JPH0722313A - Semiconductor device and manufacturing method thereof - Google Patents

Abstract

PURPOSE:To provide the title manufacturing method of SOI structured semiconductor device capable of eliminating the complicated steps and specific substrate for creating the thermal environment in a seed part or increasing the design allowance as well as electrically insulating a substrate from a single crystalline semiconductor thin film perfectly. CONSTITUTION:The title semiconductor device adopts a (100) surface single crystalline Si substrate 1 as a single crystalline semiconductor substrate also CaF2 as a fluoride as well as an Si thin film as a semiconductor thin film 6. At this time, an insulating film 2 having a partial aperture part 4 is formed on the single crystalline Si substrate 1 so as to selectively grow a CaF2/Si dual layered film (Si (silicon) layer formed on a CaF2 layer). Finally, after the formation of the Si thin film 6 on the whole substrate 1, the Si thin film 6 formed on the CaF2/Si dual layered film is single-crystallized using the same as a seed part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device used for a highly integrated LSI (three-dimensional integrated circuit), a high breakdown voltage device, a radiation resistant device and the like, and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, an SOI (Semiconducer) has been used to increase the density and speed of semiconductor circuits and reduce power consumption.
tor On Insulator) devices are under development.
When obtaining an SOI structure, it is important to form a good quality single crystal thin film on an insulating layer, and at present, a method of controlling the crystal orientation of SOI using a Si substrate as a seed crystal is used.
The most reliable and widely adopted.

FIG. 13 is a diagram for explaining a method of controlling the crystal orientation of SOI using a Si substrate as a seed. Referring to FIG. 13, in this method, a single crystal Si substrate 10 is used.
1. An insulating film 102 having a partial opening 104 is formed on the insulating film 1, and then a polycrystalline or amorphous S film is formed on the insulating film 102.
The i thin film 103 is formed, and then the Si thin film 103 is formed.
The laser beam 105 is irradiated onto the substrate to perform laser beam annealing. At this time, the Si substrate exposed on the surface of the opening 104 of the insulating film 102 is used as a seed, and its crystal information is transferred from the Si thin film of the opening 104 to the Si thin film on the insulating film 102.
The thin film 103 is melted and recrystallized to form a single crystal Si thin film.

By the way, when the SOI structure is formed by the lateral epitaxial growth method using the Si substrate 101 as a seed, the opening 104 and other portions are formed due to the difference in thermal conductivity between the Si substrate 101 and the insulating film 102. There is a problem that the optimum conditions for laser beam annealing are very difficult to determine because the thermal environments differ significantly between and. That is, since the base of the opening 104 is the Si substrate 101, the thermal conductivity is large and heat easily escapes, while the insulating film 10
2 has a low thermal conductivity, which causes the S of the opening 104 to
Heat is more likely to be accumulated in the Si thin film on the insulating film 102 than in the i thin film. As described above, since the thermal environment is significantly different between the opening 104 and other portions (that is, the thermal environment around the seed portion is significantly different), it is very difficult to determine the optimum conditions for laser beam annealing. There is.

Further, in the above-mentioned method of controlling the crystal orientation of SOI using the Si substrate as a seed crystal (seed), the crystal orientation continuously changes as the distance from the seed portion increases. The device characteristics are varied between the device manufactured at a position separated from the seed part and the device manufactured at a position separated from the seed part. There is a problem that the space between them cannot be widened.

Further, in the method of forming the SOI structure by the lateral epitaxial growth method using the underlying Si substrate as a seed crystal, the substrate and the single crystal Si thin film cannot be electrically separated completely. In particular, when a linear seed is used, that portion serves as a barrier and divides the underlying active region, so that there is a problem that the degree of freedom in device arrangement is significantly reduced.

In order to solve such a problem, Japanese Patent Laid-Open No. 63-81807 (hereinafter referred to as Conventional Example 1), Japanese Patent Laid-Open No. 63-102221 (hereinafter referred to as Conventional Example 2), and Japanese Patent Laid-Open No. Hei-2. A technique disclosed in No. 161717 (hereinafter referred to as Conventional Example 3) has been proposed.

