Solid-State Image Sensor Insulating Film Layout for Low Noise
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Solution Overview
Problem
The existing method of manufacturing solid-state image sensors, where a silicon nitride film covers almost the entire surface of transistors and pixel regions, blocks hydrogen diffusion, leading to insufficient hydrogen termination of dangling bonds in the gate insulating film, resulting in high noise levels.
Innovation Solution
A method involving the formation of a nitrogen-containing silicon compound insulating film on the photoelectric conversion element and MOS transistor, with specific openings and contact plugs to facilitate hydrogen termination during hydrogen sintering, ensuring effective hydrogen supply to the gate insulating film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a silicon nitride film is formed to cover the photoelectric converter and transistor surfaces for plasma damage protection, then plasma damage to the photoelectric converter is reduced, but hydrogen diffusion is blocked and hydrogen termination of dangling bonds becomes insufficient
Solution Approach 1:
The patent divides the silicon nitride film into two functional regions: a first silicon nitride film covering the photoelectric converter for plasma protection, and a second silicon nitride film in the transistor region with openings that allow hydrogen diffusion. This segmentation allows each region to have optimized properties for its specific function.
Solution Approach 2:
The patent applies different structural configurations of silicon nitride film to different locations: the photoelectric converter region receives continuous silicon nitride coverage for maximum plasma protection, while the transistor region has patterned openings to enable hydrogen termination. This local differentiation resolves the contradiction between plasma protection and hydrogen diffusion requirements.
2Device complexity
If the silicon nitride film is left behind on the photoelectric converter without etch back, then manufacturing complexity is reduced and plasma damage is minimized, but noise performance deteriorates due to insufficient hydrogen termination
Solution Approach 1:
The patent segments the silicon nitride film formation process into two distinct stages: first forming a silicon nitride film over the entire surface including the photoelectric converter, then selectively removing portions in the transistor region through etch back. This maintains plasma protection on the photoelectric converter while enabling hydrogen termination in transistor regions.
Solution Approach 2:
The patent extracts the silicon nitride film from the transistor region through selective etch back, removing only the portions that would block hydrogen diffusion while preserving the film on the photoelectric converter. This extraction resolves the contradiction by eliminating the harmful blocking effect in specific locations while maintaining protective coverage elsewhere.
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 approach enables reliable hydrogen termination of dangling bonds, resulting in a low-noise solid-state image sensor by allowing uninterrupted hydrogen supply during sintering processes.
Implementation Method 1
Since the silicon nitride film hardly transmits hydrogen, the silicon nitride film blocks hydrogen diffusion during hydrogen sintering
Implementation Method 2
allowing uninterrupted hydrogen supply during sintering processes
Data Source
AI summary
A method of manufacturing a solid-state image sensor comprising a pixel part including a photoelectric conversion element and a MOS transistor, comprising steps of forming a first insulating film made of a nitrogen-containing silicon compound on the photoelectric conversion element and the MOS transistor, forming an opening in at least a portion of the first insulating film, which is positioned above a channel of the MOS transistor, forming a second insulating film on the first insulating film, forming a contact hole extending through the second insulating film and the first insulating film, and forming, in the contact hole, a contact plug to be connected to the MOS transistor.