JP2009231746A - Method and apparatus for reforming polysilicon grain boundary - Google Patents

Method and apparatus for reforming polysilicon grain boundary Download PDF

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JP2009231746A
JP2009231746A JP2008078304A JP2008078304A JP2009231746A JP 2009231746 A JP2009231746 A JP 2009231746A JP 2008078304 A JP2008078304 A JP 2008078304A JP 2008078304 A JP2008078304 A JP 2008078304A JP 2009231746 A JP2009231746 A JP 2009231746A
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grain boundary
polycrystalline silicon
laser beam
crystal
pulse laser
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JP5574312B2 (en
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Naoya Kawamoto
直哉 河本
Masaki Miyoshi
正毅 三好
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Yamaguchi University NUC
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Abstract

<P>PROBLEM TO BE SOLVED: To reform polysilicon grain boundary using a laser beam by efficiently providing the grain boundary with a suitable energy without affecting a substrate portion and a crystalline portion. <P>SOLUTION: A method for reforming polysilicon grain boundary reforms the grain boundary by irradiating polysilicon with a pulse laser beam. The pulse laser beam is a visible light with a wavelength of ≥400 nm. The irradiation intensity of the pulse laser beam is an energy density under which the center of the polysilicon crystal grain is not melted. Preferably, the irradiation intensity of the pulse laser beam should be the energy density under which the vicinity of the polysilicon grain boundary is partially melted. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

本発明は、多結晶シリコンにレーザ光を照射してシリコン結晶の結晶粒界を改質するシリコン結晶成長方法及び装置に関する。   The present invention relates to a silicon crystal growth method and apparatus for modifying polycrystalline silicon grain boundaries by irradiating polycrystalline silicon with laser light.

液晶ディスプレイにおける画素のスイッチング等に用いられる薄膜トランジスタには、非晶質シリコン(アモルファスシリコン)が用いられてきた。図1は、液晶ディスプレイにおける薄膜トランジスタを表す図である。近年、薄膜トランジスタの材料として、非晶質シリコンより電子移動度やスイッチング特性の高い、多結晶シリコン(ポリシリコン)を用いられるようになってきた。多結晶シリコンを用いることでトランジスタを小さくすることができ、液晶ディスプレイの小型化や低消費電力化を図ることができる。多結晶シリコンを採用することにより、従来は外付けであったディスプレイを駆動するための回路をディスプレイ中に作り込むことが可能になるなど、ディスプレイの小型軽量化、低価格化を図る事が可能となる。良質な多結晶シリコンを生成するには、非晶質シリコンまたは多結晶シリコンにレーザ光を照射してレーザアニールを行い、結晶成長を促進させる必要がある。通常は紫外光レーザにより結晶を成長させるのであるが、紫外光レーザは結晶粒界部分だけでなく、すでに結晶になった部分にも吸収されてしまう。特に現在、ディスプレイの低価格化、及び軽量化の観点から望まれているプラスチック基板上に多結晶シリコンの薄膜トランジスタを製造するのは、吸収熱量が高くなり発熱により周囲に悪影響を及ぼすため、困難であった。この問題点を解決するために、本発明者は、紫外光レーザと、熱吸収が少ない可視光レーザとを効率よく組み合わせることにより、低温でも多結晶シリコンの結晶成長ができる方法を提案した(特願2007−111227号)。   Amorphous silicon has been used for a thin film transistor used for switching pixels in a liquid crystal display. FIG. 1 is a diagram illustrating a thin film transistor in a liquid crystal display. In recent years, polycrystalline silicon (polysilicon) having higher electron mobility and switching characteristics than amorphous silicon has been used as a material for thin film transistors. By using polycrystalline silicon, the transistor can be reduced, and the liquid crystal display can be reduced in size and power consumption. By adopting polycrystalline silicon, it is possible to reduce the size and weight of the display and reduce the price, for example, by making it possible to build a circuit for driving an external display in the display. It becomes. In order to produce high-quality polycrystalline silicon, it is necessary to irradiate laser light to amorphous silicon or polycrystalline silicon and perform laser annealing to promote crystal growth. Usually, the crystal is grown by an ultraviolet laser, but the ultraviolet laser is absorbed not only by the crystal grain boundary part but also by the already crystallized part. In particular, it is difficult to manufacture a polycrystalline silicon thin film transistor on a plastic substrate, which is currently desired from the viewpoint of reducing the price and weight of the display, because the amount of absorbed heat is high and the heat generation adversely affects the surroundings. there were. In order to solve this problem, the present inventor has proposed a method capable of crystal growth of polycrystalline silicon even at a low temperature by efficiently combining an ultraviolet laser and a visible light laser with low heat absorption (special feature). Application No. 2007-111227).

