Electro-Optic Electric Field Sensing for Real-Time Plasma Bias Control
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Solution Overview
Problem
Conventional RF plasma-assisted etching processes fail to adequately control sheath properties and ion energies, leading to undesirable plasma processing results such as excessive sputtering of mask layers and sidewall defects in high-aspect ratio features, and lack real-time measurement and control of substrate potential during semiconductor manufacturing.
Innovation Solution
An electric field measurement system using electro-optic sensors with optical fibers and a controller to detect and adjust plasma processing parameters in real-time, compensating for temperature and orientation dependencies, allowing for precise control of substrate bias and ion energy distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional RF plasma-assisted etching processes are used to form high aspect ratio features, then etching can be performed, but sheath properties and ion energies cannot be adequately controlled, leading to excessive sputtering of mask layers and sidewall defects
Solution Approach 1:
The patent implements real-time measurement of substrate potential during plasma processing using electro-optic sensors. The measured substrate potential is fed back to the control system, which adjusts the RF power and other process parameters to maintain the desired substrate bias and ion energy distribution. This closed-loop feedback control enables precise control of sheath properties and ion energies, resolving the contradiction between manufacturing precision and ease of operation.
Solution Approach 2:
The patent replaces conventional electrical measurement methods with electro-optic sensing technology. Instead of using electrical probes that can disturb the plasma, the system uses electro-optic crystals that convert electric field information into optical signals, which are then detected by photodetectors. This substitution enables non-intrusive real-time measurement of substrate potential, facilitating precise control without compromising plasma quality.
2Reliability
If real-time measurement of substrate potential is implemented, then plasma processing parameters can be controlled, but the system complexity increases due to additional sensors and control mechanisms
Solution Approach 1:
The patent introduces electro-optic crystals as intermediary elements that mediate between the electric field in the plasma and the detection system. These crystals convert the electric field information into optical signals without directly contacting the plasma or requiring complex electrical connections. This intermediary approach simplifies the overall system architecture while enabling reliable real-time measurement and control of plasma parameters.
3Measurement precision
If electro-optic sensors are used to detect electric fields, then real-time monitoring is achieved, but temperature and orientation dependencies affect measurement accuracy
Solution Approach 1:
The patent implements self-diagnostic and self-correction capabilities within the control system. The system continuously monitors sensor outputs and automatically compensates for temperature drift and orientation effects using pre-characterized correction factors and real-time environmental sensing. This self-service approach maintains measurement precision without requiring manual calibration or intervention, ensuring reliable sensor performance under varying conditions.
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 real-time monitoring and control of plasma processes, improving feature profile control, reducing defects, and enhancing the reliability of high-aspect ratio etching in semiconductor manufacturing by accurately measuring and adjusting electric fields within the plasma processing chamber.
Implementation Method 1
an electro-optic sensor that includes an electro-optic crystal... the optical fiber is configured to transmit electromagnetic energy... to a surface of the electro-optic crystal... the electromagnetic energy that was transmitted to the surface of the electro-optic crystal and subsequently passed through at least a portion of the electro-optic crystal
Data Source
AI summary
Disclosed herein is an electric field measurement system that includes a light source, a light sensor configured to receive electromagnetic energy transmitted from the light source, an electro-optic sensor, and a controller. The electro-optic sensor include a package comprising an electro-optic crystal disposed and at least one optical fiber. The optical fiber is configured to transmit electromagnetic energy transmitted from the light source to a surface of the electro-optic crystal, and transmit at least a portion of the electromagnetic energy transmitted to the surface of the electro-optic crystal and subsequently passed through at least a portion of the electro-optic crystal to the light sensor that is configured to generate a signal based on an attribute of the electromagnetic energy received by the light sensor from the at least one optical fiber. The controller is configured to generate a command signal based on a signal received from the light sensor.