JPH07230952A - Recrystallizing method - Google Patents

Abstract

PURPOSE:To obtain a stable fused region of a semiconductor layer when the semiconductor layer (semiconductor thin film) is formed on an insulating substrate, and to effectively prevent the generation of defects on a recrystallized semiconductor layer. CONSTITUTION:A polycrystalline, to be single crystallized, or amorphous semiconductor layer (semiconductor thin film) 2 is formed on an insulated substrate 1, and a surface protecting film 3 is formed on the semiconductor layer (semiconductor thin film) 2. At this point, the semiconductor layer 2 has the pattern having the microscopic pits 4 scattered therein. In the above-mentioned pattern, as the boundary between the surface protecting film 3 on the pattern side face and the semiconductor layer (semiconductor thin film) 2 is very small and the boundary is not formed continuously, the stress of fixed direction is not added. As a result, the generation of the defects such as twin crystals can be suppressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recrystallization method for recrystallizing a semiconductor thin film on an insulating substrate, which is used for large current devices, high breakdown voltage devices, radiation resistant devices, three-dimensional devices and the like.

[0002]

2. Description of the Related Art In the technology for forming a single crystal semiconductor thin film on an insulating substrate (SOI technology), the SOI structure is characterized by its structural features such as reduction of parasitic capacitance, complete isolation of elements, and three-dimensional structure. It has been actively researched in recent years because it is possible to deal with it, and it is expected that the device will have higher speed, higher integration, and higher functionality.

As a method of forming a single crystal semiconductor thin film on an insulating substrate, as shown in FIG.
After a polycrystalline or amorphous semiconductor thin film 102 is formed on 1, various heating methods (laser heating, carbon strip heater heating, halogen lamp heating, electron beam heating, high frequency heating using a carbon susceptor, etc.) are used. ,
The semiconductor thin film 10 is scanned by scanning the heating source or the substrate 101.
A method of continuously melting and recrystallizing 2 to form a single crystal is used.

At this time, in order to perform stable melting and recrystallization, a surface protective film 103 is generally formed on the semiconductor thin film 102. In addition, it is conceivable to widen the melting region of the semiconductor thin film 102 in order to improve the processing capacity. However, in the state where the surface protection film 103 only covers the wide melting region, the fluctuation of the melt cannot be sufficiently suppressed, and as shown in FIG. 15, the obtained single crystal semiconductor thin film (recrystallized Irregular surface irregularities are formed on the surface of the oxide film) 102 ', and the melted region pops off, resulting in the semiconductor thin film 10'.
There may be a bead-up phenomenon in which 2'has a hole.
In this case, when a device or the like is formed on the obtained single crystal semiconductor thin film 102 ′, there arise problems such as variations in the characteristics of the device or the like and a decrease in yield.

In order to avoid such a problem, for example, as disclosed in JP-A-59-229815, a semiconductor layer (semiconductor thin film) of Si is formed in a plurality of regions on an insulating substrate.
It is conceivable that the semiconductor layers (semiconductor thin films) formed in the shape of islands are connected to each other and melted and recrystallized. FIG. 16 shows a semiconductor layer (semiconductor thin film) 202 on an insulating substrate 101 in a stripe pattern,
Alternatively, it is a diagram showing a case of forming a connected island-shaped pattern as in the above document, and by patterning the semiconductor layer (semiconductor thin film) in this way,
The melted area is regularly divided into smaller parts, and the surface protection film is also divided into melted areas so that fluctuations in the melt can be effectively suppressed, preventing irregular surface shape irregularities and bead-ups. can do.

[0006]

However, as shown in FIG.
When patterning the semiconductor layer (semiconductor thin film) as shown in (3), a new problem arises that internal stress is generated according to the pattern of the semiconductor layer (semiconductor thin film). That is, when the semiconductor layer (semiconductor thin film) is patterned in some shape, the volume change during recrystallization (solidification) of the semiconductor thin film at the boundary between the surface protective film on the pattern side and the semiconductor layer (semiconductor thin film). Is generated in the direction perpendicular to the boundary surface, and in a pattern that is connected in a stripe shape or a connected island shape, stress in a fixed direction is continuously applied along the side surface of the pattern. There arises a problem that defects such as the above are likely to occur.

