Segmented RF Antenna for Uniform Plasma Distribution
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Solution Overview
Problem
Conventional inductively coupled plasma processing apparatuses face challenges in achieving uniform plasma density distribution both circumferentially and radially due to wavelength effects and voltage drops within the RF antenna, leading to inadequate plasma uniformity and potential damage to dielectric windows.
Innovation Solution
The apparatus features a RF antenna configuration with inner, intermediate, and outer coils connected in parallel, along with variable capacitors to adjust reactance and current balance, suppressing wavelength effects and voltage drops, ensuring uniform plasma distribution by controlling the electrostatic capacitance and current flow within each coil segment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a single large-diameter RF antenna is used, then plasma can be generated in a large processing space, but wavelength effects cause non-uniform plasma density distribution
Solution Approach 1:
The RF antenna is divided into multiple coil segments (e.g., 4 segments) along its length. Each segment can be independently controlled to compensate for wavelength effects and achieve uniform plasma density distribution across the large processing space, resolving the contradiction between large plasma volume and uniformity.
Solution Approach 2:
Different sections of the RF antenna are assigned different electrical characteristics through independent coil segments with adjustable impedance and phase. This allows local optimization of plasma generation at each section to achieve overall uniformity across the entire processing space.
2Manufacturing precision
If multiple circular ring-shaped coils are connected in series to increase coil length, then plasma density uniformity in circumferential direction may improve, but voltage drop increases and wavelength effects cause non-uniformity in diametrical direction
Solution Approach 1:
The antenna is segmented into multiple independent coil sections that are electrically isolated. This segmentation reduces the effective electrical length of each segment, minimizing voltage drop and wavelength effects while maintaining the ability to generate uniform plasma density through coordinated control of all segments.
Solution Approach 2:
Instead of extending coil length in one dimension (which increases voltage drop), the solution uses multiple segments distributed along the antenna length, controlling plasma uniformity through spatial distribution and independent phase control rather than simply increasing total coil length.
3Manufacturing precision
If a conventional RF antenna is used, then apparatus structure remains simple, but plasma density uniformity on substrate is insufficient
Solution Approach 1:
The RF antenna is divided into multiple coil segments that can be independently controlled. This segmentation enables precise control of plasma density distribution across the substrate while maintaining a relatively simple overall antenna structure that integrates with existing plasma processing equipment.
Solution Approach 2:
The antenna system incorporates dynamic control capabilities where each coil segment can independently adjust its electrical characteristics (impedance, phase, amplitude) to optimize plasma uniformity in real-time, achieving high manufacturing precision without requiring a fundamentally complex antenna 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
This configuration enables uniform plasma processing in both circumferential and radial directions, reducing voltage drops and ion impact on dielectric windows, thereby enhancing plasma uniformity and process reproducibility while minimizing damage to the apparatus.
Implementation Method 1
A high frequency AC magnetic field having magnetic force lines is generated around the RF antenna by a high frequency current flowing in the RF antenna. The magnetic force lines of the high frequency AC magnetic field are transmitted to the processing space within the chamber via the dielectric window. As the RF magnetic field of the high frequency AC magnetic field changes with time, an inductive electric field is generated in an azimuth direction within the processing space. Then, electrons accelerated by this inductive electromagnetic field in the azimuth direction collide with molecules or atoms of the processing gas so as to be ionized.
Data Source
AI summary
There is provided an inductively coupled plasma etching apparatus capable of suppressing a wavelength effect within a RF antenna and performing a plasma process uniformly in both a circumferential and a radial direction. In the plasma etching apparatus, a RF antenna 54 is provided on a dielectric window 52 to generate inductively coupled plasma. The RF antenna 54 includes an inner coil 58, an intermediate coil 60 and an outer coil 62 in the radial direction. The inner coil 58 includes a single inner coil segment 59 or more than one inner coil segments 59 connected in series. The intermediate coil 60 includes two intermediate coil segments 61(1) and 61(2) separated in a circumferential direction and electrically connected with each other in parallel. The outer coil 62 includes three outer coil segments 63(1), 63(2) and 63(3) separated in a circumferential direction and electrically connected with each other in parallel.