Diffusion of Phosphorus in Poly/Single Crystalline Silicon

Hideaki FUJIWARA, Hideharu NAGASAWA, Atsuhiro NISHIDA, Koji SUZUKI, Kazunobu MAMENO, Kiyoshi YONEDA

Summary :

Diffusion of phosphorus impurities from a polycrystalline silicon films into a silicon substrate was investigated as a function of the mean concentration of phosphorus in a polycrystalline silicon film at the first diffusion stage. We presented that good control of the redistribution of implanted phosphorus impurities was possible by optimizing the normalized dose, which is the value: [the total dose of phosphorus impurities]/[the polycrystalline silicon film thickness], in the case of samples both with and without an arsenic doped layers. In the range where the normalized dose was less than 1.52.510²⁰ cm^-3, deeper junctions were formed in samples with an arsenic doped layer. In the range where the normalized dose was more than 1.52.510²⁰ cm^-3, however, deeper junctions were formed in samples without any arsenic doped layer rather than in samples with an arsenic doped layer. These results mean that formation of the junction in the device structure where a high concentration phosphorus doped polysilicon layer is stacked on to the high concentration arsenic layer embeded at the surface of the substrate can be restricted by optimizing the normalized dose. Moreover, a trade-off relationship between suppressing phosphorus diffusion and maintaining low contact resistance against normalized doses was also observed.

• Publication: IEICE TRANSACTIONS on Electronics Vol.E75-C No.9 pp.995-1000
• Publication Date: 1992/09/25
• Type of Manuscript: Special Section PAPER (Special Issue on Silicon Devices and Materials)

Authors

Hideaki FUJIWARA
Hideharu NAGASAWA
Atsuhiro NISHIDA
Koji SUZUKI
Kazunobu MAMENO
Kiyoshi YONEDA

Keyword

ion implantation,  phosphorus,  diffusion,  polycrystalline silicon