Floating Diffusion Extension Pattern for Dual Conversion Gain

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Solution Overview

Problem

Existing semiconductor devices face challenges in efficiently operating image sensors across a wide range of illumination environments, struggling to maintain performance in both low and high illumination conditions.

Innovation Solution

A semiconductor device design incorporating a substrate with a photoelectric conversion device, floating diffusion regions, transistors, and an extension pattern, where the extension pattern is in contact with a second floating diffusion region, allowing for dual conversion gain operation and efficient capacitance adjustment between high and low illumination modes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If capacitance is increased to reduce noise in low illumination conditions, then noise performance is improved, but device area and complexity increase

Engineering Contradiction:

Improvenoise performanceVSAvoiddevice area

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent implements dynamic capacitance adjustment by configuring transistors (first and second transistors) that can selectively connect or disconnect the extension pattern from the second floating diffusion region. This allows the capacitance of the second floating diffusion region to be dynamically changed between a first capacitance value (when extension pattern is connected) and a second capacitance value (when disconnected), enabling adaptive noise reduction in low illumination conditions without permanently increasing device area.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the electrical parameter (capacitance) of the second floating diffusion region by controlling the connection state of the extension pattern through transistor switching. The capacitance can be adjusted between different values (first capacitance value and second capacitance value) based on illumination conditions, allowing optimization of noise performance without fixed structural increase.

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If dual conversion gain operation is implemented to optimize performance across illumination ranges, then adaptability is improved, but device complexity increases

Engineering Contradiction:

Improveillumination environment adaptabilityVSAvoidtransistor and capacitor count

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent implements multi-functionality by designing the second floating diffusion region to serve dual purposes: it acts as a charge storage node with adjustable capacitance for noise reduction, and simultaneously functions as part of the signal readout path through the extension pattern connection. The same structural elements (transistors, capacitors, floating diffusion region) are used for both conversion gain adjustment and noise management, reducing the need for separate dedicated components.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent merges the noise reduction function with the existing pixel structure by integrating the extension pattern and associated transistors into the conventional pixel circuit. The second floating diffusion region is combined with the extension pattern to form a unified capacitive structure that serves both signal processing and noise reduction functions, rather than adding completely separate noise reduction components.

Inventive Principle:

Principle #5Merging (Combining)

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

Enables the image sensor to operate efficiently in both low and high illumination environments by selectively increasing capacitance, minimizing noise in low light conditions and lowering conversion gain in high light conditions, thus optimizing performance across varying lighting scenarios.

Implementation Method 1

a photoelectric conversion device in the substrate

Methodology Applied

Scientific EffectPhotoelectric conversion: Photoelectric Effect

Implementation Method 2

an extension pattern, a first portion of the extension pattern being in contact with the second floating diffusion region

Methodology Applied

Scientific EffectCapacitance: Capacitance

Data Source

PatentUS10879286B2Semiconductor device including floating diffusion and extension pattern

Publication Date: 2020.12.29 SAMSUNG ELECTRONICS CO LTD

AI summary

A semiconductor device and an image sensor, the semiconductor device including a substrate; a photoelectric conversion device in the substrate; a first floating diffusion region adjacent to the photoelectric conversion device; a transfer transistor connected to the photoelectric conversion device and the first floating diffusion region; a reset transistor connected to the first floating diffusion region; a dual conversion gain (DCG) transistor between the first floating diffusion region and the reset transistor; a second floating diffusion region between the DCG transistor and the reset transistor; and an extension pattern, a first portion of the extension pattern being in contact with the second floating diffusion region.