Plasma Density Measurement Using Microwave Reflection and Optical Sensing
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Solution Overview
Problem
The miniaturization and high integration of semiconductor devices have made fine errors in plasma processes critical, necessitating precise measurement of plasma parameters to ensure quality, but existing methods are inadequate for accurate and reliable plasma density measurement.
Innovation Solution
A device and system that combine a microwave sensor to measure the input port reflection parameter and an optical sensor to measure plasma density through a flat plate probe, allowing for the calculation of absolute and relative plasma density profiles without distorting plasma distributions, enabling real-time monitoring during semiconductor manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single sensor is used to measure plasma density, then the device complexity is reduced, but the measurement precision is insufficient
Solution Approach 1:
The patent combines microwave sensor and optical sensor into a single integrated measurement system. The microwave sensor measures electron density through electromagnetic wave interaction, while the optical sensor measures plasma emission intensity. By merging these two sensing approaches, the system achieves comprehensive plasma density measurement with both absolute value and radial profile information, resolving the contradiction between measurement precision and device complexity.
Solution Approach 2:
The probe structure serves multiple functions: it acts as a microwave antenna for electromagnetic wave transmission and reception, provides a physical barrier to protect the optical sensor from plasma damage, and creates a controlled measurement geometry. This multi-functionality allows the system to achieve high measurement precision without proportionally increasing device complexity.
2Measurement precision
If an invasive probe is inserted into plasma, then direct measurement is achieved, but the plasma distribution is distorted
Solution Approach 1:
The probe structure acts as an intermediary between the measurement system and the plasma. It transmits microwave signals through the plasma without requiring direct contact, and protects the optical sensor from plasma exposure. This intermediary approach enables measurement without invasive insertion, preventing plasma distribution distortion while maintaining measurement capability.
Solution Approach 2:
The patent replaces mechanical insertion of sensors into plasma with electromagnetic wave-based measurement. Microwave signals penetrate the plasma and interact with electrons, allowing density measurement without physical intrusion. This substitution eliminates the distortion caused by invasive probes while maintaining direct measurement capability through field-based sensing.
3Productivity
If real-time monitoring is implemented, then productivity is improved, but the device complexity increases
Solution Approach 1:
The measurement system continuously transmits microwave signals and collects optical emissions during plasma processing operations. This continuous measurement provides real-time plasma density data without interrupting the manufacturing process, improving productivity through immediate feedback while the integrated sensor design keeps complexity manageable.
Solution Approach 2:
The system provides real-time feedback on plasma density conditions during semiconductor manufacturing processes. By continuously monitoring electron density and radial profiles, the system enables process control adjustments to maintain optimal plasma conditions, improving productivity through closed-loop control without requiring overly complex measurement infrastructure.
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
This solution provides a reliable and non-invasive method for measuring plasma density, combining microwave and optical signals to achieve accurate, real-time monitoring of plasma treatment, thereby improving semiconductor device quality by minimizing errors in plasma processes.
Implementation Method 1
a first sensor configured to measure a microwave spectrum of an input port reflection parameter of plasma
Implementation Method 2
a second sensor configured to measure an optical signal generated from the plasma
Data Source
AI summary
A device for measuring a density of plasma is provided. The device includes a first sensor configured to measure a microwave spectrum of an input port reflection parameter of plasma, the first sensor having a probe including a conductive material and a flat plate shape, and a second sensor configured to measure an optical signal generated from the plasma, the second sensor being configured to detect the optical signal through the probe of the first sensor.