Segmented RF Return Paths for Uniform Plasma Profiles
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Solution Overview
Problem
Non-uniform plasma profiles in the reaction chamber of substrate processing systems lead to on-wafer non-uniformity issues during Plasma Enhanced Atomic Layer Deposition (PEALD) and sputtering processes.
Innovation Solution
A plasma modulation apparatus that adjusts the impedances of radio frequency (RF) return paths to the ground, using a susceptor divided into multiple meshes connected to RF paths with Voltage-Current sensors and variable impedance circuits, to achieve uniform plasma profiles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the susceptor is divided into multiple meshes with separate RF paths, then plasma profile uniformity is improved, but device complexity increases
Solution Approach 1:
The susceptor is divided into multiple meshes (N≥2), with each mesh connected to a separate RF path. This segmentation allows independent control of plasma generation in different regions, enabling uniform plasma profiles across the wafer surface while maintaining manageable system complexity through modular architecture.
Solution Approach 2:
Each mesh is equipped with its own variable impedance circuit and VI sensor, allowing local adjustment of plasma characteristics. This local quality control enables precise regulation of plasma density and uniformity across different regions of the reaction chamber, directly improving on-wafer deposition uniformity.
2Manufacturing precision
If variable impedance circuits are used to equalize currents, then plasma profile uniformity is improved, but device complexity increases
Solution Approach 1:
VI sensors are integrated into each RF path to measure voltage and current, providing real-time feedback to the control system. This feedback mechanism enables automatic adjustment of variable impedance circuits to equalize currents across all RF paths, achieving uniform plasma profiles while reducing the need for manual tuning and complex control logic.
Solution Approach 2:
Variable impedance circuits are employed to dynamically adjust electrical parameters (impedance values) in each RF path. By changing these parameters based on measured current levels, the system equalizes plasma generation across all meshes, improving plasma profile uniformity without requiring complex mechanical adjustments.
3Measurement precision
If RF paths are grounded separately for each mesh, then plasma control precision is improved, but device complexity increases
Solution Approach 1:
Each RF path is provided with a separate ground connection, creating electrically independent measurement and control paths. This segmentation eliminates ground loops and interference between adjacent RF paths, enabling precise current measurements and accurate plasma control in each mesh region.
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 apparatus ensures on-wafer uniformity for deposition and sputter processes by equalizing the currents measured by Voltage-Current sensors, thereby stabilizing and uniformizing the plasma profiles within the reaction chamber.
Implementation Method 1
a Voltage-Current (VI) sensor connected to the RF rod and configured to measure a current from the RF rod
Implementation Method 2
a variable impedance circuit connected to the VI sensor and configured to change an impedance of the RF path and further configured to be grounded
Implementation Method 3
an RF rod connected to a mesh and configured to transmit RF signal from the meshes
Implementation Method 4
an RF filter configured to filter out noise from the RF rod
Data Source
AI summary
A plasma modulation apparatus for use in a substrate processing system is disclosed. The apparatus comprising: a plurality of radio frequency (RF) paths connected to N different meshes, wherein a susceptor of the substrate processing system is divided into the N different meshes and N is an integer equal to or greater than 2, wherein each of the RF paths comprises: an RF rod connected to a mesh and configured to transmit RF signal from the meshes; a Voltage-Current (VI) sensor connected to the RF rod and configured to measure a current from the RF rod; and a variable impedance circuit connected to the VI sensor and configured to change an impedance of the RF path and further configured to be grounded, wherein each of the RF paths are grounded separately and each of the RF paths corresponds to a different mesh, respectively.