JP5532527B2 - SOI substrate and manufacturing method thereof - Google Patents

Description

  The present invention relates to an SOI (Silicon on insulator) substrate and a method for manufacturing the same that can prevent a decrease in device reliability due to contamination by heavy metals contained in the substrate from the beginning or mixed in the manufacturing process.

  Conventionally, as a method for effectively removing heavy metal contamination and the like from an active layer on which a semiconductor device is formed, a method of providing an IG layer inside the substrate or forming a gettering layer on the back side of the substrate has been used. However, when an SOI substrate is used as a semiconductor substrate, unlike a normal bulk substrate, diffusion of heavy metals such as Fe and Ni is blocked by a buried oxide film, so it is effective to simply provide a gettering site in a support substrate. There is no. For this reason, the methods shown in Patent Documents 1 and 2 have been proposed as methods for gettering heavy metal contamination caused by heavy metals contained in the SOI substrate from the beginning or heavy metals mixed during the manufacturing process.

In Patent Document 1, a polycrystalline silicon film having a gettering function is provided between an active layer and a buried oxide film. Patent Document 2 has a structure in which a region where a buried oxide film is not partially formed is provided and some gettering means is provided on a support substrate or the back surface of the substrate.
Japanese Patent Laid-Open No. 02-260428 JP-A-5-82525

  However, the technique shown in Patent Document 1 is a method of gettering heavy metal at the grain boundary of polycrystalline silicon, and the polycrystalline silicon film is recrystallized with heat treatment during the wafer bonding process and semiconductor device manufacturing process. Since the crystal grain size increases, the area of the crystal grain boundary, which is the site for gettering heavy metals, decreases, and the effect decreases as the device formation process proceeds.

  Further, in the method shown in Patent Document 2, gettering is possible if the structure has a region where a buried oxide film is not partially formed as described above. However, an advantage of using an SOI substrate, for example, The effect of reducing leakage current and stray capacitance is reduced.

  In view of the above points, the present invention has an object to ensure a gettering effect in an SOI substrate.

In order to achieve the above object, in the present invention, a support substrate (1) made of a semiconductor material, a buried oxide film (2) formed on the support substrate (1), and a buried oxide film (2) are provided. The active layer (4) disposed on the opposite side of the support substrate (1) with the semiconductor material between the buried oxide film (2) and the active layer (4), or the support substrate (1). And a layer for forming a lattice strain (3) that generates lattice strain in the active layer (4) during heat treatment based on a difference in thermal expansion coefficient from the active layer (4). 10) and a lattice strain layer formed on the active layer (4) by the lattice strain formation layers (3, 10) .

Thus, a lattice strain layer is formed in the active layer (4) between the buried oxide film (2) and the active layer (4) or between the support substrate (1) and the buried oxide film (2). Layers (3, 10) for forming a lattice strain are provided. That is, the lattice strain forming layers (3, 10) are formed in a part of the active layer (4) or in contact with the buried oxide film (2) on the support substrate (1) side.

For this reason, when the lattice strain forming layers (3, 10) are disposed between the buried oxide film (2) and the active layer (4), the heat treatment during the wafer bonding process or the semiconductor device manufacturing process is performed. It is possible to form a lattice strain layer in the active layer (4) by generating lattice strain between them. Further, when the lattice strain forming layers (3, 10) are disposed between the support substrate (1) and the buried oxide film (2), the buried oxide film (2) having a small thermal expansion coefficient is interposed therebetween. The buried oxide film (2) and the active layer are formed on the basis of the difference in thermal expansion coefficient between the lattice strain forming layers (3, 10) and the active layer (4), although the effect is smaller than the case where the effect acts directly. When the lattice strain forming layers (3, 10) are not formed, the lattice strain generated between (4) and (4) can be generated between the buried oxide film (2) and the active layer (4). More than the lattice distortion.

