JP2003178978A - Crystalline semiconductor thin film, and method for forming the crystalline semiconductor thin film and apparatus for forming the crystalline semiconductor thin film, and mask for forming the crystalline semiconductor thin film, and further semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To ensure a high carrier mobility in perpendicular directions by forming a wide area single crystal region in a shorter processing time upon forming a crystalline semiconductor thin film by irradiating a semiconductor thin film with a laser beam and melting and solidifying the semiconductor thin film. <P>SOLUTION: A mask including a lattice shaped transparent section and a rectangular optical shielding section is disposed on an irradiation path for a laser beam. Lateral growth nuclei are ensured along a boundary 25e between a complete molten regions 25b to 25d and a non-molten region 25a, and the lateral growth is controlled mutually perpendicularly to form a crystal region 25d composed of four rectangular single crystal grains 25g. A mask optical shielding section is moved into the crystal region 25d, which is irradiated with a laser beam to obtain crystal growth using the single crystal grains 25g as nucleus. Hereby, rectangular single crystal grains partitioned in <100> and <010> directions with subintergranular regions are formed without any gap over the entire surface of a substrate continuously by the arbitrary number. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is formed by irradiating an amorphous semiconductor thin film provided on an insulating substrate with an energy beam to melt it, and then solidifying the melted amorphous semiconductor film. The present invention relates to a crystalline semiconductor thin film, a method for forming the same, a device for forming the crystalline semiconductor thin film, a mask for forming the crystalline semiconductor thin film, and a semiconductor device. In particular, the crystalline semiconductor thin film of the present invention is effective for a semiconductor device using a thin film transistor (TFT) provided on an insulating substrate, and is useful for an active matrix liquid crystal display device, a contact image sensor, a three-dimensional IC, etc. Can be used.

[0002]

2. Description of the Related Art Recently, in order to realize a large-sized liquid crystal display device capable of high-resolution display, a contact-type image sensor capable of high-speed operation and high-resolution display, and a semiconductor device such as a three-dimensional IC. Attempts have been made to form high-performance semiconductor elements on an insulating substrate made of glass or the like.
As such a semiconductor element, a TFT formed of a thin film silicon semiconductor is usually used.
The thin film silicon semiconductor is an amorphous silicon semiconductor (a
-Si) and a silicon semiconductor having crystallinity. As a crystalline silicon semiconductor, a polycrystalline silicon semiconductor, a microcrystalline silicon semiconductor, or the like is known.

Amorphous silicon semiconductor thin films are the most commonly used because they have a low formation temperature, can be formed relatively easily by a vapor phase method, and have excellent mass productivity. There is. However, since the amorphous silicon semiconductor thin film is inferior in physical properties such as conductivity to the crystalline silicon semiconductor thin film, in order to obtain a semiconductor device capable of operating at higher speed, a crystalline silicon semiconductor film is used. It is desired to establish a method for forming a semiconductor thin film on an insulating substrate such as glass.

As a method for forming a crystalline silicon semiconductor thin film on an insulating substrate such as a glass substrate,
(1) At the time of film formation, a crystalline silicon semiconductor thin film is directly formed on the substrate. (2) An amorphous silicon semiconductor thin film is formed on the substrate and solid phase growth is performed by applying heat energy. (3) Amorphous silicon semiconductor thin film is formed on the substrate by irradiating with strong light to melt, and then the melted amorphous silicon semiconductor film is solidified. There is known a method of forming a crystalline silicon semiconductor thin film by performing the above.

However, in the above method (1), crystallization progresses at the same time as the film forming step. Therefore, in order to obtain a crystalline silicon semiconductor thin film having a large grain size, it is necessary to form a thick crystalline silicon semiconductor thin film. There is. However, it is technically difficult to form a thick crystalline silicon semiconductor thin film having good semiconductor properties over the entire surface of the substrate.

The method (2) has an advantage that it can be applied to a large-area substrate, but in order to crystallize the amorphous silicon semiconductor thin film, it is performed at a high temperature of 600 ° C. or higher for several tens of hours. There is a problem in that heat treatment needs to be performed and the treatment time becomes long. Further, in the above method (2), since the solid phase crystallization phenomenon is utilized, the crystal grains spread parallel to the substrate surface. In this case, the grain size of the crystal grain is several μ
When it reaches m, the grown crystal grains may collide with each other to form grain boundaries. Since such a grain boundary functions as a trap level for carriers,
Mobility may be reduced.

On the other hand, in the above method (3), since the crystallization phenomenon in the melting and solidification process is utilized, it is possible to obtain crystal grains having a small grain size, and the grain boundaries are well treated and thus high in grain size. A crystalline silicon semiconductor thin film of high quality can be obtained. Further, for example, when an amorphous silicon semiconductor thin film is crystallized by irradiating a pulsed laser beam with an excimer laser which is most commonly used at present, the amorphous silicon is locally In this case, the melting time becomes extremely short, and the temperature of the locally melted region does not reach the substrate. Therefore, since the substrate does not have a high temperature and an inexpensive glass substrate can be used as the insulating substrate,
A large semiconductor device can be manufactured economically.

As a method of the above (3), for example, TS
ashima, S .; Usui and M.S. Seki
ya, IEEE Electron Dev. Let
t. , EDL-7, 276, 1986, "XeCl e.
xcimer laser annealing used
in the fabrication of pol
For y-Si TFT's ", an amorphous silicon semiconductor thin film provided on a glass substrate is irradiated with a pulsed excimer laser having a large output to heat and melt the amorphous silicon semiconductor film. Then, a technique of forming a crystalline silicon semiconductor thin film by solidifying the melted silicon semiconductor film and then manufacturing a TFT using the crystalline silicon semiconductor film is disclosed.

In such a method, the laser beam with which the silicon semiconductor thin film is irradiated is usually set to have an energy density such that the upper part of the silicon semiconductor thin film is partially melted. The relationship between the energy density and the crystal grain size to be formed has been studied in detail, and it has been clarified that as the energy density of the laser beam increases, the crystal grain size of the formed crystalline silicon semiconductor film also increases. ing. Therefore, the energy density of the laser beam is set based on the crystal grain size of the crystalline silicon semiconductor film to be formed.

J. S. Im et al. , Appl. P
hys. Lett. , 63, 1969, (199
3), "Phase transformation m
echanims involved in exci
mer laser crystallization o
f amorphous silicon film
s. “When the silicon semiconductor film is melted by irradiation with a laser beam, the melted portion is just before reaching the lower interface of the silicon semiconductor thin film, that is, the silicon semiconductor thin film is slightly smaller than the film thickness. It is described that a huge crystal grain of up to several μm is formed by melting over a thickness. Thus, when a silicon semiconductor film is melted over a depth slightly smaller than its film thickness, In the vicinity of the interface on the lower side of the silicon semiconductor thin film, the crystal grains slightly remain without being melted, and the crystal grains serve as seeds (nucleus) for crystal growth to grow large crystal grains.

From this, the energy density of the laser beam with which the silicon semiconductor thin film is irradiated is determined by the depth of the silicon semiconductor thin film melted by the laser beam.
Larger crystal grains can be formed by setting the thickness to be slightly smaller than the film thickness. However, in this case, if the energy density of the laser beam becomes slightly higher than a preset value, the silicon semiconductor thin film may be completely melted to the lower interface. As described above, when the silicon semiconductor thin film is completely melted, the melted silicon semiconductor film is rapidly cooled thereafter, so that nuclei of crystal growth are randomly generated and crystal grains are extremely broken. There is a possibility that it will become very small, or that it will become amorphous again.

Therefore, the energy density of the laser beam when the silicon semiconductor film is melted is such that, in consideration of the fluctuation of the laser output, there is a portion of the silicon semiconductor thin film which is not melted over an appropriate thickness due to the lower interface. Must be set to remain. However, if the energy density of the laser beam is set in this way,
Large crystal grains may not be formed, and the grain size of the obtained crystal grains may be as small as several hundred nm.

The mass-produced polycrystalline silicon semiconductor thin film is
Usually, the silicon semiconductor thin film is manufactured by irradiating the silicon semiconductor thin film in a pulsed manner with a low-temperature energy density so as not to melt the vicinity of the lower interface of the silicon semiconductor thin film. The crystalline silicon semiconductor thin film formed under such conditions is TF
The carrier mobility when T is 150 cm ² / Vs for the n-ch TFT and 80 c for the p-ch TFT.
It becomes m ² / Vs.

A TFT having such carrier mobility is used in a liquid crystal panel having a built-in peripheral driving circuit. By forming a higher quality polycrystalline silicon semiconductor thin film, a circuit element having multiple functions is formed. And to integrate such circuit elements on an active matrix TFT substrate.

In order to form a polycrystalline silicon semiconductor thin film of higher quality, when the silicon semiconductor thin film is melted by laser beam irradiation and then solidified to be crystallized, the silicon semiconductor thin film is formed in the film thickness direction. Completely melt, and suppress the generation of random nuclei,
Furthermore, crystal growth in a direction parallel to the substrate surface (referred to as lateral growth or lateral growth) may be controlled by some method. By such a method, the number of crystal grains increases, so that a high-quality polycrystalline silicon semiconductor thin film can be obtained, and a TFT having characteristics comparable to those when a single crystal substrate is used can be obtained.

For example, R. Sposili and J.
Im, Appl. Phys. Lett. 69, p286
4, 1996, "Sequential latera"
l solidification of thin si
licon films on SiO ₂ . “When the amorphous silicon semiconductor film is irradiated with a pulsed laser beam to be melted, the laser beam is applied so that the region to be melted by one irradiation is only the lateral growth region. By irradiating the laser beam repeatedly so that the irradiation region is limited to about several μm and the irradiation region of the next laser beam slightly overlaps with the previous irradiation region,
A method of growing elongated crystals elongated in one direction is described. This method is based on SLS (Sequentia).
(Lateral Solidification), which is basically a method of combining crystallization by pulsed laser and lateral growth, but the laser beam is twice to 3 times as large as the lateral growth by one irradiation. It is characterized in that it is squeezed down to about twice as thin as before.

In addition, C.I. Oh, M. Ozawa and
M. Matsumura, Jpn. J. Appl. Ph
ys. 37, L492, (1998), "A novel
l phase-modulated excimer-
Laser crystallization meth
od of silicon thin films. "In order to form a single crystal region by controlling the heat conduction by controlling the intensity distribution of the laser beam using a phase shift mask when the silicon semiconductor thin film is completely melted in the thickness direction. Is listed.

