JP2004095666A - Semiconductor thin film, method for forming the same, semiconductor device, and display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To uniform a crystal plane parallel to the film surface of a thin film formed by crystal growth and to have the crystal orientation of the crystal plane fixed. <P>SOLUTION: An amorphous Si film 3 having a seed crystal growth area 6 and a crystal growth area 7 coupled with the area 6 by a coupling part 4 is patterned so that one side 6a of the area 6 and one side 7a of the area 7 are aligned and the corner of the area 7 forms acute angle. The patterned amorphous Si film 3 is irradiated with energy beams of 1st energy density to form a seed crystal forming area 5 having a prescribed crystal plane on the film 3, and then irradiated with energy beams of 2nd energy density to form a seed crystal growth area 6 on which crystal has prescribed orientation. Then a single domain crystal 12 having the prescribed crystal orientation is allowed to grow in the lateral direction in the crystal growth area 7 on the basis of crystal grains selected from the seed crystal growth area 6. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention provides a semiconductor thin film obtained by irradiating an energy beam to an amorphous semiconductor film or the like formed on an insulating substrate and crystallizing the amorphous semiconductor film or the like by its thermal energy, a method of forming the semiconductor thin film, The present invention relates to a semiconductor device and a display device using the semiconductor thin film.
[0002]
[Prior art]
2. Description of the Related Art In recent years, a thin film semiconductor element represented by a thin film transistor (Thin Film Transistor: hereinafter, referred to as a TFT) is a semiconductor thin film having a thickness of several tens nm to several hundreds nm by a CVD method or the like on a substrate having an insulating surface. The insulated gate field effect type semiconductor element, the diode and the like are formed by using the semiconductor thin film as an active layer.
[0003]
As an application field of such an insulated gate type field effect type semiconductor device or the like, an active matrix type liquid crystal display device is known. In an active matrix type liquid crystal display device, one or more TFTs each composed of an insulated gate type field effect semiconductor element are arranged on each of several hundred thousand or more pixel electrodes arranged in a matrix, and electric charges supplied to the pixel electrodes are provided. Is controlled by the TFT.
[0004]
As a semiconductor thin film used for forming a TFT, it is easy to use an amorphous Si film in manufacturing. However, an amorphous Si film has electrical characteristics such as low carrier mobility, There is a problem that the speed is slow. In order to improve the electrical characteristics of a TFT using an amorphous Si film, a crystalline Si thin film may be used. The Si thin film having crystallinity is called polycrystalline Si, microcrystalline Si, or the like.
[0005]
Conventionally, an amorphous Si film or a polycrystalline Si film is formed on a non-single-crystal insulating film formed on a substrate or on an insulating substrate, and an energy beam is applied to the amorphous Si film or the polycrystalline Si film. There is known a method of crystallizing an amorphous Si film or a polycrystalline Si film by applying thermal energy by irradiation such as irradiation.
[0006]
For example, an amorphous Si film or a polycrystalline Si film formed on an insulating substrate is intermittently irradiated in a pulsed manner with an energy beam in which a beam irradiation region is linear, and a linear irradiation region is irradiated. , The amorphous silicon film or the polycrystalline Si film is repeatedly melted and solidified to crystallize the amorphous Si film or the polycrystalline Si film. According to this method, it is known that a crystalline Si film having a crystal orientation substantially in the <001> orientation is formed along the moving direction of the pulsed energy beam.
[0007]
In such a crystal growth method, in order to form a crystalline Si film with a controlled crystal orientation over the entire crystal growth region on the substrate, generation of irregular crystal nuclei was suppressed and controlled. It is important to use crystal nuclei as seed crystals to promote crystal growth, and finally to form a single domain. A single domain is a region where there is no large tilt boundary where the crystal orientation shift is 5 ° or more. Note that, within a single domain, there is a small tilt grain boundary having a crystal orientation shift of several degrees or less.
[0008]
FIGS. 8A and 8B are schematic diagrams illustrating conventional crystal growth, respectively.
[0009]
In FIG. 8A, an amorphous Si film 31 formed on a substrate is patterned into a predetermined shape, and an energy beam having a linear beam shape in an irradiation region is moved in one direction (the moving direction is indicated by an arrow). 35), a crystalline Si film having a crystal orientation of approximately <001> orientation along the moving direction.
[0010]
In this case, first, the amorphous Si film 31 formed on the substrate is patterned into a predetermined shape. In the amorphous Si film 31, a rectangular first island-shaped region 32 located on the upstream side in the energy beam moving direction and a second island-shaped region 33 located on the downstream side in the energy beam moving direction are mutually bonded. It is patterned into the formed shape. The second island region 33 has an acute angle at one corner located on the upstream side in the energy beam movement direction, and the corner is opposed to one corner of the first island region 32. The corner portions that are arranged and face each other are connected by a connecting portion 34. In this case, one side 32a of the first island-shaped region 32 and one side 33b of the second island-shaped region 33 connected by the coupling portion 34 are arranged in a straight line, and the acute angle corner of the second island-shaped region 33 is formed. The other side 33a forming the portion is inclined with respect to each of the straight sides 32a and 33b.
[0011]
Next, from the first island-like region 32 to the second island-like region 33, an energy beam whose beam irradiation region is linear is intermittently irradiated in a pulse shape, and the energy beam is directed along the direction indicated by the arrow 35. , And the process of melting and solidifying the amorphous Si film 31 is repeated. As a result, in the first island-shaped region 32, a crystalline Si film that becomes a seed crystal having a crystal orientation of approximately the <001> orientation grows along the moving direction of the energy beam indicated by the arrow 35. In the crystalline Si film grown in the first island region 32, only the crystal grains of one crystal region are selected in the coupling portion 34. In the second island region 33, the crystal grain of the selected crystalline Si film is used as a seed crystal while suppressing the generation of random crystal nuclei, Grows a crystalline Si film having a substantially <001> orientation. Here, the moving direction of the energy beam indicated by the arrow 35 is parallel to one side 32a of the first island region 32 and one side 33a of the second island region 33, respectively. As described above, since one side of the second island region 33 on the upstream side in the moving direction of the energy beam is inclined with respect to the moving direction, the crystal orientation of the second island region 33 extends over the entire region of the second island region 33. Can grow a crystalline Si film having a substantially <001> orientation.
[0012]
FIG. 8B shows a case where the second island region 33 is formed such that one side located on the upstream side in the moving direction of the energy beam is perpendicular to the moving direction of the energy beam. In this case, when the energy beam whose beam irradiation area is linear passes through the side 33c perpendicular to the moving direction of the energy beam indicated by the arrow 35, the energy beam becomes linear. And the side 33c perpendicular to the moving direction of the energy beam are parallel to each other. Therefore, in a region of the second island region 33 away from the joint portion 34 along the side 33c, the energy beam is irradiated before the crystal grain of the crystalline Si film selected at the joint portion 34 grows. Therefore, a crystal nucleus 36 having a random crystal orientation is generated. As a result, in the second island-like region 33, crystal grains 36a grown using the crystal nucleus 36 having a random crystal orientation as a seed crystal are generated, and a single-domain crystalline Si film cannot be obtained.
