Multi-Die SPAD Line Arrays With Lens Overlap Across Die Gaps
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Solution Overview
Problem
Conventional image sensors suffer from limited functionality, including inability to determine object distance and lower-than-desired image quality and resolution, which is addressed by incorporating single-photon avalanche diodes (SPADs) for improved light sensitivity and depth sensing.
Innovation Solution
The implementation of SPADs in imaging systems, which detect incident photons through avalanche multiplication and utilize quenching circuitry to convert photon detection into measurable signals, allowing for photon counting and time-of-flight measurements for 3D imaging, and grouping multiple SPADs in silicon photomultipliers to enhance dynamic range and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If single-photon avalanche diodes (SPADs) are used to improve sensitivity to incident light, then single-photon detection capability is achieved, but reset time limitations reduce dynamic range in low light conditions
Solution Approach 1:
The invention divides a large array of SPADs into multiple smaller semiconductor dice, each containing a subset of the total SPADs. This segmentation allows multiple dice to be operated in parallel, effectively increasing the dynamic range by enabling more pixels to be active simultaneously without being constrained by the reset time of a single large array.
2Manufacturing precision
If high aspect ratio line arrays of SPADs are arranged to improve imaging capabilities, then image resolution is enhanced, but manufacturing challenges increase
Solution Approach 1:
Instead of manufacturing one large high aspect ratio silicon die with all SPADs, the invention segments the array into multiple smaller dice with lower aspect ratios. These smaller dice are easier to manufacture with standard fabrication processes, reduce stress and defect risks, and can be subsequently assembled into the complete high-resolution imaging array.
Solution Approach 2:
The invention transitions from a single-plane large array to a multi-die stacked or tiled configuration. By distributing SPADs across multiple semiconductor dice that can be arranged in two-dimensional patterns, the system achieves high effective resolution without requiring individual dice to have extreme aspect ratios.
3Ease of manufacture
If multiple semiconductor dice are used to reduce manufacturing challenges, then ease of manufacture is improved, but device complexity increases
Solution Approach 1:
Multiple semiconductor dice are merged into a single functional imaging package with unified control and readout. The dice are electrically connected and controlled as one integrated device, allowing the system to benefit from easier manufacturing of individual dice while presenting a simplified interface and control architecture to the user system.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
SPADs enable effective low-light imaging and depth sensing, improving image quality and resolution by accurately measuring incident light and determining object distance, while silicon photomultipliers increase dynamic range and photon detection efficiency.
Implementation Method 1
single-photon avalanche diodes (SPADs) may be capable of single-photon detection
Implementation Method 2
mitigated by lenses to focus light over gaps
Implementation Method 3
single-photon avalanche diodes (SPADs)
Data Source
AI summary
A semiconductor package may include a line array of single-photon avalanche diodes (SPADs). The line array of single-photon avalanche diodes may be split between multiple silicon dice. Each silicon die may be overlapped by at least one lens to focus light away from gaps between the dice and towards the single-photon avalanche diodes. There may be one single-photon avalanche diode for each silicon die or multiple single-photon avalanche diodes for each silicon die. When there are multiple single-photon avalanche diodes for each silicon die, lenses may be formed over only the edge single-photon avalanche diodes.