JP4904688B2 - Semiconductor substrate and manufacturing method thereof - Google Patents

Description

  The present invention relates to a semiconductor substrate having a region for forming a desired semiconductor element on the surface of the substrate, and a contact electrode film on the back side of the substrate, and a method for manufacturing the same, and particularly a semiconductor suitable for use in a silicon carbide device. The present invention relates to a substrate and a manufacturing method thereof.

  Conventionally, as this type of semiconductor substrate and a method for manufacturing the same, there are, for example, those shown in FIGS. Hereinafter, with reference to FIGS. 8A and 8B, the semiconductor substrate and the manufacturing method thereof will be described.

As shown in FIG. 8A, at the time of manufacturing, first, a substrate 11 made of, for example, silicon carbide is prepared. Next, as shown in FIG. 8B, a contact electrode film 12 is formed on the back surface side of the substrate 11 having a region for forming a desired semiconductor element on the front surface so as to completely cover the one surface. Thereafter, in order to obtain an ohmic contact (ohmic characteristics) of the contact electrode film 12, the substrate is subjected to a heat treatment of 1000 ° C. to 1600 ° C., for example. As a result, the contact electrode film 12 is silicided at the interface with the substrate 11 to form an ohmic contact therebetween. In this way, a semiconductor substrate having a region for forming a desired semiconductor element on the substrate surface and a contact electrode film 12 covering the substantially entire surface on the back surface side of the substrate is manufactured.
Japanese Patent Laid-Open No. 10-284436

  By the way, in order to obtain ohmic contact (ohmic characteristics) of the contact electrode film 12 in such a semiconductor substrate, heat treatment after the film formation of the electrode film is extremely important. However, for example, a substrate made of silicon carbide, which is attracting attention as a next-generation material, requires a heat treatment at a higher temperature than a substrate made of silicon or the like because the energy gap is large and the melting point is high. . Therefore, during the heat treatment step, stress (internal stress) is applied to the substrate 11 due to the difference in thermal expansion coefficient and thermal conductivity between the substrate 11 and the contact electrode film 12, and as shown in FIG. There is a problem that the substrate is warped. Such warpage of the semiconductor substrate hinders smooth substrate transfer and, consequently, automation of the manufacturing system, and may reduce the reliability of the semiconductor device manufactured using the substrate, and is therefore minimized. It is demanded. Therefore, conventionally, a method of suppressing the warpage of the semiconductor substrate by increasing the thickness of the substrate 11 has been adopted. However, according to this, a new problem such as a significant increase in cost will arise this time, and the fact is that the fundamental problem has not been solved.

  Although only the substrate made of silicon carbide is mentioned here, such a situation is generally common in a substrate that requires high-temperature treatment after the formation of the contact electrode film.

  The present invention has been made in view of the above circumstances, and even when a high temperature treatment is required after the formation of a contact electrode film covering substantially the entire back surface of the substrate, the heating of the treatment is performed regardless of the thickness of the substrate. An object of the present invention is to provide a semiconductor substrate and a method for manufacturing the same that can suppress the warpage of the substrate due to the above.

In order to achieve such an object, in the first aspect of the present invention, the contact electrode film has a region for forming a desired semiconductor element on the substrate surface, and covers substantially the entire surface on the back surface side of the substrate. By providing a mask material having a pattern corresponding to the non-contact region of the contact electrode film covering substantially the entire back surface of the substrate on the back surface of the substrate, the contact electrode film is formed of the mask material. The contact electrode film is made of a material that satisfies the condition of “ΔG <0”, when patterning is performed in a manner that relieves stress on the substrate according to the pattern, and when the change in Gibbs free energy before and after reaction with the substrate is ΔG, The mask material for patterning the contact electrode film is made of a material that satisfies the condition “ΔG> 0” .

  According to the above structure as a semiconductor substrate, after forming a contact electrode film covering substantially the entire back surface of the substrate, for example, when high temperature treatment is required to obtain ohmic contact (ohmic characteristics) of the contact electrode film, The stress on the substrate is relaxed through the contact electrode film pattern, and the warpage of the substrate due to the heating in the high temperature treatment is suppressed.

