We report on the formation of a new material, C40 TiSi 2 , using pulsed laser annealing. On the basis of this laser-induced C40 TiSi 2 , the growth of the technologically important C54 phase is significantly promoted and can be accomplished with a subsequent rapid thermal anneal or furnace annealing at temperatures far below that for the normal C54 formation. The undesirable C49 TiSi 2 is completely bypassed. C40 TiSi 2 can also be easily transformed to the C54 phase with thermal treatments and result in the formation of a pure C54 TiSi 2 layer. The synthesis of C40 phase without the additional refractory metals and its promotion effect on the C54 phase formation have great potential for applications in the integrated circuit industry for 0.10 m technology node and beyond.Titanium disilicide ͑TiSi 2 ) has been widely applied as contact and gate electrodes for complementary metal-oxide-semiconductor ͑CMOS͒ transistor in ultralarge-scale integration ͑ULSI͒ technology. 1 In the current semiconductor industry, rapid thermal annealing ͑RTA͒ is used to fabricate TiSi 2 from Ti/Si wafers. The high resistivity ͑60-70 ⍀ cm͒ metastable C49 phase forms first at RTA temperatures of 550-700°C and transforms to the lowresistivity ͑15-20 ⍀ cm͒ stable C54 phase at higher temperatures of 750-850°C. C54 TiSi 2 is the preferred phase for integrated circuit ͑IC͒ fabrication due to its lower resistivity and better thermal stability as compared with C49 phase. Therefore, a complete C49 to C54 phase transition is important for IC fabrication. However, due to the ''fine line effect'', 1 the transformation to C54 phase on narrow polysilicon lines requires very high annealing temperature, which causes severe problems such as agglomeration 2 and ''punch through'' 3 and results in device failure. Promoting C54 phase formation at low annealing temperatures is essential in terms of both industrial requirements and scientific interests.The conventional preamorphization implantation ͑PAI͒ 4 and implantation through metal ͑ITM͒ 5 methods were usually used to enhance the C54 phase formation by using implantation to create an amorphous Si surface. In recent studies, refractory metals were found to facilitate the C54 phase formation and three approaches were developed to lower the C54 phase formation temperature. A group of IBM researchers first demonstrated that ion implantation of a small dose of refractory metals into the Si substrate prior to Ti deposition could reduce the C54 TiSi 2 formation temperature by 100-150°C. 6 Cabral et al. from the same group later revealed that codeposition of Ti alloyed with refractory metals could serve the same purpose. 7 Mouroux et al. 8 used a different approach in which a thin layer of refractory metal was deposited between Ti capping layer and Si substrate, and the C54 phase was obtained at 100°C lower than the normal C54 formation temperature. 8 Here we demonstrate a different approach to enhance the C54 phase growth and to effectively lower its formation temperature, using laser processing as the first ann...

A refractory-metal-free C40 TiSi2 phase formed by pulsed-laser annealing is identified experimentally by combined convergent beam electron diffraction (CBED) study and CBED pattern simulation. The simulation shows that the C40 TiSi2 has a hexagonal structure with the space group P6222 (180) and lattice parameters a=0.471 nm and c=0.653 nm. Upon further furnace annealing or rapid thermal annealing, C54 TiSi2 can be directly achieved from C40 TiSi2 at low temperatures (600–700 °C). This observation suggests that pulsed-laser annealing is promising for extension of TiSi2 into the subquarter micron region in semiconductor device fabrication.

In this letter, we report on the direct synthesis of C54 TiSi2 films with fine grains by pulsed-laser irradiation from Ti deposited on Si substrates, using a Q-switched Nd:YAG laser. The films were characterized using micro-Raman spectroscopy, high-resolution transmission electron microscopy, and atomic force microscopy. In comparison with the C54 TiSi2 using the conventional rapid thermal annealing (RTA) of 35 nm thick Ti/Si, which has an average grain size of about 110 nm and film thickness of 50 nm, the laser-induced C54 TiSi2 films vary from 13 to about 42 nm in thickness with different laser scanning speed and the grain size is 85 nm on average. The TiSi2/substrate Si interface is smooth on the atomic scale. Our results demonstrate the unique advantages of the laser-induced formation technique and its potential in deep submicron semiconductor technology. We propose that the C54 phase is formed by solid-state diffusion, rather than melting.

In this paper laser thermal processing ͑LTP͒ is applied to induce the Ti silicide formation in replacement of rapid thermal annealing ͑RTA͒ in narrow lines. Results show that the C40 TiSi 2 is synthesized after LTP in both large and small features. With this interfacial C40 TiSi 2 , the C54 TiSi 2-phase formation temperature can be lowered by 100°C during subsequent annealing. The C40-C54-phase transition is also achievable with low temperature treatment. Most importantly, the C54 TiSi 2 growth is linewidth independent down to at least 0.25 m using LTP followed by RTA. LTP provides a possible technique to extend the application of TiSi 2 to subquartermicrometer technologies.

In this article, we report on the laser‐induced formation of both C49 and C54 TiSi2 films with fine grains using Q‐switched Nd : YAG laser irradiation from Ti/Si samples. The films formed were characterized with micro‐Raman spectroscopy, high‐resolution transmission electron microscopy, energy‐dispersive spectrometry and atomic force microscopy. The TiSi2 films synthesized are single‐phased and thin, with fine grains and a smooth film/substrate interface on the atomic scale. The process is likely to proceed via a solid‐state reaction rather than liquid‐phase intermixing. Our results demonstrate the unique advantages of a laser annealing technique and its potential in deep submicron semiconductor technology. Copyright © 1999 John Wiley & Sons, Ltd.