Is the nitride has experienced a thermal oxidation process? If so, there will be
a thin oxide in the surface. This thin oxide should be etched prior to the
nitride etching.
Additionally, 1 hour H3PO4 etching is not enough to remove 2 micron Si3N4.

2009-10-31
xudehui0108


发件人： Nor Hafizah Ngajikin
发送时间： 2009-10-30  14:35:53
收件人： mems-talk
抄送：
主题： [mems-talk] wet etch of 2um Si3N4

Dear all,

I've tried to etch 2 micron thickness of Si3N4 using hot H3PO4. The
concentration of H3PO4 is 85w%. I heat the H3PO4 at 150 degree celcius for 1
hour. Unfortunately, this experiment didn't work as expected. None of the
nitride is etch away.

Can anybody share with me your experience on nitride etch using H3PO4.

Thank you.

Hafizah