Wafer Singulation Using Interposer and Wax Protection
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Solution Overview
Problem
Damage occurs to semiconductor wafers during wafer level packaging, particularly when processing packaging materials like glass, which can be removed and cause damage to the underlying wafer.
Innovation Solution
A method involving an optically transparent wafer and an interposer wafer with channels, where a low viscosity, solventless fluid (liquid wax) is used to protect the semiconductor wafer during sawing, allowing for precise singulation without damaging the wafer by hardening and being easily removable.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If glass packaging material is removed from the semiconductor wafer, then the wafer can be accessed for further processing, but the underlying semiconductor wafer becomes damaged
Solution Approach 1:
The patent introduces an interposer wafer as an intermediary layer between the glass packaging material and the semiconductor wafer. This interposer wafer absorbs the mechanical stress and damage from glass removal, protecting the valuable semiconductor wafer underneath while still allowing access for further processing.
Solution Approach 2:
The patent applies a protective coating to the semiconductor wafer before the glass removal process. This preliminary protective layer prevents direct contact between the removal tools and the semiconductor wafer, thereby preventing damage during the glass removal operation.
2Object-affected harmful factors
If a protective layer is applied to the semiconductor wafer, then the wafer is protected from damage, but the processing complexity increases
Solution Approach 1:
The patent uses a water-soluble protective coating that can be easily removed by washing with water after the glass removal process. This approach maintains protection during the critical removal operation while simplifying the post-processing steps, as the protective layer is removed through a simple washing operation rather than complex removal procedures.
3Productivity
If the wafer is singulated into individual dies, then individual packaging is enabled, but the wafer structure becomes compromised
Solution Approach 1:
The patent introduces an interposer wafer layer that can be independently segmented into individual dies after bonding to the semiconductor wafer. This allows the semiconductor wafer to remain intact and structurally sound while the interposer wafer is divided into individual packages, enabling individual packaging without compromising the semiconductor wafer structure.
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 effectively reduces or avoids damage to semiconductor wafers by using a removable wax to protect the wafer during processing, ensuring precise singulation and minimizing harm to the underlying semiconductor material.
Implementation Method 1
applying wax into the second channel, and sawing through the optically transparent wafer and through at least a portion of the interposer wafer
Implementation Method 2
The wax solution is then removed to expose a portion of the first surface of the semiconductor wafer
Data Source
AI summary
A method includes attaching an optically transparent wafer to a first surface of an interposer wafer. The interposer wafer has a second surface opposite the first surface, and the second surface has a first channel therein. The method further includes attaching the interposer wafer to a first surface of a semiconductor wafer, and etching a second channel through the optically transparent wafer and through the interposer wafer. The method then includes applying wax into the second channel, and sawing through the optically transparent wafer and through at least a portion of the interposer wafer to form a third channel having a width that is wider than a width of the second channel. The wax is then removed to expose a portion of the first surface of the semiconductor wafer.