JP4649282B2 - Semiconductor substrate manufacturing method and semiconductor device manufacturing method - Google Patents

Description

  The present invention relates to a method for manufacturing a semiconductor substrate and a method for manufacturing a semiconductor device, and more particularly to a technique for forming an SOI (Silicon on Insulator) structure on a semiconductor substrate.

Currently, in the semiconductor field, silicon-on-insulator (SOI) technology is being actively developed to reduce the power consumption of integrated circuits. In a device using an SOI substrate, it is known that the parasitic capacitance of a transistor can be significantly reduced, so that characteristics of higher speed and lower power consumption can be obtained than in a conventional device.
On the other hand, since the SOI substrate is manufactured by a special manufacturing apparatus such as a SIMOX method or a bonding method, the substrate cost is very high (typically about 5 to 10 times that of a bulk substrate). is there.). In addition, since the device using SOI has its special structure, there are some disadvantages such as a decrease in drain breakdown voltage and a decrease in electrostatic breakdown level. In order to solve these problems, a method of manufacturing a partial SOI structure on a bulk substrate has been proposed.

  For example, SBSI (Separation by Bonding Silicon Islands) technology disclosed in Non-Patent Document 1 is one of the proposed methods. According to the SBSI technology, a conventional semiconductor line can be manufactured, and only a desired region of a bulk substrate can be made into an SOI structure, which enables realization of an inexpensive and high-performance SOI device. .

In a specific manufacturing method, first, a SiGe layer and a Si layer are epitaxially grown on a Si substrate. Next, holes for a support are formed in the Si layer and the SiGe layer. Then, after a silicon oxide (SiO ₂ ) film or a silicon nitride (Si ₃ N ₄ ) film is formed as a support, the support is dry-etched into the shape of an element region, and the Si layer / SiGe layer is also continuously dried. Etch. When the SiGe layer is selectively etched with hydrofluoric acid in this state, a cavity is formed under the Si layer in a form in which the Si layer is suspended from the support. Thereafter, the SOI structure is obtained by filling the cavity with a SiO ₂ film by oxidation.
T, Sakai et al. “Separation by Bonding Si Islands (SBSI) for LSI Applications”, Second International SiGe Technology and Device Meeting Abstract, pp. 230-231, May (2004)

By the way, in the SBSI technique, when the support is formed of a SiO ₂ film or a Si ₃ N ₄ film, there are the following problems.
That is, when forming the support only of SiO ₂ film, SiO ₂ film forming the support when etching the SiGe layer with hydrofluoric nitric acid is also etched to some extent. Therefore, it is necessary to form a thick SiO ₂ film in anticipation of this etching amount. However, if the SiO ₂ film is formed thick, it becomes difficult to planarize the Si substrate after forming the SOI structure (Problem 1).

In addition, the Si ₃ N ₄ film is a film having a large stress, and the stress tends to work in a shrinking direction or an extending direction depending on the film forming conditions. For this reason, when the support is formed of only the Si ₃ N ₄ film, the Si ₃ N ₄ film cannot be formed thick due to the stress, and the rigidity of the support tends to be lowered. If the rigidity of the support is low, the Si layer cannot be sufficiently supported, and the Si layer may fall and crush the cavity (Problem 2).

  The present invention has been made in view of such circumstances, and is capable of simultaneously compensating for the drawbacks of using a silicon oxide film as a support and the disadvantages of using a silicon nitride film as a support. An object of the present invention is to provide a method for manufacturing a semiconductor substrate and a method for manufacturing a semiconductor device.

[Invention 1] In order to achieve the above object, a method of manufacturing a semiconductor substrate according to Invention 1 includes a step of forming a first semiconductor layer on a semiconductor substrate in a predetermined region, and an etching selection over the first semiconductor layer. Forming a second semiconductor layer having a small ratio on the first semiconductor layer, and supporting the second semiconductor layer on the semiconductor substrate so that the second semiconductor layer is covered with the semiconductor. Forming on the substrate, forming an opening on the support to expose a part of the end of the first semiconductor layer, and etching the first semiconductor layer through the opening. A step of forming a cavity under the second semiconductor layer, and a step of forming an insulating film in the cavity, wherein the support includes a silicon nitride film and a silicon oxide film. It is characterized by being a film of .

