JP2006222211A - Semiconductor device substrate, its manufacturing method, and display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To modify a quality of an amorphous silicon film by uniformly processing a large area without degradation in productivity. <P>SOLUTION: A material 111 to be irradiated is fabricated by forming a semiconductor film made of amorphous silicon on a strip-like substrate. While the material 111 is carried into a microwave irradiator 106 to pass the center or its vicinity of a hollow cylindrical microwave irradiation pipe 109, microwaves are multiple-reflected in the pipe 109. Thus, the uniformed microwaves by the multiple reflection can be successively irradiated in the longitudinal direction of the strip-like material 111. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a semiconductor element substrate manufacturing method capable of modifying a semiconductor, a semiconductor element substrate manufactured by the manufacturing method, and a display device including the semiconductor element substrate.

  In recent years, in the field of liquid crystal display devices such as large flat panel displays, development of a process for a semiconductor thin film that is inexpensive and stable in performance has been desired and has been energetically studied. Conventionally, single crystal silicon, polycrystalline silicon, amorphous silicon, or the like has been used as a silicon-based semiconductor material.

  Single crystal silicon has high electron mobility, and is widely used in the manufacture of semiconductor devices that require high-speed operation such as a CPU (Central Processing Unit) and an LSI (Large Scale Integrated circuit). However, since the temperature when forming a thin film of single crystal silicon is extremely high, it cannot be used for manufacturing a thin film transistor (TFT) substrate of a liquid crystal display device.

Therefore, conventionally, amorphous silicon that can be easily formed on a glass substrate at a low temperature has been widely used for manufacturing a TFT substrate of a liquid crystal display device. However, while the electron mobility of the single crystal silicon is 1500cm ² / V · s, the electron mobility of amorphous silicon is about 0.5cm ² / V · s, the electron mobility of amorphous silicon single Extremely low compared to crystalline silicon. Therefore, with amorphous silicon, it is difficult to achieve high-speed operation of a liquid crystal display drive circuit and the like, and it is difficult to obtain an excellent liquid crystal screen. In addition, amorphous silicon has a problem that the defect density in the film is large, and the defect voltage increases with time due to light and electrical stress, and the threshold voltage Vth fluctuates. There's a problem.

  For this reason, in recent years, polycrystalline silicon has been used to improve the performance of liquid crystal display devices. Conventionally, as a method of forming a polycrystalline silicon thin film, a method of forming a polycrystalline silicon thin film by chemical vapor deposition (CVD) has been used. In this method, the obtained polycrystalline silicon thin film is used. There was a problem of low quality. This is because the crystal grain size obtained by CVD is as small as several tens of nanometers, each crystal grain has a disordered orientation, dangling bonds are formed at the grain boundaries, and defect ranks are formed. It will be said that stability will become low.

  Therefore, at present, a method of obtaining polycrystalline silicon having a low defect density by performing post-processing on an amorphous silicon thin film formed on a glass substrate is mainly used. As this method, a laser annealing method is widely known in which an amorphous silicon thin film is irradiated with a laser beam and melted, and polycrystalline silicon is obtained when the molten silicon is cooled and solidified. However, the laser annealing method is not only expensive due to the high cost of laser light irradiation equipment, but also has a high running cost. In addition, the laser beam is focused to irradiate the amorphous silicon thin film so that a large area can be processed uniformly. There is also a problem that it is difficult to do so, leading to a decrease in productivity.

  In addition, phosphorus (P) or boron (B) is doped into a part of the amorphous silicon thin film so as to be a nucleus of the silicon crystal, and the crystallization by solid phase growth of the silicon crystal is selectively started. A partial doping method for obtaining a crystalline silicon is known. However, since this method grows crystals by heating, it cannot be used for glass substrates having a softening temperature of about 600 ° C.

  On the other hand, it has been reported that when high frequency is applied in the crystallization process of amorphous silicon, the crystallization of amorphous silicon is promoted. For example, when an amorphous silicon thin film is formed on an oxide film provided on a single crystal silicon substrate and heat-treated at 550 ° C. while irradiating microwaves (2.54 G, 450 ± 50 W) on the amorphous silicon thin film, It has been reported that crystallization takes place in 3 hours (see Non-Patent Document 1, for example).

  Further, a method for modifying an amorphous silicon thin film by directly irradiating the amorphous silicon thin film with a microwave from a waveguide while adjusting the irradiation temperature and irradiation time has been proposed (see, for example, Patent Document 1). ). A method for modifying an amorphous silicon thin film by directly irradiating microwaves from the waveguide to the amorphous silicon thin film while adjusting the position of the substrate with an adjusting rod so that the electric field intensity becomes maximum. Has been proposed (see, for example, Patent Document 2). However, these methods have insufficient uniformity in the surface of the amorphous thin film, and the process is a long-time process, so that they cannot cope with mass productivity.

  In addition, a thermal oxide film is formed on a single crystal silicon substrate, an amorphous silicon thin film is formed thereon, a nickel thin film is formed thereon except for the central portion, and a gate insulating film and a gate electrode are formed in the central portion. After forming the film, the amorphous silicon / nickel multilayer film is sandwiched between the electric field application electrodes and subjected to a heat treatment at 500 ° C. while applying a DC electric field. Silicon crystal growth preferentially proceeds in the direction of the DC electric field and simultaneously crystallizes. It has been reported that the speed is accelerated (see Non-Patent Document 2, for example). It has been reported that a thin film transistor manufactured by this method has a lower off-current, an improved on / off ratio, a lower threshold, and is desirable as a semiconductor device (see, for example, Non-Patent Document 3).

