JP5369581B2 - Back electrode for semiconductor device, semiconductor device, and method for manufacturing back electrode for semiconductor device - Google Patents

Description

  The present invention relates to a back electrode for a semiconductor device, a semiconductor device, and a method for manufacturing a back electrode for a semiconductor device. In particular, the back surface for a semiconductor device that can sufficiently suppress peeling and has low resistance and excellent characteristics. The present invention relates to an electrode, a semiconductor device including the back electrode for the semiconductor device, and a method for manufacturing the back electrode for the semiconductor device.

  Conventionally, semiconductor devices that use silicon as a semiconductor material are mainly used as power devices. In addition, as a semiconductor device used for a high breakdown voltage and large current power device, a vertical semiconductor device having a back electrode having a low-resistance ohmic electrode on the back side has become mainstream.

  Various materials and structures are used for the back electrode for solder-joining such a vertical semiconductor device. One of them is the lamination of a titanium layer, a nickel layer and a gold layer. A body (Ti / Ni / Au) has been proposed (for example, see Non-Patent Document 1).

  In recent years, semiconductor devices using silicon carbide have been greatly expected as power devices having excellent characteristics such as a higher dielectric breakdown voltage than silicon and capable of operating at high temperature with low loss.

  As an electrode of such a semiconductor device using silicon carbide, an electrode formed by heating a nickel layer formed on an n-type silicon carbide substrate by vacuum deposition has been proposed (for example, see Non-Patent Document 2). ).

  Patent Document 1 discloses that an ohmic contact with an n-type silicon carbide substrate is formed by heating after forming a nickel layer on an n-type silicon carbide substrate as a back electrode of a vertical semiconductor device using conventional silicon carbide. A back electrode having a structure in which a nickel silicide layer is formed and a nickel layer and a cathode electrode are sequentially stacked on the nickel silicide layer is described (see, for example, paragraphs [0002] to [0003] of Patent Document 1). . However, this conventional back electrode has a problem that the nickel layer and the cathode electrode are easily peeled off from the nickel silicide layer.

Therefore, in Patent Document 1, the back surface of the structure in which the cathode layer formed by laminating the titanium layer, the nickel layer, and the silver layer in this order after removing the nickel layer remaining on the surface of the nickel silicide layer when forming the nickel silicide layer is formed. It has been proposed to suppress peeling defects by using electrodes (see, for example, paragraphs [0020] to [0025] of Patent Document 1).
JP 2008-53291 A Kimiharu Ninagawa et al., “Interface structure and bonding between power device back electrode and lead-free solder”, Denso Technical Review, Vol. 11, no. 2, 2006 Advanced Power Device Laboratory, Electronics Technology R & D Lab., Department of Materials Science, Hard Electronics Laboratory, “Breakthrough with SiC Power Device Process”, Electronics Technology R & D News, Vol. 612, January 2001, p. 4-p. 8

  However, even in the back electrode configured to suppress peeling failure in Patent Document 1, the adhesion between the nickel silicide layer and the titanium layer is still low, and the cathode electrode is peeled off from the nickel silicide layer at the time of chip cutting of the semiconductor device. There was a problem that.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a back electrode for a semiconductor device that can sufficiently suppress delamination and that has low resistance and excellent characteristics, a semiconductor device including the back electrode for the semiconductor device, and the semiconductor device It is providing the manufacturing method of a back surface electrode.

According to a first aspect of the present invention, includes a two-Tsu Kell silicide layer on a semiconductor, and titanium layer on the nickel silicide layer and a metal layer on the titanium layer, the metal layer is a nickel layer, a platinum layer, a silver layer gold layer, a laminate of the nickel layer and the silver layer, and I at least Tanedea selected from the group consisting of a laminate of a nickel layer and a gold layer, the semiconductor is silicon carbide, and nickel silicide layer nickel silicon alloy layer between the titanium layer is Ru can provide back surface electrode for a semiconductor device is located.

Here, in the back electrode for a semiconductor device according to the first aspect of the present invention, the thickness of the titanium layer is preferably 5 nm or more and 500 nm or less .

In the first aspect of the semiconductor device for the back electrode of the present invention, the thickness of the metal layer is preferably der Rukoto than 1000nm or less 50nm.

  Moreover, this invention is a semiconductor device containing the back electrode for any one of said semiconductor devices.

