JP2004064064A - Laser annealing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser annealing device which is capable of carrying out an accurate annealing process at high speed. <P>SOLUTION: A digital micromirror device (DMD) 50 is used as an irradiation head, wherein 600 micromirror rows each consisting of 800 micromirrors arranged in a main scanning direction are arranged in an auxiliary scanning direction. Some of the micromirror rows (e.g. 800 micromirrors×100 rows) are controlled by a controller. The DMD 50 has its limit related to a data processing speed, and a modulation speed per line is determined in proportion to the number of pixels to be used, so that the micromirror rows are partially used to enable to increase a modulation speed per line. <P>COPYRIGHT: (C)2004,JPO

Description

【０１３０】
表１から分かるように、１対の組合せレンズは、回転対称の２つの非球面レンズから構成されている。光入射側に配置された第１のレンズの光入射側の面を第１面、光出射側の面を第２面とすると、第１面は非球面形状である。また、光出射側に配置された第２のレンズの光入射側の面を第３面、光出射側の面を第４面とすると、第４面が非球面形状である。
【０１３１】
表１において、面番号Ｓｉはｉ番目（ｉ＝１〜４）の面の番号を示し、曲率半径ｒｉはｉ番目の面の曲率半径を示し、面間隔ｄｉはｉ番目の面とｉ＋１番目の面との光軸上の面間隔を示す。面間隔ｄｉ値の単位はミリメートル（ｍｍ）である。屈折率Ｎｉはｉ番目の面を備えた光学要素の波長４０５ｎｍに対する屈折率の値を示す。
【０１３２】
下記表２に、第１面及び第４面の非球面データを示す。
【０１３３】
【表２】

【０１３４】
上記の非球面データは、非球面形状を表す下記式（Ａ）における係数で表される。
【０１３５】
【数１】

【０１３６】
上記式（Ａ）において各係数を以下の通り定義する。
Ｚ：光軸から高さρの位置にある非球面上の点から、非球面の頂点の接平面（光軸に垂直な平面）に下ろした垂線の長さ（ｍｍ）
ρ：光軸からの距離（ｍｍ）
Ｋ：円錐係数
Ｃ：近軸曲率（１／ｒ、ｒ：近軸曲率半径）
ａｉ：第ｉ次（ｉ＝３〜１０）の非球面係数
表２に示した数値において、記号“Ｅ”は、その次に続く数値が１０を底とした“ぺき指数″であることを示し、その１０を底とした指数関数で表される数値が“Ｅ”の前の数値に乗算されることを示す。例えば、「１．０Ｅ−０２」であれば、「１．０×１０^−２」であることを示す。
【０１３７】
図２９は、上記表１及び表２に示す１対の組合せレンズによって得られる照明光の光量分布を示している。横軸は光軸からの座標を示し、縦軸は光量比（％）を示す。なお、比較のために、図２８に、補正を行わなかった場合の照明光の光量分布（ガウス分布）を示す。図２８及び図２９から分かるように、光量分布補正光学系で補正を行うことにより、補正を行わなかった場合と比べて、略均一化された光量分布が得られている。これにより、照射ヘッドにおける光の利用効率を落とさずに、均一なレーザ光でムラなくレーザアニールを行うことができる。
【０１３８】
［他の結像光学系］
上記の実施の形態では、照射ヘッドに使用するＤＭＤの光反射側に、結像光学系として２組のレンズを配置したが、レーザ光を拡大して結像する結像光学系を配置してもよい。ＤＭＤにより反射される光束線の断面積を拡大することで、被照射面における照射エリア面積を所望の大きさに拡大することができる。
【０１３９】
例えば、照射ヘッドを、図３０（Ａ）に示すように、ＤＭＤ５０、ＤＭＤ５０にレーザ光を照射する照明装置１４４、ＤＭＤ５０で反射されたレーザ光を拡大して結像するレンズ系４５４、４５８、ＤＭＤ５０の各画素に対応して多数のマイクロレンズ４７４が配置されたマイクロレンズアレイ４７２、マイクロレンズアレイ４７２の各マイクロレンズに対応して多数のアパーチャ４７８が設けられたアパーチャアレイ４７６、アパーチャを通過したレーザ光を被露光面５６に結像するレンズ系４８０、４８２で構成することができる。
【０１４０】
この照射ヘッドでは、照明装置１４４からレーザ光が照射されると、ＤＭＤ５０によりオン方向に反射される光束線の断面積が、レンズ系４５４、４５８により数倍（例えば、２倍）に拡大される。拡大されたレーザ光は、マイクロレンズアレイ４７２の各マイクロレンズによりＤＭＤ５０の各画素に対応して集光され、アパーチャアレイ４７６の対応するアパーチャを通過する。アパーチャを通過したレーザ光は、レンズ系４８０、４８２により被露光面５６上に結像される。
【０１４１】
この結像光学系では、ＤＭＤ５０により反射されたレーザ光は、拡大レンズ４５４、４５８により数倍に拡大されて走査面５６に投影されるので、全体の画像領域が広くなる。このとき、マイクロレンズアレイ４７２及びアパーチャアレイ４７６が配置されていなければ、図３０（Ｂ）に示すように、走査面５６に投影される各ビームスポットＢＳの１画素サイズ（スポットサイズ）が照射エリア４６８のサイズに応じて大きなものとなり、照射エリア４６８の鮮鋭度を表すＭＴＦ（Ｍｏｄｕｌａｔｉｏｎ　Ｔｒａｎｓｆｅｒ　Ｆｕｎｃｔｉｏｎ）特性が低下する。
【０１４２】
一方、マイクロレンズアレイ４７２及びアパーチャアレイ４７６を配置した場合には、ＤＭＤ５０により反射されたレーザ光は、マイクロレンズアレイ４７２の各マイクロレンズによりＤＭＤ５０の各画素に対応して集光される。これにより、図３０（Ｃ）に示すように、照射エリアが拡大された場合でも、各ビームスポットＢＳのスポットサイズを所望の大きさ（例えば、１０μｍ×１０μｍ）に縮小することができ、ＭＴＦ特性の低下を防止して高精細な露光を行うことができる。なお、照射エリア４６８が傾いているのは、画素間の隙間を無くす為にＤＭＤ５０を傾けて配置しているからである。
【０１４３】
また、マイクロレンズの収差によるビームの太りがあっても、アパーチャによって走査面５６上でのスポットサイズが一定の大きさになるようにビームを整形することができると共に、各画素に対応して設けられたアパーチャを通過させることにより、隣接する画素間でのクロストークを防止することができる。
【０１４４】
更に、照明装置１４４に上記実施の形態と同様に高輝度光源を使用することにより、レンズ４５８からマイクロレンズアレイ４７２の各マイクロレンズに入射する光束の角度が小さくなるので、隣接する画素の光束の一部が入射するのを防止することができる。即ち、高消光比を実現することができる。
【０１４５】
【発明の効果】
本発明のレーザアニール装置は、空間光変調素子を備えているが、この空間光変調素子の変調速度を速くして、高速且つ高精細なアニールを行うことができる、という効果を奏する。
【図面の簡単な説明】
【図１】第１の実施の形態に係るレーザアニール装置の外観を示す斜視図である。
【図２】第１の実施の形態に係るレーザアニール装置のスキャナの構成を示す斜視図である。
【図３】（Ａ）は感光材料に形成される照射済み領域を示す平面図であり、（Ｂ）は各照射ヘッドによる照射エリアの配列を示す図である。
【図４】第１の実施の形態に係るレーザアニール装置の照射ヘッドの概略構成を示す斜視図である。
【図５】（Ａ）は図４に示す照射ヘッドの構成を示す光軸に沿った副走査方向の断面図であり、（Ｂ）は（Ａ）の側面図である。
【図６】デジタルマイクロミラーデバイス（ＤＭＤ）の構成を示す部分拡大図である。
【図７】（Ａ）及び（Ｂ）はＤＭＤの動作を説明するための説明図である。
【図８】（Ａ）及び（Ｂ）は、ＤＭＤを傾斜配置しない場合と傾斜配置する場合とで、走査ビームの配置及び走査線を比較して示す平面図である。
【図９】（Ａ）はファイバアレイ光源の構成を示す斜視図であり、（Ｂ）は（Ａの部分拡大図である。
【図１０】マルチモード光ファイバの構成を示す図である。
【図１１】合波レーザ光源の構成を示す平面図である。
【図１２】レーザモジュールの構成を示す平面図である。
【図１３】図１２に示すレーザモジュールの構成を示す側面図である。
【図１４】図１２に示すレーザモジュールの構成を示す部分側面図である。
【図１５】（Ａ）及び（Ｂ）は、低輝度照射ヘッドにおける焦点深度と高輝度照射ヘッドにおける焦点深度との相違を示す光軸に沿った断面図である。
【図１６】（Ａ）及び（Ｂ）は、ＤＭＤの使用領域の例を示す図である。
【図１７】（Ａ）はＤＭＤの使用領域が適正である場合の側面図であり、（Ｂ）は（Ａ）の光軸に沿った副走査方向の断面図である。
【図１８】スキャナによる１回の走査で透明基板をアニールするアニール方式を説明するための平面図である。
【図１９】（Ａ）及び（Ｂ）はスキャナによる複数回の走査で透明基板をアニールするアニール方式を説明するための平面図である。
【図２０】レーザアレイの構成を示す斜視図である。
【図２１】（Ａ）はマルチキャビティレーザの構成を示す斜視図であり、（Ｂ）は（Ａ）に示すマルチキャビティレーザをアレイ状に配列したマルチキャビティレーザアレイの斜視図である。
【図２２】合波レーザ光源の他の構成を示す平面図である。
【図２３】合波レーザ光源の他の構成を示す平面図である。
【図２４】（Ａ）は合波レーザ光源の他の構成を示す平面図であり、（Ｂ）は（Ａ）の光軸に沿った断面図である。
【図２５】（Ａ）及び（Ｂ）は、低温ポリシリコンＴＦＴ形成プロセスを説明するための図である。
【図２６】アモルファスシリコンの吸収特性を示す図である。
【図２７】光量分布補正光学系による補正の概念についての説明図である。
【図２８】光源がガウス分布で且つ光量分布の補正を行わない場合の光量分布を示すグラフである。
【図２９】光量分布補正光学系による補正後の光量分布を示すグラフである。
【図３０】（Ａ）は結合光学系の異なる他の照射ヘッドの構成を示す光軸に沿った断面図であり、（Ｂ）はマイクロレンズアレイ等を使用しない場合に走査面に投影される光像を示す平面図であり、（Ｃ）はマイクロレンズアレイ等を使用した場合に走査面に投影される光像を示す平面図である。
【図３１】半導体レーザと光ファイバとを１対１で結合したファイバ光源の構成を示す側面図である。
【図３２】図３１のファイバ光源を上方から見た平面図である。
【符号の説明】
ＬＤ１〜ＬＤ７　ＧａＮ系半導体レーザ
１０　ヒートブロック
１１〜１７　コリメータレンズ
２０　集光レンズ
３０　マルチモード光ファイバ
５０　デジタル・マイクロミラー・デバイス（ＤＭＤ）
５３　反射光像（走査ビーム）
５４、５８　レンズ系
５６　走査面（アニール面）
６４　レーザモジュール
６６　ファイバアレイ光源
６８　レーザ出射部
７３　組合せレンズ
１５０　透明基板
１５２　ステージ
１６２　スキャナ
１６６　照射ヘッド
１６８　照射エリア
１７０　照射済み領域[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a laser annealing apparatus, and more particularly to a laser annealing apparatus using a GaN (gallium nitride) based semiconductor laser as a light source.
