Ring Electrode Plasma Confinement for Bevel Etch Control
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Solution Overview
Problem
Plasma non-uniformity during semiconductor substrate processing leads to higher etch rates at the edge of the substrate, resulting in substrate non-uniformity and waste, as existing technologies fail to effectively manage plasma confinement, especially for large substrates, causing defective devices and revenue loss.
Innovation Solution
The use of a power source, gas distribution system, and match arrangements to control RF current flow through top and bottom ring electrodes, allowing for precise manipulation of plasma formation near the substrate edges, thereby controlling the etch rate without replacing ceramic process kits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If plasma processing is performed on large substrates using conventional methods, then the bulk area can be processed with acceptable plasma uniformity, but the edge areas experience non-uniform plasma distribution and higher etch rates resulting in defective devices
Solution Approach 1:
The patent divides the substrate processing into distinct regions by introducing ring electrodes that create separate plasma zones. The ring electrodes segment the plasma distribution pattern, allowing independent control of plasma density in different radial zones of the substrate, thereby addressing the non-uniformity issue at edges while maintaining uniformity in the bulk area.
Solution Approach 2:
The patent applies local quality by using ring electrodes to create region-specific plasma characteristics. Different radial positions on the substrate receive tailored plasma conditions through the ring electrode structure, enabling edge areas to achieve uniform plasma distribution similar to the bulk area, thus allowing the entire substrate including edges to be processed with consistent quality.
2Productivity
If the entire substrate including edge areas is utilized for device fabrication, then substrate yield increases, but plasma non-uniformity at edges causes higher defect rates
Solution Approach 1:
The ring electrode structure segments the plasma generation zones, creating controlled plasma regions that extend uniformly to the substrate edges. This segmentation allows the entire substrate surface to be utilized for device fabrication while maintaining consistent plasma conditions across all areas, thereby improving substrate yield without compromising device quality.
Solution Approach 2:
The patent changes the plasma generation parameters by introducing ring electrodes that modify the electric field distribution and plasma density profile. This parameter change enables uniform plasma conditions across the entire substrate including edges, allowing full substrate utilization while maintaining high device quality and low defect rates.
3Ease of manufacture
If conventional plasma processing is used without edge control, then processing is simpler, but plasma non-uniformity leads to wasted substrate areas and revenue loss
Solution Approach 1:
The ring electrode configuration provides a relatively simple segmented structure that can be integrated into existing plasma processing systems. This segmentation approach enables uniform plasma distribution across the entire substrate with minimal additional complexity, thereby reducing substrate waste without significantly increasing manufacturing 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 approach enables uniform plasma distribution across the substrate, reducing waste and increasing yield by allowing for consistent etch rates across the entire substrate surface, including the edges, thus minimizing defective semiconductor devices and optimizing substrate utilization.
Implementation Method 1
a gas mixture (e.g., etchant gas mixture) may flow into a processing chamber and be energized by radio frequency (RF) power to form an ion energy cloud (i.e., plasma)
Implementation Method 2
Plasma may then be employed to etch the substrate to form semiconductor devices
Data Source
AI summary
Methods for controlling bevel etch rate of a substrate during plasma processing within a processing chamber includes securing the substrate on a lower electrode within the processing chamber. A power source is provided. A gas mixture is flowed into the processing chamber. A first match arrangement coupled to an upper electrode is adjusted to control current flowing through the upper electrode to change the upper electrode from a grounded state to a floating state. A second match arrangement coupled to a top ring electrode is adjusted to control current flowing through the top ring electrode so as to control plasma formed above a top edge of the substrate. An extension of the upper electrode is lowered during plasma processing so as to minimize a gap between the extension of the upper electrode and the substrate received on the lower electrode, such that the gap is incapable of supporting plasma formed in the processing chamber.