Surface micromachining of uncooled infrared imaging array using anisotropic conductive film

Abstract

Micromachining processes have been extensively adapted in developing uncooled infrared imaging array. One of the most important sensing materials in the array is ferroelectric thin film. To integrate the ferroelectric thin film with the signal processing circuitry, an IC compatible process has to be applied. Various methods have been successfully used to prepare high quality oxide ferroelectric thin films. Unfortunately, not all of the methods are compatible with a standard CMOS process. None of them can optimize the ferroelectric thin film after it has been deposited onto IC chip due to high heat treatment temperature. A Flip-Chip Transfer (FCT) method is proposed here to optimize the ferroelectric thin film separately with the IC chip. Doing so, any necessary measure could be taken to optimize the performance of the ferroelectric thin film. After that, anisotropic conductive film (ACF) is applied between the ferroelectric thin film and the IC chip to establish interconnection and mechanical bonding between the sensing element and the signal processing circuit. Micromachining process is then applied to remove the substrate, usually Si, on which the sensing material is deposited. A 128x1 linear pyroelectric infrared imaging array is being fabricated.