Circular Waveguide Plasma Processing with Adjustable Dielectric Stubs
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Solution Overview
Problem
Conventional plasma processing apparatuses face challenges in achieving uniform plasma distribution and adjusting the axial ratio of circularly polarized waves, leading to non-uniform processing and increased manufacturing costs, especially when handling larger semiconductor wafers.
Innovation Solution
A plasma processing apparatus with a circularly polarized wave generator, corrector, and detector system, where dielectric stubs in the circular waveguide are adjustable to maintain an optimal axial ratio, ensuring high uniformity and accuracy in plasma distribution, even with changes in processing conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the processing chamber size is increased to accommodate larger diameter wafers (450 mm), then the manufacturing capacity and area utilization are improved, but the plasma uniformity in radial and circumferential directions deteriorates
Solution Approach 1:
The waveguide is divided into multiple sections with different impedance values along the propagation direction. This segmentation allows progressive adjustment of the electromagnetic field distribution, enabling the large processing chamber to achieve uniform plasma distribution by controlling the field characteristics in different zones
Solution Approach 2:
Different sections of the waveguide are assigned different impedance characteristics tailored to local requirements. The impedance varies along the propagation direction to optimize plasma uniformity in specific regions of the large processing chamber, particularly addressing the radial and circumferential non-uniformity issues
2Device complexity
If conventional waveguide structures are used without impedance adjustment, then the device complexity is reduced, but the axial ratio control precision of circularly polarized waves deteriorates
Solution Approach 1:
The waveguide impedance is made variable along the propagation direction rather than fixed. This dynamic impedance profile allows the system to maintain optimal axial ratio control for circularly polarized waves by adapting the field distribution to the specific operating conditions and plasma characteristics
Solution Approach 2:
The characteristic impedance of the waveguide is changed progressively along its length. By adjusting the impedance parameter in different sections, the system achieves precise control over the axial ratio of circularly polarized waves without requiring overly complex structural modifications
3Ease of manufacture
If the waveguide impedance is uniformly designed, then the manufacturing and design process is simplified, but the plasma distribution uniformity in the processing chamber deteriorates
Solution Approach 1:
The waveguide is segmented into multiple sections, each with optimized impedance values. This segmentation approach balances manufacturing simplicity with performance requirements, as each section can be designed and fabricated separately with standard tolerances while achieving the cumulative effect of improved plasma uniformity
Solution Approach 2:
Rather than requiring complex adaptive mechanisms, the impedance is designed to vary in a predetermined dynamic profile along the waveguide. This static dynamic design achieves plasma uniformity through careful impedance profiling while maintaining ease of manufacture through systematic design approaches
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 apparatus achieves high accuracy in adjusting the axial ratio of circularly polarized waves, resulting in improved uniformity and reduced non-uniformity in plasma processing, enabling efficient processing of larger wafers with reduced manufacturing costs and labor.
Implementation Method 1
a circularly polarized wave generator (201) which generates a circularly polarized wave
Implementation Method 2
adjustment of an operation of the circularly polarized wave corrector (205) according to an output from the circularly polarized wave detector (206), and based on a signal from which the circularly polarized wave corrector (205) is configured to adjust a length of each dielectric stub to protrude into the circular waveguide
Implementation Method 3
through which an electric field for plasma generation propagates
Implementation Method 4
inside of which the electric field is supplied and the plasma is generated
Data Source
AI summary
Provided is a plasma processing apparatus including: a circular waveguide connected with a vacuum vessel, and through which a circularly polarized wave of an electric field for plasma formation propagates; a processing chamber which is arranged below the circular waveguide, and in which plasma is formed; a circularly polarized wave generator, which is arranged in the waveguide; a circularly polarized wave adjuster which is connected with the circular waveguide below the circularly polarized wave generator; a circularly polarized wave detector which is below the circularly polarized wave adjuster; and a controller which adjusts an operation of the circularly polarized wave adjuster according to an output from the circularly polarized wave detector, in which the circularly polarized wave adjuster adjusts a length of a protrusion of a dielectric stub into the circular waveguide based on a signal from the controller.