Double-Helix Plasma Coil Layout for Uniform Low-Contamination Etching
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Solution Overview
Problem
Existing plasma processing apparatuses face issues with non-uniform plasma distribution and high electric field strength, leading to etch rate imbalances and increased contamination due to the end point electric field affecting the dielectric window, which is exacerbated by high RF power output.
Innovation Solution
The apparatus incorporates a plasma processing chamber with a main coil and a sub-coil assembly featuring a double helix structure, where the sub-coil's lower surface is connected to ground potential, reducing electric field strength and improving symmetry, thereby enhancing plasma distribution uniformity and reducing contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high RF power output is used to improve plasma generation efficiency, then plasma density increases, but electric field strength becomes excessively high causing contamination and non-uniform plasma distribution
Solution Approach 1:
The antenna system is divided into a main coil and a sub-coil assembly with independent ground connections. The sub-coil assembly includes first and second spiral coils with alternately arranged turns, where odd-numbered turns are connected to ground and even-numbered turns are connected to RF power. This segmentation allows the electric field to be distributed more uniformly across the plasma processing chamber, preventing excessive electric field concentration while maintaining high plasma generation efficiency.
2Manufacturing precision
If conventional single-coil antenna structure is used, then device complexity is low, but plasma distribution uniformity is poor
Solution Approach 1:
The sub-coil assembly is disposed radially inside or outside the main coil, creating a nested configuration where the first and second spiral coils are positioned within the magnetic field region of the main coil. This nested structure enables improved plasma distribution uniformity by creating overlapping magnetic field regions that enhance plasma generation consistency without requiring completely separate antenna systems.
Solution Approach 2:
The sub-coil assembly introduces a new spatial dimension to the antenna structure by adding radial positioning inside or outside the main coil, and by creating alternating turn patterns in the vertical direction. This dimensional enhancement allows for better plasma distribution uniformity through multi-dimensional field optimization while maintaining a compact overall structure.
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 achieves a more uniform plasma distribution across the substrate while minimizing electric field strength and contamination, allowing for increased RF power usage without overheating, thus improving processing efficiency and reducing part wear.
Implementation Method 1
a main coil disposed on or above the plasma processing chamber; a sub-coil assembly disposed radially inside or outside the main coil
Implementation Method 2
an RF power supply configured to supply an RF power to the main coil
Implementation Method 3
The first upper terminal is connected to a ground potential via one or more capacitors, and the first lower terminal is connected to the ground potential
Implementation Method 4
an antenna that generates plasma of a processing gas in a chamber by supplying radio-frequency to the chamber
Data Source
AI summary
A plasma processing apparatus includes: a main coil disposed on or above a plasma processing chamber; and a sub-coil assembly disposed radially inside or outside the main coil. The sub-coil assembly includes a first spiral coil and a second spiral coil. Each turn of the first spiral coil and each turn of the second spiral coil are alternately arranged in a vertical direction. A first upper terminal of the first spiral coil is connected to a ground potential via one or more capacitors, and a first lower terminal of the first spiral coil is connected to the ground potential. A second upper terminal of the second spiral coil is connected to the ground potential via one or more capacitors or one or more other capacitors, and a second lower terminal of the second spiral coil is connected to the ground potential.