Imaging and detection of current conduction in dielectric films by emission microscopy

Current conduction in dielectric films has been studied by Emission Microscopy. By combining optical microscopy with the latest night vision technology and the computer image processing techniques, we have been able to image the extremely faint light emission accompanying current conduction in a dielectric film on silicon substrate. We have found that current flows uniformly in an undamaged capacitor initially. The capacitor then breaks down after conducting a certain amount of charge and current flow becomes constricted into the failure location. To date, we have achieved a sensitivity of 10pA/µm
²
uniform current conduction through a 250Å undamaged oxide. For a damaged oxide, our sensitivity is 50nA at 12V or 300nA at 5V, strongly depending on the degree of damage. The spatial resolution achieved is 0.5µm. With its unprecedented capability, Emission Microscopy can be readily used to study the physical mechanisms of dielectric conduction and pinpoint the location of gate dielectric failure.