JP2004055906A - Semiconductor device and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor device in which a crystal growth length is elongated by reducing the generation of microcrystals at the center of a laser irradiating region of a semiconductor film formed by utilizing a sequential lateral solidification method so that the semiconductor film is formed of a polycrystalline film having a large grain size in the device having the semiconductor film, and to provide a method for manufacturing the same. <P>SOLUTION: In the semiconductor device in which at least a low thermal conductivity thin film, a high thermal conductivity thin film and a semiconductor film are sequentially laminated and formed on a substrate; the thermal conductivity of the low thermal conductivity thin film is lower than that of the substrate; and the thermal conductivity of the high thermal conductivity thin film is higher than that of the low thermal conductivity thin film. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a semiconductor device and a method for manufacturing the same. More specifically, the present invention relates to a semiconductor device capable of significantly increasing a crystal growth length in a semiconductor film, and a method for manufacturing the same.
[0002]
[Prior art]
In recent years, an active matrix type liquid crystal display (LCD) has attracted attention as a high-quality display device. As a pixel driving element (pixel driving transistor) of the active matrix type LCD, a polycrystalline silicon TFT using a polycrystalline silicon film formed on a transparent insulating substrate for an active channel region is being developed.
[0003]
Polycrystalline silicon TFTs have the following advantages over amorphous silicon TFTs using an amorphous silicon film for the active channel region.
[0004]
First, since the field-effect mobility of the polycrystalline silicon film is larger than that of the amorphous silicon film by two digits or more, sufficient pixel writing can be performed even if the TFT gate width is made small and fine. For this reason, a large aperture ratio can be obtained even when the resolution of the screen is increased and the pixels are made finer, so that a display device with high definition and high luminance can be provided.
[0005]
In addition, since the operation speed of the TFT is increased by two digits or more, not only the pixel portion (display portion) but also a peripheral drive circuit (driver), a memory such as a DRAM and an SRAM, and a processor can be integrally formed on the same substrate. it can. Therefore, it is not necessary to separately mount a driver IC or a drive circuit board on the display device, so that cost can be reduced.
[0006]
This polycrystalline silicon film is obtained, for example, by crystallizing a deposited semiconductor film made of amorphous or microcrystalline silicon with an excimer laser (ELA: Excimer Laser Anneal). The ELA method is performed at a constant speed on a sample having a structure including the insulating substrate 2, an insulating film 7 made of silicon oxide, and a semiconductor film 5 as shown in FIG. In general, the semiconductor film 5 is continuously irradiated with a linear laser 8 having a length of about 200 to 400 mm and a width of about 0.2 to 1.0 mm while scanning. At this time, the semiconductor film in the portion irradiated with the laser does not melt over the entire region in the thickness direction, but melts while leaving a part of the semiconductor film region. For this reason, crystal nuclei are generated throughout the entire interface between the unmelted region and the molten region, and crystals grow toward the outermost layer of the semiconductor film, and crystal grains having a random orientation are formed. It is very small, 100 to 200 nm.
[0007]
Since many unpaired electrons are present at the crystal grain boundaries of the polycrystalline silicon film, they form potential barriers and act as strong carrier scatterers. Therefore, a TFT formed with a polycrystalline silicon film having a smaller number of crystal grain boundaries, that is, a larger crystal grain size, generally has a higher field-effect mobility.
[0008]
However, in the conventional ELA method, as described above, since vertical crystallization occurs in which crystallization occurs at random positions at the interface between the unmelted region and the molten region, it is not possible to obtain a polycrystalline silicon film having a large grain size. It is difficult to obtain a TFT having high field-effect mobility.
[0009]
Therefore, as described in JP-T-2000-505241, by using a laser processing apparatus as shown in FIG. 4, "when forming a laterally extending crystal region in a film of a semiconductor material on a substrate, (A) exposing a first portion of the film using pulsed radiation to induce heat in the semiconductor material to melt the semiconductor material in the first portion over its thickness; Solidifying the semiconductor of the first portion to form at least one semiconductor crystal at a boundary portion of the first portion, and making the first portion a previous portion for a next process; Exposing another portion of the semiconductor that partially overlaps with at least one semiconductor crystal while step-moving in the step-moving direction, and (d) solidifying the molten semiconductor material in the another portion to form a semiconductor crystal. The semiconductor crystal is expanded by growing in the step moving direction, and (e) the combination of steps (c) and (d) is repeated until another part of each step is formed in the next step until a desired crystal region is formed. A so-called continuous lateral crystal growth (SLS) method has been proposed. In the method described in the above publication, a semiconductor film is irradiated with a pulse laser having a fine width, and the semiconductor film is melted and solidified over the entire laser irradiation region in the thickness direction to perform crystallization.
[0010]
FIG. 2B is a schematic view of a needle-like crystal structure formed by one pulse irradiation on the semiconductor device having the above-described conventional structure 1 (FIG. 5). For example, the laser irradiation region is melted by laser irradiation with a fine width of 2 to 10 μm, crystal grows laterally from the interface between the unmelted region and the melted region, that is, in the direction parallel to the substrate, and the fine particles generated in the center of the melted region The crystal collides with the crystal grown from both sides, and the growth ends.
[0011]
The length of a crystal grown by a single pulse irradiation in the SLS method is, for example, about 1 to 1.2 μm when an excimer laser having a wavelength of 308 nm is irradiated at a substrate temperature of 300 ° C., which is much smaller than that of the conventional ELA method. It is known that it grows (text of the 112th meeting of the Society of Applied Physics, Crystal Engineering Subcommittee, pages 19-25). Further, there is a method in which the crystal growth direction is controlled by devising the irradiance distribution (beam profile) by using a phase shift mask in the SLS method or the like to reduce the number of crystal grain boundaries.
[0012]
Also, a method of obtaining large crystal grains by reducing the solidification rate of a semiconductor film after laser irradiation by a conventional ELA method has been devised (Japanese Patent Laid-Open No. 10-150200).
[0013]
According to the method described in Japanese Patent Application Laid-Open No. H10-150200, a heat-resistant polymer film 3 is formed on an insulating substrate 2 as shown in FIG. And a semiconductor film 5 is formed on the insulating film 6 (this structure is hereinafter referred to as a conventional structure 2). The semiconductor film 5 is irradiated with a laser 8 to melt and crystallize the semiconductor film. is there. Since the heat conductivity of the heat-resistant polymer film 3 is smaller than the heat conductivity of quartz glass which is often used as the insulating substrate 2, the semiconductor film 5 melted by laser irradiation due to the heat insulating effect of the heat-resistant polymer film 3. Most of the heat energy is accumulated in the insulating film 6, whereby the solidification rate of the semiconductor film 5 is reduced as compared with the conventional case, and as a result, a semiconductor crystal having large crystal grains can be obtained.
