Tapered Light-Guiding Structure for Image Sensors
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Solution Overview
Problem
Existing image sensors face challenges in minimizing plasma damage to semiconductor substrates and improving electrical and optical properties, which affects the quality of digital images formed by these sensors.
Innovation Solution
A light-guiding structure is implemented using sequentially stacked insulating layers with different etching rates, where the light-guiding structure has a tapered sidewall and a bottom surface parallel to the semiconductor substrate, minimizing plasma damage and enhancing light reception by stabilizing the etching process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a conventional light-guiding structure is used, then the image sensor can receive light, but plasma damage to the semiconductor substrate occurs during manufacturing
Solution Approach 1:
The patent introduces an intermediary structure (the light-guiding structure with specific insulating layers and tapered sidewall) that mediates between the plasma etching process and the semiconductor substrate. This intermediary protects the substrate from direct plasma damage while still allowing the etching process to proceed effectively.
Solution Approach 2:
The patent applies preliminary protective measures by forming the tapered sidewall structure and insulating layers before the plasma etching process. This preliminary action prevents plasma damage to the substrate by creating a protective configuration in advance.
2Use of energy by moving object
If the light-guiding structure penetrates deep into the semiconductor substrate, then light reception is improved, but plasma damage to the substrate increases
Solution Approach 1:
The patent applies local quality by creating a tapered sidewall structure where the width of the light-guiding structure varies along its depth. The structure is wider at the top and narrows toward the bottom, allowing deep penetration for light reception while minimizing the plasma exposure area at the substrate level.
Solution Approach 2:
The patent transitions from a vertical cross-sectional view to a three-dimensional tapered structure. By changing the geometry to include a tapered sidewall, the structure achieves deep penetration in the vertical dimension while reducing the horizontal footprint at the substrate level, thereby minimizing plasma damage.
3Ease of manufacture
If the sidewall of the light-guiding structure is vertical, then manufacturing is simpler, but plasma damage to the substrate increases
Solution Approach 1:
The patent introduces asymmetry by forming a tapered sidewall instead of a vertical one. The sidewall angle varies from the vertical, creating an asymmetric profile that reduces plasma damage to the substrate while still being manufacturable through controlled etching processes.
4Ease of manufacture
If the insulating layers have the same etching rate, then material selection is easier, but the etching process cannot be precisely controlled
Solution Approach 1:
The patent changes the etching rate parameter by selecting insulating layer materials with different etching rates. This allows precise control of the etching process, enabling the formation of the tapered sidewall structure and the light-guiding structure at different depths through selective etching.
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
The light-guiding structure effectively reduces plasma damage to the semiconductor substrate and improves the electrical and optical properties of the image sensor, leading to enhanced digital image quality.
Implementation Method 1
Light-guiding structure may extend into, but not through, the first insulating layer
Implementation Method 2
An anti-reflective layer may be disposed between the semiconductor substrate and the first insulating layer
Data Source
AI summary
An example embodiment relates to a light-guiding structure. The light-guiding structure may include a bottom surface and a sidewall defined by a first, a second, and a third insulating layer disposed on a semiconductor substrate. The bottom surface may be parallel to a main surface of the semiconductor substrate and may be disposed in the first insulating layer. The sidewall may penetrate the second and third insulating layers to extend to the first insulating layer, and the sidewall may be tapered with respect to the main surface of semiconductor substrate. The light-guiding structure may be included in a image sensor. The image sensor may be included in a processor-based system.