Stacked Semiconductor Die Structure for Flat Bonding and Dense Singulation
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Solution Overview
Problem
The existing die bonding processes face challenges in maintaining the flatness of bonding surfaces due to the need for metal-free zones in the test line area, which reduces the space for semiconductor dies and complicates the singulation process, leading to reduced output and reliability issues.
Innovation Solution
A dual-dicing method is employed, where a first trench is formed on the front-side of a wafer using plasma dicing, followed by flipping and forming a second trench on the backside using laser grooving, ensuring the singulated dies have a narrow top and wide bottom configuration, allowing for gap-free bonding and increased die density without metal-free zones.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If metal-free zones are added in the test line area to facilitate singulation, then the singulation process can be simplified, but the space for semiconductor dies is reduced
Solution Approach 1:
The singulation process is divided into two separate stages: first forming a partial trench to separate the metal interconnect layer, then forming a through-trench to complete the separation. This segmentation allows each stage to be optimized independently, eliminating the need for metal-free zones while maintaining manufacturing ease.
Solution Approach 2:
The partial trench is formed in advance before the through-trench formation. This preliminary action removes metal from the singulation path beforehand, allowing the subsequent through-trench formation to proceed without metal interference, thereby eliminating the requirement for metal-free zones in the test line area.
2Ease of manufacture
If laser grooving is used to cut through metal, then the singulation can be completed, but the flatness of bonding surfaces is reduced
Solution Approach 1:
The cutting process is segmented into two steps: first using plasma dicing to create a partial trench that removes metal, then using laser grooving to complete the through-trench. This segmentation ensures that laser grooving is applied only where necessary, preserving bonding surface flatness while achieving complete singulation.
Solution Approach 2:
The partial trench formed by plasma dicing acts as an intermediary structure that facilitates the subsequent laser grooving process. By pre-removing metal and creating a controlled starting point, the intermediary partial trench enables the laser to form the through-trench without compromising the flatness of the bonding surfaces.
3Manufacturing precision
If plasma dicing is used to maintain bonding surface flatness, then the bonding quality is improved, but the process cannot cut through metal
Solution Approach 1:
The singulation process is segmented into two functional parts: plasma dicing for forming the partial trench that maintains surface flatness, and laser grooving for completing the through-trench that cuts through metal. Each process is optimized for its specific function, resolving the contradiction between flatness maintenance and metal cutting capability.
Solution Approach 2:
Two different dicing methods (plasma dicing and laser grooving) are merged into a single integrated singulation process. The plasma dicing step handles the metal removal and surface flatness maintenance, while the laser grooving step completes the through-cut, combining the advantages of both methods to overcome their individual limitations.
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 maintains the flatness of bonding surfaces, enhances die density, and improves the reliability of the semiconductor structure by enabling gap-free bonding and facilitating the use of insulating materials, thus increasing the number of semiconductor dies per wafer.
Implementation Method 1
forming at least one first trench on the front-side surface of the first wafer
Implementation Method 2
forming at least one second trench on the backside surface of the first wafer to cut through the metal
Data Source
AI summary
A semiconductor structure, a package structure and a manufacturing method of a semiconductor structure are provided. The semiconductor structure includes a first semiconductor die, a second semiconductor die and an insulating encapsulant. The second semiconductor die is overlapped with and electrically connected to the first semiconductor die. The insulating encapsulant is disposed on the second semiconductor die and at least laterally encapsulates the first semiconductor die. The first semiconductor die includes a first portion and a second portion located between the first portion and the second semiconductor die. In a sectional view, the second portion is wider than the first portion.