JP2017130590A - Semiconductor device and manufacturing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor device in which contamination of a contact face is inhibited and which has favorable Schottky junction; and provide a manufacturing method of the semiconductor device.SOLUTION: A semiconductor device comprises: a semiconductor substrate 10 having a first principal surface and a second principal surface which are opposite to each other; a Schottky electrode 20 which is arranged on a contact face defined in part of the first principal surface and forms Schottky junction with the semiconductor substrate 10; a silicide film 30 formed in a remaining area of the contact face by silicidation of part of the surface of the semiconductor substrate 10; and a cover film 40 which is arranged on the surface of the semiconductor substrate 10 to cover the silicide film 30 and composed of a material which is more chemically stabile than the silicide film 30 with respect to a chemical used for cleaning of the contact face.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a semiconductor device having a Schottky junction and a silicide film, and a manufacturing method thereof.

  A silicide film in which a part of a semiconductor layer is silicided is used in a semiconductor device. For example, a nickel (Ni) -based silicide film is used as an electrode of a semiconductor device using silicon carbide (SiC). A nickel silicide film (Ni silicide film) made of Ni and silicon (Si) can be easily formed by a method in which a silicon carbide substrate (SiC substrate) and a Ni film are directly reacted at a high temperature and has a low contact resistance. It is a good ohmic electrode. In order to form a Ni silicide film by reacting Ni and Si and to obtain a good ohmic electrode, heat treatment at 925 ° C. or higher is required. Generally, a heat treatment at about 900 ° C. to 1000 ° C. is performed to obtain ohmic contact.

  On the other hand, a metal such as titanium or molybdenum generally used as a Schottky electrode forms a Schottky junction by a heat treatment at about 400 ° C. to 700 ° C. At this time, when heated at a temperature higher than about 900 ° C., the reaction between these metals and the semiconductor layer proceeds, and the desired alloy state forming the Schottky junction interface cannot be obtained.

  For this reason, in a semiconductor device having a Schottky junction, it is necessary to form a Schottky junction after forming a silicide film because of the heating temperature. For example, after forming a silicide film as an electrode on the back surface of the semiconductor device, a Schottky electrode constituting a Schottky junction is formed (see, for example, Patent Document 1).

Japanese Patent No. 5046083

  The Schottky junction is formed at the contact interface between the metal film and the semiconductor layer, or at the contact interface between the metal reaction layer formed by reacting the metal film with the semiconductor layer and the semiconductor layer. At this time, it is preferable that the contact surface of the semiconductor layer before the metal film is disposed is in a pure state that is not contaminated by dirt or foreign matter. On the other hand, if there is dirt or foreign matter on the contact surface of the semiconductor layer, good formation of the Schottky junction is hindered. For example, a foreign substance at the contact interface becomes a leak current generation point, and the reverse leak current of the Schottky barrier diode (SBD) increases.

  Therefore, in order to form a good Schottky junction, it is important that the contact surface of the semiconductor layer is not contaminated. For example, cleaning (cleaning) for bringing the contact surface into a pure state is performed as a pretreatment immediately before the step of forming the Schottky junction.

  By the way, when the silicide film needs to be formed before the formation of the Schottky junction as described above, the pretreatment for obtaining a pure contact surface is performed in a state where the silicide film is formed. For this reason, the substance formed on the silicide film during the process dissolves in the chemical used in the pretreatment and becomes discrete as particles, and adheres to the surface of the semiconductor layer before forming the Schottky junction and contacts the surface. May contaminate.

  In view of the above problems, an object of the present invention is to provide a semiconductor device having a good Schottky junction in which contamination of a contact surface is suppressed and a method for manufacturing the same.

  According to one aspect of the present invention, (a) a semiconductor substrate having a first main surface and a second main surface facing each other, and (a) a contact surface defined as a part of the first main surface, A Schottky electrode for forming a Schottky junction with the semiconductor substrate; (c) a silicide film formed by silicidation of a part of the surface of the semiconductor substrate in the remaining region of the contact surface; and (d) a silicide film. And a cover film made of a material that is chemically more stable than the silicide film with respect to the chemical used for cleaning the contact surface, which is disposed on the surface of the semiconductor substrate.

