[moved] Why forming gas contains nitrogen?

[alyast]

I know that forming gas anneal leads to passivation of dangling bond on SiO2/Si interface. Forming gas contains 95% of nitrogen and 5% of hydrogen. Why not 100% of hydrogen. I heard that nitrogen is fairly intert but doesn't it will form oxynitride when in contact with silicon oxide at anneal temperatures?

 

[FvM]

doesn't it will form oxynitride when in contact with silicon oxide at anneal temperatures?

Unlikely.

A trivial reason not to use hydrogen might be that all possible mixtures with air should be non-incendive. So no safety measures are required.