JP2000150377A - Manufacture of semiconductor film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the manufacture of a semiconductor film capable of obtaining a high quality of semiconductor film such as a unidirectional growth polycrystalline semiconductor film or a single crystalline semiconductor film or the like at low cost. SOLUTION: This is the manufacture of a semiconductor film which applies a pulse beam 102 on a nonsingle crystalline semiconductor film 101 by scanning the nonsingle crystalline semiconductor film 101 made in the shape of an island having a constriction 101a at its one part with the pulse laser beam. At this time, the pointed end angle of the constriction 101a is 40-80 deg., and the beam profile in the direction of scanning of the above beam 102 has a region at or above the threshold for fine crystallization of a polycrystalline semiconductor film, and the absolute value of the energy density gradient at the threshold for fine crystallization of the latter half of the beam in the progress direction of the above scanning is 20-2000 J/cm3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor thin film including a step of irradiating a non-single-crystal semiconductor thin film with a pulsed laser beam (hereinafter, also referred to as a pulsed laser beam) to anneal the semiconductor thin film. The present invention relates to a laser annealing process for forming an active layer of a polycrystalline or single crystal silicon thin film transistor formed on an insulating substrate such as a display or a contact image sensor.

[0002]

2. Description of the Related Art At present, the development of thin film transistors (TFTs) using a polycrystalline silicon thin film as an active layer formed on a glass substrate for the purpose of application to a liquid crystal display device, a contact type image sensor, and the like has been actively developed. Is underway. As a method for producing a polycrystalline silicon thin film, from the viewpoint of lowering the process temperature and improving the throughput, the silicon thin film once formed as a precursor is irradiated with an ultraviolet pulse laser beam to cause crystallization through melting. Laser annealing, which forms a polycrystalline structure, is becoming mainstream. As a laser irradiation method, from the viewpoint of throughput, a method of irradiating pulse laser light shaped into a long linear beam while scanning in the beam width direction (hereinafter, also referred to as scanning) is widely used.

Further, in order to improve the characteristics of polycrystalline silicon TFTs, particularly the mobility of electrolytic effect, a method of forming a unidirectionally grown polycrystalline silicon thin film in which the position of a crystal grain boundary is controlled has been actively developed. For example, MRS Bulletin Volume 21 (1996
), March, p. 39, as disclosed by Im et al.
By irradiating an island-shaped amorphous silicon thin film with an extremely fine linear beam with a width of 5 μm, it is possible to form a unidirectionally grown polycrystalline silicon thin film with crystal grain boundaries almost aligned in parallel. . By using a fine line beam, for example, IEICE Technical Report SDM92-112 (1992), the heterogeneity of the crystal structure in the pulsed laser light scanning irradiation method as disclosed by Nada et al. On page 53 , Can be avoided.

[0004]

However, even in the case of a unidirectionally grown polycrystalline silicon thin film, the field effect mobility is inferior to that of a single crystal because of the presence of grain boundaries. Also, when using a fine beam, it is necessary to improve the resolution of the optical system. At this time, the cost of the optical system increases, the depth of focus of the optical system decreases, and the efficiency of using laser light. Is reduced.

Other techniques for obtaining a single crystal semiconductor thin film include, for example, those disclosed in Japanese Patent Application Laid-Open No. 57-113267 and
A technique for heating an island-shaped semiconductor thin film having a constricted shape, such as -66840, is disclosed. However, since these heat treatments using a heater or a CW laser are performed, there is a problem that the substrate temperature increases and an inexpensive glass substrate cannot be used. Further, there is a problem that a grain boundary is generated depending on the moving speed of the heat source and the sharp angle of the constricted portion.

The present invention has been made in view of the above-mentioned circumstances, and is intended to manufacture a semiconductor thin film capable of obtaining a high-quality semiconductor thin film such as a unidirectionally grown polycrystalline semiconductor thin film or a single crystal semiconductor thin film at low cost. The purpose is to provide a method.

[0007]

To achieve the above object, the present invention employs the following constitution. The method for manufacturing a semiconductor thin film according to claim 1, wherein the non-single-crystal semiconductor thin film formed in an island shape having a constricted portion at least in part is irradiated with a pulse laser beam to scan the non-single-crystal semiconductor thin film. A method of manufacturing a semiconductor thin film, wherein the peak angle of the constricted portion is 40 to 80 degrees, the beam profile in the scanning direction of the beam has a region equal to or more than the microcrystallization threshold of the polycrystalline semiconductor thin film. The absolute value of the energy density gradient at the microcrystallization threshold in the latter half of the beam with respect to the scanning direction is 20 to 2000 J / cm ³ .