Therefore, since the lattice strain layer is formed in the active layer (4) by this lattice strain and functions as a gettering site, the SOI layer does not deteriorate in function due to the heat treatment and does not impair the advantages of the SOI substrate. It is possible to ensure a gettering effect on the substrate.

  For example, as the lattice strain forming layer, a SiC-containing layer (3) or a SiN-containing layer (10) can be used.

In the present invention, the supporting substrate (1) made of a semiconductor material, the embedded insulating film (20) formed on the supporting substrate (1), and the supporting substrate ( An active layer (4) disposed on the opposite side of 1) and made of a semiconductor material ; and a lattice-strained layer formed in the active layer (4) by a buried insulating film (20) , the buried insulating film (20), S iN-containing layer is constituted by at least one of the Al ₂ O ₃ layer or TiO ₂ layer, based on the difference in thermal expansion coefficient between the active layer (4), the active layer during the heat treatment ( The second feature is that it functions as a lattice strain forming layer for generating lattice strain in the active layer (4) by generating lattice strain in 4) .

Thus, instead of the buried insulating film (20) oxide film, and an insulating layer such as a direct S i ₃ N ₄ layer or the Al ₂ O ₃ layer or TiO ₂ layer, which supporting substrate (1) And the active layer (4). In the case of such a structure, the difference in thermal expansion coefficient between the buried insulating film (20) and the active layer (4) increases, and these heat treatments are performed during the wafer bonding process and the semiconductor device manufacturing process. It is possible to form a lattice strain layer in the active layer (4) by generating lattice strain therebetween . Since the lattice strain layer formed in the active layer (4) by this lattice strain functions as a gettering site, the function does not deteriorate with heat treatment, and the advantages of the SOI substrate are not impaired. The gettering effect can be surely obtained, and the same effect as the first feature can be obtained.

The SOI substrate having the first feature of the present invention includes, for example, a step of preparing a first semiconductor substrate (5) made of a semiconductor material, and a second semiconductor substrate (1) made of a semiconductor material. Preparing a buried oxide film (2) on the second semiconductor substrate (1), on the first semiconductor substrate (5), or on the buried oxide film (2), A lattice strain forming layer for forming a lattice strain layer in the active layer (4) by generating lattice strain in the active layer (4) during heat treatment based on a difference in thermal expansion coefficient from the active layer (4) (3, 10) and the first semiconductor substrate (5) and the second semiconductor substrate (1) so as to sandwich the buried oxide film (2) and the lattice strain formation layers (3, 10). Bonding process and any of the first semiconductor substrate (5) and the second semiconductor substrate (1) Forming an active layer (4) or one by causing thinning can be produced by inclusive manufacturing method.

Similarly, a step of preparing a first semiconductor substrate (5) made of a semiconductor material, a step of preparing a second semiconductor substrate (1) made of a semiconductor material, and a first semiconductor substrate (5) Difference in thermal expansion coefficient between the step of forming the buried oxide film (2) on the first semiconductor substrate (1) and the active layer (4) on the second semiconductor substrate (1) or on the buried oxide film (2). A step of forming lattice strain forming layers (3, 10) for forming a lattice strain layer in the active layer (4) by generating lattice strain in the active layer (4) during heat treatment; Bonding the first semiconductor substrate (5) and the second semiconductor substrate (1) so that the film (2) and the lattice strain forming layers (3, 10) are sandwiched, and the first semiconductor substrate (5) or Active layer by thinning one of the second semiconductor substrates (1) 4) forming a, even inclusive manufacturing method capable of manufacturing an SOI substrate having a first feature of the present invention.

  In these manufacturing methods, the lattice strain forming layer is an implanted layer (6, 8) into which ions are implanted to form the lattice strain forming layer, that is, when the SOI substrate is finally completed. The concept including what is changed to the lattice strain forming layer is shown.