[0014]
However, the crystal that grows laterally from the interface between the unmelted region and the molten region when one pulse irradiation is performed in the SLS method is a microcrystal that grows larger than the ELA method but is generated from the center of the molten region. And its growth was suppressed (FIG. 2 (b)). In FIG. 2B, a microcrystalline region 10 is generated at the center of the slit-shaped region irradiated with the laser, and the crystal growth length 18 of the crystal 9 is equal to the length from the end of the slit to the microcrystalline region. Has become.
[0015]
For the purpose of the SLS method, it is desirable that the crystal growth length 18 by one laser irradiation be as long as possible. However, even if the width of the slit is widened, only the width of the microcrystalline region 10 is widened, and the crystal growth length 18 cannot be made longer than a certain extent.
[0016]
That is, in order to increase the crystal growth length 18, the central microcrystal 10 is not generated as shown in FIG. 2A, or the generation amount is reduced as much as possible. I had to devise a way.
[0017]
[Problems to be solved by the invention]
The present invention has been made in view of the above problems, and an object of the present invention is to provide a semiconductor device having a semiconductor film formed by using an SLS method, wherein the semiconductor device has a laser irradiation region central portion. A semiconductor device comprising a polycrystalline film having a large grain size by reducing the generation of microcrystals and increasing the crystal growth length in the semiconductor device, and a method for manufacturing the same. is there.
[0018]
[Means for Solving the Problems]
That is, the present invention relates to a semiconductor device in which at least a low thermal conductivity thin film, a high thermal conductivity thin film, and a semiconductor film are laminated on a substrate in this order, wherein the low thermal conductivity thin film has a thermal conductivity of the substrate. And a thermal conductivity of the high thermal conductivity thin film is higher than a thermal conductivity of the low thermal conductivity thin film.
[0019]
In the semiconductor device of the present invention, the low thermal conductivity thin film may be a heat-resistant polymer film.
[0020]
Further, in the semiconductor device of the present invention, the high thermal conductivity thin film may be a high thermal conductivity insulating film.
[0021]
Here, the high thermal conductivity thin film can be aluminum nitride.
Further, the high thermal conductivity thin film can be made of silicon nitride.
[0022]
Further, the high thermal conductivity thin film may be a mixture of aluminum nitride and silicon nitride.
[0023]
Further, the high thermal conductivity thin film can be made of magnesium oxide.
Further, the high thermal conductivity thin film can be made of cerium oxide.
[0024]
On the other hand, in the semiconductor device of the present invention, a thin film different from both of these can be formed between the low thermal conductivity thin film and the high thermal conductivity thin film.
[0025]
Further, the high thermal conductivity thin film of the semiconductor device of the present invention preferably has a thickness of 10 to 150 nm.
[0026]
Still further, the present invention relates to a method of manufacturing a semiconductor device in which at least a low thermal conductivity thin film, a high thermal conductivity thin film, and a semiconductor film are laminated on a substrate in this order, the method comprising: Forming a low thermal conductivity thin film having a lower thermal conductivity than forming a high thermal conductivity thin film having a higher thermal conductivity than the low thermal conductivity thin film on the low thermal conductivity thin film Forming a semiconductor film on the high thermal conductivity thin film; and crystallization of the semiconductor film by irradiating the semiconductor film with a slit-like energy beam that emits a pulse. And a method for manufacturing a semiconductor device.
[0027]
Further, the present invention is a method for manufacturing a semiconductor device in which at least a low thermal conductivity thin film, a thin film, a high thermal conductivity thin film, and a semiconductor film are laminated on a substrate in this order. Forming a low thermal conductivity thin film having a thermal conductivity lower than the thermal conductivity, and forming a thin film different from both the low thermal conductivity thin film and the high thermal conductivity thin film on the low thermal conductivity thin film, Forming a high thermal conductivity thin film having a higher thermal conductivity than the low thermal conductivity thin film on the thin film; forming a semiconductor film on the high thermal conductivity thin film; Crystallizing the semiconductor film by irradiating a pulse-like slit-shaped energy beam to the semiconductor film.
[0028]
Here, the reason why the present invention adopts each of the above-described configurations to make the crystal growth length 18 long as shown in FIG. 2A will be described below.
[0029]
Generally, crystallization by cooling occurs when the temperature of an object falls below its melting point. At that time, if there is a crystal around the crystal as a seed for crystal growth and time required for crystal growth, the crystal is crystallized using the crystal as a seed to grow. Conversely, if there is no seed crystal or if the cooling rate is high and there is no time required for crystal growth, the crystals will be microcrystals.
[0030]
Therefore, in order to crystallize the crystal growth length 18 to a long state as shown in FIG. 2 (a), the crystallization starts from the end of the slit, and the crystal growth proceeds sequentially from the end to the center, and the center ends at the end. It needs to be crystallized. To this end, the slit must first be cooled below the melting point, and then gradually cooled down from the melting point toward the center so that the central part is finally below the melting point.
[0031]
On the other hand, in the conventional SLS method, as shown in FIG. 2B, a microcrystalline region 10 exists at the center, and crystal growth stops there. It is considered that this is because the temperature of the central portion was lower than the melting point before the crystal 9 grew toward the center or almost simultaneously with the crystal growth, and the crystal was crystallized in that portion. In other words, before the crystal tip 19 falls below the melting point, or almost simultaneously with this, the center part falls below the melting point earlier.
[0032]
Therefore, in order to grow the crystal so as to increase the crystal growth length 18 as shown in FIG. 2 (a), the temperature at the end of the slit is quickly lowered by quickly discharging waste heat from the end of the slit. It is necessary to lower the melting point sequentially from the end toward the center.
[0033]
The above configurations of the present invention make it possible to control such waste heat conditions. More specifically, a high thermal conductivity thin film is arranged as a base film of a semiconductor film (for example, an amorphous silicon film). One technical feature is that the heat of the film is quickly wasted through the high thermal conductivity thin film.
[0034]
Further, in the present invention, the high thermal conductivity thin film has an appropriate thickness, and a low thermal conductivity thin film made of a material having low thermal conductivity such as a heat-resistant polymer film is disposed below the high thermal conductivity thin film. The heat is prevented from escaping from the conductive thin film toward the substrate, which is also a technical feature of the present invention.
[0035]
In the present invention, by adopting such a configuration, heat is mainly discharged from the side of the high thermal conductivity thin film (that is, in a direction perpendicular to the direction from the high thermal conductivity thin film toward the substrate). Thus, the cooling rate at the center of the slit was successfully reduced.
[0036]
That is, in the semiconductor device of the present invention, when the semiconductor film is crystallized, the end of the slit first falls below the melting point, and from there the melting point goes down to the center, and the central part falls below the melting point. 2A, the crystal growth length 18 of the semiconductor film can be significantly increased.
