Specific Process Knowledge/Etch/DRIE-Pegasus/processD: Difference between revisions

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See results in the acceptance report: [[Media:Pegasus_AcceptanceTest.pdf|here]].
See results in the acceptance report: [[Media:Pegasus_AcceptanceTest.pdf|here]].


==Process optimization [[Image:section under construction.jpg|70px]]==
== Effects on Process D of showerhead change in December 2014 ==
''by Frederik Stöhr 2015''
 
The effects of [[Specific Process Knowledge/Etch/DRIE-Pegasus/showerheadchange|changing of the showerhead in December 2014]] was investigated. Patterned wafers were processed before and after and the profile of the etched features were inspected in SEM.
 
Process D is intended to be used for imprinting purposes - that means smooth sidewalls at relatively shallow depths (that means 'not through wafer'). It is therefore natural to exploit the faster switching capability introduced with the new showerhead for this etch process. An improved version of Process D (called Process D4) was found - see the table below.
 
Click on the numbers in the 'Runs' column below to see the profiles.
 
{| border="1" cellpadding="1" cellspacing="0" style="text-align:center;"
|-
! rowspan="2" width="100"| Recipe
! rowspan="2" width="20"| Name
! rowspan="2" width="20"| Temp.
! colspan="6" | Deposition step
! colspan="7" | Etch step
! colspan="3" | Comments
|-
! Time
! Pres.
! C<sub>4</sub>F<sub>8</sub>
! SF<sub>6</sub>
! O<sub>2</sub>
! Coil
! Time
! Pres.
! C<sub>4</sub>F<sub>8</sub>
! SF<sub>6</sub>
! O<sub>2</sub>
! Coil
! Platen
! Showerhead
! Runs
! width="100" | Key words
|-
! rowspan="7" | Process D    <!-- recipe name -->
! Original <!-- step -->
| 0      <!-- chiller temp -->
! 2      <!-- dep time -->
| 20      <!-- dep pressure -->
| 150      <!-- C4F8 flow -->
| 0      <!-- SF6 flow -->
| 0    <!-- O2 flow -->
| 2000      <!-- coil power -->
| 2.4      <!-- etch time -->
| 26      <!-- etch pressure -->
| 0      <!-- C4F8 flow -->
| 275      <!-- SF6 flow -->
| 5      <!-- O2 flow -->
| 2500      <!-- coil power -->
| 35      <!-- platen power -->
! Old      <!-- Showerhead -->
| [[Specific Process Knowledge/Etch/DRIE-Pegasus/showerheadchange/ProcessD/original | 1]]      <!-- link processes -->
|  <!-- keywords -->
|-
! Original <!-- step -->
| 0      <!-- chiller temp -->
! 2      <!-- dep time -->
| 20      <!-- dep pressure -->
| 150      <!-- C4F8 flow -->
| 0      <!-- SF6 flow -->
| 0    <!-- O2 flow -->
| 2000      <!-- coil power -->
| 2.4      <!-- etch time -->
| 26      <!-- etch pressure -->
| 0      <!-- C4F8 flow -->
| 275      <!-- SF6 flow -->
| 5      <!-- O2 flow -->
| 2500      <!-- coil power -->
| 35      <!-- platen power -->
! New      <!-- Showerhead -->
| [[Specific Process Knowledge/Etch/DRIE-Pegasus/showerheadchange/ProcessD/original | 1]]      <!-- link processes -->
|  <!-- keywords -->
|-
! New Process D <!-- step -->
| 0      <!-- chiller temp -->
! 1      <!-- dep time -->
| 20      <!-- dep pressure -->
| 150      <!-- C4F8 flow -->
| 0      <!-- SF6 flow -->
| 0    <!-- O2 flow -->
| 2000      <!-- coil power -->
! 3      <!-- etch time -->
| 26      <!-- etch pressure -->
| 0      <!-- C4F8 flow -->
| 275      <!-- SF6 flow -->
| 5      <!-- O2 flow -->
| 2500      <!-- coil power -->
| 35      <!-- platen power -->
! New      <!-- Showerhead -->
| [[Specific Process Knowledge/Etch/DRIE-Pegasus/showerheadchange/ProcessD/NewProcessD | 4]]      <!-- link processes -->
| Large undercut  <!-- keywords -->
|-
! PrD01 <!-- step -->
| 0      <!-- chiller temp -->
| 1      <!-- dep time -->
| 20      <!-- dep pressure -->
| 150      <!-- C4F8 flow -->
| 0      <!-- SF6 flow -->
| 0    <!-- O2 flow -->
| 2000      <!-- coil power -->
! 2.4      <!-- etch time -->
| 26      <!-- etch pressure -->
| 0      <!-- C4F8 flow -->
| 275      <!-- SF6 flow -->
| 5      <!-- O2 flow -->
| 2500      <!-- coil power -->
| 35      <!-- platen power -->
| New      <!-- Showerhead -->
| [[Specific Process Knowledge/Etch/DRIE-Pegasus/showerheadchange/ProcessD/PrD01 | 2]]      <!-- link processes -->
|  <!-- keywords -->
|-
! PrD02 <!-- step -->
| 0      <!-- chiller temp -->
! 1.1      <!-- dep time -->
| 20      <!-- dep pressure -->
| 150      <!-- C4F8 flow -->
| 0      <!-- SF6 flow -->
| 0    <!-- O2 flow -->
| 2000      <!-- coil power -->
| 2.4      <!-- etch time -->
| 26      <!-- etch pressure -->
| 0      <!-- C4F8 flow -->
| 275      <!-- SF6 flow -->
| 5      <!-- O2 flow -->
| 2500      <!-- coil power -->
| 35      <!-- platen power -->
| New      <!-- Showerhead -->
| [[Specific Process Knowledge/Etch/DRIE-Pegasus/showerheadchange/ProcessD/PrD02 | 1]]      <!-- link processes -->
|  <!-- keywords -->
|-
! PrD-3 <!-- step -->
| 0      <!-- chiller temp -->
| 1      <!-- dep time -->
| 20      <!-- dep pressure -->
| 150      <!-- C4F8 flow -->
| 0      <!-- SF6 flow -->
| 0    <!-- O2 flow -->
| 2000      <!-- coil power -->
! 2.5      <!-- etch time -->
| 26      <!-- etch pressure -->
| 0      <!-- C4F8 flow -->
| 275      <!-- SF6 flow -->
| 5      <!-- O2 flow -->
| 2500      <!-- coil power -->
| 35      <!-- platen power -->
| New      <!-- Showerhead -->
| [[Specific Process Knowledge/Etch/DRIE-Pegasus/showerheadchange/ProcessD/PrD-3 | 1]]      <!-- link processes -->
|  <!-- keywords -->
|-
! PrD-4 <!-- step -->
| 0      <!-- chiller temp -->
| 1      <!-- dep time -->
| 20      <!-- dep pressure -->
| 150      <!-- C4F8 flow -->
| 0      <!-- SF6 flow -->
| 0    <!-- O2 flow -->
| 2000      <!-- coil power -->
! 2.2      <!-- etch time -->
| 26      <!-- etch pressure -->
| 0      <!-- C4F8 flow -->
| 275      <!-- SF6 flow -->
| 5      <!-- O2 flow -->
| 2500      <!-- coil power -->
| 35      <!-- platen power -->
| New      <!-- Showerhead -->
| [[Specific Process Knowledge/Etch/DRIE-Pegasus/showerheadchange/ProcessD/PrD-4 | 1]]      <!-- link processes -->
| Best one so far!  <!-- keywords -->
|-
|}

