Compared with amorphous silicon thin film,polysilicon thin film has higher electron mobility and shows better electrical properties in the device.The method of preparing polycrystalline silicon thin film by pulsed laser crystallization of amorphous silicon thin film has the advantages of low thermal budget,little influence on the substrate and low cost.An experiment about laser crystallization of amorphous silicon thin films was carried out by using 532nm solid state nanosecond laser.To solve the problem of nonuniform effect when using Gaussian beam crystallization of amorphous silicon thin film,the circular Gauss beam was transformed into a linear flat top beam based on the beam shaping system.Then the effect of single pulse energy density,pulse number and thickness of amorphous silicon thin film on the crystallization of amorphous silicon thin film was investigated.The experimental results show that,linear flat top beam show better uniformity about laser crystallization of amorphous silicon thin film.For the 100nm amorphous silicon thin film crystal,with the increase of energy density,the grain becomes larger,until the surface is thermally damaged,and the largest grain size is about 1 μm × 500nm.And as the number of pulses increases,the surface roughness tends to decrease,and the minimum surface roughness is 2.38 nm.For 20 nm uhra-thin amorphous silicon film,only when the energy density is between 134mJ/cm2 and 167mJ/cm2,and the number of pulses is more than or equal to 8,the obvious crystallization effect can be observed.%多晶硅薄膜比非晶硅薄膜具有更高的电子迁移率,在器件中表现出更优良的性能,脉冲激光结晶非晶硅薄膜制备多晶硅薄膜的方法具有热积存小、对衬底影响小、成本低等优点.使用532 nm固体纳秒激光器进行了非晶硅薄膜激光结晶实验,为了解决直接使用高斯光束结晶时因光斑能量分布带来的结晶效果不均匀,首先基于光束整型系统将圆形的高斯光束整型成为线性平顶光束,而后研究单脉冲能量密度、脉冲个数、非晶硅薄膜厚度对结晶效果的影响.结果表明,线性平顶光束用于非晶硅薄膜结晶具有更好的均匀性,对于100 nm非晶硅薄膜,随着能量密度的增加,晶粒逐渐变大,直到表面出现热损伤,最大晶粒尺寸约为1 μm×500 nm.随着脉冲个数的增加,表面粗糙度有减小的趋势,观察到的最小粗糙度约为2.38 nm.对于20nm超薄非晶硅薄膜,只有当能量密度位于134 mnJ/cm2和167 mJ/cm2之间、脉冲个数大于或等于八个时才能观察到明显的结晶效果.
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