That is, the inventions disclosed in the conventional example 1 and the conventional example 2 were made to adjust the thermal environment around the seed portion. In the invention of the conventional example 1, first, the single crystal silicon substrate is exposed. Non-single-crystal silicon having a film thickness almost equal to the thickness of the insulating film is embedded only on the dot-shaped region, and a non-single-crystal silicon thin film to be single-crystallized is formed on the entire surface. Next, an antireflection film is formed, and a region where the non-single-crystal silicon is embedded is irradiated with a light beam to preliminarily make the non-single-crystal silicon in this region into a single crystal that matches the crystal orientation of the single-crystal silicon substrate. Next, a stripe-shaped silicon film is formed on the antireflection film so as to cover the single-crystallized embedded silicon portion. By irradiating a light beam wider than the stripe width of this stripe-shaped silicon film, the non-single-crystal silicon thin film on the insulating film is single-crystallized using the embedded silicon that has been previously single-crystallized as a seed, and the single-crystal silicon substrate and the crystal orientation To obtain a single crystal silicon film.

Further, according to the invention of Conventional Example 2, when a non-single-crystal semiconductor island is formed on the insulator substrate in an insulatingly separated manner, a part of the non-single-crystal semiconductor island is covered with a light reflecting film, and a laser beam is applied. When irradiated to melt and single crystallize, the non-single crystal semiconductor island immediately below the light-reflecting film is used as a seed and single crystallization is performed in a state where it remains unmelted. Trying to get.

Further, the invention of Conventional Example 3 was made in order to widen the seed interval between the device manufactured near the seed and the device manufactured at a position distant from the seed to improve the design margin of the device. In order to achieve this object, a silicon substrate having an orientation tilted within 20 ° in the [0-11] direction with the [100] axis as a rotation axis with respect to the (001) plane is used. I am trying.

[0011]

However, in the inventions of Conventional Example 1 and Conventional Example 2, there are drawbacks such that the production process of the single crystal thin film is complicated and the throughput is lowered because the thermal environment of the seed portion is adjusted. there were.

Further, in the invention of Conventional Example 3, the substrate used is limited in order to improve the design margin of the device,
It had the drawback of poor versatility.

Further, in any of the above-mentioned conventional example 1, conventional example 2 and conventional example 3, the substrate and the semi-crystalline Si thin film cannot be electrically separated completely.

The present invention has been made in order to solve the above-mentioned conventional drawbacks, and it involves complicated steps for adjusting the thermal environment of the seed portion and improving the design margin of the device. ， Eliminates the need to use a special substrate,
Moreover, it is an object of the present invention to provide a semiconductor device having an SOI structure capable of electrically completely separating a substrate and a single crystal semiconductor thin film, and a manufacturing method thereof.

[0015]

FIG. 1 is a diagram showing a configuration example of a semiconductor device according to the present invention. This semiconductor device includes a single crystal semiconductor substrate 1, an insulating film 2 formed by partially providing an opening 4 on the single crystal semiconductor substrate 1, and the opening 4 described above.
It is characterized in that it has a fluorine compound 3 formed by epitaxial growth on the surface of the substrate 1 which is exposed at 1 and a semiconductor thin film 6 formed on the fluorine compound 3 and the insulating film 2.

In the semiconductor device of FIG. 1, for example, a (100) plane single crystal Si substrate is used as the single crystal semiconductor substrate 1,
When CaF ₂ is used as the fluorine compound 3 and a Si thin film is used as the semiconductor thin film 6, the insulating film 2 having a partial opening 4 is formed on the single crystal Si substrate 1, and CaF 2 is formed on this portion by a heteroepitaxial growth method. _After selectively growing a ₂ / Si bilayer film (a film in which a Si (silicon) layer is formed on a CaF ₂ layer) and then forming a Si thin film on the entire substrate, a CaF ₂ / Si bilayer is formed. By using the film as a seed portion, the Si thin film laminated thereon can be single-crystallized. That is, the crystal information of the substrate 1 is first set to CaF.
Take over the _two layers, then it is reflected in the Si layer on the CaF ₂ layer, a polycrystalline or amorphous Si thin film 6 deposited on the whole substrate including the seed unit with a laser beam or heat sources such as electron beams The SOI structure can be formed by annealing and lateral growth using the Si layer on the CaF ₂ layer as a seed crystal (seed).

