XR-1541

6% solution

Spin-speed vs. resist thickness:

1000 rpm – 1900 Ang

2000 rpm – 1337 Ang

3000 rpm – 1108 Ang

4000 rpm – 972 Ang

5000 rpm – 883 Ang

2% solution

Spin-speed vs. resist thickness:

velocity------acceleration-------time-------thickness

2000 rpm----1000 rpm/s-------60s-------450 A

3000 rpm----1500 rpm/s-------60s-------390 A

4000 rpm----2000 rpm/s-------60s-------353 A

5000 rpm----3000 rpm/s-------60s-------323 A

5000 rpm----5000 rpm/s-------90s-------287 A

1% solution

Spin-speed vs. resist thickness:

velocity------acceleration-------time-------thickness

5000 rpm----2500 rpm/s-------60s-------169 A

Develop process:

We currently use two develop processes. One is a "normal" process and the other is a "high contrast" process.

"Normal" process:
1. after spin coat, hot plate bake at 250C for 2min
2. EBL expose, base dose ~1000uC/cm2
3. develop 70sec, with 2.3% TMAH (MF-319) at room temperature
4. rinse with low flowing DI water from tap (it is important to use the flowing DI water to reduce residue)

"High contrast" process:
1. after spin coat, hot plate bake at 80C for 4min
2. EBL expose, base dose ~2000uC/cm2
3. develop 30sec, with 25% TMAH at 80C
4. rinse with low flowing DI water from tap (it is important to use the flowing DI water to reduce residue)

Pros/cons:
1. "normal" process needs a lower dose than "high contrast" process, so "normal" process will have faster EBL write time.
2. "normal" process only needs room temperature developer.
3. "high contrast" process is needed for thick HSQ (6% solution, >100nm thickness) to prevent resist exposure in backscattered areas near large features.
4. "high contrast" process also of course needed for minimum size features that are densly packed (for example 10nm dots on 40nm pitch).
5. "high contrast" process also gives straighter sidewalls in resist.

Also, adding NaCl to the developer has been shown to improve contrast. Will add references later.