| 摘要 |
PURPOSE:To make it possible to measure the thickness of each layer of sample constituting layers, by detecting a slight change in a sample absorbing current value based on the change in a layer to be etched, by performing phase detection using a lock in amplifier, wherein a modulating signal that modulates the potential of a sample is made to be a reference signal. CONSTITUTION:An ion beam IB is projected on a sample 4 comprising a plurality of layers 4a-4b through a condenser lens 2 and an objective lens 3. The output signal from a modulator 5, which generates a modulating voltage at a constant frequency f0, is applied on the sample 4 by a modulating transformer 6. In order to detect the ion beam current that is absorbed by the sample 4, the sample 4 is coupled to a preamplifier 7 by CR. The output signal of the amplifier 7 is supplied to a lock in amplifier 8, and its output is supplied to a recorder 9. A measuring person uses the data associated to a standard sample, and converts the data, which shows the etching time of each layer of the sample obtained from the recorder 9 into the data, which shows the thickness of each layer. Thus, the thickness of each layer of the sample can be measured. |
