Phased Array Antennas for Plasma Edge Uniformity Control
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Solution Overview
Problem
Existing plasma reactors experience non-uniformity in processing semiconductor wafers due to plasma sheath bending at the edge, caused by erosion of components, leading to continuous tilt drift over time.
Innovation Solution
Implementing phased array antennas with controlled HF power beams to adjust plasma uniformity by steering energy towards specific areas within the plasma chamber, using a Butler matrix and electronic controllers to manage phase shifts and power levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional RF signal supply methods are used in plasma reactors, then the system structure is simple, but plasma uniformity deteriorates due to sheath bending at the edge
Solution Approach 1:
The plasma reactor's RF power delivery system is segmented into multiple independent antenna elements distributed across the chamber. Each antenna element can be independently controlled to deliver RF power to specific regions, allowing localized plasma uniformity correction without requiring complete system redesign.
Solution Approach 2:
Different regions of the plasma chamber receive differentiated RF power through individually controlled antenna elements. The phased array system enables local adjustment of plasma characteristics by steering energy beams to specific areas, applying local quality enhancement where needed while maintaining simplicity in regions that don't require correction.
2Manufacturing precision
If phased array antennas with multiple antenna elements are implemented, then plasma uniformity is improved through localized energy steering, but device complexity increases
Solution Approach 1:
The phased array antenna system serves multiple functions: it provides overall plasma generation, enables localized uniformity correction, and allows dynamic steering of energy beams. This multi-functionality justifies the increased complexity by consolidating several plasma control capabilities into a single integrated system rather than requiring separate systems for each function.
Solution Approach 2:
The antenna system incorporates dynamic phase and amplitude control of RF signals to each antenna element, enabling real-time steering of energy beams and adaptation to changing plasma conditions. This dynamic capability allows the system to maintain optimal plasma uniformity throughout the substrate processing cycle, compensating for the increased complexity through intelligent control.
3Manufacturing precision
If RF power is distributed uniformly across the plasma chamber, then the system operation is simple, but edge region plasma non-uniformity worsens due to sheath bending
Solution Approach 1:
The phased array system pre-calculates and pre-configures the phase and amplitude of RF signals for each antenna element to compensate for anticipated edge region plasma non-uniformity. By applying corrective power distribution patterns before processing begins, the system proactively prevents sheath bending effects rather than reacting to them during operation.
Solution Approach 2:
The system incorporates monitoring and control mechanisms that detect plasma uniformity conditions and adjust the RF power distribution to antenna elements in real-time. This feedback loop enables automatic correction of edge region non-uniformity, reducing the operational complexity burden by making the system self-regulating rather than requiring manual intervention.
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
Enhances plasma uniformity by focusing energy on desired locations, reducing energy dissipation in undesired directions, and correcting for non-uniformity issues in substrate processing.
Implementation Method 1
a radiation pattern output from each of the antenna elements constructively combines with radiation patterns output from neighboring ones of the antenna elements to form an effective radiation pattern called an HF power beam or a main lobe
Implementation Method 2
the phased array antenna destructively interferes with signals that form nulls and side lobes in undesired directions
Implementation Method 3
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
Data Source
AI summary
A system for directing a main beam towards a gap within a plasma chamber is provided. The system includes an edge ring and a plurality of antenna elements coupled to the edge ring. The plurality of antenna elements includes a first antenna element and a second antenna element. The first antenna element receives a radio frequency (RF) signal having a phase and the second antenna element receives a phase-shifted signal. The phase-shifted signal has a phase that is shifted with respect to the phase of the RF signal to output the main beam towards the gap within the plasma chamber.