Abstract: An apparatus and a method for providing fluid communication between a process chamber and a dry pump without contamination problem are disclosed. The apparatus utilizes a conduit that has at least one gate valve installed therein for opening or closing the conduit and a T-shaped cold trap to collect large size contaminating particles. The present invention apparatus is effective in preventing particle contamination to the process chamber by a siphoning or backsteam effect when a dry pump failure occurs. While the present invention apparatus and method may be used in any deposition process which produces reaction by-products, or contaminating particles, it is particularly suitable for use in a TEOS oxide deposition process.