However, when CaF ₂ is grown on the flat Si substrate 1 (the surface is the (100) plane) by the usual method, the surface of the CaF ₂ layer 702 is (111) as shown in FIG. ) A non-uniform micro-facet 703 having a pyramid-shaped size is formed. If a Si thin film is laterally grown by heteroepitaxial growth or melt recrystallization on the CaF ₂ layer 702 in this state, the growth state becomes nonuniform and defects are likely to occur.

In order to avoid such a problem, FIG.
As shown in FIG. 1, first, a V-shaped groove 5 of (111) plane is formed on the surface of the Si substrate 1 exposed in the opening 4, and the Si substrate 1 other than the V-shaped groove 5 is formed. It is preferable to treat the insulating film 2 so that CaF ₂ does not grow on the insulating film ₂ such as SiO ₂ formed on the surface. That is, since the fluoride crystal having a strong polarity has the surface free energy of the (111) plane smaller than that of the other planes, when the fluorine compound 3, that is, CaF ₂ is grown on the V-shaped groove 5, the growth is always (111). ) Proceed so that the surface faces the surface. Further, CaF ₂ is prevented from growing laterally by the insulating film 2 and selectively grows only in the V-shaped groove 5, and as a result, the surface of the grown CaF ₂ facing the surface of the V-shaped groove 5 is opposed. The ((111) plane) 10 has an inverted V shape. Since this inverted V-shape is stable in crystal structure, the Si thin film 6 can be accurately formed in a large area. It should be noted that this inverted V-shaped shape is 100 to 1 as described later.
It is good to have an apex angle in the range of 20 °. Thus, according to the method of the present invention, the shape of the CaF ₂ facet is S
CaF having a uniform shape within the accuracy of photolithography, which is determined by the size of the opening 4 of the insulating film 2 on the i substrate 1.
_Two seeds can be formed.

3 (a) and 3 (b) respectively show the heat flow in the recrystallization process at the time of manufacturing the semiconductor device according to the present invention and at the time of manufacturing the conventional semiconductor device (semiconductor device of FIG. 13). It is a figure. Conventionally, heat is designated by the symbol H in FIG.
Since it flows as shown by T ₂ , the thermal environment around the seed portion is remarkably different. However, in the present invention, the fluorine compound 3 is formed in the seed portion at the interface between the single crystal Si substrate 1 and the Si thin film 6. , That is, CaF ₂ exists, and CaF ₂ has a smaller thermal conductivity than Si (Si: 0.34 cal / cm ・ sec ・ d
eg CaF ₂ : 0.02 cal / cm · sec · deg), heat flows as shown by reference numeral HT ₁ in FIG. 3 (a), and the heat can be suppressed from escaping to the substrate 1 at the seed portion, and the seed portion can be suppressed. It is possible to effectively prevent a situation where the surrounding thermal environment is significantly different.

Further, in the structure of the present invention, when the Si thin film 6 is melted and recrystallized, the (1) of the Si thin film 6 which becomes a solid-liquid interface is formed.
11) It is possible to realize a structure in which the plane and the CaF ₂ layer are in uniform contact with each other in the growth direction. For this reason, CaF ₂
The heat once accumulated in the layer can be uniformly supplied to the Si thin film 6. Further, the lateral thermal diffusion in the CaF ₂ layer portion can mitigate the influence on the recrystallization due to the variation in the output of the heat source such as the laser beam. As a result, it is possible to reduce the fluctuation of the thermal environment between the SOI part and the seed part in the melt recrystallization process,
It is possible to prevent the crystallinity of the i thin film 6 from decreasing.

