JP2000260709A - Method of crystallizing semiconductor thin film and semiconductor device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the crystal grain size of a semiconductor thin film with a satisfactory reproducibility only by injection of a laser beam for a method of crystallizing semiconductor thin film and a semiconductor device. SOLUTION: A non-single crystal semiconductor thin film 2 consisting essentially of silicon is formed on an insulating substrate 1, and then an insulating pattern 3 is selectively formed on the film 2. Thereafter, the resulting substrate 1 is irradiated with a laser beam 4, thereby crystallizing the film 2 from the ends toward the central portion of the pattern 3. As a result, such high- performance thin-film semiconductor devices free of variations in characteristics as TETs can be manufactured with a satisfactory productivity and hence contributes to devices such as active matrix liquid crystal display devices, given high image quality and high definition and manufactured at lower cost.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for crystallizing a semiconductor thin film and a semiconductor device using the same.
In particular, a pixel switching element of a liquid crystal display device, or
The present invention relates to a method of crystallizing a semiconductor thin film characterized by a method of increasing the grain size of a polycrystalline silicon thin film for forming a thin film transistor (TFT) used as a data driver, a gate driver, and the like, and a semiconductor device using the same.

[0002]

2. Description of the Related Art Conventionally, liquid crystal display devices have been used for OA terminals, projectors, etc. because of their small size, light weight, and low power consumption. In particular, for a high quality liquid crystal display device, an active matrix type liquid crystal display device provided with an active switching element for each pixel is used.

In such an active matrix type liquid crystal display device, by operating each pixel in the display section with an active element such as a TFT, crosstalk during non-selection as in a simple matrix type liquid crystal display device is completely eliminated. And excellent display characteristics can be exhibited.

[0004] Among them, an active matrix type liquid crystal display device using a TFT as an active element has a high driving capability of a control element, so that it is applied to a liquid crystal display device with a built-in driver and a high resolution / high definition liquid crystal display device. ,
In recent years, a device using polycrystalline silicon, which has high mobility and enables simultaneous formation of peripheral circuits, has begun to be put to practical use.

Although a higher quality polycrystalline silicon film is required as a polycrystalline silicon film used for such a polycrystalline silicon TFT, a conventional technique for growing crystal grains of a polycrystalline silicon film is a so-called polycrystalline silicon film. SOI (Silicon
In the field of "on insulator", a method of depositing amorphous silicon, that is, an amorphous silicon film or a polycrystalline silicon film on an insulating film, irradiating the film with an Ar-CW laser, and crystallizing the film has been studied for a long time.

In the field of recent low-temperature polycrystalline silicon, a crystallization method by irradiation with a short-pulse excimer laser capable of heating only a non-single-crystal thin film without affecting a glass substrate has become mainstream.

[0007]

Recently, an excimer laser capable of irradiating a high-power linear beam has been developed to perform such laser irradiation on a large-area substrate.
A crystallized silicon film obtained by crystallization by laser irradiation is easily affected not only by the irradiation energy density but also by the beam profile and the state of the film surface, etc. 10 and FIG.
This will be described with reference to FIG.

Referring to FIG. 10A, FIG. 10A shows a relatively low energy density, for example,
FIG. 4 is an explanatory diagram of a change in Raman shift in a beam scan direction when a laser beam of 304 mJ / cm ² is irradiated. Although the variation in crystallinity in the beam scan direction is relatively small, the peak wave number is near 516 cm ⁻¹ , This indicates that a TFT having a small crystal grain size and excellent characteristics cannot be obtained. In the case of an amorphous silicon film, a broad peak is observed around 480 cm ⁻¹ , while in the case of a single crystal silicon film, it is about 520.5 cm ^−1.
, A sharper peak appears, and the closer to 520.5 cm ^-1 , the larger the crystal grain size and the better the crystallinity.

FIG. 10B is a diagram illustrating a change in Raman shift in the beam scanning direction when a laser beam having a relatively high energy density, for example, 360 mJ / cm ² is irradiated. Although the peak wave number is 516 cm ⁻¹ or more, which indicates that the crystal grain size is large, the variation in crystallinity in the beam scanning direction increases due to the influence of the fluctuation of the laser power and the influence of the beam edge. Would.

