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Chemical mechanical polishing (CMP) is a process used to obtain planarized surfaces in microelectronic device manufacturing. The planarization is achieved by material removal from the wafer surface by synergistic effect of chemical and mechanical actions. The material removal rate (MRR) in chemical mechanical processes have a linear dependency on applied down pressure. However, some experimental studies have reported nonlinear relationship between MRR and applied pressure. The nonlinearity can be attributed to complex interactions among the wafer, pad, abrasive particles, and chemical agents in the slurry. Therefore, in modelling CMP processes, coupling of both the chemical and mechanical actions is imperative to provide insight into the nonlinear behavior of MRR, because treating the chemical effects only as a mere means of softening the wafer surface fails to explain the nonlinear behavior of MRR in silicon dioxide CMP. Here, we present a model that couples micro-contact mechanics with diffusion of slurry into the wafer and predict MRR in CMP of silicon dioxide. The model is validated with experimental results available in the literature. Moreover, the developed model may be used to explain the nonlinear increase in MRR of silicon dioxide with increasing applied pressure.

In this paper, we present a systematic approach to the gallium nitride (GaN) chemical mechanical planarization (CMP) process through evaluating the effect of crystallographic orientation, slurry chemistry and process variables on the removal rate and surface quality responses. A new CMP process and a complementary tool set-up are introduced to enhance GaN material removal rates. The key process variables are studied to set them at an optimal level, while a new slurry feed methodology is introduced in addition to a new tool set up to enable high material removal rates and acceptable surface quality through close control of the process chemistry. It is shown that the optimized settings can significantly improve the material removal rates as compared to the literature findings while simultaneously enabling a more sustainable process and potential removal selectivity against silica. GaN is defined as the silicon of the future based on its adaptability to a wide range of devices including microelectronics and photonics. 1It is used for the high power, high temperature and high frequency microelectronics device manufacturing due to its wide bandgap energy and high electron mobility including heterojunction field effect transistors (HFETs) and its derivatives (Metal Oxide Semiconductor HFETs-MOSHFET and Metal Oxide Semiconductor Double HFETsMOSDHFETs) as a barrier layer, 2 high electron mobility transistors (HEMTs) for power switching with AlGaN/GaN stacking as a buffer layer 3 as well as for the applications for heterojunction bipolar transistors (HBTs) and bipolar junction transistors (BJTs). 4 In addition, GaN is suitable for photonics device manufacturing based on its direct bandgap. It is designed into the light emitting diodes (LEDs) and ultraviolet LED (UVLED) manufacturing as an active region. 5,6 These applications require the polishing and optimal planarization of the GaN layers where CMP is the method of choice due to enabling nano-scale smoothness on the wafer surfaces in addition to enabling material and topographic selectivity through advanced slurry formulations.7 Yet, the main problem in integration of GaN is related to the challenges in its defect free deposition and its hard and brittle nature, which makes it difficult to polish and planarize in an integration scheme without creating surface defectivity, which can be defined as the elevated surface roughness, scratches, local pitting and protrusions, slurry particles and particles from the surroundings that might be left on the wafer surface.The growth of thick and crystalline GaN films is very challenging due to the formation of the threading dislocations between the selected substrate and the GaN interface that can act as the short-circuit leakage paths.1 Furthermore, it is also known that GaN films tend to crack above a critical thickness, which can even lead to the film and the substrate to fracture into separate pieces.8 Many conventional deposition techniques fail to satisfy the defect free deposition of GaN on conventional substrates such as si...

Chemical mechanical planarization is a process of achieving planar surfaces in the semiconductor manufacturing industry. The planarization of a surface is achieved by material removal from the wafer surface. The material removal depends on material properties and the process input parameters. Several studies have investigated the role of slurry chemistry to achieve a certain material removal selectivity for different materials. Here we propose a methodology of achieving a planar patterned surface of Cu/Mn/MnN using a model-based optimization for mechanical process parameters including applied force, slurry solid concentration, and abrasive particle size. The methodology has been developed via optimization using a genetic algorithm. The proposed methodology suggests that a lower downforce is the key parameter to achieve the desired material removal selectivity and planarity. The first part of the study suggests a low material removal rate (MRR) to achieve a lower standard deviation in MRR. The second part investigates the standard deviation in the thickness removed in the average time needed to remove a known thickness of the materials under consideration. It has been found that the application of lower downforce can also minimize the standard deviation in the thickness removed and a planar patterned surface can be achieved.

Surface properties of textiles play an essential role in their functionalization with micro/nanometer-sized polymeric capsules containing active agents that can provide controlled release. The attached capsules provide additional functionalities such as deodorizing, anti-microbial, or insect repellant properties. The efficiency of capsule attachment depends on the interaction between the selected textile material and the type of capsules. In this study, surface characteristics of the textiles were modified systematically to enhance the attachment of polyethyleneglycol based polymeric capsules. In the first phase of textile selection, four different textile materials, composed of 100% single fiber, were analyzed. Among the analyzed textile samples, cotton and polyester blends were investigated in detail due to their higher hydrophobicity, less negative zeta potential after treatment with finishing solution and broad applicability in sports outfits. In the second phase, statistical design of experiment (DoE) approach was used to have a deeper understanding of the processing factors such as the silicon (hydrophobic component) concentration in the finishing solution and the cotton/polyester blend ratio. An optimal textile was designed based on maximizing the capsule attachment on the cotton fibers woven on top and polyester at the bottom for providing strength and ease of ironing. The selected blend, treated with the required silicon concentration in the finishing solution, retained the highest amount of polymeric capsules containing eucalyptus oil for tick/insect repellency.