APPARATUS AND METHOD FOR DELIVERY OF VAPOR TO A CVD CHAMBER

摘要

CVD reactor (11) is provided with precursor delivery system (12) having evaporation vessel (31) in which high molecular weight solid precursor is converted to vapor by heating it to vapor pressure of at least about 3 Torr. Vessel (31) is connected to CVD reactor chamber (11) through tube (50) of relatively large diameter having small diameter orifice (52). Controller (60) monitors pressure upstream and downstream of orifice (52) and controls flow control device in tube upstream of orifice (52) to produce desired flow rate of precursor vapor into CVD reactor (11). Flow rate is controlled in accordance with standard flow algorithm modified by factors retrieved from look-up flow calibration table in response to measurements of pressures across tube (50).