Initial discussion on working with SNF for processing PbS

Ed Myers edmyers at
Wed Nov 7 11:26:29 PST 2007


Sorry for the delay in providing you with the final decision on your 
request.  Our aim is to support all of the processing needs of our 
lab members, however some are more challenging than 
others.  Unfortunately, yours is a challenging one.  I believe we are 
OK with the spin casting, outside of using Chloroform.  The other 
listed solvents we can devise a protocol for safe handling of the materials.

The biggest concern is the etching of PbS.  Our MRC system is a 
diffusion pumped system and we have to be conscience of what elements 
that can be picked up in the oil.  This is a safety issue for staff 
who will be servicing the tool.  The protocol for etching of the PbS 
needs to be established.  This will include how to do routine service 
the tool and how to minimize any Pb deposition on the tool during 
processing.  This will take a longer to resolve and require help from 
whoever is doing your processing.

The proposed process outline is too vague to accept in full.  It will 
be important to work with the SNF staff as you continue to refine 
your process.  For example lead has a tendency to volatilize, so 
thermal processing will need to be addressed, including your 
encapsulation step.

Ed Myers

At 12:25 PM 10/12/2007, Rick Clayton wrote:
>My name is Rick Clayton, and I am VP of Advanced Materials for 
>InVisage Technologies, an early stage (still stealth mode) 
>technology company working on advanced electronics.
>We wish to do work within the SNF, and I want to start the process 
>of material approval prior to full engagement.
>Many of the detailed questions below are more applicable once we are 
>more familiar with your facility, but I will provide a top level 
>description here as a first step in the process of getting our 
>material approved.
>Core material: PbS
>associated other materials: Thiols (Mercaptans): Ethane Thiol, 
>Ethane DiThiol, Benzene Thiol (may include other thiols in the future)
>process chemicals: toluene, chloroform, acetonitrile, acetone, hexane
>Incoming material:
>The PbS would be in either powder or solution (toluene, chloroform, 
>hexane, or other non-polar solvent).
>Typically we would use about 50-100 ml of our material per day.
>a rough process flow:
>Our device involves spinning films of PbS onto a substrate (usually 
>a Si wafer), doing some solution processing of the wafer with the 
>thiols, depositing masking materials, etching the PbS film, and then 
>depositing encapsulation materials.  Once the wafer is finished we 
>may either die saw or test at wafer level.
>We will be developing solvent systems and spin profiles to optimize our films.
>We will be developing masking and etch processes
>We will be developing encapsulation processes
>Please provide as much information as you can about your chemical or 
>material. It may very well be the first time anyone on the SpecMat 
>committee has heard of this chemical/material, so it will be your 
>responsibility to educate us. We also have a large archive of 
>chemicals and materials that have been approved, so we may also be 
>able to help you in selecting a chemical or process
>    * Your contact information: Name, Coral login, phone number, 
> email address and who you work for (your PI or company.)
>    * The chemical or material. Please provide all common names, 
> trade names, and CAS numbers where appropriate. Include an MSDS, if 
> available; or provide the reason, if not. Make sure to include 
> information for any new secondary chemicals (such as a developer 
> for a new resist). Read the MSDSs as well as the 
> <>Stanford 
> Chemical Storage Groups and the 
> <>Stanford 
> Chemical Safety Data Base sections on this website to determine the 
> <>Storage Group 
> Identifier and 
> <>Main Hazard 
> Class of your chemical/material.
>    * Vendor/manufacturer info: address and phone number, website URL.
>    * Reason for request: Please give serious thought to this. If 
> you have any process information (application notes from the 
> vendor, protocol from another lab, experimental methods section of 
> an article), please include it, preferably as attachments. Ask 
> yourself these questions: Is this the latest procedure? Are there 
> newer/safer alternatives that will also work for my project? Will 
> any of the current SNF approved chemicals and materials work for me?
>    * Process Flow: Please provide a detailed process flow 
> description on how and where you proposed to use this chemical. 
> This should include all 
> <>Lab equipment 
> to be used for processing your wafers once your new chemical or 
> material has been used (even if your new material is a film that is 
> removed, it may still pose potential contamination concerns.) Make 
> sure to include wet benches. Please note that f the 
> chemical/material is to be used in any the 
> <>"clean" 
>   equipment, purity specifications will be needed. This is most 
> important for chemicals/material that are not normally used for 
> VLSI device fabrication. To be allowed into a 
> <>"clean" 
>   tool, the material should MOS grade or better.
>    * Amount and form. How much will you bring in? Is it solid, 
> <>powder or liquid? 
> (Note: as a general rule, 
> <>powders are not 
> permitted in the cleanroom.) Do you need to mix it to use it?
>    * Storage: Will you be storing your chemical/material at SNF? If 
> so, please note any potential reactivities (this should be on the 
> MSDS). <>Storage 
> groups A,B,D and L are stored in the yellow solvent cabinet in the 
> furnace support area, while 
> <>storage groups 
> C, E, F and G are stored on top of one of the Pass-through Carts. 
> Ensure your chemical container or material is 
> <>properly 
> labeled. If there is no available room, it must be stored by in the 
> bulk storage area. You will then need to obtain it from receiving 
> area personnel each time you want to use it and return it to them 
> when you are finished using it (or each time you leave the lab). 
> Note that there is no storage of chemicals/materials in the 
> processing lab or at any wet bench.
>    * DIsposal: How will you dispose of any waste or excess chemical 
> or material? In your discussions with experts and vendors, try to 
> determine the best way to dispose of your spent chemicals and 
> by-products. Please refer to the 
> <>SNF Labmembers 
> Safety Manual for the different methods of waste disposal that are 
> available in the lab.
>Please get in touch about next steps.
>Rick Clayton
>VP Advanced Materials
>InVisage Technologies
>mail: 101 College St., South Tower, Rm 312, Toronto, Ontario, Canada, M5G 1L7
>Office: 416 673 6520
>mobile: 613 291 6578
>email: <mailto:rick.clayton at>rick.clayton at
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