Measurement of Thermally Induced Vibrations of Microelectronic Devices by Use of a Heterodyne Electronic Speckle Pattern Interferometry Imaging Technique

An imaging technique to measure modulated surface displacements on microelectronic devices is presented. A device is supplied by a sinusoidal current that creates a modulated variation of temperature. To measure the induced normal surface displacement, we use an electronic speckle pattern interferometry setup in which we introduce a secondary modulation using an electro-optic modulator. To extract the displacement information, we then analyze the term at the blinking frequency, which is equal to the difference between the frequency of the surface displacement and the frequency of the secondary modulation. As the photodetector is a visible CCD camera, we apply heterodyne detection by using a multichannel lock-in scheme. We have experimented with this new technique on a membrane to measure the amplitude of modulated surface displacement induced by the Joule effect.