Integrated Overlay Mark Layout for Stitching and Layer Alignment

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

In semiconductor processes, the use of separate stitching and layer-to-layer overlay marks occupies more layout area and complicates measurements due to the need for different marks in different regions, making alignment checks cumbersome.

Innovation Solution

The method involves forming stitching overlay mark structures in different layers, with these structures integrated into a layer-to-layer overlay mark structure, allowing for phase shift measurements that simultaneously check stitching and layer-to-layer alignments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If separate stitching overlay mark structures and layer-to-layer overlay mark structures are used in different regions, then overlay measurement coverage is improved, but layout area occupied increases and measurement complexity increases

Engineering Contradiction:

Improveoverlay measurement coverageVSAvoidlayout area occupied

Core Design Contradiction:

Adaptability or versatilityVSArea of stationary object

Solution Approach 1:

The patent combines stitching overlay mark structures and layer-to-layer overlay mark structures into a single integrated overlay mark structure. The first stitching overlay mark structure on the first layer and the second stitching overlay mark structure on the second layer are positioned such that they form both stitching overlay marks for the same layer and layer-to-layer overlay marks between different layers, eliminating the need for separate mark structures in different regions.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The integrated overlay mark structure serves multiple functions simultaneously: it acts as a stitching overlay mark for alignment within the same layer and as a layer-to-layer overlay mark for alignment between different layers. This multi-functional design allows a single mark structure to replace what would traditionally require separate dedicated mark structures.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If separate stitching overlay mark structures and layer-to-layer overlay mark structures are used in different regions, then overlay measurement coverage is improved, but measurement process complexity increases

Engineering Contradiction:

Improveoverlay measurement coverageVSAvoidmeasurement process complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent merges the measurement processes for stitching overlay and layer-to-layer overlay into a single measurement step. By positioning the stitching overlay mark structures on different layers such that they form an integrated structure, the measurement system can perform both stitching overlay measurement and layer-to-layer overlay measurement on the same mark structure, simplifying the measurement process.

Inventive Principle:

Principle #5Merging (Combining)

3Manufacturing precision

If stitching overlay mark structures are formed using photomask patterns, then manufacturing precision is achieved, but photomask complexity increases

Engineering Contradiction:

Improvepattern alignment precisionVSAvoidphotomask complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The photomask is divided into different regions with different pattern arrangements. The first photomask has patterns arranged to form first stitching overlay mark structures, while the second photomask has patterns arranged to form second stitching overlay mark structures. This segmentation allows each photomask to be optimized for its specific function while contributing to the overall integrated overlay mark structure.

Inventive Principle:

Principle #1Segmentation

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 layout area usage and simplifies overlay measurements by enabling multi-checks of alignment between layers, improving measurement efficiency and accuracy.

Implementation Method 1

the phase shift measurement is used to perform overlay measurement on the above-mentioned overlay mark

Methodology Applied

Scientific EffectPhase shift: Interference

Data Source

PatentUS20250013157A1Manufacturing method of overlay mark and overlay measurement method

Publication Date: 2025.01.09 UNITED MICROELECTRONICS CORP

AI summary

Provided are a manufacturing method of an overlay mark and an overlay measurement method. The manufacturing method includes the following steps. A first stitching overlay mark structure having a plurality of first patterns is formed on a first layer. A second layer is formed on the first layer. A second stitching overlay mark structure having a plurality of second patterns is formed on the second layer. The second stitching overlay mark structure is located above the first stitching overlay mark structure, and from the top view on the second layer, the second patterns and the first patterns are alternately arranged.