JP2005012030A - Method of manufacturing crystalline semiconductor film, crystalline semiconductor film and method of manufacturing semiconductor device and semiconductor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form a high-performance crystalline semiconductor film by a simple process and at low costs. <P>SOLUTION: This method of manufacturing crystalline semiconductor film is characterised by having a process of forming a semiconductor film 2, a translucent insulating film formation process of forming a translucent insulating film 1 with film thickness so that reflectance with respect to first laser beam may be ≥20% lower than that of a bare area semiconductor film, an energy beam emitting process for emitting a first energy beam 9 by energy larger than a cap area completely melting energy while emitting a second energy beam 8 heating the translucent insulating film 1 and the semiconductor film 2, a cap area crystallization process for crystallizing a cap area semiconductor film based on the bare area semiconductor film crystallized in advance, and a removing process for removing the semiconductor film 2 from above the translucent insulating film 1. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention provides a crystalline semiconductor by crystallizing an amorphous semiconductor film by applying thermal energy to an amorphous semiconductor film formed on an amorphous insulating substrate by irradiating an energy beam such as a laser beam. The present invention relates to a method for manufacturing a crystalline semiconductor film for obtaining a film, a crystalline semiconductor film manufactured thereby, a method for manufacturing a semiconductor device using this crystalline semiconductor film, and a semiconductor device manufactured thereby.
[0002]
[Prior art]
Conventionally, an amorphous semiconductor thin film is formed on an amorphous insulating substrate or an amorphous insulating film (hereinafter referred to as an insulating substrate) provided on the substrate, and the amorphous semiconductor thin film A method of manufacturing a crystalline semiconductor film is known in which a crystalline semiconductor film is obtained by locally applying thermal energy to melt and crystallizing from a melted portion. Such a technique for crystallizing an amorphous semiconductor film has a history of nearly 30 years of research.
[0003]
Among them, a method of irradiating an amorphous semiconductor film with a laser beam as a thermal energy source has been studied for forming an SOI substrate in the 1980s, and since the 1990s, liquid crystal using low-temperature polysilicon technology has been developed. It is used for the development and mass production of panel manufacturing methods, and can be said to be the most proven method. In particular, when using an inexpensive substrate such as a glass substrate that cannot withstand high-temperature processes, it is necessary to apply thermal energy within an extremely short time. Oscillation laser light is used.
[0004]
For example, Non-Patent Document 1 discloses a method for crystallizing an amorphous silicon thin film formed on a glass substrate by irradiating it with a high-power excimer laser. The method for crystallizing an amorphous silicon thin film disclosed in Non-Patent Document 1 was started by Takashima et al., And in this Non-Patent Document 1, a laser beam irradiated on an amorphous silicon thin film The energy density is selected so that the upper part of the silicon thin film partially melts. Subsequent research has examined in detail the relationship between the energy density of the irradiated laser beam and the crystal grain size of the formed crystalline semiconductor film. As the energy density of the laser beam increases, the crystal grain size Has been shown to increase.
[0005]
Such an increase in crystal grain size has been studied in detail in Non-Patent Document 2, for example. According to this Non-Patent Document 2, in particular, the depth at which the amorphous semiconductor film is melted by the laser beam irradiation is just before the film thickness of the silicon thin film coincides, that is, the interface where the silicon thin film reaches the underlying substrate or the like. It is reported that huge crystal grains reaching several microns are formed just before melting. This is because the crystal grains slightly remaining at the interface with the lower layer of the silicon thin film serve as crystal nuclei at the start of crystal solidification, and it is possible to grow large crystal grains.
[0006]
However, in the crystallization method described in Non-Patent Document 2 above, when the energy density of the laser beam exceeds the value melted just before the interface of the silicon thin film and is completely melted until reaching the lower layer of the silicon thin film. A rapid cooling process occurs, random nucleation occurs, and the crystal grains become very small, or re-amorphization occurs. Therefore, in practice, in consideration of fluctuations in the output of the laser beam, the irradiated laser beam is set to an energy value slightly smaller than the energy density at which complete melting occurs. For this reason, the grain size of the crystal grains obtained is about several hundreds of nanometers depending on the laser light irradiation conditions.
[0007]
Under the laser light irradiation conditions based on this non-patent document 2, a crystalline silicon film is currently mass-produced as a low-temperature polysilicon formation technique. A typical carrier mobility of a TFT manufactured based on the technology of Non-Patent Document 2 is 150 cm in an n-channel TFT. ² / Vs, 80cm with p-channel channel TFT ² / Vs is obtained.
[0008]
As described above, when a liquid crystal panel having a semiconductor device using a polysilicon semiconductor film crystallized by irradiation with a pulsed laser beam is realized, the performance of the polysilicon semiconductor thin film becomes higher and further multifunctional. There is an increasing demand for realizing an active matrix TFT substrate in which circuit elements are integrated.
[0009]
In response to such a demand, when performing crystallization by laser light irradiation, the amorphous silicon film is completely melted and lateral growth is performed while suppressing the generation of random nuclei during crystallization. A method for obtaining TFT characteristics comparable to those of a single crystal substrate by controlling the above has been reported.
[0010]
At the research stage level, a wide variety of methods have been proposed, but these exist in the silicon thin film in such a way that a partially melted region exists so as to be in contact with the completely melted region. It is common as a basic idea that the crystal nucleus present in is used as a nucleus when the melted silicon film in the completely melted region starts crystallization. Below, two methods are demonstrated as an example of the method applicable to a practical use level.
[0011]
As a first method, a laser beam having an extremely high aspect ratio is formed, and a semiconductor film in an irradiation region irradiated with the laser beam is completely melted, and then irradiated with a laser beam adjacent to the irradiation region of the laser beam. There has been proposed a method (for example, Non-Patent Document 3) for inducing lateral growth of crystal growth from a crystalline semiconductor film existing in an unirradiated region.
[0012]
In this first method, a laser beam is irradiated along a scanning direction of the laser beam by irradiating a region shifted by a distance approximately the same as the distance at which the crystal can grow laterally by one melting. Crystal grains grown in the direction are obtained. For this reason, this crystallization method is described in J. J. et al. Im et al., Named SLS (Sequential Lateral Solidification).
[0013]
When this first method is used, there is an advantage that crystal grains having an arbitrary length can be formed on the entire surface without a gap.
[0014]
As a second method, for example, Non-Patent Document 4 describes a method in which an aluminum film, which is a beam reflecting film, is formed in a stripe shape on an amorphous silicon thin film, which is illustrated in FIG. 14 (b).
[0015]
FIG. 14A is a cross-sectional view showing a conventional crystal growth method described in Non-Patent Document 5, and FIG. 14B is a plan view showing a crystalline semiconductor film obtained by this method. .
[0016]
In the method of Non-Patent Document 4, as shown in FIG. 14A, a laser is applied over the entire surface of an amorphous silicon thin film (hereinafter referred to as “a-Si film”) 2 formed on the surface of the insulating glass substrate 5. When the beam is irradiated, the region 25 where the beam reflecting film 21 is not provided is exposed to the irradiated laser beam. Therefore, the amorphous silicon film is irradiated by the laser beam irradiation. In the region 26 where the beam reflection film 21 is provided, the region 26 where the beam reflecting film 21 is provided is an unmelted portion where the amorphous silicon film 2 is not melted.