Since CaF ₂ is an insulator, the single crystal Si thin film and the underlying Si substrate 1 can be completely electrically separated by the insulating film such as SiO ₂ and the CaF ₂ layer. As a result, it becomes possible to form a device on the seed portion, which has been impossible in the past, and the degree of freedom in designing the device can be greatly improved.

In the above example, the seed portion of the CaF ₂ / Si laminated structure is provided on the single crystal Si substrate 1 to form the single crystal S.
Although the SOI structure of the i thin film 6 was obtained, in addition to this, by taking into consideration the lattice constant difference between each material, the melting point, and the like, it is possible to take the configuration shown in the following table according to the purpose of use.

[0023]

[Table 1]

4 (a) to 4 (c) and 5 (a) to 5 (c) are views showing an example of a manufacturing process of a single crystal Si thin film according to the present invention. Referring to FIGS. 4A to 4C and 5A to 5C, first, Si, Ge, GaAs, I
An insulating film 2 is deposited on the (100) plane of a single crystal substrate 1 made of nP, GaP or the like. As the insulating film, SiO ₂ ,
A material such as Si ₃ N ₄ or SiON is used in a single layer or multiple layers. As a preferable material among them, as shown in Table 1, for example, a combination of a single crystal substrate of Si and an insulating film of SiO ₂ can be used. Next, the opening 4 is partially provided in the insulating film 2 by photolithography to expose a part of the surface of the single crystal substrate 1 (FIG. 4A). In addition,
As shown, the openings 4 are formed in stripes in parallel with the [100] direction of the substrate 1 and have a width w of 1 μm to 5 μm.
0 μm, preferably 1.5 μm, and its pitch P is 10 μm to 1 mm, preferably 100 μm. Next, the surface portion of the substrate 1 exposed in the opening 4 is processed to form a V-shaped groove 5 (FIG. 4B). This processing is wet etching using an alkaline solution such as KOH. It is possible to carry out by using S.
When the i substrate is used, Si has an apex angle θ ₁ of about 110 ± 10 ° formed on the (111) plane because the etching rate of the (111) plane is slower than that of other surfaces with respect to an alkaline solution. The V-shaped groove 5 having can be formed.

Next, the V-shaped groove 5 thus formed
A fluorine compound 3 such as CaF ₂ , SrF ₂ , BaF ₂ , and Ca _x Sr _1-x F ₂ is selectively grown on it (FIG. 4C).
When Si is used as the substrate 1, CaF _{2 having} a good lattice matching with Si is a preferable material for the fluorine compound 3.
Can be used. The selectively grown CaF ₂ is
The apex angle θ ₂ has an inverted V shape with a range of 100 to 120 °. The height from the surface of the Si substrate 1 is determined by the width w of the opening 4.

Next, the Si thin film 6'is selectively grown on the inverted V-shaped fluorine compound 3, that is, CaF ₂ (FIG. 5A). Si, which is a non-polar material, is Ca
Epitaxial growth is performed in the (111) plane orientation so as to cover the inverted V-shape of F ₂ , and is formed as a Si thin film 6 ′ having a film thickness in the range of 100Å to 1 μm, preferably about 1000Å. Si coated with the insulating film 2 by the above method
CaF having an inverted V-shaped stripe on the substrate 1
_{The 2} / Si laminated structure (3, 6 ′) can be formed as a seed portion. Next, the Si thin film 6 is deposited on the entire substrate by
It is deposited to a film thickness of 0 Å to 10 μm, preferably about 3000 Å (FIG. 5B). Here, the Si thin film 6 is epitaxially grown on the seed portion (3, 6 ′), and the insulating film 2
Above it becomes polycrystalline or amorphous. Next, a material such as SiO ₂ , Si ₃ N ₄ , or SiON, preferably SiO ₂ is formed as a protective film 7 on the Si thin film 6 as a protective film 7 with a thickness of 5000 Å to 10 μm, preferably about 1 μm. To do. Finally, a laser beam 8 is irradiated to melt and recrystallize the polycrystalline or amorphous Si thin film 6 (FIG. 5).
(C)). As described above, in the method according to the present invention, the heat for recrystallization causes reverse V between the surface of the Si thin film 6 and the seed portion.
It is supplied from V-shaped CaF ₂ and can suppress the heat fluctuation in the seed portion. Further, when the inverted V-shaped CaF ₂ is formed in a stripe shape, it also functions to diffuse the variation in the output of the laser beam, so that a uniform temperature distribution can be obtained in a wide area and the solid-liquid interface ( Recrystallization on the crystal growth surface) proceeds uniformly. Therefore, the method according to the present invention can realize stable crystal growth.

