Thanks for bringing this fellow to my attention!
There are a few 15 year olds ranked above him in the juniors but none born after 1993. For example, Dennis Novikov is ranked 91 and was born on 06 Nov 1993.
There are four 15 year olds in the ATP (mens) rankings - please see my website for details. There's a section you can look up youngest players at http://statracket.net/?view=stats/stats.php
But come Monday's new rankings he will be the youngest of the lot!
He got thrashed by John Millman 6-2 6-0 in the second round of the Australia F5 but he was playing the top seed. But still very nice work getting his first ranking point so young.