According to the present invention, when a semiconductor layer (semiconductor thin film) is formed on an insulating substrate and the semiconductor layer (semiconductor thin film) is melted and recrystallized, a stable molten region of the semiconductor layer (semiconductor thin film) is obtained. It is an object of the present invention to provide a recrystallization method capable of realizing the above and effectively preventing the occurrence of defects in the semiconductor layer (semiconductor thin film) after recrystallization.

[0008]

In the recrystallization method of the present invention, first, a semiconductor material substrate having a layer structure as shown in FIG. 1 is formed. That is, in the example of FIG. 1, a polycrystalline or amorphous semiconductor layer (semiconductor thin film) 2 to be single-crystallized is formed on an insulating substrate 1 which is a support, and this semiconductor layer (semiconductor thin film) is formed. The surface protection film 3 is formed on the surface 2. Here, as the insulating substrate 1, in addition to an insulating substrate having heat resistance such as quartz glass or ceramic, a substrate on which an insulating material such as SiO ₂ or Si ₃ N ₄ is formed on the surface of metal or semiconductor is used. Can also be used. The insulating substrate 1 usually has a thickness of about 0.3 to 3.0 mm.

The polycrystalline or amorphous semiconductor layer (semiconductor thin film) 2 to be single-crystallized is, for example, Si,
It is formed by forming a semiconductor material such as Ge into a film having a thickness of about 0.1 to 3.0 μm by a film forming method such as various CVD methods, a vacuum evaporation method, and a sputtering method.

At this time, in the present invention, as shown in more detail in FIG. 2, a plurality of hole-shaped fine defect portions (hereinafter referred to as pits) 4 are formed in the semiconductor layer (semiconductor thin film) 2. Note that FIG. 2 is a cross-sectional view of the semiconductor layer (semiconductor thin film) 2 of FIG. 1 taken along the line BB. Such a pit 4
Can be formed by using a normal photolithography process. Regarding the interval between the pits 4, the semiconductor layer (semiconductor thin film) is formed in the process of melting and recrystallization of the semiconductor layer (semiconductor thin film) 2 (during heating). At intervals such that at least one pit 4 is included in the molten region 6 formed in 2 (more specifically, at an interval of about 500 μm or less in the molten region 6 formed during heating). ), Preferably formed so that they are adjacent.

The surface protective film 3 is formed on the semiconductor layer (semiconductor thin film) 2 formed as described above, for example, by S.
Insulating thin films such as iO ₂ and SiN are formed by various CVD methods, vacuum deposition methods, sputtering methods, etc.
It is formed by forming a film with a certain thickness.

FIG. 3 is an enlarged view (partially enlarged view of FIG. 1) when the surface protective film 3 is formed on the semiconductor layer (semiconductor thin film) 2 having a plurality of pits 4. As can be seen from FIG. 3, since the semiconductor layer (semiconductor thin film) 2 has the pits 4, the surface protective film 3 is directly formed on the surface of the insulating substrate 1 at that portion. As a result, the surface protective film 3 has a structure in which it is fixed to the surface of the insulating substrate 1 at intervals of about 500 μm or less.

Thereafter, the semiconductor material substrate thus formed is heated by laser heating, carbon strip heater heating, halogen lamp heating, high frequency heating, etc.,
While heating the semiconductor layer (semiconductor thin film) 2, the heating source or the substrate 1 is relatively scanned at a scanning speed of about 0.1 mm / sec to 10 mm / sec. In this case, with the structure as described above, the surface protection film 3 on the molten region 6 of the semiconductor layer (semiconductor thin film) 2 is fixed to the substrate 1 during heating, and the melt of the semiconductor layer (semiconductor thin film) 2 is melted. Is the surface protective film 3
As a result, fluctuations (fluctuations) can be suppressed, irregular irregularities on the surface and bead up can be significantly reduced, and a stable melting region can be realized.

