This paper addresses several aspects of the mu-PD growth technology as applied to submillimeter diameter sapphire tubes for UFD application. The mu-PD method has been successfully adapted for single crystal sapphire tube growth. A compound crucible made possible the growth of single crystal sapphire tube as small as around 0.70-0.72 mm in outer diameter and 0.28-0.29 in inner diameter over 160 mm in length at growth rate of 2-4 mm/min along (001) direction. An Ir crucible with a die composed of an equivalent hole and Ir wire was heated by RF coil in N-2 atmosphere. The mu-PD method has been successfully adapted for single crystal sapphire tube growth. Grown crystal tube showed good XRC value of 30.2 arcsec. (C) 2018 Elsevier B.V. All rights reserved.