According to the second aspect of the present invention, the steps of forming a nickel silicon alloy layer on the semiconductor, the nickel silicide layer on a part of the semiconductor side of the nickel silicon alloy layer by heating the nickel silicon alloy layer A step of forming, a step of forming a titanium layer on the nickel silicon alloy layer , a nickel layer, a platinum layer, a silver layer, a gold layer, a laminate of the nickel layer and the silver layer, and a nickel layer on the titanium layer, look including a step of forming at least one metal layer selected from the group consisting of a laminate of a gold layer, semiconductor Ru can provide a method of manufacturing a back electrode for a semiconductor device is silicon carbide.

Moreover, in the manufacturing method of the back electrode for semiconductor devices of the 2nd aspect of this invention, it is preferable that the thickness of a titanium layer is 5 nm or more and 500 nm or less.

Moreover , in the manufacturing method of the back surface electrode for semiconductor devices of the 2nd aspect of this invention, it is preferable that the thickness of a metal layer is 50 nm or more and 1000 nm or less .

  ADVANTAGE OF THE INVENTION According to this invention, peeling can fully be suppressed, and also it is low resistance and is excellent in the characteristic, the semiconductor device back surface electrode for the semiconductor device including the back electrode for the semiconductor device, and the back electrode for the semiconductor device The manufacturing method of can be provided.

  Embodiments of the present invention will be described below. In the drawings of the present invention, the same reference numerals represent the same or corresponding parts.

<Embodiment 1>
FIG. 1 is a schematic cross-sectional view of a Schottky diode that is an example of a semiconductor device of the present invention using an example of a back electrode for a semiconductor device of the present invention. The Schottky diode shown in FIG. 1 includes a semiconductor substrate 1, a semiconductor layer 2 placed on the surface of the semiconductor substrate 1, a Schottky electrode 4 placed on the surface of the semiconductor layer 2, and the back surface of the semiconductor substrate 1. The structure includes a nickel silicide layer 3 disposed above, a titanium layer 5 disposed on the back surface of the nickel silicide layer 3, and a metal layer 6 disposed on the back surface of the titanium layer 5.

  Here, as the semiconductor substrate 1, for example, a substrate made of a semiconductor material can be used, and in particular, an n-type silicon carbide substrate is preferably used. When an n-type silicon carbide substrate is used as the semiconductor substrate 1, silicon carbide is a semiconductor material having a band gap larger than that of silicon. Therefore, the Schottky diode is operated at a higher voltage than when a silicon substrate is used. There is a tendency to be able to drive with a large current.

  As the semiconductor layer 2, for example, a layer made of a semiconductor material can be used, and silicon carbide is particularly preferable. For example, when an n-type silicon carbide substrate is used as the semiconductor substrate 1, a semiconductor layer 2 made of silicon carbide can be epitaxially grown on the surface of the semiconductor substrate 1 to form a Schottky diode. The Schottky diode formed as described above tends to be driven by a large current under a high voltage for the same reason as described above.

  As the Schottky electrode 4, for example, a conventionally known Schottky electrode that forms a Schottky junction with the semiconductor layer 2 can be used. For example, when the semiconductor layer 2 is made of silicon carbide, the semiconductor layer 2 A laminate in which a titanium layer and an aluminum layer are laminated in this order from the side can be used.

The nickel silicide layer 3 is a layer in which nickel is silicided, and is a layer made of a compound represented by the chemical formula of Ni ₂ Si.

  Here, the thickness of the nickel silicide layer 3 is preferably 200 nm or less, and more preferably 10 nm or more and 100 nm or less. When the thickness of the nickel silicide layer 3 is 200 nm or less, particularly when the thickness is 10 nm or more and 100 nm or less, variation in characteristics due to the nickel silicide layer 3 being too thin can be reduced, and the nickel silicide layer 3 can be reduced. There is a tendency that peeling from the semiconductor substrate 1 due to being too thick can be effectively suppressed.

  As the titanium layer 5, for example, a conventionally known layer made of titanium can be used.

  Here, the thickness of the titanium layer 5 is preferably 5 nm or more and 500 nm or less, and more preferably 20 nm or more and 300 nm or less. When the thickness of the titanium layer 5 is not less than 5 nm and not more than 500 nm, particularly when it is not less than 20 nm and not more than 300 nm, it is possible to effectively suppress a decrease in adhesion with the nickel silicide layer 3 due to the titanium layer 5 being too thin. In addition, the resistance of the titanium layer 5 due to the titanium layer 5 being too thick tends to be effectively suppressed.

