Photodiode Detection Device with Planarizing Layer for Leak Path Prevention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing detection devices with PIN photodiodes mounted on active matrix array substrates face reduced detection sensitivity due to the restriction in photodiode arrangement caused by contact holes, leading to leak paths and a smaller effective light-receiving area.
Innovation Solution
A detection device design featuring a substrate with a photodiode structure where a lower electrode, semiconductor layer, and upper electrode are stacked, with a transistor integrated within the photodiode, an insulating layer, and a planarizing layer that projects towards the photodiode, covering the contact hole and overlapping with the insulating layer, allowing for electrical coupling of the lower electrode to the transistor at the contact hole's bottom.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If contact holes are provided to electrically couple transistors to photodiodes, then electrical connection is achieved, but steps formed by contact holes create leak paths and reduce effective light-receiving area
Solution Approach 1:
The patent introduces a planarizing layer that extends in the vertical dimension to cover the steps formed by contact holes. This layer fills the vertical gap created by the contact hole structure, providing a flat surface that prevents leak paths while allowing the photodiode to be positioned optimally for light reception.
Solution Approach 2:
The planarizing layer acts as an intermediary structure between the contact holes and the photodiode. It mediates the geometric mismatch by providing a flat interface that allows the photodiode to cover the contact hole without being constrained by the stepped structure, thus maintaining both electrical coupling and light-receiving area.
2Reliability
If photodiodes are arranged to avoid overlapping contact hole steps, then leak paths are reduced, but the arrangement is restricted and effective light-receiving area is reduced
Solution Approach 1:
The planarizing layer adds vertical dimension coverage by extending over the contact hole steps. This allows the photodiode to be positioned in the optimal plane for light reception while the planarizing layer handles the vertical gap filling, separating the light-receiving function from the electrical coupling function.
Solution Approach 2:
The structure is segmented into distinct functional layers: the contact holes provide electrical coupling, the planarizing layer provides geometric planarity and leak path prevention, and the photodiode provides light reception. This segmentation allows each component to optimize its function without compromising the others.
3Area of stationary object
If photodiodes are positioned to cover contact holes, then effective light-receiving area is maximized, but steps may cause short circuits between electrodes
Solution Approach 1:
The planarizing layer serves as an insulating intermediary between the contact holes and the photodiode electrodes. It provides both geometric planarity and electrical insulation, allowing the photodiode to cover the contact hole for maximum light reception while preventing direct contact between electrodes that would cause short circuits.
Solution Approach 2:
The planarizing layer extends in the vertical dimension to bridge the gap between the contact hole structure and the photodiode plane. This vertical extension provides both the flat surface needed for optimal photodiode positioning and the insulating barrier needed to prevent short circuits.
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 reduces the occurrence of leak paths and enhances detection sensitivity by minimizing the reduction in the effective light-receiving area of the photodiodes, while also preventing short circuits between the upper and lower electrodes.
Implementation Method 1
a photodiode in which a lower electrode 35, a semiconductor layer 30, and an upper electrode 34 are stacked on the substrate 21 in the order as listed
Data Source
AI summary
According to an aspect, a detection device includes: a substrate; a photodiode in which a lower electrode, a semiconductor layer, and an upper electrode are stacked on the substrate in the order as listed; a transistor provided in the photodiode; an insulating layer provided between layers of the substrate and the photodiode; and a planarizing layer covering the insulating layer. The insulating layer comprises a projecting portion that projects toward the photodiode in a direction orthogonal to the substrate. The planarizing layer has a contact hole provided in a position that is below the photodiode and overlaps the projecting portion of the insulating layer. The photodiode is provided on an upper side of the planarizing layer and is also provided so as to cover the contact hole. The lower electrode of the photodiode is electrically coupled to the transistor at a bottom of the contact hole.