Furthermore, A. Hara et al. , Te
mechanical digest of2000 IED
M, "Selective single-Cryst
alliline silicon growth at th
e pre-defined active regio
ns of TFT's on a glass by as
canning CW laser irradiati
on. Describes a method for controlling heat conduction by forming a silicon semiconductor thin film into an island.

However, in the above method of controlling the heat conduction when the silicon semiconductor thin film is completely melted, it is not easy to generalize the conditions depending on the light intensity distribution, the sample shape, etc., and it is suitable for mass production. Not not. Furthermore, these techniques have not been considered to secure a crystal that serves as a nucleus when laterally growing a silicon semiconductor thin film, as compared with SLS, and therefore, what single crystal region is arranged on a substrate There is no clear indication as to whether or not it will be done.

[0020]

The crystal obtained by the above-described SLS has a tendency that the longitudinal direction is oriented in the <100> direction, and by forming a channel of a TFT in a direction parallel to the <100> direction, An extremely high carrier mobility can be obtained. However, <100>
In the direction perpendicular to the direction, the grain size of the crystal grains is as small as about 0.5 μm, and the crystal orientation is random, so <100>
The carrier mobility is also about 1/3 as compared with the case where the TFT channel is formed in the direction.

Further, in SLS, by irradiating the laser beam in one direction with a width of about several μm,
Since the lateral growth in one direction is repeated, there is a problem that the processing time is long.

Further, in the SLS using a normal linear laser beam, the grain boundaries are formed in a state parallel to the laser scanning direction, but not strictly parallel, an angle of about 10 degrees. It is often inclined at. In this way, when the scanning direction of the laser beam is not parallel,
Since the grain boundaries of the formed crystal grains are disturbed, the single crystal silicon semiconductor film cannot be formed into a uniform flat surface. Therefore, using such a single crystal silicon semiconductor film, T
When the FT is formed, there is a problem that the TFT characteristics vary depending on the formed portion. In order to prevent the TFT characteristics from varying, it is necessary to enhance the linearity of the grain boundary and control the position where the grain boundary is formed.

As one method for enhancing the linearity of grain boundaries and controlling their positions, Japanese Patent Publication No. 2000-505241 discloses that a laser beam scanning region is shaped into a mountain shape by using a mask to form a single crystal. Is disclosed.

According to this method, a laser beam is applied to the silicon semiconductor film to melt the silicon semiconductor film, and then the silicon semiconductor film is solidified and crystallized.
The laser beam scans so that the trailing edge located on the side opposite to the scanning direction is concave with respect to the melting region (scanning direction). By such a method, crystal growth of each laser beam occurs from the central portion in the width direction of the irradiation region toward both sides, generation of random nuclei is suppressed, and a large single crystal region is formed.

However, the above publication does not describe the experimental results obtained when the scanning area of the laser beam is shaped into a mountain shape using a mask, and specific numerical values for the laser beam and the melting area.

In Japanese Patent Application No. 2001-222986, in order to improve the linearity of grain boundaries, to control the position where grain boundaries are formed with high accuracy, and to increase the interval between grain boundaries, It is described that the melting region of the semiconductor film is scanned in a sawtooth (zigzag) shape. Further, by completely controlling the crystal orientation of the thin film formed by SLS, it is possible to form a pseudo single crystal thin film which has a small in-plane direction dependence of TFT characteristics and can form a higher performance TFT. Have been described.

Specifically, in order to control the position and crystal orientation of grain boundaries, the shape of the laser beam applied to the silicon semiconductor film is a linear shape bent in a zigzag (saw tooth) shape, and each bend The line width of the laser beam is 1 μm in order to make the angle of the part about 90 ° and the predetermined lateral growth distance
It is described that the interval between adjacent bent portions is set to 15 μm or less so that a sub-grain boundary is not formed in the crystal grain.

In SLS, in order to make the molten region in the silicon semiconductor film have a predetermined shape, a mask having a light-transmitting portion having a predetermined shape is provided in the optical path of the laser beam, and the light-transmitting portion of the mask is passed through. The simplest method is to irradiate the silicon semiconductor film with the laser beam. As described above, the irradiation region of the laser beam is shaped using the mask, whereby the molten region of the silicon semiconductor film can be formed into a predetermined shape.

In the silicon semiconductor film, in order to use the mask to form the melted region into a predetermined shape, the shape of the transparent portion of the mask that is actually required should be formed by the configuration of the optical system or the like. It differs from the shape of the fusion zone.

For example, in a projection system with a magnification of 1: 1, the pattern of the light-transmitting portion in the mask is projected on the surface of the silicon semiconductor film with the same size, and thus the size of the melted region of the silicon semiconductor film is the same. The transparent portion is formed on the mask. On the other hand, in the reduction projection optical system having the magnification of 5: 1, the size of 1 μm on the silicon semiconductor film becomes 5 μm in the mask.

When the silicon semiconductor film is irradiated with a laser beam and the light transmitting portion of the mask is a zigzag (saw tooth) slit, a light proximity effect occurs at each bent portion of the zigzag light transmitting portion. However, there is a problem that the laser beam applied to the silicon semiconductor film does not completely match the pattern of the transparent portion of the mask.

That is, the laser beam that has passed through each bent portion bent at a predetermined angle in the light-transmitting portion of each mask is irradiated onto the silicon semiconductor film in a state of being curved in an arc shape. As described above, when the irradiation region of the laser beam on the silicon semiconductor film is different from the shape of the light transmitting portion of the mask, the crystal orientation is individually controlled when the crystal grains are formed by the irradiation of the laser beam. It may not be possible.

The laser beam passing through the zigzag light-transmitting portion of the mask may have a significantly high light intensity at the center of each bent portion on the silicon semiconductor film. In this case, there is a problem in that a Si film skip, which separates the silicon semiconductor film, occurs in the central portion of the bending down where the light intensity is significantly increased.

FIG. 18 is a graph showing the result of simulating the light intensity of the bent portion when the laser beam is applied to the silicon semiconductor film through the slit-shaped light transmitting portion bent in the zigzag shape in the mask. is there. In the graph of FIG. 18, the vertical axis and the horizontal axis indicate the position on the silicon semiconductor film.
The 0 scale is 2 μm.

6 to 16 scales on the horizontal axis and S6 to S16 on the vertical axis
The portion surrounded by the scale (enclosed by a thick line) corresponds to the shape of the bent portion in the zigzag light-transmitting portion of the mask, and is a design irradiation area of the laser beam on the silicon semiconductor film. . In addition, a portion where the density of the described points is high indicates that the light intensity is high.

According to the graph of FIG. 18, the laser beam is curved in an arc shape with respect to each of the outer and inner corners of the bent portion of the zigzag light-transmitting portion of the mask which are at right angles. And does not completely match the shape of the transparent portion of the mask. Further, the light intensity at the central portion of the bent portion is 1.2 to 1.4 times as high as the light intensity when the slit is not provided.

FIG. 19 is a photomicrograph of a bent portion when a laser beam is applied to the silicon semiconductor film through a slit-shaped light transmitting portion bent in a zigzag shape in the mask. According to the photomicrograph of FIG. 19, the Si film jump 61 is formed on the surface portion of the silicon semiconductor film corresponding to the central portion of the bent portion in the transparent portion of the mask.

The present invention solves such a problem, and an object thereof is to irradiate an amorphous semiconductor thin film provided on an insulating substrate with an energy beam to melt the amorphous semiconductor thin film, and then melt it. When a crystalline semiconductor thin film is formed by solidifying an amorphous semiconductor film, a single crystal region having a larger area can be efficiently formed, and high carrier mobility can be obtained in any of the directions orthogonal to each other. To provide a high-performance crystalline semiconductor thin film and a method for forming the same, a forming apparatus and a semiconductor device for the same, and a mask used for forming the crystalline semiconductor thin film.

[0039]

The crystalline semiconductor thin film of the present invention is composed of a plurality of rectangular crystal grains, and adjacent crystal grains have subgrain boundaries along the <100> direction and the <010> direction, respectively. The above-mentioned objects are achieved.

A plurality of the rectangular crystal grains may be arranged on the substrate in a continuous manner or in an arbitrary number continuously or over the entire surface without any space therebetween.

The method for forming a crystalline semiconductor thin film of the present invention is
A method for forming a crystalline semiconductor thin film by irradiating an amorphous semiconductor thin film provided on an insulating substrate with an energy beam to melt and then solidifying the amorphous semiconductor thin film. By irradiating an energy beam, a rectangular unmelted region or a partially melted region is formed in a matrix shape at regular intervals along the row direction and the column direction, and a completely melted region is formed in a lattice shape. By laterally growing from the boundary between the completely melted region and the unmelted region or the completely melted region and the partially melted region toward the completely melted region, the unmelted region or the partially melted region adjacent to each other and the vertical direction Completely melted area located between unmelted areas or partially melted areas adjacent to each other and completely melted area located between horizontally adjacent unmelted areas or partially melted areas A rectangular completely melted region surrounded by, forming a rectangular crystal region consisting of four rectangular single crystal grain, the objects can be achieved.

The method for forming a crystalline semiconductor thin film according to the present invention is
A method of forming a crystalline semiconductor thin film by irradiating an amorphous semiconductor thin film provided on an insulating substrate with an energy beam to melt and then solidifying the amorphous semiconductor thin film. Irradiation is performed to form rectangular unmelted regions or partially melted regions in a matrix form at regular intervals along the row direction and column direction, and also to form completely melted regions in a grid pattern to complete melting. By laterally growing from the boundary between the region and the unmelted region or the completely melted region and the partially melted region toward the completely melted region, the unmelted region or the partially melted region adjacent to each other is vertically adjacent A completely melted region located between the unmelted or partially melted regions and a completely melted region located between the horizontally adjacent unmelted or partially melted regions. In the enclosed rectangular completely melted region, a first step of forming a rectangular crystal region composed of four rectangular single crystal grains, and irradiating the semiconductor thin film with an energy beam, In the formed rectangular crystal region, a rectangular unmelted region or a partially melted region is formed, and a completely melted region is formed in a lattice pattern, and the completely melted region and the unmelted region or the completely melted region are formed. The second step of expanding and growing each rectangular single crystal grain by growing the crystal from the boundary with the partially melted region toward the completely melted region, thereby achieving the above object.

