Study of selective amorphous silicon etching to silicon nitride using a pin-to-plate dielectric barrier discharge in atmospheric pressure

Remote-type atmospheric pressure plasmas were generated using a modified dielectric barrier discharge with the powered electrode consisting of multipins instead of a conventional blank planar plate. For the N-2/NF3 gas mixture, a high etch rate of a:Si close to 115 nm/s was obtained by adding 300 SCCM (SCCM denotes cubic centimeter per minute at STP) of NF3 to N-2 [50 SLM (standard liters per minute)] at an ac rms voltage of 8.5 kV (2.5 kW, 30 kHz). However, the selectivity of a:Si to Si3N4 was as low as 1.3. A selectivity of a:Si/Si3N4>5.0 could be obtained while maintaining an etch rate of a:Si at 110 nm/s by adding 250 SCCM CF4 to the N-2 (50 SLM)/NF3 (300 SCCM) mixture through the formation of a C-F polymer layer preferentially on the Si3N4 surface. (c) 2007 American Institute of Physics.