In:
MRS Proceedings, Springer Science and Business Media LLC, Vol. 470 ( 1997)
Abstract:
2. 0 keV 11 B + , 2.2 keV 49 BF 2 + ion implanted and 1.0 kV Plasma Doped (PLAD) wafers of a dose of 1E15/cm 2 were annealed at various times and temperatures in a variety of ambiente: 600 to 50,000 ppm O 2 in N 2 ; 5% NH 3 in N 2 ; N 2 O; N 2 or Ar, in order to investigate the effects of the annealing ambient on the formation of ultra-shallow junctions. RGA data was collected during some (if the anneals to assist in identifying the complex surface chemistry responsible for boron out-diffusion. Subsequent to the anneals, ellipsometric, XPS, four-point probe sheet resistance and SJJVIS measurements were performed to further elucidate the effects of the different ambients on the r etained boron dose, the sheet resistance value, the RTP grown oxide layer and the junction depth. In the cases where oxygen was present, e.g. N 2 O and O 2 in N 2 , an oxidation enhanced diffusion of the boron was observed. This was most dramatic for the N 2 O anneals, which at 1050°C 10s diffused the boron an additional 283 to 427 Å, depending on the particular doping condition and species. For the case of BF 2 implants and PLAD, anneals in 5% NH 3 in N 2 reduced the junction depth by a nitridation reduced diffusion mechanism. RGA data indicated that the out-diffusion mechanisms for B and BF 2 implanted wafers are different, with the BF 2 exhibiting dopant loss mechanisms during the 950°C anneals, producing F containing compounds. B implants did not show doping loss mechanisms, ais observed by the RGA, until the 1050°C anneals and these signals did not contain F containing compounds. Equivalent effective energy boron implants of 8.9 keV BF 2 vs. 2.0 keV B, however, indicated that the overall effect of the F in the BF 2 implants is very beneficial in the creation of ultra-shallow junctions (compared to B implants): reducing the junction depth by 428 Å, and increasing the electrical activation (determined by SRP) by 11.7%, even though the retained dose (resulting from an increased out-diffusion of B), was decreased by 5.4%.
Type of Medium:
Online Resource
ISSN:
0272-9172
,
1946-4274
DOI:
10.1557/PROC-470-299
Language:
English
Publisher:
Springer Science and Business Media LLC
Publication Date:
1997
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