  However, it is not possible to obtain polycrystalline silicon excellent in performance from amorphous silicon simply by irradiation with microwaves. This is presumably because the direction of the electric field acting on the amorphous silicon varies and the orientation and shape of the generated crystal grains are not constant, the crystal grain boundaries are disturbed, and dangling bonds are formed. In order to solve these problems, an amorphous silicon thin film is formed on a quartz substrate having an Ag layer on the surface, and heat treatment is performed while applying a high-frequency electric field, so that columnar crystals grown in a direction perpendicular to the quartz substrate surface can be obtained. A method of forming a silicon layer has been proposed (see, for example, Patent Document 3).

  In Patent Document 3, the reason why such a silicon layer is obtained is that the irradiated microwave is reflected between the Ag film as a conductor and the dielectric, and the electric field component is only a component perpendicular to the conductor surface. Therefore, it is described that the silicon crystal generated from the amorphous silicon thin film grows preferentially in the direction perpendicular to the substrate surface and becomes a columnar shape.

  However, in the method of defining the growth direction of the silicon crystal only by the electric field generated by the microwave, the conductor film is essential, and there is a problem in applying to a general semiconductor device.

J.N.Lee et al, J.Appl.Phys., 82 (1997), 2918

S.H.Park et al, Jpn.J.Appl.Phys.No.2A, 38 (1999), L108

S.I.Jun et al, Appl.Phys.Lett., 75 (1999), 2235

US Pat. No. 6,528,361

US Pat. No. 6,133,076

JP 2002-26347 A

  As described above, conventionally, there has been a strong demand for a method for manufacturing a semiconductor element substrate that can uniformly process a large area without causing a decrease in productivity and can modify an amorphous silicon thin film.

  Accordingly, an object of the present invention is to manufacture a semiconductor element substrate capable of uniformly processing a large area and modifying an amorphous silicon thin film without causing a decrease in productivity, and the manufacturing method thereof. A semiconductor element substrate and a display device including the semiconductor element substrate are provided.

In order to solve the above-mentioned problem, the invention according to claim 1 includes a step of forming a semiconductor film on a substrate,
And a step of irradiating the semiconductor film with multiple reflections of microwaves.

  In the first aspect of the present invention, it is preferable to irradiate the semiconductor film subjected to chemical doping and / or electrical doping with microwaves. In addition, the electrical doping is typically performed by applying a voltage to the semiconductor film. The dopant used for chemical doping is preferably a Group 3 or Group 5 element. In addition, it is preferable that the semiconductor film be irradiated with microwaves by passing through the microwave irradiation means having one or two or more connected spaces, and by multiplying the microwaves in this space.

  According to a second aspect of the present invention, in the method of manufacturing a semiconductor thin film according to the first aspect, the method further includes a step of forming an absorption layer that absorbs microwaves in an upper layer and / or a lower layer of the semiconductor film.

  According to a third aspect of the present invention, in the method for manufacturing a semiconductor thin film according to the first aspect, the frequency of the microwave is in the range of 1 GHz to 100 GHz.

  According to a fourth aspect of the present invention, in the method for manufacturing a semiconductor thin film according to the first aspect, the substrate and / or microwave irradiation atmosphere is irradiated with microwaves while being cooled by a cooling mechanism.

  According to a fifth aspect of the present invention, in the method for producing a semiconductor thin film according to the fourth aspect, the microwave irradiation atmosphere is 600 ° C. or lower.

  A sixth aspect of the present invention is the method of manufacturing a semiconductor thin film according to the fourth aspect, wherein the cooling mechanism is water cooling.

  According to a seventh aspect of the present invention, in the method for manufacturing a semiconductor thin film according to the first aspect, the substrate is made of glass or plastic.

  According to an eighth aspect of the present invention, in the method for manufacturing a semiconductor thin film according to the first aspect, the step of irradiating the microwave is performed by a roll-to-roll process.

  The invention according to claim 9 is a semiconductor element substrate manufactured by the manufacturing method according to any one of claims 1 to 8.

  A tenth aspect of the present invention is a display device comprising the semiconductor element substrate according to the ninth aspect.

  As described above, according to the present invention, after the semiconductor film is formed on the substrate, the semiconductor film is irradiated with multiple reflections of the microwave, so that the microwave can be irradiated more uniformly on the semiconductor film. Can do. Therefore, a large area can be processed uniformly without causing a decrease in productivity.

Embodiments of the present invention will be described in the following order.
(1) First Embodiment (1-1) Configuration of Liquid Crystal Display Device According to First Embodiment (1-2) Configuration of Microwave Heating Device according to First Embodiment (1-3) First Implementation (1) Modification of First Embodiment (2) Second Embodiment (2-1) Manufacturing Method of Semiconductor Element Substrate according to Second Embodiment (2-2) ) Modification of second embodiment (3) Third embodiment (4) Fourth embodiment

(1) First Embodiment (1-1) Configuration of Liquid Crystal Display Device According to First Embodiment FIG. 1 is a sectional view showing a configuration example of a liquid crystal display device 1 according to the first embodiment of the present invention. is there. Hereinafter, the configuration of the liquid crystal display device will be described with reference to FIG.

  As shown in FIG. 1, the liquid crystal display device 1 is a so-called transmissive liquid crystal display device, and includes a backlight (light source) 7, a microlens array 8, a polarization selective transmission film 9, and a liquid crystal panel 2. In the following, the side that becomes the display screen of the liquid crystal display device 1 is referred to as a display surface side, and the opposite side is referred to as a back side.

  The backlight 7 is, for example, a cold cathode fluorescent lamp (CCFL) or an LED (Light Emitting Diode), and is disposed immediately below the liquid crystal panel 2. Here, an example of a method of arranging the backlight 7 directly under the liquid crystal panel 2 (directly under type) is shown, but the method of the backlight is not limited to this example, and one end side (edge) of the liquid crystal panel 2 is shown. A backlight (7) such as a cold cathode tube or an LED may be disposed on the side), and a method (edge type) in which light from the backlight 7 is spread over the entire surface of the liquid crystal panel 2 through a light guide plate. In addition, when the liquid crystal panel 2 is a large-sized liquid crystal panel for television use or the like, the backlight is preferably a direct type.

