Fast recovery diode and manufacturing method thereof

Abstract

The invention provides a fast recovery diode and a manufacturing method thereof, and the method comprises the steps: providing a substrate which comprises a front surface and a back surface which are opposite to each other; performing ion implantation on the front surface of the substrate to form an anode region and a terminal region; sequentially forming an oxide layer and a passivation layer on the front surface of the substrate; sequentially etching the passivation layer and the oxide layer to form a contact hole exposing the anode region; forming a front surface metal layer on the front surface of the substrate, wherein the front surface metal layer fills the contact hole and is in contact with the anode region; and forming a back metal layer on the back of the substrate. According to the invention, after the oxide layer is formed, the passivation layer is directly formed, the passivation layer and the oxide layer are etched to form the contact hole, the oxide layer does not need to be subjected to photoetching independently, photoetching of an alignment mark is omitted, the manufacturing of the alignment mark is saved by increasing the offset between the contact hole and the anode region, and the manufacturing cost is reduced. And the use of two masks is reduced in total, so that the manufacturing cost is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor integrated circuits, and in particular to a fast recovery diode and a manufacturing method thereof. Background Art

[0002] At present, the world's green energy industry has attracted widespread attention from all countries. In order to save energy and reduce emissions, all countries have put forward corresponding long-term plans. IGBT (Insulated Gate Bipolar Transistor) is a key device for power conversion and transmission, which directly affects the development of new energy vehicles, new energy power generation, smart grid and other industries. Generally, an IGBT module contains two devices: IGBT and FRD (Fast Recovery Diode), in which the fast recovery diode is used for protection and freewheeling.

[0003] During the forward conduction period of the fast recovery diode, a large number of holes and electrons are injected into the N-base region from the anode side and the cathode side respectively, and the on-state resistance is greatly reduced, resulting in a conductivity modulation effect. Currently, N-type substrates are often used, and the surface P-anode region concentration is strictly controlled to reduce the anode injection efficiency; in addition, in order to achieve a lower base resistance, Al metal without a barrier layer is often used for contact; finally, life control is required to achieve fast recovery.

[0004] The current manufacturing methods of fast recovery diodes generally include: 1) zero (zero layer) lithography, etching alignment marks; 2) PFLD (P-type ion implantation) lithography, implantation annealing; 3) LOCOS (field oxide layer) lithography etching, growing oxide layer; 4) ILD (dielectric layer) deposition, BPSG (doped borophosphosilicate glass) annealing; 5) CT (contact hole) lithography etching implantation; 6) metal deposition lithography etching; 7) PA (Passivation, usually silicon-containing material) deposition lithography etching; 8) PI (polyimide) coating lithography etching; 9) back side process.

[0005] However, the existing process is relatively long, using 7 masks, and the number of masks used is relatively large. Summary of the invention

[0006] The purpose of the present invention is to provide a fast recovery diode and a manufacturing method thereof, which can reduce the number of masks and lower the cost.

[0007] In order to solve the above technical problems, according to a first aspect of the present invention, a method for manufacturing a fast recovery diode is provided, comprising the following steps:

[0008] Providing a substrate, the substrate comprising a front side and a back side arranged opposite to each other;

[0009] Performing ion implantation on the front surface of the substrate to form an anode region and a terminal region;

[0010] forming an oxide layer and a passivation layer in sequence on the front surface of the substrate;

[0011] Sequentially etching the passivation layer and the oxide layer to form a contact hole exposing the anode region;

[0012] forming a front metal layer on the front side of the substrate, wherein the front metal layer fills the contact hole and contacts the anode region; and

[0013] A back metal layer is formed on the back side of the substrate.

[0014] Optionally, the method of performing ion implantation on the front surface of the substrate to form an anode region and a terminal region includes:

[0015] forming a first photoresist layer on the substrate;

[0016] exposing and developing the first photoresist layer to form a patterned first photoresist layer;

[0017] Using the patterned first photoresist layer as a mask, ion implantation is performed on the substrate; and

[0018] The patterned first photoresist layer is removed.

[0019] Optionally, the terminal region is formed by adopting a lateral variable doping technology.

