Plasma Processing Apparatus Antenna Segmentation
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Solution Overview
Problem
Conventional inductively coupled plasma processing apparatuses face challenges in achieving uniform plasma density distribution on substrates, particularly due to the wavelength effect and voltage drop issues within the RF antenna, which affect the reproducibility and yield of plasma processes, especially as substrate sizes increase and device miniaturization demands higher plasma density and uniformity.
Innovation Solution
The apparatus incorporates a RF antenna with multiple coil segments connected in parallel, an electrically floating coil, and a capacitor in the floating coil's loop to control plasma density distribution. The floating coil's induced current adjusts the plasma generation space's electric field, allowing for precise control of plasma density through the positional relationship and current direction, thereby suppressing wavelength effects and ensuring uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single RF antenna is used to generate plasma, then the apparatus structure is simple, but the plasma density uniformity on the substrate is insufficient
Solution Approach 1:
The RF antenna is divided into multiple coil segments (e.g., four segments) that can be independently controlled. Each coil segment generates a localized plasma region, and by adjusting the power supply to each segment, uniform plasma density across the entire substrate surface is achieved. This segmentation allows precise control over plasma distribution without requiring a completely different antenna structure.
2Area of stationary object
If the substrate size is increased to accommodate larger devices, then the processing area is expanded, but the plasma density uniformity deteriorates due to wavelength effects and voltage drops in the RF antenna
Solution Approach 1:
The antenna is segmented into multiple independent coils, each responsible for a specific region of the large substrate. This allows localized control of plasma density in different areas, compensating for the wavelength effects and voltage drops that occur in long, single-antenna configurations. Each coil segment can be optimized for its specific zone, maintaining uniformity across the entire expanded substrate area.
Solution Approach 2:
Different coil segments are supplied with different power levels according to the specific requirements of each substrate region. This local quality adjustment ensures that plasma density is optimized for each area of the large substrate, rather than using a uniform power distribution that would result in non-uniform plasma across the entire surface.
3Length of moving object
If the RF antenna length is increased to cover larger substrate areas, then the processing coverage is improved, but wavelength effects and voltage drops increase, reducing plasma generation efficiency and uniformity
Solution Approach 1:
Instead of using one long continuous antenna, the system uses multiple shorter coil segments arranged to cover the required substrate area. Each segment maintains optimal electrical characteristics for efficient plasma generation, avoiding the wavelength effects and voltage drops that would occur in a single long antenna. The segments are positioned and controlled to provide uniform plasma distribution across the entire coverage area.
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 accurate control of plasma density distribution around the substrate, enhancing the uniformity and reproducibility of plasma processes, even under varying processing conditions, by preventing wavelength effects and voltage drops within the RF antenna.
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.
Implementation Method 2
at least one floating coil that is in an electrically floating state and provided outside the processing chamber to be coupled to the RF antenna by an electromagnetic induction
Data Source
AI summary
A plasma processing apparatus includes: a processing chamber; a substrate holding unit; a processing gas supply unit; a RF antenna having an inner antenna coil and an outer antenna coil; a high frequency power supply unit; at least one floating coil that is in an electrically floating state and provided outside the processing chamber to be coupled to at least one of the inner antenna coil and the outer antenna coil by an electromagnetic induction; and a capacitor. The inner antenna coil includes a single inner coil segment or more than one inner coil segments connected in series, the outer antenna coil includes a plurality of outer coil segments segmented in a circumferential direction and electrically connected with each other in parallel, and the at least one floating coil is positioned between the inner antenna coil and the outer antenna coil in a radial direction.