  The microlens array 8 is for improving the directivity of light to the entire panel surface. The polarization selective transmission film 9 is used to unify the polarization plane of the polarizer 25 on the backlight 7 side of the liquid crystal panel 2 so that the plane of polarization matches.

  The liquid crystal panel 2 is formed by sealing liquid crystal between the first substrate 3 and the second substrate 4 and the first substrate 3 and the second substrate 4 that are opposed to each other with a spacer 5 spaced apart from each other. A liquid crystal layer 6. The spacer 5 is for maintaining a predetermined distance between the first and second substrates 3 and 4. The liquid crystal layer 6 is made of a liquid crystal such as a nematic liquid crystal, for example, and the arrangement thereof changes according to the voltage applied between the transparent electrode 13 and the transparent electrode 22.

  The first substrate 3 includes a substrate 21 made of glass, plastic, or the like. A transparent electrode 22 and an alignment film 23 are sequentially stacked on one main surface of the substrate 21, and an optical compensation film is formed on the other main surface. 24 and a polarizer (polarizing film) 25 are sequentially laminated. Although illustration is omitted for convenience, a semiconductor element such as a TFT, a signal line, and a scanning line are provided on one main surface of the substrate 21. The thickness of the substrate 21 is not particularly limited as long as the semiconductor element can be formed by a thin film forming technique such as sputtering, and may be a flexible sheet-like thickness.

  The second substrate 4 is a color filter substrate (CF substrate). The second substrate 4 includes a substrate 11. A color filter 12, a transparent electrode 13, and an alignment film 14 are sequentially stacked on one main surface of the substrate 11, and optical compensation is formed on the other main surface of the substrate 11. A film 15 and a polarizer (polarizing film) 16 are sequentially laminated.

  The transparent electrodes 13 and 22 are, for example, an alloy oxide (ITO: Indium Tin Oxide) of indium and tin. The alignment films 14 and 23 are films for aligning liquid crystal molecules in a certain direction, and are made of a polymer such as polyimide, for example.

  The color filter 12 is for color display. For example, R (red), G (green), and B (blue) elements are arranged corresponding to the pixels. Each pixel is composed of three sub-pixels of R (red), G (green), and B (blue). The size of the sub-pixel depends on the screen size and the number of pixels, but is about several tens of μm, for example.

  The optical compensation films 15 and 24 are disposed on both the display surface side and the back surface side of the liquid crystal panel 2. The optical compensation films 15 and 24 are films for compensating the refractive index. For example, a film formed by arranging optically negative uniaxial compounds so that the orientation angle continuously changes in the thickness direction. It is. Specifically, for example, it is composed of an alignment film provided on a support and an optically anisotropic layer in which a discotic compound that is a negative uniaxial compound is hybrid-aligned. As the discotic compound, for example, a discotic liquid crystal type compound can be used.

  The polarizers 16 and 25 are films that allow only one of the orthogonally polarized components of incident light to pass and absorb or reflect the other. For example, the transmission axes on the optical compensation films 15 and 24 are orthogonal to each other. Arranged.

(1-2) Configuration of Microwave Heating Device According to First Embodiment The present invention is characterized in that microwaves are applied to a substrate on which a semiconductor film is formed while being subjected to multiple reflections. By irradiating the substrate with microwaves while making multiple reflections, the intensity of the microwaves irradiated / absorbed on the semiconductor film can be made uniform, so that uniform processing within the substrate surface becomes possible. In order to irradiate microwaves while making multiple reflections, it is only necessary to prevent the microwaves oscillated from the microwave oscillating tube from irradiating the substrate directly through the waveguide. For example, a waveguide port for irradiating microwaves may be disposed at a blind spot position that cannot be seen from the substrate. In addition, it is preferable that the distance between the reflecting plates that perform multiple reflection is as large as possible with respect to the wavelength of the microwave to be irradiated. For example, the wavelength is 5 times or more, more preferably 10 times or more. On the other hand, if a substrate is directly irradiated with microwaves without multiple reflections, such as by placing a substrate in the vicinity of the waveguide port, a plurality of substrates can be processed continuously. Thus, the irradiation conditions are different and the variation between the substrates becomes large, and when annealing proceeds in a specific portion within the surface, that portion is preferentially annealed and over-annealed.

  Hereinafter, a microwave heating apparatus according to a first embodiment of the present invention will be described with reference to the drawings. FIG. 2 is a perspective view showing an appearance of the microwave heating apparatus 101 according to the first embodiment of the present invention. 3 is a cross-sectional view taken along line III-III in FIG. 4 is an enlarged sectional view taken along line III-III in FIG. FIG. 5 is a cross-sectional view taken along line IV-IV in FIG.

  As shown in FIGS. 2 and 3, the microwave heating apparatus 101 includes a feed roller 102, a take-up roller 103, guide rollers 104 a and 104 b, guide rollers 105 a and 105 b, and a microwave irradiation unit 106. A microwave oscillation device (not shown) having a microwave oscillation tube for oscillating microwaves is provided in the vicinity of the microwave heating device 101, and the microwaves oscillated from the microwave oscillation device are microwaves. It is introduced into the irradiation unit 106.

  The microwave heating apparatus 101 is a heating apparatus that uses a so-called roll-to-roll process in which an object 111 to be irradiated is sent out from the feed roller 102 and the taken-up object 111 is wound around the take-up roller 103. It is.