  Here, the “semiconductor substrate” is, for example, a bulk silicon (Si) substrate, and the “predetermined region” is a region where an element such as a transistor is formed (that is, an element forming region). The “first semiconductor layer” is, for example, a silicon germanium (SiGe) layer obtained by epitaxial growth, and the “second semiconductor layer” is, for example, an Si layer obtained by epitaxial growth. For etching SiGe, for example, hydrofluoric acid is used.

According to the semiconductor substrate manufacturing method of the first aspect of the present invention, the silicon oxide film and the silicon nitride film are laminated to form the support, whereby the respective defects of the silicon oxide film and the silicon nitride film can be compensated for each other. .
That is, the silicon oxide film is less stressed after film formation than the silicon nitride film, and can be made thicker. Therefore, it is possible to increase the rigidity of the support as compared with the case where the support is composed only of the silicon nitride film, and therefore it is possible to prevent the cavity from being crushed. In addition, the silicon nitride film is less likely to be etched by hydrofluoric acid than the silicon oxide film. Therefore, it is not necessary to form the silicon oxide film excessively thick as compared with the case where the support is composed only of the silicon oxide film, and it is easy to planarize the semiconductor substrate after forming the insulating film.

[Invention 2] A method of manufacturing a semiconductor substrate according to Invention 2 includes a step of forming a first semiconductor layer on a semiconductor substrate, and a second semiconductor layer having a lower etching selectivity than the first semiconductor layer. Forming on the semiconductor layer; forming a hole exposing the semiconductor substrate in the second semiconductor layer and the first semiconductor layer; and supporting the second semiconductor layer on the semiconductor substrate. Forming a body on the semiconductor substrate so that the hole is embedded and the second semiconductor layer is covered, and an opening exposing a part of the end of the first semiconductor layer to the support A step of forming a surface, a step of forming a cavity under the second semiconductor layer by etching the first semiconductor layer through the opening surface, and a step of forming an insulating film in the cavity The support includes silicon nitride. Is characterized in that a film of a laminated structure comprising a film and a silicon oxide film.

Here, the “hole” is formed in the element isolation region, for example.
According to the method for manufacturing a semiconductor substrate of the second aspect, by forming a support by stacking a silicon oxide film and a silicon nitride film, the respective defects of the silicon oxide film and the silicon nitride film can be compensated for each other. .
That is, the silicon oxide film is less stressed after film formation than the silicon nitride film, and can be made thicker. Therefore, it is possible to increase the rigidity of the support as compared with the case where the support is composed only of the silicon nitride film, and therefore it is possible to prevent the cavity from being crushed. In addition, the silicon nitride film is less likely to be etched by hydrofluoric acid than the silicon oxide film. Therefore, it is not necessary to form the silicon oxide film excessively thick as compared with the case where the support is composed only of the silicon oxide film, and it is easy to planarize the semiconductor substrate after forming the insulating film.

[Invention 3] The semiconductor substrate manufacturing method of Invention 3 is the semiconductor substrate manufacturing method of Invention 1 or Invention 2, wherein the first semiconductor layer includes a semiconductor layer A and a semiconductor layer C, and the second semiconductor layer. Comprises a semiconductor layer B and a semiconductor layer D, and the step of forming the first semiconductor layer on the semiconductor substrate and the step of forming the second semiconductor layer on the first semiconductor layer include the semiconductor substrate The semiconductor layer A is formed on the material, the semiconductor B is then formed on the semiconductor layer A, the semiconductor C is further formed on the semiconductor layer B, and then the semiconductor layer C is formed. This is a step of forming the semiconductor D.

Here, “semiconductor layer A” and “semiconductor layer C” are, for example, silicon germanium (SiGe) layers obtained by epitaxial growth, and “semiconductor layer B” and “semiconductor layer C” are, for example, Si layers obtained by epitaxial growth. .
According to the method for manufacturing a semiconductor substrate of the third aspect, for example, a structure in which the semiconductor layer B is an electrode and the semiconductor layer D above the body with the insulating film interposed therebetween can be formed on the semiconductor substrate.

[Invention 4] The semiconductor substrate manufacturing method of Invention 4 is the method of manufacturing a semiconductor substrate according to any one of Inventions 1 to 3, wherein the hole is embedded and the second semiconductor is formed in the step of forming the support. The silicon nitride film is formed on the semiconductor substrate so as to cover the layer, and then the silicon oxide film is formed on the silicon nitride film.