[0013]
For miniaturization of semiconductor elements and stabilization of electrical characteristics, it is essential to use semiconductor thin films having good crystallinity. In particular, a crystal in which the crystal orientation of the crystal plane is controlled and in which a single domain is formed has extremely good crystallinity, so that it is also used for a TFT of a thin film semiconductor device that requires good electrical characteristics. can do.
[0014]
[Problems to be solved by the invention]
For this reason, as shown in FIG. 8A, it is preferable that the second island region 33 is patterned as described above and irradiated with an energy beam. In the crystal growth shown in FIG. 8A, a plurality of crystal regions elongated in the direction of movement 35 of the linear energy beam are formed in the first island regions 32, and one of the crystal regions is formed at the coupling portion 34. 8B, the crystal growth of the crystalline Si film is performed in the crystal growth region of the second island region 33 while suppressing the generation of random crystal nuclei 36 as shown in FIG. Can be. However, in the crystalline Si film, the selected crystal orientation of the crystal plane with respect to the crystalline Si film surface is substantially <001>, but the crystal orientation in a crystal plane parallel to the film plane in the crystalline Si film. Is not controlled at all. For this reason, the inside of the crystalline Si film is in a state where a large number of fine crystal grains of 1 μm or less having different crystal orientations are spread, and is not in a state of a single domain having a uniform crystal orientation.
[0015]
As described above, even in the conventional crystal growth shown in FIG. 8A, a crystalline Si film having a single domain in which the crystal plane parallel to the film plane is constant and the crystal orientation of the crystal plane is uniform is obtained. I can't.
[0016]
Further, the crystal grains of the crystalline Si film formed in the first island-shaped region 32 are selected in the coupling portion 34, and the crystal orientation in the crystal plane of the crystal nucleus serving as the seed crystal of the second island-shaped region 33 is Since it is random, the crystal orientation differs for each grown island-shaped crystalline Si film.
[0017]
When a semiconductor device such as a liquid crystal driver, a semiconductor memory, or a semiconductor logic circuit is manufactured using a crystalline Si film in which the crystal orientation of the crystal plane is not uniform, the carrier mobility of a TFT provided in the semiconductor device is increased. And the threshold voltage increases, and the carrier mobility of the TFT and the variation in the threshold voltage may increase.
[0018]
The present invention is intended to solve such a problem, and an object of the present invention is to provide a semiconductor thin film in which a crystal plane parallel to a film surface in a crystal-grown thin film is constant and the crystal orientation of the crystal plane is also constant. And a method of forming the semiconductor thin film, and a semiconductor device and a display device using the semiconductor thin film.
[0019]
[Means for Solving the Problems]
In the method for forming a semiconductor thin film of the present invention, an energy beam having a linear beam irradiation region is moved to a direction perpendicular to the beam irradiation region on an insulating substrate or a semiconductor film formed on the insulating film. A method of growing a semiconductor thin film including a crystal growth step of growing a semiconductor thin film by irradiating the semiconductor film with a rectangular first island-shaped region arranged on the upstream side in the energy beam moving direction. A second island-shaped region which is arranged downstream of the first island-shaped region with respect to the moving direction of the energy beam and whose corners are joined to each other by a joint. Patterning the semiconductor film such that one side of the island-shaped region and one side of the second island-shaped region are linearly coupled, and the corner of the second island-shaped region in the joint is at an acute angle; Irradiating the first island region with the first energy density without moving the energy beam to form a seed crystal forming region in which a predetermined crystal plane is preferentially oriented; An energy beam set at a predetermined moving amount is repeatedly irradiated from the seed crystal forming region into the first island region, and a seed crystal growing region in which a predetermined crystal orientation is oriented along the moving direction of the energy beam. Forming in the first island region;
The second island-shaped region is repeatedly irradiated with an energy beam set to a second energy density and a predetermined moving amount, and is moved along the moving direction of the energy beam based on crystal grains selected from the seed crystal growing region. And a step of laterally growing a crystalline semiconductor thin film oriented in a predetermined crystal orientation, thereby achieving the above object.
[0020]
Preferably, in the method for forming a semiconductor thin film of the present invention, the crystal plane and the crystal orientation are substantially {100} plane and substantially <001> orientation, respectively.
[0021]
Still preferably, in the method for forming a semiconductor thin film according to the present invention, the second energy density is higher than the first energy density.
[0022]
More preferably, in the method for forming a semiconductor thin film of the present invention, the first energy density is 360 to 400 mJ / cm. ² It is.
[0023]
Still preferably, in the method for forming a semiconductor thin film according to the present invention, the second energy density is 400 to 500 mJ / cm. ² It is.
[0024]
More preferably, in the method of forming a semiconductor thin film according to the present invention, the peak position of the energy density distribution in the moving direction of the energy beam is inside the previous irradiation area at the time of repeated irradiation.
[0025]
More preferably, in the method for forming a semiconductor thin film according to the present invention, the amount of one movement of the energy beam is 10 μm or less.
[0026]
More preferably, in the method for forming a semiconductor thin film of the present invention, the thickness of the semiconductor film is 10 to 200 nm.
[0027]
More preferably, in the method of forming a semiconductor thin film according to the present invention, the width of the joint is set to 20 μm or less.
[0028]
Still preferably, in a method of forming a semiconductor thin film according to the present invention, a corner portion of the second island region is perpendicular to one side of the linear first island region and one side of the second island region. Incline by 10 to 80 ° from the vertical direction based on the direction.
[0029]
More preferably, in the method for forming a semiconductor thin film of the present invention, the semiconductor film is Si (silicon).
[0030]
The semiconductor thin film of the present invention is formed from crystal grains formed on an insulating substrate or an insulating film, having a substantially {100} crystal plane and a substantially <001> crystal orientation. Thereby, the above object is achieved.
[0031]
Also. Preferably, in the semiconductor thin film of the present invention, the crystal grains form a single domain.
[0032]
A semiconductor device according to the present invention uses a semiconductor thin film formed by the method for forming a semiconductor thin film according to any one of claims 1 to 11, thereby achieving the above object.
[0033]
A semiconductor device according to the present invention uses the semiconductor thin film according to claim 12 or 13, thereby achieving the above object.
[0034]
A display device according to the present invention uses the semiconductor device according to claim 14 or 15, thereby achieving the above object.
[0035]
The operation of the above configuration will be described below.
[0036]
According to the method of forming a semiconductor thin film of the present invention, a seed crystal forming region in a first island region of the semiconductor thin film is irradiated with an energy beam having a first energy density in a pulse shape so that a specific crystal plane is parallel to the film plane. A seed crystal composed of crystal grains preferentially oriented to the seed crystal is formed, and then the energy beam is moved in a direction parallel to one side of the seed crystal growth region and one side of the crystal growth region, and the specific The second energy density of the energy beam and a predetermined amount of movement are set so that the crystal orientation is preferentially oriented in the direction in which the energy beam moves, and the energy beam is moved while the irradiation position of the energy beam is moved from the seed crystal. The semiconductor thin film inheriting a specific crystal orientation of the seed crystal is laterally irradiated by repeatedly irradiating a pulse shape from the seed crystal growth region in the first island region to the crystal growth region in the second island region. Crystal is grown in the direction. Thus, according to the method of forming a semiconductor thin film of the present invention, a semiconductor thin film having a specific crystal plane parallel to the seed crystal film plane and having a specific crystal orientation in the direction in which the energy beam moves can be formed.
