Laser slicing boost for diamond semiconductors
Researchers in Japan are using laser pulses to slice diamond into thin wafers, paving the way for its adoption as a next-generation semiconductor material.
Diamond is a promising material for the semiconductor industry, but slicing it into thin wafers is challenging. In a recent study, a research team from Chiba University developed a novel laser-based technique for slicing diamonds along the optimal crystallographic plane. The findings will help make the material cost-effective for highly efficient power conversion in electric vehicles and for high-speed communication technologies.
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Despite their attractive properties for the semiconductor industry, the applications are limited due to the lack of techniques to slice them into thin wafers efficiently. As a result, wafers must be synthesized one by one, making fabrication costs prohibitive for most industries.
Now, a research team from Japan, led by Professor Hirofumi Hidai from the Graduate School of Engineering at Chiba University, has found a solution to this problem. The laser-based slicing technique is used to cleanly slice a diamond along the optimal crystallographic plane, producing smooth wafers.
Their study is co-authored by master’s student Kosuke Sakamoto from the Graduate School of Science and Engineering at Chiba University and former Ph.D. student Daijiro Tokunaga, currently an Assistant Professor at Tokyo Institute of Technology.
To prevent the propagation of undesirable cracks across the lattice, the researchers developed a processing technique that focuses short laser pulses onto a narrow cone-like volume within the material.
“Concentrated laser illumination transforms diamond into amorphous carbon, whose density is lower than that of diamond. Hence, regions modified by laser pulses undergo a reduction in density and crack formation,” said Prof Hidai.
By shining these laser pulses onto the transparent sample in a square grid pattern, the researchers created a grid of small crack-prone regions inside the material. If the space between the modified regions in the grid and the number of laser pulses used per region are optimal, all modified regions connect to each other through small cracks that preferentially propagate along the {100} plane. Consequently, a smooth wafer with {100} surface can be easily separated from the rest of the block by simply pushing a sharp tungsten needle against the side of the sample
“Diamond slicing enables the production of high-quality wafers at low cost and is indispensable to fabricate diamond semiconductor devices. Therefore, this research brings us closer to realizing diamond semiconductors for various applications in our society, such as improving the power conversion ratio in electric vehicles and trains,” he said.
doi.org/10.1016/j.diamond.2023.110045
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