Mask Fabrication


Types of masks

emulsion film mask (Transparency mask)

Emusion film masks are cheap silver emulsion film mask on PET films. They are quite cheap and easy to use although the resolution are generally limited >30micron depending of the manufacturer and the thickness of the emulsion film.
In general the emulsion side is direct contact with the photoresist and the exposure light transmits through the film to obtain the best exposure resolution.

emulsion glass mask

Chrome mask


We can make chrome mask in house using maskless lithography and precoated chrome blank plate.
clean surface technology Kanagawa Jpana
CBL5006Du-AZPFS
100mJ/cm2 exposure with 405nm mask less writer
develop in 2.5% TMAH

More advanced: 

For patterns close to Abbe's limit, the diffraction of light makes the pattern difficult to be precisely made. Several advanced masks are made for these purchases such as phase-shift mask. But the field of nanopatterning is a bit outside the scope for general microfluidic applications.
 

Mask Fabrication Services 

Japan

Tokyo lithmatic
maximum resolution 2400dpi
175線
2400dpi = 1dot/10.58333micron
it's difficult to get reasonble results below 50 micron.


Mitani
http://www.mitani-micro.co.jp/en/index.html
chrome mask accuracy 0.3micron on 2.3mm 5" quartz ~USD$930
12"x18" film mask: limit at 30micron accuracy 0.5micron, ~USD$190

Topro
https://www.topro.com/product/photomask/

I thank Mr. Kei Funakoshi for information on mask fabrication services in Japan.

Taiwan

港建
www.tkk.com.tw

明順 50000dpi
http://minsoon.com.tw/

科毅
http://opto-equipment.etrading.com.tw/


Korea

Microfit 
www.microfit.kr
$90USD for 4" transparency

Europe

JD-photodata at UK
~$550 for 50kdpi 5" chrome mask down to 1micron
12"x18" emulsion film on 177micron thick polyester down to 5 micron (monotone) 10 micron (dual tone)
~$350 enough for eight 4" wafer design  each design~$45
grade 4 premium 200kdpi
but with tax close to $80bucks making each design ~ $55.

United States





http://www.photoplotstore.com/pages/photoplots.html
http://www.benchmarktech.com/home
compugraphics
http://www.imicromaterials.com/resolution-test-mask
FineLine Imaging

https://www.appliedimage.com/using-usaf-1951-resolution-test-target



Resolution testing mask design

Several resolution testing target designs have been developed in the field of optical imaging for inspection of resolution power of optical components in imaging industry.
For examples 1951 USAF target has been used extensively.
https://www.appliedimage.com/using-usaf-1951-resolution-test-target
http://www.vinland.com/USAF-1951.html
https://en.wikipedia.org/wiki/1951_USAF_resolution_test_chart

Also Ronchi ruling, grid patterns, concentric circles, focault tests, Siemens stars and others have also been used.


resources
https://proscitech.com/?navaction=show_page&chapter=s&page=3
http://www.pyser-sgi.com/graticules/optical-resolution-charts
http://www.graphics.cornell.edu/~westin/misc/res-chart.html
http://www.woomyoung.co.kr/htm-img/mrs-5.htm


Aim: To develop a 5 inch chrome mask with high resolution patterns to test the resolution of 1:1 exposure system as well as testing the exposure condition (power and time) for optimum results.
We will take advantage of a Suss microtech 6 section exposure accessories and design the resolution testing mask on top of it.

In each section, we have designed the same design containing the following patterns in both positive and negative form.
Patterns:
1. 5mm micrometer with 50micron div (lineweight 5 micron and 10micron)
2. 1mm micrometer with 10micron div (lineweight 3 micron)
3. Siemens section star (72 section, 5 degree per section)
4. Ronchi Ruling of 10 lp/mm, 20lp/mm, 50lp/mm, 100lp/mm, and 200lp/mm
5. Grid of 50lp/mm, 100lp/mm, 150lp/mm, 200lp/mm
6. pin hole resolution dots of diameter of 5, 7.5, 10, 12.5, 15, 20, 25, 50. spacing of 75, 50, 40, 30, 25, 20, 10, 7.5 micron
7. a USAF 1951 target from group 1 to group 8
8. a group of different line weight, 1, 2,3, 5, 7.5, 10, 15, 20, 25, 37.5, 50, 75, 100, 125, 150, 175, 200
9. 50micron line weight with different spacing from 1, 3, 5, 7.5, 10, 12.5, 25, 37.5, 50, 75, 100, 150, 200, 250 micron.

The work is licensed under a Creative Commons Attribution-ShareAlike 4.0 international license.

In the original file you can find more groups of USAF 1951. the USAF1951 target is made according to the spec documented on wikipedia.

The photo the a made mask looks like this.

You can download the files on my google drive.

Resolution testing reticle



Multilayer microfluidics mask design

http://pubs.rsc.org/en/content/articlehtml/2013/RA/C3RA43732A

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