用于各向同性湿法刻蚀中的氮化硅掩膜

The Silicon Nitride Mask for Isotropic Wet Etching

摘要:

在硅的各向同性湿法刻蚀过程中,一般选用HNA溶液(即氢氟酸、硝酸和乙酸的混合溶液)作为刻蚀液,而氮化硅以其很好的耐刻蚀性而优先被选为顶层掩膜材料。在硅片上刻蚀不同的结构,通常需要选择不同的刻蚀液配比。而不同配比对于氮化硅掩膜的刻蚀速率也不一样。分别用PECVD和LPCVD两种方法在〈111〉型硅片上沉积了厚度为560和210nm的氮化硅薄膜,研究和对比了它们在8种典型配比刻蚀液下的刻蚀速率,为合理制作所需要厚度的氮化硅掩膜提供有益参考。

Abstract:

During the isotropic etching of silicon, hydrofluoric acid-nitric acid-acetic acid (HNA) solution is generally used as the etching liquor, and silicon nitride is preferentially choosen as the top mask material for its good etching resistance. To etching different structures on a silicon wafer depends on the ratio of the prepared HNA solution. However, the etching rates of silicon nitride mask in the solution of different proportions are not the same. PECVD and LPCVD methods were used to deposit a silicon nitride film on the 〈111〉 type silicon respectively, and the thickness of the deposited SiN film is 560 and 210nm, respectively. Their etching rates in the etchant of eight typical proportions were studied and compared, which provides a useful reference for depositing the desired thickness of the silicon nitride mask.