阅读说明：本技术 一种多通道超结igbt器件 (Multi-channel super-junction IGBT device ) 是由 吴玉舟 李菲 李欣 刘铁川 禹久赢 于 2021-08-10 设计创作，主要内容包括：本发明提出了一种多通道超结IGBT器件,包括金属化集电极、P-衬底、位于P-衬底上方的第一N型外延层及位于所述第一N型外延层上方的第二N外延层；所述第二N外延层中至少包括第一虚拟MOS元胞单元与MOS元胞单元,所述第一虚拟MOS元胞单元包括通过反应离子刻蚀形成的沟槽、在所述沟槽内部设置的热生长的栅氧化层及位于栅氧化层内的淀积的重掺杂多晶硅。本发明公开的器件结构打破传统超结IGBT器件PN柱节距的元胞尺寸限制,可根据器件的应用要求增减顶层MOS元胞和虚拟MOS元胞以调节超结IGBT器件的栅输入电容,防止器件开启时的电流震荡,提高器件抗EMI能力。同时还具有调节饱和输出电流密度、正向导通压降、短路时间耐量的特点。(The invention provides a multi-channel super-junction IGBT device which comprises a metalized collector, a P-substrate, a first N-type epitaxial layer positioned above the P-substrate and a second N-type epitaxial layer positioned above the first N-type epitaxial layer; the second N epitaxial layer at least comprises a first virtual MOS unit cell and an MOS unit cell, wherein the first virtual MOS unit cell comprises a groove formed by reactive ion etching, a thermally grown gate oxide layer arranged in the groove and deposited heavily doped polycrystalline silicon positioned in the gate oxide layer. The device structure disclosed by the invention breaks the cell size limitation of the PN column pitch of the traditional super-junction IGBT device, and can increase or decrease the top layer MOS cell and the virtual MOS cell according to the application requirements of the device so as to adjust the gate input capacitance of the super-junction IGBT device, prevent the current oscillation when the device is started and improve the EMI resistance of the device. Meanwhile, the method also has the characteristics of regulating the saturation output current density, the forward conduction voltage drop and the short-circuit time tolerance.)

1. A multi-channel super-junction IGBT device comprises a metalized collector (1), a P-substrate (2), a first N-type epitaxial layer (3) positioned above the P-substrate (2) and a second N-type epitaxial layer (5) positioned above the first N-type epitaxial layer (3); a P column (4) is formed in the first N-type epitaxial layer (3) through multiple epitaxial injection or deep groove etching backfill process, the second N epitaxial layer (5) at least comprises two first virtual MOS unit cells (51) and MOS unit cells (50), wherein the first dummy MOS cell unit (51) has the same structure as the MOS cell unit (50), the first virtual MOS unit cell unit (51) comprises a groove (6) formed through reactive ion etching, a thermally grown gate oxide layer (7) arranged in the groove (6), deposited heavily doped polycrystalline silicon (8) positioned in the gate oxide layer (7), a P-type body region (9) formed through a self-alignment process, deposited boron-phosphorus-silicon glass (11) positioned above the P-type body region (9) and an emitter (12) positioned above the boron-phosphorus-silicon glass (11) and provided with a metalized upper surface;

the second N epitaxial layer (5) can further comprise a second virtual MOS cellular unit (52), the first virtual MOS cellular unit (51) and the MOS cellular unit (50) have the same structure, and the potential of the emitter (12) is not transmitted to the P-type body region (9) of the second virtual MOS cellular unit (52);

a plurality of mutually independent source regions (10) are arranged in a P-type body region (9) of the MOS unit cell (50).

2. The multi-channel super junction IGBT device according to claim 1, wherein the number and the proportion of the first virtual MOS cell unit (51), the second virtual MOS cell unit (52) and the MOS cell unit (50) in the second N epitaxial layer (5) are adjusted according to application requirements, wherein at least one MOS cell unit (50) is provided, and all MOS cell units (50) can be provided.

3. The multi-channel superjunction IGBT device according to claim 1, wherein the resistivity of the second N epitaxial layer (5) is greater than the resistivity of the first N epitaxial layer (3), and the resistivity of the second N epitaxial layer (5) is in the range of 4-40 Ω -cm.

4. A multi-channel superjunction IGBT device according to claim 1, characterized in that the thickness of the second N epitaxial layer (5) is in the range of 4-40 μm.

