base p-n junctions of the emitter individual elements located at different distances from the emitter metal bus bar will deviate by an amount equal to the voltage drop along the emitter and base strip metal bus bars; the metal contact of the collector is formed on the back side of the wafer;

the current in each single element of the emitter region flows symmetrically in four directions, mainly in four discrete segments; the currents of adjacent discrete components are not overlapped and are separated by a deeper and heavily doped part of the base region, so that local overheating heat is discharged;

the resistor between the ohmic contact and the edge of the emitter is in the shape of a trapezoid, and the wide side of the resistor is the edge of the emitter; the resistance of the resistor gradually decreases from the contact point to the emitter edge; equalizing the heat distribution in each individual element area;

the resistance of the distributed resistor decreases closer to the edge of the emitter due to its expansion, while the radial flow of current from the narrow ohmic contact to the edge of the emitter is equalized in each individual element of the emitter; thus, in the proposed power bipolar transistor design, all individual elements of the transistor structure are in the same condition with respect to the bias voltage of the emitter-base p-n junction, thereby ensuring a uniform distribution of the current density over the transistor operating area and reducing the probability of a second breakdown, i.e. enlarging the safe operating area of the power device; the ratio of the area of the emitter to the area of the base is greater than 0.5; the current in each single element of the emitter region flows symmetrically in four directions, mainly in four discrete segments; the currents of adjacent discrete elements do not overlap because they are separated by a deeper and heavily doped portion of the base region, thereby precluding the possibility of local overheating; the metal ohmic contact of the electrode region is formed on the back surface of the crystal, namely in a collector low-resistance region (N + region);

the beneficial effects of the above technical scheme are that: the individual elements of the emitter and base are separated from each other by a region of increased resistance, completely excluding the flow of current between adjacent individual elements of the emitter and base; all the individual elements of the emitter and base are connected to the metal bus bars of the emitter and base, respectively, located at the opposite ends of the crystal, by strip-shaped metal bus bars; with the arrangement of the emitter and base metal bus bars, the bias voltage values of the emitter-base p-n junctions of the emitter individual elements located at different distances from the emitter metal bus bar will deviate by an amount equal to the voltage drop along the emitter and base strip metal bus bars; the metal contact of the collector is formed on the back side of the wafer; the current in each single element of the emitter region flows symmetrically in four directions, mainly in four discrete segments; the currents of adjacent discrete components are not overlapped and are separated by a deeper and heavily doped part of the base region, so that local overheating heat is discharged; the resistor between the ohmic contact and the edge of the emitter is in the shape of a trapezoid, and the wide side of the resistor is the edge of the emitter; the resistance of the resistor gradually decreases from the contact point to the emitter edge; equalizing the heat distribution in each individual element area;

the resistance of the distributed resistor decreases closer to the edge of the emitter due to its expansion, while the radial flow of current from the narrow ohmic contact to the edge of the emitter is equalized in each individual element of the emitter; thus, in the proposed power bipolar transistor design, all individual elements of the transistor structure are in the same condition with respect to the bias voltage of the emitter-base p-n junction, thereby ensuring a uniform distribution of the current density over the transistor operating area and reducing the probability of a second breakdown, i.e. enlarging the safe operating area of the power device; the ratio of the area of the emitter to the area of the base is greater than 0.5; the current in each single element of the emitter region flows symmetrically in four directions, mainly in four discrete segments; the currents of adjacent discrete elements do not overlap because they are separated by a deeper and heavily doped portion of the base region, thereby precluding the possibility of local overheating; the metal ohmic contact of the electrode region is formed on the back surface of the crystal, namely in a collector low-resistance region (N + region); the ratio of emitter area to base area is greater than 0.5, which is superior to the ratio of no more than 0.4 in known designs of prior additional "floating" emitters.

