| 摘要 |
A mechanism consisting of a method and apparatus (Fig. 1), for <I>in situ</I> calibration of a plasma processing system pressure sensor (8). Measurements from the sensor (8) are compared to those from a closely coupled, calibrated sensor (6), over a continuous pressure range obtained by flowing an appropriate gas into the plasma processing system (Fig.2) from a suitable, <I>in situ</I>, mass flow controller (10). The flow rate is low enough such that the actual pressure difference between the sensors (6, 8) is kept minimal. The calibration accuracy is enhanced by comparing measurements from the sensors at four static pressures obtained by allowing gas to move to and from an additional chamber of known volume (4). The apparatus can be isolated and disconnected from the plasma processing system and is kept at low pressure when not in use by means of an integral vacuum pump (3).
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