[0017]
Such a completely melted portion and an unmelted portion are disposed so as to be adjacent to each other repeatedly by providing the beam reflecting film 21 in a stripe shape. The silicon melted in the completely melted region 25 undergoes crystal growth in the lateral direction based on the crystal nuclei existing in the unmelted region 26. As a result, as shown in FIG. In FIG. 2, crystal growth is performed from both end sides in contact with the unmelted region 26 toward the center of the melted region 25, and crystal grains are formed in a shape in which the crystal grains collide with each other at the substantially center.
[0018]
Non-Patent Document 5 describes a method of forming a region in which a silicon thin film is partially thick, instead of providing a beam reflecting film. In the method of Non-Patent Document 4, the thinly formed portion of the silicon thin film becomes a completely melted portion, and the thickly formed portion becomes a partially melted partially melted portion. The silicon thin film completely melted in the completely melted portion undergoes lateral crystal growth based on crystal nuclei existing in the partially melted portion.
[0019]
In these second methods, laser beam scanning is performed by patterning a reflective film on a silicon thin film into a desired shape, or by patterning a region formed in a thick film on a silicon thin film into a desired shape. Regardless of the direction, the direction in which the crystal grains extend can be determined, and there is an advantage that silicon films in which the directions in which the crystal grains extend are orthogonal to each other can be formed on the same substrate.
[0020]
However, the first method and the second method described above have the following problems.
[0021]
First, in the first method, the length of the lateral growth in which crystal grains grow by a single laser beam irradiation becomes as fine as 0.5 to 4 μm. Fine laser beam scanning is required. As a result, the processing time for crystallization becomes long, and it is necessary to prepare an apparatus having a special structure for irradiating laser light.
[0022]
In the first method, extremely elongated crystal grains that are elongated in the laser beam scanning direction are obtained. When a TFT is constituted by a crystalline silicon film having such crystal grains, the carrier mobility is very high in the TFT channel if the carrier flow direction and the crystal grain extension direction coincide with each other. Although the carrier flow direction is orthogonal to the direction in which the crystal grains extend, the carrier mobility is approximately equal to the case in which the carrier flow direction and the crystal grain extension direction match. It is known to deteriorate to about 1/3. In this first method, the direction in which crystal grains extend is determined by the scanning direction of the laser beam, so that high characteristics can be obtained only in one direction, and crystal grains extending in the other direction can be placed on the same substrate. Cannot be mixed. Therefore, this first method is not preferable because it is restricted by the design of circuit elements.
[0023]
On the other hand, the second method has a problem that the length of crystal grains is limited to one lateral growth distance.
[0024]
In the second method, since crystal growth is started based on crystal nuclei remaining in the unmelted region, it is necessary to form unmelted regions at predetermined intervals adjacent to the melted region. If the crystal grains grown in the transverse direction in the completely melted part are as close as possible to the crystal grains of the other completely melted part adjacent to the unmelted part, Since the initial nuclei of the unmelted part required at the start of crystal growth in the melted part may disappear due to laser light irradiation and fine crystal nuclei may be formed by random nucleation, the unmelted part has a certain size. Need to be formed. For this reason, the second crystallization method has a problem that the element size increases due to the area required to form the unmelted portion.
[0025]
For example, Patent Document 1 discloses a configuration for solving such a problem. 15 and 16 are cross-sectional views for explaining a conventional method for forming a crystalline semiconductor film disclosed in Patent Document 1. As shown in FIG.
[0026]
As shown in FIG. 15, first, the base coat film 6 is formed on the glass substrate 5. An a-Si film 2 is formed on the base coat film 6. Thereafter, a plurality of antireflection films 22 are formed in stripes on the a-Si film 2 at regular intervals. A reflection film 23 is laminated on each antireflection film 22.
[0027]
Next, the first laser beam is irradiated from the reflective film 23 side to the a-Si film 2. The bare region a-Si film 4 between the antireflection films 22 not covered by the antireflection film 22 is completely melted by the first irradiated laser beam. At this time, the cap region a-Si film 3 covered with the antireflection film 22 is not melted because the first laser beam is reflected by the reflection film 23.
[0028]
The bare region a-Si film 4 completely melted by the first irradiated laser beam is covered with the antireflection film 22 and thus the bare region a-Si film 4 is formed with the cap region a-Si film 3 not melted as a nucleus. Crystal growth occurs laterally from both ends of the a-Si film 4 toward the center of the bare region a-Si film 4 to form crystal grains.
[0029]
Thereafter, as shown in FIG. 16, the reflective film 23 is removed. Further, the a-Si film 2 is irradiated with the second laser beam from the antireflection film 22 side. The second laser beam irradiated is prevented from being reflected by the antireflection film 22 and completely melts the cap region a-Si film 3 covered by the antireflection film 92. The completely melted cap region a-Si film 3 is centered from both sides of the cap region a-Si film 3 with the crystal grains in the bare region a-Si film 4 formed when the first laser beam is irradiated as a nucleus. The crystal is grown in the lateral direction to form crystal grains.
[0030]
As described above, according to the conventional technique described in Patent Document 1, crystal grains having a length twice as long as one lateral growth distance can be formed without leaving a gap, Crystal grains extended along different directions can be formed on the same substrate without increasing the element size.
[0031]
[Non-Patent Document 1]
IEEE Electron Dev. Lett. , EDL-7, 276, 1986 (Enoshima et al.)
[Non-Patent Document 2]
J. et al. Appl. Phys. 82,4086
[Non-Patent Document 3]
Appl. Phys. Lett. 69,2864
[Non-Patent Document 4]
IEEE Elctron Device Meeting 2000, San Francesco
[Non-Patent Document 5]
AM-LCD 2000 Digest, p281
[Patent Document 1]
Japanese Patent Application No. 2001-292538
[0032]
[Problems to be solved by the invention]
However, in the prior art disclosed in Patent Document 1, since it is necessary to further stack the reflection film 23 on the antireflection film 22, there is a problem that the process becomes complicated and the cost increases.
[0033]
In the method of Patent Document 1, it is necessary to remove the reflective film 23 laminated on the antireflection film 22 after the first laser light irradiation and before the second laser light irradiation. . For this reason, after taking out the glass substrate 5 from a laser irradiation apparatus and removing the reflective film 23, it is necessary to set the glass substrate 5 from which the reflective film 23 was removed again in a laser irradiation apparatus. Therefore, there is a problem that the process is further complicated, and the production time is correspondingly increased and the cost is further increased.
[0034]
Furthermore, in the method of Patent Document 1, when the first laser beam is irradiated, the reflective film 23 made of metal is melted and flows down onto the bare region a-Si film 4, or the reflective film 23 evaporates. The a-Si film 2 may be contaminated because it is vaporized and adheres to the bare region a-Si film 4. As a result, there is a problem in that characteristics of a thin film transistor (hereinafter referred to as “TFT”) manufactured using such a crystalline semiconductor film is deteriorated or variation in characteristics is increased.
