Chip-Scale Sonic Communication Using AlN Transducers

On-chip wired interconnects presents a bottleneck for VLSI integrated circuits. An additional channel with which to communicate information would be beneficial to supplement traditional wired designs. Utilizing virtual, reconfigurable ultrasonic interconnects operating at high bit rate could open new vistas for computer architecture and low power computing. The first step to this goal has been demonstrated in this paper by using ultrasonic pulses to communicate between two aluminum nitride thin film transducers on a silicon wafer representative of a VLSI substrate. Direct output voltages on receive pixels were on the order of 40-60 mu V-pp for a drive voltage on transmit pixels of 0.5 V-pp at 900 MHz. An FEA model was used to verify the time-of-flight and signal amplitudes to demonstrate that the primary mechanism is bulk acoustic waves travelling through the silicon substrate.