Laser-Induced Separation Layer for Low-Loss Wafer Cleaving
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Solution Overview
Problem
Current semiconductor wafer fabrication methods result in significant material loss and surface damage, leading to increased costs and reduced material availability due to inefficient cleaving processes.
Innovation Solution
A cleaving system that uses a shaper, positioner, internal preparation system, external preparation system, and cleaver to create a separation layer within the workpiece, allowing for precise cleaving with reduced force and minimizing material loss, featuring a laser-based internal preparation system to generate a structurally dissimilar separation layer and a tensile force to propagate cracks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If mechanical wire sawing is used to cut semiconductor ingots into wafers, then the wafer production process is established and controllable, but significant material loss occurs due to kerf loss and surface damage requiring removal
Solution Approach 1:
The patent replaces the mechanical wire sawing system with a laser-based system. The laser beam melts and vaporizes material along the desired cut path without mechanical contact, eliminating kerf loss and surface damage associated with mechanical cutting. This substitution directly addresses both the material loss and surface quality issues by using optical energy instead of mechanical force.
Solution Approach 2:
The laser cutting process utilizes phase transitions of the semiconductor material. The concentrated laser energy heats the material to melting and vaporization temperatures, causing phase changes from solid to liquid and gas. This thermal phase transition enables precise material removal with minimal mechanical stress and no surface damage requiring post-processing.
2Manufacturing precision
If polishing and mechanical grinding are used to finish wafer surfaces, then high-grade wafer surfaces are achieved, but additional material is removed increasing overall material loss
Solution Approach 1:
The patent replaces mechanical polishing and grinding processes with laser-based surface treatment. The laser can selectively remove damaged material and smooth surfaces through controlled melting and vaporization without the mechanical contact that causes additional material loss. This eliminates the need for post-processing steps while maintaining surface quality.
Solution Approach 2:
The laser cutting process performs the surface finishing action during the cutting process itself. By controlling the laser parameters, the cut surface is created with minimal damage and smooth finish directly during material separation, eliminating the need for subsequent polishing or grinding steps that would remove additional material.
3Loss of substance
If traditional cleaving methods are used to separate wafers from ingots, then material loss is reduced, but the process is inefficient and challenging to implement
Solution Approach 1:
The patent replaces traditional mechanical cleaving methods with laser-based separation. The laser beam precisely melts and vaporizes material along the cleavage plane, creating clean separations without the inefficiencies of mechanical methods. This maintains the material loss advantage of cleaving while dramatically improving production efficiency through automated, contactless processing.
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 achieves high-quality wafer surfaces with reduced material loss and potentially eliminates the need for post-processing steps, improving efficiency and cost-effectiveness in semiconductor wafer production.
Implementation Method 1
The internal preparation system focuses a laser beam internal to the workpiece at a focal point, creating a localized region in the workpiece ('footprint') where the mechanical properties have changed
Implementation Method 2
The cleaver then cleaves the workpiece by propagating the crack on the external surface along the separation layer. More particularly, the cleaving system applies a tensile force on opposing ends of the workpiece which propagates the crack along the dissimilar material of the separation layer
Data Source
AI summary
A cleaving system employs a shaper, a positioner, an internal preparation system, an external preparation system, a cleaver, and a cropper to cleave a workpiece into cleaved pieces. The shaper shapes a workpiece into a defined geometric shape. The positioner then positions the workpiece such that the internal preparation system can generate a separation layer at the cleaving plane. The internal preparation system focuses a laser beam internal to the workpiece at a focal point and scans the focal point across the cleaving plane to create the separation layer. The external preparation system scores the external surface of the workpiece at a location coincident with the separation layer. The cleaver cleaves the workpiece by propagating the crack on the external surface along the separation layer. The cropper shapes the cleaved piece into a geometric shape as needed.