Improved Silicon Nitride Isotropic Etch for Trench Local Oxidation Process
Original Publication Date: 2000-Feb-01
Included in the Prior Art Database: 2003-Jun-19
The process flow will be described by reference to the drawing which shows a silicon structure referenced 10. A trench 11 is etched into silicon substrate 12. A thin (2 nm) silicon oxide layer 13 and a thin (5nm) silicon nitride (Si3N4) layer 14 are deposited on the structure by LPCVD . Next, 2µ thick resist layer 15 is blanket deposited onto the structure 10 to fill the trench 11 in excess, then recessed to the desired depth (1.2 µm). At this stage of the process, the Si3N4 layer 14 in trench 11 must be etched without affecting the resist layer 15 and the oxide layer 13. To that end, an improved selective etch process has been developed which is particulary adapted for use with the isotropic etch chamber of a RPS system manufactured and commercialized by APPLIED MATERIAL Inc , SANTA CLARA , CA , USA. .