Impact of gas panel components on SDS(R) gas utilization

The efficient control and safe delivery of sub-atmospheric ion implant source gases requires specific design consideration demands on implanter hardware and software. The implanter delivery system hardware must have minimal pressure drop (maximum conductance) over the entire range of operating pressures to assure maximum utilization of the SDS source gas cylinder. Further, the critical mass flow controller component must have a dynamic range sufficient to produce repeatability over what is becoming an ever decreasing inlet pressure and lower flow rates specified by optimized recipes. Historically the focus for optimum cylinder utilization has been on the pressure drop of the flow controller. However many implanters were converted for SDS gas source operation without consideration for maximizing conductance in other components and optimum source utilization is not achieved. In this paper the characteristics of all the delivery system components such as MFCs, valves, tubing, filters, etc. and their impact on optimum source gas utilization are discussed. Pressure drop data for these individual components and for a series of integrated components over varying inlet pressures and gases is also considered.