JP2012244025A - Light radiation device and light radiation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light radiation device and light radiation method which ensure that irradiation regions on a workpiece do not overlap each other and that no gap develops between the irradiation regions, thereby making uniform crystallization over the entire workpiece surface possible, the light radiation device being composed of a light source unit having a rod-like flash lamp, a stage to place a workpiece thereon and a light-transmissive window member interposed between the light source unit and the stage.SOLUTION: A light-transmissive window member, which is a glass member, has formed therein a high transmittance area for forming a generally rectangular crystallization region on a workpiece surface and a low transmittance area for inhibiting crystallization of other regions than the crystallization region on the workpiece surface.

Description

  The present invention relates to a light irradiation apparatus and a light irradiation method using a flash lamp, and in particular, light irradiation for crystallizing (polysiliconizing) an amorphous silicon film formed on a glass substrate (work). The present invention relates to an apparatus and a light irradiation method.

Conventionally, in applications such as liquid crystal displays and organic EL displays, flash lamps have been used to crystallize an amorphous silicon film on a glass substrate when a thin film transistor is manufactured.
For example, Japanese Patent Laying-Open No. 2005-026354 (Patent Document 1) describes that amorphous silicon is crystallized by emitting a plurality of rod-shaped flash lamps arranged side by side.
The use of a flash lamp as the light source has advantages of higher throughput and lower cost as a whole apparatus than the conventional method using the excimer laser radiation.

FIG. 7 shows the above prior art, in which a plurality of rod-like flash lamps 50 are arranged in parallel with respect to the workpiece W, and these flash lamps 50 emit light simultaneously.
However, in this irradiation method using a flash lamp, there is a variation in the irradiation energy distribution on the substrate due to one light emission, and a crystallized region, a non-crystallized region, or a semi-crystallized region on the substrate surface. There has been a problem that nonuniformity in location occurs in the crystallization level, for example, mixed regions are mixed.
In the case where the rod-shaped lamps are arranged in parallel, due to the simultaneous light emission, an elliptical crystallization region X is formed on the surface of the workpiece W as shown in FIG. The reason for the elliptical shape is that the irradiation energy on the surface of the workpiece W is not uniform, and the center portion is high, but the periphery is lower. That is, in the tube axis direction of the lamp 50, the irradiation energy is high at the central portion of the tube axis, and is low at both ends thereof. Therefore, the high irradiation energy region X has an elliptical shape as illustrated.
By the way, when amorphous silicon receives irradiation energy (crystallization energy) of a predetermined value or more, a crystallization reaction occurs in the region. For this reason, in the crystallization region X, an oval shape is formed with a portion receiving the crystallization energy as an outline (boundary line).
As a result, as described above, it is inevitable that the crystallization level on the work surface is locally uneven.

As a means to solve this problem, the flash lamps are made longer, the number of lamps arranged in parallel is increased, and these lamps are caused to emit light at the same time, thereby increasing the size of the pseudo planar light source and enlarging the elliptical area itself. Conceivable. This is because, as long as the ellipse area itself is enlarged so that the entire area of the workpiece surface is within the elliptic area, the entire area can be crystallized by a single irradiation on the workpiece surface.
However, an increase in the length of the lamp and an increase in the number of arrangements are not preferable because it leads to an increase in the size of the entire apparatus.Further, it is preferable that the pulse width is as small as possible for crystallization with a flash lamp, When the lamp is lengthened, this pulse width is extended, and as a result, the thickness of the crystallized layer becomes thicker than necessary and the glass substrate is warped. It is not possible.
In addition, simultaneously emitting a plurality of flash lamps is complicated in terms of control, so there is a limit to the number of lamps to be arranged.
In particular, there is a limit to further increasing the length of the lamp against the increase in the size of workpieces in recent years, and this method also has a limit.

