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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=More test with CF4/H2, CHF3 and C4F8/H2 - SiO2 etch=
=Etch tests of Silicon Oxide=


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]]
|-
|}




Line 12: Line 115:
! '''Date'''
! '''Date'''
! '''SEM picture'''
! '''SEM picture'''
! '''SEM pic w/ no resist'''
! '''Redeposition - top view'''
! '''Profile angles'''
! '''Etch rate in SiO2'''
! '''Etch rate in SiO2'''
! '''Etch rate in resist <br> (AZ5214E inverse)'''
! '''Etch rate in resist <br> (AZ5214E inverse)'''
! '''Selectivity <br> (SiO2:resist)'''
! '''Selectivity <br> (SiO2:resist)'''
! '''Etch rate in Si'''
|-
|-
|-
|-
Line 26: Line 125:
|<!--'''Process time'''--> 11:00 min
|<!--'''Process time'''--> 11:00 min
|<!--'''Date'''--> 11/09/2023
|<!--'''Date'''--> 11/09/2023
|<!--'''SEM picture'''--> [[File:CF4ICP 11min C 01.png|200px]]
|<!--'''SEM picture'''--> [[File:CF4ICP_11min_C_01.png|200px]] [[File:800px-CF4ICP_11min_af_PA_top_01.png|200px]] [[File:800px-CF4ICP_11min_C_03.png|200px]]
|<!--'''SEM pic w/ no resist'''-->
|<!--'''Redeposition - top view'''--> [[File:CF4ICP 11min af PA top 01.png|200px]]
|<!--'''Profile angles'''--> [[File:CF4ICP 11min C 03.png|200px]]
|<!--'''Etch rate in SiO2'''--> 68 nm/min <br> +/- 8.5%
|<!--'''Etch rate in SiO2'''--> 68 nm/min <br> +/- 8.5%
|<!--'''Etch rate in resist'''--> 60,2 nm/min <br> +/- 9%
|<!--'''Etch rate in resist'''--> 60,2 nm/min <br> +/- 9%
|<!--'''Selectivity (SiO2:resist)'''--> 1.13
|<!--'''Selectivity (SiO2:resist)'''--> 1.13
|<!--'''Etch rate in Si'''-->
|-
|-
|-
|-
Line 41: Line 136:
|<!--'''Process time'''--> 08:00 min
|<!--'''Process time'''--> 08:00 min
|<!--'''Date'''--> March 2023
|<!--'''Date'''--> March 2023
|<!--'''SEM picture'''--> [[File:35.10 af ase 04.png|200px]]
|<!--'''SEM picture'''--> [[File:200px-35.10_af_ase_04.png|200px]] [[File:200px-35.10_af_PA_bot_03.png|200px]]
|<!--'''SEM pic w/ no resist'''--> [[File:35.10 af PA bot 03.png|200px]]
|<!--'''Redeposition - top view'''-->
|<!--'''Profile angles'''-->
|<!--'''Etch rate in SiO2'''--> 69 nm/min <br> +/- 11.1%
|<!--'''Etch rate in SiO2'''--> 69 nm/min <br> +/- 11.1%
|<!--'''Etch rate in resist'''--> 77,1 nm/min  <br> +/- 9.4%
|<!--'''Etch rate in resist'''--> 77,1 nm/min  <br> +/- 9.4%
|<!--'''Selectivity (SiO2:resist)'''--> 0.9
|<!--'''Selectivity (SiO2:resist)'''--> 0.9
|<!--'''Etch rate in Si'''-->
|-
|-
|-
|-
Line 56: Line 147:
|<!--'''Process time'''--> 08:00 min
|<!--'''Process time'''--> 08:00 min
|<!--'''Date'''--> March 2023
|<!--'''Date'''--> March 2023
|<!--'''SEM picture'''--> [[File:CF4ICP 45.0c bf PA 04.png|200px]]
