Hi all,
I am grateful for the very informative encyclopedia and forum. I think that the creators have done a terrific job. I found a lot of important information but still could not find the answer to my problem.  
 
I am new to the photolithography and the first time I ever tried to create a template everything worked out perfectly (beginner's luck), but after that I have been having problems with creating templates.  
After applying the photoresist (SU-8 50) and spinning it everything seems fine until I try to softbake. During the softbake process pores or dimples or small islands (bubble-like) emerge. I am not sure how to call them but small circular features emerge everywhere on the surface.  
Here are my steps:
 
I use SiO2 thermal wafers and regular microscope slides.  
 
1. Pre-clean in ultrasonic bath for 5 min. in acetone and 5 min. in alcohol. Dry with a stream of high purity nitrogen.  
 
2. Pre-bake in 120C oven for 15 min.
 
3. Leave it to cool down for 10min-15 min.  
 
4. Use SU8-50 and spin under 2200 rpm, under slow acceleration. (I have also tried to coat the whole surface with thin layer of SU8 and apply more in the center before the spin)
 
5. Softbake for 6 min at 63-65C (this is where my problem starts to occur) on hot plate then slowly increase temperature to 96C and leave for another 20 min.  
 
6.  Leave it to cool down for 10min.  
 
7. Expose for 35 sec. under 480mW UV source.  
 
8. Post-bake for 1min at 65C and 6min at 95C on hot plate.  
 
9. Develop for 8min.  
 
10. Rinse with alcohol and dry with a nitrogen stream. (I use striped photomask) Once I had the SU8 stripes peel-off from the surface when I immersed the template into alcohol after developing.  
 
I have been struggling with this issue for over a month and I would appreciate any help or suggestions.
Thanks,
Karen