In one embodiment, the method comprises the following steps:

metal bus: the device is used for equalizing the potentials of all the single elements of the emitter and the base through the width of the strip-shaped metal bus; eliminating high-resistance voltage, base-emitter saturation voltage and base-emitter input voltage, reducing input resistance, and improving transistor frequency characteristic; the voltage drop V1 along the emitter strip metal bus can be calculated using the following equation:

V₁＝(I₁/n)*((n+1)/2)*ρ*(L₁/(W₁*h₁) Equation (1)

Wherein: i is₁Representing the emitter current portion flowing by a single strip-shaped metal busbar, n representing the number of single emitter elements connected by a single strip-shaped metal busbar, ρ representing the resistivity of the metal material of the strip-shaped metal busbar, L₁，W₁H1 denotes the length, width and thickness of the emitter strip metal busbar, respectively;

the width of the strip-shaped metal bus is selected to equalize the potentials of all the single elements of the emitter and the base; removing extra area and adopting a floating emitter; eliminating high resistance voltage, base-emitter saturation voltage, base-emitter input voltage and reducing input resistance.

The working principle of the technical scheme is as follows: the potentials of all single elements of the emitter and the base are equalized by selecting the width of the strip-shaped metal bus; eliminating high-resistance voltage, base-emitter saturation voltage and base-emitter input voltage, reducing input resistance, and improving transistor frequency characteristic; further comprising: reducing the size of the transistor, eliminating additional area, employing a floating emitter, and increasing the ratio of emitter area to base area; the voltage drop V1 along the emitter strip metal bus can be calculated using the following equation:

v1 ═ I1/n ((n +1)/2) × (L1/(W1 × h1)) formula (1)

Wherein:

i1 denotes the portion of the emitter current that a single strap metal bus bar flows,

n denotes the number of individual emitter elements connected by a single strip-shaped metal busbar,

ρ represents the resistivity of the metal material of the strip-shaped metal bus bar,

l1, W1, h1 denote the length, width and thickness of the emitter strip metal busbar, respectively.

The width of the strip-shaped metal bus is selected to equalize the potentials of all the single elements of the emitter and the base; removing extra area and adopting a floating emitter; eliminating high resistance, base-emitter saturation voltage, base-emitter input voltage, and reducing input resistance, and improving frequency characteristic of transistor.

The beneficial effects of the above technical scheme are that: the width of the strip-shaped metal bus is selected, so that the potentials of all single elements of the emitter and the base can be balanced; eliminating high-resistance voltage, base-emitter saturation voltage and base-emitter input voltage, reducing input resistance, and improving transistor frequency characteristic; reducing the size of the transistor, eliminating additional area, employing a floating emitter, and increasing the ratio of emitter area to base area; after the voltage drop along the strip-shaped metal bus of the emitter is calculated, the potentials of all single elements of the emitter and the base are balanced by selecting the width of the strip-shaped metal bus; removing extra area and adopting a floating emitter; eliminating high-resistance voltage resistor, saturation voltage of base-emitter, input voltage of base-emitter and reducing input resistor, and improving frequency characteristic of transistor; and the potentials of all the individual elements of the emitter and the base can be equalized.

In one embodiment, the method comprises the following steps:

the emitter region includes: forming an N-type emitter region of an electron conductive type in the form of a continuous grid at a portion of the base region having a lower doping concentration by using photolithography and phosphorus impurity ion implantation and diffusion, a depth of the emitter-base p-N junction being 11 to 14 μm; a base region not doped with the emitter impurity has a regular octagonal shape, and forms an ohmic contact window lattice with the base region;

the voltage drop V2 along the base strip metal busbar can be calculated by the following equation:

V₂＝(I₂/n)*((n+1)/2)*ρ*(L₂/(W₂*h₂) Equation (2)

Wherein: i is₂Representing the base current portion flowing by a single strip-shaped metal busbar, n representing the number of single base elements connected by a single strip-shaped metal busbar, ρ representing the resistivity of the metal material of the strip-shaped metal busbar, L₂，W₂，h₂Respectively showing the length, width and thickness of the base electrode strip-shaped metal bus;

after the emitter region is formed, the plane of the crystal is protected by a dielectric mask of silicon oxide, wherein ohmic contacts for the base and emitter regions are formed by photolithography and silicon oxide etching;

emitter and base strap metal busbars connecting the split base ohmic contact regions to the base regions with the metal bus bars and the split emitter ohmic contact regions to the emitter regions with the metal bus bars are formed by metal deposition, photolithography and then plasma metal etching.

