Phosphorus (P) incorporation process during Si epitaxial growth by SiH4 reaction in ultraclean low-pressure chemical vapor deposition (CVD) and the electrical characteristics of the heavily P-doped epitaxial Si film on Si(1 0 0) have been investigated. Si layer growth on the P layer formed on Si(1 0 0) at 500 degreesC at SiH4 partial pressure of 6 Pa is observed when the surface P amount becomes below 7 x 10(14) cm(-2). It is also found that about 1.1 x 10(14) cm(-2) P atoms segregate onto the Si surface and the other desorbs. On the other hand, by lowering the Si growth temperature to 450 degreesC and increase in the SiH4 partial pressure to 220 Pa, P incorporation occurs and about 1.5 x 10(14) cm(-2) P atoms are buried at the initial position without segregation. By using the multiple atomic-layer doping technique, very low-resistive heavily P-doped epitaxial Si film on Si(1 0 0) can be formed with effective suppression of the electrically inactive P formation. (C) 2003 Elsevier B.V. All rights reserved.