Spiral RF Coil Gap Control for Uniform Plasma Etching
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Solution Overview
Problem
The uneven distribution of plasma caused by variable gaps between adjacent coil segments of a spiral-shaped RF coil in a plasma processing tool leads to inconsistent etch rates, resulting in incomplete removal of oxide layers and poor electrical contact between deposited metal and underlying layers, potentially causing voltage breakdown.
Innovation Solution
A movable jig is installed in the RF resonator to maintain a fixed gap between adjacent coil segments of the spiral-shaped RF coil, ensuring uniform plasma distribution and consistent etch rates across the wafer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a spiral-shaped RF coil with variable gaps between adjacent coil segments is used, then the device complexity is reduced, but plasma uniformity deteriorates
Solution Approach 1:
The patent makes the coil segments movable rather than fixed, allowing dynamic adjustment of gaps between segments. The coil segments can be positioned at different radial distances from the center of the processing chamber, enabling optimization of plasma uniformity while maintaining a simple spiral overall structure.
Solution Approach 2:
The RF coil is divided into multiple separate coil segments that can be independently positioned and adjusted. This segmentation allows each segment to be optimized for uniform plasma generation while maintaining structural simplicity through the modular design.
2Ease of manufacture
If variable gaps between coil segments are allowed, then ease of manufacture is improved, but etch rate consistency deteriorates
Solution Approach 1:
The coil segments are designed with movable mounting mechanisms that allow adjustment of radial positions. This dynamic positioning capability enables precise control of gap sizes to ensure consistent etch rates across the wafer surface, while the modular design maintains ease of assembly.
Solution Approach 2:
The patent allows changing the radial position parameter of each coil segment independently. By adjusting these parameters, the gap between segments can be optimized to achieve uniform plasma distribution and consistent etch rates, while the segments can be manufactured with standard tolerances.
3Manufacturing precision
If fixed gap between coil segments is maintained, then plasma uniformity is improved, but device complexity increases
Solution Approach 1:
Rather than using a completely rigid fixed-structure coil, the patent employs movable segments with controlled positioning. This dynamic fixed-position approach achieves plasma uniformity through precise but adjustable gap control, avoiding the need for complex rigid structures.
Solution Approach 2:
The coil is segmented into multiple independent units that can be fixed at predetermined positions. This segmentation simplifies the overall structure by allowing each segment to be a simple component, while the collective arrangement achieves the required plasma uniformity.
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 improves plasma uniformity, ensuring complete removal of oxide layers and enhances electrical contact between deposited metal and underlying layers, preventing voltage breakdown.
Implementation Method 1
a radio frequency (RF) coil disposed within a resonator housing... the RF coil allows control of the radial ion distribution and density in the chamber body
Implementation Method 2
The plasma processing tool comprises an enclosure wall that encloses a process zone into which a process gas may be introduced, a gas energizer to energize the process gas
Implementation Method 3
An electrostatic chuck is disposed on top of the pedestal for retaining the wafer thereupon
Data Source
AI summary
The method includes placing a wafer in a chamber body of a plasma processing tool; moving a first movable jig along an arc path to comb a spiral-shaped radio frequency (RF) coil over the chamber body, the first movable jig having a plurality of first confining slots penetrated by a plurality of coil segments of the spiral-shaped RF coil, respectively; and generating plasma in the chamber body through the spiral-shaped RF coil.