In addition, according to such a structure, not only patterning on the same plane but also patterning in the substrate depth direction using a step due to a mask material can be performed, and thus a more flexible pattern design can be realized. Further, the contact electrode film is made of a material that satisfies the condition “ΔG <0”, and the mask material for patterning the contact electrode film is made of a material that satisfies the condition “ΔG> 0”. As a result, only the contact electrode film of the contact electrode film and the mask material is selectively formed with silicide at the interface with the substrate, so that a good ohmic contact (ohmic characteristics) can be obtained. As a result, the contact region of the contact electrode film is suitably separated including the silicided portion, and the stress due to the high temperature treatment can be further reduced.

Incidentally, before Symbol mask material for patterning the contact electrode film, such as by the invention of claim 2, it is desirable that shall be formed with a pattern as cutting are removed rests on the scribe line at the time of dicing . As described above, by providing the mask material formation region in an unnecessary space as a device, the substrate area can be effectively used, which leads to cost reduction.

A silicon carbide device (semiconductor element) manufactured using a silicon carbide substrate is attracting attention as a next-generation device because of its excellent breakdown voltage and heat resistance. However, since the silicon carbide substrate has a large energy gap and a high melting point as described above, heat treatment at a temperature higher than that of silicon or the like is required to obtain ohmic contact (ohmic characteristics) of the contact electrode film. As described above, the warpage of the substrate resulting from the heat treatment at a high temperature is a major obstacle to the establishment of a silicon carbide device production system expected as a next-generation device. As described above, enhancement of resistance to high-temperature treatment after the formation of the contact electrode film is expected in a silicon carbide substrate. For this situation, the structure of the upper SL is particularly effective when applied to the silicon carbide substrate.

And when the said semiconductor substrate is a semiconductor substrate which consists of silicon carbide, according to the invention of Claim 3 , in the semiconductor substrate of the said Claim 1 or 2 , this is said about the said contact electrode film, It is made of any one of Ti, Ni, Au, Co, Fe, Mg, Ca, Mn, and Mo, and the mask material for patterning the contact electrode film is any one of W, Pt, and Cr. It is effective to consist of one. Thereby, the conditions regarding the Gibbs free energy change are appropriately satisfied.

Prior to forming a contact electrode film covering substantially the entire surface on the back surface side of a semiconductor substrate having a region for forming a desired semiconductor element on the surface, as in the invention described in claim 4 , A mask material having a pattern corresponding to a non-contact region of the contact electrode film is formed on the back surface of the semiconductor substrate, and then the contact electrode film is masked on the back surface of the substrate on which the mask material is formed. The contact electrode film is formed as “ΔG <when the change in Gibbs free energy before and after the reaction with the semiconductor substrate is ΔG. The mask material for patterning the contact electrode film is formed of a material satisfying the condition “ΔG> 0”. If so, so the structure according to the claim 1 is also more easily and realized favorably.

Further, according to the invention described in claim 5 , in the manufacturing method described in claim 4 , the film thickness of the mask material is set smaller than the film thickness of the contact electrode film. 1 can be manufactured more easily.

In the manufacturing method according to claim 4 or 5 , as in the invention according to claim 6 , after forming the contact electrode film, an appropriate heat treatment is applied to form the contact electrode film into the semiconductor. If silicidation is performed at the interface with the substrate, ohmic contact (ohmic characteristics) can be obtained in the contact electrode film while suppressing warpage of the substrate.

Furthermore, in the manufacturing method according to any one of claims 4 to 6 , according to the invention according to claim 7 , a mask having a pattern corresponding to a non-contact region of the contact electrode film during dicing. By removing the material by cutting, unnecessary space as a device is deleted, and miniaturization as a semiconductor device (semiconductor element) can be achieved.

In the manufacturing method according to any one of claims 4 to 7 , it is effective to employ a semiconductor substrate made of silicon carbide as the semiconductor substrate as in the invention according to claim 8. It is. By applying these manufacturing methods to a silicon carbide substrate, it is possible to greatly contribute to the establishment of a production system for silicon carbide devices that are attracting attention as next-generation devices, and thus to the creation of new industries.

