Halogen Surface Treatment for BSI Image Sensor Substrate Passivation
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Solution Overview
Problem
Backside illumination (BSI) image sensors face issues with dark current and noise due to dangling bonds on the substrate surfaces, which degrade image quality.
Innovation Solution
A halogen surface treatment process is applied to form silicon halogen compound layers on the substrate surfaces, eliminating dangling bonds and improving device characteristics by reducing noise and dark currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If BSI image sensor structure is used to eliminate obstruction from additional layers, then quantum efficiency is improved, but dark current increases due to dangling bonds on substrate surfaces
Solution Approach 1:
A passivation layer is introduced as an intermediary between the substrate surface and the environment. This layer contains dangling bonds on the substrate surface, preventing them from generating dark current while allowing the BSI structure to maintain its quantum efficiency advantages.
Solution Approach 2:
The electrical properties of the substrate surface are changed by introducing a passivation layer with different material composition and bonding characteristics. This changes the surface state from one that generates dark current to one that suppresses it, while preserving the optical performance.
2Device complexity
If substrate surface is left untreated in BSI image sensors, then manufacturing complexity is reduced, but noise increases due to dangling bonds
Solution Approach 1:
A passivation layer is applied to the substrate surface to act as a mediator that suppresses noise from dangling bonds. This adds a manufacturing step but significantly reduces noise, improving overall device performance.
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 halogen treatment effectively minimizes noise and dark current, enhancing the image quality of BSI image sensors by creating stronger bonds on the substrate surfaces, thereby improving key device characteristics.
Implementation Method 1
A halogen surface treatment process is applied to form silicon halogen compound layers on the substrate surfaces, eliminating dangling bonds
Data Source
AI summary
A method comprises forming an image sensor adjacent to a first side of a substrate, thinning a second side of the substrate, performing a halogen treatment on the second side of the substrate and forming a backside illumination layer on the second side of the substrate.