Dear Charles,

Do you know if EDTA will attack photoresist or not? When you dip the wafers
into EDTA etchant, is the etchant  commercially available or is it needed to
mix?

Your reply will be highly appreciated.

Guangqing

  -----Original Message-----
  From: Charles Ellis 
  To: [email protected] 
  Date: Thursday, April 25, 2002 7:58 AM
  Subject: Re: [mems-talk] Wet etching TiW


  Hello Anke,

  I seem to remember having this problem 22 years ago. After etching the
Ti:W
  (in 30% H2O2 - stock solution), there would be a very slight residue.
Many
  times we could only see it after passivation, but if you looked close
enough
  you could detect it.  If my memory serves me correctly, we dipped the
wafers
  in an EDTA etchant (after the H2O2), the other thing that worked was to
etch
  the Ti:W in 30% H2O2 in a Stainless-Steel tank.  I know it sounds strange,
  but we fond that just using the SS tank made a great difference. I
remember
  we tried adding various Fe products in the Ti:W without much success.  I
  hope this helps.

  Charles Ellis
  Auburn University...

  ----- Original Message -----
  From: "Anke Stock" 
  To: 
  Sent: Thursday, April 25, 2002 2:17 AM
  Subject: [mems-talk] Wet etching TiW


  > Hello to everybody,
  > is there someone who has experience in wet etching of TiW? I use a
  > mixture of HCl and H2O2, but it seems that there are small amounts of
  > TiW on the wafer after etching. Has someone experiences with parameters
  > like temperature, time, other mixtures or something else? Many thanks
  > for your help
  > Anke
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