Semiconductor Device Barrier Layer for Flip-Chip Joint Reliability
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Solution Overview
Problem
Semiconductor devices with flip-chip mounting experience thermal stress-induced cracks at the solder-electrode joint due to thermal expansion differences, affecting their operation.
Innovation Solution
A semiconductor device configuration that includes a semiconductor element, conducting members, a conductive bonding material, and barrier layers to prevent reaction and void formation at the solder-electrode interface, using materials like Cu, Ni, and Sn, with barrier layers positioned between electrodes and conductive bonding material to mitigate thermal stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solder is directly bonded to the electrode without a barrier layer, then the manufacturing process is simple, but thermal stress causes cracks at the joint interface between solder and electrode
Solution Approach 1:
A barrier layer is introduced as an intermediary between the electrode and the conductive bonding material (solder). This barrier layer prevents direct contact between dissimilar metals, blocking the formation of brittle intermetallic compounds that cause cracks under thermal stress, thereby improving joint reliability without significantly complicating the overall device structure
Solution Approach 2:
The joint structure is designed as a composite multi-layer system consisting of electrode, barrier layer, and conductive bonding material. Each layer is selected for its specific properties: the electrode provides electrical connection, the barrier layer prevents chemical reaction and reduces thermal stress, and the bonding material ensures mechanical attachment, together creating a more reliable composite joint
2Reliability
If a barrier layer is added between electrode and conductive bonding material, then crack resistance is improved, but manufacturing complexity increases
Solution Approach 1:
The barrier layer is formed on the electrode surface before the conductive bonding material is applied. This preliminary action of pre-coating the electrode with a protective barrier layer ensures that the electrode is already protected against chemical reactions and thermal stress during subsequent bonding and operation, simplifying the overall manufacturing sequence
Solution Approach 2:
The barrier layer modifies the surface properties and thermal characteristics of the electrode. By changing the material parameters at the interface (introducing a layer with intermediate thermal expansion coefficient and chemical stability), the system achieves better thermal stress resistance and chemical compatibility, improving joint durability while maintaining manufacturability
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
Prevents crack formation at the solder-electrode interface, enhancing the reliability and durability of semiconductor devices under varying temperature conditions.
Implementation Method 1
a first barrier layer which is disposed between the electrode and the conductive bonding material and prevents the electrode and the conductive bonding material from reacting with each other
Implementation Method 2
During the temperature change, thermal stress may be induced due to the thermal expansion difference between, for example, the semiconductor element and the leads
Data Source
AI summary
A semiconductor device includes a semiconductor element, a conducting member, a conductive bonding material, a resin member and a first barrier layer. The semiconductor element includes an element first surface and an element second surface facing away from each other in a thickness direction, with the element first surface provided with an electrode. The conducting member includes an obverse surface facing the element first surface and a reverse surface facing away from the obverse surface. The conductive bonding material is disposed between the electrode and the obverse surface of the conducting member. The resin member covers at least a portion of the conducting member, the semiconductor element and the conductive bonding material. The first barrier layer is disposed between the electrode and the conductive bonding material to prevent a reaction between the electrode and the conductive bonding material.