Stacked Image Sensor Wiring Fault Detection in Pixel Blocks

Solution Overview

Problem

Existing imaging devices face challenges in inspecting wiring faults within pixel rows or columns with minimal additional circuits, leading to increased chip area and complexity.

Innovation Solution

An imaging device with a stacked substrate configuration, including a pixel array and a pixel control portion, utilizes fault detection circuits that connect wiring lines in series to detect faults by measuring potential differences across intermediate positions, allowing for efficient detection of open circuit faults with minimal additional circuitry.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If wiring fault detection circuits are added to inspect pixel rows or columns, then wiring fault detection capability is improved, but device complexity increases

Engineering Contradiction:

Improvewiring fault detection capabilityVSAvoidcircuit complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The pixel control portion is designed to serve dual functions: controlling pixel operations during normal imaging and performing wiring fault detection during inspection mode. By making the control circuit universal, separate dedicated detection circuits are eliminated, resolving the contradiction between detection capability and circuit complexity

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The imaging device performs self-diagnosis by using its own control circuits to detect wiring faults. The pixel control portion autonomously tests wiring integrity without requiring external testing equipment, improving detection capability while avoiding additional circuit complexity

Inventive Principle:

Principle #25Self-service

2Reliability

If wiring fault detection circuits are added to inspect pixel rows or columns, then wiring fault detection capability is improved, but chip area increases

Engineering Contradiction:

Improvewiring fault detection capabilityVSAvoidchip area

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The pixel control portion is designed to serve dual functions: controlling pixel operations during normal imaging and performing wiring fault detection during inspection mode. By making the control circuit universal, separate dedicated detection circuits are eliminated, resolving the contradiction between detection capability and chip area

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The fault detection function is merged with the pixel control portion, combining two functions into a single integrated circuit block. This merging eliminates the need for separate detection circuitry, thereby preventing chip area increase while maintaining detection capability

Inventive Principle:

Principle #5Merging (Combining)

3Measurement precision

If multiple additional circuits are used for wiring fault detection, then wiring fault detection precision is improved, but device complexity increases

Engineering Contradiction:

Improvewiring fault detection precisionVSAvoidcircuit complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The imaging device performs self-diagnosis by using its own control circuits to detect wiring faults. The pixel control portion autonomously tests wiring integrity without requiring external testing equipment, improving detection capability while avoiding additional circuit complexity

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The pixel array is divided into multiple pixel blocks with detection performed in sequential stages. This preliminary segmentation allows systematic fault localization without requiring complex simultaneous testing circuits, maintaining detection precision while simplifying circuit design

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS12088945B2Imaging device and electronic equipment

Publication Date: 2024.09.10 SONY SEMICON SOLUTIONS CORP

AI summary

In one example, an imaging device includes stacked first and second substrates. The first substrate has an array of light receiving pixels divisible into pixel blocks and the second substrate has a pixel control portion that controls the pixels.The first substrate includes a first wiring line that transmits a first voltage, a second wiring line that transmits a second voltage, and a fault detection circuit that detects a wiring fault for each pixel block. The fault detection circuit detects a wiring fault by connecting wiring lines corresponding to pixel columns or pixel rows in series in each pixel block, connecting one of the ends of a wiring chain connected in series in each pixel block to the first wiring line, connecting the other end to the second wiring line, and detecting a wiring fault based on a potential at an intermediate position of the wiring chain.