[0037]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0038]
FIG. 1 is a perspective view illustrating a method for forming a semiconductor thin film according to an embodiment of the present invention.
[0039]
As shown in FIG. 1, first, TEOS (tetraethoxysilane) gas and O 2 gas are placed on an insulating substrate 1 such as a glass substrate. ₃ 200 nm thick SiO 2 by plasma CVD (chemical vapor deposition) using gas. ₂ The film 2 is formed.
[0040]
Next, SiO 2 ₂ Si on the film 2 ₂ H ₆ Gas and H ₂ An amorphous Si film 3 having a thickness of 50 nm is formed by a plasma CVD method using a gas. Furthermore, CF ₄ Gas and O ₂ The amorphous Si film 3 is patterned into a predetermined shape by RIE (Reactive Ion Etching) using a gas. The amorphous Si film 3 includes a first rectangular island-shaped region, which is a seed crystal growth region 6 including a seed crystal forming region 5 located on the upstream side in the moving direction of the excimer laser beam 10, and the movement of the excimer laser beam 10. The second island-shaped region, which is the crystal growth region 7 located on the downstream side in the direction, is patterned into a shape mutually connected. In the crystal growth region 7, one corner located on the upstream side in the movement direction of the excimer laser beam 10 has an acute angle, and the corner is arranged so as to face one corner of the seed crystal growth region 6. Then, the corner portions facing each other are connected by a connecting portion 4 having a width of 5 μm. In this case, one side 6a of seed crystal growth region 6 and one side 7a of crystal growth region 7 connected to coupling portion 4 are arranged in a straight line, and another edge forming an acute corner of crystal growth region 7 is formed. The side 9 is inclined by 30 ° from the vertical direction with respect to the straight sides 6a and 7a with respect to the vertical direction.
[0041]
Next, an energy density of 380 mJ / cm was applied to the seed crystal forming region 5 of the first island region. ² When the excimer laser beam 10 is applied, a crystalline Si film is obtained in which the {100} crystal plane is preferentially oriented parallel to the film plane. The excimer laser light 10 is intermittently irradiated in a pulse form from an excimer laser whose irradiation area has a linear shape, and the linear irradiation area is orthogonal to the moving direction of the excimer laser light 10 indicated by an arrow 8. I have.
[0042]
Next, the width of the linear irradiation region of the excimer laser beam 10 (the melting width of the amorphous Si film 3) is 2 μm, and the irradiation position of the excimer laser beam 10 is moved in the direction of arrow 8 by 0.5 μm at a time. , Energy density is 450mJ / cm ² The excimer laser beam 10 is repeatedly applied to the seed crystal growth region 6. Thereby, in the seed crystal growth region 6, the crystalline Si film formed in the seed crystal forming region 5 becomes a seed crystal, and the crystal plane parallel to the film surface in the crystalline Si film is substantially {100} plane. Then, a crystalline Si film having a crystal orientation of approximately <001> orientation grows in the lateral direction along the direction of arrow 8 in which the excimer laser beam 10 moves. In this case, in the seed crystal growth region 6, as shown in FIG. 2A, the crystal plane parallel to the film surface of the crystalline Si film grown from the seed crystal formation region 5 is substantially {100} plane. Along the direction of the arrow 8 where the excimer laser beam 10 moves, a plurality of elongated crystal grains 11 having a crystal orientation of approximately <001> are formed. Here, the moving direction of the excimer laser light 10 indicated by the arrow 8 is parallel to one side 6a of the seed crystal growth region 6 and one side 7a of the crystal growth region 7, respectively.
[0043]
Next, the width of the linear irradiation region of the excimer laser beam 10 (the melting width of the amorphous Si film 3) is 2 μm, and the irradiation position of the excimer laser beam 10 is moved in the direction of arrow 8 by 0.5 μm at a time. , Energy density is 450mJ / cm ² The crystal growth region 7 is repeatedly irradiated with the excimer laser beam 10 of FIG. As a result, of the plurality of crystal grains 11, only the single crystal grain 11 closest to the joint 4 at the boundary between the seed crystal growth region 6 and the crystal growth region 7 is selected by the joint 4. Using the crystal grains 11 as seed crystals, the crystal plane parallel to the film plane is substantially {100} plane, and the crystal orientation along the direction of the arrow 8 in which the excimer laser beam 10 moves is set in the entire crystal growth region 7. A single domain crystal 12, which is a crystalline Si film having a substantially <001> orientation, is formed.
[0044]
FIG. 2B shows a case where the crystal growth region 7 is formed such that one side located on the upstream side in the moving direction of the excimer laser light 10 indicated by an arrow 8 is perpendicular to the moving direction of the excimer laser light 10. Is shown. In this case, when the excimer laser light 10 whose irradiation area is linear passes through the side 9 a perpendicular to the moving direction of the excimer laser light 10 indicated by the arrow 8, the linear irradiation of the excimer laser light 10 is performed. The region and a side 9a perpendicular to the direction of the arrow 8 in which the excimer laser beam 10 moves are parallel to each other. For this reason, in a region of the crystal growth region 7 distant from the bonding portion 4 along the side 9a, the excimer laser beam 10 is irradiated before the crystal grains 11 of the crystalline Si film selected at the bonding portion 34 grow. Therefore, a crystal nucleus 13 having a random crystal orientation is generated. As a result, crystal grains 14 grown in the crystal growth region 7 with the random crystal nuclei 13 having this crystal orientation as seed crystals are generated, and the single domain crystal 12 cannot be obtained.
[0045]
On the other hand, according to the method of forming a semiconductor thin film of the present invention, one side 6a of the seed crystal growth region 6 and one side 7a of the crystal growth region 7 coupled to the coupling portion 4 are arranged in a straight line. The other side 9 forming the acute corner of the region 7 is inclined by 30 ° from the vertical direction with respect to the straight sides 6a and 7a with respect to the vertical direction, and the excimer laser light 10 indicated by the arrow 8 Are parallel to one side 6a of the seed crystal growth region 6 and one side 7a of the crystal growth region 7, respectively, so that the coupling portion 4 extends along the side 9a of the crystal growth region 7 as shown in FIG. The generation of random crystal nuclei 13 in the crystal orientation due to the irradiation of excimer laser light 10 in a region away from the crystal is prevented, and only a single crystal grain 11 that has passed through the bonding portion 4 is reliably converted into a single domain crystal 12. Grow Door can be.
[0046]
With such a configuration, the method for forming a semiconductor thin film of the present invention irradiates a seed crystal formation region of the semiconductor thin film with an energy beam having a specific energy density in a pulsed manner so that a specific crystal plane is parallel to the film plane. A seed crystal that is preferentially oriented is formed, and then the energy beam is moved in directions parallel to one side 6a of the seed crystal growth region and one side 7a of the crystal growth region, and the specific crystal orientation of the seed crystal is changed. The energy density and the amount of movement of the energy beam are set so that the energy beam is preferentially oriented in the moving direction of the energy beam, and the energy beam is moved from the seed crystal growth region to the crystal growth region while moving the irradiation position of the energy beam from the seed crystal. Are repeatedly irradiated in a pulse shape to laterally grow a semiconductor thin film inheriting a specific crystal orientation of the seed crystal. Thus, according to the method of forming a semiconductor thin film of the present invention, a semiconductor thin film having a specific crystal plane parallel to the film surface of the seed crystal and having a specific crystal orientation in the moving direction of the energy beam can be formed.
