JP2014011177A - Semiconductor device - Google Patents

Abstract

Provided is a semiconductor device in which each electrode constituting the semiconductor device can be formed by a simple method.
A semiconductor substrate having a first conductivity type semiconductor layer on a surface, a second conductivity type diffusion region formed by diffusing a second conductivity type impurity at a low concentration on the semiconductor layer, and the diffusion A Schottky metal formed on the region; a first electrode formed on the surface of the Schottky metal; and a second electrode formed on the back surface of the semiconductor substrate, wherein the first electrode and the second electrode are the same metal. Made of material.
[Selection] Figure 1

Description

  The present invention relates to a semiconductor device, and more particularly to a semiconductor device suitable for forming a rectifying element such as a diode.

In recent years, the amount of CO ₂ emitted by automobiles has been regulated, and accordingly, an alternator driven by an engine is desired to have a rectifying element with reduced loss generated during rectification.

  Patent Document 1 proposes a composite rectifying element capable of mass production having both a PN junction and a Schottky junction as such an element.

JP-A-3-250670

  The composite rectifying element as described above is manufactured by a method as shown in FIG. 3, for example. First, an epitaxial layer 2 and a silicon oxide film 6 are formed on a high-concentration N-type substrate 1, and then a P-type impurity is diffused through an opening formed in the oxide film to form a P-type diffusion layer 4 (FIG. 3a).

  Next, after the silicon oxide film 6 is removed, P-type impurities are diffused at a low concentration to form a low-concentration P-type diffusion layer 5 between the P-type diffusion layers 4 (FIG. 3b). Next, a Schottky metal 7 is formed on the P-type diffusion layer 4 and the low-concentration P-type diffusion layer 5 by vapor deposition or sputtering (FIG. 3c).

  Thereafter, solder electrodes 8 and 9 are formed on the Schottky metal 7 by vapor deposition or sputtering (FIG. 3d). Thereafter, the Schottky metal 7 and the solder electrodes 8 and 9 attached on the silicon oxide film 6 are removed by using a photolithography technique. Thereafter, solder electrodes 10 and 11 are formed on the back surface (FIG. 3e).

  As described above, when the composite element is formed, after forming the diffusion layer on the substrate, the Schottky metal is formed using the vapor deposition method or the sputtering method, and the solder electrode is formed thereon using the vapor deposition method or the sputtering method. . Thereafter, the Schottky metal and the solder electrode adhering to the insulating film are removed using a photolithography technique, and then a solder electrode is formed on the back surface.

  According to this method, the electrode forming operation using the vacuum evaporation method or the sputtering method must be performed twice for forming the anode electrode and the cathode electrode.

  The present invention has been made in view of such a problem, and provides a semiconductor device in which each electrode constituting the semiconductor device can be formed by a simple method.

  In order to solve the above problems, the present invention employs the following means.

  A semiconductor substrate having a first conductivity type semiconductor layer on the surface, a first conductivity type diffusion region formed by diffusing a second conductivity type impurity at a low concentration on the semiconductor layer, and formed on the diffusion region A Schottky metal, a first electrode formed on the surface of the Schottky metal, and a second electrode formed on the back surface of the semiconductor substrate, wherein the first electrode and the second electrode are formed of the same metal material. .

  Since the present invention has the above-described configuration, each electrode constituting the semiconductor device can be formed by a simple method.

It is a figure explaining the semiconductor device concerning a 1st embodiment. It is a figure explaining the semiconductor device concerning a 2nd embodiment. It is a figure explaining the conventional semiconductor device. It is a figure explaining junction potential.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

(Embodiment 1)
The first embodiment will be described with reference to FIG. FIG. 1 is a diagram for explaining a diode that is a semiconductor device according to the present embodiment and a method for manufacturing the diode.

  First, an N-type epitaxial layer 2 and a silicon oxide film 6 having a lower concentration than the high-concentration N-type substrate 1 are formed on the high-concentration N-type substrate 1, and an opening is formed in the silicon oxide film layer 6. A plurality of N-type diffusion layers 3 having a higher concentration than that of the N-type epitaxial layer 2 are formed in an island shape by diffusing the N-type impurities (FIG. 1a). Next, after the opening is enlarged, P-type impurities are diffused through the opening, and a plurality of P-type diffusion layers 4 having a higher concentration than the N-type epitaxial layer 2 are formed in an island shape, and the upper part of the N-type diffusion layer 3 is included. To form. At this time, a PN junction A is formed by the P-type diffusion layer 4 and the N-type diffusion layer 3 (FIG. 1b).

  The planar shape of the P-type diffusion layer 4 and the N-type diffusion layer 3 is a circle or a stripe.

