Atomistic investigation of FIB-induced damage in diamond cutting tools under various ion irradiation conditions

At a Glance

Metadata	Details
Publication Date	2017-03-10
Journal	University of Huddersfield Repository (University of Huddersfield)
Authors	Zhen Tong, Xiangqian Jiang, Qingshun Bai, Liam Blunt
Institutions	Harbin Institute of Technology
Analysis	Full AI Review Included

Atomistic Investigation of FIB-Induced Damage in Diamond Cutting Tools

Document Generated for: 6CCVD.com - Single Crystal and Polycrystalline Diamond Solutions Research Analysis Reference: Tong et al. (2017) Atomistic investigation of FIB-induced damage in diamond cutting tools under various ion irradiation conditions.

Executive Summary

This study utilizes advanced Molecular Dynamics (MD) simulations to establish optimal Focused Ion Beam (FIB) parameters for fabricating ultra-precision diamond cutting tools, directly addressing material integrity requirements for nanoscale engineering.

Application Focus: Investigating gallium ion (Ga⁺) implantation damage and residual damage layer formation in diamond used for precision cutting tools.
Methodology: Development and application of a novel Gauss random distribution multi-particle collision MD model incorporating a multi-timestep algorithm.
Efficiency Gain: The optimized multi-timestep algorithm increased simulation efficiency by a factor of 12, reducing computation time from 72 days to 6 days for key simulations.
Damage Mechanism: Confirmed the formation of a U-shape residual damaged layer at the core irradiation area, characterized by the formation of sp²-bonded carbon.
Optimal Processing Parameters: The study identified that a post-FIB polishing process using low beam energy (5 kV) and a large incident angle (45°) significantly minimized damage.
Performance Achievement: Optimal parameters reduced the residual damaged layer thickness to just 6.5 nm, minimizing tool wear acceleration caused by gallium contamination.
Material Necessity: The successful execution of nanoscale fabrication methods like FIB requires high-pquality, low-defect diamond feedstock, a specialty of 6CCVD.

Technical Specifications

The following table summarizes the key simulation parameters and performance outcomes extracted from the research data.

Parameter	Value	Unit	Context
Ion Source	Ga⁺	-	Focused Ion Beam (FIB)
Initial Temperature	297	K	Simulation baseline temperature
Simulation Time Step	0.1	fs	Temporal resolution
Simulated Diamond Geometry	Cylinder	-	Diameter 25 nm, Height 21.4 nm
Beam Size (d_beam)	10	nm	Focused beam diameter
Incident Voltage Range Tested	5, 8, 16	kV	Key processing variable
Incident Angle Range Tested	0, 15, 30, 45	°	Key processing variable
Optimal Voltage / Angle	5 / 45	kV / °	Minimized residual damage
Minimum Residual Damage Thickness	6.5	nm	Achieved at 5 kV, 45°
Maximum Damage Thickness	20.7	nm	Achieved at 16 kV, 0°
sp²-bonded Carbon Count (Optimized)	8172	atoms	Measure of damage/defect creation
MD Computational Efficiency Gain	12	times	Speed increase using multi-timestep algorithm
Deviation Rate of Damage Features	< 4.85	%	Simulation accuracy validation

Key Methodologies

The study relied on sophisticated computational modeling to investigate the atomistic interaction between Ga⁺ ions and the diamond lattice.

MD Model Development: A novel Gauss random distribution multi-particle collision Molecular Dynamics (MD) model was developed to simulate the FIB process.
System Geometry: The diamond target was modeled as a cylinder (25 nm diameter, 21.4 nm height). To simulate incident angles other than 0°, the collision surface was ‘cut’ with angles up to 45°.
Boundary Conditions: The non-collision surfaces included a thermal layer with a thickness of $2a_{1}$ ($a_{1}$ = 3.567 Å) maintained at 297 K to control temperature.
Optimized Algorithm: A multi-timestep algorithm was implemented to drastically improve computing efficiency. The system was artificially re-set to 297 K when the local temperature in the core collision area cooled down to 600 K after an ion impact.
Irradiation Test Parameters: Simulations were systematically run across incident beam voltages (5 kV, 8 kV, 16 kV) and incident angles (0°, 15°, 30°, 45°) to map the resulting residual damage layer thickness and gallium implantation depth.
Key Finding: The optimal approach for minimizing damage involves using the lowest possible beam energy (5 kV) and the highest tested incident angle (45°), effectively recommending a low-energy, oblique-incidence post-polishing step.