[0047]
Hereinafter, setting of process conditions in the method for forming a semiconductor thin film of the present invention will be described in detail.
[0048]
When an amorphous Si film formed on an insulating substrate is repeatedly irradiated with an energy beam having a predetermined range of energy density in a pulse shape, a specific crystal plane is preferentially parallel to the film surface of the amorphous Si film. An oriented crystal is formed.
[0049]
FIG. 6 shows an X-ray symmetric reflection of a crystalline Si film crystallized by repeatedly irradiating a 50 nm-thick amorphous Si film formed on a glass substrate with changing the energy density of pulsed excimer laser light. The result evaluated by diffraction is shown.
[0050]
The normalized intensity on the vertical axis shown in FIG. 6 indicates the diffraction intensity when the crystallized crystalline Si film is irradiated with X-rays, and the diffraction intensity when the non-oriented Si powder is irradiated with X-rays. It is obtained by dividing by the intensity. Generally, the higher the normalized intensity of each diffraction surface, the stronger the orientation of the diffraction surface. Incidentally, in the X-ray diffraction of the cubic Si crystal, the diffraction of the {100} plane and the {200} plane of the crystal plane were not observed due to the annihilation law, and the orientation of the {100} plane was the crystal plane. Is observed as a diffraction peak on the {400} plane.
[0051]
As shown in FIG. 6, 380 mJ / cm ² By irradiating the amorphous Si film with a pulsed excimer laser beam having a nearby laser energy density, it can be seen that the {100} crystal plane is very strongly oriented parallel to the film surface. On the other hand, if the energy density of the pulsed excimer laser light is too low, the melting of the amorphous Si film is insufficient, and if the energy density of the pulsed excimer laser light is too high, the amorphous The crystalline Si film is melted, and a crystalline Si film in which the {100} plane of the crystal plane is preferentially oriented parallel to the film surface cannot be obtained.
[0052]
On the other hand, when the energy density in a predetermined range and the moving amount in a predetermined range are set on the amorphous Si film formed on the insulating substrate, and the energy beam is repeatedly irradiated in a pulsed manner while moving the energy beam, the energy beam moves. A phenomenon occurs in which a specific crystal orientation is preferentially oriented in the direction. In the case of Si (silicon), this crystal orientation is the <001> orientation.
[0053]
In the above configuration, first, the amorphous Si film in a region where a seed crystal is to be formed (seed crystal forming region 5) is repeatedly irradiated with an energy beam having a predetermined range of energy density in a pulsed manner. A seed crystal is formed in which the {100} plane of the crystal plane is preferentially oriented in parallel with the film plane of FIG.
[0054]
Next, in the seed crystal growth region 6, the irradiation position of the energy beam set to a predetermined range of energy density and a predetermined amount of movement is repeatedly irradiated in a pulse shape while moving from the seed crystal to grow the crystal laterally. By doing so, it is possible to obtain a crystalline Si film in which the crystal plane parallel to the seed crystal film plane is substantially the {100} plane and the crystal orientation is substantially <001> in the direction in which the pulsed energy beam moves. It becomes possible. In this case, the moving direction of the energy beam is parallel to one side 6a of the seed crystal growth region. In the seed crystal forming region 5, some crystal grains whose crystal faces other than the {100} crystal plane are parallel to the film face of the seed crystal are also formed, but these crystal grains are unstable. During the lateral crystal growth, stable growth cannot be achieved, and the {100} plane of the crystal plane is absorbed by other crystal grains parallel to the seed crystal film plane.
[0055]
Thus, the entire crystal plane parallel to the film surface of the seed crystal is substantially {100} in the entire seed crystal growth region 6, and the crystal orientation is substantially <001 in the direction of arrow 8 in which the pulsed energy beam moves. > A plurality of elongated crystal grains having an orientation are formed in the crystal growth direction.
[0056]
Next, only a single crystal grain closest to the bonding portion 4 is selected at the bonding portion 4, and the crystal grain parallel to the film surface is substantially {100} over the entire crystal growth region 7 using the crystal grain as a seed crystal. A single domain crystal 12 having a｝ plane and a crystal orientation substantially in the <001> direction is formed in the direction of arrow 8 in which the pulsed energy beam moves.
[0057]
In this case, one side 6a of seed crystal growth region 6 and one side 7a of crystal growth region 7 bonded to bonding portion 4 are arranged in a straight line, and another side forming an acute corner of crystal growth region 7 is formed. The side 9 is inclined by a predetermined angle from the vertical direction with respect to the vertical direction with respect to the straight sides 6a and 7a, and the moving direction of the energy beam is parallel to the linear sides 6a and 7a. This can prevent generation of random crystal nuclei 13 having a crystal orientation due to irradiation of the pulsed energy beam at a corner portion of the crystal growth region 7 away from the vicinity of the coupling portion 4, and more surely pass through the coupling portion 4. Crystal growth can be performed using only one crystal grain 11 as a seed crystal.
[0058]
In the method for forming a semiconductor thin film of the present invention, the energy density of the pulsed energy beam used for forming the seed crystal of the crystalline Si film is 360 to 400 mJ / cm. ² Is set to The energy density of the pulsed energy beam used to form the seed crystal is 360 mJ / cm ² If it is smaller than that, the {100} plane of the crystal plane of the seed crystal is not preferentially oriented parallel to the film plane of the amorphous Si film. Further, the energy density of the pulsed energy beam used for forming the seed crystal is 400 mJ / cm. ² If it is larger than that, the amorphous Si film to be crystallized melts to the underlying interface, and the {100} crystal plane of the seed crystal is not oriented parallel to the film surface of the amorphous Si film. In this embodiment, the energy density of the pulsed energy beam used for forming the seed crystal is 380 mJ / cm. ² Therefore, a seed crystal in which the {100} crystal plane is preferentially oriented parallel to the film surface of the amorphous Si film is obtained.
[0059]
In the method for forming a semiconductor thin film according to the present invention, the energy density of the pulsed energy beam used for the lateral crystal growth is 400 to 500 mJ / cm. ² Is set to The energy density of the pulsed energy beam used for lateral crystal growth is 400 mJ / cm. ² If it is smaller than the above, crystal grains that will become a crystalline Si film having a crystal orientation of approximately <001> in the direction in which the pulsed energy beam moves do not grow. The energy density of the pulsed energy beam used for the lateral crystal growth is 500 mJ / cm. ² Even in the case where it is larger than that, the crystal grain which becomes a crystalline Si film having a crystal orientation of approximately <001> orientation does not grow in the moving direction of the pulsed energy beam. In this embodiment, the energy density of the pulsed energy beam used for the lateral crystal growth is 450 mJ / cm. ² Therefore, it is possible to grow elongated crystal grains that become a crystalline Si film having a crystal orientation of approximately <001> in the direction in which the pulsed energy beam moves.
