This Small Business Innovation Research (SBIR) Phase I project explores a new approach to internal-node integrated circuit (IC) testing. An atomic force microscope (AFM) will be used as a non-contact voltage probe for testing high-speed ICs. It can be positioned and used to image the IC with nanometer accuracy. Furthermore, it has been demonstrated to measure signal frequencies up to 70 GHz. The probe works in air and can sense voltages through passivating dielectric layers. Small electrical forces are detected by using a flexible micro-mechanical cantilever and an atomically sharp, conductive tip. The tip hovers over the IC and stroboscopically samples the voltage waveform on the metal trace below it. With progressive scaling in chip linewidths, speed, and complexity, ICs are outstripping the capabilities of conventional systems to test them. Present technologies are lacking in measurement bandwidth, spatial resolution, and accuracy. Low-end probing solutions, such as contact probes, risk damage to the IC and perturbation of circuit operation. High-end solutions, such as electron-beam testers, have the disadvantages of great complexity and cost, low sequential throughput, and inflexibility. This new technology has potential for overcoming some current deficiencies and affording new solutions for accurate measurements in design verification and fault isolation in the IC design cycle.
