Wafer-Integrated Ion Energy Analyzer for RF Plasma Measurement
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Solution Overview
Problem
Current ion energy analyzers for plasma processing face challenges such as parasitic impedance from wired connections, difficulty in robotic loading, limited vacuum pressure range, and inadequate energy range for measuring ion energy distributions, particularly in RF biased environments, which hinder their widespread adoption in semiconductor manufacturing.
Innovation Solution
A substrate-integrated ion energy analyzer with a Faraday shield encasing the ion energy analyzer, power supply, and control circuitry, featuring a high voltage generating circuit with a Cockcroft-Walton voltage multiplier and a battery manager to regulate voltage, allowing for wireless communication and operation within the plasma processing system, enabling precise measurement of ion energy distributions across a wide energy range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If wired connections are used to connect the ion energy analyzer to the control system, then the analyzer can transmit signals outside the vacuum chamber, but parasitic impedance is introduced that artificially impacts the pedestal RF bias conditions and the resultant IED
Solution Approach 1:
The patent removes the wired connections and external control electronics from the system, extracting the harmful parasitic impedance. Instead, it implements a fully integrated wireless solution where the ion energy analyzer, power supply, and control circuitry are combined into a single self-contained unit that communicates wirelessly with external systems, thereby eliminating the source of measurement distortion.
Solution Approach 2:
The patent introduces wireless communication as an intermediary between the ion energy analyzer inside the vacuum chamber and the external control system. This wireless intermediary transmits data and power without physical connections, avoiding the parasitic impedance that would otherwise be introduced by wired connections while maintaining full functionality.
2Measurement precision
If the ion energy analyzer structure is made many millimetres in height to accommodate the gridded sensor stack, then ion energy analysis capability is achieved, but deployment on a substrate with similar thickness to a process wafer becomes difficult and the vacuum pressure range is limited
Solution Approach 1:
The patent transitions from a traditional vertical stacked configuration to a planar integrated design where the gridded sensor stack is flattened and integrated directly into the substrate surface. This dimensional transformation allows the analyzer to maintain its ion energy analysis functionality while reducing its profile from millimetres to micrometres, enabling it to be deployed on substrates with thickness similar to standard process wafers.
Solution Approach 2:
The patent merges the ion energy analyzer, power supply, control circuitry, and substrate into a single integrated unit. The gridded sensor stack is combined with the substrate itself, eliminating the need for separate components and reducing overall height. This integration allows the analyzer to function as a thin-film device compatible with standard wafer thicknesses and broader vacuum pressure ranges.
3Ease of operation
If the ion energy analyzer is wired to a remote electronic control system, then the control system can be located outside the vacuum chamber, but the wiring prevents easy loading of the ion energy analyzer to the plasma processing chamber using the standard robotic loading system
Solution Approach 1:
The patent extracts the wiring and external control system from the ion energy analyzer, removing the complexity that hindered robotic loading. The analyzer becomes a standalone unit with integrated power and control, requiring no external connections during loading operations, thus enabling seamless integration with standard robotic loading systems.
Solution Approach 2:
The patent implements self-service by integrating all necessary control electronics and power supplies directly into the ion energy analyzer unit. The device is self-contained and autonomous, requiring no external wiring or control connections during installation or operation, which simplifies robotic loading and chamber integration while maintaining full analytical capability.
4Measurement precision
If a wired RFA design is used with cable bundles and vacuum feedthroughs, then signals can be transmitted from the sensor to the air side, but the structure adds significant height and complexity making deployment on thin substrates difficult
Solution Approach 1:
The patent replaces the mechanical wiring system (cable bundles, vacuum feedthroughs, connectors) with a wireless communication system. This substitution eliminates the need for physical signal transmission paths, removing the associated height and complexity while maintaining full signal transmission capability between the sensor inside the chamber and external systems.
Solution Approach 2:
The patent extracts and removes the entire wiring infrastructure including cable bundles, vacuum feedthroughs, and external control electronics. By eliminating these mechanical components, the sensor structure height is dramatically reduced, enabling deployment on thin substrates while wireless communication maintains the necessary signal transmission functionality.
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 solution provides accurate and reliable ion energy distribution measurements across a wide energy range, reduces parasitic impedance, and facilitates robotic loading, enhancing the precision and efficiency of plasma processing by integrating the necessary components within the substrate, thus improving process control and yield.
Implementation Method 1
a high voltage generating circuit within the substrate and comprising a Cockcroft-Walton voltage multiplier
Implementation Method 2
a succession of grids are used to a) prevent plasma penetration inside the device, b) repel plasma electrons, c) discriminate ions based on their energies
Implementation Method 3
A Faraday shield may encase the ion energy analyser, the power supply and the electronic control circuitry
Data Source
Figure 1
Figure 2(a)~2(d)
Figure 3(a)~3(b)
AI summary
An apparatus for obtaining ion energy distribution, IED, measurements in a plasma processing system comprising a substrate for placement in the plasma processing system and exposed to the plasma, an ion energy analyser disposed in the substrate for measuring the ion energy distribution at the substrate surface during plasma processing, the analyser comprising a first conductive grid, G0, a second conductive grid, G1, a third conductive grid, G2, a fourth conductive grid G3, and a collection electrode, C, each grid separated by an insulating layer, a battery power supply and a battery manager integrated in the substrate, for supplying and controlling voltage to each of the grids and the collector of the ion energy analyser, and a high voltage generating circuit within the substrate, wherein the high voltage generating circuit takes the output voltage of the battery manager and supplies a voltage sweep to the third conductive grid.