RF Electrode Phase Control for Better Plasma Etch Profiles
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Solution Overview
Problem
Current systems for determining phase differences between radio frequency (RF) signals in plasma reactors lack efficiency in optimizing the etch process, leading to suboptimal etch profiles and rates for semiconductor wafers.
Innovation Solution
A method and system that determine the phase difference between RF signals provided to electrodes by analyzing parameter and variable signals from sensors, allowing for synchronization of RF signals to maximize secondary electron flux and improve etch processing rates and profiles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If RF signals are supplied to plasma reactor electrodes, then etching of semiconductor wafer features occurs, but side wall etching happens reducing feature depth
Solution Approach 1:
The system dynamically adjusts the phase difference between RF signals supplied to upper and lower electrodes based on real-time measurement of secondary electron flux. By continuously optimizing the phase relationship, the system adapts electron acceleration timing to maximize vertical etching while minimizing side wall etching, thus improving etch profile precision without sacrificing etch rate
Solution Approach 2:
The invention changes the phase difference parameter between RF signals as a control variable to optimize electron flux characteristics. By adjusting this phase parameter, the system controls the timing of electron acceleration events, creating optimal conditions for vertical feature etching while suppressing lateral etching, thereby resolving the contradiction between etch profile quality and etch rate
2Productivity
If phase difference between RF signals is optimized, then secondary electron flux increases improving etch rate, but system complexity increases due to additional sensors and control
Solution Approach 1:
The system employs feedback control by measuring secondary electron flux with a sensor and using this information to adjust the phase difference between RF signals. This closed-loop approach automatically optimizes etch rate without requiring complex manual tuning or multiple sensors, as the single electron flux measurement directly guides the phase adjustment to maximize productivity
Solution Approach 2:
The system performs self-optimization by using the measured secondary electron flux to automatically determine the optimal phase difference. The control system serves itself by converting the electron flux measurement directly into phase adjustment commands, eliminating the need for external intervention or complex control algorithms, thus achieving high etch rate with minimal added 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
The method enhances the etch rate and profile by accelerating secondary electrons, reducing side wall etching and increasing feature depth, thereby improving the processing efficiency of semiconductor wafers.
Implementation Method 1
One or more radiofrequency (RF) generators generate one or more RF signals and supply the RF signals to a plasma reactor. The plasma reactor has a semiconductor wafer that is etched when the one or more RF signals are supplied and an etchant gas is supplied to the plasma reactor.
Implementation Method 2
determining, based on the variable signal, a second time at which a first amount of flux of secondary electrons from the upper electrode to the substrate support is maximum
Data Source
AI summary
A method for increasing a rate of processing a substrate to achieve an etch profile of the substrate is described. The method includes receiving a parameter signal from a first sensor when a first radio frequency (RF) signal is provided to a substrate support and a second RF signal is provided to an upper electrode. The method further includes determining, based on the parameter signal, a first time at which a value of a parameter is maximum. The method also includes receiving a variable signal from a second sensor. The method includes determining, based on the variable signal, a second time at which a first amount of flux of secondary electrons from the upper electrode to the substrate support is maximum. The method includes determining a phase difference to be a difference between the first time and the second time and achieving the phase difference.