Single-Crystal Substrate Separation Using Multi-Focal Laser Cracks
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Solution Overview
Problem
The existing methods for manufacturing substrates from single-crystal ingots using a wire saw result in high material wastage and low productivity due to large cutting allowances and surface irregularities, while increasing laser beam output power to improve throughput leads to increased costs and potential optical system damage.
Innovation Solution
A manufacturing method that forms separation layers with modified parts and cracks inside the ingot by moving the ingot and focal points along specific crystal planes, allowing longer crack formation without increasing laser output power, thereby improving substrate production efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the output power of the laser beam is set higher to improve throughput, then the length of time necessary for formation of separation layers can be made shorter, but the size and cost of the laser oscillator becomes larger and optical components may be damaged
Solution Approach 1:
The laser beam is divided into multiple beams using a beam splitter, and each beam forms a focal point that creates cracks. By segmenting the laser energy into multiple focal points arranged along the crystal plane, the patent achieves efficient crack formation without requiring excessive power from a single beam, thus improving throughput while avoiding optical component damage
Solution Approach 2:
The patent transitions from a single focal point to multiple focal points arranged in a line along the crystal plane. This dimensional change from point to line allows the laser energy to be distributed along the crack path, enabling longer crack formation with moderate power and improving processing efficiency without overloading optical components
2Productivity
If the wire saw method is used to cut substrates from ingot, then multiple substrates can be manufactured simultaneously, but approximately 1/3 of the total amount of ingot is discarded and productivity becomes low
Solution Approach 1:
The patent replaces the mechanical wire saw cutting method with a laser-based separation layer formation method. By using laser beams to create separation layers through modified parts and cracks inside the ingot, the mechanical cutting process is eliminated, reducing material wastage from 1/3 to minimal amounts while maintaining the ability to manufacture multiple substrates
Solution Approach 2:
The patent forms separation layers inside the ingot before the actual substrate extraction process. By pre-creating modified parts and cracks that serve as separation layers, the subsequent substrate removal becomes easier and more efficient, reducing both material wastage and processing time compared to direct mechanical cutting
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 method enhances substrate manufacturing throughput by forming longer cracks along the crystal plane, reducing material wastage and maintaining the integrity of the optical system, thus improving productivity without the need for higher laser power.
Implementation Method 1
irradiating the ingot with a laser beam with such a wavelength as to be transmitted through a single-crystal material from the front surface side
Implementation Method 2
forming separation layers including modified parts and cracks that extend from the modified parts inside the ingot
Data Source
AI summary
In the state in which a laser beam is split in such a manner that multiple focal points that line up along a first direction parallel to a specific crystal plane of a single-crystal material that configures an ingot are formed, the ingot and the multiple focal points are relatively moved along a second direction parallel to this specific crystal plane to form a separation layer. In this case, modified parts are formed with each of the multiple focal points being the center of the modified part. In addition, it becomes easier for cracks to extend from these modified parts along the specific crystal plane. Thus, in this case, the cracks formed inside the ingot can be made longer without setting the output power of the laser beam higher. As a result, it becomes possible to improve the throughput in manufacturing a substrate from the ingot.