CN214203692U

CN214203692U - FRD diode with short reverse recovery time

Info

Publication number: CN214203692U
Application number: CN202120308618.XU
Authority: CN
Inventors: 张振中; 郝建勇; 俞鑫罡
Original assignee: Hangzhou Zhongrui Hongxin Semiconductor Co ltd
Current assignee: Hangzhou Zhongrui Hongxin Semiconductor Co ltd
Priority date: 2021-02-03
Filing date: 2021-02-03
Publication date: 2021-09-14
Anticipated expiration: 2031-02-03

Abstract

The utility model discloses a FRD diode that reverse recovery time is short, including N type silicon substrate layer (1), N type silicon substrate layer (1) surface distribution has a plurality of slots (2), and slot (2) inboard is equipped with P + substrate structure (3), and the outside of N type silicon substrate layer (1) is equipped with N type silicon epitaxial layer (4), and the inboard of N type silicon epitaxial layer (4) is filled slot (2) completely. The utility model can effectively improve the reverse recovery time and high temperature reliability of the FRD diode through the matching of the groove formed on the surface of the N-type silicon substrate layer and the P + substrate structure, and avoid the pollution to the production line; simultaneously, the current density of FRD diode can also be improved in the setting of slot to remedy the forward conduction pressure drop increase problem that causes because of technology on the basis of the improvement performance, make the utility model discloses have reverse recovery time simultaneously short, do not have the characteristics that the line pollution and forward conduction pressure drop are little.

Description

FRD diode with short reverse recovery time

Technical Field

The utility model relates to a FRD diode, especially a FRD diode that reverse recovery time is short.

Background

The conventional FRD material is formed by directly growing a layer of N-type epitaxial material on an N-type substrate material to form a raw material for manufacturing the FRD, and then forming the whole semiconductor device structure through photoetching, etching, injecting and annealing processes. In order to accelerate the reverse recovery time of the FRD diode and improve the high-temperature stability of the FRD diode, the conventional FRD diode is formed and then subjected to a Pt diffusion or electron irradiation process. The recovery time of the FRD diode treated by the electron irradiation process is 12-30 ns, and the high-temperature reliability reaches 125 ℃; the FRD diode treated by the Pt expanding process can reach the recovery time of 5-20 ns and the high-temperature reliability of 150 ℃.

However, the Pt expanding process has the defects that Pt belongs to heavy metal and can cause pollution to other products of a semiconductor, so that the capability of a semiconductor production line for processing other products is limited, and the universality is poor. The improvement effect of the electron irradiation process is weaker than that of the Pt diffusion process in performance index, and the performance requirements of manufacturers cannot be met, so that the two treatment processes have certain defects.

In addition, the reverse recovery time of the FRD diode and the forward conduction voltage drop thereof are in a contradictory relationship, that is, the reverse recovery time can cause the increase of the forward conduction voltage drop after being shortened, thereby increasing the rectification loss of the FRD diode. Therefore, the forward conduction voltage drop of the FRD diode can be increased by the Pt expansion or electron irradiation process treatment, and the performance index of the FRD diode is reduced on the other hand. The forward conduction voltage drop of the FRD diode treated by the current Pt expansion or electron irradiation technology is generally 1.6-1.8V.

Therefore, the conventional FRD diode cannot simultaneously have the characteristics of short reverse recovery time, no production line pollution and large forward conduction voltage drop.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to provide a FRD diode that reverse recovery time is short. The method has the characteristics of short reverse recovery time, no production line pollution and small forward conduction voltage drop.

The technical scheme of the utility model: the FRD diode with short reverse recovery time comprises an N-type silicon substrate layer, wherein a plurality of grooves are distributed on the surface of the N-type silicon substrate layer, a P + substrate structure is arranged on the inner side of each groove, an N-type silicon epitaxial layer is arranged outside the N-type silicon substrate layer, and the grooves are completely filled in the inner side of the N-type silicon epitaxial layer.

In the FRD diode with short reverse recovery time, the trench includes a bottom plane, inclined sidewalls are disposed around the bottom plane, the cross-sectional shape of the sidewalls is V-shaped, and the inclination of the sidewalls is 45 °.

In the short FRD diode of aforementioned reverse recovery time, the degree of depth of basal plane is 0.5um, the width of slot is 1 ~ 3 um.