  Next, after removing the silicon oxide film 6, P-type impurities are diffused at a low concentration, and a low-concentration P-type diffusion layer 5 having a lower concentration than the P-type diffusion layer 4 is formed between the P-type diffusion layers 4. Form (FIG. 1c).

  Next, a Schottky electrode 7 is formed on the P-type diffusion layer 4 and the low-concentration P-type diffusion layer 5 by vapor deposition or sputtering, and a Schottky junction is formed between the P-type diffusion layer 4 and the low-concentration P-type diffusion layer 5. B is formed (FIG. 1d). An ohmic junction C is formed between the P-type diffusion layer 4 and the Schottky electrode 7. Moreover, as the shiyoto key electrode 7, metals, such as molybdenum, titanium, platinum, can be used.

  4A and 4B are diagrams for explaining the junction potential. FIG. 4A is a diagram showing the junction potential according to the prior art, and FIG. 4B is a diagram showing the junction potential according to the present invention.

  As shown in FIG. 4B, a P− layer (corresponding to the low-concentration P-type diffusion layer 5) is provided under the Schottky electrode by using the ion implantation method, and the Schottky junction is not a metal / silicon interface, but P -Since it is formed inside the silicon in the layer, an increase in leakage current due to damage of the Schottky electrode / silicon interface can be prevented, and the Schottky junction height is selected according to the ion implantation amount of the P- layer. It becomes possible.

  Next, the substrate on which the Schottky electrode is thus formed is immersed in a plating solution (for example, a Ni plating solution). By dipping in the plating solution, an anode electrode 8 is formed on the Schottky electrode 7 on the substrate surface, and a cathode electrode 9 is formed on the back surface (lower surface) of the substrate 1 (FIG. 1e).

  Thus, in this embodiment, since the anode electrode 8 and the cathode electrode 9 are formed using a plating method (electroless Ni plating), the anode electrode 8 and the cathode electrode can be obtained only by immersing the substrate in the plating solution. 9 can be formed.

  Further, since the plating solution does not adhere onto the silicon oxide film 6 which is an insulating film, it is not necessary to remove the metal using the photolithography technique as in the conventional technique. For this reason, the manufacturing process can be simplified, and the manufacturing cost of the semiconductor device can be reduced.

  As described above, according to the present embodiment, the anode electrodes 8 and 9 are formed on the Schottky electrode 7 by using the conventional technique (vacuum deposition method or sputtering method, and further, the vacuum deposition method or Unlike the case where the cathode electrodes 10 and 11 are formed by using the sputtering method, the anode electrode 8 and the cathode electrode 9 are formed by using the plating method. The electrode 8 and the cathode electrode 9 can be easily formed. Moreover, since the plating solution does not adhere to the insulating film (silicon oxide film) 6 formed for separating the anode electrode 8, it is possible to omit the trouble of removing the formed electrode material. .

(Embodiment 2)
A second embodiment will be described with reference to FIG. In the first embodiment shown in FIG. 1, an example in which a metal material such as molybdenum, titanium, or platinum (a material different from the material constituting the anode electrode or the cathode electrode) is used as the material constituting the Schottky electrode is shown. .

  In the present embodiment, the same material as that constituting the anode electrode or cathode electrode of the diode is used as the material constituting the Schottky electrode. Further, a plating method is used for forming each electrode.

  In this example, the anode electrode 8 can be formed on the low-concentration P-type diffusion layer 5 and the P-type diffusion layer 4 constituting the Schottky barrier diode on the substrate surface, and at the same time, the cathode electrode can be formed on the back surface of the substrate. . That is, the Schottky electrode, the anode electrode, and the cathode electrode can be formed by the work of once immersing the semiconductor substrate in the plating solution.

  In FIG. 2, first, an N-type epitaxial layer 2 and a silicon oxide film layer 6 are formed on a high-concentration N-type substrate 1, and then N-type impurities are diffused through openings formed in the oxide film layer. 3 is formed (FIG. 2a). Next, after expanding the opening, a P-type impurity is diffused through the opening to form a P-type diffusion layer 4 and a PN junction A is formed (FIG. 2b).

  Next, after removing the silicon oxide film 6, P-type impurities are diffused to form a low concentration P-type diffusion layer 5 between the P-type diffusion layers 4 (FIG. 2c).

  Next, the substrate on which the diffusion layer is thus formed is immersed in a plating solution (for example, a Ni plating solution). By dipping in the plating solution, a plating layer is formed on the region where the diffusion layer is formed on the substrate surface and on the back surface of the substrate. The plating layer formed on the surface of the substrate functions as the Schottky electrode and the anode electrode 7A, and the plating layer formed on the back surface of the substrate functions as the cathode electrode 9 (FIG. 2d).

  Thus, when the material constituting the Schottky electrode, the material constituting the anode electrode, and the material constituting the cathode electrode are selected to be the same material, the Schottky electrode, the anode electrode, and the cathode electrode are simultaneously formed. can do.