On the other hand, the SOI substrate having the second feature of the present invention includes, for example, a step of preparing a semiconductor substrate (5) for forming an active layer (4) made of a semiconductor material, and a semiconductor material. A supporting substrate (1), a step of forming a buried insulating film (20) on the supporting substrate (1) or the semiconductor substrate (5), and a buried insulating film (20) The embedded insulating film (20) is formed by a manufacturing method including a step of bonding the support substrate (1) and the semiconductor substrate (5) so as to be sandwiched and a step of thinning the semiconductor substrate (5). In the process, a buried insulating film (20) is formed by at least one of an SiN-containing layer, an Al ₂ O ₃ layer, or a TiO ₂ layer, and the buried insulating film (20) is heated with the active layer (4). Based on difference in expansion coefficient , It is sufficient to function as the lattice strain forming layer to form a lattice-strained layer by generating the lattice strain in the active layer (4) during the heat treatment.

  In addition, the code | symbol in the bracket | parenthesis of each said means shows the correspondence with the specific means as described in embodiment mentioned later.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, the same or equivalent parts are denoted by the same reference numerals in the drawings.

(First embodiment)
A first embodiment of the present invention will be described. FIG. 1 is a diagram showing a cross-sectional structure of an SOI substrate to which this embodiment is applied.

As shown in FIG. 1, a silicon oxide film (SiO ₂ ) 2 that functions as a buried oxide film is formed on the entire surface of a single crystal silicon substrate 1 that functions as a support substrate, and an SiC film itself or SiC bond is formed thereon. SiC-containing layer 3 functioning as a lattice strain forming layer in which is mixed is formed. Further, a single crystal silicon layer 4 functioning as an active layer is provided on the surface of the SiC-containing layer 3. With such a structure, the SOI substrate of this embodiment is configured.

  According to the SOI substrate configured as described above, the following effects can be obtained.

  The problem with the SOI substrate disclosed in Patent Document 1 described above is that the gettering site uses a film that deteriorates in function due to an inevitable heat treatment during the wafer bonding process or semiconductor manufacturing process. Caused by a cause. Further, the problem with the SOI substrate disclosed in Patent Document 2 is caused by providing a region where a buried oxide film is not partially formed for gettering on the back surface of the substrate or in the support substrate. For this reason, it is necessary to make it function as a gettering site without having a structure provided with a region where a buried oxide film is not partially formed without causing a function deterioration due to heat treatment.

  On the other hand, in the SOI substrate of this embodiment, the SiC-containing layer 3 is disposed between the silicon oxide film 2 that functions as a buried oxide film and the silicon layer 4 that functions as an active layer. That is, the SiC-containing layer 3 is formed in a part of the active layer. When the silicon layer 4 is formed directly on the surface of the silicon oxide film 2, the Young's modulus of the silicon oxide film 2 is smaller than that of the silicon layer 4 and a sufficient lattice distortion cannot be generated in the silicon layer 4, but as in the present embodiment. By forming the SiC-containing layer 3 having a larger coefficient of thermal expansion and Young's modulus than the single crystal silicon on the surface of the silicon oxide film 2, these heat treatments are performed during the wafer bonding process and the semiconductor device manufacturing process. Lattice distortion can be generated between them.

  And since this lattice distortion functions as a gettering site, the gettering effect is surely obtained in the SOI substrate without causing functional degradation due to heat treatment and without losing the advantages of the SOI substrate. It becomes possible.

  As a result, it is possible to manufacture a semiconductor device having an SOI structure using an SOI substrate with improved reliability by suppressing deterioration due to heavy metal contamination.

The thermal expansion coefficient of single crystal silicon is about 2.5 × 10 ⁻⁶ (/ K), and the thermal expansion coefficient of SiC is about 4.5 × 10 ⁻⁶ (/ K).

  Subsequently, a method for manufacturing an SOI substrate according to the present embodiment will be described. FIG. 2 is a cross-sectional view showing the manufacturing process of the SOI substrate of this embodiment, and will be described with reference to this figure.

