JP4447413B2 - Manufacturing method of semiconductor device - Google Patents

Description

  The present invention relates to a method for manufacturing a semiconductor element applicable to a field effect transistor, a sensor, a light emitting diode, and the like, and more particularly to a method for manufacturing a semiconductor element using a diamond thin film.

Diamond has a thermal conductivity of 20W / cm · K, the band gap 5.47 eV, mobility 2000 cm ² / V · sec saturated electron, and 2100 cm ² / V · sec hole mobility, excellent device characteristics Show. For this reason, application to high power devices, high-frequency devices, and electronic devices that operate even in harsh environments exposed to high temperatures or radiation is expected.

  Conventionally, as a semiconductor element using a diamond thin film, there is an insulated gate field effect transistor (MISFET) in which an insulator layer is inserted between a gate electrode and a channel layer as an operation layer ( For example, see Patent Document 1.) FIG. 5 is a cross-sectional view showing the structure of the MISFET described in Patent Document 1. As shown in FIG. 5, a MISFET 100 described in Patent Document 1 includes highly doped p-type semiconductor diamond layers 102a and 102b doped with boron at a high concentration on an insulating diamond single crystal substrate 101 to serve as a source and a drain. Is formed.

  In addition, between the highly doped p-type semiconductor diamond layer 102a and the highly doped p-type semiconductor diamond layer 102b on the insulating diamond single crystal substrate 101, the concentration is lower than those of the highly doped p-type diamond thin film layers 102a and 102b. A lightly doped p-type semiconductor diamond layer 103 which is a channel layer doped with boron is formed. Further, a source electrode 104 and a drain electrode 105 are formed on the highly doped p-type semiconductor diamond layers 102a and 102b, respectively, and an undoped diamond layer serving as an insulator layer is formed on the low-doped p-type semiconductor diamond layer 103. A gate electrode 107 is formed via 106.

  As a method for manufacturing such a diamond semiconductor element, for example, a diamond region is separated by etching to form a source and a drain, and a diamond serving as a channel region is exposed, and an insulating layer and a gate electrode are formed thereon. There is a method of forming (see Patent Document 2). Also, there is a manufacturing method in which a diamond region is separated by etching, selective growth method or selective ion implantation method to form a source and a drain, and a diamond thin film is selectively grown to cover a gap and its vicinity to form a channel region. It has been proposed (see Patent Document 3). Further, a manufacturing method has been developed in which a diamond region is separated by etching to form a source and a drain, and then a diamond thin film is selectively grown to fill the etched region to form a channel region (see Patent Document 4). .)

  At this time, as a method for etching diamond, for example, a plasma etching method is used in which a mask made of ladder silicone spin-on glass is formed on the surface of the diamond, and the material to be etched is exposed to plasma generated from a gas containing oxygen atoms. (For example, see Patent Documents 5 and 6).

  Conventionally, a method for manufacturing a semiconductor element has been proposed in which a semiconductor layer is formed by epitaxially growing a semiconductor material having a wurtzite crystal structure, such as a gallium nitride-based compound semiconductor, on a substrate having a specific crystal plane. (For example, see Patent Documents 7 and 8). As described in Patent Documents 7 and 8, the semiconductor layer formed by the epitaxial growth method has an inclined surface inclined at a certain angle with respect to the substrate surface. FIGS. 6A to 6D and FIGS. 7A to 7E are cross-sectional views showing a conventional semiconductor element method for forming a semiconductor layer by an epitaxial growth method in the order of steps.

  In the conventional method of manufacturing a semiconductor device, first, as shown in FIG. 6B, a mask layer made of, for example, silicon oxide and silicon nitride is formed on the main surface of the epitaxial growth substrate 111 shown in FIG. 112 is formed. At this time, as the epitaxial growth substrate 111, for example, a sapphire substrate having a C-plane as a main surface is used. Next, as shown in FIG. 6C, after forming a photosensitive resist film 113 on the mask layer 112, the photosensitive resist film 113 is exposed in a predetermined pattern as shown in FIG. 6D. To do.

  Then, a portion other than the exposed portion (resist mask) 113a in the photosensitive resist film 113 is removed to form a mask processing resist pattern shown in FIG. Next, as shown in FIG. 7B, the mask layer 112 is etched using the resist mask 113a as a mask, and then the resist mask 113a is removed as shown in FIG. A patterned epitaxial mask 112a is formed. Next, as shown in FIG. 7D, a semiconductor layer 114 made of, for example, a gallium nitride compound semiconductor is epitaxially grown in the opening of the epitaxial mask 112a, that is, the region where the epitaxial mask 112a is not formed. As shown in FIG. 7E, the epitaxial mask 112a is removed.

  Thereafter, for example, when an FET having the semiconductor layer 114 as a source and drain is manufactured as a semiconductor element, a channel layer is formed between the semiconductor layers 114, a gate electrode is formed on the channel layer via a gate insulating film, and the semiconductor is formed. A source electrode and a drain electrode are formed over the layer 114.

