Non-Contact Wafer Chuck Sensing for Accurate Engagement Detection

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Solution Overview

Problem

Existing semiconductor wafer transport methods using non-contact chucks face challenges in accurately determining whether the chuck has engaged or disengaged from the wafer due to variations in light reflection caused by wafer type, circuit pattern, and surface color, leading to errors in judgment.

Innovation Solution

The method employs an optical sensor to measure and compare the intensity of reflected light from the wafer surface before and after the non-contact chuck engages and disengages, using stored intensity values to accurately determine the chuck's engagement status, independent of wafer type or surface characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a reflective sensor is used to determine chuck engagement by comparing reflected light intensity with a preset threshold, then the determination process is simple, but errors in judgment occur due to variations in light reflection caused by wafer type, circuit pattern, and surface color

Engineering Contradiction:

Improvedetermination process simplicityVSAvoidengagement determination accuracy

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The system performs preliminary measurement of the actual wafer's reflected light intensity before engagement determination. This preliminary action captures the specific optical characteristics of the wafer being processed, which are then used as a reference for accurate engagement detection, eliminating the need for generic preset thresholds that fail to account for wafer variations

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system uses the measured reflected light intensity as feedback to dynamically adjust the engagement determination criterion. By comparing the actual measurement with the preliminarily measured reference value, the system adapts to different wafer types, patterns, and surface colors, ensuring reliable determination across varying conditions

Inventive Principle:

Principle #23Feedback

2Device complexity

If preset threshold values are used for engagement determination, then the control logic is simple, but the system cannot adapt to different wafer types, circuit patterns, and surface colors

Engineering Contradiction:

Improvecontrol logic complexityVSAvoidwafer type adaptability

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The system changes the determination parameter from a fixed preset threshold to a dynamically measured reference value. By measuring the actual reflected light intensity of the specific wafer being processed, the system adapts its determination criterion to match the wafer's optical properties, enabling versatility across different wafer types while maintaining relatively simple control logic

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The system performs self-calibration by automatically measuring the optical characteristics of each wafer and using that measurement as the basis for engagement determination. This self-service approach eliminates the need for external calibration procedures or complex adaptive algorithms, achieving versatility through straightforward self-measurement

Inventive Principle:

Principle #25Self-service

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 reduces errors in determining chuck engagement by accounting for variations in wafer type and surface conditions, ensuring reliable transport of semiconductor wafers and stacked wafers with interlayer papers.

Implementation Method 1

measuring a first intensity, which is the intensity of a reflected light from the first main surface, by the optical sensor before bringing the non-contact chuck close to the first main surface and illuminating the first main surface with the light

Methodology Applied

Scientific EffectLight reflection: Reflection

Data Source

PatentUS20250246468A1Semiconductor wafer transfer method and semiconductor wafer transfer device

Publication Date: 2025.07.31 RENESAS ELECTRONICS CORP

AI summary

The method for transporting the semiconductor wafer involves the steps of preparing the non-contact chuck provided with an optical sensor and the semiconductor wafer having a first main surface, positioning the non-contact chuck so that the optical sensor and the first main surface face each other with a predetermined interval therebetween, measuring a first intensity, which is the intensity of a reflected light from the first main surface, by illuminating the first main surface with a light from the optical sensor before bringing the non-contact chuck close to the first main surface, bringing the non-contact chuck close to the first main surface and maintaining the semiconductor wafer in a non-contact state by blowing gas to the first main surface from the non-contact chuck, and disengaging the non-contact chuck from the semiconductor wafer by moving the non-contact chuck away from the first main surface.