<div dir="ltr"><font color="#000000" face="Times New Roman" size="3">
</font><p style="margin:0cm 0cm 0pt"><font color="#000000" face="Calibri" size="3">Dear Jing,</font></p><font color="#000000" face="Times New Roman" size="3">
</font><p style="margin:0cm 0cm 0pt"><font color="#000000" face="Calibri" size="3"> </font></p><font color="#000000" face="Times New Roman" size="3">
</font><p style="margin:0cm 0cm 0pt"><font color="#000000" face="Calibri" size="3">The surface of the targets can look vastly different
depending on the process conditions they have been used with.</font></p><font color="#000000" face="Times New Roman" size="3">
</font><p style="margin:0cm 0cm 0pt"><font color="#000000" face="Calibri" size="3"> </font></p><font color="#000000" face="Times New Roman" size="3">
</font><p style="margin:0cm 0cm 0pt"><font color="#000000" face="Calibri" size="3">Some parameters that will influence this:</font></p><font color="#000000" face="Times New Roman" size="3">
</font><ul style="list-style-type:disc;direction:ltr"><li style="color:rgb(0,0,0);font-family:"Calibri","sans-serif";font-size:11pt;font-style:normal;font-weight:normal"><p style="color:rgb(0,0,0);font-family:"Calibri","sans-serif";font-size:11pt;font-style:normal;font-weight:normal;margin-top:0cm;margin-bottom:0pt">The power that goes into the target during
sputtering – plasma power minus backside cooling</p></li><li style="color:rgb(0,0,0);font-family:"Calibri","sans-serif";font-size:11pt;font-style:normal;font-weight:normal"><p style="color:rgb(0,0,0);font-family:"Calibri","sans-serif";font-size:11pt;font-style:normal;font-weight:normal;margin-top:0cm;margin-bottom:0pt">Plasma density: the type of magnets used in the
magnetron, and the power source type (DC/RF/HiPIMS)</p></li><li style="color:rgb(0,0,0);font-family:"Calibri","sans-serif";font-size:11pt;font-style:normal;font-weight:normal"><p style="color:rgb(0,0,0);font-family:"Calibri","sans-serif";font-size:11pt;font-style:normal;font-weight:normal;margin-top:0cm;margin-bottom:0pt">If reactive sputtering was used; including a chamber
or argon line leak</p></li></ul><font color="#000000" face="Times New Roman" size="3">
</font><p style="margin:0cm 0cm 0pt"><font color="#000000" face="Calibri" size="3">You can often observe target recrystallization and grain
growth if the plasma power is too high.</font></p><font color="#000000" face="Times New Roman" size="3">
</font><p style="margin:0cm 0cm 0pt"><font color="#000000" face="Calibri" size="3"> </font></p><font color="#000000" face="Times New Roman" size="3">
</font><p style="margin:0cm 0cm 0pt"><font color="#000000" face="Calibri" size="3">There must be already stronger than standard magnets in the magnetron, since
cobalt is ferromagnetic. The cross-sections of the racetrack patterns show that
you have different strength magnets as well – eg. the bottom left target shows
a sharp V-shape. This magnet was about double as strong as the one used with
the target on the top left. </font></p><font color="#000000" face="Times New Roman" size="3">
</font><p style="margin:0cm 0cm 0pt"><font color="#000000" face="Calibri" size="3"> </font></p><font color="#000000" face="Times New Roman" size="3">
</font><p style="margin:0cm 0cm 0pt"><font color="#000000" face="Calibri" size="3">The matte surface can result either from low plasma powers
or from a compound formed on the target during sputtering. In my experience this
looks like the latter, probably from a leak in the argon line. See the dark
grey central disc on the target in the top row, center. This should be porous
cobalt oxide, might be useful to check with EDX or XRF.</font></p><font color="#000000" face="Times New Roman" size="3">
</font><p style="margin:0cm 0cm 0pt"><font color="#000000" face="Calibri" size="3"> </font></p><font color="#000000" face="Times New Roman" size="3">
</font><p style="margin:0cm 0cm 0pt"><font color="#000000" face="Calibri" size="3">The supplier is not relevant in this aspect; these surfaces can
be obtained with targets from any source.</font></p><font color="#000000" face="Times New Roman" size="3">
