Dry Etcher OES Calibration for Low-Flow Plasma Beam Control
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Solution Overview
Problem
In plasma dry etching processes for semiconductor manufacturing, controlling the intensity of the plasma beam at low flow rates of etching gas is challenging due to non-linear relationships, leading to inaccuracies in etching rates and potential bridging issues during via formation.
Innovation Solution
A method involving a plasma etcher with a flow rate controller recalibrated using optical emission spectroscopy (OES) to detect emitted light from plasma discharge, allowing for precise adjustment of etching gas flow rates and generation of low-intensity plasma beams, which are used to etch substrates with improved control and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the flow rate of etching gas is reduced to generate low-intensity plasma beams, then the etching intensity is reduced for fine-tuning shapes, but the control accuracy deteriorates due to non-linear relationships
Solution Approach 1:
The system uses optical emission spectroscopy (OES) to monitor plasma parameters in real-time and provides feedback to the flow rate controller. This closed-loop feedback mechanism allows the system to compensate for non-linear relationships at low flow rates, maintaining control accuracy even when operating at reduced plasma beam intensities for fine-tuning etched shapes.
Solution Approach 2:
The patent replaces direct mechanical flow control with an optical measurement and control system. By using OES to detect plasma emission spectra and correlating these with flow rate, the system substitutes mechanical control mechanisms with an optical-field-based measurement and control approach, enabling more precise control at low flow rates where mechanical control becomes non-linear.
2Measurement precision
If the flow rate controller is recalibrated using OES signal, then the control precision is improved to less than 1% accuracy, but the device complexity increases
Solution Approach 1:
The patent introduces an intermediary measurement system using optical emission spectroscopy as a mediator between the flow rate controller and the actual gas flow. The OES system measures plasma emission characteristics that correlate with flow rate, providing an indirect but highly accurate measurement method that achieves less than 1% precision without requiring complex direct flow measurement instruments.
3Manufacturing precision
If low flow rates are used for plasma beam generation, then the etching selectivity is improved for via formation, but the reliability of flow control deteriorates
Solution Approach 1:
The real-time OES monitoring provides continuous feedback that compensates for flow control instabilities at low flow rates. By detecting plasma emission signals and correlating them with flow rate, the system can dynamically adjust to maintain reliable control even when operating at low flow rates required for high selectivity via formation.
Solution Approach 2:
The system changes the measurement parameter from direct mechanical flow sensing to optical emission spectroscopy parameters. By monitoring plasma emission spectra and using these optical parameters to infer and control flow rate, the system achieves reliable control at low flow rates where traditional mechanical sensing becomes unreliable.
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 approach enables precise control over etching processes, reducing the probability of bridging and achieving accurate etching with critical dimensions as small as 3 nm, with a calibrated precision of less than 1% accuracy.
Implementation Method 1
monitoring emitted light generated by plasma discharge corresponding to the one or more plasma beams
Data Source
AI summary
In a method of controlling a plasma beam of a plasma etcher a flow rate controller of the plasma etcher is set to generate one or more flow rates of an etching gas corresponding to one or more plasma beams of the plasma etcher. The emitted light generated by plasma discharge corresponding to the one or more plasma beams of the plasma etcher is monitored. The flow rate controller is calibrated based on the one or more flow rates and a corresponding emitted light of the plasma discharge.