[0020] Optionally, the passivation layer includes a first passivation layer and a second passivation layer sequentially located on the oxide layer, the material of the first passivation layer includes BPSG, and the material of the second passivation layer includes PA.

[0021] Optionally, the method of sequentially etching the passivation layer and the oxide layer to form a contact hole exposing the anode region includes:

[0022] forming a second photoresist layer on the passivation layer;

[0023] exposing and developing the second photoresist layer to form a patterned second photoresist layer;

[0024] Using the patterned second photoresist layer as a mask, etching the passivation layer and the oxide layer until the anode region is exposed; and

[0025] The patterned second photoresist layer is removed.

[0026] Optionally, the method of forming a front metal layer on the front side of the substrate includes:

[0027] forming a front metal material layer on the front side of the substrate, wherein the front metal material layer fills the through hole and covers the passivation layer;

[0028] forming a third photoresist layer on the front metal material layer;

[0029] Exposing and developing the third photoresist layer to form a patterned third photoresist layer;

[0030] Using the patterned third photoresist layer as a mask, etching the front metal material layer until a portion of the passivation layer is exposed; and

[0031] The patterned third photoresist layer is removed.

[0032] Optionally, after forming the front metal layer and before forming the back metal layer, the manufacturing method further includes: forming a polyimide layer, wherein the polyimide layer covers a portion of the front metal layer and the exposed passivation layer.

[0033] Optionally, the method of forming the polyimide layer includes:

[0034] forming a polyimide material layer, wherein the polyimide material layer covers the front metal layer and the exposed passivation layer;

[0035] forming a fourth photoresist layer on the polyimide material layer;

[0036] Exposing and developing the fourth photoresist layer to form a patterned fourth photoresist layer;

[0037] Using the patterned fourth photoresist layer as a mask, etching the polyimide material layer to form a polyimide layer; and

[0038] The patterned fourth photoresist layer is removed.

[0039] Optionally, after forming the front metal layer and before forming the back metal layer, the manufacturing method further includes: thinning the back side of the substrate.

[0040] In order to solve the above technical problem, according to a second aspect of the present invention, a fast recovery diode is further provided, which is manufactured by the manufacturing method of the fast recovery diode as described above, and the fast recovery diode comprises:

[0041] A substrate, the substrate comprising a front side and a back side arranged opposite to each other;

[0042] An anode region and a terminal region are respectively located in the front surface of the substrate;

[0043] an oxide layer, located on the front side of the substrate;

[0044] A passivation layer is located on the oxide layer; a contact hole exposing the anode region is formed in the passivation layer and the oxide layer;

[0045] a front metal layer, covering the passivation layer and filling the contact hole; and

[0046] The back metal layer is located on the back side of the substrate.

[0047] In the fast recovery diode and the manufacturing method thereof provided by the present invention, a substrate is first provided, the substrate includes a front side and a back side that are arranged opposite to each other, then ion implantation is performed on the front side of the substrate to form an anode region and a terminal region, then an oxide layer and a passivation layer are sequentially formed on the front side of the substrate, then the passivation layer and the oxide layer are sequentially etched to form a contact hole exposing the anode region, then a front metal layer is formed on the front side of the substrate, the front metal layer fills the contact hole and contacts the anode region, then a back metal layer is formed on the back side of the substrate. After the oxide layer is formed, the present invention directly forms a passivation layer, then etches the passivation layer and the oxide layer to form a contact hole, and there is no need to perform photolithography etching on the oxide layer separately, and the photolithography etching of the alignment mark is omitted, and the production of the alignment mark is saved by increasing the offset between the contact hole and the anode region, thereby reducing the use of two mask plates in total and reducing the production cost.

[0048] At the same time, the present invention adopts lateral variable doping technology to form the terminal area, and completes the deposition of the passivation layer before forming the front metal layer, thereby saving a mask without affecting the reliability, and further reducing the production cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 It is a flow chart of a method for manufacturing a fast recovery diode provided in one embodiment of the present invention.

[0050] Figures 2 to 8 It is a schematic structural diagram of each step of a method for manufacturing a fast recovery diode provided by an embodiment of the present invention.