  According to another aspect of the present invention, (a) a semiconductor having a first main surface in which a contact surface on which a Schottky electrode is disposed is defined as a part thereof, and a second main surface facing the first main surface (B) forming a silicide film by siliciding a part of the surface of the semiconductor substrate in the remaining area of the contact surface; and (c) covering the silicide film on the surface of the semiconductor substrate. A step of disposing a cover film; (d) a step of cleaning the contact surface by chemical pretreatment after forming the cover film; and (e) a Schottky electrode disposed on the contact surface after pretreatment, Forming a Schottky junction between the semiconductor substrate and the Schottky electrode, wherein the cover film is made of a material that is chemically more stable than the silicide film with respect to the chemical used in the pretreatment. Made A method is provided.

  ADVANTAGE OF THE INVENTION According to this invention, the contamination of a contact surface is suppressed and the semiconductor device which has a favorable Schottky junction, and its manufacturing method can be provided.

It is a typical sectional view showing the composition of the semiconductor device concerning the embodiment of the present invention. It is typical sectional drawing which shows the structure of the contact surface vicinity of the semiconductor device which concerns on embodiment of this invention. It is typical process sectional drawing for demonstrating the manufacturing method of the semiconductor device which concerns on embodiment of this invention (the 1). It is typical process sectional drawing for demonstrating the manufacturing method of the semiconductor device which concerns on embodiment of this invention (the 2). FIG. 9 is a schematic process cross-sectional view for explaining the manufacturing method of the semiconductor device according to the embodiment of the present invention (No. 3). FIG. 10 is a schematic process cross-sectional view for explaining the manufacturing method of the semiconductor device according to the embodiment of the present invention (No. 4). FIG. 10 is a schematic process cross-sectional view for explaining the manufacturing method of the semiconductor device according to the embodiment of the present invention (No. 5). FIG. 6 is a schematic process cross-sectional view for explaining the manufacturing method of the semiconductor device according to the embodiment of the present invention (No. 6). It is typical process sectional drawing for demonstrating the manufacturing method of the semiconductor device which concerns on embodiment of this invention (the 7). It is typical process sectional drawing for demonstrating the manufacturing method of the semiconductor device which concerns on embodiment of this invention (the 8). It is typical process sectional drawing for demonstrating the manufacturing method of the semiconductor device which concerns on embodiment of this invention (the 9). It is typical sectional drawing which shows the structural example of the back surface pad electrode of the semiconductor device which concerns on embodiment of this invention.

  Next, an embodiment of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic, and the ratio of the thickness of each layer is different from the actual one. Therefore, specific thicknesses and dimensions should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

  Further, the embodiments described below exemplify apparatuses and methods for embodying the technical idea of the present invention, and the embodiments of the present invention are materials, shapes, structures, arrangements, etc. of components. Is not specified as follows. The embodiment of the present invention can be variously modified within the scope of the claims.

  As shown in FIG. 1, the semiconductor device 1 according to the embodiment of the present invention is defined as a semiconductor substrate 10 having a first main surface 101 and a second main surface 102 facing each other, and a part of the first main surface 101. A Schottky electrode 20 which is disposed on the contact surface and forms a Schottky junction with the semiconductor substrate 10, and a silicide formed by siliciding a part of the surface of the semiconductor substrate 10 in the remaining region of the contact surface A film 30 and a cover film 40 that covers the silicide film 30 and is disposed on the surface of the semiconductor substrate 10 are provided.

  For example, the silicide film 30 is formed by siliciding a part of the surface of the semiconductor substrate 10 in at least one of the remaining region of the contact surface in the first main surface 101 and the second main surface 102. In the semiconductor device 1 shown in FIG. 1, the surface silicide film 31 is formed in the remaining region of the contact surface of the first main surface 101. A backside silicide film 32 is formed on the second main surface 102. The cover film 40 that covers the surface silicide film 31 is referred to as a front cover film 41, and the cover film 40 that covers the back silicide film 32 is referred to as a back cover film 42. The silicide film 30 is a generic term for silicide films formed on the semiconductor substrate 10, and the cover film 40 is a generic term for cover films disposed on the surface of the semiconductor substrate 10.

