Detection of buried layers in silicon devices using LIBS during hole drilling with femtosecond laser pulses

• Published in: Applied physics. A, Materials science & processing Materials science & processing, 2013-06, Vol.111 (3), p.791-798
• Main Authors: Banerjee, S. P., Chen, Zhijiang, Utkin, I., Fedosejevs, R.
• Format: Article
• Language: English
• Subjects: Beams (radiation); Biological and medical applications; Characterization and Evaluation of Materials; Condensed Matter Physics; Drilling; Exact sciences and technology; Femtosecond; Fundamental areas of phenomenology (including applications); Gaussian; Industrial applications; Lasers; Machines; Manufacturing; Micromachining; Monitoring; Nanotechnology; Optical and Electronic Materials; Optics; Physics; Physics and Astronomy; Processes; Semiconductors; Surfaces and Interfaces; Thin Films
• ISSN: 0947-8396; 1432-0630
• DOI: 10.1007/s00339-013-7648-9

Femtosecond laser micromachining together with Laser Induced Breakdown Spectroscopy (LIBS) allows us to drill precise hole in materials to internal buried layers as well as characterize the materials while drilling. We report detection of a metal layer buried deep inside silicon by creating an access hole through the semiconductor. We used 800 nm femtosecond laser pulses to carry out the drilling while monitoring the plasma emission with a spectrometer system. Higher drilling rates of 1 μm per shot were achieved using a Gaussian laser beam profile with peak fluences of 42 J/cm 2 . Lower drilling rates of 30 nm per pulse with better accuracy could be achieved using lower intensity flat top beam profiles at fluences of 1.4 J/cm 2 .