Therefore, when a TFT is formed on such a crystallized silicon film, the mobility increases if the crystal grain size of the channel region is large and the number of grain boundaries existing in the channel length direction is small. Small grain size,
If the number of grain boundaries existing in the channel length direction is large, the mobility becomes small, and thus, there is a problem that the characteristics tend to appear as variations in TFT characteristics. For example, in the drawing, the characteristics of the TFT formed in the portion are clearly different from the characteristics of the TFT formed in the portion.

In the crystallization by laser irradiation, the reflectance is reduced to improve the energy efficiency,
Alternatively, in order to suppress the occurrence of irregularities on the surface due to laser irradiation, laser irradiation is often performed in a state where a SiO ₂ cap is formed on the surface. However, there is a problem that the uniformity is rather deteriorated.

FIG. 11 is an explanatory diagram of the Raman shift in the case where the SiO ₂ cap is provided. As is clear from the figure, the shift has been shifted to the higher wave number side as a whole, and the improvement of the crystallinity has not been improved. Although it is recognized, the variation is large. Therefore, when a TFT is formed on such a crystallized silicon film, the problem that the variation in device characteristics is large still remains.

As a method for increasing the crystal grain size, an antireflection film pattern such as a SiN film is provided on an amorphous silicon film, and then an Ar laser is irradiated to the amorphous silicon film immediately below the antireflection film pattern. By forming a crystal nucleus and then performing a heat treatment at 600 ° C. for 10 hours in an electric furnace, the amorphous silicon immediately below the antireflection film pattern is solid-phase grown around the crystal nucleus to increase the crystal grain size. It has also been proposed (see JP-A-7-240527 if necessary).

However, in this case, in addition to laser irradiation, a heat treatment at 600 ° C. for 10 hours is required in an electric furnace, which causes a problem that the number of manufacturing steps increases and throughput decreases.

Therefore, an object of the present invention is to increase the crystal grain size of a semiconductor thin film with good reproducibility only by laser irradiation.

[0016]

FIG. 1 is an explanatory view of the principle configuration of the present invention. Referring to FIG. 1, means for solving the problems in the present invention will be described. FIG. 1 (1) In the present invention, in a method for crystallizing a semiconductor thin film, a non-single-crystal semiconductor thin film 2 containing silicon as a main component is formed on an insulating substrate 1 and then formed on the non-single-crystal semiconductor thin film 2. A step of selectively forming the insulating film pattern 3 and then irradiating a laser beam 4 to crystallize the non-single-crystal semiconductor thin film 2 from the end to the center of the insulating film pattern 3. And

As described above, after the insulating film pattern 3 is selectively formed on the non-single-crystal semiconductor thin film 2, the non-single-crystal semiconductor thin film 2 is irradiated with the laser beam 4 so that the non-single-crystal semiconductor thin film 2 is indicated by an arrow in the drawing. By crystallizing from the end to the center of the pattern 3, a crystallized region 6 having a large crystal grain size can be formed at an arbitrary position only by laser irradiation, thereby reducing variations in device characteristics. can do. In the region where the insulating film pattern 3 is not provided, the crystallization proceeds and the polycrystalline region 5 is formed, but the crystal grain size is smaller than that of the crystallized region 6. In addition, “consisting mainly of silicon” means silicon itself or
A semiconductor obtained by adding elements such as germanium to silicon means "non-single crystal" means amorphous, microcrystalline,
And polycrystalline. In this case, the wavelength of the laser light is a wavelength that becomes an absorption wavelength in accordance with the forbidden band width of the non-single-crystal semiconductor thin film, and usually ultraviolet light is used.

(2) The present invention is characterized in that, in the above (1), the line width of the insulating film pattern 3 is 5 μm or less.

