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.

The Thermionic Thermal Detector (TTD) senses infrared radiation by temperature modulation of thermionic emission current within a silicon Schottky diode. The thermionic emission current is the well known Richardson dark current. The TTD operates in the LWIR band. The physics of TTD operation is distinct from that of silicon Schottky barrier MWIR detectors, such as PtSi/Si which are based on internal photoemission. In fact, the TTD has high detection efficiency. The architecture of a TTD array is very similar to that of microbolometer arrays, except the detector elements are thermally isolated Schottky diodes, operating under reverse bias. When the TTD array is illuminated by an infrared image, the temperature of individual detector elements will vary with the local incident power of the image. Under small signal conditions, the dark current of individual detectors will vary as temperature, resulting in an electronic image of the infrared scene.The reverse bias dark current of a Schottky diode varies exponentially with temperature. For the small temperature variations observed on the focal plane of an uncooled sensor, this variation is approximately linear. The rate of temperature variation is determined by the Schottky barrier potential and, to a lesser extent by the applied bias potential. The operating temperature range of the detector can be designed into the device by selecting a metal with the appropriate Schottky barrier height. Experimental Schottky barrier heights were determined using Richardson dark current activation energy analysis. Devices optimized for operation at room ambient temperature have a 6%/K temperature coefficient. The use of Schottky diode thermionic emission for uncooled infrared imaging offers several advantages relative to current technology. TTD manufacture is 100% silicon processing compatible. Schottky barrier based thermionic emission arrays have the same uniformity characteristics as MWIR Schottky barrier photoemissive arrays. Operating TTDs in reverse bias provides a high impedance " current source" to the multiplexer, resulting in negligible Johnson noise. This mode of operation also results in negligible detector i/f-noise and drift. In addition, the TTD thermionic emission detection process has high efficiency, fully comparable with the best current thermal detectors. This paper describes the theoretical performance of a TTD based LWIR sensor. The focal plane architecture and multiplexer is similar to current microbolometer arrays, except the VO resistor is replaced with a TTD thermionic emission sensing element. The analysis models the detector using the appropriate optical radiation, thermal diffusion, and electrical conduction equations for 400K, 300K and 200K operation, using three different metal silicides. The effects of the optical radiation noise, thermal diffusion noise, Johnson noise, shot noise, and amplifier noise are considered in the analysis. Samples of the TTD designed for operation at 300 K and suitable for integration with a multiplexer, were fabricated and ...

Smooth titanium silicide films have been deposited using a Low Pressure Chemical Vapor Deposition (LPCVD) process. A system has been designed and built for the LPCVD of titanium silicide. It is a cold wall reactor with the wafer being heated externally by infrared lamps. Sequential deposition of polycrystalline silicon (polysilicon) and titanium silicide films, and in-situ annealing of these films, if required, can be performed in this system. A turbomolecular pump is used to provide a contaminant free environment with a base pressure of <10−7 torr. SiH4 and TiCl4 are used as silicon and titanium sources, respectively.Tithnium silicide films with resistivities ranging from 22 to 39 μΩ-cm have been obtained. At low deposition rates, these films have surface roughnesses ranging from 50 to 250 Å. From X-ray diffractometry, it was determined that the as-deposited titanium silicide films were polycrystalline, and TiSi2 was the predominant phase. Si/Ti ratios of 1.8 to 2.3 were obtained frog Rutherford Backscattering Spectroscopy (RBS). Auger analyses did not show any impurities such as oxygen, carbon or chlorine in these films.

We report on the tunneling properties of Ba1KBiO3 (BKBO) grain boundaries prepared on bicrystal substrates. We studied symmetric tilt boundaries with 5°, 24° , 36.8°and 45°m isorientation on SrTiO3, and 24° on MgO substrates. The three high angle misorientations used yield clear superconductor-insulator-superconductor behavior, with very little conductance below the bias corresponding to twice the BKBO energy gap, and a strong peak at that value. The two samples prepared on MgO yielded somewhat broader tunneling characteristics, but otherwise similar features compared to the samples prepared on SrTiO3 they showed the lowest junction resistivity and the weakest conductance increase at high bias. The linear conductance background consistently observed in superconductor-insulator-normal metal junctions is absent in the grain boundary junctions. For the 5° samples, we observe weak link behavior below T, with a critical current density of 65A/cm2. A similar angular dependence is seen in Nd,.85Ce015CuO8..

This article discusses the application of amorphous and crystalline films through plasma-enhanced chemical vapor deposition (PECVD) from the view point of microelectronic device fabrication. It describes the various types of PECVD reactors and deposition techniques. Plasma enhancement of the CVD process is discussed briefly. The article also describes the properties of amorphous and crystalline films deposited by the PECVD process for integrated circuit fabrication.