Japanese Patent Laid-Open No. 1-158774 JP 2000-114523 A JP 2002-57167 A JP 2002-76369 A Japanese Patent Laid-Open No. 10-330188 JP 2002-75960 A JP 2003-31841 A JP 2003-209325 A

  However, the conventional techniques described above have the following problems. That is, when the semiconductor layer 114 is formed by the conventional method shown in FIGS. 6 and 7, the resist mask 113a is first patterned, then the mask layer 112 is patterned using the resist mask 113a as a mask, and the epitaxial mask 112a is formed. Therefore, there is a problem that an error in the two patterning steps is multiplied to increase a processing dimension error.

  In addition, by adding a catalyst, the organometallic compound can be modified in its properties by energy such as light, for example, between a modified portion and a non-modified portion, Differences in solubility in various solvents can be provided. For this reason, for example, when a photosensitive material mainly composed of an organometallic compound such as spin-on-glass described in Patent Document 5 is used, an epitaxial mask can be directly formed on the substrate by a lithography technique. An epitaxial mask formed of such a photosensitive material has a problem that thermal and mechanical properties are close to those of an organic material, and these physical property values are greatly different from those of a substrate made of an inorganic material. Furthermore, an epitaxial mask formed of a photosensitive material containing an organometallic compound as a main component has a problem that adhesion to the substrate is low. For this reason, when an epitaxial mask is formed using a photosensitive material containing an organometallic compound as a main component, peeling and cracks occur in the mask in the epitaxial growth process performed at a high temperature, and diamond is not formed in a predetermined region. Will grow.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a method of manufacturing a semiconductor element that can reduce a processing dimension error when a semiconductor layer is formed by an epitaxial growth method.

The method of manufacturing a semiconductor element according to the first invention of the present application includes a step of forming a photosensitive paste layer containing an organometallic compound containing at least one functional group selected from the group consisting of a hydroxyl group and an alkoxy group on a substrate; The photosensitive paste layer is patterned by photolithography to form a mask, the mask is oxidized or reduced to remove organic components, and the mask on the substrate surface is formed by an epitaxial growth method. The method includes a step of forming a semiconductor layer over a region not formed and a step of removing the mask.

In the present invention, a photosensitive paste layer containing an organometallic compound containing at least one functional group selected from the group consisting of a hydroxyl group and an alkoxy group is formed on a substrate, and the photosensitive paste layer is formed by photolithography. By patterning, an organic metal compound is polymerized to form a mask mainly composed of a metal oxide. Therefore, a mask for epitaxial growth can be formed directly on the substrate, and the patterning process is more effective than conventional methods. Can be less. In the present invention, since the organic component remaining in the mask is decomposed and removed by oxidizing or reducing after the mask is formed, the difference in thermal and mechanical properties between the mask and the substrate is eliminated. And the mask can be prevented from peeling and cracking in the epitaxial growth process. As a result, it is possible to reduce a processing dimension error when the semiconductor layer is formed by the epitaxial growth method.

  A method of manufacturing a semiconductor element according to the second invention of the present application includes a step of forming a buffer layer on a substrate, a step of forming a photosensitive paste layer containing an organometallic compound on the buffer layer, and the photosensitive paste layer. Forming a mask by patterning the substrate by photolithography, and removing the buffer layer formed on the region of the substrate surface where the mask is not formed, and then forming a semiconductor layer on the region by epitaxial growth And a step of removing the mask and a buffer layer formed between the mask and the substrate.

  In the present invention, a photosensitive paste layer containing an organometallic compound is patterned by photolithography to form an epitaxial growth mask mainly composed of a metal oxide on the substrate directly. In addition, the number of manufacturing processes can be reduced. In the present invention, since the buffer layer is formed between the substrate and the mask, the adhesion between the mask and the substrate is improved, and the mask can be prevented from peeling off from the substrate in the epitaxial growth process. Even when the organic component remains in the mask, the adhesion between the mask and the substrate can be maintained high. As a result, it is possible to reduce a processing dimension error when forming a semiconductor layer by an epitaxial method.

  According to a third aspect of the present invention, there is provided a method for manufacturing a semiconductor device comprising: forming a buffer layer on a substrate; forming a photosensitive paste layer containing an organometallic compound on the buffer layer; and the photosensitive paste layer. Patterning by photolithography to form a mask; oxidizing or reducing the mask to remove organic components; and forming the mask on the surface of the substrate where the mask is not formed A step of forming a semiconductor layer by epitaxial growth on the region after removing the buffer layer; and a step of removing the mask and the buffer layer formed between the mask and the substrate. And

  In the present invention, a photosensitive paste layer containing an organometallic compound is patterned by photolithography to form an epitaxial growth mask mainly composed of a metal oxide on the substrate directly. In addition, the number of manufacturing processes can be reduced. Further, in the present invention, after the mask is formed, an oxidation treatment or a reduction treatment is performed to reduce organic components remaining in the mask, and a buffer layer is formed between the substrate and the mask. In this case, peeling of the mask and generation of cracks can be prevented. As a result, it is possible to reduce a processing dimension error when the semiconductor layer is formed by the epitaxial growth method.