[0060]
Furthermore, in the method for forming a semiconductor thin film of the present invention, the peak position of the energy density distribution of the energy beam in the moving direction of the pulsed energy beam used for the lateral crystal growth is within the irradiation area of the previous energy beam during repeated irradiation. Is set to As shown in FIG. 7B, the peak position of the energy density distribution 30 of the energy beam in the moving direction of the pulsed energy beam used for the lateral crystal growth corresponds to the previous energy beam irradiation area 29 during repeated irradiation. Outside, the lateral crystal growth using the crystal formed by the previous pulsed energy beam irradiation as a seed crystal does not progress well, and irregular crystal nuclei are formed. As a result, the crystal orientation Crystals grow uncontrolled. In this embodiment, as shown in FIG. 7A, the peak position of the energy density distribution 30 of the energy beam in the moving direction 8 of the pulsed energy beam used for the lateral crystal growth, Since it is inside the beam irradiation region 29, a crystal with a controlled crystal orientation can be grown.
[0061]
Further, in the method for forming a semiconductor thin film of the present invention, the amount of one movement of the pulsed energy beam used for the lateral crystal growth is set to 10 μm or less. When the amount of one movement of the pulsed energy beam used for the lateral crystal growth is larger than 10 μm, the peak position of the energy density distribution 30 of the energy beam in the moving direction of the pulsed energy beam is determined by the repeated irradiation. Even inside the irradiation region 29 of the previous energy beam, it is impossible to grow the crystal in the lateral direction for the moving distance due to the solidification speed of the molten portion, so that the crystal in which the crystal orientation of the crystal plane is not controlled grows. Become. In this embodiment, since the pulse energy beam used for the lateral crystal growth has a single movement of 0.5 μm, it is possible to grow a crystal in which the crystal orientation of the crystal plane is controlled.
[0062]
Further, in the method for forming a semiconductor thin film according to the present invention, the thickness of the crystalline Si film as the semiconductor thin film is set to 10 to 200 nm. When the thickness of the crystalline Si film, which is a semiconductor thin film, is less than 10 nm, problems such as poor growth are likely to occur. On the other hand, when the thickness of the crystalline Si film, which is a semiconductor thin film, is greater than 200 nm, it becomes difficult for crystal grains to become a crystalline Si film whose crystal direction is substantially <001> in the moving direction of the pulsed laser. , And no single domain is formed. In the present embodiment, since the thickness of the crystalline Si film, which is a semiconductor thin film, is 50 nm, problems such as poor film formation do not occur, and only a single crystal grain can be grown in the crystal growth region 7. .
[0063]
Further, in the method for forming a semiconductor thin film of the present invention, the width of the coupling portion 4 connecting the seed crystal growth region 6 and the crystal growth region 7 is set to 20 μm or less. When the width of the joint 4 connecting the seed crystal growth region 6 and the crystal growth region 7 is larger than 20 μm, the effect of selecting the crystal orientation of the crystal grain at the joint 4 is reduced, and the seed crystal growth region 6 The plurality of elongated crystal grains grown in the step (1) pass through the bonding portion and grow to the crystal growth region 7, so that the single domain crystal 12 cannot be formed. In the present embodiment, since the width of the joint 4 connecting the seed crystal growth region 6 and the crystal growth region 7 is 5.0 μm, a single crystal grain closest to the joint 4 in the seed crystal growth region 6 is formed. Only the crystal can pass through the coupling portion and grow into the crystal growth region 7 to form the single domain crystal 12.
[0064]
Further, in the method for forming a semiconductor thin film of the present invention, one side 6a of seed crystal growth region 6 and one side 7a of crystal growth region 7 coupled to coupling portion 4 are arranged in a straight line, and at least crystal growth region 7 The other side 9 forming the acute-angled corner is inclined by 10 to 80 ° from the vertical direction with respect to the vertical direction with respect to each of the linear sides 6a and 7a, and the energy beam is aligned with each of the linear sides. It is set to move in parallel with 6a and 7a. As a result, at least the other side 9 forming the acute corner of the crystal growth region 7 is inclined by 10 to 80 ° from the vertical direction with respect to the moving direction of the energy beam, based on the vertical direction. When at least the other side 9 forming the acute corner of the crystal growth region 7 is smaller than the inclination of 10 ° from the vertical direction with respect to the vertical direction with respect to each of the straight sides 6a and 7a, At the corner of the crystal growth region 7 away from the coupling portion 4, a crystal nucleus 13 having a random crystal orientation is generated by irradiation with a pulsed energy beam. Further, when at least the other side 9 forming the acute-angled corner portion of the crystal growth region 7 is larger than the inclination of 80 ° from the vertical direction with respect to the vertical direction with respect to the straight sides 6a and 7a. Requires a long distance until it spreads over the large-area crystal growth region 7, and thus has a design problem, and it is difficult to apply the semiconductor device and the liquid crystal display device. In the present embodiment, at least the other side 9 forming the acute corner of the crystal growth region 7 is inclined by 30 ° from the vertical direction with respect to the straight sides 6a and 7a with respect to the vertical direction. Therefore, generation of random crystal nuclei 13 in the crystal orientation due to irradiation of the pulsed energy beam at the corners of crystal growth region 7 remote from coupling portion 4 is prevented, and single domain crystal 12 is formed in crystal growth region 7. Can be formed.
[0065]
Here, FIG. 5 shows that the width of the coupling portion 4 that couples the seed crystal growth region 6 and the crystal growth region 7, and at least the other side 9 that forms an acute corner of the crystal growth region 7, FIG. 9 is a schematic diagram showing an angle inclined from the vertical direction with respect to each of the straight sides 6a and 7a with respect to the vertical direction, and shows a width of a coupling portion 4 coupling the seed crystal growth region 6 and the crystal growth region 7; Is D, and the angle at which the other side 9 forming at least the acute corner of the crystal growth region 7 is inclined from the vertical direction is α.
[0066]
The crystal plane parallel to the film plane obtained in this way is controlled to be substantially {100} plane, and the crystalline Si film whose crystal direction is substantially <001> in the moving direction 8 of the pulsed energy beam, or If the crystal plane parallel to the film plane is substantially a {100} plane and a single-domain crystalline Si film having a crystal orientation of approximately the <001> direction in the moving direction 8 of the pulsed energy beam, the carrier mobility is increased. A TFT which is large, has a small threshold voltage, and has small variations in carrier mobility and threshold voltage and has improved electrical characteristics can be obtained.
[0067]
FIG. 3 is a cross-sectional view of a main part of a semiconductor device using a crystalline Si film formed by the method for forming a semiconductor thin film of the present invention.
[0068]
In the semiconductor device shown in FIG. 3, a thin film transistor or the like is formed on a crystalline Si film formed by the method for forming a semiconductor thin film shown in FIG. 1, and a liquid crystal driver, a semiconductor memory, and a main part of a semiconductor logic circuit using the thin film transistor are formed. Represents.
