Dielectric Film Moat Coverage for Passivation and Wafer Singulation
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Solution Overview
Problem
Existing semiconductor device passivation techniques, such as photo-glass passivation, face challenges including defects, damage susceptibility, and excessive wafer area consumption, which lead to unwanted leakage currents and electrical overstress during processing and assembly.
Innovation Solution
The use of a dielectric film, like an oxide-nitride film, is applied to coat moat surfaces for passivation, providing effective coverage and reducing the risk of electrical overstress while consuming less wafer area, allowing for more devices on a semiconductor wafer and enabling easier cutting and processing without damaging the film or substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If photo-glass passivation is used to form passivation in wafer areas including moats, then leakage currents are minimized, but wafer processing difficulties and surface area consumption increase
Solution Approach 1:
The patent changes the material parameter from photo-glass to dielectric film, which fundamentally alters the passivation mechanism. The dielectric film provides effective passivation without the processing difficulties associated with photo-glass, as it can be deposited using standard semiconductor fabrication techniques and does not require subsequent photo-glass specific processing steps
Solution Approach 2:
The dielectric film serves as a simpler, more easily processed passivation layer that can be deposited and removed more readily than photo-glass. While photo-glass provides good passivation, it creates processing bottlenecks; the dielectric film approach trades some passivation complexity for manufacturing ease and flexibility
2Reliability
If photo-glass passivation is used to form passivation in wafer areas including moats, then leakage currents are minimized, but valuable surface area on the wafer is consumed
Solution Approach 1:
By changing from photo-glass to dielectric film material, the patent achieves more efficient space utilization. The dielectric film can be applied in thinner conformal layers that follow the moat sidewalls, providing adequate passivation coverage without the excessive material thickness required by photo-glass processes, thereby conserving valuable wafer surface area
3Reliability
If photo-glass passivation is used, then passivation is provided, but the film or substrate is damaged during cutting and processing
Solution Approach 1:
The dielectric film is designed as a robust, easily replaceable passivation layer that can withstand the mechanical stresses of wafer cutting and processing. Unlike photo-glass which is fragile and prone to cracking, the dielectric film maintains integrity through processing steps, providing durable passivation that does not compromise the substrate or require protective handling
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 dielectric film achieves better passivation than traditional methods, reduces electrical overstress, and allows for closer device spacing, increasing wafer efficiency and yield, while being more resilient to processing damages and area constraints.
Implementation Method 1
a dielectric film covering the sidewall and a first portion of the surface
Implementation Method 2
a metal contact layer covering a second portion of the surface and at least a portion of the dielectric film covering the first portion of the surface, and providing electrical contact to the semiconductor device
Data Source
AI summary
Techniques are described for the use of moats for isolating and singulating semiconductor devices formed on a wafer. Described techniques use dielectric films, such as an oxide-nitride film, to coat moat surfaces and provide passivation. The dielectric films may form a junction with a metal contact layer, to reduce electrical overstress that may otherwise occur in the resulting semiconductor devices. To ensure coverage of the moat surfaces, spray coating of a positive photoresist may be used.