  The semiconductor substrate 10 shown in FIG. 1 has a structure in which a low-concentration n-type semiconductor layer 12 is stacked on a high-concentration n-type semiconductor substrate 11. For example, the semiconductor substrate 11 is a SiC substrate, and the semiconductor layer 12 is an epitaxial growth layer. As shown in FIG. 1, the semiconductor layer 12 has a first main surface 101, and the semiconductor substrate 11 has a second main surface 102. In the semiconductor device 1, a main current flows in the thickness direction of the semiconductor substrate 10 between the Schottky electrode 20 disposed on the first main surface 101 and the backside silicide film 32 disposed on the second main surface 102. SBD. More specifically, a voltage is applied between the front surface pad electrode 50 disposed on the Schottky electrode 20 and the rear surface pad electrode 60 disposed on the back surface silicide film 32, and a main current flows through the semiconductor substrate 10.

  The semiconductor device 1 further includes a guard ring 210 disposed on a part of the upper portion of the semiconductor substrate 10 on the first main surface 101 so as to surround the periphery of the contact surface on which the Schottky electrode 20 is disposed. The guard ring 210 forms a pn junction with the semiconductor substrate 10. That is, the semiconductor layer 12 and the guard ring 210 have different conductivity types, for example, the semiconductor layer 12 is n-type, and the guard ring 210 is p-type.

  The guard ring 210 alleviates the electric field concentration at the end of the contact surface. Thereby, destruction of the semiconductor device 1 due to electric field concentration can be prevented. The depth and width of the guard ring 210 are appropriately set according to the structure of the semiconductor device 1 and the required breakdown voltage. In order to prevent the breakdown voltage of the semiconductor device 1 from decreasing, an electric field relaxation ring (Field Limiting Ring: FLR) 220 may be formed outside the guard ring 210 as shown in FIG.

  The surface silicide film 31 is disposed between the guard ring 210 and the surface pad electrode 50. The surface silicide film 31 can reduce the electrical resistance between the guard ring 210 and the surface pad electrode 50. A material that is in ohmic contact with the guard ring 210 is selected for the surface silicide film 31. Further, the electrical resistance between the back surface pad electrode 60 and the semiconductor substrate 10 can be reduced by the back surface silicide film 32 formed on the second main surface 102. A material that is in ohmic contact with the semiconductor substrate 11 is selected for the backside silicide film 32.

  As shown in FIG. 2, the entire surface silicide film 31 and the surface cover film 41 are disposed above the guard ring 210 around the Schottky electrode 20 disposed on the contact surface 110. That is, the surface silicide film 31 and the surface cover film 41 are disposed inside the guard ring 210 in plan view. For this reason, the surface cover film 41 is not in contact with the semiconductor layer 12 outside the guard ring 210. By preventing the surface cover film 41 from contacting the semiconductor substrate 10 in a region other than the guard ring 210, it is possible to prevent unnecessary Schottky junctions from being formed in the semiconductor device 1.

  Typical Schottky electrode materials used for SiC-SBD in which a semiconductor layer is epitaxially grown on a SiC substrate are titanium (Ti), molybdenum (Mo), nickel (Ni), and the like. After the Schottky electrode 20 made of these metals is formed on the contact surface 110 of the semiconductor substrate 10, a heat treatment at about 400 ° C. to 700 ° C. is performed in order to obtain a stable Schottky junction. By this heat treatment, the semiconductor substrate 10 and the metal film react to form a very thin metal reaction layer. At this time, if the contact surface of the semiconductor substrate 10 is not in a pure state, the reaction is inhibited, the metal reaction layer becomes non-uniform, and the formation of the Schottky junction becomes unstable.

