Edge Gas Injection for Semiconductor Etch Uniformity
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Solution Overview
Problem
Conventional semiconductor substrate etching methods face challenges in achieving uniform critical dimension across larger wafers due to non-uniform silicon byproduct distribution, leading to variations in feature dimensions near the center and edge of the wafer.
Innovation Solution
The method involves supporting a semiconductor substrate in a plasma etch chamber and supplying a first etch gas to the central region and a second silicon-containing gas to the peripheral region, with a higher silicon concentration, to generate plasma and etch the substrate, thereby controlling the silicon byproduct distribution and achieving uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional single-gas etching is used for large wafers, then etching can be performed across the substrate, but critical dimension uniformity deteriorates due to non-uniform silicon byproduct distribution
Solution Approach 1:
The patent applies local quality by dividing the gas supply into two distinct zones: a first gas supplied to the central region and a second silicon-containing gas supplied to the peripheral region. This spatial differentiation of gas composition addresses the non-uniform silicon byproduct distribution by providing region-specific chemistry tailored to the local etching requirements, thereby improving critical dimension uniformity across the wafer surface.
Solution Approach 2:
The etching process is segmented into two separate gas supply systems: one for the central region and another for the peripheral region. This segmentation allows independent control of gas flow and composition in different areas, enabling precise management of silicon byproduct distribution and resolving the uniformity issue that plagues conventional single-gas approaches.
2Productivity
If wafer size is increased to improve productivity, then more devices can be manufactured per batch, but critical dimension uniformity deteriorates due to enhanced non-uniformity across the larger substrate area
Solution Approach 1:
By implementing region-specific gas supply (first gas for center, second silicon-containing gas for periphery), the system maintains uniform etching characteristics across the entire large wafer surface. This local quality approach ensures that each region receives the appropriate gas composition to achieve consistent critical dimensions, thereby enabling large wafer processing without sacrificing precision.
Solution Approach 2:
The patent changes the gas composition parameter spatially across the wafer surface. By varying the silicon content in the etch gas between central and peripheral regions, the system compensates for the increased non-uniformity inherent in large wafer processing, maintaining consistent etching performance and critical dimension uniformity across the expanded substrate area.
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 ensures that features etched near the center of the substrate are substantially uniform with those closer to the edge, reducing non-uniformity to less than 1.5 nm 3σ for 300 mm wafers, improving the critical dimension uniformity and electronic characteristics of integrated circuits.
Implementation Method 1
generating plasma from the first etch gas and second gas
Data Source
AI summary
A method of etching a semiconductor substrate with improved critical dimension uniformity comprises supporting a semiconductor substrate on a substrate support in an inductively coupled plasma etch chamber; supplying a first etch gas to a central region over the semiconductor substrate; supplying a second gas comprising at least one silicon containing gas to a peripheral region over the semiconductor substrate surrounding the central region, wherein a concentration of silicon in the second gas is greater than a concentration of silicon in the first etch gas; generating plasma from the first etch gas and second gas; and plasma etching an exposed surface of the semiconductor substrate.