Dynamic Wafer Position Error Compensation in E-Beam Inspection
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Solution Overview
Problem
Position errors during the transfer of wafers in semiconductor manufacturing processes, particularly in electron beam inspection systems, lead to misprocessing and reduced yield due to the limitations of existing inspection systems and calibration methods, causing time delays and reduced throughput.
Innovation Solution
A system comprising sensing units that generate signals based on the position of a sample and a controller to determine the position, allowing for dynamic compensation of errors without unloading and reloading the wafer, thereby improving transfer accuracy and throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a second calibration wafer is used to determine drift value, then position measurement can be obtained, but measurement reliability is reduced and time delays increase
Solution Approach 1:
The patent uses an optical image (copy) of the wafer surface features detected by the sensor to determine position, rather than requiring a physical second calibration wafer. The sensor detects light reflected from or transmitted through the wafer surface, creating an optical representation that is processed to extract position information, thereby avoiding the need for physical comparison wafers while maintaining measurement capability
Solution Approach 2:
The patent replaces the mechanical approach of using physical calibration wafers with an optical detection system. A sensor optically detects wafer surface features and a controller processes the optical signal to determine position, substituting mechanical wafer handling and comparison with optical-field-based measurement, which improves both reliability and reduces time delays
2Manufacturing precision
If wafer is unloaded and reloaded with corrected position, then position errors can be corrected, but throughput is reduced
Solution Approach 1:
The patent performs preliminary position detection and correction during the wafer transfer process itself, before the wafer is fully loaded into the inspection chamber. The sensor detects position errors and the controller adjusts the transfer mechanism in real-time, correcting position accuracy without requiring the wafer to be unloaded and reloaded, thereby maintaining high throughput
Solution Approach 2:
The patent implements a feedback control system where a sensor continuously monitors wafer position during transfer, and the controller receives this feedback to dynamically adjust the transfer mechanism. This closed-loop feedback enables real-time position correction during the transfer process, eliminating the need for stop-and-reload operations and maintaining high productivity
3Measurement precision
If relative measurement with calibration wafer is used, then position can be determined, but reliability is reduced compared to absolute measurement
Solution Approach 1:
The patent creates an optical copy of the wafer surface features through light reflection or transmission detected by the sensor. This optical representation allows the system to reference absolute position markers or features on the wafer itself rather than requiring comparison with a separate calibration wafer, enabling more reliable absolute position determination
Solution Approach 2:
The patent replaces the mechanical comparison method (physical calibration wafer) with an optical detection method. The sensor optically detects features directly on the inspection wafer and the controller processes these optical signals to determine absolute position, eliminating the need for physical calibration wafers and providing more reliable measurements
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 solution enhances the accuracy of wafer transfers and increases semiconductor manufacturing yield by enabling real-time correction of position errors within the electron beam inspection system, reducing time delays and improving process efficiency.
Implementation Method 1
one or more sensing units configured to generate a signal based on a position of a sample
Data Source
AI summary
Systems and methods are provided for dynamically compensating position errors of a sample. The system can comprise one or more sensing units configured to generate a signal based on a position of a sample and a controller. The controller can be configured to determine the position of the sample based on the signal and in response to the determined position, provide information associated with the determined position for control of one of a first handling unit in a first chamber, a second handling unit in a second chamber, and a beam location unit in the second chamber.