JP4867162B2 - 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 is particularly suitable for application to a field effect transistor formed on an SOI (Silicon On Insulator) substrate.

  Field effect transistors formed on an SOI substrate are attracting attention because of their ease of element isolation, latch-up freeness, and low source / drain junction capacitance. In particular, since a fully depleted SOI transistor can operate at low power consumption and at high speed and can be easily driven at a low voltage, research for operating the SOI transistor in a fully depleted mode has been actively conducted. Here, as the SOI substrate, for example, as disclosed in Patent Documents 1 and 2, a SIMOX (Separation by Implanted Oxgen) substrate or a bonded substrate is used.

Non-Patent Document 1 discloses a method by which an SOI transistor can be formed at a low cost by forming an SOI layer over a bulk substrate. In the method disclosed in Non-Patent Document 1, a Si / SiGe layer is formed on a Si substrate, and only the SiGe layer is selectively removed using a difference in selectivity between Si and SiGe. A cavity is formed between the Si substrate and the Si layer. Then, by performing thermal oxidation of Si exposed in the cavity, an SiO ₂ layer is embedded between the Si substrate and the Si layer, and a BOX layer is formed between the Si substrate and the Si layer.
JP 2002-299951 A Japanese Patent Application Laid-Open No. 2000-124092 T.A. Sakai et al. , Second International GiGe Technology and Device Meeting, Meeting Abstract, pp. 230-231, May (2004)

  However, in order to manufacture a SIMOX substrate, it is necessary to ion-implant high concentration oxygen into a silicon wafer. In order to manufacture a bonded substrate, it is necessary to polish the surface of the silicon wafer after bonding two silicon wafers. For this reason, the SOI transistor has a problem that the cost is increased as compared with a field effect transistor formed in a bulk semiconductor.

Also, in ion implantation and polishing, the variation in the thickness of the SOI layer is large, and it is difficult to stabilize the characteristics of the field effect transistor when the SOI layer is thinned in order to produce a fully depleted SOI transistor. There was a problem.
On the other hand, in the method disclosed in Non-Patent Document 1, since only the SiGe layer is selectively removed using the selection ratio between Si and SiGe, the etching distance of the SiGe layer is limited, and the width of the SOI layer is reduced. There was a problem that was restricted. Here, if the Ge concentration in the SiGe layer is increased, the selectivity ratio between Si and SiGe can be increased. However, if the Ge concentration in the SiGe layer is increased, it is difficult to increase the thickness of the SiGe layer while maintaining the crystal quality. As a result, the BOX layer becomes thinner, the crystal quality of the Si layer formed on the SiGe layer also deteriorates, and the characteristics of the SOI transistor deteriorate.

  Accordingly, an object of the present invention is to provide a method for manufacturing a semiconductor substrate and a semiconductor device capable of forming a semiconductor layer on an insulator at a low cost while relaxing restrictions on the width of the semiconductor layer that can be formed on the insulating film. It is to provide a manufacturing method.

  In order to solve the above-described problem, according to a method for manufacturing a semiconductor substrate according to one embodiment of the present invention, a step of forming a first semiconductor layer over a semiconductor substrate and an etching rate lower than that of the first semiconductor layer are provided. Forming a second semiconductor layer on the first semiconductor layer; and irradiating the first semiconductor layer with the laser through the second semiconductor layer to dissociate the bonds of the elements constituting the first semiconductor layer. A step of forming an exposed portion exposing a part of the first semiconductor layer from the second semiconductor layer, a material having an etching rate smaller than that of the first semiconductor layer, and the second semiconductor layer Forming a support for supporting the first semiconductor layer on the semiconductor substrate, and selectively etching the first semiconductor layer irradiated with the laser through the exposed portion, thereby removing the first semiconductor layer. Forming the cave portion between the semiconductor substrate and the second semiconductor layer, and thermally oxidizing the semiconductor substrate and the second semiconductor layer in the cavity portion through the exposed portion; And a step of forming an insulating film embedded in the portion.

  Thereby, after forming the second semiconductor layer on the first semiconductor layer, it becomes possible to cut the bonds of the constituent elements of the first semiconductor layer, and epitaxially grow the second semiconductor layer on the first semiconductor layer. While making it possible, the etching rate between the second semiconductor layer and the first semiconductor layer can be increased. For this reason, the first semiconductor layer can be selectively etched while suppressing the etching of the second semiconductor layer, and the restriction on the etching area of the first semiconductor layer under the second semiconductor layer can be relaxed. Can do. As a result, the width of the second semiconductor layer that can be formed on the insulating film can be expanded while suppressing the deterioration of the crystal quality of the second semiconductor layer, and the second semiconductor layer having a good crystal quality can be formed on the insulating film. It can be formed at low cost.

  In addition, by making the etching rate of the second semiconductor layer smaller than that of the first semiconductor layer, the first semiconductor layer can be removed while leaving the second semiconductor layer, and a cavity is formed under the second semiconductor layer. It becomes possible to form. Furthermore, by providing a support for supporting the second semiconductor layer on the semiconductor substrate, it is possible to prevent the second semiconductor layer from sinking even when a cavity is formed below the second semiconductor layer. It becomes. For this reason, it becomes possible to arrange | position a 2nd semiconductor layer on an insulating film, reducing generation | occurrence | production of the defect of a 2nd semiconductor layer, and without impairing the quality of a 2nd semiconductor layer, a 2nd semiconductor layer and a semiconductor substrate It is possible to achieve insulation between them.

  In addition, according to the method of manufacturing a semiconductor substrate according to one aspect of the present invention, the step of forming the first semiconductor layer on the semiconductor substrate, and the second semiconductor layer having an etching rate smaller than that of the first semiconductor layer are the first semiconductor layer. A step of forming on one semiconductor layer, a step of dissociating bonds of elements constituting the first semiconductor layer by irradiating the first semiconductor layer through the second semiconductor layer with a laser, and the first Forming a first groove penetrating the semiconductor layer and the second semiconductor layer to expose the semiconductor substrate; and being formed on sidewalls of the first semiconductor layer and the second semiconductor layer; Forming a support having a low etching rate in the first groove, and forming a second groove that exposes at least a portion of the first semiconductor layer formed on the sidewall of the support from the second semiconductor layer; And a process of The first semiconductor layer irradiated with the laser is selectively etched through the second groove so that the cavity from which the first semiconductor layer is removed is interposed between the semiconductor substrate and the second semiconductor layer. Forming the insulating film buried in the cavity by thermally oxidizing the semiconductor substrate and the second semiconductor layer through the first groove and the second groove. It is characterized by providing.

