Surface hydrogen incorporation and profile broadening caused by sheath expansion in hydrogen plasma immersion ion implantation

Citation
Zn. Fan et al., Surface hydrogen incorporation and profile broadening caused by sheath expansion in hydrogen plasma immersion ion implantation, IEEE PLAS S, 28(2), 2000, pp. 371-375
Citations number
17
Categorie Soggetti
Physics
Journal title
IEEE TRANSACTIONS ON PLASMA SCIENCE
ISSN journal
00933813 → ACNP
Volume
28
Issue
2
Year of publication
2000
Pages
371 - 375
Database
ISI
SICI code
0093-3813(200004)28:2<371:SHIAPB>2.0.ZU;2-6
Abstract
Hydrogen plasma immersion ion implantation (PIII) in conjunction with ion-c ut is an efficient and economical technique to synthesize silicon-on-insula tor (SOI) substrates. Unlike beam-line ion implantation, the PIII hydrogen profile usually exhibits multiple peaks because of different implanted spec ies, such as H+, H-2(+), and H-3(+). In addition, a certain amount of adsor bed hydrogen exists near the surface and the hydrogen in-depth distribution is broader than that of a beam-line implant also as a result of a low-ener gy component. For the ion-cut process, the broadened hydrogen profile and s urface hydrogen can decrease the efficiency of the blistering process, Indu ce uneven exfoliation, and degrade the interfacial quality of the bonded wa fer. Hydrogen can adsorb on the wafer surface during the "off-cycle" of the sample voltage pulse and consequently be driven in by ion mixing or diffus ion. In order to reduce surface hydrogen incorporation, the implantation ti me must be short, and this requires an efficient cooling mechanism on the s ample stage because a high ion current is needed to implant a high dose in a short time (less than 5 min). Another mechanism of profile broadening is that the expanding sheath creates low-energy ions during PIII, Our experime ntal and simulation data disclose that profile broadening is less severe fo r a shorter sample voltage pulsewidth and that good blistering characterist ics can he achieved using a long pulse, in spite of a relatively long impla ntation time of 1 h.