  In order to make the contact surface of the semiconductor substrate 10 pure, for example, a process called “sacrificial oxidation” for forming a thermal oxide film on the surface of the semiconductor substrate 10 is performed. Contamination and foreign matter generated on the contact surface are taken into the thermal oxide film formed by sacrificial oxidation. For this reason, a contact surface can be made into a pure state by removing a thermal oxide film. Furthermore, the contact surface 110 can be made more pure by pretreatment using chemicals, such as exposing the contact surface 110 to a treatment solution such as aqueous ammonium peroxide or dilute hydrofluoric acid immediately before forming the metal film. .

  As already described, the silicide film 30 needs to be formed before the formation of the Schottky junction due to the relationship of the set temperature of the heat treatment. Therefore, the pretreatment for obtaining the contact surface 110 in a pure state is performed with the silicide film 30 formed. For this reason, the silicide film 30 is exposed to the chemical used in the pretreatment. Ni silicide films and the like have a certain resistance to chemicals used for these pretreatments. However, an oxide or the like formed on the silicide film 30 during the process may be partially dissolved by the processing solution into particles and dispersed in the processing solution. These particles cause contamination of the surface of the semiconductor substrate 10 by reattaching to the surface of the semiconductor substrate 10.

  Depending on the preprocessing conditions, a large amount of particles may be generated. For this reason, in particular, in a vertical structure semiconductor device in which a main current flows in the thickness direction of the semiconductor substrate, such as a SiC power device, a silicide film may be formed as an electrode on the entire back surface. There is concern about the effects of particle generation.

  However, in the semiconductor device 1 shown in FIG. 1, the silicide film 30 is covered with the cover film 40. For this reason, generation | occurrence | production of the particle in the silicide film | membrane 30 in the pre-process just before forming a Schottky junction can be suppressed. Therefore, even when the Schottky junction is formed after the silicide film 30 is formed, the contact surface is kept in a pure state.

  In order to suppress the generation of particles in the pretreatment, the material of the cover film 40 is a material that is chemically stable with respect to chemicals used for cleaning the contact surface as a pretreatment for forming a Schottky junction. Is selected. At least, the cover film 40 is made of a material that is chemically more stable than the silicide film 30 with respect to the chemicals used for the pretreatment. For example, when the silicide film 30 is a nickel silicide film or the like, a platinum (Pt) film is preferably used for the cover film 40.

  As a countermeasure against contamination of the contact surface 110 with particles generated from the silicide film 30, a method of forming a Schottky junction by shortening the pretreatment time can be considered. However, if the pretreatment time is shortened, there is a problem that cleaning becomes insufficient and foreign matter remains on the contact surface 110.

  The semiconductor device 1 shown in FIG. 1 has a front surface silicide film 31 formed on the first main surface 101 and a back surface silicide film 32 formed on the second main surface 102. However, it may be a semiconductor device in which only one of the front surface silicide film 31 and the back surface silicide film 32 is formed.

  Below, with reference to drawings, the manufacturing method of the semiconductor device 1 which concerns on embodiment of this invention is demonstrated. In addition, the manufacturing method of the semiconductor device 1 described below is an example, and it is needless to say that it can be realized by various other manufacturing methods including this modification.

First, the semiconductor substrate 10 is prepared. For example, as shown in FIG. 3, the semiconductor substrate 10 is configured by forming an n-type semiconductor layer 12 on a semiconductor substrate 11. The thickness of the semiconductor layer 12 is set according to the breakdown voltage required for the semiconductor device 1. For example, the semiconductor substrate 11 is an n-type substrate having a substrate specific resistance of about 0.02 Ω · cm. The semiconductor layer 12 is a semiconductor layer having a thickness of 5 to 10 μm and an impurity concentration of about 5.0 × 10 ^{15 to} 15.0 × 10 ¹⁵ atoms / cm ³ epitaxially grown on the semiconductor substrate 11.

  Next, a p-type guard ring 210 is formed around the contact surface 110. Note that the FLR 220 may be formed outside the guard ring 210 in order to improve the breakdown voltage. For example, the guard ring 210 and the FLR 220 are formed by ion implantation of p-type impurities such as boron (B) and aluminum (Al) and activation annealing.