[0037]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described below.
[0038]
As shown in FIG. 1, the semiconductor device of the present invention forms a low thermal conductivity thin film 3 on a substrate 2, forms a high thermal conductivity thin film 4 on the low thermal conductivity thin film 3, and forms a semiconductor on the high thermal conductivity thin film 4. It has a configuration in which a film 5 is formed, and is characterized in that the semiconductor film 5 is crystallized by a laser 8 by an SLS method.
[0039]
<Thin film lamination method>
Hereinafter, a method of sequentially forming the plurality of thin films on the substrate 2 will be described.
[0040]
First, a low thermal conductivity thin film 3 is formed on a substrate 2. Here, the substrate 2 is preferably insulative, and a glass substrate or a quartz substrate can be used. However, it is preferable to use a glass substrate because it is inexpensive and a large-area substrate can be easily manufactured. is there.
[0041]
Further, the low thermal conductivity thin film 3 can be stacked by a coating method, plasma enhanced chemical vapor deposition (PECVD), or the like so that the film thickness becomes 100 nm to 500 nm. The low thermal conductivity thin film 3 is not particularly limited as long as it has a thermal conductivity of 1.0 (W / mK) or less, preferably 0.3 (W / mK) or less, but is usually a heat-resistant polymer film. Is preferred. Here, the heat-resistant polymer film refers to a polymer film that does not deteriorate due to heat applied when crystallizing the semiconductor film 5 described below, and a polymer film having a heat resistance of 300 ° C. or higher, preferably 400 ° C. or higher is used. preferable. For example, ethyl (C ₂ H ₅ ) Group, propyl (C ₃ H ₇ ) Group, butyl (C ₄ H ₉ ) Group, vinyl (C ₂ H ₃ ) Group, phenyl (C ₆ H ₅ ) Group, CF ₃ It is preferable to use an organic substituent-containing silicon oxide having high heat resistance and low thermal conductivity, which contains any of the groups. It is preferable that such a low thermal conductivity thin film 3 has a porous structure because the thermal conductivity can be further reduced.
[0042]
Next, the high thermal conductivity thin film 4 is formed on the low thermal conductivity thin film 3. The high thermal conductivity thin film 4 is laminated by vapor deposition, ion plating, sputtering, or the like so that the film thickness is desirably 10 to 150 nm. When the film thickness is less than 10 nm, a sufficient heat conduction effect may not be obtained. On the other hand, when the film thickness exceeds 150 nm, the crystal growth of the semiconductor film 5 may be hindered. The high thermal conductivity thin film 4 is not particularly limited as long as it has a higher thermal conductivity than that of the low thermal conductivity thin film 3 described above, but is usually 10 (W / mK) or more, preferably 20 (W / mK) or more. / MK) or more. Further, the high thermal conductivity thin film 4 preferably has such thermal conductivity and exhibits insulating properties. Therefore, it is particularly preferable to use a high thermal conductivity insulating film. As such a high thermal conductivity insulating film, for example, aluminum nitride, silicon nitride, a mixture of aluminum nitride and silicon nitride, magnesium oxide, cerium oxide, or the like is preferably used.
[0043]
Next, the semiconductor film 5 is formed on the high thermal conductivity thin film 4. The semiconductor film 5 is stacked by plasma enhanced chemical vapor deposition (PECVD), vapor deposition, sputtering, or the like so as to have a thickness of 10 nm to 100 nm. The semiconductor film 5 is not particularly limited as long as it is a conventionally known film exhibiting semiconductor characteristics. However, it is preferable to use an amorphous silicon film in which various characteristics are significantly improved by increasing the crystal growth length. However, the semiconductor film 5 is not limited to an amorphous material such as amorphous silicon, and may be a crystalline semiconductor film such as microcrystal or polycrystal before being crystallized by laser irradiation.
[0044]
In the present invention, a thin film 6 different from either of these can be formed between the low thermal conductivity thin film 3 and the high thermal conductivity thin film 4 if desired. The thin film 6 is laminated by plasma enhanced chemical vapor deposition (PECVD), vapor deposition, sputtering, or the like so that the film thickness becomes 10 nm to 100 nm. As the thin film 6, a material having an insulating property is preferable, and a single film made of silicon oxide, silicon nitride, silicon oxynitride, or the like, or a stacked film thereof can be used.
[0045]
<Semiconductor film crystallization method>
Next, the semiconductor film 5 is crystallized by irradiating the semiconductor film 5 with a slit-like energy beam that emits a pulse from the semiconductor film 5 side. As the slit-shaped energy beam for pulse emission, a short pulse laser having a fine width of 2 to 10 μm is preferable, and the irradiation can be usually performed at room temperature. In the following embodiment, an excimer laser having a wavelength of 308 nm (XeCl) and a pulse width of 30 ns is used as a short pulse laser. Can be used.
[0046]
FIG. 4 is a conceptual diagram of an apparatus for crystallizing the semiconductor film 5, and includes a laser oscillator 11, a variable attenuator 12, a field lens 13, a mask 14, an imaging lens 15, a sample stage 16, and some mirrors. Contains. Further, these are controlled by the controller 17. By using this laser processing apparatus, a radiation pulse can be supplied to the semiconductor device 1 on the stage 16.
[0047]
As described above, the semiconductor device of the present invention, that is, the semiconductor device in which the crystal growth length of the semiconductor film is significantly increased can be manufactured. Note that the crystal growth length 18 according to the present invention refers to the length of a crystal that grows in the lateral direction in the semiconductor film 5 as shown in FIG. Means the length up to the tip 19 of the crystal at which the crystal has stopped.
[0048]
<Action>
In the present invention, the crystal growth in the semiconductor film 5 becomes very large by employing the above-described configuration. The fact that the present invention exerts such excellent effects is closely related to the configuration as described below.
[0049]
That is, the thermal conductivity of the high thermal conductivity thin film 4 of the present invention is very high. For example, in the case of aluminum nitride, the thermal conductivity shows a value of about 35 (W / mK). Since the thermal conductivity of the low thermal conductivity thin film 3 in contact with the high thermal conductivity thin film 4 is extremely high as described above, the thermal energy generated by the laser irradiation is promptly diffused in the high thermal conductivity thin film 4 in the lateral direction. It becomes. Moreover, the thermal conductivity of the low thermal conductivity thin film 3 of the present invention is the thermal conductivity of the substrate 2 in contact with the low thermal conductivity thin film 3 (for example, in the case of a glass substrate, the thermal conductivity is 0.8 (W / mK)). ) And the thermal conductivity of the high thermal conductivity thin film 4 is extremely low, so that the thermal energy diffused into the high thermal conductivity thin film 4 can be suppressed from diffusing toward the substrate.