First, as shown in FIG. 2A, a single crystal silicon substrate 5 is prepared for forming a silicon layer 4 serving as an active layer for forming a device. The silicon substrate 1 is, for example, a CZ substrate. For example, boron is implanted as an impurity to change the conductivity type to P type, the crystal plane orientation is <100>, the resistivity is 1 to 50 Ωcm, and the initial oxygen concentration is 1.5. What was made into * 10 < ¹⁸ > cm <^-3> or less can be used.

Next, as shown in FIG. 2B, carbon (C) is ion-implanted over the entire surface of the silicon substrate 5 at a dose of 1 × 10 ¹⁶ atoms / cm ² or more to form a carbon ion-implanted layer 6. . As another method, a SiC film may be formed on the silicon substrate 5 by a solid phase growth method. As yet another method, a SiC film may be formed on the silicon substrate 5 by a CVD method or the like.

On the other hand, as shown in FIG. 2 (c), After preparing a silicon substrate 1 as a supporting substrate single _{crystal, 900~1100 ℃, H 2: O} 2 = 1: 1~2: 1 partial pressure ratio conditions 2D, a silicon oxide film 2 is grown on the surface of the silicon substrate 1 as shown in FIG.

  Subsequently, as shown in FIG. 2E, the silicon substrate 1 on which the silicon oxide film 2 is formed and the silicon substrate 5 on which the carbon ion implantation layer 6 is formed are combined with the silicon oxide film 2 and the carbon ion implantation layer 6. Butt to face. And these are bonded together by performing the heat processing for about 2-5 hours at 1100 degreeC. During this heat treatment, the SiC-containing layer 3 in which SiC in the carbon ion implanted layer 6 is diffused and SiC bonds are mixed is formed.

  Thereafter, in order to form an active layer in the element region, the silicon layer 4 is obtained by grinding and polishing the single crystal silicon substrate 5 to a predetermined thickness (for example, about 0.1 to 20 μm) by CMP or the like. Form. Thereby, the SOI substrate having the structure shown in FIG. 1 can be manufactured. If a semiconductor element is formed in the silicon layer 4 using such an SOI substrate, a good semiconductor element in which deterioration due to heavy metal contamination is suppressed can be formed.

(Second Embodiment)
A second embodiment of the present invention will be described. In the present embodiment, a structure in which the same structure as the SOI substrate shown in FIG. 1 in the first embodiment is manufactured by another method will be described.

  FIG. 3 is a cross-sectional view showing the manufacturing process of the SOI substrate of this embodiment, and will be described with reference to this figure.

  First, in the step shown in FIG. 3A, a single-crystal silicon substrate 5 for forming a silicon layer 4 serving as an active layer for forming a device is prepared. As this silicon substrate 1, for example, the one shown in FIG.

On the other hand, as shown in FIG. 3B, after preparing a single crystal silicon substrate 1 as a support substrate, conditions of partial pressure ratio of 900 to 1100 ° C. and H ₂ : O ₂ = 1: 1 to 2: 1. Then, as shown in FIG. 3C, a silicon oxide film 7 is grown on the surface of the silicon substrate 1. Thereafter, as shown in FIG. 3D, carbon (C) is ion-implanted at a dose of 1 × 10 ¹⁷ atoms / cm ² or more over the entire surface layer portion of the silicon oxide film 7 to form a carbon ion-implanted layer 8. To do. As another method, the SiC thin film layer may be formed by a CVD method or the like.

