Semiconductor Package Conductive Pad with Barrier Layer for IMC Control
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Solution Overview
Problem
The formation of an intermetallic compound (IMC) layer between solder balls and copper pads in semiconductor packages can lead to cracks or voids, affecting the connection and hindering miniaturization due to the need for increased pad thickness to prevent IMC extension.
Innovation Solution
A semiconductor device package design featuring a conductive pad with a barrier layer sandwiched between two conductive layers, embedded within a dielectric layer, which prevents the IMC layer from extending and enhances connection strength while reducing manufacturing costs and time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solder balls are directly bonded to copper pads, then electrical connection is achieved, but intermetallic compound layer formation causes cracks or voids affecting connection reliability
Solution Approach 1:
The patent introduces a multi-layer conductive pad structure with barrier layers (e.g., nickel, titanium) between the solder balls and copper pads. These intermediary layers prevent direct contact between solder and copper, blocking IMC formation while maintaining electrical connectivity. The barrier layers act as mediators that resolve the harmful interaction between solder balls and copper pads.
Solution Approach 2:
The conductive pad is constructed as a composite structure with multiple material layers including copper, nickel, and titanium. Each layer serves specific functions: copper provides electrical conductivity, while nickel and titanium layers prevent IMC formation. This composite approach combines materials with complementary properties to eliminate the harmful effect of IMC while maintaining connection reliability.
2Reliability
If pad thickness is increased to prevent IMC extension, then connection reliability improves, but package size increases hindering miniaturization
Solution Approach 1:
The patent applies different material properties at different locations within the conductive pad structure. The barrier layers are strategically positioned at the interface where IMC formation occurs, providing localized protection without requiring increased overall pad thickness. This local quality approach maintains reliability while enabling miniaturization.
Solution Approach 2:
The patent changes the material composition parameters of the conductive pad by introducing barrier layers with specific properties (nickel, titanium) that have different IMC formation characteristics compared to pure copper. This parameter change allows thin pad structures to prevent IMC extension effectively, enabling package thinning while maintaining reliability.
3Reliability
If multi-layer conductive pad structure with barrier layers is implemented, then IMC extension is blocked and connection strength is enhanced, but manufacturing complexity increases
Solution Approach 1:
The barrier layers are formed as part of the pad structure before solder ball attachment. This preliminary action of pre-configuring the multi-layer structure with IMC-blocking properties eliminates the need for complex post-assembly processes. The structure is prepared in advance to prevent IMC formation, simplifying the overall manufacturing workflow despite the multi-layer complexity.
Solution Approach 2:
The multi-layer conductive pad structure serves multiple functions simultaneously: electrical conductivity, IMC prevention, mechanical strength enhancement, and miniaturization enablement. By consolidating these functions into a single integrated structure, the patent reduces overall device complexity compared to using separate components for each function.
Data Source
AI summary
A semiconductor device package includes a first dielectric layer, a conductive pad and an electrical contact. The first dielectric layer has a first surface and a second surface opposite to the first surface. The conductive pad is disposed within the first dielectric layer. The conductive pad includes a first conductive layer and a barrier. The first conductive layer is adjacent to the second surface of the first dielectric layer. The first conductive layer has a first surface facing the first surface of the first dielectric layer and a second surface opposite to the first surface. The second surface of the first conductive layer is exposed from the first dielectric layer. The barrier layer is disposed on the first surface of the first conductive layer. The electrical contact is disposed on the second surface of the first conductive layer of the conductive pad.