|<!--'''SEM picture'''--> [[File:200px-CF4ICP_45.0c_bf_PA_04.png|200px]] [[File:200px-CF4ICP_45.0c_af_Pa-bot_06.png|200px]]
|<!--'''SEM pic w/ no resist'''--> [[File:CF4ICP 45.0c af Pa-bot 06.png|200px]]
|<!--'''CD change (mask 55% trench) after s007467 is it <50% after barc etch'''<br>
trench opening as a fraction of pitch-->
|<!--'''Profile angles'''-->
|<!--'''Etch rate in SiO2'''--> 71.4 nm/min  <br> +/- 10.3%
|<!--'''Etch rate in SiO2'''--> 71.4 nm/min  <br> +/- 10.3%
|<!--'''Etch rate in resist'''--> 96,5 nm/min  <br> +/- 6.0%
|<!--'''Etch rate in resist'''--> 96,5 nm/min  <br> +/- 6.0%
|<!--'''Selectivity (SiO2:resist)'''--> 0.74
|<!--'''Selectivity (SiO2:resist)'''--> 0.74
|<!--'''Etch rate in Si'''-->
|-
|-
|-
|-
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|<!--'''Process time'''--> 08:00 min
|<!--'''Process time'''--> 08:00 min
|<!--'''Date'''--> March 2023
|<!--'''Date'''--> March 2023
|<!--'''SEM picture'''--> [[File:45.10 af ASE 01.png|200px]]
|<!--'''SEM picture'''--> [[File:200px-45.10_af_ASE_01.png|200px]] [[File:200px-45.10_af_PA_center_07.png|200px]]
|<!--'''SEM pic w/ no resist'''--> [[File:45.10 af PA center 07.png|200px]]
|<!--'''CD change (mask 55% trench) after s007467 is it <50% after barc etch'''<br>
trench opening as a fraction of pitch-->
|<!--'''Profile angles'''-->
|<!--'''Etch rate in SiO2'''--> 67.8 nm/min  <br> +/- 14.9%
|<!--'''Etch rate in SiO2'''--> 67.8 nm/min  <br> +/- 14.9%
|<!--'''Etch rate in resist'''--> 88,86 nm/min  <br> +/- 4.8%
|<!--'''Etch rate in resist'''--> 88,86 nm/min  <br> +/- 4.8%
|<!--'''Selectivity (SiO2:resist)'''--> 0.76
|<!--'''Selectivity (SiO2:resist)'''--> 0.76
|<!--'''Etch rate in Si'''-->
|-
|-
|-
|-
Line 88: Line 169:
|<!--'''Process time'''--> 20:00 min
|<!--'''Process time'''--> 20:00 min
|<!--'''Date'''--> Sept 2023
|<!--'''Date'''--> Sept 2023
|<!--'''SEM picture'''--> [[File:CF4lowCP 20m pat C03.png|200px]]
|<!--'''SEM picture'''--> [[File:CF4lowCP_20m_pat_C03.png|200px]] [[File:CF4owCP_20min_af_PA_03.png|200px]]  
|<!--'''SEM pic w/ no resist'''-->
|<!--'''Redeposition - top view--> [[File:CF4owCP 20min af PA 03.png|200px]]
|<!--'''Profile angles'''-->
|<!--'''Etch rate in SiO2'''--> 23.8 nm/min <br> +/- 11%
|<!--'''Etch rate in SiO2'''--> 23.8 nm/min <br> +/- 11%
|<!--'''Etch rate in resist'''--> 20,6 nm/min <br> +/- 19.4%
|<!--'''Etch rate in resist'''--> 20,6 nm/min <br> +/- 19.4%
|<!--'''Selectivity (SiO2:resist)'''--> 1.16
|<!--'''Selectivity (SiO2:resist)'''--> 1.16
|<!--'''Etch rate in Si'''-->
|-
|-
|-
|-
Line 103: Line 180:
|<!--'''Process time'''--> 10:00 min
