Plasma Chamber Ceiling Layout for Collimated Vertical Ion Flux
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Solution Overview
Problem
Current plasma processing technologies face challenges in achieving the stringent process control needed for fabricating high aspect ratio features in semiconductor devices, particularly in providing a highly collimated ion flux and maintaining smooth vertical sidewalls.
Innovation Solution
The apparatus and method involve a plasma processing chamber with a central conductive cover and a dielectric window, a substrate holder aligning the substrate's backside under the conductive cover, an antenna for coupling AC EM power to the plasma, and a magnet generating a DC magnetic field. This configuration reduces the spread in ion angle distribution, achieving a highly collimated vertical ion flux.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional plasma processing is used, then plasma processes can be performed, but ion angular spread is large and vertical sidewall smoothness deteriorates
Solution Approach 1:
The chamber ceiling is segmented into a central conductive cover and a surrounding dielectric window, creating distinct magnetic flux regions. The central conductive cover confines magnetic flux to a central flux tube that intercepts only the substrate hold area, separating the ion flux path from the plasma generation region. This segmentation reduces ion angular spread and prevents sidewall roughening while maintaining plasma processing capability.
2Productivity
If plasma density is increased to improve processing speed, then productivity increases, but ion angular spread increases and sidewall control deteriorates
Solution Approach 1:
The invention creates different plasma conditions in different spatial regions. The central flux tube region provides low electron temperature and highly collimated ion flux for precise sidewall formation, while the surrounding plasma region can maintain higher density for adequate processing speed. This local quality differentiation allows simultaneous achievement of productivity and manufacturing precision.
3Manufacturing precision
If magnetic field strength is increased to improve ion collimation, then ion angular spread decreases, but plasma confinement and stability worsen
Solution Approach 1:
The invention extracts and confines magnetic flux to a specific central flux tube region using the central conductive cover. By taking out the magnetic field from the entire chamber and concentrating it only in the central region that intercepts the substrate hold area, the patent achieves excellent ion collimation without disrupting overall plasma stability. The surrounding dielectric window region remains free from strong magnetic field effects that would cause instability.
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 described solution effectively reduces the ion angular spread, ensuring a highly collimated ion flux that enhances the precision of plasma processes such as HARC etch, leading to improved feature formation in semiconductor devices with high aspect ratios.
Implementation Method 1
an antenna configured to couple alternating current (AC) electromagnetic (EM) power from an AC EM signal to plasma in the chamber, the AC EM power being absorbed in a heating zone located within a depth directly below the dielectric window
Implementation Method 2
a magnet configured to generate a DC magnetic field in the chamber, where a width of a central flux tube at the ceiling is less than or equal to a width of the conductive cover
Data Source
AI summary
An apparatus for plasma processing a substrate, where the apparatus includes a plasma processing chamber having a ceiling including a central conductive cover surrounded by a dielectric window, the conductive cover being wider than the substrate; a substrate holder configured to hold the substrate in the chamber, a backside of the substrate being aligned to be inside a hold area of a horizontal top surface of the holder, the hold area being an area under the conductive cover; disposed over the dielectric window, an antenna configured to couple AC electromagnetic (EM) power from an AC EM signal to plasma in the chamber, the AC EM power being absorbed in a heating zone located within a depth directly below the dielectric window; and a magnet configured to generate a DC magnetic field in the chamber, the central flux tube being a magnetic flux tube intercepting the hold area.