底栅微晶硅薄膜晶体管

Study of Bottom-Gate μc-Si TFTs

对底栅微晶硅TFT的微晶硅材料生长孵化层问题进行了详细讨论,发现低硅烷浓度是减薄该层厚度的有效途径.同时又发现,以SiNx为栅绝缘层的底栅TFT,对随后生长的硅基薄膜有促进晶化的作用(约20%).沉积底栅TFT的微晶硅有源层时,必须计入该影响.因此为了获得良好的I-V特性,选用的硅烷浓度不宜低于3%.由硅基薄膜晶化体积比与系列沉积工艺条件关系和TFT所得薄膜晶化体积比的对比,可清晰证实SiNx对晶化的促进作用.

The incubation layer is the key factor in the growth of microcrystalline silicon （μc-Si） film used as the active layer of μc-Si TFT,which is confirmed by experimental results in detail. We find that decreasing the silicon concentration （Sc） is one effective way to thin the incubation layer. We also find that SiNx, used as the gate-insulator-layer of the bottom gate TFT,can increase （by about 20% ） the crystalline volume factor （Xc） of μc-Si thin film deposited thereon. Therefore,while depositing μc-Si on SiNx to fabricate the bottom gate TFT, this effect must be taken into account. As a result, to obtain excellent performance from a bottom-gate μc-Si TFT,the appropriate Sc for the active-layer must be no less than 3%. According to the relation between the Xc of μc-Si film and its deposition condition,it can be seen clearly that under the same deposition condition,the difference between the Xc value of μc-Si film deposited on glass and that on SiNx for the active layer in TFT is ～20% ,which indicates the augmenting role of SiNx in the crystalline growth of μc-Si thin film.