  With such a configuration, the support has a structure in which a silicon oxide film is laminated on a silicon nitride film. Therefore, for example, when an insulating film is formed in the cavity under the second semiconductor layer and then the entire upper surface of the semiconductor substrate is planarized by CMP (chemical mechanical polishing), the silicon nitride constituting the support is formed. The film functions as a stopper for the polishing process. Thus, the upper surface of the second semiconductor layer can be prevented from being directly rubbed with the polishing pad, so that damage caused by CMP can be prevented from being applied to the second semiconductor layer.

[Invention 5] The method for manufacturing a semiconductor substrate according to Invention 5, in the method for manufacturing a semiconductor substrate according to any one of Invention 1 to Invention 3, in the step of forming the support, the hole is embedded, and the second The silicon oxide film is formed on the semiconductor substrate so as to cover the semiconductor layer, and then the silicon nitride film is formed on the silicon oxide film.

  With such a configuration, the support has a structure in which a silicon nitride film is laminated on a silicon oxide film. Therefore, for example, when the first semiconductor layer under the second semiconductor layer is etched with hydrofluoric acid, the upper surface of the silicon oxide film constituting the support can be protected with the silicon nitride film. As a result, it is possible to prevent the support from being thinned and to maintain its rigidity higher.

[Invention 6] The semiconductor substrate manufacturing method of Invention 6 is the method of manufacturing a semiconductor substrate according to any one of Inventions 1 to 5, wherein the step of forming the second semiconductor layer, the step of forming the support, Forming a gap between the peripheral edge of the second semiconductor layer and the semiconductor substrate by etching and removing the peripheral edge of the first semiconductor layer. In the step of performing, the support is formed on the semiconductor substrate so that the gap is embedded.

  With such a configuration, the support body enters between the peripheral portion of the second semiconductor layer and the semiconductor substrate, so that the second semiconductor layer can be supported not only from the side surface but also from the lower side of the peripheral portion. It becomes. Therefore, it is possible to more effectively prevent the hollow portion from being crushed.

[Invention 7] The method for manufacturing a semiconductor substrate according to Invention 7 is the method for manufacturing a semiconductor substrate according to any one of Inventions 1 to 6, wherein the insulating film is formed in the cavity, and then the upper side of the semiconductor substrate. And a step of planarizing the entire surface to remove the support from the second semiconductor layer.
With such a configuration, since the surface of the second semiconductor layer is exposed from under the support, it is possible to form an element such as a transistor in the second semiconductor layer.

[Invention 8] A method for manufacturing a semiconductor device according to Invention 8 includes forming a transistor in the second semiconductor layer after removing the support from the second semiconductor layer by performing the method for manufacturing a semiconductor substrate of Invention 7. The process of performing is included.
With such a configuration, the semiconductor substrate manufacturing method is applied, so that the rigidity of the support can be maintained high, and the semiconductor substrate can be easily flattened. Therefore, an SOI structure transistor can be formed with high reproducibility.
The present invention is extremely suitable when applied to a so-called SBSI technique in which an SOI structure is formed only in a desired region of a bulk semiconductor substrate.

Embodiments of the present invention will be described below with reference to the drawings.
(1) First Embodiment FIGS. 1A, 2A, and 3A are plan views showing a method of manufacturing a semiconductor device according to a first embodiment of the present invention. 1B is a cross-sectional view taken along arrow X1-X1 ′ in FIG. 1A, and FIG. 1C is a cross-sectional view taken along arrow Y1-Y1 ′ in FIG. Further, FIG. 2B is a cross-sectional view taken along arrow X2-X2 ′ in FIG. 2A, and FIG. 2C is a cross-sectional view taken along arrow Y2-Y2 ′ in FIG. 3B is a cross-sectional view taken along the line X3-X3 ′ in FIG. 3A, and FIG. 3C is a cross-sectional view taken along the line Y3-Y3 ′ in FIG. Further, FIGS. 4A to 4C are cross-sectional views showing a method of manufacturing the semiconductor device after FIG. 3B in the X3-X3 ′ cross section.

  As shown in FIGS. 1A to 1C, first, a first SiGe layer 11 is formed on a Si substrate 1 which is a bulk silicon wafer, and a first Si layer 13 is formed thereon. Form. Further, a second SiGe layer 15 is formed on the first Si layer 13, and a second Si layer 17 is formed thereon. These SiGe layers 11 and 15 and Si layers 13 and 17 are formed by epitaxial growth, respectively. The film thickness of the SiGe layers 11 and 15 is, for example, about 5 to 50 [nm], and the film thickness of the Si layers 13 and 17 is, for example, about 10 to 100 [nm].

