There is no abstract available for this thesis.

The purpose of this thesis is to design and fabricate the S-shaped profile in depth. The results are applied to design a beam expander. In the experiments, we use the local etch-rate control, i.e. diffusion-limited etching, to fabricate the S-shaped profile. The etchant solution and recipe is H3PO4:H2O2:H2O =98:1:1 at 21¢J without stirring. The diffusion length of the etchant solution is 12.5mm. The device includes active semiconductor laser and passive tapered waveguide (beam expander). The design of the passive waveguide includes the lateral and vertical directions. In the lateral aspect, we use FimmWave to simulate the best symmetrical far field angle. When the waveguide width is 2.5mm and the etching depth is 1.4mm, we can get the best symmetrical far field angle which is lateral 27.88¢X and vertical 27.76¢X. In the vertical aspect, we use diffusion-limited etching to fabricate the depth changing. In this thesis, we use the beam expander length 350, 400, 450, 500mm.

The Etching Chamber is the most important component of Etcher. It provides an environment to etch wafer and transfer wafer to another chamber by robotic arm. The purpose of this research is to solve some problem such as the huge deformation around the edge of a hole which connected with a vacuum pump. And make use of the Engineering Design Method to redesign the original Etching Chamber. In the first place, the objectives of Etching Chamber are clarified, then establish function analysis figure and set requirement to separate all problem into all sub-problem . Second, by means of determining characteristics as well as generating alternatives, we can find all sub-solutions. Finally, we combine all solutions together by evaluating alternatives and improving details. Then we can find better solutions through appropriate process as well as solve all problem. Later, we use the computer aid design tool I-DEAS to draw and analyse Etching Chamber. In the end, we display the results and discuss after analysing chamber. What is more, we prove the performance and manufacturing cost of redesign Etching Chamber is better than original Etching Chamber.

Abstract Anisotropic wet etching is one of the key technologies for the microstructure fabrication in Micro Electro Mechanical Systems (MEMS). Agitation technique is one of the key parameters to affect significantly the quality of silicon anisotropic wet etching, which includes the etch rate and surface roughness. In general, magnetic stirring is used during silicon anisotropic wet etching operation. The ultrasonic agitation and add surfactant have been to replaced and to proceed a series of experiment for KOH solution and TMAH solution in this study. The results show that the ultrasonic agitation can reduce the surface roughness and achieve the high-quality etching surface, its roughness even is only about Ra 47.5Å. Besides, the etch rate is also increased slightly. But it is easily to cause the damage of the microstructure. The addition of anionic surfactant to the KOH solution without any agitation condition can achieve the same at the etching performance of the ultrasonic agitation. The addition of anionic surfactant and nonionic surfactant to the TMAH solution without any agitation condition can achieve the same at the etching performance of the ultrasonic agitation. TMAH solution adds nonionic surfactant not only improves the surface roughness, but also retards the phenomenon of the undercut. Keyword¡Ganisotropic wet etching, magnetic stirring, ultrasonic, surfactant

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Supercritical CO₂ (scCO₂) is emerging as a viable and environmentally sustainable platform for nanomaterials synthesis due to its tunable solvent properties combined with low surface tension and viscosity, which allow rapid, non-destructive wetting within small features. However, to advance the utility of this fluid, a more thorough understanding of surface chemistry at high pressures is needed. In this study, the behavior of reactive solids in scCO₂ was examined by etching thin dielectric, metal, and alloy films to determine the fundamental mechanisms controlling the reactions. Models were developed to describe the etching processes and to benchmark scCO₂ with conventional methods. Dielectric SiOₓNy films were etched with an HF/pyridine complex dissolved in scCO₂. The anhydrous etching process resulted in formation of a residual (NH₄) ₂SiF₆ layer that limited transport of reactants to the film and caused a drop in reaction order. Partial removal of the salt was accomplished by sublimation under vacuum. Etching of thin CuO films with hexafluoroacetylacetone (hfacH) in scCO₂ was studied and found to occur via a 3-step Langmuir-Hinshelwood reaction sequence. The kinetic model showed that lower scCO₂ densities favored hfacH adsorption on the CuO surface and that scCO₂ solvation forces lowered the activation barrier for the rate-limiting step. Adding up to 10× the molar ratio of pure H₂O to hfacH nearly doubled the etching rate through formation of a hydrogen-bonded hfacH complex. Both bulk and thin film AgCu alloys were selectively etched in scCO₂ to generate nanoporous Ag structures. As Cu was preferentially removed through selective oxidation and chelation, the Ag atoms conglomerated into successively larger clusters similar to mechanisms reported in aqueous phase dealloying. Supercritical dealloying was observed at Cu compositions below typical parting limits, suggesting enhanced fluid transport in the evolving pores. When using in situ oxidation, the etching reaction was limited by decomposition of H₂O₂. Inverse space image analysis of samples with initial phase domain sizes between 250 - 1000 nm showed that below a threshold of approximately 500 nm, the dealloyed feature size mimicked the starting microstructure. Larger phase domains prohibited surface diffusion of Ag between phases producing a mixture of large and small Ag nanostructures.

No description available.

No description available.

This thesis describes investigations on Cu, Ag, and Au subtractive etching by H₂ and CH₄ plasmas below room temperature. Both blanket film of Cu, Ag, and Au etching and patterning studies were performed for the applications of these metals as interconnects in electronic devices and photonic devices to replace current Damascene process. The nm scale Cu patterning in H₂ plasma was demonstrated by etching Ta/Cu/Ta stacks. Also, Ag and Au etching was feasible in H₂ plasma unlike other transition metals such as Ti, Ta, Ni, Cr, Al, and Pt indicating the etching chemistry based on the similar electronic structures of group 11 metals plays important role. In addition, employing CH₄ plasma allowed the use of photoresist mask and patterned Cu, Ag, and Au with high selectivity. The overall etch mechanism is the combination of chemical reactions and physical (photon and ion) bombardment in H₂ and CH₄ plasma. However, the Cu etching mechanism is more dependent on the chemistry while Ag and Au patterning were dominated by physical bombardment. Finally, the direction for future work including further mechanistic study and process optimization is suggested.

Thesis (M. Eng.)--Carleton University, 2002. / Includes bibliographical references (p. 60-63). Also available in electronic format on the Internet.