Can a Manufacturing Method Improve Silicon Photonics Chips?

A manufacturing process could solve a key challenge in light-based chips, helping support AI, data centres, communication and computing.

Researchers from Ghent University–imec, Belgium, say a manufacturing technique called micro-transfer printing (MTP) could make it easier to build silicon photonics chips by combining different semiconductor materials on a single platform. The approach could help improve optical communication systems, AI hardware, data centres and computing systems that require faster data transfer.

Silicon photonics uses light instead of electrical signals to move data, offering higher bandwidth and lower latency than electrical interconnects. The technology is already used in telecommunications and data communications, but silicon cannot perform every function needed in photonic chips. For example, it cannot efficiently generate light, making it necessary to integrate materials such as III-V semiconductors and lithium niobate. However, these materials cannot be easily combined using standard CMOS semiconductor manufacturing processes.

The researchers propose micro-transfer printing as a way to overcome this limitation. In the process, thin-film devices, called coupons, are first fabricated on separate source wafers using the manufacturing process suited to each material. A soft elastomeric stamp then picks up these devices and transfers them onto a silicon photonics wafer, where they are permanently bonded.

This allows lasers, modulators and other photonic components made from different materials to be integrated onto the same silicon platform without changing existing CMOS-compatible manufacturing. It also enables chiplets to be added while maintaining wafer-scale production.

The team has already demonstrated the approach in several photonic systems. These include silicon photonic engines using indium phosphide lasers for optical and microwave signal processing, gallium arsenide lasers integrated with silicon nitride waveguides, narrow-linewidth indium phosphide lasers for coherent communications and lidar, lithium niobate modulators combined with silicon nitride photonic circuits, and electronic-photonic optical receiver platforms.

According to the researchers, the technique could support future photonic systems for communications, sensing, quantum technologies and high-performance computing. Before it can be widely adopted, however, challenges such as manufacturing yield, long-term reliability, production throughput and the development of a supporting manufacturing ecosystem still need to be addressed.

To help move the technology towards commercial production, the researchers are developing a pilot manufacturing line to evaluate micro-transfer printing under industrial manufacturing conditions. If successful, the approach could enable silicon photonics devices for computing and communication applications.