UV Photosensor Treatment for Dark Current and Ghosting
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Solution Overview
Problem
Photosensors used in semiconductor lithography suffer from dark current and ghosting effects, leading to distorted image signals and reduced accuracy in measuring mask structures.
Innovation Solution
Irradiate the photosensor surface with UV light to reduce the extent of dark current and ghosting effects by altering the electronic state density within the sensor material, and adjust irradiation parameters based on the extent of these effects until the desired level is achieved.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If photosensors are used for mask inspection in semiconductor lithography, then high light sensitivity and image quality are achieved, but dark current and ghosting effects cause image aberrations and signal distortion
Solution Approach 1:
The patent applies preliminary action by irradiating the photosensor with UV light before actual mask inspection to reduce dark current and ghosting effects. This pre-treatment modifies the electronic state density in the sensor material, preparing the photosensor in an optimized state for subsequent high-precision measurements, thereby eliminating harmful effects before they degrade image quality
Solution Approach 2:
The patent changes physical parameters of the photosensor by using UV irradiation to alter the electronic state density within the sensor material. This parameter change reduces the magnitude of dark current and ghosting effects, allowing the photosensor to maintain high measurement precision while minimizing harmful artifacts in the captured images
2Reliability
If UV light irradiation is applied to reduce dark current and ghosting effects, then image quality improves, but additional treatment steps and time are required
Solution Approach 1:
The patent implements feedback by monitoring image quality metrics during and after UV irradiation treatment. The system evaluates whether dark current and ghosting effects have been reduced to acceptable levels, and adjusts the irradiation duration accordingly. This feedback mechanism ensures reliable photosensor performance while minimizing unnecessary treatment time by stopping irradiation once the desired effect is achieved
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
Improves the quality of the photosensor by significantly reducing image aberrations caused by dark current and ghosting, ensuring accurate image detection and measurement.
Implementation Method 1
The photosensor has a plurality of photosensitive pixels which are designed to convert light into an electrical signal using the internal photoelectric effect
Implementation Method 2
irradiating a sensor surface of the photosensor with UV light; repeating the determination of the extent of the image aberration and the irradiation of a sensor surface until the determined extent of the image aberration falls below a specified level
Data Source
AI summary
A method for treating a photosensor, in particular for use in an optical measuring system for semiconductor lithography. The photosensor has a sensor surface having a plurality of photosensitive pixels which are designed to convert light into an electrical signal using the internal photoelectric effect. The method comprises the following steps:determining an extent of an image aberration caused by a dark current effect and/or a ghosting effect;irradiating the sensor surface of the photosensor with UV light; andrepeating the determination of the extent of the image aberration and the irradiation of the sensor surface until the determined extent of the image aberration falls below a specified level.The quality of the photosensor is improved by the UV irradiation.