JP4772261B2 - Display device substrate manufacturing method and crystallization apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a substrate of a display device such as a liquid crystal display device and a crystallization apparatus.
[0002]
[Prior art]
In recent years, liquid crystal display devices are used in various applications, and demands for higher definition and higher performance are increasing. The liquid crystal display device includes a liquid crystal panel in which liquid crystal is sandwiched between a pair of substrates. One substrate is called a TFT substrate, on which a thin film transistor (TFT) is formed. The liquid crystal panel includes a pixel portion which is a display region and a peripheral circuit portion around the pixel portion. A TFT is provided for each pixel in the pixel portion, and other TFTs are formed in the peripheral circuit portion. Recently, it has been particularly required to form TFTs in the peripheral circuit portion with high reliability.
[0003]
The operating layer of the TFT has been conventionally formed of an amorphous semiconductor (amorphous silicon), but recently, it has been formed of a polycrystalline semiconductor (polycrystalline silicon). A polycrystalline semiconductor is formed by a crystallization process for crystallizing an amorphous semiconductor layer formed on a substrate.
[0004]
The crystallization treatment is performed by irradiating the amorphous semiconductor layer of the substrate with laser light. For example, an excimer pulse laser is used as a laser for crystallization (see, for example, Patent Document 1 and Patent Document 2). However, crystallization of an amorphous semiconductor using an excimer pulse laser has a relatively low mobility of the semiconductor, and may not satisfy the demand for higher definition and higher performance of a liquid crystal display device. Therefore, a semiconductor crystallization method using a continuous wave laser (CW laser) has been proposed (for example, see Non-Patent Document 1). There is also a proposal of Japanese Patent Application No. 14-143070. Crystallization of an amorphous semiconductor using a CW laser can increase the crystal grain size and realize a relatively large mobility of the semiconductor, which is particularly advantageous for forming a TFT in a peripheral circuit portion of a liquid crystal display device. is there.
[0005]
[Patent Document 1]
Japanese Patent Laid-Open No. 10-41244 [Patent Document 2]
JP-A-8-203843 [Non-Patent Document 1]
IEICE Transactions, Vol. J185, CN08, August 2002, P601-608
[0006]
[Problems to be solved by the invention]
In crystallization of an amorphous semiconductor layer, the amorphous semiconductor layer is scanned with laser light. Laser scanning is performed while moving a substrate having an amorphous semiconductor layer together with a stage and irradiating the amorphous semiconductor layer with laser light from a laser held at a fixed position. In the case of scanning using an excimer pulse laser, since the size of the beam spot is considerably large, the scanning time per unit area is short, and the productivity of the liquid crystal display device is good. However, in the case of scanning using a CW laser, since the size of the beam spot is very small, the scanning time per unit area increases, the productivity of the liquid crystal display device decreases, and the manufacturing cost increases.
[0007]
Therefore, if a plurality of lasers are arranged close to each other and a plurality of portions of the amorphous semiconductor layer are irradiated simultaneously with a plurality of laser beams, this is the same as increasing the beam spot of the laser beams, and the scanning time The productivity of the liquid crystal display device can be improved.
[0008]
However, when using a plurality of laser beams at the same time, it is often difficult to make the energy of the plurality of laser beams the same, and there may be a difference in the energy of the plurality of laser beams. If there is a difference in the energy of a plurality of laser beams, it will cause variations in the performance of the TFTs of the manufactured liquid crystal panel, resulting in a decrease in yield.
[0009]
An object of the present invention is to provide a method for manufacturing a substrate of a display device and a crystallization apparatus suitable for manufacturing a high-performance substrate at a low yield and with a high yield.
[0010]
[Means for Solving the Problems]
A method of manufacturing a substrate of a display device according to the present invention is a method of manufacturing a substrate of a display device having a plurality of panel regions, each panel region including a pixel portion and a peripheral circuit portion around the pixel portion, Including a step of simultaneously crystallizing the amorphous semiconductor layer formed on the substrate with a plurality of high energy lights, and the peripheral circuit portion of one panel region includes only one of the plurality of strong energy lights. It is characterized by being crystallized with.
[0011]
According to this configuration, a substrate having a plurality of panel regions is simultaneously irradiated with a plurality of strong energy lights, and scanning is performed in a short time to crystallize the amorphous semiconductor layer. At that time, the peripheral circuit portion of one panel region is crystallized by one strong energy light. Therefore, in one panel region, the amorphous semiconductor layer is crystallized with a single strong energy light, and the performance of the formed transistor becomes uniform.
