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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link="#0563C1" vlink="#954F72"><div class=WordSection1><p class=MsoNormal>Hi all,<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>I recently acquired a graphite/SiC susceptor for 3” wafers from Allwin21 for annealing GaAs samples in our Heatpulse 610 RTA and would like to solicit advise on proper use. Due to the expense and leadtime of a new susceptor, I would like to take every precaution as we develop this process.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Anneal temperatures will be on the order of 400 to 450C, holding for up to 60s. I will be annealing small pieces (4x8 mm^2), ¼ 3” wafers and very rarely 3” wafers.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>I have been reading through RTA SOPs that mention susceptor usage.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><a href="https://wiki.nbi.ku.dk/cleanroom/AccuThermo_RTA">KU</a> recommends a ramp not exceeding 15C/s, and to not heat the susceptor without a sample inside.<o:p></o:p></p><p class=MsoNormal><a href="https://louisville.edu/micronano/files/documents/standard-operating-procedures/RTPSOP.pdf">Louisville</a> recommends inserting the TC 1cm into the susceptor chamber.<o:p></o:p></p><p class=MsoNormal><a href="http://www.cen.iitb.ac.in/slotbooking/SOP/164_SOP.pdf">IITB</a> has an appendix on susceptor usage. They say to never submerge the susceptor in liquid, but suggest certain chemicals for cleaning (with wipes?). Additionally, they suggest changing the wafer type to susceptor in the recipe.<o:p></o:p></p><p class=MsoNormal><a href="https://www3.nd.edu/~ndnf/facilities/manuals/Allwin%20manual.pdf">Allwin</a> manual gives instructions on susceptor calibration and recipe creation.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Our tool runs Allwin21 RTA-610 V7.85C, for reference.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><b>Questions<o:p></o:p></b></p><p class=MsoListParagraph style='text-indent:-.25in;mso-list:l0 level1 lfo1'><![if !supportLists]><span style='mso-list:Ignore'>1.<span style='font:7.0pt "Times New Roman"'> </span></span><![endif]>Is it necessary to run a lamp/chamber calibration for the susceptor, or can one get away with the existing wafer cal?<o:p></o:p></p><p class=MsoListParagraph style='margin-left:1.0in;text-indent:-.25in;mso-list:l0 level2 lfo1'><![if !supportLists]><span style='mso-list:Ignore'>a.<span style='font:7.0pt "Times New Roman"'> </span></span><![endif]>Assuming a recipe with 60s ramp (<7C/s) and 60s/400-450C hold.<o:p></o:p></p><p class=MsoListParagraph style='margin-left:1.0in;text-indent:-.25in;mso-list:l0 level2 lfo1'><![if !supportLists]><span style='mso-list:Ignore'>b.<span style='font:7.0pt "Times New Roman"'> </span></span><![endif]>Is there any risk with running a conservative recipe (above) and looking to see if wafer-cal undershoot is manageable?<o:p></o:p></p><p class=MsoListParagraph style='margin-left:1.0in;text-indent:-.25in;mso-list:l0 level2 lfo1'><![if !supportLists]><span style='mso-list:Ignore'>c.<span style='font:7.0pt "Times New Roman"'> </span></span><![endif]>Is it ok to have the cal be at low powers (i.e. <10%) since the process temp is so low, to prevent potential damage/wear?<o:p></o:p></p><p class=MsoListParagraph style='text-indent:-.25in;mso-list:l0 level1 lfo1'><![if !supportLists]><span style='mso-list:Ignore'>2.<span style='font:7.0pt "Times New Roman"'> </span></span><![endif]>Can the susceptor be empty during calibration and/or when running a recipe?<o:p></o:p></p><p class=MsoListParagraph style='margin-left:1.0in;text-indent:-.25in;mso-list:l0 level2 lfo1'><![if !supportLists]><span style='mso-list:Ignore'>a.<span style='font:7.0pt "Times New Roman"'> </span></span><![endif]>I assume calibrating empty would lead to minor undershoot with a sample due to increased thermal mass w.r.t. the calibration.<o:p></o:p></p><p class=MsoListParagraph style='margin-left:1.0in;text-indent:-.25in;mso-list:l0 level2 lfo1'><![if !supportLists]><span style='mso-list:Ignore'>b.<span style='font:7.0pt "Times New Roman"'> </span></span><![endif]>Any idea why KU warns against running without a sample?<o:p></o:p></p><p class=MsoListParagraph style='text-indent:-.25in;mso-list:l0 level1 lfo1'><![if !supportLists]><span style='mso-list:Ignore'>3.<span style='font:7.0pt "Times New Roman"'> </span></span><![endif]>Should a ramp down be specified to control cooling?<o:p></o:p></p><p class=MsoListParagraph style='text-indent:-.25in;mso-list:l0 level1 lfo1'><![if !supportLists]><span style='mso-list:Ignore'>4.<span style='font:7.0pt "Times New Roman"'> </span></span><![endif]>Can the TC be touching the backside of the susceptor as is done with a silicon wafer?<o:p></o:p></p><p class=MsoListParagraph style='margin-left:1.0in;text-indent:-.25in;mso-list:l0 level2 lfo1'><![if !supportLists]><span style='mso-list:Ignore'>a.<span style='font:7.0pt "Times New Roman"'> </span></span><![endif]>I don’t think I can set up the TC any other way as this would affect other users of the tool.<o:p></o:p></p><p class=MsoListParagraph style='margin-left:1.0in;text-indent:-.25in;mso-list:l0 level2 lfo1'><![if !supportLists]><span style='mso-list:Ignore'>b.<span style='font:7.0pt "Times New Roman"'> </span></span><![endif]>I am happy to reduce the ramp rate further if necessary.<o:p></o:p></p><p class=MsoListParagraph style='text-indent:-.25in;mso-list:l0 level1 lfo1'><![if !supportLists]><span style='mso-list:Ignore'>5.<span style='font:7.0pt "Times New Roman"'> </span></span><![endif]>Is O2 plasma safe/sufficient for cleaning?<o:p></o:p></p><p class=MsoListParagraph style='margin-left:1.0in;text-indent:-.25in;mso-list:l0 level2 lfo1'><![if !supportLists]><span style='mso-list:Ignore'>a.<span style='font:7.0pt "Times New Roman"'> </span></span><![endif]>I’d prefer to avoid wet cleaning as the increased handling increases risk of accidental damage.<o:p></o:p></p><p class=MsoListParagraph style='margin-left:1.0in;text-indent:-.25in;mso-list:l0 level2 lfo1'><![if !supportLists]><span style='mso-list:Ignore'>b.<span style='font:7.0pt "Times New Roman"'> </span></span><![endif]>The susceptor will be used by a single user for GaAs MMICs.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Any other advice on susceptor usage would also be greatly appreciated!<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Thanks in advance,<o:p></o:p></p><p class=MsoNormal>Matt<o:p></o:p></p><p class=MsoNormal><span style='color:#BFBFBF;mso-style-textfill-fill-color:#BFBFBF;mso-style-textfill-fill-alpha:100.0%'>PhD student<o:p></o:p></span></p><p class=MsoNormal><span style='color:#BFBFBF;mso-style-textfill-fill-color:#BFBFBF;mso-style-textfill-fill-alpha:100.0%'>UW-Madison</span><o:p></o:p></p></div></body></html>