When a glass substrate is used as the insulating substrate 11, the crystal grain size obtained at a temperature that the glass substrate can withstand is at most about 2 μm. Means that the line width of the insulating film pattern 3 is 5 μm or less, more preferably 0.5 to 2.0 μm.
It is desirable to set the grain size to μm, whereby the crystal grain size of the crystallized region 6 immediately below the insulating film pattern 3 can be adjusted to a grain size suitable for device fabrication, and the crystal grain boundary can be reduced. If the line width of the insulating film pattern 3 is 2 μm, the number of crystal grains in the line width direction is about two.

(3) The present invention is characterized in that, in the above (2), the non-single-crystal semiconductor thin film 2 is processed into an island pattern before the insulating film pattern 3 is provided.

As described above, the island pattern for forming the device may be formed by patterning the non-single-crystal semiconductor thin film 2 before providing the insulating film pattern 3. Since the escape of heat is reduced, crystallization with lower energy becomes possible. Further, the temperature difference between the island patterns becomes smaller, so that a more uniform crystal is easily obtained, and the beam profile of the laser beam 4 is further improved. Less susceptible.

(4) The present invention is characterized in that, in the above (1), the line width of the insulating film pattern 3 is larger than the channel length of the thin film transistor by at most 4 μm.

As described above, by setting the line width w of the insulating film pattern 3 to be larger than the channel length of the thin film transistor by at most 4 μm, that is, by setting w ≦ channel length + 2 × 2 μm, the crystal just below the insulating film pattern 3 can be obtained. The crystal grain size of the region adjacent to the channel region of the thin film transistor at the center of the activated region 6 can be made larger than the crystal grain size of the channel region, and the adjacent region can have lower resistance.
Since there is no need to form a DD (Lightly Doped Drain) region, it is possible to prevent damage due to ion implantation for forming an LDD region.

(5) The present invention provides a semiconductor device using a crystallized semiconductor thin film formed by the crystallization method according to any one of the above (1) to (3).
Is used as an active region.

As described above, by using the crystallized region 6 having a larger crystal grain size as an active region, variations in the characteristics of semiconductor devices such as thin film transistors and diodes can be reduced.

(6) The present invention is characterized in that, in the above (5), at least a part of the crystallized region 6 immediately below the insulating film pattern 3 is used as a channel region of a thin film transistor.

As described above, by making at least a part of the crystallization region 6 immediately below the insulating film pattern 3 a channel region of the thin film transistor, the characteristics of a large number of thin film transistors provided on the insulating substrate 1 having a large area can be improved. Therefore, the active matrix type liquid crystal display device with high performance can be configured.

(7) The present invention is characterized in that, in the above (6), only two or less crystal grains exist in the channel length direction of the channel region.

As described above, by reducing the number of crystal grains existing in the channel region in the channel length direction to two or less, the mobility of the channel region can be increased.
The operation speed of the thin film transistor can be further increased.

(8) Further, according to the present invention, in a semiconductor device using a crystallized semiconductor thin film by the crystallization method according to the above (4), a channel at the center of a crystallized region 6 immediately below an insulating film pattern 3 is provided. A region in which the crystal grain size of the region adjacent to the region is larger than the crystal grain size of the channel region is defined as an electric field relaxation region.

As described above, the crystal grain size of the region adjacent to the channel region of the thin film transistor at the center of the crystallized region 6 immediately below the insulating film pattern 3 is made larger than the crystal grain size of the channel region, and the adjacent region is made low. An electric field relaxation region can be obtained by forming a resistance region, and
The electric field can be reduced without providing a region.

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Here, a first embodiment of the present invention will be described with reference to FIGS. 2 to 4. First, referring to FIGS. 2 and 3, the first embodiment of the present invention will be described. The manufacturing process of the embodiment will be described. 2 (a) to 3 (c), the drawings on the left are top views of main parts, and the drawings on the right are cross-sectional views of main parts along the channel length direction.
FIG. 4D is an enlarged view of a circle shown by a broken line in FIG.

