Self‐Aligned Ti Silicide Formed by Rapid Thermal Annealing

Abstract

Different aspects of the reaction between Ti and single‐crystal (100) Si are reported when the reaction is thermally activated by rapid thermal annealing. The sheet resistance variation of the TiSix film was measured for a wide range of annealing temperatures, from 400° to 1100°C, in two different atmospheres of high purity Ar and N2 gas, for bare and As‐implanted Si. At temperatures ⩾800°C, the only silicide formed was TiSi2 . Both cross‐sectional TEM and RBS results indicate that the amount of titanium consumed in the reaction depends strongly on the atmosphere used for silicidation. Argon makes possible the reaction of almost the whole Ti layer with silicon, while nitrogen leaves an unreacted layer of about 15 nm, independent of the thickness of the original film. A two‐step anneal is necessary to eliminate bridging in a patterned oxide structure. No difference was observed in the roughness of the external surface whether the samples were annealed in Ar or in N2 . No significant enhanced diffusion of As into Si was observed near the normalSi/TiSi2 interface after RTA in an Ar ambient, while a redistribution of As into the silicide takes place. The As piles up at the TiSi2 surface, from which it evaporates at high temperatures. Results of furnace‐annealed samples in N2 atmosphere show a pile‐up of As at the normalSi/TiSi2 and the TiSi2/normalambient atmosphere interfaces, where it evaporates from the latter, at high temperatures.

Fabrication and characterization of microsieve electrode array (µSEA) enabling cell positioning on 3D electrodes

“…Titanium-rich silicide (Ti 5 Si 3 ) and TiSi are possible candidates. The formation of these silicides is mainly observed as a problematic feature at temperatures of ⩾600 °C in the fabrication of gate electrodes using TiSi 2 [39]. From our experiments, this unexpected titanium silicide compound seems to be formed on the pore walls at RTP-1 temperatures as low as 550 °C, under both nitrogen and forming gas, while Ti 5 Si 3 and TiSi formation is reported for a 600 °C RTP in an argon ambient and not a nitrogen ambient [39].…”

“…The formation of these silicides is mainly observed as a problematic feature at temperatures of ⩾600 °C in the fabrication of gate electrodes using TiSi 2 [39]. From our experiments, this unexpected titanium silicide compound seems to be formed on the pore walls at RTP-1 temperatures as low as 550 °C, under both nitrogen and forming gas, while Ti 5 Si 3 and TiSi formation is reported for a 600 °C RTP in an argon ambient and not a nitrogen ambient [39]. This also supports our assumption that the pore walls reach significantly higher temperatures compared to the RTP temperature settings (including the temperature measured by internal thermocouple in the RTP system).…”

Effect of the Ti/TiN bilayer barrier and its surface treatment on the reliability of a Ti/TiN/AlSiCu/TiN contact metallization

“…First, it is well established that the C49-TiSi 2 phase is metastable. [19][20][21] On the other hand, B atoms diffuse out of the Si and through the silicide and have no retardation effect on the growth of the silicide layer. It is also possible that the C49-TiSi 2 grains increase in size and that might result in the deformation of the interface between TiN and Si or agglomeration of the polycrystalline film.…”

“…12,15 As the number of annealing cycles increases ͑and therefore the annealing time͒, it is possible that this phase slowly transforms into the more stable C54-TiSi 2 phase due to the increasing amount of Si atoms that diffused from the substrate into the silicide. [19][20][21] Retardation of the silicide formation may lead to a degradation of the interface between the silicide and the Si substrate. 18 A second factor to consider is dopant redistribution from the active region into the silicide during the annealing cycles.…”

The Effects of Processing Ambient on the Reaction Rate of Ti and Si Using Rapid Thermal Processing

“…The argon pressure and deposition rate were carefully adjusted to ensure that the Ti film has a dense, void free and small fibrous grain structure [15,16].…”