Furthermore, as a method for solving this problem, in order to crystallize the surface of a large workpiece, a method of sequentially irradiating a plurality of divided irradiation regions while performing position feeding is conceivable. . This is similar to the idea of step exposure of a semiconductor wafer.
That is, the non-crystallized region is crystallized by irradiating the non-crystallized region again with light. However, as described above, when the irradiation areas having an elliptical shape are sequentially irradiated so as to be adjacent to each other, the irradiation areas overlap each other, or if an attempt is made to avoid this, an unirradiated area may be formed. The problem that occurs.
If the irradiated areas overlap, the area where the crystallization reaction has already occurred will be irradiated again with an energy higher than the crystallization energy. Amorphous silicon that has been irradiated multiple times will have different crystallization qualities. There is a big problem in the field and it cannot be adopted.
In addition, there is a problem that the substrate itself is damaged when the irradiation is overlapped and excessive irradiation occurs.

JP 2005-026354 A

  In view of the above-mentioned problems of the prior art, the problems to be solved by the present invention are a light source unit having a rod-shaped flash lamp, a stage on which a work having amorphous silicon deposited thereon, a light source unit and a stage In a light irradiation apparatus comprising a light transmissive window member existing between and a light irradiation method using the same, a light irradiation apparatus having a structure capable of achieving good crystallization even in a large workpiece and It is to provide a light irradiation method used.

In order to solve the above-described problems, in the light irradiation apparatus according to the present invention, the light transmissive window member existing between the light source unit and the stage on which the work is placed is a glass member, and is substantially rectangular on the work surface. A high transmittance area for forming a shape crystallization region and a low transmittance area for preventing a region other than the crystallization region on the workpiece surface from being crystallized are formed.
The low transmittance area is formed by frost processing.
Further, the light transmissive window member is characterized in that a transmittance reduction area for reducing an irradiation amount on the work surface is locally formed within the range of the high transmittance area.
Further, the light source unit is provided with a light source unit moving mechanism, and moves so as to sequentially form the crystallization regions adjacent to each other on the work surface.
Further, the stage is provided with a stage moving mechanism, and moves so as to sequentially form the crystallization regions adjacent to each other on the work surface.
Furthermore, in the light irradiation method according to the present invention, the light that has passed through the high transmittance area with respect to the crystallization region formed on the work surface while moving the light source unit or the stage in the light irradiation apparatus. The light that has passed through the high transmittance area is sequentially irradiated to the non-crystallized region without irradiating the layers.

According to the light irradiation apparatus and the light irradiation method of the present invention, the irradiation is insufficient due to insufficient irradiation by sequentially irradiating the workpiece with a substantially rectangular irradiation region smaller than this. Crystallization is uniformly performed in all regions on the work surface without generating a region or generating a region where the irradiated regions overlap and over-irradiate.
Thereby, it is possible to appropriately cope with an increase in the size of the workpiece, regardless of the limitation of the lengthening of the lamp.

Schematic of the light irradiation apparatus of this invention. Explanatory drawing of the light transmissive window member used for this invention. The other Example of the light transmissive window member of this invention. Explanatory drawing of the irradiation area | region of a workpiece | work. Sectional drawing of amorphous silicon. The other Example of the light transmissive window member of this invention. Conventional light irradiation device.

FIG. 1 is a schematic view of a light irradiation apparatus in which a plurality of flash lamps of the present invention are arranged.
The light irradiation device 1 includes a light source unit 2, a stage 3 on which a work is mounted, and a light transmissive window member 4.
The light source unit 2 includes a plurality of rod-like flash lamps 21 arranged in parallel in the casing 22 and a reflection mirror 23 surrounding the rod-like flash lamps 21. The flash lamp 21 is filled with, for example, xenon gas, and emits light at, for example, 10 J / cm ² Joules and 1/3 hertz by a power supply device (not shown).
A stage 3 is disposed below the light source unit 2, and a work W such as a liquid crystal substrate having an amorphous silicon film formed thereon is placed thereon, and includes a vacuum suction mechanism and the like.
The light source unit 2 is provided with a light source unit moving mechanism 24 for position adjustment, and the stage 3 is provided with a stage moving mechanism 31 for position adjustment. Note that both the light source unit moving mechanism 24 and the stage moving mechanism 31 are not necessarily required, and either one may be used.

