Sinter-Bonded Backside Via Assembly for Stronger Die Attach
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional die-substrate assemblies rely on patterned solder shield layers, which increase fabrication costs, complexity, and reduce bond strength and thermal conductivity due to interference with metallurgical bonding between the backmetal layer, backside via lining, and sintered bond layer.
Innovation Solution
The implementation of sinter-bonded backside via structures that eliminate the need for patterned solder shield layers by filling plated backside vias with a sintered bond material, promoting high-strength metallurgical bonding and low resistance electrical and thermal paths through multi-stage deposition and sintering processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If patterned solder shield layers are used to protect backside vias, then via protection is achieved, but fabrication cost and complexity increase
Solution Approach 1:
The patent removes the patterned solder shield layer from the fabrication process entirely. Instead of using a separate shield layer to protect backside vias, the invention directly forms the sintered bond layer that fills and protects the vias, eliminating the need for the intermediate solder shield structure and its associated patterning steps.
Solution Approach 2:
The invention combines the via protection function and the die attach bonding function into a single sintered bond layer. This layer simultaneously protects the backside vias and provides the bonding interface between the die and substrate, merging multiple functions that were previously performed by separate structures.
2Reliability
If patterned solder shield layers are used, then via protection is achieved, but bond strength decreases
Solution Approach 1:
The patent removes the patterned solder shield layer that was interfering with metallurgical bonding. By eliminating this intermediate layer, direct metallurgical bonding can occur between the backmetal layer, backside via lining, and sintered bond layer, significantly improving bond strength.
Solution Approach 2:
The invention uses a composite sintered bond layer structure that combines multiple materials (sintered metal particles, binder, and metallurgical bonding interfaces) to achieve both via protection and high bond strength simultaneously, replacing the homogeneous solder shield layer approach.
3Reliability
If patterned solder shield layers are used, then via protection is achieved, but thermal conductivity decreases
Solution Approach 1:
The patent removes the patterned solder shield layer that was blocking thermal conduction paths. By eliminating this intermediate layer, continuous thermal conduction paths are established from the die backside through the sintered bond layer to the substrate, improving heat dissipation.
Solution Approach 2:
The sintered bond layer is designed as a composite material with high thermal conductivity characteristics, using sintered metal particles that provide excellent thermal conduction while maintaining via protection, replacing the lower thermal conductivity solder shield layer.
4Strength
If sinter precursor material is applied to fill backside vias, then metallurgical bonding is improved, but process complexity increases
Solution Approach 1:
The patent applies the sinter precursor material to fill the backside vias before the actual die attach sintering process. This preliminary filling action ensures that the vias are pre-filled with bonding material, so that during the subsequent sintering step, metallurgical bonding occurs directly without requiring separate via filling operations.
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 the durability, electrical performance, and thermal performance of microelectronic devices by maximizing bond strength and minimizing voids within the backside via structure, while reducing the likelihood of separation and improving thermal conduction.
Implementation Method 1
sintering the sinter precursor material to yield a sintered bond layer metallurgically bonded to the backside via lining, the backmetal layer, and the die support surface of the electrically-conductive substrate
Data Source
AI summary
Die-substrate assemblies having sinter-bonded backside via structures, and methods for fabricating such die-substrate assemblies, are disclosed. In embodiments, the method includes obtaining an integrated circuit (IC) die having a backside over which a backmetal layer is formed and into which a plated backside via extends. The IC die is attached to an electrically-conductive substrate by: (i) applying sinter precursor material over the backmetal layer and into the plated backside via; (ii) positioning a frontside of the electrically-conductive substrate adjacent the plated backmetal layer and in contact with the sinter precursor material; and (iii) sintering the sinter precursor material to yield a sintered bond layer attaching and electrically coupling the IC die to the frontside of the electrically-conductive substrate through the backmetal layer and through the plated backside via. The sintered bond layer contacts and is metallurgically bonded to the backside via lining.