ADVANCED SCIENTIFIC SEMICONDUCTOR PROCESSING BASED ON HIGH-PRECISION CONTROLLED LOW-ENERGY ION-BOMBARDMENT

Very low-temperature formation of high-quality thin films having ideal interface characteristics has been demonstrated by a high-precision c ontrolled low-energy ion bombardment process. In this process, films a re grown under concurrent bombardment of the growing film surface by l ow-energy ions, thus activating the surface in situ to allow low-tempe rature crystal growth. The process has been realized by two types of p lasma processing equipment: the r.f.-d.c. coupled mode plasma processi ng system and the dual frequency plasma processing system. In these sy stems, the most important process parameters, such as ion bombardment energy, ion flux density and film growth rate, are all independently a nd precisely controlled. The low-energy ion bombardment process has be en successfully applied to the growth of in situ doped device-grade ep itaxial silicon films at a temperature as low as 250-degrees-C. Format ion of giant grain copper thin films has been also shown by the proces s. The giant grain copper thin films exhibit excellent properties as a ULSI interconnect material characterized by low thin film resistivity equivalent to the bulk value and large electromigration resistance. T he basic features of the dual frequency system and its application to new process technologies are also discussed.