Embedded glass fan-out integration method for high-performance Ka-band RF microsystem

Area of Science:

• Materials Science
• Electrical Engineering
• Microsystems Engineering

Background:

• Monolithic integration faces limitations for next-generation communication networks requiring low signal loss and high frequencies.
• Glass interposers offer advantages like low dielectric loss, planarity, and tunable thermal expansion for millimeter-wave (mmWave) RF microsystems.

Purpose of the Study:

• To develop a high-density, low-noise RF integration technology using an embedded glass fan-out process.
• To address challenges in glass micromachining for precise die embedding.
• To demonstrate a heterogeneously integrated Ka-band transceiver for 5G-Advanced and 6G networks.

Main Methods:

• Utilized laser-induced deep etching (LIDE) for high-precision glass micromachining.
• Employed optimized chemical-mechanical polishing (CMP) to reduce redistribution layer (RDL) surface roughness by 97%.
• Designed and fabricated a Ka-band microsystem with a Chebyshev antenna array and Klopfenstein taper transition.

Main Results:

• Achieved transmission loss below 0.25 dB/mm.
• Fabricated a compact Ka-band microsystem with integrated low-noise amplifier and antenna.
• Demonstrated a heterogeneously integrated Ka-band transceiver with GaN amplifiers and Si switch, achieving 26.08 dB transmit gain and 2.73 dB noise figure at 28 GHz.

Conclusions:

• The developed embedded glass fan-out process offers a scalable and robust solution for heterogeneous integration.
• This technology enables high-performance, multi-functional mmWave microsystems for future communication standards like 5G-Advanced and 6G.
• The integration of diverse semiconductor technologies on glass interposers is crucial for advancing wireless communication.