The working principle of the technical scheme is as follows: the emitter region includes: forming an N-type emitter region of an electron conductivity type in the form of a continuous grid at a base region portion having a lower doping concentration by using photolithography and phosphorus impurity ion implantation and diffusion, a depth xjn of an emitter-base p-N junction being 11 μm to 14 μm; a base region not doped with the emitter impurity has a regular octagonal shape, and forms an ohmic contact window lattice with the base region;

the voltage drop V2 along the base strip metal busbar can be calculated by the following equation:

v2 ═ I2/n ((n +1)/2) × (L2/(W2 × h2)) formula (2)

Wherein:

i2 denotes the portion of the base current that a single strap metal busbar flows,

n denotes the number of individual base elements connected by a single strip-shaped metal busbar,

ρ represents the resistivity of the metal material of the strip-shaped metal bus bar,

l2, W2 and h2 respectively represent the length, width and thickness of the base strip-shaped metal bus;

after the emitter region is formed, the plane of the crystal is protected by a dielectric mask of silicon oxide, wherein ohmic contacts for the base and emitter regions are formed by photolithography and silicon oxide etching;

emitter and base strap metal busbars connecting the split base ohmic contact regions to the base regions with the metal bus bars and the split emitter ohmic contact regions to the emitter regions with the metal bus bars are formed by metal deposition, photolithography and then plasma metal etching.

The beneficial effects of the above technical scheme are that: forming an N-type emitter region of an electron conductivity type in the form of a continuous grid at a portion of the base region having a lower doping concentration using photolithography and phosphorus impurity ion implantation and diffusion, a depth xjn of the emitter-base p-N junction being 11 to 14 μm; a base region not doped with the emitter impurity has a regular octagonal shape, and forms an ohmic contact window lattice with the base region; the voltage drop along the base strip metal bus can be calculated by a formula; after the emitter region is formed, the plane of the crystal is protected by a dielectric mask of silicon oxide, wherein ohmic contacts for the base and emitter regions are formed by photolithography and silicon oxide etching; emitter and base strap metal busbars connecting the split base ohmic contact regions to the base regions with the metal bus bars and the split emitter ohmic contact regions to the emitter regions with the metal bus bars are formed by metal deposition, photolithography and then plasma metal etching.

In one embodiment, the method comprises the following steps:

emitter singles located at opposite edges of the transistor along the emitter strap metal bus will be subject to the same conditions in terms of bias voltage to the emitter-base p-n junction when the voltage drop values along the emitter and base strap metal buses are equal, as follows:

I₁/I₂＝W₁/W₂formula (3)

Wherein, I₁Representing the portion of emitter current, I, flowing by a single strap-like metal busbar₂The base current part flowing by the single strip-shaped metal bus is expressed, and the result obtained based on the formula (1) and the formula (2) is as follows: v₁＝V₂And L₂＝L₁，h₂＝h₁(ii) a And setting the width of the strip metal bus of the base according to the calculated ratio, so that the ratio of the bus width of the strip emitter to the width of the strip metal bus of the base is equal to the ratio of the maximum current of the emitter to the maximum current of the base.

The working principle of the technical scheme is as follows: with emitter individual elements located at opposite edges of the transistor along the emitter strap metal bus, the same condition will be placed on the bias voltage to the emitter-base p-n junction when the voltage drop values along the emitter and base strap metal buses are equal, which equation: I1/I2 ═ W1/W2 formula (3) where the results based on formula (1) and formula (2) are: v1 ═ V2, and L2 ═ L1, h2 ═ h 1; with the proposed design of the power bipolar transistor with continuous grid-shaped emitter, a lower voltage saturation value of the base-emitter junction is achieved on a smaller transistor than the prototype, a higher limit current value and a higher maximum dissipation current value than the prototype are obtained compared to the collector-emitter voltage saturation value of the prototype, a device with a significantly enlarged safe operating area compared to the prototype is produced, and a device with a much increased base-emitter saturation voltage and power density on a smaller transistor size than the prototype is obtained.