  Thereby, after forming the second semiconductor layer on the first semiconductor layer, it becomes possible to break the bonds of the constituent elements of the first semiconductor layer. Therefore, the etching rate between the second semiconductor layer and the first semiconductor layer can be increased without changing the constituent components of the first semiconductor layer and the second semiconductor layer, and the crystal quality of the second semiconductor layer can be increased. The width of the second semiconductor layer that can be formed on the insulating film can be increased while suppressing the deterioration of the film.

  In addition, the second semiconductor layer can be supported on the semiconductor substrate via the support formed in the first groove, and the first semiconductor below the second semiconductor layer via the second groove. An etching gas or an etching solution can be brought into contact with the layer. For this reason, it becomes possible to remove the first semiconductor layer between the second semiconductor layer and the semiconductor substrate while making it possible to stably support the second semiconductor layer on the semiconductor substrate. Insulation between the second semiconductor layer and the semiconductor substrate can be achieved without impairing the quality of the semiconductor layer, and an insulating film is formed on the back surface side of the second semiconductor layer by thermal oxidation of the second semiconductor layer. Thus, the film thickness of the second semiconductor layer can be controlled with high accuracy.

According to the method for manufacturing a semiconductor substrate of one embodiment of the present invention, the wavelength of the laser is not less than the binding energy of the element constituting the first semiconductor layer and not more than the binding energy of the element constituting the second semiconductor layer. It is characterized by being.
Thereby, the bond of the constituent elements of the first semiconductor layer can be cut while suppressing the bond of the constituent elements of the second semiconductor layer from being cut. Therefore, even when the second semiconductor layer is formed on the first semiconductor layer, it becomes possible to increase the etching rate of the first semiconductor layer while suppressing the deterioration of the crystal quality of the second semiconductor layer, and the insulating film The second semiconductor layer with good crystal quality can be formed on the insulating film at low cost while increasing the width of the second semiconductor layer that can be formed thereon.

  According to the method for manufacturing a semiconductor substrate of one embodiment of the present invention, the laser irradiation step is smaller than the binding energy of the elements constituting the first semiconductor layer, and the first semiconductor layer is the second semiconductor layer. Irradiating a first laser having a wavelength with a larger extinction coefficient than the semiconductor layer; and irradiating the first semiconductor layer in an excited state by the irradiation of the first laser with the second laser. And a step of transitioning an electronic state of the layer to an antibonded excited state of a constituent element of the first semiconductor layer.

  Accordingly, the first semiconductor layer can be selectively brought into an excited state by irradiation with the first laser, and the energy of the second laser necessary for transitioning the first semiconductor layer to the anti-coupled state is reduced. be able to. For this reason, even when the binding energy of the constituent element of the first semiconductor layer and the binding energy of the constituent element of the second semiconductor layer are close, while suppressing the bond of the constituent element of the second semiconductor layer, Bonds of constituent elements of the first semiconductor layer can be cut. As a result, even when the second semiconductor layer is formed on the first semiconductor layer, it is possible to increase the etching rate of the first semiconductor layer while suppressing the deterioration of the crystal quality of the second semiconductor layer, and the insulating film The second semiconductor layer with good crystal quality can be formed on the insulating film at low cost while increasing the width of the second semiconductor layer that can be formed thereon.

  Further, according to the method for manufacturing a semiconductor substrate according to one aspect of the present invention, the step of irradiating the laser irradiates a laser having a wavelength that matches a vibration frequency that is unique only between the elements constituting the first semiconductor layer. However, the first semiconductor layer is excited to a high vibration excited state by multiphoton absorption, thereby transitioning to an excited state higher than the binding energy of the constituent elements of the first semiconductor layer.

  Accordingly, the first semiconductor layer can be shifted to an excited state higher than the binding energy of the constituent elements of the first semiconductor layer while selectively shifting the first semiconductor layer to the vibrationally excited state, and the first semiconductor layer can be brought into the anti-bonded state. Laser energy required for the transition can be reduced. For this reason, even when the binding energy of the constituent element of the first semiconductor layer and the binding energy of the constituent element of the second semiconductor layer are close, while suppressing the bond of the constituent element of the second semiconductor layer, Bonds of constituent elements of the first semiconductor layer can be cut. As a result, even when the second semiconductor layer is formed on the first semiconductor layer, it is possible to increase the etching rate of the first semiconductor layer while suppressing the deterioration of the crystal quality of the second semiconductor layer, and the insulating film The second semiconductor layer with good crystal quality can be formed on the insulating film at low cost while increasing the width of the second semiconductor layer that can be formed thereon.

  According to the method for manufacturing a semiconductor substrate according to one aspect of the present invention, the step of irradiating the laser beam includes a first laser having a wavelength that matches a vibration frequency unique only between elements constituting the first semiconductor layer. While irradiating, the step of exciting the first semiconductor layer to a high vibration excitation state by multiphoton absorption, and the second laser is irradiated to the first semiconductor layer in a high vibration excitation state by irradiation of the first laser And a step of transitioning to an excited state higher than the binding energy of the constituent elements of the first semiconductor layer.

  This makes it possible to selectively shift the first semiconductor layer to the vibrationally excited state by irradiation with the first laser, and to reduce the energy of the second laser necessary for transitioning the first semiconductor layer to the anti-coupled state. Can be small. For this reason, even when the binding energy of the constituent element of the first semiconductor layer and the binding energy of the constituent element of the second semiconductor layer are close, while suppressing the bond of the constituent element of the second semiconductor layer, Bonds of constituent elements of the first semiconductor layer can be cut. As a result, even when the second semiconductor layer is formed on the first semiconductor layer, it is possible to increase the etching rate of the first semiconductor layer while suppressing the deterioration of the crystal quality of the second semiconductor layer, and the insulating film The second semiconductor layer with good crystal quality can be formed on the insulating film at low cost while increasing the width of the second semiconductor layer that can be formed thereon.

