Patterned Adhesive Film Self-Alignment for Die Stacking
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Solution Overview
Problem
Conventional die-to-wafer bonding techniques face challenges with alignment issues, limited I/O pad density, and reliability due to misalignment and bubble formation during molding compound filling, which reduce throughput and increase the risk of die breakage and device damage.
Innovation Solution
A method involving a patterned adhesive film with die-holding openings is used to self-align top dies onto bottom dies, eliminating the need for additional alignment steps and serving as a molding compound substitute, thereby enhancing throughput and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional alignment steps are performed for each top die bonding, then bonding precision is improved, but throughput is significantly reduced
Solution Approach 1:
The adhesive film is pre-patterned with openings at precise positions before bonding. This preliminary positioning structure eliminates the need for time-consuming alignment steps during the bonding process, as top dies automatically align with bottom dies through the pre-defined opening positions in the adhesive film.
Solution Approach 2:
The adhesive film structure provides self-alignment functionality. The openings in the adhesive film automatically guide and position the top dies over the correct bottom die locations without requiring external alignment equipment or procedures, enabling the system to self-align during bonding.
2Ease of manufacture
If molding compound is filled into gaps between top dies, then package structure is completed, but bubbles are generated causing die breakage and device damage
Solution Approach 1:
The adhesive film is removed from the bonding process and replaced with a patterned adhesive layer that is integrated into the substrate. This eliminates the separate adhesive film material that could trap bubbles, while still providing the necessary bonding and alignment functions.
Solution Approach 2:
The patterned adhesive layer serves as an intermediary structure that combines the alignment function (through its patterned openings) and bonding function (through the adhesive material) into a single integrated component, eliminating the need for separate adhesive films and reducing bubble formation risks.
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
The method significantly increases bonding throughput by ensuring accurate self-alignment of top dies on bottom dies and eliminates bubble-related issues, improving the reliability and efficiency of the die-to-wafer bonding process.
Implementation Method 1
a second adhesive film is different from the first adhesive film in that the second adhesive film comprises a plurality of isolated adhesive regions distributed over a non-adhesive background
Data Source
AI summary
A method of forming integrated circuits includes laminating a patterned film including an opening onto a wafer, wherein a bottom die in the wafer is exposed through the opening. A top die is placed into the opening. The top die fits into the opening with substantially no gap between the patterned film and the top die. The top die is then bonded onto the bottom die, followed by curing the patterned film.