Conductive Pad Structure for Micro-LED Chip Pick Force

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Solution Overview

Problem

During the mass transfer of micro-LED chips from a temporary substrate to a final substrate using the stamp pick-and-place process, the chips often drop due to insufficient pick force caused by high surface roughness and small contact area between the chip and the pick head.

Innovation Solution

The semiconductor device features a conductive feature with a larger contact area and reduced surface roughness, achieved by surrounding it with dummy structures and optionally connection segments, which increase the overall contact area with the pick head.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of moving object

If the chip surface is formed with standard contact pad patterns, then the manufacturing process is simple, but the contact area with the pick head is too small causing chips to drop during mass transfer

Engineering Contradiction:

Improvecontact areaVSAvoidpad pattern structure

Core Design Contradiction:

Area of moving objectVSDevice complexity

Solution Approach 1:

The contact pad pattern is segmented into multiple dummy pad patterns surrounding the central active pad. This segmentation increases the total contact area with the pick head while maintaining a manageable structural complexity through repetitive modular patterns.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Multiple dummy pad patterns are merged around the central active pad to form an integrated contact structure. This merging increases the overall contact area with the pick head, ensuring sufficient pick force during mass transfer while presenting a unified structural design.

Inventive Principle:

Principle #5Merging (Combining)

2Reliability

If the contact pad has high surface roughness, then the manufacturing process is simpler, but the pick force is insufficient causing chips to drop during transfer

Engineering Contradiction:

Improvepick forceVSAvoidsurface roughness

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The dummy pad patterns are formed in advance during the manufacturing process to pre-establish a larger contact area. This preliminary structural preparation ensures that when the chip undergoes mass transfer, the pick head has sufficient contact area to generate adequate pick force, preventing chip drop.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The surface roughness parameter of the contact pad is optimized through controlled manufacturing processes. By adjusting the surface roughness parameter to an optimal range, the patent achieves sufficient pick force while maintaining manufacturing feasibility, resolving the contradiction between reliability and manufacturing precision.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS20250366280A1Semiconductor device and method for forming the same

Publication Date: 2025.11.27 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A semiconductor device includes a substrate, a dielectric layer over the substrate, a conductive feature over the dielectric layer and is physically connected to a connecting via embedded in the dielectric layer; and a plurality of dummy structures over the dielectric layer and surrounding the conductive feature. A top surface of the conductive feature is separate from top surfaces of the dummy structures, and the plurality of dummy structures are electrically connected to the conductive feature.