|<!--'''Process time'''--> 10:00 min
|<!--'''Date'''--> Feb 2023
|<!--'''Date'''--> Feb 2023
|<!--'''SEM picture'''--> [[File:CF4lowCP 35.10 10.png|200px]]
|<!--'''SEM picture'''--> [[File:CF4lowCP_35.10_10.png|200px]] [[File:Low35_10_af_PA_12.png|200px]]
|<!--'''SEM pic w/ no resist'''--> [[File:low35 10 af PA 12.png|200px]]
|<!--'''CD change (mask 55% trench) after s007467 is it <50% after barc etch'''<br>
trench opening as a fraction of pitch-->
|<!--'''Profile angles'''-->
|<!--'''Etch rate in SiO2'''--> 22.65 nm/min  <br> +/- 10.2%
|<!--'''Etch rate in SiO2'''--> 22.65 nm/min  <br> +/- 10.2%
|<!--'''Etch rate in resist'''--> 35.9 nm/min  <br> +/- 10.1%
|<!--'''Etch rate in resist'''--> 35.9 nm/min  <br> +/- 10.1%
|<!--'''Selectivity (SiO2:resist)'''--> 0.63
|<!--'''Selectivity (SiO2:resist)'''--> 0.63
|<!--'''Etch rate in Si'''-->
|-
|-
|-
|-
Line 119: Line 191:
|<!--'''Process time'''--> 10:00 min
|<!--'''Process time'''--> 10:00 min
|<!--'''Date'''--> Feb 2023
|<!--'''Date'''--> Feb 2023
|<!--'''SEM picture'''--> [[File:CF4lowCP.right 01.png|200px]]
|<!--'''SEM picture'''--> [[File:CF4lowCP.right_01.png|200px]] [[File:Low45_0_af_PA_05.png|200px]]
|<!--'''SEM pic w/ no resist'''--> [[File:low45 0 af PA 05.png|200px]]
|<!--'''CD change (mask 55% trench) after s007467 is it <50% after barc etch'''<br>
trench opening as a fraction of pitch-->
|<!--'''Profile angles'''-->
|<!--'''Etch rate in SiO2'''--> 24.9 nm/min  <br> +/- 10.1%
|<!--'''Etch rate in SiO2'''--> 24.9 nm/min  <br> +/- 10.1%
|<!--'''Etch rate in resist'''--> 52,3 nm/min  <br> +/- 7.1%
|<!--'''Etch rate in resist'''--> 52,3 nm/min  <br> +/- 7.1%
|<!--'''Selectivity (SiO2:resist)'''--> 0.47
|<!--'''Selectivity (SiO2:resist)'''--> 0.47  
|<!--'''Etch rate in Si'''-->
|-
|-
|-
|-
Line 135: Line 202:
|<!--'''Process time'''--> 10:00 min
|<!--'''Process time'''--> 10:00 min
|<!--'''Date'''--> Feb 2023
|<!--'''Date'''--> Feb 2023
|<!--'''SEM picture'''--> [[File:CF4lowCP 45.10 22.png|200px]]
|<!--'''SEM picture'''--> [[File:CF4owCP_20min_af_PA_03.png|200px]]
|<!--'''SEM pic w/ no resist'''--> X
|<!--'''CD change (mask 55% trench) after s007467 is it <50% after barc etch'''<br>
trench opening as a fraction of pitch-->
|<!--'''Profile angles'''-->
|<!--'''Etch rate in SiO2'''--> 29,4 nm/min  <br> +/- 13.7%
|<!--'''Etch rate in SiO2'''--> 29,4 nm/min  <br> +/- 13.7%
|<!--'''Etch rate in resist'''--> 100,6 nm/min  <br> +/- 16.5%
|<!--'''Etch rate in resist'''--> 100,6 nm/min  <br> +/- 16.5%
|<!--'''Selectivity (SiO2:resist)'''--> 0.29
|<!--'''Selectivity (SiO2:resist)'''--> 0.29
|<!--'''Etch rate in Si'''-->
|-
|-
|-
|-
Line 153: Line 215:
<br>
<br>


