Nitride Plasma Etching
The following information is provided to SNF users to aid in the determination of appropriate equipment for their etching needs. Standard or typical programs and results are given. The user may want to tailor the programs to fit their specific process. Etch rates and selectivities are given as a starting point only and should not be considered to be current. It is highly recommended that users establish the etch rates for their work by the use of test wafers as close in material and masking pattern as possible to the device wafers to be etched.
Pre-treatments:
Etch Process (typical program):
|
Pressure |
150 mTorr |
|
SF6 |
53 sccm |
|
CF3Br |
33 sccm |
|
RF Power |
500 Watts |
Post-treatments:
Etch Rates and selectivities:
|
Material |
Etch Rate |
|
Nitride, std |
650A/min |
|
Nitride, low-stress |
670A/min |
|
Poly (undoped) |
2100A/min |
|
Resist |
450A/min |
|
Oxide (thermal) |
230A/min |
|
LTO,undensified |
200A/min |
|
LTO, undensified, 4% |
245A/min |
|
LTO, undensified, 8% |
340A/min |
|
LTO, densified |
215A/min |
|
LTO, densified, 4% |
200A/min |
|
LTO, densified, 8% |
240A/min |
|
Si |
2600A/min |
| W | 0 A/min |
| Ti | 0 A/min |
Pre-treatments:
Etch Process (typical program):
|
Pressure |
200 mTorr |
|
SF6 |
50 sccm |
|
F115 |
33 sccm |
|
RF Power |
83 Watts |
Post-treatments:
Etch Rates and selectivities:
|
Material |
Etch Rate |
|
Nitride, stressed |
521 A/min |
|
Nitride, low-stress |
815 A/min |
|
Poly (undoped) |
2739 A/min |
|
Resist |
653 A/min |
|
Oxide (thermal) |
390 A/min |
|
LTO,undensified |
518 A/min |
|
LTO, undensified, 4% |
252 A/min |
|
LTO, undensified, 8% |
379 A/min |
|
LTO, densified |
138 A/min |
|
LTO, densified, 4% |
187 A/min |
|
LTO, densified, 8% |
306 A/min |
| Si | 3000 A/min |
| Al | 0 A/min |
| W | 1350 A/min |
| Ti | 150 A/min |
| TiW | 1250 A/min |
Nitride issues in amtetcher:
The standard program #3 (Contact Etch process) will etch nitride with a fairly
anisotropic etch profile; however, the etch rate is about 55% of that of thermal
oxide. If selectivity to silicon is not important, one can go to the Via Etch
process, where the nitride etch rate is about 70% greater than for thermal oxide.
In general, as the CHF3/O2 flow ratio decreases, the etch rate of nitride increases
faster than that of oxide.
Pre-treatments:
Etch Process, Program 3 (typical program):
|
Pressure |
50 mTorr |
|
O2 |
30 sccm |
|
CH3 |
50 sccm |
|
RF Power |
1400 W |
|
Electrode Bias |
-530 VDC |
Post-treatments:
Etch Rates and selectivities:
|
Material |
Etch Rate |
|
Nitride, stressed |
680 A/min |
|
Nitride, low-stress |
445 A/min |
|
Thermal Oxide |
371 A/min |
|
LTO- undensified |
416 A/min |
|
LTO- undensified, 4% |
420 A/min |
|
LTO- undensified, 8% |
515 A/min |
|
LTO- densified |
395 A/min |
|
LTO- densified, 4% |
380 A/min |
|
LTO- densified, 8% |
500 A/min |
|
Poly, undoped |
305 A/min |
|
Photoresist |
295 A/min |
| Si | 380 A/min |
Pre-treatments:
Etch Process, CH.B JIMOX (typical program):
|
Operation |
Set Up |
Main Etch |
|
Pressure |
250 mT |
250 mT |
|
CHF3 |
15 sccm |
15 sccm |
|
CF4 |
60 sccm |
60 sccm |
|
Ar |
100 sccm |
100 sccm |
|
RF |
0 W |
500 W |
|
Mag Field |
0 Gauss |
60 Gauss |
Etch Rates and Selectivities:
|
Operation |
Etch Rate |
|
Main Etch |
Nitride 3244A/min |
Post-treatments:
|
_______________________________________________________________
Stanford Nanofabrication Facility webmaster@snf.stanford.edu Last Modified 08/29/2003 |