Shay's right. If an AR coating won't work though, the data sheets for
SU-8 address this under the "relative dose" tables. In the datasheet
for SU-8 3000, for example, this is given in Table 4:

http://www.microchem.com/pdf/SU-8%203000%20Data%20Sheet.pdf

Table 4: RELATIVE DOSE
Silicon 1X
Glass 1.5X
Pyrex 1.5X
Indium Tin Oxide 1.5X
Silicon Nitride 1.5 - 2X
Gold 1.5 - 2X
Aluminum 1.5 - 2X
Nickel Iron 1.5 - 2X
Copper 1.5 - 2X
Nickel 1.5 - 2X
Titanium 1.5 - 2

- Kevin

On Wed, Jan 11, 2012 at 12:38 AM, Shay  wrote:
> The gold coating increases the actual exposure and is many times dispersed.
> You might want to try AR coating beneath the SU*
>
> Shay
>
> -----Original Message-----
> From: [email protected]
> [mailto:[email protected]] On Behalf Of Gary
> Hillman
> Sent: Tuesday, January 10, 2012 10:35 PM
> To: 'General MEMS discussion'
> Subject: Re: [mems-talk] SU-8 process development
>
> Sounds like you did not expose the material properly. Gary