Mahmoud Rasras

Non-uniform triggering of gg-nMOSt investigated by combined emission microscopy and transmission line pulsing

The triggering of grounded gate nMOSFET (gg-nMOS) and field-oxide devices (FOXFETs), essential for optimized ESD protection design, is addressed by TLP-pulsed emission microscopy. Current nonuniformity and instability effects in snapback operation under DC and TLP conditions are demonstrated. The comprehensive correlation of emission and electrical behaviour allows an improved interpretation of device operation. Technological influences on the trigger uniformity are discussed.

Spectroscopic identification of light emitted from defects in silicon devices

A comprehensive study of different fundamental aspects of light emission from defects in Si semiconductor devices is presented. Based on an experimental analysis, using a new highly sensitive spectroscopic photon emission microscope (SPEM) for continuous wavelength analysis (2.5 eV–1.2 eV), a unique assignment of the spectrum of the emitted light and the corresponding failure mechanism is established. Three distinguishable basic spectral categories were identified. They were attributed to gate oxide breakdown, metal shorts, and electro-static discharge caused junction spiking. The focused ion beam technique was used to look at the damage sites for confirmation of the SPEM results.

High-resolution stress and temperature measurements in semiconductor devices using micro-Raman spectroscopy

After a short introduction on the theory and instrumentation of Raman spectroscopy, its application for local stress and temperature measurements in semiconductor devices is discussed. Examples are given for silicon isolation structures, transistors, solder bumps and back-grinding. It is shown how the resolution can be improved by using an oil immersion objective and deconvolution techniques. Different imaging modes are discussed and their resolution is compared. Examples of 1D and of 2D scans are shown.

Spectroscopic photon emission microscopy: a unique tool for failure analysis of microelectronics devices

Abstract Photon emission microscopy (PEM) is a technique used commonly for failure analysis of microelectronics chips. This technique has it limitations: it can only be used to indicate the place of the failure. In most cases, this is not enough to allow a definition of the failure, i.e. to find out whether it is due to a gate oxide breakdown, a metal short, a junction spiking, etc. In this paper spectral PEM is discussed. It is shown that the spectrum of the light emitted by the failure may offer valuable information about the identity of the failure.

Origin of substrate hole current after gate oxide breakdown

The origin of the substrate hole currents after gate oxide breakdown in metal-oxide-semiconductor field-effect transistor (nMosFET) devices is investigated, using spectroscopic and conventional photon emission microscopy. Spectral analysis of light from the breakdown locations, under positive gate bias, indicates that hot electrons mediate the light emitted from the breakdown spots. These hot electrons are generated by the high electric fields at the location of the breakdown. Furthermore, light emission due to substrate hole recombination with electrons injected from the gate through the leakage path (breakdown location) dominates the light emission spectrum under negative gate bias. This finding is further verified using carrier separation measurements. In these measurements, minority carrier currents induced by the light emitted at the breakdown location and measured at a remote pn junction are compared with the substrate hole currents before and after oxide breakdown. These measurements prove that und...

A reliability study of titanium silicide lines using micro-Raman spectroscopy and emission microscopy

Micro-Raman spectroscopy and emission microscopy are used to study the crystallographic phase of 0.25 /spl mu/m wide TiSi/sub 2/ lines. It is shown that these techniques allow nondestructive mapping of the local phase of TiSi/sub 2/. The results show that there is a direct correlation between the resistance variation of these lines and the local occurrence of the high resistivity C49 phase of TiSi/sub 2/ in the lines.