Bill

"Flow TEOS round the resist.." At what temperature was it done ?
Deposition of oxide from TEOS needs a high temperature ~375 C. Using
ozone/TEOS it would still need at least 300 C. For a planarizing
deposit the  temperature is higher. It  does not reflow like BPSG.

mateen

Bill Moffat wrote:
>
> The image reversed pillars resist thermal flow like silylated resist does.
> First expose the pillar regions.  Then image reverse using ammonia technique,
> dozens of papers on this technique.  Then flood expose remaining resist, this
> is the exposure level that determines the pillar wall angle.  Any angle 22
> degrees +/- from vertical is easily achievable.  Then develop away the newly
> exposed resist leaving the original exposed and reversed pillars.  This resist
> is more resistant to thermal flow.  Flow TEOS around the resist.  Then CMP or
> back lap off the hillocks over the pillars.  This exposes the tops of the
> pillars and they can be removed with simple Oxygen plasma giving vertical side
> walls down to the contacts.  Contact me by phone and I will walk through any
> variations and details of reversal down to 800 angstrom lines and spaces.  I
> think in later production they used spin on glass.  This process is one we
> tried to do in the 80's called the lost contact process but we etched and the
> contacts got bigger so we had no benefit.  With the reversal approach this
> gave a 40% reduction in chip size and a 60% increase in speed. I think.  My
> phone number if you want to hear more details is 408 954 8353.  Bill
>
> -----Original Message-----
> From: mmf [mailto:[email protected]]
> Sent: Friday, May 17, 2002 1:11 PM
> To: [email protected]
> Subject: Re: [mems-talk] PDMS pillar shape
>
> Bill,
>
> "Then flowing TEOS around the reversed image photo resist he defined
> contacts with vertical side walls..."
>
> How did he do it?
>
> mateen
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