[0035]
The present invention has been made to solve such problems, and a method for producing a crystalline semiconductor film capable of forming a high-performance crystalline semiconductor film at a low cost by a simple process, and production using this method. It is an object of the present invention to provide a crystalline semiconductor film, a method for manufacturing a semiconductor device using the crystalline semiconductor film, and a semiconductor device manufactured using the method.
[0036]
[Means for Solving the Problems]
The method for forming a crystalline semiconductor film according to the present invention is a method for manufacturing a crystalline semiconductor film in which a plurality of stripe-shaped translucent insulating films formed in parallel on a semiconductor film are used to obtain a crystalline semiconductor film from the semiconductor film. The semiconductor film in the cap region covered with the light-transmitting insulating film is completely melted, and the semiconductor film in the bare region not covered with the light-transmitting insulating film is not completely melted. An energy beam irradiation step of irradiating the light-transmitting insulating film and the semiconductor film with the first energy beam, and the cap region semiconductor from the position of the melted region extending from the completely melted cap region semiconductor film to the bare region semiconductor film A crystallizing step for crystal growth into a film, whereby the above object is achieved. Here, complete melting means that the film is completely melted in the thickness direction. Here, even when only the first energy beam is irradiated, it may be partially melted in the width direction of the bare region (from the region boundary to the middle of the bear region).
[0037]
Preferably, the irradiation with the first energy beam in the method for manufacturing a crystalline semiconductor film of the present invention is performed while irradiating the second energy beam to heat the light-transmitting insulating film and the semiconductor film.
[0038]
Further preferably, in the crystallization step in the method for producing a crystalline semiconductor film according to the present invention, the melting region at the center of the bare region semiconductor film spread by heat conduction by irradiation with the second energy beam for heating is preferably used. Crystallization is performed toward the center of the cap region semiconductor film.
[0039]
Further preferably, in the crystallization step in the method for producing a crystalline semiconductor film of the present invention, the molten region of the semiconductor film is expanded by heat conduction to melt the bare region semiconductor film, and then cooled and crystallized. The cap region semiconductor film is crystallized based on the bare region semiconductor film.
[0040]
Further preferably, in the crystallization step in the method for producing a crystalline semiconductor film according to the present invention, from the molten region spread by heat conduction in the bare region semiconductor film adjacent to the cap region semiconductor film, to the center of the cap region semiconductor film. The semiconductor crystal grains are grown in the lateral direction.
[0041]
Further preferably, as a pre-process of the energy beam irradiation step in the method for manufacturing a crystalline semiconductor film of the present invention, a semiconductor film forming step of forming a semiconductor film on an insulating substrate and a predetermined equality on each of the semiconductor films The method further includes a translucent insulating film forming step of forming a plurality of translucent insulating films having a predetermined thickness and thickness with a predetermined interval.
[0042]
Further preferably, as a subsequent step of the crystallization step in the method for manufacturing a crystalline semiconductor film of the present invention, the method further includes a removal step of removing the translucent insulating film from the semiconductor film.
[0043]
Further preferably, in the method for producing a crystalline semiconductor film of the present invention, the second energy beam is CO 2. ₂ Laser light or infrared light.
[0044]
Further preferably, the irradiation of the second energy beam in the method for manufacturing a crystalline semiconductor film of the present invention is started from a time point a predetermined time before the start time of the irradiation of the first energy beam.
[0045]
Further preferably, in the method for manufacturing a crystalline semiconductor film of the present invention, the irradiation with the second energy beam is started from a time point a predetermined time before the start time of the irradiation with the first energy beam, and The process ends at a time after a predetermined time from the end of irradiation with the first energy beam.
[0046]
Further preferably, the film thickness of the light-transmitting insulating film in the method for producing a crystalline semiconductor film of the present invention is such that the reflectance of the light-transmitting insulating film with respect to the first energy beam is that of the bare region semiconductor film. The reflectance is set to be 20% or more lower than the reflectance with respect to the first energy beam.
[0047]
Further preferably, the light-transmitting insulating film in the method for producing a crystalline semiconductor film of the present invention is configured by any one of a silicon oxide film, a silicon nitride film, and a laminated film of a silicon oxide film and a silicon nitride film. Yes.
[0048]
The crystalline semiconductor film of the present invention is manufactured by the method for manufacturing a crystalline semiconductor film according to any one of claims 1 to 12, thereby achieving the above object.
[0049]
A method of manufacturing a semiconductor device according to the present invention includes a transistor manufacturing step of manufacturing a transistor using a crystalline semiconductor thin film manufactured by the method of manufacturing a crystalline semiconductor film according to any one of claims 1 to 5 as a channel region. This achieves the above objective.
Preferably, in the transistor manufacturing step in the method for manufacturing a semiconductor device of the present invention, a source region and a drain region are formed in a direction perpendicular to the long side direction of the striped light-transmitting insulating film.
[0050]
Further preferably, in the transistor manufacturing step in the method for manufacturing a semiconductor device of the present invention, the channel region is formed so as not to include a crystal grain boundary in a direction parallel to a long side direction of the stripe-shaped light-transmitting insulating film. To do.
[0051]
Further preferably, in the translucent insulating film forming step in the method of manufacturing a semiconductor device of the present invention, a plurality of first translucent insulating films each having a predetermined thickness equal to each other in the first region on the semiconductor film. Are formed in stripes at regular intervals, and in the second region on the semiconductor film, a plurality of predetermined film thicknesses that are equal to each other along the direction intersecting the first light-transmissive insulating film. The second light-transmitting insulating films are formed in stripes at regular intervals.
[0052]
Further preferably, in the transistor manufacturing step in the method of manufacturing a semiconductor device of the present invention, in the first region, a source region and a drain region are formed in a direction perpendicular to a long side direction of the first light-transmissive insulating film, In the second region, a source region and a drain region are formed in a direction perpendicular to the long side direction of the second light-transmissive insulating film.
[0053]
Further preferably, in the transistor manufacturing step in the method for manufacturing a semiconductor device of the present invention, the first region includes a channel so as not to include a crystal grain boundary in a direction parallel to a long side direction of the first translucent insulating film. A region is formed, and a channel region is formed in the second region so as not to include a crystal grain boundary in a direction parallel to the long side direction of the second light-transmissive insulating film.
[0054]
The semiconductor device of the present invention is manufactured by the method for manufacturing a semiconductor device according to any one of claims 14 to 19, and thereby the above-described object is achieved.
[0055]
The operation of the present invention will be described below with the above configuration.
[0056]
In the method for producing a crystalline semiconductor film according to the present invention, a semiconductor film is formed on an insulating substrate, a stripe-shaped light-transmitting insulating film is formed thereon, and the light-transmitting property is obtained by the second energy beam. While preheating the insulating film and the semiconductor film, the semiconductor film in the cap region covered with the light-transmitting insulating film is completely melted by irradiating the semiconductor film with the first energy beam from the light-transmitting insulating film side. Based on the crystallized bare region semiconductor film, the molten region of the semiconductor film is expanded by conduction to melt the bare region semiconductor film not covered by the light-transmitting insulating film, and then cooled (natural cooling). A crystalline semiconductor film is obtained by crystallizing the cap region semiconductor film.