[0002]
[Prior art]
In recent years, not only thin film transistors (TFTs) for pixel display gates but also driving circuits and the like from the viewpoint of reducing the size and weight of flat panel displays such as liquid crystal displays (LCDs) and organic EL (electroluminescence) displays. A system-on-glass (SOG) -TFT in which a signal processing circuit, an image processing circuit, and the like are directly formed on a glass substrate of an LCD has attracted attention.
[0003]
Conventionally, amorphous silicon has been used for TFTs for pixel display gates, but polysilicon with high carrier mobility is required for SOG-TFTs. However, since the deformation temperature of glass is as low as 600 ° C., a crystal growth technique using a high temperature of 600 ° C. or higher cannot be used for forming a polysilicon film. Therefore, for the formation of the polysilicon film, after forming the amorphous silicon film at a low temperature (100 to 300 ° C.), the amorphous silicon film is thermally melted by pulse irradiation with a XeCl excimer laser having a wavelength of 308 nm and crystallized in the cooling process. Excimer laser annealing (ELA) is generally used (Non-Patent Document 1). By using this ELA, a polysilicon film can be formed without thermally damaging the glass substrate.
[0004]
[Non-Patent Document 1]
Junichi Tsujida and two others, "Polysilicon TFT annealing with XeCl excimer laser", Laser Research January 2000 [0005]
[Problems to be solved by the invention]
However, in the XeCl excimer laser, the light output is unstable and the output intensity varies within a range of ± 10%. For this reason, ELA has a problem in that the crystal grain size in the polysilicon film varies and reproducibility is poor. In addition, since the XeCl excimer laser has a pulse drive repetition frequency as low as 300 Hz, it is difficult to form continuous crystal grain boundaries with ELA, and high carrier mobility cannot be obtained. There is a problem that it cannot be annealed. In addition, there are problems inherent to gas lasers, such as the life of the laser tube and laser gas being as short as about 1 × 10 ⁷ shots, high maintenance costs, large equipment, and low energy efficiency of 3%.
[0006]
In ELA, a laser beam emitted from an excimer laser is shaped into a linear beam by a homogenizer optical system in order to obtain a polysilicon film having uniform crystal characteristics. There is a problem of becoming. In addition, since an XeCl excimer laser having a wavelength of 308 nm and an ultraviolet region is used, an optical system of a special material is required.
[0007]
The IEICE Technical Report ED2001-10 p21-p27 (2001) describes an example in which a high-power solid-state laser is used instead of an excimer laser, but at a low-power oscillation wavelength of 532 nm. There is a problem that amorphous silicon does not absorb light sufficiently and heat generation efficiency is poor.
[0008]
Among various problems, the problem of annealing speed is an important issue for mass production and compatibility with large substrates.
[0009]
The present invention has been made to solve the above problems, and an object of the present invention is to provide a laser annealing apparatus capable of performing high-speed and high-definition annealing.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, a laser annealing apparatus of the present invention includes a laser light source configured to generate a plurality of light emitting points that emit a laser beam having a wavelength of 350 to 450 nm by at least one GaN-based semiconductor laser, A large number of pixel portions whose light modulation states change according to a control signal are arranged on a substrate, a spatial light modulation element that modulates a laser beam emitted from the laser light source, and a pixel portion arranged on the substrate. A control means for controlling each of a plurality of pixel portions less than the total number by a control signal generated in accordance with annealing information; a scanning means for scanning the annealing surface with a laser beam modulated by each pixel portion; It is characterized by having.
[0011]
In the laser annealing apparatus of the present invention, the laser beam having a wavelength of 350 to 450 nm emitted from the laser light source is modulated by each pixel portion of the spatial light modulator. Then, the annealing surface is scanned with the laser beam modulated by the scanning means. In the laser annealing apparatus of the present invention, each of the plurality of pixel portions of the spatial light modulation element, which is smaller than the total number of pixel portions arranged on the substrate, is controlled by a control signal generated according to the annealing information. . That is, some of the pixel portions are controlled without controlling all of the pixel portions arranged on the substrate. For this reason, the number of pixel units to be controlled is reduced, and the transfer rate of the control signal is shorter than when the control signals of all the pixel units are transferred. As a result, the modulation speed of the laser beam can be increased and high-speed annealing can be performed.
[0012]
The laser light source is configured to generate a plurality of light emitting points that emit a laser beam having a wavelength of 350 to 450 nm using at least one GaN-based semiconductor laser, and outputs from the plurality of light emitting points are combined. The light output required for annealing can be obtained. Also, since a GaN-based semiconductor laser that can be driven continuously and has excellent output stability is used as a laser light source, a polysilicon film having good crystal characteristics and high carrier mobility can be formed with high reproducibility and high speed. In addition, the laser annealing apparatus using an excimer laser is smaller and more reliable, easier to maintain, and more energy efficient. Furthermore, since a laser beam with a wavelength of 350 to 450 nm is used, it is not necessary to use an optical system of a special material, and the cost is low.
[0013]
As the laser light source configured to generate the plurality of light emitting points, the following light sources are preferably used. Of these, a combined laser light source and a fiber array light source and a fiber bundle light source using a plurality of combined laser light sources, which can easily achieve high output and high brightness, are particularly preferable. That is, the combined laser light source can increase the brightness by increasing the number of laser beams to be combined. Thereby, the crystal characteristics of the polysilicon film can be improved and the resistance can be lowered, and the carrier mobility can be further increased. Further, in the fiber array light source and the fiber bundle light source, since the light source is configured by bundling a plurality of optical fibers, the area that can be irradiated with the laser at the same time is increased, and the large area can be annealed at high speed. That is, further speeding up is easy.
(1) A laser array in which a plurality of GaN semiconductor lasers are arranged in an array.
(2) A GaN-based multicavity laser having a plurality of light emitting points on one chip.
(3) Condensing laser beams emitted from each of the plurality of GaN-based semiconductor lasers, one optical fiber, and the plurality of GaN-based semiconductor lasers, and coupling the condensed beams to the incident end of the optical fiber And a condensing optical system.
(4) Condensing a laser beam emitted from each of a plurality of GaN-based multicavity lasers, a single optical fiber, and a plurality of light emitting points of the plurality of GaN-based multicavity lasers; And a condensing optical system coupled to the incident end of the optical fiber.
(5) A GaN-based multi-cavity laser having a plurality of light emitting points, one optical fiber, and a laser beam emitted from each of the plurality of light emitting points are condensed, and the condensed beam is collected from the optical fiber. And a condensing optical system coupled to the incident end.
(6) A fiber array light source including a plurality of the combined laser light sources, each of the light emitting points at the output end of the optical fiber of the plurality of combined laser light sources arranged in an array, or a fiber bundle arranged in a bundle light source.
(7) Condensing a single GaN-based semiconductor laser, one optical fiber, and a laser beam emitted from the single GaN-based semiconductor laser, and coupling the focused beam to the incident end of the optical fiber A plurality of fiber light sources, and a plurality of fiber light sources, each of the light emitting points at the output end of the optical fiber of each of the plurality of fiber light sources is arranged in an array, or in a bundle Fiber bundle light source.
[0014]
In the case of a light source that uses the output end of the optical fiber as a light emitting point, it is preferable to use an optical fiber having a uniform core diameter and a cladding diameter smaller than the incident end. In a fiber light source using an optical fiber having a large cladding diameter at the emission end, the diameter of the light emitting point when bundled becomes large, and as a result, a sufficient depth of focus cannot be obtained when performing high resolution annealing. By reducing the cladding diameter at the emission end, the brightness of the light source can be increased. Thereby, a laser annealing apparatus having a deeper focal depth can be realized. For example, even when annealing is performed with a beam diameter of 1 μm or less and a resolution of 0.1 μm or less, a deep depth of focus can be obtained, and high-speed and high-definition annealing is possible. Further, the crystal characteristics of the polysilicon film can be improved and the resistance can be lowered, and the carrier mobility can be further increased.
[0015]
Moreover, it is preferable that the output end of the optical fiber is sealed. The exit end of the optical fiber has a high light density and is likely to collect dust and easily deteriorate. However, sealing can prevent the dust from adhering to the end face and delay the deterioration.
[0016]
In addition, as the spatial modulation element, for example, a micromirror in which a large number of micromirrors each capable of changing the angle of a reflecting surface in accordance with a control signal are two-dimensionally arranged on a substrate (for example, a silicon substrate). A device (DMD; digital micromirror device) can be used.
[0017]
In addition, between the laser light source and the spatial modulation element, a collimator lens that changes the light beam from the laser light source into a parallel light beam, and the ratio of the light beam width in the peripheral part to the light beam width in the central part near the optical axis is The light beam width at each exit position is changed so that the exit side becomes smaller compared to each other, and the light amount distribution of the laser beam converted into a parallel beam by the collimator lens is substantially uniform on the irradiated surface of the spatial modulation element. It is preferable to arrange a light amount distribution correction optical system that corrects so as to be.
[0018]
According to this light quantity distribution correcting optical system, for example, light having the same light flux width on the incident side has a larger light flux width in the central part than in the peripheral part on the outgoing side. The width is smaller than the central part. In this way, since the light beam in the central part can be utilized to the peripheral part, it is possible to illuminate the spatial modulation element with light having a substantially uniform light amount distribution without reducing the light use efficiency as a whole. Thereby, it is not necessary to use an optical system of a special material, and laser annealing can be performed uniformly with a laser beam having a uniform intensity.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
In the following, an embodiment in which the laser annealing apparatus of the present invention is applied to low-temperature polysilicon TFT formation will be described in detail with reference to the drawings.
[0020]
First, a low temperature polysilicon TFT formation process will be briefly described. As shown in FIG. 25A, a silicon oxide (SiO _x ) insulating film 190 is deposited on a transparent substrate 150 made of glass or plastic, and an amorphous silicon film 192 is deposited on the SiO _x insulating film 190. The amorphous silicon film 192 is polycrystallized by laser annealing to form a polysilicon film. Thereafter, using a photolithography technique, for example, as shown in FIG. 25B, a polysilicon gate 194, a polysilicon source / polysilicon drain 196, a transparent substrate 150, with a SiO _x insulating film 190 interposed therebetween, A polysilicon TFT including the gate electrode 198, the source / drain electrode 200, and the interlayer insulating film 202 is formed.
