TMFRecipes

Return to Toronto Microfluidics Foundry Home

July 2007 - George Ye
 A. TO FABRICATE STRAIGHT WALL ON THICK SU-8 SAMPLE

Problem: The features has a large overhanging edge near the top; the walls were slanted

Cause: the photomask was not pressed firmly against the photofilm which causes UV light to leak around the photomask apertures

Solution: before exposure, cover the photomask with a large piece of 3x2 inches glass. Then, apply two thick stacks (10-15) microscope slides on either sides of the cover glass to be used as weight.

Protocol:

Dehydration bake:

1. Dehydration bake @ 200 degrees for about 15 minutes

Spincoating:

1. 500RPM DWELL: 10s   ACCELERATION: 10s

2. 2000RPM DWELL: 30s  ACCELERATION: 5s

3. 0RPM   DWELL: 0s    ACCELERATION: 10s

Pre-exposure bake:

1. 7 minutes @ 65 degrees

2. 20 minutes @ 95 degrees

3. allowed to cool to room temperature

Exposure:

1. cover the photomask as described above

2. UV exposure for 20 seconds

Post-exposure bake:

1. 2 minutes @ 65 degrees

2. 7 minutes @ 95 degrees

3. 2 minutes @ 65 degrees

Develop:

1. Develop in 20ml of developer with mild to strong agitation for 20 minutes

2. Replace with 20ml of fresh developer

3. Develop further for another 20 minutes