Heterogeneously Integrated RF Circuits Using Highly Scaled off-the-Shelf GaN HEMT Chiplets

Abstract

Heterogeneous integration of IC chiplets into systems on a chip (SoC) is further revolutionizing the semiconductor industry. This letter introduces a metal embedded chiplet assembly for microwave integrated circuit (MECAMIC) technology that uses high-scaled GaN HEMT chiplets. MECAMIC relies on the cointegration of transistor chiplets with passive interposers using an embedding backside metal process. We report the development of standardized 40-nm AlGaN/GaN HEMT chiplets to rapidly prototype GaN circuits up to W-band by combining advances in e-beam gate processes and massively parallel singulation techniques. GaN chiplets with f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</sub> > 110 GHz and I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">max</sub> > 1.3 A/mm were fabricated in yielded quantities exceeding 50000 per 4" wafer. Simulation and experimental results of single-stage MECAMIC circuits with 4 μm × 37.5 μm device chiplets demonstrated 6.8-dB gain at 77 GHz. The MECAMIC technology not only optimizes the GaN wafer utilization but also provides the ability to incorporate other technologies, offering unique design flexibility at millimeter wave.