Azimuthal RF Plasma Sensing for Real-Time Uniformity Detection
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Solution Overview
Problem
Current RF plasma processing systems face challenges in controlling plasma density uniformity within reaction chambers, leading to non-uniform etch rates and yield issues in semiconductor manufacturing, as existing monitoring techniques are not sensitive or fast enough to detect deviations in plasma density in real-time.
Innovation Solution
The implementation of high-bandwidth sensors mounted on various components of the RF plasma processing system, including electrodes and pedestals, to detect and analyze RF surface waves, allowing for rapid determination of plasma density uniformity by measuring amplitudes and phases of fundamental and harmonic frequencies, enabling prompt adjustments to maintain optimal processing conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If probes with coatings and active electronics are used to monitor plasma density, then plasma density uniformity can be monitored, but the response time is slow (milliseconds or more) and the system is complex
Solution Approach 1:
The patent replaces mechanical/electronic probes with optical emission spectroscopy to detect plasma density. The system uses optical sensors to measure emission intensity at specific wavelengths, converting a mechanical measurement problem into an optical one. This substitution enables faster response times while maintaining measurement capability.
Solution Approach 2:
The patent introduces optical emission spectroscopy as an intermediary method between the plasma and the detection system. Instead of directly measuring plasma properties with slow probes, the system uses light emission as an intermediate signal that can be rapidly detected and analyzed to infer plasma density uniformity.
2Measurement precision
If emission spectroscopy is used to determine plasma density profile, then plasma density can be measured, but multiple lines of sight are required and analysis is complicated
Solution Approach 1:
The patent extracts the essential diagnostic information by focusing on emission intensity at specific characteristic wavelengths rather than requiring complete spectral analysis. This extraction approach simplifies the measurement system by identifying only the critical wavelength regions needed to determine plasma density, eliminating the need for complex multi-wavelength analysis.
3Productivity
If traditional monitoring techniques are used, then plasma processing can proceed, but non-uniformity issues cannot be detected quickly enough to prevent yield loss
Solution Approach 1:
The patent implements a feedback mechanism where optical emission spectroscopy continuously monitors plasma density uniformity in real-time. The system uses this feedback information to detect non-uniformity conditions promptly, enabling rapid response while maintaining high productivity. The feedback loop connects measurement to process control without significant time delay.
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 approach enables real-time monitoring and correction of plasma density uniformity, preventing irreversible deviations in wafer processing and improving the yield of integrated circuits by rapidly identifying and addressing plasma faults, thus ensuring uniformity and consistency in semiconductor fabrication.
Implementation Method 1
detect and analyze RF surface waves, allowing for rapid determination of plasma density uniformity by measuring amplitudes and phases of fundamental and harmonic frequencies
Data Source
AI summary
A method of detecting non-uniformity in a plasma in a radio frequency plasma processing system, the method including generating a plasma within a reaction chamber of the radio frequency plasma processing system and detecting electrical signals from the plasma in a frequency range from a frequency of radio frequency power sustaining the plasma to a multiple of about ten times a frequency with a plurality of sensors disposed azimuthally about a chamber symmetry axis of the radio frequency plasma processing system. The method also including comparing the waveforms of the electrical signals picked up from the plasma by the plurality of sensors and determining when a plasma non-uniformity occurs based on the comparing the electrical property of the plasma detected by each of the plurality of sensors.