  The thickness of the buffer layer is, for example, 1/100 or less of the thickness of the mask. Thereby, the etching amount of the mask layer when the buffer layer formed in the epitaxial growth region is removed by etching can be suppressed to the extent that the characteristics are not affected.

  In these methods for manufacturing a semiconductor element, an organometallic compound containing at least one functional group selected from the group consisting of a hydroxyl group and an alkoxy group can be used as the organometallic compound. Since these hydroxyl groups (—OH) and alkoxy groups (—OR) are both functional groups containing oxygen, a metal oxide can be easily formed.

  The semiconductor layer may be formed of diamond. Further, the substrate may be formed of a semiconductor material, and in that case, diamond can be used as the semiconductor material. Thereby, a diamond semiconductor element with a small processing dimension error can be manufactured by an epitaxial growth method.

  According to the present invention, since a photosensitive paste layer containing an organometallic compound is patterned by photolithography, a mask for epitaxial growth mainly composed of a metal oxide is directly formed on a substrate. The number of times of patterning can be reduced as compared with the above, and the organic component remaining in the mask is reduced and / or the buffer layer is formed between the mask and the substrate. Can be prevented, and as a result, the processing dimension error when the semiconductor layer is formed by the epitaxial growth method can be reduced.

  Hereinafter, a method for manufacturing a semiconductor device according to an embodiment of the present invention will be specifically described with reference to the accompanying drawings. As a result of conducting extensive experimental research to solve the above-mentioned problems, the present inventors found that the problem in the case of using the photosensitive material mainly composed of the organometallic compound described above is still in the epitaxial mask even after development. It was found that this is due to the remaining organic components. This residual organic component, for example, acts as a contaminant at the interface between the epitaxial mask and the substrate and reduces the adhesion between the substrate and the epitaxial mask. However, in the method for manufacturing a semiconductor device of the present invention, at least in the epitaxial mask In order to perform either one of the step of reducing the organic component of the substrate and the step of forming the buffer layer between the epitaxial mask and the substrate, a photosensitive material mainly composed of an organometallic compound is used, and lithography is performed on the substrate. Even when an epitaxial mask is directly formed on the mask, peeling of the mask and generation of cracks in the epitaxial growth process can be prevented. As a result, the processing dimension error can be reduced even when the semiconductor layer is formed by the epitaxial growth method.

  First, a method for manufacturing a semiconductor device according to the first embodiment of the present invention will be described. FIGS. 1A to 1D and FIGS. 2A to 2E are cross-sectional views showing a method of manufacturing a semiconductor device according to this embodiment in the order of steps. In the method for manufacturing a semiconductor device of this embodiment, first, as shown in FIG. 1A, an epitaxial growth substrate 1 made of a semiconductor material is prepared. As this epitaxial growth substrate 1, for example, a semiconductor diamond single crystal substrate, silicon single crystal, germanium, gallium arsenide, gallium nitride having a (100) surface and doped with impurities such as boron, nitrogen and phosphorus. A substrate made of indium phosphide, indium arsenide, silicon carbide, or the like can be used.

  Next, as shown in FIG. 1B, a photosensitive mask layer 2 having a thickness of, for example, 300 nm and a main component being an organometallic compound is formed on the substrate 1. The photosensitive mask layer 2 is formed, for example, by applying a photosensitive paste in which an organic metal compound is added with a photoacid generator that generates acid by light and a solvent, and then baking the substrate. Can do. The organometallic compound that is the main component of the photosensitive mask layer 2 may be a compound that generates a metal oxide, such as a metal hydroxide having a structure of M-OH (M: metal atom). An organometallic compound containing a hydroxyl group or an organometallic compound containing an alkoxy group such as a metal alkoxide can be used. In particular, a metal alkoxide that is hydrolyzed with moisture to have an alkoxy group as a hydroxyl group is more preferable because the reaction state can be appropriately adjusted.

  Examples of the metal alkoxide used in the method for manufacturing a semiconductor device of the present embodiment include tetraethoxytitanium, tetraisopropoxytitanium, and tetranormalbutoxytitanium for compounds containing titanium (Ti) as a metal element. In a compound containing silicon (Si) as a metal element, tetraethoxysilane, tetraisopropoxysilane, tetramethoxysilane, tetranormalbutoxysilane, triethoxyfluorosilane, triethoxysilane, trisopropoxyfluorosilane, trimethoxyfluorosilane, Trimethoxysilane, trinormal butoxysilane, trinormalpropoxyfluorosilane, trimethylmethoxysilane, trimethylethoxysilane, trimethylchlorosilane, phenyltriethoxysila , Phenyl diethoxy chlorosilane, methyl trimethoxysilane, methyl triethoxysilane, ethyl triethoxysilane, dimethyl dimethoxysilane, dimethyl diethoxy silane and tris methoxyethoxy vinyl silane and the like.

