Wafer Ring-Stiffener Removal by Image-Guided Laser Cutting
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Solution Overview
Problem
Existing methods for removing a ring-shaped stiffener from the reverse side of a wafer in the outer circumferential excess region are inefficient, leading to poor productivity.
Innovation Solution
A method and apparatus that involves preparing a ring-shaped frame with an opening, affixing a tape to the wafer and frame, capturing the center of the ring-shaped stiffener's inner circle, rotating the frame unit to cut along this circle, and removing the stiffener using a laser beam and ultraviolet radiation, with image capture to ensure precision and avoid device interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a ring-shaped stiffener is left on the reverse side of the wafer to facilitate delivery, then the wafer can be easily handled and transported, but the stiffener must be removed later which causes poor productivity due to difficulty in cutting at certain positions
Solution Approach 1:
The patent applies preliminary action by pre-defining cutting positions on the wafer before the stiffener removal process. The cutting positions are determined based on the device layout, and cutting marks are formed in advance. This allows the stiffener to be removed efficiently later by simply following the pre-determined cutting paths, rather than having to calculate and determine cutting positions during the actual removal operation.
Solution Approach 2:
The patent replaces traditional mechanical cutting methods with laser processing. The laser processing apparatus uses a laser beam to cut along the predetermined cutting positions, eliminating the need for mechanical cutting tools and fixtures that would be required to hold and cut the wafer at specific positions. This substitution dramatically improves productivity by allowing flexible, precise, and rapid cutting without the constraints of mechanical positioning systems.
2Manufacturing precision
If the wafer is cut to remove the ring-shaped stiffener, then the stiffener can be removed from the wafer, but cutting at certain positions is difficult leading to poor productivity
Solution Approach 1:
The patent replaces mechanical cutting systems with laser processing. The laser beam can precisely follow the predetermined cutting paths without the inertia, friction, and positioning limitations of mechanical cutting tools. This allows high-speed cutting while maintaining accuracy, as the laser can be rapidly redirected along the cutting trajectory defined by the cutting marks.
Solution Approach 2:
The patent changes the cutting method from mechanical to optical (laser), fundamentally altering the processing parameters. The laser processing allows for variable cutting speed, power, and focus along the cutting path, enabling precise control of the cutting process while maintaining high productivity. The cutting parameters can be dynamically adjusted based on the local requirements of different cutting positions.
3Device complexity
If traditional methods are used to remove the ring-shaped stiffener, then the process is simple, but productivity is poor due to inability to cut at certain positions efficiently
Solution Approach 1:
The patent replaces complex mechanical positioning and cutting systems with a laser processing system. The laser processing apparatus automatically follows the predetermined cutting positions marked on the wafer, eliminating the need for complex mechanical fixtures, alignment systems, and manual positioning. This simplification of the system actually improves productivity by removing mechanical constraints while maintaining process simplicity through automated laser control.
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 precise and efficient removal of the ring-shaped stiffener from the wafer, improving productivity by ensuring accurate cutting and minimizing damage to the device region.
Implementation Method 1
a laser beam applying unit for applying a laser beam to the wafer along the inner circumferential circle of the ring-shaped stiffener in the outer circumferential excess region of the wafer to form a cut groove in the wafer
Implementation Method 2
a separator for separating the ring-shaped stiffener from the frame unit along the cut groove, the separator including an ultraviolet radiation applying unit for applying an ultraviolet radiation to the tape to reduce an adhesive power of the tape
Data Source
AI summary
A method of processing a wafer includes preparing a ring-shaped frame having an opening for accommodating a wafer therein, preparing a wafer having a protrusive ring-shaped stiffener on a reverse side thereof in an outer circumferential excess region thereof, producing a frame unit by affixing a tape to the frame and the reverse side of the wafer, capturing an image of the ring-shaped stiffener and setting a center of an inner circumferential circle of the ring-shaped stiffener on the basis of the captured image, rotating the frame unit around the center of the inner circumferential circle of the ring-shaped stiffener to cut the wafer along the inner circumferential circle of the ring-shaped stiffener, and removing the ring-shaped stiffener severed from the frame unit.