  According to the method for manufacturing a semiconductor substrate of one embodiment of the present invention, the step of forming the first semiconductor layer over the semiconductor substrate, and irradiating the first semiconductor layer with laser light allows the first semiconductor layer to be formed. Dissociating bonds of constituent elements, forming a second semiconductor layer having a lower etching rate than the first semiconductor layer on the laser-irradiated first semiconductor layer, and one of the first semiconductor layers Forming an exposed portion that exposes the portion from the second semiconductor layer; and a support that is made of a material having an etching rate smaller than that of the first semiconductor layer and supports the second semiconductor layer on the semiconductor substrate. Forming a cavity between the semiconductor substrate and the second semiconductor layer by selectively etching the first semiconductor layer through the exposed portion, and removing the first semiconductor layer. And forming an insulating film embedded in the cavity by thermally oxidizing the semiconductor substrate and the second semiconductor layer in the cavity through the exposed portion. And

  Accordingly, before the second semiconductor layer is epitaxially grown on the first semiconductor layer, the first semiconductor layer can be irradiated with laser, and the bonds of the constituent elements of the first semiconductor layer are cut, and then the first semiconductor layer is cut. The second semiconductor layer can be epitaxially grown on the layer. Therefore, the etching rate between the second semiconductor layer and the first semiconductor layer can be increased without breaking the bonding of the constituent elements of the second semiconductor layer, and the first semiconductor layer below the second semiconductor layer. The restriction of the etching area can be relaxed. As a result, the width of the second semiconductor layer that can be formed on the insulating film can be expanded while suppressing the deterioration of the crystal quality of the second semiconductor layer, and the second semiconductor layer having a good crystal quality can be formed on the insulating film. It can be formed at low cost.

  According to the method for manufacturing a semiconductor substrate of one embodiment of the present invention, the step of forming the first semiconductor layer over the semiconductor substrate, and irradiating the first semiconductor layer with laser light allows the first semiconductor layer to be formed. Dissociating bonds of constituent elements, forming a second semiconductor layer having an etching rate lower than that of the first semiconductor layer irradiated with the laser on the first semiconductor layer, and And irradiating the first semiconductor layer with a laser to dissociate the bonds of elements constituting the first semiconductor layer, and exposing the semiconductor substrate through the first semiconductor layer and the second semiconductor layer. Forming a first groove to be formed, and forming a support formed in sidewalls of the first semiconductor layer and the second semiconductor layer and having an etching rate smaller than that of the first semiconductor layer in the first groove. Forming a second groove for exposing at least a part of the first semiconductor layer having the support formed on the side wall from the second semiconductor layer; and selecting the first semiconductor layer through the second groove Etching to form a cavity from which the first semiconductor layer has been removed between the semiconductor substrate and the second semiconductor layer, through the first groove and the second groove, Forming an insulating film embedded in the cavity by thermally oxidizing the semiconductor substrate and the second semiconductor layer.

  Thereby, before the second semiconductor layer is epitaxially grown on the first semiconductor layer, the first semiconductor layer can be irradiated with laser, and the second semiconductor layer can be cut without breaking the bonds of the constituent elements of the second semiconductor layer. The etching rate between the layer and the first semiconductor layer can be increased. Therefore, the width of the second semiconductor layer that can be formed on the insulating film can be increased while suppressing the deterioration of the crystal quality of the second semiconductor layer, and the second semiconductor layer having a good crystal quality can be formed on the insulating film. It can be formed at low cost.

The semiconductor substrate manufacturing method according to one aspect of the present invention is characterized in that the semiconductor substrate and the second semiconductor layer are single crystal Si, and the first semiconductor layer is single crystal SiGe.
As a result, it is possible to increase the etching rate of the first semiconductor layer compared to the semiconductor substrate and the second semiconductor layer while allowing lattice matching between the semiconductor substrate, the first semiconductor layer, and the second semiconductor layer. . For this reason, it becomes possible to form the second semiconductor layer with good crystal quality on the first semiconductor layer, and insulation between the second semiconductor layer and the semiconductor substrate is achieved without impairing the quality of the second semiconductor layer. It becomes possible.

According to the method for manufacturing a semiconductor substrate of one embodiment of the present invention, the first semiconductor layer is selectively etched by a hydrofluoric acid (hydrofluoric acid, nitric acid, water mixture) treatment of the first semiconductor layer. It is characterized by doing.
As a result, the etching rate of the first semiconductor layer can be made larger than that of the semiconductor substrate and the second semiconductor layer, and the first semiconductor layer can be removed by wet etching. It is possible to achieve insulation between the second semiconductor layer and the semiconductor substrate without impairing quality.

  According to the method for manufacturing a semiconductor device of one embodiment of the present invention, the step of forming the first semiconductor layer over the semiconductor substrate, and the second semiconductor layer having an etching rate smaller than that of the first semiconductor layer are provided in the first semiconductor layer. A step of forming on one semiconductor layer, a step of dissociating bonds of elements constituting the first semiconductor layer by irradiating the first semiconductor layer through the second semiconductor layer with a laser, and the first Forming an exposed portion for exposing a part of the semiconductor layer from the second semiconductor layer; and a material having an etching rate smaller than that of the first semiconductor layer, and supporting the second semiconductor layer on the semiconductor substrate. A step of forming a supporting body, and selectively etching the laser-irradiated first semiconductor layer through the exposed portion, thereby removing the cavity from which the first semiconductor layer has been removed from the semiconductor substrate. An insulating film embedded in the cavity portion by performing thermal oxidation of the semiconductor substrate and the second semiconductor layer in the cavity portion through the exposed portion and the step of forming between the second semiconductor layer and the exposed portion; Forming a gate electrode on the second semiconductor layer via a gate insulating film, and forming source / drain layers respectively disposed on both sides of the gate electrode in the second semiconductor layer And a process.

  This makes it possible to remove the first semiconductor layer between the second semiconductor layer and the semiconductor substrate over a wide range while allowing the second semiconductor layer to be stably supported on the semiconductor substrate. At the same time, an insulating film can be formed on the back surface side of the second semiconductor layer by thermal oxidation of the second semiconductor layer. For this reason, by using a bulk substrate, it is possible to form the second semiconductor layer on the insulating film, and it is possible to increase the width of the second semiconductor layer that can be formed on the insulating film. It is possible to form a high-quality SOI transistor while suppressing the increase.