[0057]
The light-transmitting insulating film is composed of a silicon oxide film, a silicon nitride film, a stacked film of a silicon oxide film and a silicon nitride film, and the film thickness is the reflectance of the light-transmitting insulating film with respect to the first energy beam. Is set to be 20% or more lower than the reflectance of the bare region semiconductor film.
[0058]
This translucent insulating film functions as an antireflection film, and when the first energy beam such as KrF laser light is irradiated, the cap region semiconductor film is completely melted than the energy at which the bare region semiconductor film is completely melted. The energy that is used is smaller. As a result, when the first energy beam is irradiated, the bare region semiconductor film is not completely melted, and the cap region semiconductor film is completely melted.
[0059]
In the crystallization process, the cap region semiconductor film covered with the light-transmitting insulating film having a large heat capacity has a lower temperature drop than the bare region semiconductor film, so that heat is generated in the bare region semiconductor film adjacent to the cap region semiconductor film. Semiconductor crystal grains are laterally grown from the melted region spread by conduction toward the center of the cap region semiconductor film. Therefore, by patterning the light-transmitting insulating film on the semiconductor film into a desired shape, the direction in which the crystal grains extend can be determined, and the semiconductor films in which the crystal grain extending directions are orthogonal to each other can be formed on the same substrate. Can be mixed.
[0060]
From a time point a predetermined time before the irradiation start time point of the first energy beam, CO ₂ By irradiating infrared light such as laser light, the semiconductor film is heated before the first energy beam irradiation, so that the width of the melted region extending in the bare region by heat conduction can be increased. In addition, the cap region semiconductor film covered with the light-transmitting insulating film having a large heat capacity has a lower temperature drop than the bare region semiconductor film, and thus the lateral growth distance can be increased.
[0061]
By continuing to irradiate the second energy beam until a time point after the end of the first energy beam irradiation, the cooling rate of the molten region is reduced, so that the lateral growth distance can be increased. .
[0062]
A source region and a drain region are formed in a direction perpendicular to the long-side direction of the light-transmitting insulating film and parallel to the substrate surface, and includes a crystal grain boundary in a direction parallel to the long-side direction of the light-transmitting insulating film By forming the channel region so as not to exist, for example, a thin film transistor as a transistor with high carrier mobility can be manufactured.
[0063]
Further, in the translucent insulating film forming step, the first region and the second region are formed by forming the translucent insulating film in the first region and the second region along a direction intersecting each other (or a direction orthogonal to each other). The direction in which the crystal grains extend between the regions can be directions intersecting each other (or directions orthogonal to each other).
[0064]
In this case, in each of the first region and the second region, a source region and a drain region are formed in a direction perpendicular to the long-side direction of the light-transmitting insulating film, and a direction parallel to the long-side direction of the light-transmitting insulating film is formed. By forming the channel region so as not to include a crystal grain boundary, for example, a thin film transistor with high carrier mobility can be manufactured in each of the first region and the second region.
[0065]
In the present invention, unlike the prior art described in Patent Document 1, the process can be simplified because no reflection film is provided on the antireflection film. Further, since there is no need to remove the reflective film after the first laser beam irradiation and before the second laser beam irradiation, the process can be simplified. Furthermore, since the reflective film does not melt or evaporate / vaporize and adhere to the bare region semiconductor film during laser light irradiation, it is possible to suppress deterioration in characteristics and variation in characteristics of the thin film transistor as a transistor.
[0066]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments 1 to 3 of the crystalline semiconductor thin film and the semiconductor device using the same according to the present invention will be described below with reference to the drawings. In the following first to third embodiments, a case where a polycrystalline silicon film is formed as a crystalline semiconductor thin film on a glass substrate, and a case where a thin film transistor is formed as a semiconductor device which forms a channel region using this polycrystalline silicon film. explain.
[0067]
(Embodiment 1)
Hereinafter, the crystalline semiconductor thin film of Embodiment 1 and a method for forming the crystalline semiconductor thin film (a method for manufacturing a crystalline semiconductor thin film) will be described.
[0068]
The crystalline semiconductor film according to the first embodiment includes an a-Si film formed on a glass substrate, and a plurality of light-transmitting insulating films arranged on the a-Si film in a stripe pattern with a certain interval between each film. The cap region a-Si film covered with the light-transmitting insulating film is completely melted while irradiating the second laser light for heating the a-Si film and the light-transmitting insulating film. Is irradiated to the a-Si film from the translucent insulating film side, and the melting region of the a-Si film is expanded by heat conduction to melt the bare region a-Si film not covered by the translucent insulating film. Thereafter, the cap region Si film is crystallized based on the cooled and crystallized bare region Si film, and the light-transmitting insulating film is removed from the a-Si film.
[0069]
First, the semiconductor film forming process will be described.
[0070]
FIG. 1 is a cross-sectional view for explaining a step of forming an amorphous silicon film in the first embodiment of the method for producing a crystalline semiconductor film of the present invention.
[0071]
In FIG. 1, first, a base coat film 6 composed of a silicon oxide film is formed on a glass substrate 5 as an insulating substrate to a thickness of 300 nm by a P-CVD method. The glass substrate 5 is configured by Curing 1737.
[0072]
On the base coat film 6, an a-Si film 2 as a semiconductor film is formed to a thickness of 45 nm by P-CVD.
[0073]
The a-Si film 2 is dehydrogenated by heating the glass substrate 5 on which the a-Si film 2 and the base coat film 6 are formed at 500 ° C. for 1 hour in a nitrogen atmosphere in an electric furnace.
[0074]
Next, the translucent insulating film forming process will be described.
[0075]
FIG. 2 is a cross-sectional view for explaining a step of forming a translucent insulating film in Embodiment 1 in the method for producing a crystalline semiconductor film of the present invention, and FIG. 3 is a perspective view thereof.
[0076]
In FIG. 2, a silicon oxide film as a light-transmitting insulating film 1 is formed on the a-Si film 2 subjected to the dehydrogenation process by a P-CVD method.
[0077]
Thereafter, the silicon oxide film as the light-transmitting insulating film 1 formed on the a-Si film 2 is patterned by etching using BHF110 (buffered hydrofluoric acid), so that a plurality of light-transmitting films having a film width of 15 μm are obtained. The insulating films 1 are formed in stripes with an interval (parallel state) of 3 μm.
[0078]
The a-Si film 2 in the region covered with the light-transmitting insulating film 1 is referred to as a cap region a-Si film 3, and a between the light-transmitting insulating films 1 that are not covered with the light-transmitting insulating film 1. The -Si film 2 will be referred to as a bare region a-Si film 4.
[0079]
FIG. 4 is a graph showing the relationship between the thickness of a silicon oxide film, which is a kind of the translucent insulating film of FIG. The horizontal axis indicates the film thickness of the silicon oxide film 1 formed on the a-Si film 2, and the vertical axis indicates the reflectance of the silicon oxide film as the silicon oxide film 1.