When the semiconductor layer (semiconductor thin film) is patterned in some shape, as described above, at the boundary between the surface protective film on the side surface of the pattern and the semiconductor layer (semiconductor thin film), recrystallization (solidification) occurs. ) The stress due to the volume change is generated in the direction perpendicular to the boundary surface, and in a continuous pattern such as a stripe shape or a connected island shape, as described above, a constant direction is continuously applied along the side surface of the pattern. Stress is applied, and defects such as twins are likely to occur. On the other hand, in the present invention, the pattern is such that the fine pits 4 are scattered in the semiconductor layer (semiconductor thin film) 2. In such a pattern, the surface protective film 3 on the side surface of the pattern and the semiconductor layer (semiconductor layer) Since the boundary with the thin film 2 is minute and not continuous, stress in a fixed direction is not continuously applied. This makes it possible to suppress the occurrence of defects such as twins.

As described above, according to the present invention, when the semiconductor layer (semiconductor thin film) 2 is continuously recrystallized, the surface roughness and the beat-up are small, and further, the number of defects is small. A crystalline semiconductor thin film) can be obtained.

In this specification, the terms "semiconductor layer" and "semiconductor thin film" are used as the same meaning, that is, synonyms.

[0017]

EXAMPLES Examples of the present invention will be described below. (Embodiment 1) FIG. 4 is a view showing the layer structure of the substrate used in Embodiment 1. In Example 1, the insulating substrate 1 which is a support
As the substrate 1, a quartz substrate having a thickness of 500 μm is used.
As the semiconductor layer (semiconductor thin film) 2, a polycrystalline Si film 2 was formed thereon by LP-CVD to a film thickness of 3300Å. After that, by a normal photolithography process,
As shown in more detail in FIG. 5, square pits 4a each having a side of 10 μm were formed in the polycrystalline Si film 2 so as to be adjacent to each other within a distance of 300 μm in the melting region 6 formed during heating. Note that FIG. 5 is a cross-sectional view taken along the line CC of FIG. Next, as the surface protection film 3, a SiO ₂ film having a thickness of 1.3 μm was formed as a surface protection film 3 on the thus patterned polycrystalline Si film 2.

Further, as a semiconductor layer (semiconductor thin film) 2, for comparison with the semiconductor material substrate thus prepared,
As shown in FIGS. 6A and 6B, a substrate using a polycrystalline Si film 22 having the same material, film forming method, film thickness, etc., but not patterned (FIG. 6A) And the width x is 1
A substrate (FIG. 6B) using a polycrystalline Si film 32 patterned into a stripe-shaped pattern 30 of 00 μm and an interval y of 10 μm was prepared.

A laser heating method is applied to the substrate of Example 1 (the substrate having the pits 4 formed in the polycrystalline Si film 2) formed as described above by a laser heating apparatus as shown in FIG. Then, the polycrystalline Si film 2 was melted and recrystallized. At this time, the laser 6 of this laser heating device
As 01, an Ar laser having a beam diameter of 1.5 mm and an output of 10 W is used. A laser beam from the laser 601 is reflected by a mirror 602 so as to be vertically incident on a substrate 605 placed on a uniaxial table 607, and a beam expander 603 is provided. The beam diameter is expanded 10 times by the
With the cylindrical lens 604, the beam has a long axis 1
The substrate 605 was irradiated with the light by narrowing it down to an ellipse having a length of 5 mm and a minor axis of 4 mm. The whole substrate 605 is a ceramic heater 606.
The substrate 605 was scanned by bias heating to 500 ° C. above and moving the uniaxial table 607 at a scanning speed of 0.1 mm / sec in the short axis direction of the laser beam.

As a result, the polycrystalline Si film 2 of Example 1 was
As shown in FIG. 8, the major axis 10 mm and the minor axis 0.7 mm are melted in a shape close to an ellipse 702, and a width of 10 m is obtained by scanning.
The recrystallized Si film 2'of m was continuously obtained.

Unpatterned polycrystalline Si film 22
And a substrate using a polycrystalline Si film 32 patterned in a stripe shape (FIG. 6A).
Also for (b)), recrystallization was performed by the same method. In addition, polycrystalline Si patterned in a stripe shape
In the substrate using the film 32, the major axis direction of the laser beam is
A laser beam was irradiated so as to be orthogonal to the longitudinal direction Z of the stripe, and the substrate was scanned along the longitudinal direction Z of the stripe.

