JP2006216600A - Method of manufacturing thin-film semiconductor and thin-film transistor manufactured by this manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a manufacturing method of a thin-film semiconductor by which a flat gate insulating film can be formed, voltage resistance is improved, an oxidization speed of a silicon is accelerated and process time is shortened in an oxidation process by adding a process in which the surface of a polycrystalline silicon is irradiated with a gas cluster ion beam to flatten the unevenness of the surface and crystals on a polycrystalline silicon surface layer portion are destroyed to allow the surface layer portion to be amorphous silicon, prior to an oxidation process of oxidizing the polycrystalline silicon surface to form a gate insulating film. <P>SOLUTION: This manufacturing method has a process of forming an amorphous silicon layer 2 on an insulating substrate 1, a process of annealing the amorphous silicon layer 2 to form a polycrystalline silicon layer 3, a process of irradiating the surface of a polycrystalline silicon layer 3 with a gas cluster ion beam, and a process of applying an atmosphere including oxygen to the surface of the polycrystalline silicon layer 3 irradiated with the gas cluster ion beam to form an oxidized silicon layer 5. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method of manufacturing a thin film semiconductor applied to a top gate type thin film transistor in which a semiconductor layer made of polycrystalline silicon is formed on an insulating substrate.

  In general, in a polycrystalline silicon thin film transistor using polycrystalline silicon as a semiconductor layer formed on an insulating substrate, a silicon oxide layer serving as a gate insulating film is formed on the polycrystalline silicon by a chemical vapor deposition (CVD) method. Further, a manufacturing method has been adopted in which a gate electrode is formed thereon to form a MOS-FET. In this case, there is a problem that crystal defects and impurities existing on the surface of the polycrystalline silicon are localized at the MOS interface, and there are disadvantages such as low mobility and high threshold voltage as transistor characteristics.

  Therefore, instead of using the CVD method, in an atmosphere mainly containing oxygen or an atmosphere mainly containing water vapor (pressure 1 to 50 atm, temperature 300 ° C. to 700 ° C., typically 25 atm, 600 ° C.) Thus, there has been proposed a method of forming a gate insulating film or a silicon oxide layer serving as a part thereof by oxidizing the surface of the polycrystalline silicon layer (see, for example, Patent Document 1). According to this conventional method, a MOS interface is formed in polycrystalline silicon, and the surface of the polycrystalline silicon itself can be less affected by crystal defects and impurities, so that it is possible to manufacture a MOS-FET with good characteristics. . In this conventional method, polycrystalline silicon is formed using means such as furnace annealing (solid phase growth method) and laser annealing (melt recrystallization method).

JP-A-11-67758

In the above-described conventional method, a MOS interface is formed in polycrystalline silicon to form a MOS interface with few crystal defects and impurities, thereby obtaining a thin film transistor with good characteristics.
However, the surface of the polycrystalline silicon disclosed in the conventional method, particularly the polycrystalline silicon formed by laser annealing, has a concavo-convex shape having protrusions at the grain boundary portion. In this state, if oxidation is performed from the surface of the polycrystalline silicon, oxygen is impregnated to a certain depth from the surface of the polycrystalline silicon, and the thickness of the silicon oxide layer is formed to be substantially constant. In this case, undulation corresponding to the surface roughness of the initial polycrystalline silicon occurs. In addition, since the polycrystalline silicon layer is crystallized and the generation rate of the silicon oxide layer is slow, a long-time treatment is required in a high-temperature, high-pressure steam atmosphere, resulting in problems such as low productivity.

  In order to solve the above-mentioned problems, the present invention irradiates a gas cluster ion beam to the surface of the polycrystalline silicon prior to the oxidation step of oxidizing the surface of the polycrystalline silicon to form a gate insulating film, thereby forming the surface irregularities. By flattening and adding a step of breaking the crystal of the polycrystalline silicon surface layer into amorphous silicon, a flat gate insulating film can be formed in the oxidation step, the withstand voltage can be improved, and silicon An object of the present invention is to obtain a thin film semiconductor manufacturing method and a thin film transistor in which the oxidation rate is increased and the process time is shortened.