  Next, a hole h for the support is formed. That is, as shown in FIGS. 1A to 1C, the Si layer 17, the SiGe layer 15, the Si layer 13, and the SiGe layer 11 are sequentially patterned by using the photolithography technique and the etching technique, and the Si substrate 1 Expose part of the surface. This exposed portion is a hole h for the support. The hole h is formed in a part of the outside of a region where an element such as a transistor is formed (that is, an element isolation region). When a part of the Si substrate 1 is exposed, the etching may be stopped on the surface of the Si substrate 1, or the Si substrate 1 may be over-etched to form a recess in the Si substrate 1. .

Next, as shown in FIGS. 2A to 2C, the Si substrate 1 is thermally oxidized at a temperature at which Ge in the SiGe layer does not diffuse, and the surface of the Si substrate 1 and the SiGe layers 11 and 15. A thermal oxide film (SiO ₂ ) 21 is formed on the side surfaces of the Si layers 13 and 17 and the upper surface of the Si layer 17. The thermal oxide film 21 is an underlayer of _{the Si} 3 _{N 4} film 31 to be described later (i.e., a stress relaxation of _{the Si} 3 _{N 4} film 31 and an etching stopper when removing _{the Si} 3 _{N 4} film 31) The film thickness is, for example, about several tens [μm].

Next, the Si ₃ N ₄ film 31 is formed on the entire upper surface of the Si substrate 1 by a method such as CVD. As shown in FIG. 2B, the Si ₃ N ₄ film 31 is provided not only on the support hole h and on the Si layer 17 but also on the side surfaces of the SiGe layers 11 and 15 and the Si layers 13 and 17. It is formed via the thermal oxide film 21. The thickness of the Si ₃ N ₄ film 31 is, for example, about 50 to 200 [nm].
Next, a SiO ₂ film 33 is formed on the Si ₃ N ₄ film 31 by a method such as CVD. As shown in FIG. 2B, this SiO ₂ film 33 is not only on the support hole h and the Si layer 17, but also on the SiGe layers 13, 17 and the Si layer 13, similar to the Si ₃ N ₄ film 31. , 17 are also formed on the side surfaces. The thickness of the SiO ₂ film 33 is, for example, about 50 to 400 [nm].

In this method of manufacturing a semiconductor device, as shown in FIGS. 2B and 2C, the support 30 is constituted by a film having a laminated structure including a Si ₃ N ₄ film 31 and a SiO ₂ film 33. The Si layers 13 and 17 are supported on the Si substrate 1 by such a support 30. The thermal oxide film 21 is formed as a base film for the Si ₃ N ₄ film 31, and the thickness thereof is extremely smaller than that of the Si ₃ N ₄ film 31 or the SiO ₂ film 33. Therefore, it is distinguished from the support 30 (that is, it is not included in the support 30).

Next, as shown in FIGS. 3A to 3C, the support 30 composed of the Si ₃ N ₄ film 31 and the SiO ₂ film 33 using the photolithography technique and the etching technique, and the underlying heat By sequentially patterning the oxide film 21, the Si layer 17, the SiGe layer 15, the Si layer 13, and the SiGe layer 11, a part of the side surfaces of the SiGe layers 11 and 15 and the Si layers 13 and 17 are formed on the support 30. An opening surface exposing a part of the side surface (end portion) is formed.

  By this patterning, the Si layer 17, the SiGe layer 15, the Si layer 13, and the SiGe layer 11 are left only on the Si substrate 1 in a region where an element such as a transistor is formed (that is, an element formation region), The substrate 1 is completely removed. As shown in FIGS. 3A to 3C, the opening surface for exposing part of the side surfaces of the SiGe layers 11 and 15 is formed along the periphery of the element formation region. In the portion of the support 30 where the opening surface is not formed, the support 30 and the side surfaces of the SiGe layers 13 and 17 and the support 30 and the side surfaces of the Si layers 13 and 17 are in contact with each other even after the opening surface is formed. The support 30 continues to support the Si layers 13 and 17 at the contact portion.

  Next, the SiGe layers 11 and 15 are etched and removed by bringing an etching solution such as hydrofluoric acid into contact with the SiGe layers 11 and 15 and the Si layers 13 and 17 through the opening formed in the support 30. . As a result, as shown in FIG. 4A, cavities 41 and 45 are formed between the Si substrate 1 and the Si layer 13 and between the Si layer 13 and the Si layer 17, respectively. In the wet etching using hydrofluoric acid, the etching selectivity between SiGe and Si is, for example, about 100: 1. Therefore, the SiGe layers 11 and 15 (FIG. 3 (B Only) can be selectively removed.

