Variation in emitter diffusion depth by TiSi2 formation on polysilicon emitters of Si bipolar transistors

Citation
M. Kondo et al., Variation in emitter diffusion depth by TiSi2 formation on polysilicon emitters of Si bipolar transistors, IEEE DEVICE, 48(9), 2001, pp. 2108-2117
Citations number
11
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Eletrical & Eletronics Engineeing
Journal title
IEEE TRANSACTIONS ON ELECTRON DEVICES
ISSN journal
0018-9383 → ACNP
Volume
48
Issue
9
Year of publication
2001
Pages
2108 - 2117
Database
ISI
SICI code
0018-9383(200109)48:9<2108:VIEDDB>2.0.ZU;2-6
Abstract
The emitter diffusion depth of wider emitters was found to be shallower tha n that of narrower emitters for transistors with a TiSi2-formed in-situ pho sphorus doped polysilicon (IDP) emitter. This dependence of emitter diffusi on depth on emitter width W-E resulted in a large dependence of h(FE) on W- E. found that the emitter diffusion in emitters with TiSi2 formation was sh allower than that in emitters without TiSi2 formation. We conclude that the dependence of emitter diffusion depth on W-E is due to variation in phosph orus diffusivity caused by the TiSi2 formation. We found by X-ray diffracti on measurements that TiSi2 formation reduced the crystal lattice volume of the EDP emitter layers by 0.2-0.3%. We attribute this reduction to a reduct ion in packing density due to a supersaturation of vacancies caused by the TiSi2 formation. We believe that the vacancy supersaturation decreases the density of interstitials in the emitter regions, which decreases the emitte r diffusion depth, and that the dependence of emitter diffusion depth on W- E is due to variations in the density of vacancies depending on W-E.