Die Bonding with Adhesive Protection for Clean Hybrid Bonding
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Solution Overview
Problem
Existing die bonding methods face challenges in ensuring die surface cleanness due to particles and etching by-products from grinding and etching processes, leading to degraded bonding quality and yield in hybrid bonding.
Innovation Solution
A die bonding method involving coating a bonding adhesive on the device wafer, temporarily bonding a carrier wafer, forming a back-side connection structure, dicing the wafer into individual dies, and removing the adhesive to ensure die surface cleanness and protect against contamination and oxidation, while using plasma activation for enhanced bonding strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a wafer is diced by cutting with a grinding wheel and etching through the substrate, then individual dies can be obtained, but particles and etching by-products adhere to the die surface, degrading surface cleanness
Solution Approach 1:
The bonding adhesive is coated on the die surface before the dicing and etching processes. This preliminary coating creates a protective layer that prevents particles and etching by-products from adhering to the die surface during subsequent processing steps.
Solution Approach 2:
The bonding adhesive serves as an intermediary protective layer between the die surface and the harmful particles/by-products generated during dicing and etching. This intermediate layer allows the etching process to proceed while preventing contamination of the die surface.
2Reliability
If hybrid bonding is used to achieve high I/O connection density and better heat dissipation, then bonding performance is improved, but die surface cleanness becomes extremely demanding
Solution Approach 1:
The bonding adhesive is applied in advance before dicing and etching operations. This preliminary protective coating ensures that the die surface maintains high cleanness throughout subsequent processing, thereby enabling high-quality hybrid bonding without compromising surface quality.
Solution Approach 2:
The bonding adhesive, which would normally be removed after bonding, is instead retained as a protective layer during dicing and etching. This converts a potential contaminant into a beneficial protective coating that prevents surface contamination and enables high-quality bonding.
3Object-affected harmful factors
If additional photoresist is used to protect the die surface during etching, then surface protection is improved, but process complexity increases
Solution Approach 1:
The bonding adhesive is designed to serve multiple functions: it provides temporary bonding between wafers during processing and simultaneously acts as a protective coating on the die surface during dicing and etching. This multi-functionality eliminates the need for separate photoresist application steps, thereby reducing process complexity.
Solution Approach 2:
The protective function previously requiring a separate photoresist layer is merged into the bonding adhesive layer. By combining these two functions into a single material layer, the process steps are reduced and overall process complexity is decreased while maintaining adequate surface protection.
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
Ensures improved bonding quality and yield by preventing contamination and oxidation, simplifying the process, and increasing efficiency through the use of the bonding adhesive as a protective layer and plasma activation.
Implementation Method 1
coating a bonding adhesive on the front side of the device wafer and temporarily bonding a carrier wafer thereto
Implementation Method 2
cutting at least the bonding adhesive, the first hybrid bonding structure and the dielectric layer from the front side of the device wafer with a grind wheel to form horizontal and vertical dicing lanes
Implementation Method 3
performing an etching process along the dicing lanes, which proceeds downward through the substrate, thereby completely separating adjacent dies
Implementation Method 4
the bonding adhesive being retained... preventing oxidation of conductive bonding pads
Data Source
AI summary
A die bonding method is disclosed, through coating bonding adhesive on front side of device wafer and bonding carrier wafer thereto, back-side connection structure can be formed on back side of device wafer to lead out an interconnect structure in device wafer to back side of device wafer, and dies thereon can be bonded at front sides to target wafer. Moreover, after device wafer is debonded from carrier wafer, the bonding adhesive is retained on front side of device wafer to provide protection to front side of device wafer during subsequent dicing of device wafer, and to avoid particles or etching by-products produced during dicing process from adhering to front side of device wafer. Such etching by-products are subsequently removed along with the bonding adhesive, ensuring cleanness of front sides of individual dies resulting from dicing process and improved quality of bonding of dies at front sides to target wafer.