Plasma Processing Waveguide Wavelength Adjustment
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Solution Overview
Problem
As substrate sizes increase, achieving uniform plasma density becomes challenging due to standing waves generated in electrodes, especially at higher plasma excitation frequencies, which affects film quality and throughput in plasma processing applications like flat panel displays and solar cells.
Innovation Solution
A plasma processing apparatus with a waveguide path having a slit-shaped opening and an adjusting unit to lengthen the wavelength of high-frequency power, preventing standing waves and ensuring a uniform electric field, even at high excitation frequencies, by using a coaxial waveguide and impedance variable circuits to control the effective height of the waveguide path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If plasma excitation frequency is increased to improve plasma density and reduce electron temperature, then film quality and throughput are improved, but uniformity of plasma density deteriorates due to standing waves in the electrode
Solution Approach 1:
The patent changes the electrical parameters of the waveguide path by adjusting its effective height to modify the propagation characteristics of high frequency power. By controlling the effective height, the wavelength of high frequency power is lengthened, which prevents standing wave formation and enables uniform plasma excitation at high frequencies (40 MHz or higher), thereby resolving the contradiction between productivity and manufacturing precision
Solution Approach 2:
The waveguide path serves as an intermediary component between the high frequency power supply and the plasma generation region. It mediates the transmission of high frequency power by controlling its propagation characteristics through adjustable effective height, allowing uniform plasma excitation across large substrates at high frequencies without direct connection that would cause standing waves
2Productivity
If electrode size is increased to process larger substrates, then productivity is improved, but uniform plasma excitation becomes difficult due to standing waves when electrode size exceeds 1/20 of wavelength
Solution Approach 1:
The patent changes the propagation parameters of high frequency power by adjusting the effective height of the waveguide path. This lengthens the wavelength of the power in the waveguide, allowing large electrodes (exceeding 1/20 of wavelength) to be used without generating standing waves, thus enabling uniform plasma excitation across large substrates while maintaining high productivity
Solution Approach 2:
The patent introduces a new dimension of control by making the waveguide path height adjustable. This additional degree of freedom allows independent optimization of wavelength and electrode size, decoupling the constraint that previously limited electrode size to 1/20 of wavelength, thereby enabling both large substrate processing and uniform plasma excitation
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 allows for the generation of uniform plasma on large substrates even at high plasma excitation frequencies, improving film quality and throughput by minimizing reflections and maintaining a consistent electric field intensity across the electrode surface.
Implementation Method 1
a waveguide path, connected to the transmission path, having a slit-shaped opening toward the plasma space
Implementation Method 2
an adjusting unit configured to adjust a wavelength of a high frequency power propagating in the waveguide path in a lengthwise direction of the slit-shaped opening
Implementation Method 3
plasma is generated by introducing a gas into a vacuum chamber and applying a high frequency power
Data Source
AI summary
A plasma processing apparatus can excite uniform plasma on a large substrate. The plasma processing apparatus 10 includes a vacuum chamber 100 having therein a mounting table 115 configured to mount a substrate G, and a plasma space, formed above the mounting table, in which plasma is generated; a first coaxial waveguide 225 through which a high frequency power for exciting plasma is supplied into the vacuum chamber 100; a waveguide path 205, connected to the first coaxial waveguide 225, having a slit-shaped opening toward the plasma space; and an adjusting unit configured to adjust a wavelength of the high frequency power propagating in the waveguide path in a lengthwise direction of the slit-shaped opening. By adjusting the wavelength of the high frequency power propagating in the waveguide path to be sufficiently lengthened, uniform plasma can be excited on the large substrate.