[0050]
As described above, the present invention has a configuration in which the high thermal conductivity thin film 4 and the low thermal conductivity thin film 3 are laminated so as to be in contact with each other, so that the problems of the conventional structure are further synergistically eliminated. It has an effect. That is, in the conventional structures 1 and 2, the thermal energy generated in the amorphous silicon film 5 by the laser irradiation is not easily diffused not only in the substrate direction but also in the lateral direction. Due to the latent heat released when the melted portion solidifies in, a region where the temperature is locally high occurs near the interface between the center of the melted region and the solidified region, while heat energy is generated in the center of the melted region. There is a problem that almost no thermal gradient is formed due to difficulty in diffusion in the lateral direction. Therefore, in these conventional structures, in the cooling process after laser irradiation, the regions below the solidification temperature gradually solidify from the interface between the unmelted region and the molten region toward the center of the molten region. Separately, a region where the solidification occurs below the solidification temperature occurs in the center of the melting region. Therefore, in the central part of the melting region, a wide range of the melting region is almost simultaneously lower than the solidification temperature, so that the growth of the generated crystal nucleus is inhibited by the crystal nucleus generated separately, and the crystal grain size is very small. This caused a large amount of microcrystals. As a result, in these conventional structures, the crystal that grows laterally from the interface between the unmelted region and the melted region when one pulse irradiation is performed grows by the microcrystal generated in the center of the melted region. However, the present invention has an effect of eliminating this problem, because growth was not so large.
[0051]
In short, in the semiconductor device 1 of the present invention, the low thermal conductivity thin film 3 is formed on the substrate 2, the high thermal conductivity thin film 4 is formed on the low thermal conductivity thin film 3, and the high thermal conductivity thin film 4 is formed on the high thermal conductivity thin film 4. Because of the structure in which the semiconductor film 5 is formed, the heat energy generated in the semiconductor film 5 by the irradiation of the laser 8 reaches the high thermal conductivity thin film 4 and then diffuses toward the substrate due to the heat insulating effect of the low thermal conductivity thin film 3. In addition, the high thermal conductivity thin film 4 diffuses in the high thermal conductivity thin film 4 in the lateral direction due to the high thermal conductivity effect.
[0052]
In the present invention, due to such a synergistic effect of the low thermal conductivity thin film 3 and the high thermal conductivity thin film 4, the semiconductor film 5 in contact with the high thermal conductivity thin film 4 in the cooling process after laser irradiation has a molten portion solidified. Since the latent heat released at the time of melting is diffused in the horizontal direction, there is no region where the temperature rises locally near the interface between the central part of the melting region and the solidification region, and the region from the central part of the melting region to the unmelted region The temperature gradient gradually decreases over the interface with the melting region. Therefore, it is possible to suppress the generation of microcrystals in the central portion of the molten region when one pulse irradiation is performed. Therefore, crystals that grow laterally from the interface between the unmelted region and the melted region during the solidification process of the melted region are prevented from growing by microcrystals that occurred in the conventional structures 1 and 2 in the center of the melted region. Never be. As a result, the crystal that grows laterally from the interface between the unmelted region and the melted region becomes very large, and thus the crystal that grows after one pulse irradiation becomes large. Thus, a polycrystalline silicon film having a large grain size can be efficiently obtained. That is, for example, when a laser having a slit width of 4 μm is irradiated, when the conventional structures 1 and 2 are grown by the SLS method, the crystal growth length is at most about 1 to 1.2 μm. By employing the structure of the present invention, the crystal growth length can be made 2 μm or more.
[0053]
Hereinafter, the present invention will be described in more detail with reference to specific embodiments, but the present invention is not limited thereto.
[0054]
<Embodiment 1>
Embodiment 1 of the present invention will be described in detail below with reference to FIGS.
[0055]
The first embodiment is characterized in that an aluminum nitride film 4 which is a high thermal conductivity insulating film is used as the high thermal conductivity thin film 4, and the heat resistant polymer film 3 is formed on the glass substrate 2 as the low thermal conductivity thin film 3. Are laminated, the high thermal conductivity thin film 4 is laminated on the low thermal conductivity thin film 3, and the amorphous silicon film 5 is laminated as the semiconductor film 5 on the high thermal conductivity thin film 4 to form the semiconductor device 1 ( FIG. 1).
[0056]
After irradiating the laser once to the amorphous silicon film 5 as the semiconductor film 5, SECO etching was performed and observed by SEM. FIG. 2A schematically shows the result of the SEM observation. As apparent from FIG. 2A, the crystal growth length 18 of silicon in the semiconductor film 5 is different from that of the conventional structure 1 (FIG. 2B) and that of the conventional structure 2 (FIG. 2C). It can be seen that the crystal grains have grown very long, and the crystal grains have grown large. The crystal growth length 18 is about 2 μm when a laser having a slit width of, for example, 4 μm is irradiated, and collides at the center of laser irradiation to complete the growth.
[0057]
The thermal conductivity of the aluminum nitride film 4 shows a value of about 35 (W / mK), and the thermal conductivity of the heat-resistant polymer film 3 which is the low thermal conductivity thin film 3 in contact with the aluminum nitride film 4 (about 0.3 (W / mK)). W / mK)). Therefore, after the thermal energy generated by the laser irradiation reaches the aluminum nitride film 4, the heat energy does not diffuse in the substrate direction due to the heat insulating effect of the heat-resistant polymer film 3, but does not diffuse toward the substrate due to the high heat conduction effect of the aluminum nitride film 4. It diffuses in the aluminum film 4 in the lateral direction. Therefore, in the cooling process after the laser irradiation, the amorphous silicon film 5 in contact with the aluminum nitride film 4 has a temperature gradient that gradually decreases from the center of the melted region to the interface between the unmelted region and the melted region. The generation of microcrystals in the central part of the molten region when pulse irradiation is performed twice can be suppressed. For this reason, in the solidification process of the molten region, the crystal that grows laterally from the interface between the unmelted region and the molten region is suppressed from growing by microcrystals that occurred in the conventional structure at the center of the molten region. Nothing. As a result, crystals that grow laterally from the interface between the unmelted region and the molten region become very large.
[0058]
FIG. 8 shows the measurement results of the crystal growth length 18 when a sample having various thicknesses of the aluminum nitride film 4 was irradiated with a laser having a slit width of 4 μm. In FIG. 8, “○” is entered when the crystal growth length 18 is as large as 2 μm or more. As is clear from FIG. 8, when the thickness of the aluminum nitride film 4 is 10 to 150 nm, large crystal growth occurs.
[0059]
As described above, according to the first embodiment of the present invention, the thermal energy generated by irradiation of laser 8 is promoted in the lateral direction, so that a polycrystalline silicon film (semiconductor) having a larger grain size is utilized by using the SLS method. A membrane 5) can be obtained.
