JP2010045146A - Stage member for laser annealing, method of manufacturing the same, and laser annealing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stage member for laser annealing, a method of manufacturing the same, and a laser annealing method capable of reducing concentric circle stripes (Newton rings) without deteriorating an annealing property. <P>SOLUTION: In a stage member 11 for laser annealing, an upper surface 11a on which a processed body 7 is mounted is made to have a surface roughness with which the surface becomes clouded, for example a surface roughness of 0.1 &mu;m or more by Ra, by a sandblasting treatment, a hydrofluoric acid treatment, mechanical polishing or the like. Thereby, since interference between light 2 reflected at the upper surface 11a of the stage member 11 and light 2a reflected at a substrate bottom surface 8a of the treated body is reduced, concentric circle stripes caused by the reflection light can be reduced. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a laser annealing stage member for mounting an object to be processed by laser light irradiation, a manufacturing method thereof, and a laser annealing method.

  Conventionally, in order to manufacture a high-performance thin film transistor, a laser annealing process is known in which an amorphous silicon film formed on an insulating substrate such as a glass substrate is irradiated with laser light to be modified into a polycrystalline silicon film. (For example, refer to Patent Document 1). According to this method, since the crystallization phenomenon in the melting and solidifying process of the silicon film is used, a high-quality polycrystalline silicon film having a relatively large particle size can be obtained.

  A glass substrate has the advantages of being inexpensive, excellent in workability, and capable of increasing the area, compared to a quartz substrate that has been frequently used. Since the silicon film can be heated and melted by laser irradiation without increasing the temperature of the substrate so much, a glass substrate having a melting point of 600 ° C. or lower can be used.

  As a laser light source for laser annealing, in addition to an excimer laser that is a gas laser, a YAG laser that is a solid-state laser has recently been used. In the case of a YAG laser, when the fundamental wave is modulated to the second harmonic (wavelength 532 mm) and this is irradiated onto the amorphous silicon film, the absorption coefficient of the amorphous silicon film with respect to the laser light in that wavelength region is low. Not absorbed by the amorphous silicon film. For this reason, the light reflected from the surface of the amorphous silicon film interferes with the light transmitted through the amorphous silicon film and reflected from the bottom surface of the glass substrate, and the crystallized silicon film after processing is a concentric circle called Newton ring. It is known to form a striped pattern (see Patent Document 1). Hereinafter, in the present specification, the above-mentioned concentric striped pattern caused by reflected light is referred to as “concentric circular stripe”.

JP 2002-289524 A

  Until now, the above-mentioned concentric fringes have not been confirmed at the stage where the fringes caused by light scattering due to the influence of dust on the lens surface or the optical path, which are called vertical stripes, were visible. However, in Japanese Patent Application No. 2008-0003447, as a result of the establishment of a technique for reducing the above vertical stripes by the present applicant, concentric circle stripes that have not been confirmed so far can be seen.

  Similarly to the vertical stripes, the concentric circle stripes have a disadvantage that the stripes appear on the screen as they are when an active matrix type liquid crystal display or an organic EL display is manufactured. In particular, an organic EL display is more sensitive to fringes than a liquid crystal display. In the excimer laser, such a problem does not occur because the silicon film absorbs 100%.

  In Patent Document 1, as a countermeasure against concentric circular stripes, a technique is disclosed in which laser light is obliquely applied to an amorphous silicon film so that reflected light does not overlap incident light on the substrate surface. However, when a laser beam with a large NA (Numerical Aperture) is irradiated in order to obtain a light condensing degree, the following problem occurs. NA is one of numerical values indicating the performance of the objective lens by the numerical aperture. NA is expressed as NA = n · sin θ, where θ is the maximum angle with respect to the optical axis of the light beam incident on the objective lens from the object, and n is the refractive index of the medium between the object and the objective lens.

