PEVCD generally does not produce Stoichometric Si3N4, but a variable
composition often denoted SixNyHz, or simply SiN.  When Texas Instruments
started using this stuff for IC passification in the mid '70, the corporate
buzz was "Sin is in".  Hydrogen content can be 20% or more.

If you use ammonia and silane in a ratio of ~6:1 at 380 degC in a PWS Coyote
you should get SiN with a refractive index of ~2.0, which is typical of Si3N4
produced by thermal LPCVD.  However this is a silicon rich material.  If you
use a higher ammonia to silane ratio you should be able to synthisize a
material with a Si to N ratio of 3:4, but the refractive index will probably
be low due to the hydrogen content.

You may have trouble with excessive stress and poor uniformity using 2% silane
in N2.  I would expect better results using pure silane and ammonia.  Yea its
dangerous stuff, maybe 10% would work.

>>> zanolli@fisica.uniba.it 02/08/02 10:32AM >>>
Hi,
I'm trying to have Si_3 N_4 using a PECVD sistem.
I have at my disposal SiH_4 (Silane) (2% of SiH_4 in N_2) and N_2 and
i'm looking for a recipe to get Si_3 N_4.
Can someone give me some suggestion about the power, the temperature and
the ratios of Silane and Nitrogen?
Thanks a lot,
Zeila

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