直拉重掺硼硅单晶的碱腐蚀特性研究

Properties Research of Alkaline Etching on Heavily Boron-doped Czochralski Silicon

直拉重掺硅硼单晶作为重要的外延衬底材料,具有其优越的特性。由于其硬度大,杂质含量高,在抛光片的加工过程中表现出腐蚀速率慢、表面均匀性差等特点,不利于硅片腐蚀减薄和抛光清洗等。研究了直拉重掺硅硼单晶的碱性腐蚀速率随腐蚀液温度和浓度变化趋势,从直拉重掺硅硼单晶化学反应的微观角度解释了这种变化规律,在此基础上,研究了不同的添加剂对腐蚀速率和表面均匀性的影响,从理论和实验两方面证实了,在腐蚀液中加入碱性氧化剂有利于腐蚀速率的提高,并能有效改善硅片的表面均匀性。

As an epitaxial material, heavily boron-doped Czochralski silicon has several superior characteristics. However, for the high hardness and the high impurity concentration in heavily boron-doped silicon ,the etching rate is low and surface uniformity is poor during the process, which affects wafers etching thinning and cleaning. In this paper, the alkaline etching rate variation with temperature and concentration is reasearched, and this variation rules is explained by microscopic chemical reaction. On this basis, the effect of the different additives on etching rate and surface uniformity is studied. The fact that alkaline oxidant can improve the etching rate and surface uniformity ,from both aspects of theory and experiment, is demonstrated.