[0012]
The crystallization apparatus according to the present invention is a crystallization apparatus for an amorphous semiconductor layer formed on an insulating substrate, and includes a plurality of strong energy light sources and a variable variable position of the plurality of strong energy light sources. And a stage for supporting the substrate on which the amorphous semiconductor layer is formed, wherein the amorphous semiconductor layer formed on the substrate is simultaneously crystallized by a plurality of strong energy lights. It is.
[0013]
According to this configuration, a plurality of strong energy light sources are provided, and a substrate having a plurality of panel regions is irradiated with a plurality of strong energy lights simultaneously, and scanning is performed in a short time, whereby the amorphous semiconductor layer is crystallized. Turn into. The positions of the plurality of strong energy light sources can be changed, and the pitch of the strong energy light is adjusted to the pitch of the plurality of panel regions so that the peripheral circuit portion of one panel region is crystallized by one strong energy light. be able to. Therefore, in one panel region, the amorphous semiconductor layer is crystallized with a single strong energy light, and the performance of the formed transistor becomes uniform.
[0014]
Thus, according to the present invention, a high-performance display device can be manufactured at a low cost and with a high yield.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0016]
FIG. 1 is a schematic sectional view showing a liquid crystal panel 10 of a liquid crystal display device according to an embodiment of the present invention. The liquid crystal panel 10 is formed by inserting a liquid crystal 16 between a pair of opposing substrates 12 and 14. Electrodes and alignment films can be provided on the substrates 12 and 14. One substrate 12 is a TFT substrate, and the other substrate 14 is a color filter substrate.
[0017]
FIG. 2 is a schematic plan view showing the substrate 12 of FIG. The substrate 12 includes a pixel unit 18 and a peripheral circuit unit 20 around the pixel unit 18. The pixel unit 18 includes a large number of pixels 22. In FIG. 2, one pixel 22 is partially enlarged. The pixel 22 includes sub-pixel areas RGB of three colors, and a TFT is formed in each sub-pixel area RGB. The peripheral circuit unit 20 includes a control circuit including a plurality of TFTs, and the TFTs in the peripheral circuit unit 20 are arranged more densely than the TFTs in the display region 18.
[0018]
FIG. 3 is a schematic plan view showing a glass substrate 24 for making the substrate 12 of FIG. The glass substrate 24 includes a plurality of panel regions. One panel region corresponds to the substrate 12 of one liquid crystal panel 10 and includes a pixel portion 18 and a peripheral circuit portion 20. In the example shown in FIG. 3, there are four panel regions, and four substrates 12 of the liquid crystal panel 10 are collected from one glass substrate 24. The glass substrate 24 is cut into four substrates 12 after manufacturing TFTs and the like. It is also possible to collect four or more substrates 12 from one glass substrate 24.
[0019]
FIG. 4 is a diagram showing an embodiment of a crystallization process and apparatus based on the present invention. FIG. 5 is a perspective view showing details of the crystallization apparatus of FIG. In the manufacturing process before crystallization shown in FIGS. 4 and 5, an amorphous semiconductor layer (amorphous silicon layer) is formed on the glass substrate 24, and the amorphous semiconductor layer is crystallized, A TFT including a polycrystalline semiconductor layer is formed as a polycrystalline semiconductor layer (polycrystalline silicon layer).
[0020]
The glass substrate 24 is supported by the XY stage 26. The XY stage 26 is movable in the X direction and the Y direction. In crystallization of the amorphous semiconductor layer, the amorphous semiconductor layer is scanned with laser light 28. The scanning is performed while moving the glass substrate 24 having an amorphous semiconductor layer together with the XY stage 26 and irradiating the amorphous semiconductor layer with laser light 28 held at a fixed position.
[0021]
The laser device 30 includes two laser light sources 32 and 34, and the laser light (strong energy light) emitted from the laser light sources 32 and 34 passes through the optical system as an elliptical laser spot. Irradiate the crystalline semiconductor layer. For example, each optical system includes a mirror 36, a substantially semi-cylindrical lens 38, a substantially semi-cylindrical lens 40 disposed so as to be orthogonal to the lens 38, and a convex lens (not shown). Become.
