Plasma Control Apparatus for Edge Electrode Boundary Tuning
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Solution Overview
Problem
In plasma processing systems, particularly in high aspect ratio contact (HARC) etch facilities, the non-uniformity of plasma distribution due to harmonic components and intermodulation distortion frequency components generated by plasma nonlinearity affects process performance, leading to inconsistent results.
Innovation Solution
A plasma control apparatus is introduced, featuring a plasma electrode, an edge electrode, and a plasma control circuit that adjusts the electrical boundary conditions in the plasma edge boundary region to control standing waves, using RF power and sensors to manage fundamental frequency, harmonic, and intermodulation distortion components, thereby improving plasma uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high frequency RF power is applied to generate sufficient plasma density in HARC etch facilities, then plasma density is improved, but harmonic components and intermodulation distortion frequency components are generated due to plasma nonlinearity, causing non-uniform plasma distribution
Solution Approach 1:
The invention changes the electrical boundary condition parameter in the plasma edge boundary region to control the standing wave pattern. By adjusting the electrical boundary condition (e.g., through a tunable impedance element or variable capacitor), the standing wave characteristics are modified to achieve more uniform plasma distribution while maintaining high plasma density generated by high frequency RF power
Solution Approach 2:
The invention uses a sensor to detect the actual plasma distribution or electrical boundary condition, and a controller adjusts the electrical boundary condition based on the detected information. This closed-loop feedback system enables dynamic control of the standing wave to compensate for non-uniformities caused by harmonic and intermodulation distortion components
2Productivity
If high frequency RF power is used to generate sufficient plasma density, then etch process capability is improved, but standing waves in the plasma chamber cause non-uniform plasma distribution
Solution Approach 1:
The invention modifies the electrical boundary condition parameter in the plasma edge region to alter the standing wave pattern. By changing this boundary condition (through impedance tuning or capacitive adjustment), the standing wave distribution is optimized to reduce non-uniformities while preserving the high frequency RF power necessary for etch process capability
Solution Approach 2:
The invention applies local control by specifically targeting the electrical boundary condition in the plasma edge boundary region. This localized adjustment allows modification of the standing wave pattern in critical areas without affecting the overall high frequency RF power input, thereby improving plasma uniformity while maintaining etch process capability
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 solution effectively controls plasma distribution across the entire wafer area, enhancing etch rate uniformity and improving process performance by adjusting electrical boundary conditions and standing wave patterns in the plasma chamber.
Implementation Method 1
the plasma control circuit being configured to change the electrical boundary condition to control a standing wave in the plasma chamber
Implementation Method 2
a plasma power supply configured to apply radio frequency (RF) power having a fundamental frequency to the plasma electrode to generate plasma
Data Source
AI summary
Provided is a plasma control apparatus including a plasma electrode disposed in a plasma chamber and to which radio frequency (RF) power having a fundamental frequency configured to generate plasma is applied, an edge electrode disposed adjacent to the plasma electrode and corresponding to a plasma edge region, and a plasma control circuit electrically connected to the edge electrode, the plasma control circuit being configured to control an electrical boundary condition in a plasma edge boundary region of a first frequency component, a harmonic wave component generated by nonlinearity of the plasma and intermodulation distortion frequency components generated by a frequency component in the plasma chamber and each of the first frequency component and the harmonic wave component, wherein the plasma control circuit is configured to change the electrical boundary condition to control a standing wave in the plasma chamber.