The following table (Table 1) compares the recrystallized films 2, 22, 32 with respect to the surface shape of the film, the presence or absence of bead-up, and the morphology of defects.

[0023]

[Table 1]

In Table 1, regarding the surface shape, after removing the surface protective film (SiO ₂ film) 3 with a hydrofluoric acid-based etching solution, the surface of the recrystallized film was measured using a stylus type surface shape measuring device. The unevenness is measured, and the ratio of the difference between the maximum value and the minimum value to the film thickness of the polycrystalline film Si before recrystallization is shown. As a result, polycrystalline Si without patterning
In the substrate using the film 22, irregularities of up to 8% were irregularly formed over the entire recrystallized film, whereas in the substrate using the polycrystalline Si film 2 having the pit pattern of Example 1, The maximum unevenness was as small as 3%. Further, in the substrate having the stripe-patterned polycrystalline Si film 32, the shape of the unevenness was almost the same for each stripe, and the height was higher in the central portion of each stripe, but the difference was as large as about 12%. It was found that the unevenness was larger than that of the recrystallized film on the substrate using the uncoated polycrystalline Si film 22 or the substrate using the polycrystalline film 2 having the pit pattern.

Further, in the case of a substrate using the polycrystalline Si film 32 having a stripe pattern, the 12% unevenness is 100%.
While the value is for a stripe having a width of μm, the unevenness of 8% without patterning is the value for a melting width of 10 mm. Therefore, from this, the gradient of the unevenness is also the stripe pattern of the polycrystalline Si film 32. It was found that the substrate using was larger.

When the film thickness is uneven, the electrical characteristics of the device vary depending on the place where the device is formed. Therefore, it becomes necessary to perform a surface flattening process such as lapping or etch back. When such a surface flattening process is performed, the poorer the flatness, the more the time and the number of times increase, and the Si film also deviates from the set value. It is desirable that the surface irregularities be as small as possible. From this point, it was found that the substrate using the polycrystalline Si film 2 having the pit pattern of Example 1 is the best.

9 (a) and 9 (b) are the unpatterned polycrystalline Si thin film 22 of FIG. 6 (a), respectively.
Recrystallized into a central region (region having a width w of about 10 mm and a length l of 100 mm) A of the substrate using the substrate and the substrate using the polycrystalline Si thin film 2 in which the pit pattern of Example 1 was formed. It is a figure which shows typically the state in which Si thin film 22 ', 2'is formed. As can be seen from FIGS. 9 (a) and 9 (b), the bead-ups 53 and 13 occur when the Si thin film is not patterned or when the pit pattern is formed. Both are different.

That is, in the substrate in which the Si thin film is not patterned (FIG. 9A), 3 in the recrystallization region A is used.
The bead-ups 53 are generated at the locations, and in each of the bead-ups 53, Si is popped off over the substantially entire width w of the melted region A at the location where the bead-ups 53 occur. On the other hand, in the substrate in which the pits are formed on the Si thin film (FIG. 9B), there are two bead-ups 13 in the same area A.
However, it has not expanded further beyond the pit,
It does not fall out over the width w of the entire melting region. As described above, the number of bead-up occurrences is smaller and the size thereof is smaller in the substrate in which the pits are formed.

The occurrence of bead-up is largely due to the fluctuation of the heat source and the rapid fluctuation of the melt due to foreign matter such as dust in the film, and the surface protective film 3 is fixed to the substrate at the pit. It has been found that increasing the strength is effective in suppressing this. Furthermore, these results show that the presence of pits also has the effect of preventing the bead-up from expanding even if it occurs. No bead up occurred in the Si thin film of FIG. 6 (b) in which the Si thin film was patterned in a stripe shape.

