Japanese researchers have developed a novel laser slicing technology for diamond semiconductors

Silicon-based materials are currently the undisputed leader in the field of semiconductors. Even so, scientists around the world are actively working to find quality alternatives for next-generation electronics and high-power systems. Interestingly, diamonds are one of the most promising materials for applications such as fast telecommunications and power conversion in electric vehicles and power plants.

Despite the properties of diamond that are attractive to the semiconductor industry, the application of diamond is limited by the lack of technology to effectively cut diamond into thin sheets. As a result, adamantine wafers must be synthesized one by one, making manufacturing costs too high for most industries.

Now, a Japanese research team led by Professor Hirofumi Hidai of the Graduate School of Engineering at Chiba University has found a way to solve this problem. In a recent study published in Diamonds and Related Materials, they report a novel laser-based slicing technique that can be used to slice diamonds cleanly along the optimal crystal face to produce smooth wafers.

Their study was co-authored by Kosuke Sakamoto, a master's student at Chiba University's Graduate School of Science and Engineering, and former doctoral students. Student Daijiro Tokunaga is currently an assistant professor at Tokyo Institute of Technology.

The properties of most crystals, including diamonds, vary along different crystal faces (imaginary surfaces containing the atoms that make up the crystal). For example, a diamond can be sliced easily along the surface of {111}. However, slicing {100} is challenging because it also creates cracks along the cleavage plane {111}, which increases the notch loss.

To prevent the propagation of these undesirable cracks, the researchers developed a diamond processing technique that focuses short laser pulses onto a narrow, conical volume within the material. "Concentrated laser irradiation converts diamond into amorphous carbon, which has a lower density than diamond. As a result, the density of the area modified by the laser pulse decreases and cracks can form, "explains Professor Hidai.

By shining these laser pulses onto a transparent diamond sample in a square grid pattern, the researchers created a grid inside the material made up of small areas prone to cracks. If the space between modified regions in the grid and the number of laser pulses used in each region is optimal, all modified regions are connected to each other by small cracks preferentially propagating along the {100} plane.

As a result, a smooth wafer with a {100} surface can be easily separated from the rest of the block by simply pushing a sharp tungsten needle to the side of the sample.

Overall, the proposed technique is a key step towards making diamond a suitable semiconductor material for future technologies. In this regard, Professor Hidai said: "Diamond slicing enables the production of high-quality wafers at a low cost and is essential for the manufacture of diamond semiconductor devices. Therefore, this research brings us closer to realizing the various applications of diamond semiconductors in society, such as improving the power conversion rate of electric cars and trains."

Source: Laser Network