LAM 9400/Processes/LNF Aluminum
|About this Process|
|Mask Materials||Photoresist, SiO2|
|Gases Used||BCl3, HBr|
|Date Created||November 2018|
|Authored By||Ashley Jian & Shawn Wright|
This is a fast anisotropic aluminum etch.
These were measured using 1cm pieces on a 6" Si carrier. At this point we have limited data on how stable these etch rates are.
- Aluminum: 536 nm/min
- ALD Al2O3: 11 nm/min (49:1)
- SPR: 41 nm/min (13:1)
- SiO2: 36 nm/min (15:1)
- PMMA: 36 nm/min (15:1)
- ZEP: 29 nm/min (18:1)
The breakthrough step is typically set to ~10 seconds, or enough time to get through any native oxide on the aluminum.
- Aluminum: 88 nm/min
- ALD Al2O3: 28 nm/min
- SPR: 29.6 nm/min
- SiO2: 48.4 nm/min
- PMMA: 73.4 nm/min
- ZEP: 49.4 nm/min
This is a short ashing step intended to replace Cl embedded in the sidewalls of the features with F in order to reduce how much corrosion happens when the sample encounters moisture in the air. Even small amounts of Cl on the surface of aluminum can form a HCl corrosion cell that can continually corrode aluminum. Below is an example of HCl corrosion on aluminum. It can also help to go from the etch directly into a DI water tank or QDR to attempt to rinse off any HCl.
|Parameter||Break Through||Main Etch||SF6 Ash|
|Pressure||5 mTorr||20 mTorr||20 mTorr|
|TCP Power||600 W||600 W||400 W|
|Bias Power||50 W||50 W||-|
|HBr Flow||25 sccm||40 sccm||-|
|BCl3 Flow||25 sccm||10 sccm||-|
|SF6 Flow||-||-||90 sccm|
|O2 Flow||-||-||10 sccm|
|Time||10 sec (typ)||Variable||20 sec (typ)|