Ring-Shaped Upper Electrode for Uniform Plasma Density
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Solution Overview
Problem
In semiconductor manufacturing, the formation of high aspect ratio structures requires precise control of plasma density to avoid defects, but existing upper electrodes lead to non-uniform plasma distribution, causing etching irregularities and defects in high aspect ratio structures.
Innovation Solution
An upper electrode design with a ring-shaped protrusion portion and a recessed second portion surrounding the first, optimizing the plasma distribution by controlling the radial gradient and minimizing edge peaks, ensuring uniform plasma treatment across the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional upper electrode with a flat bottom surface is used, then the structure is simple and easy to manufacture, but the plasma density distribution becomes non-uniform, causing etching irregularities and defects
Solution Approach 1:
The upper electrode bottom surface is designed with different local geometries: a first protrusion portion with a ring-shaped apex positioned at a first distance from the center axis, and a second protrusion portion with an apex positioned at a second distance from the center axis. These localized structural variations create corresponding plasma density enhancements at specific radial positions, achieving uniform overall plasma distribution by compensating for edge peaks and center dips through targeted local modifications rather than uniform changes across the entire electrode surface.
2Reliability
If the upper electrode has a protrusion portion with apex distance greater than substrate radius, then plasma uniformity is improved, but the electrode design becomes more complex
Solution Approach 1:
The invention optimizes specific geometric parameters of the upper electrode: the first distance (radial position of first protrusion apex) is set greater than the substrate radius, the second distance (radial position of second protrusion apex) is set within a specific range (0.3 to 0.7 times the substrate radius), and the heights of the protrusion portions are controlled within specific ranges. By precisely controlling these parameters, the plasma density distribution is optimized to enhance reliability of plasma treatment while keeping the structural complexity manageable through systematic parameter optimization rather than arbitrary design changes.
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 design enhances the uniformity of plasma distribution, reducing etching irregularities and improving the reliability and yield of semiconductor devices by minimizing radial variations in plasma density, thus reducing defects in high aspect ratio structures.
Implementation Method 1
an upper electrode used for a substrate processing apparatus using plasma
Implementation Method 2
a first distance, which is a first radial-direction distance between the first apex and a center axis of the upper electrode
Data Source
AI summary
An upper electrode used for a substrate processing apparatus using plasma is provided. The upper electrode includes a bottom surface including a center region and an edge region having a ring shape and surrounding the center region, a first protrusion portion protruding toward plasma from the edge region and having a ring shape, wherein the first protrusion portion includes a first apex corresponding to a radial local maximum point toward the plasma, and a first distance, which is a radial-direction distance between the first apex and a center axis of the upper electrode, is greater than a radius of a substrate.