Solid-State Image Sensor Insulating Layer Planarization
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Solution Overview
Problem
The existing methods for manufacturing solid-state image sensors with light waveguides result in steps on the upper surface of the insulating member, leading to insufficient planarization and reduced image quality due to the removal of high refractive index insulating members in peripheral regions.
Innovation Solution
A method involving the formation of multiple insulating and conductive layers, where the high refractive index waveguide members are strategically removed to expose connecting portions, allowing for plug formation and planarization, thereby reducing surface steps and enhancing image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the insulating member of the high refractive index is removed in the peripheral region to form a through hole, then the through hole can be formed for plug arrangement, but a step is generated on the upper surface of the insulating member
Solution Approach 1:
The insulating member is segmented into two types: a first insulating member (low refractive index) covering the entire surface including peripheral regions, and a second insulating member (high refractive index) forming the waveguide core only in the pixel region. This segmentation allows the first insulating member to provide a planar surface for plug formation while the second insulating member provides the waveguide function where needed.
Solution Approach 2:
Different refractive index properties are assigned to different regions: the first insulating member with low refractive index covers peripheral regions to maintain surface planarity, while the second insulating member with high refractive index is localized to the pixel region to provide waveguide functionality. This local differentiation resolves the conflict between surface planarity and waveguide formation.
2Ease of manufacture
If the insulating member of the high refractive index is removed in the peripheral region, then the through hole can be formed, but the solid-state image sensor becomes tall
Solution Approach 1:
The insulating member structure is segmented such that the first insulating member extends across the entire surface including peripheral regions at a uniform thickness, providing a flat upper surface. The second insulating member is segmented to exist only in the pixel region, allowing through holes to be formed in the first insulating member in peripheral regions without creating height differences.
Solution Approach 2:
The high refractive index second insulating member is localized only to the pixel region where waveguide functionality is required, while the low refractive index first insulating member covers the peripheral regions. This local quality differentiation enables through hole formation in peripheral regions at a uniform height level, preventing the sensor from becoming tall.
3Reliability
If the insulating member of the high refractive index remains in the peripheral region, then the waveguide structure is complete, but it is difficult to form a through hole for plug arrangement
Solution Approach 1:
The insulating member system is divided into two functional components: the first insulating member serving as a universal substrate and planarization layer across all regions, and the second insulating member serving as the waveguide core specifically in the pixel region. This segmentation allows through holes to be formed in the first insulating member without compromising the waveguide structure formed by the second insulating member.
Solution Approach 2:
The first insulating member acts as an intermediary layer between the substrate and the second insulating member. It provides a planar surface for through hole formation and plug arrangement, while the second insulating member maintains the waveguide structure. The first insulating member mediates between the manufacturing requirement for through holes and the structural requirement for waveguides.
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 improves the planarization of the surface, facilitating better light waveguide functionality and image quality by minimizing surface irregularities and allowing for efficient plug formation.
Implementation Method 1
an insulating member of a high refractive index is formed on this insulating member. A portion of the insulating member of the high refractive index arranged in the opening forms the core of a light waveguide
Data Source
AI summary
A method of manufacturing a solid-state image sensor is provided. A first insulating member and an electrically conductive member is formed above a semiconductor substrate. A connecting portion of an upper surface of the electrically conductive member is covered with part of the first insulating member. First openings corresponding to the photoelectric conversion units are formed in the first insulating member. A second insulating member covering the first insulating member is then formed. The second insulating member is partially removed to expose the part of the first insulating member covering the connecting portion. A third insulating member that covers the first and second insulating members is then formed. The third insulating member is partially removed to expose the second insulating member. A second opening to expose the connecting portion is then formed to form a plug.