  Similarly to the first embodiment, no electrode material is formed on the insulating film (silicon oxide film 6) formed to separate the anode electrode 8. For this reason, the trouble of removing this can be omitted.

  In this example, the Shiyoto key electrode 7 and the cathode electrode 8 are the same metal, and this metal forms a Schottky junction B with the low concentration P type diffusion layer 5, and the high concentration P type diffusion layer 4. Between the two, an ohmic junction C is formed.

  In the first embodiment, the metal is different between the shiyotaki key electrode 7 and the anode electrode 8, and therefore, the electrode formation must be performed in two steps. However, in the second embodiment, the Schottky electrode 7, the anode electrode 8, and the cathode electrode 9 are formed of the same metal material. Therefore, the Schottky electrode 7, the anode electrode 8, and the cathode electrode 9 can be formed simultaneously. Further, since the electrode does not adhere on the insulating film (silicon oxide film), the manufacturing process can be further simplified and the cost of the semiconductor device can be reduced.

As described above, according to the present embodiment, the Schottky electrode, the anode electrode, and the cathode electrode can be formed by a single operation. As a result, the manufacturing process can be simplified and the manufacturing cost of the semiconductor device can be reduced. The present invention is not limited to the above-described embodiment, and includes various modifications. For example, the above-described embodiment has been described in detail for easy understanding of the present invention, and is not necessarily limited to one having all the configurations described. For example, a diode that does not form the N-type diffusion layer 3 as in the prior art shown in FIG. In addition, the conductivity types shown in the above description are merely examples, and the same effect can be expected even if the conductivity types (N type and P type) shown in the respective embodiments are respectively reversed conductivity types.

  Further, a part of the configuration of an embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of an embodiment. In addition, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

DESCRIPTION OF SYMBOLS 1 High concentration N type board | substrate 2 N type epitaxial layer 3 N type diffusion layer 4 P type diffusion layer 5 Low concentration P type diffusion layer 6 Silicon oxide film 7 Schottky electrode 8 Anode electrode 9 Cathode electrode

Claims (7)

A semiconductor substrate having a first conductivity type semiconductor layer on a surface;
A second conductivity type diffusion region formed by diffusing a second conductivity type impurity at a low concentration on the semiconductor layer;
A Schottky metal formed on the diffusion region;
A first electrode formed on the surface of the Schottky metal;
A second electrode formed on the back surface of the semiconductor substrate;
The semiconductor device, wherein the first electrode and the second electrode are formed of the same metal material. A semiconductor substrate having a first conductivity type semiconductor layer on a surface;
A plurality of first conductivity type diffusion regions formed in an island shape on the semiconductor layer;
An island-shaped second conductivity type diffusion region formed so as to include the upper portion of the diffusion region;
A second conductivity type diffusion region formed by diffusing a second conductivity type impurity at a low concentration between the second conductivity type diffusion regions;
A Schottky metal formed on the island-shaped second conductivity type diffusion region and a second conductivity type diffusion region formed between the second conductivity type diffusion regions;
A first electrode formed on the surface of the Schottky metal;
A second electrode formed on the back surface of the semiconductor substrate;
The semiconductor device, wherein the first electrode and the second electrode are formed of the same metal material. The semiconductor device according to claim 2,
The semiconductor device according to claim 1, wherein the planar shape of the diffusion region of the first conductivity type is a circle or a stripe. The semiconductor device according to claim 1 or 2,
The semiconductor device according to claim 1, wherein the first electrode and the second electrode are formed by plating the same metal material. The semiconductor device according to claim 1 or 2,
The semiconductor device, wherein the first electrode, the second electrode, and the Schottky metal are made of the same metal material. A semiconductor substrate having a first conductivity type semiconductor layer on a surface;
A plurality of first conductivity type diffusion regions formed in an island shape on the semiconductor layer;
An island-shaped second conductivity type diffusion region formed so as to include the upper portion of the diffusion region;
A second conductivity type diffusion region formed by diffusing a second conductivity type impurity at a low concentration between the second conductivity type diffusion regions;
A Schottky metal formed on the island-shaped second conductivity type diffusion region and a first conductivity type diffusion region formed between the second conductivity type diffusion regions;
A first electrode formed on the surface of the Schottky metal;
In a method for manufacturing a semiconductor device including a second electrode formed on the back surface of the semiconductor substrate,
The method of manufacturing a semiconductor device, wherein the first electrode and the second electrode are made of the same metal material, and the metal material is formed by plating. The method of manufacturing a semiconductor device according to claim 6.
The method of manufacturing a semiconductor device, wherein the first electrode, the second electrode, and the Schottky metal are the same metal material, and the metal material is formed by plating.