[0022]
The laser light sources 32 and 34 are supported on the frame 46 of the laser device 30 by support adjustment mechanisms 42 and 44, respectively. The support adjusting mechanisms 42 and 44 support the laser light sources 32 and 34, respectively, and can be adjusted in position by an adjusting bolt or the like (not shown) to constitute a variable mechanism that can change the positions of the laser light sources 32 and 34. The positions of the laser light sources 32 and 34 are adjusted so that the irradiation position matches the interval between the panel regions of the glass substrate 24. The position of the optical system is adjusted in conjunction with the laser light sources 32 and 34.
[0023]
When the peripheral circuit portion 20 is crystallized, as shown in FIG. 5, the laser light 28 emitted from one of the laser light sources 32 is a peripheral circuit in the panel region located on the upper side of the glass substrate 24 in FIG. The laser light 28 emitted from the other laser light source 34 is irradiated to the upper side portion of the peripheral circuit portion 20 in the panel area located on the lower side of the glass substrate 24 in FIG. To be arranged. Laser light 28 emitted from the two laser light sources 32 and 34 simultaneously irradiates the upper side portion of the peripheral circuit section 20 in the two panel regions. However, the peripheral circuit unit 20 in one panel region is crystallized by only one laser beam 28 of the laser beams 28 emitted from the two laser light sources 32 and 34.
[0024]
In scanning, the laser light sources 32 and 34 are CW lasers, which generate laser light having a wavelength of 532 nm, energy of 6 W, beam diameter of 400 μm × 40 μm, and the XY stage 26 on which the glass substrate 24 is mounted has a scanning speed of 20 cm / s. Moving. A shutter (not shown) linked to the amount of movement of each laser is provided so that only the region requiring crystallization is irradiated.
[0025]
FIG. 6 is a schematic diagram showing a procedure for crystallization of the peripheral circuit section 20 by the crystallization apparatus of FIG. First, laser light 28 emitted from one laser light source 32 scans the upper side portion of the peripheral circuit portion 20 in the panel region on the upper side of the glass substrate 24 as indicated by an arrow A. The laser light 28 emitted from the other laser light source 34 scans the upper side portion of the peripheral circuit portion 20 in the lower panel region of the glass substrate 24 as indicated by an arrow B. The scanning of the peripheral circuit portion 20 in each panel area is performed in the direction of arrows A and B, and then the glass substrate 24 is moved slightly in the direction of arrow Y, and scanning in the direction opposite to the directions of arrows A and B is performed. These scans can be repeated. Note that the laser beam is shielded by the shutter while crystallization is not performed (for example, while the direction is changed).
[0026]
When the scanning of the upper side portion of the peripheral circuit unit 20 in the upper and lower panel regions of the glass substrate 24 is completed, the laser light 28 emitted from one laser light source 32 is transmitted to the periphery of the upper panel region of the glass substrate 24. The lower side portion of the circuit unit 20 is scanned as indicated by an arrow C. The laser light 28 emitted from the other laser light source 34 scans the lower side portion of the peripheral circuit portion 20 in the lower panel region of the glass substrate 24 as indicated by an arrow D. Also in this case, scanning of the upper side portion of the peripheral circuit portion 20 in each panel area is performed not only by scanning in the directions of the arrows C and D but also by scanning in the direction opposite to the arrows C and D. Scanning can be repeated.
[0027]
Next, laser light 28 emitted from one laser light source 32 scans the left side portion of the peripheral circuit portion 20 in the upper panel region of the glass substrate 24 as indicated by an arrow E. The laser light 28 emitted from the other laser light source 34 scans the left side portion of the peripheral circuit portion 20 in the lower panel region of the glass substrate 24 as indicated by an arrow F. Also in this case, scanning of the upper side portion of the peripheral circuit portion 20 in each panel region is performed not only by scanning in the directions of arrows E and F but also by scanning in the direction opposite to the arrows F and E. The scan can be repeated.
[0028]
Next, the laser light 28 emitted from one laser light source 32 scans the right side portion of the peripheral circuit portion 20 in the panel region on the upper side of the glass substrate 24 as indicated by an arrow G. The laser light 28 emitted from the other laser light source 34 scans the right side portion of the peripheral circuit portion 20 in the lower panel region of the glass substrate 24 as indicated by an arrow H. Also in this case, scanning of the upper side portion of the peripheral circuit portion 20 in each panel area is performed not only by scanning in the directions of the arrows G and H but also by scanning in the direction opposite to the arrows G and H. The scan can be repeated. The crystallization procedure and order are not limited to the above example.