In the short-reverse recovery FRD diode, the implanted ion type of the P + substrate structure is B type, the doping concentration of the P + substrate structure is 1E 15-6E 15, the depth of the P + substrate structure is 0.8-1 um, and the width of the P + substrate structure is greater than the width of the groove by 0.4-0.6 um.

In the FRD diode with short reverse recovery time, a P-substrate structure is disposed on the surface of the N-type silicon epitaxial layer, and a Ti/AL metal stack is disposed outside the N-type silicon epitaxial layer; the N-type silicon epitaxial layer and the Ti/AL metal stack are partially filled with a SiO2 layer at the connection.

Compared with the prior art, the utility model has the characteristics of it is following:

(1) the utility model discloses a P + substrate structure that forms is poured into at N type silicon substrate layer surface, can effectively reduce the reverse recovery time of FRD diode, makes the recovery time of this application diode can reach 5 ~ 20ns, and high temperature reliability reaches 150 ℃, and the performance with the FRD diode after the current Pt technology that expands handles is the same, and is superior to the improvement effect of electron irradiation technology; meanwhile, compared with a Pt expanding process, the P + substrate structure can effectively avoid pollution to a semiconductor production line during processing, and the universality of the utility model is improved;

(2) the current density of the FRD diode can be improved by the groove formed on the surface of the N-type silicon substrate layer, on the basis, the current flowing area can be further increased by setting the inclination of the side wall of the groove to be 45 degrees, and the current density of the diode is improved to 190A/cm from the original 130-160A/cm; the current density of the diode can play a role in reducing the forward conduction voltage drop after being improved, so that the forward conduction voltage drop of the diode is reduced to 1.5V, which is similar to the forward conduction voltage drop of the diode which is not treated by the conventional Pt expansion process or the electron irradiation process;

therefore, the utility model discloses can have reverse recovery time simultaneously short, no production line pollutes and the characteristics that the forward conduction pressure drop is little.

Drawings

Fig. 1 is a schematic structural diagram of the present invention;

FIG. 2 is an enlarged view of the trench and P + substrate structure;

FIG. 3 is a schematic diagram of a conventional FRD diode;

fig. 4 is a process flow diagram of the present invention.

The labels in the figures are: the structure comprises a 1-N type silicon substrate layer, a 2-groove, a 3-P + substrate structure, a 4-N type silicon epitaxial layer, a 5-P-substrate structure, a 6-Ti/AL metal lamination layer, a 7-SiO2 layer, a 201-bottom plane and a 202-side wall.

Detailed Description

The following description is made with reference to the accompanying drawings and examples, but not to be construed as limiting the invention.

Examples are given. The FRD diode with short reverse recovery time is shown in figures 1-2 and comprises an N-type silicon substrate layer 1, wherein a plurality of grooves 2 are distributed on the surface of the N-type silicon substrate layer 1, a P + substrate structure 3 is arranged on the inner side of each groove 2, an N-type silicon epitaxial layer 4 is arranged outside the N-type silicon substrate layer 1, and the grooves 2 are completely filled by the inner side of the N-type silicon epitaxial layer 4.

The groove 2 comprises a bottom plane 201, an inclined side wall 202 is arranged around the bottom plane 201, the cross section of the side wall 202 is V-shaped, and the inclination alpha of the side wall 202 is 45 degrees.

The degree of depth H of base plane 201 is 0.5um, the width I of slot 2 is 1 ~ 3 um.

The implanted ion type of the P + substrate structure 3 is B type, the doping concentration of the P + substrate structure 3 is 1E 15-6E 15, the depth J of the P + substrate structure 3 is 0.8-1 um, and the width K of the P + substrate structure 3 is larger than the width I of the groove 2 by 0.4-0.6 um.

The surface of the N-type silicon epitaxial layer 4 is provided with a P-substrate structure 5, and the outside of the N-type silicon epitaxial layer 4 is provided with a Ti/AL metal lamination 6; the N-type silicon epitaxial layer 4 and the Ti/AL metal stack 6 are partially filled with a SiO2 layer 7 at the connections.

