SPAD Pixel Wiring Layout for Withstand Voltage Isolation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing photoelectric conversion apparatuses with SPAD pixels face challenges in ensuring withstand voltage between the first and second wiring supplying potentials to the cathode and anode of avalanche photodiodes, respectively.
Innovation Solution
The apparatus includes a wiring structure with a first wiring closest to the layer supplying voltage to the second conductivity type region, a plug connecting the first wiring to this region, and a second wiring covering the first region when viewed in plan, with the distance between the second wiring and the layer being shorter than that between the first wiring and the layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the first wiring is positioned closest to the layer to supply voltage to the second conductivity type region, then the voltage distribution is improved, but the withstand voltage between the first and second wiring may be compromised due to insufficient spacing
Solution Approach 1:
The patent positions the second wiring to cover the first region in plan view while being closer to the layer than the first wiring, utilizing the vertical dimension to resolve the contradiction. This three-dimensional wiring arrangement allows the second wiring to be spatially separated from the first wiring in the vertical direction while maintaining electrical connection to the first region, thereby ensuring both proper voltage distribution and sufficient withstand voltage between wirings.
Solution Approach 2:
The patent introduces an insulating film between the first and second wirings as an intermediary element. This insulating layer provides electrical isolation while allowing both wirings to be positioned close to the layer for optimal voltage distribution, thus resolving the contradiction between manufacturing precision and reliability by mediating the electrical interaction between the two wirings.
2Manufacturing precision
If the second wiring is positioned closer to the layer to cover the first region, then the connection to the first region is improved, but the distance between wirings may be reduced affecting voltage isolation
Solution Approach 1:
The patent utilizes vertical positioning to allow the second wiring to cover the first region in plan view while being closer to the layer, achieving improved connection without compromising voltage isolation. The insulating film provides the necessary electrical separation in the vertical dimension, enabling both objectives to be simultaneously achieved.
Solution Approach 2:
The patent applies different properties to different regions: the second wiring is positioned close to the layer and covers the first region to ensure good electrical connection and voltage distribution, while the insulating film is strategically placed between the wirings to provide localized electrical isolation where needed, thus resolving the contradiction through spatially differentiated properties.
3Productivity
If both wirings are positioned close to the layer for optimal voltage distribution, then the photoelectric conversion efficiency is improved, but the risk of electrical breakdown between wirings increases
Solution Approach 1:
The insulating film serves as a mediator between the first and second wirings, enabling both wirings to be positioned close to the layer for optimal photoelectric conversion efficiency while preventing electrical breakdown through provided electrical isolation. This intermediary layer resolves the contradiction by decoupling the electrical interaction while maintaining spatial proximity.
Solution Approach 2:
The patent employs vertical positioning combined with insulating films to achieve close proximity of both wirings to the layer for enhanced photoelectric conversion, while the insulating film in the vertical dimension prevents electrical breakdown, thus resolving the contradiction between productivity and reliability.
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 ensures proper voltage distribution and withstand voltage between the wirings, enhancing the reliability and sensitivity of the photoelectric conversion apparatus, particularly for long-wavelength light.
Implementation Method 1
a photoelectric conversion apparatus including a pixel array in which SPAD (Single Photon Avalanche Diode) pixels are formed
Implementation Method 2
a photocarrier attributable to a single photon causes avalanche multiplication in a PN junction region within a semiconductor region
Data Source
AI summary
An apparatus includes a layer that has a light incident surface and includes elements, and a wiring structure. Each of the elements includes a photodiode. The photodiode includes first and second regions of first and second conductivity types. A voltage is supplied to the second region through a second-conductivity-type region. The wiring structure includes a first wiring positioned closest to the layer among wirings to supply the voltage to the second-conductivity-type region, a plug connecting the first wiring and the second-conductivity-type region, and a second wiring supplying a voltage to the first region. The second wiring covers the first region when viewed in plan, and a distance between the second wiring and the layer is shorter than a distance between the first wiring and the layer.