===Recipes and results - <span style="background:#FFD850">CHF<sub>3</sub> tests===
===Recent results - <span style="background:#FFD850">CF<sub>4</sub> / H<sub>2</sub> tests</span> ===


{| border="1" cellspacing="1" cellpadding="1" align="left"
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). <br>
! '''Recipe'''
(25 jan 2024)
! '''Recipe parameters'''
 
! '''Process time'''
 
! '''Date'''
{| border="1" style="text-align: center; width: 320px; height: 200px;"
! '''SEM picture'''
|colspan="7" style="text-align: center;" style="background:LightGrey" |'''CF4ICP @ 30W platen, 8min'''  
! '''SEM pic w/ no resist'''
! '''Redeposition - top view'''
! '''Profile angles'''
! '''Etch rate in SiO2'''
! '''Etch rate in resist <br> (AZ5214E inverse)'''
! '''Selectivity <br> (SiO2:resist)'''
! '''Etch rate in Si'''  
|-
|-
|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'''
|-
|-
|-style="background:white; color:black"
|<!-- '''Recipe name''' --> CHF3_t1
|<!-- '''SiO2 before etch''' --> CHF<sub>3</sub>= '''22.5''' sccm <br> Coil= 800W <br> Platen= 15W <br> Press= 2.5mTorr <br> Temp= 20°C <br>
|<!--'''Process time'''--> 12:00 min
|<!--'''Date'''--> 04/09/2023
|<!--'''SEM picture'''--> [[File:CHF3 t1 pat C 01.png|200px]]
|<!--'''SEM pic w/ no resist'''-->
|<!--'''Redeposition - top view'''--> [[File:CHF3 t1 12min af PA 03.png|200px]]
|<!--'''Profile angles'''-->
|<!--'''Etch rate in SiO2'''--> 69.7 nm/min <br> +/- 10.5%
|<!--'''Etch rate in resist'''--> 57.3 nm/min <br> +/- 12.9%
|<!--'''Selectivity (SiO2:resist)'''--> 1.22
|<!--'''Etch rate in Si'''-->
|-
|-
!Structure size (nm)
|'''structure pitch (nm)'''
|'''SiO2 ER (nm/min)'''
|'''Resist ER (nm/min)'''
|'''Selectivity SiO2/resist'''
|
|
|-
|-
|-style="background:white; color:black"
|<!-- '''Recipe name''' --> '''CHF3_t2'''
|<!-- '''SiO2 before etch''' --> CHF<sub>3</sub>= 22.5 sccm <br> Coil= '''150W''' <br> Platen= '''25W''' <br> Press= 2.5mTorr <br> Temp= 20°C <br>
|<!--'''Process time'''--> 25:00 min
|<!--'''Date'''--> 04/09/2023
|<!--'''SEM picture'''--> [[File:CHF3 t2 pat C 05.png|200px]]
|<!--'''SEM pic w/ no resist'''-->
|<!--'''Redeposition - top view'''--> [[File:CHF3 t2 25min af PA 05.png|200px]]
|<!--'''Profile angles'''--> [[File:CHF3 t2 pat C 03.png|200px]]
|<!--'''Etch rate in SiO2'''--> 26.7 nm/min <br> +/- 11.9%
|<!--'''Etch rate in resist'''--> 24.2 nm/min <br> +/- 21.1%
|<!--'''Selectivity (SiO2:resist)'''--> 1.1
|<!--'''Etch rate in Si'''-->
|-
|-
!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
|-
|-
|-style="background:white; color:black"
|<!-- '''Recipe name''' --> '''CHF3 t2'''
|<!-- '''SiO2 before etch''' --> CHF<sub>3</sub>= 22.5 sccm <br> '''H<sub>2</sub>= 22.5 sccm''' <br> Coil= 150W <br> Platen= 25W <br> Press= 2.5mTorr <br> Temp= 20°C <br>
|<!--'''Process time'''--> 10:00 min
|<!--'''Date'''--> 22/09/2023
|<!--'''SEM picture'''--> [[File:CHF3.t2-10H2-25min-C-01.png|200px]]
|<!--'''SEM pic w/ no resist'''-->
|<!--'''Redeposition - top view'''--> [[File:CHF3.t2 22.5H2 10min af PA 02.png|200px]]
|<!--'''Profile angles'''--> [[File:CHF3.t2-10H2-25min-C-08.png|200px]]
|<!--'''Etch rate in SiO2'''--> 9,7 nm/min <br> +/- 34.4%
|<!--'''Etch rate in resist'''--> 1,8 nm/min <br> +/- 46.5%
|<!--'''Selectivity (SiO2:resist)'''--> 5.4
|<!--'''Etch rate in Si'''-->
|-
|-
!500
|1000
|87.04
|114.38
|0.76
|[[File:25.01 CF4ICP 30w 8m-03.png|200px]]
|
|-
|-
|-style="background:white; color:black"
!1000
|<!-- '''Recipe name''' --> CHF3_t1
|2000
|<!-- '''SiO2 before etch''' --> CHF<sub>3</sub>= '''22.5''' sccm <br> '''H<sub>2</sub>= 10''' sccm <br> Coil= 800W <br> Platen= 15W <br> Press= 2.5mTorr <br> Temp= 20°C <br>
|98.83
|<!--'''Process time'''--> 10:00 min
|114.38
|<!--'''Date'''--> 12/09/2023
|0.86
|<!--'''SEM picture'''--> [[File:CHF310 H2 10min 08.png|200px]]
|[[File:25.01 CF4ICP 30w 8m-04.png|200px]]
|<!--'''SEM pic w/ no resist'''-->
|
|<!--'''Redeposition - top view'''--> [[File:CHF310 H2 10min af PA top 01.png|200px]]
|<!--'''Profile angles'''--> [[File:CHF310 H2 10min 10.png|200px]]
|<!--'''Etch rate in SiO2'''--> 59,6 nm/min <br> +/- 12.9%
|<!--'''Etch rate in resist'''--> 47,5 nm/min <br> +/- 21.5%
|<!--'''Selectivity (SiO2:resist)'''--> 1.25
|<!--'''Etch rate in Si'''-->
|-
|-
!2000
|4000
|100.03
|114.38
|0.87
|[[File:25.01 CF4ICP 30w 8m-05.png|200px]]
|
|-
|-
|-style="background:white; color:black"
|}
|<!-- '''Recipe name''' --> CHF3_t1
 
|<!-- '''SiO2 before etch''' --> CHF<sub>3</sub>= '''22.5''' sccm <br> '''O<sub>2</sub>= 10''' sccm <br> Coil= 800W <br> Platen= 15W <br> Press= 2.5mTorr <br> Temp= 20°C <br>
 
