Stacked Imaging Sensor Via Structure for Further Miniaturization
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Solution Overview
Problem
There is a limit to downsizing and miniaturization of imaging devices with a three-dimensional structure.
Innovation Solution
An imaging device is designed with a first semiconductor substrate having a photoelectric conversion element and a second semiconductor substrate stacked with an interlayer insulating film, connected via a via that penetrates the film to electrically connect both substrates, and a pixel circuit on the second substrate reads out charges generated in the photoelectric conversion element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a three-dimensional stacked structure is adopted, then pixel density and integration are improved, but further downsizing is limited
Solution Approach 1:
The patent transitions from planar two-dimensional pixel arrangement to a three-dimensional stacked structure where sensor pixels and signal processing circuits are vertically integrated on separate substrates. This dimensional change enables higher pixel density while reducing the overall device footprint, effectively overcoming the downsizing limitation of conventional 2D structures.
Solution Approach 2:
The imaging device is divided into functionally independent substrates: a first substrate containing sensor pixels and a second substrate containing signal processing circuits. This segmentation allows each substrate to be optimized independently for its specific function while being integrated through via connections, enabling further miniaturization without compromising performance.
2Reliability
If conventional through-hole filling methods are used, then electrical connection is achieved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent changes the material parameter of the via filling from traditional metal conductors to polysilicon material. This parameter change simplifies the manufacturing process by eliminating complex metal deposition and planarization steps, while maintaining reliable electrical connection between substrates. The polysilicon can be deposited using standard semiconductor fabrication techniques already present in the manufacturing line.
Solution Approach 2:
The polysilicon filling serves multiple functions: it provides electrical conduction between substrates, acts as a mechanical filler to maintain via structure, and can be integrated with existing polysilicon-based circuit elements on the substrates. This multi-functionality reduces the need for separate processing steps and simplifies the overall manufacturing complexity.
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
This configuration enables further downsizing and miniaturization of the imaging device while maintaining functionality.
Implementation Method 1
a via that penetrates the interlayer insulating film and electrically connects a first surface of the first semiconductor substrate facing the second semiconductor substrate and at least a part of a second surface of the second semiconductor substrate facing the first surface
Implementation Method 2
a first semiconductor substrate provided with a photoelectric conversion element; a second semiconductor substrate stacked on the first semiconductor substrate with an interlayer insulating film interposed therebetween, the second semiconductor substrate being provided with a pixel circuit that reads out charges generated in the photoelectric conversion element
Data Source
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AI summary
Provided is an imaging device (1) including: a first semiconductor substrate (100) provided with a photoelectric conversion element, a second semiconductor substrate (200) stacked on the first semiconductor substrate with an interlayer insulating film (123) interposed therebetween and provided with a pixel circuit that reads out charges generated in the photoelectric conversion element as a pixel signal, and a via (600) that penetrates the interlayer insulating film and electrically connects a first surface of the first semiconductor substrate facing the second semiconductor substrate and at least a part of a second surface of the second semiconductor substrate facing the first surface.