First, as shown in FIG. 2A, for example, a base SiO ₂ film 12 having a thickness of 150 nm and a thickness 10 are formed on a transparent glass substrate 11 serving as a TFT substrate by a plasma CVD method (PCVD method). ~ 200
nm, eg, 50 nm, amorphous silicon film 1
3, and a SiO ₂ film 14 having a thickness of, for example, 50 nm
Are sequentially deposited. The thickness d of the SiO ₂ film 14 in this case, the wavelength of the laser beam in the laser irradiation step after lambda, if the refractive index of the SiO ₂ film 14 was set to n, d ≒ lambda
/ 4n is set to a value that satisfies / 4n to form an antireflection film.

Next, by patterning the SiO ₂ film 14, an S ₂ having a line width w of 5.0 μm or less, for example, 2.0 μm, is used.
After the formation of the iO ₂ film pattern 15, an ultraviolet laser beam in a wavelength region easily absorbed by the amorphous silicon film 13, for example, Xe-Cl
Using an excimer laser, excimer laser light 16 having a wavelength of 308 nm is applied at 200 to 400 mJ / cm ² , for example, 3
The amorphous silicon film 13 is crystallized by irradiation with the energy density of 00 mJ / cm ^{2 from} the SiO ₂ film pattern 15 side. In order to heat only the amorphous silicon film 13 without affecting the glass substrate 11, it is necessary to use a pulse laser at present.

[0035] In this case, it means that satisfy a relation of 50nm ≒ 308nm / 4n, SiO ₂ film pattern 15
Acts as an anti-reflection film, the incident energy increases in the lower portion of the SiO ₂ film pattern 15, on the more temperature rises, the lower the SiO ₂ film pattern 15 because the SiO ₂ film pattern 15 also functions as a heat insulating layer In, the cooling rate becomes slow. Therefore, crystallization proceeds from the end of the SiO ₂ film pattern 15 toward the center, and the colliding occurs near the center, and a crystal grain boundary is formed near the center.

Next, after the SiO ₂ film pattern 15 is removed, the Si
Using a resist pattern (not shown) of a predetermined shape as a mask, Cl ₂ + BCl ₃ is used as an etching gas in the crystallized amorphous silicon film 13 so that a region below the O ₂ film pattern 15 becomes a channel region of the TFT. The silicon island pattern 17 is formed by performing dry etching.

In this case, the lower region of the SiO ₂ film pattern 15 is a crystallized silicon region 19 having a larger crystal grain size, and both sides thereof are polycrystalline silicon regions 18 having a relatively smaller crystal grain size, as shown in FIG.
The average crystal grain size in the crystallized silicon region 19 is about 0.8 to 1.0 μm, and one crystal grain boundary 20 is formed near the center of the crystallized silicon region 19 in the channel length direction. Become.

Although not shown hereafter, a basic structure of a TFT substrate is completed by forming a gate insulating film and a gate electrode in a normal TFT manufacturing process and performing ion implantation for forming a source / drain. Become. In this case, the crystallized silicon region 19 having a larger crystal grain size becomes the channel region, and the polycrystalline silicon regions 18 on both sides of which the crystal grain size is relatively small become the source / drain regions.

[0039] See Figure 4. Figure 4 is an illustration of Raman shift by Raman spectroscopy of the silicon thin film in the case where the line width of the SiO ₂ film pattern 15 to 2.0 .mu.m, you provided SiO ₂ film pattern 15 This indicates that the wave number in the region where the laser light is high is high and the crystallinity is good.

As described above, in the first embodiment of the present invention, since the laser annealing is performed after the SiO ₂ film pattern 15 is selectively provided, the crystal grain size is 0.8 to 0.8.
A crystallized silicon region 19 of about 1.0 μm can be formed at an arbitrary position with good reproducibility only by laser annealing, and since laser irradiation is performed with the SiO ₂ film pattern 15 provided, the surface is flat. The TF composed of TFTs with uniform characteristics can be expected.
T substrates can be manufactured.

FIG. 3D shows the crystallized silicon region 1.
As schematically shown in FIG. 9, only one crystal grain boundary 20 exists in the channel length direction of the TFT.
Characteristics close to those of a TFT using single crystal silicon can be obtained, and therefore, the speed and definition of the active matrix liquid crystal display device can be increased.