[0080]
As shown in FIG. 4, the reflectivity of the translucent insulating film 1 periodically changes depending on the film thickness. Therefore, when the a-Si film 2 is irradiated with laser light from the translucent insulating film side, The energy of the laser light reaching the cap region a-Si film 3 covered with the light-insulating film 1 varies depending on the film thickness of the light-transmitting insulating film 1, and increases as the reflectance decreases.
[0081]
The thickness of the translucent insulating film 1 formed on the a-Si film 2 is such that the reflectance of the translucent insulating film 1 is 20% or more smaller than the reflectance of the bare region semiconductor film 4. It is preferable to do. For example, when a silicon oxide film is used as the translucent insulating film 1, it can be formed with a thickness of about 115 nm.
[0082]
Next, the energy beam irradiation process will be described.
[0083]
The laser energy (cap region complete melting energy) at which the cap region a-Si film 3 covered with the translucent insulating film 1 made of the silicon oxide film having a thickness of about 115 nm is completely melted is the bare region a-Si. This is smaller than the laser energy at which the film 4 is completely melted (bearing region complete melting energy).
[0084]
Here, CO as the second energy beam ₂ When irradiating KrF laser light having an energy larger than the cap region complete melting energy and smaller than the bare region complete melting energy as the first energy beam while irradiating infrared light with a laser or the like, CO before being irradiated ₂ By heating the a-Si film 2 with laser light, it is possible to increase the width of the melted region that spreads in the bare region by heat conduction, compared to the case of irradiation with KrF laser light alone.
[0085]
FIG. 5 is a cross-sectional view for explaining a step of irradiating laser light in the first embodiment of the method for manufacturing a crystalline semiconductor film of the present invention.
[0086]
As shown in FIG. 5, first, 4.0 J / cm ² CO with a wavelength of 10.6 μm and an energy density of ₂ The second laser beam 9 for heating the translucent insulating film 1 and the a-Si film 2 by the laser is transmitted from the time before the start of the irradiation of the first laser beam 8, for example, 3.84 msec. The Si film 2 is irradiated from the surface on the conductive insulating film 1 side. In this way, while irradiating the second laser light 9, 150 mJ / cm which is smaller than the bare region complete melting energy but larger than the cap region complete melting energy. ² The Si film 2 is irradiated from the translucent insulating film 1 side with the first laser light 8 having the energy density of KrF laser light having a wavelength of 248 nm.
[0087]
The beam size of the first laser light 8 is 0.5 mm × 100 mm, the repetition rate is 80 Hz, and the stage feed speed is 40 mm / second.
[0088]
Next, the crystallization process will be described.
[0089]
In the cooling and crystallization process, CO ₂ The cap region covered with the silicon oxide film (translucent insulating film 1) having a large heat capacity heated by the laser beam has a lower temperature drop than the bare region, and the CO region is stopped even after the KrF laser is stopped. ₂ If the laser beam is continuously irradiated, the cooling rate of the melted Si film decreases. Therefore, the distance of lateral growth toward the center of the cap region becomes longer. According to a preliminary experiment, an energy of 4.0 J / cm is obtained for a sample in which a striped silicon oxide film of about 115 nm is formed on an a-Si film. ² CO with a pulse width of 4.0 msec ₂ While irradiating laser light, energy 150mJ / cm ² , KrF laser light with a pulse width of about 20 nsec ₂ When irradiation was performed 3.84 msec after the start of laser irradiation, the lateral growth distance was about 10 μm, and the width of the molten region spreading to the bare region side was about 2 μm.
[0090]
6 is a perspective view for explaining a crystallization step in the first embodiment of the method for producing a crystalline semiconductor film of the present invention, and FIG. 7 is a plan view of FIG.
[0091]
As shown in FIGS. 5 to 7, when the first laser beam 8 and the second laser beam 9 are irradiated, the cap region Si film 3 is completely melted, and at the same time, the bare region Si film 4 is formed by heat conduction. The melting area spreads to the side. Since the spread of the melted region is about 2 μm under the laser irradiation condition, if the distance between the translucent insulating films 1 is 3 μm, all the bare region Si film 4 is melted.
[0092]
After the irradiation with the first laser beam 8, the cooling of the Si film 2 starts, but the bare region Si4 is compared with the cap region Si3 covered with the translucent insulating film 1 made of a silicon oxide film having a large heat capacity. As a result, the temperature drops faster. In the bare region Si4, since the cooling rate increases as the distance from the cap region increases, crystallization starts from the center of the bare region Si4. The Si film 2 is crystallized by crystal growth in the lateral direction toward the center of the cap region Si film 3 using the crystallized bare region Si4 as a crystal nucleus.
[0093]
The crystal growth distance in the lateral direction is maintained even after the KrF laser is stopped. ₂ By continuing to irradiate the laser beam, it becomes longer than the case of irradiating with the KrF laser beam alone. For example, in addition to the above irradiation conditions, the COr laser beam is stopped ₂ If the laser beam is continuously irradiated for 0.12 msec, the lateral crystal growth distance becomes about 10 μm. In contrast, 150 mJ / cm ² When the KrF laser beam alone is irradiated, the lateral crystal growth distance is about 1 μm. Therefore, if the width of the cap region Si3 is set to 20 μm or less, for example, 15 μm, crystal grains grown toward the center of the cap region Si3 collide with each other at the center of the cap region Si3.
[0094]
Thereafter, the translucent insulating film 1 is removed from the Si film 2 by etching using BHF110.
[0095]
FIG. 8 shows a plan view of the crystalline semiconductor film of the first embodiment formed as described above.
[0096]
FIG. 8 is a plan view schematically showing Embodiment 1 of the crystalline semiconductor film of the present invention. Here, the crystalline state of the crystalline silicon film observed by SEM after the light-transmitting insulating film 1 is removed is shown.
[0097]
The crystal grains constituting the crystalline silicon film are respectively grown laterally from the vicinity of the center of the bare region Si film 4 toward the center of the cap region Si film 3, and collide with each other at the center of the cap region Si film 3. Yes. A crystal grain boundary is formed in the center of the cap region Si film 3 along the longitudinal direction of the cap region Si film 3.
[0098]
As a result, in the crystalline silicon film, crystal grains grown in the lateral direction and having a length approximately twice the crystal growth distance are formed without a gap.
[0099]
A semiconductor device and a manufacturing method thereof will be described using the crystalline silicon film of the first embodiment having the above-described configuration.
[0100]
Using the crystalline silicon film of the first embodiment formed as described above, an n-channel thin film transistor in which a channel region is disposed along the crystal growth direction, and a channel region is disposed along the width direction of the crystal grains. An n-channel thin film transistor is manufactured.
[0101]
In the crystalline silicon film of the first embodiment, the length of the crystal grains in the crystal growth direction is long. For example, when the width of the cap region Si4 is 15 μm and the width of the bare region Si3 is 3 μm, the length of the crystal grains Is about 18 μm. Therefore, by providing the source region and the drain region along the crystal growth direction and arranging the channel region along the crystal growth direction, a crystal generated along the longitudinal direction of the cap region Si film 3 in the channel region A thin film transistor including no grain boundary can be manufactured.
