Thermal stabilisation of titanium-silicide film in IC - by formation of oxide-film on top by thermal oxidn. preventing redistribution during heat treatment

摘要

The Ti-silicide film is formed as follows: a Ti-layer (12) of the required thickness is deposited on the relevant surfaces, pref. on Si-surfaces. The film is heat treated in an ambient which inhibits oxidn. to form a Ti-silicide (TiSi) film, pref. -in an ambient of N2 or Ar. The unreacted Ti is then pref. removed. At a temp. between 600 and 1000 deg.C for a given time, pref. 30 secs to 10 mins. for a fast heating process or several mins. to several hrs. for a slower process, in an ambient contg. oxygen to form an oxide on the surface of the Ti-silicide. An insulation film (8), pref. of P-doped or P- and B-doped silicate glass, is pref. formed on the Ti-silicide film by Chemical Vapour Depsn. (CVD) pref. before the oxidn. of the TiSi, and followed by a heat treatment to oxidise the TiSi. Also claimed is the use of the above process in the construction of a Si-gate MOS-transistor, for the gate-electrode and/or drain and source electrodes. Also claimed is the formation of contacts to the source/drain regions by forming openings in the insulator film down to the TiSi-film, implanting impurities into the Si-substrate through the metal film and depositing a metallisation layer contacting the regions. Also claimed is the formation of a TiSi-film, using a similar process, on top of a deposited polycrystalline layer. USE/ADVANTAGE - The process allows the use of a Ti-silicide film in devices even though at least one heat treatment above 600 deg.C will be carried out after its depsn. This allows advantage to be taken of the low resistance of the Ti-silicide film. The process is carried out as part of a mfg. process of integrated circuits, including Drams where the contacts are made with polycrystalline Si part of which has been converted to Ti-silicide.