[0060]
By performing an appropriate treatment on the film formed in this manner, a transistor can be formed, and the film can be used as a display element of a liquid crystal panel or the like.
[0061]
In this case, according to the present invention, since the crystal grains are much larger than in the conventional case, the mobility of carriers flowing through the channel of the transistor is high, and a high-performance device can be obtained.
[0062]
<Embodiment 2>
Embodiment 2 of the present invention will be described below in detail with reference to FIGS.
[0063]
The second embodiment is characterized in that a silicon nitride film 4 that is a high thermal conductivity insulating film is used as the high thermal conductivity thin film 4, and the heat resistant polymer film 3 is formed on the glass substrate 2 as the low thermal conductivity thin film 3. Are laminated, the high thermal conductivity thin film 4 is laminated on the low thermal conductivity thin film 3, and the amorphous silicon film 5 is laminated as the semiconductor film 5 on the high thermal conductivity thin film 4 to form the semiconductor device 1 ( FIG. 1).
[0064]
After irradiating the laser once to the amorphous silicon film 5 as the semiconductor film 5, SECO etching was performed and observed by SEM. FIG. 2A schematically shows the result of the SEM observation. As apparent from FIG. 2A, the crystal growth length 18 of silicon in the semiconductor film 5 is different from that of the conventional structure 1 (FIG. 2B) and that of the conventional structure 2 (FIG. 2C). It can be seen that the crystal grains have grown very long, and the crystal grains have grown large. The crystal growth length 18 is about 2 μm when a laser having a slit width of, for example, 4 μm is irradiated, and collides at the center of laser irradiation to complete the growth.
[0065]
The thermal conductivity of the silicon nitride film 4 shows a numerical value of about 10 (W / mK), and the thermal conductivity of the heat-resistant polymer film 3 which is the low thermal conductivity thin film 3 in contact with the silicon nitride film 4 (about 0.3 (W / mK)). W / mK)). Therefore, after the thermal energy generated by the laser irradiation reaches the silicon nitride film 4, it does not diffuse in the substrate direction due to the heat insulating effect of the heat-resistant polymer film 3, but does not diffuse toward the substrate due to the high heat conduction effect of the silicon nitride film 4. It diffuses in the silicon film 4 in the lateral direction. Therefore, in the cooling process after the laser irradiation, the amorphous silicon film 5 in contact with the silicon nitride film 4 has a temperature gradient that gradually decreases from the center of the molten region to the interface between the unmelted region and the molten region. The generation of microcrystals at the center of the melted region when pulse irradiation is performed twice can be suppressed. For this reason, in the solidification process of the molten region, the crystal that grows laterally from the interface between the unmelted region and the molten region is suppressed from growing by microcrystals that occurred in the conventional structure at the center of the molten region. Nothing. As a result, crystals that grow laterally from the interface between the unmelted region and the molten region become very large.
[0066]
FIG. 8 shows the measurement results of the crystal growth length 18 when a sample having various thicknesses of the silicon nitride film 4 was irradiated with a laser having a slit width of 4 μm. In FIG. 8, “○” is entered when the crystal growth length 18 is as large as 2 μm or more. As is clear from FIG. 8, when the thickness of the silicon nitride film 4 is 10 to 150 nm, large crystal growth occurs.
[0067]
Although silicon nitride has a lower thermal conductivity than aluminum nitride, its constituent element is silicon and its compatibility with amorphous silicon to be laminated is good, and both silicon nitride and amorphous silicon can be formed by CVD in a process, or the same. For example, simplification can be achieved by forming silicon nitride by reactive sputtering using a silicon target and forming amorphous silicon by ordinary sputtering.
[0068]
As described above, according to the second embodiment of the present invention, the diffusion of the thermal energy generated by the irradiation of the laser beam 8 in the lateral direction is promoted, so that the polycrystalline silicon film (semiconductor) having a larger grain size is formed by utilizing the SLS method. A membrane 5) can be obtained.
[0069]
By performing an appropriate treatment on the film formed in this manner, a transistor can be formed, and the film can be used as a display element of a liquid crystal panel or the like.
[0070]
In this case, according to the present invention, since the crystal grains are much larger than in the conventional case, the mobility of carriers flowing through the channel of the transistor is high, and a high-performance device can be obtained.
[0071]
<Embodiment 3>
Embodiment 3 of the present invention will be described below in detail with reference to FIGS.
[0072]
The third embodiment is characterized in that a film 4 made of a mixture of aluminum nitride and silicon nitride, which is a high thermal conductivity insulating film, is used as the high thermal conductivity thin film 4, and the low thermal conductivity thin film 3 is formed on a glass substrate 2. A heat-resistant polymer film 3 is formed as a laminate, a high thermal conductivity thin film 4 is formed on the low thermal conductivity thin film 3, and an amorphous silicon film 5 is formed as a semiconductor film 5 on the high thermal conductivity thin film 4. By doing so, a semiconductor device 1 (FIG. 1) is obtained.
[0073]
After irradiating the laser once to the amorphous silicon film 5 as the semiconductor film 5, SECO etching was performed and observed by SEM. FIG. 2A schematically shows the result of the SEM observation. As apparent from FIG. 2A, the crystal growth length 18 of silicon in the semiconductor film 5 is different from that of the conventional structure 1 (FIG. 2B) and that of the conventional structure 2 (FIG. 2C). It can be seen that the crystal grains have grown very long, and the crystal grains have grown large. The crystal growth length 18 is about 2 μm when a laser having a slit width of, for example, 4 μm is irradiated, and collides at the center of laser irradiation to complete the growth.
[0074]
The thermal conductivity of the film 4 made of a mixture of aluminum nitride and silicon nitride shows a numerical value of about 20 (W / mK), and the low heat conductivity thin film 3 in contact with the film 4 made of a mixture of aluminum nitride and silicon nitride It is very high compared to the thermal conductivity of the polymer film 3 (about 0.3 (W / mK)). Therefore, the thermal energy generated by the laser irradiation reaches the film 4 made of a mixture of aluminum nitride and silicon nitride, and does not diffuse toward the substrate due to the heat insulating effect of the heat-resistant polymer film 3. Due to the high thermal conductivity of the film 4 made of a mixture of silicon, the film 4 is diffused laterally in the film 4 made of a mixture of aluminum nitride and silicon nitride. Therefore, in the cooling process after laser irradiation, the amorphous silicon film 5 in contact with the film 4 made of a mixture of aluminum nitride and silicon nitride gradually decreases from the center of the molten region to the interface between the unmelted region and the molten region. Because of the temperature gradient, it is possible to suppress the generation of microcrystals in the central part of the molten region when one pulse irradiation is performed. For this reason, in the solidification process of the molten region, the crystal that grows laterally from the interface between the unmelted region and the molten region is suppressed from growing by microcrystals that occurred in the conventional structure at the center of the molten region. Nothing. As a result, crystals that grow laterally from the interface between the unmelted region and the molten region become very large.
