Die Bond Pad Structure for Dangling-Bond Stress Relief

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Solution Overview

Problem

The increasing complexity of integrated circuit packages, which include multiple device dies with different technologies and functions, poses challenges in achieving strong and reliable bond structures, particularly in stacked die configurations where dangling bonds can lead to reduced bond strength and reliability.

Innovation Solution

The solution involves forming dummy dies with dangling pads that are bonded to active pads in the dielectric layer, improving bond strength by using a stress-absorbing buffer layer and specific bonding processes such as fusion bonding and gap-filling with dielectric materials, and incorporating dummy pads to reduce stress and warpage in the package.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple device dies are stacked in the same package to achieve more functions, then the device functionality and integration are improved, but the bond strength and reliability deteriorate due to dangling bonds

Engineering Contradiction:

Improvedevice functionalityVSAvoidbond strength

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent converts the harmful effect of dangling bonds into a beneficial structure by intentionally creating dummy bond pads that simulate the dangling bond configuration. These dummy pads are designed to absorb stress and prevent the negative effects of actual dangling bonds at active bonding interfaces, thereby maintaining reliability while enabling multi-die stacking functionality

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Ease of manufacture

If device dies with different technologies and functions are bonded together, then the system optimization and manufacturing cost are improved, but the bonding complexity and stress management become more difficult

Engineering Contradiction:

Improvemanufacturing costVSAvoidbonding complexity

Core Design Contradiction:

Ease of manufactureVSDevice complexity

Solution Approach 1:

The patent segments the bonding interface into two distinct components: active bond pads for electrical connection and dummy bond pads for stress management. This segmentation allows different die with different technologies to be bonded together by separating the electrical bonding function from the mechanical stress absorption function, simplifying the overall bonding process despite the diversity of dies

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The dummy bond pads act as intermediaries between different die technologies. They provide a standardized interface that absorbs thermal and mechanical stress generated by heterogeneous die stacking, mediating the compatibility issues between different technologies and enabling cost-effective multi-vendor die integration

Inventive Principle:

Principle #24Intermediary (Mediator)

3Quantity of substance

If upper memory dies are bonded to lower memory dies to form stacks, then the memory density is improved, but the warpage and stress control become more challenging

Engineering Contradiction:

Improvememory densityVSAvoidwarpage control

Core Design Contradiction:

Quantity of substanceVSStability of the object's composition

Solution Approach 1:

The patent applies preliminary action by pre-configuring dummy bond pads on die surfaces before stacking. These dummy pads are positioned and structured in advance to anticipate and absorb the thermal and mechanical stress that will occur during subsequent die bonding and operation, preventing warpage issues before they manifest in the final stacked structure

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent utilizes parameter changes in the dummy bond pad design, varying their size, material composition, and spatial distribution to optimize stress absorption. By adjusting these parameters, the system can compensate for the increased warpage tendency in higher-density memory stacks, maintaining structural stability while achieving greater memory capacity

Inventive Principle:

Principle #35Parameter changes

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

This approach enhances the bond strength and reliability of stacked die packages by improving the contact between active and dummy pads, reducing stress and warpage, and optimizing the planarization process, leading to more robust and functional integrated circuit packages.

Implementation Method 1

improving the contact between active and dummy pads, reducing stress and warpage

Methodology Applied

Scientific EffectStress absorption: Absorption (physical)

Implementation Method 2

forming a dielectric layer on the semiconductor substrate; forming a plurality of bond pads in the dielectric layer

Methodology Applied

Scientific EffectDielectric insulation: Dielectric

Implementation Method 3

specific bonding processes such as fusion bonding

Methodology Applied

Scientific EffectFusion bonding: Welding

Data Source

PatentUS11908817B2Bonding structure of dies with dangling bonds

Publication Date: 2024.02.20 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A method includes polishing a semiconductor substrate of a first die to reveal first through-vias that extend into the semiconductor substrate, forming a dielectric layer on the semiconductor substrate, and forming a plurality of bond pads in the dielectric layer. The plurality of bond pads include active bond pads and dummy bond pads. The active bond pads are electrically coupled to the first through-vias. The first die is bonded to a second die, and both of the active bond pads and the dummy bond pads are bonded to corresponding bond pads in the second die.