Semiconductor Connecting Structure With Dual IMC Layers for Void-Free Bonding
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Solution Overview
Problem
Existing semiconductor device packaging technologies face challenges in achieving reliable and stable bonding between conductive elements, leading to issues such as solder collapse and intermetallic compound shrinkage voids, which affect the reliability and integrity of the connections.
Innovation Solution
A multi-layer metal structure is formed with a seed layer, followed by sequential deposition of metal layers and a thermal process to create a connecting structure with intermetallic compounds, including Cu—Ni—Sn and Ni—Sn intermetallic compounds, which stabilize the bond and reduce copper consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional bonding method is used to connect conductive elements, then the bonding process is simple, but solder collapse and intermetallic compound shrinkage voids occur, reducing connection reliability
Solution Approach 1:
The bonding structure is segmented into multiple functional layers: a copper pillar layer, a solder layer, and an intermetallic compound layer. This segmentation allows each layer to perform its specific function optimally - the copper pillar provides structural support and electrical connection, the solder layer provides bonding functionality, and the intermetallic compound layer prevents void formation. By dividing the bonding structure into these distinct segments, the patent achieves improved reliability without excessive complexity.
Solution Approach 2:
The patent applies preliminary action by pre-forming the copper pillar structure with controlled dimensions and properties before the bonding process. The copper pillar is prepared in advance with specific height, diameter, and surface characteristics that prevent solder collapse and intermetallic compound shrinkage voids during subsequent bonding operations. This preliminary preparation ensures that the bonding process proceeds smoothly with improved reliability.
2Loss of substance
If copper consumption is reduced in the bonding structure, then material cost and weight decrease, but bonding reliability and stability are compromised
Solution Approach 1:
The patent applies parameter changes by optimizing the copper pillar dimensions (height, diameter, wall thickness) to achieve the minimum required copper consumption while maintaining bonding reliability. The copper pillar parameters are precisely controlled within specific ranges to ensure sufficient mechanical strength and electrical conductivity without excessive copper usage. This parameter optimization resolves the contradiction between reducing copper consumption and maintaining bonding stability.
Solution Approach 2:
The patent uses composite materials by combining copper pillar structure with solder layer and intermetallic compound layer to create a multi-material bonding structure. This composite approach allows the system to achieve the required mechanical and electrical properties with reduced copper consumption, as the solder and intermetallic compound layers contribute to overall bonding strength and stability. The composite structure distributes functional requirements across multiple materials, reducing reliance on excessive copper.
3Ease of manufacture
If the bonding structure is simplified, then manufacturing process is easier, but void formation increases and connection durability decreases
Solution Approach 1:
The patent applies local quality by creating an intermetallic compound layer with specific local properties at the bonding interface. This intermetallic compound layer has distinct characteristics (composition, structure, properties) that are tailored to prevent void formation and improve connection durability. By providing this specialized local quality at the critical bonding interface, the patent achieves improved manufacturing precision regarding void control without significantly complicating the overall manufacturing process.
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 proposed method enhances bonding reliability by maintaining sufficient solder volume and reducing void formation, ensuring stable connections with improved durability and reduced copper consumption during high-temperature storage.
Implementation Method 1
performing a thermal process to form a connecting structure
Implementation Method 2
create a connecting structure with intermetallic compounds, including Cu—Ni—Sn and Ni—Sn intermetallic compounds
Data Source
AI summary
A structure including a substrate having a conductive pad and a connecting structure disposed on the conductive pad and electrically connected to the conductive pad. The connecting structure includes a first metallic layer disposed on the conductive pad, a first intermetallic compound layer disposed on the first metallic layer, a second intermetallic compound layer disposed on the first intermetallic compound layer and a second metallic layer disposed on the second intermetallic compound layer. The first metallic layer comprises copper. The first intermetallic compound layer comprises a first intermetallic compound. The second intermetallic compound layer comprises a second intermetallic compound different from the first intermetallic compound. The second metallic layer comprises tin. The first intermetallic compound contains copper, tin and one of nickel and cobalt.