Hi,
I want to transfer feature (array of holes, diameter - 140 nm) from 110nm SiO2/hard cured HSQ layer to 220 nm silicon layer of SOI wafer. I need good anisotropic etch. I am using a Oxford RIE NGP 80 (no ICP source). The available gases are CHF3, SF6, O2, Ar. So, I am looking for a recipe for good anisotropic etch at this scale. I will really appreciate any suggestion or recommendation to relevant literature.
Thanks in advance,
Salahuddin
Dear Salahuddin
Please try the following recipe:
Si piece resting unclamped on 240mm graphite platen
CHF3 50sccm
SF6 15sccm
Pressure 10mT
RIE Power 200W
Temp 20˚C
Etch Rate = 76nm/min (piece so wafer uniformity unknown)
Sidewall Profile = 89˚
Selectivity to PR = 1.2:1
You may have marginal selectivity over 110nm HSG to etch 220nm deep Si holes. In this case reduce the RIE power to 150W.
Best regards
Colin
Colin Welch, Principal Etch Applications Engineer
Oxford Instruments Plasma Technology,
Sorry for the late response ..... Thanks a lot guys .... It is really helpful ....
Hi Colin,
Last Friday, I tried almost the same recipe you suggested but with much lower power as I found in some literature that DC bias window of 145 - 160 V gives better anisotropy and selectivity for oxide. It gave me quite good result but I haven't analysed it quantitatively yet. I am going to check your recipe (higher power). Higher power seems more reasonable for Oxford RIE because with low power there was lot of RF reflection.
Anyway, Thanks you very much for your reply and recipe.
Kindest Regards,
Salahuddin
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