[labnetwork] Resist coating of tiny pieces

Mon Nov 16 18:21:51 EST 2020

Hi Lino,
You are getting good ideas for the resist but you are correct that you'll need to do something to level the sample during contact, if you are in fact using a contact aligner.  We were less concerned about breaking the sample/mask (although that is of course a concern) but more with the uniformity of the contact, which leads to poor resolution and/or definition.

We had a post doc work out this plan.

1)      Pattern and etch a grid with alpha numeric labels across a full wafer.

2)      Place your sample piece onto the wafer above using a VERY small drop of DI water on the back of your sample (make sure it doesn't wick to the front of the sample).  We use the size of a drip from the end of a pipette, so that it just barely spreads out across the sample (when in contact).

3)      Place dummy samples of the same thickness on the patterned alpha numeric wafer to ensure the mask/wafer pieces are level during wedge compensation.

This has worked VERY well for me, even in the case of thin flexible materials (Kapton).  The reason for the labeled wafer is that you can use it again if you need to do alignment.  You have to note where you placed the sample the first time but it reduces the "search and find" alignment strategy on your subsequent layers.

If you are interested I'll look for those wafers tomorrow and send you a few images.  We made some to keep on hand.

Good luck!

Aimee Bross Price

Sr. Research Associate
The Ohio State University
Nanotech West Lab
Institute for Materials Research
1381 Kinnear Road
Suite 100
Columbus, OH 43212
614-292-2753

From: labnetwork-bounces at mtl.mit.edu <labnetwork-bounces at mtl.mit.edu> On Behalf Of Lino Eugene
Sent: Monday, November 16, 2020 5:39 PM
To: Orad Reshef <orad at reshef.ca>; Nathanael Sieb <sieb at 4dlabs.ca>; Michael Rooks <michael.rooks at yale.edu>; Carsen Kline <carsen at stanford.edu>
Cc: 'labnetwork at mtl.mit.edu' <labnetwork at mtl.mit.edu>
Subject: Re: [labnetwork] Resist coating of tiny pieces

Dear Orad, Michael, Nathanael and Carsen,

Thanks for your reply. It is good to know that mounting a tiny piece on a carrier wafer is sufficient for EBL.

Sorry for not providing the context . We have currently an user who wants to plasma etch several microns of dielectric on a diced chip of ~3 mmx 3 mm. A thick photoresist is needed and I think that just mounting the chip on a carrier wafer would not work well. I was suggested to use dummy pieces placed all around the chip, which should work well for this process. Also, I believe that this would avoid also to break the chip or the carrier wafer (or the photomask?) because of the pressure applied during the wedge compensation on the mask aligner but maybe there is nothing to be worried about.

Best,

Lino Eugene, P.Eng., Ph.D.,
Micro/nanofabrication process engineer
Quantum Nano-Fabrication and Characterization Facility
QNC 1611
University of Waterloo
200 University Avenue West
Waterloo, ON, Canada
N2L 3G1

Ph: +1 519-888-4567 #37788
Cell: +1 226-929-1685
Website: https://qnfcf.uwaterloo.ca/<https://urldefense.com/v3/__https:/qnfcf.uwaterloo.ca/__;!!KGKeukY!lJpDRMwMq7tjme5BDs-NgI4GdVjNh5FkEm0LEO7cZ_6JOLZbys7A3NdKBOhuJ5Z9nRU$>

From: Orad Reshef [mailto:orad at reshef.ca]
Sent: November 16, 2020 16:19
To: Lino Eugene <lino.eugene at uwaterloo.ca<mailto:lino.eugene at uwaterloo.ca>>
Cc: labnetwork at mtl.mit.edu<mailto:labnetwork at mtl.mit.edu>
Subject: Re: [labnetwork] Resist coating of tiny pieces

Dear Lino,

We need a little more context for what you consider a "tiny piece". I routinely work with 1x1 cm pieces, and for those we use chucks that have an o-ring about 0.5 cm in diameter.

I have colleagues who have worked with 1mm x 1mm square diced samples. They mounted those on a large si handle wafer using double-sided carbon tape, like you would use to mount a sample on an SEM stub.

Hope this helps,
Orad

Orad Reshef, PhD

Département de physique | Department of Physics
Université d'Ottawa | University of Ottawa
boydnlo.ca<https://urldefense.com/v3/__http:/boydnlo.ca__;!!KGKeukY!lJpDRMwMq7tjme5BDs-NgI4GdVjNh5FkEm0LEO7cZ_6JOLZbys7A3NdKBOhuIeMYg3Q$> | reshef.ca<https://urldefense.com/v3/__http:/reshef.ca__;!!KGKeukY!lJpDRMwMq7tjme5BDs-NgI4GdVjNh5FkEm0LEO7cZ_6JOLZbys7A3NdKBOhu9TBqguU$>

On Mon, Nov 16, 2020 at 11:44 AM Lino Eugene <lino.eugene at uwaterloo.ca<mailto:lino.eugene at uwaterloo.ca>> wrote:
Dear colleagues,

We are having more users who work on tiny pieces to be coated with photo and e-beam resist.

I am thinking of different ways to coat these pieces:

*       custom chucks with a recess of the size of the chip

*       Si carrier wafer with recess etched by SF6 plasma

*       MicroSpray photoresist

I am wondering if you could share the techniques you use to get uniform coating on very small pieces.

Best,

Lino Eugene, P.Eng., Ph.D.,
Micro/nanofabrication process engineer
Quantum-Nano Fabrication and Characterization Facility
QNC 1611
University of Waterloo
200 University Avenue West
Waterloo, ON, Canada
N2L 3G1

Ph: +1 519-888-4567 #37788
Cell: +1 226-929-1685
Website: https://fab.qnc.uwaterloo.ca/<https://urldefense.com/v3/__https:/fab.qnc.uwaterloo.ca/__;!!KGKeukY!lJpDRMwMq7tjme5BDs-NgI4GdVjNh5FkEm0LEO7cZ_6JOLZbys7A3NdKBOhuWtUGD3w$>

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