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In Situ Determination of Growth Rate and Stoichiometry in a Heterogeneous CVD Reactor

IP.com Disclosure Number: IPCOM000039040D
Original Publication Date: 1987-Apr-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Bartha, J: AUTHOR [+3]

Abstract

The growth rate of layers in a heterogeneous chemical vapor deposition (CVD) reactor is determined from the concentration decrease of reactants in the outlet gas as measured in a mass spectrometer. In a heterogeneous CVD reaction, layers are deposited only on selected surfaces of known size; if, for instance, an Si-layer is to be grown on wafers by pyrolysis of silane (SiH4/gas T Si/solid + 2H2/gas), the silane can be supplied to the reactor along with a large quantity of He as a carrier gas which is not affected by the reaction.

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In Situ Determination of Growth Rate and Stoichiometry in a Heterogeneous CVD Reactor

The growth rate of layers in a heterogeneous chemical vapor deposition (CVD) reactor is determined from the concentration decrease of reactants in the outlet gas as measured in a mass spectrometer. In a heterogeneous CVD reaction, layers are deposited only on selected surfaces of known size; if, for instance, an Si-layer is to be grown on wafers by pyrolysis of silane (SiH4/gas T Si/solid + 2H2/gas), the silane can be supplied to the reactor along with a large quantity of He as a carrier gas which is not affected by the reaction. The outlet of the reactor is provided with a small diaphragm (of, say, 20 mm) for continuously extracting a gas sample which is fed to a mass spectrometer for measuring the changing partial pressure of silane relative to the constant partial pressure of He (a calibration measurement is initially performed without any reaction taking place). The total reaction rate can thus be calculated from the reaction equation, yielding the deposition rate of the layers growing on the surface of known size. In CVD reactions with several reactants, measurement of the individual partial pressure in a mass spectrometer allows determining the stoichiometric composition of the layers. The relative and thus precise measurement with its high dynamic range (up to 103 being achievable in mass spectrometers) can be applied to all CVD reactions, if the diaphragm (or several dif...