Semiconductor Chip Bonding Trenches for Peel-Off Stress Relief

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Solution Overview

Problem

The existing semiconductor device structures with a chip bonding portion larger than the semiconductor chip face issues with heat dissipation and reliability due to stress-induced peel-off of the die-bond material, especially at corner portions, and moisture ingress, leading to reduced reliability and heat dissipation performance over time.

Innovation Solution

A semiconductor device design featuring a chip bonding region with trenches at corner portions to reduce stress and prevent peel-off, where the trenches are formed along intersecting diagonal lines to direct stress release outside the bonding area, and an annular trench surrounding the chip bonding region to manage die-bond material distribution and prevent moisture ingress.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If the outer-shape size of the chip bonding portion is formed larger than the semiconductor chip, then heat dissipation performance is improved, but stress-induced peel-off of die-bond material occurs at corner portions

Engineering Contradiction:

Improveheat dissipation performanceVSAvoidpeel-off resistance of die-bond material

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The chip bonding portion is segmented by forming trenches at the corner portions, dividing the continuous bonding area into regions separated by stress-relief gaps. This segmentation allows the die-bond material to be divided into multiple bonding regions, preventing stress-induced peel-off from propagating across the entire bonding area while maintaining the larger outer-shape size for heat dissipation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The corner portions of the chip bonding portion are given different local properties by forming trenches only at these locations. The trenches create local stress relief zones with different mechanical properties compared to the central bonding region. This local modification allows the corner portions to accommodate thermal expansion differences without causing peel-off, while the central region maintains strong bonding for heat dissipation.

Inventive Principle:

Principle #3Local quality

2Temperature

If the chip bonding portion is exposed from the sealing body, then heat dissipation performance is improved, but moisture ingress into the semiconductor device increases

Engineering Contradiction:

Improveheat dissipation performanceVSAvoidmoisture ingress

Core Design Contradiction:

TemperatureVSObject-affected harmful factors

Solution Approach 1:

The trenches are formed at the corner portions of the chip bonding portion before the die-bond material is applied and before the sealing body is formed. This preliminary structuring of the bonding surface creates predetermined stress relief zones that prevent peel-off before it can occur during subsequent thermal cycling, while the exposed configuration maintains heat dissipation performance.

Inventive Principle:

Principle #10Preliminary action

3Reliability

If trenches are formed at corner portions of the chip bonding region, then stress-induced peel-off is suppressed, but manufacturing complexity increases

Engineering Contradiction:

Improvepeel-off resistance of die-bond materialVSAvoidchip bonding region structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Instead of forming trenches across the entire chip bonding region or using complex stress management structures, the invention applies partial action by forming trenches only at the critical corner portions where peel-off most readily occurs. This targeted approach provides sufficient stress relief to prevent peel-off while minimizing the added manufacturing complexity and material usage.

Inventive Principle:

Principle #16Partial or excessive action

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 design effectively suppresses the peel-off of die-bond material and enhances heat dissipation by reducing stress at corner portions and improving moisture sealing, thereby increasing the reliability and performance of the semiconductor device.

Implementation Method 1

a first trench (groove) is formed at a first corner portion of the chip bonding region... a second trench is formed at a second corner portion opposed to the first corner portion so as to interpose a center portion of the chip bonding region therebetween

Methodology Applied

Scientific EffectStress relaxation: Stress Relaxation

Implementation Method 2

a lower surface (rear surface) of the chip bonding portion can be also connected to a mounting substrate, and therefore, heat dissipation performance can be improved

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS9006871B2Semiconductor device and method of manufacturing the same

Publication Date: 2015.04.14 RENESAS ELECTRONICS CORP

AI summary

A trench portion (trench) is formed at each of four corner portions of a chip bonding region having a quadrangular planar shape smaller than an outer-shape size of a die pad included in a semiconductor device. Each trench is formed along a direction of intersecting with a diagonal line which connects between the corner portions where the trench portions are arranged, and both ends of each trench portion are extended to an outside of the chip bonding region. The semiconductor chip is mounted on the chip bonding region so as to interpose a die-bond material. In this manner, peel-off of the die-bond material in a reflow step upon mounting of the semiconductor device on a mounting substrate can be suppressed. Also, even if the peel-off occurs, expansion of the peel-off can be suppressed.