[Fwd: HBr usage in clean room]

Mary Tang mtang at snf.stanford.edu
Tue Jan 11 14:30:15 PST 2005


Hi all --

I think we could possibly manage it, if we required that the bench be 
used exclusively by Zhigang (i.e., reserved the whole bench) -- this is 
pretty commonly done by the GaAs folk at the wbgaas bench. That way, we 
can be pretty sure that there would be little risk of exposure to other 
strong corrosives.

I think I'm a little wary about storage. Although I know we are in 
compliance and it is considered to be OK to store something like HBr in 
the same area as strong corrosives, provided everything is capped and 
stored in isolated containment areas, I guess I'm concerned about 
vapors. We do have other things that probably pose similar, albeit low, 
risk (like gold etchant), but it's an unknown for me, so I'm wary.


Mary


Jim McVittie wrote:

> John,
>
> As I recall, the previous request was for using Br not HBr. HBr is a 
> bit better than Br but I agree there is concern in using it in a 
> common wet bench. Br has a exposure limit of 0.1 ppm while the limit 
> for HBr is 3 ppm and for HCl is 5 ppm.
>
> Jim
>
> John Shott wrote:
>
>> Mary et al:
>>
>> I'm sorry to be contributing to this discussion so late ... I think 
>> that I must have missed this when I was in Denver.
>>
>> However, if I'm not mistaken, at one point we had NOT allowed HBr in 
>> the lab based on the fact that it would have to be used at wbgen and 
>> that it's got serious chemical reactivity problems ... if I remember 
>> correctly, it's exceedingly reactive with nitric acid and we didn't 
>> feel that we had the controls in place to insure that nitric and HBr 
>> wouldn't be in and around the wet bench at the same time.
>>
>> My memory may be bad on this subject ... Jim or Mike may have better 
>> recall than I .... but I think that an argument can be made that use 
>> of HBr in a shared laboratory environment may not be a great idea.
>>
>> I apologize again for not jumping in before now .... I must have 
>> missed this either when I was trying to read email over a slow modem 
>> from Denver last week or when I was wading through the large volume 
>> of e-mail in my mailbox upon my return.
>>
>> Comments from other members?
>>
>> Thanks,
>>
>> John
>>
>> Mary Tang wrote:
>>
>>> Hi all --
>>>
>>> Zhigang stopped by and asked about the status of this request. It 
>>> looks fine to me, so with Mahnaz' OK, I've approved it. Zhigang will 
>>> collect waste locally and label appropriately. As he plans to use 
>>> this chemical frequently, the chemical will be stored in the 
>>> original container, labeled with his contact info, in the chemical 
>>> passthrough area for personal chemicals (there is room there.)
>>>
>>> Mary
>>>
>>> -------- Original Message --------
>>> Subject: HBr usage in clean room
>>> Date: Thu, 06 Jan 2005 18:02:01 -0800
>>> From: Zhigang Xie <zxie at stanfordalumni.org>
>>> To: <specmat at snf.stanford.edu>
>>>
>>> Dear committee,
>>>
>>> As a formal new material request, I put three file related to 
>>> Hydrogen Bromide
>>> (HBr)here: MSDS pdf file,
>>> text file for filling the form,
>>> word file to describe the process I will use. I plan to use this 
>>> chemical frequently, so a storage place inside clean room
>>> is ideal.
>>> Thanks,
>>> Zhigang Xie (coral ID: zxie)
>>>
>>> ____________________________________________________________________
>>>
>>>
>>>------------------------------------------------------------------------
>>>
>>>1. Requestor name: Zhigang Xie
>>> 
>>>2. Phone number: (650)7238040
>>>
>>>3. email address: zxie at stanford.edu
>>> 
>>>4. Requestor’s PI (Advisor) or Company: 
>>>
>>>J. S. Harris and G. S. Solomon.
>>> 
>>>5. The name of the new Chemical (give all names commonly used): 
>>>
>>>hydrobromic acid (HBr)
>>> 
>>>6. If there are secondary new chemicals that must be used with this material, such as a developer for a new resist, list each of them here and supply MSDSs for each of them. 
>>>
>>>N/A
>>>
>>>7. Name of vendor/manufacturer that you are planning to obtain this material from: 
