JP4268700B2 - Excimer laser annealing apparatus, method for manufacturing polycrystalline thin film transistor, and method for manufacturing liquid crystal display element - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an excimer laser annealing apparatus that irradiates an excimer laser beam to amorphous silicon in order to obtain amorphous silicon by annealing amorphous silicon, and a semiconductor layer formed by annealing the polycrystalline silicon formed by the excimer laser annealing apparatus. And a method for manufacturing a liquid crystal display device using the polycrystalline thin film transistor thus obtained.
[0002]
[Prior art]
In recent years, as a switching element of a high-definition liquid crystal display element, since it has high mobility and high performance including driving of the liquid crystal display element is possible, a polycrystalline thin film transistor (hereinafter referred to as p) -It is abbreviated as Si TFT). In general, polycrystalline silicon is formed by a laser annealing method in which amorphous silicon is irradiated with a laser beam to be polycrystalline.
[0003]
In such a laser annealing method, as the area of the array substrate on which the p-Si TFT for forming a liquid crystal display element is increased is further increased, the length of the laser beam is required. However, in the case where the length of the laser beam is shorter than the width of the display area of the array substrate and the scanning width of the array substrate cannot be covered with the length of one line of the laser beam, regardless of the length of the laser beam, FIG. As shown in FIG. 2, the display area of the array substrate 5 is divided into P1 and P2, and the divided areas are scanned by the laser beam L. Therefore, the laser beam L is superimposed on the array substrate 5. Irradiated region Q is generated, and this overlapped irradiation region Q has different characteristics from other regions and the degree of surface unevenness. When a liquid crystal display element is manufactured using such an array substrate, display is performed. There was a problem that the quality was lowered and the production yield was lowered.
[0004]
Therefore, in order to obtain polycrystalline silicon that is as good as possible by annealing, conventionally, an excimer laser annealing apparatus having a long laser beam line length is used to anneal amorphous silicon.
[0005]
That is, the commercially available excimer laser annealing apparatus 1 shown in FIG. 6 cuts both ends of an excimer laser beam 3 having a predetermined length that has been emitted from a light source and passed through the imaging lens 2 with a long slit 4, and then is applied to the window frame 6. Amorphous silicon on the array substrate 11 that is incident on the annealing chamber 8 through the supported annealing window 7 and is irradiated onto the stage 10 and supported so as to be scan-movable by the stage 10 is converted into one line of excimer laser beam. 3 was annealed and polycrystallized.
[0006]
[Problems to be solved by the invention]
However, even with an excimer laser beam having a long line length, the line length is limited. However, a liquid crystal display element having a large size of 13.3 type (203 mm × 270 mm) is mainly used due to a demand for further enlargement. It is becoming. In order to obtain a drive circuit type array substrate, 210 × 280 polycrystalline silicon is required. On the other hand, in the current commercially available excimer laser annealing apparatus, the line length of the excimer laser beam is limited to about 200 mm at the maximum. Therefore, even if an excimer laser beam is used, to anneal an array substrate of a larger 13.3 type liquid crystal display element, the entire area cannot be covered with a single line of excimer laser beam, and the array substrate is divided into two regions. As a result, the laser beam must be annealed, and as a result, a laser beam overlap irradiation region having different characteristics from the surroundings is generated, resulting in a problem that the display quality is deteriorated.
[0007]
For this reason, development has been made to increase the length of the excimer laser beam of a commercially available excimer laser annealing apparatus as much as possible so that it can be applied to a larger liquid crystal display element of at least 13.3 type. There are many problems that require much time for development, such as the need to increase the output of the laser and the development of a more optimal optical system.
[0008]
On the other hand, in the above-described commercially available excimer laser annealing apparatus 1, the inner periphery 6 a of the window frame 6 that supports the annealing window 7 that makes the excimer laser beam 3 incident on the stage 10 in the annealing chamber 8 has the traveling direction of the excimer laser beam. It is formed in parallel to.
[0009]
On the other hand, since the excimer laser beam 3 enters the annealing chamber 8 while spreading from the light source, the excimer laser beam 3 incident on the dotted line region [R] is reflected on the inner periphery 6 a of the window frame 6. When this reflected beam is irradiated onto the array substrate 1, unevenness is generated in the irradiation intensity distribution of the excimer laser beam 3 on the array substrate 1, and the beam profile is not a top flat shape, so that uniform annealing can be obtained. Therefore, there has been a problem that uniform crystallization of polycrystalline silicon cannot be obtained.
