CrossLab Name: Cleanroom Ellipsometer
FIC: Shared
Owner: Dan Hosler
Location: Cleanroom - P Bay
Maximum Wafer Size: 6"/150 mm

Overview

General Description

The cleanroom Ellipsometer can measure the thickness and refractive index of thin films on reflective substrates, as well as the optical properties of bare substrates.

Specifications

The stage can handle up to a 6 inch wafer diameter
Light source: HeNe laser, 632.8 nm, 1 mW output.
Incidence angles: 70° (default), 50°, 30°.
Maximum sample thickness: 1/2 inch.
Maximum sample diameter: 5 inch.
Film thickness range: 0-60,000 Angstroms.
Accuracy: ±3 Angstroms (manufacturer claimed over most of measurement range)
Repeatability: ±1 Angstrom (manufacturer claimed over most of measurement range)
Spot size is approximately 1mm by 3mm
Your substrate must be polished and must not rough to defract the laser

Technology Overview

Ellipsometry measures the thickness of an optically transparent film based on a change in polarization of an incident laser. This change is compared to a model, and values for thickness and refractive index are calculated. The values PSI (psi, Ψ) and DEL (delta, Δ).

The software uses the following abbreviations:

d: Thickness of film being measured
Nf: Real value of refractive index for film being measured
Kf: Imaginary value of refractive index for film being measured
ω (OMEGA): Thickness period; used for determination of thick film thickness
Ns: Real value of refractive index for substrate
Ks: Imaginary value of refractive index for substrate
Φ (PHI): Angle of incidence
ψ (PSI): Amplitude ratio as determined by measurement
Δ (DELTA): Phase difference as determined by measurement
λ (LAMBDA): Wavelength of incident light; fixed at 632.8 nm for HeNe laser

Sample Requirements and Preparation

Backside must be free of contaminants that may transfer to the stage. The area of measurement should be clean to be measured properly.

Standard Operating Procedure

Questions & Troubleshooting