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| '''Feedback to this page:
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| [mailto:plasma@danchip.dtu.dk?Subject=Feed%20back%20from%20page%20http://labadviser.danchip.dtu.dk/index.php/Specific_Process_Knowledge/Etch/DRIE-Pegasus/FAQ/Nanoetch click here]'''
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| ; Question
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| : One of our 'popular' etches on the old ASE, a switched etch of nanostructures , is proving very difficult to transfer to the Pegasus. The structures are typically e-beam defined channels or holes a few hundred nanometers wide and masked with 50-100 nm ZEP resist. The etch load is usually very low, less than a few percent. We would like to go as much as 1 µm down. (I have been on paternity leave during the summer and I am sitting at home with my son right now so I don't have/know the complete story but I will get it for you if needed.) Do you have a suggestion to a starting point for such an etch?
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| ; Answer
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| :Congratulations of your new addition! I can suggest a starting point for this but it would probably be best to wait until you can send me the additional details.
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| Three different examples of etch are shown here. The masking material was zep520A (80 nm).
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| {| border="1" cellspacing="1" cellpadding="2" align="left"
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| ! Vertical sidewalls
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| ! Low ARDE
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| ! Positive tappered side walls
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| | [[Image:WF_2A_n5_jan02_06_1x_100_75.jpg|250x250px]]
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| |[[Image:WF_2C_n5_nov3_06_1x_100_75.jpg|250x250px]]
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| |[[Image:WF_2D_n6_sep19_05_1x_100_75.jpg|250x250px]]
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| |[[Image:WF_2A_n5_jan02_06_3x_overview.jpg|250x250px]]
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| |[[Image:WF_2C_n5_nov3_06_overview.jpg|250x250px]]
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| |[[Image:WF_2D_n6_sep19_05_1x_overview.jpg|250x250px]]
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| Etch cycle
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| *SF6 flow [sccm]:50
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| *C4F8 flow [sccm]:100
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| *Pressure [mTorr] 20
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| *Coil power [W]: 350
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| *Platen power [W]: 30
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| *Cycle Time [s]: 5
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| Dep. Cycle
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| *C4F8 flow [sccm]: 100
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| *Pressure [mTorr]: 20
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| *Coil power [W]: 500
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| *Platen power [W]: 0
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| *Cycle Time [s]: 3
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| *Temperature [Deg. C] 20
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| Results:
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| *Etch rate of 100nm lines: 146nm/min @etch time: 1:36min.
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| Etch cycle
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| *SF6 flow [sccm]:50
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| *C4F8 flow [sccm]:100
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| *Pressure [mTorr] 10
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| *Coil power [W]: 350
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| *Platen power [W]: 30
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| *Cycle Time [s]: 5
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| Dep. Cycle
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| *C4F8 flow [sccm]: 100
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| *Pressure [mTorr]: 10
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| *Coil power [W]: 500
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| *Platen power [W]: 0
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| *Cycle Time [s]: 3
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| *Temperature [Deg. C] -10
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| Results:
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| *Etch rate of 100nm lines: 131nm/min @etch time: 1:36min.
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| Etch cycle
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| *SF6 flow [sccm]:50
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| *C4F8 flow [sccm]:100
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| *Pressure [mTorr] 10
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| *Coil power [W]: 350
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| *Platen power [W]: 10
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| *Cycle Time [s]: 5
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| Dep. Cycle
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| *C4F8 flow [sccm]: 100
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| *Pressure [mTorr]: 10
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| *Coil power [W]: 500
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| *Platen power [W]: 0
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| *Cycle Time [s]: 3
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| *Temperature [Deg. C] 20
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| Results:
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| *Etch rate of 100nm lines: 209nm/min @etch time: 2:56min.
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| |}
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| ; Question
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| : I have attached some images/summary of the nanoetches produced on the ASE and that we haven't been able to transfer to the Pegasus. What we are interested in is making small holes/trenches down to 30 nm diameter/width using ZEP520A E-beam resist as masking, hopefully as deep as 500 nm and (because of the small openings) with excellent selectivity. There is, in fact, a lot of need for this recipe so I really hope that you can help me with a starting point.
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| ;Question
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| : Nano-scale etching on the Pegasus is relatively rare, however I would imagine that it should be possible to get similar results to those achieved in ICP. The process below was used to etch trenches of ~125nm to a depth of ~150nm with very low CD loss and smooth sidewall. The process was used to only etch a small amount to define the opening of the structure; following this a standard Bosch process was used to etch to several microns depth so we did not look at selectivity of this first opening step.
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| : 38SF6, 52C4F8, 4mT, 800W Coil, 50W platen, Platen @10°C, 38s to achieve 150nm depth.
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| : The process was run in long funnel configuration; if you are using short funnel, I would expect that a reduction of platen power would be needed but ultimately selectivity with long funnel is likely to be better.
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| : I will send the details on the positive profile etching shortly.
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