Auxiliary laser crystallization method for making polysilicon

Abstract

This invention relates to assistant laser crystal method, which comprises the following steps: forming non-crystal silicon layer on baseboard; then forming one thermal band in the non-crystal silicon layer, wherein, by control of thickness of the band, the band has one reflection thickness to lower non-crystal silicon melt threshold energy; Finally processing laser heating and crystal process to make the non-crystal into multi-crystal, wherein, the part laser energy passes thermal band to melt non-crystal layer with part laser energy in the ban to heat up non-crystal layer.

Description

technical field [0001] The present invention relates to a method for assisting laser crystallization, and in particular to a method for assisting laser crystallization which is applied to the production of polysilicon and has thermal retention characteristics and anti-reflection capabilities. Background technique [0002] Poly-silicon (poly-silicon) has been widely valued in the manufacture of thin-film transistors in recent years because of its electrical characteristics superior to amorphous silicon and cost considerations lower than that of single-crystal silicon, especially in thin-film transistors driving liquid crystal displays. (TFT-LCD) applications. [0003] However, the grain size of polysilicon crystals has a great influence on electron mobility and device characteristics. Among them, the grain-boundary existing in polysilicon is more constitutive of the carrier passing through the gate in the device. Obstacles in extreme passage. Therefore, how to increase the ...

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Problems solved by technology

However, the crystal grains of polysilicon formed by the above-mentioned solid phase crystallization method or direct vapor deposition method are quite small, with a particle size of only about 100nm. Therefore, the properties of polysilicon thin films formed by these methods are not good.

[0005] At present, the Excimer Laser Anneal (ELA) technology is most commonly used in the production of polysilicon thin films. Although the polysilicon grain size that can be obtained can reach about 600nm, for the development of higher performance planar The display is still not enough

Moreover, the general excimer laser tempering technology must use a high repetition rate irradiation method to improve the shortcomings of the excimer laser's uneven laser energy distribution and unstable energy output. However, the high repetition rate irradiation quasi The molecular laser tempering process will lead to an increase in production costs and accelerate the aging rate of laser optical components

In addition, the problem of unstable laser energy output will also make the optimal process window of laser operating energy very small, generally only about tens of mJ / cm 2

[0006] Although many methods for increasing the grain size of polycrystalline silicon have been proposed in recent years, such as Sequential Lateral Solidification (SLS) or Phase Modulated Excimer Laser Tempering (Phase Modulated ELA; PMELA), these technologies It is necessary to partially modify the existing laser system, and there are still technical problems to be solved

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