ESC-Edge Ring Power Balancing for Wafer Edge Ion Tilt Control
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Solution Overview
Problem
Modern semiconductor chip fabrication processes face challenges with non-uniformity of features along the extreme edge of the wafer due to ion angular spread, which is not effectively addressed by existing technologies.
Innovation Solution
Measuring RF and pulsed DC current at the interface between an electrostatic chuck and an edge ring to balance power and/or voltages, adjusting phase and amplitude to achieve a desired ion tilt at the wafer edge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If existing technologies are used to control ion tilt, then the system is simple to operate, but the feature uniformity at the wafer edge deteriorates due to ion angular spread
Solution Approach 1:
The system measures the actual ion tilt angle at the wafer edge using a tilt sensor, compares it with the desired angle, and automatically adjusts the RF power distribution between the electrostatic chuck and edge ring to minimize the difference. This closed-loop feedback control achieves precise feature uniformity while automating the complex adjustments.
Solution Approach 2:
The patent replaces manual mechanical adjustment of power distribution with an automated electronic control system that uses electrical measurements and signal processing to determine ion tilt and adjust power ratios, thereby improving precision without requiring complex manual mechanical systems.
2Manufacturing precision
If RF power is increased to reduce ion angular spread, then feature uniformity improves, but power consumption increases
Solution Approach 1:
The system dynamically changes the RF power distribution parameters between the electrostatic chuck and edge ring based on real-time ion tilt measurements. By optimizing the power ratio rather than simply increasing total power, the system achieves the desired ion tilt and feature uniformity while minimizing overall power consumption.
Solution Approach 2:
The control system automatically monitors ion tilt and self-adjusts the power distribution to achieve optimal uniformity, eliminating the need for excessive power input and reducing energy waste while maintaining precise control over the etching process.
3Manufacturing precision
If manual adjustment of power signals is performed, then the control mechanism is simple, but the accuracy of ion tilt control deteriorates
Solution Approach 1:
A tilt sensor provides real-time feedback on the actual ion tilt angle at the wafer edge. This measurement is fed back to the control system, which automatically adjusts the RF power distribution to achieve the desired tilt angle, thereby improving control accuracy through automated feedback rather than manual adjustment.
Solution Approach 2:
The control system integrates multiple functions including ion tilt measurement, signal processing, power ratio calculation, and automated power adjustment into a single multi-functional unit. This universal system achieves high precision ion tilt control while consolidating what would otherwise require multiple separate complex subsystems.
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 provides a more accurate and direct control mechanism for achieving a desired ion tilt, improving feature uniformity and reducing power consumption in semiconductor fabrication.
Implementation Method 1
a radio frequency (RF) signal provides power and is applied to at least one of the electrodes of the plasma processing chamber to form an electric field between the electrodes. The process gas is turned into plasma by the RF signal
Implementation Method 2
The process gas is turned into plasma by the RF signal, thereby performing plasma etching on a predetermined layer disposed on the wafer
Implementation Method 3
providing a first power signal to an electrostatic chuck (ESC) within a plasma chamber. The method including providing a second power signal to an edge ring within the plasma chamber
Implementation Method 4
determining a phase relationship between a phase of the low frequency current signal and a phase of a reference signal to determine a direction of ion tilt at the interface between the ESC and the edge ring
Implementation Method 5
measuring an amplitude of a low frequency current signal occurring at an interface between the ESC and the edge ring. The method including adjusting one or more parameters of the first power signal and the second power signal to achieve a minimum amplitude of the low frequency current signal
Data Source
AI summary
A method performed within a plasma chamber. The method including providing a first power signal to an electrostatic chuck (ESC). The method including providing a second power signal to an edge ring. The method including measuring an amplitude of a current signal occurring at an interface between the ESC and the edge ring. The method including adjusting one or more parameters of the first power signal and the second power signal to achieve a minimum amplitude of the current signal. The method including determining a phase relationship between a phase of the current signal and a phase of a reference signal to determine a direction of ion tilt at the interface. The method including adjusting at least one parameter of the second power signal to achieve a predetermined angle of the ion tilt at the interface based on the phase relationship and the amplitude of the current signal.