Solid-State Imaging Device with Stacked Photoelectric Layers
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Solution Overview
Problem
The existing single-plate-type color solid-state imaging devices have low light use efficiency and sensitivity due to the absorption of incident light by color filters, leading to poor resolution and potential false colors, and the process of forming openings in electrode pads using photolithography can degrade the photoelectric conversion layer.
Innovation Solution
A manufacturing method for a solid-state imaging device with multiple photoelectric conversion layers laminated on a semiconductor substrate, where the first electrode is partitioned for each section, and the second electrode is common, with electrode pads exposed to prevent photolithography-induced degradation, using masks to cover non-photoelectric conversion regions during layer formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If photolithography technique is used to form openings in electrode pads, then electrode pads can be exposed for connection, but the photoelectric conversion layer performance is degraded due to heat or moisture exposure
Solution Approach 1:
The patent applies preliminary action by forming openings in the electrode pad layer before forming the photoelectric conversion layer. This allows the photoelectric conversion layer to be deposited over the exposed electrode pads without requiring subsequent photolithography steps that would expose the sensitive organic photoelectric conversion layer to heat and moisture, thus preventing performance degradation while maintaining ease of manufacture
Solution Approach 2:
The patent segments the manufacturing process into distinct stages: first forming openings in the electrode pad layer, then depositing the photoelectric conversion layer, and finally forming subsequent electrodes and insulating layers. This segmentation allows each layer to be formed under optimal conditions without exposing the sensitive photoelectric conversion layer to harmful processing conditions
2Loss of information
If color filters are arranged in mosaic shape on light-receiving sections, then color signals can be obtained, but light use efficiency and sensitivity are reduced because about 2/3 of incident light is absorbed by the color filters
Solution Approach 1:
The patent transitions from a planar mosaic arrangement of color filters to a three-dimensional stacked structure with multiple photoelectric conversion layers positioned at different heights above the substrate. This dimensional change allows incident light to be utilized more efficiently by distributing absorption across multiple layers, with each layer optimized for specific wavelength ranges, thereby improving both light use efficiency and color signal acquisition
Solution Approach 2:
The patent applies local quality by creating regions with different optical properties at different locations and heights. The first photoelectric conversion layer is positioned to capture blue light, the second layer captures green light, and the third layer captures red light. Each layer has optimized optical characteristics for its specific function, allowing efficient spectral decomposition without the light waste associated with mosaic color filters
3Reliability
If multiple photoelectric conversion layers are laminated on semiconductor substrate, then light use efficiency and sensitivity are improved, but manufacturing complexity increases due to multiple electrode and layer formation steps
Solution Approach 1:
The patent applies universality by using the same basic layer structure (electrode-photoelectric conversion layer-electrode) repeatedly for all three color channels. This modular approach, where each photoelectric conversion section follows the same pattern, simplifies manufacturing by repeating proven processes rather than creating entirely new structures for each layer, thereby reducing overall manufacturing complexity while maintaining high light use efficiency
Solution Approach 2:
The patent merges multiple manufacturing operations into unified steps. For example, the first electrode is formed as a continuous layer that is then partitioned into individual sections, and the second electrode is formed as a single continuous layer covering all photoelectric conversion sections. This merging of operations reduces the number of separate processing steps and simplifies the overall manufacturing process while achieving the desired multi-layer functionality
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 method enhances light use efficiency and sensitivity, preventing performance degradation of the photoelectric conversion layer while allowing for high-resolution color imaging without conspicuous false colors.
Implementation Method 1
photoelectric conversion layers, which generate signal charges (electrons, holes) with respect to red (R), blue (B), and green (G) light components
Data Source
AI summary
After electrode pads 20 formed on a silicon substrate 1 and an electrode 21 to be connected thereto are exposed, a photoelectric conversion layer 12 is formed via a first mask 23 which covers exposed surfaces of the electrode pads 20 and the electrode 21. Then, a second electrode 13 is formed on a third electrode via a second mask 26 in which an opening is formed. This establishes a connection between the second electrode 13 and the electrode pads 20.