Engineering Science and Materials Commons^™

Synthesis Of Boron Nitride/Vycor Composite Membrane Structures By An Optimized Lpcvd Process, Chenna Ravindranath

Theses

Since the advent of the idea of ultrafiltration, microporous membranes have come through a long way in establishing a niche as an efficient technology for gas separation applications. More and more research is aimed at reducing pore size towards nanolevels, when separation factor is the criterion rather than the permeability. This work is focused at synthesizing and characterizing microporous inorganic membranes for gas separations by molecular sieving. BN was deposited on mesoporous vycor tubes using triethylamine borane complex (TEAB) and ammonia as precursors. Effect of temperature and deposition geometry on permeability of various gases has been studied. Very high selectivities …

Low Pressure Chemical Vapor Deposition Of Tungsten As An Absorber For X-Ray Masks, Hongyu Chen

Theses

Tungsten film is one of promising materials for X-ray absorber in X-ray Lithography technology because of its high X-ray absorption and refractory properties. This study focus on CVD method to make tungsten film for X-ray absorber.

In this work, a cold wall, single wafer, Spectrum 211 CVD reactor was used for the deposition of tungsten from H, and WF6. The growth kinetics were determined as a function of temperature, pressure and flow ratio. The deposition rate of as deposited tungsten films was found to follow an Arrehnius behavior in the range of 300-500°C with an activation energy of 55.7 kJ/mol. …

The Photolithographic Patterning Of Porous Silicon Using Silicon Nitride And Silicon Carbide Films As Masks, Hong Wang

Theses

In this study, a simple photolithographic pattern process for porous silicon is described. The process utilizes silicon nitride or silicon carbide coated on the top of silicon wafer as a masks. Then a test pattern was projected on the sample by illumination during anodic etching in HF:ethanol solution which produced microcracks in regions illuminated during anodization. Creation of these microcracks resulted in formation of porous silicon in the underlying regions. The cracking is related to the stress in the thin film. The films with tensile stress exhibit cracking while compressive stress samples do not. Compared to silicon carbide films, silicon …

Aeration And Operation Of An Immobilized Cell Oxidative Bioreactor, James Joseph Woods

Theses

The primary purpose of this work is to help define the optimum window of operations for an immobilized cell oxidative bioreactor. The analytical technique employed requires no outside verification (such as G.C. analysis) and is independent of liquid flow rate. Method of aeration has been determined to be an important parameter for optimizing bioreactor efficiency, and optimization of the quantity of hydrogen peroxide added to provide oxygen during bio-oxidation has been investigated. Ammonium hydroxide as a fixed nitrogen source can be used to restore the vitality of the bioreactor under certain conditions.

The effects of several different methods of providing …

Low Pressure Chemical Vapor Deposition Of Copper Films From Cu(I)(Hfac)(Tmvs), Wei-Shang King

Theses

Recently, copper has been found as a possible substitute for Al alloys because of its low resistivity (1.67 μΩ • cm) and potentially improved resistance to electromigration. Conventional physical vapor deposition (PVD) method do not provide the conformal deposition profile for the high density integrated circuit, therefore, chemical vapor deposition (CVD) has become the most promising method for the resulting conformal profile.

In this work, a cold wall, single wafer, CVD tungsten reactor was used for the deposition of copper with Cu(I)(hfac)(tmvs). Film growth rates were between 100 to 800 A/min depending on processing conditions, and an Arrhenius type activation …

Synthesis Of Silicon Oxide/Vycor Composite Membrane Structures By An Optimized Lpcvd Process, Abhijit Datta

Theses

This study is focused on development of highly selective ceramic membrane structures consisting of silicon dioxide films synthesized by low pressure chemical vapor deposition (LPCVD) on mesoporous Vycor substrates. The ability of easily altering the composition of such films by varying the LPCVD processing parameters affords the opportunity of microengineering the pore structure by reducing the diameters of pre-existing pores in the support. The process parameters investigated include, deposition temperature, total pressure, and flow rate of oxygen. Both the kinetics and select properties of the deposits were examined. The growth rate as a function of temperature was seen to follow …