|<!--'''Process time'''--> 10:00 min
 
|<!--'''Date'''--> 11/09/2023
{| border="1" style="text-align: center; width: 320px; height: 200px;"
|<!--'''SEM picture'''--> [[File:CHF310 O2 10min 01.png|200px]]
|colspan="7" style="text-align: center;" style="background:LightGrey" |'''CF4lowCP @ 45W platen, 15min'''  
|<!--'''SEM pic w/ no resist'''-->
|<!--'''Redeposition - top view'''--> [[File:CHF310 O2 10min af PA top 02.png|200px]]
|<!--'''Profile angles'''--> [[File:CHF310 O2 10min 04.png|200px]]
|<!--'''Etch rate in SiO2'''--> 60,6 nm/min <br> +/- 10.1%
|<!--'''Etch rate in resist'''--> 130,8 nm/min <br> +/- 8.8%
|<!--'''Selectivity (SiO2:resist)'''--> 0.46
|<!--'''Etch rate in Si'''-->
|-
|-
|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'''
|-
|-
|-style="background:white; color:black"
|<!-- '''Recipe name''' --> CHF3 t1
|<!-- '''SiO2 before etch''' --> CHF<sub>3</sub>= '''22.5''' sccm <br> H<sub>2</sub>= '''22.5''' sccm <br> Coil= 800W <br> Platen= 15W <br> Press= 2.5mTorr <br> Temp= 20°C <br>
|<!--'''Process time'''--> 10:00 min
|<!--'''Date'''--> 20/09/2023
|<!--'''SEM picture'''--> [[File:CHF3=22.5 H2 10min C 01.png|200px]]
|<!--'''SEM pic w/ no resist'''-->
|<!--'''Redeposition - top view'''--> [[File:CHF3.t1 22.5H2 10min af PA 02.png|200px]]
|<!--'''Profile angles'''--> [[File:CHF3=22.5 H2 10min C 03.png|200px]]
|<!--'''Etch rate in SiO2'''--> 47,3 nm/min <br> +/- 12%
|<!--'''Etch rate in resist'''--> 26,4 nm/min <br> +/- 17,4%
|<!--'''Selectivity (SiO2:resist)'''--> 1.8
|<!--'''Etch rate in Si'''-->
|-
|-
!Structure size (nm)
|'''structure pitch (nm)'''
|'''SiO2 ER (nm/min)'''
|'''Resist ER (nm/min)'''
|'''Selectivity SiO2/resist'''
|
|
|-
|-
|-style="background:white; color:black"
|<!-- '''Recipe name''' --> CHF3 t1
|<!-- '''SiO2 before etch''' --> CHF<sub>3</sub>= '''22.5''' sccm <br> H<sub>2</sub>= '''35''' sccm <br> Coil= 800W <br> Platen= 15W <br> Press= 2.5mTorr <br> Temp= 20°C <br>
|<!--'''Process time'''--> 10:00 min
|<!--'''Date'''--> 22/09/2023
|<!--'''SEM picture'''--> [[File:CHF3 35H2 10min C 02.png|200px]]
|<!--'''SEM pic w/ no resist'''-->
|<!--'''Redeposition - top view'''--> [[File:CHF3 35H2 10min af PA 01.png|200px]]
|<!--'''Profile angles'''--> [[File:CHF3 35H2 10min D 05.png|200px]]
|<!--'''Etch rate in SiO2'''--> 36,5 nm/min <br> +/- 10.6%
|<!--'''Etch rate in resist'''--> 17,5 nm/min <br> +/- 13.9%
|<!--'''Selectivity (SiO2:resist)'''--> 2.09
|<!--'''Etch rate in Si'''-->
|-
|-
!250
|500
|33.54
|33.45
|1.0
|[[File:25.01 CF4lowCP 45w 15m-01.png|200px]]
| there was visible redeposition across smaller structures
|-
|-
|-style="background:white; color:black"
|<!-- '''Recipe name''' --> CHF3 t1
|<!-- '''SiO2 before etch''' --> CHF<sub>3</sub>= '''35''' sccm <br> H<sub>2</sub>= '''35''' sccm <br> Coil= 800W <br> Platen= 15W <br> Press= 2.5mTorr <br> Temp= 20°C <br>
|<!--'''Process time'''--> 10:00 min
|<!--'''Date'''--> 22/09/2023
|<!--'''SEM picture'''--> [[File:CHF3 3535H2 10min E 01.png|200px]]
