[labnetwork] Metallization on rough ceramic substrates

[Mark K Mondol]

I agree with Noah Clay, he identifies the issues correctly, in my view.

I would add that a general rule of thumb for liftoff is to spin resist 
about 3X thicker than the metal layer you want to liftoff.

Regards,

Mark K Mondol

On 1/4/2019 2:16 PM, Noah Clay wrote:
> Hello Adithi,
>
> As you know, ceramics can be quite porous and metal adhesion can be 
> diminished by surface/internally adsorbed water, organics, etc. 
> Therefore, you may consider deep solvent cleaning, other surface 
> treatments as appropriate (e.g., plasma) for your material and a 
> lengthy dehydration bake prior to resist application.  If pre-resist 
> cleaning proves ineffective, then after resist development, you may 
> consider O2 plasma or, if available, in-situ ion bombardment.  Lastly, 
> given the rough topography of your substrate, there may be undeveloped 
> or underexposed pockets of resist on the substrate, which necessitate 
> optimizing bake, exposure and develop conditions.
>
> As for HMDS (mainly used for Si), without knowing the type of ceramic 
> you’re using, I can’t say that it will be effective as an adhesion 
> promoter.  I very humbly/respectfully disagree with previous comments 
> that HMDS is used mostly for etching, but agree that to facilitate 
> liftoff, a relatively thick LOR layer should be spun and baked before 
> application of imaging resist.
>
> Best,
> Noah Clay
> /
> /
> /Singh Center for Nanotechnology /
> /University of Pennsylvania /
> /Philadelphia, PA/
>
> Sent from my iPhone
>
> On Jan 4, 2019, at 08:51, Hitesh Kamble <hit.kamble at gmail.com 
> <mailto:hit.kamble at gmail.com>> wrote:
>
>> Hello Adithi,
>>  In case of HMDS ,it will improve adhesion but resists will not 
>> remove easily from surafce.HMDS is mostly use in etching. Since 
>> you're having rough surface, Instead of HMDS use LOR 3B or say 
>> liftOFF resists which helps to improve liftoff process.
>> Also for 250nm metallization you need more than 2um thick resists.
>>
>> We did not do this on ceramic samples exactly but successfully did 
>> liftoff on etched/textured glass and etched samples(roughness more 
>> than~400nm).
>> Following are my suggestions:
>> -Time Interval between litho and deposition should be lowest as possible
>> - Dehydration at higher temp and for longer time.
>> -LOR 3B coating at lower rpm and gradually increase rpm.
>> -Keep sample in Remover PG and heat at 80C for 5min or more if metal 
>> not lifted,(Sonication not recquired in most cases)
>>
>>
>> Thanks,
>> Hitesh Kamble
>> IITBNF-IIT Bombay
>>
>>
>>
>> On Fri 4 Jan, 2019, 6:08 PM ADITHI U <uadithi at iisc.ac.in 
>> <mailto:uadithi at iisc.ac.in> wrote:
>>
>>     Dear All,
>>
>>
>>           We are having difficulties in doing metal(Ti/Pt) lift
>>     off on ceramic substrates. Does any of you have experience on
>>     fabricating metal patterns on the rough Ceramic Substrates. Below
>>     are the details of the process done.
>>
>>
>>        The roughness of the ceramic substrates were approximately
>>     400nm. We had used HMDS as adhesion promoter for lithography, the
>>     thickness of the Photoresist was ~ 1.5um.The thickness of the
>>     Ti/Pt layer was ~ 250nm. Immediately after lithography the
>>     deposition was done  followed by 48 hours of lift off(Acetone)
>>     process. Ultrasonication(5-10mins) in Acetone was done after
>>     48hours.
>>
>>     *Best Regards*
>>     *Adithi.U Senior Facility Technologist, National Nano Fabrication
>>     Centre, CeNSE, Indian Institute of Science Bangalore*
>>
>>
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-- 
Mark K Mondol
Assistant Director NanoStructures Laboratory
And
Facility Manager
Scanning Electron Beam Lithography Facility
Bldg 36  Room 229
www.rle.mit.edu/sebl
mondol at mit.edu
office - 617-253-9617
cell - 617-224-8756

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