Magnetic Field Control for Twisted Dielectric Etch Profiles
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Solution Overview
Problem
Semiconductor substrate processing systems face challenges with etch uniformity and global ion tilt due to plasma density non-uniformity, leading to twisted profiles and clipping of features during high aspect ratio dielectric etch processes, particularly in 3D NAND slit features.
Innovation Solution
Implementing a tunable magnetic field source in conjunction with a flat upper electrode to generate active magnetic fields, which control plasma density uniformity and ion trajectories, minimizing systematic twisting by enhancing sheath uniformity and secondary electron generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a flat upper electrode is used without magnetic field control, then device complexity is reduced, but plasma density uniformity deteriorates leading to twisted profiles
Solution Approach 1:
A magnetic field source is introduced as an intermediary element between the flat upper electrode and the substrate to control plasma density distribution. The magnetic field acts as a mediator that shapes ion trajectories and enhances plasma uniformity without requiring complex electrode geometries, thus resolving the contradiction between simple electrode design and profile precision.
Solution Approach 2:
The patent applies magnetic field parameters (strength, direction, distribution) to control plasma behavior. By adjusting magnetic field characteristics rather than electrode shape, the system achieves precise plasma density control and profile uniformity while maintaining simple flat electrode geometry.
2Manufacturing precision
If process optimization is slowed to ensure profile control, then manufacturing precision is maintained, but productivity decreases
Solution Approach 1:
The magnetic field configuration is predetermined and pre-optimized to achieve the desired plasma density distribution and profile control. This preliminary setup eliminates the need for slow, iterative process optimization during production, allowing fast manufacturing while maintaining precise CD tolerance compliance.
Solution Approach 2:
The system incorporates monitoring and control mechanisms that provide feedback on plasma density and profile development. This enables real-time adjustments to magnetic field parameters, ensuring consistent profile control without requiring slow manual optimization cycles, thus maintaining both precision and productivity.
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 improves plasma density uniformity and sheath uniformity, reducing systematic slit twisting defects and enabling faster process optimization without hardware changes, thus maintaining high secondary electron yields and normal ion trajectories.
Implementation Method 1
at least one magnetic field source configured to generate one or more active magnetic fields through the processing zone of the vacuum chamber
Implementation Method 2
apply RF power between the upper electrode and a lower electrode of the vacuum chamber to generate the plasma within the processing zone using a process gas
Data Source
AI summary
A substrate processing apparatus includes a vacuum chamber with upper and lower electrodes and a processing zone for processing a substrate using plasma. The upper electrode includes a surface that is substantially parallel to a surface of the substrate when the substrate is positioned in the chamber. The apparatus includes at least one magnetic field source configured to generate one or more active magnetic fields through the processing zone, and a controller coupled to the at least one magnetic field source and the upper electrode. The controller is configured to apply RF power between the upper and lower electrodes to generate the plasma using a process gas. The controller controls the current through the at least one magnetic field source during the processing of the substrate, where the current is based on a target value corresponding to at least one characteristic of the one or more active magnetic fields.