  For compounds containing aluminum (Al) as a metal element, triethoxyaluminum, triisobutoxyaluminum, triisopropoxyaluminum, trimethoxyaluminum, trinormalbutoxyaluminum, trinormalporopoxyaluminum, trisecondary butoxyaluminum Examples of the compound containing boron (B) as a metal element include triethoxyboron, triisobutoxyboron, triisopropoxyboron, trimethoxyboron, trinormalbutoxyboron, and trisecondary butoxyboron. It is done.

  Furthermore, examples of the compound containing germanium (Ge) as a metal element include tetraethoxygermanium, tetraisopropoxygermanium, tetramethoxygermanium, and tetranormalbutoxygermanium. A compound containing lanthanum (La) as a metal element includes trismethoxyethoxy. Lanthanum, bismethoxyethoxymagnesium for compounds containing magnesium (Mg) as a metal element, and pentaethoxyniobium, pentaisopropoxyniobium, pentamethoxyniobium, pentanormalbutoxyniobium and pentanormal for compounds containing niobium (Nb) as a metal element Examples include propoxyniobium.

  Furthermore, in the compound containing phosphorus (P) as a metal element, triethyl phosphate, triethyl phosphite, toy isopropoxy phosphite, triisopropoxy phosphite, trimethyl phosphite, trimethyl phosphite, trinormal butyl phosphate, tri Examples thereof include normal butyl phosphite and trinormal propyl phosphite. Examples of compounds containing tantalum (Ta) as a metal element include pentaethoxy tantalum, pentaisopropoxy tantalum, and pentamethoxy tantalum.

  Furthermore, in the compound containing tin (Sn) as a metal element, tetratertiary butoxy tin, tin acetate, triisopropoxy normal butyl tin and the like can be mentioned. In the compound containing vanadium (V) as a metal element, triethoxy vanadyl, Examples of the compound containing zirconium (Zr) as a metal element include tetraisopropoxyzirconium, tetranormalbutoxyzirconium, and tetratertiary butoxyzirconium.

  Among these metal alkoxides, tetraisopropoxytitanium, tetranormalbutoxytitanium, tetraethoxysilane, tetraisopropoxysilane, tetramethoxysilane, tetranormalbutoxysilane, triisobutoxyaluminum and trisopropoxyaluminum are widely used industrially. It is more preferable because it is easy to obtain and handle. In addition, these metal alkoxides may use only 1 type as a raw material, or may use the mixture of 2 or more types of metal alkoxides.

Next, as a lithography process, as shown in FIG. 1C, the photosensitive mask layer 2 is irradiated with the electron beam 3 in a predetermined pattern shape, for example, at a dose of 50 keV and 5 to 50 μC / cm ² . Thereby, in the part 2a irradiated with the electron beam 3 in the photosensitive mask layer 2, an acid is generated from the photoacid generator, this acid serves as a catalyst, and a dehydration condensation reaction of the organometallic compound proceeds, and Ti, Si , Al, Ge, La, Mg, Nb, P, Ta, Sn, V, Zr, and other metal elements, and metal oxides insoluble in organic solvents and alkaline solutions are generated.

  Next, as a development step, for example, the substrate 1 is immersed in a solvent in which the photosensitive mask layer 2 such as an alcohol solution dissolves for a predetermined time, and then the substrate 1 is washed with ultrapure water or the like. As a result, as shown in FIG. 1 (d), the portion other than the electron beam irradiated portion 2 a, that is, the portion not irradiated with the electron beam 3 in the photosensitive mask layer 2 is removed, and the metal oxide is formed on the substrate 1. An epitaxial mask pattern containing as a main component is formed. Thereafter, the organic component remaining in the electron beam irradiated portion 2a is decomposed and removed by oxidation treatment or reduction treatment to form the epitaxial mask 4 shown in FIG. At this time, as the oxidation treatment, for example, heat treatment is performed in at least one kind of oxidizing gas selected from the group consisting of oxygen, ozone, dinitrogen oxide and water vapor, or exposure to plasma containing these oxidizing gases. Or the like can be applied. Further, as the reduction treatment, for example, heat treatment is performed in at least one reducing gas selected from the group consisting of hydrogen, carbon monoxide, and carbon hydrogen, or exposure to plasma containing these reducing gases. Etc. can be applied. Note that when the organic component remaining by the plasma treatment is decomposed and removed, a reactive component is included, and damage to the substrate becomes significant. Therefore, it is preferable to keep the substrate temperature at 300 ° C. or lower.

  Next, the substrate 1 on which the epitaxial mask 4 shown in FIG. 2A is formed is held in hydrogen-diluted methane plasma for about 20 minutes, for example. In that case, the temperature of the board | substrate 1 is hold | maintained at about 800 degreeC, for example. As a result, as shown in FIG. 2B, diamond is epitaxially grown in a region where the epitaxial mask 4 is not formed on the substrate 1 to form semiconductor diamond layers 5a and 5b. Next, as shown in FIG. 2C, the epitaxial mask 4 is removed by, for example, holding the substrate 1 in hot phosphoric acid at about 180 ° C. for about 10 minutes.

