Laser Cutting Out Process for Semiconductor Crystal Material Applying Laser Slicing Method
At a Glance
Section titled “At a Glance”| Metadata | Details |
|---|---|
| Publication Date | 2017-01-01 |
| Journal | Journal of the Japan Society for Precision Engineering |
| Authors | Yohei Yamada, Yohei Kaneko, Riku Aoki, Junichi Ikeno, Hideki Suzuki |
| Citations | 2 |
| Analysis | Full AI Review Included |
Technical Analysis and Documentation: Laser Slicing for High-Quality Crystal Cutting
Section titled “Technical Analysis and Documentation: Laser Slicing for High-Quality Crystal Cutting”Executive Summary
Section titled “Executive Summary”This technical analysis evaluates a novel high-precision laser cutting process based on internally induced micro-crack chains, proposed for hard-brittle materials including Si, SiC, and Diamond. The method addresses key challenges inherent to conventional mechanical processing (high kerf loss, crystal anisotropy, and chipping).
- Core Value Proposition: Achieves extremely high-quality cuts in hard crystals by chaining internal micro-cracks generated by a focused nanosecond laser.
- Precision and Quality: Demonstrated ultra-low kerf loss of 0.8 µm and achieved a 56% reduction in surface roughness compared to traditional methods.
- Anisotropy Mitigation: Successful control of the micro-crack length to less than 7 µm eliminates dependence on crystal orientation, enabling isotropic, high-quality cutting.
- Deep Penetration: Utilizes a correction collar to compensate for spherical aberration, successfully maintaining focus and creating cracks uniformly throughout a 725 µm thick wafer.
- 3D Capability: The method allows for complex, three-dimensional shaping, demonstrated by successful R-chamfering of the wafer edge, crucial for handling and device reliability.
- 6CCVD Relevance: These findings are directly applicable to the precision processing of 6CCVD’s Single Crystal Diamond (SCD) and Polycrystalline Diamond (PCD) wafers, which are challenging to machine using standard techniques.
Technical Specifications
Section titled “Technical Specifications”The following key data points were extracted from the fundamental and optimized laser cutting experiments:
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Target Material (Tested) | Si (100) | 725 µm | Wafer thickness used in optimization |
| Laser Wavelength (λ) | 1064 | nm | Near-IR (27% transmission through 725 µm Si) |
| Pulse Width | 190 | ns | Used in all tests (Nanosecond regime) |
| Frequency (Pulse Repetition) | 500 | kHz | Used for optimization |
| Critical Micro-Crack Length (Lc) | < 7 | µm | Threshold required to minimize crystal orientation effects |
| Optimized Kerf Loss (Carf Loss) | 0.8 | µm | Achieved using the developed method |
| Surface Roughness Reduction | 56 | % | Reduction in Rz roughness compared to previous method |
| Max Roughness (Rz) | 2.876 | µmRz | Achieved on the {100} face post-slicing |
| Crack Pitch (Optimized) | 2.0 | µm | Spacing between adjacent micro-cracks |
| Line Pitch | 3.0 | µm | Spacing between adjacent laser scan lines |
| Maximum Pulse Energy (Tested) | 9.3 | µJ | Used for deep focus crack formation |
| Focus Compensation Mechanism | Correction Collar (CC 0.0 to 1.0) | mm | Used to control focus depth and counter spherical aberration |
Key Methodologies
Section titled “Key Methodologies”The optimized laser slicing process leverages spherical aberration control and precise energy ramping to achieve uniform crack formation in depth:
- Wavelength Selection: A laser wavelength (1064 nm) with sufficient transmission through the material thickness (e.g., 725 µm Si) is chosen to allow internal focusing.
- Focus Calibration: The Correction Collar (CC) is fixed (e.g., CC 1.0 mm) to compensate for spherical aberration, ensuring the laser is accurately focused at the target depth (the back surface of the wafer).
- Process Direction: Cutting proceeds from the material’s bottom surface (back side) toward the top surface (front side). This direction is crucial because starting on the surface at high energy causes immediate melting and ablation.
- Energy Ramping: Pulse energy is progressively and gradually increased as the laser focus moves closer to the front surface.
- This ramping compensates for the natural decrease in laser energy density caused by aberrations and maintains a uniform crack length (Lc < 7 µm) throughout the depth.
- Crack Chaining: Laser pulses are scanned at high frequency, generating micro-cracks (e.g., 2.0 µm pitch) that are precisely linked to form a continuous, high-quality cutting plane (kerf).
- 3D Profiling: By altering the laser path and energy profile, complex geometries (such as R 0.3 mm chamfers) are achieved simultaneously with the slicing process.
6CCVD Solutions & Capabilities
Section titled “6CCVD Solutions & Capabilities”The demonstrated laser slicing technique offers a path to overcome the manufacturing constraints of extremely hard materials, making it highly relevant for applications utilizing 6CCVD’s superior diamond substrates. 6CCVD provides the specialized material quality and post-processing capabilities necessary to successfully implement and scale this technology for industrial diamond applications (e.g., high-power electronics, quantum computing, or precision micro-optics).
| Application Requirement (Based on Research) | 6CCVD Recommended Material | 6CCVD Capability Match & Customization Potential |
|---|---|---|
| High-Precision Cutting of Extremely Hard Crystals | Optical Grade SCD Wafers | SCD offers the highest purity and thermal conductivity, essential for micro-electronic and optical components that rely on sub-micron processing fidelity. |
| Large-Area Cutting/Slicing | High-Purity PCD Plates | We supply Polycrystalline Diamond (PCD) substrates up to 125mm in diameter, enabling scaling of this high-throughput laser cutting method for larger wafer sizes. |
| Deep Penetration in Diamond | Custom Thickness CVD Diamond | We provide both SCD and PCD layers up to 500 µm (and substrates up to 10mm), requiring robust laser setups and expertise in controlling spherical aberration, which our in-house team can support. |
| Need for Ultra-Low Surface Roughness Post-Processing | Ultra-Precision Polishing | Our capability to achieve Ra < 1nm (SCD) and Ra < 5nm (Inch-size PCD) provides the ideal starting surface required for precision laser interaction and minimizes subsequent chipping risk. |
| Integrated Device Manufacturing (e.g., Contacts) | Custom Metalization Services | We offer internal metal deposition capabilities, including standard materials (Au, Pt, Pd, Ti, W, Cu), allowing customers to integrate slicing with functional electrode or thermal layers. |
| Tolerance for Complex 3D Structures/Chamfers | Advanced Laser Structuring | 6CCVD provides custom laser cutting services to shape wafers to unique specifications, replicating or extending the demonstrated 3D cutting and chamfering capabilities. |
Engineering Support
Section titled “Engineering Support”6CCVD’s specialized material science and engineering team, staffed by PhD experts, is prepared to assist researchers in selecting the optimal MPCVD diamond specifications (crystal orientation, nitrogen content, thickness, and doping level) required to successfully adapt this near-IR laser slicing process to diamond. Our global shipping services (DDU default, DDP available) ensure timely delivery of custom substrates worldwide.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
We propose a new high precision, high quality laser cutting process for semiconductor substrates such as Si, SiC and diamond. According to this method, micro cracks are introduced inside the material by appropriate focusing of the laser beam. A scanning laser beam, then, connects the cracks so as to realize three dimensional cutting. In this paper, we focus on the effects of laser energy, laser pitch and spherical aberration on the shape of the micro cracks. High quality laser cutting is achieved by forming minute and uniform cracks regardless of the crystal orientation and heating produced. In order to ascertain the three dimensional cutting process, cutting out with round chamfering is realized.