Further, as shown in FIG. 4A, even after the SiGe layer is removed and the cavities 41 and 45 are formed, the side surfaces of the Si layers 13 and 17 are not formed in the portion where the opening surface of the support 30 is not formed. Remains covered with the support 30. Therefore, even after the cavities 41 and 45 are formed, the Si layers 13 and 17 are supported on the Si substrate 1 and continue to maintain this state.
Next, the Si substrate 1 is thermally oxidized. At this time, the oxidizing species such as O ₂ reaches not only the surface of the Si substrate 1 exposed from under the SiO ₂ film 33 but also the cavities 41 and 45 through the opening surface. Therefore, as shown in FIG. 4B, SiO ₂ films 51 and 55 are also formed in the cavity. Hereinafter, the SiO ₂ films 51 and 55 formed in the cavity are referred to as buried oxide films. If the buried oxide films 51 and 55 are not sufficiently filled in the cavity, an SiO ₂ film or the like may be deposited in the cavity by a method such as CVD after thermal oxidation. Further, after forming the buried oxide film in the cavity, high-temperature annealing at 1000 ° C. or higher may be performed. Thereby, the buried oxide film can be reflowed.

Next, an insulating film (not shown) such as SiO ₂ is formed on the entire upper surface of the Si substrate 1 by a method such as CVD. Then, the entire upper surface of the Si substrate 1 is planarized by CMP. Thereby, the SiO ₂ film 33 and the like are removed from above the Si layer 17 and at the same time, the element isolation of the Si layer 17 is performed. In this planarization process using CMP, the Si ₃ N ₄ film 31 under the SiO ₂ film 33 functions as a stopper for the polishing process. Therefore, the upper surface of the Si layer 17 can be prevented from being directly rubbed with the polishing pad, and damage due to CMP can be prevented from being given to the Si layer 17.

Next, the Si ₃ N ₄ film 31 on the Si layer 17 is removed by wet etching using, for example, hot phosphoric acid. In the wet etching using hot phosphoric acid, since SiO ₂ is hardly etched, as shown in FIG. 4C, the upper surface of the Si layer 17 is exposed and the Si layer 17 is element-isolated (that is, SOI structure) can be completed on the bulk Si substrate 1.

  Thereafter, for example, the surface of the Si layer 17 is thermally oxidized to form a gate insulating film (not shown) on the surface of the Si layer 17. Then, a gate electrode (not shown) is formed on the Si layer 17 on which the gate insulating film is formed. Further, using this gate electrode or the like as a mask, impurities such as As, P, and B are ion-implanted into the Si layer 17 to form a source and a drain (not shown), thereby completing an SOI transistor. Since this SOI transistor has a structure in which the Si layer 13 and the Si layer 17 are stacked with the buried insulating film 55 interposed therebetween, the Si layer 13 can be used as an electrode, for example.

Thus, according to the manufacturing method of the semiconductor device according to the first embodiment of the present invention, the support is formed by stacking the Si ₃ N ₄ film 31 and the SiO ₂ film 33, thereby forming the Si ₃ N _4. The respective defects of the film 31 and the SiO ₂ film 33 can be compensated for each other.
That is, the SiO ₂ film 33 is less stressed after film formation than the Si ₃ N ₄ film 31 and can be made thicker. Therefore, it is possible to increase the rigidity of the support 30 as compared with the case where the support 30 is composed of only the Si ₃ N ₄ film 33, and therefore it is possible to prevent the cavities 41 and 45 from being crushed. .

Further, the Si ₃ N ₄ film 31 is less likely to be etched by fluorinated nitric acid than the SiO ₂ film 33. Therefore, the support member 30 as compared with the case contain only the SiO ₂ film 33, it is not necessary to form excessively thick SiO ₂ film 33. Furthermore, since the Si ₃ N ₄ film 31 functions as a stopper during the planarization process by CMP, damage to the Si layer 17 can be prevented from being caused by CMP. Therefore, it is easy to planarize the Si substrate 1 after the buried oxide films 51 and 55 are formed.