Revision as of 10:07, 2 June 2016

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Mask information

  • 1 µm of spin coated AZ5214E photoresist, no hardbake
  • Patterned by UV lithography with the ‘Travka 50’ mask
  • 50 % etch load


Process D specifications
Parameter Specification Average result
Etch rate (µm/min) Not specified 2.88
Etched depth (µm) 20-30 28.75
Scallop size (nm) < 30 46
Profile (degs) 85 +/- 5 89.7
Selectivity to AZ photoresist Not specified 50
Undercut (nm) Not specified 65
Uniformity (%) < 3.5 4.56-0.25
Repeatability (%) <4



Process D recipe
Main etch (D->E) Etch Dep
Gas flow (sccm) SF6 275 O2 5 C4F8 150
Cycle time (secs) 2.4 2.0
Pressure (mtorr) 26 20
Coil power (W) 2500 2000
Platen power (W) 35 0
Cycles 110 (process time 08:04)
Common Temperature 0 degs, HBC 10 torr, Long funnel, with baffle & 100 mm spacers

See results in the acceptance report: here.

Effects on Process D of showerhead change in December 2014

The effects of changing of the showerhead in December 2014 was investigated. Patterned wafers were processed before and after and the profile of the etched features were inspected in SEM.

Process D is intended to be used for imprinting purposes - that means smooth sidewalls at relatively shallow depths (that means 'not through wafer'). It is therefore natural to exploit the faster switching capability introduced with the new showerhead for this etch process. An improved version of Process D (called Process D4) was found - see the table below.

Click on the numbers in the 'Runs' column below to see the profiles.

Recipe Name Temp. Deposition step Etch step Comments
Time Pres. C4F8 SF6 O2 Coil Time Pres. C4F8 SF6 O2 Coil Platen Showerhead Runs Key words
Process D Original 0 2 20 150 0 0 2000 2.4 26 0 275 5 2500 35 Old 1
Original 0 2 20 150 0 0 2000 2.4 26 0 275 5 2500 35 New 1
New Process D 0 1 20 150 0 0 2000 3 26 0 275 5 2500 35 New 4 Large undercut
PrD01 0 1 20 150 0 0 2000 2.4 26 0 275 5 2500 35 New 2
PrD02 0 1.1 20 150 0 0 2000 2.4 26 0 275 5 2500 35 New 1
PrD-3 0 1 20 150 0 0 2000 2.5 26 0 275 5 2500 35 New 1
PrD-4 0 1 20 150 0 0 2000 2.2 26 0 275 5 2500 35 New 1 Best one so far!
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