Laser Wafer Thinning With Internal Modification Layer Separation
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Solution Overview
Problem
Conventional wafer thinning processes are inefficient, leading to high running costs due to grinding stone abrasion and waste liquid disposal, and can damage wafers with sharp edge shapes during grinding, requiring edge trimming and increasing maintenance needs.
Innovation Solution
A substrate processing system that forms internal and edge modification layers using laser technology within a combined wafer, allowing for efficient edge trimming and rear surface thinning without grinding water, reducing maintenance and waste disposal, and preventing wafer damage by breaking the edge portion into smaller pieces for easy removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional grinding method is used for wafer thinning, then wafer thickness can be reduced, but grinding stone abrasion increases and maintenance frequency increases
Solution Approach 1:
The patent replaces the conventional mechanical grinding system with a laser-based modification system. The laser modifies the wafer structure internally without requiring contact with a grinding stone, thereby eliminating grinding stone abrasion and the associated maintenance requirements while achieving precise wafer thinning.
Solution Approach 2:
The patent introduces an internal modification layer as an intermediary structure formed by laser irradiation. This modification layer serves as a pre-defined separation plane that enables subsequent easy removal of the modified portion, achieving precise thickness control without mechanical grinding contact.
2Manufacturing precision
If conventional grinding method is used for wafer thinning, then wafer thickness can be reduced, but waste liquid disposal costs increase
Solution Approach 1:
The patent replaces the conventional mechanical grinding system that generates waste liquid with a laser-based modification system. The laser processing is a dry process that modifies the wafer internally without generating grinding slurry, thereby eliminating waste liquid disposal requirements and associated costs.
3Manufacturing precision
If conventional grinding method is used for wafer thinning, then wafer thickness can be reduced, but wafer damage risk increases due to sharp edge shapes
Solution Approach 1:
The patent performs preliminary laser modification of the wafer structure before any removal process. The internal modification layer is formed in advance at the desired thickness position, creating a controlled separation plane that prevents uncontrolled cracking and chip formation during subsequent removal, thereby eliminating wafer damage risks associated with conventional grinding.
Solution Approach 2:
The internal modification layer acts as an intermediary that enables controlled separation. This pre-formed layer provides a defined plane for subsequent removal processes, preventing the formation of sharp edges and uncontrolled fractures that occur with conventional mechanical grinding.
4Reliability
If edge trimming is performed to prevent wafer damage, then wafer reliability improves, but processing time increases
Solution Approach 1:
The patent merges the edge trimming process with the internal modification process into a single laser treatment step. The laser simultaneously creates the internal modification layer and modifies the edge structure, eliminating the need for separate edge trimming operations and reducing total processing time while maintaining wafer reliability.
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 system reduces maintenance frequency, eliminates the need for grinding water, suppresses contamination, and improves yield by enabling precise and efficient thinning of wafers with reduced equipment costs and environmental impact.
Implementation Method 1
a first modifying apparatus configured to form, in a combined substrate in which a front surface of a first substrate and a front surface of a second substrate are bonded to each other, an internal modification layer elongated within the first substrate in a plane direction from a center of the first substrate toward at least an edge portion of the first substrate as a removing target
Implementation Method 2
a second modifying apparatus configured to form, within the first substrate, an edge modification layer elongated in a thickness direction of the first substrate along a boundary between the edge portion and a central portion of the first substrate
Data Source
AI summary
A substrate processing system configured to process a substrate includes a first modifying apparatus configured to form, in a combined substrate in which a front surface of a first substrate and a front surface of a second substrate are bonded to each other, an internal modification layer elongated within the first substrate in a plane direction from a center of the first substrate toward at least an edge portion of the first substrate as a removing target; a second modifying apparatus configured to form, within the first substrate, an edge modification layer elongated in a thickness direction of the first substrate along a boundary between the edge portion and a central portion of the first substrate; and a separating apparatus configured to separate a portion of the first substrate at a rear surface side, starting from the internal modification layer.