Cylindrical Workpiece as Internal RF Antenna for Plasma Processing
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Solution Overview
Problem
Existing inductively coupled plasma (ICP) processing apparatuses face challenges in scalability and plasma uniformity when applied to large area or three-dimensional workpieces due to limitations in RF power transfer efficiency, capacitive coupling, and contamination issues, particularly in semiconductor processing.
Innovation Solution
An inductively coupled plasma processing reactor with a cylindrical workpiece acting as an internal RF antenna, connected through an impedance matching network and terminating capacitor, and equipped with a cylindrical gas shower electrode, magnetic field control, and a rotating mechanism to achieve uniform plasma distribution and minimize secondary electron emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If an exterior antenna ICP apparatus is used for large area processing, then the processing area can be increased, but the separation between the antenna and plasma leads to lower RF power transfer efficiency
Solution Approach 1:
The patent inverts the conventional exterior antenna configuration by placing the antenna inside the plasma chamber. The cylindrical workpiece itself serves as the antenna, with RF power applied directly to it. This internal antenna configuration eliminates the separation between antenna and plasma, ensuring efficient RF power transfer while enabling large area processing.
Solution Approach 2:
The cylindrical workpiece serves dual functions: it is both the object to be processed and the antenna for plasma generation. By making the workpiece itself the antenna, the system eliminates the need for a separate antenna structure, directly coupling RF power to the plasma at the processing location.
2Strength
If a thick vacuum dielectric window is used to maintain structural integrity for large area processing, then structural strength is improved, but the cost increases
Solution Approach 1:
Instead of using a thick vacuum window to maintain structural integrity, the patent inverts the approach by placing the antenna inside the chamber. The workpiece itself serves as the antenna, eliminating the need for a separate window structure and reducing costs while maintaining structural integrity through the chamber design.
3Area of stationary object
If the area or volume of the workpiece is increased for large scale processing, then the processing capacity is improved, but the inductance of the antenna increases leading to higher required RF voltage
Solution Approach 1:
The patent addresses the inductance issue by inverting the antenna configuration. Instead of using a traditional external antenna whose inductance increases with size, the workpiece itself becomes the antenna. This internal configuration allows for better impedance matching and reduces the required RF voltage even for large area processing.
Solution Approach 2:
The patent employs impedance matching networks to optimize the electrical parameters of the system. By adjusting the impedance parameters and using appropriate matching circuits, the system can efficiently deliver RF power to large workpieces without requiring excessive voltage, thereby managing the inductance issue effectively.
4Quantity of substance
If the length of the helical or spiral antenna is increased to achieve high efficiency plasma, then the plasma density is improved, but the spatial uniformity of coupling between antenna and plasma deteriorates
Solution Approach 1:
The patent resolves the uniformity issue by inverting the antenna approach. Instead of using a long helical or spiral external antenna that creates non-uniform coupling, the cylindrical workpiece itself serves as the antenna. This configuration ensures uniform RF power distribution and consistent plasma coupling across the entire workpiece surface, maintaining both high plasma density and spatial uniformity.
5Reliability
If a conventional ICP apparatus is used for three-dimensional workpieces, then planar processing capability is maintained, but plasma uniformity across large volume and through three-dimensional structures deteriorates
Solution Approach 1:
The patent inverts the conventional planar processing approach by making the three-dimensional workpiece itself the antenna. This internal antenna configuration allows plasma to be generated uniformly throughout the volume of the workpiece, enabling effective processing of three-dimensional structures while maintaining processing reliability.
Solution Approach 2:
The patent transitions from two-dimensional planar processing to three-dimensional volume processing by using the cylindrical workpiece as an internal antenna. This dimensional change allows RF power to be coupled throughout the volume of the workpiece, achieving uniform plasma distribution across complex three-dimensional geometries.
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
Enables efficient plasma processing for three-dimensional substrates with improved uniformity and reduced contamination, allowing for surface cleaning, etching, and micro/nano-pattern transfer on large or complex substrates, including 3-D semiconductor devices and other materials.
Implementation Method 1
inductively coupled plasma (ICP)... applying RF power to the cylindrical workpiece through the impedance matching network... forming plasma inside the vacuum chamber through generation of resonance by the applied RF power
Implementation Method 2
a rotating mechanism to achieve uniform plasma distribution
Data Source
AI summary
The present invention relates to an inductively coupled plasma processing chamber and method for a cylindrical workpiece with a three-dimensional profile, and more particularly to an inductively coupled plasma processing reactor and method for a cylindrical workpiece with a three-dimensional profile, in which the workpiece serving as an internal RF antenna is connected to an RF power source through an impedance matching network at one end, and a terminating capacitor at another end so as to achieve low plasma contamination, confine dense uniform plasma in the substrate vicinity and suppress secondary electrons emitted from the substrate, and a plasma process can be applied to a 3-D linear semiconductor device, a metal, glass, ceramic or polymer substrate having planar or 3-D structured micro or nano patterns, and the like.