  Subsequently, as shown in FIG. 3E, the silicon substrate 1 and the silicon substrate 5 on which the silicon oxide film 7 and the carbon ion implanted layer 8 are formed are connected so that the carbon ion implanted layer 6 is in contact with the silicon substrate 5. Match. And these are bonded together by performing the heat processing for about 2-5 hours at 1100 degreeC. During this heat treatment, C in the carbon ion implanted layer 6 is diffused to form a SiC-containing layer 3 in which SiC bonds are mixed, and the remaining silicon oxide film 7 forms the silicon oxide film 2 shown in FIG. The

  Thereafter, in order to form an active layer in the element region, the silicon layer 4 is obtained by grinding and polishing the single crystal silicon substrate 5 to a predetermined thickness (for example, about 0.1 to 20 μm) by CMP or the like. Form. Thereby, the SOI substrate having the structure shown in FIG. 1 can be manufactured. If a semiconductor element is formed in the silicon layer 4 using such an SOI substrate, a good semiconductor element in which deterioration due to heavy metal contamination is suppressed can be formed.

(Third embodiment)
A third embodiment of the present invention will be described. The SOI substrate of the present embodiment is different from the first embodiment in that the structure of the lattice strain forming layer is changed, specifically, the SiN-containing layer 10 is provided instead of the SiC-containing layer 3. In addition, the SiN-containing layer 10 generates lattice distortion between the silicon oxide film 2 and the silicon layer 4. Since other aspects are the same as those in the first embodiment, only portions different from those in the first embodiment will be described.

  FIG. 4 is a cross-sectional view of the SOI substrate according to the present embodiment. As shown in this figure, the SOI substrate of this embodiment is obtained by forming a SiN-containing layer 10 on a silicon oxide film 2 of a single crystal silicon substrate 1 instead of the SiC-containing layer 3 shown in FIG. It is.

  As described above, even when the SiN-containing layer 10 having a larger thermal expansion coefficient than that of single crystal silicon is formed in the lower layer of the silicon layer 4, these heat treatments are performed during the wafer bonding process and the semiconductor device manufacturing process. Lattice distortion can be generated between them. For this reason, the effect similar to 1st Embodiment can be acquired.

The thermal expansion coefficient of single crystal silicon is about 2.5 × 10 ⁻⁶ (/ K), and the thermal expansion coefficient of SiN is about 3.0 × 10 ⁻⁶ (/ K).

The manufacturing method of this SOI substrate is basically the same as the manufacturing method shown in FIG. 2 in the first embodiment, and only the point shown in FIG. 2B is changed to the step of forming the SiN-containing layer 10. Different. For example, the SiN-containing layer 10 can be formed by thermally nitriding the silicon substrate 5 at 1050 ° C. in an NH ₃ atmosphere. As another method, the SiN-containing layer 10 can be formed by nitriding the silicon substrate 5 with N plasma. As yet another method, a nitrogen ion implantation layer may be formed by ion implanting nitrogen at a dose of 1 × 10 ¹⁶ atoms / cm ² or more over the entire surface of the silicon substrate 5. As yet another method, a SiN thin film layer may be formed on the silicon substrate 5 by a CVD method.

  On the other hand, similarly to the steps shown in FIGS. 2C and 2D, after the silicon oxide film 2 is grown on the surface of the silicon substrate 1, the silicon substrate 1 on which the silicon oxide film 2 is formed and the SiN-containing layer 10 are formed. The silicon substrate 5 on which the (or nitrogen ion implanted layer) is formed is abutted so that the silicon oxide film 2 and the SiN-containing layer 10 (or nitrogen ion implanted layer) are in contact with each other. And these are bonded together by performing the heat processing for about 2-5 hours at 1100 degreeC. When the silicon substrate 5 on which the nitrogen ion implanted layer is formed is bonded, N in the nitrogen ion implanted layer is diffused during the heat treatment to form the SiN-containing layer 10 in which SiN bonds are mixed.

  Thereafter, in order to form an active layer in the element region, the silicon layer 4 is obtained by grinding and polishing the single crystal silicon substrate 5 to a predetermined thickness (for example, about 0.1 to 20 μm) by CMP or the like. Form. Thereby, the SOI substrate having the structure shown in FIG. 3 can be manufactured. If a semiconductor element is formed in the silicon layer 4 using such an SOI substrate, a good semiconductor element in which deterioration due to heavy metal contamination is suppressed can be formed.

