Asymmetric Light Waveguide Opening Shape for Void Prevention
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Solution Overview
Problem
The existing solid-state image sensors with light waveguides may form voids during manufacturing, leading to reduced light transmission to photoelectric conversion portions due to reflection effects, which affects the efficiency of light condensation and focus detection.
Innovation Solution
The light waveguide's upper surface is designed with a shape that ensures a width ratio of 0.6d or more in both directions, preventing void formation by maintaining a curvature radius of 0.3d or more, allowing efficient light guidance to the photoelectric conversion portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a material is embedded in an opening to form a light waveguide with a non-circular shape to efficiently perform light condensation, then light condensation efficiency is improved, but voids may be formed during manufacturing which reduces light transmission
Solution Approach 1:
The opening is designed with an asymmetric shape where the width in the first direction (L1) is different from the width in the second direction (L2). This asymmetric configuration enables efficient light condensation while preventing void formation during material embedding, as the shape satisfies the condition that a circle of 0.6d diameter drawn at each point on the circumference does not include portions outside the opening.
2Reliability
If the light waveguide upper surface is made circular, then void formation is reduced, but light condensation efficiency decreases
Solution Approach 1:
The invention changes the geometric parameters of the opening from a conventional circular shape to a specific non-circular shape defined by width L1 in the first direction and width L2 in the second direction, where L1 ≠ L2. This parameter modification maintains void-free manufacturing while achieving superior light condensation efficiency.
3Quantity of substance
If the light waveguide size is increased to improve light transmission, then more light reaches the photoelectric conversion portion, but resolution decreases due to excessive size
Solution Approach 1:
The opening shape is designed with specific curvature characteristics where a circle of 0.6d diameter can be drawn at each point on the circumference without extending outside the opening. This curved boundary design optimizes light guidance while maintaining compact dimensions, achieving high light transmission without excessive waveguide size that would degrade resolution.
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 effectively suppresses void formation and enhances light use efficiency, improving the amount of light reaching the photoelectric conversion portions and maintaining resolution without excessive light waveguide size, which could decrease image quality.
Implementation Method 1
a material having a refractive index higher than that of the insulating layer
Implementation Method 2
the amount of light reaching the photoelectric conversion portion is decreased due to a reflection effect of incident light by the void
Data Source
AI summary
A solid-state image sensor includes a substrate including a photoelectric conversion portion, an insulating layer having an opening, and a member arranged inside the opening. Letting d be a depth of the opening, the opening has, at an upper end of the opening, a shape having a width in a first direction parallel to the surface of the substrate, and a width in a second direction parallel to the surface of the substrate and orthogonal to the first direction. The widths in the first and second directions are different from each other. The shape is capable of drawing, at each point on a circumference of the opening at the upper end, a circle of 0.6d in diameter which contacts the circumference at the point and does not include a portion outside the opening.