Optimized Deposition Parameters for Low Pressure Chemical Vapor Deposited Titanium Silicide

Ilderem, V.; Reif, R.

doi:10.1149/1.2095387

Cited by 40 publications

(18 citation statements)

References 8 publications

(15 reference statements)

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“…In the initial stage of deposition, TIC14 and the silicon substrate react to produce Ti~Si4, an undetermined silicide, and SiCI~ (n = 1,2,3,4). This reaction explains the high sensitivity to the native oxide.…”

mentioning

confidence: 99%

Reaction and Film Properties of Selective Titanium Silicide Low‐Pressure Chemical Vapor Deposition

Saito

Higashi²,

Amazawa

et al. 1994

J. Electrochem. Soc.

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The reaction processes of selective titanium silicide low-pressure chemical vapor deposition using a TiC14/SiH4 gas system at 720 to 740~ are studied, in conjunction with film properties, using quadrupole mass spectrometry measurements and other analyses. In the initial stage of deposition, TIC14 and the silicon substrate react to produce Ti~Si4, an undetermined silicide, and SiCI~ (n = 1,2,3,4). This reaction explains the high sensitivity to the native oxide. After that, the Sill4 gas joins into the reaction to produce C54-TiSi2, HCI, H2, relatively small amounts of SiCl~ (n = I, 2, 3, 4), and SiHCI. This reaction moderates silicon consumption and changes the film properties. The features of this reaction at higher temperatures of 780 to 820~ are similar to those exhibited at 720 to 740~ Nucleation is discussed in terms of stress generation by a gradient in the Ti/Si composition, caused by independent changes in the source-gas decomposition rates.Titanium silicide films are being used as clad layers on source/drain and gate electrodes in ultralarge scale integration (ULSI) to reduce sheet resistance. Selective titanium silicide low pressure chemical vapor deposition (LPCVD) I-~ seems to have several advantages in forming the clad layers. LPCVD is a simple process resulting in low contact resistance. 5 However, it has shortcomings such as nucleation, which causes high sheet resistance in thin films, and large silicon consumption. Thin titanium silicide film with low sheet resistance and small silicon consumption is required to form the clad layers on very shallow junctions. While several studies have led to improved film properties, 6-9 further improvements are required to achieve titanium silicide films with these characteristics. Research on the deposition reaction is essential in improving the titanium silicide film properties because this reaction is not yet sufficiently understood.The reaction processes and film properties are explained herein on the basis of quadrnpole mass spectrometry (QMS) measurements and other analyses. A better understanding of the reaction will explain the characteristics of LPCVD such as high sensitivity to native oxide, silicon consumption, and film property changes during deposition. Nucleation of the titanium silieide is discussed on the basis of the results. ExperimentsSurface cleaning and film deposition.--p-Type (100)-oriented, 1 to 100 s cm silicon wafers were used. Thick SiO2 films were formed on a portion of each wafer. The SiQ films were partially etched by photolithography and wet etching. The patterned-oxide wafers were used to confirm selective deposition and bare silicon wafers were used for QMS and film property measurements. To reduce the "loading effect of deposition," which is explained in a later section, the area of the patterned oxide was kept small. The wafers were first dipped in dilute hydrofluoric acid (HF) to remove native oxide on the silicon surfaces and then rinsed in deionized water (DIW). The wafers were then loaded into a cold wall-type reaction cha...

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confidence: 99%

Reaction and Film Properties of Selective Titanium Silicide Low‐Pressure Chemical Vapor Deposition

Saito

Higashi²,

Amazawa

et al. 1994

J. Electrochem. Soc.

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“…A persistent challenge with the formation of TiSi 2 is the transition from the high-resistivity C49-type phase to the low-resistivity C54-type phase [11]. Incomplete phase transformation from the high-resistivity phase (C49-type) to the low-resistivity phase (C54-type) makes its update application difficult [12][13][14]. And the polymorphic transition from the C49-type phase to the C54-type phase is still a longstanding problem [15].…”

Section: Resultsmentioning

confidence: 99%

Co-reduction route to nanocrystalline titanium silicide by using different metal reductants