  According to the method for manufacturing a semiconductor device of one embodiment of the present invention, a step of forming a first semiconductor layer over a semiconductor substrate, and laser irradiation of the first semiconductor layer, the first semiconductor layer is formed. Dissociating bonds of constituent elements, forming a second semiconductor layer having a lower etching rate than the first semiconductor layer on the laser-irradiated first semiconductor layer, and one of the first semiconductor layers Forming an exposed portion that exposes the portion from the second semiconductor layer; and a support that is made of a material having an etching rate smaller than that of the first semiconductor layer and supports the second semiconductor layer on the semiconductor substrate. Forming a cavity between the semiconductor substrate and the second semiconductor layer by selectively etching the first semiconductor layer through the exposed portion, and removing the first semiconductor layer. A step of thermally oxidizing the semiconductor substrate and the second semiconductor layer in the cavity through the exposed portion, and forming an insulating film embedded in the cavity, and the second semiconductor Forming a gate electrode on the layer via a gate insulating film; and forming a source / drain layer respectively disposed on both sides of the gate electrode in the second semiconductor layer.

  This makes it possible to remove the first semiconductor layer between the second semiconductor layer and the semiconductor substrate over a wide range while allowing the second semiconductor layer to be stably supported on the semiconductor substrate. At the same time, an insulating film can be formed on the back surface side of the second semiconductor layer by thermal oxidation of the second semiconductor layer. For this reason, by using a bulk substrate, it is possible to form the second semiconductor layer on the insulating film, and it is possible to increase the width of the second semiconductor layer that can be formed on the insulating film. It is possible to form a high-quality SOI transistor while suppressing the increase.

Hereinafter, a semiconductor device manufacturing method according to an embodiment of the present invention will be described with reference to the drawings.
1A and 2A are perspective views showing a method of manufacturing a semiconductor device according to an embodiment of the present invention, and FIGS. 1B and 2B are views of FIG. Sectional views cut along line A11-A11 ′ and line A12-A12 ′ in FIG. 2A, respectively, FIG. 1C and FIG. 2C are B11-B11 ′ in FIG. It is sectional drawing cut | disconnected by the B12-B12 'line | wire of a), respectively. 7A to 14A are perspective views showing a method for manufacturing a semiconductor device according to an embodiment of the present invention, and FIGS. 7B to 14B are FIGS. ) To FIG. 14A are cross-sectional views cut along lines A1-A1 ′ to A8-A8 ′, respectively, and FIG. 7C to FIG. 14C are those of FIG. 7A to FIG. It is sectional drawing cut | disconnected by the B1-B1'-B8-B8 'line | wire, respectively.

  In FIG. 1, a first semiconductor layer 2 is formed on a semiconductor substrate 1 by epitaxial growth, and a second semiconductor layer 3 is formed on the first semiconductor layer 2 by epitaxial growth. The first semiconductor layer 2 can be made of a material having an etching rate larger than that of the semiconductor substrate 1 and the second semiconductor layer 3, and the material of the semiconductor substrate 1, the first semiconductor layer 2 and the second semiconductor layer 3 can be used. For example, a combination selected from Si, Ge, SiGe, SiC, SiSn, PbS, GaAs, InP, GaP, GaN, ZnSe, and the like can be used. In particular, when the semiconductor substrate 1 is Si, it is preferable to use SiGe as the first semiconductor layer 2 and Si as the second semiconductor layer 3. Accordingly, it is possible to secure a selection ratio between the first semiconductor layer 2 and the second semiconductor layer 3 while enabling lattice matching between the first semiconductor layer 2 and the second semiconductor layer 3. it can. The first semiconductor layer 2 may be a single crystal semiconductor layer, another crystal semiconductor layer, an amorphous semiconductor layer, or a porous semiconductor layer.

  Next, as shown in FIG. 2, by irradiating the first semiconductor layer 2 with the laser light R through the second semiconductor layer 3, the bonds of the elements constituting the first semiconductor layer 2 are dissociated, and the first semiconductor layer 2 is dissociated. A dissociation point K is selectively formed in the semiconductor layer 2. Here, the wavelength of the laser beam R is preferably not less than the binding energy of the elements constituting the first semiconductor layer 2 and not more than the binding energy of the elements constituting the second semiconductor layer 3. For example, as disclosed in “Michinori Ohki et al., Chemistry Dictionary 6th edition (2001)”, the bond energy between Si and Si is 450.6 kJ / mol (4.67 eV), between Ge and Ge. The binding energy is 167.2 kJ / mol (1.73 eV). The bond energy between Si and Ge varies depending on the composition ratio of SiGe and is between these energies. Therefore, when the semiconductor substrate 1 and the second semiconductor layer 3 are Si and the first semiconductor layer 2 is SiGe, visible or ultraviolet laser irradiation having a wavelength corresponding to the Ge composition ratio can be performed.

Thereby, it is possible to cut the bond between the constituent elements of the first semiconductor layer 2 while suppressing the bond between the constituent elements of the second semiconductor layer 3 from being cut. For this reason, even when the second semiconductor layer 3 is formed on the first semiconductor layer 2, it is possible to increase the etching rate of the first semiconductor layer 2 while suppressing deterioration of the crystal quality of the second semiconductor layer 3. It becomes.
When the binding energy of the constituent elements of the first semiconductor layer 2 and the binding energy of the constituent elements of the second semiconductor layer 3 are close, such as a combination of Si and SiGe, the first semiconductor layer 2 is obtained by two-stage excitation. The bonds of the constituent elements may be selectively dissociated.

FIG. 3 is a diagram illustrating a two-stage excitation method according to an embodiment of the present invention.
In FIG. 3, the first semiconductor layer 2 is irradiated with laser light having a wavelength λ ₁ that is smaller than the binding energy of the elements constituting the first semiconductor layer 2 and has a larger extinction coefficient than the second semiconductor layer 3. Then, by irradiating the first semiconductor layer 2 in the electronically excited state laser having a wavelength lambda ₂ by the irradiation of the wavelength lambda ₁ of the laser beam, the electron state of the first semiconductor layer 2 of the first semiconductor layer 2 constituting elements It is possible to transition to the antibonded excited state.

