Heterogeneous Optical Assembly for High-Resolution Infrared Sensing
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Solution Overview
Problem
Conventional silicon-based infrared sensors have low quantum efficiency for sensing infrared light with wavelengths longer than 1 μm, and integrating non-silicon based infrared sensors with silicon-based read/processor circuits is challenging due to differences in material properties and integration complexities.
Innovation Solution
A heterogeneously substrate-bonded optical assembly is manufactured using a non-silicon wafer for infrared sensors and a silicon wafer for read-processing circuits, bonded together with a molding compound, allowing for high-resolution and low-cost long-wavelength infrared light sensing through wafer-level manufacturing processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If non-silicon based infrared sensors are used to sense long-wavelength infrared light, then quantum efficiency is improved, but integration with silicon-based read/processor circuits becomes difficult
Solution Approach 1:
The system is divided into separate functional modules: non-silicon infrared sensor pixels on one substrate and silicon read/processor circuits on another substrate. This segmentation allows each module to be optimized independently for its specific function while maintaining high quantum efficiency for long-wavelength infrared detection and enabling complex circuit integration separately before final assembly.
Solution Approach 2:
A bonding substrate serves as an intermediary component between the non-silicon infrared sensor array and the silicon-based read/processor circuits. This intermediate layer facilitates the heterogeneous integration of dissimilar materials, enabling electrical and mechanical connection between the two different semiconductor technologies while managing thermal and structural compatibility.
2Ease of manufacture
If conventional wire bonding is used to connect pixel array chip with reader circuit chip, then manufacturing process is simple, but integration density is low and high-resolution arrays cannot be achieved
Solution Approach 1:
The connection architecture transitions from two-dimensional wire bonding on the surface to three-dimensional vertical integration through bonded substrates. Multiple connection points are established in the vertical dimension through the bonding substrate, enabling high-density interconnections that support high-resolution pixel arrays while maintaining manufacturability through standardized bonding processes.
3Device complexity
If silicon-based materials are used for infrared sensors, then read/processor circuits can be easily integrated, but quantum efficiency for long-wavelength infrared light is low
Solution Approach 1:
Different substrate materials are used for different functional regions: non-silicon materials (such as InGaAs) are used specifically for the infrared sensor pixels where high quantum efficiency for long-wavelength detection is critical, while silicon materials are used for the read/processor circuits where mature fabrication processes and high integration density are advantageous. This local optimization allows each region to perform its specific function with maximum efficiency.
Data Source
AI summary
A heterogeneously substrate-bonded optical assembly includes a processor chip, an optical chip and a molding compound layer. The processor chip includes: a processor circuit; reader circuits electrically connected to the processor circuit; a first protection layer disposed on the processor circuit and the reader circuits; and first vias penetrating through first protection layer and being electrically connected to the reader circuit. The optical chip includes: a second protection layer bonded to the first protection layer; second vias penetrating through the second protection layer and being bonded to the first vias; and optical pixels electrically connected to the reader circuit respectively through the second vias and the first vias. The molding compound layer surrounds the optical chip and is disposed on the first protection layer. A method of manufacturing the optical assembly applicable to high-resolution applications is also disclosed.