[Configuration of laser annealing equipment]
As shown in FIG. 1, the laser annealing apparatus according to an embodiment of the present invention includes a flat stage 152 that holds and holds a transparent substrate 150 on which an amorphous silicon film is deposited on the surface. Two guides 158 extending along the stage moving direction are installed on the upper surface of the thick plate-shaped installation table 156 supported by the four legs 154. The stage 152 is arranged so that the longitudinal direction thereof faces the stage moving direction, and is supported by a guide 158 so as to be reciprocally movable. The laser annealing apparatus is provided with a driving device (not shown) for driving the stage 152 along the guide 158.
[0021]
A U-shaped gate 160 is provided at the center of the installation table 156 so as to straddle the movement path of the stage 152. Each of the ends of the U-shaped gate 160 is fixed to both side surfaces of the installation table 156. A scanner 162 is provided on one side of the gate 160, and a plurality of (for example, two) detection sensors 164 for detecting the front and rear ends of the transparent substrate 150 are provided on the other side. The scanner 162 and the detection sensor 164 are respectively attached to the gate 160 and fixedly arranged above the moving path of the stage 152. The scanner 162 and the detection sensor 164 are connected to a controller (not shown) that controls them.
[0022]
As shown in FIGS. 2 and 3B, the scanner 162 has a plurality of (for example, 14) laser beams for annealing arranged in a substantially matrix of m rows and n columns (for example, 3 rows and 5 columns). A head 166 is provided. In this example, four irradiation heads 166 are arranged in the third row in relation to the width of the transparent substrate 150. In addition, when each irradiation head arranged in the m-th row and the n-th column is shown, the irradiation head is expressed as 166 _mn .
[0023]
The irradiation area 168 by the irradiation head 166 has a rectangular shape with the short side in the sub-scanning direction. Therefore, as the stage 152 moves, a strip-shaped irradiated region 170 is formed on the transparent substrate 150 for each irradiation head 166. In addition, when showing the irradiation area by each irradiation head arranged in the mth row and the nth column, it describes with the irradiation area _168mn .
[0024]
Further, as shown in FIGS. 3A and 3B, each of the irradiation heads in each row arranged in a line so that the band-shaped irradiated regions 170 are arranged in the direction orthogonal to the sub-scanning direction without gaps. These are arranged with a predetermined interval (natural number times the long side of the irradiation area, twice in this embodiment) in the arrangement direction. Therefore, not be laser irradiated portion between the illumination area _{168 11} in the first row and the irradiation area _{168 12,} be laser irradiated by the second line of the irradiation area _{168 21} and third line of the irradiation area _{168 31} it can.
[0025]
Each of the irradiation heads 166 _{11 to} 166 _mn is a spatial light modulation element that modulates an incident light beam for each pixel according to image data, as shown in FIGS. 4, 5 (A) and (B). A digital micromirror device (DMD) 50 is provided. The DMD 50 is connected to a controller (not shown) including a data processing unit and a mirror drive control unit. The data processing unit of the controller generates a control signal for driving and controlling each micromirror in the region to be controlled by the DMD 50 for each irradiation head 166 based on the input image data. The area to be controlled will be described later. The mirror drive control unit controls the angle of the reflection surface of each micromirror of the DMD 50 for each irradiation head 166 based on the control signal generated by the image data processing unit. The control of the angle of the reflecting surface will be described later.
[0026]
On the light incident side of the DMD 50, a fiber array light source 66 including a laser emitting section in which emission ends (light emitting points) of an optical fiber are arranged in a line along a direction corresponding to the long side direction of the irradiation area 168, a fiber A lens system 67 for correcting the laser light emitted from the array light source 66 and condensing it on the DMD, and a mirror 69 for reflecting the laser light transmitted through the lens system 67 toward the DMD 50 are arranged in this order.
[0027]
The lens system 67 includes a pair of combination lenses 71 that collimate the laser light emitted from the fiber array light source 66 and a pair of combination lenses that correct the light quantity distribution of the collimated laser light to be uniform. 73 and a condensing lens 75 that condenses the laser light whose light quantity distribution is corrected on the DMD. With respect to the arrangement direction of the laser emitting ends, the combination lens 73 spreads the light beam at a portion close to the optical axis of the lens and contracts the light beam at a portion away from the optical axis, and with respect to a direction orthogonal to the arrangement direction. Has a function of allowing light to pass through as it is, and corrects the laser light so that the light quantity distribution is uniform.
[0028]
Further, on the light reflection side of the DMD 50, lens systems 54 and 58 that form an image of the laser light reflected by the DMD 50 on the scanning surface (annealed surface) 56 of the transparent substrate 150 are arranged. The lens systems 54 and 58 are arranged so that the DMD 50 and the scanning surface 56 are in a conjugate relationship.
[0029]
As shown in FIG. 6, the DMD 50 is configured such that a micromirror 62 is supported by a support column on an SRAM cell (memory cell) 60, and a large number of (pixels) (pixels) are formed. For example, the mirror device is configured by arranging 600 × 800 micromirrors in a lattice pattern. Each pixel is provided with a micromirror 62 supported by a support column at the top, and a material having a high reflectance such as aluminum is deposited on the surface of the micromirror 62. The reflectance of the micromirror 62 is 90% or more. A silicon gate CMOS SRAM cell 60 manufactured on a normal semiconductor memory manufacturing line is disposed directly below the micromirror 62 via a support including a hinge and a yoke, and is entirely monolithic (integrated type). ).
[0030]
When a digital signal is written in the SRAM cell 60 of the DMD 50, the micromirror 62 supported by the support is inclined within a range of ± α degrees (for example, ± 10 degrees) with respect to the substrate side on which the DMD 50 is disposed with the diagonal line as the center. It is done. FIG. 7A shows a state in which the micromirror 62 is tilted to + α degrees in the on state, and FIG. 7B shows a state in which the micromirror 62 is tilted to −α degrees in the off state. Therefore, by controlling the inclination of the micromirror 62 in each pixel of the DMD 50 as shown in FIG. 6 according to the image signal, the light incident on the DMD 50 is reflected in the inclination direction of each micromirror 62. .
[0031]
FIG. 6 shows an example of a state in which a part of the DMD 50 is enlarged and the micromirror 62 is controlled to + α degrees or −α degrees. On / off control of each micromirror 62 is performed by a controller (not shown) connected to the DMD 50. A light absorber (not shown) is arranged in the direction in which the light beam is reflected by the micromirror 62 in the off state.
[0032]
Further, it is preferable that the DMD 50 is arranged with a slight inclination so that the short side forms a predetermined angle θ (for example, 0.1 ° to 5 °) with the sub-scanning direction. 8A shows the scanning trajectory of the reflected light image (irradiation beam) 53 by each micromirror when the DMD 50 is not tilted, and FIG. 8B shows the scanning trajectory of the irradiation beam 53 when the DMD 50 is tilted. Show.
[0033]
In the DMD 50, a number of micromirror arrays in which a large number (for example, 800) of micromirrors are arranged in the longitudinal direction are arranged in a large number (for example, 600 sets) in the short direction. as shown, by tilting the DMD 50, the pitch P ₁ of the scanning locus of the illumination beam 53 by the micromirrors (scan line), it becomes narrower than the pitch P ₂ of the scanning lines in the case of not tilting the DMD 50, significant resolution Can be improved. On the other hand, the inclination angle of the DMD 50 is small, the scanning width _{W 2} in the case of tilting the DMD 50, which is substantially equal to the scanning width _{W 1} when not inclined DMD 50.
[0034]
Further, laser irradiation (multiple exposure) is performed by overlapping the same scanning line by different micromirror arrays. Thus, by performing multiple exposure, a minute amount of the laser irradiation position can be controlled, and high-definition annealing can be realized. Further, the joints between a plurality of irradiation heads arranged in the main scanning direction can be connected without a step by controlling a laser irradiation position with a minute amount.
[0035]
Note that the same effect can be obtained by arranging the micromirror rows in a staggered manner by shifting the micromirror rows by a predetermined interval in a direction orthogonal to the sub-scanning direction instead of tilting the DMD 50.
[0036]
As shown in FIG. 9A, the fiber array light source 66 includes a large number (for example, 100) of laser modules 64, and one end of the multimode optical fiber 30 is coupled to each laser module 64. Yes. An optical fiber 31 having the same core diameter as that of the multimode optical fiber 30 and a cladding diameter smaller than that of the multimode optical fiber 30 is coupled to the other end of the multimode optical fiber 30. ) Are arranged in a line along the main scanning direction orthogonal to the sub-scanning direction to constitute the laser emitting portion 68. Note that the light emitting points can also be arranged in two rows along the main scanning direction.
[0037]
As shown in FIG. 9B, the emission end of the optical fiber 31 is sandwiched and fixed between two support plates 65 having a flat surface. Further, a transparent protective plate 63 such as glass is disposed on the light emitting side of the optical fiber 31 in order to protect the end face of the optical fiber 31. The protective plate 63 may be disposed in close contact with the end face of the optical fiber 31. The protective plate 63 is separated from the end face of the optical fiber 31, and the protective plate 63 and the peripheral support plate 65 are used. You may arrange | position so that an end surface may be sealed. In this case, the end face of the optical fiber 31 is sealed together with the sealing gas. The exit end portion of the optical fiber 31 has a high light density and is likely to collect dust and easily deteriorate. However, the protective plate 63 can prevent the dust from adhering to the end face and can also delay the deterioration.
[0038]
In this example, in order to arrange the emission ends of the optical fibers 31 with a small cladding diameter in a line without any gaps, the multimode optical fiber 30 is placed between two adjacent multimode optical fibers 30 at a portion with a large cladding diameter. Two exit ends of the optical fiber 31 coupled to two adjacent multi-mode optical fibers 30 where the exit ends of the optical fibers 31 coupled to the stacked multi-mode optical fibers 30 are adjacent to each other at a portion where the cladding diameter is large. Are arranged so as to be sandwiched between them.
[0039]
For example, as shown in FIG. 10, an optical fiber 31 having a length of 1 to 30 cm and having a small cladding diameter is coaxially connected to the tip of the multimode optical fiber 30 having a large cladding diameter on the laser light emission side. Can be obtained by linking them together. In the two optical fibers, the incident end face of the optical fiber 31 is fused and joined to the outgoing end face of the multimode optical fiber 30 so that the central axes of both optical fibers coincide. As described above, the diameter of the core 31 a of the optical fiber 31 is the same as the diameter of the core 30 a of the multimode optical fiber 30.