  When this semiconductor element is, for example, a transistor in which the semiconductor diamond layers 5a and 5b are the source and drain, respectively, as shown in FIG. 2 (d), between the semiconductor diamond layers 5a and 5b on the surface of the substrate 1 A gate electrode 9 is formed on the region, that is, on the channel region via the gate insulating film 6, and a source electrode 7 and a drain electrode 8 are formed on the semiconductor diamond layers 5a and 5b, respectively.

  In the method of manufacturing a semiconductor device of this embodiment, since the epitaxial mask 4 made of a metal oxide is formed directly on the substrate 1 using an organometallic compound as a main raw material, the number of patterning steps is reduced as compared with the conventional method. Can do. Further, in the method of manufacturing a semiconductor device of this embodiment, the organic component remaining in the epitaxial mask 4 is reduced by performing oxidation treatment or reduction treatment after development. Further, the difference in mechanical properties can be reduced, and peeling of the epitaxial mask 4 and generation of cracks can be prevented in the epitaxial growth process. As a result, it is possible to reduce a processing dimension error when the semiconductor layer is formed by the epitaxial growth method.

  Next, a method for manufacturing a semiconductor element according to the second embodiment of the present invention will be described. FIGS. 3A to 3D and FIGS. 4A to 4E are cross-sectional views showing the method of manufacturing the semiconductor device of this embodiment in the order of the steps. 3 and 4, the same components as those in the method of manufacturing the semiconductor device of the first embodiment shown in FIGS. 1 and 2 are denoted by the same reference numerals, and detailed description thereof is omitted. In the method of manufacturing a semiconductor device of this embodiment, first, as shown in FIG. 3A, an epitaxial growth substrate 1 made of a semiconductor material is made of an inorganic material that is the same as the metal oxide that forms the epitaxial mask. The buffer layer 10 is formed.

  The buffer layer 10 must be removed before the epitaxial growth process is performed. At this time, the epitaxial mask is also etched together. Therefore, it is desirable to make the buffer layer 10 as thin as possible. If the buffer layer 10 is formed in principle by about one atomic layer, the effect can be obtained. However, in practical use, the buffer layer 10 may be 1/100 or less of the thickness of the epitaxial mask. If the thickness of the buffer layer 10 exceeds 1/100 of the thickness of the epitaxial mask, the processing dimension error of the epitaxial mask cannot be ignored.

  Next, as shown in FIG. 3B, a photosensitive paste whose main component is an organometallic compound is applied on the buffer layer 10 to form a photosensitive mask layer 2 having a thickness of, for example, 300 nm. The organometallic compound that is the main component of the photosensitive mask layer 2 may be any compound that generates a metal oxide of the same quality as the buffer layer 10. For example, an organometallic compound containing a hydroxyl group and / or an alkoxy group may be used. Can be used. Among these organometallic compounds, it is more preferable to use a metal alkoxide.

Next, as a lithography process, as shown in FIG. 3C, the photosensitive mask layer 2 is irradiated with the electron beam 3 in a predetermined pattern shape, for example, at a dose of 50 keV and 5 to 50 μC / cm ² . Thereby, in the part 2a irradiated with the electron beam 3 in the photosensitive mask layer 2, an acid is generated from the photoacid generator, this acid serves as a catalyst, and a dehydration condensation reaction of the organometallic compound proceeds, and the organic solvent and A metal oxide insoluble in an alkali solution or the like is generated.

  Next, as a development step, for example, the substrate 1 is immersed in a solvent in which the photosensitive mask layer 2 such as an alcohol solution dissolves for a predetermined time, and then the substrate 1 is washed with ultrapure water or the like. As a result, as shown in FIG. 3D, the part other than the electron beam irradiated part 2a, that is, the part not irradiated with the electron beam 3 in the photosensitive mask layer 2 is removed. Thereafter, as shown in FIG. 4A, the buffer layer 10 formed in the region where the semiconductor layer is epitaxially grown is obtained by a method such as holding the substrate 1 in hot phosphoric acid at about 180 ° C. for about 30 seconds. After removing, an epitaxial mask 14 having a metal oxide as a main component is formed on the substrate 1. When the buffer layer 10 is etched, the epitaxial mask 14 is also etched. However, since the etching amount is about the thickness of the buffer layer 10, that is, 1/100 or less of the thickness of the epitaxial mask 14, It does not affect the characteristics of

  Next, the substrate 1 on which the epitaxial mask 14 shown in FIG. 4A is formed is held in hydrogen-diluted methane plasma for about 20 minutes, for example. In that case, the temperature of the board | substrate 1 is hold | maintained at about 800 degreeC, for example. As a result, as shown in FIG. 4B, diamond is epitaxially grown in the region where the epitaxial mask 14 is not formed on the substrate 1 to form semiconductor diamond layers 5a and 5b. Next, as shown in FIG. 4C, the epitaxial mask 14 and the buffer layer 10 are removed by a method such as holding the substrate 1 in hot phosphoric acid at about 180 ° C. for about 10 minutes, for example.

  When this semiconductor element is, for example, a transistor in which the semiconductor diamond layers 5a and 5b are the source and drain, respectively, as shown in FIG. 4 (d), between the semiconductor diamond layers 5a and 5b on the surface of the substrate 1 A gate electrode 9 is formed on the region, that is, on the channel region via the gate insulating film 6, and a source electrode 7 and a drain electrode 8 are formed on the semiconductor diamond layers 5a and 5b, respectively.

