Laser Crack Guidance for Precise Planar Layer Separation
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Solution Overview
Problem
Conventional wafer production methods, such as cold splitting, face challenges in achieving precise planarity and minimizing material waste due to mechanical stresses and refractive index variations, leading to inefficiencies and increased processing costs.
Innovation Solution
A method involving a laser impingement device that adjusts laser beams based on multiple parameters, including refractive index and processing depth, to guide crack propagation for precise separation of solid layers, using a polymer hybrid material with fillers to enhance crack propagation and minimize material loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If cold splitting is used to separate wafers from ingots, then material efficiency is improved, but surface planarity deteriorates due to mechanical stresses and thermal expansion differences
Solution Approach 1:
The patent replaces mechanical wedge compensation with an optical autofocus system that uses a distance sensor to detect surface deviations and dynamically adjusts the laser focus in real-time, eliminating the need for mechanical compensation components and enabling precise planarization without mechanical contact
Solution Approach 2:
The patent dynamically changes the laser focus position parameter based on real-time surface topography measurements, adjusting the focal point depth to compensate for surface deviations and maintain consistent modification depth despite variations in surface planarity caused by cold splitting
2Manufacturing precision
If mechanical wedge compensation is used to achieve planarity, then static planarization is improved, but adaptability to dynamic surfaces deteriorates
Solution Approach 1:
The patent transforms the static mechanical wedge compensation system into a dynamic autofocus system that continuously measures surface distance and adjusts laser focus in real-time, enabling adaptation to dynamic surface variations during the laser processing of cold-split wafers
Solution Approach 2:
The patent implements a feedback control loop where a distance sensor measures surface topography, the control unit processes this information, and the laser focus is automatically adjusted accordingly, enabling real-time compensation for surface deviations without mechanical contact
3Measurement precision
If classic autofocus is used to track surface profile, then distance tracking is improved, but planarization capability deteriorates due to refractive index amplification
Solution Approach 1:
The patent adjusts the laser focus depth parameter as a function of both the measured surface distance and the local refractive index, compensating for the amplification effect by dynamically changing the focal position to maintain accurate planarization despite refractive index variations in the material
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 enables more efficient and precise separation of solid layers with reduced material waste and improved planarity, increasing overall yield and reducing the need for extensive rework and polishing steps.
Implementation Method 1
successively generating or successively emitting a plurality of laser beams by means of the laser impingement device (8) to produce at least one modification (2) in each case within the solid body (1)
Implementation Method 2
wherein the polymer material undergoes a glass transition as a result of thermal loading of the receiving layer for, in particular mechanically, generating crack propagation stresses in the solid body
Implementation Method 3
the laser impingement device (8) for the defined focusing of the laser beams continuously depending on a plurality of parameters, in particular at least two parameters, is set
Data Source
Figure 1
Figure 2a~2b
Figure 3a~3b
AI summary
The present invention relates to a method for creating modifications in a solid body, wherein by means of the modifications a crack guiding region is provided for guiding a crack in order to detach a solid body portion, in particular a solid body layer, from the solid body. The method according to the invention comprises preferably at least the steps of: moving the solid body relative to a laser application device; successively producing a plurality of laser beams by means of the laser application device in order to create a respective at least one modification, wherein the laser application device is adjusted for defined focusing of the laser beams, continuously depending on a plurality of parameters, in particular at least two parameters.