>These answers provided abundant options in thick photoresist
applications,
>but they all have a thickness limit below 100 microns, so I'm still
curious
>is there any positive resist with the thickness of more than 300um,
which is
>sensitive for UV light and easy to be removed by chemical liquid.

I don't think you can reliably put such thick resist films. The resist
will have to be very viscous, and you will have lots of difficulties with
uniformity and trapped bubbles. You may try applying several coats (spin,
soft bake, repeat). Also I know that in LCD screen industry people use
so-called slot coaters to produce thick uniform films.

Regards,
Anatoli Olkhovets,
Lucent - Bell Labs.