(First comparative example )
A semiconductor substrate and a manufacturing method thereof according to the present invention Before describing the form of implementation of that shows a first comparative example.

First, an outline of the structure of the semiconductor substrate according to this comparative example will be described with reference to FIG. FIG. 1 is a plan view schematically showing a planar structure viewed from the back side of the semiconductor substrate.

  As shown in FIG. 1, this semiconductor substrate covers substantially the entire surface on the back side of a substrate 1 made of, for example, silicon carbide (SiC) having a region for forming a desired semiconductor element on the surface. The contact electrode film 2 is formed. Here, the contact electrode film 2 is patterned so as to relieve stress on the substrate 1, and more specifically, is formed with a collective pattern composed of a number of squares over substantially the entire back surface of the substrate. The pattern formed by the contact electrode film 2 is formed by arranging electrode films made of squares each having a dimension a on each side in the vertical and horizontal directions with an interval of a dimension b smaller than the dimension a. . Thus, the contact resistance can be reduced because the dimension b between the electrodes is set smaller than the dimension a of the electrode width. The contact electrode film 2 having the same pattern is silicided at the interface with the substrate 1 to form an ohmic contact. As a material for the contact electrode film 2, for example, Ti, Ni, Au, Co, Fe, Mg, Ca, Mn, Mo, or the like can be employed.

  Next, with reference to FIGS. 2A and 2B, a method for manufacturing the semiconductor substrate will be described. 2A and 2B are enlarged cross-sectional views showing a part of the cross-sectional structure of the semiconductor substrate.

  As shown in FIG. 2 (a), in the manufacture, first, a substrate 1 made of, for example, silicon carbide is prepared. Next, as shown in FIG. 2B, a contact electrode film 2 is formed on the back side of the substrate 1 so as to completely cover the one surface, and the contact electrode film 2 is shown in FIG. Patterning is performed in the above manner. Thereafter, in order to obtain ohmic characteristics of the contact electrode film 2, for example, a heat treatment of 500 ° C. to 1300 ° C. is performed on the substrate. As a result, the contact electrode film 2 is silicided at the interface with the substrate 1 to form an ohmic contact therebetween. In this way, a semiconductor substrate having a region for forming a desired semiconductor element on the substrate surface and the contact electrode film 2 covering the substantially entire surface on the back surface side of the substrate is manufactured.

  Thus, in this semiconductor substrate, the contact electrode film 2 is patterned in such a manner that the contact region is subdivided over substantially the entire back surface of the substrate. For this reason, even in the high temperature treatment for obtaining the ohmic contact (ohmic characteristics) of the contact electrode film 2, the application of stress due to the high temperature treatment is separated and dispersed through the pattern. Warpage of the substrate due to heating is suppressed.

As described above, according to the semiconductor substrate and a manufacturing method thereof according to this comparative example, so that effects can be obtained as described below.
(1) The above-mentioned contact electrode film as a semiconductor substrate having a region for forming a desired semiconductor element on the substrate surface and provided with a contact electrode film 2 covering the entire surface on the back surface side of the substrate. 2 was patterned in such a manner that its contact region was subdivided over substantially the entire back surface of the substrate. Thereby, even when a high temperature treatment is performed to obtain ohmic contact (ohmic characteristics) of the contact electrode film 2 after the formation of the contact electrode film 2 covering substantially the entire back surface of the substrate, the high temperature is applied over the substantially entire surface of the substrate. The application of stress due to the processing is separated and dispersed, and as a result, the warpage of the substrate due to the heating of the high-temperature processing described above can be reduced.

  (2) Further, the reduction of the warpage of the semiconductor substrate also leads to an improvement in the yield of semiconductor elements manufactured using this substrate, which leads to a reduction in cost and energy saving.

  (3) As the pattern of the contact electrode film 2, an aggregate pattern composed of a large number of squares covering substantially the entire back surface of the substrate is adopted. As a result, the contact electrode film 2 in which the contact region is subdivided over substantially the entire back surface of the substrate can be easily realized.