  In FIG. 3, 2 a is the reflected light of the laser beam 2 from the bottom surface 8 a of the glass substrate 8. When NA is increased, as shown in FIG. 3, there is a beam perpendicularly incident on the amorphous silicon film 9 and the glass substrate 8, and this is reflected to form concentric circular stripes in the irradiated region. In order to avoid this, when the method of further tilting the laser beam 2 is adopted, interference may be avoided, but the light collection characteristics (beam shape, depth of focus) change, and the annealing characteristics deteriorate. Therefore, this method is not a good idea.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a laser annealing stage member capable of reducing concentric circular stripes without deteriorating annealing characteristics, a manufacturing method thereof, and a laser annealing method. .

As a result of intensive studies on the factors of concentric circular stripes, the present inventor has found that the presence of an air layer formed between the glass substrate and the stage member on which the glass substrate is placed is a factor of the concentric circular stripes. That is, the light reflected from the bottom surface of the glass substrate and the light reflected from the surface of the stage member have an optical path difference that is an integral multiple of the wavelength corresponding to the thickness of the air layer, causing light interference and forming concentric circular stripes. I understood.
This concentric circle stripe is called a Newton stripe or Newton ring, and the same problem is pointed out in a touch panel or the like. In order to reduce the Newton ring in Japanese Patent Laid-Open Nos. 2003-75610 and 2002-373056 A method has been proposed. The present invention is an application of these methods.

That is, the laser annealing stage member, the manufacturing method thereof, and the laser annealing method employ the following technical means.
(1) The stage member for laser annealing of the present invention is a stage member for laser annealing for placing the object to be processed when processing the surface of the object to be processed by laser irradiation. The upper surface is subjected to a treatment for increasing the surface roughness.

  According to the configuration of the present invention described above, the surface roughness of the upper surface of the stage member on which the object to be processed is placed is formed so that the laser light reaching the stage member is diffused on the rough upper surface. Thereby, since interference between the light reflected on the upper surface of the stage member and the light reflected on the bottom surface of the substrate, which is the object to be processed, is reduced, concentric circular stripes caused by the reflected light can be reduced. Further, according to this method, even when NA is large, concentric fringes can be reduced without greatly tilting the laser beam, so that the annealing characteristics are not deteriorated.

(2) In the stage member for laser annealing described above, the surface roughness of the upper surface is preferably 0.1 μm or more in terms of Ra.

  Thus, by setting the surface roughness of the upper surface of the stage member to 0.1 μm or more in Ra, the diffusion effect of the reflection of the laser beam on the upper surface of the stage member can be enhanced.

(3) The laser annealing stage member is preferably made of quartz glass.

  Since quartz glass has a low reflectivity with respect to a visible light laser that easily transmits through an amorphous silicon film, reflection of laser light on the upper surface of the stage member can be reduced, and the effect of reducing concentric circular stripes can be further enhanced.

(4) The present invention relates to a method for manufacturing a laser annealing stage member for placing the object to be processed when the surface of the object to be processed is processed by laser irradiation. The method includes a step of preparing a workpiece to be formed, and a step of performing a process of roughening a surface roughness on a portion of the workpiece that becomes the upper surface.

  According to the method of the present invention described above, interference between the light reflected on the upper surface of the stage member and the light reflected on the bottom surface of the substrate is reduced, so that concentric fringes caused by the reflected light can be reduced.

(5) In the laser annealing stage member manufacturing method, the surface roughness is increased by sandblasting, hydrofluoric acid, or mechanical polishing.

  By these treatments, the surface roughness can be easily roughened.

(6) Further, the present invention is a laser annealing method for performing processing by laser irradiation on the surface of an object to be processed, the laser annealing stage member having an upper surface subjected to processing for roughening the surface roughness. The object to be processed is placed on an upper surface, and the surface of the object to be processed is irradiated with laser light.

  According to the present invention, concentric circular stripes can be reduced without deteriorating the annealing characteristics.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, the same code | symbol is attached | subjected to the common part in each figure, and the overlapping description is abbreviate | omitted.