[0075]
FIG. 8 shows the measurement results of the crystal growth length 18 when a laser having a slit width of 4 μm was irradiated to samples in which the thickness of the film 4 made of a mixture of aluminum nitride and silicon nitride was variously changed. In FIG. 8, “○” is entered when the crystal growth length 18 is as large as 2 μm or more. As is clear from FIG. 8, when the film 4 made of a mixture of aluminum nitride and silicon nitride has a thickness of 10 to 150 nm, large crystal growth is observed.
[0076]
Since the thermal conductivity of the film 4 made of a mixture of aluminum nitride and silicon nitride can be freely designed according to the composition ratio, it is possible to design the film thickness and configuration of the device corresponding to the laser oscillation device. become.
[0077]
As described above, according to the third embodiment of the present invention, the thermal energy generated by the irradiation of laser 8 is promoted in the lateral direction, so that a polycrystalline silicon film (semiconductor) having a larger grain size is utilized by utilizing the SLS method. A membrane 5) can be obtained.
[0078]
By performing an appropriate treatment on the film formed in this manner, a transistor can be formed, and the film can be used as a display element of a liquid crystal panel or the like.
[0079]
In this case, according to the present invention, since the crystal grains are much larger than in the conventional case, the mobility of carriers flowing through the channel of the transistor is high, and a high-performance device can be obtained.
[0080]
<Embodiment 4>
Embodiment 4 of the present invention will be described below in detail with reference to FIGS.
[0081]
The fourth embodiment is characterized in that a magnesium oxide film 4 which is a high thermal conductivity insulating film is used as the high thermal conductivity thin film 4, and the heat resistant polymer film 3 is formed on the glass substrate 2 as the low thermal conductivity thin film 3. The high thermal conductivity thin film 4 is laminated on the low thermal conductivity thin film 3, and the amorphous silicon film 5 is laminated on the high thermal conductivity thin film 4 as the semiconductor film 5 to form the semiconductor device 1 (FIG. 1).
[0082]
After irradiating the laser once to the amorphous silicon film 5 as the semiconductor film 5, SECO etching was performed and observed by SEM. FIG. 2A schematically shows the result of the SEM observation. As apparent from FIG. 2A, the crystal growth length 18 of silicon in the semiconductor film 5 is different from that of the conventional structure 1 (FIG. 2B) and that of the conventional structure 2 (FIG. 2C). It can be seen that the crystal grains have grown very long, and the crystal grains have grown large. The crystal growth length 18 is about 2 μm when a laser having a slit width of, for example, 4 μm is irradiated, and collides at the center of laser irradiation to complete the growth.
[0083]
The thermal conductivity of the magnesium oxide film 4 shows a value of about 60 (W / mK), and the thermal conductivity of the heat-resistant polymer film 3 which is the low thermal conductivity thin film 3 in contact with the magnesium oxide film 4 (about 0.3 (W / mK)). W / mK)). Therefore, after the thermal energy generated by the laser irradiation reaches the magnesium oxide film 4, the heat energy does not diffuse in the substrate direction due to the heat insulating effect of the heat-resistant polymer film 3, but is oxidized due to the high heat conduction effect of the magnesium oxide film 4. It diffuses in the magnesium film 4 in the lateral direction. Therefore, in the cooling process after the laser irradiation, the amorphous silicon film 5 in contact with the magnesium oxide film 4 has a temperature gradient that gradually decreases from the center of the molten region to the interface between the unmelted region and the molten region. The generation of microcrystals at the center of the melted region when pulse irradiation is performed twice can be suppressed. For this reason, in the solidification process of the molten region, the crystal that grows laterally from the interface between the unmelted region and the molten region is suppressed from growing by microcrystals that occurred in the conventional structure at the center of the molten region. Nothing. As a result, crystals that grow laterally from the interface between the unmelted region and the molten region become very large.
[0084]
FIG. 8 shows a measurement result of the crystal growth length 18 when a laser having a slit width of 4 μm is irradiated on samples in which the thickness of the magnesium oxide film 4 is variously changed. In FIG. 8, “○” is entered when the crystal growth length 18 is as large as 2 μm or more. As is clear from FIG. 8, when the thickness of the magnesium oxide film 4 is 10 to 150 nm, large crystal growth occurs.
[0085]
Magnesium oxide not only has a high thermal conductivity but also has a very high crystal orientation despite being polycrystalline, and can be oriented only in, for example, the (111) direction as shown in FIG. Therefore, when laser irradiation is performed, silicon is crystallized in the same direction under the influence of the orientation of magnesium oxide, which increases the possibility of obtaining a polycrystalline silicon film having excellent crystallinity. Therefore, if the obtained crystallized region is used as a channel, a higher mobility may be obtained.
[0086]
As described above, according to the fourth embodiment of the present invention, the thermal energy generated by irradiation with laser 8 is promoted in the lateral direction, so that a polycrystalline silicon film (semiconductor) having a larger grain size is utilized by utilizing the SLS method. A membrane 5) can be obtained.
[0087]
By performing an appropriate treatment on the film formed in this manner, a transistor can be formed, and the film can be used as a display element of a liquid crystal panel or the like.
[0088]
In this case, according to the present invention, since the crystal grains are much larger than in the conventional case, the mobility of carriers flowing through the channel of the transistor is high, and a high-performance device can be obtained.
[0089]
<Embodiment 5>
Embodiment 5 of the present invention will be described below in detail with reference to FIGS.
[0090]
The fifth embodiment is characterized in that the cerium oxide film 4 which is a high thermal conductivity insulating film is used as the high thermal conductivity thin film 4, and the heat resistant polymer film 3 is formed on the glass substrate 2 as the low thermal conductivity thin film 3. The high thermal conductivity thin film 4 is laminated on the low thermal conductivity thin film 3, and the amorphous silicon film 5 is laminated on the high thermal conductivity thin film 4 as the semiconductor film 5 to form the semiconductor device 1 (FIG. 1).
[0091]
After irradiating the amorphous silicon film 5 as the semiconductor film 5 with a laser once, SECO etching was performed and observed by SEM. FIG. 2A schematically shows the result of the SEM observation. As apparent from FIG. 2A, the crystal growth length 18 of silicon in the semiconductor film 5 is different from that of the conventional structure 1 (FIG. 2B) and that of the conventional structure 2 (FIG. 2C). It can be seen that the crystal grains have grown very long, and the crystal grains have grown large. When a laser having a slit width of, for example, 4 μm is irradiated, the crystal growth length 18 becomes about 2 μm in length and collides at the center of laser irradiation to complete the growth.