In the irradiation path of the energy beam, rectangular masking portions are provided in a matrix form at regular intervals along the row direction and the column direction, and a mask having the shielding portions arranged in a grid pattern is arranged. Forming rectangular metal thin films or second semiconductor thin films in a matrix on the semiconductor thin film at regular intervals along the row direction and the column direction, or forming rows on the semiconductor thin film. By providing an antireflection film in which rectangular openings are provided in a matrix at regular intervals along the row and column directions, a rectangular interval is provided at regular intervals along the row and column directions. The unmelted region or the partially melted region can be formed in a matrix, and the completely melted region can be formed in a lattice.

The light-shielding portion of the mask, the metal thin film or the second semiconductor thin film, or the length of one side of the opening portion of the antireflection film is set so that the light-shielding portion of the adjacent mask, the reflection film,
Alternatively, it is set to be smaller than the distance between the openings of the antireflection film, and the light shielding portion of the mask, the metal thin film or the second semiconductor thin film, or the antireflection film is formed in the first step and the second step. The opening of the film is moved in the X direction and the Y direction by (length of one side + spacing) / 2, respectively, and the mask, the metal thin film or the second semiconductor thin film,
Alternatively, the antireflection film can be provided.

By moving the beam mask holder holding the mask in the first step and the second step, the light shielding portion of the mask can be moved in the X and Y directions, respectively. .

The method for forming a crystalline semiconductor thin film of the present invention is
A method for forming a crystalline semiconductor thin film by irradiating an amorphous semiconductor thin film provided on an insulating substrate with an energy beam to melt the amorphous semiconductor thin film, and then solidifying the amorphous semiconductor thin film. Alternatively, a light-transmitting portion or a light-shielding portion having a plurality of right-angled bent portions is provided,
By arranging a mask provided with an OPC pattern at a corner tip of the right-angled bent portion, a melted region of the semiconductor thin film is formed, and a melted region having one or more right-angled bent portions is formed. The above object is achieved by the above.

A mask having a sawtooth light-transmitting portion and an OPC pattern provided at the apex of the sawtooth is used, or a rectangular light shield is provided at regular intervals along the row and column directions. It is possible to use a mask in which the parts are provided in a matrix, the light-transmitting parts are provided in a lattice, and the OPC pattern is provided at the apex of the lattice.

The OPC pattern has a square shape,
It is possible to use a mask in which the offset h of the OPC pattern and the length g of one side of the OPC pattern satisfy the relationship of (-1/2) * g <h <(1/2) * g.

Using the mask provided with the sawtooth light-transmitting portion, the completely melted region of the semiconductor thin film has a line width a of 1
It is desirable to form them in a saw-tooth shape with a pitch angle of 5 μm or more and 5 μm or less, an apex angle b of approximately 90 °, and a spacing c of each vertex of 15 μm or less.

The OPC pattern has a square shape,
It is desirable to use a mask in which the length g of one side of the OPC pattern is ⅕ or more and ½ or less of the line width d of the sawtooth light-transmitting portion.

Using the mask provided with the saw-toothed light-transmitting portion, the energy beam is irradiated with the intensity adjusted so that the semiconductor thin film is completely melted in the film thickness direction, and one shot is taken for each shot. It is desirable to move the semiconductor thin film or the energy beam in a certain direction by a distance smaller than the lateral growth distance formed in the melted region to cause crystal growth in one direction.

Using the mask provided with the above-mentioned lattice-shaped light-transmitting portion, the melted region of the semiconductor thin film has a line width L of 2 μm.
Formed in a lattice shape having a size of 5 μm or less, and the unmelted region,
It is desirable to form a rectangular shape in which the length S of one side is smaller than L.

The OPC pattern has a square shape,
It is desirable to use a mask in which the length g of one side of the OPC pattern is 1/5 or more and 1/2 or less of the length j of one side of the rectangular light-shielding portion.

The length j of one side of the light-shielding portion in the mask provided with the lattice-like light-transmitting portion is set to be smaller than the interval i between the openings of the light-shielding portion of the mask so that the mask has almost the same area. Irradiating the energy beam twice through the mask,
It is desirable to dispose the mask by moving the light shielding portion of the mask by (i + j) / 2 in the X direction and the Y direction between the first irradiation and the second irradiation.

The crystalline semiconductor thin film of the present invention is a crystalline semiconductor thin film formed by the method for forming a crystalline semiconductor thin film of the present invention, and is composed of a plurality of rectangular crystal grains, and adjacent crystal grains are <100> direction or <110
It is divided by sub-grain boundaries along the> direction, and the plurality of rectangular crystal grains are arranged on the substrate in a continuous manner or in an arbitrary number continuously or over the entire surface, whereby The above object is achieved.

The crystalline semiconductor thin film of the present invention is a crystalline semiconductor thin film formed by the method for forming a crystalline semiconductor thin film of the present invention, and is composed of a plurality of rectangular crystal grains, and adjacent crystal grains are <100> direction and <010
Are separated by sub-grain boundaries along each of the> directions, and the plurality of rectangular crystal grains are arranged on the substrate in a continuous manner or in an arbitrary number continuously or over the entire surface without any gaps between them. The above object is achieved by the above.

The semiconductor device of the present invention uses the crystalline semiconductor thin film of the present invention and has a transistor in which the channel direction from the source to the drain is parallel to the <100> direction and <0>.
A transistor parallel to the 10> direction is provided,
Thereby, the above object is achieved.

The apparatus for forming a crystalline semiconductor thin film of the present invention is
An apparatus for forming a crystalline semiconductor thin film by irradiating an amorphous semiconductor thin film provided on an insulating substrate with an energy beam to melt and then solidifying the amorphous semiconductor thin film,
A light-transmitting body that includes a stage on which a substrate provided with an amorphous semiconductor thin film is mounted and an energy beam source that generates an energy beam, and has one or more right-angled bent portions in an irradiation path of the energy beam. A mask having an OPC pattern is provided at the corner tip of the bent portion at a right angle, and the above-mentioned object is achieved thereby.

The mask for forming a crystalline semiconductor thin film of the present invention irradiates an amorphous semiconductor thin film provided on an insulating substrate with an energy beam to melt and then solidify the crystalline semiconductor thin film. A mask, which is arranged in the irradiation path of the energy beam during formation, is provided with a light-transmitting portion or a light-shielding portion having one or more right-angled bent portions, and a corner tip of the right-angled bent portions. Is provided with an OPC pattern, which achieves the above object.

A saw-toothed light-transmitting portion is provided and an OPC pattern is provided at the apex portion of the sawtooth, or rectangular light-shielding portions are arranged in a matrix at regular intervals along the row and column directions. It is possible to adopt a configuration in which the light-transmitting portion is provided in a lattice shape and the OPC pattern is provided at the apex portion of the lattice.

The OPC pattern has a square shape,
It is desirable that the offset h of the OPC pattern and the length g of one side of the OPC pattern satisfy the relationship of (-1/2) * g <h <(1/2) * g.

The OPC pattern has a square shape,
The length g of one side of the OPC pattern is 1/5 or more and 1/2 or less of the line width d of the sawtooth light-transmitting portion, or
It is desirable that the length g of one side of the OPC pattern is 1/5 or more and 1/2 or less of the length j of one side of the rectangular light-shielding portion.

In the present specification, among the crystal grain boundaries, those having a small deviation in crystal orientation between the crystal grains in contact with each other are called subgrain boundaries.

The operation of the present invention will be described below.

According to the present invention, a method for forming a crystalline semiconductor thin film by irradiating an amorphous semiconductor thin film provided on an insulating substrate with an energy beam to melt and then solidify the amorphous semiconductor thin film is used. By arranging the melted area and the unmelted area or the completely melted area and the partially melted area in contact with each other, the boundary between the completely melted area and the unmelted area, or the boundary between the completely melted area and the partially melted area A crystal that serves as a nucleus (seed) for lateral growth can be secured in the portion. In addition, rectangular unmelted regions or partially melted regions are formed in a matrix shape at regular intervals along the row direction and the column direction, and a grid-shaped completely melted region is formed to form a rectangular completely melted region. And the unmelted region, or the boundary between the completely melted region and the partially melted region, are laterally grown toward the completely melted region, and thus, in the vertical direction with the unmelted region or the partially melted region adjacent to each other. A rectangular completely melted area surrounded by a completely melted area located between adjacent unmelted areas or partially melted areas and a completely melted area located between horizontally adjacent unmelted areas or partially melted areas To form a portion where the lateral growth regions orthogonal to each other intersect,
A rectangular crystal region composed of four rectangular single crystal grains can be formed.

Subsequently, the semiconductor thin film is irradiated with an energy beam to form a rectangular unmelted region or a partially melted region in the rectangular crystal region and a lattice-shaped completely melted region. Crystals grow from the boundary between the completely melted region and the unmelted region, or from the boundary between the completely melted region and the partially melted region, toward the completely melted region, with the rectangular single crystal grain that was first formed as the nucleus. However, the crystal grains obtained by enlarging each of the rectangular single crystal grains can be formed continuously or over the entire surface in any number without any gaps on the substrate.

In the crystalline semiconductor thin film thus obtained, adjacent crystal grains have <100> direction and <010>.
Since it is divided by sub-grain boundaries along each direction, a TFT provided with a channel direction from the source to the drain in a direction parallel to the <100> direction and a source to a drain in a direction parallel to the <010> direction. The respective characteristics can be made equal to those of the TFT provided with the channel direction toward which it goes.

For example, in the irradiation path of the energy beam,
A mask provided with a rectangular light-shielding portion and a lattice-shaped light transmitting portion is arranged, a rectangular metal thin film or a second semiconductor thin film is provided on the semiconductor thin film, or a rectangular metal thin film is formed on the semiconductor thin film. By providing the antireflection film having the shaped openings, it is possible to control the lateral growth regions orthogonal to each other.

Further, in the present invention, a lateral growth region is formed by inserting a mask having a light-transmitting portion or a light-shielding portion having one or more right-angled portions into the irradiation path of the energy beam. In the method of controlling, the serif (S
A mask provided with a fine OPC pattern called erif) is used. For example, in a mask provided with a sawtooth light-transmitting part, an OP having fine protrusions at the apex of the sawtooth is used.
The C pattern is provided. Further, in a mask in which a rectangular light-shielding portion is provided and a lattice-shaped light-transmitting portion is provided, an OPC pattern having fine protrusions is provided at the apex portion of the lattice.

By providing such an OPC pattern, it is possible to alleviate the concentration of light at the center of the corner portion of the beam shape bent at a right angle, and suppress the skipping of the Si film.

[0071]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 is a schematic view showing the state of crystal grains in the crystalline semiconductor thin film of Embodiment 1. This crystalline semiconductor thin film is composed of a plurality of rectangular crystal grains 1.
1 are arranged on the substrate continuously without gaps, in an arbitrary number, or over the entire surface. Adjacent crystal grains 11 are sub-grain boundaries along the <100> direction and the <010> direction, respectively. Separated by twelve.

