STS Pegasus 4/Processes/LNF O2 Descum

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.

Procedure

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.

Parameters

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

Capabilities

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.

Limitations

Maximum allowed etch time is 5 min.