  In the first embodiment, the Si substrate 1 corresponds to the “semiconductor substrate” of the present invention, the SiGe layers 11 and 15 correspond to the “first semiconductor layer” of the present invention, and the Si layers 13 and 17 correspond to the present invention. To the “second semiconductor layer”. The SiGe layer 11 corresponds to the “semiconductor layer A” of the present invention, the Si layer 13 corresponds to the “semiconductor layer B” of the present invention, the SiGe layer 15 corresponds to the “semiconductor layer C” of the present invention, The Si layer 17 corresponds to the “semiconductor layer D” of the present invention. Further, the buried oxide films 51 and 55 correspond to the “insulating film” of the present invention.

(2) Second Embodiment FIGS. 5A and 6A are plan views showing a method for manufacturing a semiconductor device according to a second embodiment of the present invention. 5B is a cross-sectional view taken along arrow X4-X4 ′ of FIG. 5A, and FIG. 5C is a cross-sectional view taken along arrow Y4-Y4 ′ of FIG. 5A. Further, FIG. 6B is a cross-sectional view taken along arrow X5-X5 ′ in FIG. 6A, and FIG. 6C is a cross-sectional view taken along arrow Y5-Y5 ′ in FIG. The second embodiment is the same as the first embodiment up to the step of forming the support hole h in a part of the outside of the element isolation region.

  In this second embodiment, as shown in FIGS. 5A to 5C, after the hole h for the support is formed, the SiGe layers 11 and 15 are lightly etched with hydrofluoric acid or the like, and the peripheral portion thereof. Remove. As a result, gaps 60 are formed between the periphery of the Si layer 13 and the Si substrate 1 and between the periphery of the Si layer 13 and the periphery of the Si layer 17. As shown in FIG. 5A, when the depth of the gap 60 is L, L is, for example, about 0.01 to 0.3 [μm].

Next, as shown in FIGS. 6A to 6C, the Si substrate 1 is thermally oxidized, and the surface of the Si substrate 1, the side surfaces of the SiGe layers 11 and 15 and the Si layers 13 and 17, and the Si layer A thermal oxide film 21 is formed on the upper surface of 17. Then, the Si ₃ N ₄ film 31 is formed over the entire upper surface of the Si substrate 1 by a method such as CVD so that the gap 60 is embedded. The subsequent steps are the same as those in the first embodiment.

With such a configuration, the Si ₃ N ₄ film 31 enters between the periphery of the Si layer 13 and the Si substrate 1 and between the periphery of the Si layer 13 and the periphery of the Si layer 17. The Si layers 13 and 17 can be supported not only from the side surfaces but also from the lower side of the peripheral portion. Therefore, it is possible to more effectively prevent the hollow portion from being crushed.

(3) Third Embodiment FIG. 7A is a plan view showing a method for manufacturing a semiconductor device according to a third embodiment of the present invention. 7B is a cross-sectional view taken along the line X4-X4 ′ in FIG. 7A, and FIG. 7C is a cross-sectional view taken along the line Y4-Y4 ′ in FIG. 7A.

In the first and second embodiments described above, the case where two SiGe layers and two Si layers are alternately stacked has been described. However, one SiGe layer and one Si layer may be provided. For example, as shown in FIGS. 7A to 7C, a SiGe layer 15 ′ and a Si layer 17 ′ are stacked on a Si substrate 1, and a Si ₃ N ₄ film 31 and a SiO 2 are formed thereon as a support 30. _Two films 33 are stacked. Even with such a configuration, since the respective defects of the Si ₃ N ₄ film 31 and the SiO ₂ film 33 can be compensated for each other, the rigidity of the support 30 can be kept high. In addition, the Si substrate 1 can be easily flattened.

In the third embodiment, the SiGe layer 15 ′ corresponds to the “first semiconductor layer” of the present invention, and the Si layer 17 ′ corresponds to the “second semiconductor layer” of the present invention.
In the embodiment of the present invention, the case where the lower layer of the support 30 is configured by the Si ₃ N ₄ film 31 and the upper layer of the support 30 is configured by the SiO ₂ film 33 has been described. However, the lower layer of the support 30 of the present invention may be the SiO ₂ film 33 and the upper layer may be the Si ₃ N ₄ film 31.

