The formation of islands arrays during Ge deposition on Si(100) at high temperatures is studied using scanning tunneling and electron microscopies. It is found that the island size and shape distributions, which are known to be bimodal at growth temperatures below 700°C, become monomodal at temperatures above 800°C. The obtained data suggest that the processes such as island nucleation and Ostwald ripening become less significant in the surface morphology formation, giving the advantage to selective attachment of deposited Ge atoms to island sidewalls and spatially inhomogeneous Si-Ge intermixing, as the temperature increases. At 900°C, the islands exhibit a tendency to form laterally ordered arrays when the growth conditions approach the dynamic equilibrium between the growth of islands and their decay by means of Si-Ge intermixing. The islands ordering is accompanied by their shape transformation into the cone with shallow sidewalls inclined from (100) by angles of around 10°.