[0040]
In addition, a short optical fiber in which an optical fiber having a short cladding diameter and a large cladding diameter is fused to an optical fiber having a short cladding diameter and a large cladding diameter may be coupled to the output end of the multimode optical fiber 30 via a ferrule or an optical connector. Good. By detachably coupling using a connector or the like, the tip portion can be easily replaced when an optical fiber having a small cladding diameter is broken, and the cost required for the irradiation head maintenance can be reduced. Hereinafter, the optical fiber 31 may be referred to as an emission end portion of the multimode optical fiber 30.
[0041]
The multimode optical fiber 30 and the optical fiber 31 may be any of a step index type optical fiber, a graded index type optical fiber, and a composite type optical fiber. For example, a step index type optical fiber manufactured by Mitsubishi Cable Industries, Ltd. can be used. In the present embodiment, the multimode optical fiber 30 and the optical fiber 31 are step index type optical fibers, and the multimode optical fiber 30 has a cladding diameter = 125 μm, a core diameter = 25 μm, NA = 0.2, an incident end face. The transmittance of the coat is 99.5% or more, and the optical fiber 31 has a cladding diameter = 60 μm, a core diameter = 25 μm, and NA = 0.2.
[0042]
In general, in laser light in the infrared region, propagation loss increases as the cladding diameter of the optical fiber is reduced. For this reason, a suitable cladding diameter is determined according to the wavelength band of the laser beam. However, the shorter the wavelength, the smaller the propagation loss. In the case of laser light having a wavelength of 405 nm emitted from a GaN-based semiconductor laser, the cladding thickness {(cladding diameter−core diameter) / 2} is set to infrared light in the wavelength band of 800 nm. The propagation loss hardly increases even if it is about ½ of the case of propagating infrared light and about ¼ of the case of propagating infrared light in the 1.5 μm wavelength band for communication. Therefore, the cladding diameter can be reduced to 60 μm.
[0043]
However, the cladding diameter of the optical fiber 31 is not limited to 60 μm. The clad diameter of an optical fiber used in a conventional fiber light source is 125 μm, but the depth of focus becomes deeper as the clad diameter becomes smaller. Therefore, the clad diameter of a multimode optical fiber is preferably 80 μm or less, more preferably 60 μm or less. Preferably, it is 40 μm or less. On the other hand, since the core diameter needs to be at least 3 to 4 μm, the cladding diameter of the optical fiber 31 is preferably 10 μm or more.
[0044]
The laser module 64 is configured by a combined laser light source (fiber light source) shown in FIG. This combined laser light source includes a plurality of (for example, seven) chip-like lateral multimode or single mode GaN-based semiconductor lasers LD1, LD2, LD3, LD4, LD5, LD6, arrayed and fixed on the heat block 10. And LD7, collimator lenses 11, 12, 13, 14, 15, 16, and 17 provided corresponding to each of the GaN-based semiconductor lasers LD1 to LD7, one condenser lens 20, and one multi-lens. Mode optical fiber 30. The number of semiconductor lasers is not limited to seven. For example, as many as 20 semiconductor laser beams can be incident on a multimode optical fiber having a cladding diameter = 60 μm, a core diameter = 50 μm, and NA = 0.2. In addition, the number of optical fibers can be further reduced.
[0045]
The GaN-based semiconductor lasers LD1 to LD7 all have a common oscillation wavelength (for example, 405 nm), and the maximum output can also be all common (for example, 100 mW for a multimode laser and 30 mW for a single mode laser, The laser output is not limited to this). As the GaN-based semiconductor lasers LD1 to LD7, lasers having an oscillation wavelength other than the above 405 nm in a wavelength range of 350 nm to 450 nm may be used. A suitable wavelength range will be described later.
[0046]
As shown in FIGS. 12 and 13, the above-described combined laser light source is housed in a box-shaped package 40 having an upper opening together with other optical elements. The package 40 includes a package lid 41 created so as to close the opening thereof. After the deaeration process, a sealing gas is introduced, and the package 40 and the package lid 41 are closed by closing the opening of the package 40 with the package lid 41. The combined laser light source is hermetically sealed in a closed space (sealed space) formed by 41.
[0047]
A base plate 42 is fixed to the bottom surface of the package 40, and the heat block 10, a condensing lens holder 45 that holds the condensing lens 20, and the multimode optical fiber 30 are disposed on the top surface of the base plate 42. A fiber holder 46 that holds the incident end is attached. The exit end of the multimode optical fiber 30 is drawn out of the package from an opening formed in the wall surface of the package 40.
[0048]
Further, a collimator lens holder 44 is attached to the side surface of the heat block 10, and the collimator lenses 11 to 17 are held. An opening is formed in the lateral wall surface of the package 40, and wiring 47 for supplying a driving current to the GaN-based semiconductor lasers LD1 to LD7 is drawn out of the package through the opening.
[0049]
In FIG. 13, in order to avoid complication of the drawing, only the GaN semiconductor laser LD7 among the plurality of GaN semiconductor lasers is numbered, and only the collimator lens 17 among the plurality of collimator lenses is numbered. doing.
[0050]
FIG. 14 shows the front shape of the attachment part of the collimator lenses 11-17. Each of the collimator lenses 11 to 17 is formed in a shape obtained by cutting a region including the optical axis of a circular lens having an aspherical surface into a long and narrow plane. This elongated collimator lens can be formed, for example, by molding resin or optical glass. The collimator lenses 11 to 17 are closely arranged in the arrangement direction of the light emitting points so that the length direction is orthogonal to the arrangement direction of the light emitting points of the GaN-based semiconductor lasers LD1 to LD7 (left and right direction in FIG. 14).
[0051]
On the other hand, each of the GaN-based semiconductor lasers LD1 to LD7 includes an active layer having a light emission width of 2 μm, and each of the laser beams B1 in a state parallel to the active layer and a divergence angle in a direction perpendicular to the active layer, respectively, for example A laser emitting ~ B7 is used. These GaN-based semiconductor lasers LD1 to LD7 are arranged so that the light emitting points are arranged in a line in a direction parallel to the active layer.
[0052]
Accordingly, in the laser beams B1 to B7 emitted from the respective light emitting points, the direction in which the divergence angle is large coincides with the length direction and the divergence angle is small with respect to the elongated collimator lenses 11 to 17 as described above. Incident light is incident in a state where the direction coincides with the width direction (direction perpendicular to the length direction). That is, the collimator lenses 11 to 17 have a width of 1.1 mm and a length of 4.6 mm, and the horizontal and vertical beam diameters of the laser beams B1 to B7 incident thereon are 0.9 mm and 2. 6 mm. Each of the collimator lenses 11 to 17 has a focal length f ₁ = 3 mm, NA = 0.6, and a lens arrangement pitch = 1.25 mm.
[0053]
The condensing lens 20 is formed by cutting a region including the optical axis of a circular lens having an aspheric surface into a long and narrow shape in parallel planes, and is long in the arrangement direction of the collimator lenses 11 to 17, that is, in a horizontal direction and short in a direction perpendicular thereto. Is formed. This condenser lens 20 has a focal length f ₂ = 23 mm and NA = 0.2. This condensing lens 20 is also formed by molding resin or optical glass, for example.
[0054]
[Operation of laser annealing equipment]
Next, the operation of the laser annealing apparatus will be described.
[0055]
In each irradiation head 166 of the scanner 162, laser beams B1, B2, B3, B4, B5, B6 emitted in a divergent light state from each of the GaN-based semiconductor lasers LD1 to LD7 constituting the combined laser light source of the fiber array light source 66. , And B7 are collimated by corresponding collimator lenses 11-17. The collimated laser beams B <b> 1 to B <b> 7 are collected by the condenser lens 20 and converge on the incident end face of the core 30 a of the multimode optical fiber 30.
[0056]
In this example, the collimator lenses 11 to 17 and the condenser lens 20 constitute a condensing optical system, and the condensing optical system and the multimode optical fiber 30 constitute a multiplexing optical system. That is, the laser beams B1 to B7 condensed as described above by the condenser lens 20 enter the core 30a of the multimode optical fiber 30 and propagate through the optical fiber to be combined with one laser beam B. The light is emitted from the optical fiber 31 coupled to the output end of the multimode optical fiber 30.
[0057]
In each laser module, when the coupling efficiency of the laser beams B1 to B7 to the multimode optical fiber 30 is 0.85 and each output of the GaN-based semiconductor lasers LD1 to LD7 is 30 mW (when a single mode laser is used). Can obtain a combined laser beam B with an output of 180 mW (= 30 mW × 0.85 × 7) for each of the optical fibers 31 arranged in an array. Therefore, the output from the laser emitting unit 68 in which 100 optical fibers 31 are arranged in an array is about 18 W (= 180 mW × 100).
[0058]
In the laser emitting portion 68 of the fiber array light source 66, light emission points with high luminance are arranged in a line along the main scanning direction as described above. A conventional fiber light source that couples laser light from a single single-mode semiconductor laser to a single optical fiber has a low output, so a desired output cannot be obtained unless multiple rows are arranged. Since the combined laser light source used in the embodiment has a high output, a desired output can be obtained even with a small number of columns, for example, one column.
[0059]
For example, in a conventional fiber light source in which a semiconductor laser and an optical fiber are coupled on a one-to-one basis, a laser having an output of about 30 mW (milliwatt) is usually used as the semiconductor laser, and the core diameter is 50 μm and the cladding diameter is 125 μm. Since a multimode optical fiber having a numerical aperture (NA) of 0.2 is used, if an output of about 18 W (watt) is to be obtained, 864 (8 × 10 8) multimode optical fibers must be bundled. In addition, since the area of the light emitting region is 13.5 mm ² (1 mm × 13.5 mm), the luminance at the laser emitting portion 68 is 1.3 (MW (megawatt) / m ² ), which is per optical fiber. The luminance is 8 (MW / m ² ).
[0060]
In contrast, in the present embodiment, as described above, an output of about 18 W can be obtained with 100 multimode optical fibers, and the area of the light emitting region at the laser emitting portion 68 is 0.3125 mm ² (0.025 mm). × 12.5 mm), the luminance at the laser emitting portion 68 is 57.6 (MW / m ² ), and the luminance can be increased by about 44 times compared to the conventional case. Moreover, the brightness | luminance per optical fiber is 288 (MW / m < ² >), and it can aim at about 36 time high brightness compared with the past.
[0061]
Here, with reference to FIGS. 15A and 15B, the difference in depth of focus between the low-intensity irradiation head and the high-intensity irradiation head of the present embodiment will be described. The diameter of the light emitting region of the bundled fiber light source of the low-intensity irradiation head in the sub-scanning direction is 1.0 mm, and the diameter of the light emitting region of the fiber array light source of the high-intensity irradiation head of this embodiment is 0. 0.025 mm. As shown in FIG. 15A, in the low-intensity irradiation head, since the light emitting region of the light source (bundle-shaped fiber light source) 1 is large, the angle of the light beam incident on the DMD 3 increases, and as a result, the light beam enters the scanning surface 5. The angle of the light beam increases. For this reason, the beam diameter tends to increase with respect to the light condensing direction (shift in the focus direction).