That is, in the present invention, by using a fluorine compound thin film such as CaF ₂ formed by the heteroepitaxial growth method in the seed portion, it is possible to reduce the deviation of the temperature distribution in the vicinity of the seed portion during the process of melt recrystallization. Further, the CaF ₂ stripe formed by the (111) plane alleviates the fluctuation of the output of the heat source such as the laser beam, so that the thermal environment of the seed portion, which is the starting point of the crystal growth, can be made uniform in a wide range. Therefore, good crystal growth can be achieved in a large area. Further, since the fluorine compound such as CaF ₂ is an insulator, it is possible to electrically completely separate the substrate and the single crystal semiconductor thin film formed by the melt recrystallization, and the device can be placed close to the seed portion. It can also be formed, and restrictions on device arrangement can be reduced. Therefore, when the seed parts are provided at a plurality of positions, the interval between the seed parts can be narrowed, and by this,
It is also possible to suppress the rotation of the crystal axis of the single crystal semiconductor thin film during the melt recrystallization process and reduce the change in the plane orientation within the substrate.

[0028]

EXAMPLES Examples of the present invention will be described below. Example 1 In Example 1, a semiconductor device was manufactured through the steps shown in FIGS. 6A to 6E and FIGS. 7A to 7C. That is, the SiO ₂ thin film 22 having a thickness of 5000 Å is formed on the (100) plane of the single crystal Si substrate 21 by thermal oxidation,
Then, a 1.5 μm wide stripe-shaped opening 24 of 100 μm is formed in the SiO ₂ thin film 22 by photolithography.
It was formed with a pitch (FIG. 6A).

Next, the substrate 21 is dipped in a KOH solution,
By processing the exposed Si portion of the substrate 21, the apex angle is about 110 °.
Forming a V-shaped groove 25 (FIG. 6B). In this state, the substrate 21 was dipped in a hydrofluoric acid solution to terminate the surface of the V-shaped groove 25 and the surface of the SiO ₂ thin film 22 with hydrogen atoms 34 (FIG. 6C). 8 (a) and 8 (b),
The bonding states of hydrogen atoms 34 on the surface of the V-shaped groove 25 and on the surface of the SiO ₂ thin film 22 are shown in more detail. In the figure, reference numeral 35 is a Si atom, and reference numeral 36 is an O atom.

Then, the seed portion of the CaF ₂ / Si laminated structure was selectively grown. Here, the molecular beam epitaxial growth method (MBE method) was used for the growth of Si and CaF ₂ . That is, the substrate was inserted into the MBE apparatus, the growth chamber was evacuated to a back pressure of the order of 10 ⁻¹⁰ (Torr), and then the substrate surface was heated for a short time with an infrared lamp. At this time, since the transmittance of infrared rays is different between the SiO ₂ portion and the Si portion on the substrate surface, the temperature distribution shown in FIG. 9 can be formed on the substrate surface. As a result, the hydrogen atoms 34 on the surface of the V-shaped groove 25, which has a high temperature, are desorbed, and only the hydrogen atoms 34 on the SiO ₂ thin film 22 remain (FIG. 6D).