According to a second aspect of the present invention, there is provided a method of manufacturing a semiconductor thin film, comprising: applying a pulse laser beam to a non-single-crystal semiconductor thin film via a light-transmitting insulating thin film having at least a part having a constricted portion; A method for manufacturing a semiconductor thin film, which irradiates the non-single-crystal semiconductor thin film by scanning, wherein a pointed angle of the constricted portion is 40 to 80 degrees, and a beam profile in a scanning direction of the beam is a polycrystalline semiconductor thin film. wherein the of a fine crystallization above threshold region, the absolute value of the energy density gradient of a microcrystalline threshold beam rear half portion with respect to the traveling direction of the scanning is 20~2000J / cm ³ And

According to a third aspect of the present invention, there is provided a method of manufacturing a semiconductor thin film, wherein an island-shaped non-single-crystal semiconductor thin film having at least a part of a constricted portion is oscillated from different light sources.
The first and second pulse laser beams are scanned in the width direction of the beam and irradiated by using a double pulse method of sequentially irradiating the same first pulse laser beam and second pulse laser beam to the same spot. A method of manufacturing a semiconductor thin film, wherein a peak angle of the constricted portion is 40 to 80 degrees, and a beam profile in a scanning direction of the first pulsed laser beam is equal to or more than a microcrystallization threshold of the polycrystalline semiconductor thin film. And the absolute value of the energy density gradient at the microcrystallization threshold in the latter half of the beam with respect to the scanning direction is
20 to 2000 J / cm ³ , wherein the maximum energy density of the second pulse laser beam is equal to or less than the maximum energy density of the first pulse laser beam.

According to a fourth aspect of the present invention, there is provided a method for manufacturing a semiconductor thin film, wherein a non-single-crystal semiconductor thin film is oscillated from a different light source into an island-shaped light-transmitting insulating thin film having at least a portion having a constricted portion. Using a double pulse method of sequentially irradiating two types of first pulse laser beam and second pulse laser beam to the same spot, the pulsed laser beam is scanned in the width direction of the beam to irradiate the semiconductor thin film. In the manufacturing method, a sharp angle of the constricted portion is 40 to 80 degrees, and a beam profile in a scanning direction of the first pulsed laser beam has a region equal to or larger than a microcrystallization threshold of the polycrystalline semiconductor thin film. The absolute value of the energy density gradient at the microcrystallization threshold in the latter half of the beam in the scanning direction is 20 to 2000 J / cm ³ , and the maximum energy density of the second pulsed laser beam is The degree is not more than the maximum energy density of the first pulsed laser beam.

According to a fifth aspect of the present invention, in the method of manufacturing a semiconductor thin film according to the third or fourth aspect, the beam profile of the second pulsed laser beam in the scanning direction is polycrystalline. A position having a region equal to or larger than the microcrystallization threshold value of the semiconductor thin film, and a position where the microcrystallization threshold value of the second half portion of the beam with respect to the scanning direction is set in the second half of the beam profile of the first pulse laser beam The portion is located ahead of the position of the microcrystallization threshold of the portion in the scanning direction.

According to a sixth aspect of the present invention, there is provided a method of manufacturing a semiconductor thin film according to the fifth aspect.
The beam profile in the width direction of the second pulsed laser beam is such that the absolute value of the energy density gradient at the microcrystallization threshold in the latter half of the beam with respect to the traveling direction of the scan is 20.
20002000 J / cm ³ .

According to a seventh aspect of the present invention, there is provided a method of manufacturing a semiconductor thin film according to any one of the first to sixth aspects, wherein a coarse portion formed by irradiating the latter half of the beam. The minimum width at the constricted portion is smaller than the grain size of the crystal grains.

According to an eighth aspect of the present invention, in the method of manufacturing a semiconductor thin film according to any one of the first to seventh aspects, the absolute value of the energy density gradient is 100 to 1000 J / cm ^3. It is characterized by being.

It is known that when a pulsed laser beam applied to an amorphous silicon thin film exceeds a certain energy density, the grain size of the formed polycrystalline silicon thin film becomes extremely fine, less than 20 nm. It is also known that, depending on the film thickness, it becomes amorphous without being crystallized after being melted by laser irradiation. The energy density at this time is called a microcrystallization threshold. Also, the microcrystallization threshold of the polycrystalline silicon thin film exists at a value about 14% larger in energy density than the microcrystallization threshold of the amorphous silicon thin film. Note that a thin film having no single crystal structure such as an amorphous thin film and a polycrystalline thin film is referred to as a non-single-crystal thin film.