[0069]
In the semiconductor device shown in FIG. 3, a 200 nm-thick SiO.sub.2 is formed on an insulating substrate 1 such as a glass substrate. ₂ The film 2 is formed. SiO ₂ In a predetermined region on the film 2, a crystalline Si film 15 is formed by the method for forming a semiconductor thin film shown in FIG. A channel region 15a is formed at the center of the crystalline Si film 15, and a gate SiO 2 is formed on the channel region 15a. ₂ WSi through film 16 ₂ / A gate electrode 17 made of polycrystalline Si is formed. A drain region 15b and a source region 15c are formed on both sides of the channel region 15a, respectively. End of crystalline Si film 15 and SiO ₂ On the film 2, a gate SiO ₂ Film 16 and an interlayer insulating film of SiO ₂ A film 18 is formed in order, and a gate SiO on the channel region 15a is formed. ₂ The area around the film 16 and the gate electrode 17 is also SiO ₂ Covered by membrane 18. A gate SiO is formed on the drain region 15b and the source region 15c. ₂ Film 16 and SiO ₂ Contact holes provided in the film 18 are formed, and these contact holes and SiO on the channel region are formed. ₂ SiO except film 18 ₂ An Al wiring 9 is formed on the film 18. Al wiring 9 is connected to drain region 15b and source region 15c. SiO on Al wiring 9 and channel region 15c ₂ An SiN protective film 20 is formed so as to cover film 18, and an opening 20 a is formed in a predetermined region of SiN protective film 20 so that Al wiring 9 is exposed.
[0070]
Subsequently, a method for manufacturing the semiconductor device shown in FIG. 3 will be described.
[0071]
A 200 nm thick SiO 2 is formed on an insulating substrate 1 such as a glass substrate by a plasma CVD method. ₂ The film 2 is formed. Furthermore, SiO ₂ A crystalline Si film 15 is formed on the film 2 by the method of forming a semiconductor thin film shown in FIG. ₄ Gas and O ₂ The crystalline Si film 15 is patterned into a predetermined shape by RIE using gas. After that, the SiO ₂ On the film 2 and the crystalline Si film 15, TEOS gas and O ₃ Gate SiO by plasma CVD using gas ₂ A film 16 is formed, and a gate SiO ₂ WSi is formed on the film 16 by sputtering. ₂ / Form polycrystalline Si. Then, CF ₄ Gas and O ₂ By patterning by RIE using gas, a gate SiO 2 is formed on the crystalline Si film 15. ₂ WSi through film 16 ₂ / Form gate electrode 17 made of polycrystalline Si.
[0072]
Next, using the gate electrode 17 as a mask, P (phosphorus) and B (boron) are implanted into the crystalline Si film 15 by ion doping to form a source region 15c and a drain region 15b. A channel region 15a is formed between the source region 15c and the drain region 15b masked by the gate electrode 17. After that, TEOS gas and O ₃ SiO 2 as an interlayer insulating film is formed by a plasma CVD method using a gas. ₂ A film 18 is formed, and the CF is so formed as to expose the surfaces of the drain region 15b and the source region 15c in predetermined regions on the drain region 15b and the source region 15c, respectively. ₄ Gas and CHF ₃ Etching is performed by a RIE method using a gas to form a contact hole. In this case, the gate SiO on the channel region 15a ₂ The area around the film 16 and the gate electrode 17 is SiO 2 ₂ Covered by membrane 18.
[0073]
Next, each opening where a contact hole is formed on the drain region 15b and the source region 15c and SiO 2 ₂ An Al alloy layer is formed on the film 18 by a sputtering method. ₃ Gas and Cl ₂ The Al alloy layer is patterned into a predetermined shape by RIE using a gas, and SiO 2 covering the respective openings where the contact holes are formed on the drain region 15b and the source region 15c and the gate electrode 17 are formed. ₂ SiO except film 18 ₂ An Al wiring 19 is formed on the film 18. Al wiring 19 is electrically connected to drain region 15b and source region 15c, respectively.
[0074]
Next, the SiO 2 covering the gate electrode 17 is ₂ SiH is entirely formed on the film 18 and the Al wiring 19. ₄ Gas, NH ₃ Gas and N ₂ The SiN protective film 20 is formed by a plasma CVD method using a gas. Finally, a part of the SiN protective film 20 is replaced with CF. ₄ Gas and CHF ₃ Etching is performed by RIE using a gas, and an opening is formed in a predetermined region of the SiN protective film 20 so that the Al wiring 9 is exposed.
[0075]
Thus, a semiconductor device such as a liquid crystal driver, a semiconductor memory, and a semiconductor logic circuit including semiconductor elements such as a thin film transistor, a resistor, and a capacitor can be manufactured.
[0076]
FIG. 4 is a sectional view of a main part of a liquid crystal display device using the semiconductor device shown in FIG.
[0077]
The liquid crystal display device shown in FIG. 4 has a thickness of 200 nm on an insulating substrate 1 such as a glass substrate. ₂ The film 2 is formed. SiO ₂ In a predetermined region on the film 2, a crystalline Si film 15 is formed by the method for forming a semiconductor thin film shown in FIG. A channel region 15a is formed at the center of the crystalline Si film 15, and a gate SiO 2 is formed on the channel region 15a. ₂ WSi through film 16 ₂ / A gate electrode 17 made of polycrystalline Si is formed. A drain region 15b and a source region 15c are formed on both sides of the channel region 15a, respectively. End of crystalline Si film 15 and SiO ₂ On the film 2, a gate SiO ₂ Film 16 and an interlayer insulating film of SiO ₂ A film 18 is formed in order, and a gate SiO on the channel region 15a is formed. ₂ The area around the film 16 and the gate electrode 17 is also SiO ₂ Covered by membrane 18. A gate SiO is formed on the drain region 15b and the source region 15c. ₂ Film 16 and SiO ₂ Contact holes provided in the film 18 are formed, and these contact holes and SiO on the channel region are formed. ₂ SiO except film 18 ₂ An Al wiring 9 is formed on the film 18. Al wiring 9 is connected to drain region 15b and source region 15c. SiO on Al wiring 9 and channel region 15c ₂ SiO so as to cover the film 18 ₂ A film 21 is formed, and SiO formed on the source region 15c side is formed. ₂ A through-hole is provided in a predetermined region of the film 21 so that the Al wiring 9 is exposed.
[0078]
Through hole and SiO ₂ A pixel electrode 22 made of an ITO (Indium Tin Oxide) film is formed on the film 21, and is connected to the metal wiring 9 through a through hole. The pixel electrode 12 made of an ITO film is formed by a sputtering method and is patterned into a predetermined shape so as to cover a thin film transistor (TFT) having the gate electrode 17, the source region 15c, and the drain region 15b. . Pixel electrode 22 and SiO ₂ On the film 21, a SiN protective film 23 and a polyimide film 24 as an alignment film are formed in order. The SiN protective film 23 is formed by a plasma CVD method, and the polyimide film 24 as an alignment film is formed by an offset printing method, and the surface is flattened. Further, the polyimide film 24 as an alignment film is subjected to a rubbing treatment for aligning liquid crystal molecules in a predetermined direction.
