Process development of halide transport chemical vapor deposited (HTCVD) ZnS:Mn thin film has been studied. To this end, electrical characterization of HTCVD ZnS:Mn electroluminescent devices has been used. Process optimization focused on a simple design of experiment (DOE) with brightness as the major response. Deposition parameters such as HCl and H���S gas flow rates, ZnS and Mn source temperatures and substrate temperature were studied. A substrate temperature of 550��C gives the brightest devices. ZnS source temperature and H���S gas flow rate are insignificant parameters according to the statistical analysis. However HCl gas flow rate and Mn source temperature show strong interaction. It is proposed that the incorporation of Cl into the ZnS:Mn film causes the interaction. A Cl defect is also consistent with anomalous electrical behavior observed in the devices. Cl defects are thought to precipitate at the grain boundaries of the initial growth interface, then diffuse (or migrate) along the grain boundaries and possibly into the bulk crystal. This defect will easily form negative charge leading to asymmetric space charge in the bulk of the phosphor. Since the defects are believed to originate from the nucleation of Cl at high grain boundary density, one potential solution is to remove the Cl source as the grains begin to grow and only later expose the film to Cl. While film growth without HCl present at the beginning of deposition leads to brighter films, it is a sub-optimal solution. Part of the ZnS host does not have luminescent centers. It is believed other processing solutions need to be realized to make the HTCVD system viable. / Graduation date: 1999

Graduation date: 1995

Abstract The development and advancement of microelectronics technology has been very dramatic. However the cost of creating new process technology by using experiment has been very high. By using computer simulation to evaluate the performance of these equipment, we are able to achieve the same goal at a much lower cost. The reactor of chemical vapor deposition (CVD) is very important to semiconductor production process. This research use numerical method (simulation) to study the process parameters of Low-Pressure Chemical Vapor Deposition (LPCVD) of silicon (Si). In this simulation, the CVD reactor modelings are constructed and discredited by using implicit finite volume method. The grids are arranged in a staggered manner for the discretization of the governing equations. Then the SIMPLE-type algorithm is used to solve all of the discretized algebra equations. Many people in the field are beginning to realize that these challenges can no longer be tackled with the traditional trial-and-error method which have dominated the CVD technology since its beginning, and that modeling may lead to better process and equipment design, reduced costs, and improved IC manufacturing. It is also to be expected that in the future, detailed CVD simulation models will not only be used in design and optimization, but also in real-time process control. Key word: chemical vapor deposition, flow simulation, natural convection.

No description available.

No description available.

Honors Project--Smith College, Northampton, Mass., 2009. / Includes bibliographical references (p. 91-95)

Thesis (M.S.)--Oregon State University, 2009. / Printout. Includes bibliographical references (leaves 74-82). Also available on the World Wide Web.

No description available.

Tungsten metal is used as an electrical conductor in many modern microelectronic devices. One of the primary motivations for its use is that it can be deposited in thin films by chemical vapor deposition (CVD). CVD is a process whereby a thin film is deposited on a solid substrate by the reaction of a gas-phase molecular precursor. In the case of tungsten chemical vapor deposition (W-CVD) this precursor is commonly tungsten hexafluoride (WF6) which reacts with an appropriate reductant to yield metallic tungsten. A useful characteristic of the W-CVD chemical reactions is that while they proceed rapidly on silicon or metal substrates, they are inhibited on insulating substrates, such as silicon dioxide (Si02). This selectivity may be exploited in the manufacture of microelectronic devices, resulting in the formation of horizontal contacts and vertical vias by a self-aligning process. However, reaction parameters must be rigorously controlled, and even then tungsten nuclei may form on neighboring oxide surfaces after a short incubation time. Such nuclei can easily cause a short circuit or other defect and thereby render the device inoperable. If this loss of selectivity could be controlled in the practical applications of W-CVD, thereby allowing the incorporation of this technique into production, the cost of manufacturing microchips could be lowered. This research was designed to investigate the loss of selectivity for W-CVD in an attempt to understand the processes which lead to its occurrence. The effects of passivating the oxide surface with methanol against the formation of tungsten nuclei were studied. It was found that the methanol dissociates at oxide surface defect sites and blocks such sites from becoming tungsten nucleation sites. The effect of reactant partial pressure ratio on selectivity was also studied. It was found that as the reactant partial pressures are varied there are significant changes in the product partial pressure ratios, which are associated with gas phase reactions which contribute to the loss of selectivity.

Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references (leaves 141-150). Available also in a digital version from Dissertation Abstracts.