  The feed roller 102 and the take-up roller 103 are horizontally supported at a predetermined distance, and a microwave irradiation unit 106 is provided between the feed roller 102 and the take-up roller 103. Guide rollers 104 a and 104 b are provided on the feed roller 102 side of the microwave irradiation unit 106, and guide rollers 105 a and 105 b are provided on the take-up roller 103 side.

  The irradiation object 111 is a belt-like substrate or sheet in which a semiconductor film is provided on at least one main surface, and the semiconductor film is made of, for example, amorphous silicon. Note that an absorption layer that absorbs microwaves may be provided in the upper layer and / or the lower layer of the semiconductor film. Note that the absorption layer provided as the upper layer may be removed after the microwave irradiation. The material constituting the absorption layer is not particularly limited as long as it can absorb microwaves. For example, a metal or an alloy is used.

  The feed roller 102 has a cylindrical shape and is configured to be rotatable about the center thereof. An irradiation target object 111 produced by a predetermined process is wound around the feed roller 102, and the wound irradiation target object 111 is directed toward the micro irradiation unit 106 as the feed roller 102 rotates. Sent out.

  The take-up roller 103 has a cylindrical shape and is configured to be rotatable about the center thereof. An object to be irradiated 111 that has been fed from the feed roller 102 and passed through the micro-irradiation unit 106 is taken up by the take-up roller 103.

  The guide rollers 104 a and 104 b and the guide rollers 105 a and 105 b are for guiding the irradiation target 111 to appropriate positions in the microwave irradiation unit 106. The guide rollers 104a and 104b have a cylindrical shape, and are arranged to face each other at a predetermined interval, for example, a distance of about the thickness of the irradiation target object 111. The guide rollers 105a and 105b have a cylindrical shape, and are arranged to face each other with a predetermined interval, for example, a distance of about the thickness of the irradiation target object 111.

  The microwave irradiation unit 106 includes a plurality of microwave irradiation tubes 109 connected in a row by a connecting unit 110, and a carry-in port and a carry-out port are respectively provided at both ends of the connected microwave irradiation tube 106. Yes. The carry-in entrance is an opening for carrying the object to be irradiated 111 into the microwave irradiation unit 1, and the carry-out port is an opening for carrying the object to be irradiated 111 out of the microwave irradiation unit 1.

  Further, the flange portion 107 a and the flange portion 107 b are provided on the carry-in side of the microwave irradiation unit 106, and the flange portions 108 a and 108 b are provided on the carry-out side of the microwave irradiation unit 106. The flanges 107a and 107b and the jaws 108a and 108b are for preventing the microwave introduced into the microwave irradiation unit 106 from leaking to the outside, and are horizontal while maintaining a certain clearance (gap). It extends to. Note that the flanges 107a and 107b and the jaws 108a and 108b are preferably made of a material having microwave absorbability in order to prevent the microwave from leaking to the outside.

  The microwave irradiation tube 109 is for irradiating the irradiation target object 111 conveyed in the microwave irradiation tube 109 while performing multiple reflection of the microwaves. The microwave irradiation tube 109 has a hollow cylindrical shape. A waveguide port 109c is provided at one end of the microwave irradiation tube 109, and the waveguide 112 is connected to the waveguide port 109c. A microwave oscillated from a microwave irradiation device (not shown) is introduced into the microwave irradiation tube 109 through the waveguide 112.

  The length of the microwave irradiation tube 109 is selected wider than the width of the irradiation target object 111, and the irradiation target object 111 is not directly irradiated with the microwave introduced from the waveguide port 109c. It is conveyed a predetermined distance away from one end where the wave tube port 109c is provided. As a result, it is possible to irradiate the object 111 with multiple reflections of microwaves in the microwave irradiation tube 109. Therefore, it is possible to irradiate the irradiated object 111 with a more uniform microwave.

  Further, as shown in FIG. 4, the irradiation object 111 is transported into the microwave irradiation tube 109 so as to pass through the center of the microwave irradiation tube 109 having a circular cross section or the vicinity thereof.

  Further, it is preferable to make the diameter of the reflection surface 109 that multi-reflects the microwave as large as possible with respect to the wavelength of the irradiated microwave, for example, set to 5 times or more, preferably 10 times or more of the wavelength.

  As described above, by providing the plurality of microwave irradiation tubes 109, it is possible to make the intensity of the microwaves irradiated and absorbed on the irradiation target object 111 uniform. The irradiated object 111 may be swung in a direction perpendicular to the traveling direction of the irradiated object 111. In order to swing the irradiation target object 111 in this way, for example, the feed roller 102 and the take-up roller 103 may be configured to be swingable in a direction perpendicular to the advancing direction of the substrate. By swinging the irradiation object 111 in this way, a more uniform process can be performed.

  As shown in FIGS. 3 to 5, a cooling solvent path 109 b is provided inside the microwave irradiation unit 106, an introduction pipe (not shown) for introducing the cooling solvent into the cooling solvent path 109 b, An outlet tube (not shown) for extracting the cooling solvent from the cooling solvent 109 b is connected to the microwave irradiation unit 106.

  The cooling solvent path 109 b is a cooling mechanism for controlling the atmosphere in the microwave irradiation tube 109. For example, water, oil, liquid nitrogen, liquid helium, or the like can be used as the cooling solvent flowing through the cooling solvent path 109b. By flowing the cooling solvent through the cooling solvent path 109b in this way, the atmosphere of the microwave irradiation tube 109 can be controlled, and the temperature increase of the irradiated object 111 can be suppressed. Note that when the irradiation target 111 includes a substrate made of glass having a softening temperature of 600 ° C. or less (for example, non-alkali glass), the atmosphere in the microwave irradiation period 109 is preferably maintained at 600 ° C. or less.

  In the first embodiment, a case where the microwave irradiation unit 106 is formed by combining a microwave irradiation tube 109 having a cylindrical shape will be described as an example. However, the microwave irradiation unit 106 includes a plurality of microwave irradiation units 106 connected to the inside thereof. As long as it has a cylindrical space, it is not particularly limited to this example.