Such a crystalline semiconductor thin film is, for example,
It is formed by irradiating a laser beam on an amorphous silicon semiconductor thin film formed on an insulating substrate.

FIG. 2 is a schematic block diagram of an apparatus for forming a crystalline semiconductor thin film used for forming such a crystalline semiconductor film. This forming apparatus includes an insulating substrate 10 on which an amorphous silicon semiconductor thin film, which is a crystalline semiconductor thin film, is formed.
And an XY stage 77 on which is mounted, and a laser oscillator 71 that oscillates a laser beam that is a laser beam with which the substrate 10 of the XY stage is irradiated.
The laser light emitted from the laser oscillator 77 is enlarged by the telescope 72 and the aspect ratio is adjusted. The laser light whose aspect ratio has been adjusted is given to the homogenizer 73.

The homogenizer 73 converts the intensity distribution of laser light from a Gaussian distribution to a uniform intensity distribution.
After that, the laser light is made into a long and narrow linear beam by the field lens 74 and applied to the mask 15. The mask 15 shapes an elongated linear beam into a predetermined beam shape, and the shaped laser beam is applied to the substrate 10 mounted on the XY stage 77 by the projection lens 76.

FIG. 3 is a schematic plan view of the metal mask 15 used in this forming apparatus. This mask 15
Square light-shielding portions 15a are arranged in a matrix at regular intervals along the row and column directions.
The lattice-shaped portion other than the light shielding portion 15a is a light transmitting portion 15b. Such a mask 15 is formed by forming a chromium thin film on a transparent quartz substrate and patterning it so that the plurality of light-shielding portions 15a remain in a matrix, as in a normal photomask. To be done.

A crystalline semiconductor thin film is formed by the apparatus for forming a crystalline semiconductor thin film shown in FIG. 2 in which such a mask 15 is provided in the laser beam irradiation path. When forming a crystalline semiconductor film, the substrate 10 on which an amorphous silicon semiconductor film is formed in advance is prepared. When a TFT is manufactured using a crystalline semiconductor thin film formed on a substrate, the thickness of this amorphous silicon semiconductor thin film is preferably 25 nm to 100 nm. In this embodiment, a 35 nm intrinsic (I) type amorphous silicon semiconductor thin film is formed on the substrate.

When a glass substrate is used as the insulative substrate 10, in order to prevent impurity diffusion from the glass substrate, a base coat film, for example, a film thickness, is formed at the interface between the glass substrate and the amorphous silicon semiconductor thin film. It is preferable to provide a 300 nm silicon oxide film.

The substrate 10 is mounted on the XY stage 77 of the apparatus for forming a crystalline semiconductor thin film shown in FIG. The laser light emitted from 71
The mask 15 forms a laser beam having a predetermined pattern and irradiates the amorphous silicon semiconductor thin film.

In this case, as the laser oscillator 71,
An excimer laser oscillator that can obtain high output is preferable,
In particular, a XeCl laser oscillator that can easily obtain a high output is preferable. As the laser oscillator 71,
Not limited to such a configuration, an excimer laser oscillator such as ArF, KrF, or XeF may be used. In this embodiment, the XeCl laser oscillator irradiates a laser beam of 308 nm.

The energy density of the laser beam emitted from the laser oscillator 71 is set to such a value that the amorphous silicon semiconductor thin film on the substrate 10 is completely melted in the film thickness direction. For example, in the case of a 45 nm amorphous silicon semiconductor thin film, the energy density is set to 430 mJ / cm ² or more.

FIG. 4 is a schematic plan view for explaining the state of the amorphous silicon semiconductor thin film when the amorphous silicon semiconductor thin film is irradiated with the laser beam through the mask 15. As shown in FIG. 4, the lattice-shaped region irradiated with the laser beam through the transparent portion 15b of the mask 15 is
The amorphous silicon semiconductor thin film is completely melted to become completely melted regions 25b to 25d, and the square region where the laser beam is not irradiated by the light shielding portion 15a of the mask 15 is an unmelted region 25a where the amorphous silicon semiconductor thin film does not melt. Becomes

As a result, the amorphous silicon semiconductor is explosively crystallized at the boundary 25e between the square unmelted region 25a and the lattice-shaped completely melted regions 25b to 25d to form fine crystal grains. Lateral growth occurs toward the completely melted regions 25b to 25d by using such crystal grains as crystal growth nuclei.

In this case, the completely melted region 25b located between the unmelted regions 25a vertically adjacent to each other and the completely melted region 25c located between the unmelted regions 25a horizontally adjacent to each other have a square shape. Unmelted area 2
Lateral growth occurs vertically on each side of 5a, and <010>
Crystal is grown in the <100> direction and the <100> direction.

On the other hand, four unmelted regions 25a adjacent to each other, a completely melted region 25b located respectively between the unmelted regions 25a vertically adjacent to each other in these four unmelted regions 25a, and a horizontal direction. Completely melted regions 25 respectively located between the adjacent unmelted regions 25a
In the square completely melted region 25d surrounded by c and 4 from each corner of the square unmelted region 25a.
Lateral growth occurs in the 5 ° direction.

As a result, the square completely melted region 2 is formed.
Within 5d, a square-shaped crystal region 25d composed of four square-shaped single crystal grains 25g, which are separated by sub-grain boundaries along the <100> direction and the <010> direction, is formed.

Next, as shown in FIG. 3, since the first laser beam irradiation, the pattern of the mask light-shielding portion 15a is set to the interval i between the mask light-shielding portions 15a in the mask 15 and one side of the light-shielding portion 15a. 1/2 of the total length of j
By moving ((i + j) / 2) respectively in the X direction and the Y direction, as shown in FIG. 5, the projection pattern 25f of the light shielding portion 15a is formed into a square crystal in which four square single crystal grains 25g are formed. The second laser beam irradiation is performed by arranging the laser beam at the center of the region 25d.

As a result, as shown in FIG. 6, lateral growth occurs toward the completely melted regions 25a to 25c with the square single crystal grains 25g already formed as nuclei. In this case, the completely melted area 25b and the completely melted area 25c
Then, lateral growth occurs perpendicularly to each side of the projection pattern 25f of the light shielding portion 15a of the mask 15, and <0
Crystals are grown in the 10> direction and the <100> direction.

As a result, each of the single crystal grains 25g shielded by the projection pattern 25f of the light shielding portion 15a is expanded and grown, and as shown in FIG. 1, over the entire surface of the substrate or continuously in an arbitrary number. , <100>
Boundaries 12 along the <10> and <10 10> directions, respectively
Crystal regions composed of rectangular single crystal grains, which are separated by, are formed without any gap.

In the mask 15, adjacent light-shielding portions 15
The interval i of a, that is, the width of the transparent portion 15b is determined based on the lateral growth distance that can be formed when one shot of the laser beam is irradiated. This lateral growth distance depends on many parameters such as the energy density of the irradiated laser light, the pulse width, the film thickness of the silicon semiconductor thin film, the substrate temperature, etc., and is generally 1 μm to
The value is about 5 μm.

As shown in FIG. 7, the projection pattern 15c of the rectangular light-shielding portion 15a is inclined at an angle of 45 ° from the corner.
Since it is necessary to maximize the distance G that grows in the direction,
Based on this, the width of the melted region = the interval L between the unmelted regions is L = 2 × G / √2. For example, 1 laser beam
If the lateral growth distance that can be formed by shot irradiation is 2 μm and if G is set to 2 μm, the tips of the laterally grown crystals collide with each other from the corners of the unmelted regions facing each other. Set and G
= 1.5 μm, L = 2 × G / √2 = 2 × 1.5
/ √2≈2 μm.

The above values are those when the mask pattern is projected on the surface of the semiconductor thin film, and in the projection system with a magnification of 1: 1 the light is shielded in accordance with the values on the mask 15 for beam shaping. Interval i of portion 15a = interval L of the unmelted region
However, in the reduction projection system, the values are different, and in the reduction projection system with a magnification of 5: 1, the size of 1 μm when projected on the surface of the semiconductor thin film corresponds to 5 μm on the mask 15.

When the crystal region is formed by one laser beam irradiation, the light shielding portion 15 in the mask 15 is formed.
As described above, if the interval i of a is set based on the relationship with the lateral growth distance that can be formed, the light shielding unit 1
The length j of one side of 5a can be freely set. However, in the case where a plurality of crystal regions are formed without gaps by irradiating the laser beam twice, the light shielding portion 1
The length i of one side of 5a is set to be smaller than the interval j of the light shielding portion 15a by a constant size m, and i = j−m.
This is because it is necessary to provide a light-shielding portion for the second laser beam irradiation inside the single crystal region formed for the first laser beam irradiation.

The value of m in this case is 0.1 μm to 0.5.
The size can be appropriately selected from a size of about μm, but √2 (m + S) with respect to the above G and the width S of the unmelted region.
<G relationship must be satisfied. For example, S = L
It can be set to −m = 2-0.4 = 1.6 μm. This value is also when the mask pattern is projected on the surface of the amorphous silicon semiconductor thin film, and the size of the mask pattern is set by the magnification of the projection system.

In this way, when forming a crystal region formed of rectangular single crystal grains, the required energy density is 0.5 J / cm ² and the output is 1 J.
Assuming that there is no energy loss in the optical system by using the laser beam, the rectangular beam is 14 mm ×
A laser beam having a size of 14 mm and a linear beam of about 300 mm × 0.66 mm can be formed.
Therefore, in this embodiment, the XY stage 77 on which the substrate 10 is mounted can be moved by a value of about 14 mm or 0.66 mm between the laser shots, and the laser beam is unidirectionally on the order of several tens of μm. The processing can be performed at an extremely high speed as compared with the conventional laser beam irradiation method of moving by.

After the first laser beam irradiation is performed over the entire surface of the large glass substrate in this way,
The beam mask holder can be moved in the X direction and the Y direction, and the second laser beam can be scanned in the same manner as in the first irradiation to irradiate the entire surface of the substrate. The movement of the beam mask holder in this case is, for example, (L + S) / 2 = (2 + 1.6) / 2 =
It is 1.8 μm. Therefore, in this embodiment, the conventional S
An apparatus having a highly accurate scanning system capable of moving at a fine pitch of about 1 μm, which is required in the LS method, is unnecessary, and an inexpensive apparatus can perform processing with high throughput.