|<!--'''SEM pic w/ no resist'''-->
|<!--'''Redeposition - top view'''--> [[File:CHF3 35.35H2 10min af PA 01.png|200px]]
|<!--'''Profile angles'''--> [[File:CHF3 3535H2 10min C 06.png|200px]]
|<!--'''Etch rate in SiO2'''--> 42 nm/min <br> +/- 15.4%
|<!--'''Etch rate in resist'''--> 23,8 nm/min <br> +/- 22.2%
|<!--'''Selectivity (SiO2:resist)'''--> 1.76
|<!--'''Etch rate in Si'''-->
|-
|-
!500
|1000
|35.94
|30.45
|1.18
|[[File:25.01 CF4lowCP 45w 15m-02.png|200px]]
|
|-
|-
|-style="background:white; color:black"
!1000
|<!-- '''Recipe name''' --> CHF3 t1
|2000
|<!-- '''SiO2 before etch''' --> CHF<sub>3</sub>= 22.5 sccm <br> '''CF<sub>4</sub>= 22.5''' sccm <br> Coil= 800W <br> Platen= 15W <br> Press= 2.5mTorr <br> Temp= 20°C <br>
|36.54
|<!--'''Process time'''--> 10:00 min
|29.85
|<!--'''Date'''--> 22/09/2023
|1.22
|<!--'''SEM picture'''--> [[File:CHF3.t1 22.5CF4 10min C 01.png|200px]]
|[[File:25.01 CF4lowCP 45w 15m-03.png|200px]]
|<!--'''SEM pic w/ no resist'''-->
|
|<!--'''Redeposition - top view'''--> [[File:CHF3 22.5CF4 10min af PA 01.png|200px]]
|<!--'''Profile angles'''--> [[File:CHF3.t1 22.5CF4 10min C 03.png|200px]]
|<!--'''Etch rate in SiO2'''--> 75,8 nm/min <br> +/- 13.1%
|<!--'''Etch rate in resist'''--> 74,9 nm/min <br> +/- 10.8%
|<!--'''Selectivity (SiO2:resist)'''--> 1.01
|<!--'''Etch rate in Si'''-->
|-
|-
|-style="background:white; color:black"
|<!-- '''Recipe name''' --> CHF3 t1
|<!-- '''SiO2 before etch''' --> CHF<sub>3</sub>= '''22.5''' sccm <br> H<sub>2</sub>= '''22.5''' sccm <br> Coil= 800W <br> Platen= 15W <br> '''Press= 25mTorr''' <br> Temp= 20°C <br>
|<!--'''Process time'''--> 10:00 min
|<!--'''Date'''--> 22/09/2023
|<!--'''SEM picture'''--> [[File:CHF3.t122.5H2 25mT 10m C 04.png|200px]]
|<!--'''SEM pic w/ no resist'''-->
|<!--'''Redeposition - top view'''--> [[File:CHF3 22.5H2 25mT 10mn af PA 01.png|200px]]
|<!--'''Profile angles'''--> [[File:CHF3.t122.5H2 25mT 10m C 03.png|200px]]
|<!--'''Etch rate in SiO2'''--> -
|<!--'''Etch rate in resist'''--> -
|<!--'''Selectivity (SiO2:resist)'''--> no etch done,<br> polymer deposited
|<!--'''Etch rate in Si'''-->
|-
|-
|-style="background:white; color:black"
|<!-- '''Recipe name''' --> CHF3 t1
|<!-- '''SiO2 before etch''' --> CHF<sub>3</sub>= 22.5 sccm <br> H<sub>2</sub>= 22.5 sccm <br> Coil= 800W <br> Platen= 15W <br> Press= 2.5mTorr <br> '''Temp= 0°C''' <br>
|<!--'''Process time'''--> 10:00 min
|<!--'''Date'''--> 22/09/2023
|<!--'''SEM picture'''--> [[File:CHF3-22.5-H2-10min-0C-C-03.png|200px]]
|<!--'''SEM pic w/ no resist'''-->
|<!--'''Redeposition - top view'''--> [[File:CHF3 22.5H2 10min 0C af PA 01.png|200px]]
|<!--'''Profile angles'''--> [[File:CHF3-22.5-H2-10min-0C-C-07.png|200px]]
|<!--'''Etch rate in SiO2'''--> 48 nm/min <br> +/- 11.2%
|<!--'''Etch rate in resist'''--> 23,3 nm/min <br> +/- 13.7%
|<!--'''Selectivity (SiO2:resist)'''--> 2.06
|<!--'''Etch rate in Si'''-->
|-
|-
!2000
|4000
|38.09
|28.65
|1.33
|[[File:25.01 CF4lowCP 45w 15m-05.png|200px]]
|
|-
|-
|}
|}


