XiaoQiang,

Is the recommended dose rated at the resist thickness you use? If your
resist is thicker than the rated setting, you need more dose. If the rated
dose is for i-line or g-line only, it is not very useful for your
broadband exposure because your dose is contributed from 350-500nm,
although peaked at 356, 405, and 436nm. Did you set the intensity control
on Ch1 (365nm i-line) or Ch2 (405nm h-line)? Do you use contact or
proximity exposure? For contact exposure, the intensity profile should be
sharp. For proximity exposure, did you leave the gap too wide? Do your
photomask patterns have sharp or transition edges (Cr mask vs. emulsion
mask)? If you mask patterns are not sharp, your intensity profile is not
sharp as well.

Regards,

Isaac


On Fri, 29 Sep 2006, Zhang Xiao Qiang wrote:

> Dear all
>
> I am handling AZ P4620 now. I also was confused by the dose of print and
> found with low dose of exposure you can not develop thoroughly. I can
> not get the steep wall with recommended dose. My feather is hole with
> diameter of 6 um and aspect ratio of above 2.5:1.
>
> My recipe is(on wafer dice with about 20*20 mm)
>
> Spin coating: 500 rpm 8 sec with 250 r/s; 1000 rpm 180 sec with 3000 r/s
> (15 um)
>
> Soft bake: 80 C 1 min then goes to 110 C and keep 6-8 min
>
> EBR with tweezer
>
> Expose 40-70 sec with broad band UV and the power is 900 w.
>
> Develop: AZ400K : DI water 1:4, 4-5 min. shaking with hand-holding
> tweezer.