RF Voltage and Current Sensor Assembly for Precise Plasma Metrology
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Solution Overview
Problem
Current plasma processing systems for semiconductor IC fabrication face challenges in achieving precise control of RF signals due to the lack of accurate and unobtrusive metrology for RF voltage and current measurements, which affects the precision and repeatability of plasma processes, especially at the atomic scale dimensions required for advanced IC designs.
Innovation Solution
The development of a radio frequency (RF) sensor assembly with a sensor casing and cavity design that includes a dielectric material, a current sensor with a conductive ridge and toroidal mandrel, and a voltage sensor with a ring-shaped pickup, allowing for precise measurement of voltage, current, and phase angle of RF signals with minimal disturbance to the plasma process, enabling improved control and repeatability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional RF measurement methods are used, then measurement capability is provided, but measurement precision and accuracy are insufficient for atomic scale plasma control
Solution Approach 1:
The patent introduces an intermediary RF sensor assembly that couples to the RF signal without directly interfering with the plasma process. The sensor uses a pickup electrode and coupling capacitor to indirectly measure RF voltage and current, acting as a mediator between the plasma environment and measurement instrumentation. This intermediary approach enables precise measurements while maintaining plasma process integrity.
Solution Approach 2:
The patent replaces direct mechanical/probe-based measurement methods with an electromagnetic field-based sensing system. The RF sensor assembly uses electromagnetic coupling through capacitive and inductive elements to measure RF parameters, substituting physical contact methods with field-based measurement. This substitution reduces measurement intrusion and improves precision for atomic scale plasma control.
2Measurement precision
If RF sensors are introduced to improve measurement accuracy, then measurement capability is enhanced, but device complexity increases
Solution Approach 1:
The RF sensor assembly is designed to perform multiple measurement functions (voltage, current, phase angle) using a single integrated device. The sensor can measure different RF parameters by configuring which electrodes are active, eliminating the need for separate sensors for each measurement type. This multi-functionality reduces overall system complexity while maintaining high measurement precision.
Solution Approach 2:
The patent combines voltage sensing and current sensing capabilities into a single RF sensor assembly. The pickup electrode and sense electrode work together within one housing, sharing common components like the coupling capacitor and impedance matching circuitry. This merging of functions reduces the number of separate devices needed and simplifies the overall measurement system.
3Device complexity
If conventional measurement approaches are used, then simplicity is maintained, but measurement disturbance to plasma process increases
Solution Approach 1:
The patent extracts the measurement function from the main plasma processing system by using a separate, externally coupled RF sensor assembly. The sensor is positioned to couple with RF signals without being physically immersed in the plasma, separating the measurement apparatus from the plasma environment. This extraction minimizes plasma disturbance while maintaining measurement capability.
Solution Approach 2:
The RF sensor assembly uses thin dielectric layers and flexible coupling structures to interface with RF signals. The coupling capacitor and impedance matching network use thin-film techniques to create minimal physical presence in the RF path. This approach maintains measurement simplicity while reducing plasma process disturbance through minimalistic sensor construction.
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 RF sensor assembly provides high-precision measurements of RF signals, enhancing the control and repeatability of plasma processes without increasing costs, allowing for better plasma processing systems that maintain precision at the atomic scale dimensions needed for advanced IC designs.
Implementation Method 1
a current sensor electrically insulated from the sensor casing and including a current pickup disposed symmetrically around the central hole
Implementation Method 2
a cavity disposed around the central hole and including a dielectric material, the cavity being bounded by a first major outer surface and a second major outer surface
Data Source
AI summary
A radio frequency sensor assembly includes a sensor casing disposed around a central hole, the sensor casing including a first conductive cover and a second conductive cover. The assembly includes a cavity disposed around the central hole and includes a dielectric material, the cavity being bounded by a first major outer surface and a second major outer surface along a radial direction from a center of the central hole, where the first conductive cover is electrically coupled to the second conductive cover through a coupling region beyond the second major outer surface of the cavity, and electrically insulated from the second conductive cover by the cavity and the central hole. The assembly includes a current sensor electrically insulated from the sensor casing and including a current pickup disposed symmetrically around the central hole, the current pickup being disposed within the cavity and being insulated from the sensor casing.