  In the method for manufacturing a semiconductor device of this embodiment, an epitaxial mass 14 made of a metal oxide is formed directly on the substrate 1 using an organometallic compound as a main raw material, so that there are fewer patterning steps than the conventional method. Thus, the number of manufacturing steps can be reduced, and the processing dimension error can be reduced.

  Further, in the method of manufacturing a semiconductor device according to the present embodiment, the substrate 1 and the epitaxial mask are made of the same inorganic material as the epitaxial mask 14 between the substrate 1 made of an inorganic material and the epitaxial mask 14 made of a metal oxide. 14 is formed, the adhesion between the epitaxial mask 14 and the substrate 1 is improved, and the epitaxial mask 14 can be prevented from being peeled off from the substrate 1 in the epitaxial growth process. Further, since the buffer layer 10 can be provided to suppress a sudden change in physical properties between the epitaxial mask 14 and the substrate 1, the epitaxial mask 14 and the epitaxial mask 14 can be formed even when an organic component remains in the epitaxial mask 14. High adhesion to the substrate 1 can be maintained. As a result, it is possible to prevent the epitaxial mask 4 from being peeled off from the substrate 1 or the epitaxial mask 4 from being cracked in the epitaxial growth step.

  In the semiconductor device manufacturing method of the first and second embodiments described above, after forming an epitaxial mask pattern, the mask is oxidized or reduced, or a buffer is provided between the epitaxial mask and the substrate. Although the layer is provided, the present invention is not limited to this, and these may be used in combination. That is, a buffer layer may be provided between the epitaxial mask and the substrate, and the epitaxial mask may be oxidized or reduced to decompose and remove organic components remaining in the mask. As a result, the adhesion between the substrate and the epitaxial mask is further improved, and peeling and cracks are less likely to occur in the mask in the epitaxial growth process.

  In the semiconductor element manufacturing methods of the first and second embodiments described above, the semiconductor layer is formed of diamond. However, the present invention is not limited to this. For example, silicon, germanium, gallium are used. The semiconductor layer may be formed of arsenic, gallium nitride, indium phosphide, indium arsenic, silicon carbide, or the like.

  Furthermore, in the semiconductor element manufacturing methods of the first and second embodiments described above, the epitaxial growth substrate 1 is formed of a semiconductor material. However, the present invention is not limited to this, and the substrate 1 is Any semiconductor material may be used as long as the semiconductor material is epitaxially grown on the surface. For example, an insulating diamond single crystal substrate having a {110} surface may be used. When an insulating substrate is used as the substrate for epitaxial growth, a semiconductor element such as a transistor can be manufactured by forming a channel layer between opposing semiconductor layers, for example.

  Furthermore, in the first and second embodiments described above, the case where a transistor is manufactured as a semiconductor element has been described as an example. However, the present invention is not limited to this. For example, various sensors and The present invention can also be applied to the manufacture of light emitting diodes and the like, and similar effects can be obtained.

  Hereinafter, the effect of the embodiment of the present invention will be described by taking a field effect transistor using a diamond thin film as an example in comparison with a comparative example that is out of the scope of the present invention. First, as a first example of the present invention, a transistor was manufactured by a method similar to the method for manufacturing the semiconductor device of the first embodiment shown in FIGS. In this embodiment, a semiconductor diamond single crystal substrate having a (100) surface and doped with boron as an impurity is used as the epitaxial growth substrate 1, and an alcohol-based solvent is added to tri-normal butoxyaluminum on the substrate 1. Then, after applying the paste to which the photoacid generator was added, the substrate 1 was baked with a hot plate at 80 ° C. for 5 minutes to form a photosensitive mask layer 2 having a thickness of 300 nm on the substrate 1.

Next, using an electron beam exposure apparatus, the photosensitive mask layer 2 was irradiated with the electron beam 3 in a predetermined pattern shape at a dose of 5 to 50 μC / cm ² at 50 keV. At that time, the electron beam 3 was selectively irradiated only to the region where the semiconductor layer was not formed. As a result, in the portion 2a irradiated with the electron beam 3 in the photosensitive mask 2, tri-normal butoxyaluminium is dehydrated and polymerized using the acid generated from the photoacid generator as a catalyst, and insoluble in organic solvents and alkaline solutions. Aluminum was produced.

  Next, after immersing the substrate 1 in an alcohol solution for 1 minute, the substrate 1 is washed with ultrapure water for 1 minute to remove a portion of the photosensitive mask layer 2 that is not irradiated with the electron beam 3, and further a remote method. Thus, the substrate 1 was exposed to hydrogen plasma for 30 minutes to decompose and remove organic components, thereby forming an epitaxial mask 4 made of aluminum oxide. During the hydrogen plasma treatment, the temperature of the substrate 1 was set to 300 ° C. or lower.