  Thereafter, as shown in FIG. 4, the first main surface 101 and the second main surface 102 of the semiconductor substrate 10 are thermally oxidized to form a thermal oxide film 70. In addition, before forming the thermal oxide film 70, it is preferable to remove dirt and foreign matter on the surface of the semiconductor substrate 10 by sacrificial oxidation. By forming the thermal oxide film 70 after the sacrificial oxidation, a clean thermal oxide film 70 that is flat and has few defect levels is obtained on the surface of the semiconductor substrate 10. Thereby, the fixed charge on the surface of the semiconductor device 1 can be reduced. For this reason, for example, when the electric field relaxation structure for improving the breakdown voltage is formed in the outer peripheral region around the active region in the semiconductor device 1, the balance of the electric field applied when applying the breakdown voltage becomes more stable. Can withstand pressure.

  Next, an interlayer insulating film 80 is formed on the thermal oxide film 70 formed on the first main surface 101 by a chemical vapor deposition (CVD) method or the like. The interlayer insulating film 80 is, for example, a silicon oxide film, a silicon nitride film, an NSG film, a PSG film, or the like.

  Next, a silicide film 30 is formed by siliciding a part of the surface of the semiconductor substrate 10 in the remaining region of the contact surface 110 where the Schottky electrode 20 is disposed. That is, the surface silicide film 31 is formed on the guard ring 210 for electrical connection between the guard ring 210 and the surface pad electrode 50. For example, as shown in FIG. 5, a part of the thermal oxide film 70 and the interlayer insulating film 80 on the first main surface 101 is removed by photolithography technique and etching, and the upper surface of the guard ring 210 is selectively exposed. . Then, after a nitride film (not shown) is formed on the guard ring 210 and patterned, the nitride film and the semiconductor substrate 10 are reacted by heat treatment to form a surface silicide film 31 as shown in FIG.

  Further, as shown in FIG. 6, a backside silicide film 32 is formed on the second main surface 102 of the semiconductor substrate 10. Specifically, after removing the thermal oxide film 70 on the second main surface 102 by etching, a nitride film (not shown) is formed. Then, the backside silicide film 32 is formed by reacting the nitride film and the semiconductor substrate 10 by heat treatment.

  The thickness of the silicide film 30 is about 10 nm. Note that while one of the front surface silicide film 31 and the back surface silicide film 32 is formed, the other may be covered and protected by a resist film or the like. Further, the heat treatment for forming the front surface silicide film 31 and the back surface silicide film 32 may be performed simultaneously.

  Next, as shown in FIG. 7, a cover film 40 that covers the silicide film 30 is formed. For the cover film 40, a Pt film having a thickness of about 50 nm to 100 nm is preferably used. For example, after a Pt film is formed on the entire surface on the first main surface 101 side, the surface cover film 41 is formed by leaving the Pt film only in a portion covering the surface silicide film 31 by photolithography technique and etching. The surface silicide film 31 and the surface cover film 41 are formed so as to be disposed inside the guard ring 210 in plan view. Further, a back cover film 42 is formed on the second main surface 102 of the semiconductor substrate 10 so as to cover the entire surface of the back silicide film 32.

  Thereafter, the thermal oxide film 70 and the interlayer insulating film 80 formed on the first main surface 101 are selectively removed so that the contact surface 110 is exposed. At this time, as shown in FIG. 8, the surface oxide film 31 and the thermal oxide film 70 and the interlayer insulating film 80 above the surface cover film 41 disposed on the guard ring 210 are also removed.

  Next, the contact surface 110 is cleaned by a pretreatment using a chemical such as ammonium peroxide water or dilute hydrofluoric acid to make the contact surface 110 pure. Then, as shown in FIG. 9, the Schottky electrode 20 is formed on the contact surface 110. At this time, heat treatment may be performed as necessary to stabilize the contact interface of the Schottky junction. For example, the semiconductor substrate 10 and the Schottky electrode 20 are reacted by performing heat treatment in an inert atmosphere gas or a reducing atmosphere gas at 400 ° C. to 650 ° C. for 5 minutes to 30 minutes. The thickness of the Schottky electrode 20 is, for example, about 50 nm to 200 nm.

