阅读说明：本技术 一种双向晶闸管及其制造方法 (Bidirectional thyristor and manufacturing method thereof ) 是由 王政英 姚震洋 朱为为 李勇 操国宏 王东东 郭润庆 王亚飞 张西应 高军 银登 于 2019-11-13 设计创作，主要内容包括：本发明提供一种双向晶闸管及其制造方法,所述双向晶闸管包括：硅单晶,所述硅单晶被隔离区分割为第一区域和第二区域,所述第一区域和所述第二区域之间通过隔离区隔离；主晶闸管,位于所述第一区域,包括第一阴极、第一门极和第一阳极,所述第一阴极和所述第一门极位于所述第一区域的上表面,所述第一阳极位于所述第一区域的下表面；集成BOD晶闸管,位于所述第二区域,包括第二阴极和第二阳极,所述第二阳极位于所述第二区域的上表面,所述第二阴极位于所述第二区域的下表面。本发明的主晶闸管和集成BOD晶闸管集成在一片芯片上,二者之间通过隔离区间隔开,其中过压保护功能通过集成BOD晶闸管实现,该集成BOD晶闸管的转折电压通过挖槽尺寸进行控制。(The invention provides a bidirectional thyristor and a manufacturing method thereof, wherein the bidirectional thyristor comprises: a silicon single crystal divided by an isolation region into a first region and a second region separated by the isolation region; the main thyristor is positioned in the first area and comprises a first cathode, a first gate and a first anode, the first cathode and the first gate are positioned on the upper surface of the first area, and the first anode is positioned on the lower surface of the first area; an integrated BOD thyristor located in the second zone and comprising a second cathode and a second anode, the second anode being located on the upper surface of the second zone and the second cathode being located on the lower surface of the second zone. The main thyristor and the integrated BOD thyristor are integrated on a chip and are separated by an isolation area, wherein the overvoltage protection function is realized by the integrated BOD thyristor, and the turning voltage of the integrated BOD thyristor is controlled by the size of the groove.)

1. A method for manufacturing a bidirectional thyristor, comprising the steps of:

s1: selecting an N-type silicon single crystal, and respectively cleaning the upper surface and the lower surface of the silicon single crystal;

s2: respectively performing first aluminum impurity diffusion on the upper surface and the lower surface of the silicon single crystal;

s3: forming an isolation region in the silicon single crystal, the isolation region penetrating the upper surface and the lower surface to divide the silicon single crystal into a first region and a second region;

s4: removing all aluminum impurities on the upper surface of the silicon single crystal, and etching the lower surface of the silicon single crystal to form a second circular groove, wherein the second circular groove is a circular groove with the radius of R and is positioned in the second region;

s5: carrying out aluminum impurity oxidation promotion on the lower surface to form a P1-region;

s6: performing secondary aluminum impurity or gallium impurity diffusion on the upper surface and the lower surface;

s7: etching the second region of the lower surface of the silicon single crystal to form a first circular ring and a second circular ring, wherein the outer diameter of the first circular ring is smaller than R, and the inner diameter of the second circular ring is larger than R;

s8: performing double-sided aluminum impurity or gallium impurity drive to form a P2 region on the upper surface and a P1 region on the lower surface;

s9: selective phosphorus diffusion is respectively carried out on the first region of the upper surface and the second region of the lower surface to form an N + region;

s10: performing selective boron diffusion on the upper surface and the lower surface to form a P + region;

s11, evaporating aluminum metal on the upper surface and the lower surface, photoetching, and respectively leading out a first cathode, a first gate pole, a first anode, a second cathode and a second anode; wherein said first cathode and said first gate are located on a first region of said upper surface, said second anode is located on a second region of said upper surface and said second cathode is located on a second region of said lower surface, and said first anode is located on said first region of said lower surface.

2. The method of manufacturing a triac as claimed in claim 1 wherein the step of forming isolation regions in said silicon single crystal in step S3 includes:

forming an isolation region by removing aluminum impurities or gallium impurities in the respective regions of the upper surface and the lower surface; or by irradiating respective areas of the upper and lower surfaces.

3. The manufacturing method of a triac as claimed in claim 2, wherein when the isolation region is formed by removing aluminum impurity or gallium impurity in the respective regions of the upper surface and the lower surface, the width of the isolation region formed is 0.3-0.6 mm; when the isolation region is formed by irradiating the corresponding regions of the upper surface and the lower surface, the width of the formed isolation region is 3-5mm, the irradiation energy is 12MeV, and the irradiation dose is 1000-3000 Gray.

