JPH11288898A - Excimer laser annealing apparatus, manufacture of polycrystalline thin-film transistor device, and manufacture of liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a liquid crystal display device in display quality and production yield by a method, wherein an excimer laser beam of a conventional excimer laser annealing device is elongated in line length, without having to improve the excimer laser in output or optical systems in performance, and an amorphous silicon layer on a larger array board is turned polycrystalline uniformly. SOLUTION: A peripheral edge 43a of a window frame 43, which supports an annealing window 44 of an excimer laser annealing apparatus 36 is cut obliquely to prevent an excimer laser beam 37 from being reflected from the window frame 43, whereby the excimer laser beam 37 can be expanded in the direction of its major axis as large as the width of the window frame 43, and the excimer laser beam 37 can be elongated in line width.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an excimer laser annealing apparatus for irradiating amorphous silicon with an excimer laser beam in order to anneal amorphous silicon to obtain polycrystalline silicon, and an annealing method using the excimer laser annealing apparatus. The present invention relates to a method of manufacturing a polycrystalline thin film transistor using polycrystalline silicon as a semiconductor layer and a method of manufacturing a liquid crystal display element using the polycrystalline thin film transistor thus obtained.

[0002]

2. Description of the Related Art In recent years, as a switching element of a high-definition liquid crystal display element, a high mobility and high performance including driving of the liquid crystal display element can be achieved. Crystal thin film transistor (hereinafter p-
Abbreviated as SiTFT. ) Is being put to practical use.
Generally, polycrystalline silicon is formed by a laser annealing method in which amorphous silicon is irradiated with a laser beam to be polycrystallized.

In such a laser annealing method, a longer laser beam is required as the area of an array substrate on which a p-Si TFT is formed is increased in order to respond to an increase in the size of a liquid crystal display element. However, regardless of the length of the laser beam, if the length of the laser beam is shorter than the width of the display area of the array substrate and the length of one line of the laser beam cannot cover the scanning width of the array substrate, FIG. As shown in (1), the display area of the array substrate 5 is divided into P1 and P2, and scanning is performed by the laser beam L for each of the divided areas.
This results in a region Q to be irradiated in a superimposed manner. In the superimposed irradiation region Q, the characteristics are different from those of the other regions and the degree of surface irregularities is different. Therefore, a liquid crystal display element is manufactured using such an array substrate. Then, there is a problem that the display quality is lowered and the production yield is lowered.

Therefore, in order to obtain polycrystalline silicon as good as possible by annealing, conventionally, an excimer laser annealing apparatus having a long laser beam line length has been used to anneal amorphous silicon.

That is, a commercially available excimer laser annealing apparatus 1 shown in FIG. 6 cuts both ends of an excimer laser beam 3 having a predetermined length emitted from a light source and passed through an imaging lens 2 by a long slit 4 and then a window. The light enters the annealing chamber 8 through the annealing window 7 supported by the frame 6, and is irradiated onto the stage 10. The amorphous silicon on the array substrate 11 supported by the stage 10 so as to be movable by scanning is converted into one line. Annealing with an excimer laser beam 3 resulted in polycrystallization.

[0006]

However, even with an excimer laser beam having a long line length, the line length has a limit. On the other hand, a liquid crystal display element is required to be larger in size by a 13.3-inch (203 mm) type. (× 270 mm) is becoming mainstream. 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 a maximum of about 200 mm. Therefore, even if an excimer laser beam is used, the larger one
In order to anneal an array substrate of a 3.3-type liquid crystal display device, one line of an excimer laser beam cannot cover the entire area, and the array substrate must be divided into two regions and annealed. There has been still a problem that a laser beam having different characteristics is overlapped and an overlapping irradiation region is generated, thereby deteriorating display quality.

For this reason, developments have been made to increase the length of the excimer laser beam of a commercially available excimer laser annealing apparatus, so as to be applicable to at least a 13.3 type larger liquid crystal display device. However, there are many problems that require a long time for development, such as an increase in the output of an excimer laser and the development of a more optimal optical system.