</font><p style="margin:0cm 0cm 0pt"><font color="#000000" face="Calibri" size="3"> </font></p><font color="#000000" face="Times New Roman" size="3">
</font><p style="margin:0cm 0cm 0pt"><font color="#000000" face="Calibri" size="3">I would recommend the following:</font></p><font color="#000000" face="Times New Roman" size="3">
</font><ul style="list-style-type:disc;direction:ltr"><li style="color:rgb(0,0,0);font-family:"Calibri","sans-serif";font-size:11pt;font-style:normal;font-weight:normal"><p style="color:rgb(0,0,0);font-family:"Calibri","sans-serif";font-size:11pt;font-style:normal;font-weight:normal;margin-top:0cm;margin-bottom:0pt">Run a leak check on the argon line with a RGA</p></li><li style="color:rgb(0,0,0);font-family:"Calibri","sans-serif";font-size:11pt;font-style:normal;font-weight:normal"><p style="color:rgb(0,0,0);font-family:"Calibri","sans-serif";font-size:11pt;font-style:normal;font-weight:normal;margin-top:0cm;margin-bottom:0pt">Use a getter metal (Zr, Ti, Al) and check the oxygen
content of deposited films</p></li><li style="color:rgb(0,0,0);font-family:"Calibri","sans-serif";font-size:11pt;font-style:normal;font-weight:normal"><p style="color:rgb(0,0,0);font-family:"Calibri","sans-serif";font-size:11pt;font-style:normal;font-weight:normal;margin-top:0cm;margin-bottom:0pt">Decrease power if you see large, mm-sized grains</p></li><li style="color:rgb(0,0,0);font-family:"Calibri","sans-serif";font-size:11pt;font-style:normal;font-weight:normal"><p style="color:rgb(0,0,0);font-family:"Calibri","sans-serif";font-size:11pt;font-style:normal;font-weight:normal;margin-top:0cm;margin-bottom:0pt">Check if backside water cooling is sufficient</p></li></ul><font color="#000000" face="Times New Roman" size="3">
</font><p style="margin:0cm 0cm 0pt"><font color="#000000" face="Calibri" size="3"> </font></p><font color="#000000" face="Times New Roman" size="3">
</font><p style="margin:0cm 0cm 0pt"><font color="#000000" face="Calibri" size="3">I hope this helps!</font></p><font color="#000000" face="Times New Roman" size="3">
</font><p style="margin:0cm 0cm 0pt"><font color="#000000" face="Calibri" size="3"> </font></p><font color="#000000" face="Times New Roman" size="3">
</font><p style="margin:0cm 0cm 0pt"><font color="#000000" face="Calibri" size="3">All the best,</font></p><font color="#000000" face="Times New Roman" size="3">
</font><p style="margin:0cm 0cm 0pt"><font color="#000000" face="Calibri" size="3">Laszlo</font></p><font color="#000000" face="Times New Roman" size="3">
</font><p style="margin:0cm 0cm 0pt"><font color="#000000" face="Calibri" size="3"> </font></p><font color="#000000" face="Times New Roman" size="3">
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</font><p style="margin:0cm 0cm 0pt"><a name="_MailAutoSig"><span><font color="#000000" face="Calibri" size="3">Laszlo
Pethö</font></span></a></p><font color="#000000" face="Times New Roman" size="3">
</font><p style="margin:0cm 0cm 0pt"><span><span><font color="#000000" face="Calibri" size="3">Scientist</font></span></span></p><font color="#000000" face="Times New Roman" size="3">
</font><p style="margin:0cm 0cm 0pt"><span><span><font color="#000000" face="Calibri" size="3">Empa</font></span></span></p><font color="#000000" face="Times New Roman" size="3">
</font><p style="margin:0cm 0cm 0pt"><span><span><font color="#000000" face="Calibri" size="3">Swiss Federal Laboratories for Materials Science and
Technology</font></span></span></p><font color="#000000" face="Times New Roman" size="3">
</font><p style="margin:0cm 0cm 0pt"><span><span lang="DE-CH"><font color="#000000" face="Calibri" size="3">Feuerwerkerstrasse 39</font></span></span></p><font color="#000000" face="Times New Roman" size="3">
</font><p style="margin:0cm 0cm 0pt"><span><span lang="DE-CH"><font color="#000000" face="Calibri" size="3">3602 Thun</font></span></span></p><font color="#000000" face="Times New Roman" size="3">