In these microcrystallizations, the nucleation mechanism during recrystallization changes from non-uniform nucleation using the substrate thin film interface as a nucleation site to uniform nucleation due to a change in the melting state of the thin film. It is thought to occur due to This change in the nucleation mechanism depends on the temperature reached and the cooling rate of the thin film. Therefore, the microcrystallization threshold changes depending on the thickness of the thin film, the structure of the thin film, the wavelength of the pulsed laser light, the pulse width, the substrate temperature, and the like.

When a non-single-crystal silicon thin film is irradiated with a laser beam having an energy density exceeding the microcrystallization threshold, a portion of the beam profile having an energy density just below the microcrystallization threshold is irradiated. Coarse crystal grains are formed. That is, a coarse crystal is formed at a position adjacent to the microcrystalline region. The study by the present inventors has revealed that the arrangement of the coarse crystal grains depends on the energy density gradient in the beam profile. In the present invention, the “energy density gradient” refers to the gradient of the inclined portion in the beam profile in which the horizontal axis represents the position in the laser beam irradiation area and the vertical axis represents the energy density. Since the energy density gradient is obtained by differentiating the energy density with a variable representing the position, the unit is (J / cm ² ) / cm,
That is, it can be expressed in J / cm ³ .

When the energy density gradient is increased to 20 J / cm ³ or more, the arrangement of the coarse crystal grains changes from a disordered state to a state in which they are arranged in a line. Therefore, the beam profile has a portion equal to or higher than the microcrystallization threshold of the non-single-crystal silicon thin film, and the energy density gradient in the vicinity of the microcrystallization threshold in the second half of the beam with respect to the traveling direction is 20 J / cm ³ or more When irradiating the non-single-crystal silicon thin film with the laser light, it is possible to one-dimensionally control the grain size and the generation position of the formed crystal grains.

In order to control the crystal grain generation position in two dimensions,
It is effective to process the non-single-crystal silicon thin film into an island shape having a constricted portion. When the sharpest point of the constricted portion is set to be equal to or less than the grain size of the coarse crystal grains and the position is irradiated with the pulsed laser beam having the above-mentioned beam profile, the portion having the energy density immediately below the microcrystallization threshold in the latter half of the beam is irradiated. Only one coarse crystal grain is formed at a position. When this coarse crystal grain is used as a seed crystal and a laser beam is scanned at a grain size or less, the seed crystal continues to grow without interruption.

Here, the polycrystalline structure including the coarse crystal grains formed in the first half of the beam is microcrystallized by the subsequent scan irradiation, and thus does not hinder the growth of the seed crystal grains. That is, by utilizing the microcrystallization phenomenon, it is possible to avoid the inhomogeneity of the crystal structure in the pulsed laser beam scanning irradiation method. Therefore, if an energy density equal to or higher than the microcrystallization threshold of the polycrystalline silicon thin film is used, a complicated optical system for forming a fine beam is not required.

In order to increase the single crystallization width by using the constricted portion of the island-shaped silicon thin film, it is necessary to appropriately control the constriction angle. According to the study by the present inventors, it has been clarified that the constriction angle is preferably set in a range of 40 to 80 degrees centered on 60 degrees. This angle range is considered to be due to the crystal growth direction during crystal grain growth. In silicon crystal grains formed by the laser annealing method, {111} or {110} represented by the Miller index appears as a main preferred orientation plane. Table 1 lists relatively low order crystal orientations that can be crystal grain growth orientations in {111} and {110}, and the angles formed by each orientation group are in the range of about 40 to 80 degrees.

[Table 1]

As described above, according to the present invention, a single crystal thin film can be obtained at low cost by a laser annealing method having a novel beam profile and a novel thin film shape.

[0023]

Embodiments of the present invention will now be described with reference to the drawings.

A first embodiment of the present invention will be described with reference to the drawings. As shown in the schematic plan view of FIG. 1, a pulsed laser beam 102 is emitted from a constricted portion of an island-shaped non-single-crystal semiconductor thin film 101 having a constricted portion 101a having a peak angle P of 40 to 80 degrees on an insulating substrate. Irradiate scan.

FIG. 2A shows a beam profile in the width direction of the linear pulsed laser beam. The laser travels from left to right in the figure. The maximum energy density in the profile exceeds the microcrystallization threshold (E) of the polycrystalline silicon thin film, and the energy density gradient at E is 20 to 2000 J / cm ³ . FIG. 2A shows a top flat type profile, but the profile shape in a region of E or more is not particularly limited.