>>>
>>>VWR international
>>>
>>>8. URL for vendor’s website where info on the proposed chemical can be found: 
>>>
>>>www.vwr.com
>>>
>>>9. Vendor’s address and phone number: 
>>>
>>>San Francisco Regional Distribution Center 
>>>3745 Bayshore Blvd. 
>>>Brisbane, CA 94005 
>>>Orders: 1-800-932-5000 
>>>Web Orders: www.vwr.com 
>>>Phone: (415) 468-7150 
>>>Fax: (415) 468-1105
>>>
>>>
>>>10. What is your reason for wanting to bring this material into the lab: 
>>>
>>>For etching of GaAs and AlGaAs with enough smoothness and roundness for optical device fabrication.  
>>>
>>>11. Make a strong case why you can not use an already approved chemical/material for this purpose: 
>>>
>>>HBr is the standard chemical for making my devices according to publications. Try to find alternative, but it is impossible. 
>>>(Note that all previously approved chemicals are listed in the MSDS Index binder located in the receiving area. Also see SNF Index of MSDS Sheets.)
>>>
>>>12. List all the lab equipment and wet benches that you propose to use with this chemical: 
>>>
>>>Only GaAs wet bench. 
>>>
>>>13. Proposed quantity of the chemical that you want to bring into lab (give both raw and mixed quantities): 
>>>
>>>the order for VWR is one bottle (500ml)
>>>
>>>14. State the form that the proposed chemical is in. (Is it solid, powder or liquid? Note: as a general rule, powders are not permitted in the cleanroom.): 
>>>
>>>It is liquied (acid)
>>>
>>>15. State whether the chemical needed to be mixed to use it: 
>>>
>>>It need to mix with H2O2 (peroxide) in very diluted solution.
>>>
>>>16. From manufacturer, vendor or the Stanford safety site, obtain a legible Material Safety Data Sheet (MSDS) for all the proposed chemicals. Send these to the person listed below. 
>>>
>>>Please see the attached PDF file. 
>>>
>>>17. If 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. 
>>>
>>>It will not be used in "clean" equipment.
>>>
>>>18. 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. 
>>>
>>>19. Determine whether there is enough room to store your material in the designed lab storage areas. 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. 
>>>
>>>As an inorganic Acid, it should be in storage group F. 
>>>
>>>20. In your discussions with vendors, try to determine the best way to dispose of your spent chemicals and by-products. The lab has acid/base, HF and solvent drains. The acid/base drains go to a neutralization system before going the city waste water system. The city of Palo Alto has tight limits on the amount of heavy metals that be disposed of through the waste water system. If your chemical contains any metals, there is a good chance that you will have to collect all your waste and dispose of it in labeled containers which are picked up the Health and Safety Department. The HF drains go to a central tank which is pumped out by a HF disposal service at considerable expense on a regular basis. The solvent drains in the solvent benches are collected under the benches and disposed of by Heath and Safety as needed.
>>>
>>>I intend to keep the spent chemical and by-products in a plastic bottle for EH&S to pick up. (After discussions with vendors, it seems OK to get aspirated, but it wait for the committee to approve.)  
>>> 
>>>21. Put together a detailed process flow description on how you proposed to use this chemical. This should include: Any chemical mixing, all lab equipment and wet benched to be used, all containers to be used, where chemical is to be stored and how chemical and by-products are to be deposed of. This should be in a Word file attached to your e-mail request. In reviewing your procedure, we will be most interested in how the safety and contamination issues are to be dealt with. 
>>>
>>>See the attached word file.
>>>


-- 
Mary X. Tang, Ph.D.
Stanford Nanofabrication Facility
CIS Room 136, Mail Code 4070
Stanford, CA  94305
(650)723-9980
mtang at stanford.edu
http://snf.stanford.edu




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