In this state, the growth of the CaF ₂ layer 23 is started. Since the surface of the SiO ₂ thin film 22 terminated by hydrogen atoms 34 is very inactive, CaF ₂ does not adsorb. Therefore, the CaF ₂ layer 23 selectively grows on the V-shaped groove 25, and as described above, its shape is such that the surface ((111) plane) facing the surface of the V-shaped groove 25 has an apex angle of about 110 °. Reverse V
It becomes a letter shape (Fig. 6 (e)). The height h from the Si substrate 21 to the upper end of the CaF ₂ layer 23 is about 1 μm.
Usually, when a junction between dissimilar materials is formed by the heteroepitaxial growth method, it is affected by the lattice mismatch between the materials, the difference in the coefficient of thermal expansion, and the like, and a slight deviation occurs in the lattice spacing and the like. However, in the growth of the CaF ₂ layer on the (100) plane of the Si substrate, near the interface between the substrate and the CaF ₂ layer,
It is affected by lattice mismatch, but as the growth progresses, it shifts to a more stable structure of CaF ₂ itself. Therefore, the apex angle formed by the (111) facet on the CaF ₂ layer surface can be accurately reproduced.

Next, the Si layer 2 is formed on the CaF ₂ layer 23.
6 ′ is grown using the same MBE apparatus as that for growing the CaF ₂ layer 23 (FIG. 7A). Here, the CaF ₂ layer 23
Surface after growth SiO ₂ film 22, because it is terminated with hydrogen atoms 34, Si layer 26 'is also selectively grown to reflect the inverted V-shaped CaF ₂ layer 23 on the CaF ₂ layer 23 . Here, the film thickness of the Si layer 26 'is 1000 Å.

Next, the polycrystalline Si film 2 is formed on the entire surface of the substrate.
6 is deposited using the CVD (Chemical Vapor Depositon) method (FIG. 7B). The film forming conditions at this time are as follows: the source gas is SiH ₂ Cl / H ₂ , and the film forming temperature is 100.
The film formation pressure was 0 ° C. and 20 Torr. Here, by setting the film forming temperature to 1000 ° C., the hydrogen atoms 34 terminating the surface of the SiO ₂ thin film 22 during the selective growth of the CaF ₂ / Si laminated structure are desorbed. As a result, the polycrystalline Si thin film 26 is deposited on the entire surface of the substrate.

In this way, the polycrystalline Si thin film 26
Deposited to a film thickness of 000Å, and finally SiH ₄ / N ₂ O / H
_After depositing a SiO ₂ film as the protective film 27 with a film thickness of 1 μm by the CVD method using ₂ as a source gas to complete the substrate for melting recrystallization, the polycrystalline Si thin film 26 is used with an argon laser. Melt recrystallization is performed by laser beam annealing (FIG. 7C). Here, the output of the argon laser is 5 W, and the beam diameter of the laser beam 28 is condensed to 50 μm and irradiated on the surface of the substrate, and 5 cm / sec in the direction perpendicular to the seed on the stripe, that is, in the direction of arrow A. The beam scanning was started from the position of the seed portion at the scanning speed of 1 to recrystallize. That is, the polycrystalline Si thin film 26 is melted-
During the solidification process, the crystal information of Si on the CaF ₂ thin film used as a seed was taken over and laterally epitaxially grown. Thus, the semiconductor device of Example 1 was completed. FIG. 10 shows the Si thin film 26 in the semiconductor device of Example 1 manufactured as shown in FIGS. 6A to 6E and FIGS. 7A to 7C from the spread of diffraction spots by electron beam diffraction.
The result of evaluating the distribution of the slope of the [100] axis with respect to the distance from the seed part of is shown. For comparison, S in a conventional semiconductor device manufactured using a Si substrate as a seed is used.
The distribution of the slope of the [100] axis with respect to the distance from the seed portion of the i thin film is also shown. Here, the electron beam was incident on the stripe-shaped seed in the direction perpendicular to the seed, that is, in the [001] direction, and the distribution in the region of 100 mm was measured. Figure 10
As can be seen from the above, in the semiconductor device of Example 1, the tilt angle of the [100] axis of the Si thin film 26 can be made smaller than that of the conventional one, and the tilt angle is ± 1 when the spacing between the seed portions is 100 μm or less. It was possible to make it less than °.

