2024-03-29T13:27:02Z
https://nagoya.repo.nii.ac.jp/oai
oai:nagoya.repo.nii.ac.jp:02002103
2023-01-16T05:13:41Z
673:674:675
Gallium nitride wafer slicing by a sub-nanosecond laser: effect of pulse energy and laser shot spacing
Sena, Hadi
Tanaka, Atsushi
Wani,Yotaro
Aratani, Tomomi
Yui, Toshiki
Kawaguchi, Daisuke
Sugiura, Ryuji
Honda, Yoshio
Igasaki, Yasunori
Amano, Hiroshi
Gallium nitride (GaN)
Laser slicing
Sub-nanosecond laser
Liquid crystal on silicon (LCOS)
Gallium nitride (GaN)-based devices surpass the traditional silicon-based power devices in terms of higher breakdown voltage, faster-switching speed, higher thermal conductivity, and lower on-resistance. However, heteroepitaxial GaN growths like GaN on sapphire are not suitable for power devices due to the threading dislocation densities as high as 108/cm2. Recently, homoepitaxial GaN growth has become possible thanks to the native GaN substrates with dislocation densities in the order of 104/cm2 but the extremely high cost of the GaN substrates makes the homoepitaxy method unacceptable for industrial applications, and the slicing of wafers for reusing them is an effective solution for cost reduction. In this study, we will investigate a route for slicing the GaN single crystal substrate by controlling the laser pulse energy and changing the distance between each laser shot. The 2D and 3D crack propagations are observed by a multiphoton confocal microscope, and the cross section of samples is observed by a scanning electron microscope (SEM). The results showed that two types of radial and lateral cracking occurred depending on the pulse energy and shot pitch, and controlling them was of importance for attaining a smooth GaN substrate slicing. Cross-sectional SEM images showed that at suitable pulse energy and distance, crack propagation could be controlled with respect to the irradiation plane.
journal article
Springer
2021-08-10
application/pdf
Applied Physics A
9
127
648
0947-8396
https://nagoya.repo.nii.ac.jp/record/2002103/files/Applied-physics-A-Sena.pdf
eng
https://doi.org/10.1007/s00339-021-04808-y
This version of the article has been accepted for publication, after peer review (when applicable) and is subject to Springer Nature’s AM terms of use, but is not the Version of Record and does not reflect post-acceptance improvements, or any corrections. The Version of Record is available online at: http://dx.doi.org/10.1007/s00339-021-04808-y