The process kinetics, chemical composition, morphology, microstructures, and stress of rapidthermal low pressure metalorganic chemical vapor deposited (RT-LPMOCVD) TiN, films on InP, using a combined reactive chemistry of ammonia (NH,) gas and tetrakis (dimethylamido) titanium ( DMATi) liquid precursors, were studied. Enhanced deposition rates of l-3 nm s -' at total chamber pressures in the range of 3-10. Torr and temperatures of 300 "C-350 "C at a NHs:DMATi flow rate ratio of I:8 to 1:15 were achieved. Stoichiometric film compositions were obtained, with carbon and oxygen impurity concentrations as low as 5%. Transmission electron microscopy analysis identified the deposited films as TiN with some epitaxial relationship to the underlying (001) InP substrate. This process provides a superior film to the preview RT-LPMOCVD TN, film deposited using only the DMATi precursor. 993

Articles you may be interested inMean-time-to-failure study of flip chip solder joints on Cu/Ni(V)/Al thin-film under-bump-metallization J. Appl. Phys. 94, 5665 (2003); 10.1063/1.1616993 Au-Sn solder bumps with tungsten silicide based barrier metallization schemesThe possibility of replacing Pt in the Ti/Pt/Au base and traditionally used metallurgical structure by Ni, while bonding InP laser chip to a submount with AuSn (80% Au) solder, has been investigated. Various Ni-based metal alloys have been prepared by evaporation. Reflow experiments were conducted in a chamber under forming gas-controlled ambient. The Ti/Ni/ AuSn system provided much longer surface local freezing duration compared to the Ti/Pt/ AuSn system. Scanning electron microscopy analysis revealed a smoother surface morphology for the Ti/Ni/AuSn system after the metal refroze. Auger electron spectroscopy depth profiles indicated the formation of a NiSn-Au interacted layer. The interaction took place in two steps: the iirst stage was the dissolution of Ni into the Au-Sn liquid followed by precipitation of a Ni-&-Au intermetallic compound; the second stage was a solid-state interdiffusion of Sn, Au, and Ni which occured in the interacted layer and in the original Ni layer. The latter step was a diffusion-controlled process, resulting in a very slow growth rate. Both Au and Sn reacted to form Ni alloy layers of almost equal thickness, regardless of the reaction duration (up to about 5 min). This intensive reaction, however, did not lead to full consumption of the Ti interfacial layer, which provided an excellent adhesion layer between the submount and the metallurgical structure.

Titanium nitride (TiNx) thin films were deposited onto InP by means of the rapid-thermal-low-pressure-chemical-vapor-deposition (RT-LPMOCVD) technique, using the tetrakis (dimethylamido) titanium (Ti(NMe2)4 or DMATi) complex as the precursor. Depositions were successfully carried out at temperatures below 550 °C, pressure range of 5–20 Torr and duration of 50 to 90 s, to give layer thicknesses up to 200 nm and growth rates in the range of 0.8 to 4.5 nm/s. These films had a stoichiometric structure and contained nitrogen and titanium in a ratio close to unity, but also contained a significant amount of carbon and oxygen. The elements were spread uniformly through the films, the nitrogen was Ti bounded, and the carbon was partially titanium bonded and organic bonded as well. The film resistivity was in the range of 400–800 μΩ cm−2; the stress was always compressive, in the range of − 0.5 × 109 to − 2 × 1010 dyne cm−2, and the film had a good morphology. These layers performed as an ohmic contact while deposited onto p-In0.53Ga0.47As material, (Zn-doped 1.2 × 1018 cm−3), provided an excellent step coverage for high aspect ratio via holes and were deposited selectively onto the InP and based materials when using SiO2 mask. This represents the first report of TiNx films deposited in a commercial RT-LPMOCVD reactor using the DMATi precursor.

The reactive ion etching of GaAs with a CCl2F2:O2 discharge was investigated as a function of gas flow rate (10–60 sccm), total pressure (2–50 mTorr), power density (0.25–1.31 W cm−2), gas composition (0%–70% O2), and etch time (1–64 min). The etch rate decreases with increasing gas flow rate, increases with increasing power density, and goes through a maximum at a gas composition of 75:25 CCl2F2:O2 under our conditions. After etching at low-power densities (0.56 W cm−2) and for high CCl2F2 ratios (19:1 to O2), carbon and chlorine could be detected in the GaAs to a depth of less than 15 Å by x-ray photoelectron spectroscopy. Under these conditions there was a Ga deficiency to a depth of ∼100 Å, which we ascribe to surface roughening and the preferential vaporization of As2O3 over Ga2O3. At high-power densities (1.31 W cm−2) a polymeric layer several hundred angstroms thick containing CCl and CF bonds was observed on the GaAs surface. Etching under O2-rich conditions did not lead to any additional creation of surface oxides. Both ion channeling and electron microscopy detected a thin disordered layer on the GaAs after etching. Small (<100 Å diam) dislocation loops were present at a depth varying from ∼400 Å for 0.56 W cm−2 (380-V self-bias) plasma power density to ∼2200 Å for 1.31 W cm−2 (680-V self-bias). The disorder was stable against a 500 °C annealing treatment.

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