[0102]
In an n-channel thin film transistor in which a channel region is arranged along the width direction of crystal grains, the carrier mobility is 110 cm. ² / Vs. In the n-channel thin film transistor in which the channel region is arranged along the crystal growth direction and does not include the crystal grain boundary generated along the longitudinal direction of the cap region Si film 3 in the channel region, the carrier mobility Is 400cm ² / Vs.
[0103]
The defect rate defined by the variation in the threshold voltage is 0/100, and as a result of measuring the threshold voltage of 100 n-channel thin film transistors in which the channel regions are arranged along the crystal growth direction, no defect occurred. .
[0104]
As described above, the method for forming a crystalline semiconductor film according to the first embodiment includes a semiconductor film forming process for forming the a-Si film 2 on the glass substrate 5 and stripes with a predetermined interval between them. a translucent insulating film forming step for forming a plurality of translucent insulating films 1 disposed on the a-Si film 2, and a second laser beam for heating the translucent insulating film 1 and the a-Si film 2 The first laser beam 8 is irradiated from the translucent insulating film 1 side to the a-Si film 2 so that the cap region a-Si film 3 covered with the translucent insulating film 1 is completely melted while irradiating 9. The a-Si film 2 is expanded by expanding the melting region of the a-Si film 2 by heat conduction and the bare region a-Si film 4 not covered by the translucent insulating film 1 is melted, and then cooled and crystallized. A crystallization step of crystallizing the cap region Si film 3 based on the bare region Si film 4; The translucent insulating film 1 and a removal step of removing from the top a-Si film 2.
[0105]
Only the translucent insulating film 1 needs to be provided on the Si film 2, and the antireflection film 22, the reflective film 23, and the like as in the prior art of Patent Document 1 described above with reference to FIGS. 15 and 16. Is not required to be stacked on the a-Si film 2. Therefore, the process in the method for forming the crystalline semiconductor film can be simplified, and the cost can be reduced.
[0106]
Further, as in the prior art of Patent Document 1, after the first laser light irradiation and before the second laser light irradiation, the reflection film 23 stacked on the antireflection film 22 is removed. In addition, it is not necessary to take out the glass substrate 5 from the laser beam irradiation apparatus, remove the reflection film 23, and set the glass substrate 5 from which the reflection film 23 has been removed to the laser beam irradiation apparatus again. Therefore, the process in the method for forming the crystalline semiconductor film can be further simplified, and the cost can be further reduced.
[0107]
Furthermore, since the thin film transistor can be manufactured using the Si film formed in this manner so that there is no crystal grain boundary perpendicular to the carrier movement direction in the channel region, A high-performance thin film transistor can be manufactured without being hindered by the boundary.
[0108]
In the first embodiment, the example in which the translucent insulating film 1 is formed of a silicon oxide film has been described. However, the present invention is not limited to this. For example, the translucent insulating film 1 may be constituted by a silicon nitride film or a laminated film of a silicon oxide film and a silicon nitride film.
[0109]
(Comparative Example 1)
Hereinafter, the crystalline semiconductor film of Comparative Example 1 and a method for forming the crystalline semiconductor film will be described.
[0110]
The difference between the method for forming the crystalline semiconductor film of Comparative Example 1 and the method for forming the crystalline semiconductor film of Embodiment 1 described above with reference to FIGS. 1 to 8 is that the film thickness of the translucent insulating film 1 is different. And the energy density of the first laser beam 8 is set to 200 mJ / cm for the reason that the reflectance is set to 75 nm, which is a film thickness at which the reflectance is comparable to that of the bare region Si film. ² This is the point. Since the other points are the same as the method for forming the crystalline semiconductor film of the first embodiment, detailed description thereof is omitted.
[0111]
When the crystalline silicon film of Comparative Example 1 formed in this way is observed by SEM, crystal grains are not laterally grown in the cap region Si film 3 and the bare region Si film 4, and the microcrystalline regions are not grown. It was. The reason for this is as follows.
[0112]
In Comparative Example 1, since the reflectances of the cap region Si film 3 and the bare region Si film 4 are approximately the same, the laser light energy absorbed by the translucent insulating film 1 is also approximately the same, and the cap region Si film 3 and The temperature reached by the bare region Si film 4 is about the same. Since a silicon oxide film (translucent insulating film 1) as a translucent insulating film is provided on the cap region Si film 3, the cooling rate of the cap region Si film 3 is higher than that of the bare region Si film 4. Slowly, but not enough temperature gradients to cause lateral growth. As a result, a microcrystalline region is formed.
[0113]
(Comparative Example 2)
Hereinafter, the crystalline semiconductor film of Comparative Example 2 and the manufacturing method thereof will be described.
[0114]
9 and 10 are cross-sectional views for explaining the method for manufacturing the crystalline semiconductor film of Comparative Example 2. FIG.
[0115]
As shown in FIG. 9, first, a base coat film 6 composed of a silicon oxide film is formed on a glass substrate 5 to a thickness of 300 nm by a P-CVD method.
[0116]
An a-Si film 2 is formed on the base coat film 6 to a thickness of 45 nm by P-CVD.
[0117]
The a-Si film 2 is dehydrogenated by heating the glass substrate 5 on which the a-Si film 2 and the base coat film 6 are formed at 500 ° C. for 1 hour in a nitrogen atmosphere in an electric furnace.
[0118]
Thereafter, as shown in FIG. 10, a silicon oxide film is formed to a thickness of 32 nm on the a-Si film 2 by P-CVD.
[0119]
An aluminum film is deposited on the silicon oxide film 22 to a thickness of 300 nm by sputtering. BCl ₃ The reflective film 23 is formed by patterning the aluminum film formed on the silicon oxide film by dry etching using silicon.
[0120]
The antireflection film 22 is formed by patterning the silicon oxide film by etching using the BHF 110 with the reflective film 23 formed by patterning as a mask. In this way, the laminated film of the antireflection film 22 and the reflection film 23 is formed on the a-Si film 2 in a stripe shape having a width (parallel state) of 2 μm with a spacing of 2 μm. .
[0121]
Next, 200 mJ / cm ² The a-Si film 2 is irradiated from the laminated film side of the antireflection film 22 and the reflection film 23 with the first laser light having an energy density of KrF laser light having a wavelength of 248 nm.
[0122]
Thereafter, the reflective film 23 is removed by etching with an SLA etchant using phosphoric acid and acetic acid.
[0123]
160mJ / cm ² The a-Si film 2 is irradiated from the antireflection film 22 side with a second laser beam having an energy density of 2 nm. For both the first laser beam and the second laser beam, the beam size is 0.5 mm × 100 mm, the repetition rate is 80 Hz, and the stage feed speed is 40 mm / second. The antireflection film 22 is removed from the a-Si film 2 by etching using BHF110. The crystalline semiconductor film of Comparative Example 2 formed in this way is shown in FIG.
[0124]
FIG. 11 is a plan view schematically showing the crystalline semiconductor film of Comparative Example 2. FIG. 11 shows the crystalline state of the crystalline silicon film observed by SEM after removing the antireflection film 22.