  Here, an example of the method for manufacturing the SOI substrate shown in FIG. 4 has been shown. However, as in the second embodiment, the silicon oxide film 2 and the SiN-containing layer 10 are formed on the silicon substrate 1 serving as the support substrate. Alternatively, the silicon substrate 5 serving as an active layer may be bonded.

(Fourth embodiment)
A fourth embodiment of the present invention will be described. The SOI substrate according to the present embodiment is different from the first and second embodiments in that a SiC layer, a Si ₃ N ₄ layer, or an Al ₂ O ₃ is used instead of the buried oxide film, that is, the silicon oxide film 2 that functions as a buried insulating film. An insulating layer such as a layer or a TiO ₂ layer is formed on a single crystal silicon substrate 1, and this insulating layer is made to function as a lattice strain forming layer. Since other aspects are the same as those in the first embodiment, only portions different from those in the first embodiment will be described.

FIG. 5 is a cross-sectional view of the SOI substrate according to the present embodiment. As shown in this figure, the SOI substrate of this embodiment is an insulating layer such as a SiC layer, a Si ₃ N ₄ layer, an Al ₂ O ₃ layer, or a TiO ₂ layer, instead of the silicon oxide film 2 shown in FIG. The structure includes the layer 20.

Thus, instead of the silicon oxide film 2, the insulating layer 20 such as a direct SiC layer, Si ₃ N ₄ layer, Al ₂ O ₃ layer, or TiO ₂ layer is used as the supporting substrate and the silicon substrate 1 as the active layer. It can also be arranged between the layers 4.

  In such a structure, since the insulating layer 20 having a thermal expansion coefficient larger than that of single crystal silicon is formed below the silicon layer 4, the heat between the silicon oxide film 2, the insulating layer 20, and the silicon layer 4 is formed. The difference in expansion coefficient is enlarged, and lattice distortion can be generated between the wafer bonding process and the heat treatment in the semiconductor device manufacturing process. Since this lattice strain functions as a gettering site, the gettering effect can be surely obtained in the SOI substrate without causing a function deterioration due to the heat treatment and without losing the advantages of the SOI substrate. It becomes possible and the same effect as a 1st embodiment can be acquired.

The thermal expansion coefficient of single crystal silicon is about 2.5 × 10 ⁻⁶ (/ K), the thermal expansion coefficient of SiC is about 4.5 × 10 ⁻⁶ (/ K), and the thermal expansion coefficient of SiN is About 3.0 × 10 ⁻⁶ (/ K), Al ₂ O _{3 has} a thermal expansion coefficient of about 3.9 to 9.3 × 10 ⁻⁶ (/ K), and TiO _{2 has} a thermal expansion coefficient of 7.1 to It is about 9.2 × 10 ⁻⁶ (/ K).

  Subsequently, a method for manufacturing an SOI substrate according to the present embodiment will be described. FIG. 6 is a cross-sectional view showing the manufacturing process of the SOI substrate of this embodiment, and will be described with reference to this figure.

  First, as shown in FIG. 6A, a single crystal silicon substrate 5 is prepared for forming a silicon layer 4 serving as an active layer for forming a device. As this silicon substrate 1, for example, the one shown in FIG. Next, as shown in FIG. 6B, the carbon ion implanted layer 6 is formed on the entire surface of the silicon substrate 5 by the same process as that shown in FIG.

  On the other hand, as shown in FIG. 6C, a single crystal silicon substrate 1 to be a support substrate is prepared. Thereafter, as shown in FIG. 6D, the silicon substrate 1 and the silicon substrate 5 on which the carbon ion implanted layer 6 is formed are abutted so that the carbon ion implanted layer 6 is in contact with the silicon substrate 1. And these are bonded together by performing the heat processing for about 2-5 hours at 1100 degreeC. During this heat treatment, the insulating layer 20 is formed of a SiC-containing layer in which C in the carbon ion implanted layer 6 diffuses and SiC bonds are mixed.