[0062]
On the other hand, as shown in FIG. 15B, in the high-intensity irradiation head of the present embodiment, the diameter of the light emitting area of the fiber array light source 66 is small, so that it passes through the lens system 67 and enters the DMD 50. As a result, the angle of the light beam incident on the scanning surface 56 is reduced. That is, the depth of focus becomes deep. In this example, the diameter of the light emitting region in the sub-scanning direction is about 30 times that of the conventional one, and a depth of focus substantially corresponding to the diffraction limit can be obtained. Therefore, it is suitable for laser annealing at a minute spot. The effect on the depth of focus is more prominent and effective as the required light quantity of the irradiation head is larger. In this example, the size of one pixel projected on the annealed surface is 10 μm × 10 μm. DMD is a reflective spatial modulation element, but FIGS. 15A and 15B are developed views for explaining the optical relationship.
[0063]
Image data corresponding to the annealing pattern is input to a controller (not shown) connected to the DMD 50 and temporarily stored in a frame memory in the controller. This image data is data representing the density of each pixel constituting the image by binary values (whether or not dots are recorded).
[0064]
The stage 152 that adsorbs the transparent substrate 150 to the surface is moved at a constant speed from the upstream side to the downstream side of the gate 160 along the guide 158 by a driving device (not shown). When the leading edge of the transparent substrate 150 is detected by the detection sensor 164 attached to the gate 160 when the stage 152 passes under the gate 160, the image data stored in the frame memory is sequentially read out for a plurality of lines. A control signal is generated for each irradiation head 166 based on the image data read by the data processing unit. Then, each of the micromirrors of the DMD 50 is controlled on and off for each irradiation head 166 based on the generated control signal by the mirror drive control unit.
[0065]
When the DMD 50 is irradiated with laser light from the fiber array light source 66, the laser light reflected when the micromirror of the DMD 50 is on is imaged on the annealed surface 56 of the transparent substrate 150 by the lens systems 54 and 58. The In this manner, the laser light emitted from the fiber array light source 66 is turned on and off for each pixel, and the transparent substrate 150 is irradiated with laser and annealed in approximately the same number of pixels (irradiation area 168) as the number of pixels used in the DMD 50. . Further, when the transparent substrate 150 is moved at a constant speed together with the stage 152, the transparent substrate 150 is sub-scanned in the direction opposite to the stage moving direction by the scanner 162, and a strip-shaped irradiated region 170 is formed for each irradiation head 166. It is formed.
[0066]
Amorphous silicon or the like has the absorption characteristics shown in FIG. 26 as described in “Amorphous Semiconductor Fundamentals” by Kazuo Morigaki, Ohm Co., p90 (1982). As can be seen from FIG. 26, the light absorption coefficient of amorphous silicon or the like changes according to the wavelength of the irradiated light. In this embodiment, a GaN-based semiconductor laser having a wavelength of 405 nm is used. However, as shown in FIG. 26, hydrogenated amorphous silicon (a-SiH _{0.16) is} also applied to laser light having a wavelength band of 400 nm. ) has a 105 cm ^-1 or more sufficient absorption properties can be estimated to have a 105 cm ^-1 or more absorption characteristics in the amorphous silicon (a-Si). Therefore, annealing can be efficiently performed with laser light having a wavelength band of 350 nm to 450 nm. However, from the viewpoint of absorption efficiency, laser light in the wavelength band of 370 nm to 410 nm is more preferable, and laser light in the wavelength band of 370 nm to 375 nm that has a relatively large output of the GaN-based semiconductor laser and large absorption of amorphous silicon is particularly preferable. preferable. The relationship between the photon energy and the wavelength is 1 eV = 8.0655 × 103 cm ⁻¹ , the wavelength 532 nm corresponds to 2.3 eV, and the wavelength 400 nm corresponds to 3.1 eV.
[0067]
As shown in FIGS. 16A and 16B, the DMD 50 includes 600 sets of micromirror arrays in which 800 micromirrors are arranged in the main scanning direction. In the embodiment, control is performed so that only a part of micromirror rows (for example, 800 × 10 rows) are driven by the controller.
[0068]
As shown in FIG. 16A, a micromirror array arranged at the center of the DMD 50 may be used, and as shown in FIG. 16B, the micromirror array arranged at the end of the DMD 50 is used. May be used. In addition, when a defect occurs in some of the micromirrors, the micromirror array to be used may be appropriately changed depending on the situation, such as using a micromirror array in which no defect has occurred.
[0069]
Since the data processing speed of the DMD 50 is limited and the modulation speed per line is determined in proportion to the number of pixels used, the modulation speed per line can be increased by using only a part of the micromirror rows. Get faster. On the other hand, in the scanning method in which the irradiation head is continuously moved relative to the annealing surface, it is not necessary to use all the pixels in the sub-scanning direction.
[0070]
For example, when only 300 sets are used in 600 micromirror rows, modulation can be performed twice as fast per line as compared to the case of using all 600 sets. Further, when only 200 sets of 600 micromirror arrays are used, modulation can be performed three times faster per line than when all 600 sets are used. That is, the laser irradiation can be performed in 17 seconds for a 500 mm region in the sub-scanning direction. Further, when only 100 sets are used, modulation can be performed 6 times faster per line. That is, the laser irradiation can be performed in 9 seconds in an area of 500 mm in the sub-scanning direction.
[0071]
The number of micromirror rows to be used, that is, the number of micromirrors arranged in the sub-scanning direction is preferably 10 or more and 200 or less, and more preferably 10 or more and 100 or less. Since the area per micromirror corresponding to one pixel is 15 μm × 15 μm, when converted to the use area of DMD50, an area of 12 mm × 150 μm or more and 12 mm × 3 mm or less is preferable, and 12 mm × 150 μm or more and 12 mm A region of × 1.5 mm or less is more preferable.
[0072]
If the number of micromirror rows to be used is within the above range, as shown in FIGS. 17A and 17B, the laser light emitted from the fiber array light source 66 is made into substantially parallel light by the lens system 67, and the DMD 50 Can be irradiated. It is preferable that the irradiation area where the laser beam is irradiated by the DMD 50 coincides with the use area of the DMD 50. When the irradiation area is wider than the use area, the utilization efficiency of the laser light is lowered.
[0073]
On the other hand, the diameter of the light beam condensed on the DMD 50 in the sub-scanning direction needs to be reduced according to the number of micromirrors arranged in the sub-scanning direction by the lens system 67, but the number of micromirror rows to be used. Is less than 10, it is not preferable because the angle of the light beam incident on the DMD 50 increases and the depth of focus of the light beam on the scanning surface 56 becomes shallow. Further, the number of micromirror rows to be used is preferably 200 or less from the viewpoint of modulation speed. DMD is a reflective spatial modulation element, but FIGS. 17A and 17B are developed views for explaining the optical relationship.
[0074]
Here, the light density on the exposure surface is calculated. As described above, the output of each irradiation head 166 is about 18 W. In addition, since only a part of the micromirror rows (for example, 800 × 10 rows) of the DMD 50 are used, the area of the irradiation area 168 (beam size on the exposure surface) by each irradiation head 166 is 150 μm × 12 mm. . When the 150 μm region is exposed at 1 msec, the light density on the exposed surface is 1000 mJ / cm ² . Furthermore, even if the loss due to the optical system is estimated to be about 50%, the light density on the exposed surface is 500 mJ / cm ² . In the entire scanner 162 including the 14 irradiation heads 166, the number of optical fibers 31 to be arrayed is 1400, and the total output is 252W. The total area of the irradiation area 168 is 150 μm × 168 mm, and the light density on the exposure surface is 500 mJ / cm ² .
[0075]
When a multimode laser having an output of 100 mW is used as the combined laser light source of the irradiation head, a combined laser beam B having an output of 600 mW can be obtained from seven LDs. Therefore, an output of about 18 W can be obtained with the 30 optical fibers 31. In the entire scanner 162 including the 14 irradiation heads 166, the number of optical fibers 31 to be arrayed is 420, and the total output is 252W. The total area of the irradiation area 168 is 150 μm × 168 mm, and the light density on the exposure surface is 500 mJ / cm ² .
[0076]
When the sub-scan of the transparent substrate 150 by the scanner 162 is completed and the rear end of the transparent substrate 150 is detected by the detection sensor 164, the stage 152 is moved along the guide 158 by the driving device (not shown) on the most upstream side of the gate 160. Returned to the origin at the point, and again moved along the guide 158 from the upstream side to the downstream side of the gate 160 at a constant speed.
[0077]
As described above, the laser annealing apparatus of this embodiment includes a DMD in which 600 sets of micromirror arrays in which 800 micromirrors are arranged in the main scanning direction are arranged in the subscanning direction. Since control is performed so that only some of the micromirror rows are driven, the modulation speed per line becomes faster than when all the micromirror rows are driven. This enables laser annealing at high speed.
[0078]
In addition, since the laser annealing apparatus of this embodiment uses a GaN-based semiconductor laser having a wavelength band of 350 to 450 nm, a line beam is generated using an optical system of a special material corresponding to ultraviolet rays like an ELA apparatus. There is no need to generate the same, and similarly to the laser exposure apparatus in the visible region, high-definition annealing in an arbitrary pattern is possible by on / off control of DMD.
[0079]
In particular, in the present embodiment, since the cladding diameter of the output end of the optical fiber is made smaller than the cladding diameter of the incident end, the diameter of the light emitting section is further reduced, and the brightness of the fiber array light source can be increased. Thereby, a laser annealing apparatus having a deeper focal depth can be realized. For example, even in the case of annealing at an ultra-high resolution with a beam diameter of 1 μm or less and a resolution of 0.1 μm or less, a deep focal depth can be obtained, and high-speed and high-definition annealing is possible.
[0080]
Further, since the laser annealing apparatus of the present embodiment uses a high-quality GaN-based semiconductor laser as the laser light source instead of the excimer laser that is a gas laser, there are the following advantages 1) to 6).
[0081]
1) A polysilicon film with a stabilized light output and a uniform crystal grain size can be produced with good reproducibility.
[0082]
2) Since the GaN-based semiconductor laser is a solid semiconductor laser, it can be driven for tens of thousands of hours and has high reliability. In addition, since the GaN-based semiconductor laser is covalently bonded, the light emitting end face called COD (catalytic optical damage) is not easily damaged, is highly reliable, and can achieve high peak power.
[0083]
3) Compared with the case of using an excimer laser, which is a gas laser, the size can be reduced and the maintenance becomes very simple. Moreover, energy efficiency is as high as 10% to 20%.
