Dear Ahmad Khan, yes it is possible and KOH is more prefered. Similar questions have been already discussed within RG. Please check the following links. My Regards
https://www.researchgate.net/post/KOH_etching_solution_SiO2_above_Si
https://www.researchgate.net/post/Why_is_specifically_KOH_is_used_for_Silicon_etching
Dear Ahmad Khan, yes it is possible and KOH is more prefered. Similar questions have been already discussed within RG. Please check the following links. My Regards
https://www.researchgate.net/post/KOH_etching_solution_SiO2_above_Si
https://www.researchgate.net/post/Why_is_specifically_KOH_is_used_for_Silicon_etching
Using KOH or similar oxidative-aimed reactants wll always provide a Si etch rate much higher than SiOx one. This is the reason for which KOK solutions have been used for ages in Semiconductor industry to rtch Si using SIO2 as a mask.
You could try increasing the KOH concentration and/or bath temperature, however this would nit change Si-toSiO2 selectivity that much so to ensure you that, when the oxide film has been completely removed, you are not dramatically etch the underlying Si subsdtrate... and even favoring the etch of any structural defectivity of the same substrate such as dislocations or terraces where the etch rate would be even much higher then expexted for a perfect Si crystal.
Therefore, if you have to remove a thin SiO2 film you will face severe difficulties in avoiding Si substrate residual etching, because it is really hard to control the etch time.
On the other hand, if you have to remove a thick SiO2 film, you should tailor the process so to stop before reachning the Si substrate to avoid the problems said above in the case of thin oxide film... useless, of course.
HF (at a concentration as low as 1:20 in water in case of thin oxide films, or 1:7 for thick films) is what is universally used for precise reasons, first of all it high, high selectivity against Si etch.
dear Ahmad Khan
You can use 4M NaOH. Stir the suspension for 24 h at room temperature. We do that all the time and it works well, no Si is detected by ICP afterwards. HF is faster, but it is more dangerous, try to avoid it. We request people to have special training to use HF and you always have to have gluconate antidote at the hood, use thick gloves and long sleeve coat, but again: it is better if you can avoid using HF
yours
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