薄膜トランジスタの電気特性や信頼性は多結晶シリコンの結晶粒界の特性が大きな影響を与える。従来は、多結晶シリコンの大粒径化を行うこと、または、レーザ照射後、多結晶シリコンを水素雰囲気にて炉アニールを行い、粒界部分のダングリングボンドを水素終端することにより、粒界部分の及ぼす悪影響を低減してきた。通常、多結晶シリコンの大粒径化は紫外レーザを多結晶シリコンへ照射することにより行われるが、安価で軽量なことから実現が望まれるプラスチック基板上においては、十分な大粒径化を生じさせるのに必要なエネルギーをもつレーザ光を照射する、もしくは水素終端アニールを十分な温度で行うことは、プラスチックの軟化点が低いため、技術的な問題点となっていた。   The characteristics of the crystal grain boundaries of polycrystalline silicon have a great influence on the electrical characteristics and reliability of thin film transistors. Conventionally, the grain boundary of the grain boundary is increased by increasing the grain size of the polycrystalline silicon, or by annealing the polycrystalline silicon in a hydrogen atmosphere after the laser irradiation, and terminating the dangling bonds at the grain boundary part with hydrogen. The adverse effects of parts have been reduced. Usually, the grain size of polycrystalline silicon is increased by irradiating the polycrystalline silicon with an ultraviolet laser. However, on a plastic substrate that is desired to be realized because it is inexpensive and lightweight, the grain size is sufficiently increased. Irradiation with a laser beam having the energy required to perform the annealing or performing hydrogen termination annealing at a sufficient temperature has been a technical problem because the plastic has a low softening point.

従来技術としては、特許文献1乃至3がある。
特許文献1には、可視光及び紫外光のレーザを用いて、アモルファスシリコンの溶融多結晶化を行う技術が記載されている。しかしながら、特許文献1は可視光パルスレーザ及び紫外光パルスレーザを同時に照射するものであり、低温で多結晶シリコンの結晶粒界を改質する方法については記載されていない。
特許文献2には、異なる波長のレーザ光を異なるタイミングで照射するアニーリングが記載されている。しかしながら、特許文献2には可視光パルスレーザにより、低温で多結晶シリコンの結晶粒界を改質する方法については記載されていない。
特許文献3には、非晶質シリコンにレーザ照射して多結晶シリコンを形成する方法が記載されている。また、レーザ光の波長として、可視光であるYAGレーザの第2高調波を用いることも示唆されている(段落0016)。しかしながら、特許文献3は、多結晶シリコンの形成を主眼においているため、エネルギー密度の高いレーザ光を照射している。すでに結晶になった部分の溶融を抑え、少ないエネルギー密度で結晶粒界を改質することについては記載も示唆もされていない。
特開2000−12484号公報 特開昭56−29323号公報 特開2007−158372号公報
As conventional techniques, there are Patent Documents 1 to 3.
Patent Document 1 describes a technique for performing melt polycrystallization of amorphous silicon using visible and ultraviolet lasers. However, Patent Document 1 irradiates a visible light pulse laser and an ultraviolet light pulse laser at the same time, and does not describe a method for modifying a crystal grain boundary of polycrystalline silicon at a low temperature.
Patent Document 2 describes annealing in which laser beams having different wavelengths are irradiated at different timings. However, Patent Document 2 does not describe a method of modifying a crystal grain boundary of polycrystalline silicon at a low temperature with a visible light pulse laser.
Patent Document 3 describes a method of forming polycrystalline silicon by laser irradiation of amorphous silicon. It has also been suggested that the second harmonic of a YAG laser, which is visible light, be used as the wavelength of the laser light (paragraph 0016). However, since Patent Document 3 focuses on the formation of polycrystalline silicon, it irradiates a laser beam having a high energy density. There is no description or suggestion of suppressing the melting of the already crystallized portion and modifying the grain boundaries with a small energy density.
JP 2000-12484 A JP 56-29323 A JP 2007-158372 A