[0084]
4) Since the GaN-based semiconductor laser is basically a laser capable of CW (continuous) driving, even in the case of pulse driving, the repetition frequency and pulse width (duty) according to the absorption amount and heat generation amount of amorphous silicon. Can be set freely. For example, an arbitrary repetitive operation from several Hz to several MHz can be realized, and an arbitrary pulse width of several psec to several hundred msec can be realized. In particular, the repetition frequency can be up to several tens of MHz, and continuous crystal grain boundaries can be formed as in the case of CW driving. In addition, since the repetition frequency can be increased, high-speed annealing is possible.
[0085]
5) Since the annealing surface can be scanned in a predetermined direction with continuous laser light driven by CW driving a GaN-based semiconductor laser, the direction of crystal growth can be controlled and continuous crystal grain boundaries can be formed. It becomes possible to form a polysilicon film having a high carrier mobility.
[0086]
6) A laser beam having a wavelength of 350 to 450 nm can be obtained. In particular, high output can be obtained in the wavelength range of 370 to 410 nm (especially at 405 nm) where the light absorption rate of amorphous silicon is high, and amorphous silicon can be efficiently crystallized. Note that GaN-based semiconductor lasers can be expected to have higher output in the future.
[0087]
In addition, the laser annealing apparatus of the present embodiment uses a fiber array light source in which emission ends of optical fibers of a combined laser light source are arranged in an array as a laser light source. Therefore, there are the following advantages 1) to 3).
[0088]
1) Generally, in the laser annealing apparatus, it is necessary high optical density in the range of 400mJ ^/ cm ² ~700mJ ^/ cm 2 in the annealing surface (exposure surface), in this embodiment, a fiber number of arraying, if By increasing the number of laser beams to be waved, it is possible to easily achieve high output and high light density with multiple beams. For example, if the fiber output of one combined laser light source is 180 mW, a high output of 100 W can be stably obtained by bundling 556 lines. In addition, the beam quality is stable and the power density is high. Therefore, it is possible to cope with the future increase in the film formation area and high throughput of the low-temperature polysilicon.
[0089]
2) The exit end of the optical fiber can be attached in a replaceable manner using a connector or the like, and maintenance is facilitated.
[0090]
3) Since it is a small multiplexing module that combines small semiconductor lasers, the light source unit can be much smaller than the excimer laser.
[0091]
Next, modified examples of the laser annealing apparatus described above will be described.
[Other uses of laser annealing equipment]
In the above embodiment, an example in which a low-temperature polysilicon TFT is formed using the laser annealing apparatus of the present invention has been described. However, the laser annealing apparatus of the present invention uses ITO (indium-tin oxide), SnO ₂ (dioxide dioxide). It can also be used for annealing other materials such as annealing of a transparent electrode film composed of tin).
[0092]
[Other spatial modulation elements]
In the above embodiment, the example in which the DMD micromirror is partially driven has been described. However, the length of the direction corresponding to the predetermined direction is controlled on the substrate longer than the length of the direction intersecting the predetermined direction. Even if a long and thin DMD in which a number of micromirrors that can change the angle of the reflecting surface according to the signal are arranged in two dimensions is used, the number of micromirrors that control the angle of the reflecting surface is reduced. Speed can be increased.
[0093]
In the above-described embodiment, an irradiation head including a DMD as a spatial modulation element has been described. For example, a MEMS (Micro Electro Mechanical Systems) type spatial modulation element (SLM) or transmission by an electro-optic effect is used. Even when a spatial modulation element other than the MEMS type, such as an optical element (PLZT element) that modulates light or a liquid crystal optical shutter (FLC), is used, a part of the pixel parts is compared with all the pixel parts arranged on the substrate. By using it, the modulation speed per pixel and the main scanning line can be increased, so that the same effect can be obtained.
[0094]
Note that MEMS is a general term for micro systems that integrate micro-sized sensors, actuators, and control circuits based on micro-machining technology based on the IC manufacturing process. It means a spatial modulation element that is driven by the electromechanical operation used.
[0095]
[Other exposure methods]
As shown in FIG. 18, similarly to the above embodiment, the entire surface of the transparent substrate 150 may be annealed by one scan in the X direction by the scanner 162, as shown in FIGS. 19 (A) and 19 (B). As shown in the drawing, after the transparent substrate 150 is scanned in the X direction by the scanner 162, the scanner 162 is moved one step in the Y direction and scanned in the X direction. The entire surface of the transparent substrate 150 may be annealed. In this example, the scanner 162 includes 18 irradiation heads 166.
[0096]
[Other laser devices (light sources)]
In the above embodiment, an example using a fiber array light source including a plurality of combined laser light sources has been described. However, the laser light source is not limited to a fiber array light source in which combined laser light sources are arrayed. For example, a fiber array light source obtained by arraying fiber light sources including one optical fiber that emits laser light incident from a single semiconductor laser having one light emitting point can be used.
[0097]
(Broad stripe laser)
The broad stripe laser is a laser having a long light emitting region in a direction (horizontal direction) orthogonal to the stacking direction, and has a high output because the light emitting region is large. Therefore, by using a broad stripe laser, a high output and high luminance provided with a single semiconductor laser having one light emitting point and one optical fiber for emitting laser light incident from the semiconductor laser. Fiber light source, and thus a fiber array light source or a fiber bundle light source obtained by arraying the fiber light sources can be realized.
[0098]
For example, as shown in FIGS. 31 and 32, a broad stripe laser 180 is used as an illumination light source, and a first cylindrical lens is used as a beam shaping optical system between the broad stripe laser 180 and the incident end of the multimode optical fiber 30. 182, the second cylindrical lens 184, the third cylindrical lens 186, and the fourth cylindrical lens 188 are sequentially arranged from the broad stripe laser 180 side.
[0099]
The light beam emitted from the broad stripe laser 180 has the NA (numerical aperture) of the light beam in the stacking direction (vertical direction) less than the NA of the multimode optical fiber 30 by the first cylindrical lens 182 and the third cylindrical lens 186. The first cylindrical lens 182 and the third cylindrical lens 186 are converted, and the NA of the horizontal light beam is maintained at an equal magnification, and an image is formed on the incident end of the multimode optical fiber 30.
[0100]
When the width (vertical length) of the light emitting layer of the broad stripe laser 180 is 0.5 μm, the length of the light emitting layer (horizontal length) is 30 μm, and the wavelength of the light beam is 400 to 420 nm, An output of about 500 mW can be obtained. The 500 mW light beam is condensed and incident on one multimode optical fiber 30. Assuming that the coupling efficiency is 96%, the output end of each multimode optical fiber 30 is a light source of 480 mW. The exit end of the multimode optical fiber 30 can be arrayed or bundled and used as a light source.
[0101]
As the multimode optical fiber 30, for example, an optical fiber having a cladding diameter of 125 μm and a core diameter of 50 μm can be used. Further, by connecting an optical fiber having a small diameter of, for example, a cladding diameter of 60 μm and a core diameter of 50 μm to the emission end of the multimode optical fiber 30, the area of the emission end can be reduced and high luminance can be achieved. The multimode optical fiber 30 may be a small-diameter optical fiber having a cladding diameter of 60 μm and a core diameter of 50 μm. In other words, the beam of the broad stripe laser 180 is directly incident on the small-diameter multimode optical fiber 30 so that the exit end of the multimode optical fiber 30 can be used as the exit end with the same diameter.
[0102]
When the width of the light emitting layer of the broad stripe laser 180 is 5 to 200 μm, the NA of the multimode optical fiber 30 is 0.15 to 0.3, and the core diameter of the multimode optical fiber 30 is 10 to 80 μm. The coupling efficiency to the multimode optical fiber 30 is preferably increased. Further, the beam shaping optical system can be configured by using optical components other than the cylindrical lens.
[0103]
In the above description, the example in which the light beam from one broad stripe laser is coupled to one optical fiber has been described. However, the light beams from a plurality of broad stripe lasers are combined and coupled to one optical fiber. By doing so, it is possible to obtain a laser light source with higher output and higher brightness.
[0104]
(Laser array)
As a light source having a plurality of light emitting points, for example, as shown in FIG. 20, a laser array in which a plurality of (for example, seven) chip-shaped semiconductor lasers LD1 to LD7 are arranged on a heat block 100 is used. Can be used.
[0105]
(Multi-cavity laser and its array)
Further, a chip-shaped multicavity laser 110 in which a plurality of (for example, five) light emitting points 110a shown in FIG. 21A is arranged in a predetermined direction is known. Since the multicavity laser 110 can arrange the light emitting points with higher positional accuracy than the case where the chip-shaped semiconductor lasers are arranged, it is easy to multiplex laser beams emitted from the respective light emitting points. However, as the number of light emitting points increases, the multicavity laser 110 is likely to be bent at the time of laser manufacturing. Therefore, the number of light emitting points 110a is preferably 5 or less.
[0106]
In the irradiation head of the present invention, as shown in FIG. 21B, the multi-cavity laser 110 and a plurality of multi-cavity lasers 110 on the heat block 100 are in the same direction as the arrangement direction of the light emitting points 110a of each chip. A multi-cavity laser array arranged in the above can be used as a laser light source.
(Multiple cavity laser combined laser source)
The combined laser light source is not limited to one that combines laser beams emitted from a plurality of chip-shaped semiconductor lasers. For example, as shown in FIG. 22, a combined laser light source including a chip-shaped multicavity laser 110 having a plurality of (for example, three) light emitting points 110a can be used. This combined laser light source is configured to include a multi-cavity laser 110, one multi-mode optical fiber 130, and a condensing lens 120. The multi-cavity laser 110 can be composed of, for example, a GaN-based laser diode having an oscillation wavelength of 405 nm.
[0107]
In the above configuration, each of the laser beams B emitted from each of the plurality of light emitting points 110 a of the multicavity laser 110 is collected by the condenser lens 120 and enters the core 130 a of the multimode optical fiber 130. The laser light incident on the core 130a propagates in the optical fiber, is combined into one, and is emitted.
[0108]
A plurality of light emitting points 110 a of the multi-cavity laser 110 are juxtaposed within a width substantially equal to the core diameter of the multi-mode optical fiber 130, and a focal point substantially equal to the core diameter of the multi-mode optical fiber 130 is used as the condenser lens 120. By using a convex lens of a distance or a rod lens that collimates the outgoing beam from the multicavity laser 110 only in a plane perpendicular to the active layer, the coupling efficiency of the laser beam B to the multimode optical fiber 130 can be increased. it can.
[0109]
23, a multi-cavity laser 110 having a plurality of (for example, three) emission points is used, and a plurality of (for example, nine) multi-cavity lasers 110 are equally spaced from each other on the heat block 111. A combined laser light source including the laser array 140 arranged in (1) can be used. The plurality of multi-cavity lasers 110 are arranged and fixed in the same direction as the arrangement direction of the light emitting points 110a of each chip.
[0110]
This combined laser light source includes a laser array 140, a plurality of lens arrays 114 arranged corresponding to each multi-cavity laser 110, and a single rod arranged between the laser array 140 and the plurality of lens arrays 114. The lens 113, one multimode optical fiber 130, and a condenser lens 120 are provided. The lens array 114 includes a plurality of microlenses corresponding to the emission points of the multicavity laser 110.