  Further, as shown in FIG. 10, the surface pad electrode 50 is formed so as to be connected to the Schottky electrode 20 and the exposed surface cover film 41. For example, the surface pad electrode 50 is patterned so that the end portion overlaps the interlayer insulating film 80 surrounding the contact surface 110 and the guard ring 210. As the surface pad electrode 50, for example, a structure in which a first surface electrode 51 and a second surface electrode 52 are stacked as shown in FIG. 10 can be used. The second surface electrode 52 is, for example, an Al film, an AlSi film, an AlCu film, or the like. The first surface electrode 51 is disposed to prevent Al from diffusing from the second surface electrode 52. For the first surface electrode 51, for example, a Ti film, a TiN film, a Ni film, a Mo film, or the like is used as a single layer or a plurality of layers.

  Thereafter, as shown in FIG. 11, a protective film 90 is formed. As the protective film 90, for example, a SiN film, an NSG film, or a structure in which a PSG film and a polyimide film are stacked and formed by a CVD method and having a thickness of 100 nm to 2 μm can be used. Then, the protective film 90 above the Schottky electrode 20 is opened by the photolithography technique, and the surface of the surface pad electrode 50 is exposed. By disposing the protective film 90 on the first main surface 101, it is possible to prevent moisture from entering the semiconductor device 1 and enhance mechanical protection.

  Further, the back surface pad electrode 60 is formed on the second main surface 102 of the semiconductor substrate 10 so as to cover the back surface cover film 42. The back pad electrode 60 is preferably made of a material that is in close contact with the back cover film 42. For example, as shown in FIG. 12, a back surface pad electrode 60 having a structure in which a Ti film 61, a Ni film 62, and an Au film 63 are stacked is used. The Ti film 61 is disposed for improving adhesion with the back cover film 42. The Ni film 62 is for solder bonding at the back surface pad electrode 60 during mounting such as wire bonding. The Au film 63 prevents the back surface pad electrode 60 from being oxidized.

  Thus, the semiconductor device 1 shown in FIG. 1 is completed. In the above description, the interlayer insulating film 80 is formed immediately after the thermal oxide film 70 is formed. However, depending on the intended structure of the interlayer insulating film 80, the interlayer insulating film 80 is formed after the surface silicide film 31 is formed. Also good.

  Pt has excellent resistance to aqueous ammonium peroxide, dilute hydrofluoric acid, hot concentrated sulfuric acid, and the like. Therefore, by using a Pt film for the cover film 40 that covers the silicide film 30 such as the Ni silicide film, the silicide film 30 is formed in the chemical treatment from after the silicide film 30 is formed to just before the Schottky electrode 20 is formed. Are prevented from being exposed to the respective chemicals. For this reason, generation of particles from the silicide film 30 can be prevented. Therefore, according to the method for manufacturing the semiconductor device 1 described above, the contact surface 110 of the semiconductor substrate 10 is prevented from being contaminated by particles. Other than the Pt film, a chemically stable material such as an Au film can be used for the cover film 40.

  As shown in FIG. 9, it is preferable that the outer edge portion of the Schottky electrode 20 overlaps a part of the inside of the guard ring 210. By overlapping Schottky electrode 20 and guard ring 210, exposure of contact surface 110 can be completely prevented. For this reason, in the manufacturing process of the semiconductor device 1, after the Schottky electrode 20 is formed, the Schottky electrode 20 serves as a mask, and the contact surface 110 can be prevented from being etched.

  In the above description, the case where the surface cover film 41 covering the surface silicide film 31 and the back surface cover film 42 covering the back surface silicide film 32 are formed has been described as an example. However, depending on the structure of the semiconductor device 1 and the manufacturing method, the front cover film 41 or the back cover film 42 may not be formed. For example, when the Ni film is formed by laser annealing between the semiconductor substrate 10 and the back surface pad electrode 60 without forming the back surface silicide film 32, the back surface cover film 42 need not be formed.

