Laser slicing of large-area diamond substrates

More than just a precious gemstone for jewelry, diamond has properties that make it exceptionally attractive for several next-generation, high-performance technologies. Its high thermal conductivity can help move heat away from semiconductor devices, while its wide bandgap is promising for high-power electronics. Moreover, its transparency in the visible light range makes diamond useful for demanding optical applications.

Unfortunately, the extreme hardness, so characteristic of diamond, also makes it hard to turn into the thin, precisely shaped substrates that these technologies need. Over the past few years, laser-based diamond slicing has emerged as a potential alternative to conventional mechanical machining. Simply put, focused lasers can produce microscopic structural modifications directly inside the crystal, leading to internal stresses that promote and guide crack propagation. However, scientists still don’t fully understand how diamonds produced via different methods respond to such laser treatment.

In a recent study, made available online on September 21, 2026, and published in Volume 169 of the journal Diamond and Related Materials on November 1, 2026, a research team led by Professor Hirofumi Hidai from the Graduate School of Engineering, Chiba University, Japan, set out to address these knowledge gaps. Their paper, coauthored by Mr. Mahiro Ikeno from Chiba University, investigates how different lab-grown diamonds respond to ultrashort laser pulses, turning these insights into a practical strategy to slice large diamonds.

The team first compared three single-crystal diamonds, one made by the high-pressure high-temperature (HPHT) method, and two via chemical vapor deposition (CVD), each with a different level of nitrogen impurity. They irradiated these samples with focused laser pulses, with pulse durations varying from 233 fs to 30 ps. They then used optical microscopy, spectroscopy, and image analysis to examine the size, shape, and continuity of the modified regions produced inside each diamond.

Interestingly, the diamond samples responded quite differently to the laser pulses. The two CVD diamonds could be modified using much shorter pulses than the HPHT diamond. Additionally, in the CVD diamonds, the shortest pulses produced tiny, separated marks, whereas pulses of about 10 ps or longer produced more continuous modified regions. Nitrogen content alone did not explain the differences observed between samples, suggesting that differences in microscopic defects associated with the crystals’ individual growth histories may play an important role. Compared with HPHT diamonds, CVD diamonds also tended to exhibit less stable laser-induced modified regions, as well as greater variation in their morphology.

Building on these findings, the researchers then applied 10 ps pulses to an 8 mm × 8 mm CVD diamond, creating modified regions in a carefully controlled grid. Rather than attempting to generate a complete crack network at once, they progressively introduced additional modified regions at the midway points between existing ones. After four such processing steps, the diamond split cleanly along the {100} plane with a light tap from a pair of tweezers. The {100} plane is the easiest one to polish, making it especially important in practical applications.

The area of the 8 mm × 8 mm slice was approximately 710 times larger than that of the 300 µm-square HPHT diamond the researchers produced in their previous study. This larger slicing area represents an important step toward realizing the larger diamond substrates needed for optical components and electronics. “Potential applications of this new slicing method include the production of diamond substrates and components for high-power laser optical windows used in lithography systems, heat spreaders for advanced electronic devices such as AI chips, and next-generation diamond-based power semiconductors,” remarks Prof. Hidai.

Considering that the steps involved in the slicing process are potentially scalable, the researchers envision their new method being adapted for use in various industrial settings. “The proposed technology could be incorporated into future mass-production processes for diamond substrates, helping to reduce manufacturing costs and improve material utilization. In turn, this may accelerate the broader adoption of high-end technologies that take advantage of diamond’s exceptional thermal, optical, and electronic properties,” says Prof. Hidai.

The adoption of diamond as a major component of future technologies could also bring considerable benefits in terms of sustainability. In the future, diamond-based power semiconductor devices could help reduce energy losses in applications such as data centers, power infrastructure, and electric vehicles, paving the way for higher energy efficiency in rapidly expanding areas. 

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Reference:
Title of original paper: Ultrashort-pulse laser-induced internal modification in HPHT and CVD diamond specimens and {100} laser slicing of single-crystal CVD diamond

Journal: Diamond and Related Materials

DOI: 10.1016/j.diamond.2026.114182

Authors: Mahiro Ikeno¹, Kosuke Sakamoto¹, Hirofumi Hidai^1,2, Koji Koyama³, Seong-Woo Kim³, and Souta Matsusaka¹

Affiliations:

¹Department of Mechanical Engineering, Chiba University, Japan

²Molecular Chirality Research Center, Chiba University, Japan

³Orbray Co., Ltd., Japan

About Professor Hirofumi Hidai from Chiba University, Japan
Dr. Hirofumi Hidai obtained his doctoral degree from Tokyo Institute of Technology in 2004. He joined Chiba University in 2010, where he currently holds the title of Full Professor at the Department of Mechanical Engineering. His research interests focus primarily on advanced manufacturing technologies, including precision machining and laser-based processing. He has published over 120 papers on these topics and holds several patents. He is also a member of the Japan Society for Precision Engineering, the Japan Society of Laser Technology, and the Japan Society of Applied Physics, among others.

Funding:
This work was supported by the Osawa Scientific Studies Grants Foundation and JKA and its promotion funds from the KEIRIN RACE.