Sébastien Jorez

Imaging setup for temperature, topography, and surface displacement measurements of microelectronic devices

We present an imaging system that enables the extraction of three different types of information: First, the topography measurement of an electronic device at rest; then, two other informations are obtained when the same device is submitted to a transient current: on one hand, the induced surface displacement and on the other hand, the qualitative surface temperature variations field. The same bench includes two imaging techniques, one based upon interferometry, the other upon thermoreflectance, both of them using a light-emitting diode as a source of light. Results on a microheater are presented.

Laser probes for the thermal and thermomechanical characterisation of microelectronic devices

This paper presents a review of some of the recent works that we have done on thermal characterisation of running electronic devices by laser probing. Both the single point probing and the surface imaging methodologies are considered. Besides temperature mapping, laser point probing allows fault detection in integrated circuits. Electronic speckle pattern interferometry and shearography metholologies are presented, and examples of images of running power devices and this relation to the underlying thermomechanical stress are shown.

Optical method for the measurement of the thermomechanical behaviour of electronic devices

Abstract We present in this paper a laser probing method for the study of the surface deformation and thermomechanical behaviour of electronic components. The method has been applied to running power devices and creep analysis of solder joints in after-fabrication processes. The set-up allows following the whole surface deformation as a function of time even in the long-term range. The method is based upon electronic speckle pattern interferometry (ESPI) and allows measuring surface normal deformation with a 10nm resolution.

Surface displacement imaging by interferometry with a light emitting diode

We present an imaging technique to measure static surface displacements of electronic components. A device is supplied by a transient current that creates a variation of temperature, thus a surface displacement. To measure the latter, a setup that is based on a Michelson interferometer is used. To avoid the phenomenon of speckle and the drawbacks inherent to it, we use a light emitting diode as the light source for the interferometer. The detector is a visible CCD camera that analyzes the optical signal containing the information of surface displacement of the device. Combining images, we extract the amplitude of the surface displacement. Out-of-plane surface-displacement images of a thermoelectric device are presented.

Laser diode COFD analysis by thermoreflectance microscopy

We present thermoreflectance measurements upon a 980 nm wavelength laser diode. Using the energy conservation law, we are able to determine the temperature increase near the active region due to surface absorption. In this paper, we have studied the influence of this surface source contribution for three different configurations of the input current: below the threshold current ITh, for a moderate current above ITh and finally for a current far above ITh. We can analyse frome these reliability issues for the diode in terms of carastrophic optical facet damage (COFD)

Temperature variation mapping of a microelectromechanical system by thermoreflectance imaging

We present in this letter a cost effective noncontact imaging technique well adapted to measure the temperature variations on microelectromechanical systems. The setup is tested on a microheater constituted of a polysilicon resistor deposited on a dielectric membrane. Results concerning the temperature variations of this device are compared on one hand with simulation predictions, and on the other hand with thermoreflectance point measurements. From thermoreflectance images, we also estimate the values of the thermoreflectance coefficients of the polysilicon and of the dielectric.

Measurement of the thermomechanical strain of electronic devices by shearography

This paper deals with the optical measurement of strain in electronic power devices under normal operating conditions. This non-contact and non-invasive method called shearography is based upon speckle interferometry. The technique developed produces images of normal displacement gradient of devices. Numerical processing allows the determination of the surface displacement and its related strain. The main advantages of the measuring tool are to be a simple optical set-up, to be very robust with a good sensitivity and to measure directly strain. Therefore, his well suited to fit into an industrial environment

Laser diode light efficiency determination by thermoreflectance microscopy

In this paper, we present the thermoreflectance measurements done on 980 nm wavelength laser diodes. We determine the light output power for a given electric power input by using the energy conservation law.

Fault localisation in ICs by goniometric laser probing of thermal induced surface waves

Abstract New methods for fault detection in ICs are needed due to new technological trends. The detection of heat generated by faults offers interesting perspectives in this respect. Periodic heat released at the surface or inside ICs generates a surface thermal wave that can be detected by appropriate laser probing at distances up to 500 μm from the source. We propose in this paper a goniometric laser probing method allowing the determination of the direction and distance of a fault with respect to the probing point.

Study of the thermal behaviour of PN thermoelectric couples by laser probe interferometric measurement

The purpose of the present paper is to provide experimental data related to the temperature distribution within thermoelectric devices (TE). Moreover our aim is to get this knowledge for a dynamic temperature response of the device. We propose a non-contact optical measuring method, based upon very high-resolution interferometry, to map temperature effects upon the surface of running thermoelectric devices. The Peltier sources within the device generate thermal waves associated to heat transport. These waves interfere when AC current is driven through the device. The interferences are clearly observed in our measurements, showing how heat flows from different sources and merge. The measuring method can be used to check material properties which in turns allows to optimize contact design.