3D IC Underfill Metrology for Void Prevention

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Solution Overview

Problem

In three-dimensional integrated circuit (3D IC) packaging, determining the optimal amount of underfill material to prevent voids and bridging between closely-spaced dies while ensuring good fillet formation is challenging due to variations in die size, bump height, and spacing.

Innovation Solution

A method involving metrology to calculate the volume of underfill material for each die using equations that account for stand-off height, die dimensions, bump density, and shrinkage rate, ensuring accurate dispensing to form optimal fillets and prevent voids and bridging.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a fixed amount of underfill material is dispensed for all dies, then the dispensing process is simple and fast, but voids form in areas with larger stand-off height and bridging occurs between closely-spaced dies

Engineering Contradiction:

Improvedispensing speedVSAvoidunderfill material distribution accuracy

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent implements dynamic adjustment of underfill material dispensing parameters based on real-time metrology data. The system varies the volume of underfill material dispensed for each die according to its specific stand-off height and spacing to adjacent dies, transforming a static fixed-volume process into a dynamic adaptive process that resolves the contradiction between speed and precision

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the dispensing parameters (volume, rate, position) based on measured variations in die characteristics. By adjusting these parameters according to actual stand-off height and die spacing, the system achieves precise underfill distribution without requiring manual intervention for each die, maintaining productivity while improving manufacturing precision

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the underfill material volume is increased to prevent voids in high stand-off areas, then void formation is reduced, but bridging occurs between closely-spaced dies

Engineering Contradiction:

Improvevoid preventionVSAvoidbridging between dies

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent applies local quality by dispensing different volumes of underfill material to different dies based on their specific characteristics. Each die receives a customized amount of underfill material calculated from its stand-off height and spacing to adjacent dies, ensuring adequate filling in high stand-off areas while preventing excess material from causing bridging in closely-spaced regions

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent performs preliminary metrology measurements of stand-off height and die spacing before the dispensing process. This advance characterization allows the system to pre-calculate the optimal underfill volume for each die, preventing both voids and bridging before the dispensing operation begins

Inventive Principle:

Principle #10Preliminary action

3Manufacturing precision

If custom underfill volume is calculated for each die based on metrology, then fillet formation and void prevention are optimized, but the process complexity and measurement requirements increase

Engineering Contradiction:

Improvefillet formation accuracyVSAvoidmetrology and calculation system

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent replaces complex manual measurement and calculation processes with an automated optical metrology system and integrated control algorithm. The system automatically captures images, calculates stand-off height and die spacing, determines optimal underfill volume, and executes dispensing without human intervention, reducing operational complexity despite increased system sophistication

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent implements a multi-functional integrated system that performs metrology measurement, data processing, volume calculation, and dispensing control through a single automated platform. This universal system handles multiple functions that would otherwise require separate devices and processes, managing complexity through consolidation rather than proliferation of components

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS9859181B2Underfill dispensing in 3D IC using metrology

Publication Date: 2018.01.02 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

In some embodiments, a semiconductor device includes a first die, a second die coupled to a first surface of the first die, and a third die coupled to the first surface of the first die. The semiconductor device further includes an underfill material disposed between the first die and the second die and between the first die and the third die. A first volume of the underfill material for the second die is different than a second volume of the underfill material for the third die.