Etching of TOPAS
TOPAS is etched by an oxygen plasma in the ASE. Masking of TOPAS was achieved by photo resist or a hard mask of aluminum or silicon. Photo resist is the preferred masking material, since hard masks tends to introduce local masking due to redeposition. TOPAS can be etched at rates up to 500 nm/min, with excellent uniformity over the wafer.
TOPAS by khara@danchip
| Parameter
|
Slow TOPAS etch
|
Fast TOPAS etch
|
| O2 (sccm)
|
50
|
99
|
| CO2 (sccm)
|
50
|
0
|
| Pressure (mTorr)
|
40
|
40
|
| Coil power (W)
|
800
|
720
|
| Platen power (W)
|
60
|
60
|
| Temperature (oC)
|
20
|
20
|
| Etch rate (nm/min)
|
~350
|
~500
|
| Center-Edge uniformity
|
0.98
|
0.95
|
Under etching and local masking
| Silicon hard mask
|
Aluminum hard mask
|
|
|
| Etch broke through the photo resist layer, and sputtered silicon have redeposited on the polymer surface, introducing local masking effects.
|
The aluminum hard mask has been etched in the resist developer introducing poor edge definition even though the resist was not completely removed by the etch.
|
Etch
- O2 flow [sccm]:50
- CO2 flow [sccm]:50
- Pressure [mTorr]:40
- Coil power [W]:800
- Platen power [W]:60
- Temperature [°C]:20
|
Etch
- O2 flow [sccm]:50
- CO2 flow [sccm]:50
- Pressure [mTorr]:40
- Coil power [W]:800
- Platen power [W]:60
- Temperature [°C]:20
|