  The metal layer 6 includes a nickel layer, a platinum layer, a silver layer, a laminate of a nickel layer and a silver layer (the order of lamination of the nickel layer and the silver layer is not limited), and a laminate of the nickel layer and the gold layer. At least one selected from the group consisting of a body (the order of lamination of the nickel layer and the silver layer is not limited) is used. Needless to say, when two or more layers are selected from the above layers as the metal layer 6, for example, a stacked structure such as a laminate of a nickel layer and a platinum layer is formed.

  Here, the thickness of the metal layer 6 is preferably 50 nm or more and 1000 nm or less, and more preferably 100 nm or more and 500 nm or less. When the thickness of the metal layer 6 is 50 nm or more and 1000 nm or less, particularly when the thickness is 100 nm or more and 500 nm or less, it is possible to effectively suppress a decrease in adhesion with the titanium layer 5 due to the metal layer 6 being too thin. In addition, the resistance of the metal layer 6 due to the metal layer 6 being too thick tends to be effectively suppressed.

  In the present embodiment, the back electrode for a semiconductor device of the present invention is composed of a laminate of the nickel silicide layer 3, the titanium layer 5, and the metal layer 6.

  Hereinafter, an example of a method for manufacturing the Schottky diode shown in FIG. 1 will be described with reference to the schematic cross-sectional views of FIGS.

  First, as shown in FIG. 2, the semiconductor layer 2 is formed on the surface of the semiconductor substrate 1. Here, the semiconductor layer 2 can be formed, for example, by epitaxial growth on the surface of the semiconductor substrate 1 by a conventionally known CVD (Chemical Vapor Deposition) method or the like.

  Next, as shown in FIG. 3, a nickel silicon alloy layer 8 is formed on the back surface of the semiconductor substrate 1. Instead of the nickel silicon alloy layer 8, a laminate of a nickel layer and a silicon layer (the order of lamination of the nickel layer and the silicon layer is not limited, but the nickel layer and the silicon layer are laminated in this order from the semiconductor substrate 1 side. It is preferable that the Here, the nickel silicon alloy layer 8 or the laminate of the nickel layer and the silicon layer can be formed by, for example, a sputtering method or a vacuum deposition method.

  The nickel silicon alloy layer 8 is a layer in which nickel and silicon are mixed. Here, for example, the nickel silicon alloy layer 8 is amorphous before heating the nickel silicon alloy layer 8 described later, but may be polycrystallized after heating the nickel silicon alloy layer 8 described later.

  Next, as shown in FIG. 4, the nickel silicon alloy layer 8 on the back surface of the semiconductor substrate 1 or the laminate of the nickel layer and the silicon layer is heated to thereby form the nickel silicon alloy layer 8 or the nickel layer and the silicon layer. A part of the stacked body on the semiconductor substrate 1 side is a nickel silicide layer 3. Here, the heating of the nickel silicon alloy layer 8 or the laminate of the nickel layer and the silicon layer is performed, for example, at a temperature in the vicinity of atmospheric pressure in an argon gas atmosphere, for example, at a temperature of 900 ° C. to 1100 ° C., for example, 30 seconds or more. This can be done by heating for a period of 30 minutes or less. The nickel silicon alloy layer 8 or the laminate of the nickel layer and the silicon layer can be heated by, for example, a method using a conventionally known heating furnace or a RTA (Rapid Thermal Annealing using a conventionally known infrared lamp). There is a method of heating using an apparatus.

Next, as shown in FIG. 5, the Schottky electrode 4 is formed on the surface of the semiconductor layer 2. Here, the Schottky electrode 4 can be formed by, for example, EB (Electron Beam) vapor deposition. Further, after the formation of the Schottky electrode 4, the Schottky electrode 4 may be heated for the purpose of improving the adhesion between the Schottky electrode 4 and the semiconductor layer 2. Further, after the Schottky electrode 4 is formed, the Schottky electrode 4 may be patterned by using, for example, a conventionally known photolithography technique and etching technique. In addition, an oxide film such as silicon dioxide (SiO ₂ ) may be formed on the surface of the semiconductor layer 2 before and / or after the formation of the Schottky electrode 4.

