Semiconductor Inspection

There are a number of techniques that are utilised today in the post process on line optical inspection of semiconductor wafers. These include:

• Spectroscopic reflectometry where multiple laser wavelengths are shone down onto the surface of the thick film covered substrate to obtain information regarding the film thickness, density and purity
• Ellipsiometry, a similar technique but in this case information is gleaned by looking at the change in polarisation of the reflected light

Surface scattering techniques employing measurement of the Raman and Rayleigh scattered light from defects in the deposited structures.

A number of wavelengths are popular in these techniques, some in the infrared and others in the 532nm and 266nm regions. All require exceptionally good beam pointing and profile parameters to ensure the highest resolution and most accurate measurements are achieved.

However, there are many other economic parameters driving inspection instrument manufacturers in this field, not least the need to ensure minimal laser heat generation, long lifetimes, low real estate usage and low on going service and support costs.

The Verve^® and Symphony^® lasers from KLASTECH^® provide such compact solutions to instrument designers in this field.