In:
Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films, American Vacuum Society, Vol. 6, No. 3 ( 1988-05-01), p. 2064-2068
Abstract:
The depth of origin of sputtered atoms is a subject of considerable interest. The surface sensitivity of analytical techniques such as secondary ion mass spectrometry and surface analysis by resonance ionization of sputtered atoms (SARISA), and the sputtering properties of strongly segregating alloy systems, are critically dependent on the sputtering depth of origin. A significant discrepancy exists between the predictions of existing analytical sputtering theories and computer sputtering models; in general, the computer models predict a much shallower depth of origin. The existing experimental evidence suggests that most of the sputtered atoms originate in the topmost atomic layer, but until recently, the results have not been definitive. We have experimentally determined the depth of origin of atoms sputtered from surfaces consisting of Cu films of & lt;2 monolayers on a Ru(0001) substrate. The Cu/Ru target was statically sputtered using 3.6-keV Ar+. The sputtered neutrals were nonresonantly laser ionized and detected using SARISA. The Cu/Ru sputtering yield ratio and the suppression of the Ru sputtering yield were determined for various Cu coverages. The results indicate that the majority of the sputtered atoms originate in the topmost atomic layer. The Cu/Ru system is also modeled using a modified transport of ions in matter (trim) code. It was found that trim c does not correctly treat the first atomic layer, resulting in a serious underestimate of the number of sputtered atoms which originate in this layer. The corrected version adequately describes the results, predicting that for the experimental conditions roughly two-thirds of the sputtered atoms originate in the first atomic layer. These results are significantly greater than the analytical theory estimate of & gt;40%.
Type of Medium:
Online Resource
ISSN:
0734-2101
,
1520-8559
Language:
English
Publisher:
American Vacuum Society
Publication Date:
1988
detail.hit.zdb_id:
1475424-1
detail.hit.zdb_id:
797704-9