According to the present invention, when the mask pattern is projected onto the surface of the semiconductor thin film, the rectangular and lattice-shaped corners formed on the surface of the semiconductor thin film are orthogonal to each other. It is important to form a crystal region of the following, and it is important to design the optical system so that such orthogonality of the corner portion can be realized on the surface of the semiconductor thin film.

Using the crystalline silicon semiconductor thin film formed as described above, a TFT can be manufactured by a usual method. Generally, when designing a circuit,
A plurality of TFTs are arranged such that the channel directions from the source to the drain are orthogonal to each other. Conventional SLS
In the method, as shown in FIG. 8A, the crystal grains are formed so as to extend in one direction (horizontal direction in FIG. 8A), so that the channel direction is arranged in a direction orthogonal to the crystal grain boundaries. TF
At T82, the TFT8 arranged in the direction parallel to the crystal grain
It is known that the device characteristics are significantly inferior to those of No. 1.

On the other hand, in this embodiment, as shown in FIG.
As shown in (b), 2
Since the rectangular single crystal grains are formed by dimensional growth, the transistor 83 whose channel direction is parallel to the <100> direction and the transistor 84 whose channel direction is parallel to the <010> direction have the same device characteristics. can get.

(Embodiment 2) FIG. 9 is a schematic cross-sectional view for explaining a method for forming a crystalline semiconductor thin film according to Embodiment 2. In the second embodiment, instead of the mask 15 in the first embodiment, a metal thin film 93 is formed on the amorphous semiconductor thin film 91 to form a rectangular shape at regular intervals along the row direction and the column direction. The unmelted region is formed in a matrix and the lattice-shaped completely melted region is formed.

First, similarly to the first embodiment, the insulating substrate 1
Amorphous silicon semiconductor thin film 91 is deposited on 0. TF
When producing T, it is preferable that the film thickness of the amorphous silicon semiconductor thin film 91 is 25 nm to 100 nm.

Next, a SiO ₂ film 92 is formed on the amorphous silicon semiconductor thin film 91. The film thickness of the SiO ₂ film 92 is not particularly limited, but the energy of the laser light is effectively set by setting the film thickness of the SiO ₂ film 92 so as to obtain an antireflection function for the laser light used. Can be used for. For example, when irradiating a 308 nm laser beam by a XeCl laser,
By setting the thickness of the SiO ₂ film 92 to 53 nm,
An antireflection function can be obtained.

Then, an Al film 93 is formed on the SiO ₂ film 92.
To form a film. The Al film 93 is used to reflect the laser light and is patterned into a shape corresponding to the light shielding portion 15a shown in FIG.

In addition to the antireflection function of the SiO ₂ film, the Al film is in direct contact with the silicon semiconductor thin film,
It prevents the silicon semiconductor thin film from being contaminated.

After that, the amorphous semiconductor thin film 91, the SiO ₂ film 92, and the Al film 93 are placed on the XY stage 77 with the mask 15 removed from the apparatus for forming a crystalline semiconductor thin film shown in FIG. The substrate 10 on which is formed is mounted, and the amorphous silicon semiconductor thin film 91 is irradiated with laser light.

The energy density of the irradiated laser beam is set to a value such that the silicon semiconductor thin film 91 is completely melted in the film thickness direction. As a result, as shown in FIG. 4, in the lattice-shaped region where the laser beam is not shielded by the Al film 93, the amorphous silicon semiconductor thin film 91 is formed.
Completely melts to become completely melted regions 25b to 25d,
In the square region shielded by the Al film 93 and not irradiated with the laser beam, the amorphous silicon semiconductor thin film 91 does not melt and becomes an unmelted region 25a. as a result,
Square unmelted region 25a and lattice-shaped completely melted region 2
From the boundary 25e with 5b to 25d to the completely melted region 25b to
Lateral growth occurs toward 25d, forming a square crystal region 25d composed of four square single crystal grains 25g divided by subgrain boundaries along the <100> direction and the <010> direction, respectively.

Next, after the Al film 93 is once removed by etching, the pattern of the Al film 93 is changed to {(the size of one side of the Al film 93 from the first laser beam irradiation, as shown in FIG. S) + (interval L of Al film 93)} /
2 only in the X and Y directions to move A
The pattern 25f of the I film 93 is arranged in the central portion of the square crystal region 25d in which the four square single crystal grains 25g are formed, and the second laser beam irradiation is performed.

As a result, as shown in FIG. 6, lateral growth occurs toward the completely melted regions 25a to 25c with the already formed rectangular single crystal grains 25g as nuclei. In the completely melted regions 25b and 25c, lateral growth occurs perpendicularly to each side of the pattern 25f of the Al film 93, and crystals are grown in the <010> direction and the <100> direction. In the completely melted region 25d, the Al film 93
Lateral growth occurs in the 45 ° direction from each corner of the pattern 25f.

As a result, the pattern 25 of the Al film 93 is formed.
The single crystal grains 25g shielded by f are expanded and grown, and as shown in FIG. 1, over the entire surface of the substrate or continuously in an arbitrary number, in the <100> direction and the <010> direction, respectively. Rectangular single crystal regions separated by subgrain boundaries are formed without gaps.

When a TFT is produced by forming a crystal region made of rectangular single crystal grains at a specific position by one laser beam irradiation, the pattern of the Al film 93 can be processed. It only needs to be large, and can be set to a very small size.

In addition, in the second embodiment, it is possible to reflect the laser beam by a metal thin film other than the Al film. Furthermore, on the amorphous silicon semiconductor thin film 91,
Instead of the metal thin film 93, a semiconductor thin film such as a silicon semiconductor thin film may be patterned to form the partially melted region of the semiconductor thin film 91 under the pattern. In this case, lateral crystal growth occurs toward the completely melted region with the crystal grains remaining in the partially melted region as nuclei, and a crystal region composed of rectangular single crystal grains can be obtained in the same manner as above. .

Using the crystalline silicon semiconductor thin film formed as described above, a TFT can be manufactured by a usual method. In the second embodiment as well, similar to the first embodiment, adjacent single crystal grains are two-dimensionally grown in a direction orthogonal to each other to form a rectangular crystal region made of rectangular single crystal grains. . Therefore, as shown in FIG. 8B, the transistor 83 whose channel direction is parallel to the <100> direction and the transistor 84 whose channel direction is parallel to the <010> direction can obtain the same element characteristics.

(Third Embodiment) FIG. 10 is a cross-sectional view for explaining a method for forming a crystalline semiconductor thin film according to the third embodiment. In the third embodiment, instead of the mask 15 in the first embodiment, an antireflection film 94 is formed on the amorphous semiconductor thin film 91 to form a rectangular shape at regular intervals in the row direction and the column direction. The partially melted regions are formed in a matrix and the lattice-shaped completely melted regions are formed.

First, similarly to the first embodiment, the insulating substrate 1
Amorphous silicon semiconductor thin film 91 is deposited on 0. TF
When producing T, it is preferable that the film thickness of the amorphous silicon semiconductor thin film 91 is 25 nm to 100 nm.

Next, a SiO ₂ film 94 is formed on the amorphous silicon semiconductor thin film 91 to have a film thickness to be an antireflection film. This SiO ₂ film 94 is opened by etching and removing a portion corresponding to the light shielding portion 15a shown in FIG. 3, and is patterned into a shape corresponding to the light transmitting portion 15b.

Then, the amorphous silicon semiconductor thin film 91 and the SiO 2 film are formed on the XY stage 77 with the mask 15 removed from the apparatus for forming a crystalline semiconductor thin film shown in FIG.
_The substrate 10 on which the _two films 94 are formed is mounted, and the amorphous silicon semiconductor thin film 91 is irradiated with laser light.

The energy density of the laser beam applied is such that the silicon semiconductor thin film 91 is completely melted in the film thickness direction under the SiO ₂ film 94, and the silicon semiconductor thin film 91 is formed in the opening where the SiO ₂ film 94 is not provided. Is set to a value such that is partially melted. For example, for a 45 nm silicon semiconductor thin film 91, 430 mmJ / cm
Set to an energy density of ² or more.

As a result, as shown in FIG.
In the region where the O ₂ film 94 is provided, the completely melted region 35b~35d next to the amorphous silicon semiconductor thin film 91 by the laser beam is completely melted, SiO ₂ film 94
In the region below the opening of the amorphous silicon semiconductor thin film 91
Partially melts to become the unmelted region 35a. As a result, lateral growth occurs from the boundaries between the completely melted regions 35a to 35d and the unmelted regions 35a toward the completely melted regions 35b to 35d, and is divided by subgrain boundaries along the <100> direction and the <010> direction, respectively. A square crystal region 35 composed of four square single crystal grains 35 g
d is formed.

[0119] Next, after the SiO ₂ film 94 is once removed by etching, from the time of laser beam irradiation of the first round, the pattern of the SiO ₂ film 94 {(of one side of the opening of the SiO ₂ film 94 size S ) + (Distance L between the openings of the SiO ₂ film 94)} / 2 in the X and Y directions, respectively, to form four rectangular single crystal grains 35g in the openings of the SiO ₂ film 94. It is arranged in the central portion of the crystal region 35d, and the second laser beam irradiation is performed.

As a result, the already formed single crystal grains 3
Lateral growth occurs toward the completely melted regions 35a to 35c with 5g as a nucleus. Complete melting regions 35b and 3
5c, lateral growth occurs perpendicularly to each side of the opening of the SiO ₂ film 94, and the <010> direction and <
Crystals are grown in the 100> direction. In the completely melted region 35d, lateral growth occurs from the corners of the opening of the SiO ₂ film 94 toward the direction of 45 °.

As a result, each of the single crystal regions 35d arranged under the opening of the SiO ₂ film 94 is expanded and grown, and as shown in FIG. 1, the <100> direction and the <01> direction.
Rectangular single crystal regions separated by sub-grain boundaries respectively along the 0> direction are formed on the entire surface of the substrate or continuously in an arbitrary number without gaps.

Using the crystalline silicon semiconductor thin film formed as described above, a TFT can be manufactured by a usual method. Also in the third embodiment, similarly to the first embodiment, the crystal grains are two-dimensionally grown in the directions orthogonal to each other to form a rectangular crystal region made of rectangular single crystal grains. Therefore, as shown in FIG. 8B, the transistor 83 whose channel direction is parallel to the <100> direction.
And the transistor 84 parallel to the <010> direction, similar element characteristics can be obtained.