[0010]
For this reason, conventionally, the position of the long slit 4 is narrowed or the annealer is narrowed so that the width of the excimer laser beam 3 is narrowed so that both ends of the excimer laser beam 3 do not touch the window frame 6 when entering the annealing chamber 8. A slit is formed on the light source side of the window 7, and as a result, the length of the excimer laser beam 3 irradiated to the array substrate 1 is unnecessarily increased, and the advantage of the excimer laser annealing apparatus is reduced. I couldn't make full use of it.
[0011]
The present invention eliminates the above-described problems. When an excimer laser beam from a light source is incident on an annealing chamber through an annealing window, the length of the excimer laser beam is reduced without unnecessarily shortening the beam length. By taking full advantage of the excimer laser beam, it is possible to irradiate a larger array substrate with an excimer laser beam over the entire surface with uniform intensity, and to achieve uniform drive characteristics of the polycrystalline thin film transistor device. An object of the present invention is to provide an excimer laser annealing apparatus, a polycrystalline thin film transistor device manufacturing method, and a liquid crystal display element manufacturing method capable of obtaining a liquid crystal display element with high display quality.
[0012]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention provides an excimer laser annealing apparatus for irradiating amorphous silicon deposited on an insulating substrate with an excimer laser beam to polycrystallize the amorphous silicon, and a supporting means for supporting the insulating substrate. A housing that accommodates the support means in a scannable manner; a light source that emits an excimer laser beam to the support means that is scanned and moved in the housing from outside the housing; and the excimer formed in the housing. An opening for entering the excimer laser beam emitted from the laser beam emitting means into the housing;
A window frame that supports the peripheral edge of the opening and is inclined in the same direction with respect to the traveling direction of the excimer laser beam that passes at least part of the inner periphery in the vicinity of the opening. is there.
[0013]
With the above configuration, the present invention does not cause the excimer laser beam to be reflected by the window frame at the time of incidence from the window frame into the housing, and the irradiation intensity is uniform and the excimer laser beam having a longer and longer size is used. This enables uniform annealing of the array substrate.
[0014]
Further, since the present invention is to solve the above problems, in the method for producing polycrystalline thin film transistor for forming a thin film transistor data polycrystalline silicon formed by irradiating the excimer laser beam to the amorphous silicon is deposited on an insulating substrate as a semiconductor layer, wherein the step of depositing said amorphous silicon on an insulating substrate, wherein the supporting means for supporting the insulating substrate in the housing for scanning movably accommodated, the excimer laser beam at least part of the inner periphery passes near this part The excimer laser beam is incident through an opening having a window frame that is inclined in the same direction with respect to the direction of travel of the excimer laser beam from the light source that emits light to the polycrystalline silicon. And crystallization step.
[0015]
In the present invention, uniform polycrystalline silicon can be obtained on a larger array substrate by irradiation with a longer excimer laser beam having a uniform irradiation intensity, and thus a p-Si TFT having uniform driving characteristics. Is obtained in a large area.
[0016]
Further, since the present invention is to solve the above problems, it is manually driven to a thin film transistor motor which is formed a polycrystalline silicon formed by irradiating the excimer laser beam to the amorphous silicon is deposited on the first insulating substrate as a semiconductor layer An array substrate having a pixel electrode; a counter substrate having a counter electrode on a second insulating substrate and disposed opposite the array substrate; and a liquid crystal composition sealed between the array substrate and the counter substrate; In a method for manufacturing a liquid crystal display device comprising: a step of depositing the amorphous silicon on the first insulating substrate; and a supporting means for supporting the first insulating substrate in a housing that is slidably movable. at least partially inclined in the same direction with respect to the traveling direction of the outside of the excimer laser beam from the light source emitting an excimer laser beam passing near this part of the peripheral Enters the excimer laser beam through an opening having a window frame formed by the steps of crystallizing the amorphous silicon into polycrystalline silicon, it is to implement.
