[labnetwork] Gold Deposition over Chrome

Tue Jun 4 01:48:46 EDT 2019

Hello Jim,

The Gold - Cr2O3 adherence test you had done applying enough pressure with
a swab was very conclusive, and this problem has to be addressed indeed.

I think there are some constraints for heating up a mask plate.
First Cr itself might get Sinter like alloyed with the Glass/Quartz plate, resulting 
a rough top surface (pinholes too) for such a thin 1000A film: as the metal
is “suck” like in the substrate. The lines edges might get affected.
All these for 15 min at ~ 400-500C : actually it depends on the “Temperature-Time
budget” 
Au, Cu, Cr, Fe diffuse very fast in Silicon based materials; TiN blocks them/ see
the Damascene process.
Very possible that Au to significantly diffuse in Cr2O3, or other thermal assisted 
enhanced adherence reaction.
You could try to use RTA. 

Second is the mask plate flatness issue.
The Glass plate is safe limited to ~ 490C to minimize the plastic-gravity deformation.
The plate bending due to the metal stress and metal-Glass expansion coefficient 
mismatch might not be a problem as the metal is very thin and is not continuous
being patterned.

Also possible you might think of depositing in-situ Cr & Au, or Cr2O3-Au and see
how it goes cold or after anneal.

Success!
Bernard

Sent from my iPad

> On Jun 3, 2019, at 5:01 PM, Jim Carroll <jim at photomaskportal.com> wrote:
> 
> Hi Greg,
> 
> Thanks, that sounds like a viable option.  In this specific case, since we already have patterned chrome masks, we're going to try the "“Reverse-side exposure Lift-Off” process mentioned by Andrei near the beginning of the thread, plus the addition of an anneal step to punch through the oxide layer and improve adhesion.
> 
> Thanks,
> Jim Carroll
> PhotomaskPORTAL
> We help you make masks
> (415) 448-6275
> 
> 
> 
>> On Mon, Jun 3, 2019 at 2:49 PM Greg Allion <grallion at ncsu.edu> wrote:
>> Maybe I'm not understanding your process correctly, but couldn't you just write the mask inverted, develop, evaporate your Au, lift-off, then Cr etch?  The Au will act as a your mask then for the Ctr etch.
>> -Greg
>> 
>>> On Fri, May 31, 2019 at 7:37 PM Nathanael Sieb <sieb at 4dlabs.ca> wrote:
>>> A similar interesting idea might be to use a fluoro-silane to make a fluorinated surface in the glass areas.  I've never tried it before for this application, but it might work.
>>> Thanks,
>>> 
>>> Nathanael
>>>> On 2019-05-31 3:40 a.m., Morrison, Richard H., Jr wrote:
>>>> Here’s a crazy idea try vapor HMDS, it will react with the glass but not the Chrome and it might help. Gold does not really like to stick to glass how thick is the film?
>>>> 
>>>>  
>>>> 
>>>> Rick
>>>> 
>>>>  
>>>> 
>>>>  
>>>> 
>>>>  
>>>> 
>>>> From: labnetwork-bounces at mtl.mit.edu [mailto:labnetwork-bounces at mtl.mit.edu] On Behalf Of Jim Carroll
>>>> Sent: Thursday, May 30, 2019 4:24 PM
>>>> To: labnetwork at mtl.mit.edu
>>>> Subject: [labnetwork] Gold Deposition over Chrome
>>>> 
>>>>  
>>>> 
>>>> Dear LabNetwork colleagues,
>>>> 
>>>>  
>>>> 
>>>> We are trying to add a thin film of gold over patterned chrome on a standard photomask using e-beam evaporation.  We want the gold to preferentially adhere to the chrome while lifting off the glass.
>>>> 
>>>> 
>>>> After a few tests, it appears that the gold sticks equally well to both the glass and chrome.  Ultrasonic agitation and swabbing do not selectively remove the gold from the glass while leaving it on the chrome.  Eventually, after enough pressure is applied with a swab, the gold releases from both the glass and chrome.  
>>>> 
>>>>  
>>>> 
>>>> Does anyone have a suggested approach?
>>>>  
>>>> 
>>>> Thanks,
>>>> 
>>>> Jim Carroll
>>>> PhotomaskPORTAL
>>>> 
>>>> We help you make masks
>>>> (415) 448-6275
>>>> 
>>>> ·         <image001.jpg>
>>>> 
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