shared via CourseHero com This study resource was This study source was downloaded by 100000788678392 from CourseHero com on 10 20 2021 01 13 32 GMT 05 00 https www coursehero com file 39456554 Tutorial 9 lecturepdf 1 Tutorial 9 Problem 1 WWWR 26 17 Microvia are microscopic passages between two thin films on a microelectronic device Often microvia are filled with a conductive metal to make a microscopic conductor for the flow of electrons between the two thin films In one particular process tungsten is deposited onto the base of the microvia by the following chemical vapor deposition reaction WF6 g 3 H2 g W s 6 HF g As the tungsten metal forms it fills the microvia 2 0 m depth 0 5 m diameter as illustrated in the following figure The tungsten metal does not coat the side walls of the microvia it only grows upward from the base of the microvia where the tungsten was initially seeded The reactants are significantly diluted in inert Helium He gas to lower the deposition rate The temperature is 700K the total system pressure is 75 Pa and the concentrations of WF6 and H2 in the bulk gas space over the microvia are each 0 001 mol Assume that the tungsten deposition is limited by molecular diffusion The molecular weight of tungsten W is 184 g mol the molecular weight of fluorine is 19 g mol and the density of solid tungsten is 19 4 g cm3 a Develop a pseudo steady state model to predict the depth of tungsten metal within the microvia as a function of time Estimate the time required to completely fill the microvia assuming Knudsen diffusion for WF6 vapor shared via CourseHero com This study resource was This study source was downloaded by 100000788678392 from CourseHero com on 10 20 2021 01 13 32 GMT 05 00 https www coursehero com file 39456554 Tutorial 9 lecturepdf shared via CourseHero com This study resource was This study source was downloaded by 100000788678392 from CourseHero com on 10 20 2021 01 13 32 GMT 05 00 https www coursehero com file 39456554 Tutorial 9 lecturepdf shared via CourseHero com This study resource was This study source was downloaded by 100000788678392 from CourseHero com on 10 20 2021 01 13 32 GMT 05 00 https www coursehero com file 39456554 Tutorial 9 lecturepdf shared via CourseHero com This study resource was This study source was downloaded by 100000788678392 from CourseHero com on 10 20 2021 01 13 32 GMT 05 00 https www coursehero com file 39456554 Tutorial 9 lecturepdf 2 Problem 2 WWWR 26 27 A 20 cm long cylindrical graphite pure carbon rod is inserted into an oxidizing atmosphere at 1145 K and 1 013 x 105 Pa pressure The oxidizing process is limited by the diffusion of oxygen counterflow to the carbon monoxide that is formed on the cylindrical surface Under the conditions of the combustion process the diffusivity of oxygen in the gas mixture may be assumed to be 1 0 x 10 5 m2 s a Determine the moles of CO that are produced at the surface of the rod per second at the time when the diameter of the rod is 1 0 cm and the oxygen concentration that is 1 0 cm radial distance from the rod is 40 mol Assume a steady state process b What would be the composition of oxygen 1 0 cm from the center of the rod shared via CourseHero com This study resource was This study source was downloaded by 100000788678392 from CourseHero com on 10 20 2021 01 13 32 GMT 05 00 https www coursehero com file 39456554 Tutorial 9 lecturepdf shared via CourseHero com This study resource was This study source was downloaded by 100000788678392 from CourseHero com on 10 20 2021 01 13 32 GMT 05 00 https www coursehero com file 39456554 Tutorial 9 lecturepdf shared via CourseHero com This study resource was This study source was downloaded by 100000788678392 from CourseHero com on 10 20 2021 01 13 32 GMT 05 00 https www coursehero com file 39456554 Tutorial 9 lecturepdf 3 Problem 3 WWWR 27 6 A large tanker truck overturns and spills a herbicide over a field If the mass diffusivity of the fluid in the soil is 1 x 10 3 m2 s and the fluid remains on the soil for 1800 s before evaporating into the air determine the depth at which plant and insect life is likely to be destroyed if a concentration of 0 1 by weight will destroy most of the life shared via CourseHero com This study resource was This study source was downloaded by 100000788678392 from CourseHero com on 10 20 2021 01 13 32 GMT 05 00 https www coursehero com file 39456554 Tutorial 9 lecturepdf Powered by TCPDF www tcpdf org