1. Vertical Pillars for Biological Force Sensing
Class update – July 20th
Sarah Coulthard, Nahid Harjee, Nathan Klejwa, Ronald Kwon

2. Device Overview

3. Training Completed: To be completed: MERL clean shop: All
wafersaw: Ron
amtetcher: Nahid
wbgeneral: Nathan
innotec: Nahid and Nathan
Laser ablator: Ron
To be completed:
Critical point dryer

4. Thick SU-8 Characterization
Trying to obtain >300um layer of SU-8
SU gives huge indentations
Reason: Expired, SU formulation
Tried SU using recipe from last year
Second attempt: 450um +/- 25um
7 hours to process
Set up oven in MERL

5. Release Experiments

6. Strain Gage Resistance
1000 A of Au on 100 A of Cr
Desired resistance: 100 Ω
Measured resistance: Ω
Measurement system resistance: 10 Ω
Trace resistance: ~6 Ω

7. Runsheet Process Target Recipe Tool 1 Clean Piranha wbnonmetal 2
Lithography
1 um Shipley 3612
#1 Align/Spacer
karlsuss/karlsuss2 3
Oxide Etch
2500 A
6:1 BOE 4
Resist strip 5
Evaporate Cr
100 A
innotec 6
Evaporate Au
1000 A 7
Singe
MERL hot plate 8
Spin SU-8
5 um SU
MERL spinner 9
Pre-bake 10
Expose
#2 Cantilever 11
PEB 12
Develop
SU-8 Developer
MERL fumehood 13
Rinse and Dry
IPA and N2 14
Hard bake 15 16

8. Runsheet (cont’d) 17 Lithography 3 um SPR 220 #3 Metal
karlsuss/karlsuss2 18
Au etch
1000 A
Au etchant
wbgeneral 19
Cr etch A
CR-7/CR-14 20
Resist strip
PRX-127 21
Singe
MERL hot plate 22
Spin SU-8
450 um
SU-8 100
MERL spinner 23
Pre-bake 24
Expose
#4 Pillar 25
PEB 26
35 um SU 27 28
#1 Align/Spacer 29 30
Develop
335 um
SU-8 Developer
MERL fumehood 31
Rinse and Dry
IPA and N2 32
Hard bake 33
Release
50 um
HF vapor 34
Dice
ablator 35
Wire bond

9. Next Steps Further investigation of HF vapor:
Cr/SU-8 mask
SU-8 only mask
Exposure time for thick SU-8 layer
Characterize 35 um SU-8 layer
Test laser ablator
Wire bonding (wafer submitted to Pauline)

10. Innotec Reservation tomorrow 8 am – 12 pm Current plan: 100 A Cr
1000 A Au

11. Congratulations!!!
Nahid’s birthday
Sarah got hitched