Protective Layer for Semiconductor Die Assembly
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Solution Overview
Problem
Conventional semiconductor die assembly methods face issues such as backgrinding tape residue, uneven wafer thinning, and flux residue, which lead to delamination, electrical faults, and reduced yield in the assembly of thin integrated circuit dies to substrates.
Innovation Solution
A protective layer is applied over the connector terminals and the active surface of the semiconductor wafer, which covers the lower portion of the terminals and provides mechanical support during backgrinding, preventing tape residue and flux interference, and allowing for controlled wafer thinning without complete sawing through the wafer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If backgrinding tape is applied over connector terminals during wafer thinning, then mechanical support is provided during backgrinding, but tape residue remains on terminals causing delamination and electrical faults
Solution Approach 1:
A protective layer of underfill material is applied over the connector terminals before backgrinding. This protective layer acts as an intermediary between the backgrinding tape and the connector terminals, allowing the tape to be applied for mechanical support during thinning while preventing direct contact and residue deposition on the terminals. The protective layer is subsequently removed after backgrinding, leaving the terminals clean and free of tape residue.
2Manufacturing precision
If wafer is thinned by backgrinding without protective measures, then thinning is achieved, but uneven stress concentrations cause uneven wafer thinning
Solution Approach 1:
The protective layer of underfill material is applied beforehand over the connector terminals and active surface areas. This protective layer cushions and distributes the mechanical stress during backgrinding, preventing concentrated stress points that would cause uneven thinning. The protective layer ensures uniform stress distribution across the wafer surface during the thinning process.
3Ease of manufacture
If complete sawing through the wafer is performed to separate dies, then die separation is achieved, but mechanical damage and increased complexity occur
Solution Approach 1:
Instead of completely sawing through the wafer to separate the dies, the backgrinding process is used to thin the wafer to a point where the dies can be separated with minimal or no additional sawing. The protective layer enables this partial action by providing the necessary mechanical support during backgrinding, allowing die separation to be achieved with reduced mechanical intervention and lower risk of damage.
Data Source
AI summary
Methods and apparatus for die assembly. A method includes forming a trench extending from an active surface of a semiconductor substrate comprising a plurality of integrated circuit dies having connector terminals extending from the active surface, the trench extending into, but not through, the semiconductor substrate; forming a protective layer overlying the active surface of the semiconductor substrate and the trench, and covering the lower portion of the connector terminals; opening a pre-dicing opening in the protective layer and within the trench; applying a tape over the active surface of the semiconductor wafer, the protective layer and the connector terminals; and performing an operation on a backside of the semiconductor substrate to remove material until the pre-dicing opening is exposed on the backside of the semiconductor wafer. An apparatus includes a semiconductor substrate with integrated circuits and a protective layer surrounding connector terminals of integrated circuits.