[0111]
In the above configuration, each of the laser beams B emitted from each of the plurality of light emitting points 110a of the plurality of multi-cavity lasers 110 is condensed in a predetermined direction by the rod lens 113, and then each microlens of the lens array 114. It becomes parallel light. The collimated laser beam L is condensed by the condenser lens 120 and enters the core 130a of the multimode optical fiber 130. The laser light incident on the core 130a propagates in the optical fiber, is combined into one, and is emitted.
(Multiple laser light source using multi-stage laser array)
Still another example of the combined laser light source will be described. In this combined laser light source, as shown in FIGS. 24A and 24B, a heat block 182 having an L-shaped cross section in the optical axis direction is mounted on a substantially rectangular heat block 180, and two heats are provided. A storage space is formed between the blocks. On the upper surface of the L-shaped heat block 182, a plurality of (for example, two) multi-cavity lasers 110 in which a plurality of light emitting points (for example, five) are arranged in an array form the light emitting points 110a of each chip. It is arranged and fixed at equal intervals in the same direction as the arrangement direction.
[0112]
A concave portion is formed in the substantially rectangular heat block 180, and a plurality of (for example, two) light emitting points (for example, five) are arranged in an array on the upper surface of the space side of the heat block 180. The multi-cavity laser 110 is arranged such that its emission point is located on the same vertical plane as the emission point of the laser chip arranged on the upper surface of the heat block 182.
[0113]
On the laser beam emission side of the multi-cavity laser 110, a collimator lens array 184 in which collimator lenses are arranged corresponding to the light emission points 110a of the respective chips is arranged. In the collimating lens array 184, the length direction of each collimating lens coincides with the direction in which the divergence angle of the laser beam is large (the fast axis direction), and the width direction of each collimating lens is in the direction in which the divergence angle is small (slow axis direction). They are arranged to match. Thus, collimating lenses are arrayed and integrated, thereby improving the space utilization efficiency of the laser light and increasing the output of the combined laser light source, and reducing the number of parts and reducing the cost. it can.
[0114]
Further, on the laser beam emitting side of the collimating lens array 184, there is one multimode optical fiber 130, and a condensing lens 120 that condenses and combines the laser beam at the incident end of the multimode optical fiber 130. Has been placed.
[0115]
In the above configuration, each of the laser beams B emitted from each of the plurality of light emitting points 110a of the plurality of multi-cavity lasers 110 arranged on the laser blocks 180 and 182 is collimated by the collimating lens array 184, The light is condensed by the condensing lens 120 and enters the core 130 a of the multimode optical fiber 130. The laser light incident on the core 130a propagates in the optical fiber, is combined into one, and is emitted.
[0116]
As described above, this combined laser light source can achieve particularly high output by the multi-stage arrangement of multi-cavity lasers and the array of collimating lenses. By using this combined laser light source, a higher-intensity fiber array light source or bundle fiber light source can be configured, so that it is particularly suitable as a fiber light source constituting the laser light source of the irradiation head of the present embodiment.
[0117]
It should be noted that a laser module in which each of the above combined laser light sources is housed in a casing and the emission end portion of the multimode optical fiber 130 is pulled out from the casing can be configured.
[0118]
In the above embodiment, another optical fiber having the same core diameter as the multimode optical fiber and a cladding diameter smaller than the multimode optical fiber is coupled to the output end of the multimode optical fiber of the combined laser light source. However, for example, a multimode optical fiber having a cladding diameter of 125 μm, 80 μm, 60 μm, or the like can be used without coupling another optical fiber to the output end. Good.
[0119]
[Light distribution correction optical system]
In the above embodiment, the light amount distribution correcting optical system including a pair of combination lenses is used for the irradiation head. This light quantity distribution correcting optical system changes the light flux width at each exit position so that the ratio of the light flux width at the peripheral portion to the light flux width at the central portion close to the optical axis is smaller on the exit side than on the entrance side. When the parallel light beam from the light source is irradiated onto the DMD, the light quantity distribution on the irradiated surface of the DMD is corrected so as to be substantially uniform. Hereinafter, the operation of this light quantity distribution correcting optical system will be described.
[0120]
First, as shown in FIG. 27A, the case where the entire luminous flux width (total luminous flux width) H0 and H1 is the same for the incident luminous flux and the outgoing luminous flux will be described. In FIG. 27A, the portions denoted by reference numerals 51 and 52 virtually indicate the incident surface and the exit surface in the light amount distribution correcting optical system.
[0121]
In the light quantity distribution correcting optical system, it is assumed that the light flux widths h0 and h1 of the light beam incident on the central part near the optical axis Z1 and the light beam incident on the peripheral part are the same (h0 = hl). The light quantity distribution correcting optical system expands the light beam width h0 of the incident light beam in the central portion with respect to the light having the same light beam width h0 and h1 on the incident side, and conversely with respect to the incident light beam in the peripheral portion. Thus, the light beam width h1 is reduced. That is, the width h10 of the outgoing light beam at the center and the width h11 of the outgoing light beam at the periphery are set to satisfy h11 <h10. In terms of the ratio of the luminous flux width, the ratio “h11 / h10” of the luminous flux width in the peripheral portion to the luminous flux width in the central portion on the emission side is smaller than the ratio (h1 / h0 = 1) on the incident side ( (H11 / h10) <1).
[0122]
By changing the light flux width in this way, the light flux in the central part, which normally has a large light quantity distribution, can be utilized in the peripheral part where the light quantity is insufficient. In addition, the light quantity distribution on the irradiated surface of the DMD is made substantially uniform.
[0123]
The effects and effects of such a light quantity distribution correcting optical system are the same when the entire light flux width is changed between the incident side and the exit side (FIGS. 27B and 27C).
[0124]
FIG. 27B shows a case where the entire light flux width H0 on the incident side is “reduced” to the width H2 and emitted (H0> H2). Even in such a case, the light quantity distribution correcting optical system uses the light flux widths h0 and h1 that are the same on the incident side, and the light flux width h10 in the central portion is larger than that in the peripheral portion on the outgoing side. In addition, the light flux width h11 in the peripheral portion is made smaller than that in the central portion. Considering the reduction rate of the light beam, the reduction rate with respect to the incident light beam in the central part is made smaller than that in the peripheral part, and the reduction rate with respect to the incident light beam in the peripheral part is made larger than that in the central part. Also in this case, the ratio “H11 / H10” of the light flux width in the peripheral portion to the light flux width in the central portion is smaller than the ratio (h1 / h0 = 1) on the incident side ((h11 / h10) <1). .
[0125]
FIG. 27C shows a case where the entire light flux width H0 on the incident side is “enlarged” by a width Η3 and emitted (H0 <H3). Even in such a case, the light quantity distribution correcting optical system uses the light flux widths h0 and h1 that are the same on the incident side, and the light flux width h10 in the central portion is larger than that in the peripheral portion on the outgoing side. In addition, the light flux width h11 in the peripheral portion is made smaller than that in the central portion. Considering the expansion rate of the light beam, the expansion rate for the incident light beam in the central portion is made larger than that in the peripheral portion, and the expansion rate for the incident light beam in the peripheral portion is made smaller than that in the central portion. Also in this case, the ratio “h11 / h10” of the light flux width in the peripheral portion to the light flux width in the central portion is smaller than the ratio (h1 / h0 = 1) on the incident side ((h11 / h10) <1). .
[0126]
As described above, the light amount distribution correcting optical system changes the light beam width at each emission position, and the ratio of the light beam width in the peripheral part to the light beam width in the central part near the optical axis Z1 is larger on the outgoing side than on the incident side. Since the light has the same light flux width on the incident side, the light flux width in the central portion is larger than that in the peripheral portion, and the light flux width in the peripheral portion is larger than that in the central portion. Get smaller. As a result, it is possible to make use of the light beam at the center part to the peripheral part, and it is possible to form a light beam cross-section with a substantially uniform light amount distribution without reducing the light use efficiency of the entire optical system.
[0127]
Next, an example of specific lens data of a pair of combination lenses used as a light quantity distribution correcting optical system is shown. In this example, lens data in the case where the light amount distribution in the cross section of the emitted light beam is a Gaussian distribution as in the case where the light source is a laser array light source is shown. When one semiconductor laser is connected to the incident end of the single mode optical fiber, the light quantity distribution of the emitted light beam from the optical fiber becomes a Gaussian distribution. The present embodiment can also be applied to such a case. Further, the present invention can be applied to a case where the light amount in the central portion near the optical axis is larger than the light amount in the peripheral portion, for example, by reducing the core diameter of the multi-mode optical fiber and approaching the configuration of the single mode optical fiber.
[0128]
Table 1 below shows basic lens data.
[0129]
[Table 1]

[0130]
As can be seen from Table 1, the pair of combination lenses is composed of two rotationally symmetric aspherical lenses. If the light incident side surface of the first lens disposed on the light incident side is the first surface and the light exit side surface is the second surface, the first surface is aspherical. In addition, when the surface on the light incident side of the second lens disposed on the light emitting side is the third surface and the surface on the light emitting side is the fourth surface, the fourth surface is aspherical.
[0131]
In Table 1, the surface number Si indicates the number of the i-th surface (i = 1 to 4), the curvature radius ri indicates the curvature radius of the i-th surface, and the surface interval di indicates the i-th surface and the i + 1-th surface. The distance between surfaces on the optical axis is shown. The unit of the surface interval di value is millimeter (mm). The refractive index Ni indicates the value of the refractive index with respect to the wavelength of 405 nm of the optical element having the i-th surface.
[0132]
Table 2 below shows the aspheric data of the first surface and the fourth surface.
[0133]
[Table 2]

[0134]
The aspheric data is expressed by a coefficient in the following formula (A) that represents the aspheric shape.
[0135]
[Expression 1]

[0136]
In the above formula (A), each coefficient is defined as follows.
Z: Length of a perpendicular line (mm) drawn from a point on the aspheric surface at a height ρ from the optical axis to the tangent plane (plane perpendicular to the optical axis) of the apex of the aspheric surface
ρ: Distance from optical axis (mm)
K: Conic coefficient C: Paraxial curvature (1 / r, r: Paraxial radius of curvature)
ai: i-th (i = 3 to 10) aspheric coefficient In the numerical values shown in Table 2, the symbol “E” indicates that the subsequent numerical value is a “pick index” with 10 as the base. The numerical value represented by the exponential function with the base of 10 is multiplied by the numerical value before “E”. For example, “1.0E-02” indicates “1.0 × 10 ⁻² ”.
