Wafer Thinning via Laser Line Beam Interface Formation
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Solution Overview
Problem
Existing wafer thinning methods, such as mechanical and chemical back grinding, cause mechanical or chemical stress leading to cracks and waste, and are inefficient in achieving uniform thickness and recycling of wafers.
Innovation Solution
A method and apparatus using a laser line beam to scan and form an interface at a specific depth in the wafer, allowing for precise cleaving into pattern and dummy wafers, reducing stress and waste while enabling recycling of wafers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If mechanical back grinding is used to thin the wafer, then the wafer thickness is reduced, but mechanical stress causes cracks and breakage
Solution Approach 1:
The patent replaces the mechanical grinding system with a laser-based system. The laser beam is focused at a specific depth within the wafer to form an interface without mechanical contact, thereby eliminating mechanical stress and preventing cracks and breakage while achieving the desired thickness reduction.
Solution Approach 2:
The patent changes the physical state and parameters of the laser beam by focusing it at a specific depth within the wafer. By controlling the focal depth and laser parameters, the interface is formed precisely at the desired location, enabling thickness control without mechanical contact.
2Productivity
If traditional dicing process is used to separate dies, then individual dies are obtained, but the process is complex and time-consuming
Solution Approach 1:
The patent merges the thinning process and the dicing process into a single laser-based operation. The laser beam both thins the wafer to a specific depth and creates the separation interface, eliminating the need for separate mechanical grinding and dicing steps, thereby simplifying the process and improving productivity.
Solution Approach 2:
The laser system performs multiple functions: it thins the wafer, creates the interface at the desired depth, and enables separation of dies. This multi-functional approach replaces multiple specialized tools and processes with a single versatile laser system.
3Manufacturing precision
If wafer back grinding is performed, then uniform thickness is achieved, but material is removed and waste is generated
Solution Approach 1:
The patent replaces mechanical material removal with a laser-based interface formation process. The laser focuses at a specific depth to create a precise interface without removing excessive material, thereby achieving uniform thickness control while minimizing material waste.
Solution Approach 2:
The laser interface is formed at the precise depth required before any separation or further processing occurs. This preliminary formation of the interface at the exact desired thickness eliminates the need for subsequent material removal steps, preventing waste generation.
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 method minimizes mechanical stress, reduces waste water, and allows for precise thinning and recycling of wafers, replacing traditional dicing processes with high productivity and reduced thickness variations.
Implementation Method 1
irradiating a line beam focused at a specific depth of a wafer
Implementation Method 2
scanning the wafer by using the line beam and forming an interface at the specific depth of the wafer
Data Source
AI summary
A method and an apparatus for thinning a wafer are provided. The method for thinning a wafer, according to one embodiment of the present invention, comprises the steps of: irradiating a line beam focused at a specific depth of the wafer; scanning the wafer by using the line beam so as to form an interface at the specific depth of the wafer; and cleaving the wafer on which the interface is formed into a pattern wafer and a dummy wafer.