[0029]
FIG. 7 is a diagram showing an example of a beam spot of laser light. When crystallization is performed by scanning in the X-axis direction (scanning by arrows A, B, C, and D), as shown in FIG. 7A, the crystallization region is efficiently performed with a wide laser beam. Thus, scanning is performed with an elliptical beam spot that is long in a direction perpendicular to the X-axis direction. Next, when crystallization is performed by scanning in the Y-axis direction (scanning by arrows E, F, G, and H), the shape of the laser beam spot is rotated by 90 degrees, as shown in FIG. 7B. Thus, scanning is performed with an elliptical beam spot that is long in a direction perpendicular to the Y-axis direction. The rotation of the beam spot shape of the laser light is performed by rotating the pair of semi-cylindrical lenses 38 and 40 shown in FIG. 5 by 90 degrees in accordance with the optical axis.
[0030]
If the shape of the laser beam spot is circular, it is not necessary to rotate the shape of the beam spot.
[0031]
FIG. 8 is a schematic diagram showing an example in which the pixel portion 18 is crystallized. In the crystallization of the pixel unit 18, the two laser light sources 32 and 34 are aligned with the interval between the panel regions of the glass substrate 24, the irradiation position is adjusted, the laser light 28 is held at a fixed position, the XY stage 26 and the glass substrate. Scanning is performed while moving 24. The laser light sources 32 and 34 are CW lasers, which generate laser light having a wavelength of 532 nm, energy of 6 W, beam diameter of 400 μm × 40 μm, for example, and the XY stage 26 on which the glass substrate 24 is mounted moves at a scanning speed of 40 cm / s. The laser light is applied to the amorphous semiconductor layer of the glass substrate 24, and the pixel portion 18 is repeatedly scanned.
[0032]
Further, the peripheral circuit unit 20 is crystallized by using two CW lasers as in the examples shown in FIGS. 5 and 6, and the pixel unit 18 is crystallized by, for example, excimer laser (wavelength 308 nm) with an energy of 300 mL / cm. ^2. Irradiation may be performed at a frequency of 300 Hz and a beam overlap rate of 95%.
[0033]
FIG. 9 is a schematic diagram showing another example in which the peripheral circuit unit 20 and the pixel unit 18 are crystallized. In this example, the laser light 28 emitted from one laser light source 32 scans the peripheral circuit portion 20 in the upper panel region of the glass substrate 24, and the laser light 28 emitted from the other laser light source 34 is glass. The pixel portion 18 in the panel area on the lower side of the substrate 24 is scanned. In this way, the pixel unit 18 and the peripheral circuit unit 20 may be irradiated simultaneously with the CW laser. However, the peripheral circuit unit 20 in one panel region is crystallized by only one laser beam among a plurality of laser beams.
[0034]
FIG. 10 is a diagram showing an example of an apparatus for synthesizing laser beams. In this example, a CW laser is also used. FIG. 11 is a diagram illustrating an example of a beam spot of a synthesized laser beam. The laser light 52 emitted from the laser light source 50 is split into two laser lights 52A and 52B by a beam splitter 54. The laser beam 52A is irradiated to the amorphous semiconductor layer of the glass substrate 24 through the mirror 56, the beam splitter 58, and the semicylindrical lenses 60 and 62. The laser beam 52B is irradiated on the amorphous semiconductor layer of the glass substrate 24 through the mirror 54, the beam splitter 58, and the semicylindrical lenses 60 and 62. It should be noted that two lasers may be used for beam synthesis and synthesized in the same manner.
[0035]
As shown in FIG. 11, the laser beams 52A and 52B applied to the amorphous semiconductor layer of the glass substrate 24 are shifted from each other but partially overlap each other. Accordingly, the two CW (continuous oscillation) laser lights are combined into a single spot light. In FIG. 11A, the two laser beams 52A and 52B are shifted from each other in the long axis direction to provide a beam spot having a longer width. In this case, it is important to align the energy of the two spots 52A and 52B. This is because it must be crystallized uniformly in the major axis direction. In FIG. 11B, the two laser beams 52A and 52B are shifted from each other in the minor axis direction to provide a double beam spot. In this case, the spot size and energy of the two spots 52A and 52B may be changed intentionally. This is because, since the crystal grain size strongly depends on the melting temperature and the cooling speed, polycrystalline silicon having a large grain size can be obtained by adjusting two beams and optimizing them.