  A method of manufacturing a thin film semiconductor according to the present invention includes a step of forming an amorphous silicon layer on an insulating substrate, a step of annealing the amorphous silicon layer to form a polycrystalline silicon layer, and a gas on the surface of the polycrystalline silicon layer. A step of irradiating a cluster ion beam, and a step of forming a silicon oxide layer by applying an atmosphere containing oxygen to the surface of the polycrystalline silicon layer irradiated with the gas cluster ion beam.

  According to the present invention, since the surface of the polycrystalline silicon layer is irradiated with the gas cluster ion beam before the oxidation step, the surface unevenness of the polycrystalline silicon layer is flattened and the surface layer portion of the polycrystalline silicon layer is Crystals are destroyed and turned into amorphous silicon. Therefore, in the oxidation step, a flat gate insulating film is formed, the withstand voltage is improved, the silicon oxidation rate is increased, and the process time is shortened.

Embodiment 1 FIG.
FIG. 1 is a process cross-sectional view illustrating a method of manufacturing a thin film semiconductor according to Embodiment 1 of the present invention.

Here, the manufacturing method of the thin film semiconductor according to the first embodiment will be described with reference to FIG.
First, as shown in FIG. 1A, an amorphous silicon layer 2 is formed on an insulating substrate 1 by a CVD (Chemical Vapor Deposition) method using SiH ₄ or Si ₂ H ₆ source gas. Then, as shown in FIG. 1B, the amorphous silicon layer 2 is irradiated and heated with excimer laser light (typically, XeCl laser having a wavelength of 308 nm) to melt the amorphous silicon. The silicon is cooled and solidified to form the polycrystalline silicon layer 3. The melted and recrystallized polycrystalline silicon layer 3 is a collection of crystal grains, and the surface thereof has an uneven shape having protrusions at crystal grain boundary portions between the crystal grains.
Next, as shown in FIG. 1C, the surface of the polycrystalline silicon layer 3 is irradiated with a gas cluster ion beam mainly composed of argon. As a result, the gas cluster ion beam selectively etches the silicon protrusions formed at the grain boundary portions of the polycrystalline silicon to flatten the surface irregularities of the polycrystalline silicon layer 3. Further, argon clusters or argon atoms enter the surface layer of the polycrystalline silicon layer 3 to destroy the crystallinity, and the surface layer of the polycrystalline silicon layer 3 is turned into amorphous silicon. Thereby, an amorphous silicon layer 4 is formed on the surface layer of the polycrystalline silicon layer 3.
Next, as shown in FIG. 1D, the polycrystalline silicon layer 3 is patterned into an island shape. Then, as shown in FIG. 1 (e), the silicon surface that has been planarized and whose surface layer has been amorphized is oxidized efficiently in an oxidizing atmosphere, preferably saturated water vapor, and oxidized as a gate insulating film. A silicon layer 5 is formed. Further, a gate electrode 6 is formed in the silicon oxide layer 5 as shown in FIG. The basic part of the MOS is configured through these steps.
Although not shown, the top gate thin film transistor shown in FIG. 1G is formed by forming the source and drain portions by impurity implantation, forming the protective film 7, and forming the extraction electrodes 8 and 9 from the source and drain portions. Is formed.

