[labnetwork] Silicon Nitride question

[Philip Infante]

Hello Rick,

At the CNF we run a heated valve and fore line from the quartz tube up to an MKS/HPS water cooled trap. The trap condenses out the ammonium chloride byproduct from the process and is easily cleaned with water on a periodic maintenance interval. We also use HPS jacketed heaters self regulated at 150 C. This set up works great and we get minimal deposit between the trap and dry pump. We use an Ebara dry pump running at a 125 C case temp and heat the pump outlet line up to an Edwards Gas Reactor Column before it hits the pump exhaust main.

The majority of the work here is silicon rich/low stress nitride - which uses higher dichlorosilane flows.

Unreacted dichlorosilane is a bigger concern than the hydrogen byproduct. Scrubbing the pump outlet is important and we have learned from "real world experience" that even at very low dilutions (<1% SICl2H2) you can get a flammable/explosive deposits built up in the pump exhaust over time. I have attached a paper that describes this deposit build up associated with dichlorosilane based processes. Since installing the scrubber we have not had any issues with deposits building up.

I am not sure of what effect the platinum would have with the process gas.

Phil


Phil Infante
Cornell NanoScale Facility
Cornell University
250 Duffield Hall
Ithaca, NY 14853
607-254-4926

On Apr 11, 2012, at 8:08 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?

2nd 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


Rick Morrison
Senior Member Technical  Staff
Group Leader Microfabrication Operations
Draper Laboratory
555 Technology Square
Cambridge, MA  02139

W  617-258-3420
C   508-930-3461

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