Harmonic Control Unit for Plasma Uniformity
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Solution Overview
Problem
The uniformity of plasma density in semiconductor substrate processing is compromised by harmonics generated in the chamber during the etching process, leading to non-uniform substrate processing, especially as the strength of RF power increases, and existing methods are inadequate in controlling multiple harmonic components effectively.
Innovation Solution
A substrate processing apparatus with a harmonic control unit that includes a ring unit and a harmonic control circuit, utilizing blocking filters and variable capacitors to block and remove specific harmonic components, allowing the harmonic control circuit to resonate at specific frequencies and effectively manage harmonics in the electric field.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If RF power is increased to increase plasma density, then plasma density increases, but uniformity of plasma density deteriorates due to increased harmonic components
Solution Approach 1:
The patent extracts and removes harmful harmonic components from the RF power signal using a harmonic control unit. The unit identifies specific harmonic frequencies generated in the chamber and selectively removes them through filtering, allowing the main RF power to remain high for plasma density while eliminating the harmful harmonics that cause non-uniformity.
Solution Approach 2:
The patent introduces a harmonic control unit as an intermediary between the RF generator and the chamber. This intermediary device monitors the RF signal, identifies harmonic components, and removes them before they can affect plasma uniformity, thus mediating between the need for high RF power and the need for uniform plasma distribution.
2Object-generated harmful factors
If external circuit is connected to change resonant frequency region to suppress harmonics, then harmonic amplification is prevented, but transfer characteristics of RF power are affected
Solution Approach 1:
The harmonic control unit serves as an intermediary that selectively removes harmonics without disrupting the main RF power transfer. By using targeted filtering rather than broad resonant frequency shifting, the unit eliminates harmful harmonics while preserving the impedance matching and power transfer characteristics needed for efficient plasma generation.
Solution Approach 2:
The patent changes the electrical parameters (impedance, resonant frequency) of the harmonic control unit dynamically to match and remove specific harmonic frequencies. By adjusting these parameters to target only the harmful harmonic components rather than the main RF frequency, the system suppresses harmonics while maintaining optimal RF power transfer to the plasma.
3Device complexity
If control of only one harmonic component is implemented, then control complexity is reduced, but plasma uniformity improvement is insufficient as multiple harmonic components affect plasma density
Solution Approach 1:
The patent segments the harmonic control into multiple independent control circuits, each targeting a specific harmonic frequency. This segmentation allows the system to handle multiple harmonic components separately and efficiently, improving plasma uniformity by addressing each harmonic's unique characteristics without creating a monolithic complex control system.
Solution Approach 2:
The patent implements dynamic control where the harmonic control unit can adaptively adjust which harmonic frequencies are targeted and removed based on real-time conditions. This dynamic approach allows the system to respond to varying harmonic content across different process steps while maintaining manageable complexity through modular architecture.
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 solution improves the uniformity of plasma density and substrate processing by efficiently controlling and removing harmonic components, thereby enhancing the consistency of the etching process even at higher RF power levels.
Implementation Method 1
utilizing blocking filters and variable capacitors to block and remove specific harmonic components
Implementation Method 2
utilizing blocking filters and variable capacitors to block and remove specific harmonic components
Implementation Method 3
allowing the harmonic control circuit to resonate at specific frequencies
Implementation Method 4
The RF power applied by the RF generator excites the process gas supplied into a chamber to generate plasma
Implementation Method 5
harmonics may be generated due to the nonlinear impedance of the structure of the chamber, an external circuit, plasma, and a plasma sheath
Data Source
AI summary
Disclosed is a substrate processing apparatus. The substrate processing apparatus includes a chamber having an inner space; a support unit that supports a substrate in the inner space; a ring unit disposed on an edge area of the support unit when viewed from above; a power unit that generates RF power for forming an electric field in the inner space; and a harmonic control unit connected to the ring unit to control harmonics generated by the RF power.