Low-Temperature Chip-Package Form Closure for Thermal Stress Reduction
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Solution Overview
Problem
The integration of semiconductor devices faces reliability and yield issues due to thermal mismatch between silicon-based chips and organic package substrates, leading to mechanical stress and delamination of low-k dielectric materials, which are exacerbated by the use of lead-free materials and increased complexity in metallization systems.
Innovation Solution
The solution involves establishing mechanical connections between the package substrate and semiconductor chip through form closure without solder, using metal-containing contact elements that engage via a socket and plug-like configuration, eliminating the need for high-temperature solder processes and reducing thermally induced mechanical stresses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solder processes are used to connect package substrate to semiconductor chip, then reliable electrical and mechanical connection is achieved, but thermally induced mechanical stresses and delamination of low-k dielectric materials occur
Solution Approach 1:
The patent changes the temperature parameter from high-temperature soldering (typically 200-400°C) to low-temperature mechanical engagement (below 100°C). This parameter change eliminates thermal expansion mismatch between silicon chip and organic package substrate, preventing delamination of low-k dielectric materials while maintaining connection reliability through form closure mechanical engagement
Solution Approach 2:
The patent replaces the thermal-field-based soldering process with a mechanics-based form closure engagement system. Instead of using heat and molten solder to create joints, the invention uses precisely engineered complementary geometric shapes that mechanically interlock, substituting a thermal process with a mechanical one that avoids thermally induced stress
2Adaptability or versatility
If lead-free materials are used in bump structures, then environmental compliance is achieved, but mechanical stability and adhesion of dielectric materials are reduced
Solution Approach 1:
The patent extracts and eliminates the solder material from the connection process entirely. By removing the solder bump structure and replacing it with direct mechanical engagement of complementary contact elements, the invention eliminates the need for lead-free solder while avoiding the mechanical stability issues associated with lead-free materials and their interaction with low-k dielectrics
3Reliability
If high-temperature processes are used for connecting package and chip, then reliable solder joints are formed, but delamination of low-k dielectric layers occurs
Solution Approach 1:
The patent fundamentally changes the temperature parameter from high-temperature soldering processes (200-400°C) to low-temperature mechanical engagement (below 100°C). This parameter change prevents thermal expansion mismatch between materials, eliminating the root cause of delamination while maintaining joint reliability through precise mechanical form closure engagement
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 approach enhances mechanical stability, reduces the risk of delamination, and allows for the use of flexible metal materials, improving the reliability and yield of semiconductor devices by avoiding thermally induced mechanical stresses and allowing for more flexible process conditions.
Implementation Method 1
The contact elements may be elastically deformed during the process of mechanically engaging the package contact element with the chip contact element
Implementation Method 2
The sticking friction may provide superior mechanical stability
Data Source
AI summary
A semiconductor chip and a package substrate may be directly connected on the basis of form closure by providing appropriately shaped complementary contact structures in the semiconductor chip and the package substrate. Consequently, solder material may no longer be required and thus any elevated temperatures during the assembly process may be avoided, which may conventionally result in significant stress forces, thereby creating damage, in particular in very complex metallization systems.