[labnetwork] Pinholes in SiO2 from TMAH Etching

[Tyler Hieber]

Dear Colleagues,

We have been attempting to etch Si SOI wafers in TMAH with an SiO2 mask that was wet grown. The wafer layer we are etching is 300 microns thick, the other Si layer is 40 microns thick and the mask is approximately 1.7 microns thick. We have noticed etch pit in the 40 micron side of the wafer (non-etched side) and originally thought that it was due to microbubbles in the photoresist that allowed BOE to reach the SiO2 layer during the pattern transfer step. We have since ruled this out since we did not submerge the wafer in BOE for pattern transfer this time. Regardless, we are still seeing obvious etch pits in what should have been a continuous SiO2 layer on the 40 micron side.

If anyone has some experience with this phenomena, your assistance would be greatly appreciated.

The best,

Tyler J. Hieber
Ph.D. Graduate Student
Kansas State University
Department of Mechanical and Nuclear Engineering
thieber at ksu.edu
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