Measure the thickness of the thin-film single-slice-capacitor

According to wave-absorbing materialpsilas electricity characteristic, this text created a kind of new high-performance, low-cost capacitance type absorbing-wave coatpsilas thickness measuring system. Carry out a research of thin film measurement which from nm-level to micron-level. According to the theory which capacitor working in electric field, it design a special single-piece capacitance sensor. This system can carry on a measurement to the thickness of thin film from nm-level to micron-level. Pass to adopt a kind of new capacitance signal to collect the framework type integration chip(Frame ASIC) CAV424 and shield measure and low price position RISC microcontroller, it carries out a method combine with the difference technique and three-signals-inspect technique. The system can automatically adjust null, correct and remove a great deal of errors. Because the microcontroller has inside place 10 position A/D conversion and driver of LCD, the CAV424 outputpsilas differential voltage signal can be directly with the ADC connection, link in the microcontroller, and the structure of system is very simple.