5. The multi-channel super-junction IGBT device according to claim 1, characterized in that the P-pillars (4) are formed by deep trench etching and silicon backfill process or multiple epitaxy and ion implantation and formed by high temperature annealing.

6. The multi-channel super-junction IGBT device according to claim 1, characterized in that the P-pillars (4) are not in contact with the P-type body regions (9) and the trenches (6).

7. A multi-channel superjunction IGBT device according to claim 1, characterized in that the upper layer of the metalized collector (1) forms by epitaxy a field stop layer with a resistivity less than the resistivity of the first N-type epitaxial layer (3), the field stop layer being 10-40 μm thick.

8. The multi-channel super-junction IGBT device according to claims 1-8, characterized in that the scheme of the invention is applied to a P-channel multi-channel super-junction IGBT device.

9. The multi-channel super-junction IGBT device according to claims 1 to 9, wherein the semiconductor material in the IGBT device can be bulk silicon, silicon carbide, gallium arsenide, indium phosphide or silicon germanium.

Technical Field

The invention belongs to the technical field of power semiconductor devices, and particularly relates to a multi-channel super-junction IGBT device.

Background

A conventional super junction igbt (insulated Gate Bipolar transistor) device structure in the prior art is shown in fig. 1, and includes a metalized collector 1, a P-type substrate 2, a first N-type epitaxial layer 3 located above the P-type substrate 2, a P pillar 4 formed in the first N-type epitaxial layer by a deep trench etching backfill process, a second N-type epitaxial layer 5 located above the first N-type epitaxial layer 3 and the P pillar 4, and one and only one MOS cell 50 in the second N-type epitaxial layer 5, where the MOS cell 50 includes a trench 6 formed by etching, a thermally grown Gate oxide layer 7, deposited heavily doped polysilicon 8, and a P-type body region 9 formed by a self-alignment process, where the P-type body region 9 is provided with a N + source region 10, a deposited borophosphosilicate glass 11, and an upper surface metalized emitter 12 that are partially independent of each other.

The super junction IGBT device is a novel power semiconductor device with PN columns arranged repeatedly added in an epitaxial layer on the basis of a traditional IGBT device structure. The formation of the PN column has similar effect to the super junction MOS device in optimizing parameters such as device withstand voltage, forward conduction voltage drop and the like. The PN column is introduced to ensure that the super junction IGBT device is in forward voltage withstanding except Pbody-N^-Outside the longitudinal electric field of the Epi junction, mutual depletion of the PN columns generates a transverse electric field, triangular electric field distribution of the traditional IGBT device is modulated to be similar to rectangular distribution, and the voltage resistance of the super-junction IGBT device is greatly improved. On the premise of ensuring a certain breakdown voltage of the device, the concentration of the N-Epi layer can be obviously increased, so that the forward conduction voltage drop is obviously reduced, and the super-junction IGBT device is helped to obviously reduce conduction loss in application. Under the same current specification, the area of the super-junction IGBT device can be greatly reduced, and the chip cost is reduced.

The super-junction structure in the super-junction IGBT device is formed by following the manufacturing process of a super-junction MOS, and two manufacturing methods are mainly adopted: firstly, forming a super junction structure through multiple times of epitaxial implantation; and secondly, the etching and the filling of the deep groove are completed. Both manufacturing methods are currently in common use and are classified into different generation products according to the width (pitch) of the PN column, for example, the pitch of the British flying C3 process is 16 μm, the pitch of the C6 and P6 processes is 12 μm, the pitch of the C7 and P7 processes is 5.5 μm, and each pitch only contains one MOS cellular structure.

The super junction IGBT device has the advantages that the chip area is smaller and the current density is larger due to the excellent electrical property of the super junction IGBT device. Smaller chip area leads to littleer gate input capacitance, and when using and surpassing knot IGBT device and replace traditional IGBT device, its stronger drive current of drive chip can lead to surpassing and surpassing the knot IGBT device and easily forming the electric current when opening and vibrate, produce the EMI problem, lead to the device to burn out even. Therefore, when the super junction IGBT device is applied, the traditional IGBT device cannot be directly replaced, peripheral circuits need to be adjusted or a driving chip with smaller driving current needs to be replaced, and system cost and complexity of application solution providers are indirectly increased. Meanwhile, the improvement of the current density of the IGBT device is also a key direction for the development of the IGBT technology.