従来の多結晶シリコンの結晶成長方法は、多結晶シリコンの結晶部分の大粒径化を行うことに主眼がおかれていたが、既に結晶になった部分の結晶粒界の改質については特に考慮されていなかった。結晶粒界の改質には、レーザ照射後、多結晶シリコンを水素雰囲気にて炉アニールを行い、粒界部分のダングリングボンドを水素終端していたが、炉アニールは基板全体を熱してしまうため、プラスチック基板では行うことができない。
本発明は、レーザ光を用い、効率よく適度なエネルギーを結晶粒界に与えることにより、基板部分や既に結晶になった部分に影響を与えることなく、結晶粒界を改質する多結晶シリコン結晶粒界改質方法及び装置を提供することを目的とする。
Conventional polycrystalline silicon crystal growth methods have focused on increasing the grain size of the polycrystalline silicon crystal part, but the grain boundary modification of the already crystallized part is particularly important. It was not considered. For the grain boundary modification, after laser irradiation, polycrystalline silicon was subjected to furnace annealing in a hydrogen atmosphere, and dangling bonds at the grain boundary part were terminated with hydrogen, but the furnace annealing heated the entire substrate. Therefore, it cannot be performed with a plastic substrate.
The present invention provides a polycrystalline silicon crystal that uses a laser beam and efficiently modifies the grain boundary without affecting the substrate part or the already crystallized part by giving appropriate energy to the grain boundary. An object is to provide a grain boundary modification method and apparatus.

上記目的を達成するため、本発明は以下の構成を有する。
多結晶シリコンにパルスレーザ光を照射して結晶粒界の改質を行う多結晶シリコン結晶粒界改質方法であって、
前記パルスレーザ光は波長400nm以上の可視光であり、
前記パルスレーザ光の照射強度は、前記多結晶シリコンの結晶粒中心が溶融しないエネルギー密度である、
ことを特徴とする多結晶シリコン結晶粒界改質方法。
多結晶シリコンにパルスレーザ光を照射して結晶粒界の改質を行う多結晶シリコン結晶粒界改質装置であって、
波長400nm以上の可視光のパルスレーザ光を発生するパルスレーザ発生手段と、
前記パルスレーザ発生手段のパルスレーザ光の強度及び照射タイミングを制御する制御手段と、を有し、
前記パルスレーザ光の照射強度は、前記多結晶シリコンの結晶粒中心が溶融しないエネルギー密度である、
ことを特徴とする多結晶シリコン結晶粒界改質装置。
In order to achieve the above object, the present invention has the following configuration.
A polycrystalline silicon grain boundary modification method for modifying a grain boundary by irradiating polycrystalline silicon with a pulsed laser beam,
The pulse laser beam is visible light having a wavelength of 400 nm or more,
The irradiation intensity of the pulse laser beam is an energy density that does not melt the crystal grain center of the polycrystalline silicon.
A polycrystalline silicon grain boundary modification method characterized by the above.
A polycrystalline silicon grain boundary reforming apparatus for modifying grain boundaries by irradiating polycrystalline silicon with pulsed laser light,
Pulse laser generating means for generating pulsed laser light having a wavelength of 400 nm or more;
Control means for controlling the intensity and irradiation timing of the pulse laser beam of the pulse laser generating means,
The irradiation intensity of the pulse laser beam is an energy density that does not melt the crystal grain center of the polycrystalline silicon.
A polycrystalline silicon grain boundary reformer characterized by the above.

また、以下の好ましい実施態様がありうる。
前記多結晶シリコン結晶粒界改質方法は、レーザ光によるシリコン結晶成長方法の補助処理として行われ、前記シリコン結晶成長方法の、少なくとも、前処理、後処理、中間処理のいずれかとして行われる。
前記パルスレーザ光の照射強度は、前記多結晶シリコンの結晶粒界近傍が部分溶解するエネルギー密度である。
前記パルスレーザ光の照射を複数回繰り返し行う。
Further, there can be the following preferred embodiments.
The polycrystalline silicon crystal grain boundary modification method is performed as an auxiliary process of the silicon crystal growth method using laser light, and is performed as at least one of pre-processing, post-processing, and intermediate processing of the silicon crystal growth method.
The irradiation intensity of the pulse laser beam is an energy density at which the vicinity of the crystal grain boundary of the polycrystalline silicon is partially dissolved.
The pulsed laser light irradiation is repeated a plurality of times.