  FIG. 6 is a cross-sectional view illustrating another configuration example of the microwave irradiation unit 106. As shown in FIG. 6, it is good also as a structure which provided the several column-shaped space connected in the inside of the plate-shaped base material etc. which consist of a material which has a microwave reflectivity.

(1-3) Manufacturing Method of Semiconductor Device Substrate according to First Embodiment The manufacturing method of a semiconductor device substrate according to the present invention is characterized in that a substrate on which a semiconductor thin film is formed is irradiated with multiple reflections of microwaves. . By irradiating the substrate with microwaves while making multiple reflections, the intensity of the microwaves irradiated and absorbed on the semiconductor thin film can be made uniform, so that uniform processing within the substrate surface becomes possible.

  Next, a method for manufacturing a semiconductor element substrate according to the first embodiment of the present invention will be described with reference to FIG. Here, a case where the microwave is applied to the semiconductor thin film using the microwave heating apparatus 101 according to the first embodiment will be described as an example. However, the method for manufacturing a semiconductor substrate of the present invention is limited to this example. It is not something.

First, an undercoat 31 made of silicon oxide (SiO _x ) is formed on the substrate 21 made of plastic, for example, by the CVD method. Next, a semiconductor film made of amorphous silicon is formed on the undercoat 31 by, for example, plasma CVD (hereinafter referred to as PECVD). Next, the semiconductor film 32 and the semiconductor film 33 are formed by patterning the semiconductor film into a predetermined shape by, for example, a photolithography process and a dry etching process. Next, after forming the gate insulating film 34 by plasma CVD using, for example, tetraethoxysilane (TEOS), an alloy thin film made of MoW alloy or the like is formed by sputtering, for example. Thereafter, the gate electrode 35 is formed by patterning the alloy thin film by, for example, a photolithography process and an etching process.

  Next, the n-type TFT region is covered with a predetermined resist pattern by, for example, a photolithography process, and boron (B) is implanted into the semiconductor film in the p-type TFT region by, for example, ion doping. At this time, since the gate electrode 35 serves as a mask, boron (B) is not implanted into the semiconductor film of the channel region 32C, and a large amount of boron (B) is implanted only into the source region 32S and the drain region 32D.

  Next, the p-type TFT region is covered with a predetermined resist pattern by, for example, a photolithography process, and phosphorus (P) is implanted into the semiconductor film in the n-type TFT region by, for example, ion doping. Next, after performing gate electrode processing for reducing the width of the gate electrode 35 of the n-type TFT, a smaller amount of phosphorus (P) than the source region 33S and the drain region 33D is formed in an LDD (Lightly Doped Drain) region 33L. inject. At the time of doping, since the gate electrode 35 serves as a mask, phosphorus (P) is not implanted into the semiconductor film of the channel region 33C, and phosphorous (P) is applied only to the source region 33S, the drain region 33D, and the LDD region 33L. ) Is injected.

  Thereafter, the substrate 21 is heat-treated at a high temperature to activate the implanted boron (B) and phosphorus (P) impurities. Next, for example, after the substrate 21 obtained as described above is wound around the feed roller 102, the feed roller 102 is attached to the microwave heating apparatus 101. Then, one end of the substrate 21 wound around the feed roller 102 is fixed to the take-up roller 103 via the microwave irradiation unit 106.

  Next, the feed roller 102 and the take-up roller 103 are driven to transport the substrate 21 into the microwave irradiation unit 106 so as to pass through the center of the microwave irradiation tube 109 having a hollow cylindrical shape or the vicinity thereof. Then, a microwave is introduced into the microwave irradiation tube 109 through the waveguide 112, and the semiconductor film 32 and the semiconductor film 33 formed on the substrate 21 are irradiated while being subjected to multiple reflections. Thereby, it is possible to reduce variation in the intensity of the microwaves applied to the semiconductor film 32 and the semiconductor film 33. Therefore, the semiconductor film 32 and the semiconductor film 33 can be processed uniformly and with high reproducibility.

Next, an insulating film 36 such as a SiO ₂ film or a SiNx film is formed on the entire surface by, eg, PECVD. Next, after forming a transparent electrode (pixel electrode) 22 such as an ITO film by sputtering, for example, the pixel is patterned by, for example, a photolithography process and an etching process.

  Next, contact holes are formed in the gate insulating film 34 and the insulating film 36 by, for example, a photolithography process and an etching process. Then, after forming an aluminum (Al) film on the insulating film 36 by, for example, a sputtering method, patterning is performed by, for example, a photolithography process and an etching process to form the source electrode 37S and the drain electrode 37D. Finally, after forming the protective film 38 by, for example, PECVD, the protective film 38 is patterned by, for example, photolithography and etching.

  Finally, the band-shaped semiconductor element substrate obtained as described above is cut into a predetermined width according to the size of a desired liquid crystal display device. As described above, a target semiconductor element substrate is manufactured.

  In the first embodiment described above, an example is described in which a step of irradiating microwaves is performed after the step of doping impurities into the semiconductor film 32 and the semiconductor film 33 and before the step of forming the insulating film 36. However, the order of this process is an example, and the process of irradiating microwaves is not limited to this order. For example, a step of irradiating microwaves may be provided after the step of forming a semiconductor film on the undercoat 31 and before the step of patterning the semiconductor film.

According to the first embodiment of the present invention, the following effects can be obtained.
The substrate 21 on which the semiconductor film 32 and the semiconductor film 33 are formed is conveyed into the microwave irradiation unit 106 so as to pass through the center of the hollow cylindrical microwave irradiation tube 109 or the vicinity thereof, and the microwaves are multiplexed. Since the semiconductor film 32 and the semiconductor film 33 are irradiated while being reflected, variation in the intensity of the microwaves applied to the semiconductor film 32 and the semiconductor film 33 can be reduced. Therefore, the semiconductor film 32 and the semiconductor film 33 can be processed uniformly and with high reproducibility.

