T UNCERTAINTY OF WHITE LIGHT INTERFEROMETRY ON ROUGHNESS SURFACE SiO2 WITH SURFACE PROFILE NT1100 Experiment Methods Mech 529 Research 4/30/2015
The technique of inspecting and measurement of the surface without touching the surface has been widely used in the semiconductor industry and research of the science field.The Optical profiler is one of the tool have been used to measurement of surface which use the methodology technique to measure the surface of the wafer without touching the surface using white laser light technology .In a decade, the engineers and scientists have been researching a new Metrology (methods) to measure with less possible uncertainties used white laser in optical profile.At the Washington State University Vancouver the student of electrical engineer major has the opportunity to do experiment using optical profile to measure the surface. The experiment condition in the clean room with Class-100 and nano electronic photonics device as the tool. The goal of this experiment to understand uncertainty of optical profile , we will provide a brief testing surface Silicon oxide (SiO2) .The measurement will determine the uncertainty of optical profile using the silicon oxidation without treatments as the sample surface to test . The process will test at one location on the surface with four of the tests to get the roughness of height of the spot 100x100 micro meter on a surface of SiO2. The deviation of the four tests height are 274.3 nm with comparison of the the operation manual optical profiler measurement is 160 nm with VSI. The data show the error height deviation on the surface and manual process error 40 percent.
Keyword: accuracy, optical critical dimension metrology, uncertainty analysis
Optical profile using the white light has been used a lot in the semiconductor industry to measure the surface and profile of the surface of wafer SiO2. However, during the focus on the lithography scaling of light of the equipment, the measurement surface of topography will increase the uncertainty of measurement and technology white light in increase will reach a maximum fundamental limit(Geerlings 2003). As the Operations manual show, the uncertainty of the equipment will be +-3 nm in vertical shift interference (VSI) with vertical range, and Phase Shift interference (PSI) is +- 10 angstroms with vertical range 160 nm [manual of Optical profile]. The uncertainty increase in measurement will affect a lot of the thin film development, electrical characteristic of device such as Capacitor, Resistor, inductor. Also, more importantly it will affect the dynamic mechanical flow in the surface[(Akter)]. The measurement surface will have a lot of impact in the device function. In this experiment, we will have the measurement four test with the same location and the same piece of silicon oxide. The silicon oxidation have not been clean and treatment with any chemical or physical process.Under Optical profile we can measure of the height of slop in the surface. THe standard deviation of the equipment comparison with the data height calculation the standard deviation height using excel statically.
Measurement surface have been around for a long time, however, using the electronics signal processing with high quality optical laser components such as lasers and focused lithography technology, it has became available for measurement and vision of the roughness surface about 20 years. Now a day, the equipment optical profile have been developed more complexity and more function to analysis roughness of surface.However The principle of the equipment is still the same as it has been developed. The system has developed with white laser as source light triangulation method with 3D surface methodology(Dorsch 1994) .In this experimental , we will discuss optical methodology device which is based on the variation principle. The system scan samples with the small uncertain and the testing can repeatable will small error .Before measurement the surface of roughness and the surface profile, we should understand the principle of the light and the principle of uncertainty of Plank’s constants and the interferometry light theory(Dorsch 1994). Wyko surface profile systems are the optical profilers to measures the surface height with accuracy in the nanometer. The system based on the interference fringes with fundamental is the best contract fringe occurs at the best focus. The system has been build the white laser light at the source, digitize intensity, detect array [figure 1].