本発明は上記構成を採用したことにより、少ないエネルギーを結晶粒界に効率よく与えることにより、基板部分や既に結晶になった部分に影響を与えることなく、結晶粒界を改質することができる。照射レーザ光のエネルギー密度を必要最小限にしているため、基板部分の発熱を最小限に抑えることができ、プラスチック基板などの熱に弱い基板上の多結晶シリコンに対しても効率よく結晶粒界を改質することができる。
図2に、非晶質シリコン(a−Si)、多結晶シリコン(poly−Si)、結晶シリコン(c−Si)における、各波長の照射レーザ光の吸収率を示す。このグラフからわかるように、波長が400nm以上のレーザ光では、非晶質シリコンの吸収率は高いが、結晶シリコンの吸収率は極端に低い。本発明はこの性質を利用して、波長400nm以上の比較的弱いレーザ光を多結晶シリコンに照射することにより、既に結晶になっている部分をほとんど溶融することなく、非晶質シリコンが多く占めている結晶粒界部分のみを効率よく加熱することができる。これにより、結晶粒界部分のみを選択的に加熱することができるので、基板全体を加熱することなく結晶粒界の改質を効率よく行うことができる。
By adopting the above configuration, the present invention can modify the crystal grain boundary without affecting the substrate part or the already crystallized part by efficiently giving less energy to the crystal grain boundary. . Since the energy density of the irradiated laser light is minimized, heat generation at the substrate can be minimized, and even for polycrystalline silicon on heat-sensitive substrates such as plastic substrates, the grain boundaries can be efficiently Can be modified.
FIG. 2 shows the absorptance of irradiated laser light of each wavelength in amorphous silicon (a-Si), polycrystalline silicon (poly-Si), and crystalline silicon (c-Si). As can be seen from this graph, in the laser light having a wavelength of 400 nm or more, the absorption rate of amorphous silicon is high, but the absorption rate of crystalline silicon is extremely low. The present invention utilizes this property to irradiate polycrystalline silicon with a relatively weak laser beam having a wavelength of 400 nm or more, so that amorphous silicon occupies a large amount without almost melting the already crystallized portion. It is possible to efficiently heat only the crystal grain boundaries. Thereby, since only the crystal grain boundary part can be selectively heated, the crystal grain boundary can be efficiently modified without heating the whole substrate.

以下、図面を用いて本発明の実施形態について説明する。
図2は、多結晶シリコン、非晶質シリコン及び結晶シリコンの、レーザ光の吸収率の波長依存性を表すグラフである。図2からわかるように、非晶質シリコン(a−Si)は紫外光及び可視光で高い吸収特性を有するのに対し、結晶シリコン(c-Si)は紫外光では高い吸収特性を有するものの波長400nm以上の可視光はほとんど吸収しない。
図3は、多結晶シリコンに、可視光レーザ(波長532nm)を照射した場合の吸収状態を表す図である。可視光は、図2に示されるとおり、結晶シリコン(c−Si)部分ではほとんど吸収されないが、非晶質シリコン(a−Si)では多く吸収されるため、非晶質シリコン(a−Si)の特性を持つ結晶粒界部分のみに効率よくレーザが吸収され、発熱量も小さい。全体的な加熱量は小さいため結晶成長には不十分であるが、結晶粒界の結晶欠陥を低減したり、結晶粒界の移動を促進して結晶粒を大きくすることができる。
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 2 is a graph showing the wavelength dependence of the absorption rate of laser light of polycrystalline silicon, amorphous silicon, and crystalline silicon. As can be seen from FIG. 2, amorphous silicon (a-Si) has a high absorption characteristic in ultraviolet light and visible light, whereas crystalline silicon (c-Si) has a high absorption characteristic in ultraviolet light. Visible light of 400 nm or more is hardly absorbed.
FIG. 3 is a diagram illustrating an absorption state when polycrystalline silicon is irradiated with a visible light laser (wavelength 532 nm). As shown in FIG. 2, visible light is hardly absorbed in the crystalline silicon (c-Si) portion, but is absorbed much in the amorphous silicon (a-Si). The laser is efficiently absorbed only in the crystal grain boundary portion having the above characteristics, and the heat generation amount is small. Although the overall heating amount is small, it is insufficient for crystal growth, but crystal defects at the crystal grain boundary can be reduced, or the crystal grain can be enlarged by promoting the movement of the crystal grain boundary.