FIG. 4 is a view showing visible ultraviolet absorption spectra of Si and SiGe according to one embodiment of the present invention.
In FIG. 4, when the visible ultraviolet absorption spectrum of Si and SiGe is calculated from the dielectric constant function described in “Journal of Applied Physics, Volume 65, pp 2827-2832 (1989)”, 500-700 nm (2.48- It can be seen that there is an intrinsic absorption peak in SiGe at 1.55 eV). For this reason, for example, when the semiconductor substrate 1 and the second semiconductor layer 3 are Si and the first semiconductor layer 2 is SiGe, a laser beam having a wavelength λ ₁ is irradiated to a region of 500 to 700 nm, and further, a wavelength λ ₂ By irradiating the laser, energy larger than the bond energy of Si—Ge can be given to the first semiconductor layer 2 by two-stage excitation.

Thereby, it becomes possible to selectively bring the first semiconductor layer 2 into an excited state by irradiation with laser light having the wavelength λ ₁ , and the wavelength λ ₂ necessary for transitioning the first semiconductor layer 2 to the anti-coupled state. The energy of the laser beam can be reduced. For this reason, even when the binding energy of the constituent elements of the first semiconductor layer 2 and the binding energy of the constituent elements of the second semiconductor layer 3 are close, the bond between the constituent elements of the second semiconductor layer 3 is suppressed. However, the bonds of the constituent elements of the first semiconductor layer 2 can be cut, and the etching rate of the first semiconductor layer 2 can be increased.

  When the binding energy of the constituent elements of the first semiconductor layer 2 is close to the binding energy of the constituent elements of the second semiconductor layer 3, the bonds of the constituent elements of the first semiconductor layer 2 are selectively dissociated by two-stage excitation. In addition to the method, the vibration state between the constituent elements of the first semiconductor layer 2 is excited to a high vibration state by multiphoton absorption, and the bonds of the constituent elements of the first semiconductor layer 2 are selectively dissociated. Also good.

FIG. 5 is a diagram illustrating an excitation method by multiphoton absorption according to an embodiment of the present invention.
In FIG. 5, while irradiating a laser having a wavelength that matches a vibration frequency unique only to the elements constituting the first semiconductor layer 2, the first semiconductor layer 2 is successively brought into a high vibration excitation state by multiphoton absorption. By exciting, it is possible to shift to an electronically excited state higher than the binding energy of the constituent elements of the first semiconductor layer 2.

FIG. 6 is a diagram showing an infrared absorption spectrum of Si and SiGe according to an embodiment of the present invention.
In FIG. 6, as disclosed in “Physical Review B, Volume 59, pp 10614-10621 (1999)”, an absorption peak appears in the vicinity of 390 cm ⁻¹ (48 meV) in the infrared absorption spectrum of SiGe. Therefore, for example, when the semiconductor substrate 1 and the second semiconductor layer 3 are Si and the first semiconductor layer 2 is SiGe, infrared laser light having a wavelength λ ₁ is irradiated in the vicinity of 390 cm ⁻¹ , and one after another by multiphoton absorption. By energizing in a high vibrationally excited state, energy larger than the bond energy of Si—Ge can be given to the first semiconductor layer 2.

  As a result, the first semiconductor layer 2 can be shifted to an excited state higher than the binding energy of the constituent elements of the first semiconductor layer 2 while selectively shifting the first semiconductor layer 2 to the vibrationally excited state. It is possible to reduce the energy of the laser necessary for transition to the coupled state. For this reason, even when the binding energy of the constituent elements of the first semiconductor layer 2 and the binding energy of the constituent elements of the second semiconductor layer 3 are close, the bond between the constituent elements of the second semiconductor layer 3 is suppressed. However, the bonds of the constituent elements of the first semiconductor layer 1 can be cut, and the etching rate of the first semiconductor layer 2 can be increased.

  The first semiconductor layer 2 is irradiated with a first laser having a wavelength that is smaller than the binding energy of the elements constituting the first semiconductor layer 2 and has a larger extinction coefficient than the second semiconductor layer 3. By irradiating the first semiconductor layer 2 in the vibrationally excited state by irradiation with the first laser after being excited in the vibrationally excited state, the binding energy of the constituent elements of the first semiconductor layer 2 is exceeded. You may make it make it change to a high excited state.

  Next, as shown in FIG. 7, a base oxide film 4 is formed on the surface of the second semiconductor layer 3 by a method such as thermal oxidation or CVD of the second semiconductor layer 3. This oxide film becomes a protective film for the next dry etching. Next, as shown in FIG. 8, by patterning the base oxide film 4, the sacrificial oxide film 4, the second semiconductor layer 3, and the first semiconductor layer 2 using a photolithography technique and an etching technique, the semiconductor substrate 1 A groove 6 for exposing a part of the groove 6 is formed. When a part of the semiconductor substrate 1 is exposed, the etching may be stopped on the surface of the semiconductor substrate 1 or the semiconductor substrate 1 may be over-etched to form a recess in the semiconductor substrate 1. . Further, the arrangement position of the groove 6 can correspond to a part of the element isolation region of the second semiconductor layer 3.

Next, the support 5 is formed on the entire surface of the substrate by a method such as CVD. As shown in FIG. 9, the support 5 is also formed on the side walls of the first semiconductor layer 2 and the second semiconductor layer 3 in the groove 6, and supports the second semiconductor layer 3 on the semiconductor substrate 1. As a material of the support 5, an insulator such as a silicon oxide film or a silicon nitride film is used.
Next, as shown in FIG. 10, the first semiconductor layer 2 is patterned by patterning the support 5, the base oxide film 4, the second semiconductor layer 3, and the first semiconductor layer 2 using a photolithography technique and an etching technique. A groove 8 for exposing a part of the groove 8 is formed. Here, the arrangement position of the groove 8 can correspond to the remaining portion of the element isolation region of the second semiconductor layer 3.