Next, the manufacturing process of the second embodiment of the present invention will be described with reference to FIGS.
6 (c), the left side is a top view of the main part, the right side is a cross-sectional view of the main part along the channel length direction, and FIG. 6 (d) is a sectional view of FIG. 3 is an enlarged view showing a part of the inside of a circle shown by a broken line in a see-through view of the SiO ₂ film pattern 15. First, as shown in FIG. 5A, for example, a transparent SiO ₂ film 12 having a thickness of 150 nm and a thickness of 10 to 200 nm are formed on a transparent glass substrate 11 serving as a TFT substrate by using a plasma CVD method.
For example, after sequentially depositing a 50 nm amorphous silicon film, a resist pattern having a predetermined shape (not shown)
Is used as a mask to form Cl ₂ + B on the amorphous silicon film.
By performing dry etching using Cl ₃ as an etching gas, the amorphous silicon island pattern 21 is formed.
To form

Next, referring to FIG. 5 (b), the thickness d is reduced to d ≒ again using the plasma CVD method.
After depositing a SiO ₂ film having a value satisfying λ / 4n, for example, 50 nm, the line width is 5.0 μm or less, for example, 2.
By patterning to a thickness of 0 μm, S
After forming the iO ₂ film pattern 15 and then setting the substrate temperature to room temperature, for example, using a Xe-Cl excimer laser, a pulse-like excimer laser beam 1 having a wavelength of 308 nm is used.
6 to 200 to 400 mJ / cm ² , for example, 240 mJ / cm ²
SiO ₂ film pattern 15 at an energy density of J / cm ²
Irradiation from the side crystallizes the amorphous silicon island pattern 21.

Also in this case, since the relationship of 50 nm ≒ 308 nm / 4n is satisfied also in this case, the SiO ₂ film pattern 15 functions as an antireflection film, and light is incident on the lower portion of the SiO ₂ film pattern 15. energy is increased, on the more temperature rises, the SiO ₂ film pattern 15 is the cooling rate is slower at the bottom of the SiO ₂ film pattern 15 so also serves as a heat insulating layer, in order that the end of the SiO ₂ film pattern 15 Since crystallization proceeds from the portion toward the center, the lower portion of the SiO ₂ film pattern 15 becomes a crystallized silicon region 19 having a large crystal grain size, and both sides thereof form a polycrystalline silicon region 18 having a relatively small crystal grain size. Become.

Referring to FIG. 6D, also in this case, the average crystal grain size in the crystallized silicon region 19 is about 0.8 to 1.0 μm. One crystal grain boundary 20 is formed near the central portion in the channel length direction of silicon nitride region 19.

Although not shown hereafter, a basic structure of a TFT substrate is completed by forming a gate insulating film and a gate electrode in a normal TFT manufacturing process and performing ion implantation for forming a source / drain. Become. Also in this case, the crystallized silicon region 19 having a larger crystal grain size serves as a channel region, and the polycrystalline silicon regions 18 having relatively smaller crystal grain sizes on both sides thereof serve as source / drain regions.

As described above, in the second embodiment of the present invention, in addition to obtaining the same operation and effects as those of the first embodiment, the amorphous silicon film is patterned to form an amorphous silicon island pattern. After the formation of 21, laser annealing is performed by selectively providing the SiO ₂ film pattern 15, so that heat escape is reduced, so that crystallization at lower energy becomes possible. The temperature difference for each pattern 21 is reduced, so that a more uniform crystal is easily obtained, and furthermore, the crystal is less affected by the beam profile of the excimer laser beam 16.