  Next, as shown in FIG. 6, the back surface of the nickel silicide layer 3 is exposed by removing the nickel silicon alloy layer 8 or the laminate of the nickel layer and the silicon layer remaining on the back surface of the nickel silicide layer 3. Let Here, the nickel silicon alloy layer 8 or the laminate of the nickel layer and the silicon layer can be removed by, for example, a conventionally known SPM (Sulfuric acid Hydrogen Peroxide Mixture), aqua regia and It can be performed using hydrofluoric acid or the like.

  Next, as shown in FIG. 7, a titanium layer 5 is formed on the back surface of the nickel silicide layer 3. Thereafter, by forming the metal layer 6 on the titanium layer 5, the Schottky diode having the configuration shown in FIG. 1 can be manufactured. Note that a conductive layer such as a gold layer may be further formed on the back surface of the metal layer 6. The titanium layer 5, the metal layer 6, and the conductive layer can be formed by, for example, an EB vapor deposition method.

  Thereafter, the Schottky diode having the configuration shown in FIG. 1 formed as described above is used with the back surface of the Schottky diode bonded to the die bonding substrate 9 as shown in FIG. 8, for example.

  As described above, in the present invention, the nickel silicon alloy layer 8 or the laminate of the nickel layer and the silicon layer is formed on the back surface of the semiconductor substrate 1, and the nickel silicon alloy layer 8 or the nickel layer and the silicon layer are formed. The nickel silicide layer 3 is formed by heating the laminated body. Then, the titanium layer 5 is formed on the back surface of the nickel silicide layer 3 formed by heating the nickel silicon alloy layer 8 or the laminate of the nickel layer and the silicon layer.

  When the nickel silicide layer is formed by heating after forming the nickel layer as in the conventional patent document 1, the surface roughness of the nickel silicide layer is large, and there is a problem in the adhesion between the nickel silicide layer and the titanium layer. there were.

  However, when the nickel silicide layer 3 is formed by heating the nickel silicon alloy layer 8 or the laminate of the nickel layer and the silicon layer as in the present invention, the heating is performed after the nickel layer is formed as in the prior art. As a result, the adhesion between the nickel silicide layer 3 and the titanium layer 5 is improved as compared with the case where the nickel silicide layer is formed, so that the peeling of the titanium layer 5 can be sufficiently suppressed. This is presumably because, for example, when the semiconductor substrate 1 in contact with the nickel silicide layer 3 is a semiconductor containing carbon such as silicon carbide, the deposition of carbon from the semiconductor substrate 1 made of a semiconductor containing carbon is suppressed.

  Furthermore, since the back electrode for a semiconductor device formed on the back surface of the semiconductor substrate 1 as in the present invention has a low resistance, it can have excellent characteristics.

<Embodiment 2>
FIG. 9 shows a schematic cross-sectional view of a Schottky diode which is another example of the semiconductor device of the present invention using another example of the back electrode for a semiconductor device of the present invention. The Schottky diode having the configuration shown in FIG. 9 is characterized in that a nickel silicon alloy layer 8 is provided between the nickel silicide layer 3 and the titanium layer 5. In place of the nickel silicon alloy layer 8, a laminate of a nickel layer and a silicon layer may be provided.

  Therefore, in the present embodiment, a nickel silicide layer 3, a nickel silicon alloy layer 8 (or a laminate of a nickel layer and a silicon layer), a laminate of a titanium layer 5 and a metal layer 6 are used for the semiconductor device of the present invention. A back electrode is formed.

Hereinafter, an example of a method for manufacturing the Schottky diode having the configuration shown in FIG. 9 will be described.
First, as shown in FIG. 2, after forming the semiconductor layer 2 on the surface of the semiconductor substrate 1, the nickel silicon alloy layer 8 is formed on the back surface of the semiconductor substrate 1 as shown in FIG. Here, instead of the nickel silicon alloy layer 8, a laminate of a nickel layer and a silicon layer (the order of lamination of the nickel layer and the silicon layer is not specified, but the nickel layer and the silicon layer are laminated in this order from the semiconductor substrate 1 side). It is preferable that the

  Here, the ratio of the number of silicon (Si) atoms and the number of nickel (Ni) atoms in the nickel silicon alloy layer 8 (the number of Si atoms / the number of Ni atoms) is not particularly limited. It is preferably 4 or more and 0.6 or less, and more preferably 0.45 or more and 0.55 or less. When the ratio (number of Si atoms / number of Ni atoms) is 0.4 or more and 0.6 or less, particularly when the ratio is 0.45 or more and 0.55 or less, the surface roughness of the nickel silicon alloy layer 8 Therefore, the contact resistance between the nickel silicon alloy layer 8 and the titanium layer 5 described later tends to be small, and the bonding strength between the nickel silicon alloy layer 8 and the titanium layer 5 tends to increase.

