What photoresist is this?

In fact this happens with some photoresists...i have come across this
problem recently. Though a microscope image shows that the resist has been
stripped, my glass wafer is still hydrophobic.

Would be great if someone could tell why this happens

Thanks
MK

> my spin speed is 4000rpm with a ramp of 30000r/s, and the prebake
> temperature is 100 degree c with a time of 1 minute, but there is always
> some photoresist
> remained no matter how long the develop time, why? Is the pre bake
> temperature too high and the the photoresist been destroyed?