On the other hand, when the silicide film 30 is formed in a region other than the upper surface of the guard ring 210 and the second main surface 102, the cover film 40 covering the silicide film 30 is formed. Thereby, a good Schottky junction can be formed.
(Other embodiments)
As described above, the present invention has been described according to the embodiments. However, it should not be understood that the descriptions and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  For example, the material of the semiconductor substrate 10 is not limited to SiC. That is, the present invention can be applied to a semiconductor device in which the silicide film 30 is formed regardless of the material of the semiconductor substrate 10.

  Moreover, although the case where the semiconductor device 1 was SBD was shown above, this invention is applicable to the semiconductor device which has Schottky junction other than SBD. For example, the semiconductor device 1 includes a semiconductor having a junction barrier Schottky (JBS) structure diode, or a diode having an MPS (Merged PiN Schottoky) structure in which a pn junction region is added to an SBD and a Schottky junction and a pn junction are provided. A semiconductor device having the SBD may be used.

  As described above, the present invention naturally includes various embodiments not described herein. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

DESCRIPTION OF SYMBOLS 1 ... Semiconductor device 10 ... Semiconductor base | substrate 11 ... Semiconductor substrate 12 ... Semiconductor layer 20 ... Schottky electrode 30 ... Silicide film 31 ... Surface silicide film 32 ... Back surface silicide film 40 ... Cover film 41 ... Surface cover film 42 ... Back surface cover film 50 ... front surface pad electrode 60 ... back surface pad electrode 70 ... thermal oxide film 80 ... interlayer insulating film 90 ... protective film 101 ... first main surface 102 ... second main surface 110 ... contact surface 210 ... guard ring

Claims (6)

A semiconductor substrate having a first main surface and a second main surface facing each other;
A Schottky electrode disposed on a contact surface defined as a part of the first main surface and forming a Schottky junction with the semiconductor substrate;
A silicide film formed by siliciding a part of the surface of the semiconductor substrate in the remaining region of the contact surface;
A cover film made of a material which is disposed on the surface of the semiconductor substrate so as to cover the silicide film and which is chemically more stable than the silicide film with respect to a chemical used for cleaning the contact surface. A featured semiconductor device.   The semiconductor device according to claim 1, wherein the cover film is a platinum film. A guard ring that is disposed on a part of the upper portion of the semiconductor substrate so as to surround the contact surface on the first main surface, and that forms a pn junction with the semiconductor substrate;
A surface silicide film is formed as the silicide film on the first main surface, and the entirety of each of the cover film covering the surface silicide film and the surface silicide film is disposed above the guard ring. The semiconductor device according to claim 1 or 2. Providing a semiconductor substrate having a first main surface in which a contact surface on which a Schottky electrode is disposed is defined as a part thereof, and a second main surface opposite to the first main surface;
Forming a silicide film by siliciding a part of the surface of the semiconductor substrate in the remaining region of the contact surface;
Disposing a cover film on the surface of the semiconductor substrate covering the silicide film;
After forming the cover film, washing the contact surface by a pretreatment using a chemical;
Placing the Schottky electrode on the contact surface after the pretreatment and forming a Schottky junction between the semiconductor substrate and the Schottky electrode; and
The method of manufacturing a semiconductor device, wherein the cover film is made of a material that is chemically more stable than the silicide film with respect to the chemical used in the pretreatment.   The method of manufacturing a semiconductor device according to claim 4, wherein the cover film is a platinum film. A step of disposing a guard ring forming a pn junction with the semiconductor substrate at a part of the upper portion of the semiconductor substrate so as to surround the contact surface on the first main surface;
A surface silicide film is formed as the silicide film on the first main surface, and the entire cover film covering the surface silicide film and the surface silicide film is disposed above the guard ring. Item 6. A method for manufacturing a semiconductor device according to Item 4 or 5.

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