  Thereafter, in order to form an active layer in the element region, the silicon layer 4 is obtained by grinding and polishing the single crystal silicon substrate 5 to a predetermined thickness (for example, about 0.1 to 20 μm) by CMP or the like. Form. Thereby, the SOI substrate having the structure shown in FIG. 1 can be manufactured. If a semiconductor element is formed in the silicon layer 4 using such an SOI substrate, a good semiconductor element in which deterioration due to heavy metal contamination is suppressed can be formed.

Here, an example in which the carbon ion implanted layer 6 is formed on the entire surface of the silicon substrate 5 and the insulating layer 20 made of the SiC-containing layer is formed from the carbon ion implanted layer 6 has been described. Instead of this, the insulating layer 20 made of Si ₃ N ₄ layer, Al ₂ O ₃ layer, TiO ₂ layer or the like may be formed by, for example, the CVD method.

  Here, an example is shown in which the insulating layer 20 or the carbon ion implantation layer 6 for forming the insulating layer 20 is formed on the silicon substrate 5 side that functions as an active layer, but the silicon substrate 1 side that functions as a support substrate is shown. You may make it provide in.

(Fifth embodiment)
A fifth embodiment of the present invention will be described. The SOI substrate according to the present embodiment is obtained by reversing the arrangement of the silicon oxide film 2 and the SiC-containing layer 3 or the SiN-containing layer 10 as the buried oxide film with respect to the first and second embodiments. Since it is the same as that of 1st Embodiment, only a different part from 1st Embodiment is demonstrated.

  FIG. 7 is a cross-sectional view of the SOI substrate according to the present embodiment. As shown in this figure, in the SOI substrate of the present embodiment, a SiC-containing layer 3 and a silicon oxide film 2 are formed in order on the entire surface of a silicon substrate 1 serving as a support substrate, and active on the surface of the silicon oxide film 2. The silicon layer 4 to be a layer is formed.

  Even with such a structure, the silicon oxide film 2 and the silicon layer 4 are less effective compared to the case where the effect is directly exerted because of the action through the buried oxide film (2) having a small thermal expansion coefficient. It is possible to cause lattice distortion between the two. More specifically, the lattice strain generated between the silicon oxide film 2 and the silicon layer 4 based on the difference in thermal expansion coefficient between the SiC-containing layer 3 and the silicon oxide film 2 does not form the SiC-containing layer 3. In this case, the lattice distortion is sufficiently larger than the lattice distortion that can occur between the silicon oxide film 2 and the silicon layer 4.

  For this reason, the lattice distortion generated between the silicon oxide film 2 and the silicon layer 4 can function as a gettering site, the function does not deteriorate with heat treatment, and the advantage of the SOI substrate is not impaired. In addition, the gettering effect can be surely obtained in the SOI substrate, and the same effect as in the first embodiment can be obtained.

  In addition, the manufacturing method of the SOI substrate having such a structure only needs to replace the support substrate and the active layer in the step shown in FIG. 2 in the first embodiment and the step shown in FIG. 3 in the second embodiment. .

  Here, the SiC-containing layer 3 is taken as an example of the lattice strain forming layer, but the same can be said even if it is replaced with the SiN-containing layer 10 described in the third embodiment.

(Other embodiments)
In each of the above embodiments, the SiC-containing layer 3, the SiN-containing layer 10, or the insulating layer 20, which has a larger thermal expansion coefficient than the single crystal silicon, is formed on the entire lower layer of the single crystal silicon layer 4. The same effect as described above can be obtained by forming a part of the silicon layer 4 instead of the entire lower layer, such as a dot shape or a mesh shape.