  FIG. 1 is a diagram showing a schematic configuration of a laser annealing apparatus 1 including a laser annealing stage member 11 according to an embodiment of the present invention. The laser annealing apparatus 1 has, as its basic components, a laser light source 3 that emits laser light 2, a beam shaping optical system 4 that shapes the laser light 2 from the laser light source 3, and the laser light 2 that is to be processed by the object 7. A mirror 5 that reflects in the direction, a condenser lens 6 that condenses the laser beam 2 from the mirror 5 on the surface of the object 7 to be processed, and a stage device 10 on which the object 7 to be processed is placed.

  Here, as shown in FIG. 2, the object 7 to be processed by laser annealing is formed on a substrate 8 (for example, a glass substrate) made of a material transparent to the laser light 2 and on the surface of the substrate 8. The amorphous semiconductor film 9 is formed. The amorphous semiconductor film 9 is an amorphous silicon film, for example.

The laser light source 3 emits a laser beam 2 having a wavelength that is not completely absorbed by the amorphous semiconductor film 9 when the amorphous semiconductor film 9 is irradiated. For example, a YAG laser, a YLF laser, A laser beam obtained by modulating a fundamental wave of a YVO ₄ laser or glass laser into a second or third harmonic using a wavelength conversion element such as a nonlinear optical crystal may be emitted. The laser beam 2 may be either pulsed light or continuous light.

  The beam shaping optical system 4 shapes the laser light 2 so as to have a predetermined beam shape on the surface of the object 7 to be processed. The predetermined beam shape may be, for example, a circular or quadrangular spot shape, but is shaped into a linear beam that is elongated in the X direction in the figure and is scanned in the Y direction relative to the object 7 to be processed. By doing so, the large-scale object 7 can be processed efficiently. The beam shaping optical system 4 can include a beam expander, a homogenizer, and the like as components so as to have a predetermined beam shape.

  The stage apparatus 10 includes a laser annealing stage member 11 on which the workpiece 7 is placed and a stage moving apparatus 12 capable of moving the laser annealing stage member 11 two-dimensionally. Hereinafter, the stage member 11 for laser annealing is simply referred to as “stage member 11”.

  The stage member 11 is a member for placing the object to be processed 7 when processing the surface of the object 7 to be processed by laser irradiation. The stage member 11 has an upper surface 11a on which the object 7 is placed.

  The stage moving device 12 can scan the laser light 2 shaped into, for example, a linear beam in the Y direction relative to the object 7 by moving the stage member 11 in the Y direction. Further, when processing the object 7 to be processed which is longer than the length of the linear beam in the X direction, when the linear beam is scanned in the Y direction and the first column processing is completed, the stage member 11 is moved in the X direction, The entire surface of the object to be processed 7 can be processed by shifting the irradiation position of the linear beam to the object to be processed 7 in the X direction and performing the second and subsequent rows.

  FIG. 2 is a schematic view of a state in which the workpiece 7 is placed on the upper surface 11 a of the stage member 11. Although the upper surface 11a of the stage member 11 and the bottom surface of the substrate 8 are both made to be flat, in reality, as shown in FIG. An air layer (gap) 13 is formed between 8a.

  Therefore, when laser annealing is performed using a conventional stage member, the light reflected on the bottom surface of the glass substrate 8 and the light reflected on the surface of the stage member have an optical path difference that is an integral multiple of the wavelength by the thickness of the air layer 13. As a result, light interference occurs, and concentric stripes are formed in the processed semiconductor film.

In order to solve such a problem, in the stage member 11 of the present invention, the upper surface 11a on which the object to be processed 7 is placed is subjected to a process for increasing the surface roughness.
Moreover, the manufacturing method of the stage member 11 of this invention roughens surface roughness with respect to the process of preparing the workpiece | work which should become the stage member 11, and the part used as the upper surface 11a which mounts the to-be-processed body 7 of this workpiece | work. And a process of applying a treatment.
Further, in the laser annealing method of the present invention, the object to be processed 7 is placed on the upper surface 11a of the stage member 11 that has been processed to increase the surface roughness, and the surface of the object to be processed 7 (amorphous semiconductor film 9). The laser light 2 is irradiated.

