S18

S18Edit

1.  Deposit:

primer: Microposit

spin 5” @ 1000 rpm (rise time 10”)
spin ~30” @ 6000 rpm (rise time 0”)
Not necessary on SiO2 wafers

resist: S1800 series from Shipley

dispense 2mL for 3 inches wafer
Dispense at constant rate in the center of the wafer, and do not empty the container to avoid bubbles.

1- spin 5”  @ 1000 rpm (rise time 5”) to spread the resist over the wafer -
or rise time 9” and skip the first step
2- spin 30” for a uniform coat (rise time ~0”)

3- Finish with a 1” @ 7000 rpm (rise time ~0”) to evacuate edges (rather psychological : should do it with back side solvent sputtering)

Spin parameters

From datasheet:

2.  Soft Bake (solvent evaporation)

Hot plate 1’
Temperature: 110°C (set hot-plate to 115°C)

Wafer must be cooled down before exposure

3.  Exposure:

From datasheet ( @ 436 nm = G-line):

Local adjustments:
following doses are given for the MJB3 mask aligner (without UV filter) on silicon substrate

Dose parameters

4.  Hardening:

One can switch to the next step if an overhang is not needed (inversed resist profile for good lift-off)

Damp in dichlorobenzene, at 31-33°C (in a regulated bath) for 30’’.
Dichlorobenzene penetrates over 600nm for this duration, and the resist is made less soluble in developer.

To stop the diffusion rinse in cold ODI (under tap), and wash in washing machine for 100’’  at 130 bars.
Do not dry warm in the washing machine
Dry with N2

Be sure not to contaminate developer with Dichlorobenzene 

5.  Development:

developer: MF319

First determination of timing: Observe appartition of patterns: first pattern turns white (when hardened in dichlo) in the center of the wafer, then turns dark red (much of the resist is dissolved), and once the last pattern has turned red add 1’. 

Development at ambient temperature
Developer must be changed each time (contamination changes parameters) -> use small quantities

MF319 etches Al !!

parameters 30/01/2006:
-For a 1.3µm thick layer, exposed 200mJ/cm2, hardened for 30’’ @ 32°C in fresh dichlo (resp. used dichlo), development duration at 19°C: after 30’’ (resp. 1’) last pattern turns white, then 50’’ (resp. 1’30) it turns red -> Total time: 1’35 (resp. 2’35). No residues, perfect undercut ~800nm in both cases.

Rinse: De-Ionized water
to stop development, ~20’’ under water tap

6.  Dry:

Nitrogen

aceton + ultrasounds

solvent