CN112838128A

CN112838128A - A kind of fast recovery diode and its manufacturing method

Info

Publication number: CN112838128A
Application number: CN201911158451.7A
Authority: CN
Inventors: 曾丹; 刘勇强; 史波; 肖婷
Original assignee: Gree Electric Appliances Inc of Zhuhai
Current assignee: Gree Electric Appliances Inc of Zhuhai
Priority date: 2019-11-22
Filing date: 2019-11-22
Publication date: 2021-05-25

Abstract

The invention provides a fast recovery diode and a manufacturing method thereof, and relates to the technical field of semiconductors. The fast recovery diode includes: a wafer; a cell area disposed on the wafer, the cell area includes a first ion part and a second ion part, and the first ion part is spaced along a preset direction , the second ion part is arranged between two adjacent first ion parts. The present application is provided with a first ion part and a second ion part in the cell region, wherein the first ion part and the second ion part can be doping ion types with different concentrations, forming the first ion part and the second ion part alternately The distributed main junction region can thus take into account the advantages of the fast recovery diode under the ion concentration of the first ion part and the advantages of the fast recovery diode under the second ion concentration, and effectively improve the performance of the fast recovery diode.

Description

Fast recovery diode and manufacturing method thereof

Technical Field

The invention relates to the technical field of semiconductors, in particular to a fast recovery diode and a manufacturing method thereof.

Background

Along with the progress of technology and the development of society, the power consumption is larger and larger, and the demand on power electronic devices is larger and larger for realizing green sustainable development; among them, the power semiconductor device is the mainstream device in the field of power electronics, and is a key device for controlling strong electricity by weak electricity. The power semiconductor device is widely applied to various power control circuits, driving circuits and other circuits, and has irreplaceable effects in the fields of various variable frequency motors, photovoltaic inversion, smart power grids, new energy automobiles, electric locomotives, traction driving and the like.

The power semiconductor device mainly includes: GTOs (thyristors), IGBTs (insulated gate bipolar transistors), power MOSFETs (metal oxide semiconductor field effect transistors), FRDs (fast recovery diodes), and the like.

A cell region of a conventional FRD (fast recovery diode) generally has only one main junction, as shown in fig. 1, and there is no repetitive cell unit, so that a fast recovery diode device is also limited to only one main junction, and one main junction can only focus on one characteristic of the device, so that the performance of the fast recovery diode device is poor and cannot be improved well.

Disclosure of Invention

In order to solve the technical problem of poor performance of a fast recovery diode device in the prior art, the invention mainly aims to provide a fast recovery diode capable of effectively improving performance and a manufacturing method thereof.

In a first aspect, an embodiment of the present invention provides a fast recovery diode, including:

a wafer;

the cell area is arranged on the wafer and comprises first ion parts and second ion parts, the first ion parts are distributed at intervals along a preset direction, and the second ion parts are arranged between every two adjacent first ion parts.

Further, in a preferred embodiment of the present invention, the wafer includes: the cell structure comprises a substrate layer and an epitaxial layer formed on the surface of the substrate layer, wherein the cell area is formed on one side, away from the substrate layer, of the epitaxial layer, and the cell area extends along the direction from the epitaxial layer to the substrate layer.

Further, in a preferred embodiment of the present invention, an arc-shaped groove is disposed on a surface of the epitaxial layer between two adjacent first ion portions, and the second ion portion is disposed in the arc-shaped groove.

Further, in a preferred embodiment of the present invention, the first ion portion extends for a distance greater than the second ion portion.

Further, in a preferred embodiment of the present invention, the first ion portion includes heavily doped P-type ions, and the second ion portion includes lightly doped P-type ions.

Further, in a preferred embodiment of the present invention, the epitaxial layer includes a first epitaxial layer and a second epitaxial layer sequentially disposed on the surface of the substrate, and the cell region is formed on the second epitaxial layer.

Another embodiment of the present invention provides a method for manufacturing a fast recovery diode, including the following steps:

growing a first ion part on the wafer;

etching the wafer by adopting a preset process to form an etching groove between two adjacent first ion parts;

and injecting second ions into the etching groove to form a second ion part.

