A solution for pressure variations in vacuum process tools due to pressure regulator fluctuations

We have observed plasma variations which were found to be due to gas pressure regulator fluctuations.1 The fluctuations in pressure may not be noticeable when operating in a normal process configuration since changes in flow, and hence pressure, are generally compensated for by an automatic downstream pressure controller. Although chamber pressure is maintained to ±0.5 mTorr of the pressure setpoint, other important parameters, i.e. plasma chemistry, may be out of control as we will further discuss. These effects can be apparent when, for example, attempting etch stops utilizing plasma emission.