Further, when the morphology of crystal defects was compared by microscope observation, it was found that the substrate using the polycrystalline Si film 2 having the pit pattern of Example 1 and the polycrystalline Si of FIGS. 6 (a) and 6 (b). Any of the substrates using the films 22 and 32 has a sub-grain bandary 901 as shown in FIG.
However, in addition to being observed throughout the recrystallized Si film with an average interval of about 10 μm, grain boundary was also observed near the boundary with the polycrystalline Si film.

In the substrate using the Si thin film 2 having the pit pattern of Example 1, cracks 903 were observed in the Si thin film at a length of several μm from the corner of the square pit 4a. It is considered that this is because the internal stress of the Si thin film due to the difference in thermal expansion coefficient between Si and SiO ₂ was concentrated at the corner of the pit, but it is local and the length is short, so avoid that part. If a recrystallized film is used, there is no particular problem.

On the other hand, in the substrate using the polycrystalline Si film 32 patterned in the stripe shape as shown in FIG. 6B, the linear defect 905 is almost parallel to the stripe pattern 30 as shown in FIG. Are formed,
This defect 9 was observed by a transmission electron microscope.
It was found that 05 was twinned. Twin formation is Si
It is considered that when the thin film is patterned in a stripe shape, a compressive stress due to a large volume expansion of 9% at the time of solidification is continuously applied from a fixed direction along the pattern side surface at the boundary between SiO ₂ and Si on the pattern side surface. To be The portion where the twin crystal is formed has a different electric property of the film from the portion where the sub-grain boundary is formed, which causes variations in device characteristics. Therefore, it is necessary to suppress the occurrence thereof as much as possible. In the substrate using the unpatterned polycrystalline Si film 22 of FIG. 6A and the substrate using the pit-patterned polycrystalline Si film 2 of the first embodiment, a continuous pattern is formed in a certain direction. Since no stress was applied from the surface, twinning was not observed.

As described above, the quality of the recrystallized film (surface irregularities, bead-ups, defects) is summarized for the substrate not patterned with the Si thin film, the substrate patterned with stripes, and the substrate using the polycrystalline Si film with pits formed. As can be seen from Table 1, the substrate of Example 1 in which the pits were formed had the smallest surface irregularities, no twin formation due to stress was observed, and the bead-up also occurred at two locations. It is the most advantageous semiconductor substrate for device formation because it is possible to eliminate it by only optimizing the size and spacing of pits, since there are only minute ones. .

Example 2 In Example 2, as in Example 1, LP-PVD was formed on a quartz substrate having a thickness of 500 μm.
After forming the polycrystalline Si thin film 2 with a thickness of 3300Å by the method, a square pit 4a having a side of 10 μm is formed on the polycrystalline Si thin film 2 by a normal photolithography process.
Were randomly formed such that the distance between them was 600 μm in the melting region even at the maximum. Then, a SiO ₂ film as a surface protection film 3 is formed thereon by LP-CVD to 1.3
It was formed to a thickness of μm. When this semiconductor material substrate was melted and recrystallized by a laser beam in the same manner as in Example 1, the surface unevenness was about 8%, and no significant improvement was observed as compared with the case without a pit pattern. . Therefore, the pit pattern interval is 100
The same recrystallization was carried out for the materials which were changed by 100 μm from μm to 1 mm. The following table (Table 2)
As shown in, when the distance is about 500 μm or less,
It was found that the surface irregularities were greatly improved.

[0035]

[Table 2]

(Embodiment 3) In Embodiment 3, as in Embodiments 1 and 2, the substrate having the layer structure shown in FIG. 1 was used. However, in Embodiment 3, a circular pit pattern is used instead of a square. Was formed on the polycrystalline Si film 2. That is, first, as in the first and second embodiments, the substrate 1 having a thickness of 500 is formed.
A polycrystalline Si thin film having a thickness of 3300 Å was formed on the substrate 1 by a LP-CVD method using a quartz substrate of μm. After that, by a normal photolithography process,
As shown in FIG. 12, the polycrystalline Si thin film 2 has a diameter of 10 μm.
The circular pits 4b were randomly formed so that the distance between them was about 500 μm or less in the melting region even at the maximum distance.

