Process for preparing microporous layers of silicon nitride in quartz ampoules and apparatus for making the same
Abstract
In the present invention, there is disclosed a process for preparing microporous layers of silicon nitride in quartz ampoules wherein the invented process is characterized in that a quartz ampoule is put into a furnace at an initial laboratory temperature, is provided with a gas tight head. Then heating of the furnace is switched on and the quartz ampoules are heated to an operating temperature.
Further, it is filled with methane wherein methane pyrolysis takes place and the pyrolysis carbon deposits on the quartz ampoule wall and a carbon is let to react with the surface of the quartz ampoule. At the same time, an active layer of silicon, being just formed, is washed in ammonium flow.
A mixture of silane and hydrogen is introduced into the quartz ampoule during permanent flow of ammonium, wherein the mixture of silane and hydrogen is proportioned in a controlled manner through an inlet electromagnetic valve into a metering chamber. The flow of the silane and hydrogen mixture into the quartz ampoule is stopped and under the permanent flow of ammonia, the quartz ampoule is let to cool down in the switched off furnace to laboratory temperature.
Apparatus for making the above-described process of microporous layers of silicon nitride in quartz ampoules consists of a reaction section, a pumping section, a methane-introducing section, an ammonia-introducing section, and a silane and hydrogen mixing section comprised of a silane delivery subsection and a hydrogen delivery subsection.