Reinforced Package Substrates for Underfill Stress and Warp Control

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Solution Overview

Problem

Semiconductor packages face mechanical issues such as warpage, cracking, and delamination due to thermal expansion mismatch between package components, which affect the reliability of interconnections and overall package performance.

Innovation Solution

Incorporating a reinforcing portion within the semiconductor package substrate with a higher bulk modulus and lower thermal expansion coefficient than the core material, and using an external reinforcing member to mitigate warpage, while forming the reinforcing portion with materials like silicon, silicon nitride, or ceramic to reduce thermal-stress-induced damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If package size is increased to accommodate greater numbers of integrated circuits and dies per package, then the quantity of components per package is improved, but mechanical stability deteriorates due to thermal expansion mismatch causing warpage and cracking

Engineering Contradiction:

Improvenumber of integrated circuits and dies per packageVSAvoidmechanical stability of package

Core Design Contradiction:

Quantity of substanceVSStability of the object's composition

Solution Approach 1:

The patent applies local quality by creating a reinforcing portion with different material properties (higher bulk modulus, lower thermal expansion coefficient) than the core substrate material. This localized reinforcement at specific regions of the substrate provides enhanced mechanical stability and thermal-mismatch compensation without requiring the entire package to be larger or more complex.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent employs composite materials by combining the core substrate material with a reinforcing portion made of different materials (such as silicon, silicon nitride, or ceramic). This composite structure leverages the complementary properties of each material to achieve both the desired component capacity and improved mechanical stability against warpage and cracking.

Inventive Principle:

Principle #40Composite materials

2Strength

If reinforcing structures are added to mitigate warpage, then mechanical integrity is improved, but device complexity increases due to additional manufacturing steps and material layers

Engineering Contradiction:

Improvemechanical integrity of package substrateVSAvoidcomplexity of substrate structure

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The patent applies segmentation by dividing the substrate into distinct functional regions: a core portion and a reinforcing portion. This segmentation allows each region to be optimized independently for its specific function while maintaining overall structural integrity. The reinforcing portion can be strategically placed only where needed to combat warpage, rather than requiring a completely redesigned complex substrate structure.

Inventive Principle:

Principle #1Segmentation

3Reliability

If materials with different thermal expansion coefficients are used for reinforcement, then thermal expansion mismatch compensation is improved, but manufacturing difficulty increases due to material selection and integration challenges

Engineering Contradiction:

Improvethermal expansion mismatch compensationVSAvoidease of substrate fabrication

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent applies parameter changes by selecting reinforcing materials with specific thermal expansion coefficients and bulk moduli that are optimized for compensating thermal expansion mismatch. By carefully choosing materials such as silicon, silicon nitride, or ceramic with appropriate physical parameters, the patent achieves reliable thermal-mismatch compensation while maintaining compatibility with existing semiconductor manufacturing processes.

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

The solution effectively reduces or eliminates warpage and mechanical degradation, enhancing the reliability and stability of semiconductor package interconnections by compensating for thermal expansion mismatches and improving the mechanical integrity of the package substrate.

Implementation Method 1

thermal expansion mismatch between package components leading to warpage, cracking, delamination

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

a reinforcing portion (212) including a second material having a second bulk modulus and a second coefficient of thermal expansion

Methodology Applied

Scientific EffectBulk modulus:

Data Source

PatentUS20230378042A1Reinforced substrates to mitigate underflow stress and package warp and methods of making the same

Publication Date: 2023.11.23 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

An embodiment package substrate may include a core portion including a first material having a first bulk modulus and a first coefficient of thermal expansion, and a reinforcing portion including a second material having a second bulk modulus and a second coefficient of thermal expansion. The second bulk modulus may be chosen to be greater than the first bulk modulus and the second coefficient of thermal expansion may be chosen to be less than the first coefficient of thermal expansion. The core portion may include a fiber-reinforced polymer material and the reinforcing portion may include silicon, silicon nitride, or a ceramic material. The second bulk modulus may be greater than or equal to 100 GPa and the second coefficient of thermal expansion may be less than 10 ppm/° C. The reinforcing portion may include four components each respectively located proximate to a respective corner of the package substrate.