In the method of manufacturing a thin film semiconductor according to the first embodiment, a step of irradiating the surface of the polycrystalline silicon layer 3 with a gas cluster ion beam containing argon gas as a main component prior to the oxidation step of the polycrystalline silicon layer 3 is performed. We are carrying out. In this step, the silicon protrusion formed on the grain boundary portion of the polycrystalline silicon where the gas cluster ion beam is melted and recrystallized is selectively etched to flatten the surface irregularities of the polycrystalline silicon layer 3. Further, argon clusters or argon atoms enter the surface layer of the polycrystalline silicon layer 3 to destroy the crystallinity, the surface layer of the polycrystalline silicon layer 3 is converted to amorphous silicon, and the amorphous silicon layer 4 is formed on the surface layer of the polycrystalline silicon layer 3. Is formed.
Therefore, in the oxidation step of the polycrystalline silicon layer 3, the silicon oxide layer 5 as the gate insulating film formed on the surface layer of the polycrystalline silicon layer 3 is flat without undulation corresponding to the surface state of the polycrystalline silicon layer 3. The surface resistance of the gate insulating film is improved, leading to high performance of the thin film semiconductor. Further, the surface layer of the polycrystalline silicon layer 3 is an amorphous silicon layer 4 having a faster oxidation rate than the polycrystalline silicon layer 3, and the time for the oxidation process is shortened. Therefore, a high-performance thin film semiconductor can be manufactured with high productivity.

As the insulating substrate 1, a glass substrate, a quartz substrate, a sapphire substrate, or the like is used, but a glass substrate is preferable in that it is inexpensive and can reduce device costs. Alternatively, a substrate in which a base insulating film is formed on the insulating substrate 1 may be used. As the base insulating film, a single film such as a silicon oxide layer, a silicon nitride layer, an aluminum oxide film, a tantalum oxide film, or a stack of two or more kinds can be used. In the present invention, the insulating substrate on which the amorphous silicon layer is formed is not limited to a single insulating substrate, but includes an insulating substrate having a base insulating film formed thereon.
Further, a method for forming the amorphous silicon layer 2 on the insulating substrate 1 is not particularly limited, but a plasma CVD method, a low pressure CVD method, a sputtering method, or the like can be used.
In addition, the amorphous silicon layer 2 is irradiated with excimer laser light to form the polycrystalline silicon layer 3, but the laser light is not limited to excimer laser light. For example, Nd: YAG laser light is used. Also good.
The polycrystalline silicon layer 3 is formed by laser annealing the amorphous silicon layer 2, but the annealing method is not limited to laser annealing, and examples thereof include electron beam annealing, lamp annealing, and furnace annealing. May be used.

Embodiment 2. FIG.
In the first embodiment, in the step shown in FIG. 1C, the surface of the polycrystalline silicon layer 3 is irradiated with a gas cluster ion beam mainly composed of argon gas. 2, the surface of the polycrystalline silicon layer 3 is irradiated with a gas cluster ion beam mainly composed of oxygen gas. Other configurations are the same as those in the first embodiment.

  In the second embodiment, the cluster ion beam mainly composed of oxygen gas selectively etches the silicon protrusion formed at the grain boundary portion of the polycrystalline silicon, and as in the first embodiment, The surface irregularities of the polycrystalline silicon layer 3 are flattened. Further, oxygen clusters or oxygen atoms penetrate into the surface layer of the polycrystalline silicon layer 3 to destroy the crystallinity, and the surface layer of the polycrystalline silicon layer 3 is turned into amorphous silicon. An amorphous silicon layer 4 is formed on the surface layer of the layer 3. Therefore, also in the second embodiment, the same effect as in the first embodiment can be obtained.

  In the second embodiment, since a cluster ion beam containing oxygen gas as a main component is used, the element implanted into the portion where the polycrystalline silicon crystal is broken to form the amorphous silicon layer 4 is oxygen. It becomes. Therefore, the silicon oxidation rate in the oxidation process of the polycrystalline silicon layer 3 is further increased as compared with the first embodiment in which the element implanted into the amorphous silicon layer 4 is argon. The time is shortened. Therefore, a high-performance thin film semiconductor can be manufactured with higher productivity.

Embodiment 3 FIG.
In the third embodiment, polycrystallization is performed by irradiating the amorphous silicon layer 2 with YAG2ω laser light instead of excimer laser light.