(4) The dimension b between the electrodes is set smaller than the dimension a of the electrode width. As a result, the contact resistance can be reduced.
(5) The contact electrode film 2 is silicided at the interface with the substrate 1. As a result, a good ohmic contact (ohmic characteristics) can be obtained between the contact electrode film 2 and the substrate 1.

  (6) Further, when the semiconductor substrate is manufactured, the contact electrode film 2 is formed in such a manner as to completely cover one surface on the back surface side of the substrate 1 having a region for forming a desired semiconductor element on the surface, After patterning the deposited contact electrode film 2, an appropriate heat treatment was performed so that the contact electrode film 2 was silicided at the interface with the substrate 1. By adopting such a manufacturing method, the above structure can be realized more easily and suitably. With the same structure, ohmic contact (ohmic characteristics) is made to the contact electrode film 2 while suppressing the warpage of the substrate described above. Can be obtained.

  (7) The substrate 1 is a semiconductor substrate made of silicon carbide. Thus, by applying the above structure and manufacturing method to a silicon carbide substrate, it is possible to greatly contribute to the establishment of a production system for silicon carbide devices that are attracting attention as the next-generation device, and thus to the creation of new industries. Become.

(In the form of implementation)
Hereinafter, the one embodiment of a semiconductor substrate and a manufacturing method thereof according to the present invention.

  First, an outline of the structure of the semiconductor substrate according to this embodiment will be described with reference to FIG. FIG. 3 is a plan view schematically showing a planar structure viewed from the back side of the semiconductor substrate. In FIG. 3, the same elements as those shown in FIG. 1 are denoted by the same reference numerals.

As shown in FIG. 3, this semiconductor substrate also has a region for forming a desired semiconductor element on the surface, and a contact electrode that covers the entire surface on the back surface side of the substrate 1 made of, for example, silicon carbide. A film 2 is provided. The contact electrode film 2 is patterned in a manner that relieves stress on the substrate 1 as in the first comparative example . In this case, however, the contact electrode film 2 is patterned using a step provided on the base. Specifically, a mask material 3 having a pattern corresponding to the non-contact region of the contact electrode film 2 is provided on the back surface of the substrate 1, and the contact electrode film 2 is patterned according to the pattern of the mask material 3. Yes. Thus, the contact electrode film 2 is formed as a contact region with a collective pattern composed of a large number of squares covering substantially the entire back surface of the substrate. The pattern of the contact electrode film 2, that is, the pattern of the contact region of the electrode film is separated by a distance of a dimension d corresponding to a width of the mask material 3 in which a square having a dimension c on each side is smaller than the dimension c. Are arranged side by side vertically and horizontally. Thus, the contact resistance can be reduced because the dimension d between the electrodes is set smaller than the dimension c of the electrode width. Moreover, the mask material 3 is formed with a pattern that is placed on a scribe line and cut off when dicing.

  Also here, the contact electrode film 2 is silicided at the interface with the substrate 1 to form an ohmic contact. However, in this embodiment, any one of Ti, Ni, Au, Co, Fe, Mg, Ca, Mn, and Mo is adopted as the material of the contact electrode film 2 and the material of the mask material 3 is used. , W, Pt, or Cr is adopted. Here, assuming that the change in Gibbs free energy before and after reaction (silicidation) with the substrate 1 is ΔG, in each of the materials listed above, the material of the contact electrode film 2 satisfies the condition “ΔG <0”, For the material of the mask material 3, this satisfies the condition of “ΔG> 0”. Thereby, only the contact electrode film 2 of the contact electrode film 2 and the mask material 3 is selectively formed with silicide at the interface with the substrate 1 to obtain good ohmic contact (ohmic characteristics). Further, the contact region of the contact electrode film 2 is separated including the silicidized portion, so that the stress can be further reduced by the high temperature treatment described above. Note that the change in Gibbs free energy before and after the reaction with the substrate 1 is ΔG, where the standard production Gibbs energy of the reaction product related to the reaction is ΔG1, and the standard production Gibbs energy of the product resulting from the reaction is ΔG2. It can be expressed as “ΔG2−ΔG1”.

