有的测量硅片厚度就是这个方法，国内和国外都有，一直不得其解。
大概利用的就是数脉冲的方式计算电容容值，但是就是这个硅片作为一级始终不明白。
The measurement technique follows directly from the formula for capacitance. The
capacitance of two parallel plates, separated by air, is directly proportional to the area of the
plates and inversely proportional to the distance between the plates. When measuring the
thickness of a silicon wafer, wafer acts as one plate of the capacitor, and a measurement
electrode, held a fixed distance above the bottom surface of the wafer, acts as the second
plate. Because the silicon in conductive, the thicker the wafer, the smaller the spacing
between the “lower” plate and the upper plate.
Semilab In-Line systems (WLT and WMT) measure thickness of wafers while moving on a
conveyor belt. In this case the wafer is not grounded, and the one-sided measurement won’t
work. Instead, Semilab uses a proprietary double-sided extension of the one-sided
measurement technique.
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