  Further, carriers due to chemical doping are generated in the semiconductor film 32 and the semiconductor film 33, and the semiconductor film 32 and the semiconductor film 33 are irradiated with microwaves. It is possible to make the temperature rise steep. Therefore, the semiconductor film 32 and the semiconductor film 33 can be selectively heated in a short time, and damage to the substrate 21 can be suppressed. In addition, a semiconductor element substrate having electron mobility comparable to that of polycrystalline polysilicon can be obtained.

  The microwave heating apparatus 101 includes a microwave irradiation unit 106 that is a microwave irradiation unit, and a feed roller 102 and a take-up roller 103 that are conveyance units. The microwave irradiation unit 106 includes a plurality of microwave irradiation tubes 109 connected in a line and having a hollow cylindrical shape. The feed roller 102 and the take-up roller 103 are driven to transport the irradiation target object 111 into the microwave irradiation unit 106 so as to pass through the center of the microwave irradiation tube 109 having a hollow cylindrical shape or the vicinity thereof. Then, a microwave is introduced into the microwave irradiation tube 109 through the waveguide 112, and the object to be irradiated 111 formed on the substrate 21 is irradiated while being subjected to multiple reflections. Thereby, the dispersion | variation in the intensity | strength of the microwave irradiated with respect to the to-be-irradiated target object 111 can be decreased. Therefore, the irradiated object 111 can be processed uniformly and with good reproducibility.

(1-4) Modification of First Embodiment In the first embodiment, an electric field may be applied to the semiconductor film when the semiconductor film is irradiated with multiple reflections of microwaves. In this case, for example, the semiconductor element substrate is manufactured as follows.

  First, except that the step of irradiating microwaves using the microwave heating apparatus 101 is omitted, the steps up to patterning the protective film 38 are performed in the same manner as in the first embodiment described above, thereby forming a band-shaped semiconductor element. Get the substrate. Then, after winding the obtained semiconductor element substrate around the feed roller 102, the feed roller 102 is attached to the microwave heating device 101.

  Next, one end of the semiconductor element substrate wound around the feed roller 102 is fixed to the take-up roller 103 via the microwave irradiation unit 106, and then wiring is applied to the gate electrode 35. At this time, it is preferable to protect the wiring with ferrite beads.

  Next, the feed roller 102 and the take-up roller 103 are driven to transport the semiconductor element substrate into the microwave irradiation unit 106 so as to pass through the center or the vicinity of the microwave irradiation tube 109 having a hollow cylindrical shape. . And while applying a gate voltage, a microwave is introduce | transduced in the microwave irradiation tube 109 via the waveguide 112, and it irradiates, multiply-reflecting a microwave with respect to a semiconductor element substrate. The gate voltage is set in the range of 0 to 100V, for example. Finally, the band-shaped semiconductor element substrate obtained as described above is cut into a predetermined width according to the size of a desired liquid crystal display device. As described above, a target semiconductor element substrate is manufactured.

In the modification of the first embodiment of the present invention, the following effects can be obtained.
Carriers due to electrical doping are generated in the semiconductor film 32 and the semiconductor film 33 and the semiconductor film 32 and the semiconductor film 33 are irradiated with microwaves. Therefore, the microwaves are efficiently applied to the semiconductor film 32 and the semiconductor film 33. It can be absorbed to enable a steep rise in temperature. Therefore, the semiconductor film 32 and the semiconductor film 33 can be selectively heated in a short time, and damage to the substrate 21 can be suppressed. In addition, a semiconductor element substrate having electron mobility comparable to that of polycrystalline polysilicon can be obtained.

  In addition, the semiconductor film 32 and the semiconductor film 33 can be modified at a low temperature of 600 degrees or less. That is, a semiconductor element substrate can be manufactured using glass having a softening temperature of 600 ° C. or less, for example, inexpensive alkali-free glass. In addition, the crystal orientation can be aligned by an electric field applied to the semiconductor film 32 and the semiconductor film 33.

(2) Second Embodiment Next, a second embodiment of the present invention will be described. The second embodiment is the same as the first embodiment except that a bottom-gate type semiconductor element substrate is provided as the semiconductor element substrate. Therefore, the configuration of the liquid crystal display device and the microwave heating apparatus Description of the configuration is omitted, and a method for manufacturing a semiconductor element substrate will be described below.

(2-1) Semiconductor Device Substrate Manufacturing Method According to Second Embodiment Hereinafter, a semiconductor device substrate manufacturing method according to the second embodiment of the present invention will be described with reference to FIG. First, an alloy thin film made of a MoW alloy or the like is formed on the substrate 21 by sputtering, for example. Thereafter, the alloy thin film is patterned by, for example, a photolithography process and an etching process to obtain the gate electrode 131.

Next, for example, by PECVD, an insulating film 132 made of, for example, SiO ₂ or SiN, a semiconductor film 133 made of amorphous silicon, for example, an amorphous silicon film doped with phosphorus (P) (hereinafter, n ⁺ a-Si layer) 134 are sequentially formed on the substrate 21. Then, the semiconductor film 133 and the n ⁺ a-Si film 134 are patterned by, for example, a photolithography process and an etching process.

  Next, after forming a transparent electrode (pixel electrode) 22 such as an ITO film by sputtering, for example, the pixel is patterned by, for example, a photolithography process and an etching process.

Next, after forming a metal thin film such as Al, for example, patterning is performed to form the source electrode 135 and the drain electrode 136. Thereafter, using the source electrode 135 and the drain electrode 136 as a mask, the n ⁺ a-Si film 134 between the electrodes is etched.