  Next, with reference to FIGS. 4A and 4B, a method for manufacturing the semiconductor substrate will be described. 4A and 4B are cross-sectional views showing an enlarged part of the cross-sectional structure of the semiconductor substrate.

  As shown in FIG. 4A, at the time of manufacturing, first, a substrate 1 made of, for example, silicon carbide is prepared. Next, as shown in FIG. 4B, a mask material 3 is formed on the back side of the substrate 1 so as to completely cover the entire surface, and the mask material 3 is formed in the above-described manner shown in FIG. To pattern. Subsequently, as shown in FIG. 4C, a contact electrode film 2 is formed on the back surface of the substrate 1 on which the mask material 3 is formed. At this time, by setting the film thickness dimension e of the mask material 3 to be smaller than the film thickness dimension f of the contact electrode film 2, the structure can be realized more easily. Thereafter, in order to obtain ohmic characteristics of the contact electrode film 2, for example, a heat treatment of 500 ° C. to 1300 ° C. is performed on the substrate. As a result, the contact electrode film 2 is silicided at the interface with the substrate 1 to form an ohmic contact therebetween. In this way, a semiconductor substrate having a region for forming a desired semiconductor element on the substrate surface and the contact electrode film 2 covering the substantially entire surface on the back surface side of the substrate is manufactured. Furthermore, by removing the mask material 3 by cutting at the time of dicing, unnecessary space as a device is deleted, and miniaturization as a semiconductor device (semiconductor element) can be achieved.

  Thus, also in this embodiment, the contact electrode film 2 is patterned in such a manner that the contact region is subdivided over substantially the entire back surface of the substrate. For this reason, even in the high temperature treatment for obtaining the ohmic contact (ohmic characteristics) of the contact electrode film 2, the application of stress due to the high temperature treatment is separated and dispersed through the pattern. Warpage of the substrate due to heating is suppressed.

As described above, according to the semiconductor substrate and the manufacturing method thereof according to this embodiment, the same effects as the effects (1) to (7) in the first comparative example or the effects equivalent thereto. In addition, the following effects can be obtained.

  (8) The contact electrode film 2 is patterned using a step (mask material 3) provided on the base. As a result, not only patterning on the same plane but also patterning in the substrate depth direction using the base level difference, that is, the mask material 3, can be realized, and as a result, more flexible pattern design can be realized.

  (9) As the material of the contact electrode film 2, any one of Ti, Ni, Au, Co, Fe, Mg, Ca, Mn, and Mo is adopted, and as the material of the mask material 3, W, Pt, Cr One of these was adopted. Thereby, only the contact electrode film 2 of the contact electrode film 2 and the mask material 3 is selectively formed with silicide at the interface with the substrate 1 to obtain good ohmic contact (ohmic characteristics). In addition, the contact region of the contact electrode film 2 is separated including the silicidized portion, so that the stress can be further reduced by the high-temperature treatment described above.

  (10) Further, the mask material 3 for patterning the contact electrode film 2 has a pattern that can be removed by cutting on the scribe line during dicing. In this way, by providing the formation region of the mask material 3 in an unnecessary space as a device, the substrate area can be effectively used, which leads to cost reduction.

  (11) On the other hand, when manufacturing the semiconductor substrate, the film thickness dimension e of the mask material 3 is set smaller than the film thickness dimension f of the contact electrode film 2. As a result, the semiconductor substrate can be manufactured more easily.

  (12) Further, the mask material 3 is cut and removed during dicing. As a result, unnecessary space as a device is deleted, and miniaturization as a semiconductor device (semiconductor element) is achieved.

( Second comparative example )
Hereinafter , a second comparative example will be shown.

First, the outline of the structure of the semiconductor substrate according to this comparative example will be described with reference to FIG. FIG. 5 is a plan view schematically showing a planar structure viewed from the back side of the semiconductor substrate. In FIG. 5, the same elements as those shown in FIG. 1 are denoted by the same reference numerals.