4. The method of manufacturing a triac according to claim 2, wherein for the step of forming isolation regions by removing aluminum impurities or gallium impurities in respective regions of said upper surface and said lower surface, further comprising: boron diffusion is performed within the isolation region to limit surface electric field strength.

5. The method of claim 1, wherein the first gate is located at a center of the triac.

6. The method of manufacturing a triac as claimed in claim 1 wherein a depth of the P region formed at the upper surface is smaller than a depth of the P region formed at the lower surface.

7. The method of claim 6, wherein the P region formed on the lower surface is formed by first aluminum impurity diffusion and second aluminum impurity or gallium impurity diffusion, and is formed by proceeding separately; the P area formed on the upper surface is formed by corroding the upper surface after the first aluminum impurity diffusion, removing the surface aluminum impurity layer and pushing after the second aluminum impurity or gallium impurity diffusion; wherein the upper surface forms a P region that does not include the P2-region.

8. The method of manufacturing a triac as claimed in claim 1 wherein said step S7 further includes adjusting a breakover voltage of the thyristor formed in said second region by adjusting a size of said first ring.

9. A method of manufacturing a triac as claimed in claim 1 or 2 further comprising the steps of:

s12, carrying out table top modeling on the chip, wherein the modeling structure is a double positive angle or double negative angle structure, the angle of the double positive angle is 20-50 degrees, and the angle of the double negative angle is 10-20 degrees and 1.5-2.5 degrees respectively;

s13: and carrying out mesa corrosion, edge passivation and protection on the mesa of the chip.

10. A triac, comprising:

a silicon single crystal divided by an isolation region into a first region and a second region separated by the isolation region;

the main thyristor is positioned in the first area and comprises a first cathode, a first gate and a first anode, the first cathode and the first gate are positioned on the upper surface of the first area, and the first anode is positioned on the lower surface of the first area;

an integrated BOD thyristor located in the second zone and comprising a second cathode and a second anode, the second anode being located on the upper surface of the second zone and the second cathode being located on the lower surface of the second zone.

Technical Field

The invention relates to the technical field of semiconductor devices, in particular to a manufacturing method of a bidirectional thyristor.

Background

In the flexible direct current transmission engineering, in order to protect the parallel-connected IGBTs, a bypass thyristor with a voltage resistance not lower than that of the IGBTs is generally required to be equipped, as shown in fig. 1. Under the short-circuit fault of a direct current polar line of a flexible direct current system, a Fast Recovery Diode (FRD) bears short-circuit current for a long time, bypass thyristors are needed for shunting protection, and the whole converter valve is prevented from being burnt out due to overheating. Therefore, under the working condition, the bypass thyristor is required to be capable of achieving forward fast conduction at a lower FRD pipe voltage drop. In addition, the effect that the bypass thyristor needs overvoltage breakdown is definitely proposed in engineering, namely when the voltage (reverse voltage) at two ends of the thyristor is higher than the withstand voltage of the IGBT, the thyristor can realize self-conduction, and the situation that the voltage at two ends of a circuit is continuously increased to cause the failure of an IGBT device or the formation of high-voltage impact on a rear-end capacitor is avoided. After the thyristor is self-conducted, a certain current needs to be continuously passed through.

Based on the above requirements, how to provide a manufacturing process of a bidirectional thyristor to satisfy the low voltage turn-on function and the reverse overvoltage protection function becomes a problem to be solved by those skilled in the art.

Disclosure of Invention

The invention aims to provide a manufacturing method of a bidirectional thyristor with overvoltage protection and bidirectional current capacity.

In order to achieve the above object, the present invention provides a method for manufacturing a bidirectional thyristor, comprising the steps of:

s1: selecting an N-type silicon single crystal, and respectively cleaning the upper surface and the lower surface of the silicon single crystal;

s2: respectively performing first aluminum impurity diffusion on the upper surface and the lower surface of the silicon single crystal;

s3: forming an isolation region in the silicon single crystal, the isolation region penetrating the upper surface and the lower surface to divide the silicon single crystal into a first region and a second region;

s4: removing all aluminum impurities on the upper surface of the silicon single crystal, and etching the lower surface of the silicon single crystal to form a second circular groove, wherein the second circular groove is a circular groove with the radius of R and is positioned in the second region;

