Semiconductor Die Separation via Plasma Etching and Adhesive Support
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Solution Overview
Problem
Conventional semiconductor fabrication processes face inefficiencies in separating small-sized semiconductor dies due to substantial real estate loss from dicing streets and the inability of chemical etching to practically etch through entire wafers, requiring a combination of mechanical and chemical processes that are challenging for thin wafer stabilization.
Innovation Solution
A method involving forming trenches around semiconductor device regions, filling them with an adhesive, attaching a carrier, thinning the substrate, and using high density plasma etching with CF4 and oxygen to expose sidewalls and remove the adhesive, thereby enabling efficient separation of small dies with improved mechanical stability and selective etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If mechanical separation is used to separate semiconductor devices, then the separation process is simple and direct, but the space efficiency is poor due to substantial real estate loss from dicing streets
Solution Approach 1:
The patent replaces the conventional mechanical dicing process with a chemical etching process using plasma. Instead of mechanically cutting through the wafer with diamond blades that create wide dicing streets, the invention uses chemically active species in a plasma environment to selectively etch and separate the semiconductor devices. This substitution eliminates the need for wide mechanical cutting paths, thereby reducing real estate loss while maintaining separation effectiveness.
2Loss of substance
If chemical etching is used to separate semiconductor devices, then space efficiency is improved, but the process cannot practically etch through entire wafers and requires thin wafer stabilization
Solution Approach 1:
The patent divides the wafer into discrete device regions separated by trenches. By forming isolation trenches around each device region and filling them with adhesive material, the wafer is segmented into independent units that can be processed separately. This segmentation allows the chemical etching process to work effectively on thinner sections without requiring stabilization of the entire thin wafer, as each device region is independently supported by the adhesive in the trenches.
Solution Approach 2:
The patent introduces adhesive material as an intermediary substance filled in the isolation trenches. This adhesive serves multiple functions: it provides mechanical support to the thinned wafer regions, enables chemical etching by allowing reagent access, and facilitates subsequent device release. The adhesive acts as a mediator that resolves the conflict between achieving thin wafer processing and maintaining structural stability during chemical etching.
3Loss of substance
If thin wafer processing is implemented, then chemical etching becomes feasible, but mechanical stability is compromised
Solution Approach 1:
The patent applies different properties to different regions of the wafer. The device regions are thinned to enable chemical etching access, while the isolation trenches are filled with adhesive material that provides localized mechanical support. This local differentiation allows the wafer to be thin where needed for chemical processing while maintaining strength where structural support is required, resolving the contradiction between thinness and mechanical stability.
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 allows for efficient separation of small semiconductor dies with reduced material loss and precise exposure of sidewalls, overcoming the limitations of conventional mechanical and chemical separation methods by providing enhanced mechanical stability and selective etching without damaging the semiconductor material.
Implementation Method 1
A high density plasma is generated using CF4 and oxygen. The adhesive is removed using the high density plasma thereby exposing the sidewalls and the top surface.
Data Source
AI summary
In accordance with an embodiment of the present invention, a method of fabricating a semiconductor device includes forming a trench from a top surface of a substrate having a device region. The device region is adjacent to the top surface than an opposite bottom surface. The trench surrounds the sidewalls of the device region. The trench is filled with an adhesive. An adhesive layer is formed over the top surface of the substrate. A carrier is attached with the adhesive layer. The substrate is thinned from the bottom surface to expose at least a portion of the adhesive and a back surface of the device region. The adhesive layer is removed and adhesive is etched to expose a sidewall of the device region.