The beneficial effects of the above technical scheme are that: emitter individual elements, which may be located at opposite edges of the transistor along the emitter strip metal bus, when the voltage drop values along the emitter and base strip metal bus are equal, the same conditions will be imposed on the bias voltage to the emitter-base p-n junction, using the proposed design of a power bipolar transistor with a continuous grid-shaped emitter, lower voltage saturation values of the base-emitter junction are achieved on transistors smaller than the prototype, compared with the collector-emitter voltage saturation value of the prototype, the limit current value and the maximum dissipation current value which are higher than the prototype are obtained, the device with the safety working area which is obviously enlarged compared with the prototype is produced, a device with lower base-emitter saturation voltage and greatly increased power density than the prototype is obtained on a transistor with smaller size; the use of the proposed design of a power bipolar transistor with a continuous grid-shaped emitter allows to reach lower voltage saturation values of the base-emitter junction on transistors smaller than the prototype, obtaining higher limit current values and maximum dissipation current values than the prototype, compared to the collector-emitter voltage saturation values of the prototype, thus allowing to produce devices with a significantly enlarged safe operating area compared to the prototype, obtaining devices with a much lower base-emitter saturation voltage and power density than the prototype on transistors of smaller dimensions.

In one embodiment, the method comprises the following steps:

the emitter grid of the transistor structure has a periodic configuration, the number of the emitter strip-shaped metal buses is equal to that of the base strip-shaped metal buses, and the ratio of the emitter maximum current value Iemax to the base maximum current value Ibmax is calculated by the following formula:

Iemax/Ibmax＝W₁/W₂formula (4)

Wherein: iemax denotes the maximum emitter current value, Ibmax denotes the maximum base current value, W₁Width of emitter strip-shaped metal bus bar, W₂The width of the base strip-shaped metal bus is shown;

in the extreme operating mode of the transistor, the voltage drop along the strip-shaped metal bus of the emitter and base is compensated by selecting the width ratio between the emitter and the base by equation (4).

The working principle of the technical scheme is as follows: the emitter grid of the transistor structure has a periodic configuration, the number of the emitter strip-shaped metal buses is equal to that of the base strip-shaped metal buses, and the ratio of the emitter maximum current value Iemax to the base maximum current value Ibmax is calculated, wherein the formula is as follows: Iemax/Ibmax ═ W1/W2 formula (4) where: iemax represents the maximum current value of the emitter, Ibmax represents the maximum current value of the base, W1 represents the width of the strip-shaped metal bus of the emitter, and W2 represents the width of the strip-shaped metal bus of the base; in the extreme operating mode of the transistor in the proposed design, the voltage drop along the strip-shaped metal bus of the emitter and base can be compensated by choosing the width ratio between emitter and base by equation (4).

The beneficial effects of the above technical scheme are that: the emitter grid of the transistor structure has a periodic configuration, the number of the emitter strip-shaped metal buses is equal to that of the base strip-shaped metal buses, the ratio of the maximum emitter current value Iemax to the maximum base current value Ibmax is calculated, wherein Iemax represents the maximum emitter current value, Ibmax represents the maximum base current value, W1-the width of the emitter strip-shaped metal buses and W2-the width of the base strip-shaped metal buses; in the extreme operating mode of the transistor in the proposed design, the voltage drop along the strip-shaped metal bus of the emitter and base can be compensated by selecting the width ratio between the emitter and base by equation (4); the voltage drop along the strip-shaped metal bus of the emitter and the base can be supplemented through quantitative calculation, so that the voltage drop is more accurate.