本発明の実施形態の1つとして、YAGレーザの第2高調波(波長532nm)を用いて、多結晶シリコンの結晶粒界の改質を行った。図4及び図5に、本実施形態の方法により、多結晶シリコン基板の結晶粒界の改質を行った実験結果を示す。図4は、本実施形態の結晶粒界の改質方法により形成された基板を、電子スピン共鳴(ESR)により不対電子量(スピン密度)を測定した結果である。スピン密度が小さいほど、結晶欠陥が少ないことを意味している。このグラフからわかるように、400mJ/cm程度のエネルギー密度のレーザ光でも結晶欠陥が低減しており、結晶粒の中心付近が溶融しないようなエネルギー密度の小さな可視光レーザでも十分に結晶欠陥を低減できることがわかる。
また、図5は、この実験により形成した基板のSEM像である。この図からわかるように、レーザ光のエネルギー密度が400mJ/cmでショット数が99shotのときに最も結晶が成長している。これは、エネルギー密度の高さにより結晶粒界の改質効果が高かったことにもよるが、ショット数が多いほど結晶粒界の改質効果が高いことが本発明の特有の効果である。本発明の構成により少ないエネルギー密度で少しずつ結晶粒界の改質を行うことができるため、多結晶シリコン全体を加熱することなく低温で多結晶シリコンの結晶粒界の改質を行うことができる。
As one embodiment of the present invention, the grain boundary of polycrystalline silicon was modified using the second harmonic (wavelength of 532 nm) of a YAG laser. FIG. 4 and FIG. 5 show the results of experiments in which the grain boundaries of the polycrystalline silicon substrate were modified by the method of this embodiment. FIG. 4 shows the results of measuring the amount of unpaired electrons (spin density) by electron spin resonance (ESR) of the substrate formed by the grain boundary modification method of this embodiment. A smaller spin density means fewer crystal defects. As can be seen from this graph, crystal defects are reduced even with a laser beam having an energy density of about 400 mJ / cm 2 , and even a visible light laser with a small energy density that does not melt in the vicinity of the center of the crystal grains can sufficiently exhibit crystal defects. It can be seen that it can be reduced.
FIG. 5 is an SEM image of the substrate formed by this experiment. As can be seen from this figure, the crystal is most grown when the energy density of the laser beam is 400 mJ / cm 2 and the number of shots is 99 shots. This is due to the fact that the grain boundary modification effect is high due to the high energy density, but the grain boundary modification effect is higher as the number of shots is larger. Since the grain boundary can be modified little by little with a low energy density, the grain boundary of polycrystalline silicon can be modified at a low temperature without heating the entire polycrystalline silicon. .

