Wafer Imaging Correction for High-Speed Robot Transfer

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Solution Overview

Problem

Existing semiconductor processing systems face challenges in accurately measuring the geometry of wafer surface features, such as film layer concentricity and width, at high speeds due to motion-induced image distortion, which affects productivity and defect detection.

Innovation Solution

A method involving capturing successive frames of an elongate stationary field of view while the wafer is in motion, correcting for motion-induced distortion using robot velocity profile information, and adjusting image coordinates to achieve accurate imaging and measurement of wafer features without slowing down the wafer transfer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the wafer is imaged during high-speed transfer, then productivity is improved, but motion-induced image distortion occurs reducing measurement precision

Engineering Contradiction:

Improvewafer transfer speedVSAvoidimage accuracy

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The system captures images at predetermined locations along the wafer transfer path where the wafer reaches specific positions. By pre-determining optimal imaging locations and timing, the system captures accurate images during motion without requiring speed reduction, thus maintaining both productivity and measurement precision

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system uses feedback from the robot controller regarding wafer position and velocity to dynamically adjust imaging timing and correct motion-induced distortion. This feedback mechanism allows the system to compensate for motion effects in real-time, enabling accurate measurements during high-speed transfer

Inventive Principle:

Principle #23Feedback

2Measurement precision

If the wafer is slowed down or stopped for imaging, then measurement precision is improved, but productivity deteriorates

Engineering Contradiction:

Improveimage accuracyVSAvoidwafer transfer speed

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The system pre-determines optimal imaging locations along the transfer path and captures images at these predetermined positions during normal-speed transfer. This eliminates the need to slow down or stop the wafer, maintaining both measurement precision and productivity

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system replaces the mechanical approach of slowing down or stopping the wafer for imaging with an optical and computational approach. By using high-speed imaging combined with motion distortion correction algorithms, the system achieves accurate measurements without mechanical speed reduction

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Area of stationary object

If in-situ measurement is implemented, then space utilization is improved, but measurement precision deteriorates due to motion distortion

Engineering Contradiction:

Improvefabrication areaVSAvoidfilm edge measurement accuracy

Core Design Contradiction:

Area of stationary objectVSMeasurement precision

Solution Approach 1:

The system incorporates feedback from robot position and velocity sensors to correct for motion-induced distortion in in-situ images. This feedback mechanism enables accurate film edge measurements to be taken during high-speed transfer through the factory interface, maintaining measurement precision while utilizing in-situ measurement space efficiency

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS8452077B2Method for imaging workpiece surfaces at high robot transfer speeds with correction of motion-induced distortion

Publication Date: 2013.05.28 APPLIED MATERIALS INC

AI summary

A method is provided for imaging a workpiece by capturing successive frames of an elongate stationary field of view transverse to a workpiece transit path of a robot, while the workpiece is transported by the robot. The robot transit path is illuminated with an elongate illumination pattern transverse to the transit path to obtain a workpiece image of successive frames. Motion-induced image distortion is corrected by computing respective correct locations of respective ones of the frames along the transit path.