With such a configuration, for example, in FIGS. 3A to 3C, when the SiGe layers 11 and 15 are etched with hydrofluoric acid, the upper surface of the SiO ₂ film 33 constituting the support 30 is made of Si ₃ N. It can be protected by the _four films 31. Therefore, it is possible to prevent the support 30 from being thinned and to maintain the rigidity higher.
In the embodiment of the present invention, the case where the support 30 is composed of two layers of the Si ₃ N ₄ film 31 and the SiO ₂ film 33 has been described. However, the support 30 of the present invention is limited to two layers. is not. _Three or more layers including the Si ₃ N ₄ film 31 and the SiO ₂ film 33 may be used. For example, the lower layer of the support 30 may be the Si ₃ N ₄ film 31, the intermediate layer may be the SiO ₂ film 33, and the upper layer may be the Si ₃ N ₄ film 31. Alternatively, the lower layer of the support 30 may be the SiO ₂ film 33, the intermediate layer may be the Si ₃ N ₄ film 31, and the upper layer may be the SiO ₂ film 33.

Even with such a configuration, the respective defects of the SiO ₂ film 33 and the Si ₃ N ₄ film 31 can be compensated for each other, so that the rigidity of the support 30 can be maintained high, and the Si substrate 1 can be flattened. Easy.
Furthermore, in the embodiment of the present invention, the case where the SiGe layer 11, the Si layer 13, the SiGe layer 15, and the Si layer 17 are sequentially epitaxially grown on the entire surface of the Si substrate 1 has been described. However, these layers may be formed not only on the entire surface of the Si substrate 1, but only in the element formation region and not in the element isolation region. For example, the SiGe layer and the Si layer may be alternately formed by selective epitaxial growth with the surface of the Si substrate 1 in the element isolation region covered with the SiO ₂ film.

Even with such a configuration, the support 30 can be formed on the Si substrate 1 so as to cover the Si layer 17, and the opening that exposes the side surfaces of the SiGe layers 11, 15, etc. on the support 30. A surface can be formed. Therefore, the cavity portions 41 and 45 (see FIG. 4A) can be formed in the element formation region.
In the embodiment of the present invention, the case where the material of the “semiconductor substrate” is Si, the material of the “first semiconductor layer” is SiGe, and the material of the “second semiconductor layer” is Si has been described. However, these materials are not limited to the above. For example, Si, Ge, SiGe, SiC, SiSn, PbS, GaAs, InP, GaP, GaN, ZnSe, or the like can be used as the material of the “semiconductor substrate”. Further, as the material of the “first semiconductor layer”, a material having a higher etching selection ratio than the Si substrate 1 and the second semiconductor layer can be used. For example, a combination selected from Si, Ge, SiGe, SiC, SiSn, PbS, GaAs, InP, GaP, GaN, ZnSe, or the like is used as the material of the “first semiconductor layer” and the “second semiconductor layer”. be able to.

FIG. 3 is a view showing the method for manufacturing a semiconductor device according to the first embodiment (No. 1). FIG. 6 is a diagram (No. 2) illustrating the method for manufacturing the semiconductor device according to the first embodiment. 3A and 3B are diagrams illustrating the method for manufacturing a semiconductor device according to the first embodiment (No. 3). 4A and 4B are diagrams illustrating the method for fabricating a semiconductor device according to the first embodiment (No. 4). The figure which shows the manufacturing method of the semiconductor device which concerns on 2nd Embodiment (the 1). FIG. 6 is a view (No. 2) showing the method for manufacturing a semiconductor device according to the second embodiment. The figure which shows the manufacturing method of the semiconductor device which concerns on 3rd Embodiment (the 1).

Explanation of symbols

1 Si substrate, 11 (first) SiGe layer, 13 (first) Si layer, 15 (second) SiGe layer, 15 'SiGe layer, 17 (second) Si layer, 17' Si layer, 21 thermal oxide film (SiO ₂ ), 30 support, 31 Si ₃ N ₄ film, 33 SiO 2 film, 41, 45 cavity, 51, 55 buried oxide film (SiO ₂ ), 60 gap, h (for support )hole

Claims (10)

