A trick I've seen used to remove surface damage from grinding and polishing
is to grow a thermal oxide, then etch it off in an HF solution, say 5:1 BHF.
It's standard practice to perform a nitrogen anneal after oxidiation to
recover some of the damage caused by oxide growth.
The silicon thickness used to grow oxide is 46% of the oxide thickness; for
example, a 0.22-um oxide consumes 0.1 um of silicon.
    --Kirt Williams

----- Original Message -----
From: "Dave Goldstein" 
To: ; "General MEMS discussion"

Sent: Wednesday, December 19, 2007 7:21 PM
Subject: Re: [mems-talk] How to uniformly etch ~0.05 - 0.3um off a 3" Si
wafer?


> Thanks Edward and Andrea for the reply!
> I need to remove the top ~ 0.1 um of Si with diffusion 'cause I am
> suspecting my top surface is rich with defects due to the saturating
> concentration of dopants right at the surface.
>
> About surface roughness: I think you don't get rougher than 0.1um when you
> are etching 0.1um off. And my requirement for surface roughness is very
> lenient. 0.1um will do. But uniformity is the problem.
>
> I have a small RIE (Plastherm 790) but it doesn't give me much uniformity
> over 3" wafer.
>
> right now I am thinking about using low temperature UV oxidation to create
> some oxide and then remove them by HF.
>
> More suggestions?
>
> On Dec 19, 2007 12:57 PM, Andrea Mazzolari  wrote:
>
>> Hello Dave,
>> which is the thickness you need to remove ? Which is wafer orientation ?
>> Which is surface rougness you can accept ?