Example 2 In Example 2, FIGS. 11 (a) to 11 (c) and 12 (a) are used.
As shown in (c) to (c), a Ge single crystal thin film was further formed on the Si thin film 26 of the semiconductor device manufactured as in Example 1. That is, first, the Si single crystal thin film 26 is formed by the method according to the first embodiment (FIG. 11).
(A)). Next, the Si single crystal thin film 26 is thermally oxidized.
An SiO ₂ thin film 42 having a thickness of 5000 Å is formed on the SiO ₂ thin film 42, and then a stripe-shaped opening 43 is formed in the SiO ₂ thin film 42 by photolithography to be used as a seed for melting and recrystallization of the Si thin film 26. The exposed CaF ₂ is exposed (FIG. 11 (b)). Here, the width of the opening 43 is 1.
The width is set to 0 μm and is narrower than the width of the opening 24 of the lower insulating layer 22. Further, to expose the CaF _2, but removing the Si thin film 26 on the CaF _2, the removal process, CaF ₂
Wet etching using an etchant having a sufficiently large selection ratio between Si and Si.

Next, Ca _x Sr _1-x F used as a seed
_{The 2} / Ge laminated structure was selectively grown by the same process as in Example 1. That is, after inserting the above substrate into the MBE apparatus and evacuating the growth chamber to a back pressure of the order of 10 ^-10 (Torr), the substrate surface is heated by an infrared lamp for a short time, and S
Hydrogen atoms are left only on the iO ₂ thin film 42. In this state,
The growth of the Ca _x Sr _1-x F ₂ layer 45 is started (FIG. 11).
(C)). That is, the Ca _x Sr _1-x F ₂ layer 45 is
It is formed by supplying the F ₂ raw material and the SrF ₂ raw material from different evaporation sources. At this time, the composition x of the Ca _x Sr _1-x F ₂ layer 45 is set to 0.4 by controlling the temperature of the evaporation source. Here, the shape of the Ca _x Sr _1-x F ₂ layer 45 after growth has an apex angle of about 11 as in the CaF ₂ layer 23 of the first embodiment.
It becomes an inverted V shape with 0 °. Next, the substrate temperature is once set to 80
The temperature is raised to 0 ° C. and hydrogen atoms on the SiO ₂ thin film 42 are removed. After that, the Ge thin film 46 is set to 3 in the same MBE apparatus.
The film is grown to a film thickness of 000Å (FIG. 12 (a)). The Ge thin film 46 epitaxially grows on the Ca _x Sr _1-x F ₂ layer 45 to become a single crystal, and becomes a polycrystalline thin film on the SiO ₂ thin film 42.

Finally, a SiO ₂ thin film 47 having a thickness of 1.0 μm was deposited by a CVD method using SiH ₄ / N ₂ O / H ₂ as a source gas to complete a substrate for melt recrystallization ( FIG. 12B).

Next, the polycrystalline Si thin film 46 is melted and recrystallized by laser beam annealing using an argon laser (FIG. 12 (c)). Here, the output of the argon laser is 1 W
Then, the beam diameter of the laser beam 48 is converged to 100 μm and irradiated onto the substrate surface, and the beam is emitted from the position of the seed portion at a scanning speed of 10 cm / sec in the direction perpendicular to the seed on the stripe, that is, in the direction of arrow A. Was started to recrystallize. That is, the polycrystalline Ge thin film 46 inherits the crystal information of Ge on the Ca _x Sr _{1 -x} F ₂ layer 45 used as the seed in the process of melting and solidifying, and epitaxially grows in the lateral direction.
A single crystal Ge thin film was obtained. In this way, a laminated structure of a plurality of semiconductor thin films could be formed.

[0039]

As described above, according to the first to fourth aspects of the invention, a single crystal semiconductor substrate is formed, and an opening is partially formed on the surface of the single crystal semiconductor substrate. And a fluorine compound formed by epitaxial growth on the surface of the substrate exposed in the opening, and a single crystal semiconductor thin film formed on the fluorine compound and the insulating film. In addition, the design margin of the device can be improved, and the substrate and the single crystal semiconductor thin film can be electrically separated completely, and a good device can be easily obtained.

