Electrostatic Chuck Bias Correction for Balanced Wafer Clamping
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Solution Overview
Problem
Semiconductor processing technologies face challenges with substrate movement and nonuniform processing due to unbalanced chucking forces caused by changes in substrate DC voltage during plasma processing, leading to potential substrate damage and processing inefficiencies.
Innovation Solution
A bipolar electrostatic chuck system with power sources and ammeters measures leakage currents to estimate substrate DC voltage changes, allowing for real-time adjustment of chucking voltages to balance forces and maintain uniform processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If plasma processing is performed on the substrate, then material layers are formed and processed, but substrate DC voltage changes cause unbalanced chucking forces leading to substrate movement and nonuniform processing
Solution Approach 1:
The system measures leakage current from the substrate and uses this feedback signal to detect changes in substrate DC voltage. The controller then adjusts the chucking voltages in real-time based on this feedback to maintain balanced chucking forces and prevent substrate movement during plasma processing
Solution Approach 2:
The system dynamically changes the chucking voltage parameters applied to the electrostatic chuck electrodes. By adjusting the voltage magnitude and distribution on the electrodes based on measured leakage current, the system compensates for substrate DC voltage changes and maintains uniform chucking forces throughout the processing cycle
2Productivity
If unbalanced chucking forces are applied to the substrate, then plasma processing can be performed, but substrate damage may occur due to movement and nonuniform forces
Solution Approach 1:
The system continuously monitors leakage current to detect substrate DC voltage changes that could lead to unbalanced chucking forces. By providing real-time feedback to the controller, the system can adjust electrode voltages to prevent substrate movement and damage while maintaining continuous processing operation
Solution Approach 2:
The system proactively compensates for potential substrate damage by detecting DC voltage changes before they cause harmful substrate movement. The controller adjusts chucking voltages in advance to prevent unbalanced forces from developing, thereby cushioning against potential substrate damage before it occurs
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 helps maintain substrate flatness, prevents damage from uneven forces, and enhances thermal coupling and process uniformity, improving the reliability of semiconductor processing.
Implementation Method 1
two electrodes are disposed atop at least a portion of the electrostatic chuck body, and below the insulative substrate support surface. Each of the two power sources is operable to provide a DC voltage output to a corresponding one of the electrodes
Implementation Method 2
The ammeter is coupled in series electrical connection with a first one of the electrodes, and is configured to measure electrical current flowing to the first electrode
Implementation Method 3
Plasma generated near the substrate may transfer electric charge to the substrate, changing the voltage level of the substrate relative to its surroundings
Data Source
AI summary
A chucking system reduces differences in chucking forces that are applied by two electrodes of an electrostatic chuck, to a substrate disposed atop the chuck. Initial chucking voltages are applied to each of two electrodes, and an initial current provided to at least a first electrode of the two electrodes is measured. A process is initiated that affects a DC voltage of the substrate, then a modified current provided to at least the first electrode is measured. A modified chucking voltage for a selected one of the two electrodes is determined that will reduce chucking force imbalance across the substrate based at least on the initial current and the modified current. The modified chucking voltage is then provided to the selected one of the two electrodes.