  Then, as shown in FIG. 4, by heating the nickel silicon alloy layer 8 or the laminate of the nickel layer and the silicon layer on the back surface of the semiconductor substrate 1, the nickel silicon alloy layer 8 or the nickel layer and the silicon layer are heated. A part of the stacked body on the semiconductor substrate 1 side is a nickel silicide layer 3.

  Next, as shown in FIG. 5, the Schottky electrode 4 is formed on the surface of the semiconductor layer 2. The steps so far are the same as those in the first embodiment.

  Next, as shown in FIG. 10, without removing the nickel silicon alloy layer 8 or the laminate of the nickel layer and the silicon layer, on the back surface of the nickel silicon alloy layer 8 or the laminate of the nickel layer and the silicon layer. A titanium layer 5 is formed. Thereafter, by forming the metal layer 6 on the titanium layer 5, a Schottky diode having the configuration shown in FIG. 9 can be manufactured. Note that a conductive layer such as a gold layer may be further formed on the back surface of the metal layer 6.

  Thereafter, the Schottky diode having the configuration shown in FIG. 9 formed as described above is used with the back surface of the Schottky diode bonded to the die bonding substrate 9 as shown in FIG. 11, for example.

  As described above, in the present embodiment, the nickel silicon alloy layer 8 or the laminate of the nickel layer and the silicon layer is formed on the back surface of the semiconductor substrate 1, and the nickel silicon alloy layer 8 or the nickel layer and the silicon layer are formed. The nickel silicide layer 3 is heated to form the nickel silicide layer 3, and then the nickel silicon alloy layer 8 or the nickel layer and the silicon layer are removed without removing the nickel silicon alloy layer 8 or the laminate of the nickel layer and the silicon layer. A titanium layer 5 is formed on the back surface of the laminate.

  Also in this case, compared to the case where the nickel silicide layer is formed by heating after forming the nickel layer as in the prior art, the nickel silicon alloy layer 8 or the laminate of the nickel layer and the silicon layer and the titanium layer 5 Therefore, the peeling of the titanium layer 5 can be sufficiently suppressed. This is presumably because, for example, when the semiconductor substrate 1 in contact with the nickel silicide layer 3 is a semiconductor containing carbon such as silicon carbide, the deposition of carbon from the semiconductor substrate 1 made of a semiconductor containing carbon is suppressed.

  In this case, since the nickel silicon alloy layer 8 or the laminate of the nickel layer and the silicon layer is not removed, a natural oxide film formed on the back surface of the nickel silicide layer 3 when the back surface of the nickel silicide layer 3 is exposed. Back surface contamination due to can be suppressed.

  Therefore, when the titanium layer 5 is formed on the back surface of the nickel silicon alloy layer 8 without removing the nickel silicon alloy layer 8 as in the present embodiment, the step of removing the nickel silicon alloy layer 8 is omitted. Therefore, the manufacturing process can be simplified, and the generation of a natural oxide film on the back surface of the nickel silicide layer 3 due to the deterioration of the ohmic characteristics can be caused by the nickel silicon alloy layer 8 or the nickel layer and the silicon layer. Since it can suppress by a laminated body and the back electrode for semiconductor devices becomes low resistance, it can be set as the thing excellent in the characteristic.

  Since the description other than the above in the present embodiment is the same as that in the first embodiment, the description thereof is omitted.

<Example 1>
First, an SiC substrate made of n-type silicon carbide (SiC) was prepared, and an SiC layer having a thickness of 10 μm was epitaxially grown on the surface of the prepared SiC substrate by a CVD method.

  Next, a nickel silicon alloy layer was formed on the back surface of the SiC substrate by sputtering using a target made of Ni and a target made of Si, respectively.

  Here, the ratio of the number of Si atoms and the number of Ni atoms constituting the nickel silicon alloy layer (the number of Si atoms / the number of Ni atoms) was measured by Auger electron spectroscopy. It was confirmed that the ratio to the number of atoms (number of Si atoms / number of Ni atoms) was 0.51.

  Next, the nickel silicon alloy layer on the back surface of the SiC substrate was heated, so that a part of the nickel silicon alloy layer on the SiC substrate side was a nickel silicide layer having a thickness of 50 nm.

