Specific Process Knowledge/Etch/DRIE-Pegasus/Pegasus-4/Slow etch

The slow etch

This work is done by Berit Herstrøm @DTU Nanolab, is nothing else is stated
The slow etch is designed to etch slow at low powers to etch thin films and to avoid overheating of samples mounted on a carrier with Capton/polyimide tape

Parameter	Recipe name: Slow Etch	Recipe name: Slow Etch2
Coil Power [W]	350	200
Platen Power [W]	25	50
Platen temperature [oC]	20	20
H2 flow [sccm]	15	15
CF4 flow [sccm]	30	30
Pressure [mTorr]	3	10

Typical results	Slow Etch	Slow Etch2
Etch of SRN	~43nm/min [measured 39-50 nm/min over a 6" wafer]	23-25 nm/min [4" on carrier]]
Etch rate of Si3N4	~49 nm/min [4" on carrier]	24-26 nm/min [4" on carrier]
Etch rate of SiO2	~42nm/min [41-43 nm/min over a 6" wafer]	13.7-14.7 nm/min [4" on carrier]
Etch rate in Si	ñm/min	11-13 nm/min (10% load, 4" wafer on 6" carrier)
Etch rate of Mir resist	~nm/min	~17 nm/min
Tested etch time without burning the resist	3 min (6 min => resist burned)	30 min
Profile [o]

Etch Profile SEM images

• Profile of etch for 'Slow Etch2' 12 min, 100mm wafer on 150mm carrier with double side polyimide tape (capton), Si3N4 from LPCVD
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Etch Uniformity maps

• Map of etch rate measurements for 'Slow Etch'
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  Etch rate map of SiO2 etch on 6" wafer
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  Etch rate map of SRN etch on 6" wafer

• Map of etch rate measurements for 'Slow Etch2'
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  Etch rate map of Si3N4 etch on 4" wafer (on 6" carrier)
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  Etch rate map of SRN etch on 4" wafer (on 6" carrier)
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  Etch rate map of SiO2 etch on 4" wafer (on 6" carrier)
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  Etch rate map of Si etch on 4" wafer (on 6" carrier)

Test section - do not use

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A	Header text	Header text
Example	Example	Example
Example	Example	Example
Example	Example	Example