Semiconductor Package Post Structure for Heat Dissipation

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Solution Overview

Problem

Existing semiconductor packages with a chip last structure face challenges in securing effective heat dissipation due to limited copper post height and potential undercut issues when using multiple photosensitive films.

Innovation Solution

A semiconductor package design featuring a lower post connected to a first redistribution layer, an upper post with increasing width, and a mold layer covering the redistribution layer and semiconductor chip, with the upper post surface coplanar with the mold layer, enhancing heat dissipation and reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If the thickness of the package is increased to secure heat dissipation characteristics, then heat dissipation performance is improved, but the device complexity and manufacturing difficulty increase

Engineering Contradiction:

Improveheat dissipation characteristicsVSAvoidpackage structure complexity

Core Design Contradiction:

TemperatureVSDevice complexity

Solution Approach 1:

The copper post is divided into two distinct segments: a lower post formed directly on the redistribution layer and an upper post formed subsequently on the mold layer. This segmentation allows each part to be optimized independently - the lower post provides thermal conduction path while the upper post extends the thermal dissipation area, resolving the contradiction between heat dissipation performance and structural simplicity

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention transitions from a single-dimensional vertical post structure to a two-dimensional expanded structure by adding the upper post that extends horizontally on the mold layer. This dimensional change increases the thermal dissipation surface area without proportionally increasing package thickness, thereby improving heat dissipation while controlling overall package complexity

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Temperature

If the height of the copper post is increased to improve heat dissipation, then thermal management is improved, but manufacturing precision deteriorates due to limited photosensitive film height

Engineering Contradiction:

Improveheat dissipationVSAvoidcopper post height control

Core Design Contradiction:

TemperatureVSManufacturing precision

Solution Approach 1:

The copper post height is segmented into two controllable portions formed in separate manufacturing steps. The lower post height is controlled by the thickness of the redistribution layer structure, while the upper post height is controlled by the mold layer thickness and subsequent planarization. This segmentation eliminates the need for a single tall photosensitive film, improving manufacturing precision

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The mold layer is formed and planarized before forming the upper post, creating a flat reference surface that enables precise control of the upper post height. This preliminary action of preparing the surface ensures that the upper post can be formed with controlled dimensions, resolving the manufacturing precision issue

Inventive Principle:

Principle #10Preliminary action

3Temperature

If multiple photosensitive films are used to achieve desired copper post height, then heat dissipation is improved, but manufacturing reliability deteriorates due to undercut phenomena

Engineering Contradiction:

Improveheat dissipation characteristicsVSAvoidpackage manufacturing reliability

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The copper post formation is segmented into two independent steps using different formation methods. The lower post is formed by electroplating through a via hole, while the upper post is formed by electroplating on a planarized mold layer surface. This segmentation eliminates the need to stack multiple photosensitive films, thereby eliminating the undercut phenomenon and improving manufacturing reliability

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention replaces the photosensitive film-based height control mechanism with an electroplating-based mechanism. Instead of relying on the mechanical stacking of photosensitive films (which causes undercut), the copper post height is controlled by electrochemical deposition processes that provide better dimensional control and eliminate the undercut phenomenon, improving reliability

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS12463125B2Semiconductor package including post

Publication Date: 2025.11.04 SAMSUNG ELECTRONICS CO LTD

AI summary

A semiconductor package according to an example embodiment of the disclosure includes a first redistribution layer including a first via, a first redistribution pattern, and a first insulating layer, a first semiconductor chip connected to the first redistribution layer via a chip connection terminal, a lower post directly connected to the first redistribution layer, an upper post connected to an upper surface of the lower post, a first mold layer at least partially covering the first redistribution layer, the first semiconductor chip, the lower post, and the upper post, and a second redistribution layer on the upper post and the first mold layer. The upper post has a width that gradually increases as the upper post extends from the lower post toward the second redistribution layer. An upper surface of the upper post is coplanar with an upper surface of the first mold layer.