No abstract

A system and a process have been developed for the low pressure chemical vapor deposition (LPCVD) of titanium sillcide. We report for the first time the optimization of LPCVD titanium silicide film properties against the deposition parameters, including the temperature, pressure, and SiHJTiC14 flow rate ratios. Smooth, reproducible, low resistivity (15-20 ~-cm) titanium silicide films have been deposited at a temperature of 730~ a pressure of 67 mtorr, and a SiH4/TiC14 flow rate ratio of 20/2. The as-deposited films did not require any post-deposition annealing to achieve this low resistivity. All the as-deposited films had a Si/Ti metal ratio of about 2 (determined by Rutherford backscattering spectroscopy). Within the Auger detection limit, no contamination was observed in the silicide films, and the films had uniform composition except for a transition region between the titanium silicide and the underlying polysilicon layers. During the experiments, it was observed that the SiH4/TiC14 flow rate ratio is the primary variable that affects the titanium silicide film properties. The rate of the silicon consumption during the silicide deposition has been determined and discussed in conjunction with the dependence of this rate on the TIC14 flow rate; increasing the TIC14 flow increases the polysilicon consumption rate. ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 142.58.129.109 Downloaded on 2015-03-16 to IP Vol. 135, No. 10 TITANIUM SILICIDE 2591

In this paper, we present a study on signal isolation approaches for mixed-signal circuits, via both simple test structures and actual circuits. Analysis was focused on commonly used substrates such as p+, p-and buried p+ substrate. Results show that the selection of substrate, isolation structures and layout rules have significant impact on the substrate noise isolation.

The low pressure chemical vapor deposition (LPCVD) of titanium silicide is reported here for the first time. X-ray diffraction spectra show that the as-deposited films are polycrystalline and TiSi2 is the predominant phase. The as-deposited films had resistivities of 22 to 39 μΩ cm with film thicknesses ranging from 2000 to 15 500 Å, and Si/Ti ratios of 1.8 to 2.3 as determined by Rutherford backscattering spectroscopy. Auger analyses did not detect any impurities such as oxygen and carbon in these films. The LPCVD system consists of a cold wall reactor with the wafer being heated externally by infrared lamps. The reactor is capable of sequential deposition of polycrystalline silicon (polysilicon) and silicide films; moreover, the final annealing step, if necessary, can be performed in situ. Care has been taken to provide a clean environment by using a turbomolecular pump which is capable of keeping the base pressure of the reactor ≤10−7 Torr. We have deposited in situ sequential films of polysilicon and titanium silicide in this system. The silicide films were deposited by reacting SiH4 with TiCl4.

We report for the first time the effects of very low pressure chemical vapor deposited (VLPCVD) titanium silicide on device electrical characteristics. The compatibility of this material for VLSI technology is examined through careful characterization of the shallow junction and gate oxide integrities, sheet resistance, and contact resistivity. It is shown that the integrity of the shallow junctions is preserved if the silicon consumption during the silicide deposition is controlled. If this consumption is not controlled, a Schottky diode behavior is observed for the source/drain junctions. It is shown that titanium silicide lowers the specific contact resistivity of metal/source-drain and metal/polysilicon structures by an order of magnitude and a factor of 4-5, respectively. The sheet resistance of the doped polysilicon (gate conductor) is reduced by more than two orders of magnitude through using a TiSi2/polysilicon structure. In addition, it is shown that VLPCVD titanium silicide has no significant effect on the quality of the gate oxide. Slightly lower breakdown voltages for the TiSi2/ polysilicon capacitors are measured, which could be due to the stress induced by siliciding the gate. The results presented in this paper indicate the suitability of VLPCVD titanium silicide films for high quality device fabrication.ABSTRACT A mechanistic study of oxide deposition from silane and nitrous oxide between 495~ and 690~ was performed in a laminar flow, cool wall reactor. Results indicated the existence of two distinct chemical pathways. At high nitrous oxide concentrations, the deposition reaction is dominated by radical chain chemistry initiated by the decomposition of N20. At lovcer N20 concentrations, the decomposition of siIane to form silylene (SiH~) initiates the deposition. Studies of the reaction of disilane and nitrous oxide confirmed the role of Sill2 in the deposition. Reactions involving Sill2 are used to explain the observed growth of sub-stoiehiometric oxides under low N20 conditions. ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 128.122.253.212 Downloaded on 2015-06-06 to IP