[0092]
The thermal conductivity of the cerium oxide film 4 shows a numerical value of about 10 (W / mK), and the thermal conductivity of the heat-resistant polymer film 3 which is the low thermal conductivity thin film 3 in contact with the cerium oxide film 4 (about 0.3 (W / mK)). W / mK)). Therefore, after the thermal energy generated by the laser irradiation reaches the cerium oxide film 4, it does not diffuse toward the substrate due to the heat insulating effect of the heat-resistant polymer film 3, but is oxidized by the high heat conduction effect of the cerium oxide film 4. The cerium film 4 diffuses in the lateral direction. Therefore, in the cooling process after the laser irradiation, the amorphous silicon film 5 in contact with the cerium oxide film 4 has a temperature gradient that gradually decreases from the central portion of the molten region to the interface between the unmelted region and the molten region. The generation of microcrystals at the center of the melted region when pulse irradiation is performed twice can be suppressed. For this reason, in the solidification process of the molten region, the crystal that grows laterally from the interface between the unmelted region and the molten region is suppressed from growing by microcrystals that occurred in the conventional structure at the center of the molten region. Nothing. As a result, crystals that grow laterally from the interface between the unmelted region and the molten region become very large.
[0093]
FIG. 8 shows the measurement results of the crystal growth length 18 when a sample having various thicknesses of the cerium oxide film 4 was irradiated with a laser having a slit width of 4 μm. In FIG. 8, “○” is entered when the crystal growth length 18 is as large as 2 μm or more. As is clear from FIG. 8, when the thickness of the cerium oxide film 4 is 10 to 150 nm, large crystal growth occurs.
[0094]
Cerium oxide has high thermal conductivity and can be oriented only in the same direction as magnesium oxide, and its lattice constant is 5.41５, which is very close to that of silicon 5.43 定 数. Therefore, there is a possibility that it can be grown with good consistency with silicon. Therefore, there is a high possibility that a polycrystalline silicon film having excellent crystallinity can be obtained. Therefore, if the obtained crystallized region is used as a channel, a higher mobility may be obtained.
[0095]
As described above, according to the fifth embodiment of the present invention, the thermal energy generated by the irradiation of laser 8 is promoted in the lateral direction, so that a polycrystalline silicon film (semiconductor) having a larger grain size is utilized by utilizing the SLS method. A membrane 5) can be obtained.
[0096]
By performing an appropriate treatment on the film formed in this manner, a transistor can be formed, and the film can be used as a display element of a liquid crystal panel or the like.
[0097]
In this case, according to the present invention, since the crystal grains are much larger than in the conventional case, the mobility of carriers flowing through the channel of the transistor is high, and a high-performance device can be obtained.
[0098]
<Embodiment 6>
Embodiment 6 of the present invention will be described below in detail with reference to FIGS.
[0099]
In the sixth embodiment, as shown in FIG. 7, a heat-resistant polymer film 3 as a low thermal conductivity thin film 3 is formed on an insulating substrate 2 and an insulating film 6 as a thin film 6 is formed on the heat-resistant polymer film 3. A film 6 is formed by lamination, a high thermal conductivity insulating film 4 which is a high thermal conductivity thin film 4 is formed on the insulating film 6, and an amorphous silicon film 5 which is a semiconductor film 5 is formed by lamination on the high thermal conductivity insulating film 4. After that, the amorphous silicon film 5 is laser-crystallized by the SLS method.
[0100]
Here, the insulating film 6, which is the thin film 6 formed with a thickness of 10 nm to 100 nm on the heat resistant polymer film 3, is different from both the low thermal conductivity thin film 3 and the high thermal conductivity thin film 4. There is no particular limitation as long as it is a single film made of silicon oxide, silicon nitride, silicon oxynitride, or the like, which is usually stacked by plasma enhanced chemical vapor deposition (PECVD), evaporation, or sputtering. A membrane can be used.
[0101]
In order to form the high thermal conductivity insulating film 4 on the insulating film 6, the high thermal conductivity insulating film 4 is laminated by vapor deposition, ion plating, sputtering, or the like so that the thickness of the high thermal conductivity insulating film 4 is desirably 10 to 150 nm. Form.
[0102]
Next, in order to form the amorphous silicon film 5 on the high thermal conductivity insulating film 4, plasma enhanced chemical vapor deposition (PECVD), evaporation, or The layers are formed by sputtering or the like.
[0103]
The amorphous silicon film (semiconductor film) 5 of the semiconductor device formed as described above was irradiated once with the laser by the above-described method, and then subjected to SECO etching and SEM observation. FIG. 2A schematically shows the result of the SEM observation. As apparent from FIG. 2A, the crystal growth length 18 of silicon in the semiconductor film 5 is different from that of the conventional structure 1 (FIG. 2B) and that of the conventional structure 2 (FIG. 2C). It can be seen that the crystal grains have grown very long, and the crystal grains have grown large. The crystal growth length 18 is about 2 μm when a laser having a slit width of, for example, 4 μm is irradiated, and collides at the center of laser irradiation to complete the growth.
[0104]
In the sixth embodiment, since the insulating film 6 is formed on the heat-resistant polymer film 3, damage to the heat-resistant polymer film 3 during device formation is suppressed, and the heat resistance of the heat-resistant polymer film 3 is reduced. The heat resistance can be further improved, and the heat insulating effect of the heat-resistant polymer film 3 increases. As a result, the diffusion of the thermal energy generated by the laser irradiation in the horizontal direction can be further promoted, so that a crystal having a larger grain size can be obtained.
[0105]
As described above, according to the sixth embodiment of the present invention, by promoting the diffusion of the thermal energy generated by the irradiation of the laser beam 8 in the lateral direction, a polycrystalline silicon film (semiconductor) having a larger grain size is utilized by utilizing the SLS method. A membrane 5) can be obtained.
[0106]
By performing an appropriate treatment on the film formed in this manner, a transistor can be formed, and the film can be used as a display element of a liquid crystal panel or the like.
[0107]
In this case, according to the present invention, since the crystal grains are much larger than in the conventional case, the mobility of carriers flowing through the channel of the transistor is high, and a high-performance device can be obtained.
[0108]
<Embodiment 7>
Embodiment 7 of the present invention will be described with reference to FIG.
[0109]
The configuration of the semiconductor device 1 is the same as that of any one of the first to sixth embodiments, and the description is omitted here.
[0110]
FIG. 4 is a conceptual diagram of an apparatus for crystallizing the amorphous silicon film 5, and includes a laser oscillator 11, a variable attenuator 12, a field lens 13, a patterned projection mask 14, an imaging lens 15, and a sample stage. 16 and some mirrors. Further, these are controlled by the controller 17. By using this laser processing apparatus, a radiation pulse can be supplied to the semiconductor device 1 on the stage 16. In this embodiment mode, an excimer laser having a wavelength of 308 nm (XeCl) and a pulse width of 30 ns is used as a laser, but the laser is not limited to the above-described excimer laser.
