Ion implantation device with a closed-loop process chamber pressure control system

摘要

An ion implantation device is presented having a closed-loop pressure control system to reduce pressure fluctuations within a process chamber during ion implantation. A pressure probe extends through a wall of the process chamber or a wall of a beam chamber in gaseous communication with the process chamber. A vacuum measurement unit, coupled to the pressure probe, is configured to produce an electrical pressure signal corresponding to the pressure sensed by the pressure probe. An interface electronics unit coupled to the vacuum measurement unit converts the electrical pressure signal into an electrical control signal for a flow control valve. The flow control valve is coupled to receive the electrical control signal and is configured to control a flow of an inert gas from an inert gas source to a gas inlet port in a wall of the process chamber. The inert gas may comprise argon, nitrogen, or any other gas inert to a wafer fabrication process. Fluctuations in the pressure within the process chamber are reduced by additions of appropriate amounts of inert gas when the pressure sensed by the vacuum measurement unit drops below a predetermined pressure threshold value.