Sonar Wafer Detection in Processing Chambers for Transparent Wafers
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Solution Overview
Problem
Existing detection equipment, such as light source detectors, are ineffective for transparent wafers in semiconductor fabrication due to low reflectivity, leading to reduced reliability in processing steps like wafer presence detection and alignment.
Innovation Solution
Employing a sonar sensor with an emitter and detector to utilize sound waves for detecting the presence and alignment of wafers, including transparent ones, by measuring sonar intensity values to determine distances and verify wafer placement within processing chambers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If light source detectors are used to detect wafer presence and alignment, then the detection system is simple and cost-effective, but transparent wafers cannot be reliably detected due to low reflectivity
Solution Approach 1:
The patent replaces optical detection systems with acoustic detection systems. Specifically, ultrasonic sensors emit sound waves that penetrate transparent wafer materials, and the reflected or transmitted sound waves are detected to determine wafer presence, position, and alignment. This mechanical/acoustic approach overcomes the limitation of optical methods with transparent materials.
Solution Approach 2:
The patent changes the detection parameter from optical reflectivity to acoustic impedance. By using ultrasonic waves with specific frequencies and measuring their interaction with the wafer material, the system can detect transparent wafers that are invisible to optical detectors. The acoustic parameters (frequency, wavelength, impedance) are optimized for the specific wafer materials.
2Reliability
If ultrasonic sensors are used to detect transparent wafers, then detection reliability for transparent materials improves, but device complexity increases
Solution Approach 1:
The patent introduces an ultrasonic coupling medium (such as a liquid or gel) between the ultrasonic sensor and the wafer surface. This intermediary ensures efficient transmission of acoustic energy into the transparent wafer material, improving detection reliability while keeping the sensor design relatively simple. The coupling medium compensates for air gaps and enhances acoustic coupling.
3Adaptability or versatility
If multiple detection methods are implemented to handle both transparent and opaque wafers, then detection versatility improves, but processing time and system complexity increase
Solution Approach 1:
The patent implements a universal ultrasonic detection system that can detect both transparent and opaque wafers using the same basic mechanism. The ultrasonic waves interact with all materials (transparent or opaque) through acoustic impedance differences, allowing a single detection system to handle all wafer types without requiring separate detection paths or switching between different detection methods.
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
Enhances the reliability of semiconductor fabrication processes by accurately detecting wafer presence and alignment, regardless of material transparency, thereby preventing errors and improving processing step control.
Implementation Method 1
the sonar sensor comprises: an emitter configured to emit sound waves towards the wafer chuck, and a detector configured to receive reflected sound waves
Data Source
AI summary
In some embodiments, the present disclosure relates a process tool that includes a chamber housing defining a processing chamber. Within the processing chamber is a workpiece holder apparatus that is configured to hold a workpiece. A sonar sensor is arranged over the workpiece holder apparatus. The sonar sensor includes an emitter that is configured to produce sound waves traveling towards the workpiece holder apparatus. The sonar sensor also includes a detector that is configured to receive reflected sound waves from the workpiece holder apparatus or an object between the sonar sensor and the workpiece holder apparatus. Further, sonar sensor control circuitry is coupled to the sonar sensor and is configured to determine if a workpiece is present on the workpiece holder apparatus based on a sonar intensity value of the reflected sound waves received by the detector of the sonar sensor.