  Next, the substrate 1 was held in methane plasma diluted with hydrogen for 20 minutes, and diamond semiconductor layers 5a and 5b serving as a source and a drain were epitaxially grown on the surface of the substrate 1. At that time, the temperature of the substrate was kept at 800 ° C. Then, the substrate 1 was kept in hot phosphoric acid at 180 ° C. for 10 minutes, and the epitaxial mask 4 was removed. Thereafter, a channel layer 6 is formed between the diamond semiconductor layers 5a and 5b, a gate electrode 9 is formed on the channel layer 6 via a gate insulating film 6, and a source is formed on the diamond semiconductor layers 5a and 5b, respectively. The electrode 7 and the drain electrode 8 were formed to obtain the transistor of Example 1.

  Next, as a second embodiment of the present invention, the organic component remaining in the epitaxial mask 4 is decomposed and removed by oxygen plasma treatment instead of hydrogen plasma treatment, and the other methods and methods similar to those of the first embodiment described above, Under the conditions, the transistor of Example 2 was manufactured. As the oxygen plasma treatment in this example, the temperature of the substrate 1 was kept at 300 ° C. or lower, and the substrate 1 was exposed to oxygen plasma for 30 minutes by a remote method.

  Next, as a third example of the present invention, a transistor was manufactured by a method similar to the method for manufacturing the semiconductor device of the second embodiment shown in FIGS. In this embodiment, a semiconductor diamond single crystal substrate having a (100) surface and doped with boron is used as the epitaxial growth substrate 1, and a buffer layer is formed on the substrate 1 by atomic layer CVD. As a result, an alumina film having a thickness of 1 nm was formed. Then, after applying a paste obtained by adding an alcohol solvent and a photoacid generator to tri-normal butoxyaluminum on this alumina film, the substrate 1 was baked at 80 ° C. for 5 minutes by a hot plate, A photosensitive mask layer 2 having a thickness of 300 nm was formed.

Next, using an electron beam exposure apparatus, the photosensitive mask layer 2 was irradiated with the electron beam 3 in a predetermined pattern shape at a dose of 5 to 50 μC / cm ² at 50 keV. At that time, the electron beam 3 was selectively irradiated only to the region where the semiconductor layer was not formed. As a result, in the portion 2a irradiated with the electron beam 3 in the photosensitive mask 2, tri-normal butoxyaluminum is dehydrated and polymerized using the acid generated from the photoacid generator as a catalyst, and insoluble in organic solvents and alkaline solutions. Aluminum was produced.

  Next, after immersing the substrate 1 in an alcohol solution for 1 minute, the substrate 1 is washed with ultrapure water for 1 minute to remove a portion of the photosensitive mask layer 2 that is not irradiated with the electron beam 3. Was kept in hot phosphoric acid at 180 ° C. for 30 seconds, the alumina film formed in the region where the semiconductor layer was epitaxially grown was removed, and an epitaxial mask 14 mainly composed of aluminum oxide was formed on the substrate 1.

  Next, the substrate 1 was held in methane plasma diluted with hydrogen for 20 minutes, and diamond semiconductor layers 5a and 5b serving as a source and a drain were epitaxially grown on the surface of the substrate 1. At that time, the temperature of the substrate was kept at 800 ° C. Then, the substrate 1 was held in hot phosphoric acid at 180 ° C. for 10 minutes, and the alumina film as the epitaxial mask 14 and the buffer layer 10 was removed. Thereafter, a channel layer 6 is formed between the diamond semiconductor layers 5a and 5b, a gate electrode 9 is formed on the channel layer 6 via a gate insulating film 6, and a source is formed on the diamond semiconductor layers 5a and 5b, respectively. An electrode 7 and a drain electrode 8 were formed to form a transistor of Example 3.

  Further, as a comparative example of the present invention, a transistor was manufactured by epitaxially growing diamond using an epitaxial mask directly formed on an epitaxial growth substrate without performing hydrogen plasma treatment, oxygen plasma treatment, and formation of a buffer layer. . In this comparative example, first, a paste in which an alcohol solvent and a photoacid generator are added to trinormalbutoxyaluminum is applied onto a semiconductor diamond single crystal substrate having a (100) surface and doped with boron. After that, the substrate was baked at 80 ° C. for 5 minutes with a hot plate to form a photosensitive mask layer having a thickness of 300 nm on the substrate 1.

Next, using an electron beam exposure apparatus, the photosensitive mask layer was irradiated with an electron beam in a predetermined pattern shape at a dose of 5 to 50 μC / cm ² at 50 keV. At that time, the electron beam was selectively irradiated only to the region where the semiconductor layer was not formed. As a result, tri-normal butoxyaluminum undergoes dehydration polymerization using the acid generated from the photoacid generator as a catalyst in the portion of the photosensitive mask irradiated with the electron beam, and aluminum oxide insoluble in organic solvents and alkaline solutions is generated. did.

