<html>
<head>
<meta content="text/html; charset=ISO-8859-1"
http-equiv="Content-Type">
</head>
<body text="#000000" bgcolor="#FFFFFF">
Depositing ZnS and CdS (as you mentioned in the earlier e-mail) are
both difficult tasks particularly for the equipment person. There
are several issues (1) health hazard, (2) deterioration of the
vacuum system including the pumping station (2) equipment and
process area contamination, (3) cross contamination for all other
depositions done in the same system, and (4) process and quality
control for ZnS and CdS and, more importantly, for other
materials deposited in the same system. The contamination issue
itself is quite serious. <br>
<br>
These materials will contaminate the chamber permanently
particularly with all the non-stoichiometric material that will be
produced during the deposition. It will reach every surface
including locations that are not in the line of sight from the
source. Removing the material completely from the chamber is
virtually impossible. Then you end up having perpetual cross
contamination, out-gassing, and corrosion problems. You shouldn't
use the vacuum system for these materials if it is critical to other
processes involving device quality materials (pure metals,
silicides, nitrides, photoconductors, superconductors, optical
films etc). The contamination will remain in the system for ever
and you will see traces of it in subsequent runs. Materials
analysis techniques may not show it but it will manifest as bad
films (e.g. quenched superconducting transition temperature or
deterioration of similar other properties that are affected by
extremely low level trace contamination). <br>
<br>
Sometimes you can risk making a run for an extremely important
project if the user shares in the risk. "Somehow managing one or
two runs" will depend on the system design and how you maintain it.
The runs can be scheduled just before you take apart the system for
a major wet chemical clean up and rebuilding with new vacuum
components. I would install deposition shields all over the chamber
and also try to use a chimney (metallic tube or duct) if possible
to restrict the material in the target-to-substrate region only. I
have done this a number of times but it is extremely disruptive and
time consuming. It creates a precedence too. <br>
<br>
See Zn vapor pressure on chart 14 of this presentation: <br>
<a class="moz-txt-link-freetext" href="http://www.cockcroft.ac.uk/education/PG_courses_2006-7/RR_vacuum_2007/Reid_Lecture_5.ppt">http://www.cockcroft.ac.uk/education/PG_courses_2006-7/RR_vacuum_2007/Reid_Lecture_5.ppt</a><br>
<br>
There are some references to sputtering similar solar cell materials
that would allow you to contact the authors directly or send samples
out for deposition.<br>
<a class="moz-txt-link-freetext" href="http://www.hindawi.com/journals/ijp/2011/801292/">http://www.hindawi.com/journals/ijp/2011/801292/</a><br>
<br>
Propose alternate techniques. Here is info on SILAS. This would
involve safety precautions/systems for use of exotic vapors/gases.
<br>
<a class="moz-txt-link-freetext" href="http://www.sciencedirect.com/science/article/pii/S0169433297002481">http://www.sciencedirect.com/science/article/pii/S0169433297002481</a><br>
<br>
Good luck....<br>
<pre class="moz-signature" cols="72">Pramod C Karulkar Ph. D.
Home 2*5*3* 3*0*3 0*4*1*8
6024 33rd Street Ct NW
Gig Harbor WA 98335 </pre>
<br>
<br>
<br>
<br>
<br>
<br>
<div class="moz-cite-prefix"> 5/9/2013 10:53 PM, raghavan wrote:<br>
</div>
<blockquote cite="mid:013201ce4d42$b1079ed0$1316dc70$@iisc.ernet.in"
type="cite">
<meta http-equiv="Content-Type" content="text/html;
charset=ISO-8859-1">
<meta name="Generator" content="Microsoft Word 12 (filtered
medium)">
<style><!--
/* Font Definitions */
@font-face
{font-family:"Cambria Math";
panose-1:2 4 5 3 5 4 6 3 2 4;}
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0cm;
margin-bottom:.0001pt;
font-size:11.0pt;
font-family:"Calibri","sans-serif";}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:blue;
text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
{mso-style-priority:99;
color:purple;
text-decoration:underline;}
span.EmailStyle17
{mso-style-type:personal-compose;
font-family:"Calibri","sans-serif";
color:windowtext;}
.MsoChpDefault
{mso-style-type:export-only;}
@page WordSection1
{size:612.0pt 792.0pt;
margin:72.0pt 72.0pt 72.0pt 72.0pt;}
div.WordSection1
{page:WordSection1;}
--></style><!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</o:shapelayout></xml><![endif]-->
<div class="WordSection1">
<p class="MsoNormal">Dear all<o:p></o:p></p>
<p class="MsoNormal">We have a request from a tool user to
sputter ZnS in our sputter tool. Our sputter tool is a share
tool used by many users. I would like to know from experienced
users if ZnS sputtering needs any extra precautions to be
taken? Does it contaminate the chamber? <o:p></o:p></p>
<p class="MsoNormal">Thank you <o:p></o:p></p>
<p class="MsoNormal">Best wishes<o:p></o:p></p>
<p class="MsoNormal">Raghavan<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span style="color:gray">*************************************************</span><span
style="font-family:"Times New
Roman","serif";color:gray"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:gray">Dr.Vijayaraghavan<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:gray">Technology Manager<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:gray">National
Nanofabrication Centre <o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:gray">Centre for Nano
Science and Engineering<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:gray">Indian institute
of Science ( IISc)<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:gray">Bangalore - 560
012<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:gray">India<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:gray">Ph: 09663304316<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:gray"><a class="moz-txt-link-freetext" href="http://sindhu.ece.iisc.ernet.in/nanofab/twikii/bin/view/Main/WebHome">http://sindhu.ece.iisc.ernet.in/nanofab/twikii/bin/view/Main/WebHome</a><o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:gray">***************************************************<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<br>
-- <br>
This message has been scanned for viruses and
<br>
dangerous content by
<a moz-do-not-send="true" href="http://www.mailscanner.info/"><b>MailScanner</b></a>,
and is
<br>
believed to be clean.
<br>
<fieldset class="mimeAttachmentHeader"></fieldset>
<br>
<pre wrap="">_______________________________________________
labnetwork mailing list
<a class="moz-txt-link-abbreviated" href="mailto:labnetwork@mtl.mit.edu">labnetwork@mtl.mit.edu</a>
<a class="moz-txt-link-freetext" href="https://www-mtl.mit.edu/mailman/listinfo.cgi/labnetwork">https://www-mtl.mit.edu/mailman/listinfo.cgi/labnetwork</a>
</pre>
</blockquote>
<br>
<pre class="moz-signature" cols="72">--
</pre>
</body>
</html>