On the other hand, in the above-mentioned commercially available excimer laser annealing apparatus 1, the inner periphery 6a of a window frame 6 supporting an anneal window 7 into which an excimer laser beam 3 is incident on a stage 10 in an annealing chamber 8 is formed by an excimer laser beam. Is formed in parallel to the traveling direction of.

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 in the dotted line region [R] is reflected by the inner periphery 6 a of the window frame 6. Is generated. When this reflected beam is applied to the array substrate 1, the irradiation intensity distribution of the excimer laser beam 3 on the array substrate 1 becomes uneven, so that the beam profile no longer has a top flat shape, and uniform annealing can be obtained. Therefore, there has been a problem that uniform crystallization of polycrystalline silicon cannot be obtained.

For this reason, conventionally, at the time of incidence on the annealing chamber 8, both ends of the excimer laser beam 3 do not touch the window frame 6 so that the width of the excimer laser beam 3 is reduced so that the position of the long slit 4 is narrowed. Alternatively, a slit is formed on the light source side with respect to the annealing window 7, and as a result, the length of the excimer laser beam 3 applied to the array substrate 1 is lengthened more than necessary, and an excimer laser annealing apparatus is used. Was unable to make the most of the benefits of

SUMMARY OF THE INVENTION The present invention has been made to solve the above problem, and when excimer laser beams from a light source enter an annealing chamber through an annealing window, the beam length of the excimer laser beams can be reduced without being shortened more than necessary. By taking full advantage of the excimer laser beam, which is a long laser beam, it is possible to irradiate the excimer laser beam with uniform intensity over the entire surface even on a larger array substrate, and thus to make the driving characteristics of the polycrystalline thin film transistor device uniform. Accordingly, an object of the present invention is to provide an excimer laser annealing apparatus, a method for manufacturing a polycrystalline thin film transistor device, and a method for manufacturing a liquid crystal display element, which can obtain a liquid crystal display element with high display quality.

[0012]

According to the present invention, there is provided an excimer laser annealing apparatus for irradiating an amorphous silicon deposited on an array substrate with an excimer laser beam to polycrystallize the amorphous silicon. Support means for supporting the array substrate, a housing for accommodating the support means in a scanable manner, and a light source that emits an excimer laser beam to the support means that is scanned and moved within the housing from outside the housing, An opening formed in the housing, for receiving the excimer laser beam emitted from the excimer laser beam emitting means into the housing, and supporting the periphery of the opening; at least a part of the inner circumference is the excimer laser; A window frame inclined with respect to the traveling direction of the beam.

According to the present invention, the excimer laser beam is not reflected by the window frame at the time of incidence from the window frame into the housing, and the irradiation intensity is uniform and longer. This enables uniform annealing of a larger array substrate.

According to another aspect of the present invention, there is provided a method of manufacturing a polycrystalline thin-film transistor in which a thin-film transistor device is formed using polycrystalline silicon as a semiconductor layer by irradiating amorphous silicon deposited on an array substrate with an excimer laser beam. In the step of depositing the amorphous silicon on the array substrate, and in a housing accommodating scanning means to support the array substrate, at least a part of the inner circumference from a light source that emits an excimer laser beam Irradiating the excimer laser beam through an opening having a window frame inclined with respect to the traveling direction of the excimer laser beam to crystallize the amorphous silicon into polycrystalline silicon. It is.

According to the present invention, a 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 a uniform driving characteristic. p-Si TFT
Is obtained in a large area.

Further, the present invention provides a first method for solving the above problems.
An array substrate having pixel electrodes driven by a thin film transistor device formed of polycrystalline silicon as a semiconductor layer by irradiating an excimer laser beam to amorphous silicon deposited on an array substrate, and on a second array substrate A method of manufacturing a liquid crystal display element, comprising: a counter substrate having a counter electrode and disposed opposite to the array substrate; and a liquid crystal composition sealed between the array substrate and the counter substrate. A step of depositing the amorphous silicon on an array substrate, and a housing housing the support means for supporting the first array substrate in a scan-movable manner.
At least a part of the inner periphery is incident on the excimer laser beam through an opening having a window frame inclined with respect to the traveling direction of the excimer laser beam from a light source that emits an excimer laser beam, and the amorphous silicon And crystallizing the polycrystalline silicon into polycrystalline silicon.

