hi i am doing BHF etch on silicon dioxide deposited on silicon wafer. i am using 5:1 BHF etchant etch rate 120 nm/min i want to etch 1 micron deeep channel with 200 micron width. there are multiple channels in parallel each seprated by 6 micron. so i diped my sample in BHF for 8.33 min but after the etch no channels was formed and everything is etched away. can anyone tell me what could be the problem ??? -- Kamlesh Pawar M.Tech (Biomedical Engg) Mob :+919870062960 IIT-Bombay