[labnetwork] Silicon Nitride question

[John Shott]

Rick:

To add our practices at Stanford to the discussion ...

1. Our newer, higher quality system has heated line between tube and 
pump as well as an inline mesh filter before the pump.

2. Our older system actually only has a filter on the exhaust side of 
the pump.  That is primarily to help avoid buildup in the exhaust line.  
Our exhaust line is actually too small ... 1" OD ... so occlusion of the 
exhaust line can be a problem.

We have some form of abatement on each system .... in fact all of our 
LPCVD either runs to an old Innovative Engineering/Delatech CDO unit 
running at 800 C or to a Pure Air EDOC (Dynamic Oxidation Chamber) to 
treat exhaust gases. The output of either the CDO or EDOC then goes to 
our building-wide water scrubber .... that will remove the HCl and 
ammonia products from the nitride process.

Note: I believe that just about all nitride LPCVD processes will have 
significant fractions of unreacted DCS coming out the end of the tube.  
That is particularly true if you are running hgh DCS flows, which is 
often the case if you are trying to produce a silicon-rich, low-stress 
nitride film.  So, even though we don't use production volumes of gas, 
we still believe in abatement on all LPCVD tubes.

Good luck,

John


On 4/11/2012 5:08 AM, Morrison, Richard H., Jr. wrote:
>
> Hi Everyone,
>
> I am restarting a Silicon Nitride LPCVD process and I have a few 
> questions. The process will use a EBARA dry pump therefore should I 
> use a trap on the vacuum pump inlet to catch any particulate generated?
>
> Any issue with excess hydrogen from the process going into the dry 
> pump, do I need a burn box on the vacuum pump exhaust?
>
> 2^nd question has anybody tried to run the LPCVD process on a wafer 
> with a platinum metal pattern on the surface? I was wondering if there 
> maybe some adverse effect because of the catalytic nature of Platinum.
>
> Thanks
>
> Rick
>

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