FIG. 2 is an explanatory diagram of a laser annealing step in the method for manufacturing a thin film semiconductor according to Embodiment 3 of the present invention, and FIG. 3 is a structure of a target to which laser annealing is performed in the method for manufacturing a thin film semiconductor according to Embodiment 3 of the present invention. It is a schematic cross section which shows.
In FIG. 2, the laser beam irradiation apparatus adjusts the second harmonic oscillator 91 of the Nd: YAG laser and the laser beam (wavelength: 532 nm) 92 emitted from the second harmonic oscillator 91 to a predetermined intensity. A variable attenuator 93 and a beam shaping optical system 94 for converting the laser light 92 adjusted to a predetermined intensity by the variable attenuator 93 into a linear beam are provided. The target 95 is installed on the moving stage 96.
Here, as shown in FIG. 3, the target 95 is formed by forming a silicon oxide layer with a thickness of 200 nm as a base insulating film 102 on a glass substrate 103 as an insulating substrate by CVD, and further using a low pressure CVD (Low Pressure). An amorphous silicon layer (amorphous silicon layer) 101 having a thickness of 70 nm is formed on the base insulating film 102 by chemical vapor deposition.

Next, the laser annealing process according to the third embodiment will be described.
First, the laser beam 92 is emitted from the second harmonic oscillator 91, adjusted to a predetermined intensity by the variable attenuator 93, and then enters the beam shaping optical system 94. The laser beam 92 is converted into a linear beam profile by the beam shaping optical system 94, and then irradiated to the target 95 installed on the moving stage 96, and laser annealing (heat treatment) of the amorphous silicon layer 101 is performed. .
At this time, the laser beam is irradiated while moving the moving stage 96 in a direction perpendicular to the line of the linear beam. If the distance that the moving stage 96 moves between each pulse laser beam irradiation is longer than the width of the linear beam, the number of times of laser pulse irradiation to the same location is one, but if the distance is shorter than the beam width, As shown in FIG. 4, the same spot is irradiated with the laser beam a plurality of times, and the entire surface of the amorphous silicon layer 101 can be crystallized.

Next, melting of the amorphous silicon layer 101 by the linear beam profile and laser beam irradiation will be described with reference to FIG. FIG. 5 is a conceptual diagram showing a molten state of an amorphous silicon layer by irradiating a laser beam in the method of manufacturing a thin film semiconductor according to the third embodiment. FIG. 5 (a) shows a linear beam profile. 5 (b) shows the molten state of the amorphous silicon layer.
The linear beam 110 converted by the beam shaping optical system 94 is condensed and irradiated onto the amorphous silicon layer 101 by the condenser lens 941 at the output portion of the beam shaping optical system 94. As shown by a dotted line A in FIG. 5A, the beam profile of the linear beam 110 collected on the amorphous silicon layer 101 is a top flat shape having a uniform profile in the longitudinal direction, The profile has a Gaussian distribution, for example.
When the heat treatment method using the second harmonic of the Nd: YAG laser based on this linear beam profile is used, the second harmonic absorption coefficient for amorphous silicon is small, so that the film is heated almost uniformly in the film thickness direction, and laser irradiation is performed. As shown by B in FIG. 5A, the lateral temperature distribution in the amorphous silicon layer 101 generated by is formed only in the width direction of the linear beam 110. Therefore, as shown in FIG. 5B, the entire amorphous silicon layer 101 is melted in the depth direction. That is, in the amorphous silicon layer 101, a melted portion 111 is formed in which the melted portion extending in the entire depth direction is linearly distributed. Therefore, since the temperature distribution is small in the depth direction and the longitudinal direction of the linear beam 110, the crystal growth is one-dimensional lateral growth in the width direction of the linear beam 110, and the crystal grain size is as large as several μm. Is formed.

