Semiconductor Bonding via Cavity Intermetallic Layers
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional thermal-compression bonding methods for 3D stacking of semiconductor components require high temperatures, leading to low throughput and risk of oxidation, while alternative low-temperature solutions like indium-based solders lack reliability and high-temperature methods take excessively long, failing to meet industry requirements for speed and efficiency.
Innovation Solution
A method involving the formation of intermetallic compound layers with cavities on semiconductor components, allowing solder insertion at temperatures below its melting point under pressure, without forming a second intermetallic layer, to achieve a strong bond in significantly shorter times, using interdiffusion of contact metals like cobalt and solder materials like tin to create CoSn3 intermetallic layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional thermal-compression bonding is used with Sn-based solder at temperatures above 250°C, then strong bonds are achieved, but the bonding time becomes excessively long (10 minutes or more) and oxidation of microbumps occurs
Solution Approach 1:
The intermetallic layer with cavities is formed on the contact areas before the bonding process. This preliminary preparation creates pre-formed receptacles that guide solder insertion and enable rapid bonding without requiring prolonged heating times, thus resolving the contradiction between bond strength and bonding time
Solution Approach 2:
The intermetallic layer is designed with a cavity structure that provides channels for solder material insertion. This porous/cavity structure allows solder to quickly penetrate and form bonds under pressure, achieving strong bonds in seconds rather than minutes, thereby resolving the time-strength contradiction
2Reliability
If high temperature bonding (>250°C) is applied, then reliable bonds are formed, but the risk of oxidation of microbumps increases and temperature-sensitive devices are damaged
Solution Approach 1:
The invention changes the bonding parameters by using a cavity-containing intermetallic layer that enables effective bonding at lower temperatures (below 250°C). This parameter change maintains bond reliability while eliminating the harmful oxidation effects associated with high-temperature processing
Solution Approach 2:
The intermetallic layer that would normally be considered a barrier to bonding is instead designed with cavities that facilitate solder insertion and rapid bonding at lower temperatures, converting what could be a harmful obstacle into a beneficial bonding structure
3Temperature
If alternative low-temperature solder materials like indium-based solder are used, then bonding temperature is reduced, but the reliability of the bond decreases
Solution Approach 1:
The intermetallic layer with cavities acts as an intermediary structure between the contact areas and the solder material. This intermediary enables low-temperature bonding while maintaining high reliability by providing a controlled pathway for solder insertion and bonding, eliminating the need to compromise on solder material quality
4Temperature
If sharp microcone structures are used on microbumps for mechanical interlocking, then bonding temperature can be reduced, but the throughput remains low due to long bonding times (e.g., 60 seconds)
Solution Approach 1:
The cavity structure in the intermetallic layer provides optimized channels for solder insertion that are more effective than microcone structures. This enables bonding times reduced from 60 seconds to seconds, thereby dramatically improving throughput while maintaining low bonding temperatures and high productivity
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 method enables strong bonds with improved electrical characteristics in less than 10 seconds, maintaining reliability and preventing oxidation, with bonding times as short as 2 seconds and temperatures below 150°C, while ensuring high die shear strength and protecting neighboring dies.
Implementation Method 1
the roughness of the intermetallic layer is such that the intermetallic layer includes cavities suitable for insertion of a solder material in the cavities, under the application of a bonding pressure
Implementation Method 2
using interdiffusion of contact metals like cobalt and solder materials like tin to create CoSn3 intermetallic layers
Data Source
AI summary
A method is disclosed for electrically bonding a first semiconductor component to a second semiconductor component, both components including arrays of contact areas. In one aspect, prior to bonding, layers of an intermetallic compound are formed on the contact areas of the second component. The roughness of the intermetallic layers is such that the intermetallic layers include cavities suitable for insertion of a solder material in the cavities, under the application of a bonding pressure, when the solder is at a temperature below its melting temperature. The components are aligned and bonded, while the solder material is applied between the two. Bonding takes place at a temperature below the melting temperature of the solder. The bond can be established only by the insertion of the solder into the cavities of the intermetallic layers, and without the formation of a second intermetallic layer.