QCM Impactor for Sub-10nm Particle Detection Under Vacuum
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Solution Overview
Problem
Current methods struggle to detect low concentrations of aerosol particles below 10 nm in size under vacuum conditions, which is crucial for semiconductor processing to prevent particle contamination and ensure device performance.
Innovation Solution
A quartz crystal microbalance (QCM) impactor is developed, comprising an orifice tube with an orifice nozzle and a QCM sensor, configured to deliver particles towards a detection position on the QCM sensor, allowing for the quantification of particle mass at low mass concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional detection methods (SMPS, ELPI, MOUDI, OPC, AMS) are used, then detection capability is available, but they cannot detect low concentrations of particles below 10 nm under vacuum conditions
Solution Approach 1:
The patent introduces a differential mobility analyzer (DMA) as an intermediary device that operates at atmospheric pressure to pre-separate particles by size before they enter the vacuum environment. This mediator allows particles to be conditioned in a compatible environment before detection, enabling the QCM to detect sub-10nm particles under vacuum that would otherwise be undetectable by conventional methods
2Measurement precision
If particle detection sensitivity is increased to detect sub-10nm particles, then measurement precision improves, but device complexity increases
Solution Approach 1:
The patent extracts the complex particle separation function into a standalone differential mobility analyzer (DMA) module that operates independently at atmospheric pressure. This separates the detection function (QCM at vacuum) from the separation function (DMA at atmospheric pressure), allowing each component to be optimized independently and reducing overall system complexity while maintaining high detection sensitivity
3Object-affected harmful factors
If particle removal techniques (increasing flowrate, thermophoresis, plasma pulsing, hydrogen dilution) are applied, then particle formation is suppressed, but processing speed and precursor yield are limited
Solution Approach 1:
The patent replaces mechanical particle removal methods (increasing flowrate, thermophoresis) with a detection-based approach using QCM. By substituting the mechanical suppression system with a sensitive detection system, the patent enables monitoring of particle formation without necessarily requiring aggressive particle removal, thus maintaining processing speed while controlling contamination
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
The QCM impactor effectively detects and quantifies low concentrations of aerosol particles below 10 nm, providing high mass resolution and sensitivity, and is particularly beneficial for monitoring dust contamination in microelectronic processing reactors.
Implementation Method 1
a quartz crystal microbalance (QCM) impactor... a QCM sensor... quantifying a mass of the particles in the process gas
Implementation Method 2
flowing a process gas comprising particles through the orifice tube and the orifice nozzle, delivering the process gas comprising particles from the orifice nozzle to the QCM sensor
Data Source
AI summary
The present disclosure is directed to a quartz crystal microbalance (QCM) impactor and method of using same. The QCM impactor is particularly useful for detecting particles at low mass concentrations, such as for semiconductor process monitoring applications.