s5: carrying out aluminum impurity oxidation promotion on the lower surface to form a P1-region;

s6: performing secondary aluminum impurity or gallium impurity diffusion on the upper surface and the lower surface;

s7: etching the second region of the lower surface of the silicon single crystal to form a first circular ring and a second circular ring, wherein the outer diameter of the first circular ring is smaller than R, and the inner diameter of the second circular ring is larger than R;

s8: performing double-sided aluminum impurity or gallium impurity drive to form a P2 region on the upper surface and a P1 region on the lower surface;

s9: selective phosphorus diffusion is respectively carried out on the first region of the upper surface and the second region of the lower surface to form an N + region;

s10: performing selective boron diffusion on the upper surface and the lower surface to form a P + region;

s11, evaporating aluminum metal on the upper surface and the lower surface, photoetching, and respectively leading out a first cathode, a first gate pole, a first anode, a second cathode and a second anode; wherein said first cathode and said first gate are located on a first region of said upper surface, said second anode is located on a second region of said upper surface and said second cathode is located on a second region of said lower surface, and said first anode is located on said first region of said lower surface.

According to the method for manufacturing a triac provided by the present invention, the step of forming an isolation region in the silicon single crystal in step S3 includes:

forming an isolation region by removing aluminum impurities in the respective regions of the upper surface and the lower surface; or

Isolation regions are formed by irradiating respective regions of the upper surface and the lower surface.

According to the manufacturing method of the bidirectional thyristor provided by the invention, when the isolation region is formed by removing the aluminum impurities in the corresponding regions of the upper surface and the lower surface, the width of the formed isolation region is 0.3-0.6 mm; when the isolation region is formed by irradiating the corresponding regions of the upper surface and the lower surface, the width of the formed isolation region is 3-5mm, the irradiation energy is 12MeV, and the irradiation dose is 1000-3000 Gray.

According to the method for manufacturing a triac provided by the present invention, for the step of forming the isolation region by removing the aluminum impurity in the corresponding region of the upper surface and the lower surface, the method further comprises: boron diffusion is performed within the isolation region to limit surface electric field strength.

According to the manufacturing method of the bidirectional thyristor provided by the invention, the first gate pole is positioned at the circle center of the bidirectional thyristor.

According to the method for manufacturing the bidirectional thyristor provided by the invention, the depth of the P region formed on the upper surface is smaller than that of the P region formed on the lower surface.

According to the manufacturing method of the bidirectional thyristor provided by the invention, the P region formed on the lower surface is formed by first aluminum impurity diffusion and second aluminum impurity or gallium impurity diffusion which are respectively carried out; the P area formed on the upper surface is formed by corroding the upper surface after the first aluminum impurity diffusion, removing the surface aluminum impurity layer and pushing after the second aluminum impurity or gallium impurity diffusion; wherein the upper surface forms a P region that does not include the P2-region.

According to the method for manufacturing a triac provided by the present invention, the step S7 further includes adjusting a breakover voltage of the thyristor formed in the second region by adjusting the first ring.

According to the manufacturing method of the bidirectional thyristor provided by the invention, the depth of the N + region formed in the step S9 is 10-20um, and the impurity concentration is (2.0-5.0) x 10²⁰/cm³(ii) a The impurity concentration of the P + region formed in said step S10 is (1.0-7.0) x 10²⁰/cm³。

According to the manufacturing method of the bidirectional thyristor provided by the invention, the thickness of the aluminum layer of the first gate electrode is 5-10um, and the thickness of the aluminum layer of the first anode, the first cathode, the second anode and the second cathode is 20-30 um.

The manufacturing method of the bidirectional thyristor provided by the invention further comprises the following steps:

s12, carrying out table top modeling on the chip, wherein the modeling structure is a double positive angle or double negative angle structure, the angle of the double positive angle is 20-50 degrees, and the angle of the double negative angle is 10-20 degrees and 1.5-2.5 degrees respectively;

s13: and carrying out mesa corrosion, edge passivation and protection on the mesa of the chip.

To achieve the above object, the present invention also provides a bidirectional thyristor, including:

a silicon single crystal divided by an isolation region into a first region and a second region separated by the isolation region;

the main thyristor is positioned in the first area and comprises a first cathode, a first gate and a first anode, the first cathode and the first gate are positioned on the upper surface of the first area, and the first anode is positioned on the lower surface of the first area;

an integrated BOD thyristor located in the second zone and comprising a second cathode and a second anode, the second anode being located on the upper surface of the second zone and the second cathode being located on the lower surface of the second zone.