  Next, after winding the semiconductor element substrate obtained as described above around the feed roller 102, the feed roller 102 is attached to the microwave heating apparatus 101. Then, one end of the semiconductor element substrate wound around the feed roller 102 is fixed to the take-up roller 103 via the microwave irradiation unit 106.

  Next, the feed roller 102 and the take-up roller 103 are driven to transport the substrate 21 into the microwave irradiation unit 106 so as to pass through the center of the microwave irradiation tube 109 having a hollow cylindrical shape or the vicinity thereof. Then, a microwave is introduced into the microwave irradiation tube 109 through the waveguide 112, and the semiconductor element substrate is irradiated while being subjected to multiple reflections. Thereby, the dispersion | variation in the intensity | strength of the microwave irradiated with respect to a semiconductor element substrate can be decreased. Therefore, the semiconductor element substrate can be processed uniformly and with good reproducibility.

  Next, the belt-like substrate 21 wound around the take-up roller 103 is fed out and cut into a predetermined width according to the desired size of the liquid crystal display device. As described above, a target semiconductor element substrate is manufactured.

  In the second embodiment of the present invention, the same effect as in the first embodiment can be obtained.

(2-2) Modification of Second Embodiment In the second embodiment, an electric field may be applied to a semiconductor film when multiple reflections of microwaves are applied to the semiconductor film. In this case, for example, the semiconductor element substrate is manufactured as follows.

  First, similarly to the method for manufacturing the semiconductor element substrate according to the second embodiment described above, the steps before the microwave irradiation are performed. Then, before irradiating the microwave, wiring is applied to the gate electrode 131 of the obtained semiconductor element substrate. At this time, it is preferable to protect the wiring with ferrite beads.

  Next, the feed roller 102 and the take-up roller 103 are driven to transport the substrate 21 into the microwave irradiation unit 106 so as to pass through the center of the microwave irradiation tube 109 having a hollow cylindrical shape or the vicinity thereof. Then, while applying a gate voltage, a microwave is introduced into the microwave irradiation tube 109 through the waveguide 112, and the microwave is subjected to multiple reflection on the semiconductor element substrate formed on the substrate 21. Irradiate. The gate voltage is set in the range of 0 to 100V, for example. As described above, a target semiconductor element substrate is manufactured.

  In the modification of the second embodiment of the present invention, the same effect as the deformability of the first embodiment described above can be obtained.

(3) Third Embodiment FIG. 9 is a perspective view showing an appearance of a microwave heating apparatus 201 according to a third embodiment of the present invention. Waveguide ports are alternately provided at end portions of the plurality of microwave irradiation tubes 109 connected by the connecting portion 110, and the waveguide 112 is connected to the waveguide ports. The length of the microwave irradiation tube 109 is selected wider than the width of the irradiated object 111, and the irradiated object 111 is irradiated with microwaves so that the microwave introduced from the waveguide port 109c is not directly irradiated. It is conveyed at a predetermined distance from both ends of the tube 109. Since other than that is the same as that of the above-mentioned 1st Embodiment, description is abbreviate | omitted.

  In the third embodiment, it is possible to obtain an effect that the irradiation target object 111 can be irradiated with a more uniform microwave as compared with the first embodiment described above.

(4) Fourth Embodiment FIG. 10 is a perspective view showing an appearance of a microwave heating apparatus 301 according to a fourth embodiment of the present invention. Each of the plurality of microwave turrets 109 connected by the connecting part 110 is provided with a waveguide port at both ends, and a waveguide 112 is connected to the waveguide port. The length of the microwave irradiation tube 109 is selected wider than the width of the irradiated object 111, and the irradiated object 111 is irradiated with microwaves so that the microwave introduced from the waveguide port 109c is not directly irradiated. It is conveyed at a predetermined distance from both ends of the tube 109. Since other than that is the same as that of the above-mentioned 1st Embodiment, description is abbreviate | omitted.

  In the fourth embodiment, it is possible to obtain an effect that the irradiation target object 111 can be irradiated with a more uniform microwave than in the third embodiment described above.

  In addition, the present inventor conducted the following study in order to verify the effect of modifying the amorphous silicon thin film by microwave irradiation.

Sample 1
First, a sample 1 was obtained by depositing an amorphous silicon thin film on a substrate by CVD. Thereafter, the crystallinity of the amorphous silicon thin film was analyzed by Raman spectroscopy.

Sample 2
First, an amorphous silicon thin film was formed on a substrate by CVD, and a sample of 2 was obtained by irradiating the amorphous silicon thin film with a microwave of 2.45 GHz. Thereafter, the crystallinity of the amorphous silicon thin film was analyzed by Raman spectroscopy.

Sample 3
After preparing Sample 3 in the same manner as Sample 2, the crystallinity of the amorphous silicon thin film was analyzed by Raman spectroscopy.

  FIG. 11 shows the measurement results of the spectra of samples 1 to 3 by Raman spectroscopy. FIG. 11 shows that the high-frequency Raman peak 1 and the Raman peak 2 that are considered to be derived from dangling bonds are reduced by microwave irradiation. Thus, it can be seen that the amorphous silicon thin film can be modified by irradiation with microwaves.

Sample 4
First, an amorphous silicon thin film was formed on a substrate by CVD, and the crystallinity of the amorphous silicon thin film was analyzed by Raman spectroscopy. Then, after irradiating the amorphous silicon thin film formed on the substrate with microwaves of 28 GHz, the crystallinity of the amorphous silicon thin film was analyzed by Raman spectroscopy.

FIG. 12 shows the spectrum of sample 4 near 500 cm ⁻¹ before and after microwave irradiation. From Figure 12, by microwave irradiation, it is understood that Raman peak is shifted from 480 cm ^-1 to 523cm ^-1. In other words, it can be seen that the amorphous silicon is polymorphized by microwave irradiation.