A light transmissive window member (hereinafter also simply referred to as “window member”) 4 made of quartz glass or the like is provided below the flash lamp 21. In this embodiment, the light source unit 2 is attached to the casing 22.
FIG. 2 shows the light transmissive window member 4, FIG. 2 (A) is a plan view, and FIG. 2 (B) is a side view. As shown in FIG. 2A, the light transmissive window member 4 has a substantially rectangular plate shape as a whole. The window member 4 is formed with a rectangular high transmittance area 41 in the center and a low transmittance area 42 around it. The high transmittance area 41 is an area that transmits the light emitted from the flash lamp 21 with a high probability, and may be an untreated quartz glass or may be formed with an opening.
On the other hand, as shown in FIG. 2B, the low-transmittance area 42 is an area in which, for example, frost processing is performed on the surface of the glass material, and the emitted light of the flash lamp 21 is reduced and irradiated onto the workpiece surface. It is an area.
Technical drawing of the high transmittance area 41 and the low transmittance area 42 shows that light passing through the high transmittance area 41 crystallizes amorphous silicon, while light passing through the low transmittance area 42 is amorphous. The purpose is not to crystallize silicon. In other words, the irradiation energy on the work surface crystallizes or does not crystallize amorphous silicon, but the high transmittance area 41 and the low transmittance area 42 are drawn.
The means for forming the low transmittance area 42 is not limited to the frost processing described above, and any other method may be used as long as it is a means for reducing the transmittance. Alternatively, the transmittance may be zero by applying a light shielding material or the like. Here, regarding the window member 4, taking a numerical example, the overall dimensions are 150 mm × 250 mm and the thickness is 1.0 mm. The high transmittance area is 50 mm × 100 mm.

  FIG. 3 shows another embodiment of the light transmissive window member 4, in which processing such as frost processing that constitutes the low transmittance area 42 is performed on both surfaces of the glass member.

FIG. 4 shows an irradiation region X formed on the surface of the workpiece W. In this embodiment, a case will be described in which irradiation regions are sequentially formed on the work surface while the light source unit 2 is moved by the light source unit moving mechanism 24.
First, a rectangular irradiation region X1 irradiated with light transmitted through the light transmittance area 41 of the light transmissive window member 4 by light emission of the flash lamp 21 is formed on the workpiece W, and crystallization is performed in the region X1. The Next, the light source unit 2 is moved, and a rectangular irradiation region X <b> 2 is also formed adjacent to the light source unit 2.
In the same manner, irradiation regions Xn are sequentially formed thereafter, but irradiation is performed without overlapping with previously formed irradiation regions and without forming a gap therebetween.
Thus, in the present invention, by forming the rectangular irradiation region X on the workpiece W, even if the workpiece W is enlarged, the irradiation region (crystallization region) X is overlapped and irradiated twice. It is possible to irradiate so as not to create a non-irradiated area, and the entire irradiated surface area of the workpiece W is satisfactorily crystallized in the adjacent irradiated area X so that there is no gap and does not overlap. Can be crystallized.
For example, the dimension of the workpiece W is a rectangle of 1000 mm × 1000 mm, and the crystallization region X by one light irradiation is 50 mm × 100 mm.
In the above description, the light source unit 2 is sequentially moved. However, the stage 3 may be moved by the stage moving mechanism 31, and the both are relatively moved. It may be.