上述の例では、結晶粒界における結晶欠陥の低減について説明したが、多結晶シリコンの結晶成長のステージによっては(例えば、結晶粒がまだ小さい段階)、本実施形態の結晶粒界改善方法により、多結晶シリコンの結晶粒の成長を促進させることができる。二次元結晶成長の駆動力ΔFは、以下の式により表される。
(Δγ:表面エネルギー異方性、h:膜厚、γgb:粒界エネルギー、r:二次元結晶粒径、r:膜厚程度の結晶粒径)
多結晶シリコン薄膜における結晶欠陥の支配的な位置は結晶粒界、且つ多結晶シリコン薄膜における内部応力は結晶欠陥数に依存することから、ESRにより定量された不対電子数は、応力場をもつ転位に由来するものである。つまり、図4で示した結果は、結晶粒界を溶融しない程度に選択加熱することで歪エネルギーである粒界エネルギーγgbが減少することを示している。
≒rの場合、つまり二次元結晶成長初期における結晶成長の駆動力は次式で表される。
式(数2)からわかるように、二次元結晶成長の初期の場合、粒界エネルギーγgbに関する第二項目は二次元結晶成長の駆動力ΔFに対しマイナス、つまり抑止力として働く。このため、二次元結晶成長の初期においては、結晶粒界を溶融しない程度に選択加熱することで結晶粒界における結晶欠陥を低減し、その駆動力向上(抑止力低下)による結晶成長の促進を図ることが可能となる。図5に示す多結晶シリコン粒の大粒径化は、以上により生じたものであると考えられる。
しかし、結晶成長が進むことで、rが大きくなり式(数1)における第三項目が第二項目より小さくなることで、粒界エネルギーγgbは二次元結晶成長の駆動力ΔFに対しプラスに、つまり駆動力として働く。このため、二次元結晶成長の初期以降においては、結晶粒界を部分溶融により選択加熱することで、結晶粒界における結晶欠陥を増加させ、その駆動力向上による結晶成長の促進を図ることが可能となる。図4に示すように533mJ/cm程度のエネルギー密度のレーザ光を照射し、多結晶シリコン薄膜の一部を溶融させることで結晶欠陥数を増加させることにより、多結晶シリコン粒の大粒径化が可能となる。
二次元結晶成長の駆動力ΔFは、図6に示すように結晶粒界の移動を促進するので、結果的に結晶成長が促進される。粒界の移動度νは、以下の式により表せる。
(Q:活性化エネルギー、k:ボルツマン定数、T:粒界温度)
ちなみに、式(数1)からわかるように、二次元結晶粒径rが大きいときは、粒界エネルギーγgbの減少しても二次元結晶成長の駆動力ΔFが大きくならない。したがって、結晶粒径が大きいときは、可視光レーザ照射エネルギーは主に結晶欠陥の低減に用いられる。
In the above-described example, reduction of crystal defects in the crystal grain boundary has been described. However, depending on the stage of crystal growth of polycrystalline silicon (for example, the stage where the crystal grain is still small), the crystal grain boundary improving method of the present embodiment The growth of crystal grains of polycrystalline silicon can be promoted. The driving force ΔF for two-dimensional crystal growth is expressed by the following equation.
(Δγ: surface energy anisotropy, h: film thickness, γ gb : grain boundary energy, r s : two-dimensional crystal grain size, r n : crystal grain size of about the film thickness)
Since the dominant position of crystal defects in the polycrystalline silicon thin film is the grain boundary, and the internal stress in the polycrystalline silicon thin film depends on the number of crystal defects, the number of unpaired electrons determined by ESR has a stress field. It originates from dislocations. That is, the results shown in FIG. 4 indicate that the grain boundary energy γ gb, which is the strain energy, is reduced by selectively heating the crystal grain boundaries so as not to melt.
In the case of r n ≈r s , that is, the driving force of crystal growth at the initial stage of two-dimensional crystal growth is expressed by the following equation.
As can be seen from the equation (Equation 2), in the initial stage of the two-dimensional crystal growth, the second item regarding the grain boundary energy γ gb acts as a minus, ie, a deterrent, to the driving force ΔF of the two-dimensional crystal growth. For this reason, at the initial stage of two-dimensional crystal growth, crystal defects at the grain boundaries are reduced by selective heating to such an extent that the grain boundaries are not melted, and crystal growth is promoted by improving the driving force (decreasing deterrence). It becomes possible to plan. The increase in the grain size of the polycrystalline silicon grains shown in FIG. 5 is considered to be caused by the above.
However, the crystal growth proceeds, that the third entry is less than the second item in the r s increases and the expression (Expression 1), the grain boundary energy gamma gb plus with the driving force ΔF of the two-dimensional crystal growth In other words, it works as a driving force. For this reason, after the initial stage of two-dimensional crystal growth, it is possible to increase the crystal defects at the crystal grain boundary by promoting selective growth of the crystal grain boundary by partial melting and to promote crystal growth by improving the driving force. It becomes. As shown in FIG. 4, by irradiating a laser beam having an energy density of about 533 mJ / cm 2 and melting a part of the polycrystalline silicon thin film to increase the number of crystal defects, Can be realized.
The driving force ΔF for the two-dimensional crystal growth promotes the movement of the crystal grain boundary as shown in FIG. 6, and as a result, the crystal growth is promoted. The mobility ν of the grain boundary can be expressed by the following formula.
(Q: activation energy, k: Boltzmann constant, T: grain boundary temperature)
Incidentally, as can be seen from equation (1), when the large two-dimensional grain diameter r s, the driving force ΔF also two-dimensional crystal growth by a decrease in grain boundary energy gamma gb is not increased. Therefore, when the crystal grain size is large, the visible light laser irradiation energy is mainly used for reducing crystal defects.

