Direct On-Chip 3-D Aerosol Jet Printing With High Reliability

We demonstrate a new, low-cost, additive aerosol jet (AJ) printing fabrication method for 3-D on-chip interconnects on III-V semiconductor chips. A dielectric layer and bridge-type gold interconnects were printed on a GaAs-based microwave monolithic integrated circuit (MMIC) to connect a gate pad and a ground pad of the MMIC. The MMICs with the printed 3-D interconnects show the same RF performance as those tested before printing with the gate voltage biased at 0 V. This indicates that the 3-D printed interconnects can provide effective and reliable connections. Extensive reliability tests including thermal shock, thermal cycle, and current stress tests were performed on the MMIC with the printed 3-D interconnects. No performance degradation was found after the reliability tests. The performance and reliability study demonstrates that the low-cost, additive 3-D AJ printing is an effective fabrication method for adding highly reliable on-wafer circuit functionalities and features. Additive printing is an excellent complementary technology to existing semiconductor technologies for instantaneous on-wafer circuit prototyping, repair, tuning, reconfiguration, and system on-chip integration with high reliability.