Disclosure of Invention

In view of the above, the technical problem to be solved by the present invention is to provide a multi-channel super-junction IGBT device, which can adjust the gate input capacitance of the super-junction IGBT device without changing the device process complexity and affecting the device breakdown voltage, prevent the current oscillation when the device is turned on, enhance the EMI resistance of the device, and can directly replace the conventional IGBT device when applied. Meanwhile, the method also has the characteristics of regulating the saturation output current density, the forward conduction voltage drop and the short-circuit time tolerance.

The technical scheme of the invention is as follows: a multi-channel superjunction IGBT device, comprising: the device comprises a metalized collector, a P-substrate, a first N-type epitaxial layer positioned above the P-substrate and a second N-type epitaxial layer positioned above the first N-type epitaxial layer; the first N-type epitaxial layer is internally provided with a P column formed by multiple times of epitaxial injection or deep groove etching backfill process, the second N-type epitaxial layer at least comprises two first virtual MOS cell units and MOS cell units, the first virtual MOS cell units and the MOS cell units have the same structure, each first virtual MOS cell unit comprises a groove formed by reactive ion etching, a thermally grown gate oxide layer arranged in the groove, deposited heavily doped polycrystalline silicon positioned in the gate oxide layer, a P-type body area formed by a self-alignment process, deposited boron-phosphorus-silicon glass positioned above the P-type body area and an emitting electrode positioned above the boron-phosphorus-silicon glass and provided with metalized upper surface;

the second N epitaxial layer may further include a second virtual MOS cell unit, the second virtual MOS cell unit and the MOS cell unit have the same structure, and a potential of the emitter is not received in the P-type body region of the second virtual MOS cell unit;

a plurality of mutually independent source regions are arranged in the P-type body region of the MOS unit cell.

Preferably, the number and the proportion of the first virtual MOS cell unit, the second virtual MOS cell unit, and the MOS cell unit are adjusted according to application requirements in the second N epitaxial layer, wherein at least one MOS cell unit is provided, and all MOS cell units may be provided.

Preferably, the resistivity of the second N epitaxial layer is greater than that of the first N epitaxial layer, and the resistivity of the second N epitaxial layer ranges from 4 Ω · cm to 40 Ω · cm.

Preferably, the thickness of the second N epitaxial layer is in the range of 4-40 μm.

Preferably, the P column is formed by deep trench etching and silicon backfill processes or multiple times of epitaxy and ion implantation and formed by high-temperature annealing.

Preferably, the P-pillar is not in contact with the P-type body region and the trench.

Preferably, the upper layer of the metalized collector forms a field stop layer through epitaxy, the resistivity of the field stop layer is smaller than that of the first N-type epitaxial layer, and the thickness of the field stop layer is 10-40 μm.

Preferably, the scheme of the invention is suitable for a P-channel multi-channel super-junction IGBT device.

Preferably, the semiconductor material in the IGBT device may be bulk silicon, silicon carbide, gallium arsenide, indium phosphide or silicon germanium.

The multi-channel super-junction IGBT device has the beneficial effects that the gate input capacitance of the super-junction IGBT device can be adjusted by adjusting the number of the first virtual MOS cellular unit, the MOS cellular unit and the second virtual MOS cellular unit of the top structure of the device, and meanwhile, the multi-channel super-junction IGBT device has the advantages of adjusting the saturation output current density of the device, the forward conduction voltage drop, the short-circuit time tolerance and the like. The first virtual MOS unit cell is added to increase the grid input capacitance, prevent the current oscillation when the device is started and improve the anti-EMI capability of the device. The third virtual MOS unit cell is added, so that an electron accumulation region can be formed below a P-type body region when the device is conducted in the forward direction, the concentration distribution of current carriers in the device is modulated to be closer to a PIN diode, a current carrier injection enhancement effect is formed, the forward conduction voltage drop of the device is reduced, and the conduction loss of the device is reduced. According to the simulation data, the grid input capacitance of the super-junction IGBT device can be increased by multiple by adding the first virtual MOS unit cell. The forward conduction voltage drop can be reduced by more than 10% by adding 2 second virtual MOS unit cells. In addition, the breakdown voltage and the short-circuit tolerance characteristic of the device are not affected by the increase of the first virtual MOS unit cell and the second virtual MOS unit cell. The MOS cellular unit provides base current of a parasitic PNP transistor for the super-junction IGBT device, and the increase of the MOS cellular unit can improve electron hole density of the first N-type epitaxial layer, so that saturation output current density of the device is increased, forward conduction voltage drop is reduced, and conduction loss is reduced.

