Making the invisible visible

Introduction

UNISERS is a process based on (i) physical coating of the test wafer and (ii) optical inspection. The UNISERS coating is necessary to improve the signal-to-noise ratio of the (particle) defects on wafers for total and inelastic (Raman) scattering. We use enhanced scattering to detect (particle) defects, estimate the true-size and location. Enhanced Raman scattering is used to acquire spectra of individual defects for chemical characterization.

Specifications for 300mm lab tool

Particle detection limit on unpatterned wafers with RMS roughness <1nm8nm
Wafer sizes and types1-inch – 12-inch bare silicon and other blanket wafers (W, Cu, TEOS, etc.)
Coating time30 – 60 mins / wafer
Dynamic range of detection8nm – 250nm
Scan speed for detection8nm mode: 20mins/cm2
25nm mode: 3mins/cm2
Particle speciation limit50nm
Particle speciation speed1 - 10s/defect
Optical resolution to differentiate two 20nm particles close to each other2 micron
Particle size estimationTrue size estimation (Material-independent)
Wafer handlingManual (Between two modules)
Scanning / signal processingAutomated & Customizable

Example results for UNISERS wafer inspection

Particle size distribution

Physical classification of particle defects

Chemical classification with UNISERS enhanced Raman spectroscopy (optional)