The preparation method of the FRD diode with short reverse recovery time, as shown in fig. 4, includes the following steps:

firstly, forming a plurality of grooves on the surface of an N-type silicon substrate layer through photoetching and etching processes in sequence to obtain a product A;

photoetching, etching, injecting and high-temperature propelling processes are sequentially carried out on the product A at the position of the groove to form a P + substrate structure, and a product B is obtained;

thirdly, growing and forming an N-type silicon epitaxial layer on the surface of the product B, and completely filling the groove with the N-type silicon epitaxial layer to obtain a product C;

fourthly, photoetching, etching and injecting processes are sequentially carried out on the surface of the product C to form a P-substrate structure, and a product D is obtained;

and fifthly, carrying out photoetching, etching, injecting and annealing processes on the surface of the product D in sequence to form an SiO2 layer and a Ti/AL metal lamination to obtain a finished product.

The structure of the conventional FRD diode is shown in FIG. 3, and the processing technology comprises the steps of firstly growing an N-type silicon epitaxial layer 4 on the surface of an N-type silicon substrate layer 1, then forming a P-substrate structure 5 on the surface of the N-type silicon epitaxial layer 4 through photoetching, etching and injection processes, and then forming a SiO2 layer 7 and a Ti/AL metal lamination 6 through photoetching, etching, injection and annealing processes; and finally, adopting a Pt expanding or electron irradiation process (the effect generated by adopting the Pt expanding or electron irradiation process is relatively microscopic and is not shown in the figure) to the FRD material to form an FRD diode.

The utility model discloses a theory of operation: the utility model discloses a mode of injecting into P + substrate structure 3 at the surface of N type silicon substrate layer 1 replaces current Pt technology or electron irradiation technology that expands to handle the FRD material, can play with expand the effect that the same accelerated diode reverse recovery time of Pt technology and electron irradiation technology was with improvement high temperature reliability, and improve the effect and be superior to electron irradiation technology. On the other hand, the utility model discloses compare to the preparation technology of P + substrate structure 3 and expand the Pt technology and can avoid producing the pollution of line to the diode to effectively improve this commonality of producing the line, reduce the utility model discloses required preparation finished product.

On the basis, the utility model discloses a photoetching and etching process to N type silicon substrate layer 1 surface form slot 2 to set up P + substrate structure 3 in slot 2 inboard, can effectively improve the current density of FRD diode, make its current density improve to 190A/cm from original 130 ~ 160A/cm; the current density of the FRD diode can play a role in reducing forward conduction voltage drop (VF) after being improved, so that the problem of increase of the forward conduction voltage drop caused by accelerated reverse recovery time of the diode is solved; alleviate the VF increase phenomenon that technology caused in accelerating FRD diode reverse recovery time and improving high temperature reliability, improved the utility model discloses a work efficiency.

Claims

1. FRD diode that reverse recovery time is short, its characterized in that: the silicon substrate comprises an N-type silicon substrate layer (1), wherein a plurality of grooves (2) are distributed on the surface of the N-type silicon substrate layer (1), a P + substrate structure (3) is arranged on the inner side of each groove (2), an N-type silicon epitaxial layer (4) is arranged outside the N-type silicon substrate layer (1), and the grooves (2) are completely filled in the inner side of the N-type silicon epitaxial layer (4).

2. The FRD diode with short reverse recovery time of claim 1, wherein: the groove (2) comprises a bottom plane (201), inclined side walls (202) are arranged on the periphery of the bottom plane (201), the cross section of each side wall (202) is V-shaped, and the inclination of each side wall (202) is 45 degrees.

3. The FRD diode with short reverse recovery time of claim 2, wherein: the degree of depth of basal plane (201) is 0.5um, the width of slot (2) is 1 ~ 3 um.

4. The FRD diode with short reverse recovery time of claim 3, wherein: the implanted ion type of the P + substrate structure (3) is B type, the doping concentration of the P + substrate structure (3) is 1E 15-6E 15, the depth of the P + substrate structure (3) is 0.8-1 um, and the width of the P + substrate structure (3) is larger than the width of the groove (2) by 0.4-0.6 um.

5. The FRD diode with short reverse recovery time of claim 1, wherein: the surface of the N-type silicon epitaxial layer (4) is provided with a P-substrate structure (5), and the outside of the N-type silicon epitaxial layer (4) is provided with a Ti/AL metal lamination (6); the N-type silicon epitaxial layer (4) and the Ti/AL metal stack (6) are partially filled with a layer of SiO2 (7) at the junction.