Thin CVD layers of carbon-doped silicon nitride on quartz glass
1989; Elsevier BV; Volume: 15; Issue: 2 Linguagem: Inglês
10.1016/0272-8842(89)90016-3
ISSN1873-3956
Autores Tópico(s)Aerogels and thermal insulation
ResumoAbstract The present paper gives the results of research on the formation of thin layers of Si3N4 doped with carbon in the course of their synthesis on quartz glass. Due to considerable differences in the thermal expansion coefficients of quartz glass and pyrolytic Si3N4, it is impossible to obtain uncracked layers of this material with thicknesses exceeding 0·6 μm. Introducing about 3% carbon into the Si3N4 layer in the course of the synthesis, makes the layer crack-free even at the thickness of 3 μm. Layers which are this thick do not undergo the strain corrosion that leads to crack formation in the thin Si3N4 layers on the quartz glass. A mechanism is proposed for this positive influence of carbon on the formation of thick and crack-free Si3N4 layers. A Gr/Re2 criterion was introduced which facilitates obtaining, with the chemical vapour deposition (CVD) method, layers uniform in thickness and properties, even for large supports, including those of irregular shape, as a result of the inhibition of the homogeneous nucleation. A method of calculating the thermodiffusion coefficients for a multi-component gas mixture is proposed.
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