用于LDD和SST的SiO2边墙干法腐蚀工艺研究

本文从干法腐蚀角度出发,首先从数学上分析了多晶硅角度,SiO_2边墙的宽度和高度,衬底损失与各工艺参数间的关系,指出边墙的宽度和高度分别取决于多晶硅的角度和过腐蚀量。在Tegal1512e设备上,采用Cl_2、SF_6、N_2混合气体,开发了多晶硅干法腐蚀工艺,讨论了LDD的正胶掩膜及SST的SiO_2掩膜对工艺的不同影响。SEM分析发现了SF_6气体腐蚀的各向同性。在Tegal903e设备上,采用CHF_3、SF_6、He混合气体,开发了SiO_2边墙干法腐蚀工艺,研究了腐蚀的各向异性,辐射损伤,选择比,均匀性及重复性的控制方法。取得的工艺结果为,腐蚀速率(?)_(sio_2)≈400nm/min,均匀性U≤±5％,选择比S_(f8)>10,工序能力指数C_p>1。

A Dry Etch Technology for SiO2 Sidewall in LDD and SST Device Structures

For dry etching, the dependence of the poly-silicon angle, the width and height of SiO2 sidewalls and the substrate loss on various process parameters is mathematically analyzed in the paper. It has been shown that the width and height of SiO2 sidewalls are determined by the poly-silicon angle and the the amount of overetching, respectively. A dry etch technology for poly-silicon using Cl2, SF6 and N2 mixed gas has been developed on Tegal 1512e. Different effects of positive resist mask for LDD and SiO2 mask for SST on the process are discussed. Isotropy in SF6 was observed through SEM analysis. Dry etch process for SiO2 using CHFs, SF6 and He has been developed on Tegal 903e. Techniques to control the anisotropy, radiation damage, selectivity, uniformity and reproducibility were examined. An etch rate Rsio2=400nm/min was achieved, with uniformity U<5%, selectivity Sf5>10 and process capability index Cp>l.