[0017]
According to the above configuration, the present invention has a uniform p-type driving characteristic composed of uniform polycrystalline silicon formed on a larger array substrate by irradiation with a longer excimer laser beam having a uniform irradiation intensity. A liquid crystal display element having a larger size and good display quality, which uses a Si TFT, is obtained.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described below with reference to the embodiments shown in FIGS. Reference numeral 12 denotes a 13.3 type (210 mm × 280 mm) liquid crystal display element integrated with a drive circuit, and an alignment film 18 a is formed in the gap between the array substrate 16 that drives the pixel electrode 28 by the p-Si TFT 13 and the counter substrate 17. The liquid crystal composition 20 is sealed through 18b.
[0019]
In the array substrate 16, a semiconductor layer 23 having an active layer 23 a made of polycrystalline silicon, a drain region 23 b, and a source region 23 c is patterned on the first insulating substrate 21 through an undercoat layer 22. A gate electrode 26 is formed on the semiconductor layer 23 via a gate insulating film 24. Further, the pixel electrode 28 is formed via the interlayer insulating film 27, the pixel electrode 28 and the source region 23 c are connected by the source electrode 30, and the drain region 23 b and the signal line (not shown) are connected by the drain electrode 31. Reference numeral 32 denotes a protective film. The counter substrate 17 has a counter electrode 34 on a second insulating substrate 33.
[0020]
Next, an excimer laser annealing apparatus for laser annealing amorphous silicon in order to obtain a polycrystalline silicon semiconductor layer 23 on the first insulating substrate 21 will be described. FIG. 2 is a schematic configuration diagram of the excimer laser annealing apparatus 36 viewed from the long axis direction of the excimer laser beam 37. The excimer laser annealing device 36 forms an image of an excimer laser beam 37 emitted from a light source (not shown) with an imaging lens 38, cuts both ends with a long slit 40, and within the annealing chamber 41, Irradiated onto a stage 42 that scans and moves in a direction perpendicular to the major axis direction of the excimer laser beam 37.
[0021]
That is, an annealing window 44 supported by the window frame 43 is formed above the annealing chamber 41, and the excimer laser beam 37 whose both ends are cut by the long slit 40 is passed through the annealing chamber 44 through the annealing chamber 44. 41 is incident. Out of the peripheral edge of the window frame 43 that supports the annealing window 44, a peripheral edge portion 43a that faces the long axis of the excimer laser beam 37 is cut obliquely. For this reason, the excimer laser beam 37 does not hit the window frame 43 even if it is incident on the annealing window 44 with a full width of the window frame 43 while spreading from a light source (not shown). Therefore, the excimer laser beam 37 irradiated on the stage 42 can obtain a uniform intensity distribution without unevenness without cutting both ends more than necessary by the long slit 40.
[0022]
When the intensity distribution of the long axis of the excimer laser beam 37 on the stage 42 by the excimer laser annealing apparatus 36 was examined, as shown in FIG. 3, it may have a top flat beam profile over a length of 220 mm. found.
[0023]
Next, a method for forming the semiconductor layer 23 made of polycrystalline silicon on the array substrate 16 by the excimer laser annealing apparatus 36 will be described.
[0024]
First, an undercoat layer 22 formed by forming a silicon nitride (SiNx) film by 50 nm and a silicon oxide (SiOx) film by 100 nm is formed on a glass substrate 47 having a size of 400 mm × 500 mm by plasma CVD, and then by plasma CVD. Amorphous silicon is deposited to a thickness of 50 nm. Thereafter, heat treatment is performed at 500 ° C. for 1 hour in a nitrogen atmosphere to reduce the hydrogen concentration in the film. At this time, when the film thickness of the amorphous silicon was obtained by the spectroscopic ellipso method, the actual film thickness was 51 nm.
[0025]
Thereafter, the glass substrate 47 is placed on the stage 42 of the excimer laser annealing apparatus 36, and the stage 42 is scanned and moved at a speed of 0.6 mm / s in the direction perpendicular to the long axis of the excimer laser beam 37 as shown in FIG. Similarly, first, the amorphous silicon in the first region [A] on one side is annealed by the excimer laser beam 37. An excimer laser is oscillated at 300 Hz with a light source (not shown), the irradiation size of the excimer laser beam 37 is a linear beam of 220 mm × 0.4 mm, and the irradiation energy density on the glass substrate 47 is 300 mJ / cm 2. The overlap ratio at the time of scanning in the direction perpendicular to the long axis direction of the excimer laser beam was set to be 95%.