Such a beam profile can be easily obtained by using an ordinary optical system including a cylindrical lens and a fly-eye lens. When the mask imaging method is used, a steeper energy density gradient can be obtained. As the mask, for example, a metal mask or a dielectric mask of chromium, aluminum, a stainless steel alloy, or the like can be used.

The structure change when the non-single-crystal semiconductor thin film is irradiated with the pulse laser beam having the profile shown in FIG. 2A will be described with reference to FIGS. 2B to 2C. In the latter half of the beam profile of the laser beam, the part directly below E irradiates the tip of the constricted part, the single crystal grain
201 is formed. Single crystal grain 2 with beam profile
A microcrystal region 202 is formed adjacent to 01, and coarse crystal grains 203 formed by a portion directly below E in the first half of the beam profile are formed continuously. Here, when the crystal grain size of coarse grains 203 is d, such that the area of the single crystal grain 201 is [pi] d ^2/4 or less, it is necessary to control the laser beam irradiation position.

Next, when the laser beam is moved by a distance X which is d or less and irradiated, the single crystal grain 201 grows by X minutes. The region width of the microcrystallized region 202 does not change because it is defined by the beam profile, and the coarse crystal grains 203 formed in the first half of the beam profile are reconstructed at a point advanced by X. By repeating this scan irradiation, the island-shaped non-single-crystal semiconductor thin film can be changed to a single-crystal thin film without depending on the thermal history of the laser light irradiated in the past.

Further, when performing scan irradiation for irradiating the same spot a plurality of times, a single crystal film with less intragranular defects can be obtained. However, excessive irradiation reduces the throughput of the laser annealing process and promotes ablation of the thin film.

Next, a second embodiment of the present invention will be described.
This will be described with reference to the schematic plan view of FIG. On a non-single-crystal semiconductor thin film formed on an insulating substrate, an island-shaped translucent insulating thin film 30 having a constricted portion 301a having a peak angle P of 40 to 80 degrees.
1 is formed, and the constricted portion is irradiated with the pulse laser beam 102 while scanning in the same manner as in the first embodiment. Since the reflectance of the pulse laser beam 102 changes due to the light-transmitting insulating thin film 301, the value of E changes, but the definition of the beam profile is the same as in the first embodiment. At this time, the region where the light-transmitting insulating thin film 301 of the non-single-crystal thin film is deposited is monocrystallized.

Next, a third embodiment of the present invention will be described.
This will be described with reference to the schematic plan view of FIG. An island-shaped non-single-crystal semiconductor thin film 401 having a constricted portion is formed over an insulating substrate. The non-single-crystal thin film 401 has a forehead 402 and a main body 403, and a constricted portion 40 formed between the forehead 402 and the main body 403.
The tip angle P of 1a is 40 to 80 degrees. Also, the forehead 402
The width of the thin film at the connection between the body and the body is d or less.

A pulse laser beam 102 having an energy density gradient of 20 to 2000 J / cm ³ at E in the latter half of the beam is applied to the frontal region.
From 402, irradiation is performed while scanning in the same manner as in the first embodiment. Although a plurality of crystal grains are generated in the forehead 402, the number of crystal grains decreases with the progress of irradiation due to the effect of the constriction, and only one crystal grain exists at the connection between the forehead 402 and the main body 403 I do. Subsequent scan irradiation causes the main body 403
Becomes a single crystal.

Next, a fourth embodiment of the present invention will be described with reference to FIGS. Pointed angle of 40 to 80 on insulating substrate
A pulse laser beam is scanned and irradiated by the double pulse method from the constricted portion of the island-shaped non-single-crystal semiconductor thin film having the constricted portion. The double pulse method is a pulse laser irradiation method for sequentially irradiating two types of pulse laser lights oscillated from different light sources to the same point.

FIG. 5 shows the widthwise profiles of the first pulse laser beam and the second pulse laser beam when the double pulse method is used. The laser travels from left to right in the figure. The first pulsed laser beam having the profile shown in FIG. 5A has a region of E or more,
Is 20 to 2000 J / cm ³ .
FIG 5 (b) maximum energy density E ₂ of the second pulse laser light shown in is less than or equal to the maximum energy density E ₁ of the first pulse laser beam. Further, the position of E in the latter half of the second pulsed laser light is ahead of the position of E in the latter half of the first pulsed laser light.

