Optical Reflectometry
Film thickness and structure analysis

ApplicationsMetrology by optical microscopy
Surface contamination analysis
Optical reflectometry

Optical reflectometry for film thickness uniformity analysis

The EFiT-TT reflectometry tool can render in 3D the film characteristics. From film thickness distribution of SiO2 on Si to complex film porosity on low-K materials, the EFiT tabletop tool provides a 3D analysis in the field of view of the microscope. Films on glass, PET, silicon wafers and other can be analyzed within different field of view sizes provided by the tool. To analyse porous film, the film thickness monitor can measure the mixture ratio (density) and film thickness separately if the target layer has sufficient film thickness. Thanks to modeling capabilities, film thickness resolution is under 1 nm and the density resolution is under 1%.

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Complex film structure (trench, holes) analysis by optical reflectometry

In the case of the following complex pattern, the film thickness of each layer and the etching depth can be obtained simultaneously from the reflection spectrum. This is also applicable to MEMS and trench structure. The modeling can also resolve multitasked layer structures of several films.

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Polysilicon crystallinity analysis by optical reflectometry

The EFiT-TT tool is sensitive to silicon crystallinity and can analyze stacks including polysilicon layer. To improve the electron mobility, annealing is used for improving the crystallinity of p – Si. Especially laser annealing can perform spot processing in a short time and has little influence on other parts.

Meanwhile, it’s important to measure to local effect of the annealing on the Si crystallinity. Since c-Si and a-Si have completely different crystallinity, their electrical and optical properties also differ which allow to determine, thanks to modelling p-Si as a mixture of a-Si and c-Si.

Evaluate the crystallinity of the p-Si film with this structure. The unknown parameters that will be determined are the crystallinity of the p-Si film, the film thickness of p-Si, and the film thickness of SiO2 above and below p-Si.