[0026]
When the annealing scan of the first region [A] of the glass substrate 47 is finished and polycrystalline silicon is formed, the amorphous silicon of the remaining second region [B] is annealed in the same manner, and both regions [A], [A, B] are annealed with the width of one line of the excimer laser beam 37, and are polycrystallized to form polycrystalline silicon. Next, the glass substrate 47 is taken out from the stage 42, and the p-Si TFT 13 and the pixel electrode 28 having polycrystalline silicon as the semiconductor layer 23 are formed in both regions [A] and [B] of the glass substrate 47 by using a photolithography technique. The array substrate 16 is formed in the first and second regions [A] and [B] on the glass substrate 47, respectively.
[0027]
Thereafter, the glass substrate 47 having the two array substrates 16 is cut out, and the glass substrate (not shown) having the counter substrate 17 is fixed with a sealant (not shown), and the liquid crystal cell is fixed. After the formation, the liquid crystal composition 20 is sealed in the gap to complete two 13.3 type liquid crystal display elements 12.
[0028]
With such a configuration, the same commercially available apparatus as before is used, and the peripheral edge portion 43a of the window frame 43 supporting the annealing window 44 of the excimer laser annealing apparatus 36 is cut obliquely, so that the window frame 43 of the excimer laser beam 37 is obtained. By preventing reflection, the excimer laser beam 37 can be incident on the annealing chamber 41 with the full width of the window frame 43, and the excimer laser beam can be made larger than before without increasing the output of the excimer laser or changing the optical system. The excimer laser beam 37 having a top flat beam profile over a width of 220 mm can be obtained. Therefore, even with a large 13.3 type drive circuit integrated array substrate 16, the entire length of the annealing width can be covered with a one-line excimer laser beam 37 during annealing, and a 13.3 type large drive circuit is provided. Even with the integrated array substrate 16, it is possible to uniformly anneal without generating a laser beam overlap irradiation region, and to easily form polycrystalline silicon having uniform characteristics applicable to the large liquid crystal display element 12. Become.
[0029]
By using polycrystalline silicon that is uniformly annealed by the excimer laser beam 37 having a long line length and is uniformly crystallized by such an excimer laser annealing apparatus 36 as a semiconductor layer, a TFT showing high mobility can be obtained. Since it can be obtained uniformly in a large area, by using such a TFT, a liquid crystal display element having a large size of 13.3 type and uniform display characteristics can be easily obtained, the production yield can be improved, and a high display can be obtained. A liquid crystal display element having high quality can be manufactured.
[0030]
The present invention is not limited to the above-described embodiment, and can be changed within a range that does not change the spirit thereof. For example, the inclination angle of the window frame is within a range that does not cause excimer laser beam reflection. It is not limited. Further, the output and frequency of the excimer laser beam are not limited.
[0031]
【The invention's effect】
As described above, according to the present invention, the excimer laser beam can be obtained by simply cutting the inner periphery of the window frame supporting the annealing window obliquely without increasing the output of the excimer laser or improving the performance of the optical system. Reflection on the window frame is prevented, and the line length of the excimer laser annealing apparatus can be easily increased. Therefore, the annealing width by the excimer laser beam of one line length can be increased, and the annealing width of the amorphous silicon on the array substrate can be covered by the excimer laser beam of one line length even in a large area. Therefore, uniform annealing can be performed over the entire surface, and uniform polycrystalline silicon can be easily obtained. A high mobility TFT using this homogeneous polycrystalline silicon as a semiconductor layer can be obtained uniformly in a large area, and as a result, a liquid crystal display element having a large size of 13.3 type, uniform display characteristics and high display quality can be obtained. It can be easily manufactured without causing a decrease in yield.
[Brief description of the drawings]
FIG. 1 is a partial schematic cross-sectional view showing a liquid crystal display element in an embodiment of the present invention.
FIG. 2 is a schematic configuration diagram of an excimer laser annealing apparatus according to an embodiment of the present invention as viewed from the long axis direction.
FIG. 3 is a graph showing an intensity distribution of a long axis of an excimer laser beam on a stage in the excimer laser annealing apparatus according to the embodiment of the present invention.
FIG. 4 is an explanatory diagram showing an annealing process of a glass substrate by an excimer laser annealing apparatus in an embodiment of the present invention.
FIG. 5 is an explanatory view showing a state in which a conventional large array substrate is divided and laser annealed.
