Grooved Focus Ring Structure for Uniform Plasma Etching
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Solution Overview
Problem
Plasma etching devices face challenges in achieving uniform etching across the entire substrate surface due to difficulty in controlling plasma distribution, particularly at the edges, leading to non-uniform etch rates.
Innovation Solution
A focus ring with a groove portion on its outer circumference is designed to enhance plasma distribution and improve etching uniformity by stabilizing the focus ring's fixation to the electrostatic chuck, utilizing specific volume and thickness ratios, and materials like silicon carbide or boron carbide for enhanced durability and electrostatic attraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high-frequency power is applied above and below the electrostatic chuck to generate plasma, then plasma control in the central region is improved, but plasma distribution in the outer portion deteriorates
Solution Approach 1:
The focus ring introduces localized structural variation (groove portions with different depths) to different regions of the electrostatic chuck. The groove portions create local differences in plasma generation characteristics, allowing the outer regions to generate sufficient plasma while maintaining central region control, thereby achieving uniform etch rate across the entire substrate surface.
2Ease of manufacture
If the focus ring structure is simplified for ease of manufacture, then manufacturing cost is reduced, but fixation stability to the electrostatic chuck deteriorates
Solution Approach 1:
The focus ring is segmented into multiple groove portions (first, second, third groove portions) with different depths arranged in specific patterns. This segmentation allows the structure to be manufactured using standard techniques while the varied groove depths create different plasma generation zones that enhance fixation stability through improved plasma distribution and electrostatic field uniformity.
3Manufacturing precision
If groove depth is increased to improve plasma distribution, then etching uniformity is improved, but structural strength of the focus ring deteriorates
Solution Approach 1:
Different groove portions have different depths (first groove portion with greater depth, second and third groove portions with lesser depths) to create localized plasma generation variations. This local quality variation achieves improved etching uniformity while the shallower second and third groove portions maintain the structural strength of the focus ring, preventing excessive material removal that would compromise integrity.
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 focus ring ensures stable fixation and improved plasma control, resulting in uniform etching of the substrate surface and increased durability, reducing the need for frequent replacements.
Implementation Method 1
A plasma etching process may be performed by converting a gas introduced into the chamber into plasma using high-frequency power applied between the electrodes and etching a substrate mounted on the electrostatic chuck using the plasma.
Implementation Method 2
utilizing specific volume and thickness ratios, and materials like silicon carbide or boron carbide for enhanced durability and electrostatic attraction
Data Source
AI summary
A focus ring for mounting an etching target in a plasma etching device, includes a seating portion, including a seating surface configured to accommodate the etching target; and a main body, formed on an outer circumference of the seating portion, comprising a groove portion having a groove disposed in an upper surface of the main body. A height of an upper surface of the groove portion is lower than a maximum height of the upper surface of the main body.