Specific Process Knowledge/Etch/ICP Metal Etcher/silicon oxide
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It is possible to etch SiO2 in the ICP metal etcher but it is not designed for it and the results are not fantastic. It is a challenge to get a good selectivity to resist (typically in the range of 1:1 or worse) and it is probably not possible to get a profile angle of 90 degrees. More likely about 75-85 degrees.
Slow etch of SiO2 with resist as masking material - using a 6" carrier wafer with recess
This recipe can be used for slow etching of SiO2 with resist as masking material. Here are some test results presented.
| Parameter | Resist mask |
|---|---|
| Coil Power [W] | 200 |
| Platen Power [W] | 25 |
| Platen temperature [oC] | 0 |
| CF4 flow [sccm] | 20 |
| H2 flow [sccm] | 10 |
| Pressure [mTorr] | 3 |
| Results | Test on wafer with 50% load (Travka 50), by BGHE @danchip | 100% load on 100mm wafers with Barc and KRF (no mask) |
|---|---|---|
| Etch rate of thermal oxide | 44.1 nm/min (50% etch load) (01-02-2014) | |
| Selectivity to resist [:1] | ~0.9 (SiO2:resist) | ~1.25:1 (Barc:KRF) |
| Wafer uniformity (100mm) | ±1.6% (01-02-2014) | |
| Profile [o] | Take a look at the images but be aware that the resist profile was not good to begin with. | |
| Wafer uniformity map (click on the image to view a larger image) |  |
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| SEM profile images |
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| Etch rate in barc | 50 nm/min (2014-09-09) | |
| Etch rate in KRF resist | 40 nm/min (2014-09-09) |
SiO2 etch using DUV mask
SiO2 etch nLOF
| Parameter | Resist mask |
|---|---|
| Coil Power [W] | 800 |
| Platen Power [W] | 100 |
| Platen temperature [oC] | 0 |
| CF4 flow [sccm] | 30 |
| H2 flow [sccm] | 10 |
| Pressure [mTorr] | 4 |
| Results | Test on wafer with 50% load (Travka 50), by BGHE @danchip |
|---|---|
| Etch rate of thermal oxide | >110 nm/min (50% etch load) (09-03-2015) |
| Selectivity to resist [:1] | <0.7:1 (SiO2:resist) |
| Wafer uniformity (100mm) | |
| Profile [o] | Not known |
| Wafer uniformity map (click on the image to view a larger image) | Not Known |
| SEM profile images | NONE |
| Etch rate in nLOF resist | 1.6µm was removed after 10min |