Stacked Photoelectric Conversion Device Substrate Layout
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Solution Overview
Problem
The existing solid-state imaging devices with stacked substrates face challenges in suppressing characteristic variation among pixels due to complex connections and high process requirements, which complicates the manufacturing process.
Innovation Solution
A photoelectric conversion device is designed with a first substrate containing a pixel array and a second substrate with a readout circuit, where the AD conversion circuit and parallel-serial conversion circuit are strategically arranged to facilitate signal processing, allowing for partial overlap and simplifying the structure, thereby reducing characteristic variation among pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If elements are connected between two substrates to increase pixel count or photoelectric conversion unit size, then the number of pixels or size increases, but characteristic variation among pixels increases and process complexity increases
Solution Approach 1:
The patent transitions from a planar arrangement to a three-dimensional stacked substrate configuration. By arranging pixel arrays and readout circuits on separate substrates that are bonded together, the invention increases the photoelectric conversion unit size while keeping connection paths short (vertical bonds rather than long lateral connections), thereby reducing characteristic variation among pixels.
Solution Approach 2:
The invention divides the photoelectric conversion device into functionally separate substrates: one substrate contains pixel arrays while another contains readout circuits. This segmentation allows each substrate to be optimized independently and reduces the complexity of interconnections by minimizing the number of elements that need to be connected between substrates.
2Area of moving object
If elements are connected between two substrates to increase pixel count or photoelectric conversion unit size, then the number of pixels or size increases, but device complexity increases
Solution Approach 1:
By utilizing the third dimension through stacked substrates, the invention accommodates more functional elements without increasing lateral complexity. The vertical stacking allows pixel arrays and readout circuits to be positioned on different planes, simplifying the overall structural arrangement compared to trying to fit all elements on a single planar substrate.
Solution Approach 2:
Segmenting the device into multiple substrates with distinct functions reduces the complexity of interconnections. Each substrate can be designed and manufactured independently with fewer inter-element connections, and the bonding interface between substrates requires minimal connection structures compared to a monolithic design.
Data Source
AI summary
A device has stacked first and second substrates. The first substrate includes pixel array having pixels arranged along surface, the second substrate includes readout circuit having first AD-conversion circuit for generating first digital signals corresponding to first signals from the pixels, first parallel-serial conversion circuit for outputting first serial signal by performing parallel-serial conversion on the first digital signals, and processing circuit for processing the first serial signal. In orthogonal projection to the surface, part of the pixel array and part of the processing circuit overlap with each other. The first AD-conversion circuit is arranged between edge of the second substrate and the processing circuit. The first parallel-serial conversion circuit is arranged between the first AD-conversion circuit and the processing circuit.