Hi folks,

I have a problem with buried oxide layer etching after SI deep RIE
..

The pattern on the back side is 120 um x 120 um square and 400 um depth.

DRIE stopped at the BOX layer.

Since the wafer was thermally oxidized and the oxide on the front side must
be protected, only the oxide on the back side and the BOX layer must be
etched.

However, due to high aspect ratio, I couldn't etch the box layer.

Because the device layer must be intact, SiO2 RIE is not suitable for this.

Anyone has any idea?

Thanks

T.