Aluminum Nitride

Mary Tang mtang at
Fri Sep 19 15:33:11 PDT 2008

Hi Joey --

Thanks for the detailed process flow, as really helps...  If I read 
correctly, your request is for etching metal-containing wafers on the 
stsetch, with the consideration that no metal is expected to be exposed 
to plasma.  I think we'll need a SpecMat quorum to decide that, so can't 
answer right now.  However, I do think that you will have a problem with 
resist surviving the hot phosphoric acid.  I would suggest that either 
using p5000etch metal chamber to plasma etch AlN (another SpecMat 
request) or depositing an oxide on top of the AlN, patterning that with 
a plasma or wet oxide etch, removing the resist, then using the hard 
mask for the AlN etch.


Joey Doll wrote:
> Hi again -
> I have been working with a vendor in San Jose to have aluminum nitride 
> deposited, and I would like to submit a new specmat request.
> The vendor is
> Hionix
> 2363 Bering Drive, San Jose, CA 95131, USA
> +1(408) 526-2333
> <>
> The aluminum nitride sputtering is performed in a system that is only 
> used to aluminum and titanium sputtering, normally for backend CMOS 
> interconnects. Sputtering is performed with an aluminum target with 
> nitrogen ambient at ~200C. This is in contrast with the system at 
> Berkeley which is also used for platinum.
> My process flow would be as follows:
> * start with a new DP SOI
> * clean wafer @ SNF
> * have titanium underlayer and aluminum nitride sputtered at Hionix 
> (with an additional RCA clean there)
> * lithography on top of the aluminum nitride (on ASML)
> * etch the aluminum nitride with phosphoric acid @ 120C on wbgeneral
> * strip the photoresist
> * lithography on top of the titanium
> * etch the titanium using standard ti wet etch on wbmetal
> * strip the photoresist
> * blanket sputter aluminum on gryphon
> * lithography on top of the aluminum
> * etch with standard al etch on wbmetal (which doesn't attack the 
> aluminum nitride or titanium)
> * strip the photoresist
> * frontside lithography with spr220
> * frontside STS etch on wafer to release front of cantilevers
> * strip the photoresist
> * backside lithography using spr220
> * backside STS etch to release wafers
> * oxide release on AMTEtcher
> * strip the photoresist
> The aluminum nitride would only be brought into the lab already 
> deposited on wafers, and the phosphoric acid would be drained down the 
> AWN system once returning to room temperature. Also, the aluminum 
> nitride, aluminum and titanium will be protected by photoresist while 
> in STS and AMTEtcher. I have been characterizing the films with XRD 
> for the past month or so and am ready to start fabricating working 
> devices as soon as the material is approved.
> Thanks for your consideration and please let me know if you have any 
> questions.
> - Joey
> On Tue, Jan 22, 2008 at 8:52 AM, Ed Myers <edmyers at 
> <mailto:edmyers at>> wrote:
>     Joey,
>     One of our weak areas is RF sputtering.  This is need for reactive
>     deposition of insulating materials.  As a result, we can not
>     support your request due to hardware limitations.  If you have any
>     questions please let me know.
>     Regards,
>     Ed
>     At 10:47 AM 1/19/2008, Joey Doll wrote:
>         Hi -
>         I'm considering a process which would use aluminum nitride as a
>         piezoelectric actuator layer. I wasn't able to find anything
>         mentioned
>         about it on the SNF website and was wondering if there is a
>         recipe /
>         it would be possible to sputter it on grypon or metallica? It is
>         sputtered up at Berkeley
>         ( and I was
>         hoping to use it instead of other materials like ZnO or PZT in
>         order
>         to keep my wafer semi-clean. Please let me know what you think.
>         Thanks!
>         Joey

Mary X. Tang, Ph.D.
Stanford Nanofabrication Facility
CIS Room 136, Mail Code 4070
Stanford, CA  94305
mtang at

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