Cl_2和SF_6混合气体对a-Si刻蚀反应的研究

Optimization of Cl_2 and SF_6 Flow Rates in Reactive Ion Etching of Amorphous-Si on Industrial Scale

对薄膜晶体管(TFT)像素区域的非晶Si(a-Si)进行刻蚀是TFT-LCD行业的主要工艺之一,通常在电容耦合射频真空放电设备中采用Cl2和SF6作为刻蚀反应气体实现。为了保证刻蚀速率并节省工艺循环时间,同时又控制用气成本,需要获取最佳的气体使用量。本文通过调整Cl2和SF6的用量,研究了a-Si的刻蚀速率和均匀性的变化关系。研究表明,当Cl2用量大于5000 m L/min时,刻蚀速率无明显变化;当SF6少量增加时也能够加速a-Si刻蚀。同时,通过光谱分析系统对a-Si和光刻胶的刻蚀反应进行了分析,与刻蚀率测试结果相同。

The impact of the C12 and SF6 flow rates on reactive ion etching of the amorphous-Si, in fabrication of thin film transistor of liquid crystal display in the capacitive coupled RF discharge reactor on industrial scale, was experimen- tally investigated to optimize the RIE etching rate, etching time and cost. The major variables, including the etching rate, etching uniformity, loss of photo-resist and plasma reactivity, were evaluated with the end point detector system of Semisysco. When reducing only the C12 flow rate by 1000 mL/min in the mixture, its etching rate decreased by less than 4% in 8000-4000 mL/min range,but decreased by more than 10% in 4000 ~ 2000 mL/min range;whereas when in- creasing only the SF6 flow rate by 100 mL/min in 150- 450 mL/min range,its etching rate increased by about 5% ,ac- companied by an increased etching of photo-resist, especially when the SF6 flow rate accounted for less than 6% in the mixture.