(Embodiment 4) In the present embodiment, the mask shown in FIG. 12 is used in place of the mask 15 shown in FIG. 3 in the apparatus for forming a crystalline silicon semiconductor film shown in FIG. FIG. 12A is a plan view of an essential part for explaining the pattern shape of the crystalline semiconductor thin film forming mask in the fourth embodiment, and FIG. 12B is a partially enlarged view thereof. In the fourth embodiment, this mask 40 is used.

In this mask 40, a light-shielding portion 44 is provided with a light-transmitting portion 43 having a saw-tooth slit bent in zigzag. The translucent portion 44 is bent at a substantially right angle at each bent portion. A translucent OPC (OPC (O
optical Proximity Correctio
n, proximity effect correction) pattern 45, and the light-shielding OPC pattern 4 is formed so as to extend the light-shielding portion 44 at the inner corner of each bent portion.
6 are provided respectively.

Each translucent OPC pattern 45 is formed in a square shape in which one corner portion is overlapped with a corner portion outside each bent portion in the zigzag light transmissive portion 43. Similarly, each of the OPC patterns 46 having a light shielding property
Is formed in a square shape in which one corner portion is overlapped with the outer corner portion of each bent portion in the zigzag light transmitting portion 43. The OPC patterns 45 and 46 are arranged so as to be offset by a distance h from the vertices at the outer and inner corners of the translucent portion 43 to the centers of the squares forming the OPC patterns 45 and 46, respectively. There is.

The mask 40 having such a structure is used in place of the mask 15 in the crystalline semiconductor thin film forming apparatus shown in FIG.

In the forming apparatus shown in FIG. 2, when a crystalline semiconductor thin film is formed using the mask 40 having such a structure, first, as in the first embodiment, an amorphous substrate is formed on the insulating substrate. A thin silicon semiconductor thin film. When manufacturing a TFT, the film thickness of this amorphous silicon semiconductor thin film is preferably 25 nm to 100 nm. In this embodiment, an intrinsic (I) type amorphous silicon semiconductor thin film of 35 nm is formed.

After that, the amorphous silicon semiconductor thin film is irradiated with laser light by the apparatus for forming a crystalline semiconductor thin film shown in FIG. In the present embodiment, XeCl laser is used to irradiate light of 308 nm.
An excimer laser such as F, KrF or XeF can be used.

The laser beam is transmitted through the transparent portion 4 of the mask 40.
The amorphous silicon semiconductor thin film is irradiated in a pulsed manner through 3.

The energy density of the irradiated laser beam is set to a value such that the silicon semiconductor thin film is completely melted in the film thickness direction. As a result, as shown in FIG. 13, a zigzag slit-shaped melted region 41 is formed in the amorphous silicon semiconductor thin film, and the other part becomes an unmelted region 42.

In this case, as shown in FIG. 14, for each shot of the laser beam, the amorphous silicon semiconductor thin film or the laser beam is irradiated by a distance smaller than the lateral growth distance formed in the molten region of one shot. , The crystal is grown in one direction by moving the angle of each bent portion of the mask 40, which is bent at a right angle of the transparent portion 43, in a direction along a line that bisects the angle.

When the laser beam is moved relative to the amorphous silicon semiconductor thin film, rectangular single crystal grains are formed in the molten region 46 scanned by the laser beam. As a result, the rectangular pseudo single crystal grains 48, which are separated by the sub-grain boundaries 47 formed along the scanning direction of the laser beam, are formed on the entire surface of the substrate or continuously in an arbitrary number, without any gap. It is arranged and formed.
In the direction of the sub-grain boundary 47, the film thickness of the silicon semiconductor thin film is 35
When it is thicker than μm, it becomes parallel to <110> direction,
When the film thickness of the silicon semiconductor thin film is 35 μm or less, it becomes parallel to the <100> direction.

Melting region 4 of the amorphous semiconductor silicon thin film due to the laser beam passing through the light transmitting portion 43 of the mask 40.
The shape of 1 is a zigzag shape, the bending angle (apex angle) b of each bent portion is about 90 degrees from the viewpoint of grain boundary position control and crystal orientation control, and the width a from the viewpoint of lateral growth distance.
Is 1 μm to 5 μm, and the distance between adjacent corners along the direction orthogonal to the scanning direction of the laser beam, that is, the bisector of each corner, so that subgrain boundaries are not formed in the crystal grains. The pattern of the translucent portion 43 of the mask 40 is formed so that the interval c between adjacent corners along the direction orthogonal to the, ie, the width of the trailing edge of the sub-grain boundary 47 is 15 μm or less. Is desirable.

In this embodiment, in the melting region 41,
The bending angle b of each corner portion is 90 degrees, the width a is 2 μm, and the spacing (distance between subgrain boundaries 47) c between adjacent corner portions along the direction orthogonal to the bisector of each corner portion is 10 μ.
In order to obtain m, for example, in a reduced projection system of 5: 1,
A mask 40 having the following shape is used.

As shown in FIG. 12, the bending angle e of each corner portion of the zigzag light-transmitting portion 43 of the mask 40 is 90 degrees, the slit width d of the light-transmitting portion 43 is 10 μm, and the like of each corner portion. The interval f between adjacent corners along the direction orthogonal to the line is set to 50 μm. The square-shaped OPC patterns 45 and 46 provided at the respective corners of the zigzag light-transmitting portion 43 have one side length g that is not less than 1/5 and not more than 1/2 of the width d of the light-transmitting portion 43. It is said that

Offset h of the OPC patterns 45 and 46 (from the apex at the corner of the transparent portion 43 to the OPC
Distance to the center of patterns 45 and 46) and OPC
The length g of one side of the pattern 45 is (−1/2) × g <
It is desirable to set so as to satisfy the relationship of h <(1/2) × g.

In this embodiment, the transparent OPC patterns 45 and 46 each having a side g of 4 μm are formed on the transparent portion 43.
And the centers of the OPC patterns 45 and 46 are made to coincide with each other and arranged in a state of offset h = 0.

FIG. 15 is a graph showing the results of simulating the light intensity at the corners of a laser beam applied in a zigzag pattern to an amorphous silicon semiconductor thin film. In FIG. 15, the vertical axis and the horizontal axis represent the positions on the front surface silicon semiconductor thin film, and 10 scale is 2 μm.
It has become m.

In FIG. 15, the portion surrounded by the thick lines of the horizontal axis scales 6 to 16 and the vertical axis scales S6 to S16 is an ideal bent portion of the laser beam with which the amorphous silicon semiconductor thin film is irradiated. Shows a simple shape. Further, it is shown that the light intensity is higher in the region where the points in the bent portion are denser and darker.

In the graph shown in FIG. 15, the zigzag pattern of the laser beam with which the amorphous silicon semiconductor thin film is irradiated is well reproduced from the pattern of the transparent portion 43 of the mask 40. As compared with the graph shown, the roundness at the outer and inner corners of each bent portion is smaller. In addition, the light intensity in the central portion of the bent portion is 1 to 1.2 times the light intensity in the case where the slit is not provided, which is smaller than that in the graph shown in FIG. The concentration of the light intensity distribution is alleviated, and the concentration of light on the central portion of the bent portion is reduced. As a result, it is possible to prevent the Si film from jumping at the center of the corner as shown in FIG.

Using the crystalline silicon semiconductor thin film formed as described above, a semiconductor device having a plurality of transistors in which the channel directions from the source to the drain are orthogonal to each other can be manufactured by an ordinary method. .

In the fourth embodiment, the mask 40
The zigzag shape of the light transmitting portion 43 and the shape of the OPC pattern 45 are not limited to the above-described shapes, and an optimum mask shape can be appropriately designed depending on the configuration of the optical system.

(Embodiment 5) In the present embodiment, in the crystalline silicon semiconductor film forming apparatus shown in FIG. 2, a mask 50 shown in FIG. 16 is used instead of the mask 15 shown in FIG. FIG. 16A is a plan view of an essential part for explaining the pattern shape of the mask 50.
(B) is the elements on larger scale. In the fifth embodiment, this mask 50 is used.

In the mask 50, square light-shielding portions 54 are provided in a matrix on the light-transmitting portions 53 at regular intervals along the row and column directions, and the light-transmitting portions 53 are arranged in a grid pattern. Has become. At each corner of the square light shielding portion 54, a square OP is formed so as to extend the light shielding portion 54.
C patterns 55 are provided respectively. The respective OPC patterns 55 are arranged so that one square corner portion overlaps each corner portion of the square light shielding portion 54.

The mask 50 having such a structure is used in place of the mask 15 in the apparatus for forming a crystalline semiconductor thin film shown in FIG.

In the forming apparatus shown in FIG. 2, when the crystalline semiconductor thin film is formed by using the mask 50 having such a structure, first, as in the first embodiment, the amorphous semiconductor is formed on the insulating substrate. A thin silicon semiconductor thin film. When manufacturing a TFT, the film thickness of this amorphous silicon semiconductor thin film is preferably 25 nm to 100 nm. In this embodiment, an intrinsic (I) type amorphous silicon semiconductor thin film of 35 nm is formed.

Thereafter, the amorphous silicon semiconductor thin film is irradiated with laser light by using the crystalline semiconductor thin film forming apparatus shown in FIG. In the present embodiment, XeCl laser is used to irradiate light of 308 nm.
An excimer laser such as F, KrF or XeF can be used.

The laser beam is transmitted through the transparent portion 5 of the mask 50.
Then, the amorphous silicon semiconductor thin film is irradiated with the light through 3.
As a result, in the amorphous silicon semiconductor thin film 60, a plurality of square melting regions 52 are formed in a matrix at regular intervals along the row direction and the column direction, and a portion other than the melting regions 52 is not formed. It becomes the melting region 51.

In this embodiment, the energy density of the irradiated laser beam is set to such a value that the silicon semiconductor thin film is completely melted in the film thickness direction. As a result, as shown in FIG. 4, the amorphous silicon semiconductor thin film is completely melted and completely melted in the lattice-shaped region where the laser beam is irradiated through the light transmitting portion 53 of the mask 50. Therefore, in the square area where the laser beam is not irradiated by the light shielding portion 54 of the mask 50,
The amorphous silicon semiconductor thin film does not melt and becomes a square unmelted region 25a.

As a result, the amorphous silicon semiconductor is explosively crystallized at the boundary 25e between the square unmelted region 25a and the lattice-shaped completely melted regions 25b to 25d to form fine crystal grains. Lateral growth occurs toward the completely melted regions 25b to 25d by using such crystal grains as crystal growth nuclei. Then, the <100> direction and <010
A square crystal region 25d composed of four square single crystal grains 25g separated by sub-grain boundaries along the> direction is formed.

