RF Plasma Power Feedback Control for Wafer Processing
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Solution Overview
Problem
Conventional plasma processing in semiconductor manufacturing lacks real-time monitoring and control of deposition rates and power output across multiple chambers, leading to variability and instability in plasma conditions.
Innovation Solution
An apparatus and method that includes a detector to monitor the root-mean-square current to the plasma electrode, converting the signal into a controlled signal, and a controller to adjust the RF power output based on deviations from a set point, ensuring precise power management in real-time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional power supplies are used for plasma electrodes, then the system is simple to operate, but the power output drifts and cannot be adjusted in real-time
Solution Approach 1:
The patent implements a feedback control system where a detector monitors the actual RF power delivered to the plasma electrode, converts the oscillating signal to a controlled signal, and feeds it back to a controller that adjusts the power supply output. This closed-loop feedback mechanism eliminates power drift and enables real-time power adjustment, directly resolving the contradiction between power control capability and stability.
2Productivity
If multiple deposition chambers are used, then productivity increases, but deposition rates and qualities vary among chambers
Solution Approach 1:
The feedback control system enables independent real-time monitoring and adjustment of RF power for each deposition chamber. By continuously measuring actual power delivery and adjusting accordingly, each chamber can maintain consistent deposition rates and quality regardless of plasma instability or power supply drift, thus resolving the contradiction between increased productivity through multiple chambers and maintaining manufacturing precision.
3Reliability
If real-time monitoring is implemented, then plasma condition consistency improves, but device complexity increases
Solution Approach 1:
The patent employs a relatively simple feedback mechanism using a detector, signal generator, and controller to achieve real-time plasma power monitoring and control. This straightforward implementation minimizes added complexity while effectively maintaining plasma condition consistency, resolving the contradiction between improved reliability and increased device complexity.
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 enables real-time monitoring and control of deposition rates, maintaining consistent plasma conditions across multiple chambers, reducing variability and instability, and improving the quality and consistency of semiconductor manufacturing processes.
Implementation Method 1
a detector coupled to a power delivery conduit, wherein the power delivery conduit is configured to deliver RF power from a power supply to an electrode for generating the plasma
Implementation Method 2
a signal generator configured to convert an oscillating electrical signal from the detector into a controlled signal
Implementation Method 3
a controller configured to control the power supply based on the controlled signal
Implementation Method 4
an inductive coil may be disposed around a torroidal permanent magnet, which is itself disposed around the tube, to generate an inductively-coupled electric field inside the tube
Data Source
AI summary
A method and apparatus for controlling power output of a capacitatively-coupled plasma are provided. A detector is disposed on the power delivery conduit carrying power to one electrode to detect fluctuations in power output to the electrode. The detector is coupled to a signal generator, which converts the RF input signal to a constant control signal. A controller adjusts power input to the RF generator by comparing the control signal to a reference.