[0079]
On the other hand, a color filter 26 that transmits predetermined light is formed on an insulating substrate 25 such as a glass substrate disposed so as to face the insulating substrate 1 on which the TFT portion is formed. The color filter 26 is formed by transferring a film having each of the red, green and blue photosensitive resin thin films onto the insulating substrate 25 by thermocompression bonding, and further performing patterning by photolithography. Is formed by providing a black matrix portion in the same space. A counter electrode 27 made of an ITO film is formed on the color filter 26 by a sputtering method, and a polyimide film 28 as an alignment film is formed on the counter electrode 27 by an offset printing method. Like the polyimide film 24, the polyimide film 28 is subjected to a rubbing process for aligning liquid crystal molecules in a predetermined direction.
[0080]
The liquid crystal display device shown in FIG. 4 includes an insulating substrate 1 on which a semiconductor device including a TFT portion, a pixel electrode 22 and the like is formed, and an insulating substrate 25 on which a color filter 26, a counter electrode 27 and the like are formed. Liquid crystal is injected between the quartz substrate 1 and the glass substrate 31 by bonding with a sealing resin.
[0081]
Subsequently, a method for manufacturing the liquid crystal display device shown in FIG. 4 will be described.
[0082]
A 200 nm thick SiO 2 is formed on an insulating substrate 1 such as a glass substrate by a plasma CVD method. ₂ The film 2 is formed. Furthermore, SiO ₂ A crystalline Si film 15 is formed on the film 2 by the method of forming a semiconductor thin film shown in FIG. ₄ Gas and O ₂ The crystalline Si film 15 is patterned into a predetermined shape by RIE using gas. After that, the SiO ₂ On the film 2 and the crystalline Si film 15, TEOS gas and O ₃ Gate SiO by plasma CVD using gas ₂ A film 16 is formed, and a gate SiO ₂ WSi is formed on the film 16 by sputtering. ₂ / Form polycrystalline Si. Then, CF ₄ Gas and O ₂ By patterning by RIE using gas, a gate SiO 2 is formed on the crystalline Si film 15. ₂ WSi through film 16 ₂ / Form gate electrode 17 made of polycrystalline Si.
[0083]
Next, using the gate electrode 17 as a mask, P (phosphorus) and B (boron) are implanted into the crystalline Si film 15 by ion doping to form a source region 15c and a drain region 15b. A channel region 15a is formed between the source region 15c and the drain region 15b masked by the gate electrode 17. After that, TEOS gas and O ₃ SiO 2 as an interlayer insulating film is formed by a plasma CVD method using a gas. ₂ A film 18 is formed, and the CF is so formed as to expose the surfaces of the drain region 15b and the source region 15c in predetermined regions on the drain region 15b and the source region 15c, respectively. ₄ Gas and CHF ₃ Etching is performed by a RIE method using a gas to form a contact hole. In this case, the gate SiO on the channel region 15a ₂ The area around the film 16 and the gate electrode 17 is SiO 2 ₂ Covered by membrane 18.
[0084]
Next, each opening in which a contact hole is formed on the drain region 15b and the source region 15c and SiO 2 ₂ An Al alloy layer is formed on the film 18 by a sputtering method. ₃ Gas and Cl ₂ The Al alloy layer is patterned into a predetermined shape by RIE using a gas, and SiO 2 covering the respective openings where the contact holes are formed on the drain region 15b and the source region 15c and the gate electrode 17 are formed. ₂ SiO except film 18 ₂ An Al wiring 19 is formed on the film 18. Al wiring 19 is electrically connected to drain region 15b and source region 15c, respectively.
[0085]
Next, the SiO 2 covering the gate electrode 17 is ₂ TEOS gas and O ₃ SiO 2 by plasma CVD using a gas ₂ A film 21 is formed and SiO ₂ Part of the film 21 is CF ₄ Gas and CHF ₃ Etching is performed by RIE using a gas, and SiO 2 formed on the source region 15c side is formed. ₂ A through hole is formed in a predetermined region of the film 21 so that the Al wiring 9 is exposed.
[0086]
Next, a pixel electrode 22 made of an ITO film is formed by a sputtering method, and HCl and FeCl 2 are formed. ₃ Is used to pattern the pixel electrode 22 into a predetermined shape. The pixel electrode 22 is patterned so as to cover the TFT portion having the gate electrode 17, the source region 15c, and the drain region 15b. Then, the pixel electrode 22 and SiO ₂ SiH on the film 21 ₄ Gas, NH ₃ Gas and N ₂ An SiN protective film 23 is formed by a plasma CVD method using a gas, a polyimide film 24 as an alignment film is formed on the SiN protective film 23 by an offset printing method, and a rubbing process is performed on the polyimide film 24.
[0087]
Next, a film with each of the red, green, and blue photosensitive resin thin films is transferred by thermocompression bonding to an insulating substrate 25 such as a glass substrate different from the insulating substrate 1 on which the TFT portion is formed, and is subjected to photolithography. The film is patterned, and a black matrix portion is similarly formed in a space between red, green, and blue to form a color filter 26. Thereafter, a counter electrode 27 made of an ITO film is formed on the color filter 26 by a sputtering method, and a polyimide film 28 as an alignment film is formed on the counter electrode 27 by an offset printing method. A rubbing treatment is performed on the surface.
[0088]
Next, the insulating substrate 25 on which the color filter 26 and the counter electrode 27 are formed and the insulating substrate 1 on which the semiconductor device including the TFT portion, the pixel electrode 22, and the like are formed are bonded with a sealing resin. In this case, spherical silica is sprayed in order to keep the distance between the two insulating substrates 1 and 25 constant. Then, after injecting a liquid crystal between the insulating substrate 1 and the insulating substrate 25, a polarizing plate is attached, and a driver IC and the like are mounted on the periphery to manufacture a liquid crystal display device.
[0089]
In the method of forming a semiconductor thin film according to the embodiment of the present invention described above, a Si film (crystalline Si film) was described as an example of a semiconductor thin film. However, a SiGe film, a GaAs film, a GaP film, an InP film, or the like may be used as the semiconductor thin film. The same effect can be obtained by using.
[0090]
Although a pulsed excimer laser beam was used for the lateral growth of the crystalline Si film, the same effect can be obtained by using other energy beams such as other pulsed laser light, pulsed light, and pulsed charged particles. Is obtained.
[0091]
As described above in detail, in the formation direction of the semiconductor thin film of the present invention, an amorphous or polycrystalline semiconductor film is repeatedly irradiated with an energy beam having an energy density in a specific range, so that the semiconductor film becomes {100} parallel to the film surface.種 Form a seed crystal in which the plane is preferentially oriented, and then repeatedly irradiate while moving the irradiation position of the pulsed energy beam in which a specific range of energy density and a specific amount of movement are set. The crystal Si film having a crystal plane parallel to the film plane is substantially {100} plane and having a substantially <001> orientation in the direction of movement of the pulsed energy beam, thereby forming a softening point temperature of the substrate. Obtained below. Further, one side 6a of seed crystal growth region 6 and one side 7a of crystal growth region 7 coupled to coupling portion 4 are arranged in a straight line, and other sides forming acute corners of crystal growth region 7 are formed. 9 is inclined by a predetermined angle from the vertical direction with respect to the vertical direction with respect to each of the straight sides 6a and 7a, and the energy beam moves in parallel with each of the straight sides 6a and 7a, whereby the crystal is formed. Prevention of random crystal nuclei having a crystal orientation caused by irradiation of the pulsed energy beam at the corner of the growth region 7, the crystal plane parallel to the film surface being substantially {100}, and the movement of the pulsed energy beam In this case, a single-domain crystalline semiconductor film having a crystal orientation of approximately <001> is obtained at a temperature lower than the softening point of the substrate.