Next, as shown in FIG. 5, from the time of the first laser beam irradiation, the pattern of the light shielding portion 54 of the mask is X (interval i of the light shielding portion 54 + width j of the light shielding portion 54) / 2. The projection pattern 25f of the light-shielding portion 54 by moving the four square single-crystal grains 2 respectively.
The second laser beam irradiation is carried out by arranging it in the central portion of the crystal region 25d in which 5 g is formed. As a result, as shown in FIG. 6, 25 g of already formed single crystal grains
With n as a nucleus, lateral growth occurs toward the completely melted regions 25a to 25c. Fully melted areas 25b and 25c
Then, lateral growth occurs in each of the sides of the projection pattern 25f of the light-shielding portion perpendicularly to the <010> direction and <
Crystals are grown in the 100> direction. Further, in the completely melted region 25d, lateral growth occurs in the 45 ° direction from each corner of the projection pattern 25f of the light shielding part. As a result, each of the single crystal grains 25g shielded by the projection pattern 25f of the light shielding portion 54 is expanded and grown, and as shown in FIG. 1, the <100> direction and the <010> direction.
Rectangular single crystal grains separated by sub-grain boundaries along the> direction are formed on the entire surface of the substrate or continuously in an arbitrary number and are arranged without any gap therebetween.

Considering the lateral growth distance that can be formed in the semiconductor silicon thin film when one shot of the laser beam is applied, for example, the line width L of the molten region 51 is 2
It is set to be not less than μm and not more than 5 μm. Further, when a plurality of crystal regions are formed without gaps by laser beam irradiation twice, the length S of one side of the unmelted region 52 is L.
Is set smaller than.

In this embodiment, the line width L of the melted region 51 is 4 μm, and the length S of the position side of the unmelted region 52 is 3.6 μm.
And In order to form the melted region 51 having this shape, a mask 50 having the following shape is used, for example, in a reduction projection system of 5: 1.

In this mask 50, the width i of the transparent portion 53 = the interval between the light shielding portions 54 is set to 20 μm, and the length j of one side of the light shielding portion 54 is set to 18 μm. When the OPC pattern 55 has a square shape, the length g of one side of the OPC pattern 55 is ⅕ or more of the length j of one side of the rectangular light-shielding portion 54 and 1 /.
It is set to 2 or less. In addition, the offset h of the OPC pattern 55 (from the apex of the corner of the light shielding portion 54 to the OPC
The distance to the center of the pattern 55) and the length g of one side of the OPC pattern are (-1/2) * g <h <(1/2).
It is desirable to set so as to satisfy the relationship of xg. In this embodiment, a square OPC having a side g of 8 μm.
The pattern 55 is arranged in a state where the offset h = 0 with the apex of the corner portion of the light shielding portion 54 and the center of the OPC pattern 55 aligned.

Using the crystalline silicon semiconductor thin film formed as described above, a conventional method shown in FIG.
As shown in (b), a semiconductor device including a transistor 83 whose channel direction is parallel to the <100> direction and a transistor 84 whose channel direction is parallel to the <010> direction can be manufactured.

In the fifth embodiment, the mask 50 is used.
The shapes of the light-transmitting portion 53 and the light-shielding portion 54 are not limited to the above-described shapes, and an optimum mask shape is appropriately designed according to the lateral growth region that can be formed by irradiating a one-shot laser beam. be able to. Further, the shape of the OPC pattern 55 is not limited to the above-mentioned shape, and an optimum mask shape can be appropriately designed according to the configuration of the optical system.

[0157]

As described in detail above, according to the present invention,
In a method of forming a crystalline semiconductor thin film by irradiating an amorphous semiconductor thin film provided on an insulating substrate with an energy beam to melt and then solidifying the amorphous semiconductor thin film, a completely melted region and an unmelted region, or a completely melted region is formed. By arranging the melted region and the partially melted region in contact with each other, it is possible to secure a crystal that serves as a nucleus (seed) for lateral growth. In addition, the unmelted regions or partially melted regions are formed in a matrix shape at regular intervals along the row direction and the column direction, and the completely melted regions are formed in a grid pattern to form rectangular completely melted regions and unmelted regions. By laterally growing from the boundary with the region or from the boundary between the completely melted region and the partially melted region toward the completely melted region, the unmelted region or the partially melted region adjacent to each other and the vertically adjacent unmelted region A rectangular completely melted region surrounded by a completely melted region located between the melted regions or the partially melted regions and a horizontally melted completely unmelted region or partially melted regions adjacent to each other, It is possible to form a rectangular crystal region composed of rectangular single crystal grains with a high throughput by forming a portion where the lateral growth intersects at right angles. In the rectangular crystal region thus obtained, the transistor provided with the channel direction from the source to the drain parallel to the <100> direction and the transistor provided parallel to the <010> direction have respective device characteristics. Can be made equal to each other, so that a high-performance semiconductor device can be realized.

Further, according to the present invention, a lateral growth region is controlled by inserting a mask having a light-transmitting portion or a light-shielding portion having one or more right-angled bent portions into the irradiation path of the energy beam. In the method described above, by using a mask having an OPC pattern provided at the corner tip of the portion bent at a right angle, the dullness of the light intensity is improved at the corner portion of the beam shape bent at a right angle, and the light intensity at the center of the corner portion is improved. The concentration of can be eased. As a result, it is possible to suppress the Si film skip and obtain a desired beam shape, so that it becomes possible to accurately control the lateral growth in the completely melted region, and an easy laser beam can be formed on an insulating substrate such as glass. By the scanning method, a high-quality crystalline semiconductor thin film can be formed and a high-performance semiconductor device can be realized.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a configuration of crystal grains in a crystalline semiconductor thin film according to a first embodiment.

FIG. 2 is a schematic diagram showing a schematic configuration of a crystalline semiconductor thin film forming apparatus used in the first embodiment.

FIG. 3 is a diagram showing a pattern example of a mask for forming a crystalline semiconductor thin film used in the first embodiment.

FIG. 4 is a schematic diagram for explaining the relationship between the layout and the lateral growth of the mask pattern projected on the semiconductor thin film during the first laser beam irradiation in the method for forming a crystalline semiconductor thin film according to the first embodiment. .

FIG. 5 is a schematic diagram for explaining the arrangement of mask patterns projected on the semiconductor thin film during the second laser beam irradiation in the method for forming a crystalline semiconductor thin film according to the first embodiment.

FIG. 6 is a schematic diagram for explaining the relationship between the layout and the lateral growth of the mask pattern projected on the semiconductor thin film during the second laser beam irradiation in the method for forming a crystalline semiconductor thin film according to the first embodiment. .

FIG. 7 is a diagram for explaining a lateral growth distance in the method for forming a crystalline semiconductor thin film according to the first embodiment.

FIG. 8A is a schematic diagram for explaining a semiconductor device in which a plurality of TFTs are arranged so that channel directions thereof are orthogonal to each other using a crystalline semiconductor thin film formed by a conventional SLS method, (B) is a schematic diagram for explaining a semiconductor device in which the crystalline semiconductor thin film of Embodiment 1 is used and the plurality of TFTs are arranged such that their channel directions are orthogonal to each other.

FIG. 9 is a cross-sectional view for explaining the method for forming a crystalline semiconductor thin film according to the second embodiment.

FIG. 10 is a cross-sectional view for explaining the method for forming a crystalline semiconductor thin film according to the second embodiment.

FIG. 11 is a schematic diagram for explaining the relationship between the lateral growth and the arrangement of partially melted regions and completely melted regions formed during the first laser beam irradiation in the method for forming a crystalline semiconductor thin film according to the third embodiment. Is.

12A and 12B are schematic diagrams showing pattern examples of a mask for forming a crystalline semiconductor thin film according to the fourth embodiment.

FIG. 13 is a schematic diagram showing a molten region of a semiconductor thin film in the method for forming a crystalline semiconductor thin film of Embodiment 4.

FIG. 14 is a schematic diagram showing a beam scanning direction and a configuration of a pseudo single crystal to be formed in the method for forming a crystalline semiconductor thin film according to the fourth embodiment.

FIG. 15 is a graph showing a result of simulating the light intensity of a sawtooth-shaped corner portion in the method for forming a crystalline semiconductor thin film according to the fourth embodiment.

16A and 16B are schematic diagrams showing pattern examples of a mask for forming a crystalline semiconductor thin film according to the fifth embodiment.

FIG. 17 is a schematic diagram showing a molten region of a semiconductor thin film in the method for forming a crystalline semiconductor thin film according to the fifth embodiment.

FIG. 18 is a graph showing a result of simulating the light intensity of a sawtooth-shaped corner portion in the conventional method for forming a crystalline semiconductor thin film.

FIG. 19 is a diagram showing a Si film jump that occurs in a conventional method for forming a crystalline semiconductor thin film.

[Explanation of symbols]

11 crystal grains 12 crystal grain boundaries 10 substrates 15, 40, 50 on which a semiconductor thin film is formed mask 15a light shielding portion 15b light transmitting portion 25a shielded during the first laser beam irradiation and irradiated during the second laser beam irradiation Areas 25b, 25c in which lateral growth occurs are irradiated with a laser beam during the first and second laser beam irradiations. Areas 25d in which lateral growth occurs During the first laser beam irradiation, lateral growth occurs and lateral growth occurs. Region 25e where crystal grains are formed 25e Boundary between completely melted region and unmelted region during first laser beam irradiation 25f Regions shielded during second laser beam irradiation 25g, 35g Rectangular single crystal grains 35a First laser beam irradiation Sometimes partially melted,
Regions 35b, 35c that are completely melted and laterally grown during the second laser beam irradiation. Regions 35b and 35c that are completely melted and laterally grown during the second laser beam irradiation are melted during the first laser beam irradiation. Lateral growth occurs and rectangular single crystal grains are formed 41, 51 Melted regions 42, 52 Unmelted regions 43, 53 Light transmitting parts 44, 54 Light shielding parts 45, 46, 55 OPC pattern 47 Subgrain boundary 48 Crystal grains 60, 91 Amorphous silicon semiconductor thin film 61 Si film jump 71 Laser 72 Telescope 73 Homogenizer 74 Field lens 75 Mask 76 Projection lens 77 XY stage 81, 82, 83, 84 TFT 92, 94 SiO ₂ film 93 Al film

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 5F052 AA02 BA01 BA08 BA12 BA18                       BB07 CA04 CA10 DA02 FA01                       JA01                 5F110 AA01 BB01 BB10 BB11 DD02                       DD13 GG02 GG13 GG15 GG17                       GG25 GG35 PP03 PP04 PP05                       PP06 PP11 PP24

