High Resolution Surface Particle Detector with Split Airstreams
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current particle counting technologies in clean room environments are limited in detecting particles smaller than 300 nm, as they rely on visual inspection methods that provide only qualitative data and are not sensitive enough for particles below 20 microns, and existing devices using optical laser technology can only detect particles up to 10,000 nm, failing to meet the stringent contamination standards of the semiconductor industry as it scales down to smaller geometries.
Innovation Solution
A device with a scanner probe and dual airstreams, where one airstream is split into high and low resolution flows, allowing a high resolution condensation particle counter to detect particles as small as 10 nm and a low resolution optical detector to detect larger particles, with control circuitry managing flow rates to ensure accurate particle counting across different sizes, and an air flow modulator to enhance particle dislodgement and reduce ejection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If visual inspection techniques are used to detect particles on cleanroom surfaces, then the inspection process is simple and quick, but the detection capability is limited to particles larger than twenty microns and only provides qualitative data
Solution Approach 1:
The patent replaces visual inspection methods with an automated particle counter that uses optical detection and condensation techniques. The device substitutes manual observation with electronic sensors and automated counting, enabling detection of particles as small as 10 nm while providing quantitative data instead of qualitative assessments.
Solution Approach 2:
The invention changes the detection parameter from visual observation (wavelengths visible to human eye) to optical scattering and condensation nucleus detection (much smaller wavelengths). This parameter change enables detection of particles two orders of magnitude smaller than visual techniques can detect, transforming the measurement capability from microns to nanometers.
2Measurement precision
If adhesive tape is used to remove particles from the test surface for manual counting, then particles of approximately five microns or larger can be detected, but the process is very time consuming and highly sensitive to variability between operators
Solution Approach 1:
The patent replaces the manual tape removal and microscope counting process with an automated device that uses optical lasers and condensation particle counters. The system automatically collects, detects, and counts particles without human intervention, eliminating operator variability and dramatically increasing inspection speed while maintaining or improving detection capability.
Solution Approach 2:
The device performs the entire particle detection process autonomously - collecting particles from the surface, transporting them through the detection chamber, counting them with sensors, and providing results. The system serves itself without requiring manual particle removal or operator interpretation, making the process both faster and more consistent.
3Measurement precision
If optical laser technology is used in the particle counter, then particles can be detected with improved sensitivity, but the detection is still limited to particles of 300 nm or larger
Solution Approach 1:
The patent employs condensation particle counting that utilizes phase transition of a condensable vapor (such as alcohol or water) onto particle surfaces. This phase change amplifies the optical signal from sub-300 nm particles by forming visible condensation shells around them, making particles as small as 10 nm detectable through their enhanced light scattering or absorption characteristics.
Solution Approach 2:
The invention changes the detection mechanism from direct optical scattering by particles to optical detection of condensation shells formed on particles. This parameter change in the detection method allows much smaller particles to produce detectable signals, extending the lower detection limit from 300 nm to 10 nm while maintaining quantitative measurement capability.
4Device complexity
If a single airstream is used to transport particles from the sample surface, then the device structure is simple, but particle ejection occurs and detection accuracy is reduced
Solution Approach 1:
The patent divides the single airstream into multiple separate airstreams - typically a sample airstream that collects particles from the surface and a reference airstream that does not contact the surface. This segmentation allows the system to compare particle counts between streams, compensate for background particles, and eliminate false positives from particle ejection, thereby improving measurement accuracy.
Solution Approach 2:
The invention introduces a reference airstream as an intermediary that carries ambient air through the same detection chamber without contacting the sample surface. This reference stream serves as a control to distinguish actual surface particles from background contamination and ejected particles, enabling accurate subtraction of false signals and improving overall measurement precision.
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 detection of particles down to 10 nm, improving surface particle data sensitivity to 10 nm and above, providing quantitative data and increasing particle detection efficiency by minimizing ejection and maximizing the capture of particles, thus meeting the stringent contamination standards of advanced technology industries.
Implementation Method 1
improving surface particle data sensitivity to 10 nm and above
Implementation Method 2
low resolution optical detector to detect larger particles
Implementation Method 3
an air flow modulator to enhance particle dislodgement and reduce ejection
Data Source
AI summary
A particle counting device includes a scanner probe having a first opening for receiving particles from a sample surface and second openings. Pumps produce a first airstream flowing from the first opening and a second airstream flowing to the second openings. A flow device splits the first airstream into third and fourth airstreams. A first particle detector detects particles in the third airstream. The first particle detector is capable of detecting particles within a first range of particle sizes. A second particle detector detects particles in the fourth airstream. The second particle detector is capable of detecting particles within a second range of particle sizes different from the first range of particle sizes. Control circuitry controls the flow device and the pumps to provide a first flow rate of the third airstream and a second flow rate of the fourth airstream that is larger than the first flow rate.