As shown in FIG. 5, this semiconductor substrate also has a contact electrode covering the substantially entire surface on the back side of the substrate 1 made of, for example, silicon carbide having a region for forming a desired semiconductor element on the surface. A film 2 is provided. Then, it is similar to the form of the first comparative example Oyo BiMinoru facilities to contact the electrode film 2 is patterned in the form to relieve stress on the substrate 1. As with the implementation of the form it was or, again, contact electrode film 2 is patterned in a way that utilizes a step provided in the base. However, here, the trench T is formed on the back surface of the substrate 1 which is the base of the contact electrode film 2, so that the contact electrode film 2a formed in the trench T and the contact electrode formed outside the trench T are formed. The film 2 is separated in the substrate depth direction, and the contact electrode film 2 is patterned corresponding to the pattern of the trench T. Thus, the contact electrode film 2 is formed as a contact region with a collective pattern composed of a large number of squares covering substantially the entire back surface of the substrate. The pattern formed by the contact electrode film 2 is formed such that squares each having a dimension g are juxtaposed vertically and horizontally with an interval of a dimension h corresponding to the width of the trench T smaller than the dimension g. Has been. Thus, the contact resistance can be reduced because the dimension h between the electrodes is set smaller than the dimension g of the electrode width. The contact electrode film 2 having the same pattern is silicided at the interface with the substrate 1 to form an ohmic contact. As a material for the contact electrode film 2, for example, Ti, Ni, Au, Co, Fe, Mg, Ca, Mn, Mo, or the like can be employed.

  Next, with reference to FIGS. 6A and 6B, a method for manufacturing the semiconductor substrate will be described. 6A and 6B are cross-sectional views showing an enlarged part of the cross-sectional structure of the semiconductor substrate.

  As shown in FIG. 6A, in manufacturing, first, a substrate 1 made of, for example, silicon carbide is prepared, and a trench T having the pattern shown in FIG. . Subsequently, as shown in FIG. 6B, the contact electrode films 2 and 2a are formed on the back surface of the substrate 1 on which the trench T is formed. At this time, the structure is more easily realized by setting the depth dimension i of the trench T to be larger than the film thickness dimension j of the contact electrode films 2 and 2a. Thereafter, in order to obtain ohmic characteristics of the contact electrode film 2, for example, a heat treatment of 500 ° C. to 1300 ° C. is performed on the substrate. As a result, the contact electrode film 2 is silicided at the interface with the substrate 1 to form an ohmic contact therebetween. In this way, a semiconductor substrate having a region for forming a desired semiconductor element on the substrate surface and the contact electrode film 2 covering the substantially entire surface on the back surface side of the substrate is manufactured.

Thus, also in this comparative example , the contact electrode film 2 is patterned in such a manner that the contact region is subdivided over substantially the entire back surface of the substrate. For this reason, even in the high temperature treatment for obtaining the ohmic contact (ohmic characteristics) of the contact electrode film 2, the application of stress due to the high temperature treatment is separated and dispersed through the pattern. Warpage of the substrate due to heating is suppressed.

As described above, according to the semiconductor substrate and the manufacturing method thereof according to this comparative example , in addition to the effects similar to the effects (1) to (7) in the first comparative example or effects equivalent thereto. Further, the following effects can be obtained.

  (13) The contact electrode film 2 is patterned using a step (trench T) provided on the base. As a result, not only patterning on the same plane but also patterning in the substrate depth direction using the step of the base, that is, the trench T, can be realized, and thus a more flexible pattern design can be realized.

  (14) Further, the trench T makes it possible to easily separate the silicide region as a contact region of the contact electrode film 2 and further reduce the stress due to the high-temperature treatment described above.

  (15) The depth dimension i of the trench T is set larger than the film thickness dimension j of the contact electrode films 2 and 2a. As a result, the semiconductor substrate can be manufactured more easily.

