Multi-Frequency Plasma Power Supply for Uniform Ion Control
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Solution Overview
Problem
Current semiconductor manufacturing processes face challenges in achieving plasma uniformity and independent control of ion flux and ion energy, particularly with increasing driving frequency and chamber size, leading to standing wave effects and inhomogeneous etching and deposition.
Innovation Solution
A power supply system comprising a signal generator and signal processing circuits that generate and process signals at different frequencies, applied to electrodes to improve plasma uniformity and reduce coupling effects between high-frequency and low-frequency power supplies, allowing for independent control of ion flux and ion energy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the driving frequency is increased to improve plasma density and processing efficiency, then the plasma density increases and etching/deposition efficiency improves, but the sheath voltage decreases resulting in reduced ion bombardment energy, and standing wave effects become significant causing plasma inhomogeneity
Solution Approach 1:
The power supply signal is segmented into multiple frequency components (fundamental frequency and harmonic frequencies) that are applied separately through independent signal processing circuits. This allows each frequency component to be optimized independently to address different aspects of plasma control, thereby resolving the contradiction between maintaining plasma uniformity and achieving high processing efficiency at high driving frequencies
Solution Approach 2:
The patent changes the electrical parameters by introducing multiple frequency components with different amplitudes and phases. By adjusting the amplitude ratio and phase difference between the fundamental frequency and harmonic frequency signals, the system can independently control ion flux and ion energy while maintaining plasma uniformity, thus resolving the contradiction between productivity and reliability
2Area of stationary object
If the chamber size is increased to accommodate larger wafers, then the processing capacity increases, but the standing wave effect becomes more significant causing serious spatial plasma inhomogeneity
Solution Approach 1:
By introducing harmonic frequency components and adjusting their amplitude ratios and phase differences, the patent modifies the electrical parameters to counteract the standing wave effects that become more pronounced in larger chambers. This allows plasma uniformity to be maintained across larger chamber sizes, enabling increased processing capacity without sacrificing plasma quality
3Reliability
If a Gaussian lens-shaped electrode is used to compensate standing wave effect at a specific frequency, then plasma uniformity improves at that frequency, but the electrode becomes unsuitable when discharge conditions change and cannot adapt to different frequencies
Solution Approach 1:
Instead of using a fixed geometric electrode shape optimized for one frequency, the patent employs dynamic signal processing that can adjust the amplitude and phase of multiple frequency components in real-time. This dynamic approach allows the system to maintain plasma uniformity across varying discharge conditions and frequencies without requiring physical electrode modifications
Solution Approach 2:
The signal processing system is designed to be universal and multi-functional, capable of generating and controlling multiple frequency components simultaneously. This universal approach replaces the frequency-specific Gaussian lens electrode, providing plasma uniformity control that adapts to different operating conditions and frequencies
4Reliability
If a ladder-shaped electrode with multiple voltage applications is used to avoid high voltage at discharge center, then standing wave effect is reduced, but the manufacturing cost, processing precision requirements, and device complexity increase significantly
Solution Approach 1:
The patent replaces the complex mechanical ladder-shaped electrode structure with an electrical solution involving signal processing circuits that generate multiple frequency components. This substitution eliminates the need for complex electrode geometries while achieving the same goal of reducing standing wave effects and improving plasma uniformity
Solution Approach 2:
Instead of changing the physical structure of the electrode, the patent changes the electrical parameters by introducing harmonic frequency components with specific amplitude ratios and phase differences. This parameter-based approach achieves plasma uniformity control without the manufacturing complexity and high precision requirements of structured electrodes
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 system enhances plasma discharge stability, improves plasma uniformity, and enables flexible control of ion flux and ion energy, optimizing etching and film deposition processes without the need for complex or costly electrode structures.
Implementation Method 1
a signal generator, respectively connected with the plurality of signal processing circuits, is used for generating a plurality of initial signals at different frequencies
Implementation Method 2
the initial signals, after being processed through signal processing circuits, act on the plasma through the first electrode
Implementation Method 3
the capacitively coupled plasma (CCP) source is composed of a pair of plate electrodes in parallel with each other
Data Source
AI summary
The present disclosure relates to a power supply system for improving plasma uniformity and a method thereof, wherein the power supply system includes a signal generating device, a first electrode and a second electrode. The signal generator is respectively connected with a plurality of signal processing circuits and is used for generating a plurality of initial signals at different frequencies; the signal processing circuits are used for processing the initial signals at corresponding frequencies; the plurality of signal processing circuits are all connected with the first electrode; and the initial signals are processed by the signal processing circuits and then act on the plasma through the first electrode. The present disclosure may effectively process signals in different power supplies, improve the stability of plasma discharge, reduce the impact of the coupling effect between different power supplies, and realize the independent control of ion flux and ion energy.