STS Pegasus 4/Processes/LNF O2 Descum

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About this Process
Process Details
Equipment STS Pegasus 4
Technology RIE
Material all
Mask Materials none
Gases Used O2

LNF O2 Descum (previously known as LNF ASH) uses an O2 plasma to isotropically remove polymers. It is intended as a photoresist descum prior to etching, although it may oxidize expose surfaces. The LNF Ar Descum is better suited for normal circumstances. This recipe may also be used for photoresist mask stripping post process, although there are other systems at the LNF with better performance for this process.


Follow the standard operating procedure. This recipe may also be added as an additional step within another recipe. Create a helpdesk ticket for assistance.

The maximum etch time allowed for this process is 5 minutes.


Parameter Units Setpoint
ICP Power W 2500
Bias Power (LF) W 75
Bias Pulsing Hz none
Pressure mTorr 20
O2 Flow sccm 200
Ar Flow sccm 100


Etch rate and uniformity

All of the etch rates below (with the exception of photoresist) are characterized using LPCVD or thermal furnace films.

Material Etch Rate Uniformity
SPR 220 7800 Å/min 6%
Silicon dioxide 30 Å/min 5%
Silicon nitride 22 Å/min 5%
Low stress nitride 20 Å/min 5%
Silicon 15 Å/min 5%

Mask Selectivity

This recipe is intended for blanket descum of the wafer surface, so a mask is not necessary.


Maximum allowed etch time is 5 min.