Abstract: A high precision fluid pump for accurately delivering desired amounts of processing fluids, particularly for use in semiconductor processing and semiconductor processors. The fluid is dispensed by a piston driven by a stepper motor with precise electronic control. A rolling diaphragm isolates the stepper motor from the fluid, fumes or gas. To provide a clean environment for high purity applications, the pump is preferably made of PTFE and nitrogen purging is provided on both sides of the rolling diaphragm to reduce particle count and maintain the motor and controller temperature.