Formation of internal modified line with high aspect ratio in sapphire by sub-nanosecond pulsed fiber laser

Yasuhiro Okamoto, Tomohiro Takekuni, Akira Okada

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)


The internal modification technique for a sapphire substrate using a sub-nanosecond pulsed fiber laser of 180 ps was experimentally investigated with a normal achromatic focusing lens of 20 mm focal length, and the possibility of a singulation method with this internal modification technique was discussed. The laser beam of 1060 nm was focused in sapphire substrate of 0.4 mm thickness by passing through GaN epitaxial layer grown on the top surface of the sapphire substrate, and the internal modification zone was generated from the stain-finished surface as the bottom surface of sapphire substrate. The laser beam was absorbed from the stain-finished bottom surface, and the absorption point moved in the axis of laser irradiation without moving the focusing optics. The narrow internal modified line less than 5 μm in width with a high aspect ratio of more than 30 was successfully obtained only by one laser scanning irradiation from the epitaxial layer side. A sapphire wafer could be broken from the internal modified line with less damage of the epitaxial layer by a stress sufficiently smaller than the tensile strength of sapphire. The breaking strength and its dispersion became smaller with increasing number of laser scans.

Original languageEnglish
Pages (from-to)52-58
Number of pages7
JournalJournal of Laser Micro Nanoengineering
Issue number1
Publication statusPublished - Mar 2014


  • Breaking strength
  • High aspect ratio
  • Internal modification
  • Sapphire
  • Sub-nanosecond pulsed laser
  • Ultrashort pulsed laser

ASJC Scopus subject areas

  • Instrumentation
  • Industrial and Manufacturing Engineering
  • Electrical and Electronic Engineering


Dive into the research topics of 'Formation of internal modified line with high aspect ratio in sapphire by sub-nanosecond pulsed fiber laser'. Together they form a unique fingerprint.

Cite this