STS Pegasus 4/Processes/LNF Unswitched Poly

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About this Process
STS Pegasus 4 Unswitched Poly 1 um.jpg
Process Details
Equipment STS Pegasus 4
Technology RIE
Material Silicon
Mask Materials PR, SiO2
Gases Used SF6, C4F8, O2

LNF Unswitched Poly is a single-step mixed-gas process intended for shallow silicon and thin film poly- and amorphous silicon etches.


Follow the standard operating procedure.


Parameter Units Setpoint
ICP Power W 500
Bias Power W 20
Bias Pulsing Hz 40 (80%)
Pressure mTorr 5
C4F8 Flow sccm 50
SF6 Flow sccm 100
Ar Flow sccm 50
Chuck Temperature °C 20


Etch rate

Etch rate will vary with feature size and loading.

Material Etch Rate Uniformity
Silicon 0.8 µm/min ?%
Etch rate is feature size dependent: narrow openings will etch slower than larger open areas.

Mask selectivity

Material Etch Rate Uniformity
SPR 220 250 Å/min 6%
Silicon dioxide 90 Å/min 7%
Silicon nitride 220 Å/min 4%
Low stress nitride 180 Å/min 4%

Etch profile

This process etches semi-isotropically. Vertical to lateral etch rate is approximately 2:1.


Etch length

This etch is designed for thin films and shallow etches (< 2 µm). It is not characterized for long processes.

Feature size

Remaining features that are narrower than the total depth will be etched away due to undercut during the etch.

Open area