  Here, the heating of the nickel silicon alloy layer was performed by placing the SiC substrate after the nickel silicon alloy layer was formed in a heating furnace and heating at 1000 ° C. for 10 minutes in an argon gas atmosphere under atmospheric pressure. .

  Next, on the surface of the SiC layer on the SiC substrate, a titanium layer having a thickness of 10 nm and an aluminum layer having a thickness of 3 μm are formed in this order by the EB vapor deposition method. From the laminate of the titanium layer and the aluminum layer, A Schottky electrode was formed.

  Next, by forming a resist pattern having an opening in a predetermined shape on the surface of the Schottky electrode using photolithography technology, and then removing the Schottky electrode into the shape of the opening of the resist pattern by etching technology The Schottky electrode was patterned. Thereafter, a resist pattern was formed from the surface of the Schottky electrode.

  Next, in order to improve the adhesion between the Schottky electrode and the SiC layer, the Schottky electrode was heated at 300 ° C. for 30 minutes.

  Next, the organic substance was removed by washing the back side of the nickel silicide layer by immersing the back side of the heated nickel silicide layer in SPM and heating.

  Next, the nickel silicon alloy layer on the back surface of the nickel silicide layer was removed by immersing the back surface side of the nickel silicide layer in aqua regia.

  Next, the natural oxide film formed on the back surface of the nickel silicide layer was removed by immersing the back surface of the nickel silicide layer after removal of the nickel silicon alloy layer in hydrofluoric acid. Thereafter, the back surface of the nickel silicide layer was washed with pure water.

  Next, a titanium layer having a thickness of 100 nm, a nickel layer having a thickness of 300 nm, and a gold layer having a thickness of 100 nm are formed in this order on the back surface of the nickel silicide layer by the EB evaporation method. A Schottky diode was fabricated.

  And after joining the back surface of the Schottky diode of Example 1 produced as mentioned above to the board | substrate for die bonding, the current-voltage characteristic of the Schottky diode of Example 1 was evaluated. The result is shown in FIG.

  The current-voltage characteristics of the Schottky diode of Example 1 are as follows. A plurality of Schottky diodes of Example 1 are produced as described above, and the current-voltage characteristics of each of the plurality of Schottky diodes of Example 1 are obtained. Evaluated.

<Comparative Example 1>
A Schottky diode of Comparative Example 1 was fabricated in the same manner as in Example 1 except that the nickel layer and the gold layer were formed in this order on the back surface of the nickel silicide layer by the EB vapor deposition method without forming the titanium layer. did. That is, the back electrode formed on the back surface of the SiC substrate of the Schottky diode of Comparative Example 1 was formed from a laminate of a nickel silicide layer, a nickel layer, and a gold layer.

  Then, the current-voltage characteristics of the Schottky diode of Comparative Example 1 were evaluated in the same manner as in Example 1 above. The result is shown in FIG.

<Comparative example 2>
A Schottky diode of Comparative Example 2 was produced in the same manner as in Example 1 except that the titanium layer, nickel layer, and gold layer were not formed. That is, the back electrode formed on the back surface of the SiC substrate of the Schottky diode of Comparative Example 2 was formed only from the nickel silicide layer.

  Then, the current-voltage characteristics of the Schottky diode of Comparative Example 2 were evaluated in the same manner as in Example 1 above. The result is shown in FIG.

<Evaluation results>
As is clear from comparison of FIGS. 12 to 14, the Schottky diode of Example 1 has a larger current flowing at a lower voltage than the Schottky diodes of Comparative Example 2 and Comparative Example 3. Therefore, it was confirmed that the resistance was low and the characteristics were excellent.

  In addition, a Schottky diode of Comparative Example 3 was fabricated separately in the same manner as in Example 1 except that the nickel silicide layer was formed by heating the nickel layer after forming the nickel layer on the surface of the SiC layer.

  When the peelability of the titanium layer was evaluated for the Schottky diode of Example 1 and the Schottky diode of Comparative Example 3, the Schottky diode of Example 1 was compared with the Schottky diode of Comparative Example 3. Thus, it was confirmed that the adhesion between the nickel silicide layer and the titanium layer was excellent, and the titanium layer was difficult to peel off.