[0051] Description of reference numerals:

[0052] 10 - substrate; 11 - anode region; 12 - terminal region; 13 - field oxide layer; 14 - first passivation layer; 15 - second passivation layer; 16 - contact hole; 17 - front metal layer; 18 - polyimide layer; 19 - back metal layer. DETAILED DESCRIPTION

[0053] In order to make the purpose, advantages and features of the present invention clearer, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the drawings are all in a very simplified form and are not drawn to scale, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention. In addition, the structure shown in the drawings is often a part of the actual structure. In particular, the emphasis of each drawing is different, and sometimes different scales are used.

[0054] As used in the present invention, the singular forms "one", "an" and "the" include plural objects, unless the content clearly indicates otherwise. As used in the present invention, the term "or" is generally used in a sense that includes "and / or", unless the content clearly indicates otherwise. As used in the present invention, the term "several" is generally used in a sense that includes "at least one", unless the content clearly indicates otherwise. As used in the present invention, the term "at least two" is generally used in a sense that includes "two or more", unless the content clearly indicates otherwise. In addition, the terms "first", "second", and "third" are used only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first", "second", and "third" may explicitly or implicitly include one or at least two of the features, unless the content clearly indicates otherwise.

[0055] Figure 1 FIG. 1 is a flow chart of a method for manufacturing a fast recovery diode provided by an embodiment of the present invention. Figure 1 As shown, the method for manufacturing a fast recovery diode includes the following steps:

[0056] S1: providing a substrate, wherein the substrate comprises a front side and a back side arranged opposite to each other;

[0057] S2: performing ion implantation on the front surface of the substrate to form an anode region and a terminal region;

[0058] S3: forming an oxide layer and a passivation layer in sequence on the front surface of the substrate;

[0059] S4: etching the passivation layer and the oxide layer in sequence to form a contact hole exposing the anode region;

[0060] S5: forming a front metal layer on the front side of the substrate, wherein the front metal layer fills the contact hole and contacts the anode region; and

[0061] S6: forming a back metal layer on the back side of the substrate.

[0062] Figures 2 to 8 FIG. 1 is a schematic diagram of the structure of each step of the method for manufacturing a fast recovery diode provided by an embodiment of the present invention. Figure 1 , Figures 2 to 8 The method for manufacturing the fast recovery diode provided in the embodiment of the present invention is described in detail.

[0063] In step S1, refer to Figure 2 As shown, a substrate 10 is provided, wherein the substrate 10 includes a front surface and a back surface that are oppositely arranged.

[0064] Figure 2 In the figure, the top of the substrate 10 is the front side of the substrate 10 , and the bottom of the substrate 10 is the back side of the substrate 10 .

[0065] In one embodiment of the present invention, the substrate 10 includes an N-type substrate and an N-type base layer located on the N-type substrate, wherein the N-type substrate is a high-concentration N+ silicon layer, and the N-type base layer is a low-concentration N- silicon layer. The side of the N-type base layer away from the N-type substrate serves as the front side of the substrate 10, and the side of the N-type substrate away from the N-type base layer serves as the back side of the substrate 10. Subsequently, a P-type anode region is formed in the N-type base layer to form a PN-N+ structure, and then the reverse recovery time is reduced by minority carrier lifetime control technology such as platinum diffusion or irradiation.

[0066] In one embodiment of the present invention, an N-type buffer layer may be formed between the N-type base layer and the N-type substrate, that is, a medium-concentration N-type buffer layer is first epitaxially formed on the high-concentration N-type substrate, and then a low-concentration N-type base layer is epitaxially formed on the medium-concentration N-type buffer layer, thereby reducing the on-state voltage drop and increasing the softness of the reverse recovery time.

[0067] In step S2, please continue to refer to Figure 2 As shown, ion implantation is performed on the front surface of the substrate 10 to form an anode region 11 and a terminal region 12 .