(Other embodiments)
In addition, you may implement by changing each said comparative example and embodiment as follows.
In the embodiment above you facilities, as the material of the contact electrode film 2, Ti, Ni, Au, Co, Fe, Mg, Ca, Mn, while adopting any one of Mo, the mask material 3 material As described above, any one of W, Pt, and Cr is adopted. However, the present invention is not limited thereto, and a material that satisfies the condition “ΔG <0” is adopted as the material of the contact electrode film 2 and a material that satisfies the condition “ΔG> 0” is adopted as the material of the mask material 3. Thus, an effect according to the effect (9) can be obtained.

- in the form of the implementation is the mask material 3 for patterning the contact electrode film 2, it is assumed to have a pattern as cutting are removed rests on the scribe line at the time of dicing, the this essential constituent Absent. The pattern of the mask material 3 may be any pattern as long as it corresponds to the non-contact region of the contact electrode film 2, and is basically arbitrary in that range.

- Also, in the same implementation, upon manufacturing the semiconductor device, the thickness dimension e of the mask material 3, but was set to be smaller than the thickness dimension f of the contact electrode film 2, which Is not an essential configuration. The relationship of these dimensions is also arbitrary like the pattern of the mask material 3.

- Also, in the same implementation were the mask material 3 at the time of dicing as cutting and removing. However, this is not an essential process.
In the second comparative example , when manufacturing the semiconductor device, the depth dimension i of the trench T is set larger than the film thickness dimension j of the contact electrode films 2 and 2a. This is also not an essential configuration. It is sufficient that the contact electrode film 2 is patterned into a desired pattern by the trench T, and the relationship between the dimensions i and j can be basically set arbitrarily.

In each of the comparative examples and embodiments, a semiconductor substrate made of silicon carbide is employed as the substrate 1. However, the present invention is not limited to this, and the above structure and manufacturing method can be similarly applied to any semiconductor substrate that requires high-temperature treatment after the formation of the contact electrode film.

In each of the above comparative examples and embodiments, the contact electrode film 2 is silicided at the interface with the substrate 1. However, this is not an essential configuration, and it is sufficient if an ohmic contact (ohmic characteristic) is obtained.

In the comparative examples and embodiments described above, the dimension between the electrodes is set smaller than the dimension of the electrode width. However, this is not an essential configuration.
In each of the above comparative examples and embodiments, the contact electrode film 2 is formed as a contact region with a collective pattern made up of a large number of squares over substantially the entire back surface of the substrate. However, the contact electrode film 2 is not limited to this, and for example, a contact region formed with a collective pattern made of a polygon other than a square (rectangle, triangle, pentagon, hexagon, octagon, etc.) It can be adopted as appropriate.

  Furthermore, a layout pattern as shown in FIGS. 7A and 7B can be appropriately employed as the layout pattern of the contact electrode film 2. FIG. 7A is a plan view corresponding to FIG. 1 and schematically shows a planar structure viewed from the back side of the semiconductor substrate. Moreover, FIG.7 (b) is a top view which expands and shows a part of Fig.7 (a).

  As shown in FIG. 7A, here, the contact electrode film 2 is formed as a contact region with a collective pattern composed of a large number of small circles extending over substantially the entire back surface of the substrate. More specifically, for example, as shown in FIG. 7B, when the radius of each small circle is r and the distance between the centers of the small circles is k, these dimensions satisfy the relationship “2r <k”. Like that. This ensures that these small circles are separated from each other. Furthermore, it is desirable that these small circles be arranged so as to be separated from each other to such an extent that the silicided portions do not contact even after the heat treatment.

  In such a structure, since the contact electrode film 2 has a collective pattern having a circular shape without corners, a process abnormality due to a resist residue or the like during the patterning is suitably suppressed. On the other hand, even in the aggregate pattern composed of the polygonal shapes, the same effect can be obtained by making the polygonal shapes rounded.

In each of the comparative examples and embodiments, the contact electrode film 2 is patterned in such a manner that the contact region is subdivided over substantially the entire back surface of the substrate. However, the present invention is not limited to this, and the contact electrode film 2 only needs to be patterned in such a manner that the contact region is completely separated into at least two parts. Effects according to the effects can be obtained.