=Etch test of Silicon Nitride=


<br clear="all" />


===Recipes and results - <span style="background:#FFD850">C<sub>4</sub>F<sub>8</sub> / H<sub>2</sub> tests</span> ===
* The nitride layer deposited was 560nm, on the PECVD4 (recipe: Standard HF SiN with wafer clean, for 1h). <br>
* They were patterned with 750 DUV resist and 65nm of BARC (exposure:355 J/m2, focus:-3.1). <br>
* The following results were processed on chips (2*2cm) bonded to a 100mm dummy wafer.
 


{| border="1" cellspacing="1" cellpadding="1"  align="left"
{| border="1" cellspacing="1" cellpadding="1"
! '''Recipe'''
! '''Recipe'''
! '''Recipe parameters'''
! '''Time (min)'''
! '''Process time'''
! '''Date'''
! '''Date'''
! '''SEM picture'''
! '''SEM picture'''
! '''SEM pic w/ no resist'''
! '''Redeposition - top view'''
! '''Redeposition - top view'''
! '''Profile angles'''
! '''Etch rate SiN (nm/min)'''
! '''Etch rate in SiO2'''
! '''Etch rate resist (nm/min)'''
! '''Etch rate in resist <br> (AZ5214E inverse)'''
! '''Selectivity <br> (SiN:resist)'''
! '''Selectivity <br> (SiO2:resist)'''
! '''Etch rate in Si'''  
|-
|-
|-
|-
|-style="background:white; color:black"
|-style="background:white; color:black"
|<!-- '''recipe name''' --> SiO2_ICP
|<!-- '''Recipe name''' --> '''CF4lowCP''' <br> CF<sub>4</sub>= 22.5 sccm <br> H<sub>2</sub>= 22.5 sccm <br> Coil= 150W <br> Platen= '''45W''' <br> Press= 2.5mTorr <br> Temp= 20°C <br>
|<!-- '''SiO2 before etch''' --> C<sub>4</sub>F<sub>8</sub>= '''10''' sccm <br> H<sub>2</sub>= '''28''' sccm <br> Coil= 1000W <br> Platen= 100W <br> Press= 2.5mTorr <br> Temp= 20°C <br>
|<!--'''Process time'''--> 5:00
|<!--'''Process time'''--> 04:00 min
|<!--'''Date'''--> 29/02<br>-2024
|<!--'''Date'''--> 04/09/2023
|<!--'''SEM picture'''--> [[File:Si3N4 pat3 cf4lowcp- 250.png|170px]] [[File:Si3N4 pat3 cf4lowcp- 500.png|170px]] [[File:Si3N4 pat3 cf4lowcp- 1000.png|170px]] [[File:Si3N4 pat3 cf4lowcp- 2000.png|170px]]
|<!--'''SEM picture'''--> [[File:SiO2 ICP 4m pat C 07.png|200px]]
|<!--'''Redeposition - top view'''--> [[File:SiN cf4lowcp sidewalls 01.png|170px]] [[File:SiN cf4lowcp sidewalls 02.png|170px]]
|<!--'''SEM pic w/ no resist'''-->
|<!--'''Etch rate in SiO2'''-->250nm- 76,50 <br> <br>500nm- 73,92 <br> <br>1000nm- 73,94 <br> <br>2000nm- 76,50
|<!--'''Redeposition - top view'''--> [[File:SiO2_ICP 4min af PA 02.png|200px]]
|<!--'''Etch rate in resist'''-->250nm- 44,98 <br> <br>500nm- 33,52 <br> <br>1000nm- 31,16 <br> <br>2000nm- 25,66
|<!--'''Profile angles'''--> [[File:SiO2 ICP 4m pat C 04.png|200px]]
|<!--'''Selectivity (SiO2:resist)'''-->250nm- 1,70 <br> <br>500nm- 2,21 <br> <br>1000nm- 2,37 <br> <br>2000nm- 2,98
|<!--'''Etch rate in SiO2'''--> 211,9 nm/min <br> +/- 14.6%
|<!--'''Etch rate in resist'''--> 153,4 nm/min <br> +/- 16.7%
|<!--'''Selectivity (SiO2:resist)'''--> 1.4
|<!--'''Etch rate in Si'''-->  
|-
|-
|-style="background:white; color:black"
|<!-- '''recipe name''' --> SiO2_ICP
|<!-- '''SiO2 before etch''' --> C<sub>4</sub>F<sub>8</sub>= 10 sccm <br> H<sub>2</sub>= 28 sccm <br> Coil= '''800W''' <br> Platen= '''15W''' <br> Press= 2.5mTorr <br> Temp= 20°C <br>
|<!--'''Process time'''--> 04:00 min
|<!--'''Date'''--> 22/09/2023
|<!--'''SEM picture'''--> [[File:SiO2_ICP 800W-15W 4min C 04.png|200px]]
|<!--'''SEM pic w/ no resist'''-->  
|<!--'''Redeposition - top view'''--> [[File:SiO2_ICP 800.15W 4min af PA 02.png|200px]]
|<!--'''Profile angles'''--> [[File:SiO2_ICP 800W-15W 4min E 04.png|200px]]
|<!--'''Etch rate in SiO2'''--> 134,7 nm/min <br> +/- 20.8%
|<!--'''Etch rate in resist'''--> 145,7 nm/min <br> +/- 25.1%
|<!--'''Selectivity (SiO2:resist)'''--> 0.92
|<!--'''Etch rate in Si'''-->
|-
|-
|-
|-
|}