Forming a silicon germanium layer on a silicon substrate,
Forming a silicon layer on the silicon germanium layer,
Forming a hole exposing the silicon substrate in the silicon layer and the silicon germanium layer;
A step of forming the silicon layer support supporting on the silicon substrate, as the hole is filled and the silicon layer is covered on the silicon substrate,
Forming an opening surface exposing a part of an end of the silicon germanium layer on the support;
Etching the silicon germanium layer with hydrofluoric acid through the opening, thereby forming a cavity under the silicon layer;
Forming an insulating film in the cavity,
The method of manufacturing a semiconductor substrate, wherein the support is a film having a laminated structure including a silicon nitride film and a silicon oxide film. The silicon germanium layer includes a silicon germanium layer A and a silicon germanium layer C, and the silicon layer includes a silicon layer B and a silicon layer D.
Forming the silicon germanium layer on the silicon substrate, and forming the silicon layer on the silicon germanium layer,
Forming the silicon germanium layer A on the silicon substrate, then forming the silicon layer B on the silicon germanium layer A, and further forming the silicon germanium layer C on the silicon layer B; 2. The method of manufacturing a semiconductor substrate according to claim 1, wherein the silicon layer D is formed on the silicon germanium layer C. 3 . In the step of forming the support,
Forming the silicon nitride film on the silicon substrate such that the hole is embedded and the silicon layer is covered;
The method of manufacturing a semiconductor substrate according to claim 1 , wherein the silicon oxide film is formed on the silicon nitride film . In the step of forming the support,
The hole is buried, and as the silicon layer is covered to form the silicon oxide film on the silicon substrate, then
The method of manufacturing a semiconductor substrate according to claim 1 or claim 2, characterized in that forming the silicon nitride film on the silicon oxide film. Between the step of forming the silicon layer and the step of forming the support,
Forming a gap between the peripheral edge of the silicon layer and the silicon substrate by etching away the peripheral edge of the silicon germanium layer;
In the step of forming the support,
The method of manufacturing a semiconductor substrate according to any one of claims 1 to 4, characterized in that to form the support on the silicon substrate as the gap is filled. Forming a silicon germanium layer on a predetermined area of the silicon substrate;
Forming a silicon layer on the silicon germanium layer;
Forming a support for supporting the silicon layer on the silicon substrate on the silicon substrate so that the silicon layer is covered;
Forming an opening surface exposing a part of an end of the silicon germanium layer on the support;
Etching the silicon germanium layer with hydrofluoric acid through the opening, thereby forming a cavity under the silicon layer;
Forming an insulating film in the cavity,
The support is a film having a laminated structure including a silicon nitride film and a silicon oxide film,
The silicon germanium layer includes a silicon germanium layer A and a silicon germanium layer C, and the silicon layer includes a silicon layer B and a silicon layer D.
Forming the silicon germanium layer on the silicon substrate, and forming the silicon layer on the silicon germanium layer,
Forming the silicon germanium layer A on the silicon substrate, then forming the silicon layer B on the silicon germanium layer A, and further forming the silicon germanium layer C on the silicon layer B; Then, the method of manufacturing a semiconductor substrate, which is a step of forming the silicon layer D on the silicon germanium layer C. Forming a silicon germanium layer on a predetermined area of the silicon substrate;
Forming a silicon layer on the silicon germanium layer;
Forming a support for supporting the silicon layer on the silicon substrate on the silicon substrate so that the silicon layer is covered;
Forming an opening surface exposing a part of an end of the silicon germanium layer on the support;
Etching the silicon germanium layer with hydrofluoric acid through the opening, thereby forming a cavity under the silicon layer;
Forming an insulating film in the cavity,
The support is a film having a laminated structure including a silicon nitride film and a silicon oxide film,
In the step of forming the support,
Forming the silicon nitride film on the silicon substrate such that the silicon layer is covered;
A method of manufacturing a semiconductor substrate , comprising forming the silicon oxide film on the silicon nitride film . Forming a silicon germanium layer on a predetermined area of the silicon substrate;
Forming a silicon layer on the silicon germanium layer;
Forming a support for supporting the silicon layer on the silicon substrate on the silicon substrate so that the silicon layer is covered;
Forming an opening surface exposing a part of an end of the silicon germanium layer on the support;
Etching the silicon germanium layer with hydrofluoric acid through the opening, thereby forming a cavity under the silicon layer;
Forming an insulating film in the cavity,
The support is a film having a laminated structure including a silicon nitride film and a silicon oxide film,
Between the step of forming the silicon layer and the step of forming the support,
A step of forming a gap between the peripheral portion of the silicon layer and the silicon base material by etching and removing the peripheral portion of the silicon germanium layer;
In the step of forming the support,
A method of manufacturing a semiconductor substrate, wherein the support is formed on the silicon base material so that the gap is embedded . After forming the insulating film in the cavity,
The semiconductor substrate according to any one of claims 1 to 8, further comprising a step of planarizing the entire upper surface of the silicon base material to remove the support from the silicon layer. Manufacturing method. After performing the method for manufacturing a semiconductor substrate according to claim 9, removing the support from the silicon layer,
Forming a transistor in the silicon layer. A method for manufacturing a semiconductor device, comprising:

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