Semiconductor Bump Structure With Barrier Layer For Reliability
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Solution Overview
Problem
The reliability of semiconductor device bumps is hindered by the formation of intermetallic compound (IMC) layers, as existing techniques fail to effectively control the constituent materials and dimensions of these layers, affecting the size and reliability of the bumps.
Innovation Solution
A semiconductor device structure is developed with a conductive support layer, a barrier layer, and an IMC layer, where the conductive support layer has a smaller width than the IMC layer, and a solder layer is formed on the IMC layer, with a reaction layer between the barrier and IMC layers, using specific materials like copper, nickel, and tin-silver, and a reflow process to form the IMC layer, ensuring alignment and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the size of bumps is reduced to achieve higher integration, then the density of semiconductor devices increases, but the reliability of bumps deteriorates
Solution Approach 1:
The bump structure is segmented into multiple functional layers: conductive support layer, barrier layer, IMC layer, and solder layer. Each layer performs a specific function, allowing the bump to maintain reliability even as overall size is reduced for higher integration density.
Solution Approach 2:
The bump employs composite material structure with different metal layers (Cu, Ni, SnAg, CuSn) stacked together. This composite approach allows each material to contribute its optimal properties, maintaining mechanical and electrical reliability while enabling smaller bump dimensions.
2Strength
If the IMC layer is formed between different metal layers to improve bonding, then the bonding strength increases, but the control over constituent materials and dimensions becomes difficult
Solution Approach 1:
The barrier layer is formed in advance on the conductive support layer before the IMC layer formation process. This preliminary action prevents unwanted material diffusion and enables precise control over the IMC layer's constituent materials and dimensions during subsequent processing.
Solution Approach 2:
The barrier layer acts as an intermediary between the conductive support layer and the IMC layer. It mediates the interaction between different metals, allowing the IMC layer to form with controlled composition and thickness while maintaining bonding strength.
3Reliability
If a barrier layer is introduced between the conductive support layer and IMC layer to control reactions, then the reliability improves, but the device complexity increases
Solution Approach 1:
The barrier layer serves as a thin intermediary film that prevents harmful reactions between the conductive support layer and IMC layer. Despite adding a layer, its thin nature and specific material properties minimize the overall complexity increase while significantly improving reliability.
Solution Approach 2:
The barrier layer's thickness and material composition are precisely controlled within specific parameter ranges. By optimizing these parameters, the layer provides effective reaction control without excessively increasing device complexity or manufacturing difficulty.
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 configuration enhances the reliability of semiconductor device bumps by controlling the dimensions and materials of the IMC layer, preventing unwanted reactions that reduce reliability, and maintaining the integrity of the bump structure.
Implementation Method 1
using specific materials like copper, nickel, and tin-silver, and a reflow process to form the IMC layer
Data Source
AI summary
According to aspects provided herein, a semiconductor device may include a bump providing improved reliability and reduced size. In some aspects, a conductive pad may be formed on a substrate, and a conductive support layer, which may be a pillar, may be formed on the conductive pad. An intermetallic compound (IMC) layer may be formed on the conductive support layer, and a solder layer may be formed on the IMC layer. In some aspects, the conductive support layer may be of a smaller width than the IMC layer. In some aspects, the conductive support layer may have side surfaces which are wider at the solder side than at the conductive pad side. In some aspects, other layers may be formed, such as a seed layer between the conductive pad and the conductive support layer, or a barrier layer between the conductive support layer and the IMC layer.