准分子激光相位掩模法制备大晶粒尺寸多晶硅薄膜

为扩大晶粒尺寸并降低晶粒间界缺陷对多晶硅薄膜晶体管的不良影响,采用准分子激光相位掩模法制备了大晶粒尺寸的多晶硅薄膜。首先,在无相位掩模时利用不同能量密度的准分子激光晶化非晶硅薄膜,通过扫描电镜观测晶粒尺寸确定超级横向生长的能量窗口;然后,在该能量密度下采用周期为1 073 nm的相位掩模板对入射光束进行相位调制,在样品表面形成人工可控的横向温度梯度,使非晶硅熔化并横向生长结晶为多晶硅;最后,对薄膜特性进行测量,并与非晶硅薄膜和超级横向生长制备的多晶硅薄膜进行比较。结果表明:本文方法制作的薄膜的平均晶粒尺寸提高了一个数量级,达到了228.24 nm;薄膜电阻率降低一个数量级,为18.9 Ω·m;且晶粒分布规则有序。该方法能有效提高多晶硅薄膜的电学特性,适用于高质量多晶硅薄膜器件的制作。

Fabrication of large grain size p-Si film by phase modulated excimer laser crystallization

To enlarge the grain size and decrease the effect of the defect between the grain boundaries on a p-Si film transistor, a phase modulated excimer laser crystallization technique is used to fabricate the uniform p-Si film with a large grain size. First, an energy window for super lateral growth is determined by measuring the grain size of p-Si film fabricated with different laser energy intensities. Then, the spatial distribution of the input laser is modulated by a phase mask with a period of 1 073 nm and an artificially controlled lateral temperature gradient is induced on the a-Si film, which leads the a-Si to be melten and crystallized into p-Si grains by super lateral growth. Finally, the characteristics of the prepared p-Si film are measured and compared with those of the a-Si film and the p-Si film fabricated by super lateral growth technique. The results show that the grain size of the p-Si film is 228.24 nm, which is ten times of that fabricated by super lateral growth under the same processing parameters; the electrical resistivity of the prepared sample is 18.9 Ω·m, which is lower by an order magnitude than that prepared by super lateral growth. Furthermore, the distribution of the grain is more uniform than that fabricated by other techniques. The reported technique can increase the electrical characteristics of the p-Si film greatly and is suitable for the fabrication of high quality p-Si devices.