Micro-transfer printing for heterogeneous PICs
Belgian group develops versatile, widely applicable micro-transfer printing technology
A group of researchers from the University of Ghent in Belgium has developed a new integration approach for heterogeneous silicon photonic integrated circuits (PICs). They say their micro-transfer printing (μTP) approach combines the high throughput advantages of die-to-wafer bonding with those of flip-chip integration.
The researchers describe the process rather like pressing a stamp down on paper. The stamp is 65 percent polydimethylsiloxane (PDMS), a transparent material, which is used to transfer the components into a substrate with 1 μm lateral alignment tolerance.
Transfer printing is used because is easier and cheaper to make III-V devices on a native substrate. The Belgian researchers also use III-V materials for their waveguides. Ultimately though, all these parts must go onto a silicon substrate.
The transfer technology is said to be very versatile. Other demonstrations of μTP are underway, specifically: InAs/GaAs quantum dot lasers, Ce:YIG magneto-optic materials for optical isolators, periodically poled LiNbO3 for nonlinear optics, BiCMOS electronics. Scaling up the technology to 200 mm and 300 mm wafers is underway.
The researchers say they are continuously improving device performance (e.g., laserwall plug efficiency) and studying yield and reliability. However, there is still a way to go for this technology to be used as a manufacturing technology.
Reference
'Micro-Transfer Printing for Heterogeneous Si Photonic Integrated Circuits' by G. Roelkens et al; IEEE Journal of Selected Topics in Quantum Electronics, vol. 29, no. 3: Photon. Elec. Co-Inte. and Adv. Trans. Print., pp. 1-14, May-June 2023