According to the present invention, with the above-described structure, uniform irradiation characteristics can be obtained by uniform polycrystalline silicon formed on a larger array substrate by irradiation with a longer excimer laser beam having a uniform irradiation intensity. Na p-Si TFT
To obtain a larger liquid crystal display element having good display quality.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to an embodiment shown in FIGS. 12 is 13.3 type (2
(10 mm × 280 mm) is a liquid crystal display element integrated with a driving circuit, and a liquid crystal composition is provided in the gap between the array substrate 16 for driving the pixel electrode 28 by the p-Si TFT 13 and the counter substrate 17 via the alignment films 18 a and 18 b. 20 is enclosed.

In the array substrate 16, a semiconductor layer 23 having an active layer 23a made of polycrystalline silicon, a drain region 23b, and a source region 23c is pattern-formed on a first insulating substrate 21 via an undercoat layer 22. A gate electrode 26 is formed on the semiconductor layer 23 with a gate insulating film 24 interposed. Further, the pixel electrode 2 is interposed via the interlayer insulating film 27.
8 are formed, the pixel electrode 28 and the source region 23c are connected by the source electrode 30, and the drain region 23b and the signal line (not shown) are connected by the drain electrode 31. 32 is a protective film. The opposing substrate 17 includes a second
The counter electrode 34 is provided on the insulating substrate 33 of FIG.

Next, an excimer laser annealing apparatus for laser annealing amorphous silicon to obtain a polycrystalline silicon semiconductor layer 23 on the first insulating substrate 21 will be described. FIG. 2 shows an excimer laser annealing apparatus 3
6 is a schematic configuration diagram of the excimer laser beam 6 viewed from the major axis direction. The excimer laser annealing device 36 is provided with an excimer laser beam 3 emitted from a light source (not shown).
7 is imaged by an imaging lens 38, both ends are cut by a long slit 40, and is placed on a stage 42 that scans and moves in an annealing chamber 41 in a direction perpendicular to the long axis direction of an excimer laser beam 37. Irradiated.

That is, an anneal window 44 supported by a 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, passes through the anneal window 44. Then, the light enters the annealing chamber 41 through the intermediary.
And, of the peripheral edge of the window frame 43 supporting the annealer window 44, a peripheral edge portion 43a facing the major axis of the excimer laser beam 37 is cut obliquely. For this reason, the excimer laser beam 37 spreads from a light source (not shown) and has a width that
4 does not hit the window frame 43. Therefore,
Excimer laser beam 37 irradiated onto stage 42
Can obtain a uniform intensity distribution without irregularities without cutting both ends more than necessary by the long slit 40.

When the intensity distribution of the major axis of the excimer laser beam 37 on the stage 42 by the excimer laser annealing device 36 was examined, as shown in FIG.
over m, it was found to have a top-flat beam profile.

Next, the semiconductor layer 2 made of polycrystalline silicon on the array substrate 16 by the excimer laser annealing device 36
The method of forming No. 3 will be described.

First, a silicon nitride (SiNx) film having a thickness of 50 nm and a silicon oxide (SiOx) film were formed on a glass substrate 47 having a size of 400 mm × 500 mm by a plasma CVD method.
An undercoat layer 22 having a thickness of 100 nm is formed, and then amorphous silicon is formed to a thickness of 50 nm by a plasma CVD method. After that, 500 under nitrogen atmosphere
A heat treatment is performed at 1 ° C. for 1 hour to reduce the hydrogen concentration in the film. At this time, when the film thickness of the amorphous silicon was determined by the spectral ellipsometry, the actual film thickness was 51 nm.