  When a part of the first semiconductor layer 2 is exposed, the etching may be stopped on the surface of the first semiconductor layer 2, or the first semiconductor layer 2 is over-etched to form a recess in the first semiconductor layer. You may make it form. Alternatively, the surface of the semiconductor substrate 1 may be exposed through the first semiconductor layer 2 in the groove 8. Here, it is possible to prevent the surface of the semiconductor substrate 1 in the groove 8 from being exposed by stopping the etching of the first semiconductor layer 2 halfway. For this reason, when the first semiconductor layer 2 is removed by etching, the time during which the semiconductor substrate 1 in the groove 8 is exposed to the etching solution or the etching gas can be reduced, and the overetching of the semiconductor substrate 1 in the groove 8 can be reduced. Can be suppressed.

Next, as shown in FIG. 11, the first semiconductor layer 2 is removed by etching by bringing an etching gas or an etchant into contact with the first semiconductor layer 2 through the groove 8, so that the semiconductor substrate 1 and the second semiconductor layer are removed. And a cavity 9 is formed between the two.
Here, by selectively forming the dissociation point K in the first semiconductor layer 2 by laser irradiation, the etching rate of the first semiconductor layer 2 can be increased while suppressing damage to the second semiconductor layer 3. It becomes possible. Therefore, the first semiconductor layer 2 can be selectively etched while suppressing the second semiconductor layer 3 from being etched, and the etching area of the first semiconductor layer 2 below the second semiconductor layer 3 is limited. Can be relaxed. As a result, the width of the second semiconductor layer 3 that can be formed on the oxide film 10 can be increased while suppressing the deterioration of the crystal quality of the second semiconductor layer 3, and the second semiconductor layer 3 with good crystal quality can be obtained. It can be formed on the oxide film 10 at low cost.

  In addition, by providing the support 5 in the groove 6, the second semiconductor layer 3 can be supported on the semiconductor substrate 1 even when the first semiconductor layer 2 is removed. In addition, by providing the groove 8 separately, the etching gas or the etching solution can be brought into contact with the first semiconductor layer 2 below the second semiconductor layer 3. For this reason, it is possible to achieve insulation between the second semiconductor layer 3 and the semiconductor substrate 1 without impairing the quality of the second semiconductor layer 3.

  When the semiconductor substrate 1 and the second semiconductor layer 3 are Si and the first semiconductor layer 2 is SiGe, hydrofluoric acid (a mixed solution of hydrofluoric acid, nitric acid, and water) is used as the etchant for the first semiconductor layer 2. preferable. As a result, a Si / SiGe selection ratio of about 1: 100 to 1000 can be obtained, and the first semiconductor layer 2 can be removed while suppressing overetching of the semiconductor substrate 1 and the second semiconductor layer 3. It becomes.

Next, as shown in FIG. 12, the oxide film 10 is formed in the cavity 9 between the semiconductor substrate 1 and the second semiconductor layer 3 by performing thermal oxidation of the semiconductor substrate 1 and the second semiconductor layer 3. At the same time, an oxide film 11 is formed on the side wall of the second semiconductor layer 3 in the trench 8.
Thus, the film thickness of the second semiconductor layer 3 after element isolation can be defined by the film thickness of the second semiconductor layer 3 during epitaxial growth and the film thickness of the oxide film 11 during thermal oxidation of the second semiconductor layer 3. it can. For this reason, it is possible to control the film thickness of the second semiconductor layer 3 with high accuracy, and to reduce the variation in the film thickness of the second semiconductor layer 3 while reducing the thickness of the second semiconductor layer 3. it can.

  In addition, the first semiconductor layer 2 and the second semiconductor layer 3 having different etching rates are sequentially formed on the semiconductor substrate 1 and the grooves 6 and 8 are formed in two steps, whereby the semiconductor substrate 1 and The oxide film 10 can be formed in the cavity 9 between the second semiconductor layer 3. Therefore, it is possible to stably manufacture a high-quality SOI substrate while suppressing an increase in processes, and it is possible to stably manufacture an SOI transistor while suppressing an increase in cost.

  Further, by providing the support 5 on the second semiconductor layer 3, the oxide film 10 is formed on the back surface side of the second semiconductor layer 3 while preventing the surface of the second semiconductor layer 3 from being thermally oxidized. It becomes possible. Therefore, the surface of the second semiconductor layer 3 can be exposed while preventing the oxide film 11 formed in each of the grooves 6 and 8 from being eroded, and the element isolation can be performed stably. However, a transistor can be formed in the second semiconductor layer 3.

  In addition, by making the arrangement positions of the grooves 6 and 8 correspond to the element isolation regions of the second semiconductor layer 3, it becomes possible to collectively perform the element isolation in the horizontal direction and the vertical direction of the second semiconductor layer 3. Therefore, it is not necessary to separately provide a groove for removing the first semiconductor layer 2 below the second semiconductor layer 3. Therefore, an SOI transistor can be formed while suppressing an increase in the number of processes, and an increase in chip size can be suppressed, so that the cost of the SOI transistor can be reduced.

Note that high-temperature annealing may be performed after the oxide films 10 and 11 are formed. As a result, the support 5 can be reflowed, and the oxide film 10 grown from above and below the cavity 9 can be bonded without a gap.
Next, as shown in FIG. 13, after the buried insulating layer 13 is buried in the grooves 6 and 8 by a method such as CVD, the base oxide film 4 and the support 5 on the base oxide film 4 are removed. As a result, it is possible to embed the buried insulating layer 13 in the trenches 6 and 8 at a time, and it is possible to stably perform element isolation while suppressing an increase in the number of processes. Alternatively, the buried insulating layer 13 may be buried in the grooves 6 and 8 after removing the base oxide film 4 and the support 5 on the base oxide film 4. If necessary, the buried insulating layer 13 may be planarized by a method such as CMP (Chemical Mechanical Polishing).

  Next, as shown in FIG. 14, the surface of the second semiconductor layer 3 is thermally oxidized to form a gate insulating film 21 on the surface of the second semiconductor layer 3. Then, a polycrystalline silicon layer is formed on the second semiconductor layer 3 on which the gate insulating film 21 is formed by a method such as CVD. Then, the gate electrode 22 is formed on the second semiconductor layer 3 by patterning the polycrystalline silicon layer using a photolithography technique and an etching technique.