  ・ Furthermore, even if a high temperature treatment is required after the formation of the contact electrode film, the intended purpose of suppressing the warpage of the substrate due to the heating of the treatment is not dependent on the thickness of the substrate. The contact electrode film 2 can be obtained as long as it is patterned so as to relieve stress on the substrate 1. That is, for example, the contact electrode film 2 may be patterned with a pattern obtained based on a structural analysis by a finite element method or the like.

The top view which shows typically the schematic structure of the semiconductor substrate about the 1st comparative example . (A) And (b) is sectional drawing which shows the manufacturing process about the manufacturing method of the semiconductor substrate which concerns on the said 1st comparative example . The top view which shows typically the schematic structure of the semiconductor substrate about one Embodiment of the semiconductor substrate which concerns on this invention, and its manufacturing method. (A) ~ (c) are cross-sectional views showing a manufacturing process for manufacturing a semiconductor substrate according to the embodiment of the implementation. The top view which shows typically the schematic structure of the semiconductor substrate about the 2nd comparative example . (A) And (b) is sectional drawing which shows the manufacturing process about the manufacturing method of the semiconductor substrate which concerns on the 2nd comparative example . (A) is a top view which shows another example of the layout pattern of a contact electrode film | membrane, (b) is a top view which expands and shows a part of (a). (A) And (b) is sectional drawing which shows an example of the conventional semiconductor substrate and its manufacturing method. Sectional drawing which shows the one aspect | mode of board | substrate curvature.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Substrate, 2, 2a ... Contact electrode film, 3 ... Mask material, T ... Trench.

Claims (8)

A semiconductor substrate having a region for forming a desired semiconductor element on the substrate surface, and a contact electrode film covering the substantially entire surface on the back surface side of the substrate;
A mask material having a pattern corresponding to a non-contact region of a contact electrode film covering substantially the entire back surface of the substrate is provided on the back surface of the substrate, and the contact electrode film is formed according to the pattern of the mask material. Ri Na is patterned in the form to relieve stress on the substrate, when the Gibbs free energy change before and after reaction with the substrate and .DELTA.G, the contact electrode layer is made of materials satisfying comprising ".DELTA.G <0", the A semiconductor substrate characterized in that a mask material for patterning a contact electrode film is made of a material that satisfies a condition of “ΔG> 0” . The semiconductor substrate according to claim 1, wherein the mask material for patterning the contact electrode film is formed with a pattern that is placed on a scribe line and cut off during dicing. The semiconductor substrate is a semiconductor substrate made of silicon carbide, and the contact electrode film is made of any one of Ti, Ni, Au, Co, Fe, Mg, Ca, Mn, and Mo, and the contact electrode film is patterned. the semiconductor substrate according to the mask material W, Pt, according to claim 1 or 2 consisting of one of Cr. Prior to forming a contact electrode film covering the entire surface on the back surface side of the semiconductor substrate having a region for forming a desired semiconductor element on the surface, the contact electrode film is not formed on the back surface of the semiconductor substrate. Forming a mask material having a pattern corresponding to the contact region, and then relieving the stress on the substrate on the back surface of the substrate on which the mask material is formed according to the pattern of the mask material. A method of manufacturing a semiconductor substrate for forming a film on a substrate,
When the change in Gibbs free energy before and after reaction with the semiconductor substrate is ΔG, the contact electrode film is formed of a material that satisfies the condition of “ΔG <0”, and a mask material for patterning the contact electrode film is “ΔG A method of manufacturing a semiconductor substrate, comprising forming a material that satisfies a condition> 0 . The method for manufacturing a semiconductor substrate according to claim 4 , wherein a film thickness of the mask material is set smaller than a film thickness of the contact electrode film. The method for manufacturing a semiconductor substrate according to claim 4 , wherein after forming the contact electrode film, an appropriate heat treatment is performed to silicide the contact electrode film at an interface with the semiconductor substrate. The method for manufacturing a semiconductor substrate according to claim 4 , wherein a mask material having a pattern corresponding to a non-contact region of the contact electrode film is cut and removed during dicing. The method for manufacturing a semiconductor substrate according to any one of claims 4 to 7 , wherein the semiconductor substrate is a semiconductor substrate made of silicon carbide.

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