Thereafter, the glass substrate 47 is placed on the stage 42 of the excimer laser annealing device 36,
2 in the direction perpendicular to the long axis of the excimer laser beam 37.
While scanning and moving at a speed of 6 mm / s, as shown in FIG. 4, the amorphous silicon in the first region [A] on one side is first annealed with an excimer laser beam 37. An excimer laser is oscillated at 300 Hz by a light source (not shown), and the irradiation size of the excimer laser beam 37 is 22
A linear beam of 0 mm × 0.4 mm is formed on the glass substrate 47.
The irradiation energy density was set to 300 mJ / cm @ 2, and the overlap ratio during scanning in the direction perpendicular to the long axis direction of the excimer laser beam was set to 95%.

After the annealing scan of the first region [A] of the glass substrate 47 is completed and the polycrystalline silicon is formed, the amorphous silicon of the remaining second region [B] is similarly annealed to form both regions [A]. ] And [B] are both annealed with the width of one line of the excimer laser beam 37, and polycrystallized to form polycrystalline silicon. Next, the glass substrate 47 is taken out of the stage 42, and the p-Si TFT 13 using the polycrystalline silicon as the semiconductor layer 23 and the pixel electrode 28 are placed in both regions [A] and [B] of the glass substrate 47 by using a photolithography technique. The array substrate 16 is formed in each of the first and second regions [A] and [B] on the glass substrate 47.

Thereafter, a glass substrate 47 having two array substrates 16 is cut out, and a glass substrate (not shown) having the opposite substrate 17 is sealed with a sealing agent (not shown).
After forming a liquid crystal cell, the liquid crystal composition 20 is sealed in the gap to complete two 13.3 type liquid crystal display elements 12.

With this configuration, the same peripheral device 43 as that of the excimer laser beam 37 is cut off obliquely by using the same commercially available device as in the prior art, by cutting the peripheral portion 43 a of the window frame 43 supporting the annealer window 44 of the excimer laser annealing device 36. By preventing the reflection at the window frame 43, the excimer laser beam 37
Can be incident on the annealing chamber 41 with a width that is the full width of the window frame 43, the line length of the excimer laser beam 37 can be made longer than before, without increasing the output of the excimer laser or changing the optical system, and the top flat over a width of 220 mm Excimer laser beam 3 having a beam profile of
7 is obtained. Therefore, even in the case of the large 13.3 type drive circuit integrated type array substrate 16, the entire width of the annealing width can be covered by the excimer laser beam 37 having one line length at the time of annealing. Even if the integrated array substrate 16 is used, annealing can be performed uniformly without generating a laser beam overlapping irradiation region, and polycrystalline silicon having uniform characteristics applicable to the large liquid crystal display element 12 can be easily formed. Become.

The excimer laser annealing apparatus 36 uses polycrystalline silicon, which is uniformly annealed by the excimer laser beam 37 having a long line length and is uniformly crystallized, as a semiconductor layer, thereby achieving high mobility. Since the TFT shown 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, and the production yield can be improved. Thus, a liquid crystal display element having high display quality can be manufactured.

The present invention is not limited to the above-described embodiment, but can be changed without departing from the spirit of the invention. For example, the inclination angle of the window frame is limited to the range where the reflection of the excimer laser beam does not occur. It is not limited if it is. The output and frequency of the excimer laser beam are not limited.

[0031]

As described above, according to the present invention, the inner periphery of the window frame supporting the annealer window can be simply cut obliquely without increasing the output of the excimer laser or improving the performance of the optical system. In addition, the reflection of the excimer laser beam on the window frame can be prevented, and the line length of the excimer laser annealing apparatus can be easily increased. Therefore, the annealing width by the one-line excimer laser beam can be increased, and even if the area is large, the annealing width of the amorphous silicon on the array substrate can be covered by the one-line excimer laser beam. No overlapping irradiation area is generated, uniform annealing can be performed over the entire surface, and a uniform polycrystalline silicon can be easily obtained. A high-mobility TFT using this homogeneous polycrystalline silicon as a semiconductor layer and having a high mobility can be obtained uniformly in a large area. As a result, a large-sized 13.3 type liquid crystal display element having uniform display characteristics and high display quality can be obtained. It can be easily manufactured without lowering the yield.

