A method for selectively forming semiconductor regions (28) is provided, by exposing a patterned substrate (21) having exposed regions of semiconductor material (26,27) and exposed regions of oxide (24) to a first temperature and a semiconductor source-gas and hydrogen in an atmosphere substantially absent halogens, a blanket semiconductor layer (28,29) forms over the exposed regions of semiconductor material (26,27) and oxide (24). By further exposing the patterned substrate (21) to a second temperature higher than the first temperature in a hydrogen atmosphere, polycrystalline semiconductor material (29) formed over the exposed oxide regions (24) is selectively removed leaving that portion of the blanket semiconductor layer (28) over the exposed regions of semiconductor material (26,27). The method is suitable for forming isolated regions of semiconductor material for fabricating semiconductor devices and is not load dependent.