Specific Process Knowledge/Etch/DRIE-Pegasus/Pegasus-2/ORE with Al2O3 mask: Difference between revisions

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 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.
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-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.
+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 etched correctly, without the unwanted bias.
-[[File:graf bias & recipes.png|600px|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. From @Nanolab internal, March 2022''''']]
+[[File:graf bias & recipes.png|600px|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. Scheme: Maria Farinha @DTU Nanolab, March 2022''''']]
-Going further, the process is set with 4 steps, Oxidize, Removal, E<sub>1</sub> and E<sub>2</sub> steps. In the E<sub>1</sub>, the pressure will rise, without power applied, so that for the E<sub>2</sub> the pressure is already rising and the power starts to be applied.
+Going further, the process is set with 4 steps, Oxidize, Removal, E<sub>1</sub> and E<sub>2</sub> steps. In the E<sub>1</sub>, the pressure will rise, without power applied, so for the E<sub>2</sub> the pressure is already rising and the power starts to be applied.
 === Pillars ===
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 === Holes ===
-Using patterned samples of 1 μm holes with 50 nm of Al<sub>2</sub>O<sub>3</sub>. After the tests, approximately 28nm of Al<sub>2</sub>O<sub>3</sub> were still intact. When using this recipe, by adjusting the number of cycles, approximately 10 μm were achieved maintaining a straight profile. When going for deeper profiles, 17 μm were also achieved, but the profile starts to get positive. Further work may solve the issue. During the recipe, Pegasus 2 conditions were: Outer EM=10A, T=20°C, no clamping, no He BGC and all heaters OFF.
+Using patterned samples of 1 μm holes with 50 nm of Al<sub>2</sub>O<sub>3</sub>. After the tests, approximately 28nm of Al<sub>2</sub>O<sub>3</sub> were still intact. When using this recipe, by adjusting the number of cycles, approximately 10 μm was achieved maintaining a straight profile. When going for deeper profiles, 17 μm was also achieved, but the profile started to get positive. Further work may solve the issue. During the recipe, Pegasus 2 conditions were: Outer EM=10A, T=20°C, no clamping, no He BGC and all heaters OFF.
 [[File:holes 17 e 10 um.png|400px|left|thumb|'''''Holes profile. #144 cycles for 60 min and #288 cycles for 120 min.''''']]
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