[0036]
The beam spots shown in FIGS. 11A and 11B can be configured to irradiate the peripheral circuit unit 20 instead of the beam spots shown in FIG. Further, the beam spots shown in FIGS. 11A and 11B can be configured to irradiate the pixel portion 18 instead of the beam spots shown in FIG. Further, the beam spots shown in FIGS. 11A and 11B can be configured to irradiate the pixel portion 18 and the peripheral circuit portion 20 instead of the beam spot shown in FIG. When the pixel portion 18 is crystallized, the beam spot may be formed by one laser beam or a combination of a plurality of laser beams.
[0037]
【The invention's effect】
As described above, according to the present invention, since the amorphous semiconductor layer in the peripheral circuit portion of the substrate is crystallized by only one strong energy light, the obtained crystallinity does not vary and the characteristics are uniform. Thus, a stable operation circuit can be manufactured. Further, by using a plurality of strong energy lights, a high processing capability can be obtained, and a display device such as a liquid crystal display device can be manufactured at a low cost.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view showing a liquid crystal display device according to an embodiment of the present invention.
2 is a schematic plan view showing the substrate of FIG. 1. FIG.
3 is a schematic plan view showing a glass substrate for making the substrate of FIG. 2. FIG.
FIG. 4 is a schematic diagram showing a crystallization apparatus for crystallizing an amorphous semiconductor formed on a glass substrate.
FIG. 5 is a perspective view showing details of the crystallization apparatus of FIG. 4;
6 is a schematic diagram showing a procedure for crystallization of a peripheral circuit section by the crystallization apparatus of FIG.
FIG. 7 is a diagram showing an example of a beam spot of laser light.
FIG. 8 is a schematic diagram showing an example of performing crystallization of a pixel portion.
FIG. 9 is a schematic diagram showing another example in which the peripheral circuit portion and the pixel portion are crystallized.
FIG. 10 is a diagram showing an example of an apparatus for synthesizing laser light.
FIG. 11 is a diagram showing an example of a beam spot of a synthesized laser beam.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Liquid crystal panel 12 ... Substrate 14 ... Substrate 16 ... Liquid crystal 18 ... Pixel part 20 ... Peripheral circuit part 22 ... Pixel 24 ... Glass substrate 26 ... XY stage 28 ... Laser light 30 ... Laser apparatus 32 ... Laser light source 34 ... Laser light source 36 ... mirror 38 ... lens 40 ... lens 42 ... support adjustment mechanism 44 ... support adjustment mechanism

Claims (4)

A method of manufacturing a substrate of a display device having a plurality of panel regions, each panel region including a pixel portion and a peripheral circuit portion around the pixel portion,
Forming an amorphous semiconductor layer on the substrate;
A step of simultaneously crystallizing the amorphous semiconductor layer formed on the substrate with a plurality of strong energy lights,
The crystallization step includes
Irradiating the first strong energy light to the first side portion of the first panel region and the other strong energy light to the second side portion of the other panel region simultaneously among the plurality of strong energy lights ; A first step of scanning ;
The first strong energy light is applied to a third side portion different from the first side portion in the first panel region, and the other strong energy light is supplied to the second side portion in the other panel region. And a second step of simultaneously irradiating and scanning a fourth side portion different from
The first side part and the second side part are respectively disposed at the relatively same position,
The third side portion and the fourth side portion are respectively disposed at the relatively same position ,
The scanning of a plurality of strong energy lights in any one of the scanning of the plurality of strong energy lights in the first step and the scanning of the plurality of strong energy lights in the second step is continued. Which is done across the panel area,
A peripheral circuit portion of one panel area of the plurality of strong energy light, a manufacturing method of a substrate for display device characterized by crystallizing in only one strong energy light.   2. The method for manufacturing a substrate of a display device according to claim 1, wherein spot light of a continuous wave laser is used as the plurality of strong energy lights.   2. The method of manufacturing a substrate of a display device according to claim 1, wherein the high-energy light is a single spot light by combining continuous wave laser light.   4. The method for manufacturing a substrate of a display device according to claim 2, wherein the spot light is spot light having the same shape with respect to the scanning direction.

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