Drawings

Fig. 1 is a schematic structural diagram of a conventional super junction IGBT device embodiment of the prior art;

fig. 2 is a schematic structural diagram of a multi-channel super junction IGBT device according to a first embodiment of the present invention;

fig. 3 is a schematic structural diagram of a multi-channel super junction IGBT device according to a second embodiment of the present invention;

fig. 4 is a schematic structural diagram of a multi-channel super junction IGBT device according to a third embodiment of the present invention;

fig. 5 is a schematic structural diagram of a multi-channel super junction IGBT device according to a fourth embodiment of the present invention;

FIG. 6 is a flow chart of the key steps in the first embodiment of the present invention;

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be described in detail below with reference to the accompanying drawings in the embodiments of the present invention. It should be understood that the embodiments described are only a part of the embodiments of the present invention, and not all embodiments, and all other embodiments obtained by those of ordinary skill in the art without any inventive work based on the embodiments of the present invention are within the scope of the present invention as described below with reference to the attached drawings.

It is to be understood that the terms "having," "including," and "comprising," as used herein, do not preclude the presence or addition of one or more other elements or groups thereof. Meanwhile, in order to clearly illustrate the embodiments of the present invention, the schematic diagrams listed in the drawings of the specification enlarge the thicknesses of the layers and regions of the present invention, and the sizes of the listed figures do not represent actual sizes; the drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure. The examples listed in the specification should not be limited to the specific shapes of the regions shown in the drawings of the specification, but include the resulting shapes such as deviations due to production and the like.

As shown in fig. 2, a multi-channel super-junction IGBT device according to a first embodiment of the present invention includes a metalized collector 1, a P-substrate 2, a first N-type epitaxial layer 3 located above the P-substrate 2, and a second N-type epitaxial layer 5 located above the first N-type epitaxial layer 3; the P-pillar 4 is formed in the first N-type epitaxial layer 3 through multiple epitaxial injection or deep trench etching backfill process, the second N-type epitaxial layer 5 at least comprises two first virtual MOS cell units 51 and MOS cell units 50, the first virtual MOS cell units (51) and the MOS cell units (50) have the same structure, each first virtual MOS cell unit (51) comprises a groove (6) formed through reactive ion etching, a thermally grown gate oxide layer (7) arranged in the groove (6) and deposited heavily doped polysilicon (8) positioned in the gate oxide layer (7), a P-type body region (9) formed through a self-alignment process, deposited borophosphosilicate glass (11) positioned above the P-type body region (9), and an emitter (12) positioned above the borophosphosilicate glass (11) and provided with metalized upper surface;

the second N epitaxial layer 5 may further include a second dummy MOS cell unit 52, the first dummy MOS cell unit 51 and the MOS cell unit 50 have the same structure, and the P-type body region 9 of the second dummy MOS cell unit 52 does not have the potential of the emitter 12;

a plurality of source regions 10 independent of each other are provided in the P-type body region 9 of the MOS unit cell 50.

Further, the number and the proportion of the second virtual MOS cell unit 52, the first virtual MOS cell unit 51, and the MOS cell unit 50 are adjusted according to the application requirement in the second N epitaxial layer 5, wherein at least one MOS cell unit 50, and all MOS cell units 50 may be MOS cell units 50.

Further, the resistivity of the second N epitaxial layer 5 is greater than that of the first N epitaxial layer 3, and the resistivity range of the second N epitaxial layer 5 is 4-40 Ω · cm.

Further, the thickness of the second N epitaxial layer 5 is in the range of 4-40 μm.

The P-pillar 4 is further characterized by being formed by a deep trench etch and silicon backfill process, multiple epitaxy or ion implantation and formed by a high temperature annealing process.

Further, there is no contact between the P-pillars 4 and the P-type body regions 9 and trenches 6.

Further, a field stop layer is formed on the upper layer of the metalized collector 1 through epitaxy, the resistivity of the field stop layer is smaller than that of the first N-type epitaxial layer 3, and the thickness of the field stop layer is 10-40 μm.

