What is the Value of Non-Invasive Leak Detection?
The common method of identifying leaks in a gas distribution system is, unfortunately, bad wafer product. Sometimes, the result of an atmospheric contamination can be seen visually, in the form of a hazy, dull surface finish (hazing) on the wafers caused by oxygen in an annealing or epitaxial process. Often, subtle contamination, such as uncontrolled thin oxide growth (<50 Angstroms) during a diffusion process, can go unnoticed because the effects are not detected until contaminated wafers reach a test step. By then, depending on the contamination and the process it affects, several production lots may need to be scrapped. The classic approach to checking gas distribution system integrity is by the detection of helium using a Mass Spectrometer. This is done to verify integrity after initial fabrication, and after a process failure to locate the leak. The procedure requires helium to be flooded into the piping branch to be checked. Then a high sensitivity mass spectrometer detector is u