Next, the second embodiment of the present invention will be described with reference to FIGS.
The third embodiment will be described. First, refer to FIG. 7 and FIG.
In the following, the manufacturing process of the third embodiment of the present invention will be described.
You. Note that in FIGS. 7A to 8C, the left side
The figure is a top view of the main part, and the figure on the right is
FIG. 8D is a sectional view of a main part along the direction, and FIG.
In the circle shown by the broken line in FIG.
_TwoIt is the enlarged view which showed the film pattern partially transparently. Referring to FIG. 7A, first, as in the second embodiment, the TFT substrate is
Using a plasma CVD method on a transparent glass substrate 11
And, for example, a base SiO having a thickness of 150 nm. _TwoMembrane 1
2, and the thickness is 10 to 200 nm, for example, 50 nm
After successively depositing amorphous silicon films
Using a resist pattern (not shown) as a mask,
Cl on amorphous silicon film_Two+ BCl_ThreeThe etchin
By dry etching
The morphous silicon island pattern 21 is formed.

Next, referring to FIG. 7 (b), the thickness d is set again by using the plasma CVD method.
After depositing a SiO ₂ film having a value satisfying λ / 4n, for example, a 50 nm SiO ₂ film, the line width w becomes w ≦ channel length + 2 × 2 μm.
m, for example, by patterning to a pattern of 5.0 μm on both sides larger than the desired channel length by 1 μm to form a SiO ₂ film pattern 22, and then with the substrate temperature at room temperature, For example, X
Using an e-Cl excimer laser, a pulse-like excimer laser beam 16 having a wavelength of 308 nm is converted to 200 to 400 mJ /
The amorphous silicon island pattern 21 is crystallized by irradiating from the SiO ₂ film pattern 22 side at an energy density of cm ² , for example, 240 mJ / cm ² .

Next, referring to FIG. 8C, the SiO ₂ film pattern 22 is used as it is as a gate insulating film, a gate electrode 24 is provided thereon, and ion implantation for forming a source / drain is performed. The basic configuration of the substrate is completed.

Referring to FIG. 8D, also in this case, the thickness of the SiO ₂ film pattern 22 is 50 n.
Since the relation of m ≒ 308 nm / 4n is satisfied,
The SiO ₂ film pattern 22 functions as an anti-reflection film,
iO incident energy increases in the lower portion of the ₂ film pattern 22, on the more temperature rises, the SiO ₂ film pattern 22 is the cooling rate is slower at the bottom of the SiO ₂ film pattern 22 so also serves as a heat insulating layer, Therefore, crystallization proceeds from the end of the SiO ₂ film pattern 15 toward the center.

In this case, however, the SiO ₂ film pattern 22
Although the crystal grain size of the crystallized silicon region 23 at the end of the SiO ₂ film pattern is about 1 μm, at the center of the SiO ₂ film pattern 22, apart from the lateral crystal growth,
₂ It is considered that crystallization from the vicinity of the film 12 proceeds,
For this reason, before the crystal grains grown from the end of the SiO ₂ film pattern 22 hit the center, a region having a relatively small crystal grain size of about 0.6 to 0.7 μm is formed in the center. It is formed. The crystal grain size at the center is larger than the crystal grain size of the polycrystalline silicon regions 18 on both sides of the SiO ₂ film pattern 22.

Therefore, the crystallized silicon region 23 having a relatively large crystal grain size on both sides of the gate electrode 24 becomes the low-resistance region 25. By making the low-resistance region 25 correspond to the offset portion, the LDD region is formed. Even without the formation, the electric field can be relaxed.

[0054] Figure 9 Referring 9 is an explanatory view of a Raman shift by Raman spectroscopy of the silicon thin film in the case where the line width of the SiO ₂ film pattern 22 to 5.0 .mu.m, you provided SiO ₂ film pattern 22 It can be seen that the wave number at the central part of the region was lower, indicating that the crystallinity at the central part was slightly reduced.

As described above, in the third embodiment of the present invention, in addition to obtaining the same operation and effect as the above-described second embodiment, the line width w of the SiO ₂ film pattern 22 is changed to w
≦ channel length + 2 × 2 μm, so that both sides of the channel region can be low resistance offset regions,
This eliminates the need for an ion implantation step for forming an LDD region, which is a cause of instability of the characteristics, so that the manufacturing process can be simplified and the element characteristics can be stabilized.

