3D accelerometer for measuring three components of inertial force vector with respect to an orthogonal coordinate system, which has high sensitivity due to a big proof mass located within a cavity beneath the surface of the sensor die. Then, the processor determines whether an access from the second program to a memory area used by the first program is permitted based on memory restriction information when the fault occurs while the first program and the second program are under execution, and changes the setting of the memory management unit so that the fault does not occur when the access to the memory area is permitted. The selected initial interpolation value can be the average of two calculated values of using values of two predetermined fractions associated with the two boundary points between which the quotient falls. The method is adapted to make the spacing between the upper and lower electrodes larger at least at the time of plasma extinction than during plasma processing of a wafer on the lower electrode.