[0068] In one embodiment of the present invention, a first photoresist layer is formed on the front side of the substrate 10, and the first photoresist layer is exposed and developed to form a patterned first photoresist layer, wherein the patterned first photoresist layer exposes a predetermined area for ion implantation, i.e., the patterned first photoresist layer forms an ion implantation window. Then, ion implantation is performed on the front side of the substrate 10 using the patterned first photoresist layer as a mask, and an anode region 11 and a terminal region 12 are formed in the substrate 10, and then the patterned first photoresist layer is removed. Of course, a mask layer may also be formed between the first photoresist layer and the substrate 10, and the mask layer may be etched using the patterned first photoresist layer as a mask to form a patterned mask layer, and then the patterned first photoresist layer may be removed, and ion implantation is performed on the front side of the substrate 10 using the patterned mask layer as a mask, and then the patterned mask layer may be removed.

[0069] Exemplarily, P-type ion implantation is performed on the front surface of the substrate 10 .

[0070] In one embodiment of the present invention, the terminal region 12 is formed by using a lateral variable doping technology (VLD), that is, a VLD structure terminal is formed. By changing the size of the doping injection opening, the doping impurity concentration and junction depth after annealing are changed, thereby forming a P-type region with a varying doping concentration and junction depth in the lateral direction, so as to improve the main junction electric field and enhance the terminal withstand voltage.

[0071] After ion implantation and removal of the patterned first photoresist layer, the substrate 10 is annealed, for example, at a temperature of 1050° C. to 1250° C. in a nitrogen environment, to finally form the anode region 11 and the terminal region 12 .

[0072] In step S3, please refer to Figure 3 and Figure 4 As shown, an oxide layer 13 and a passivation layer are sequentially formed on the front surface of the substrate 10 .

[0073] First, please refer to Figure 3 As shown, the oxide layer 13 is formed on the front side of the substrate 10, and the oxide layer 13 covers the substrate 10. Exemplarily, the oxide layer 13 can be formed by any suitable process such as thermal oxidation process, chemical vapor deposition (CVD), physical vapor deposition (PVD), atomic layer deposition (ALD), etc. The material of the oxide layer 13 includes but is not limited to silicon oxide. In one embodiment, the oxide layer 13 is formed by a thermal oxidation process, and the material of the oxide layer 13 is silicon oxide.

[0074] Then, a passivation layer is formed on the oxide layer 13. In one embodiment of the present invention, please refer to Figure 4 As shown, the passivation layer includes a first passivation layer 14 and a second passivation layer 15. The material of the first passivation layer 14 includes but is not limited to a BPSG layer, and the material of the second passivation layer 15 includes but is not limited to PA (Passivation, usually a silicon-containing material).

[0075] Exemplarily, the first passivation layer 14 is formed on the oxide layer 13 by any suitable process such as chemical vapor deposition, physical vapor deposition, atomic layer deposition, etc. After the deposition process, high-temperature reflow is required, for example, reflow at a high temperature of 900°C to 1100°C, to finally form a BPSG layer.

[0076] Then, a PA layer is formed on the BPSG layer. The PA layer is, for example, an inorganic oxide, nitride or oxynitride of silicon. In this embodiment, the PA layer includes a silicon dioxide layer and / or a silicon nitride layer, and can be formed by any suitable process such as chemical vapor deposition, physical vapor deposition, atomic layer deposition, etc.

[0077] In step S4, please refer to Figure 5 As shown, the passivation layer and the oxide layer 13 are etched in sequence to form a contact hole 16 exposing the anode region 11 .

[0078] In this embodiment, the second passivation layer 15 , the first passivation layer 14 , and the oxide layer 13 are sequentially etched until the anode region 11 on the front side of the substrate 10 is exposed, thereby forming a contact hole 16 .

[0079] Exemplarily, a second photoresist layer is formed on the surface of the second passivation layer 15, and the second photoresist layer is exposed and developed to form a patterned second photoresist layer. Using the patterned second photoresist layer as a mask, the second passivation layer 15, the first passivation layer 14 and the oxide layer 13 are etched in sequence to form the contact hole 16, and then the patterned second photoresist layer is removed.