Next, on the polycrystalline Si thin film 2 having the pits 4b formed in this manner, SiO ₂ as a surface protective film 3 is formed.
The film was formed to a thickness of 1.3 μm by the LP-CVD method. Next, the semiconductor material substrate thus formed is irradiated with a laser beam in the same manner as in Examples 1 and 2, and the substrate is relatively scanned to cause polycrystalline S
The i thin film 2 was melted and recrystallized.

With respect to the Si melt recrystallized film thus obtained, the surface irregularities of the film, the presence or absence of bead-up, and the morphology of defects were evaluated. The evaluation results almost equal to those of the substrate in Example 2 were obtained, and in the case where the pits were square, no minute cracks were found at the corners of the pits.

(Embodiment 4) Similar to Embodiment 3, a polycrystalline Si thin film 2 is formed on a quartz substrate 1, circular pits 4b are formed in this polycrystalline Si thin film 2, and then a SiO ₂ film is formed on the surface. In Example 4, the circular pits 4b had a diameter of 100 μm, and the intervals between the pits 4b were about 500 μm to 300 μm in the melting region. The polycrystalline Si thin film on this substrate was melted and recrystallized in the same manner as in Example 1.

The film quality of the recrystallized film obtained here was evaluated from the same viewpoint as in Example 1. As a result, the surface shape was disturbed around each pit, and the surface unevenness was as large as 10%. . When the pit size and the pit interval were examined, as shown in the following table (Table 3), the pit size (diameter) was the minimum distance between adjacent pits (that is, the distance between the closest hole-like fine defect portions). 30 in the example of Table 3
Is about 1/10 or less of (0 μm)
It was found that there was almost no disturbance in the surface shape around the pit.

[0041]

[Table 3]

The irregularities in the surface shape around the pits cause the pits to become obstacles to the Si melt during the movement of the melted area due to the substrate scanning. Therefore, if the pit diameter is large,
It is considered that this occurs because the melt is disturbed, and by making the size of the pit smaller than a circle whose diameter is about one-tenth of the distance between the minimum adjacent pits, the pit does not move In this case, it does not become a major obstacle, and therefore, the disorder of the surface unevenness of the obtained single crystal semiconductor thin film around the pit can be reduced without disturbing the melt.

(Embodiment 5) In Embodiment 5, as in Embodiment 1, a polycrystalline Si thin film 2 is formed on a quartz substrate 1, square pits 4a are formed, and then a SiO ₂ film 3 is formed on the surface. However, in Example 5, the arrangement of the pits 4a was not random, but was 500 μm on each side as shown in FIG.
Are arranged at the lattice positions of.

In the Si melt recrystallized film obtained by melting and recrystallizing the polycrystalline Si thin film of the semiconductor material substrate thus formed in the same manner as in Example 1, the pit positions are regular in a certain direction. Since the Si melt recrystallized film region is continuous in a certain direction, it is advantageous in device design.

Example 6 The same semiconductor thin film material substrate as in Example 1 was placed in a vacuum chamber having a laser introduction window, and the same melt recrystallization was performed in a reduced pressure atmosphere of 2 × 10 ⁻⁴ Torr. As a result, the surface roughness of the obtained Si recrystallized film was 2%, which was smaller than that in the air atmosphere. This is because the substrate surface suffers severe heat loss due to convection when melt recrystallization is performed in the atmosphere.
This unstable heat circulation causes a large fluctuation of the Si melt, so the surface shape of Si is disturbed, but a stable molten state is realized by creating a depressurized atmosphere that is not affected by heat loss due to convection. It is thought to be because.

[0046]

As described above, according to the first aspect of the present invention, the semiconductor material substrate in which the semiconductor thin film and the surface protective film are sequentially formed on the insulating substrate is heated and scanned to obtain the semiconductor. When the thin film is melted and recrystallized, the semiconductor thin film is provided with a plurality of hole-shaped fine defect portions at predetermined intervals in the melting region at the time of heating, and the surface protective film is formed in the melting region. Since there is one or more portions fixed to the substrate and structurally reinforces the surface protective film, it is possible to effectively suppress the fluctuation of the melt, and to obtain the surface of the obtained single crystal semiconductor thin film. It is possible to reduce unevenness and prevent bead-up. Further, in a pattern in which fine defect portions are scattered, a continuous constant pattern along the side surface of the pattern due to a change in deposition during solidification, as in the case of a continuous pattern in which a semiconductor thin film is stripe-shaped or island-shaped, is connected. Since no directional stress is applied, the occurrence of defects such as twins can be suppressed.

