Hello Zhao,
there are many ways:
for silicon
-KOH or TMAH etch in the case of (100) or (110) wafers, HNA for (111)
wafers. Or you can use also grinding operations
For glass:
HF, sandblasting, grinding

For both silicon and glass probably there are also other ways.

I don't have experience with SU8.

Best regards,
Andrea

> Hello,
>
>      In my project, I need to increase the surface roughness of silicon,
> glass
> substrate or SU8. The surface roughness should be around 1 to 2um. Any
> suggestion will be hightly appreciated.