|}
<br clear="all" />

Latest revision as of 11:54, 29 April 2024

Etch tests of Silicon Oxide

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
71.4
11.7%
0.74
-
-
35 CF4 + 10 H2
69
12.6%
0.89
-
-
22.5 CF4 + 22.5 H2
58.6
13.3%
1.43
84.4
42.9
  • 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
24.9
11.5%
0.47
-
-
35 CF4 + 10 H2
22.6
11.6%
0.64
-
-
22.5 CF4 + 22.5 H2
17.8
13.7%
1.85
28
22.5


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
CF4ICP-45.0c-af-PA-bot-04 1.png 45.10-af-PA-center-07.png CF4lowCP-45.10-22.png CF4ICP-35.10-39.png Low45-0-af-PA-03.png Low45-0-af-PA-08.png Low35-10-af-PA-12.png Low35-10-af-PA-06.png Low22.5-af-PA-08.png Low22.5-af-PA-04.png



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 CF4ICP 11min C 01.png 800px-CF4ICP 11min af PA top 01.png 800px-CF4ICP 11min C 03.png 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 200px-35.10 af ase 04.png 200px-35.10 af PA bot 03.png 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 200px-CF4ICP 45.0c bf PA 04.png 200px-CF4ICP 45.0c af Pa-bot 06.png 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 200px-45.10 af ASE 01.png 200px-45.10 af PA center 07.png 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 CF4lowCP 20m pat C03.png CF4owCP 20min af PA 03.png 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 CF4lowCP 35.10 10.png Low35 10 af PA 12.png 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 CF4lowCP.right 01.png Low45 0 af PA 05.png 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 CF4owCP 20min af PA 03.png 29,4 nm/min
+/- 13.7% 		100,6 nm/min
+/- 16.5% 		0.29



Recent 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).
(25 jan 2024)


CF4ICP @ 30W platen, 8min
Values SEM pictures 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 25.01 CF4ICP 30w 8m-02.png Across the sample, the resist was fully etched away
500 1000 87.04 114.38 0.76 25.01 CF4ICP 30w 8m-03.png
1000 2000 98.83 114.38 0.86 25.01 CF4ICP 30w 8m-04.png
2000 4000 100.03 114.38 0.87 25.01 CF4ICP 30w 8m-05.png


CF4lowCP @ 45W platen, 15min
Values SEM pictures 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 25.01 CF4lowCP 45w 15m-01.png there was visible redeposition across smaller structures
500 1000 35.94 30.45 1.18 25.01 CF4lowCP 45w 15m-02.png
1000 2000 36.54 29.85 1.22 25.01 CF4lowCP 45w 15m-03.png
2000 4000 38.09 28.65 1.33 25.01 CF4lowCP 45w 15m-05.png

Etch test of Silicon Nitride

  • The nitride layer deposited was 560nm, on the PECVD4 (recipe: Standard HF SiN with wafer clean, for 1h).
  • They were patterned with 750 DUV resist and 65nm of BARC (exposure:355 J/m2, focus:-3.1).
  • The following results were processed on chips (2*2cm) bonded to a 100mm dummy wafer.


Recipe Time (min) Date SEM picture Redeposition - top view Etch rate SiN (nm/min) Etch rate resist (nm/min) Selectivity
(SiN:resist)
CF4lowCP
CF4= 22.5 sccm
H2= 22.5 sccm
Coil= 150W
Platen= 45W
Press= 2.5mTorr
Temp= 20°C
5:00 29/02
-2024 		Si3N4 pat3 cf4lowcp- 250.png Si3N4 pat3 cf4lowcp- 500.png Si3N4 pat3 cf4lowcp- 1000.png Si3N4 pat3 cf4lowcp- 2000.png SiN cf4lowcp sidewalls 01.png SiN cf4lowcp sidewalls 02.png 250nm- 76,50

500nm- 73,92

1000nm- 73,94

2000nm- 76,50 		250nm- 44,98

500nm- 33,52

1000nm- 31,16

2000nm- 25,66 		250nm- 1,70

500nm- 2,21

1000nm- 2,37

2000nm- 2,98



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