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</font><p style="margin:0cm 0cm 0pt"><span><span lang="DE-CH"><font color="#000000" face="Calibri" size="3">Tel <span class="baec5a81-e4d6-4674-97f3-e9220f0136c1" style="white-space:nowrap">+41 58 765 63 45</span></font></span></span></p><font color="#000000" face="Times New Roman" size="3">
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</font></div><div class="gmail_extra"><br><div class="gmail_quote">On Mon, Jan 8, 2018 at 5:15 PM, Guo, Jing <span dir="ltr"><<a href="mailto:jguo5@central.uh.edu" target="_blank">jguo5@central.uh.edu</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="-ms-word-wrap: break-word;">Dear Colleagues,<div><br></div><div>Happy new year!</div><div><br></div><div>I found a lot of used Co targets while I was checking all the sputtering targets. They are all Co targets from two orders which showed different property as shown in the attachment. <br><div><br></div><div>For the top row, all of them surface is shinning but the sputtered ring is not perfect round shape and sharp. </div><div>For the second row, the surface is quite different from the top row. And the sputtering mark/ring is sharp and round. </div><div><br></div><div>The second picture is Ag (99.99%) targets from different company. The surface showed different property after sputtering also. </div><div><br></div><div>I guess the difference came from the different fabrication process to make the targets. Is there anyone familiar about the targets fabrication process? Will this difference affect the sputtering property? </div><div>Could you please advise which type of the targets should be ordered next time?</div><div><br></div><div>Thank you.</div><div><br></div><div><br></div><div><br></div><div>Best Regards,</div><div><br></div><div>Jing</div><div><br></div><div><div><font color="#333333" face="Helvetica Neue, Helvetica, Arial, sans-serif"><span style="font-size:14px">Research Lab Supervisor</span></font></div><div><font color="#333333" face="Helvetica Neue, Helvetica, Arial, sans-serif"><span style="font-size:14px">Nanofabrication Facility</span></font></div><div><font color="#333333" face="Helvetica Neue, Helvetica, Arial, sans-serif"><span style="font-size:14px">University of Houston</span></font></div><div><font color="#333333" face="Helvetica Neue, Helvetica, Arial, sans-serif"><span style="font-size:14px">Postal Address: </span></font></div><div><font color="#333333" face="Helvetica Neue, Helvetica, Arial, sans-serif"><span style="font-size:14px">UNIVERSITY OF HOUSTON</span></font></div><div><font color="#333333" face="Helvetica Neue, Helvetica, Arial, sans-serif"><span style="font-size:14px">NANOFABRICATION FACILITY</span></font></div><div><font color="#333333" face="Helvetica Neue, Helvetica, Arial, sans-serif"><span style="font-size:14px">3517 CULLEN BLVD, RM 1011</span></font></div><div><font color="#333333" face="Helvetica Neue, Helvetica, Arial, sans-serif"><span style="font-size:14px">HOUSTON TX 77204-5062</span></font></div><div><font color="#333333" face="Helvetica Neue, Helvetica, Arial, sans-serif"><span style="font-size:14px">Phone: <a href="tel:(832)%20842-8822" target="_blank" value="+18328428822">832-842-8822</a></span></font></div><div><span style="color:rgb(51,51,51);font-family:"Helvetica Neue",Helvetica,Arial,sans-serif;font-size:14px">Email: <a href="mailto:jguo5@central.uh.edu" target="_blank">jguo5@central.uh.edu</a></span></div><div><font color="#333333" face="Helvetica Neue, Helvetica, Arial, sans-serif"><span style="font-size:14px">Web: <a href="http://www.uh.edu/nanofab" target="_blank">www.uh.edu/nanofab</a></span></font></div></div><div><br></div><div><img width="640" height="421" id="m_8232286249241805373511DDD5C-61D3-4F68-8E43-B006EA3F6620" src="cid:2A56ACF0-B851-4F27-B157-F49FE6E5AD2E@uh.edu"><img width="480" height="640" id="m_82322862492418053731E572988-C5AF-4D36-8660-D19A5910C888" src="cid:F607D494-473A-4370-9716-7DC609CE5FA3@uh.edu"></div></div></div><br>______________________________<wbr>_________________<br>
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