  According to the present invention described above, since the surface roughness of the upper surface 11a of the stage member 11 on which the object 7 is placed is rough, the laser beam 2 that has reached the stage member 11 is diffused by the rough upper surface 11a. It is done. Thereby, since interference between the light reflected by the upper surface 11a of the stage member 11 and the light 2a reflected by the bottom surface of the substrate 8 is reduced, concentric circular stripes (Newton rings) caused by the reflected light can be reduced. Further, according to the present invention, even when NA is large, concentric fringes can be reduced without greatly tilting the laser beam 2, so that the annealing characteristics are not deteriorated.

As a process for roughening the surface roughness, sandblasting, hydrofluoric acid, mechanical polishing, or the like can be applied, and the surface roughness can be easily roughened by these processes.
Further, the surface roughness of the upper surface 11a of the stage member 11 is desirably such that the surface becomes clouded, and for example, Ra should be 0.1 μm or more. By setting such surface roughness, the diffusion effect of the reflection of the laser light 2 on the upper surface 11a of the stage member 11 can be enhanced.

  The material of the stage member 11 is not particularly limited, and may be made of metal, for example, but is preferably made of quartz glass. Since quartz glass has a low reflectivity with respect to a visible light laser that easily transmits through an amorphous silicon film, the reflection of the laser beam 2 on the upper surface 11a of the stage member 11 can be reduced, and the concentric fringe reduction effect can be further enhanced. it can.

  Although the embodiments of the present invention have been described above, the embodiments of the present invention disclosed above are merely examples, and the scope of the present invention is not limited to these embodiments. . The scope of the present invention is indicated by the description of the scope of claims, and further includes meanings equivalent to the description of the scope of claims and all modifications within the scope.

It is a figure which shows schematic structure of the laser annealing apparatus provided with the stage member for laser annealing concerning embodiment of this invention. It is a schematic diagram of the state which mounted the to-be-processed object on the upper surface of the stage member shown in FIG. It is a figure explaining the problem of a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laser annealing apparatus 2 Laser beam 3 Laser light source 4 Beam shaping optical system 5 Mirror 6 Condensing lens 7 To-be-processed object 8 Substrate 8a Bottom surface 9 Amorphous semiconductor film 10 Stage apparatus 11 Laser annealing stage member 11a Upper surface 13 Air layer ( Gap)

Claims (6)

A stage member for laser annealing for placing the object to be processed when processing the surface of the object to be processed by laser irradiation,
A stage member for laser annealing, comprising: an upper surface on which the object to be processed is placed, wherein the upper surface is subjected to a treatment for increasing the surface roughness.   The stage member for laser annealing according to claim 1, wherein the surface roughness of the upper surface is 0.1 μm or more in Ra.   3. The stage member for laser annealing according to claim 1, wherein the stage member is made of quartz glass. A method for manufacturing a stage member for laser annealing for mounting a target object when processing the surface of the target object by laser irradiation,
Preparing a workpiece to be the laser annealing stage member;
And a step of roughening the surface roughness of the part to be the upper surface of the workpiece. A method for manufacturing a stage member for laser annealing, comprising:   The method for producing a stage member for laser annealing according to claim 4, wherein the treatment for roughening the surface roughness is sandblast treatment, hydrofluoric acid treatment or mechanical polishing. A laser annealing method for performing processing by laser irradiation on the surface of an object to be processed,
A laser characterized in that the object to be processed is placed on the upper surface of a stage member for laser annealing having an upper surface that has been processed to increase the surface roughness, and the surface of the object to be processed is irradiated with laser light. Annealing method.

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