Interfacial reactions between Al and RuO₂, MoO_x and WN_x diffusion barriers on Si

Abstract

The interfacial reactions between A1 and RuO, , MOO, and WN, diffusion barriers on Si (100) wafers have been studied. The diffusion barrier structures were analyzed before and after various heat treatments using Auger electron spectroscopy (AES) and cross-seCtional transmission electron microscopy (XTEM). Al was found to reduce the oxides of both Ru and Mo. A 100 di thick A1,0, layer developed between the A1 and the RuO, films during annealing at 500°C for 30 minutes. The formation of interfacial Al,O, effwiently prevents A1 penetration but may cause a too high contact resistance for applications in contact structures of microelectronic devices. The WN, barrier was stable after annealing at 600 "C for 30 minutes, if the film was exposed to air prior to A1 deposition. If, instead, the A1 was deposited in situ, the structure failed after annealing at 500°C due to a reaction between A1 and W giving WAI,,. A thin A1,03 layer was detected between the A1 and the WN, films of the air exposed sample. This layer had the effect of retarding the ALW reaction and thereby raised the failure temperature of the barrier by at least 100 "C.

Amorphous (Mo, Ta, or W)–Si–N diffusion barriers for Al metallizations

“…Although widely investigated, only a marginal degree of stability has been achieved with most metal-nitride, 1-9 boride, 10-13 oxide, 6,14,15 and carbide 16 -20 barriers because aluminum reacts with the vast majority of these interstitial compounds. Also reactive with Al, many amorphous barriers [21][22][23][24][25][26] have had no advantage over their polycrystalline counterparts, despite their supposed lack of fast diffusion paths.…”