Further, in a preferred embodiment of the present invention, the etching on the wafer by using a predetermined process includes: and etching the surface of the substrate layer by adopting a wet etching process or a dry isotropic silicon etching process of silicon.

In the fast recovery diode and the manufacturing method thereof provided by the embodiments of the present invention, the cell area is provided with the first ion portion and the second ion portion, wherein the first ion portion and the second ion portion may be doped ion types with different concentrations, and the main junction region distributed between the first ion portion and the second ion portion is formed, so that the advantages of the fast recovery diode under the first ion portion ion concentration and the advantages of the fast recovery diode under the second ion portion ion concentration can be both considered, and the performance of the fast recovery diode is effectively improved.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.

FIG. 1 is a schematic diagram of a prior art fast recovery diode;

fig. 2 is a schematic structural diagram of a fast recovery diode according to an embodiment of the present invention.

Reference numerals:

1. the semiconductor device comprises a wafer, 11, a substrate layer, 12, a first epitaxial layer, 13, a second epitaxial layer, 2, a terminal region, 3, a cell region, 31, a first ion part, 32, a second ion part, 4, an oxide layer, 5 and a metal layer.

Detailed Description

In order to more clearly explain the technical solutions of the embodiments of the present application, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and that for those skilled in the art, other related drawings can be obtained from the drawings without inventive effort.

As shown in fig. 1, a conventional power semiconductor device generally includes a termination region 2(Terminal) and a Cell region 3(Cell), and the termination region 2 is mainly used to improve a fringe electric field and to improve a lateral breakdown voltage of the device. In FRD (fast recovery diode), the cell region 3 is generally only a main junction, and there is no repetitive cell unit.

Research shows that the fast recovery diode device in the prior art is limited to only one main junction (main junction), and if the Vf (conduction voltage drop) is lower, a heavily doped and deep P-type junction is needed; if the good switching characteristic is realized, a lightly doped and shallow junction deep P-type junction is needed; the two implementation modes are contradictory, and in order to balance the device performance in the prior art, a mode of performance compromise is often adopted, and the performance of two parameters cannot be improved at the same time.

As shown in fig. 2, a fast recovery diode according to an embodiment of the present invention includes: a wafer 1; the cell region 3 is disposed on the wafer 1, the cell region 3 includes first ion parts 31 and second ion parts 32, the first ion parts 31 are distributed at intervals along a predetermined direction, and the second ion part 32 is disposed between two adjacent first ion parts 31. In the fast recovery diode provided by the embodiment of the present invention, the cell region 3 is provided with the first ion portion 31 and the second ion portion 32, wherein the first ion portion 31 and the second ion portion 32 may be doped ion types with different concentrations, and main junction regions (the cell region 3) where the first ion portion 31 and the second ion portion 32 are distributed at intervals are formed, so that the advantages of the fast recovery diode under the ion concentration of the first ion portion 31 and the advantages of the fast recovery diode under the ion concentration of the second ion portion 32 can be both considered, and the performance of the fast recovery diode is effectively improved.

In this embodiment, the predetermined direction is a radial direction of the silicon wafer 1.

As shown in fig. 2, the silicon wafer 1 includes: the cell structure comprises a substrate layer 11 and an epitaxial layer formed on the surface of the substrate layer 11, wherein a cell area 3 is formed on one side of the epitaxial layer, which is far away from the substrate layer 11, and the cell area 3 extends along the direction from the epitaxial layer to the substrate layer 11. The substrate layer 11 is a semiconductor silicon epitaxial substrate layer 11, and parameters such as the thickness, the resistivity and the like of the substrate layer 11 are different according to the voltage withstanding requirements of different products; in this embodiment, the epitaxial layer is a double-layer epitaxial structure, that is, the epitaxial layer includes a first epitaxial layer 12 and a second epitaxial layer 13 which are sequentially grown on the surface of the substrate layer 11; growing a first epitaxial layer (NBuffer)12 structure on a silicon wafer (N + Sub)11, and then growing a second epitaxial layer (N-EPI)13 structure; an oxide layer 4 is then grown on the second epitaxial layer 13, and the cell region 3 and the termination region 2 are both formed on the second epitaxial layer 13.