Ma¹,

Gu²,

Shi³

et al. 2004

Journal of Alloys and Compounds

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“…For this reason both reactions 7 and 8 will occur and contribute to the TiSi2 formation with a more complicated situation as a result. Furthermore, with hydrogen present, chlorosilanes (SiHzCl~_x) can be formed according to the overall reaction TiC14(g) + (2 + x)Si(s) + yH2(g) ~ TiSi2(s) + zHCl(g) + xSiHuCl,, [9] This reaction shows that the etching yield of the process is dependent on the molar ratio between the reactants. It is also dependent on the temperature and the total pressure.…”

Section: Calculation Proceduresmentioning

confidence: 97%

Selective Deposition of TiSi2 from H 2 ‐ TiCl4 Gas Mixtures and Si: Aspects of Thermodynamics Including Critical Evaluation of Thermochemical Data in the Ti‐Si System

Engqvist

Myers

Carlsson

1992

J. Electrochem. Soc.

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Chemical vapor deposition (CVD) of TiSi2 from TIC14, H2, and substrate silicon has been investigated thermodynamically. From a critical evaluation of the thermochemical data, an assessment of the Ti-Si binary phase diagram has been performed. This is the basis of a new set of thermodynamic values for the titanium silicides, which have been used in the calculations. As a comparison, two other common data sets have also been used. The results from the calculations showed that the trends in selectivity as well as substrate etching were not affected by the choice of the silicide data. However, in the calculated CVD phase diagrams the stability regions for the various equilibria were strongly affected. The selectivity of the process was found to be very high and was favored by a low temperature and a low H2/TiC14 molar ratio. Moreover, improved selectivity can be expected for hot-wall reactor conditions. It was also shown that thermodynamics can be used for prediction of trends in substrate etching. The lowest etching yield was obtained at low pressures, at high temperatures, and at high H2/TiC14 molar ratios.With the decreasing feature sizes of the integrated circuits there is a need for new metallization schemes. Metals like W, Cu, and AI and disilicides of Ti, Mo, and W are here attractive candidates for various metallizatien applications. I Among the disilicides TiSi2 has the lowest resistivity and a low contact resistance to silicon.TiSi2 can be prepared by techniques like evaporation and sputtering. ~ However, chemical vapor deposition (CVD) offers several advantages like selectivity, excellent uniformity, and good step coverage. TiSi2 can be deposited from an H2-TiCI4 vapor and using substrate silicon 2-6 or from H~-TiCI4 vapor with a gaseous silicon-carrying precursor (SiHI4 or SIC14). s-17 The latter case has the advantage of less consumption of the substrate silicon. Cold-wall ~47 as well as hot-wall reactors are used for TiSi~ CVD. 2-4 Concerning the deposition pathways, the basic difference between these two reactor types is that the homogeneous reactions in the vapor are favored in the hot-wall reactor, while these reactions are suppressed in a cold-wall reactor.As mentioned above, TiSi2 can be deposited selectively onto silicon on a patterned Si/SiO2 substrate from a TIC14 carrying vapor. The selectivity is based on the difference in reactivity between the different substrate materials Si and SiO2. The Si is much more reactive towards the vapor than SiO2 and hence the Ti deposition with the subsequent TiSi2 formation is localized to the Si windows according to a reaction TiCl4(g) + 3St(s) --) TiSi~(s) + SiCl4(g)[I]With He in the reaction gas mixture, competing reactions involving HCI also occur. Thermodynamic calculations can be used for prediction of trends in selectivity as well as substrate etching when changing the experimental parameters. Calculated CVD phase diagrams are often used in order to select appropriate deposition parameters, such as temperature, total pressure and molar ratio between the ...

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Optimized Deposition Parameters for Low Pressure Chemical Vapor Deposited Titanium Silicide

Cited by 40 publications

References 8 publications

Reaction and Film Properties of Selective Titanium Silicide Low‐Pressure Chemical Vapor Deposition

Reaction and Film Properties of Selective Titanium Silicide Low‐Pressure Chemical Vapor Deposition

Co-reduction route to nanocrystalline titanium silicide by using different metal reductants

Selective Deposition of TiSi2 from H 2 ‐ TiCl4 Gas Mixtures and Si: Aspects of Thermodynamics Including Critical Evaluation of Thermochemical Data in the Ti‐Si System

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