Inductive Plasma Power Delivery Without Impedance Matching
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Solution Overview
Problem
Existing inductively coupled plasma (ICP) power systems face challenges such as high cost, complexity, and non-repeatable power delivery due to slow impedance matching and frequency tuning, which affect etch or deposition uniformity.
Innovation Solution
A power delivery system utilizing DC-controlled RF resonant power amplifiers with zero-voltage switching and adjustable impedance, eliminating the need for impedance matching and reducing complexity by using remote fixed-DC power supplies and DC/DC converters, allowing precise control of power and current to each ICP coil.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fixed frequency RF power sources with separate RF match circuits are used for each ICP coil, then power delivery to each coil is achieved, but system cost and complexity increase, and impedance matching tuning time becomes slow (hundreds of milliseconds to several seconds)
Solution Approach 1:
The patent combines multiple ICP coil drives into a single RF power source with a unified impedance matching network, eliminating the need for separate match circuits for each coil. This merging approach reduces system complexity and component count while maintaining the ability to independently control power to each coil through reactive current splitting circuitry.
Solution Approach 2:
The patent segments the current path after the unified impedance matching network, using reactive current splitting circuitry to divide and control the current to each individual ICP coil. This allows independent power control to each coil while sharing the complex impedance matching functionality, resolving the contradiction between reliability and complexity.
2Adaptability or versatility
If variable frequency RF power sources with separate RF match circuits are used for each ICP coil, then frequency tuning capability is achieved, but system cost increases and frequency tuning time becomes slow (hundreds of microseconds to tens of milliseconds)
Solution Approach 1:
The patent employs a single variable frequency RF power source that serves all ICP coils, merging the frequency tuning capability into one shared system. This eliminates the need for multiple variable frequency sources and their associated impedance matching networks, significantly reducing system complexity while maintaining full frequency tuning capability for plasma processing applications.
3Device complexity
If a single fixed-frequency RF power source is coupled to multiple ICP coils through an RF match circuit with reactive current splitting, then system complexity is reduced, but current control range between coils is limited and tuning time remains slow (hundreds of milliseconds to several seconds)
Solution Approach 1:
The patent implements dynamically adjustable reactive current splitting circuitry that can rapidly modify the current distribution to each ICP coil. By using variable reactive components that can be quickly adjusted, the system achieves wide current control range and fast tuning response, overcoming the limitations of fixed or slowly-adjustable current splitting networks.
Solution Approach 2:
The patent changes the electrical parameters (reactive impedance values) of the current splitting circuitry to control the current magnitude and ratio between different ICP coils. By dynamically adjusting these parameters, the system achieves broad current control range and optimized performance for different process conditions without increasing overall system complexity.
4Adaptability or versatility
If variable frequency tuning is implemented in existing systems, then frequency adaptation is achieved, but tuning time becomes slow (hundreds of microseconds to several milliseconds)
Solution Approach 1:
The patent implements preliminary impedance matching and frequency tuning through microprocessor-controlled algorithms that pre-optimize the RF power delivery system before plasma ignition. By performing the tuning action in advance and using predictive algorithms, the system achieves fast frequency adaptation without requiring slow iterative adjustments during operation, significantly reducing tuning time.
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
Enables fast and repeatable power delivery with improved uniformity in plasma processing, reducing costs and complexity by eliminating the need for impedance matching and frequency tuning algorithms.
Implementation Method 1
A power delivery system utilizing DC-controlled RF resonant power amplifiers with zero-voltage switching and adjustable impedance, eliminating the need for impedance matching and reducing complexity by using remote fixed-DC power supplies and DC/DC converters, allowing precise control of power and current to each ICP coil.
Implementation Method 2
The power delivery system also comprises an impedance coupled to a second node and a controller configured to control power to the first node by varying the voltage source and control power to the second node by adjusting the impedance.
Data Source
AI summary
A power delivery system comprising a voltage source, an amplifier coupled to a first node and the voltage source, the amplifier comprising a reactive network configured to form a resonant circuit when the first node is coupled to a coil. The power delivery system also comprises an impedance coupled to a second node and a controller configured to control power to the first node by varying the voltage source and control power to the second node by adjusting the impedance.