Here, since the profile in the width direction of the linear beam 110 is a Gaussian type, the energy density gradient applied to the target 95 varies depending on the position in the width direction in addition to the energy of the laser. When the energy density gradient becomes 3 mJ / cm ² / μm or more by observing the shape of the crystal grains 111, one-dimensional lateral growth occurs greatly in that portion, and the length L1 of the laterally grown crystal as shown in FIG. A crystal row of a polycrystalline silicon layer is formed that is at least twice the width L2 perpendicular to the growth direction and is aligned with the width direction of the linear beam 110 that is the crystal growth direction, that is, the movement (scanning) direction of the movement stage 96. It was confirmed that

  The surface of the polycrystalline silicon layer formed by such crystal growth is irradiated with a gas cluster ion beam mainly composed of argon gas, and then the polycrystalline silicon layer is patterned into an island shape, and a gate is formed on the polycrystalline silicon layer. A silicon oxide layer as an insulating film was formed. Then, a thin film transistor is manufactured using the thin film semiconductor manufactured as described above, and its electrical characteristics are measured. The result is shown in FIG. 7A shows the mobility of the thin film transistor, and FIG. 7B shows the threshold voltage of the thin film transistor. FIG. 7 also shows the characteristics in the third embodiment and the characteristics when annealed with an excimer laser beam (corresponding to the first embodiment). Here, as a method of forming a silicon oxide layer as a gate insulating film, a method of oxidizing the surface of a polycrystalline silicon layer in a saturated water vapor atmosphere at a pressure of 20 atm and a temperature of 600 ° C. (hereinafter referred to as HPA), low pressure CVD ( LPCVD) and a combination of HPA and low pressure CVD were used to change the thickness of the silicon oxide layer to be formed to produce a thin film transistor.

From FIG. 7B, in this Embodiment 3, when the surface of the polycrystalline silicon is oxidized in a saturated water vapor atmosphere to form a gate insulating film (denoted HPA), the CVD method is used instead of HPA. It can be seen that the threshold voltage is lowered by deviating from the simple film thickness dependence obtained in the case of the formed silicon oxide layer.
Further, from FIG. 7A, in the case of the laser annealing and the oxidation process according to the third embodiment, the mobility is lowered even when the polycrystalline silicon is oxidized as compared with the case of the excimer laser annealing and the oxidation process. Thus, it was found that a thin film transistor with high mobility was realized.

  The reason is estimated as follows. This is performed by laser heat treatment with a linear beam profile using an excimer laser (typically an XeCl laser with a wavelength of 308 nm), but this is based on a concept fundamentally different from the heat treatment with a laser beam with a wavelength of 532 nm. Is. In other words, the heat treatment with the laser beam having a wavelength of 532 nm is uniformly absorbed in the film thickness direction due to the small absorption coefficient in the amorphous silicon as described above, and is re-executed in the lateral direction which is the in-plane direction of the film in the recrystallization process. Crystal growth occurs. On the other hand, in the case of excimer laser, the absorption coefficient of amorphous silicon is very high, light absorption occurs only on the film surface, the film surface is hot, and the lower part of the film is cold. Growth with respect to. For this reason, in the case of the excimer laser, it is considered that a difference in crystallinity is produced in which the crystallinity is good from the bottom to the surface in the film thickness direction. In other words, it is important to form a polycrystalline silicon layer so that the crystallinity does not change in the thickness direction in terms of high mobility and low threshold voltage in the thin film transistor.

As described above, according to the third embodiment, the laser beam 92 having a wavelength of 532 nm is formed into the linear beam 110 having a steep intensity distribution in which the energy density gradient in the width direction is 3 mJ / cm ² / μm or more. Since the laser annealing is performed by irradiating the silicon layer 101, it is possible to grow a crystal in the direction parallel to the glass substrate 103 (insulating substrate) and form a polycrystalline silicon layer whose crystallinity does not change in the thickness direction. Therefore, even if the surface of the polycrystalline silicon is irradiated with a gas cluster ion beam to make the surface layer amorphous, and further oxidized to form a silicon oxide layer as a gate insulating film, the polycrystalline silicon crystal at the interface of the silicon oxide layer Therefore, a high performance top-gate thin film transistor with high mobility and low threshold voltage can be realized.

In addition, if the surface of the polycrystalline silicon layer is oxidized in a saturated water vapor atmosphere to form a silicon oxide layer as a gate insulating film, a clean MOS interface can be formed on the silicon surface. The threshold voltage can be lowered as compared with the case where a silicon oxide layer is formed.
In addition, if the surface of the polycrystalline silicon layer is oxidized in a saturated water vapor atmosphere to form a silicon oxide layer, and further a silicon oxide layer is formed by low-pressure CVD, a silicon oxide layer having a film thickness necessary for a gate insulating film is formed. It can be formed with high productivity in a short time.