  From the above experimental results, the Schottky diode of Example 1 manufactured by heating the nickel silicon alloy layer to form the nickel silicide layer and forming the titanium layer on the surface of the nickel silicide layer is It was confirmed that peeling could be sufficiently suppressed, low resistance and excellent characteristics.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  In the above description, the case where the back electrode for a semiconductor device of the present invention is used for a Schottky diode has been mainly described. However, the back electrode for a semiconductor device of the present invention is not limited to the case where it is used for a Schottky diode. It can also be suitably used for semiconductor devices such as Metal Oxide Semiconductor Field Effect Transistors (JFETs) and JFETs (Junction Field Effect Transistors).

It is typical sectional drawing of the Schottky diode which is an example of the semiconductor device of this invention using an example of the back surface electrode for semiconductor devices of this invention. It is typical sectional drawing illustrating a part of manufacturing process of the manufacturing method of the Schottky diode which is an example of the semiconductor device of this invention. It is typical sectional drawing illustrating a part of manufacturing process of the manufacturing method of the Schottky diode which is an example of the semiconductor device of this invention. It is typical sectional drawing illustrating a part of manufacturing process of the manufacturing method of the Schottky diode which is an example of the semiconductor device of this invention. It is typical sectional drawing illustrating a part of manufacturing process of the manufacturing method of the Schottky diode which is an example of the semiconductor device of this invention. It is typical sectional drawing illustrating a part of manufacturing process of the manufacturing method of the Schottky diode which is an example of the semiconductor device of this invention. It is typical sectional drawing illustrating a part of manufacturing process of the manufacturing method of the Schottky diode which is an example of the semiconductor device of this invention. It is typical sectional drawing of an example of the structure which joined the Schottky diode of the structure shown in FIG. 1 to the board | substrate for die bonding. It is typical sectional drawing of the Schottky diode which is another example of the semiconductor device of this invention using another example of the back surface electrode for semiconductor devices of this invention. FIG. 10 is a schematic cross-sectional view illustrating a part of the manufacturing process of the method for manufacturing the Schottky diode having the configuration shown in FIG. 9. It is typical sectional drawing of an example of the structure which joined the Schottky diode of the structure shown in FIG. 9 to the board | substrate for die bonding. It is a figure which shows the result evaluated about the current-voltage characteristic of the Schottky diode of Example 1. FIG. It is a figure which shows the result evaluated about the current-voltage characteristic of the Schottky diode of the comparative example 1. FIG. It is a figure which shows the result evaluated about the current-voltage characteristic of the Schottky diode of the comparative example 2. FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Semiconductor substrate, 2 Semiconductor layer, 3 Nickel silicide layer, 4 Schottky electrode, 5 Titanium layer, 6 Metal layer, 8 Nickel silicon alloy layer, 9 Substrate for die bonding.

Claims (7)

And two Tsu Kell silicide layer on a semiconductor,
A titanium layer on the nickel silicide layer ;
And a metallic layer on the titanium layer,
The metal layer is a nickel layer, a platinum layer, a silver layer, a gold layer, Tsu least 1 Tanedea selected from the group consisting of a laminate of a laminated body, and the nickel layer and the gold layer of the nickel layer and the silver layer And
The semiconductor is silicon carbide;
Wherein between the nickel silicide layer and the titanium layer, a nickel silicon alloy layer that are located, the backside electrode for a semiconductor device. The back electrode for a semiconductor device according to claim 1, wherein the titanium layer has a thickness of 5 nm to 500 nm. The back electrode for a semiconductor device according to claim 1 or 2, wherein the metal layer has a thickness of 50 nm or more and 1000 nm or less. Claims 1 comprises a back electrode for a semiconductor device according to any one of claims 3, semiconductor devices. Forming a nickel silicon alloy layer on the semiconductor;
Forming a nickel silicide layer on a portion of the semiconductor side of the nickel silicon alloy layer by heating said nickel-silicon alloy layer,
Forming a titanium layer on the nickel silicon alloy layer;
On the titanium layer, at least one metal selected from the group consisting of a nickel layer, a platinum layer, a silver layer, a gold layer, a laminate of a nickel layer and a silver layer, and a laminate of a nickel layer and a gold layer look including a step of forming the layer,
The said semiconductor is a silicon carbide, The manufacturing method of the back surface electrode for semiconductor devices. The manufacturing method of the back surface electrode for semiconductor devices of Claim 5 whose thickness of the said titanium layer is 5 nm or more and 500 nm or less. The manufacturing method of the back surface electrode for semiconductor devices of Claim 5 or Claim 6 whose thickness of the said metal layer is 50 nm or more and 1000 nm or less.

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