Further, according to the second aspect of the present invention, since the shape of the fine defect portion is circular, there is no corner where stress concentrates in the fine defect portion, and therefore the occurrence of cracks can be prevented. .

According to the third aspect of the present invention, the size of the fine defect portion is smaller than a circle having a diameter of about 1/10 of the distance between the closest hole-like fine defect portions. As a result, the fine defect portion does not become a major obstacle during the movement of the melt, and therefore the melt is not disturbed, and the disturbance of the surface irregularities of the obtained single crystal semiconductor thin film around the fine defect portion is small. can do.

In the invention according to claim 4, since the plurality of hole-shaped fine defect portions are arranged at the lattice positions, the single crystal semiconductor thin film can be continuously obtained in a certain direction.
If a device is to be formed there, it is advantageous in design.

Further, in the invention described in claim 5, since the melting and recrystallization steps are carried out in a reduced pressure atmosphere, there is no heat disturbance due to convection near the surface of the substrate, and thus the melt is formed. It is possible to stabilize and further reduce the unevenness of the surface of the obtained single crystal semiconductor thin film.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a semiconductor material substrate of the present invention.

2 is a cross-sectional view of the semiconductor material substrate of FIG. 1 taken along the line BB.

3 is a partially enlarged view of the semiconductor material substrate of FIG.

4 is a vertical sectional view of a semiconductor material substrate used in Example 1. FIG.

5 is a cross-sectional view taken along line CC of the semiconductor material substrate of FIG.

FIG. 6 is a configuration diagram of a semiconductor layer of a semiconductor material substrate used for comparison with the semiconductor material substrate of the present invention.

FIG. 7 is a diagram showing a configuration example of a laser heating device.

FIG. 8 is a diagram for explaining the state of melting and recrystallization according to the present invention.

FIG. 9 is a diagram showing a result of occurrence of bead up.

FIG. 10 is a diagram showing a result of occurrence of subgrain boundary.

FIG. 11: Polycrystalline S patterned in stripes
It is a figure which shows the linear defect which arose in the i film.

FIG. 12 is a cross-sectional view of a semiconductor layer of a semiconductor material substrate used in Example 3.

FIG. 13 is a diagram showing a state in which pits are arranged at lattice positions.

FIG. 14 is a diagram showing a configuration example of a conventional semiconductor material substrate.

FIG. 15 is a view of melting the semiconductor layer of the semiconductor material substrate of FIG.
It is a figure which shows the state recrystallized.

FIG. 16 is a diagram showing another configuration example of the conventional semiconductor material substrate to be recrystallized.

[Explanation of symbols]

 1 Insulating Substrate 2 Semiconductor Layer (Semiconductor Thin Film) 3 Surface Protection Film 4 Fine Defects (Pits) 6 Melting Area

Claims (5)

[Claims] 1. A recrystallization method of melting and recrystallizing the semiconductor thin film by heating and scanning a semiconductor material substrate in which a semiconductor thin film and a surface protective film are sequentially formed on an insulating substrate. In the recrystallization method, a plurality of hole-shaped fine defect portions are provided at a predetermined interval in the melting region during heating scanning. 2. The recrystallization method according to claim 1, wherein
The recrystallization method is characterized in that each of the fine defect portions has a circular shape. 3. The recrystallization method according to claim 1, wherein
The size of each of the fine defect portions is smaller than a circle having a diameter of about 1/10 of the distance between the closest hole-like fine defect portions. . 4. The recrystallization method according to claim 1, wherein
The recrystallization method, wherein each of the fine defect portions is arranged at a lattice position. 5. The recrystallization method according to claim 1, wherein
A recrystallization method characterized in that the melting and recrystallization are performed in a reduced pressure atmosphere.