Semiconductor Die Packaging With Sidewall Passivation for Precise Thinning
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Solution Overview
Problem
Existing methods for thinning semiconductor dies during or after die to wafer bonding are costly and inefficient, requiring excessive dielectric materials and processes that compromise the integrity and precision of the dies.
Innovation Solution
A method involving the application of a conformal polymer film layer on semiconductor dies, followed by anisotropic plasma etching to selectively remove the film from top surfaces while preserving it on side surfaces, allowing precise thinning of the dies with minimal material usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a thick dielectric film is deposited to fill gaps between dies, then the gaps are filled, but excessive dielectric material covers the die surfaces requiring grinding and polishing
Solution Approach 1:
The patent applies a conformal film coating that selectively covers only the side surfaces of the dies while leaving the top surfaces exposed. This localized application ensures that the film is present only where needed for gap filling, eliminating the waste of excessive material coverage on die surfaces that would require subsequent grinding and polishing.
2Manufacturing precision
If conventional plasma etching is used without side wall protection, then the top surfaces are etched, but the side walls are damaged
Solution Approach 1:
The conformal film acts as an intermediary protective layer on the side walls during plasma etching. This film barrier protects the side walls from plasma damage while allowing precise etching of the top surfaces, thereby maintaining both etching precision and side wall integrity without requiring additional protection steps.
3Length of moving object
If chemical mechanical polishing is used for die thinning, then the die thickness is reduced, but the process is slow and costly
Solution Approach 1:
The patent replaces the mechanical chemical mechanical polishing process with plasma etching for die thinning. This substitution enables much faster material removal rates while achieving the required thickness reduction, significantly improving productivity and reducing process costs compared to conventional polishing methods.
4Length of moving object
If excessive dielectric filler material is used for die thinning, then the thinning is achieved, but the process becomes prohibitively expensive
Solution Approach 1:
The conformal film is applied selectively to cover only the side surfaces of the dies, providing precise control over die thickness during plasma etching without requiring excessive dielectric filler material. This localized application minimizes material usage while achieving the required thickness control, making the process cost-effective.
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
Enables high-precision thinning of semiconductor dies with a smooth horizontal surface and preserved side walls, achieving an etch rate of approximately 1-10µm/minute, reducing material costs and maintaining die integrity.
Implementation Method 1
plasma etching the top surfaces of the dies
Implementation Method 2
the etch of the semiconductor dies is almost perfectly anisotropic in the vertical direction due to the use of the film layer which provides selective passivation of the die side walls during the main etch
Implementation Method 3
the film layer which provides selective passivation of the die side walls during the main etch
Implementation Method 4
current plasma enhanced chemical vapour deposition (PECVD) SiO 2 films
Data Source
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AI summary
There is provided a method of packaging semiconductor dies. The method comprises a first step of providing a substrate and a plurality of semiconductor dies interspaced on the substrate, there being an exposed surface of the substrate between the dies. Thereafter, a film is applied to the substrate to cover the plurality of semiconductor dies and the exposed substrate surface with a film layer, wherein each die comprises a top surface and at least one side surface, and wherein the film layer extends across the top surfaces and along the side surfaces of the dies. Subsequently, the film is removed from the top surfaces of the dies, whilst leaving the film intact on the side surfaces of the dies. Thereafter the top surfaces of the dies are plasma etched and the film is removed from the side surfaces of the dies. The semiconductor dies are thinned for use in a variety of end applications.