具体的には、図4からわかるように、レーザ光のエネルギー密度が400mJ/cm程度のとき、最も結晶欠陥数の減少が見られる。また、さらにエネルギー密度が533mJ/cm程度になると、結晶粒界の一部が溶解してむしろ結晶欠陥数が増加し、結晶粒界の移動が促進されるので、結果的に結晶成長が促進される。なお、結晶粒界の改質は小さなエネルギー密度でも起き、実験により少なくとも66mJ/cm程度のエネルギー密度でも結晶粒界の改質が起きることを確認している。 Specifically, as can be seen from FIG. 4, the number of crystal defects is most reduced when the energy density of the laser beam is about 400 mJ / cm 2 . Further, when the energy density is about 533 mJ / cm 2 , a part of the crystal grain boundary is dissolved and the number of crystal defects is rather increased, and the movement of the crystal grain boundary is promoted. As a result, the crystal growth is promoted. Is done. The grain boundary modification occurs even at a small energy density, and it has been confirmed by experiments that the grain boundary modification occurs even at an energy density of at least about 66 mJ / cm 2 .

図7は、本実施形態の多結晶シリコン結晶粒界改質方法の照射タイミングを説明する図である。本実施形態の多結晶シリコン結晶粒界改質方法は単独で用いても良いが、従来の多結晶シリコンの結晶成長方法と組み合わせることでより高い効果が得られる。図7(A)は、本発明者による紫外光レーザと可視光レーザとを組み合わせた従来の結晶成長方法(特願2007−111227号)である。本実施形態の多結晶シリコン結晶粒界改質方法の適用方法としては、図7(B)のように、従来の結晶成長方法の前処理(最初のパルスレーザ印加前)、中間処理(パルスレーザとパルスレーザの間)、後処理(全てのパルスレーザ印加後)などが考えられる。   FIG. 7 is a view for explaining the irradiation timing of the polycrystalline silicon crystal grain boundary modification method of the present embodiment. The polycrystalline silicon crystal grain boundary modification method of this embodiment may be used alone, but a higher effect can be obtained by combining it with a conventional polycrystalline silicon crystal growth method. FIG. 7A shows a conventional crystal growth method (Japanese Patent Application No. 2007-111227) in which the inventors have combined an ultraviolet laser and a visible laser. As an application method of the polycrystalline silicon crystal grain boundary modification method of the present embodiment, as shown in FIG. 7B, a pretreatment of a conventional crystal growth method (before applying the first pulse laser), an intermediate treatment (pulse laser). And post-processing (after application of all pulse lasers) and the like.

以上、本発明の実施形態の一例を説明したが、本発明はこれに限定されるものではなく、特許請求の範囲に記載された技術的思想の範疇において各種の変更が可能であることは言うまでもない。   Although an example of the embodiment of the present invention has been described above, the present invention is not limited to this, and it goes without saying that various modifications can be made within the scope of the technical idea described in the claims. Yes.

液晶ディスプレイの薄膜トランジスタを表す図。The figure showing the thin-film transistor of a liquid crystal display. 非晶質シリコン、多結晶シリコン、結晶シリコンの吸収特性を表すグラフ。A graph showing absorption characteristics of amorphous silicon, polycrystalline silicon, and crystalline silicon. 多結晶シリコンへの可視光の吸収を表す図。The figure showing absorption of visible light to polycrystalline silicon. 本実施形態における実験結果(スピン密度)を表す図。The figure showing the experimental result (spin density) in this embodiment. 本実施形態における実験結果(SEM像)を表す図。The figure showing the experimental result (SEM image) in this embodiment. 本実施形態における結晶成長を説明する図。The figure explaining the crystal growth in this embodiment. 本実施形態におけるパルスレーザ光の照射タイミングを説明する図。The figure explaining the irradiation timing of the pulse laser beam in this embodiment.

Claims (5)