  In each of the above embodiments, the case where single crystal silicon is used as a semiconductor material, such as the silicon substrate 1 or the silicon layer 4, has been described. However, the case where another semiconductor material such as GaAs is used is also described. The invention can be applied. That is, in each of the above embodiments, since the silicon oxide film 2 functioning as a buried insulating film is softer than the silicon layer 4, lattice strain cannot be formed in the silicon layer 4 serving as the active layer. The SiC-containing layer 3, the SiN-containing layer 10, or the insulating film 20 is formed as a lattice strain forming layer for forming the same, but the above-described effect can be obtained even when other semiconductor materials are used by causing the same action. It is possible.

For example, when GaAs is used as the semiconductor material, the thermal expansion coefficient of GaAs is a high value of about 7.0 × 10 ⁻⁶ (/ K), but the difference from the thermal expansion coefficient is large, and it is younger than GaAs. A lattice strain forming layer that has a high rate and can form lattice strain when GaAs is heat-treated may be disposed.

  Although not described in the above embodiments, of course, a gettering site may be formed in advance for the silicon substrate 5 for forming the active layer 4. In this way, even if the gettering site is reduced by heat treatment or the like, it is possible to prevent the gettering site from being reduced by the lattice distortion described above. Therefore, it is effective to form the gettering site in advance.

It is the figure which showed the cross-section of the SOI substrate to which 1st Embodiment of this invention was applied. FIG. 2 is a cross-sectional view showing a manufacturing process of the SOI substrate shown in FIG. It is sectional drawing which showed the manufacturing process of the SOI substrate which concerns on 2nd Embodiment of this invention. It is the figure which showed the cross-section of the SOI substrate to which 3rd Embodiment of this invention was applied. It is the figure which showed the cross-section of the SOI substrate to which 4th Embodiment of this invention was applied. FIG. 6 is a cross-sectional view showing a manufacturing process of the SOI substrate shown in FIG. 5. It is the figure which showed the cross-section of the SOI substrate to which 5th Embodiment of this invention was applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Silicon substrate, 2 ... Silicon oxide film, 3 ... SiC containing layer, 4 ... Silicon layer,
5 ... Silicon substrate, 6 ... Carbon ion implantation layer, 7 ... Silicon oxide film,
8 ... carbon ion implanted layer, 10 ... SiN-containing layer, 20 ... insulating layer.

Claims (2)

A support substrate (1) made of a semiconductor material;
A buried insulating film (20) formed on the support substrate (1);
An active layer (4) disposed on the opposite side of the support substrate (1) across the buried insulating film (2) and made of a semiconductor material;
A lattice-strained layer formed on the buried insulating film (20) side of the active layer (4) by the buried insulating film (20) ,
The buried insulating film (20) is composed of any one of a SiN-containing layer, an Al ₂ O ₃ layer, or a TiO ₂ layer, and is subjected to a heat treatment based on a difference in thermal expansion coefficient from the active layer (4). It functions as a lattice strain forming layer for generating lattice strain on the active layer (4) by generating lattice strain on the buried insulating film (20) side of the active layer (4). SOI substrate. Preparing a semiconductor substrate (5) for forming an active layer (4) composed of a semiconductor material;
Preparing a support substrate (1) made of a semiconductor material;
Forming a buried insulating film (20) on the support substrate (1) or on the semiconductor substrate (5);
Bonding the support substrate (1) and the semiconductor substrate (5) so as to sandwich the buried insulating film (20);
Forming the active layer (4) by thinning the semiconductor substrate (5),
Wherein in the step of forming a buried insulating film (20) is, SiN-containing layer, the buried insulating layer (20) is formed by any one of the Al ₂ O ₃ layer or TiO ₂ layer, the buried insulating film (20) Based on the difference in thermal expansion coefficient with the active layer (4), a lattice strain layer is formed by generating lattice strain on the buried insulating film (20) side of the active layer (4) during heat treatment. A method for manufacturing an SOI substrate, which functions as a lattice strain forming layer.

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