Failure Analysis using Optical Emission Spectroscopy
There are many dimensions to analyzing semiconductors and integrated circuits. Last week we looked at how one could peer into fine internal structures using high resolution x-ray analysis. Today we look at how to find tiny defects in the material based on failure analysis using optical emission spectroscopy.
There are a whole bunch techniques that fall under the bracket of emission spectroscopy, but all of them rely on one fundamental principle. Namely, that when atoms are excited, they release either photons or electrons (via the Auger effect) which are characteristic of their unique composition. An analysis of these emissions gives us valuable data regarding what sort of defects may be present.
Each technique is geared towards detecting a certain class of failures with varying degrees of sensitivity. In this article, we take a look at a few such failures and techniques for detecting them.
Types of Errors
Failure analysis using optical emission spectroscopy is used to identify many types of defects in integrated circuits. Some of these defects have to do with variations in the flow of current which can damage it. Electrostatic discharge is one example where this can happen.
Another problem which IC manufacturers run up against is that of leakage current. At the microscopic level, quantum effects manifest themselves and sometimes electrons manage to tunnel themselves through insulating layers! Indeed, this is one of the biggest roadblocks to greater miniaturization of integrated circuits.
Photon Emission Spectroscopy Techniques
There are a few relatively simple ways to employ light emission microscopy techniques which give us a detailed insight into the composition of the materials under observation. These are non invasive methods which don't damage the samples being studied and are therefore especially useful.
Auger electron spectroscopy for example, relies on the Auger effect where a stimulated electron in the process of releasing a photon knocks another electron out of its shell. Initially viewed as a nuisance effect, it has come into widespread use in the last 60 years ago as a surface analysis technique.
Deep level transient spectroscopy is another method that is unparalleled in its ability to detect minute defects in silicon - as low as 1 in 1012 parts. These defects show up as charge carrier traps which present obstacles to the smooth flow of electrons and cause all kinds of malfunctions.
There are many more advanced techniques and types of failures which Failure analysis using optical emission spectroscopy is designed to solve. Contact us to find out how we can help you analyse the failures in your ICs.