Photoelectric Conversion Metal Layer Coverage for Level Difference Reduction
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Solution Overview
Problem
The existing photoelectric conversion apparatuses with global shutter functions face issues due to level differences and residue formation caused by varying metal layer coverage between pixel and peripheral regions, affecting optical characteristics and manufacturing reliability.
Innovation Solution
A photoelectric conversion apparatus design that includes a metal layer covering the charge holding portion and electrode pattern in the pixel region, and an upper surface of an electrically conductive pattern in the peripheral region, with an interlayer insulating film and contact plugs to connect wiring and electrode patterns, ensuring uniform coverage and reducing level differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the metal layer coverage is reduced in the peripheral region compared to the pixel region, then light shielding effectiveness in the pixel region is improved, but level differences between regions are generated affecting optical characteristics
Solution Approach 1:
The patent applies local quality by making the metal layer thickness region-dependent: the first thickness in the pixel region provides optimal light shielding, while the second thickness (smaller than first) in the peripheral region reduces level differences. This spatial variation in metal layer properties resolves the contradiction between light shielding effectiveness and manufacturing precision.
2Manufacturing precision
If the metal layer coverage is reduced in the peripheral region, then level differences are minimized, but residues may exist in layers above the metal layer decreasing reliability
Solution Approach 1:
The patent uses local quality to address residue formation by providing different metal layer thicknesses in different regions. The sufficient thickness in the pixel region prevents residue formation and ensures reliability, while the reduced thickness in the peripheral region minimizes level differences. The insulating film configuration further addresses residues by providing proper coverage over the metal layer.
3Device complexity
If the metal layer coverage is reduced in the peripheral region, then manufacturing complexity is reduced, but exposure condition setting becomes difficult during photolithography
Solution Approach 1:
The patent applies local quality by configuring the insulating film with different thicknesses in different regions. This approach maintains the benefits of region-specific metal layer thicknesses while providing a uniform surface for subsequent photolithography processes, making exposure condition setting easier and more consistent across the entire substrate.
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 design improves the optical characteristics and manufacturing reliability by minimizing level differences and residue formation, enhancing the performance and yield of the photoelectric conversion apparatus.
Implementation Method 1
it is necessary to suppress entry of light by covering the charge holding portion with a metal layer for shielding light
Data Source
AI summary
A photoelectric conversion apparatus is provided. The apparatus comprises a pixel region in which a plurality of pixels each including a photoelectric conversion portion and a charge holding portion formed in a substrate are arranged, and a peripheral region. Above the substrate, an electrically conductive layer including an electrode pattern for transferring charges in the photoelectric conversion portion to the charge holding portion, a wiring layer including a wiring pattern electrically connected to the electrode pattern, an interlayer film arranged between the wiring layer and the substrate, a metal layer arranged between the interlayer film and the substrate and arranged so as to cover at least the charge holding portion and the electrode pattern are provided. In the peripheral region, the metal layer covers at least an upper surface of an electrically conductive pattern included in the electrically conductive layer.