Infrared Pixel Defect Detection via Self-Heating Current Differential
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for inspecting infrared solid-state image sensors are inefficient, as they require downstream inspection after packaging, leading to lower throughput and higher production costs due to the inability to detect defective pixels early in the manufacturing process.
Innovation Solution
An apparatus and method that includes a current control unit, A-D converter, and determining unit to differentiate between normal and defective infrared detection pixels by supplying different constant currents and calculating signal differences, allowing for early detection of defective pixels on wafers or chips.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If inspection is performed after packaging in the downstream stage, then the manufacturing process can be completed, but throughput decreases and production costs increase
Solution Approach 1:
The patent applies preliminary action by performing defective pixel detection during the manufacturing process itself, specifically using self-heating measurement on infrared detection pixels before packaging. This allows defects to be identified early when pixels are still accessible and testable, eliminating the need for downstream inspection after packaging and thereby improving throughput while maintaining detection reliability
2Reliability
If inspection is performed after packaging in the downstream stage, then the manufacturing process can be completed, but production costs increase
Solution Approach 1:
The patent performs defective pixel detection during manufacturing using self-heating measurement techniques, which identifies defects early when they can be addressed or filtered out during production. This preliminary detection approach reduces the need for costly downstream inspection and replacement operations, thereby lowering overall production costs while maintaining reliable defect detection
Solution Approach 2:
The patent utilizes the self-heating property of infrared detection pixels as a built-in diagnostic mechanism. By measuring the temperature rise of pixels when subjected to constant current, the system leverages the pixels' own operational characteristics to detect defects, eliminating the need for external complex inspection equipment and reducing production costs
3Productivity
If a known method of determining pixel address is used, then replacement can be done quickly, but inspection cannot be performed on infrared sensor chips or wafers
Solution Approach 1:
The patent enables defective pixel detection during the manufacturing stage by measuring self-heating characteristics of infrared detection pixels on wafers or chips before they are packaged. This preliminary measurement capability allows quality control to be performed at the chip level, providing both early defect detection and the ability to determine pixel addresses for replacement when needed
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 early detection of defective pixels during the manufacturing process, improving image quality without increasing production costs or decreasing throughput.
Implementation Method 1
an incident infrared ray of approximately 10 μm in wavelength is converted into heat by an absorption mechanism
Implementation Method 2
the temperature change in the heat sensing unit caused by the small amount of heat is then converted into an electrical signal by a thermoelectric converting means
Implementation Method 3
silicon pn junctions that convert temperature changes into voltage changes by applying a constant forward current
Implementation Method 4
a first self-heating temperature rise characteristic and a second self-heating temperature rise characteristic at different constant currents
Data Source
AI summary
An apparatus includes: a current control unit to control an amount of constant current and supply a first and second constant currents to an infrared detection pixel; a constant current supply time control unit to control periods of time in which the first and second constant currents are supplied to the infrared detection pixel; an A-D converter to convert a first and second electrical signals from the infrared detection pixel into a first and second digital signals, the first and second electrical signals being generated when the first and second constant currents is supplied to the infrared detection pixel, respectively; a subtracting unit to calculate a difference between the first and second digital signals; and a determining unit to determine whether the infrared detection pixel is a defective pixel based on the absolute value of the difference calculated by the subtracting unit.