Split ICP Coil Assembly for Uniform Wafer Etch Control
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Solution Overview
Problem
Inductively coupled plasma (ICP) chambers experience non-uniform etch rates on semiconductor wafers, leading to performance issues and reduced yields due to defects caused by etch rate nonuniformity.
Innovation Solution
A method and apparatus utilizing a split coil assembly with electrically isolated coil sets and multiple RF power source channels, combined with isolation filters and current dividers, to achieve precise control over RF energy distribution and plasma density uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single coil assembly is used in the ICP chamber, then the device complexity is low, but the etch rate uniformity across the wafer deteriorates
Solution Approach 1:
The coil assembly is divided into multiple electrically isolated coil sets (first coil set, second coil set, etc.), each capable of receiving RF power at different frequencies. This segmentation allows independent control of plasma generation in different spatial regions, enabling uniform etch rates across the wafer surface while managing complexity through modular design
2Adaptability or versatility
If multiple RF power source channels at different frequencies are used, then the adaptability and control flexibility improve, but the device complexity increases
Solution Approach 1:
The coil assembly is designed to serve multiple functions by accepting RF power at different frequencies from multiple channels. Each coil set can operate independently or in combination with others, providing universal control capability for different plasma processing requirements while maintaining a unified hardware platform
Solution Approach 2:
Isolation filters are introduced as intermediary components between the RF power sources and coil sets. These filters prevent frequency crosstalk and interference, enabling multiple RF channels to operate simultaneously without mutual interference, thus achieving frequency flexibility while managing system complexity
3Manufacturing precision
If electrically isolated coil sets are used, then the plasma density uniformity improves, but the device complexity and manufacturing cost increase
Solution Approach 1:
The coil assembly is divided into multiple electrically isolated coil sets that can be independently controlled. This segmentation enables precise control of plasma generation in different spatial zones, achieving uniform plasma density across the wafer while using standardized, modular coil components that simplify manufacturing
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
Enhances etch rate uniformity by minimizing crosstalk and power feedback, allowing for flexible frequency and power level adjustments, resulting in improved process uniformity and ion density control.
Implementation Method 1
Inductively coupled plasma (ICP) chambers use coils or antennas to induce RF energy into a gas disposed inside of the process volume of the chamber. The induced RF energy and gas creates plasma with a high plasma density. The coupling of the RF energy into the gas is accomplished via a magnetic field produced by the coils.
Implementation Method 2
generating a first RF power for the ICP chamber with a first frequency to a first electrical connection of a first coil set of the coil assembly via a first match network and generating a second RF power for the ICP chamber with a second frequency to a third electrical connection of a second coil set of the coil assembly via a second match network
Data Source
AI summary
Methods and apparatus for inductively coupled plasma chambers allow for split parallel coil sets to be energized with the same or different RF frequencies. An ICP source may comprise a first RF power with a first frequency connected to a first coil set of the coil assembly, a second RF power with a second frequency connected to a second coil set where the first coil set has a first inner coil and a first outer coil positioned concentrically about the first inner coil, the first inner coil and the first outer coil are electrically connected in series, the second coil set has a second inner coil and a second outer coil positioned concentrically about the second inner coil, the second inner coil and the second outer coil are electrically connected in series, and the first coil set and the second coil set are electrically energized separately from each other.