Specific Process Knowledge/Etch/Etching of Silicon Oxide/SiO2 etch using Plasma Asher

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SiO2 can be etched in the Plasma Asher using CF4

Test work done January 2014 by Lis Nielsen and Berit Herstrøm @Danchip


SiO2 can be etched in the Plasma Asher using CF4. This gives an isotropic etch. In test2 the SiO2 layer has been etched through and there is a small over etch in the Silicon substrate. The masking material is 100nm Al. Etch rate and uniformity measurements have been done on wafers with no mask.


Plasma Asher parameter settings and results for the tests
  Test1 Test2
O2 flow 0 sccm 0 sccm
N2 flow 0 sccm 0 sccm
CF4 flow 200 sccm 200 sccm
Power 1000 W 1000 W
Process Time 10 min 50 min
Average Etch rate on wafer (5 points measured) 22.6 nm/min 31.8 nm/min
Non-uniformity over the wafer (5 points measured) ±10.8 % ±11.0 %
Non-uniformity plot