Integrated Circuit Die Connector with Copper Insertion Layer
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Solution Overview
Problem
Current integrated circuit structures face limitations in achieving efficient three-dimensional integration due to issues with void formation and solder joint reliability, particularly during thermal cycling, which affect device performance and reliability.
Innovation Solution
The integration of a connector structure between dies using micro bumps and controlled collapse chip connection (C4) bumps, along with an intermetallic compound (IMC) layer formed from copper and tin, which reduces solder diffusion and void formation by consuming metal insertion layers to form stable IMC layers like Cu6Sn5 and Cu3Sn, enhancing the reliability of solder joints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional soldering methods are used to connect dies, then electrical connectivity is achieved, but void formation occurs and solder joint reliability deteriorates during thermal cycling
Solution Approach 1:
A copper insertion layer is introduced as an intermediary between the solder joint and the die substrate. This copper layer acts as a mediator that reacts with tin from the solder to form intermetallic compounds (Cu6Sn5 and Cu3Sn), which reduces void formation and improves solder joint reliability during thermal cycling.
Solution Approach 2:
The invention changes the chemical composition and structure of the solder joint interface by introducing copper and controlling the formation of intermetallic compounds. This parameter change in the material composition (adding copper insertion layer) transforms the soldering process outcome, reducing voids and improving reliability.
2Reliability
If copper and tin layers are used to form connectors, then electrical conductivity is achieved, but solder diffusion increases causing reliability issues
Solution Approach 1:
The copper insertion layer is placed beforehand between the tin layer and the substrate, performing a preliminary action to control the interaction between solder and substrate. This pre-positioned copper layer manages solder diffusion by providing a controlled interface for intermetallic compound formation, preventing uncontrolled solder spread.
Solution Approach 2:
The copper insertion layer serves as an intermediary that controls and limits solder diffusion. By positioning copper between the solder tin and the substrate, it mediates the diffusion process, allowing controlled formation of intermetallic compounds while preventing excessive solder spread that would compromise connector reliability.
3Reliability
If micro bumps and C4 bumps are integrated for connectivity, then electrical connection is established, but structural integrity is compromised due to voids
Solution Approach 1:
The invention changes the material parameters at the solder joint interface by introducing a copper insertion layer. This parameter change alters the metallurgical reaction products, promoting the formation of dense intermetallic compound layers (Cu6Sn5 and Cu3Sn) that eliminate voids and improve structural integrity of the bump connections.
Solution Approach 2:
The connector structure becomes a composite material system consisting of multiple layers: solder, copper insertion layer, and intermetallic compounds. This composite structure combines the advantages of different materials to create a void-free, structurally integrity connection that withstands thermal cycling better than traditional homogeneous solder joints.
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 solution significantly improves device performance and reliability by minimizing voids in solder joints and enhancing thermal cycling and high-temperature storage test results, demonstrating improved connectivity and structural integrity between dies.
Implementation Method 1
an intermetallic compound (IMC) layer formed from copper and tin, which reduces solder diffusion and void formation by consuming metal insertion layers to form stable IMC layers like Cu6Sn5 and Cu3Sn
Data Source
AI summary
An embodiment is an integrated circuit structure including a first die attached to a second die by a first connector. The first connector includes a solder joint portion between a first nickel-containing layer and a second nickel-containing layer, a first copper-containing layer between the first nickel-containing layer and the solder joint portion, and a second copper-containing layer between the second nickel-containing layer and the solder joint portion.