thank you Andrew, I also think the sputtering Cr film should have lots of problem. But the Sputtering is the only way to deposit Cr in our lab. i think what if i change the recipe of the sputtering, the film could become more dense. On Tue, Dec 14, 2010 at 12:04 AM, Andrew Saranganwrote: > Most likely Cr has pin holes in the film and the HF is penetrating > through it. Sputtered Cr is particularly prone to developing pin > holes. I've had better luck with evaporated Cr. -- Yan Xin -Pen-Tung Sah MEMS Research Center, -Xiamen University, CHINA XMU HOME: http://memsc.xmu.edu.cn/mems_renchaiduiwu/XuYuan_Chen-Group/index_1.html