[0137]
FIG. 29 shows a light amount distribution of illumination light obtained by the pair of combination lenses shown in Tables 1 and 2 above. The horizontal axis indicates coordinates from the optical axis, and the vertical axis indicates the light amount ratio (%). For comparison, FIG. 28 shows a light amount distribution (Gaussian distribution) of illumination light when correction is not performed. As can be seen from FIG. 28 and FIG. 29, a light amount distribution that is substantially uniform is obtained by performing correction using the light amount distribution correcting optical system as compared with the case where correction is not performed. Thereby, laser annealing can be performed uniformly with uniform laser light without reducing the light use efficiency in the irradiation head.
[0138]
[Other imaging optics]
In the above embodiment, two sets of lenses are arranged as the imaging optical system on the light reflection side of the DMD used for the irradiation head, but the imaging optical system that enlarges the laser beam to form an image is arranged. Also good. By enlarging the cross-sectional area of the light beam reflected by the DMD, the irradiation area area on the irradiated surface can be expanded to a desired size.
[0139]
For example, as shown in FIG. 30A, the illumination head 144 irradiates the laser beam to the DMD 50, the illumination device 144 that irradiates the laser beam, the lens system 454, 458, the DMD 50 that enlarges the laser beam reflected by the DMD 50 and forms an image. A microlens array 472 in which a large number of microlenses 474 are arranged corresponding to each of the pixels, an aperture array 476 in which a large number of apertures 478 are provided corresponding to each microlens of the microlens array 472, and a laser that has passed through the aperture It can be configured by lens systems 480 and 482 that form an image of light on the exposed surface 56.
[0140]
In this irradiation head, when a laser beam is irradiated from the illumination device 144, the cross-sectional area of the light beam reflected by the DMD 50 in the ON direction is expanded several times (for example, two times) by the lens systems 454 and 458. . The expanded laser light is condensed corresponding to each pixel of the DMD 50 by each microlens of the microlens array 472, and passes through the corresponding aperture of the aperture array 476. The laser light that has passed through the aperture is imaged on the exposed surface 56 by the lens systems 480 and 482.
[0141]
In this imaging optical system, the laser light reflected by the DMD 50 is magnified several times by the magnifying lenses 454 and 458 and projected onto the scanning surface 56, so that the entire image area is widened. At this time, if the microlens array 472 and the aperture array 476 are not arranged, as shown in FIG. 30B, one pixel size (spot size) of each beam spot BS projected onto the scanning plane 56 is an irradiation area. It becomes large according to the size of 468, and the MTF (Modulation Transfer Function) characteristic indicating the sharpness of the irradiation area 468 is deteriorated.
[0142]
On the other hand, when the microlens array 472 and the aperture array 476 are arranged, the laser light reflected by the DMD 50 is condensed corresponding to each pixel of the DMD 50 by each microlens of the microlens array 472. Thereby, as shown in FIG. 30C, even when the irradiation area is enlarged, the spot size of each beam spot BS can be reduced to a desired size (for example, 10 μm × 10 μm), and the MTF characteristics are obtained. It is possible to perform high-definition exposure while preventing the deterioration of the above. Note that the irradiation area 468 is inclined because the DMD 50 is inclined and disposed in order to eliminate a gap between pixels.
[0143]
Even if the beam is thick due to the aberration of the microlens, the aperture can shape the beam so that the spot size on the scanning surface 56 becomes a constant size, and is provided corresponding to each pixel. By passing the formed aperture, crosstalk between adjacent pixels can be prevented.
[0144]
Furthermore, by using a high-intensity light source for the illumination device 144 as in the above embodiment, the angle of the light beam incident on each microlens of the microlens array 472 from the lens 458 is reduced, so that the light flux of adjacent pixels can be reduced. Part of the incident can be prevented. That is, a high extinction ratio can be realized.
[0145]
【The invention's effect】
The laser annealing apparatus of the present invention includes the spatial light modulation element, and has an effect that the high-speed and high-definition annealing can be performed by increasing the modulation speed of the spatial light modulation element.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an appearance of a laser annealing apparatus according to a first embodiment.
FIG. 2 is a perspective view showing a configuration of a scanner of the laser annealing apparatus according to the first embodiment.
FIG. 3A is a plan view showing an irradiated region formed on a photosensitive material, and FIG. 3B is a diagram showing an array of irradiation areas by each irradiation head.
FIG. 4 is a perspective view showing a schematic configuration of an irradiation head of the laser annealing apparatus according to the first embodiment.
5A is a cross-sectional view in the sub-scanning direction along the optical axis showing the configuration of the irradiation head shown in FIG. 4, and FIG. 5B is a side view of FIG.
FIG. 6 is a partially enlarged view showing a configuration of a digital micromirror device (DMD).
7A and 7B are explanatory diagrams for explaining the operation of the DMD. FIG.
FIGS. 8A and 8B are plan views showing the arrangement of scanning beams and the scanning lines in a case where the DMD is not inclined and in a case where the DMD is inclined. FIG.
9A is a perspective view showing a configuration of a fiber array light source, and FIG. 9B is a partially enlarged view of FIG. 9A.
FIG. 10 is a diagram showing a configuration of a multimode optical fiber.
FIG. 11 is a plan view showing a configuration of a combined laser light source.
FIG. 12 is a plan view showing the configuration of a laser module.
13 is a side view showing the configuration of the laser module shown in FIG. 12. FIG.
14 is a partial side view showing the configuration of the laser module shown in FIG. 12. FIG.
FIGS. 15A and 15B are cross-sectional views along the optical axis showing the difference between the focal depth of the low-luminance irradiation head and the focal depth of the high-luminance irradiation head.
FIGS. 16A and 16B are diagrams showing examples of DMD usage areas; FIGS.
FIG. 17A is a side view when the DMD use area is appropriate, and FIG. 17B is a cross-sectional view in the sub-scanning direction along the optical axis of FIG.
FIG. 18 is a plan view for explaining an annealing method for annealing a transparent substrate by one scanning with a scanner.
FIGS. 19A and 19B are plan views for explaining an annealing method for annealing a transparent substrate by scanning a plurality of times with a scanner. FIGS.
FIG. 20 is a perspective view showing a configuration of a laser array.
21A is a perspective view showing the configuration of a multi-cavity laser, and FIG. 21B is a perspective view of a multi-cavity laser array in which the multi-cavity lasers shown in FIG.
FIG. 22 is a plan view showing another configuration of the combined laser light source.
FIG. 23 is a plan view showing another configuration of the combined laser light source.
24A is a plan view showing another configuration of the combined laser light source, and FIG. 24B is a cross-sectional view taken along the optical axis of FIG.
FIGS. 25A and 25B are diagrams for explaining a low-temperature polysilicon TFT formation process; FIGS.
FIG. 26 is a diagram showing absorption characteristics of amorphous silicon.
FIG. 27 is an explanatory diagram of a concept of correction by a light amount distribution correction optical system.
FIG. 28 is a graph showing the light amount distribution when the light source has a Gaussian distribution and the light amount distribution is not corrected.
FIG. 29 is a graph showing a light amount distribution after correction by the light amount distribution correcting optical system.
30A is a cross-sectional view along the optical axis showing the configuration of another irradiation head having a different coupling optical system, and FIG. 30B is projected onto the scanning surface when a microlens array or the like is not used. It is a top view which shows a light image, (C) is a top view which shows the light image projected on a scanning surface when a microlens array etc. are used.
FIG. 31 is a side view showing a configuration of a fiber light source in which a semiconductor laser and an optical fiber are coupled on a one-to-one basis.
32 is a plan view of the fiber light source of FIG. 31 as viewed from above.
[Explanation of symbols]
LD1 to LD7 GaN-based semiconductor laser 10 Heat blocks 11 to 17 Collimator lens 20 Condensing lens 30 Multimode optical fiber 50 Digital micromirror device (DMD)
53 Reflected light image (scanning beam)
54, 58 Lens system 56 Scanning surface (annealed surface)
64 Laser module 66 Fiber array light source 68 Laser emitting unit 73 Combination lens 150 Transparent substrate 152 Stage 162 Scanner 166 Irradiation head 168 Irradiation area 170 Irradiated area

Claims (6)

A laser light source configured to generate a plurality of emission points for emitting a laser beam having a wavelength of 350 to 450 nm by at least one GaN-based semiconductor laser;
A plurality of pixel units each having a light modulation state that changes in response to a control signal are arranged on a substrate, and a spatial light modulation element that modulates a laser beam emitted from the laser light source;
Control means for controlling each of a plurality of pixel portions less than the total number of pixel portions arranged on the substrate by a control signal generated according to annealing information;
Scanning means for scanning the annealing surface with a laser beam modulated in each pixel portion;
Laser annealing equipment equipped with The laser annealing apparatus according to claim 1, wherein the laser light source is configured by any one of the following light sources (1) to (5).
(1) A plurality of GaN-based semiconductor lasers, one optical fiber, and a laser beam emitted from each of the plurality of GaN-based semiconductor lasers are condensed, and the condensed beam is coupled to an incident end of the optical fiber. And a condensing optical system.
(2) A combined laser light source in which the GaN semiconductor laser in the combined laser light source of (1) is constituted by a GaN-based multicavity laser having a plurality of light emitting points.
(3) A GaN-based multi-cavity laser having a plurality of light emitting points, one optical fiber, and a laser beam emitted from each of the plurality of light emitting points are condensed, and the condensed beam is collected from the optical fiber. And a converging optical system coupled to an incident end.
(4) A fiber array light source comprising a plurality of the combined laser light sources, each of the light emitting points at the emission end of the optical fiber of the plurality of combined laser light sources arranged in an array, or a fiber bundle arranged in a bundle light source.
(5) Condensing a single GaN-based semiconductor laser, one optical fiber, and a laser beam emitted from the single GaN-based semiconductor laser, and coupling the focused beam to the incident end of the optical fiber A plurality of fiber light sources, and a plurality of fiber light sources, each of the light emitting points at the output ends of the optical fibers of the plurality of fiber light sources arranged in an array, or in a bundle Fiber bundle light source. The laser annealing apparatus according to claim 2, wherein the optical fiber is an optical fiber having a uniform core diameter and a cladding diameter at an emission end smaller than a cladding diameter at an incident end. The laser annealing apparatus according to claim 2, wherein an emission end of the optical fiber is sealed. 5. The spatial modulation element according to claim 1, wherein the spatial modulation element is configured by a micromirror device in which a plurality of micromirrors each capable of changing an angle of a reflection surface according to a control signal are arranged in a two-dimensional manner on a substrate. The laser annealing apparatus according to any one of the above. Between the laser light source and the spatial modulation element,
A collimator lens for converting the light beam from the laser light source into a parallel light beam;
The light flux width at each exit position is changed so that the ratio of the light flux width at the peripheral portion to the light flux width at the central portion close to the optical axis is smaller on the exit side than on the entrance side, and the collimator lens changes the parallel light flux. A light amount distribution correction optical system that corrects the light amount distribution of the laser light that has been made to be substantially uniform on the irradiated surface of the spatial modulation element;
The laser annealing apparatus according to any one of claims 1 to 5, wherein:

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