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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Tests performed by Maria Farinha @DTU Nanolab | Tests performed by Maria Farinha @DTU Nanolab | ||
The gas flows were combined and the following results were achieved. It´s visible that with higher CF<sub>4</sub> 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. | |||
<br> | |||
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. | |||
{| border="1" cellspacing="2" cellpadding="2" | |||
|-style="background:Black; color:White" | |||
! CF4ICP | |||
|SiO<sub>2</sub> ER (nm/min) | |||
|Uniformity (SiO<sub>2</sub> etch) | |||
|Selectivity (SiO<sub>2</sub>:resist) | |||
|Si<sub>3</sub>N<sub>4</sub> ER (nm/min) | |||
|Si<sub>x</sub>N ER (nm/min) | |||
|- | |||
|45 CF<sub>4</sub> + 0 H<sub>2</sub> | |||
|<center>71.4</center> | |||
|<center>11.7%</center> | |||
|<center>0.74</center> | |||
|<center>-</center> | |||
|<center>-</center> | |||
|- | |||
|35 CF<sub>4</sub> + 10 H<sub>2</sub> | |||
|<center>69</center> | |||
|<center>12.6%</center> | |||
|<center>0.89</center> | |||
|<center>-</center> | |||
|<center>-</center> | |||
|- | |||
|22.5 CF<sub>4</sub> + 22.5 H<sub>2</sub> | |||
|<center>58.6</center> | |||
|<center>13.3%</center> | |||
|<center>1.43</center> | |||
|<center>84.4</center> | |||
|<center>42.9</center> | |||
|- | |||
|} | |||
*The uniformity considers a 100mm wafer, calculated with 5 points. | |||
<br> | |||
{| border="1" cellspacing="2" cellpadding="2" | |||
|-style="background:Black; color:White" | |||
! CF4lowCP | |||
|SiO<sub>2</sub> ER (nm/min) | |||
|Uniformity (SiO<sub>2</sub> etch) | |||
|Selectivity (SiO<sub>2</sub>:resist) | |||
|Si<sub>3</sub>N<sub>4</sub> ER (nm/min) | |||
|Si<sub>x</sub>N ER (nm/min) | |||
|- | |||
|45 CF<sub>4</sub> + 0 H<sub>2</sub> | |||
|<center>24.9</center> | |||
|<center>11.5%</center> | |||
|<center>0.47</center> | |||
|<center>-</center> | |||
|<center>-</center> | |||
|- | |||
|35 CF<sub>4</sub> + 10 H<sub>2</sub> | |||
|<center>22.6</center> | |||
|<center>11.6%</center> | |||
|<center>0.64</center> | |||
|<center>-</center> | |||
|<center>-</center> | |||
|- | |||
|22.5 CF<sub>4</sub> + 22.5 H<sub>2</sub> | |||
|<center>17.8</center> | |||
|<center>13.7%</center> | |||
|<center>1.85</center> | |||
|<center>28</center> | |||
|<center>22.5</center> | |||
|- | |||
|} | |||
<br> | |||
'''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. <br> | |||
Also, it´s noticeable that the feature profile is trenching, being more evident with faster etch rates. | |||
{| border="1" cellspacing="2" cellpadding="2" | |||
|-style="background:Black; color:White" | |||
|CF4ICP 45 CF<sub>4</sub> + resist strip | |||
|CF4ICP 45 CF<sub>4</sub> / 10 H<sub>2</sub> + resist strip | |||
|CF4ICP 35 CF<sub>4</sub>/ 10 H<sub>2</sub> | |||
|CF4lowCP 45 CF<sub>4</sub>/ 10 H<sub>2</sub> | |||
|CF4lowCP 45 CF<sub>4</sub>/ 0 H<sub>2</sub> + resist strip | |||
|CF4lowCP 35 CF<sub>4</sub>/ 10 H<sub>2</sub> + resist strip | |||
|CF4lowCP 22.5 CF<sub>4</sub>/ 22.5 H<sub>2</sub> + resist strip | |||
|- | |||
|[[File:CF4ICP-45.0c-af-PA-bot-04_1.png|200px]] | |||
|[[File:45.10-af-PA-center-07.png|200px]] | |||
|[[File:CF4lowCP-45.10-22.png|200px]] | |||
|[[File:CF4ICP-35.10-39.png|200px]] | |||
|[[File:low45-0-af-PA-03.png|200px]] [[File:low45-0-af-PA-08.png|200px]] | |||
|[[File:low35-10-af-PA-12.png|200px]] [[File:low35-10-af-PA-06.png|200px]] | |||
|[[File:low22.5-af-PA-08.png|200px]] [[File:low22.5-af-PA-04.png|200px]] | |||
|- | |||
|} | |||
Revision as of 15:30, 26 January 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.