The optimum distance y between the position of E in the latter half of the second pulse laser beam and the position of E in the latter half of the first pulse laser beam depends on the double pulse irradiation interval. For example, when the irradiation interval is sufficiently larger than the pulse width of the first pulsed laser beam and the second pulsed laser beam is irradiated after the melting and solidification process of the thin film by the first pulsed laser beam, y is d or less. And The diameter of the coarse crystal grains formed at this time is d + y, which is larger than d in the first embodiment. Therefore, the scan distance can be made longer than X, and the throughput in the laser annealing process is improved. When irradiating the second pulse laser beam before the melting and solidifying process of the thin film by the first pulse laser beam is completed, d is controlled without controlling y to d or less.
The above crystal grains can be formed. Further, E ₂ <E may be satisfied.

FIG. 6 shows a laser irradiation apparatus for realizing the double pulse method. The first pulse laser light source 601 and the second pulse laser light source 602 oscillate under the control of the synchronization control unit 603. Each pulsed laser beam is irradiated through the optical system 604, but may pass through the same optical path here.

[0037]

Next, a first embodiment according to the first embodiment of the present invention will be described.
An example will be described. An OA-2 substrate manufactured by NEC Corporation was used as the glass substrate. Next, S by plasma CVD
Using iH ₄ and N ₂ O, a silicon dioxide thin film as a base insulating film was deposited to a thickness of 100 nm. Next, an amorphous silicon thin film was deposited to a thickness of 75 nm from Si ₂ H ₆ by a low pressure CVD method. As the deposition conditions,
Si ₂ H ₆ Flow rate 150 sccm, pressure 8 Pa, substrate temperature 450 ° C. 70
For a minute.

As a preliminary experiment for determining a profile, E was examined when the amorphous silicon thin film was irradiated with a pulse laser beam having a wavelength of 308 nm and a pulse width of 50 nm. FIG. 7 shows the average grain size of the polycrystalline structure obtained by irradiating the amorphous silicon film and the polycrystalline silicon thin film having an average grain size of 18 nm with one pulse of laser light when the film thickness is 75 nm. This shows energy density dependence. In the case of the amorphous silicon thin film, the average particle diameter showed a change indicated by a black circle in the figure, and showed microcrystallization at 460 mJ / cm ² . Then obtained by irradiating the amorphous silicon thin film at 340 mJ / cm ^2, when the polycrystalline silicon thin film having an average particle size of 18 nm, the average particle diameter indicates a change shown in the drawing the white squares,
Microcrystallization was shown at 520 mJ / cm ² . That is, it was found that E was 520 mJ / cm ² . When the maximum energy density of the pulsed laser beam exceeds E, coarse crystal grains with a grain size exceeding 1 μm are formed adjacent to the microcrystalline region, but the coarse crystal grains are formed at the energy density gradient near E on the profile. Depended on.

FIG. 8 shows an interface between coarse crystal grains and fine crystal grains formed when the energy density gradient is 10 J / cm ³ . Due to the distribution probability of nucleation frequency associated with structural fluctuations, the coarse / fine grain interface was randomly arranged over a width of about 15 μm. On the other hand, the energy density gradient shown in FIG.
At 20 J / cm ³ , the coarse / fine grain interface is 0.5 μm wide
Controlled within. Therefore, in order to continuously grow a seed crystal by scanning irradiation at a pitch smaller than the particle size,
An energy density gradient of 20 J / cm ^{3 at which} the interface width becomes 1/2 or less of the particle size is required at a minimum. Also, the energy density gradient
At 100 J / cm ³ , the interface between the coarse crystal grains / fine crystal grains is controlled within 0.1 μm in width, which is a more preferable condition.

If the energy density is excessive, the film is peeled off by ablation. In this embodiment, about 720 mJ / cm ²
Was the ablation intensity. Therefore, the upper limit of the energy density gradient is about 2000 J / cm ³ in consideration of the controllability of the profile, the resolution, and the like. Because in general the mask imaging method of the optical system using about 1000 J / cm ³ is limited, from the viewpoint of cost 1000 J / cm ³ or less of the energy density gradient is desirable.

From the above results, the beam profile was
The maximum energy density is 600mJ / cm ^Two, The second half of the beam, E
The energy density gradient at the point was set to 100 J / cm3. Beam width
Was about 50 μm. Pal with above profile
When scanning laser light with a pitch of 0.5 μm,
It was confirmed that a directional growth structure was obtained.

