Wafer Plasma Dicing Without Masks Using Pre-Formed Grooves
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Solution Overview
Problem
Existing plasma dicing methods for semiconductor wafers require expensive and difficult-to-manufacture masks, increasing costs and manufacturing time due to the need for precise alignment and high manufacturing complexity, especially when processing small-sized device chips with numerous streets.
Innovation Solution
A wafer processing method involving a protective member, cutting steps to form grooves in the wafer's undersurface, followed by plasma etching from the undersurface to divide the substrate along the streets without a mask, and optional laser processing to remove the functional layer, facilitating cost reduction and efficient chip division.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If plasma dicing is performed using a precise mask to accurately expose only the region to be removed, then etching precision is improved, but manufacturing cost and device complexity increase dramatically
Solution Approach 1:
The patent extracts and removes the mask component from the plasma dicing system entirely. Instead of using a mask to define etching regions, the method uses pre-formed grooves on the wafer surface that directly guide the plasma etching process, eliminating mask preparation, alignment, and removal steps while maintaining precise etching along the groove locations
Solution Approach 2:
The patent introduces grooves as an intermediary structure between the desired etching pattern and the plasma etching process. These grooves serve as physical guides that direct plasma etching along specific paths without requiring masks, effectively mediating between the wafer structure and the etching process to achieve precise street formation
2Productivity
If the number of streets per wafer is increased to produce more small-sized device chips, then productivity is improved, but processing time is lengthened when processing is performed on one line at a time
Solution Approach 1:
The patent performs preliminary action by pre-forming grooves along all street locations across the entire wafer surface before plasma etching. This preliminary groove formation enables parallel processing of multiple streets simultaneously during plasma etching, rather than processing one line at a time, thereby maintaining short processing time even when the number of streets is dramatically increased
Solution Approach 2:
The patent transitions from one-dimensional sequential line processing to two-dimensional parallel processing by forming grooves and performing plasma etching across the entire wafer surface simultaneously. This dimensional change allows all streets to be processed in parallel rather than sequentially, enabling high productivity with increased street density without proportionally increasing processing time
3Ease of manufacture
If conventional cutting processing is used to divide the wafer, then manufacturing cost is reduced, but transverse rupture strength of the divided chips is lowered
Solution Approach 1:
The patent replaces the mechanical cutting blade system with a plasma etching system that uses plasma chemistry to remove material. This substitution eliminates the mechanical contact and physical stress that cause micro-cracks and reduce transverse rupture strength, while maintaining cost-effectiveness by using plasma processing on standard wafer structures without requiring expensive masks
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 plasma etching without the need for expensive masks, reducing manufacturing costs and time while maintaining high precision and transverse rupture strength of the divided device chips, allowing for efficient production of small-sized chips.
Implementation Method 1
a plasma etching step of extending the cut groove toward the top surface of the wafer and dividing the substrate along the streets by plasma-etching, from an undersurface side, the wafer whose protective member side is held by a chuck table
Implementation Method 2
a laser processing step of removing the functional layer along the cut groove by irradiating the functional layer remaining at a groove bottom of the cut groove dividing the substrate with a laser beam having a wavelength absorbable by the functional layer after performing the plasma etching step
Data Source
AI summary
A wafer processing method is a method of dividing a wafer in which a functional layer is laminated to a top surface of a substrate and a plurality of devices are formed, along streets dividing the plurality of devices. The wafer processing method includes: a protective member disposing step of disposing an adhesive tape on the functional layer side of a top surface of the wafer; a cutting step of forming, along the streets, a cut groove having a depth exceeding a finished thickness of the wafer by making a cutting blade cut into an undersurface of the wafer; and a plasma etching step of extending the cut groove toward the top surface of the wafer and dividing the substrate along the streets by plasma-etching, from an undersurface side, the wafer whose adhesive tape side is held by a chuck table.