  Note that after forming the silicon oxide layer by oxidizing the surface of the polycrystalline silicon layer in a saturated water vapor atmosphere, the method of forming the silicon oxide layer as a thick film of the gate insulating film is limited to the low pressure CVD method. Instead, a plasma CVD method or a PVD (Physical Vapor Deposition) method such as sputtering may be used.

In addition, in order to form a polycrystalline silicon layer, amorphous silicon is formed by CVD, and a catalytic metal (for example, nickel) is in contact with this, followed by thermal annealing at 640 ° C. for about 4 hours to crystallize the substrate in parallel. Then, a thermal oxide film is formed on the polycrystalline silicon surface at a high temperature of 800 ° C. to 1100 ° C. in an oxidizing atmosphere, nickel is gettered, the thermal oxide film containing nickel is removed, and then patterned. A method of forming a thermal oxide film again to form a gate insulating film is proposed, for example, in Japanese Patent Laid-Open No. 9-312403. In this conventional method, a crystal is grown in a direction parallel to the substrate, and then the surface of the polycrystalline silicon is oxidized to form a silicon oxide layer. Therefore, the crystallinity is not much changed in the thickness direction of the polycrystalline silicon. It is thought that there is not. That is, even if polycrystalline silicon is oxidized by forming silicon oxide, it is considered that the crystallinity of the remaining silicon layer is good as in the surface portion. However, in order to grow a crystal in a direction parallel to the substrate, nickel must be contained in silicon, a nickel removal step is necessary, the process is complicated, and a high temperature of about 1000 ° C. is required. There was a bug.
On the other hand, in the third embodiment, the short axis shape of the laser beam having a high permeability to silicon and a beam shape having a steep spatial intensity distribution is melted and recrystallized by laser annealing, thereby obtaining silicon. A polycrystalline silcon film having a crystal growth in a direction parallel to the substrate is formed instead of the film thickness direction. Therefore, according to the third embodiment, nickel in the above-described conventional method is not required to be included in the silicon and the nickel removing step is not required, and a polycrystalline silicon film grown in a direction parallel to the substrate can be obtained by a simple process. Can be formed.

Embodiment 4 FIG.
In the fourth embodiment, a third harmonic oscillator of Nd: YAG laser is used instead of the second harmonic oscillator of Nd: YAG laser.
Other configurations are the same as those in the third embodiment.

The wavelength of the laser beam emitted from the third harmonic oscillator of this Nd: YAG laser is 355 nm. In the fourth embodiment, as in the third embodiment (wavelength of 532 nm), the linear beam grows in the one-dimensional lateral direction in the width direction, and a crystal grain having a large crystal grain size of about several μm is formed. It was done.
The surface of the polycrystalline silicon layer is irradiated with a gas cluster ion beam containing argon gas as a main component, and then the polycrystalline silicon layer is patterned into an island shape. The surface of the crystalline silicon layer was oxidized to form a silicon oxide layer. As a result of fabricating a thin film transistor using this silicon oxide layer as a gate insulating film, a high performance thin film transistor similar to the case of a wavelength of 532 nm was obtained.

Embodiment 5. FIG.
In the fifth embodiment, a titanium sapphire laser oscillator is used instead of the second harmonic oscillator of the Nd: YAG laser.
Other configurations are the same as those in the third embodiment.

This titanium sapphire laser oscillation device is variable in wavelength and can emit laser light of 700 nm to 800 nm. At any wavelength of this oscillation device, one-dimensional lateral growth in the width direction of the linear beam occurred, and a large crystal grain having a crystal grain size of about several μm was formed.
The surface of the polycrystalline silicon layer is irradiated with a gas cluster ion beam containing argon gas as a main component, and then the polycrystalline silicon layer is patterned into an island shape. The surface of the crystalline silicon layer was oxidized to form a silicon oxide layer. As a result of fabricating a thin film transistor using this silicon oxide layer as a gate insulating film, a high performance thin film transistor similar to the case of a wavelength of 532 nm was obtained.

