Substrate-Integrated Ion Energy Analysis Without Wired RF Interference
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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, which hinder their widespread adoption in semiconductor manufacturing and other industries.
Innovation Solution
A substrate-integrated ion energy analyzer with a four-grid design, including a Faraday shield, battery power supply, and high voltage generating circuit, capable of measuring ion energy distributions with a voltage sweep, is developed to address these challenges by eliminating parasitic impedance and enabling robotic loading and elevated temperature operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If wired connections are used to connect the ion energy analyzer to the control system, then the analyzer can transmit signals and data, but parasitic impedance is introduced that artificially impacts the pedestal RF bias conditions and the resultant ion energy distribution
Solution Approach 1:
The patent removes the wired connections and external control system from the plasma chamber environment. The ion energy analyzer is fully integrated into the substrate with all control electronics, power supply, and data processing contained within the substrate itself, eliminating the parasitic impedance introduced by external wiring.
Solution Approach 2:
The patent introduces a wireless communication interface as an intermediary between the integrated analyzer and the external control system. This allows signal transmission without physical wired connections, thereby eliminating parasitic impedance while maintaining data transmission capability.
2Reliability
If the ion energy analyzer structure is made many millimetres in height to accommodate the sensor stack, then the sensor can function properly, but it becomes difficult to deploy on a substrate with similar thickness to a process wafer and limits the vacuum pressure range
Solution Approach 1:
The patent nests the entire ion energy analyzer sensor stack, including multiple grids, insulation layers, collection electrode, power supply, and control electronics, within the substrate itself. This integration reduces the overall height requirement and allows the substrate to maintain thickness similar to standard process wafers.
Solution Approach 2:
The patent transitions from a three-dimensional protruding sensor structure to a planar integration within the substrate plane. The sensor stack is embedded within the substrate thickness, utilizing the substrate's internal volume rather than extending outward, thereby maintaining wafer-like dimensions.
3Extent of automation
If standard robotic loading systems are used to load substrates, then automated substrate handling is achieved, but the wired connections prevent easy loading of the ion energy analyzer
Solution Approach 1:
The patent removes all wired connections and external interfaces from the substrate edges, eliminating the obstacles that prevent standard robotic loading. The fully integrated wireless design allows the substrate to be loaded using conventional robotic systems without modification.
4Measurement precision
If the ion energy analyzer measures ion energy distributions in typical plasma processes requiring an energy range of a few thousand electron volts, then useful measurements can be obtained, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent employs a voltage sweep technique that dynamically changes the retarding potential applied to the analyzer grids over time. This allows the measurement of ion energy distributions across a wide energy range (a few thousand eV) using a relatively simple grid structure, avoiding the need for complex multi-stage acceleration systems.
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, enhancing process control and yield in plasma processing by integrating the analyzer directly into the substrate, reducing parasitic impedance, and allowing for robotic loading and operation at elevated temperatures.
Implementation Method 1
a first conductive grid, G0... to prevent plasma penetration inside the device, b) repel plasma electrons
Implementation Method 2
c) discriminate ions based on their energies... A succession of grids are used to... discriminate ions based on their energies
Implementation Method 3
The collector electrode terminates the stack and is used to detect the ion current signal for measurement
Data Source
AI summary
An apparatus for obtaining ion energy distribution, IED, measurements in a plasma processing system, in one example, 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, a second conductive grid, a third conductive grid, a fourth conductive grid, and a collection electrode, each grid separated by an insulation layer, a battery power supply and control circuitry, integrated in the substrate, for supplying and controlling voltage to each of the grids and the collector of the ion energy analyser; wherein at least one insulation layer includes a peripheral portion which is of reduced thickness with respect to the remaining portion of the insulation layer.