[0092]
By using a single-domain crystalline semiconductor film in which the crystal orientation is controlled as described above, the performance of the semiconductor device can be improved.
[0093]
【The invention's effect】
In the method for forming a semiconductor thin film according to the present invention, a semiconductor film is formed by forming a first island-shaped region arranged on the upstream side in a moving direction of a rectangular energy beam, And a second island-shaped region in which corner portions are connected to each other by a connecting portion, and one side of the first island-shaped region and one side of the second island-shaped region are aligned in the connecting portion. The semiconductor film is patterned such that the corners of the second island-shaped region at the coupling portion are acute, and then the first energy density is transferred to the first island-shaped region without moving the energy beam. Irradiate to form a seed crystal forming region in which a predetermined crystal plane is preferentially oriented, and then apply an energy beam set to a second energy density and a predetermined moving amount from the seed crystal forming region to the first island shape. Repetition in the area Forming a seed crystal growth region in which a predetermined crystal orientation is oriented along the moving direction of the energy beam in the first island region, and furthermore, a second energy density and a predetermined Is repeatedly irradiated with an energy beam set to the amount of movement of the crystalline semiconductor thin film oriented in a predetermined crystal orientation along the direction of energy beam movement based on crystal grains selected from the seed crystal growth region. By crystal growth in the direction, the crystal plane parallel to the film surface in the crystal-grown thin film is constant, and the crystal orientation of the crystal plane is also constant.
[Brief description of the drawings]
FIG. 1 is a perspective view illustrating a method for forming a semiconductor thin film according to an embodiment of the present invention.
FIGS. 2A and 2B are schematic diagrams showing a state of crystal grain growth in a method of forming a semiconductor thin film, respectively.
FIG. 3 is a sectional view of a main part of a semiconductor device using a crystalline Si film formed by the method for forming a semiconductor thin film of the present invention.
4 is a cross-sectional view of a main part of a liquid crystal display device using the semiconductor device shown in FIG.
FIG. 5 is a view for explaining the definition of the width (D) of the joint and the angle (α) at which the side extending from the joint is inclined with respect to the direction perpendicular to the moving direction of the linear energy beam in the present invention. FIG.
FIG. 6 is a graph showing an X-ray diffraction measurement result of a crystalline Si film crystallized by changing an energy density of an excimer laser beam on an amorphous Si film.
FIGS. 7A and 7B are schematic diagrams showing a relationship between a peak position of an energy density distribution in a moving direction of an energy beam to be repeatedly irradiated and a previous irradiation region.
FIGS. 8A and 8B are schematic views showing crystal grains growing in a conventional method of forming a semiconductor thin film.
[Explanation of symbols]
1 Insulating substrate
2 SiO ₂ film
3 Amorphous Si film
4 Joint
5 seed crystal formation area
6 seed crystal growth area
7 Crystal growth area
8 Moving direction of excimer laser beam
9 Other sides forming acute corners of the crystal growth region
10 Excimer laser light
11 crystal grains
12 Single domain crystal
13 Crystal nucleus
14 crystal grains
15 Crystalline Si film
16 Gate SiO ₂ film
17 Gate electrode
18 SiO ₂ film
19 Al wiring
20 SiN protective film
21 SiO ₂ film
22 Pixel electrode
23 SiN protective film
24 Polyimide film
25 Insulating substrate
26 Color filter
27 Counter electrode
28 Polyimide film
29 Energy beam previous irradiation area
30 Energy density distribution of the energy beam of this irradiation
31 Amorphous semiconductor film
32 First island area
33 Second island area
34 Joint
35 Moving direction of linear energy beam
36 crystal nucleus
D Width of joint
α Angle at which the sides forming the acute corners of the crystal growth region are inclined with respect to the direction perpendicular to the direction of movement of the linear energy beam.

Claims (16)

A semiconductor thin film is grown by irradiating an energy beam having a linear beam irradiation area on a semiconductor film formed on an insulating substrate or an insulating film while moving the energy beam in a direction perpendicular to the beam irradiation area. A method of growing a semiconductor thin film including a crystal growth step of:
The semiconductor film is formed by a first rectangular island-shaped region arranged on the upstream side in the moving direction of the energy beam, and a coupling portion disposed on the downstream side in the moving direction of the energy beam with respect to the first island-shaped region. A second island-shaped region in which each corner is joined to each other, and one side of the first island-shaped region and one side of the second island-shaped region are linearly joined at the joint portion, Patterning the semiconductor film so that a corner of the second island region in the coupling portion becomes an acute angle;
Irradiating the first island region with the first energy density without moving the energy beam, thereby forming a seed crystal forming region in which a predetermined crystal plane is preferentially oriented;
Thereafter, the energy beam set to the second energy density and the predetermined moving amount is repeatedly irradiated from the seed crystal forming region to the first island region, and the predetermined crystal is moved along the moving direction of the energy beam. Forming a seed crystal growth region in which the orientation is oriented in the first island region;
The second island-shaped region is repeatedly irradiated with the energy beam set at a second energy density and a predetermined moving amount, and along the moving direction of the energy beam, the crystal grains selected from the seed crystal growing region are illuminated. A step of crystal growing a crystalline semiconductor thin film oriented in a predetermined crystal orientation in a lateral direction based on the
A method for forming a semiconductor thin film, comprising: The method of claim 1, wherein the crystal plane and the crystal orientation are substantially {100} plane and substantially <001> orientation, respectively. The method of claim 1, wherein the second energy density is higher than the first energy density. The method according to claim 1, wherein the first energy density is 360 to 400 mJ / cm ² . The method according to claim 1, wherein the second energy density is 400 to 500 mJ / cm ² . 2. The method according to claim 1, wherein a peak position of an energy density distribution in a moving direction of the energy beam is located inside a previous irradiation area during repeated irradiation. The method according to claim 1, wherein an amount of movement of the energy beam at one time is 10 μm or less. The method of claim 1, wherein the semiconductor film has a thickness of 10 to 200 nm. The method of claim 1, wherein a width of the joint is set to 20 μm or less. A corner portion of the at least second island-shaped region is inclined at an angle of 10 to 80 ° from a vertical direction with respect to a vertical direction with respect to one side of the linear first island-shaped region and one side of the second island-shaped region. A method for forming a semiconductor thin film according to claim 1. The method according to claim 1, wherein the semiconductor film is Si (silicon). A semiconductor thin film formed on an insulating substrate or an insulating film, having a crystal plane of a substantially {100} plane and a crystal orientation substantially having a <001> orientation. 13. The semiconductor thin film according to claim 12, wherein the crystal grains form a single domain. A semiconductor device using a semiconductor thin film formed by the method for forming a semiconductor thin film according to claim 1. A semiconductor device using the semiconductor thin film according to claim 12. A display device using the semiconductor device according to claim 14.

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