The embodiments of the present invention have been described above. However, the present invention is not limited to the configuration described in each embodiment, and various modifications are possible. For example, the target of crystallization is not limited to an amorphous silicon film, but may be a polycrystalline silicon film having low crystallinity formed by a low pressure chemical vapor deposition (LPCVD) method or the like, or a microcrystal. A (micro crystal) silicon film may be used.

The material is not limited to silicon, but may be any semiconductor containing silicon as a main component containing another element such as Ge. For example, by adding Ge, a crystallized semiconductor thin film can be formed. The forbidden band width can be arbitrarily controlled, so that the light receiving portion of the thin film line sensor can be formed of a semiconductor having high sensitivity according to the wavelength of the light source.

In the description of each of the above embodiments, a transparent glass substrate is used as the substrate, but a quartz substrate may be used, and the substrate is not necessarily required to be transparent. Other insulating substrates having properties may be used.

In the description of each of the above embodiments, the Xe-Cl excimer laser is used as the laser, but other excimer lasers may be used.
Further, an Ar laser may be used, and in any case, a laser beam having a wavelength easily absorbed by the non-single-crystal semiconductor thin film to be crystallized may be used.

In the description of each of the above embodiments, a base SiO ₂ film is provided on a glass substrate.
Although an amorphous silicon film is provided on the iO ₂ film,
An amorphous silicon film may be directly deposited on a glass substrate.

In the description of each of the above embodiments, the SiO ₂ film pattern is used as the insulating film pattern serving as the anti-reflection film. However, the present invention is not limited to the SiO ₂ film, but may be any other material such as a SiN film. May be used as long as the film is transparent to the wavelength of the laser light to be irradiated.

The thickness d of the antireflection film is also expressed as d
≒ λ / 4n is most effective, but is not limited to this, and it is better if the reflectance is smaller than that of the portion without the antireflection film.

In the description of each of the above embodiments, laser irradiation is performed with the substrate temperature kept at room temperature. However, the crystal grain size depends on the thickness of the amorphous silicon film, the irradiation energy density, and the substrate temperature. Because it depends
By performing laser irradiation while the substrate is heated,
The overall crystal grain size may be further increased.
The upper limit of the substrate temperature in this case is a temperature that the glass substrate or the like can withstand, and is usually 400 ° C. or less.

In the above description of the first and second embodiments, the crystal grain boundary exists at the center of the channel region. However, it is necessary to set the gate electrode to 1 μm or less and select a region where the gate electrode is provided. Accordingly, in the channel region, the crystal grain boundary may not exist in the channel length direction, thereby further improving the characteristics of the TFT.

[0065] In the third embodiment described above, but after forming the amorphous silicon island pattern to form a SiO ₂ film pattern, like the first embodiment described above, the SiO ₂ film After pattern formation and laser irradiation, patterning into an island pattern may be performed.

In the third embodiment, the SiO ₂ film pattern 22 is used as it is as the gate insulating film. However, after removing the SiO ₂ film pattern 22, a new SiO ₂ film or SiN film is formed. A film may be deposited to form a gate insulating film.

In the third embodiment, the ion implantation is not performed and the offset portion is used.
The ion implantation for forming the LDD region may be performed. Since the crystallinity of the portion to be implanted is uniform and the quality is high, the resistance value after the implantation is stable.

In each of the above embodiments, a method of growing a high quality polycrystalline silicon film for forming a TFT for an active matrix type liquid crystal display device has been described. The present invention is not limited to polycrystalline silicon films for liquid crystal display devices, but also covers polycrystalline silicon films used for thin film semiconductor devices for other uses such as thin film semiconductor devices for line sensors. The element formed in the region is not limited to the TFT, and another semiconductor element such as a diode may be formed.

