Laser-Guided Wafer Splitting for Low-Loss Smooth Separation
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Solution Overview
Problem
Traditional semiconductor wafering processes, such as diamond or slurry-based wire sawing, result in material loss and surface damage due to kerf losses and subsurface damage, which necessitate additional polishing and grinding steps, while stress-based spalling techniques like laser-assisted spalling (LAS) face challenges in controlling wafer thickness and surface roughness due to Wallner lines.
Innovation Solution
A method involving a laser system to create a modification layer in the semiconductor material, allowing for precise control of crack propagation by adjusting laser parameters based on material properties like doping and refractive index, and using position-dependent laser power to minimize surface roughness and material loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If conventional wire sawing processes are used to separate semiconductor wafers, then material can be separated, but material loss occurs due to kerf losses and surface damage is caused
Solution Approach 1:
The patent replaces the mechanical wire sawing process with a laser-based modification process. Laser beams are used to create modifications within the solid body that define a detachment plane, eliminating the need for mechanical cutting and thereby reducing material loss and surface damage.
Solution Approach 2:
The patent applies laser modifications in advance to create a predetermined detachment plane within the solid body before separation occurs. This preliminary action defines the exact separation location and reduces the force needed for subsequent separation, minimizing both material loss and surface damage.
2Loss of substance
If stress-based spalling techniques are used to separate semiconductor layers, then material loss is reduced, but Wallner lines appear on the surface increasing roughness
Solution Approach 1:
The patent replaces stress-based spalling with laser-induced modifications. By using laser beams to create controlled modifications within the material and defining a detachment plane, the process eliminates the uncontrolled crack propagation that causes Wallner lines, thereby reducing surface roughness while maintaining minimal material loss.
3Manufacturing precision
If laser-assisted spalling is used to eliminate Wallner patterns, then surface roughness is reduced, but control over wafer thickness becomes limited
Solution Approach 1:
The patent employs feedback mechanisms where laser parameters are continuously adjusted based on real-time monitoring of the separation process. This allows precise control over the detachment plane depth and wafer thickness while maintaining smooth surfaces, resolving the contradiction between surface quality and thickness control.
Solution Approach 2:
The patent uses dynamic adjustment of laser parameters during the modification process. By varying laser power, pulse duration, and scanning speed in real-time, the system can precisely control the depth and location of the detachment plane, enabling accurate wafer thickness control while eliminating Wallner patterns.
4Ease of manufacture
If diamond or slurry-based wire sawing is used to separate semiconductor materials, then separation is achieved, but subsurface damage occurs requiring additional processing steps
Solution Approach 1:
The patent replaces mechanical wire sawing with laser-based modification. The laser creates controlled modifications within the solid body that define a clean detachment plane without the mechanical contact that causes subsurface damage, thereby eliminating the need for subsequent polishing and grinding steps.
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 material loss and surface roughness, enabling more efficient and accurate separation of semiconductor wafers with improved surface quality, reducing the need for subsequent polishing and grinding steps and minimizing Wallner line patterns.
Implementation Method 1
moving the solid body relative to a laser irradiation device, successively generating a plurality of laser beams by means of the laser irradiation device to generate at least one modification
Implementation Method 2
wherein the modifications define a detachment plane for guiding a crack to separate a solid portion, in particular a solid layer, from the solid
Data Source
Figure 1
Figure 2a~2b
Figure 3
AI summary
The invention relates to a method for detaching at least one solid body layer (14) from a solid body (1), wherein by means of the modifications (2) a crack guiding region (4) is provided for guiding a crack in order to detach a solid body portion (6), in particular a solid body layer, from the solid body (1). The invention preferably comprises at least the steps: moving the solid body (1) relative to a laser application device (8), successively producing laser beams (10) by means of the laser application device (8) in order to produce respectively at least one modification (2), wherein the laser application device (8) is adjusted for defined production of modifications depending on at least one parameter, in particular the transmission of the solid body at defined locations and for a defined solid body depth, wherein inhomogeneities of the solid body (1) in the region of the affected surface and/or in the region of the affected volume of the solid body (1) can be compensated for by the adjustment of the laser application device (8), detaching the solid body layer (14) from the solid body (1).