Copper CMP is a corrosion-wear process, in which mechanical and chemicalelectrochemical phenomena interact synergistically. Existing models generally treat copper CMP as a corrosion enhanced wear process. However, the underlying mechanisms suggest that copper CMP would be better modeled as a wear enhanced corrosion process, where intermittent asperity/abrasive action enhances the local oxidation rate, and is followed by time-dependent passivation of copper. In this work an integrated tribo-chemical model of material removal at the asperity/abrasive scale was developed. Abrasive and pad properties, process parameters, and slurry chemistry are all considered. Three important components of this model are the passivation kinetics of copper in CMP slurry chemicals; the mechanical response of protective films on copper; and the interaction frequency of copper with abrasives/pad asperities. The material removal rate during copper CMP was simulated using the tribo-chemical model, using input parameters obtained experimentally in accompanying research or from the literature.

Millisecond scale benzotriazole (BTA) adsorption kinetics in acidic aqueous solution containing 0.01M glycine and 0.01M BTA have been investigated. Chronoamperometry was used to measure current densities on the surface of a micro-copper electrode in pH 4 aqueous solutions containing 0.01M glycine with or without 0.01M BTA. In the presence of BTA the current density decreased as the inverse of the square root of time for a few seconds due to adsorption of BTA. At potentials above 0.4V saturated calomel electrode the current leveled off after a second or so due to the formation of a Cu(I)BTA monolayer on the copper surface. Based on these data a governing equation was constructed and solved to determine the initial kinetics of BTA adsorption. Analysis shows that material removal during copper chemical mechanical planarization (CMP) in this slurry chemistry occurs mostly by direct dissolution of copper species into the aqueous solution rather than mechanical removal of oxidized or pure copper species and that each interaction between a pad asperity and a given site on the copper removes only a small fraction of the Cu(I)BTA species present at that site.

In this paper a review of various methodologies for burr prediction and minimization in face milling is presented. In particular, the authors look into the geometric solutions employed, which typically consist of understanding and modifying tool engagement conditions. The extent of applicability of various approaches is discussed and the possible direction for future research is indicated.

During copper CMP, abrasives and asperities interact with the copper at the nano-scale, partially removing protective films. The local Cu oxidation rate increases, then decays with time as the protective film reforms. In order to estimate the copper removal rate and other Cu-CMP output parameters with a mechanistic model, the passivation kinetics of Cu, i.e. the decay of the oxidation current with time after an abrasive/copper interaction, are needed. For the first time in studying Cu-CMP, microelectrodes were used to reduce interference from capacitive charging, IR drops and low diffusion limited currents, problems typical with traditional macroelectrodes. Electrochemical impedance spectroscopy (EIS) was used to obtain the equivalent circuit elements associated with different electrochemical phenomena (capacitive, kinetics, diffusion etc.) at different polarization potentials. These circuit elements were used to interpret potentialstep chronoamperometry results in inhibiting and passivating solutions, notably to distinguish between capacitive charging and Faradaic currents.Chronoamperometry of Cu in acidic aqueous glycine solution containing the corrosion inhibitor benzotriazole (BTA) displayed a very consistent current decay behavior at all potentials, indicating that the rate of current decay was controlled by diffusion of BTA to the surface. In basic aqueous glycine solution, Cu (which undergoes passivation by a mechanism similar to that operating in weakly acidic hydrogen peroxide slurries) displayed similar chronoamperometric behavior for the first second or so at all anodic potentials. Thereafter, the current densities at active potentials settled to values around those expected from polarization curves, whereas the current densities at passive potentials continued to decline. Oxidized Cu species typically formed at 'active' potentials were found to cause significant current decay at active potentials and at passive potentials before more protective passive films form. This was established from galvanostatic experiments.

The quality of machined components in the aerospace and automotive industries has become increasingly critical in the past years because of greater complexity of the workpieces, miniaturization, usage of new composite materials, and tighter tolerances. This trend has put continual pressure not only on improvements in machining operations, but also on the optimization of the cleanability of parts. The paper reviews recent work done in these areas at the University of California-Berkeley. This includes: Finite element modeling of burr formation in stacked drilling; development of drill geometries for burr minimization in curved-surface drilling; development of a enhanced drilling burr control chart; study of tool path planning in face-milling; and cleanability of components and cleanliness metrics.

The traditional approach of thermo-mechanical (T-M) reliability modeling is based on power cycle events. This approach is not useful for products which are rarely powered down, because power cycles alone do not capture all the reliability stress from temperature variation over these products' use life.This paper describes a methodology to determine the temperature cycle requirements for products like smartphones and tablets which accounts for the temperature variation associated with usage events, which we call "mini-cycles".The T-M model is based on the distribution of individual users' histories as a series of events over time, which is then translated into a temperature vs. time trace for each user. These temperature traces are then used as the main inputs to T-M models, for example using the Norris-Landzberg (N-L) acceleration model to evaluate solder damage for each user. Results are summarized in a distribution of T-M damage across all users. This new methodology improves the understanding of thermo-mechanical reliability requirements due to the impact of "mini-cycles".KEY WORDS: ther mo -mechanical, solder joint reliability, event-based use conditions, knowledge-based qualification. INTRODUCTIONPresently, the majority of industry uses either JEDEC or power cycles [1, 2] to determine the package temperature cycle requirements. Power cycles include both on-to-off and on-to-suspend event cycles. The temperature cycle (TC) requirement for a product is determined by assigning temperatures to each distinct, time-weighted state (on, suspend, off), and accounting for the number of events over the product lifetime as the input to the T-M reliability model, which may be based on Norris-Landzberg (N-L) model. However, for products that are not regularly power cycled, like smartphones and tablets, power cycles alone do not capture all the reliability stress from temperature variation over time. There is significant temperature (T) variation associated with application (app) usage which should be accounted for towards determining the TC requirement.Usage events, such as phone calls, represent a temperature vs. time behavior which we call a mini-cycle, to distinguish it from power cycles. A distribution of actual user app traces can be converted by modeling to a sequence of mini-cycles. It has been shown [3, 4] that mini-cycles may have a significant impact on T-M failure. The main subject of this paper is to convert user histories of events to T vs. time traces, which can be used as inputs for T-M modeling.New data was acquired for this work because previous user behavior studies [5,6] did not provide the detailed usage vs.

No abstract