Next, laser annealing was performed on the amorphous silicon thin film formed into islands using the above-described beam profile, and optimization of the islanded shape was studied. In the case of the conventional example shown in FIG. 10, when a rectangular shape was formed into islands, a grain boundary was generated when the thin film width was set to 2 μm or more. The average grain boundary spacing was 1.3 μm, which was in good agreement with the maximum crystal grain size shown in FIG.

As shown in FIG. 1, when a constricted portion is provided in an island shape in the beam traveling direction, the width of the thin film is 10 μm.
FIG. 11 shows the relationship between the peak angle of the constricted portion and the average number of grain boundaries of 10 samples. Samples with no grain boundaries were formed at a peak angle of 80 degrees or less, and the average number of grain boundaries was 1 or less. 7
In the range of 0 to 50 degrees, all samples were grain-free. 40
Below the temperature, a sample having a particle size was observed again, and the number of particle sizes tended to increase as the angle decreased. 30 substrates
When laser annealing is performed by heating to 0 degree, the peak angle is 40
At 80 and 80 degrees, all samples were grain-free.

Note that the constricted portion does not necessarily need to be formed symmetrically with respect to the beam, and the same effect is obtained when the constricted portion is asymmetric as shown in FIG. Further, as shown in FIG. 13, a parallel region having a width equal to or smaller than the grain diameter of the seed crystal grain may be provided at the tip of the constricted portion.

Next, a second example based on the second embodiment of the present invention will be described. OA as in the first embodiment
A silicon dioxide thin film and an amorphous silicon thin film were deposited on a -2 substrate. Next, a silicon dioxide thin film serving as an antireflection film was deposited to a thickness of 50 nm by a low pressure CVD method. Anti-reflection coating using PR method
The island was formed into a shape having a sharp angle of 60 degrees. The width and length were 10 and 30 μm, respectively.

A wavelength of 308 nm and a pulse width of 5
Irradiate amorphous silicon thin film with 0nm pulse laser light
When E is 350mJ / cm^TwoMet. Maximum energy density 370m
J / cm ^Two, Energy density gradient 80 at point E in the latter half of the beam
J / cm^ThreeLaser beam with a beam width of 60 μm at 0.8 μm pitch.
Single crystal in the area under the anti-reflective coating
The resulting silicon thin film was obtained.

Next, a third example based on the third embodiment of the present invention will be described. An OA-2 substrate manufactured by NEC Corporation was used as the glass substrate. Next, a silicon dioxide thin film as a base insulating film was deposited to a thickness of 100 nm using SiH4 and N2O by a plasma CVD method. Next, a 50 nm amorphous silicon thin film was deposited from Si ₂ H ₆ by a low pressure CVD method. The deposition was performed for 46 minutes at a Si ₂ H ₆ flow rate of 150 sccm, a pressure of 8 Pa, and a substrate temperature of 450 ° C.

Next, the amorphous silicon thin film was formed into islands as shown in FIG. 4 by the ordinary PR method. The thin film width was 5 μm, and the length of the main body was 20 μm. The forehead angle of the forehead and the main body were both 70, and the width of the connecting portion at both locations was 1 μm. Film thickness
In the case of 50 nm, E was 470 mJ / cm ² with a pulse laser beam having a wavelength of 308 nm and a pulse width of 50 nm. Maximum energy density 500m
J / cm ² , energy density gradient 60 at point E in the latter half of the beam
A single crystal thin film was obtained by scanning and irradiating a laser beam of 0 J / cm ³ and a beam width of 30 μm at a pitch of 0.7 μm.
In addition to the island shape, a plurality of main bodies may be connected as shown in FIG.

Next, a fourth example based on the fourth embodiment of the present invention will be described. As a glass substrate, a Corning 1737 substrate was used. Next, S by plasma CVD
Using iH ₄ and N ₂ O, a silicon dioxide thin film as a base insulating film was deposited to a thickness of 100 nm. Next, an amorphous silicon thin film was deposited to a thickness of 75 nm by plasma CVD using SiH ₄ and H ₂ . The deposition conditions were as follows: SiH ₄ flow rate 150 sccm, H2 flow rate 400 sccm, pressure 100P
a, Deposition was performed for 8 minutes under the conditions of a discharge power of 0.1 W / cm ² and a substrate temperature of 320 ° C. After the deposition, dehydrogenation annealing was performed at a heat treatment temperature of 400 ° C. for a heat treatment time of 2 hours. Next, the amorphous silicon thin film was formed into an island shape with a peak angle of 50 degrees, a width of 20 μm, and a length of 100 μm. E of this amorphous silicon thin film using pulse laser light having a wavelength of 248 nm and a pulse width of 35 nm was 550 mJ / cm ² .

