[labnetwork] EBeam Lithography on Glass substrates

Wed Aug 23 18:03:53 EDT 2017

Sputtering is ok as is thermal evaporation.  Ebeam evaporation tends to expose your resist (I believe it is the x-rays generated not the electrons).  We sputter Al and have in the past (hopefully will again soon) thermally evaporated Au on top.  I need both a conductive and reflective layer, so just using conductive polymers is an issue if the sample is transparent (glass, SiC, sapphire, etc.).

Hope that helps.

Aimee

-----Original Message-----
From: labnetwork-bounces at mtl.mit.edu [mailto:labnetwork-bounces at mtl.mit.edu] On Behalf Of Marc Zuiddam - TNW
Sent: Wednesday, August 23, 2017 8:29 AM
To: 'labnetwork at mtl.mit.edu'
Subject: Re: [labnetwork] EBeam Lithography on Glass substrates

Dear people,

I always have the idea that sputting/evaporating a thin Au layer on my sample is exposing the e-beam resist on my sample.. Do you also experience that?

 Regards, Marc Zuiddam

-----Original Message-----
From: labnetwork-bounces at mtl.mit.edu [mailto:labnetwork-bounces at mtl.mit.edu] On Behalf Of Fouad Karouta
Sent: woensdag 23 augustus 2017 1:42
To: Jugessur, Aju S; labnetwork at mtl.mit.edu
Subject: Re: [labnetwork] EBeam Lithography on Glass substrates

Hi Aju,

Am echoing other voices:
- We use 12 nm of Au mostly on top of PMMA/ZEP to do the EBL which we remove in a Ki/I2 solution.
- Sometime we use Cr under resist layer as well when we need Cr for further processing.

Regards, Fouad Karouta

*************************************
Manager ANFF ACT Node
Australian National Fabrication Facility Research School of Physics and Engineering L. Huxley Building (#56), Mills Road, Room 4.02 Australian National University ACT 0200, Canberra, Australia
Tel: + 61 2 6125 7174
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Email: fouad.karouta at anu.edu.au
http://anff-act.anu.edu.au/

-----Original Message-----
From: labnetwork-bounces at mtl.mit.edu [mailto:labnetwork-bounces at mtl.mit.edu] On Behalf Of Lino Eugene
Sent: Tuesday, 22 August 2017 11:49 PM
To: labnetwork at mtl.mit.edu
Cc: Steven Wei <c27wei at edu.uwaterloo.ca>
Subject: Re: [labnetwork] EBeam Lithography on Glass substrates

Hi Aju,

We have a coop student who has worked on different anti-charging materials: PEDOT:PSS, Electra 92 and sputtered Al.

We had also adhesion and uniformity issues with PEDOT:PSS from Sigma-Aldrich. The solution was filtered and Triton X-100 was added and but no noticeable improvement. I was told that surface treatment with SurPass 3000 improves adhesion but we haven't tried this yet. Moreover, PEDOT:PSS cross-links under certain conditions and then the layer cannot be removed with water.

10-20 nm of sputtered Al should work well . The resistivity of 5 nm Al is expected to be high because of surface electron scattering (electron mean free path in Al at room temperature is ~19nm) and oxidation. We use MF-319 at room temperature or 40 degC  to remove the layer.

Electra 92 from AllResist is easy to work with as it can be removed with DI water after EBL and gives pretty good results on PMMA and on ZEP520A. Surface treatment on HSQ is needed, so far treatment with IPA gives good results. Also, the price is reasonable compared to ESpacer and AquaSave.

Best,

Lino Eugene, Ph.D., Jr. Eng.
Micro/nanofabrication process engineer
Quantum NanoFab
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/

-----Original Message-----
From: labnetwork-bounces at mtl.mit.edu [mailto:labnetwork-bounces at mtl.mit.edu] On Behalf Of Matthew Moneck
Sent: August 21, 2017 21:09
To: Mark K Mondol <mondol at mit.edu>; labnetwork at mtl.mit.edu
Subject: Re: [labnetwork] EBeam Lithography on Glass substrates

Hi Aju,

We have commonly used Al as a conductive layer on top of PMMA on glass (removal is typically done with minimal damage by using dilute AZ400K photoresist developer).  However, 5nm seems to be on the thin side.  Al can form native oxide that is up to 3-4nm thick.  Therefore, I would confirm the answer to Mark's question of whether or not the 5nm Al layer is conductive.  We typically sputter deposit films that are 10-20nm thick for our applications.

Best Regards,

Matt

--
Matthew T. Moneck, Ph.D.
Executive Manager, Carnegie Mellon Nanofabrication Facility Electrical and Computer Engineering | Carnegie Mellon University
5000 Forbes Ave., Pittsburgh, PA 15213-3890
T: 412.268.5430
F: 412.268.3497
www.ece.cmu.edu
nanofab.ece.cmu.edu

-----Original Message-----
From: labnetwork-bounces at mtl.mit.edu [mailto:labnetwork-bounces at mtl.mit.edu] On Behalf Of Mark K Mondol
Sent: Monday, August 21, 2017 5:04 PM
To: labnetwork at mtl.mit.edu
Subject: Re: [labnetwork] EBeam Lithography on Glass substrates

Aju:

1. Be 100% certain the layer is conductive and connected to ground in the tool.

2. Every time they write on glass, do the same exposure on Si, if the problem shows up on both Si and glass the issue is not the insulating substrate.

3. Al etch can damage PMMA; not always in a repeatable way. Does your process include etching the Al (I have found Transene CR-7 chrome etch to be compatible with PMMA and ZEP, so usually use Cr not Al as the conductive layer).

Regards,

Mark K MOndol

--
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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