Semiconductor Wafer Dicing with Sacrifice Layer Cavity Protection
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Solution Overview
Problem
The existing dicing methods for semiconductor devices often result in breakage of structures with poor strength, leading to decreased fabrication yield, particularly when water pressure is applied during blade dicing and contaminants can enter hollow portions, degrading the performance of devices like MEMS microphones.
Innovation Solution
A method involving the formation of a vibrating film, an intermediate film with a sacrifice layer, and a fixed film on semiconductor wafers, followed by dicing with protective measures such as laser or blade dicing with a protective film, and etching to create cavities, which prevents breakage and contamination by maintaining the fixed film integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If blade dicing is performed with water supply for removal of cutting fragments, then cleaning effectiveness is improved, but structures with poor strength (such as thin films covering hollow portions) are likely to be damaged by water pressure
Solution Approach 1:
The patent applies preliminary action by forming a protective film on the semiconductor wafer before dicing. This protective film is formed in advance to prevent damage to thin films and hollow portion structures during the subsequent dicing process with water supply, thereby resolving the contradiction between cleaning effectiveness and structure integrity.
Solution Approach 2:
The protective film acts as an intermediary between the water supply during dicing and the fragile structures (thin films covering hollow portions). It mediates the interaction by withstanding water pressure while allowing the dicing process to proceed, thus protecting the underlying structures from damage.
2Productivity
If dicing is performed on semiconductor wafers with hollow portions and thin films, then chip separation is achieved, but the thin films covering hollow portions are easily broken by water pressure
Solution Approach 1:
The protective film is formed preliminarily before dicing to prevent damage to thin films during chip separation. This preliminary protective measure enables successful dicing while maintaining film integrity, resolving the contradiction between productivity and manufacturing precision.
Solution Approach 2:
The patent uses a flexible protective film that can withstand water pressure during dicing while allowing the underlying thin films and hollow portion structures to maintain their integrity. This flexible protective layer enables chip separation without breaking the delicate thin films.
3Object-generated harmful factors
If cleaning liquid is supplied during dicing for removal of cutting fragments, then cutting fragment removal is improved, but pressure from water can damage poor-strength portions of the structure
Solution Approach 1:
The protective film serves as an intermediary that allows cleaning liquid to be supplied during dicing for effective fragment removal, while simultaneously protecting the poor-strength portions of the structure from water pressure damage. It mediates between the beneficial cleaning action and the harmful pressure effect.
Solution Approach 2:
The patent changes the parameter of the wafer structure by adding a protective film with specific mechanical properties that can withstand water pressure. This parameter change enables the use of water supply during dicing without causing damage to underlying structures, thus resolving the contradiction between fragment removal and pressure damage.
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 method enhances the fabrication yield of semiconductor devices by preventing breakage during dicing and reducing contamination within cavities, ensuring the quality and reliability of devices like MEMS microphones by maintaining the integrity of the fixed film and avoiding pressure-induced damage.
Implementation Method 1
removing, by etching each of the chips, the sacrifice layer to provide a cavity between the vibrating film and the fixed film
Implementation Method 2
subjecting the semiconductor wafer to blade dicing to separate the chips
Data Source
AI summary
A method for fabricating a semiconductor device includes: the step (a) of forming a vibrating film on a predetermined region of each of a plurality of chips included in a semiconductor wafer; the step (b) of forming, on the semiconductor wafer, an intermediate film containing a sacrifice layer located on the vibrating film of each of the chips; and the step (c) of forming a fixed film on the intermediate film. This method further includes, after the step (c), the step (d) of subjecting the semiconductor wafer to blade dicing to separate the chips, and the step (e) of removing, by etching, the sacrifice layer to provide a cavity between the vibrating film and the fixed film.