Patent ID: 7521089
Filing Date: 2009-04-21
Classification: C23C,H01L,Y10S

Abstract:
1. A method of controlling the migration of reaction by-product gases from a chemical vapor deposition (CVD) process chamber contaminated with CVD reaction by-products to a transfer vacuum chamber through a gate valve interconnecting the chambers, the CVD process chamber selectively evacuated by a first vacuum pump and the transfer vacuum chamber selectively evacuated by a second vacuum pump, the method comprising: introducing a first flow of a purge gas from a first purge gas supply into the CVD process chamber, with the gate valve closed, sufficient to establish a first vacuum pressure; introducing a second flow of the purge gas from a second purge gas supply into the transfer vacuum chamber, with the gate valve closed, sufficient to establish a second vacuum pressure; discontinuing the first flow of the purge gas so that the vacuum pressure in the CVD process chamber falls to a third vacuum pressure less than the first vacuum pressure; isolating the second vacuum pump from the transfer vacuum chamber, while continuing to introduce the second flow of the purge gas to the transfer vacuum chamber, so that the vacuum pressure in the transfer vacuum chamber rises from the second vacuum pressure to a fourth vacuum pressure greater than the third vacuum pressure; and opening the gate valve to couple the transfer vacuum chamber and the CVD process chamber in fluid communication after performing the steps of discontinuing and isolating, the second flow of the purge gas directed into the CVD process chamber and the pressure differential between the third vacuum pressure and the fourth vacuum pressure being sufficiently low to reduce the migration of reaction by-product gases from the CVD process chamber to the transfer vacuum chamber induced by the opening of the gate valve.