As the first pulse laser beam, a pulse laser beam having a profile of a maximum energy density of 580 mJ / cm ² , an energy density gradient of 390 J / cm ³ at point E in the latter half of the beam, and a beam width of 40 μm is irradiated. As the second pulse laser beam, a pulse laser beam having a top-flat profile, a maximum energy density of 400 mJ / cm ² , an energy density gradient at point E in the latter half of the beam of 220 J / cm ³ , and a beam width of 35 μm Is irradiated. The oscillation interval between the first pulse laser beam and the second pulse laser beam was set to 50 nsec.
At this time, the grain size of the seed crystal was 3 μm, which was more than 1.3 μm that when irradiated with only the first pulse laser beam.

By scanning and irradiating the above double pulse laser beam at a pitch of 2.5 μm, an island-shaped single crystal thin film was obtained at high throughput.

[0052]

As described in detail above, according to the method of manufacturing a semiconductor thin film according to the present invention, a high-quality semiconductor thin film such as a unidirectionally grown polycrystalline semiconductor thin film or a single crystal semiconductor thin film can be obtained at low cost. Is obtained.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a first embodiment of a method for manufacturing a semiconductor device according to the present invention.

FIG. 2A is a diagram showing a beam profile in the width direction of a pulse laser beam. FIGS. 3B and 3A are diagrams showing a change in the structure of the non-single-crystal semiconductor thin film irradiated with the pulsed laser beam shown in FIG. FIGS. 3C and 3B are diagrams illustrating a change in the structure of the non-single-crystal semiconductor thin film when the pulsed laser beam advances x.

FIG. 3 is a diagram illustrating a second embodiment of a method for manufacturing a semiconductor device according to the present invention.

FIG. 4 is a diagram illustrating a third embodiment of the method of manufacturing a semiconductor device according to the present invention.

FIG. 5 is a diagram showing a beam profile in a width direction of a pulse laser beam in a third embodiment of the method of manufacturing a semiconductor device according to the present invention. (A) The case of the first pulse laser beam. (B) The case of the second pulse laser beam.

6 is a schematic diagram of a configuration of a laser irradiation device in FIG.

FIG. 7 shows an energy density of an average grain size of a polycrystalline structure obtained by irradiating a pulse laser beam to an amorphous silicon film and a polycrystalline silicon thin film having an average grain size of 18 nm in the first embodiment. Show dependencies.

8A is a diagram showing a beam profile in the width direction when the energy density gradient is 10 J / cm ³ in the first embodiment. FIG. (B) It is a figure which shows typically the interface of the coarse crystal grain and the fine crystal grain formed when the pulse laser beam of (a) is irradiated.

9A is a diagram showing a beam profile in the width direction when the energy density gradient is 20 J / cm ³ in the first embodiment. FIG. (B) It is a figure which shows typically the interface of the coarse crystal grain and the fine crystal grain formed when the pulse laser beam of (a) is irradiated.

FIG. 10 is a view in which a conventional rectangular island-shaped thin film is irradiated with a pulsed laser beam.

FIG. 11 is a diagram showing a relationship between a pointed angle of a constricted portion and an average number of grain boundaries of ten samples in the first embodiment.

FIG. 12 is a diagram showing a case of an asymmetrical shape in a case of a constricted portion having another shape of the present invention.

FIG. 13 is a view showing a case where a constricted portion having another shape according to the present invention is provided, and a tip end of the constricted portion is provided with a parallel region having a width equal to or smaller than a grain size of a seed crystal grain.

FIG. 14 is a diagram showing a case where a plurality of main bodies are connected in a case of a constricted portion having another shape of the present invention.

[Explanation of symbols]

 Reference Signs List 101 non-single-crystal semiconductor thin film 101a constriction 102 pulse laser beam 201 single crystal grain 202 microcrystalline region 203 coarse crystal grain 301 light-transmitting insulating film 301a constriction 401 non-single-crystal semiconductor thin film 401a constriction 601 first pulsed laser light source 602 2nd pulse laser light source P Point angle

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4G077 AA03 AB10 BB03 BC60 DB04 DB16 ED06 FE16 FE19 HA01 TA04 5F052 AA02 BA07 BA14 BA15 CA10 DA02 DB02 DB03 FA02 FA03 GB07 JA01 JA10 5F110 DD02 DD13 GG02 GG12 GG13 GG14 GG15 GG15 GG15 GG15 GG15 GG15 GG15 GG15 GG15 GG15 GG58 PP03 PP04 PP05 PP06 PP07 PP11 PP23 PP35