[0080] In the embodiment of the present invention, after the oxide layer 13 is formed, the passivation layer is directly formed, and then the passivation layer and the oxide layer 13 are etched to form the contact hole 16, and there is no need to perform photolithography on the oxide layer separately after the oxide layer is formed as in the prior art, thereby saving a mask. In addition, in the present embodiment, the photolithography etching of the alignment mark is omitted by increasing the offset between the contact hole 16 and the anode area 11, thereby saving a mask for forming the alignment mark, that is, in the present embodiment, the mask is not used for exposure to form the alignment mark, and the alignment of the contact hole 16 and the anode area 11 is completed by increasing the offset between the contact hole 16 and the anode area 11, thereby saving the number of masks and reducing the manufacturing cost.

[0081] In step S5, please refer to Figure 6 As shown, a front metal layer 17 is formed on the front side of the substrate 10 , and the front metal layer 17 fills the contact hole 16 and contacts the anode region 11 .

[0082] The front metal layer 17 may be formed by a magnetron sputtering process or a metal deposition process. The material of the front metal layer 17 includes but is not limited to aluminum.

[0083] In one embodiment, a front metal material layer is formed, the front metal material layer fills the contact hole 16 and covers the second passivation layer 15, then a third photoresist layer is formed on the front metal material layer, the third photoresist layer is exposed and developed using a mask to form a patterned third photoresist layer, the front metal material layer is etched using the patterned third photoresist layer as a mask until a portion of the passivation layer is exposed to form a front metal layer 17, and then the patterned third photoresist layer is removed. The front metal layer 17 exposes a portion of the second passivation layer 15 on both sides of the contact hole 16.

[0084] In the embodiment of the present invention, the terminal region 12 is formed by using the lateral variable doping technology, and the deposition of the passivation layer is completed before forming the front metal layer 16, which saves a mask without affecting the reliability, and further reduces the manufacturing cost. That is, in the embodiment of the present invention, a VLD structure terminal is used, and the electric field strength at the edge of the front metal layer 17 is controlled by ion implantation (ion implantation in step S1), and the corrosion of the metal in moisture is reduced, so that the deposition of the PA layer can be completed first, and then the metal layer is deposited, thereby saving a mask (saving the photolithography etching of the PA layer) and not affecting the reliability.

[0085] Please refer to Figure 7 As shown, after forming the front metal layer 17 , the method further includes: forming a polyimide (PI) layer 18 , wherein the polyimide layer 18 covers a portion of the front metal layer 17 and fills the second passivation layer 15 exposed between adjacent front metal layers 17 .

[0086] The polyimide layer 18 has good electrical properties, chemical resistance, mechanical and thermodynamic stability, and can improve the reliability of the device as a protective layer together with the PA layer. In one embodiment of the present invention, a polyimide material layer is first formed, and the polyimide material layer covers the front metal layer 17 and the exposed passivation layer, and then a fourth photoresist layer is formed on the polyimide material layer, and then the fourth photoresist layer is exposed and developed to form a patterned fourth photoresist layer, and the patterned fourth photoresist layer is used as a mask to etch the polyimide material layer to form a polyimide layer 18, and the polyimide layer 18 exposes a portion of the front metal layer 17 above the anode area 11, and then the patterned fourth photoresist layer is removed.

[0087] Exemplarily, the polyimide material layer, i.e., PI glue, is formed by coating, and then the PI glue is subjected to curing pretreatment, such as heat treatment at about 200° C. to cure the PI glue, so as to facilitate the coating, exposure, development, etching, etc. of the photoresist. After the polyimide layer 18 is formed, imidization is also included, i.e., a polycondensation reaction occurs at above 300° C. to 400° C., the amide groups open bonds, and the ring is closed to form a stable five-ring structure.

[0088] In step S6, please refer to Figure 8 As shown, a back metal layer 19 is formed on the back side of the substrate 10 .

[0089] In one embodiment of the present invention, the surface of the substrate 10 may be thinned first, and then a back metal layer 19 may be formed on the back side of the substrate 10 .

[0090] The back metal layer 19 may be formed by a magnetron sputtering process or a metal deposition process. The material of the back metal layer 19 includes but is not limited to aluminum.

