Multi-Pixel Image Sensor Isolation for Uniform Angular Selectivity

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Solution Overview

Problem

Conventional image sensors face challenges in achieving uniform angular selectivity and light sensitivity across varying lighting conditions and positions within the sensor, which affects phase detection autofocus performance.

Innovation Solution

The implementation of a multi-pixel detector with a partial isolation structure, including a multi-finger isolation structure and adjustable lateral lengths of partial isolation structures, along with offset shared microlenses, to enhance light sensitivity and angular selectivity uniformly across the image sensor.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional image sensors are used without partial isolation structures, then the device complexity is low, but the angular selectivity and light sensitivity are non-uniform across different positions and lighting conditions

Engineering Contradiction:

Improveangular selectivity uniformityVSAvoidisolation structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The isolation structure is divided into multiple partial isolation structures arranged in a multi-finger configuration between adjacent photodiode regions. Each partial isolation structure is separated from others by gaps, creating a segmented isolation system that reduces lateral light coupling while maintaining structural simplicity and enabling uniform angular selectivity across the sensor array.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Partial isolation structures are selectively positioned between specific adjacent photodiode regions where lateral light coupling needs to be reduced. The isolation structures have varying lateral lengths that are optimized for local conditions, providing tailored isolation performance different across the sensor while maintaining overall uniformity in angular selectivity.

Inventive Principle:

Principle #3Local quality

2Reliability

If partial isolation structures with adjustable lateral lengths are implemented, then light sensitivity and angular selectivity are improved uniformly, but the manufacturing precision requirements increase

Engineering Contradiction:

Improvelight sensitivity uniformityVSAvoidlateral length control precision

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The lateral lengths of partial isolation structures are varied as a design parameter to optimize performance. By adjusting the lateral length of each partial isolation structure, the structure achieves optimal balance between light sensitivity and angular selectivity uniformity across different positions on the sensor, while the parameter variations are designed to be manufacturable with standard precision tolerances.

Inventive Principle:

Principle #35Parameter changes

3Measurement precision

If multi-pixel detectors with partial isolation structures are used, then phase detection autofocus performance is enhanced, but the device complexity increases due to additional isolation structures

Engineering Contradiction:

Improvephase detection precisionVSAvoiddetector structure complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The detector is organized as a multi-pixel array with partial isolation structures segmented between pixel groups. This segmentation enables independent optimization of each pixel region for phase detection while reducing cross-talk, thereby improving measurement precision without requiring complete isolation of all structures.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The partial isolation structures serve multiple functions: they reduce lateral light coupling between adjacent photodiodes, maintain uniform angular selectivity across the sensor, and enable improved phase detection autofocus performance. This multi-functionality achieves enhanced measurement precision without proportionally increasing device complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 configuration improves phase detection autofocus by maintaining consistent angular selectivity and light sensitivity across the image sensor, regardless of position or lighting conditions, thereby enhancing image acquisition performance.

Implementation Method 1

The image sensor includes an array of pixels having photosensitive elements (e.g., photodiodes) that absorb a portion of the incident image light and generate image charge upon absorption of the image light

Methodology Applied

Scientific EffectPhotoelectric effect: Photoelectric Effect

Data Source

PatentUS11967602B2Image sensor with multi-pixel detector and partial isolation structure

Publication Date: 2024.04.23 OMNIVISION TECHNOLOGIES INC

AI summary

A multi-pixel detector of an image sensor is described. The multi-pixel detector includes a first photodiode region disposed within a semiconductor substrate to form a first pixel, a second photodiode region disposed within the semiconductor substrate to form a second pixel adjacent to the first pixel, and a partial isolation structure extending from a first side of the semiconductor substrate towards a second side of the semiconductor substrate between the first photodiode region and the second photodiode region. A length of a lateral portion of the partial isolation structure between the first photodiode region and the second photodiode region is less than a lateral length of the first photodiode region.