| CF4ICP 45 CF4 + resist strip | CF4ICP 45 CF4 / 10 H2 + resist strip | CF4ICP 35 CF4/ 10 H2 | CF4lowCP 45 CF4/ 10 H2 | CF4lowCP 45 CF4/ 0 H2 + resist strip | CF4lowCP 35 CF4/ 10 H2 + resist strip | CF4lowCP 22.5 CF4/ 22.5 H2 + resist strip |
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Recipes and results - CF4 / H2 tests
| Recipe | Recipe parameters | Process time | Date | SEM picture | Etch rate in SiO2 | Etch rate in resist (AZ5214E inverse) |
Selectivity (SiO2:resist) |
|---|---|---|---|---|---|---|---|
| CF4ICP 22.5/22.5 | CF4= 22.5 sccm H2= 22.5 sccm Coil= 800W Platen= 15W Press= 2.5mTorr Temp= 20°C |
11:00 min | 11/09/2023 |   
|
68 nm/min +/- 8.5% |
60,2 nm/min +/- 9% |
1.13 |
| CF4ICP 35/10 | CF4= 35 sccm H2= 10 sccm Coil= 800W Platen= 15W Press= 2.5mTorr Temp= 20°C |
08:00 min | March 2023 |  
|
69 nm/min +/- 11.1% |
77,1 nm/min +/- 9.4% |
0.9 |
| CF4ICP 45/0 | CF4= 45 sccm H2= 0 sccm Coil= 800W Platen= 15W Press= 2.5mTorr Temp= 20°C |
08:00 min | March 2023 |  
|
71.4 nm/min +/- 10.3% |
96,5 nm/min +/- 6.0% |
0.74 |
| CF4ICP 45/10 | CF4= 45 sccm H2= 10 sccm Coil= 800W Platen= 15W Press= 2.5mTorr Temp= 20°C |
08:00 min | March 2023 |  
|
67.8 nm/min +/- 14.9% |
88,86 nm/min +/- 4.8% |
0.76 |
| CF4lowCP 22.5/22.5 | CF4= 22.5 sccm H2= 22.5 sccm Coil= 150W Platen= 25W Press= 2.5mTorr Temp= 20°C |
20:00 min | Sept 2023 |  
|
23.8 nm/min +/- 11% |
20,6 nm/min +/- 19.4% |
1.16 |
| CF4lowCP 35/10 | CF4= 35 sccm H2= 10 sccm Coil= 150W Platen= 25W Press= 2.5mTorr Temp= 20°C |
10:00 min | Feb 2023 |  
|
22.65 nm/min +/- 10.2% |
35.9 nm/min +/- 10.1% |
0.63 |
| CF4lowCP 45/0 | CF4= 45 sccm H2= 0 sccm Coil= 150W Platen= 25W Press= 2.5mTorr Temp= 20°C |
10:00 min | Feb 2023 |  
|
24.9 nm/min +/- 10.1% |
52,3 nm/min +/- 7.1% |
0.47 |
| CF4lowCP 45/10 | CF4= 45 sccm H2= 10 sccm Coil= 150W Platen= 25W Press= 2.5mTorr Temp= 20°C |
10:00 min | Feb 2023 |
|
29,4 nm/min +/- 13.7% |
100,6 nm/min +/- 16.5% |
0.29 |