[0091] In the manufacturing method of the fast recovery diode provided by the present invention, a substrate 10 is first provided, the substrate 10 includes a front side and a back side that are arranged oppositely, then ion implantation is performed on the front side of the substrate 10 to form an anode region 11 and a terminal region 12, then an oxide layer 13 and a passivation layer are sequentially formed on the front side of the substrate 10, then the passivation layer and the oxide layer 13 are sequentially etched to form a contact hole 16 that exposes the anode region 11, then a front metal layer 17 is formed on the front side of the substrate 10, the front metal layer 17 fills the contact hole 16 and contacts the anode region 11, then a back metal layer 19 is formed on the back side of the substrate 10. After the oxide layer 13 is formed, the present invention directly forms a passivation layer, then etches the passivation layer and the oxide layer 13 to form a contact hole, and does not need to perform photolithography on the oxide layer 13 separately, and omits the photolithography etching of the alignment mark, saves the production of the alignment mark by increasing the offset between the contact hole 16 and the anode region 11, reduces the use of two mask plates in total, and reduces the manufacturing cost.

[0092] At the same time, the present invention adopts lateral variable doping technology to form the terminal area 12, and completes the deposition of the passivation layer before forming the front metal layer 17, thereby saving a mask without affecting the reliability, and further reducing the production cost.

[0093] In the embodiment of the present invention, a mask is used when ion implantation is performed on the front side of the substrate 10, when the contact hole 16 is formed, when the front metal layer 17 is formed, and when the polyimide layer 18 is formed. That is, four masks are used. Compared with the prior art, three masks are saved when forming alignment marks, when forming an oxide layer, and when forming a PA layer, thereby reducing the manufacturing cost.

[0094] Correspondingly, the present invention also provides a fast recovery diode, which is manufactured using the manufacturing method of the fast recovery diode as described above.

[0095] Please refer to Figure 8 As shown, the fast recovery diode comprises:

[0096] A substrate 10, wherein the substrate 10 includes a front surface and a back surface that are oppositely disposed;

[0097] The anode region 11 and the terminal region 12 are respectively located in the front surface of the substrate 10;

[0098] An oxide layer 13, located on the front side of the substrate 10;

[0099] A passivation layer is located on the oxide layer 13; a contact hole 16 exposing the anode region 11 is formed in the passivation layer and the oxide layer 13;

[0100] A front metal layer 17 covering the passivation layer and filling the contact hole 16; and

[0101] The back metal layer 19 is located on the back side of the substrate 10 .

[0102] In one embodiment of the present invention, the passivation layer includes a first passivation layer 14 and a second passivation layer 15 sequentially located on the oxide layer 13. The material of the first passivation layer 14 includes but is not limited to a BPSG layer, and the material of the second passivation layer 15 includes but is not limited to PA.

[0103] In one embodiment of the present invention, a polyimide layer 18 is also formed on the front metal layer 17 , and the polyimide layer 18 covers the front metal layer 18 and fills the second passivation layer 15 exposed between adjacent front metal layers 18 , and exposes a portion of the front metal layer 17 above the anode area 11 .

[0104] In summary, in the fast recovery diode and its manufacturing method provided by the present invention, a substrate is first provided, the substrate includes a front side and a back side that are arranged opposite to each other, then ion implantation is performed on the front side of the substrate to form an anode region and a terminal region, then an oxide layer and a passivation layer are sequentially formed on the front side of the substrate, then the passivation layer and the oxide layer are sequentially etched to form a contact hole exposing the anode region, then a front metal layer is formed on the front side of the substrate, the front metal layer fills the contact hole and contacts the anode region, and then a back metal layer is formed on the back side of the substrate. After forming the oxide layer, the present invention directly forms a passivation layer, then etches the passivation layer and the oxide layer to form a contact hole, and there is no need to perform photolithography on the oxide layer separately, and at the same time omits the photolithography etching of the alignment mark, and saves the production of the alignment mark by increasing the offset between the contact hole and the anode region, thereby reducing the use of two mask plates in total and reducing the production cost.

[0105] At the same time, the present invention adopts lateral variable doping technology to form the terminal area, and completes the deposition of the passivation layer before forming the front metal layer, thereby saving a mask without affecting the reliability, and further reducing the production cost.