FIG. 5 shows the structure of amorphous silicon. (A) shows the structure of the top gate type amorphous silicon, and (B) shows the structure of the bottom gate type amorphous silicon.
In both the top gate type and the bottom gate type, SiO2 is formed on an alkali-free glass substrate, and amorphous silicon is formed thereon. In the top gate type, the amorphous silicon is irradiated with light, and then an electrode is formed on the amorphous silicon. However, in the bottom gate type, the electrode is already embedded in the SiO 2 when the light is irradiated.
Therefore, in the case of the top gate type, the amorphous silicon can be crystallized by irradiating light to the amorphous silicon by the procedure of the above-described embodiment. Irradiation light that has passed through the electrode is reflected by the electrode, and the reflected silicon irradiates the amorphous silicon again.
That is, the region where the electrode is formed is irradiated with light exceeding the design value, and the region that should not be crystallized is crystallized or the region that is originally crystallized is excessively light. Problems such as performance degradation due to irradiation occur.

FIG. 6 copes with such a situation, and shows a configuration of the light transmissive window member 4 used in the case of bottom gate type amorphous silicon.
A medium transmittance area 43 is locally formed in the high transmittance area 41 of the light transmissive window member 4. The medium transmittance area 43 is formed at a portion corresponding to the position of the electrode embedded in the SiO2. The transmittance is inferior to that of the high transmittance area 41, but is higher than that of the low transmittance area 42, and good crystallization can be achieved in consideration of light reflection by the electrodes.

  As described above, according to the light irradiation apparatus and the light irradiation method according to the present invention, the irradiation region is irradiated by sequentially irradiating the workpiece with a substantially rectangular irradiation region smaller than this. In all areas on the workpiece surface, there is no crystallization due to inadequate irradiation and no uncrystallized areas are generated due to insufficient irradiation, and there is no overlapped irradiation area. There is an effect that crystallization is performed uniformly.

DESCRIPTION OF SYMBOLS 1 Light irradiation apparatus 2 Light source unit 21 Flash lamp 22 Casing 23 Reflection mirror 24 Light source unit moving mechanism 3 Stage 31 Stage moving mechanism 4 Light transmissive window member 41 Light transmittance area 42 Low transmittance area 43 Medium decrease rate area W Workpiece ( substrate)
X irradiation area (crystallization area)

Claims (6)

In a light irradiation device comprising a light source unit having a rod-shaped flash lamp, a stage on which a work having amorphous silicon film formed thereon is placed, and a light transmissive window member existing between the light source unit and the stage,
The light transmissive window member is a glass member, and a high transmittance area for forming a substantially rectangular crystallization region on the work surface and a region other than the crystallization region on the work surface are crystallized. A light irradiating apparatus characterized in that a low transmittance area is formed so as not to cause a loss.   The light irradiation apparatus according to claim 1, wherein the low transmittance area is formed by frosting.   2. The light irradiation according to claim 1, wherein the light transmissive window member has a transmittance reduction area for locally reducing an irradiation amount on the workpiece surface within the range of the high transmittance area. apparatus.   2. The light irradiation apparatus according to claim 1, wherein the light source unit is provided with a light source unit moving mechanism, and moves so as to sequentially form the crystallization regions adjacent to each other on the work surface.   The light irradiation apparatus according to claim 1, wherein a stage moving mechanism is provided on the stage, and the stage moves so as to sequentially form the crystallization regions adjacent to each other on the work surface. A light irradiation method using an apparatus comprising: a light source unit having a rod-shaped flash lamp; a stage on which a work having an amorphous silicon film formed thereon is placed; and a light transmissive window member existing between the light source unit and the stage. In
The light transmissive window member is a glass member, and a high transmittance area for forming a substantially rectangular crystallization region on the work surface and a region other than the crystallization region on the work surface are crystallized. A low-transmittance area to prevent it from being formed,
While moving the light source unit or the stage, the crystallized region formed on the work surface is not irradiated with the light that has passed through the high transmittance area, and the high level is applied to the uncrystallized region. A light irradiation method characterized by sequentially irradiating light that has passed through a transmittance area.

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