多結晶シリコンにパルスレーザ光を照射して結晶粒界の改質を行う多結晶シリコン結晶粒界改質方法であって、
前記パルスレーザ光は波長400nm以上の可視光であり、
前記パルスレーザ光の照射強度は、前記多結晶シリコンの結晶粒中心が溶融しないエネルギー密度である、
ことを特徴とする多結晶シリコン結晶粒界改質方法。
A polycrystalline silicon grain boundary modification method for modifying a grain boundary by irradiating polycrystalline silicon with a pulsed laser beam,
The pulse laser beam is visible light having a wavelength of 400 nm or more,
The irradiation intensity of the pulse laser beam is an energy density that does not melt the crystal grain center of the polycrystalline silicon.
A polycrystalline silicon grain boundary modification method characterized by the above.
前記多結晶シリコン結晶粒界改質方法は、レーザ光によるシリコン結晶成長方法の補助処理として行われ、前記シリコン結晶成長方法の、少なくとも、前処理、後処理、中間処理のいずれかとして行われる、
ことを特徴とする請求項1記載の多結晶シリコン結晶粒界改質方法。
The polycrystalline silicon crystal grain boundary modification method is performed as an auxiliary process of the silicon crystal growth method by laser light, and is performed as at least one of pre-processing, post-processing, and intermediate processing of the silicon crystal growth method.
The polycrystalline silicon grain boundary modification method according to claim 1, wherein:
前記パルスレーザ光の照射強度は、前記多結晶シリコンの結晶粒界近傍が部分溶解するエネルギー密度である、
ことを特徴とする請求項1または2記載の多結晶シリコン結晶粒界改質方法。
The irradiation intensity of the pulsed laser light is an energy density at which the vicinity of a crystal grain boundary of the polycrystalline silicon is partially dissolved.
The polycrystalline silicon crystal grain boundary modification method according to claim 1 or 2, wherein:
前記パルスレーザ光の照射を複数回繰り返し行う、
ことを特徴とする請求項1乃至3いずれか記載の多結晶シリコン結晶粒界改質方法。
The pulsed laser light irradiation is repeated a plurality of times.
The polycrystalline silicon crystal grain boundary modification method according to any one of claims 1 to 3.
多結晶シリコンにパルスレーザ光を照射して結晶粒界の改質を行う多結晶シリコン結晶粒界改質装置であって、
波長400nm以上の可視光のパルスレーザ光を発生するパルスレーザ発生手段と、
前記パルスレーザ発生手段のパルスレーザ光の強度及び照射タイミングを制御する制御手段と、を有し、
前記パルスレーザ光の照射強度は、前記多結晶シリコンの結晶粒中心が溶融しないエネルギー密度である、
ことを特徴とする多結晶シリコン結晶粒界改質装置。
A polycrystalline silicon grain boundary reforming apparatus for modifying grain boundaries by irradiating polycrystalline silicon with pulsed laser light,
Pulse laser generating means for generating pulsed laser light having a wavelength of 400 nm or more;
Control means for controlling the intensity and irradiation timing of the pulse laser beam of the pulse laser generating means,
The irradiation intensity of the pulse laser beam is an energy density that does not melt the crystal grain center of the polycrystalline silicon.
A polycrystalline silicon grain boundary reformer characterized by the above.
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103081065A (en) * 2010-08-31 2013-05-01 株式会社日本制钢所 Laser annealing device and laser annealing method

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0864526A (en) * 1994-08-24 1996-03-08 Sony Corp Modifying method of material by photo-irradiation and manufacture of semiconductor device
JP2000260731A (en) * 1999-03-10 2000-09-22 Mitsubishi Electric Corp Method and equipment for laser heat treatment and semiconductor device
JP2002367904A (en) * 2000-06-12 2002-12-20 Seiko Epson Corp Method of manufacturing thin film semiconductor device
JP2002367905A (en) * 2001-04-06 2002-12-20 Seiko Epson Corp Method of manufacturing thin film semiconductor device
JP2005347694A (en) * 2004-06-07 2005-12-15 Sharp Corp Method and device for manufacturing semiconductor thin film
KR100740124B1 (en) * 2006-10-13 2007-07-16 삼성에스디아이 주식회사 Poly silicon thin film transistor and the method therefor

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0864526A (en) * 1994-08-24 1996-03-08 Sony Corp Modifying method of material by photo-irradiation and manufacture of semiconductor device
JP2000260731A (en) * 1999-03-10 2000-09-22 Mitsubishi Electric Corp Method and equipment for laser heat treatment and semiconductor device
JP2002367904A (en) * 2000-06-12 2002-12-20 Seiko Epson Corp Method of manufacturing thin film semiconductor device
JP2002367905A (en) * 2001-04-06 2002-12-20 Seiko Epson Corp Method of manufacturing thin film semiconductor device
JP2005347694A (en) * 2004-06-07 2005-12-15 Sharp Corp Method and device for manufacturing semiconductor thin film
KR100740124B1 (en) * 2006-10-13 2007-07-16 삼성에스디아이 주식회사 Poly silicon thin film transistor and the method therefor

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103081065A (en) * 2010-08-31 2013-05-01 株式会社日本制钢所 Laser annealing device and laser annealing method

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