Claims (24)

[Claims] 1. A plurality of rectangular crystal grains are formed, and adjacent crystal grains have a <100> direction and a <010> direction.
A crystalline semiconductor thin film separated by subgrain boundaries along each direction. 2. The crystalline semiconductor thin film according to claim 1, wherein the plurality of rectangular crystal grains are arranged on the substrate in a continuous manner or in an arbitrary number continuously or over the entire surface without a gap. 3. A method for forming a crystalline semiconductor thin film by irradiating an amorphous semiconductor thin film provided on an insulating substrate with an energy beam to melt and then solidify the amorphous semiconductor thin film. Irradiating the thin film with a rectangular energy beam to form a plurality of rectangular unmelted regions or partially melted regions arranged in a matrix at regular intervals along the row and column directions, and also to form a lattice. By forming a completely melted region in the shape of a circle and laterally growing from the boundary between the completely melted region and the unmelted region or the completely melted region and the partially melted region toward the completely melted region. A melted or partially melted area, a completely melted area located between vertically adjacent unmelted or partially melted areas, and a horizontally adjacent unmelted or partially melted area A rectangular completely melted region surrounded by the completely melted region located between the band, the method of forming the crystalline semiconductor film to form a rectangular crystal region consisting of four rectangular single crystal grain. 4. A method of forming a crystalline semiconductor thin film by irradiating an amorphous semiconductor thin film provided on an insulating substrate with an energy beam to melt and then solidify the amorphous semiconductor thin film. The thin film is irradiated with an energy beam to form rectangular unmelted regions or partially melted regions in a matrix at regular intervals along the row and column directions, and to form a completely melted region in a grid. By the lateral growth from the boundary between the completely melted region and the unmelted region or the completely melted region and the partially melted region toward the completely melted region, the unmelted region or the partially melted region adjacent to each other, Fully melted area located between vertically adjacent unmelted or partially melted areas and completely melted area between horizontally adjacent unmelted or partially melted areas A first step of forming a crystal region composed of four rectangular single crystal grains in a rectangular completely melted region surrounded by a region, and irradiating the semiconductor thin film with an energy beam to perform the first step. Forming a rectangular unmelted region or a partially melted region in the rectangular crystal region formed by, and forming a completely melted region in a lattice pattern, the completely melted region and the unmelted region or the completely melted region. By growing crystals from the boundary between the partial melting region and the partial melting region,
A second step of expanding and growing each rectangular single crystal grain,
A method for forming a crystalline semiconductor thin film containing: 5. A mask having rectangular light-shielding portions arranged in a matrix in the irradiation path of the energy beam at regular intervals along the row direction and the column direction, and the mask having the light-shielding portions arranged in a grid pattern is arranged. Alternatively, rectangular metal thin films or second semiconductor thin films are provided in a matrix on the semiconductor thin film at regular intervals along the row direction and the column direction, or on the semiconductor thin film. By providing an antireflection film in which rectangular openings are provided in a matrix at regular intervals along the row direction and the column direction,
4. A rectangular unmelted region or a partially melted region is formed in a matrix form at regular intervals along the row direction and the column direction, and a completely melted region is formed in a lattice form.
Alternatively, the method for forming a crystalline semiconductor thin film according to claim 4. 6. The light-shielding portion of the mask, the metal thin film or the second semiconductor thin film, or the length of one side of the opening of the antireflection film is set so that the light-shielding portion of the adjacent mask, the reflective film, or the It is set to be smaller than the distance between the openings of the antireflection film, and in the first step and the second step,
The light shielding portion of the mask, the metal thin film or the second semiconductor thin film, or the opening of the antireflection film is moved by (length of one side + interval) / 2 in the X direction and the Y direction, respectively, A mask, the metal thin film or the second semiconductor thin film,
Alternatively, the method for forming a crystalline semiconductor thin film according to claim 4, wherein the antireflection film is disposed. 7. The light-shielding portion of the mask is moved in the X direction and the Y direction by moving the beam mask holder holding the mask in the first step and the second step. Item 7. A method for forming a crystalline semiconductor thin film according to item 6. 8. A method for forming a crystalline semiconductor thin film by irradiating an amorphous semiconductor thin film provided on an insulating substrate with an energy beam to melt and then solidify the amorphous semiconductor thin film. The path is provided with a light-transmitting portion or a light-shielding portion having one or more right-angled bent portions, and OP is provided at a corner tip of the right-angled bent portions.
C (Optical Proximity Correc
section), a method for forming a crystalline semiconductor thin film, wherein a melted region of a semiconductor thin film is formed by arranging a mask provided with a pattern. 9. A mask having a sawtooth light-transmitting portion and an OPC pattern provided at the apex of the sawtooth is used, or a rectangular shape is formed at regular intervals along the row and column directions. 9. The method for forming a crystalline semiconductor thin film according to claim 8, wherein the light-shielding portion is provided in a matrix, the light-transmitting portion is provided in a lattice, and an OPC pattern is provided at a vertex of the lattice. 10. The OPC pattern has a square shape, and an offset h of the OPC pattern and a length g of one side of the OPC pattern are (−1/2) × g <h <(1 / The method for forming a crystalline semiconductor thin film according to claim 9, wherein a mask that satisfies the relationship 2) × g 2 is used. 11. A completely melted region of a semiconductor thin film is formed with a line width a by using a mask provided with the sawtooth light-transmitting portion.
Is 1 μm or more and 5 μm or less, the apex angle b is approximately 90 °, and the spacing c between the vertices is 15 μm or less.
7. The method for forming a crystalline semiconductor thin film according to. 12. A mask in which the OPC pattern has a square shape, and a length g of one side of the OPC pattern is ⅕ or more and ½ or less of a line width d of the sawtooth light transmitting portion. The method for forming a crystalline semiconductor thin film according to claim 9, wherein the method is used. 13. The mask is provided with the saw-toothed light-transmitting portion, and the energy beam is radiated by adjusting the intensity so that the semiconductor thin film is completely melted in the film thickness direction. The crystalline semiconductor thin film according to claim 9, wherein the semiconductor thin film or the energy beam is moved in a certain direction by a distance smaller than a lateral growth distance formed in one shot molten region to perform crystal growth in one direction. Forming method. 14. A molten region of a semiconductor thin film having a line width L of 2 using a mask provided with the lattice-shaped light-transmitting portion.
The method for forming a crystalline semiconductor thin film according to claim 9, wherein the crystalline semiconductor thin film is formed in a grid shape having a size of from 5 μm to 5 μm, and the unmelted region is formed into a rectangular shape having a side length S smaller than L. 15. The OPC pattern has a square shape, and a length g of one side of the OPC pattern is 1/5 or more and 1/2 or less of a length j of one side of the rectangular light-shielding portion. The method for forming a crystalline semiconductor thin film according to claim 9, wherein a certain mask is used. 16. The mask is provided with the light-transmitting portion in the form of a grid, and the length j of one side of the light-shielding portion is set to be smaller than the interval i between the openings of the light-shielding portion of the mask, and the mask has substantially the same length. The region is irradiated with the energy beam twice through the mask, and the light-shielding portion of the mask is (i + j) / 2 in the X direction and the Y direction during the first irradiation and the second irradiation, respectively. The method for forming a crystalline semiconductor thin film according to claim 9, wherein the mask is moved to dispose the mask. 17. A crystalline semiconductor thin film formed by the method for forming a crystalline semiconductor thin film according to claim 9, wherein the crystalline semiconductor thin film is composed of a plurality of rectangular crystal grains, and adjacent crystal grains have a <100> direction. Alternatively, a crystal which is divided by sub-grain boundaries along the <110> direction and in which the plurality of rectangular crystal grains are arranged on the substrate in a continuous manner or in an arbitrary number continuously or over the entire surface. Thin semiconductor film. 18. A crystalline semiconductor thin film formed by the method for forming a crystalline semiconductor thin film according to claim 9, wherein the crystalline semiconductor thin film is composed of a plurality of rectangular crystal grains, and adjacent crystal grains have a <100> direction. And a plurality of rectangular crystal grains, which are separated by sub-grain boundaries along the <010> direction and on the substrate, are arranged continuously or over the entire surface in any number without gaps. Crystalline semiconductor thin film. 19. A claim 2, a claim 17, or a claim 1.
8. A semiconductor device using the crystalline semiconductor thin film according to 8, wherein a transistor whose channel direction from a source to a drain is parallel to the <100> direction and a transistor whose channel direction is parallel to the <010> direction. 20. An apparatus for forming a crystalline semiconductor thin film by irradiating an amorphous semiconductor thin film provided on an insulating substrate with an energy beam to melt and then solidify the amorphous semiconductor thin film, which is amorphous. A stage on which a substrate provided with a high quality semiconductor thin film is mounted, and an energy beam source for generating an energy beam, and a light transmitting portion having one or more bent portions at right angles in an irradiation path of the energy beam or A light-shielding portion is provided, and OP is provided at the corner tip of the bent portion at a right angle.
An apparatus for forming a crystalline semiconductor thin film, in which a mask having a C pattern is arranged. 21. When an amorphous semiconductor thin film provided on an insulating substrate is irradiated with an energy beam to be melted and then solidified to form a crystalline semiconductor thin film, an irradiation path of the energy beam is used. A crystalline semiconductor in which a mask to be arranged is provided with a light-transmitting portion or a light-shielding portion having one or more right-angled bent portions, and an OPC pattern is provided at a corner tip of the right-angled bent portions. Mask for thin film formation. 22. A sawtooth light-transmitting portion is provided, and an OPC pattern is provided at the top of the sawtooth, or
The rectangular light-shielding portions are provided in a matrix form at regular intervals along the row direction and the column direction, the light-transmitting portions are provided in a lattice shape, and the OPC pattern is provided at the apex portion of the lattice. 21. A mask for forming the crystalline semiconductor thin film according to 21. 23. The OPC pattern has a square shape, and an offset h of the OPC pattern and a length g of one side of the OPC pattern are (−1/2) × g <h <(1 / The crystalline semiconductor thin film formation mask according to claim 22, wherein the relationship of 2) × g 2 is satisfied. 24. The OPC pattern has a square shape, and the length g of one side of the OPC pattern is not less than ⅕ and not more than ½ of the line width d of the sawtooth light-transmitting portion. 24. The crystalline semiconductor thin film according to claim 23, wherein the length g of one side of the OPC pattern is ⅕ or more and ½ or less of the length j of one side of the rectangular light-shielding portion. Forming mask.