As shown in fig. 2, in the present embodiment, the first ion portion 31 extends a distance greater than the second ion portion 32, that is, the thickness of the doped region of the first ion portion 31 is greater than the thickness of the doped region of the second ion portion 32 in the axial direction of the wafer 1. When the first ion portion 31 includes heavily doped P-type ions and the second ion portion 32 includes lightly doped P-type ions, the first ion portion 31 forms heavily doped deep P-type ions and the second ion portion 32 forms lightly doped shallow P-type ions according to the extension distance. Therefore, the fast recovery diode provided in the embodiment has the dual advantages of lower Vf (conduction loss) of the heavily doped deep P-type junction and better switching characteristics of the lightly doped shallow P-type junction, and effectively improves the performance of the device.

The heavy doping and the light doping are directed at different concentrations of impurities doped in ions, and the heavy doping refers to a doping mode which is usually adopted by a person skilled in the art because the amount of the impurities doped in a semiconductor material is large.

In this embodiment, an arc groove is etched on the surface of the epitaxial layer between two adjacent first ion portions 31 or the surface of the epitaxial layer is etched into a bowl-shaped surface, a second ion portion 32 is disposed in the arc groove, and the second ion portion 32 is formed by implanting second ions into the arc groove. The cellular region 3 of the fast recovery diode adopts a cellular region 3 structure combining a heavily doped deep P-type junction and a lightly doped shallow P-type junction, and the lightly doped shallow P-type junction adopts an ion doping distribution mode similar to an arc structure.

Another embodiment of the present invention provides a method for manufacturing a fast recovery diode, including the steps of:

s101, a first ion portion 31 (heavily doped P-type ion portion) is grown on the wafer 1.

S102, etching the wafer 1 by adopting a preset process to form an etching groove between two adjacent first ion parts 31; etching the wafer 1 by adopting a preset process, comprising the following steps of: the surface of the substrate layer 11 is etched by wet etching or dry isotropic silicon etching of silicon.

And S103, implanting second ions (lightly doped P-type ions) into the etching groove to form a second ion part.

The method for manufacturing the fast recovery diode provided by the other embodiment of the invention comprises the following steps:

s201, growing a first epitaxial layer 12 on the surface of the substrate layer 11.

And S202, growing a second epitaxial layer 13 on the side, away from the substrate layer 11, of the first epitaxial layer 12.

And S203, growing an oxide layer 4 on the side, far away from the substrate layer 11, of the second epitaxial layer 13.

S204, the oxide layer 4 is etched, and a first ion portion 31 (heavily doped P-type ion portion) is grown in the predetermined region.

S205, etching is performed on the wafer 1 by using a predetermined process to form an etching groove between two adjacent first ion portions 31.

And S206, implanting second ions (lightly doped P-type ions) into the etching groove to form a second ion part.

The fast recovery diode cell region 3 structure in the embodiment of the invention can be matched with different terminal structures, such as a field limiting ring structure, a field limiting ring and field plate structure, a junction terminal extension structure (JTE), a transverse variable doping structure (VLD) and the like. In an embodiment of the present invention, only one of the cell domain field-limiting ring-and-field plate structures is described, as shown in fig. 2, a method for manufacturing a fast recovery diode in the embodiment includes the following steps:

and S301, growing a first epitaxial layer 12 on the surface of the substrate layer 11.

And S302, growing a second epitaxial layer 13 on the side, far away from the substrate layer 11, of the first epitaxial layer 12.

And S303, growing an oxide layer 4 on one side of the second epitaxial layer 13 far away from the substrate layer 11.

And S304, coating photoresist on the oxide layer 4, exposing and developing the photoresist by using a mask, photoetching and etching the terminal region 2, and performing ion implantation and trap (activation) of the terminal region 2 on an implantation window formed by etching.

S305, carrying out active area photoetching and etching: coating photoresist on the oxide layer 4 corresponding to the cellular region 3, and exposing and developing the photoresist by using a first mask; etching the oxide layer 4, implanting first ions (heavily doped deep P-type ions) into a plurality of first implantation windows (namely, in a preset region) which are formed by etching and distributed at intervals to form a first ion part 31, and performing trap pushing (activation);

the shape of the first mask involved in this step may be set to be the same as the distribution of the first ion portions 31, that is, the first mask is set to have a plurality of first annular openings distributed at intervals, each first annular opening corresponds to one first implantation window, so that after etching, the first implantation windows are implanted with first ions.

