Die Stack Substrate Marks for Accurate Alignment Verification

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Solution Overview

Problem

Existing die stack packages face challenges in accurately determining the stacking state of semiconductor dies, particularly due to the subtle differences in light reflection from alignment marks, making it difficult to distinguish between proper and improper alignments.

Innovation Solution

A substrate with specific die alignment and position marks, including cross-shaped alignment marks and square-shaped position marks, is used to facilitate precise alignment and determination of the stacking state of semiconductor dies, ensuring they are properly positioned without exposing the main position marks.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional alignment marks are used in die stack packages, then the structure is simple, but it is difficult to accurately determine the stacking state due to subtle light reflection differences

Engineering Contradiction:

Improvedetection accuracy of stacking stateVSAvoidmark structure complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The alignment mark is segmented into multiple distinct components: a cross-shaped alignment mark for positioning and a separate square-shaped main position mark for state verification. This segmentation allows each component to serve a specific function, improving the accuracy of stacking state detection while maintaining structural clarity

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention uses asymmetric shapes with distinct geometric characteristics - the cross-shaped alignment mark has four arms extending in cardinal directions, while the square-shaped main position mark has four sides. These asymmetric shapes create unique light reflection patterns that are easily distinguishable, solving the problem of subtle light reflection differences in conventional symmetric marks

Inventive Principle:

Principle #4Asymmetry

2Ease of operation

If simple alignment marks are used, then the manufacturing process is easy, but real-time verification of proper alignment is difficult

Engineering Contradiction:

Improveease of alignment verificationVSAvoidtime for alignment verification

Core Design Contradiction:

Ease of operationVSLoss of time

Solution Approach 1:

The substrate is pre-configured with both the cross-shaped alignment mark and the square-shaped main position mark during manufacturing. This preliminary arrangement enables operators to perform real-time verification by simply observing the relative positions of these pre-placed marks, eliminating the need for complex verification procedures and reducing alignment verification time

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention utilizes optical contrast through differently shaped marks that reflect light in distinct patterns. The cross-shaped and square-shaped marks create visually distinguishable signatures under illumination, enabling rapid visual verification of alignment status without requiring additional tools or time-consuming measurements

Inventive Principle:

Principle #32Color changes

Data Source

PatentUS12581961B2Substrate having a die position mark and a semiconductor die stack structure including semiconductor dies stacked on the substrate

Publication Date: 2026.03.17 SK HYNIX INC

AI summary

A substrate includes: a first die alignment mark and a first die position mark defining a die stack region. The first die alignment mark has substantially a cross shape having substantially a vertical bar and substantially a horizontal bar intersecting each other substantially perpendicularly, and the first die position mark includes a first main position mark having a first area and a first branch position mark having a second area different from the first area.