if your looking for polished surfaces (front and back), the best flatness that I
have seen is from Ultrasil Corporation in Hayward where they can supply 4"
wafers
at  0.6-0.9 um  TTV and <1 um on 150mm wafers with Double Side Polishing.

Dont know of anything better- Should you find some , let me know as well.

Ken

Justin Mansell wrote:

> Can someone recommend a silicon wafer vendor for very flat wafers?  I'm
> looking ideally for less than a wave at 633nm over the entire wafer.
> Justin Mansell          |       "Only a risk tests the reality of a belief"
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