RF Return Path Impedance Control for Plasma Uniformity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Plasma-based systems face challenges in controlling uniformity of plasma etching and deposition processes due to difficulties in managing standing waves, leading to non-uniform material etching and deposition on wafers, resulting in reduced yield.
Innovation Solution
The system controls the impedance of the radio frequency (RF) return path by adjusting capacitance and inductance between the impedance match circuitry and the plasma reactor, using a switch circuit and a controller to implement a tune recipe for achieving uniform etch or deposition rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If impedance of RF return path is controlled by adjusting capacitance and inductance, then uniformity of etch or deposition rates is improved, but device complexity increases
Solution Approach 1:
The patent applies parameter changes by adjusting capacitance and inductance values in the RF return path to control impedance. The system modifies electrical parameters (capacitance C and inductance L) to achieve impedance matching, which eliminates standing waves and ensures uniform plasma distribution across the wafer surface, thereby improving etch or deposition rate uniformity.
Solution Approach 2:
The patent introduces an intermediary impedance control circuit between the RF generator and the plasma reactor. This intermediary component includes adjustable capacitors and inductors that mediate the RF signal transmission, allowing precise control of the RF return path impedance to eliminate standing waves without modifying the plasma reactor itself.
2Manufacturing precision
If standing waves in plasma are controlled, then uniformity of plasma etching or depositing is improved, but difficulty in controlling plasma properties remains
Solution Approach 1:
The patent replaces direct mechanical or physical control of plasma properties with an electrical field-based approach. By controlling the RF return path impedance through electrical components (capacitors and inductors), the system indirectly controls plasma distribution without requiring direct measurement or manipulation of plasma parameters, thereby simplifying the control mechanism.
Solution Approach 2:
The patent implements feedback control by monitoring the RF return path and adjusting capacitance and inductance values to maintain optimal impedance matching. The system uses RF power reflection measurements to detect standing waves and dynamically adjusts the impedance control circuit parameters to eliminate them, ensuring uniform plasma distribution.
3Measurement precision
If impedance match circuitry is positioned closer to plasma reactor, then control precision is improved, but loss of energy in RF return path increases
Solution Approach 1:
The patent applies dynamics by making the impedance control circuit adjustable and adaptable rather than fixed. The capacitance and inductance values can be dynamically tuned to optimize performance for different operating conditions, allowing the system to balance between control precision and energy efficiency by positioning and configuring components optimally.
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 ensures uniformity in etch or deposition rates across the substrate, reducing non-uniformities and enhancing wafer yield by precisely controlling the impedance of the RF return path.
Implementation Method 1
The impedance is controlled by controlling a capacitance and/or an inductance between an impedance match circuitry of the plasma tool and a plasma reactor of the plasma tool
Implementation Method 2
The impedance is controlled by controlling a capacitance and/or an inductance between an impedance match circuitry of the plasma tool and a plasma reactor of the plasma tool
Implementation Method 3
The system includes an RF generator coupled to the matchbox to supply an RF supply signal to the matchbox via a first portion of an RF supply path
Data Source
AI summary
A system for controlling an impedance of a radio frequency (RF) return path includes a matchbox further including a match circuitry. The system further includes an RF generator coupled to the matchbox to supply an RF supply signal to the matchbox via a first portion of an RF supply path. The RF generator is coupled to the matchbox to receive an RF return signal via a first portion of an RF return path. The system also includes a switch circuit and a plasma reactor coupled to the switch circuit via a second portion of the RF return path. The plasma reactor is coupled to the match circuitry via a second portion of the RF supply path. The system includes a controller coupled to the switch circuit, the controller configured to control the switch circuit based on a tune recipe to change an impedance of the RF return path.