Molded Die Stack Hybrid Bonding for Misalignment Tolerance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing techniques for stacking and bonding dies or wafers face challenges due to the requirement for extremely flat, smooth, and clean surfaces, which can be difficult to achieve, especially when misalignment occurs during the stacking process.
Innovation Solution
The use of hybrid bonding techniques, such as direct dielectric bonding and metal-to-metal bonding, without adhesives, allows for the stacking and bonding of dies or wafers with minimal surface preparation, while also enabling the formation of continuous conductive interconnects between stacked devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If direct bonding or hybrid bonding techniques are used to stack dies or wafers, then reliable electrical interconnection is achieved, but the surfaces must be extremely flat, smooth, and clean which increases manufacturing difficulty
Solution Approach 1:
The patent introduces an underfill material as an intermediary substance between the bonding surfaces of dies or wafers. This underfill compensates for surface imperfections and misalignments, enabling reliable bonding without requiring extremely flat and smooth surfaces. The underfill material fills gaps and voids, providing mechanical support and electrical insulation while allowing the bonding process to proceed with relaxed surface preparation requirements.
Solution Approach 2:
The patent modifies the bonding process by controlling various parameters including applying heat and pressure during bonding, using specific underfill materials with appropriate viscosity and curing characteristics, and adjusting bonding temperature and time. These parameter changes enable bonding to succeed even when surfaces are not perfectly flat, thereby reducing manufacturing precision requirements while maintaining bonding reliability.
2Adaptability or versatility
If adhesive materials are used in bonding, then misalignment can be compensated, but the bonding speed decreases and thermal management becomes more difficult
Solution Approach 1:
The patent employs underfill material that can be easily applied and cured in a rapid process, replacing traditional slow-curing adhesives. The underfill provides sufficient misalignment compensation during the brief bonding process and then serves as a permanent structural element, eliminating the need for slow-curing adhesive materials while maintaining misalignment tolerance.
Solution Approach 2:
The patent changes the bonding parameters by using heat-curable or UV-curable underfill materials that set rapidly under controlled conditions. This allows misalignment compensation to be achieved during the brief curing process rather than requiring slow-curing adhesives, thereby maintaining high bonding speed while providing adaptability to misalignment.
3Productivity
If multiple dies are stacked vertically, then device density increases, but thermal management becomes more challenging
Solution Approach 1:
The patent uses thermally conductive underfill materials as intermediaries between stacked dies. These underfill materials provide thermal pathways that conduct heat away from the dies, preventing heat accumulation in the vertical stack. The underfill acts as a thermal management interface that maintains acceptable operating temperatures while enabling high device density through vertical stacking.
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 enables reliable bonding and efficient interconnection between stacked dies or wafers, even with misalignment, while providing enhanced thermal management and connectivity options.
Implementation Method 1
The direct dielectric bonding techniques include a spontaneous covalent bonding process that takes place at ambient conditions when two prepared dielectric surfaces are brought together
Implementation Method 2
the hybrid bonding technique adds direct metal-to-metal bonds of respective metallic bond pads at the bonding surfaces of the respective dies or wafers, also without an intervening material, forming unified conductive structures
Implementation Method 3
Heated annealing of the metallic bond pads may be used to augment the metal-to-metal bonds
Data Source
AI summary
Dies and/or wafers are stacked and bonded in various arrangements including stacks, and may be covered with a molding to facilitate handling, packaging, and the like. In various examples, the molding may cover more or less of a stack, to facilitate connectivity with the devices of the stack, to enhance thermal management, and so forth.