  Next, the substrate was immersed in an alcohol solution for 1 minute and then washed with ultrapure water for 1 minute to remove a portion of the photosensitive mask layer that was not irradiated with an electron beam, thereby forming an epitaxial mask. Then, the substrate on which this epitaxial mask was formed was held in hydrogen-diluted methane plasma for 20 minutes, and diamond was epitaxially grown in a region on the substrate surface where the epitaxial mask was not formed to form a diamond semiconductor layer serving as a source and drain. . At that time, the temperature of the substrate was kept at 800 ° C. Thereafter, the substrate was kept in hot phosphoric acid at 180 ° C. for 10 minutes, and the epitaxial mask was removed. Next, a channel layer is formed between the diamond semiconductor layers, a gate electrode is formed on the channel layer via a gate insulating film, and a source electrode and a drain electrode are formed on the diamond semiconductor layer, respectively. An example transistor was used.

  In the method of manufacturing a semiconductor device according to the first to third embodiments of the present invention, it is possible to manufacture a transistor with little processing dimensional error without abnormality such as cracks and peeling in the epitaxial mask even after the epitaxial growth process. did it. On the other hand, in the semiconductor device manufacturing method of the comparative example, when the sample was observed after the epitaxial growth step, a crack was generated in a part of the epitaxial mask formed in the peripheral portion of the substrate. Furthermore, in the transistor of the comparative example manufactured by this method, diamond was epitaxially grown in the portion where the crack was generated in the epitaxial mask, and the diamond semiconductor layer was shifted from the predetermined pattern. The yield of pattern defects in this comparative transistor was about 90%.

(A) thru | or (d) are sectional drawings which show the manufacturing method of the semiconductor element of the 1st Embodiment of this invention in the order of the process. (A) thru | or (e) are sectional drawings which show the manufacturing method of the semiconductor element of the 1st Embodiment of this invention in order of the process, (a) shows the next process of FIG.1 (d). (A) thru | or (d) are sectional drawings which show the manufacturing method of the semiconductor element of the 2nd Embodiment of this invention in the order of the process. (A) thru | or (e) are sectional drawings which show the manufacturing method of the semiconductor element of the 1st Embodiment of this invention in order of the process, (a) shows the next process of FIG.3 (d). 6 is a cross-sectional view showing the structure of a MISFET described in Patent Document 1. FIG. (A) thru | or (d) are sectional drawings which show the manufacturing method of the conventional semiconductor element which forms a semiconductor layer by an epitaxial growth method in the order of the process. (A) thru | or (e) is sectional drawing which shows the manufacturing method of the conventional semiconductor element which forms a semiconductor layer by an epitaxial growth method in the order of the process, (a) shows the next process of FIG.6 (d).

Explanation of symbols

1, 111; Substrate 2; Photosensitive mask layer 2a; Electron beam irradiated portion 3; Electron beam 4, 14, 112a; Epitaxial mask 5a, 5b; Semiconductor diamond layer 7, 104; Source electrode 8, 105; Gate insulating films 9, 107; gate electrode 10; buffer layer 100; insulated gate field effect transistor (MISFET)
101; Diamond single crystal substrate 102a, 102b; Highly doped p-type semiconductor diamond layer 103; Low-doped p-type semiconductor diamond layer 106; Undoped diamond layer 112; Mask layer 113; Photosensitive resist film 113a;

Claims (8)

Forming a photosensitive paste layer containing an organometallic compound containing at least one functional group selected from the group consisting of a hydroxyl group and an alkoxy group on a substrate; and patterning the photosensitive paste layer by photolithography. A step of forming a mask, a step of oxidizing or reducing the mask to remove organic components, a step of forming a semiconductor layer on a region of the substrate surface where the mask is not formed by an epitaxial growth method, And a step of removing the mask. Forming a buffer layer on the substrate; forming a photosensitive paste layer containing an organometallic compound on the buffer layer; and patterning the photosensitive paste layer by photolithography to form a mask; Removing the buffer layer formed on a region of the substrate surface where the mask is not formed, and then forming a semiconductor layer on the region by epitaxial growth; the mask, the mask and the substrate; And a step of removing the buffer layer formed therebetween. Forming a buffer layer on the substrate; forming a photosensitive paste layer containing an organometallic compound on the buffer layer; and patterning the photosensitive paste layer by photolithography to form a mask; A step of removing an organic component by oxidizing or reducing the mask, and removing the buffer layer formed on a region of the substrate surface where the mask is not formed, and then performing an epitaxial growth method on the region. A method of manufacturing a semiconductor device, comprising: forming a semiconductor layer on the substrate; and removing the mask and a buffer layer formed between the mask and the substrate. 4. The method of manufacturing a semiconductor device according to claim 2, wherein the thickness of the buffer layer is 1/100 or less of the thickness of the mask. 5. The semiconductor element according to claim 2, wherein the organometallic compound is an organometallic compound containing at least one functional group selected from the group consisting of a hydroxyl group and an alkoxy group. Manufacturing method. 6. The method of manufacturing a semiconductor element according to claim 1, wherein the semiconductor layer is formed of diamond. The method of manufacturing a semiconductor element according to claim 1, wherein the substrate is made of a semiconductor material. The method of manufacturing a semiconductor device according to claim 7, wherein the semiconductor material is diamond.

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