According to the fifth and sixth aspects of the invention, a V-shaped groove having a predetermined apex angle is formed on the surface of the substrate exposed in the opening, and only the V-shaped groove is selectively formed. Since the fluorine compound of the seed portion is grown and formed on the substrate, the heat environment of the seed portion is adjusted, and in order to improve the design margin of the device, the complicated process and the necessity of using a special substrate are eliminated, and It is possible to electrically and completely separate the substrate and the single crystal semiconductor thin film.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration example of a semiconductor device according to the present invention.

FIG. 2 is a diagram showing a state in which CaF ₂ is grown on a flat Si substrate.

3 (a) and 3 (b) are diagrams for explaining a heat flow in a recrystallization process in manufacturing a semiconductor device according to the present invention and in manufacturing a conventional semiconductor device, respectively.

4A to 4C are diagrams showing an example of a manufacturing process of a single crystal silicon thin film according to the present invention.

5A to 5C are diagrams showing an example of a manufacturing process of a single crystal silicon thin film according to the present invention.

6A to 6E are views showing a manufacturing process of the semiconductor device of the first embodiment.

7A to 7C are diagrams showing the manufacturing process of the semiconductor device of the first embodiment.

8A and 8B are SiO ₂ on the surface of a V-shaped groove.
It is a figure which shows the bonding state of the hydrogen atom on the thin film surface.

9 is a diagram showing a temperature distribution on the substrate surface when the substrate surface is heated for a short time by an infrared lamp in the manufacturing process of FIG.

FIG. 10 is a tilt of the [100] axis with respect to the distance from the seed portion of the Si thin film in the semiconductor device of Example 1 manufactured by the steps of FIGS. 6A to 6E and FIGS. 7A to 7C. It is a figure which shows the evaluation result of distribution.

11A to 11C are views showing a manufacturing process of the semiconductor device according to the second embodiment.

12A to 12C are views showing a manufacturing process of the semiconductor device according to the second embodiment.

FIG. 13 is a diagram showing a conventional SOI structure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Single crystal semiconductor substrate 2 Insulating film 3 Fluorine compound 4 V-shaped groove 5 Si thin film 6 Semiconductor device 7 Protective film 10 Opening

Claims (6)

[Claims] 1. A single crystal semiconductor substrate, an insulating film formed on the surface of the single crystal semiconductor substrate, and an epitaxial growth on the surface of the substrate exposed in an opening provided in a part of the insulating film. A semiconductor device comprising: a fluorine compound formed by the method described above; and a semiconductor thin film formed on the fluorine compound and an insulating film. 2. The semiconductor device according to claim 1, wherein the single crystal semiconductor substrate and the semiconductor thin film are made of Si, Ge,
A semiconductor device comprising at least one of GaAs, InP, and GaP. 3. The semiconductor device according to claim 1, wherein the fluorine compound contains at least one element of Ca, Sr, and Ba. 4. The semiconductor device according to claim 1, wherein the fluorine compound has an inverted V-shape having an apex angle in the range of 100 to 120 °. 5. An insulating film having a partial opening is formed on a single crystal semiconductor substrate, and two layers of a fluorine compound layer and a semiconductor layer are formed on the surface of the substrate exposed at the opening of the insulating film. At least the seed portion having the seed portion is selectively epitaxially grown, and a polycrystalline or amorphous semiconductor thin film is deposited on the entire substrate including the seed portion, and the semiconductor layer of the seed portion is used as a seed crystal by a laser beam or an electron beam. A method for manufacturing a semiconductor device, wherein a single crystal semiconductor thin film is obtained by melting and recrystallizing the thin film. 6. The method of manufacturing a semiconductor device according to claim 5, wherein a V-shaped groove having a predetermined apex angle is formed on the surface of the substrate exposed in the opening, and only the V-shaped groove is selectively formed. A method of manufacturing a semiconductor device, wherein the fluorine compound layer of the seed portion is grown and formed on.