[0106] The above description is only a description of the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention. Any changes or modifications made by a person skilled in the art in the field of the present invention based on the above disclosure shall fall within the scope of protection of the claims.

Claims

1. A method for manufacturing a fast recovery diode, characterized in that: The following steps are involved: Providing a substrate, the substrate comprising a front side and a back side arranged opposite to each other; Performing ion implantation on the front surface of the substrate to form an anode region and a terminal region; forming an oxide layer and a passivation layer in sequence on the front surface of the substrate; Sequentially etching the passivation layer and the oxide layer to form a contact hole exposing the anode region; Forming a front metal layer on the front side of the substrate, wherein the front metal layer fills the contact hole and contacts the anode region; as well as A back metal layer is formed on the back side of the substrate.

2. The method for manufacturing a fast recovery diode according to claim 1, characterized in that: The method of performing ion implantation on the front surface of the substrate to form an anode region and a terminal region comprises: forming a first photoresist layer on the substrate; exposing and developing the first photoresist layer to form a patterned first photoresist layer; Using the patterned first photoresist layer as a mask, ion implantation is performed on the substrate; and The patterned first photoresist layer is removed.

3. The method for manufacturing a fast recovery diode according to claim 1, characterized in that: The terminal region is formed by adopting a lateral variable doping technology.

4. The method for manufacturing a fast recovery diode according to claim 1, characterized in that: The passivation layer includes a first passivation layer and a second passivation layer sequentially located on the oxide layer. The material of the first passivation layer includes BPSG, and the material of the second passivation layer includes PA.

5. The method for manufacturing a fast recovery diode according to claim 1, characterized in that: The method of sequentially etching the passivation layer and the oxide layer to form a contact hole exposing the anode region comprises: forming a second photoresist layer on the passivation layer; exposing and developing the second photoresist layer to form a patterned second photoresist layer; Using the patterned second photoresist layer as a mask, etching the passivation layer and the oxide layer until the anode region is exposed; and The patterned second photoresist layer is removed.

6. The method for manufacturing a fast recovery diode according to claim 1, characterized in that: The method of forming a front metal layer on the front side of the substrate comprises: forming a front metal material layer on the front side of the substrate, wherein the front metal material layer fills the through hole and covers the passivation layer; forming a third photoresist layer on the front metal material layer; Exposing and developing the third photoresist layer to form a patterned third photoresist layer; Using the patterned third photoresist layer as a mask, etching the front metal material layer until a portion of the passivation layer is exposed; and The patterned third photoresist layer is removed.

7. The method for manufacturing a fast recovery diode according to claim 6, characterized in that: After forming the front metal layer and before forming the back metal layer, the manufacturing method further includes: forming a polyimide layer, wherein the polyimide layer covers a portion of the front metal layer and the exposed passivation layer.

8. The method for manufacturing a fast recovery diode according to claim 7, characterized in that: The method of forming the polyimide layer includes: forming a polyimide material layer, wherein the polyimide material layer covers the front metal layer and the exposed passivation layer; forming a fourth photoresist layer on the polyimide material layer; Exposing and developing the fourth photoresist layer to form a patterned fourth photoresist layer; Using the patterned fourth photoresist layer as a mask, etching the polyimide material layer to form a polyimide layer; and The patterned fourth photoresist layer is removed.

9. The method for manufacturing a fast recovery diode according to claim 1, characterized in that: After forming the front metal layer and before forming the back metal layer, the manufacturing method further includes: thinning the back side of the substrate.

10. A fast recovery diode, characterized in that: The fast recovery diode is manufactured by the manufacturing method of any one of claims 1 to 9, wherein the fast recovery diode comprises: A substrate, the substrate comprising a front side and a back side arranged opposite to each other; An anode region and a terminal region are respectively located in the front surface of the substrate; an oxide layer, located on the front side of the substrate; A passivation layer is located on the oxide layer; a contact hole exposing the anode region is formed in the passivation layer and the oxide layer; a front metal layer, covering the passivation layer and filling the contact hole; and The back metal layer is located on the back side of the substrate.

Images