Alignment marks etched in LTO ?

[Mahnaz Mansourpour]

The recommendation was made to Gaurav yesterday during training.

mahnaz

Ed Myers wrote:
> All,
>
> Be careful.  We have seen alignment marks which are marginal and work 
> for a number of layers but not for your whole process.  If Jim pulled 
> his batch data and saw a strong signal, I would feel more 
> comfortable.  The system has a large capture range, which is why some 
> are lead to believe the marks are fine when in reality they are 
> extremely marginal.
>
> ASML engineers have a simulation program which they can use to 
> determine the correct alignment mark depth for the various films.  I 
> recommend we contact ASML to run the simulation and also verify the 
> quality of the alignment mark before I would commit my wafers.
>
> How many times have you heard "it aligned at the last layer."  Many 
> times this came from marginal alignment marks.
>
> Ed
>
>
> At 03:40 PM 5/13/2009, jim kruger wrote:
>
>> I have etched (wet) into 1000A thermal Oxide on Si.  Seems to work 
>> fine.  I have not tried to overlay more than 2 levels with this.
>>
>> jim
>>
>> --- On Wed, 5/13/09, Gaurav Thareja <gthareja at stanford.edu> wrote:
>>
>> > From: Gaurav Thareja <gthareja at stanford.edu>
>> > Subject: Alignment marks etched in LTO ?
>> > To: asml at snf.stanford.edu
>> > Date: Wednesday, May 13, 2009, 3:22 PM
>> > Dear ASML users.
>> >
>> > Does anybody have any experience in etching and aligning
>> > ASML alignment marks in LTO or Thermal Oxide (instead of
>> > etching in the substrate) ?
>> >
>> > please let me know
>> >
>> > warm regards
>> > ~gaurav
>> >
>> > --
>> > Gaurav Thareja
>> > Ph.D candidate, Nishi group
>> > Electrical Engineering
>> > Stanford University
>> > 420 Via Palou Mall, CISX 128
>> > Stanford, CA 94305
>> > Tel: 650-704-1029
>> > Email: gthareja at stanford.edu
>> >
>>
>>
>>
>
>