RF Sensor Circuit for Plasma Process Control
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Solution Overview
Problem
Plasma processing in semiconductor fabrication faces challenges in achieving precise control of RF signals for advanced IC designs, particularly in sustaining plasma properties at nanometer scales, requiring innovative metrology for accurate and unobtrusive RF signal measurement.
Innovation Solution
A measurement system that includes a sensor circuit with amplifiers for sensing electric and magnetic fields, an analysis circuit with frequency selective demodulation, and analog-to-digital converters to determine the amplitude and phase of RF signals, enabling accurate control of RF power delivery in plasma processing systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If RF power is used to sustain plasma in semiconductor fabrication, then plasma processes can be performed for deposition and patterning, but precise control and measurement of RF signals become challenging due to the complex interaction between RF power and plasma properties
Solution Approach 1:
The patent introduces an RF sensor as an intermediary device that couples to the RF signal path without disrupting plasma generation. The sensor extracts RF signal information (voltage, current, impedance) through electromagnetic coupling, acting as a mediator between the RF power source and the plasma chamber, enabling measurement without direct intrusion into the plasma environment
Solution Approach 2:
The patent replaces traditional physical probe measurements with electromagnetic field-based sensing. Instead of inserting mechanical probes into the plasma chamber, the system uses RF sensors that detect RF signals through electromagnetic coupling, eliminating mechanical intrusion and its associated disruptions to plasma stability
2Manufacturing precision
If feature sizes are scaled down to nanometer dimensions, then component packing density increases, but precise control of plasma process dimensions becomes more difficult
Solution Approach 1:
The patent implements a feedback control system where RF sensor measurements of voltage, current, and impedance are continuously monitored and fed back to adjust RF power delivery. This closed-loop feedback enables precise control of plasma process parameters (etch rate, deposition thickness) even at nanometer feature sizes, compensating for process variations in real-time
Solution Approach 2:
The patent replaces complex mechanical adjustment mechanisms with electronic RF signal control. Instead of physically adjusting plasma chamber components, the system achieves precise dimension control through electronic modulation of RF power parameters, reducing device complexity while improving precision
3Ease of operation
If unobtrusive RF signal measurement is implemented, then plasma process control is improved, but measurement accuracy becomes challenging due to signal complexity and noise
Solution Approach 1:
The patent uses an RF sensor as an intermediary that provides isolated measurement capability. The sensor couples to the RF signal path through electromagnetic fields without direct electrical connection, enabling unobtrusive measurement while maintaining signal integrity and reducing noise interference from the plasma environment
Solution Approach 2:
The patent replaces direct electrical measurement methods with electromagnetic field-based sensing. This substitution enables non-intrusive measurement that avoids ground loops and electrical noise, improving measurement accuracy while maintaining ease of operation in the plasma environment
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 precise and accurate RF measurements across multiple frequencies, allowing for closed-loop control of plasma processes, improving the precision and uniformity of plasma etching and deposition characteristics in semiconductor manufacturing.
Implementation Method 1
an RF sensor configured to sense an electric field and sense a magnetic field of the RF pipe
Data Source
AI summary
In accordance with an embodiment, a measurement system includes a sensor circuit configured to provide a voltage sense signal proportional to an electric field sensed by the RF sensor and a current sense signal proportional to a magnetic field sensed by the RF sensor; an analysis circuit comprising a frequency selective demodulator circuit configured to: demodulate the voltage sense signal into a first set of analog demodulated signals according to a set of demodulation frequencies, demodulate the current sense signal into a second set of analog demodulated signals according to the set of demodulation frequencies, and determine a phase shift between the voltage sense signal and the current sense signal for at least one frequency of the set of demodulation frequencies; and analog-to-digital converters configured to receive the first and second sets of analog demodulated signals.