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

3-Dimensional analysis of layer structured samples with high depth resolution using picosecond laser-induced breakdown spectroscopy

“…The ablation rate determines the depth resolution of our method, which indicated a best resolution of 24 nm for Mo element (laser fluence: 2.3 J/cm 2 ). The depth resolution of the applied ps-LIBS setup is comparable to some typical results of fs-LIBS, such as 40 nm for Si [26] with a fluence of 1.4 J/cm 2 and 55nm for Cr [16] with a fluence of 1.8 J/cm 2 , which proves its excellent depth resolution ability. Furthermore, the same laser is applied to measure Hydrogen (gas retention, low concentration) in the divertor as well, which is a challenge for fs laser.…”

Femtosecond laser-induced breakdown spectroscopy

“…On the other hand, a at-top beam prole is capable of producing straight-wall craters with a at bottom. 91 For example, Banerjee et al 92 recently demonstrated that the ablation rates for Gaussian and at-top beams differed by 30fold (1 mm per pulse vs. 30 nm per pulse, respectively) similar to the ratio of the laser uences of the beams, 42 J cm À2 vs. 1.4 J cm À2 . Like an 'awl', a Gaussian beam can quickly (<30 shots) drill an upper thick layer of silicon (32 mm) to reach to buried layers of Cu and Cr (about several mm).…”

“…As an example, Banerjee et al 92 demonstrated that a Gaussian beam produced craters with a diameter of $7-9 mm, while craters made by a at-top beam had a size of $90 mm. Because the vast majority of available femtosecond lasers provide a Gaussian distribution across a beam, several studies reporting such a beam prole for mapping can be mentioned; these studies include mapping of sunower cells, 108 leaves, 109,110 lms on silicon 111,112 and aluminium alloys.…”

Atomic spectrometry updates: Review of advances in atomic spectrometry and related techniques

“…The fs-LIBS technique was employed by Banerjee et al 112 for the detection of submicron buried layers inside a semiconductor material (e.g., Si) by making use of the precise hole drilling capabilities of fs-LA. A correlation between depth resolution and processing speed was observed when carrying out these analyses.…”