Furthermore, the scheme of the invention is suitable for a P-channel multi-channel super-junction IGBT device.

Further, the semiconductor material in the IGBT device may be bulk silicon, silicon carbide, gallium arsenide, indium phosphide or silicon germanium.

The super-junction IGBT device has the advantages that the number of the virtual MOS cells 51 and the number of the MOS cells 50 are increased, the limitation of the process pitch adopted by the device is avoided, the super-junction voltage-resistant part of the super-junction IGBT device is separated from the top-layer MOS part, and the super-junction voltage-resistant part and the top-layer MOS part can be independently designed without being influenced.

The invention has the second advantage that the main process flow of the super junction IGBT device is not changed by adding the first virtual MOS cellular unit 51, and the scheme has strong operability.

The third advantage of the invention is that the number of the first virtual MOS unit cells 51 can be flexibly increased according to the application requirements, and the scheme can monotonically increase the gate input capacitance of the super-junction IGBT device, thereby avoiding the problems of starting current oscillation and EMI of the super-junction IGBT device. And meanwhile, the breakdown voltage and the short-circuit tolerance capability of the device are not degraded. Besides the virtual MOS unit cell, the MOS unit cell 50 can be added, so that the saturation output current density of the device can be obviously improved, the conductance modulation state effect can be improved, and the forward conduction voltage drop of the device can be reduced.

Fig. 3 is a schematic structural diagram of a multi-channel super-junction IGBT device according to the present invention, wherein an emitter contact hole is not opened in the second virtual MOS cell unit 52, so that the potential of the P-type body region 9 is floating, which is beneficial to forming an electron accumulation layer below the P-type body region 9 when the device is forward conducted, and reducing the forward conduction voltage drop;

fig. 4 is a schematic structural diagram of a multi-channel super-junction IGBT device according to the first embodiment of the present invention, in which a super-junction portion may be formed by multi-layer epitaxy and multiple ion implantation, and the principle is the same as that of the first embodiment of fig. 2.

Fig. 5 is a schematic structural diagram of a multi-channel super-junction IGBT device according to a second embodiment of the present invention, in which a super-junction portion may be formed by multi-layer epitaxy and multiple ion implantation, and the principle is the same as that of the second embodiment of fig. 3.

FIG. 6 is a flow chart of the key steps in the first embodiment of the present invention. Fig. 6-1 is an epitaxial Wafer used in Wafer start, and includes a high-resistance P-type substrate 2 and a first N-type epitaxial layer 3; FIG. 6-2 is a super junction structure of a super junction IGBT device formed by forming a P-pillar 3 by deep trench reactive ion etching and silicon backfill processes; fig. 6-3 shows that the second N-type epitaxial layer 5 is formed by high temperature epitaxy, and the key point is that the resistivity of the second N-type epitaxial layer is higher than that of the first N-type epitaxial layer, so that the walk out phenomenon in the test process is avoided; FIG. 6-4 illustrates the formation of trenches 6 by reactive ion etching using a Hard mask and carrier storage layer implantation; fig. 6-5 are thermal growth of gate oxide layer 7 by dry oxidation; 6-6 is depositing in-situ doped polysilicon and etching to form gate 8; FIGS. 6-7 illustrate the formation of P-type body region 9 by self-aligned ion implantation and high temperature drive-in; fig. 6-8 illustrate the formation of emitter region 10 by lithographic implantation, the implanted region of the emitter region separating dummy MOS cell 51 and MOS cell 50; 6-9 is depositing boron phosphorus silicon glass 11, high temperature reflow, performing contact hole lithography and etching, etching 3000-5000A thick silicon, distinguishing the dummy cells 51 and 52 if the contact hole is opened, and then depositing a metal layer to form the emitter 12; and then, turning over the wafer, thinning the device, implanting P-type ions to form ohmic contact, depositing a Ti/NiV/Ag metal layer to form a collector 1, and finally forming the first embodiment of the invention shown in FIG. 2.

Fig. 6 depicts a manufacturing process of key steps of an N-channel super junction IGBT device, and the scheme of the present invention is also applicable to a P-channel super junction IGBT device. The semiconductor material can adopt bulk silicon, silicon carbide, gallium arsenide, indium phosphide or silicon germanium.