[0125]
In FIG. 11, the crystal grains constituting the cap region Si film 3 are laterally grown from both ends of the cap region Si film 3 toward the center. The crystal grains constituting the bare region Si film 4 are laterally grown from both ends of the bare region Si film 4 toward the center. However, spot-like spots 24 are formed in some places. This is because when the first laser beam is irradiated, the reflective film 23 made of metal melts and flows down onto the bare region Si film 4, or the reflective film 23 evaporates and vaporizes to cause the bare region Si film. The Si film 2 is contaminated because it adheres to the surface 4.
[0126]
Next, using the crystalline silicon film thus formed, an n-channel thin film transistor in which a channel region is disposed along the width direction and an n-channel thin film transistor in which a channel region is disposed along the crystal growth direction Make it.
[0127]
In an n-channel thin film transistor in which a channel is arranged along the width direction, the carrier mobility is 100 cm. ² / Vs. In the n-channel thin film transistor in which the channel is arranged along the crystal growth direction, the carrier mobility is 295 cm. ² / Vs.
[0128]
However, the variation in threshold voltage is larger than the variation in threshold voltage of the thin film transistor of the first embodiment, and the defect rate defined by the variation in threshold voltage is 13/100. Further, as a result of measuring the threshold voltage of 100 n-channel thin film transistors in which channel regions are arranged along the crystal growth direction, there were 13 defects.
[0129]
(Embodiment 2)
In the second embodiment, a thin film transistor as a semiconductor device in which a crystalline semiconductor film manufactured by the method for manufacturing a crystalline semiconductor film of the first embodiment is configured as a channel region and a manufacturing method thereof will be described.
[0130]
FIG. 12 is a plan view for explaining the second embodiment of the thin film transistor manufacturing method of the present invention, and FIG. 13 is a plan view showing the configuration of the thin film transistor of the second embodiment.
[0131]
First, the base coat film 6 is formed on the glass substrate 5 as in the first embodiment. An a-Si film 2 is formed on the base coat film 6. Next, the a-Si film is dehydrogenated by heating the glass substrate on which the a-Si film and the base coat film are formed in an electric furnace.
[0132]
As shown in FIG. 12, the a-Si film has a first region 10 and a second region 11 each having a substantially rectangular shape provided so as to be adjacent to each other. In the first region 10, a plurality of light-transmissive insulating films 1 are formed in parallel along the left-right direction in FIG. In the second region 11, a certain interval is formed in a stripe shape along the vertical direction in FIG. 12, which is a direction perpendicular to the longitudinal direction of the translucent insulating film 1 formed in the first region 10. A plurality of light-transmitting insulating films 1 are formed in parallel.
[0133]
Thus, the longitudinal direction of the translucent insulating film 1 formed in the first region 10 is orthogonal to the longitudinal direction of the translucent insulating film 1 formed in the second region 11. The direction in which the crystal grains of the cap region Si film and the bare region Si film grow in the first region 10 is the longitudinal direction of the translucent insulating film 1 formed in the first region 10, which is the left-right direction in FIG. The vertical direction is perpendicular to the vertical direction.
[0134]
The direction in which the crystal grains of the cap region Si film and the bare region Si film grow in the second region 11 is the vertical direction of FIG. 12 in the longitudinal direction of the translucent insulating film 1 formed in the second region 11. The horizontal direction is perpendicular to.
[0135]
Accordingly, the crystal grains in the first region 10 are grown along a direction perpendicular to the direction in which the crystal grains in the second region 11 grow.
[0136]
Therefore, as shown in FIG. 13, in the first region 10, the source region 13 and the drain region 14 are provided along the vertical direction in which the crystal grains grow, and the lateral grain boundaries are formed in the channel region. The TFT 12 is formed so as not to be included. In the second region 11, the source region 13 and the drain region 14 are provided along the left-right direction in which crystal grains grow, and the TFT 12 is formed so as not to include the vertical crystal grain boundary in the channel region. . Accordingly, a TFT having a channel region with high carrier mobility can be formed, and a high-performance TFT can be obtained.
[0137]
As described above, according to the embodiment 1.2, the step of forming the semiconductor film 2, the translucent insulating film 1 on the semiconductor film 2, and the reflectivity for the first laser light of the bare region semiconductor film A light-transmitting insulating film forming step of forming a film thickness that is 20% or more lower than the reflectance, and irradiating the second energy beam 8 for heating the light-transmitting insulating film 1 and the semiconductor film 2, An energy beam irradiation step of irradiating the first energy beam 9 with energy larger than the cap region complete melting energy, and cap region crystallization for crystallizing the cap region semiconductor film based on the previously crystallized bare region semiconductor film A process and a removing process of removing the translucent insulating film 2 from the semiconductor film 1. Therefore, the process can be simplified because no reflection film is provided on the antireflection film as in the prior art. Further, since there is no need to remove the reflective film as in the prior art after the first laser beam irradiation and before the second laser beam irradiation, the process can be simplified. Furthermore, since the reflective film does not melt or evaporate / vaporize and adhere to the bare region semiconductor film when irradiated with laser light as in the prior art, it is possible to suppress deterioration in characteristics and variation in characteristics of the thin film transistor. Therefore, a high-performance crystalline semiconductor film can be formed at a low cost with a simple process. Further, using this high-performance crystalline semiconductor film, for example, a thin film transistor can be manufactured with a low defect rate and low cost as a high-performance semiconductor device having a channel region with high carrier mobility.
[0138]
In the first and second embodiments, in the crystallization step, the cap region starts from the central portion of the bare region Si film 4 in which the melting region is expanded by heat conduction while irradiating the heating energy beam (second energy beam). Although it is configured to crystallize toward the central portion of the Si film 3, the melted region spread from the completely melted cap region Si film 3 to the bare or incompletely melted bare region Si film 4. Crystal growth from the position to the cap region Si film 3 may be performed. That is, from the central part of the bare region Si film 4 excluding the boundary part between the bare region Si film 4 and the cap region Si film 3 or from the region up to the central portion (or the region beyond the central portion) of the cap region Si film 3. The effect of the present invention can be obtained by crystallization toward the center position.
[0139]
【The invention's effect】
As described above, according to the present invention, a high-performance crystalline semiconductor film grown in a lateral direction at low cost can be formed without gaps by a crystalline semiconductor film manufacturing method with a simple process. In addition, a high-performance semiconductor device having a channel region with high carrier mobility can be manufactured with a low defect rate and low cost by a method for manufacturing a semiconductor device with a simple process.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view for explaining a step of forming an amorphous silicon film in a first embodiment of a method for producing a crystalline semiconductor film of the present invention.
FIG. 2 is a cross-sectional view for explaining a step of forming a translucent insulating film in the first embodiment of the method for producing a crystalline semiconductor film of the present invention.
FIG. 3 is a perspective view for explaining a translucent insulating film forming step of the first embodiment.
4 is a graph showing the relationship between the thickness of a silicon oxide film, which is a kind of the light-transmitting insulating film in FIG. 2, and its reflectance.
