"200 rpm per second" ? Cliff???

200 rpm means 200 revolutions per minute.  Are you suggesting an
acceleration or is it just a mistake?

Vic

----- Original Message -----
From: CLIF HAMEL 
To: 
Sent: Friday, March 15, 2002 4:39 PM
Subject: Re: [mems-talk] SU-8 spinning problems


> When you apply the SU-8 have the wafer rotating about 20 or rpm to get a
> puddle that is centered every time.  You may have to change the slow spin
rpm
> for 2" wafers.  Also, start the spin cycle at a slow acceleration, say 200
rpm
> per second.
>
> Clif
>
> Clifford J. Hamel
> Suss Microtec Applications Engineer
> (802) 244-5181, ext 297
>
> >>> landry@anvil.nrl.navy.mil 03/15/02 08:24AM >>>
> I have a problem spinning SU-8 2050 photoresist (Microchem corp). When
> I place the required amount on my 2" silicon wafer and spin, it does not
> spread uniformly. Instead it all goes to one side (if it is not exactly
> centered) or it spreads out in a starfish pattern, leaving large portions
> of the wafer uncovered.
> I have tried manually spreading the SU-8 across the wafer, with my
> pipette, but this introduces bubbles. It was also suggested to tilt the
> wafer to get the SU-8 to spread, or to sit it on a table. Neither of these
> suggestions worked, since the SU-8 2050 is so viscous and it takes so long
> to spread with gravity, a skin forms on the SU-8 before it spreads.
>
> Does anyone have suggestions?
>
> Glen Landry
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