[0069]

According to the present invention, after an insulating film pattern is formed at an arbitrary position, laser irradiation is performed to crystallize the insulating film pattern from the end to the center, thereby forming a non-conductive portion under the insulating film pattern. Since a single-crystal silicon film is converted to a high-quality polycrystalline silicon film, a polycrystalline silicon film with a large crystal grain size cannot be formed over a large area. A high-quality polycrystalline silicon film can be obtained with good reproducibility, and thereby, a high-performance T
A thin film semiconductor device such as an FT can be manufactured with high productivity, which greatly contributes to high image quality, high definition, and low cost of an active matrix type liquid crystal display device and the like.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a basic configuration of the present invention.

FIG. 2 is an explanatory diagram of a manufacturing process partway through the first embodiment of the present invention.

FIG. 3 is an explanatory view of a manufacturing process of the first embodiment of the present invention after FIG. 2;

FIG. 4 is an explanatory diagram of Raman shift of a silicon thin film according to the first embodiment of the present invention.

FIG. 5 is an explanatory diagram of a manufacturing process partway through a second embodiment of the present invention.

FIG. 6 is an explanatory diagram of a manufacturing process of the second embodiment of the present invention after FIG. 5;

FIG. 7 is an explanatory diagram of a manufacturing process partway through a third embodiment of the present invention.

FIG. 8 is an explanatory view of the manufacturing process of the third embodiment of the present invention after FIG. 7;

FIG. 9 is an explanatory diagram of Raman shift of a silicon thin film according to a third embodiment of the present invention.

FIG. 10 is an explanatory diagram of a change in Raman shift in a beam scanning direction.

FIG. 11 is an explanatory diagram of Raman shift when a SiO ₂ cap is provided.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 Insulating substrate 2 Non-single-crystal semiconductor thin film 3 Insulating film pattern 4 Laser light 5 Polycrystalline region 6 Crystallized region 11 Glass substrate 12 Base SiO ₂ film 13 Amorphous silicon film 14 SiO ₂ film 15 SiO ₂ film pattern 16 Excimer laser light Reference Signs List 17 silicon island pattern 18 polycrystalline silicon region 19 crystallized silicon region 20 crystal grain boundary 21 amorphous silicon island pattern 22 SiO ₂ film pattern 23 crystallized silicon region 24 gate electrode 25 low resistance region

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasuyoshi Mishima 4-1-1, Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa F-term within Fujitsu Limited (reference) 5F052 AA02 AA11 BB01 BB07 CA04 DA02 DB03 EA02 EA11 FA27 JA01 5F110 AA01 BB01 CC01 DD02 DD03 DD13 FF02 FF30 GG02 GG13 GG16 GG25 GG28 GG45 PP04 PP11 PP24 QQ04 QQ09

Claims (8)

[Claims] 1. After forming a non-single-crystal semiconductor thin film containing silicon as a main component on an insulating substrate, an insulating film pattern is selectively formed on the non-single-crystal semiconductor thin film.
A method of crystallizing a semiconductor thin film, comprising irradiating a laser beam to crystallize the non-single-crystal semiconductor thin film from an end to a center of the insulating film pattern. 2. The method according to claim 1, wherein the line width of the insulating film pattern is 5 μm or less. 3. The method according to claim 2, wherein the non-single-crystal semiconductor thin film is processed into an island pattern before providing the insulating film pattern. 4. The method according to claim 1, wherein a line width of the insulating film pattern is larger than a channel length of the thin film transistor by at most 4 μm. 5. A semiconductor device using a crystallized semiconductor thin film by the method of crystallizing a semiconductor thin film according to claim 1, wherein a crystallized region immediately below the insulating film pattern is an active region. A semiconductor device characterized by being used as a semiconductor device. 6. The semiconductor device according to claim 5, wherein at least a part of a crystallization region immediately below said insulating film pattern is used as a channel region of a thin film transistor. 7. The semiconductor device according to claim 6, wherein only two or less crystal grains exist in a channel length direction of said channel region. 8. A semiconductor device using a crystallized semiconductor thin film according to the method for crystallizing a semiconductor thin film according to claim 4.
A semiconductor device, wherein a region adjacent to a channel region at a central portion of a crystallization region immediately below the insulating film pattern and having a crystal grain size larger than the crystal grain size of the channel region is an electric field relaxation region.