Plasma Health Determination in Semiconductor Reactors
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Solution Overview
Problem
Existing semiconductor etch processes face challenges in determining the health of remote and local plasmas, leading to inefficiencies and potential damage to patterned substrates due to out-of-tune plasma conditions, which conventional methods struggle to detect effectively.
Innovation Solution
The method involves monitoring the power difference between the power delivered and received in a substrate processing chamber using a V/I sensor, calculating a dimensionless ratio of reflected power, and comparing frequency-based voltage spectra to determine if the plasma is out-of-tune, allowing for timely termination of the process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional plasma monitoring methods are used, then the system operates with existing detection capabilities, but the ability to detect out-of-tune plasma conditions is insufficient leading to substrate damage
Solution Approach 1:
The system continuously monitors plasma conditions by measuring reflected power and comparing it to expected values, providing real-time feedback on plasma health. When the reflected power indicates an out-of-tune condition (exceeding threshold ratios), the system automatically terminates the process to prevent substrate damage, creating a closed-loop control system that actively responds to plasma state changes.
Solution Approach 2:
The patent replaces conventional mechanical or direct sensing methods with electromagnetic field-based detection using V/I sensors that measure voltage and current waveforms. This substitution enables non-intrusive monitoring of plasma conditions through electrical parameter analysis, specifically detecting plasma health through reflected power measurements and frequency spectrum analysis without direct mechanical contact with the plasma.
2Measurement precision
If the plasma process is monitored continuously with traditional methods, then some plasma conditions can be detected, but the detection range is limited to reflected power between 20% and 80%
Solution Approach 1:
The system detects plasma conditions by monitoring changes in electrical parameters (voltage, current, reflected power, frequency) rather than relying on a single parameter. By analyzing the ratio of reflected power to delivered power and examining frequency spectrum characteristics, the system can detect out-of-tune conditions across a broader reflected power range (10%-90%), adapting to various plasma states beyond traditional detection limits.
3Productivity
If the plasma process continues despite out-of-tune conditions, then processing time is maintained, but substrate damage occurs and productivity is reduced due to rework
Solution Approach 1:
The system performs preliminary detection of plasma health conditions before significant substrate damage can occur. By continuously monitoring reflected power ratios and frequency spectra, the system identifies out-of-tune conditions early in the process and terminates them proactively, preventing the need for rework and maintaining both productivity and process quality.
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 early detection and termination of out-of-tune plasma processes, preventing substrate damage and optimizing processing time by determining the health of plasmas with reflected power between 10% and 90%, expanding the detection range beyond conventional limits.
Implementation Method 1
The power received may be determined by a V/I sensor positioned after the matching circuit and calculated by VRF×IRF×cos(ΦRF)
Implementation Method 2
turning on an RF power from an RF power supply disposed outside the region... delivering the RF power to region to excite an RF plasma within the region
Implementation Method 3
calculating a power difference between the RF power and the power delivered to the RF plasma... determining the health of plasmas with reflected power between 10% and 90%
Data Source
AI summary
Methods of monitoring a plasma while processing a semiconductor substrate are described. In embodiments, the methods include determining the difference in power between the power delivered from the plasma power supply and the power received by the plasma in a substrate processing chamber. The power received may be determined using a V/I sensor positioned after the matching circuit. The power reflected or the power lost is the difference between the delivered power and the received power. The process may be terminated by removing the delivered power if the reflected power is above a setpoint. The VRF may further be fourier transformed into frequency space and compared to the stored fourier transform of a healthy plasma process. Missing frequencies from the VRF fourier transform may independently or further indicate an out-of-tune plasma process and the process may be terminated.