Specific Process Knowledge/Etch/Etching of Silicon Oxide/SiO2 etch using ASE/More test with CF4/H2, CHF3 and C4F8/H2 - SiO2 etch: Difference between revisions
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===Recipes and results - <span style="background:#FFD850">CF<sub>4</sub> / H<sub>2</sub> tests</span> === | |||
The following results were processed on chips bonded to a 100mm wafer. They were patterned with 915 UVN resist (DUV negative) and 65nm of BARC. The SiO2 layer was 2um (deposited on the C1 furnace). | |||
{| border="1" style="text-align: center; width: 320px; height: 200px;" | |||
|colspan="7" style="text-align: center;" style="background:LightGrey" |'''CF4ICP @ 30W platen, 8min''' | |||
|- | |||
|colspan="5" style="text-align: center;" style="background: #efefef;" |'''Values''' | |||
|colspan="1" style="text-align: center;" style="background: #efefef;" |'''SEM pictures''' | |||
|colspan="1" style="text-align: center;" style="background: #efefef;" |'''Comments''' | |||
|- | |||
|- | |||
!Structure size (nm) | |||
|'''structure pitch (nm)''' | |||
|'''SiO2 ER (nm/min)''' | |||
|'''Resist ER (nm/min)''' | |||
|'''Selectivity SiO2/resist''' | |||
| | |||
| | |||
|- | |||
|- | |||
!250 | |||
|500 | |||
|69.36 | |||
|114.38 | |||
|0.61 | |||
|[[File:25.01 CF4ICP 30w 8m-02.png|200px]] | |||
| Across the sample, the resist was fully etched away | |||
|- | |||
|- | |||
!500 | |||
|1000 | |||
|87.04 | |||
|114.38 | |||
|0.76 | |||
|[[File:25.01 CF4ICP 30w 8m-03.png|200px]] | |||
| | |||
|- | |||
!1000 | |||
|2000 | |||
|98.83 | |||
|114.38 | |||
|0.86 | |||
|[[File:25.01 CF4ICP 30w 8m-04.png|200px]] | |||
| | |||
|- | |||
!2000 | |||
|4000 | |||
|100.03 | |||
|114.38 | |||
|0.87 | |||
|[[File:25.01 CF4ICP 30w 8m-05.png|200px]] | |||
| | |||
|- | |||
|} | |||
{| border="1" style="text-align: center; width: 320px; height: 200px;" | |||
|colspan="7" style="text-align: center;" style="background:LightGrey" |'''CF4lowCP @ 45W platen, 15min''' | |||
|- | |||
|colspan="5" style="text-align: center;" style="background: #efefef;" |'''Values''' | |||
|colspan="1" style="text-align: center;" style="background: #efefef;" |'''SEM pictures''' | |||
|colspan="1" style="text-align: center;" style="background: #efefef;" |'''Comments''' | |||
|- | |||
|- | |||
!Structure size (nm) | |||
|'''structure pitch (nm)''' | |||
|'''SiO2 ER (nm/min)''' | |||
|'''Resist ER (nm/min)''' | |||
|'''Selectivity SiO2/resist''' | |||
| | |||
| | |||
|- | |||
|- | |||
!250 | |||
|500 | |||
|33.54 | |||
|33.45 | |||
|1.0 | |||
|[[File:25.01 CF4lowCP 45w 15m-01.png|200px]] | |||
| there was visible redeposition across smaller structures | |||
|- | |||
|- | |||
!500 | |||
|1000 | |||
|35.94 | |||
|30.45 | |||
|1.18 | |||
|[[File:25.01 CF4lowCP 45w 15m-02.png|200px]] | |||
| | |||
|- | |||
!1000 | |||
|2000 | |||
|36.54 | |||
|29.85 | |||
|1.22 | |||
|[[File:25.01 CF4lowCP 45w 15m-03.png|200px]] | |||
| | |||
|- | |||
!2000 | |||
|4000 | |||
|38.09 | |||
|28.65 | |||
|1.33 | |||
|[[File:25.01 CF4lowCP 45w 15m-05.png|200px]] | |||
| | |||
|- | |||
|} |
Revision as of 14:03, 22 April 2024
More test with CF4/H2 - SiO2 etch
Tests performed by Maria Farinha @DTU Nanolab
The gas flows were combined and the following results were achieved. It´s visible that with higher CF4 the selectivity is not good, so by adding H2, until 1:1, the selectivity improves. Additionally, the uniformity gets slightly worse while going for 1:1 of gas chemistry.
The recipe CF4lowCP 22.5/22.5 seems to be the only one good enough to use. It is a slow etch recipe, with good selectivity with AZ5214E resist.
CF4ICP | SiO2 ER (nm/min) | Uniformity (SiO2 etch) | Selectivity (SiO2:resist) | Si3N4 ER (nm/min) | SixN ER (nm/min) |
---|---|---|---|---|---|
45 CF4 + 0 H2 | |||||
35 CF4 + 10 H2 | |||||
22.5 CF4 + 22.5 H2 |
- The uniformity considers a 100mm wafer, calculated with 5 points.
CF4lowCP | SiO2 ER (nm/min) | Uniformity (SiO2 etch) | Selectivity (SiO2:resist) | Si3N4 ER (nm/min) | SixN ER (nm/min) |
---|---|---|---|---|---|
45 CF4 + 0 H2 | |||||
35 CF4 + 10 H2 | |||||
22.5 CF4 + 22.5 H2 |
Profile pictures of some tests - April 2023
Even in the cases with the resist strip (plasma asher 2 processing for 10/15min), there are some traces of resist left on the edges of the features.
Also, it´s noticeable that the feature profile is trenching, being more evident with faster etch rates.
Recipes and results - CF4 / H2 tests
Recipes and results - CF4 / H2 tests
The following results were processed on chips bonded to a 100mm wafer. They were patterned with 915 UVN resist (DUV negative) and 65nm of BARC. The SiO2 layer was 2um (deposited on the C1 furnace).