Silicon Investor (SI) -- The First Internet Community

STOCKTALK

We've detected that you're using an ad content blocking browser plug-in or feature. Ads provide a critical source of revenue to the continued operation of Silicon Investor. We ask that you disable ad blocking while on Silicon Investor in the best interests of our community. If you are not using an ad blocker but are still receiving this message, make sure your browser's tracking protection is set to the 'standard' level.

Politics : Formerly About Advanced Micro Devices -- Ignore unavailable to you. Want to Upgrade?

To: Petz who wrote (83108)	12/15/1999 3:08:00 PM
From: Yousef	Respond to of 1572185

John, Re: "Can the bottom gate width be changed via the process, e.g., etching longer?" The bottom gate width can most certainly be changed via the "process". The notch is formed by using a two step poly etch. The first step etches vertically (anisotropically) by generating polymer (from the resist) as the poly is being etched. This polymer is deposited on the sidewalls of the poly which prevents etching of the poly sidewalls. This is why this part of the etch is almost entirely vertical. As the we get close to the bottom of the poly, a second etch phase is started that etches equally in all directions (isotropically). This part of the etch won't etch the already polymer protected sidewalls, but will etch vertically and laterally at the bottom of the poly line. The length of time of this part of the etch will determine the size of the notch. As with any process step, there are many things to be optimized. For example, this last etch step must NOT etch gate oxide very fast as we can't "punch thru" this without yield problems. Hope this helps. Make It So, Yousef