[0111]
When a laser pulse is sequentially irradiated by this apparatus so as to partially overlap the needle-like crystal formed by the previous laser irradiation, a longer needle-like crystal is grown by taking over the already grown crystal. Then, it is possible to obtain a long crystal having a uniform orientation in the crystal growth direction.
[0112]
Further, according to the procedure of the present embodiment, since the high thermal conductivity thin film 4 is formed over the entire surface of the insulating substrate 2, a step of partially forming the high thermal conductivity thin film 4 is included. The manufacturing process (crystallization process) can be shortened compared to the conventional technology.
[0113]
The embodiments and examples disclosed this time are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.
[0114]
【The invention's effect】
In the semiconductor device 1 of the present invention, a low thermal conductivity thin film (heat resistant polymer film) 3 is formed on a substrate 2, and a high thermal conductivity thin film (high thermal conductivity insulating film) 4 is formed on the low thermal conductivity thin film 3. Since the semiconductor film (amorphous silicon film) 5 has a structure in which the semiconductor film (amorphous silicon film) 5 is formed on the high thermal conductivity thin film 4, heat energy generated in the semiconductor film 5 by the laser irradiation reaches the high thermal conductivity thin film 4. The low thermal conductivity thin film 3 does not diffuse in the direction of the substrate 2 due to the heat insulating effect, but diffuses in the high thermal conductivity thin film 4 in the horizontal direction due to the high thermal conductivity effect of the high thermal conductivity thin film 4. Due to the synergistic effect of the low thermal conductivity thin film 3 and the high thermal conductivity thin film 4, the crystal that grows laterally from the interface between the unmelted region and the melted region has a structure similar to that generated in the conventional structure at the center of the melted region. The growth is not suppressed by the microcrystal. Therefore, the crystal that grows laterally from the interface between the unmelted region and the molten region becomes very large. Therefore, the crystal that grows when one pulse irradiation is performed becomes large, so that a polycrystalline silicon film (semiconductor film 5) having a large grain size can be efficiently obtained by crystallization by the SLS method.
[0115]
By performing an appropriate treatment on the film formed in this manner, a transistor can be formed, and the film can be used as a display element of a liquid crystal panel or the like. In this case, according to the present invention, since the crystal grains are much larger than in the conventional case, the mobility of carriers flowing through the channel of the transistor is high, and a high-performance device can be obtained.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view of a semiconductor device of the present invention.
FIG. 2 is a schematic diagram illustrating a surface crystal state of a semiconductor film of a semiconductor device. (A) shows the semiconductor device of the present invention, (b) shows the semiconductor device of the conventional structure 1, and (c) shows the semiconductor device of the conventional structure 2, respectively.
FIG. 3 is an XRD measurement result illustrating a crystal orientation of magnesium oxide according to a fourth embodiment.
FIG. 4 is a conceptual diagram of a laser processing apparatus for crystallizing a semiconductor film.
FIG. 5 is a schematic sectional view of a semiconductor device having a conventional structure 1.
FIG. 6 is a schematic sectional view of a semiconductor device having a conventional structure 2.
FIG. 7 is a schematic sectional view of a semiconductor device according to a sixth embodiment.
FIG. 8 is a diagram showing the dependence of the crystal growth length upon laser irradiation on the thickness of a high thermal conductivity thin film.
[Explanation of symbols]
Reference Signs List 1 semiconductor device, 2 substrate, 3 low thermal conductivity thin film, 4 high thermal conductivity thin film, 5 semiconductor film, 6 thin film, 7 insulating film, 8 laser, 9 crystal, 10 microcrystalline region, 11 laser oscillator, 12 variable attenuator, 13 field lens, 14 mask, 15 imaging lens, 16 sample stage, 17 controller, 18 crystal growth length, 19 tip of crystal.

Claims (12)

A semiconductor device in which at least a low thermal conductivity thin film, a high thermal conductivity thin film and a semiconductor film are laminated on the substrate in this order,
A semiconductor device, wherein the thermal conductivity of the low thermal conductivity thin film is lower than the thermal conductivity of the substrate, and the thermal conductivity of the high thermal conductivity thin film is higher than the thermal conductivity of the low thermal conductivity thin film. . 2. The semiconductor device according to claim 1, wherein said low thermal conductivity thin film is a heat-resistant polymer film. 3. The semiconductor device according to claim 1, wherein the high thermal conductivity thin film is a high thermal conductivity insulating film. 4. The semiconductor device according to claim 1, wherein said high thermal conductivity thin film is aluminum nitride. 4. The semiconductor device according to claim 1, wherein said high thermal conductivity thin film is silicon nitride. 4. The semiconductor device according to claim 1, wherein said high thermal conductivity thin film is a mixture of aluminum nitride and silicon nitride. 4. The semiconductor device according to claim 1, wherein said high thermal conductivity thin film is magnesium oxide. 4. The semiconductor device according to claim 1, wherein said high thermal conductivity thin film is cerium oxide. 9. The semiconductor device according to claim 1, wherein a thin film different from any of the two is formed between the low thermal conductivity thin film and the high thermal conductivity thin film. 10. The semiconductor device according to claim 1, wherein the high thermal conductivity thin film has a thickness of 10 to 150 nm. What is claimed is: 1. A method for manufacturing a semiconductor device, comprising: forming at least a low thermal conductivity thin film, a high thermal conductivity thin film, and a semiconductor film on a substrate in the above-described order. Forming a low thermal conductivity thin film having a thermal conductivity;
Forming a high thermal conductivity thin film having a higher thermal conductivity on the low thermal conductivity thin film than the thermal conductivity of the low thermal conductivity thin film;
Forming a semiconductor film on the high thermal conductivity thin film;
Crystallizing the semiconductor film by irradiating the semiconductor film with a slit-like energy beam that emits a pulse,
A method for manufacturing a semiconductor device, comprising: A method of manufacturing a semiconductor device in which at least a low thermal conductivity thin film, a thin film, a high thermal conductivity thin film, and a semiconductor film are laminated and formed in this order on a substrate,
Forming a low thermal conductivity thin film having a thermal conductivity lower than the thermal conductivity of the substrate on the substrate;
Forming a thin film different from both the low thermal conductivity thin film and the high thermal conductivity thin film on the low thermal conductivity thin film;
Forming a high thermal conductivity thin film having a higher thermal conductivity than the low thermal conductivity thin film on the thin film;
Forming a semiconductor film on the high thermal conductivity thin film;
Crystallizing the semiconductor film by irradiating the semiconductor film with a slit-like energy beam that emits a pulse,
A method for manufacturing a semiconductor device, comprising:

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