FIG. 5 is a cross-sectional view for explaining a step of irradiating laser light in the first embodiment of the method for manufacturing a crystalline semiconductor film of the present invention.
FIG. 6 is a perspective view for explaining a crystallization step in the first embodiment of the method for producing a crystalline semiconductor film of the present invention.
7 is a plan view of FIG. 6 for explaining a crystallization step. FIG.
FIG. 8 is a plan view schematically showing Embodiment 1 of the crystalline semiconductor film of the present invention.
9 is a cross-sectional view for explaining an a-Si film forming step in the method for producing a crystalline semiconductor film of Comparative Example 2. FIG.
10 is a cross-sectional view for explaining a laminated film forming step of an antireflection film and a reflection film in the method for producing a crystalline semiconductor film of Comparative Example 2. FIG.
11 is a plan view schematically showing a crystalline semiconductor film of Comparative Example 2. FIG.
FIG. 12 is a plan view for explaining Embodiment 2 of the method for producing a thin film transistor of the present invention.
13 is a plan view of the thin film transistor of FIG. 12. FIG.
14A is a cross-sectional view illustrating a conventional method for manufacturing a crystalline semiconductor film, and FIG. 14B is a plan view thereof.
FIG. 15 is a cross-sectional view for explaining another conventional method for manufacturing a crystalline semiconductor film.
FIG. 16 is a cross-sectional view for explaining another conventional method for manufacturing a crystalline semiconductor film.
[Explanation of symbols]
1 Translucent insulating film
2 a-Si film (or Si film)
3 Cap region a-Si film (or cap region Si film)
4 Bare region a-Si film (or bare region Si film)
5 Glass substrate
6 Base coat film
8 First laser beam
9 Second laser beam
10 First region
11 Second region
12 Thin film transistor
13 Source area
14 Drain region
22 Anti-reflective coating
23 Reflective film
24 Spot-like spots

Claims (20)

In a method for manufacturing a crystalline semiconductor film, a crystalline semiconductor film is obtained from the semiconductor film using a plurality of stripe-shaped translucent insulating films formed in parallel on the semiconductor film.
The translucent semiconductor film in the cap region covered with the translucent insulating film is completely melted, and the bare region semiconductor film not covered with the translucent insulating film is not completely melted. An energy beam irradiation step of irradiating the conductive film and the semiconductor film with the first energy beam;
A method for producing a crystalline semiconductor film, comprising: a crystallization step of growing a crystal from the position of the melted region that has spread from the completely melted cap region semiconductor film to the bare region semiconductor film to the cap region semiconductor film. 2. The method for manufacturing a crystalline semiconductor film according to claim 1, wherein the irradiation with the first energy beam is performed while irradiating the second energy beam to heat the light-transmitting insulating film and the semiconductor film. The crystallization step includes crystallizing from a molten region at a central portion of the bare region semiconductor film, which is spread by heat conduction by irradiation with a second energy beam for heating, toward a central portion of the cap region semiconductor film. 3. A method for producing a crystalline semiconductor film according to 1 or 2. In the crystallization step, the molten region of the semiconductor film is expanded by heat conduction to melt the bare region semiconductor film, and then cooled, and the cap region semiconductor film is crystallized based on the crystallized bare region semiconductor film. The method for producing a crystalline semiconductor film according to claim 1. 2. In the crystallization step, semiconductor crystal grains are grown in a lateral direction from a molten region spread by heat conduction in a bare region semiconductor film adjacent to the cap region semiconductor film toward a center of the cap region semiconductor film. Or 4. A method for producing a crystalline semiconductor film according to 4. As a pre-process of the energy beam irradiation process,
A semiconductor film forming step of forming a semiconductor film on the insulating substrate;
2. A translucent insulating film forming step of forming a plurality of translucent insulating films each having a predetermined thickness and a predetermined width on the semiconductor film with a predetermined interval, respectively. 6. A method for producing a crystalline semiconductor film according to any one of 4 and 5. The method for manufacturing a crystalline semiconductor film according to claim 1, further comprising a removing step of removing the translucent insulating film from the semiconductor film as a subsequent step of the crystallization step. The method for manufacturing a crystalline semiconductor film according to claim 2, wherein the second energy beam is infrared light or CO ₂ laser light. 9. The method for manufacturing a crystalline semiconductor film according to claim 2, wherein the irradiation of the second energy beam is started from a time point a predetermined time before the irradiation start time of the first energy beam. The irradiation of the second energy beam is started from a time point that is a predetermined time before the irradiation start time point of the first energy beam, and after a predetermined time period after the irradiation end time point of the first energy beam. The method for producing a crystalline semiconductor film according to claim 2, wherein the method is completed at the time. The film thickness of the light transmitting insulating film is such that the reflectance of the light transmitting insulating film with respect to the first energy beam is 20% or more lower than the reflectance of the bare region semiconductor film with respect to the first energy beam. The method for producing a crystalline semiconductor film according to claim 1, which is set to be 7. The crystalline semiconductor film according to claim 1, wherein the translucent insulating film is formed of any one of a silicon oxide film, a silicon nitride film, and a laminated film of a silicon oxide film and a silicon nitride film. Method. A crystalline semiconductor film manufactured by the method for manufacturing a crystalline semiconductor film according to claim 1. A method for manufacturing a semiconductor device, comprising: a transistor manufacturing step for manufacturing a transistor using the crystalline semiconductor thin film manufactured by the method for manufacturing a crystalline semiconductor film according to claim 1 as a channel region. The method for manufacturing a semiconductor device according to claim 14, wherein in the transistor manufacturing step, a source region and a drain region are formed in a direction perpendicular to a long side direction of the stripe-shaped translucent insulating film. 16. The manufacturing of a semiconductor device according to claim 14, wherein in the transistor manufacturing step, the channel region is formed so as not to include a crystal grain boundary in a direction parallel to a long side direction of the stripe-shaped translucent insulating film. Method. In the light-transmitting insulating film forming step, a plurality of first light-transmitting insulating films each having a predetermined film thickness equal to each other are formed in a stripe shape in the first region on the semiconductor film, with a predetermined interval between them. In addition, a plurality of second light-transmitting insulating films each having a predetermined thickness equal to each other along the direction intersecting the first light-transmitting insulating film are fixed to the second region on the semiconductor film. The method of manufacturing a semiconductor device according to claim 14, wherein the semiconductor device is formed in a stripe shape with an interval. In the transistor manufacturing process, a source region and a drain region are formed in a direction perpendicular to a long side direction of the first light-transmissive insulating film in the first region, and the second light-transmissive insulating film is formed in the second region. The method for manufacturing a semiconductor device according to claim 17, wherein the source region and the drain region are formed in a direction perpendicular to the long side direction. In the transistor manufacturing step, a channel region is formed in the first region so as not to include a crystal grain boundary in a direction parallel to a long side direction of the first light-transmitting insulating film, and the second region includes the second region. 19. The method for manufacturing a semiconductor device according to claim 17, wherein the channel region is formed so as not to include a crystal grain boundary in a direction parallel to the long side direction of the light-transmitting insulating film. A semiconductor device manufactured by the method for manufacturing a semiconductor device according to claim 14.

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