Claims (8)

[Claims] 1. A method of manufacturing a semiconductor thin film, wherein a non-single-crystal semiconductor thin film formed in an island shape having at least a part of a constricted portion is scanned with a pulsed laser beam and irradiated on the non-single-crystal semiconductor thin film. The peak angle of the constricted portion is 40 to 80 degrees, the beam profile in the scanning direction of the beam has a region equal to or more than the microcrystallization threshold of the polycrystalline semiconductor thin film, and the method for manufacturing a semiconductor thin film in which the absolute value of the energy density gradient of a microcrystalline threshold beam rear half portion is characterized by a 20~2000J / cm ³ Te. 2. A non-single-crystal semiconductor thin film is scanned by a pulsed laser beam through an island-shaped light-transmitting insulating thin film having a constricted portion at least partially on the non-single-crystal semiconductor thin film. A method of manufacturing a semiconductor thin film to be irradiated, wherein a sharp angle of the constricted portion is 40 to 80 degrees, and a beam profile in a scanning direction of the beam has a region equal to or larger than a microcrystallization threshold of the polycrystalline semiconductor thin film. And a method of manufacturing a semiconductor thin film, wherein the absolute value of the energy density gradient at the microcrystallization threshold in the latter half of the beam in the scanning direction is 20 to 2000 J / cm ³ . 3. An island having a constriction at least in part
The non-single-crystal semiconductor thin film formed in
Two types of the first pulsed laser beam and the second
Pulsed laser beam to the same spot sequentially
The first and second pulse laser beads are formed using a pulse method.
Semiconductor thin film that scans and irradiates the beam in the width direction of the beam
Wherein the peak angle of the constricted portion is 40 to 80 degrees, and the beam profile in the scanning direction of the first pulsed laser beam is provided.
File is above the threshold for microcrystallization of polycrystalline semiconductor thin film
And the latter half of the beam in the scanning direction
Value of the energy density gradient at the microcrystallization threshold of the part
Is 20 ~ 2000J / cm ^ThreeAnd the maximum energy density of the second pulsed laser beam
Is the maximum energy density of the first pulsed laser beam.
A method for producing a semiconductor thin film, wherein the temperature is not more than a degree. 4. The method according to claim 1, wherein at least one of
Island-shaped translucent insulating thin film with constricted part
First, two types of first pulse trains oscillated from different light sources
Laser beam and second pulsed laser beam at the same point
Using the double pulse method of sequentially irradiating
Semiconductor for scanning and irradiating a laser beam in the width direction of the beam
A method of manufacturing a body thin film, wherein a pointed angle of the constricted portion is 40 to 80 degrees, and a beam profile in a scanning direction of the first pulsed laser beam is provided.
File is above the threshold for microcrystallization of polycrystalline semiconductor thin film
And the latter half of the beam in the scanning direction
Value of the energy density gradient at the microcrystallization threshold of the part
Is 20 ~ 2000J / cm ^ThreeAnd the maximum energy density of the second pulsed laser beam
Is the maximum energy density of the first pulsed laser beam.
A method for producing a semiconductor thin film, wherein the temperature is not more than a degree. 5. The method for manufacturing a semiconductor thin film according to claim 3, wherein a beam profile of the second pulsed laser beam in a scanning direction is equal to or more than a microcrystallization threshold of the polycrystalline semiconductor thin film. A position where the microcrystallization threshold value of the second half of the beam with respect to the scanning traveling direction is higher than the position where the microcrystallization threshold value of the second half of the beam in the beam profile of the first pulsed laser beam is provided. A semiconductor thin film manufacturing method, wherein the semiconductor thin film is located in front of the scanning direction. 6. The method of manufacturing a semiconductor thin film according to claim 5, wherein a beam profile of the second pulsed laser beam in a width direction is a microcrystallization threshold value in a latter half of the beam with respect to a traveling direction of the scanning. The absolute value of the energy density gradient at
2,000 J / cm ³ . 7. The method of manufacturing a semiconductor thin film according to claim 1, wherein a diameter of the coarse crystal grains formed by irradiating the latter half of the beam is smaller than a diameter of the narrow crystal part. A method for producing a semiconductor thin film, wherein a minimum width is small. 8. The method of manufacturing a semiconductor thin film according to claim 1, wherein the absolute value of the energy density gradient is 100 to 1000 J / cm ^3. Method.