FIG. 6 is a schematic configuration diagram showing a conventional excimer laser annealing apparatus.
[Explanation of symbols]
12 ... Liquid crystal display element 13 ... p-Si TFT
16 ... Array substrate 17 ... Counter substrate 20 ... Liquid crystal composition 23 ... Semiconductor layer 28 ... Pixel electrode 36 ... Excimer laser annealing device 37 ... Excimer laser beam 41 ... Annealing chamber 42 ... Stage 43 ... Window frame 43a ... Peripheral portion 47 ... Glass substrate

Claims (9)

In an excimer laser annealing apparatus for irradiating an amorphous silicon deposited on an insulating substrate with an excimer laser beam to polycrystallize the amorphous silicon,
Support means for supporting the insulating substrate;
A housing for storing the support means in a scannable manner;
A light source that emits an excimer laser beam to the support means that is scanned and moved in the housing from the outside of the housing;
An opening that is formed in the casing and that enters the excimer laser beam emitted from the light source into the casing;
A window frame that supports the periphery of the opening and is inclined in the same direction with respect to the traveling direction to the outside of the excimer laser beam in which at least a part of the inner periphery passes in the vicinity of the part ;
An excimer laser annealing apparatus characterized by comprising: 2. The excimer laser annealing apparatus according to claim 1, wherein at least a part of an inner periphery of the window frame is inclined in a direction that is wider than an incident angle at the periphery of the opening of the excimer laser beam. Any wherein an excimer laser beam cross-sectional shape is approximately rectangular, at least a portion of the inner periphery of the window frame, according to claim 1 or claim 2, characterized in that a portion facing the longitudinal axis of the excimer laser beam An excimer laser annealing apparatus according to claim 1. The method of manufacturing a polycrystalline thin film transistor for forming a thin film transistor data polycrystalline silicon formed by irradiating the excimer laser beam to the amorphous silicon is deposited on an insulating substrate as a semiconductor layer,
Depositing the amorphous silicon on the insulating substrate;
Progression of the supporting means for supporting the insulating substrate in the housing for scanning movably housed, at least a portion of the inner periphery to the outside of the excimer laser beam from the light source emitting an excimer laser beam passing through the vicinity of this part Irradiating the excimer laser beam through an opening having a window frame inclined in the same direction with respect to the direction, and crystallizing the amorphous silicon into polycrystalline silicon;
A method for producing a polycrystalline thin film transistor, comprising: 5. The method of manufacturing a polycrystalline thin film transistor according to claim 4, wherein at least a part of the inner periphery of the window frame is inclined in a direction that is wider than the incident angle of the excimer laser beam at the periphery of the opening. Any wherein an excimer laser beam cross-sectional shape is approximately rectangular, at least a portion of the inner periphery of the window frame, according to claim 4 or claim 5, characterized in that a portion facing the longitudinal axis of the excimer laser beam A method for producing a polycrystalline thin film transistor according to claim 1. An array substrate having a first pixel electrode which is manually driven to a thin film transistor motor which is formed in the amorphous silicon is deposited on an insulating substrate a polycrystalline silicon formed by irradiating an excimer laser beam as the semiconductor layer, the second In a method for manufacturing a liquid crystal display element, comprising: a counter substrate having a counter electrode on an insulating substrate and disposed opposite to the array substrate; and a liquid crystal composition sealed between the array substrate and the counter substrate.
Depositing the amorphous silicon on the first insulating substrate;
Outside the excimer laser beam from a light source that emits an excimer laser beam in which at least a part of the inner circumference passes in the vicinity of a part of the inside of the casing that accommodates the support means for supporting the first insulating substrate so as to be movable. Injecting the excimer laser beam through an opening having a window frame inclined in the same direction with respect to the traveling direction to crystallize the amorphous silicon into polycrystalline silicon;
A method for producing a liquid crystal display element, comprising: 8. The method of manufacturing a liquid crystal display element according to claim 7, wherein at least a part of the inner periphery of the window frame is inclined in a direction that is wider than the incident angle of the excimer laser beam at the periphery of the opening. Any wherein an excimer laser beam cross-sectional shape is approximately rectangular, at least a portion of the inner periphery of the window frame, according to claim 7 or claim 8, characterized in that a portion facing the longitudinal axis of the excimer laser beam A method for producing a liquid crystal display element according to claim 1.

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