The bidirectional thyristor and the manufacturing method thereof integrate a main thyristor and an integrated BOD (biological-over-diode) thyristor on a chip, the main thyristor and the integrated BOD thyristor are separated by an isolation area, wherein the overvoltage protection function is realized by the integrated BOD thyristor, and the turning voltage of the integrated BOD thyristor can be controlled by the size of a groove.

Drawings

FIG. 1 is a schematic diagram of a conventional IGBT parallel protection circuit;

fig. 2 is a schematic diagram of step S1 in the method of manufacturing the triac according to the present invention;

fig. 3 is a schematic diagram of step S2 in the method of manufacturing the triac according to the present invention;

fig. 4 is a schematic view of steps S3 and S4 in the method of manufacturing the triac of the present invention;

fig. 5 is a schematic diagram of step S5 in the method of manufacturing the triac of the present invention;

fig. 6 is a schematic diagram of step S6 in the method of manufacturing the triac of the present invention;

fig. 7 is a schematic diagram of step S7 in the method of manufacturing the triac of the present invention;

fig. 8 is a schematic diagram of step S8 in the method of manufacturing the triac of the present invention;

fig. 9 is a schematic diagram of step S9 in the method of manufacturing the triac of the present invention;

fig. 10 is a schematic view of step S10 in the method of manufacturing the triac of the present invention;

fig. 11 is a schematic view of step S11 in the method of manufacturing the triac of the present invention;

fig. 12A and 12B are a front structure view and a back structure view of the triac of the present invention, respectively;

fig. 13A and 13B are a dual positive angle structure chip mesa configuration and a dual negative angle structure chip mesa configuration of the bidirectional thyristor according to the present invention, respectively.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The manufacturing method of the bidirectional thyristor provided by the invention can obtain the bidirectional thyristor which not only has bidirectional circulation capability, but also has reverse overvoltage protection function. The bidirectional thyristor integrates the main thyristor and the integrated BOD thyristor on a chip, and the main thyristor and the integrated BOD thyristor are separated by an isolation area. The reverse overvoltage protection function is realized by the integrated BOD thyristor, and the turning voltage of the integrated BOD thyristor is controlled by the size of the groove. The forward withstand voltage of the main thyristor is the conduction voltage drop of the FRD, so the thyristor withstand voltage is made into asymmetric withstand voltage.

Example one

Referring to fig. 1, the present embodiment provides a method for manufacturing a bidirectional thyristor, which specifically includes the following steps:

s1: selecting an N-type silicon single crystal, and respectively cleaning the upper surface and the lower surface of the silicon single crystal, as shown in fig. 2. The method selects the N-type silicon single crystal with the thickness of 800-1000 mu m, the resistivity of 180-230 omega cm and the crystal orientation of (100) or (111), and the two sides of the silicon wafer are treated by adopting a chemical corrosion method.

S2: aluminum impurity diffusion was performed on the upper and lower surfaces of the silicon single crystal, respectively, with a surface resistance of 40-60mV/mA, as shown in FIG. 3.

S3: an isolation region is formed in the silicon single crystal, the isolation region penetrating the upper surface and the lower surface to divide the silicon single crystal into a first sector region and a second sector region, the area of the first sector region being larger than the area of the second sector region, as shown in fig. 4. Specifically, the main thyristor is formed in the first sector area, and the integrated BOD thyristor is formed in the second sector area.

It should be noted that although the area of the first sector is larger than the area of the second sector in the embodiment of fig. 4, in practical application, the present invention does not limit the area relationship between the first sector and the second sector, and the area of the first sector may be equal to or smaller than the area of the second sector. Further, the shapes of the first and second sectors are also presented for illustration purposes only and are not intended to be limiting. In particular, the shape may be other regular shapes or irregular shapes besides the fan shape.

Wherein the step of forming an isolation region in the silicon single crystal of the present invention comprises: forming an isolation region by removing aluminum impurities in the respective regions of the upper surface and the lower surface; or by irradiating respective areas of the upper and lower surfaces.

S4: and removing all aluminum impurities on the upper surface of the silicon single crystal, and etching the lower surface of the silicon single crystal to form a second circular groove to remove the aluminum impurities. The second circular groove is a circular groove with a radius R in the second sector, as shown in fig. 4.

