The Automatic System Of Measurement The Refractive Index And Thickness Of Nano-Meter Material Thin Films

The Nano-meter Multi-bore Silica Thin Film(NMSTF) is a kind of new nano-meter material with super low dielectric constant and high factor of porosity, which is used mostly for micro-electronics purpose.. The refractive index of the NMSTF is highly related with the factor of porosity of the material. So the high accuracy measurement of the refractive index can tell the structure property as well as the judgment on the manufacturing technical of the material.The automatic system of measurement of the refractive index & thickness of NMSTF applies the reflection method to measure the parameters with the helium-neon laser as the incident light source. Firstly the incident light is polarized to single orient polarized light by a polarizer. This polarized light is divided into two beam of light, one for real time monitoring and the other for practical measuring. The light beam for real-time monitoring is received by the detector and then send directly to the data-collection card. While the light beam for measuring is reflected firstly by the sample surface and then send to the detector. The stepper motor device is used to change the incident angle freely and continuously. At last the property value of the material can be get after computer processing of the data.Through many tests on the sample material with the prototype, such conclusions can be drawn: firstly the measurement results on the NMSTF have high repeatability, secondly the data measuring accuracy error is limited to a certain small range, i.e. the measuring accuracy error of refractive index is less than 0.1 and the relative measuring error of the thickness is less than 3%. These conclusions suggest that the research work has attained its anticipant purpose and the device is qualified to be used practically.