yes you can thin with DRIE or KOH but the deeper you etch the worse it gets.

The shortcomings we experienced are the following:

- DRIE:

- wafer wavyness will be progressively compromised

- you need a dedicated recipe for very large area load to avoid grass

- if your tool has a protective ring you will create a bevel

- if you have no protective ring the wafer will become fragile

- KOH:

- without holder you may induce wafer fragility along the edges

- with holder you will create a bevel and will be limited in etching

(after some time the solution will leak under your holder's O-ring)

if you look for small thinning like removal of about 10-20um then both techniques are ok, for deeper thinning I would consider e.g. DRIE on both sides with protective ring, if you can compromise on wafer wavyness.

regards,

Alvise

Thanks a lot for your detailed reply! It seems worth to try DRIE to get 200um thinner. Hope it works!

Good, please bear in mind you will definitely need a protection ring in your DRIE tool, and will get a huge bevel along the wafer frame which will hamper further processing.

Regards

Alvise