S5: an aluminum impurity oxidation drive is performed on the lower surface to form a P1-region, as shown in fig. 5. The depth of the P1-region was 85-100um, the impurity concentration was (2.0-8.0) x 10¹⁴/cm³。

S6: high concentration diffusion of aluminum impurities or gallium impurities is performed on the upper surface and the lower surface, and the surface resistance is 8-15mV/mA, as shown in FIG. 6.

S7: etching is performed in the second sector region of the lower surface of the silicon single crystal to form a first ring with a width R and a second ring with a width R', wherein the outer diameter of the first ring is smaller than R, and the inner diameter of the second ring is larger than R, as shown in FIG. 7.

S8: carrying out double-sided aluminum impurity propulsion on the upper surfaceForming a P2 region and a P1 region in the lower surface, as shown in fig. 8. Wherein the depth of the P1 region and the P2 region is 30-50um, and the impurity concentration is (2.0-8.0) x 10¹⁶/cm³。

S9: phosphorus diffusion is performed on the first sector of the upper surface and the second sector of the lower surface, respectively, to form N + regions, as shown in fig. 9. The depth of the N + region is 10-20um, the impurity concentration is (2.0-5.0) x 10²⁰/cm³。

S10: selective boron diffusion is performed on the upper surface and the lower surface, so that a P + region is formed after boron diffusion is performed on a P1 region of the main thyristor, a P2 region of the integrated BOD thyristor, an N + layer short-circuit region of the main thyristor, an N + layer short-circuit region of the integrated BOD thyristor portion, a BOD trenching middle portion and an isolation region, as shown in fig. 10. The surface impurity concentration of the P + region is (1.0-7.0) x 10²⁰/cm³。

S11, evaporating aluminum metal on the upper surface and the lower surface, and respectively leading out a first cathode, a first gate pole, a first anode, a second cathode and a second anode; wherein the first cathode and the first gate are located in a first sector of the upper surface, the second anode is located in a second sector of the upper surface, the second cathode is located in a second sector of the lower surface, and the first anode is located in the first sector of the lower surface, as shown in fig. 11.

Specifically, the first cathode, the first gate pole and the first anode are respectively a cathode, a gate pole and an anode of the main thyristor, and the second cathode and the second anode are respectively a cathode and an anode of the integrated BOD thyristor. Fig. 12A and 12B are schematic views of the respective electrodes of the main thyristor and the integrated BOD thyristor of the present invention.

S12: the table top of the chip is shaped into a double positive angle structure or a double negative angle structure, the positive angle is (20-50) degrees, and the negative angle is (10-20) degrees and 1.5-2.5 degrees, as shown in fig. 13A and 13B.

S13: and carrying out mesa corrosion on the mesa of the chip, and then carrying out edge passivation and protection.

Through the steps, the bidirectional thyristor simultaneously comprising the main thyristor and the integrated BOD thyristor can be obtained.

The overvoltage protection function in the bidirectional thyristor is realized by the integrated BOD thyristor, wherein the breakover voltage of the integrated BOD thyristor can be controlled by the size of the groove. In order to increase the sensitivity of a first-stage amplification gate electrode, a circular ring with the width r' is grooved under the first-stage amplification gate electrode, and avalanche current is stably amplified in multiple stages and finally sufficient trigger current is provided for a cathode.

The breakover voltage of the integrated BOD thyristor can be controlled by the size r of the groove after high-concentration diffusion. According to experience, when r is 100-_BOD＝(90-95)％V_R(ii) a When r is 200-_BOD＝(85-90)％V_R. Wherein VR is the breakover voltage for BOD-free design.

The main thyristor and the integrated BOD thyristor are isolated by an isolation region, the isolation region is isolated in a mode of forming PNP isolation by grooving, and the isolation between the two thyristors is realized by two opposite PN structures. Besides the PNP isolation mode, the isolation region can be irradiated without grooving, so that the minority carrier lifetime is shortened, and the mutual influence between two thyristors is reduced.

The above-mentioned serial numbers of the embodiments of the present invention are merely for description and do not represent the merits of the embodiments.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example" or "some examples" or the like are intended to mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

Through the above description of the embodiments, those skilled in the art will clearly understand that the method of the above embodiments can be implemented by software plus a necessary general hardware platform, and certainly can also be implemented by hardware, but in many cases, the former is a better implementation manner.

The above description is only a preferred embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes, which are made by using the contents of the present specification and the accompanying drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.