Semiconductor Metal Bump Intermetallic Compound Formation

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Solution Overview

Problem

Flip chip mounting with metal bonding faces issues of weak bonding strength at the interface between intermetallic compounds and metal, leading to breakage under minor forces, especially when excessive bonding material is used, which compromises mounting reliability.

Innovation Solution

A semiconductor device with a metal bump stacked on an electrode, comprising bonding material and metal material, where the metal material initiates the formation of intermetallic compounds through interdiffusion, ensuring complete conversion of bonding material into intermetallic compounds without reducing the bonding material amount, thereby enhancing bonding strength and reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a great amount of bonding material is used in metal bonding, then the bonding area is sufficient for reliable mounting, but the bonding material cannot be completely formed into intermetallic compound, resulting in weak bonding strength at the interface

Engineering Contradiction:

Improvemounting reliabilityVSAvoidbonding strength

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

A metal layer is formed on the semiconductor substrate before bonding in advance. This preliminary metal layer serves as a metal source that will diffuse into the bonding material during the bonding process, ensuring complete conversion to intermetallic compound and strong bonding strength from the outset.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention changes the chemical composition parameters of the bonding structure by introducing a metal layer that provides additional metal atoms. This alters the diffusion dynamics during bonding, ensuring complete intermetallic compound formation throughout the bonding material volume.

Inventive Principle:

Principle #35Parameter changes

2Ease of manufacture

If wire bonding is used for electrical connection, then the connection is simple to implement, but the mounting structure becomes large in size and the connection distance is long

Engineering Contradiction:

Improveease of electrical connectionVSAvoidmounting structure size

Core Design Contradiction:

Ease of manufactureVSVolume of moving object

Solution Approach 1:

Instead of using wire bonding where a wire connects distant points, the invention inverts the approach by using flip-chip mounting where bonding material and metal layers directly connect the semiconductor substrate to the mounting substrate at closely spaced bump locations, eliminating the need for long wires.

Inventive Principle:

Principle #13The other way round (Inversion)

3Ease of manufacture

If wire bonding is used for electrical connection, then the connection method is conventional and simple, but the inductance of the wire increases making high speed driving difficult

Engineering Contradiction:

Improveease of electrical connectionVSAvoiddriving speed

Core Design Contradiction:

Ease of manufactureVSSpeed

Solution Approach 1:

The invention replaces the wire bonding method with flip-chip mounting, inverting the connection architecture from distant wire connections to close-proximity direct bonding. This dramatically reduces the connection path length and wire inductance, enabling high-speed signal transmission while maintaining manufacturing simplicity.

Inventive Principle:

Principle #13The other way round (Inversion)

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 improves bonding strength in flip chip mounting while maintaining high mounting reliability by accelerating intermetallic compound formation, preventing breakage and ensuring reliable electrical connections.

Implementation Method 1

Heat generated by this application of heat causes interdiffusion of metals

Methodology Applied

Scientific EffectInterdiffusion: Diffusion

Implementation Method 2

mounting methods by means of metal bonding allow attainment of high mounting reliability

Methodology Applied

Scientific EffectMetal bonding: Diffusion Welding

Implementation Method 3

Heat is applied to the metals used for carrying out the metal bonding so as to bond these metals together

Methodology Applied

Scientific EffectThermal heating: Heating

Data Source

PatentUS8148819B2Semiconductor device, method for mounting semiconductor device, and mounting structure of semiconductor device

Publication Date: 2012.04.03 SHARP KK

AI summary

A semiconductor device includes a semiconductor substrate on which an electrode and a Cu bump are stacked. On the electrode and the Cu bump, a metal bump layer is provided. The metal bump layer comprises (i) a solder layer via which the semiconductor device is bonded and electrically connected to the mounting substrate by metal bonding and (ii) a Cu layer. A intermetallic compound can be formed by interdiffusion of the Cu layer and the solder layer.