Bonded Wafer Edge Metrology for Centricity Offset Detection

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Solution Overview

Problem

Bonded wafers with improper centricity cause manufacturing issues during CMP processes, leading to undesired edge profiles, device yield impact, and potential equipment damage.

Innovation Solution

A metrology system and method that analyze wafer edge profile images to determine the X and Y offsets between bonded wafers, using image processing techniques and a sinusoidal model to calculate the center positions and displacement of the wafers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If bonded wafers are used with complex edge profiles and different layer heights, then three-dimensional integrated circuits can be produced, but centricity problems arise that affect CMP process and handling

Engineering Contradiction:

Improve3D IC production capabilityVSAvoidcentricity

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The patent performs wafer edge profile analysis and centricity measurement before the CMP process using a metrology system. By detecting and calculating the offset between the bonded wafer center and carrier wafer center in advance, the system enables preliminary correction or adjustment, preventing centricity-related defects during subsequent manufacturing steps.

Inventive Principle:

Principle #10Preliminary action

2Ease of manufacture

If traditional metrology methods are used for bonded wafers, then simple measurements can be performed, but complex edge profiles and varying layer heights cannot be accurately measured

Engineering Contradiction:

Improvemeasurement simplicityVSAvoidwafer-to-wafer displacement measurement

Core Design Contradiction:

Ease of manufactureVSMeasurement precision

Solution Approach 1:

The patent transforms the measurement approach by analyzing the wafer edge profile shape and applying a sinusoidal model to extract centricity information. Instead of direct physical contact measurement, the system uses optical imaging combined with mathematical modeling, changing the measurement parameters from direct displacement sensing to edge profile characterization.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces traditional mechanical measurement methods with an optical-based metrology system. The system uses imaging to capture wafer edge profiles and employs image processing algorithms to calculate displacement, eliminating the need for complex mechanical probes or contact-based measurement devices.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Productivity

If improper centricity is not detected, then production continues without interruption, but manufacturing errors occur and equipment damage can happen

Engineering Contradiction:

Improveproduction continuityVSAvoidmanufacturing quality

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent implements a feedback mechanism where the metrology system continuously measures wafer centricity and provides information about offset values. This feedback enables real-time monitoring and detection of improper bonding, allowing operators to correct issues before they cause manufacturing defects or equipment damage, thus maintaining both productivity and reliability.

Inventive Principle:

Principle #23Feedback

Data Source

PatentEP3507826B1Bonded wafer metrology

Publication Date: 2025.05.28 KLA CORP

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Figure 4A

AI summary

Wafer edge profile images are analyzed at locations around a bonded wafer, which may have a top wafer and a carrier wafer. An offset curve is generated based on the wafer edge profile images. Displacement of the top wafer to the carrier wafer is determined based on the offset curve. The wafer edge profile images may be generated at multiple locations around the wafer. The wafer edge profile images may be shadowgram images. A system to determine displacement of the top wafer to the carrier wafer can include an imaging system connected with a controller.