UV Release Tape Pre-cure for Laser Plasma Wafer Dicing
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Solution Overview
Problem
Current wafer dicing methods, such as scribing and sawing, often result in chipping and cracking of semiconductor wafers, leading to reduced die density and increased waste of wafer real estate, while plasma dicing faces challenges like high costs and production issues with metals like copper.
Innovation Solution
A hybrid method involving laser scribing and plasma etching with a UV-curable adhesive film, where the adhesive is pre-cured beyond the wafer edge to prevent redeposition during plasma etching, and the wafer is singulated using a patterned mask to minimize damage and improve die separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If scribing or sawing is used for wafer dicing, then the wafer can be separated into individual dice, but chipping and cracking occur along the severed edges reducing die density
Solution Approach 1:
The patent replaces traditional mechanical dicing methods (scribing with diamond tips, sawing with rotating blades) with a plasma-based process. The plasma etches the wafer through photoresist patterns without mechanical contact, eliminating the chipping and cracking caused by mechanical forces while maintaining effective wafer separation and high die density
Solution Approach 2:
The patent changes the physical state and parameters of the adhesive film through UV curing. By controlling the degree of curing (partially cured vs. fully cured regions), the process enables precise control over wafer release characteristics during plasma dicing, allowing clean separation without damage to the dice edges
2Productivity
If sawing is used with a thick blade, then the wafer can be cut through, but the blade thickness requires substantial spacing between dice increasing waste
Solution Approach 1:
The plasma etching process replaces mechanical sawing, allowing for extremely precise and narrow cut paths. The plasma can etch through the wafer following precise photoresist patterns with minimal kerf width, maximizing the usable area on each wafer and reducing waste from spacing requirements
Solution Approach 2:
The patent utilizes UV light wavelength and exposure parameters to control the precision of the dicing pattern. By adjusting UV exposure parameters and photoresist properties, the process achieves sub-micron precision in defining die boundaries, minimizing kerf width and maximizing wafer real estate utilization
3Reliability
If plasma dicing is implemented, then chipping and cracking are reduced, but cost increases due to lithography requirements
Solution Approach 1:
The patent applies adhesive film to the wafer before the plasma dicing process and selectively cures portions of it. This preliminary action protects the wafer surfaces and defines the separation paths, enabling the plasma process to proceed without requiring expensive lithography steps while maintaining clean, precise cuts
Solution Approach 2:
The adhesive film serves as an intermediary layer between the wafer and the plasma process. It protects the wafer during handling and plasma exposure, and its selective UV curing creates a template that guides the plasma etching without requiring complex lithography equipment, thereby reducing costs while maintaining chip integrity
4Productivity
If plasma processing is used on copper metals, then dicing can be performed, but production issues and throughput limits occur
Solution Approach 1:
The adhesive film is applied and partially cured before plasma processing, creating a protective barrier that prevents plasma-induced production issues with metal layers. This preliminary preparation allows subsequent plasma dicing to proceed smoothly through copper-containing structures without causing the typical production problems and throughput limitations
Solution Approach 2:
The adhesive film acts as an intermediary protective layer during plasma processing of copper-containing wafers. It shields the metal layers from direct plasma exposure that causes production issues, enabling high-throughput processing without the harmful effects previously associated with plasma treatment of metallic interconnects
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 reduces chipping and cracking, allows for closer die placement, and enhances the efficiency of the dicing process by minimizing waste and maintaining chip integrity, while also addressing the cost and throughput limitations of plasma dicing.
Implementation Method 1
pre-curing a peripheral portion of the adhesive film disposed beyond an edge of the semiconductor wafer
Implementation Method 2
patterning the mask with a laser scribing process to provide a patterned mask with gaps
Implementation Method 3
etching the semiconductor wafer through the gaps in the patterned mask to form singulated integrated circuits
Data Source
AI summary
Methods and systems of laser and plasma etch wafer dicing using UV-curable adhesive films. A method includes forming a mask covering ICs formed on the wafer. The semiconductor wafer is coupled to a film frame by a UV-curable adhesive film. A pre-cure of the UV-curable adhesive film cures a peripheral portion of the adhesive extending beyond an edge of the wafer to improve the exposed adhesive material's resistance to plasma etch and reduce hydrocarbon redeposition within the etch chamber. The mask is patterned by laser scribing to provide a patterned mask with gaps. The patterning exposes regions of the semiconductor wafer, below thin film layers from which the ICs are formed. The semiconductor wafer is plasma etched through the gaps in the patterned mask to singulate the ICs. A center portion of the UV-curable adhesive is then cured and the singulated ICs detached from the film.