Reflectometer Monitoring for Wafer De-Chucking Movement
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Solution Overview
Problem
Residual electrostatic chucking forces cause unwanted substrate movement, such as bending, tilting, and breaking, during the de-chucking process in semiconductor processing due to trapped electric charges, which existing technologies fail to adequately detect and mitigate.
Innovation Solution
Employing reflectometers that sense reflected and scattered light from the substrate to monitor its position and movement, allowing for detection of successful de-chucking and prevention of substrate breakage by analyzing changes in the returned signal intensity and noise patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the lift pins are raised to lift the substrate off the ESC during de-chucking, then the substrate can be removed from the electrostatic chuck, but residual chucking forces cause unwanted substrate movement such as bending, tilting, and breaking
Solution Approach 1:
The system performs preliminary detection of substrate position and movement before the substrate is fully lifted off the ESC. By monitoring the substrate during the critical transition phase when residual forces are strongest, the system can detect abnormal movements (bending, tilting) and prevent breakage before it occurs
Solution Approach 2:
The reflectometer provides continuous feedback on substrate position and movement during the de-chucking process. This feedback allows the system to monitor for residual chucking forces and their effects on substrate integrity in real-time, enabling corrective actions if abnormal movements are detected
2Device complexity
If existing technologies are used without reflectometer monitoring, then the system is simpler and less expensive, but substrate movement and breakage cannot be detected or mitigated
Solution Approach 1:
The patent replaces complex mechanical monitoring systems with an optical detection system (reflectometer). Instead of using mechanical sensors that would require direct contact with the substrate and complex installation, the system uses light reflection to non-contactively monitor substrate position and movement, achieving reliable detection while maintaining system simplicity
Solution Approach 2:
The reflectometer acts as an intermediary between the de-chucking process and the control system. It provides indirect but accurate information about substrate position and movement through light reflection, enabling detection of residual chucking forces without requiring direct mechanical interaction with the substrate
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
Effectively prevents substrate breakage and ensures safe release by accurately detecting substrate movement and residual chucking forces, reducing the risk of damage and improving processing reliability.
Implementation Method 1
reflectometers that sense reflected and scattered light from the substrate to monitor its position and movement
Implementation Method 2
reflectometers that sense reflected and scattered light from the substrate to monitor its position and movement
Data Source
AI summary
Various embodiments include a reflectometer and a reflectometry system for monitoring movements of a substrate, such as a silicon wafer. In one embodiment, a reflectometry system monitors and controls conditions associated with a substrate disposed within a process chamber. The process chamber includes a substrate-holding device having an actuator mechanism to control movement of the substrate with respect to the substrate-holding device. The reflectometry system includes a light source configured to emit a beam of light directed at the substrate, collection optics configured to receive light reflected from the substrate by the beam of light directed at the substrate and output a signal related to one or more conditions associated with the substrate, and a processor configured to process the signal and direct the actuator mechanism to control the movement of the substrate with respect to the substrate-holding device based on the signal. Other devices and methods are disclosed.