As shown in fig. 4, the present invention provides an application of a bipolar power transistor having a mesh structure, including:

the silicon-based power bipolar transistor and integrated circuit, the metal insulator semiconductor field effect power device, the compound semiconductor power device and/or the power integrated circuit of the bipolar power transistor with the grid structure, which is applied to any one of the embodiments, comprises the following steps:

step one, establishing a device model required by product application according to the power, breakdown voltage, switching frequency, turn-off current and characteristic frequency of a device andor an integrated circuit, and establishing a database of the device andor the integrated circuit and the model;

determining materials and device types required to be adopted and corresponding process flows according to the models of the devices and/or the integrated circuits; the materials and devices used include: silicon-based or compound semiconductor materials, metal oxide semiconductor field effect (DMOS) power devices, insulated gate bipolar transistors and or electron mobility transistors (HEMTs);

thirdly, performing parameter test of full power and frequency range on the device designed and produced based on the device model, and determining links of the device which need to be improved; the improvement links comprise: the distribution of the breakdown electric field of low breakdown voltage and/or the distribution of current density;

step four, improving the overall or local structure of the device and the corresponding process flow according to the links and weak links of the device and/or the integrated circuit which need to be improved; the method comprises the following steps: for low breakdown voltage, a new device structure is designed by adopting the bipolar power transistor with the grid structure to change the field intensity distribution of the breakdown voltage;

and step five, feeding back the improved test and analysis results of the device to the device model, and establishing a new database.

The working principle of the technical scheme is as follows: establishing a device model required by product application according to the power, breakdown voltage, switching frequency, turn-off current and characteristic frequency of the device and/or the integrated circuit, and creating a database of the device and/or the integrated circuit and the model; determining the material and device type to be adopted and the corresponding process flow according to the device and/or integrated circuit model; the method comprises the following steps: silicon-based or compound semiconductor materials, metal oxide semiconductor field effect (DMOS) power devices, insulated gate bipolar transistors and/or electron mobility transistors (HEMTs) are adopted; carrying out parameter test of full power and frequency range on a device designed and produced based on a device model, and determining links of the device which need to be improved; the improvement links comprise: the distribution of the breakdown electric field of low breakdown voltage and/or the distribution of current density; improving the overall or local structure of the device and the corresponding process flow according to the links and weak links of the device and/or the integrated circuit which need to be improved; the method comprises the following steps: for low breakdown voltage, a new device structure is designed by adopting the bipolar power transistor with the grid structure to change the field intensity distribution of the breakdown voltage; and feeding back the improved test and analysis results of the device to the device model, and establishing a new database.

The beneficial effects of the above technical scheme are that: establishing a device model required by product application according to the power, breakdown voltage, switching frequency, turn-off current and characteristic frequency of the device and/or the integrated circuit, and creating a database of the device and/or the integrated circuit and the model; determining the material and device type to be adopted and the corresponding process flow according to the device and/or integrated circuit model; the method comprises the following steps: silicon-based or compound semiconductor materials, metal oxide semiconductor field effect (DMOS) power devices, insulated gate bipolar transistors and/or electron mobility transistors (HEMTs) are adopted; carrying out parameter test of full power and frequency range on a device designed and produced based on a device model, and determining links of the device which need to be improved; the improvement links comprise: the distribution of the breakdown electric field of low breakdown voltage and/or the distribution of current density; improving the overall or local structure of the device and the corresponding process flow according to the links and weak links of the device and/or the integrated circuit which need to be improved; the method comprises the following steps: for low breakdown voltage, a new device structure is designed by adopting the bipolar power transistor with the grid structure to change the field intensity distribution of the breakdown voltage; feeding back the improved test and analysis results of the device to the device model, and establishing a new database; thereby achieving the effect of enhancing the performance of the device.

While embodiments of the invention have been disclosed above, it is not limited to the applications set forth in the description and examples, which are fully applicable to various fields of endeavor for which the invention may be embodied, and further modifications may readily be effected therein by those skilled in the art without departing from the general concept as defined by the appended claims and their equivalents, and the invention is therefore not limited to the details shown and described herein.