[Brief description of the drawings]

FIG. 1 is a partial schematic cross-sectional view showing a liquid crystal display device according to 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 a long axis direction.

FIG. 3 is a graph showing an intensity distribution of a major axis of an excimer laser beam on a stage in an excimer laser annealing apparatus according to an embodiment of the present invention.

FIG. 4 is an explanatory view showing a step of annealing a glass substrate by an excimer laser annealing apparatus according to the embodiment of the present invention.

FIG. 5 is an explanatory diagram showing a state in which a conventional large array substrate is divided and subjected to laser annealing.

FIG. 6 is a schematic configuration diagram showing a conventional excimer laser annealing apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 12 ... Liquid crystal display element 13 ... p-SiTFT 16 ... Array substrate 17 ... Opposite 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 part 47 ... glass substrate

Continuation of the front page (72) Inventor Takashi Fujimura 1-9-2, Hara-cho, Fukaya-shi, Saitama Prefecture Toshiba Fukaya Electronics Factory Co., Ltd.

Claims (9)

[Claims] 1. 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, wherein: a supporting means for supporting the insulating substrate; A light source that emits an excimer laser beam to the support means that is moved from outside the case to the inside of the case, and the light source emits light from the light source. An opening through which the excimer laser beam is incident into the housing; and a window frame that supports the periphery of the opening and has at least a part of the inner periphery inclined with respect to the traveling direction of the excimer laser beam. Excimer laser annealing equipment characterized by the following. 2. The excimer laser annealing according to claim 1, wherein at least a part of the 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. apparatus. 3. The excimer laser beam according to claim 1, wherein the cross-sectional shape of the excimer laser beam is substantially rectangular, and at least a part of the inner periphery of the window frame is a portion facing the major axis of the excimer laser beam. Item 3. An excimer laser annealing apparatus according to any one of Items 2. 4. A method of manufacturing a polycrystalline thin film transistor in which a thin film transistor device is formed by using polycrystalline silicon as a semiconductor layer by irradiating amorphous silicon deposited on an insulating substrate with an excimer laser beam, wherein the amorphous silicon is formed on the insulating substrate. A step of depositing silicon, and in a housing housing the supporting means for supporting the insulating substrate in a scan-movable manner, at least a part of an inner periphery of the housing is moved with respect to a traveling direction of an excimer laser beam from a light source emitting an excimer laser beam. A step of irradiating the excimer laser beam through an opening having an inclined window frame to crystallize the amorphous silicon into polycrystalline silicon. Method. 5. The 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 wider than the incident angle of the excimer laser beam at the periphery of the opening. Manufacturing method. 6. The excimer laser beam according to claim 4, wherein the cross-sectional shape of the excimer laser beam is substantially rectangular, and at least a part of the inner periphery of the window frame is a portion facing the major axis of the excimer laser beam. Item 6. A method for manufacturing a polycrystalline thin film transistor according to any one of Items 5. 7. An array substrate having a pixel electrode driven by a thin film transistor device formed of polycrystalline silicon as a semiconductor layer by irradiating an excimer laser beam to amorphous silicon deposited on a first insulating substrate; Manufacture of a liquid crystal display element including a counter substrate having a counter electrode on a second insulating substrate and disposed opposite to the array substrate, and a liquid crystal composition sealed between the array substrate and the counter substrate A method of depositing the amorphous silicon on the first insulating substrate, wherein at least a part of an inner periphery of the exciter is formed in a housing for movably enclosing support means for supporting the first insulating substrate. The excimer laser through an opening having a window frame inclined with respect to the traveling direction of the excimer laser beam from a light source that emits a laser beam; It enters the over beam, a method of manufacturing a liquid crystal display element characterized by comprising a step of crystallizing the amorphous silicon into polycrystalline silicon. 8. The 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 wider than the incident angle of the excimer laser beam at the periphery of the opening. Manufacturing method. 9. The cross section of the excimer laser beam is substantially rectangular, and at least a part of the inner periphery of the window frame is a portion facing the major axis of the excimer laser beam. Item 10. The method for manufacturing a liquid crystal display element according to any one of items 8.