Specific Process Knowledge/Etch/ICP Metal Etcher/Chromium/End point

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Made by Berit bghe @ DTU Nanolab

Using the standard Cr etch recipe I was etching through 100 nm Cr on a 150 mm wafer it an etch load of 50%

I recorded the end point signal and tried three different stopping times to figure out when to stop the etch. I want to find out how I can use the end point signal to get the best etch result; Etch though - also in the small patterns without too much over etch.

I was looking at trenches with sizes ranging from 200 nm to 2 µm in width. The masking materials was negative DUV resist: NUV 2300-0.5 of approximately 500 nm. Here process flow can be seen here: File:Process_flow_for_test_wafers xx.pdf

Etched close to optimal

Middel of the wafer	Close to wafer edge
S047676 X min, Feb-2025, wafer center, 100 nm Cr mask, with 500 nm resist	S047676 X min, Feb-2025, wafer edge, 100 nm Cr mask, with 500 nm resist File:-

Etched too long

Middel of the wafer	Close to wafer edge
S047670 30 s barc etch, 7:45 min Cr etch, Feb-2025, wafer center, 100 nm Cr mask, with 500 nm resist	S047670 30 s barc etch, 7:45 min Cr etch, Feb-2025, wafer edge, 100 nm Cr mask, with 500 nm resist File:-

Etched too short

Middel of the wafer	Close to wafer edge
S047671 30 s barc etch, 7:00 min Cr etch, Feb-2025, wafer center, 100 nm Cr mask, with 500 nm resist	S047671 30 s barc etch, 7:00 min Cr etch, Feb-2025, wafer edge, 100 nm Cr mask, with 500 nm resist