6CCVD Solutions & Capabilities

The research demonstrates that controlling subsurface damage is paramount for the longevity and performance of nanoscale diamond tools. The quality and purity of the initial diamond substrate supplied by 6CCVD are foundational to achieving these nanometric tolerances.

Applicable Materials

The fabrication of high-performance cutting tools requires diamond with extremely low defect density and high purity, typically achieved with MPCVD.

Recommended Material: Optical Grade Single Crystal Diamond (SCD). For applications requiring ultimate precision and thermal stability (as is standard for high-speed cutting tools), 6CCVD provides SCD plates up to 500 µm thick with guaranteed high crystalline quality essential for subsequent high-energy processing like FIB.
Alternative: High-Quality Polycrystalline Diamond (PCD). If the application allows for a controlled grain structure, our PCD wafers (up to 125mm in size) offer excellent hardness and customizable dimensions.

Customization Potential for Tool Fabrication

FIB milling is a critical step in shaping the complex geometries of micro/nanoscale tools. 6CCVD supplies the engineering blanks ready for this advanced processing stage, ensuring optimal starting conditions.

Fabrication Requirement	6CCVD Capability	Value Proposition
Material Pre-Shaping	Custom plates and wafers up to 125mm (PCD)	Supply of large, customized blanks ready for subsequent precision FIB milling.
Surface Quality	Polishing capability Ra < 1 nm (SCD)	Starting surfaces are ultra-smooth, minimizing pre-existing defects before FIB processing.
Thickness Control	SCD and PCD thicknesses from 0.1 µm to 500 µm	Providing material optimized for specific tool geometry and structural support requirements.
Tool Integration/Mounting	Custom Metalization Services (Au, Pt, Pd, Ti, W, Cu)	Tool blanks can be delivered with specified metal contacts, critical for bonding to tool holders or integration with on-tool sensors.

Engineering Support

The research highlights the complex interplay between processing parameters (V, angle) and material damage. 6CCVD’s in-house PhD team provides authoritative support to integrate material selection with advanced processing techniques.

Material Selection: Our experts assist engineers in selecting the optimal SCD or PCD grade to minimize the intrinsic defect density before FIB processing begins, ensuring maximum tool integrity.
Process Optimization: We understand the necessity of minimizing implantation (Ga⁺ range) and residual damage layer thickness (6.5 nm target). Our team can advise on how material orientation and substrate preparation affect susceptibility to FIB-induced damage for similar precision engineering projects.

For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.

View Original Abstract

Focused Ion Beam (FIB) has been demonstrated as a promising tool to the fabrication of micro- and nanoscale diamond cutting tools. In-depth understanding of the ion-solid interaction in diamond leading to residual damage under different processing parameters are in high demand for the fabrication of nanoscale diamond tools. Molecular dynamics (MD) simulation method has long been regarded as a powerful and effective tool for analysing atomistic interactions with regard to its capacity of tracking each atom dynamically. Developing on the previous research work on single ion collision process in diamond, a novel Gauss random distribution multi-particle collision MD model was developed in this paper to study FIB-induced damage in diamond under various ion irradiation conditions. A multi-timestep algorithm was developed to control the whole collision process. \nThe results show that the proposed model can effectively track the impulse of each single ion leads to atomic displacements in diamond and finally to a U-shape residual damaged layer at the core irradiation area. The multi-timestep algorithm can increase the computing efficiency by 12 times while still holding high simulation accuracy in terms of the thickness of residual damaged layer and the range of incident gallium distribution. The simulation model was further used to study the ion-induced damage layer in diamond under various beam voltages (5 kV, 8 kV, and 16 kV) and incident angles (0˚, 15˚, 30˚, and 45˚). Less damage range were found under the beam energy of 5 kV with the ion incident angle of 45˚, which indicated that a post ion beam polishing process (low beam energy with large incident angle) would be an effective way in practice to remove/minimise the residual damage layer when shaping the diamond cutting tools.

Tech Support

Original Source

DOI: None