Specific Process Knowledge/Characterization/Optical characterization

Ellipsometer

Ellipsometer: positioned in cleanroom 2

Filmtek 4000

FilmTek 4000: positioned in cleanroom 2

FilmTek 4000 is a computerized film thickness measurement and material characterization system. This system combines fiber-optic spectrophotometry with advanced material modeling software to provide an affordable and reliable tool for the simultaneous measurement of film thickness, index of refraction, and extinction coefficient

Normal incidence and polarized 70 degree reflection data is collected and used to calculate thickness and index of refraction of the measured film using SCI’s patented Differential Power Spectral Density (DPSD) technique. Absolute reflection data is obtained by comparing sample data to the measured reflection of a known reference sample, typically a silicon wafer with a thermally grown thin oxide (~63 nm) film.

The spectrophotometer scans the sample over a predefined range of wavelengths. The software generates a reflection spectrum based on a previously stored reference scan, and then performs a regression on the unknown parameters to fit the simulated reflection and power spectral density to the observed values. The resulting thin film parameters along with the measured and modeled spectra are then displayed for the user to examine.

A rough overview of the performance of the FilmTek

Purpose	Film thickness measurements and optical characterization of optically transparent thin films	Measurement of (multi layer) film thickness (only one unknown layer) Optical constants Surface roughness
Performance	Thin film materials that can be measured	Any film that is transparent to the light in the given wavelength range ex: Silicon Oxide Silicon nitride PolySilicon Photoresists SU8 Other polymers Very thin layers of metals (<20 nm) and many more
.	Film thickness range	<100 Å to 250 µm (depending of the material)
Process parameter range	Wavelength range	400-1000 nm
Substrates	Batch size	One sample at a time - all sample larger than 5x5 mm2sizes up to 6"
.	Substrate material allowed	In principle all materials Only pure silicon, silicon oxides, silicon nitrides and quartz may be in direct contact with the surface of the stage. If you have metals, III-V materials or polymers on the back side of the substrate the please mount your sample on a silicon carrier wafer.

Prism Coupler

Prism coupler: positioned in cleanroom 2

Comparison of the three methods

See here: Film thickness and optical constants of optical transparent films