S306, coating photoresist on the oxide layer 4, and carrying out exposure development on the photoresist by using a mask; etching to form a plurality of second injection windows distributed at intervals, wherein each second injection window is positioned between every two adjacent first injection windows in the step S305;

simultaneously, etching the surface of the substrate layer 11 of the wafer 1 by adopting a wet etching process or a dry isotropic silicon etching process of silicon, and forming a bowl-mouth-shaped etching groove on the surface of the substrate layer 11 between two adjacent first ion parts 31;

the shape of the second mask plate involved in the step is complementary to the shape of the first mask plate in the step S305, that is, the second mask plate has a plurality of second annular openings distributed at intervals, and each second annular opening is correspondingly located between every two first annular openings on the first mask plate; each second annular opening corresponds to one second injection window, so that second ions are injected into the second injection windows after etching.

S307, implanting second ions (lightly doped shallow P-type ions) into the etching trench to form a second ion portion 32; and the lightly doped shallow P-type ions are driven (activated).

S308, photoetching and etching the stop ring by adopting a conventional technical means in the field of power semiconductor devices; and the injection and trapping of the ring-cut ions are performed.

And S309, depositing a dielectric layer by adopting a conventional technical means in the field of power semiconductor devices.

And S310, performing contact hole photoetching and etching by adopting a conventional technical means in the field of power semiconductor devices.

S311, depositing the metal layer 5 by adopting a conventional technical means in the field of power semiconductor devices, and photoetching and etching the metal.

S312, depositing, photoetching and etching a passivation layer by adopting a conventional technical means in the field of power semiconductor devices; this step is not essential and is set according to the product characteristics.

In the description of the present invention, it is to be understood that the terms "upper", "lower", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", and the like, indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings. This is merely to facilitate description of the invention and to simplify the description, and is not intended to indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and is therefore not to be considered limiting of the invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.

In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. a fast recovery diode, is characterized in that, comprises:

wafer(1);

A cell region (3) disposed on the wafer (1), the cell region (3) comprising a first ion part (31) and a second ion part (32), the first ion part ( 31) Distributed at intervals along a preset direction, and the second ion parts (32) are arranged between two adjacent first ion parts (31).

2. The fast recovery diode according to claim 1, wherein the wafer (1) comprises: a substrate layer (11) and an epitaxial layer formed on the surface of the substrate layer (11), the epitaxial layer The cell region (3) is formed on the side away from the substrate layer (11), and the cell region (3) extends along the direction from the epitaxial layer to the substrate layer (11).

3 . The fast recovery diode according to claim 2 , wherein an arc-shaped groove is formed on the surface of the epitaxial layer between two adjacent first ion parts ( 31 ), and the arc-shaped groove is inside the arc-shaped groove. 4 . The second ion part (32) is provided.

4 . The fast recovery diode according to claim 2 , wherein the extending distance of the first ion portion ( 31 ) is greater than the extending distance of the second ion portion ( 32 ). 5 .

5. The fast recovery diode according to claim 2, wherein the first ion part (31) comprises heavily doped P-type ions, and the second ion part (32) comprises lightly doped P-type ions .

6. The fast recovery diode according to claim 2, wherein the epitaxial layer comprises a first epitaxial layer (12) and a second epitaxial layer (13) sequentially arranged on the surface of the substrate layer (11), The cell region (3) is fabricated on the second epitaxial layer (13).

7. The manufacturing method of the fast recovery diode, is characterized in that, comprises the following steps:

growing a first ion portion (31) on the wafer (1);

Etching is performed on the wafer (1) by using a preset process, so as to form an etching groove between two adjacent first ion parts (31);

The second ions are implanted in the etching groove to form a second ion part.

8 . The method for manufacturing a fast recovery diode according to claim 7 , wherein the etching on the wafer ( 1 ) using a preset process comprises: using silicon wet etching or dry etching. 9 . The surface of the substrate layer (11) is etched by an isotropic silicon etching process.