Overlay Shift Measurement Using Mark Asymmetry Correction

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Solution Overview

Problem

In semiconductor device manufacturing, the miniaturization of circuit line widths increases the difficulty of accurately measuring overlay shift between layers due to distortion of overlay marks caused by film stress, leading to measurement errors.

Innovation Solution

A measurement method that involves using a system to measure overlay shift between layers by acquiring an asymmetry parameter related to the shape of the overlay marks and applying correction based on this parameter to obtain accurate measurements, thereby mitigating the effects of distortion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If overlay marks are used to measure overlay shift between layers, then measurement capability is provided, but film stress causes distortion of the overlay marks leading to measurement errors

Engineering Contradiction:

Improveoverlay shift measurement accuracyVSAvoidmeasurement accuracy due to mark distortion

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent changes the measurement parameter from direct geometric position measurement to asymmetry parameter measurement. By detecting the asymmetry of overlay mark shapes caused by film stress and using this asymmetry information to calculate corrected overlay shift values, the method compensates for distortion effects and maintains measurement accuracy despite mark deformation

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent utilizes the asymmetry introduced by film stress rather than treating it purely as noise. By deliberately measuring the asymmetric shape parameters of overlay marks and correlating them with stress-induced distortion, the method converts the harmful asymmetry into useful correction information that improves measurement reliability

Inventive Principle:

Principle #4Asymmetry

2Productivity

If thick resist films are formed to create footstep structures in multilayer wiring, then three-dimensional memory cell arrangement is enabled, but film stress increases causing greater overlay mark distortion

Engineering Contradiction:

Improvethree-dimensional memory cell arrangement capabilityVSAvoidfilm stress causing overlay mark distortion

Core Design Contradiction:

ProductivityVSStress or pressure

Solution Approach 1:

The patent implements a feedback mechanism where the asymmetry of overlay marks is measured and used to correct subsequent overlay shift measurements. By continuously monitoring mark asymmetry and applying corrections based on this feedback, the system compensates for distortion caused by thick resist films and maintains accurate overlay control throughout the manufacturing process

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS9972547B2Measurement method, manufacturing method of device, and measurement system

Publication Date: 2018.05.15 KIOXIA CORP

AI summary

According to one embodiment, there is provided a measurement method. The method includes measuring an amount of overlay shift between a first layer and a second layer using a first overlay mark and a second overlay mark. The first layer is provided as a layer including the first overlay mark above a first substrate. The second layer is provided as a layer including the second overlay mark above the first overlay mark. The method includes acquiring a parameter related to asymmetry of a shape of the second overlay mark. The method includes obtaining an amount of correction with respect to a measured value of the amount of overlay shift based on the acquired parameter and the measured amount of overlay shift.