Improvements to Fabrication of Single-Photon-Sensitive Silicon Avalanche Photodiodes
Silicon avalanche photodiode (APD) arrays play a crucial role in various scientific and technological applications. However, traditionally they were created using wafer-level 3D integration, which was time-consuming and cost-prohibitive, and presented challenges for integration with existing readout integrated circuits (ROICs). These challenges created significant delays and increased costs, limiting the wider adoption of this innovative technology. The main problem with the traditional wafer-level back-illumination process is the extensive processing time, making the prototyping of APD arrays slow and expensive. Furthermore, the mechanical support for the APD devices could not be efficiently provided, posing challenges for integrating fast microlenses directly on the APD back surface. Similarly, there were difficulties in producing APDs with low dark count rates and higher radiation tolerance, much required for functioning properly in harsh environments.
Technology Description
The developed chip-to-chip integration process radically innovates the prototyping method of silicon avalanche photodiode (APD) arrays. It considerably reduces the cost per development cycle, eliminating the need for a dedicated full-wafer readout integrated circuit (ROIC) fabrication. It also offers compatibility with ROICs made in previous fabrication runs, and accelerates schedules. The chips can be processed swiftly at the chip-level, from dicing to bump-bonding and thinning, contrasting the slower wafer-level back-illumination process. This technology stands out for its ability to provide mechanical support to the APD device via the CMOS substrate, enabling the integration of fast microlenses directly on the APD back surface. It yields APDs with lower dark count rates and higher radiation tolerance, suitable for harsh environments. Also, the process can be extended to create larger arrays of APDs.
Benefits
- Reduced cost per development cycle
- Fast prototyping process
- Compatibility with pre-existing ROICs
- Higher radiation tolerance
- Potential for large array APD development
Potential Use Cases
- Development of advanced imaging sensors for aerospace applications
- Enhancement of radiation detection and imaging in nuclear industry
- Creation of advanced sensor arrays for environmental monitoring
- Improvement of advanced security systems using high-quality imaging
- Development of cutting-edge medical imaging devices