View source for Specific Process Knowledge/Etch/DRIE-Pegasus/Pegasus-2/ORE with Al2O3 mask

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=<span style="background:#FF2800">THIS PAGE IS UNDER CONSTRUCTION</span>[[image:Under_construction.png|200px]]=



''By Maria Farinha @nanolab, Jan 2023''

'''''Important!''''' The pressure settings used below '''''may no longer be permitted''''', always check with the Dry etch group.

As stated by [https://labadviser.nanolab.dtu.dk/images/5/5c/The_CORE_sequence.pdf '''Nguyen et al.'''], the SF<sub>6</sub> and O<sub>2</sub> fluxes are only separated after 4 s during the C-step. Shorter time steps than that do not execute the function of the clearing. After testing recipes with only 2 s of clearing and with no clear step, it was understood it could be eliminated, showing more depth as well as less undercut when going for shorter cycles. From then on, not CORE but ORE recipes were applied D/E = O/RE. 
<br>
Moreover, during the E-step, the MFC (mass flow controller) presented a delay to read the pressure when compared with the power, creating unwanted bias. To fight it, the E-step was divided into E<sub>1</sub> and E<sub>2</sub>. The E<sub>1</sub> of only 2 s is enough to stabilize the pressure, and E<sub>2</sub> the profile is etch correctly, without the unwanted bias.
[[File:graf bias & recipes.png|800px|center|thumb|'''''CORE process graphics and recipes: a) unwanted DC bias during the E-step; b) E-step separated into two steps, E<sub>1</sub> decreased the bias.''''']]

=== Pillars ===

[[File:compare pillars.png|600px|thumb|'''''Pillars with different etching times.''''']]
{| border="1" style="text-align: center; width: 650px; height: 200px"
|+ 1μm Pillar recipe from March 2022
|-
|-style="background:DarkGray; color:White"
!  !! Time (s) !! Pressure (valve control) !! O<sub>2</sub> flow (SCCM) !! SF<sub>6</sub> flow (SCCM) !! Platen power (W)
|-
| '''O-step''' || 10 || 3% || 200 || 0 || 40
|-
| '''R-step''' || 10 || 100% || 0 || 5 || 40
|-
| '''E<sub>1</sub>-step''' || 2 || 4% || 0 || 350 || 40
|-
| '''E<sub>2</sub>-step''' || 7 || 4% || 0 || 350 || 300
|}

<br clear="all" />


=== Holes ===

{| border="1" style="text-align: center; width: 650px; height: 200px"
|+ 1μm holes recipe from March 2022
|-
|-style="background:DarkGray; color:White"
!  !! Time (s) !! Pressure !! O<sub>2</sub> flow (SCCM) !! SF<sub>6</sub> flow (SCCM) !! Platen power (W) !! Coil power (W)
|-
| '''O-step''' || 10 || 220 mTorr || 200 || 0 || 40 || 0
|-
| '''R-step''' || 10 || 100% || 0 || 40 || 40 || 0
|-
| '''E<sub>1</sub>-step''' || 2 || 220 mTorr || 0 || 1200 || 0 || 0
|-
| '''E<sub>2</sub>-step''' || 1-5 || 220 mTorr || 0 || 1200 || 1 || 2000
|}
[[File:drawing (1) (1).png|400px|thumb|'''''17.6 μm holes profile.''''']]


=== Nanoholes ===

{| border="1" style="text-align: center; width: 650px; height: 200px"
|+ 200nm nanoholes recipe from March 2022
|-
|-style="background:DarkGray; color:White"
!  !! Time (s) !! Pressure (valve control) !! O<sub>2</sub> flow (SCCM) !! SF<sub>6</sub> flow (SCCM) !! Platen power (W)
|-
| '''O-step''' ||  ||  ||  ||  || 
|-
| '''R-step''' ||  ||  ||  ||  || 
|-
| '''E<sub>1</sub>-step''' ||  ||  ||  ||  || 
|-
| '''E<sub>2</sub>-step''' ||  ||  ||  ||  || 
|}

=== Isotropic etch ===



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