  As mentioned above, although each embodiment of this invention was described concretely, this invention is not limited to each above-mentioned embodiment, Various deformation | transformation based on the technical idea of this invention is possible.

  For example, the numerical values given in the above-described embodiments are merely examples, and different numerical values may be used as necessary.

  In each of the above-described embodiments, the case where the present invention is applied to the semiconductor element substrate provided in the liquid crystal display device is shown as an example. However, the present invention can also be used in other electronic device manufacturing processes. . Further, the present invention can be used not only in the improvement of a semiconductor film such as an amorphous thin film but also in a film-forming drying process and a heating process.

  Further, in each of the above-described embodiments, microwave irradiation may be performed in a vacuum atmosphere.

  Further, in each of the above-described embodiments, the transport unit that transports the irradiation target object 111 to the microwave irradiation unit 106 is not limited to the feed roller 102 and the take-up roller 103. For example, instead of the feed roller 102 and the take-up roller 103, a feed mechanism capable of performing microwave irradiation in a state where an object to be irradiated such as a substrate is held in a flat shape without being wound around a roller or the like is provided. You may do it.

  Moreover, in each above-mentioned embodiment, it is preferable that the guide rollers 105 a and 105 b have a configuration capable of cooling the irradiation target object 111 that has passed through the microwave irradiation unit 106. By setting it as the structure which can be cooled in this way, the to-be-irradiated target object 111 which rose in temperature by microwave irradiation can be cooled rapidly. Therefore, damage to the irradiated object 111 due to heat can be reduced.

  In each of the above-described embodiments, a plurality of microwave irradiation tubes 109 are arranged in a line without being connected by the connecting portion 110, and a guide roller having a cooling mechanism is provided between the arranged microwave irradiation tubes 109. May be provided. As a result, the irradiation target object 111 is cooled by the guide roller every time it passes through each microwave irradiation tube 109, so that the irradiation target object 111 whose temperature has been increased by the microwave irradiation can be cooled more quickly. it can. Therefore, damage to the irradiated object 111 due to heat can be further reduced.

  Further, in each of the above-described embodiments, the case where the microwave irradiation unit 106 has a cylindrical space and multiple reflections of microwaves in the space is shown as an example, but the space for multiple reflections of microwaves is shown. The shape of is not limited to this example. That is, the shape of the space for the multiple reflection of the microwave is such that the irradiation target 111 is irradiated with multiple reflections of the microwave, and the intensity of the microwave irradiated to the irradiation target 111 is as follows. Any shape that can reduce the variation may be used. As the shape of such a space, in addition to the above-described columnar shape, for example, an elliptical columnar shape, a shape formed by opposing parabolic column surfaces, and the like can be given.

It is sectional drawing which shows one structural example of the liquid crystal display device by 1st Embodiment of this invention. 1 is a perspective view showing an appearance of a microwave heating apparatus according to a first embodiment of the present invention. It is sectional drawing in the III-III line of FIG. It is an expanded sectional view in the III-III line of FIG. It is sectional drawing in the IV-IV line of FIG. It is an expanded sectional view showing other examples of composition of a microwave irradiation tube. 1 is a cross-sectional view of a semiconductor element substrate according to a first embodiment of the present invention. It is sectional drawing of the semiconductor element substrate by 2nd Embodiment of this invention. It is a perspective view which shows the external appearance of the microwave heating device by 3rd Embodiment of this invention. It is a perspective view which shows the external appearance of the microwave heating device by 4th Embodiment of this invention. It is a basic diagram which shows the measurement result of the spectrum by a Raman spectroscopy. It is an approximate line figure showing a spectrum near 500cm- ¹ .

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Liquid crystal display device, 2 ... Liquid crystal panel, 3 ... 1st board | substrate, 4 ... 2nd board | substrate, 5 ... Spacer, 6 ... Liquid crystal layer, 7 ... Backlight, 8 ... microlens array, 9 ... polarization selective transmission film, 11,21 ... substrate, 12 ... color film, 13,22 ... transparent electrode, 14,23 ... Alignment film 15, 24 ... Optical compensation film, 16, 25 ... Polarizer, 31 ... Undercoat, 32, 33 ... Semiconductor film, 32S, 33S ... Source region, 32D, 33D ... Drain region, 34 ... Gate insulating film, 35 ... Gate electrode, 36 ... Insulating film, 37S ... Source electrode, 37D ... Drain electrode, 38 ... Protective film

Claims (10)

Forming a semiconductor film on the substrate;
And a step of irradiating the semiconductor film with multiple reflections of microwaves.   2. The method of manufacturing a semiconductor element substrate according to claim 1, further comprising a step of forming an absorption layer that absorbs microwaves in an upper layer and / or a lower layer of the semiconductor film.   2. The method of manufacturing a semiconductor element substrate according to claim 1, wherein a frequency of the microwave is in a range of 1 GHz to 100 GHz.   2. The method of manufacturing a semiconductor element substrate according to claim 1, wherein microwave irradiation is performed while cooling the substrate and / or the microwave irradiation atmosphere by a cooling mechanism.   5. The method of manufacturing a semiconductor element substrate according to claim 4, wherein the microwave irradiation atmosphere is 600 [deg.] C. or less.   5. The method of manufacturing a semiconductor element substrate according to claim 4, wherein the cooling mechanism is water cooling.   2. The method of manufacturing a semiconductor element substrate according to claim 1, wherein the substrate is made of glass or plastic.   2. The method of manufacturing a semiconductor element substrate according to claim 1, wherein the step of irradiating the microwave is performed by a roll-to-roll process.   A semiconductor element substrate manufactured by the manufacturing method according to claim 1.   A display device comprising the semiconductor element substrate according to claim 9.

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