3DIC Package Substrate Layout for Underfill Bleeding Control

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Solution Overview

Problem

Existing three-dimensional integrated circuit (3DIC) packaging technologies face challenges in efficiently controlling underfill material bleeding during the dispensing process, leading to increased keep-out zones and reduced reliability due to inadequate control over underfill fillet formation.

Innovation Solution

The implementation of dummy patterns, specifically first and second dummy patterns, which are formed over the board substrate and between semiconductor packages, function as underfill blocking walls to constrain the flow of underfill materials, preventing bleeding to undesired bumps or devices and reducing the bleeding length by at least 20%, thereby allowing for a smaller keep-out zone and improved process window.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional 3DIC packaging without dummy patterns is used, then the packaging structure is simpler, but underfill material bleeding occurs and reliability is reduced

Engineering Contradiction:

Improvepackaging reliabilityVSAvoidpackaging structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Dummy patterns are introduced as intermediary structures between semiconductor packages and underfill material. These dummy patterns act as blocking walls that intercept and contain the underfill material, preventing it from bleeding into unwanted areas. The dummy patterns serve as a mediating element that resolves the conflict between maintaining simple packaging structure and achieving reliable underfill control.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

Dummy patterns are formed in advance during the packaging process, before underfill material dispensing. This preliminary action of creating blocking structures ensures that when underfill material is subsequently applied, its flow is already constrained by the pre-positioned dummy patterns, preventing bleeding issues before they occur.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If larger keep-out zones are used to prevent underfill bleeding, then underfill control is improved, but the package area increases

Engineering Contradiction:

Improveunderfill controlVSAvoidpackage area

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

Instead of implementing a large keep-out zone across the entire package area, dummy patterns are strategically placed only in specific locations where underfill bleeding is most likely to occur. This localized approach provides effective underfill control precisely where needed, while maintaining a compact overall package footprint by avoiding unnecessary restrictions in other areas.

Inventive Principle:

Principle #3Local quality

3Manufacturing precision

If dummy patterns are added to control underfill flow, then underfill bleeding is reduced, but manufacturing process complexity increases

Engineering Contradiction:

Improveunderfill bleeding controlVSAvoidmanufacturing process complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The formation of dummy patterns is merged with existing packaging process steps, such as being formed simultaneously with other structural elements or integrated into the same fabrication sequence. This consolidation approach incorporates the underfill control function without requiring completely separate manufacturing processes, thereby limiting the increase in overall process complexity.

Inventive Principle:

Principle #5Merging (Combining)

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

The use of dummy patterns effectively controls underfill fillet formation, reducing bleeding length and enabling a more compact 3DIC structure with enhanced reliability and process accuracy.

Implementation Method 1

The dummy patterns function as underfill blocking walls to constrain the flow of underfill materials

Methodology Applied

Scientific EffectPhysical containment: Physical Containment

Data Source

PatentUS12113027B2Three-dimensional integrated circuit structures and methods of forming the same

Publication Date: 2024.10.08 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

Board substrates, three-dimensional integrated circuit structures and methods of forming the same are disclosed. A board substrate includes a core layer, a first build-up layer, a second build-up layer, a first group of bumps, a second first group of bumps and at least one first underfill blocking wall. The first build-up layer and the second build-up layer are disposed on opposite sides of the core layer. The first group of bumps is disposed over the first build-up layer. The second first group of bumps is disposed over the first build-up layer. The at least one first underfill blocking wall is disposed over the first build-up layer and between the first group of bumps and the second group of bumps.