Semiconductor Misalignment Checking Device

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Solution Overview

Problem

In the semiconductor industry, existing methods for checking misalignment between layered patterns during the lithography process are inefficient, particularly in achieving accurate alignment without compromising throughput, especially as packing density increases and multi-layering becomes more complex.

Innovation Solution

A misalignment checking device comprising an optical element, first and second imaging elements, and an arithmetic processing unit that captures and processes images of marks with different focus positions, allowing for simultaneous imaging and calculation of misalignment without requiring frequent Z-axis adjustments, while using filters to optimize imaging environments and eliminate unnecessary wavelength regions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a wafer stage is vertically driven to align focus positions for misalignment checking, then measurement precision is improved, but productivity deteriorates due to frequent Z-axis adjustments and time consumption

Engineering Contradiction:

Improvemisalignment checking precisionVSAvoidthroughput

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The patent divides the imaging function into multiple imaging elements (first imaging element and second imaging element) positioned at different Z-positions. Each imaging element captures images at its respective focus plane simultaneously, eliminating the need for sequential Z-axis movement. This segmentation of the imaging function across multiple spatial positions enables parallel capture of marks at different focus positions, thereby maintaining measurement precision while improving productivity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent transitions from a single-Z-position imaging approach to a multi-Z-position imaging architecture. By arranging imaging elements along the Z-axis (optical axis direction) at different positions, the system captures images at multiple focus planes simultaneously. This dimensional expansion from one Z-position to multiple Z-positions enables simultaneous imaging without sequential Z-axis adjustments, resolving the contradiction between precision and productivity.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Productivity

If multiple imaging elements are used to capture marks at different focus positions simultaneously, then productivity is improved, but device complexity increases

Engineering Contradiction:

ImprovethroughputVSAvoidimaging system complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent employs a single optical system that serves multiple imaging elements simultaneously. The optical system (including light source, objective lens, and condenser lens) is configured to illuminate and form images for both the first and second imaging elements at different Z-positions. This multi-functional optical system reduces the need for separate imaging systems for each Z-position, thereby improving productivity while limiting the increase in device complexity through shared optical components.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Measurement precision

If filters are used to eliminate unnecessary wavelength regions, then measurement precision is improved, but use of energy increases

Engineering Contradiction:

Improveimaging accuracyVSAvoidenergy consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent uses filters to selectively transmit specific wavelength regions and block unnecessary wavelengths. By changing the optical parameters (wavelength transmission characteristics) through filtering, the system improves imaging accuracy by eliminating stray light and unwanted reflections. The filters are positioned in the optical path to condition the light before it reaches the imaging elements, achieving precision improvement while managing energy consumption through selective wavelength transmission.

Inventive Principle:

Principle #35Parameter changes

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 solution enhances the accuracy and efficiency of misalignment checking, improving throughput while maintaining precision, by enabling simultaneous imaging of marks with different focus positions and optimizing imaging conditions, thus addressing the inefficiencies of existing methods.

Implementation Method 1

an optical element, a first imaging element, a second imaging element... The optical element branches reflection light from a first mark and a second mark having different focus positions

Methodology Applied

Scientific EffectReflection: Reflection

Implementation Method 2

using filters to optimize imaging environments and eliminate unnecessary wavelength regions

Methodology Applied

Scientific EffectOptical filtering: Filter (optical)

Data Source

PatentUS9929103B2Misalignment checking device and manufacturing method of semiconductor device

Publication Date: 2018.03.27 KIOXIA CORP

AI summary

According to one embodiment, an optical element branches reflection light from a first mark and a second mark having different focus positions, a first imaging element captures an image of the first mark based on a first branch light branched by the optical element, a second imaging element captures an image of the second mark based on a second branch light branched by the optical element, and an arithmetic processing unit that calculates a misalignment between the first mark and the second mark based on a result of superimposition of the image of the first mark and the image of the second mark.