As described above, from the third to fifth embodiments, in the step of forming the polycrystalline silicon layer, the laser beam generated by the pulse laser light source having a wavelength of 350 nm or more and 800 nm or less is 3 mJ / cm ² / width in the width direction. By forming a linear beam with an energy density gradient of μm or more and irradiating the amorphous silicon layer formed on the insulating substrate to melt and recrystallize the amorphous silicon layer, it is not the thickness direction of silicon. A polycrystalline silicon layer crystal-grown in a direction parallel to the substrate can be formed, and a polycrystalline silicon portion having good crystallinity is used as a semiconductor layer even if the surface of the polycrystalline silicon layer is planarized, amorphized, or oxidized. High-performance thin-film semiconductors using a high-voltage gate insulating film and a polycrystalline silicon semiconductor layer with good crystallinity The body can be realized with good productivity.

It is process sectional drawing explaining the manufacturing method of the thin film semiconductor demonstrated concerning Embodiment 1 of this invention. It is explanatory drawing of the laser annealing process in the manufacturing method of the thin film semiconductor which concerns on Embodiment 3 of this invention. It is a schematic cross section which shows the structure of the target which performs laser annealing in the manufacturing method of the thin film semiconductor which concerns on Embodiment 3 of this invention. It is a figure explaining the irradiation state of the laser beam in the laser annealing process in the manufacturing method of the thin film semiconductor which concerns on Embodiment 3 of this invention. It is a conceptual diagram which shows the molten state of an amorphous silicon layer by irradiating the laser beam in the manufacturing method of the thin film semiconductor which concerns on this Embodiment 3. FIG. It is a figure explaining the crystal row | line | column state of the polycrystalline silicon layer in the laser annealing process in the manufacturing method of the thin film semiconductor which concerns on Embodiment 3 of this invention. It is a characteristic view of the thin-film transistor using the thin film semiconductor manufactured by the manufacturing method of the thin film semiconductor which concerns on Embodiment 3 of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1,103 Insulating substrate, 2,101 Amorphous silicon layer, 3 Polycrystalline silicon layer, Silicon oxide layer, 91 2nd harmonic oscillator (pulse laser light source), 92 Laser beam (laser beam), 110 Linear beam.

Claims (5)

  In a method of manufacturing a thin film semiconductor using polycrystalline silicon as a semiconductor layer, a step of forming an amorphous silicon layer on an insulating substrate, a step of annealing the amorphous silicon layer to form a polycrystalline silicon layer, and the polycrystalline silicon Irradiating the surface of the layer with a gas cluster ion beam and forming a silicon oxide layer by applying an atmosphere containing oxygen to the surface of the polycrystalline silicon layer irradiated with the gas cluster ion beam. A method for producing a thin film semiconductor.   2. The method of manufacturing a thin film semiconductor according to claim 1, wherein the gas cluster ion beam is a cluster ion beam mainly composed of a gas containing oxygen. In the step of forming the polycrystalline silicon layer, a laser beam generated by a pulse laser light source having a wavelength of 350 nm or more and 800 nm or less is converted into a linear beam having an energy density gradient of 3 mJ / cm ² / μm or more in the width direction. 2. The thin film semiconductor manufacturing method according to claim 1, wherein the amorphous silicon layer formed on the insulating substrate is irradiated and annealed to form the polycrystalline silicon layer. Method.   After the step of forming a silicon oxide layer by applying an atmosphere containing oxygen to the surface of the polycrystalline silicon layer irradiated with the gas cluster ion beam, a silicon oxide layer is formed on the silicon oxide layer to a predetermined thickness. 4. The method of manufacturing a thin film semiconductor according to claim 1, further comprising a step of forming a film.   A thin film transistor manufactured by the manufacturing method according to claim 1.

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