  Next, by using the gate electrode 22 as a mask, impurities such as As, P, and B are ion-implanted into the second semiconductor layer 3, thereby forming LDDs composed of low-concentration impurity introduction layers respectively disposed on both sides of the gate electrode 22. Layers 23 a and 23 b are formed on the second semiconductor layer 3. Then, an insulating layer is formed on the second semiconductor layer 3 on which the LDD layers 23a and 23b are formed by a method such as CVD, and the insulating layer is etched back using anisotropic etching such as RIE. Side walls 24a and 24b are formed on the side walls of the electrode 22, respectively. Then, by using the gate electrode 22 and the sidewalls 24a and 24b as masks, impurities such as As, P, and B are ion-implanted into the second semiconductor layer 3 to be respectively disposed on the sides of the sidewalls 24a and 24b. Source / drain layers 25 a and 25 b made of high-concentration impurity introduction layers are formed in the second semiconductor layer 3.

  Accordingly, the first semiconductor layer between the second semiconductor layer 3 and the semiconductor substrate 1 can be removed over a wide range while the second semiconductor layer 3 can be stably supported on the semiconductor substrate 1. In addition, the oxide film 10 can be formed on the back surface side of the second semiconductor layer 3 by thermal oxidation of the second semiconductor layer 3. Therefore, by using the bulk substrate, the second semiconductor layer 3 can be formed on the oxide film 10 and the width of the second semiconductor layer 3 that can be formed on the oxide film 10 can be increased. This makes it possible to form a high-quality SOI transistor while suppressing an increase in cost.

  In the above-described embodiment, the method of collectively filling the buried insulating layer 13 in the grooves 6 and 8 after forming the oxide films 10 and 11 has been described. However, before forming the groove 8, the support 5 is formed. An insulator may be embedded in the groove 6 in which is formed. As a result, the support 5 can be reinforced with an insulator, and the second semiconductor layer 3 can be stably supported on the semiconductor substrate 1 even when the width of the groove 6 is narrow.

In the above-described embodiment, the method for laminating the second semiconductor layer 3 by one layer on the semiconductor substrate 1 through the oxide film 10 has been described. However, a plurality of semiconductor layers are formed on the semiconductor substrate through the oxide film, respectively. 1 may be stacked on top of each other.
In the above-described embodiment, the method for forming the base oxide film 4 on the body layer 3 has been described. However, if there is a risk of etching damage on the surface of the second semiconductor layer 3, The support 5 may be formed without forming the base oxide film 4.

In the above-described embodiment, the method of irradiating the first semiconductor layer 2 with the laser after forming the second semiconductor layer 3 on the first semiconductor layer 2 and before forming the grooves 6 and 8 has been described. The first semiconductor layer 2 may be irradiated with laser after the formation of the groove 6 or the groove 8, or any time before the first semiconductor layer 2 is removed by etching.
In the above-described embodiment, the method in which the second semiconductor layer 3 is epitaxially grown on the first semiconductor layer 2 and then laser irradiation is performed on the first semiconductor layer 2 has been described. However, the second semiconductor layer 2 is formed on the first semiconductor layer 2. Before the semiconductor layer 3 is epitaxially grown, the first semiconductor layer 2 may be irradiated with laser.

The figure which shows the manufacturing method of the semiconductor device which concerns on one Embodiment of this invention. The figure which shows the manufacturing method of the semiconductor device which concerns on one Embodiment of this invention. The figure which shows the two step excitation method which concerns on one Embodiment of this invention. The figure which shows the visible ultraviolet absorption spectrum of Si and SiGe. The figure which shows the excitation method by multiphoton absorption which concerns on one Embodiment of this invention. The figure which shows the infrared absorption spectrum of Si and SiGe. The figure which shows the manufacturing method of the semiconductor device which concerns on one Embodiment of this invention. The figure which shows the manufacturing method of the semiconductor device which concerns on one Embodiment of this invention. The figure which shows the manufacturing method of the semiconductor device which concerns on one Embodiment of this invention. The figure which shows the manufacturing method of the semiconductor device which concerns on one Embodiment of this invention. The figure which shows the manufacturing method of the semiconductor device which concerns on one Embodiment of this invention. The figure which shows the manufacturing method of the semiconductor device which concerns on one Embodiment of this invention. The figure which shows the manufacturing method of the semiconductor device which concerns on one Embodiment of this invention. The figure which shows the manufacturing method of the semiconductor device which concerns on one Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Semiconductor substrate, 2 1st semiconductor layer, 3rd semiconductor layer, 4 Underlayer oxide film, 5 Support body, 6, 8 Element isolation groove, 7 Support body, 9 Cavity part, 10, 11, 12 Oxide film, 13 Buried insulating layer, 21 gate insulating film, 22 gate electrode, 23a, 23b LDD layer, 24a, 24b sidewall spacer, 25a, 25b source / drain layer, K dissociation point

Claims (10)

Forming a first semiconductor layer on a semiconductor substrate;
Forming a second semiconductor layer having a lower etching rate than the first semiconductor layer on the first semiconductor layer;
Dissociating bonds of elements constituting the first semiconductor layer by irradiating the first semiconductor layer with laser through the second semiconductor layer; and
Forming an exposed portion for exposing a part of the first semiconductor layer from the second semiconductor layer;
Forming a first groove through the first semiconductor layer and the second semiconductor layer to expose the semiconductor substrate;
Forming a support in the first groove, which is made of a material having an etching rate smaller than that of the first semiconductor layer and supports the second semiconductor layer on the semiconductor substrate;
The cavity from which the first semiconductor layer has been removed by selectively etching the first semiconductor layer irradiated with the laser through the exposed portion while being supported by the support, and the semiconductor substrate. Forming between the second semiconductor layer;
Forming an insulating film embedded in the cavity by thermally oxidizing the semiconductor substrate and the second semiconductor layer in the cavity through the exposed portion. Manufacturing method. Forming a first semiconductor layer on a semiconductor substrate;
Forming a second semiconductor layer having a lower etching rate than the first semiconductor layer on the first semiconductor layer;
Dissociating bonds of elements constituting the first semiconductor layer by irradiating the first semiconductor layer with laser through the second semiconductor layer; and
Forming a first groove through the first semiconductor layer and the second semiconductor layer to expose the semiconductor substrate;
Forming a support formed in sidewalls of the first semiconductor layer and the second semiconductor layer and having a lower etching rate in the first groove than the first semiconductor layer;
Forming a second groove for exposing at least a part of the first semiconductor layer formed on the side wall of the support from the second semiconductor layer;
By selectively etching the first semiconductor layer irradiated with the laser through the second groove, the cavity from which the first semiconductor layer has been removed is interposed between the semiconductor substrate and the second semiconductor layer. Forming , and
Through a pre-Symbol second groove, wherein by thermally oxidizing the semiconductor substrate and the second semiconductor layer, a semiconductor substrate, characterized in that it comprises a step of forming an insulating film embedded in said cavity Production method. The laser irradiation step includes
Exciting the first semiconductor layer to a high vibration excitation state by multiphoton absorption while irradiating a laser having a wavelength corresponding to a vibration frequency unique to only between elements constituting the first semiconductor layer. 3. The method of manufacturing a semiconductor substrate according to claim 1, wherein the semiconductor substrate is shifted to an excited state higher than the binding energy of the constituent elements of one semiconductor layer. The laser irradiation step includes
Exciting the first semiconductor layer into a high-vibration excited state by multiphoton absorption while irradiating a first laser having a wavelength that matches a vibration frequency that is unique only between elements constituting the first semiconductor layer;
Irradiating the first semiconductor layer in a high vibration excitation state by irradiation with the first laser with a second laser to transition to an excitation state higher than the binding energy of the constituent elements of the first semiconductor layer; The method for manufacturing a semiconductor substrate according to claim 1, further comprising: Forming a first semiconductor layer on a semiconductor substrate;
Dissociating the bonds of the elements constituting the first semiconductor layer by irradiating the first semiconductor layer with laser;
Forming a second semiconductor layer having an etching rate smaller than that of the first semiconductor layer on the laser-irradiated first semiconductor layer;
Forming an exposed portion for exposing a part of the first semiconductor layer from the second semiconductor layer;
Forming a first groove through the first semiconductor layer and the second semiconductor layer to expose the semiconductor substrate;
Forming a support in the first groove, which is made of a material having an etching rate smaller than that of the first semiconductor layer and supports the second semiconductor layer on the semiconductor substrate;
The first semiconductor layer is selectively etched through the exposed portion while being supported by the support, thereby removing the cavity from which the first semiconductor layer has been removed from the semiconductor substrate and the second semiconductor layer. A step of forming between
Forming an insulating film embedded in the cavity by thermally oxidizing the semiconductor substrate and the second semiconductor layer in the cavity through the exposed portion. Manufacturing method. Forming a first semiconductor layer on a semiconductor substrate;
Dissociating the bonds of the elements constituting the first semiconductor layer by irradiating the first semiconductor layer with laser;
Forming a second semiconductor layer having an etching rate smaller than that of the first semiconductor layer irradiated with the laser on the first semiconductor layer;
Dissociating bonds of elements constituting the first semiconductor layer by irradiating the first semiconductor layer with laser through the second semiconductor layer; and
Forming a first groove through the first semiconductor layer and the second semiconductor layer to expose the semiconductor substrate;
Forming a support formed in sidewalls of the first semiconductor layer and the second semiconductor layer and having a lower etching rate in the first groove than the first semiconductor layer;
Forming a second groove for exposing at least a part of the first semiconductor layer formed on the side wall of the support from the second semiconductor layer;
Forming a cavity from which the first semiconductor layer is removed between the semiconductor substrate and the second semiconductor layer by selectively etching the first semiconductor layer through the second groove ;
Through a pre-Symbol second groove, wherein by thermally oxidizing the semiconductor substrate and the second semiconductor layer, a semiconductor substrate, characterized in that it comprises a step of forming an insulating film embedded in said cavity Production method. Said semiconductor substrate and said second semiconductor layer is a single crystal Si, the first semiconductor layer manufacturing method of a semiconductor substrate according to any one of claims 1 6, characterized in that the single crystal SiGe. The method of manufacturing a semiconductor substrate according to claim 7 , wherein the first semiconductor layer is selectively etched by a hydrofluoric acid treatment of the first semiconductor layer. Forming a first semiconductor layer on a semiconductor substrate;
Forming a second semiconductor layer having a lower etching rate than the first semiconductor layer on the first semiconductor layer;
Dissociating bonds of elements constituting the first semiconductor layer by irradiating the first semiconductor layer with laser through the second semiconductor layer; and
Forming an exposed portion for exposing a part of the first semiconductor layer from the second semiconductor layer;
Forming a first groove through the first semiconductor layer and the second semiconductor layer to expose the semiconductor substrate;
Forming a support in the first groove, which is made of a material having an etching rate smaller than that of the first semiconductor layer and supports the second semiconductor layer on the semiconductor substrate;
The cavity from which the first semiconductor layer has been removed by selectively etching the first semiconductor layer irradiated with the laser through the exposed portion while being supported by the support, and the semiconductor substrate. Forming between the second semiconductor layer;
Forming an insulating film embedded in the cavity by thermally oxidizing the semiconductor substrate and the second semiconductor layer in the cavity through the exposed portion;
Forming a gate electrode on the second semiconductor layer through a gate insulating film;
Forming a source / drain layer respectively disposed on both sides of the gate electrode in the second semiconductor layer. Forming a first semiconductor layer on a semiconductor substrate;
Dissociating the bonds of the elements constituting the first semiconductor layer by irradiating the first semiconductor layer with laser;
Forming a second semiconductor layer having an etching rate smaller than that of the first semiconductor layer on the laser-irradiated first semiconductor layer;
Forming an exposed portion for exposing a part of the first semiconductor layer from the second semiconductor layer;
Forming a first groove through the first semiconductor layer and the second semiconductor layer to expose the semiconductor substrate;
Forming a support in the first groove, which is made of a material having an etching rate smaller than that of the first semiconductor layer and supports the second semiconductor layer on the semiconductor substrate;
The first semiconductor layer is selectively etched through the exposed portion while being supported by the support, thereby removing the cavity from which the first semiconductor layer has been removed from the semiconductor substrate and the second semiconductor layer. A step of forming between
Forming an insulating film embedded in the cavity by thermally oxidizing the semiconductor substrate and the second semiconductor layer in the cavity through the exposed portion;
Forming a gate electrode on the second semiconductor layer through a gate insulating film;
Forming a source / drain layer respectively disposed on both sides of the gate electrode in the second semiconductor layer.

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