The effects of slurry pH, hydrogen peroxide (H2O2) concentration, and their interactions on a thick Cu chemical mechanical planarization (CMP) process for through-water interconnect (TWI) applications were investigated using a two-level full factorial design of experiment. Four permutations of high and low levels of slurry pH and H2O2 were investigated to determine the level of impact or significance on the CMP process. At constant machine parameters and pad types, significant changes in removal rate and within-wafer-nonuniformity (WIWNU) were observed based on the different slurry combinations used during the CMP process. Although slurry pH and H2O2 concentration were observed to be the dominant main effects on the CMP process, the interaction between the two variables was also found to have a significant impact on the average removal rate of Cu and WIWNU during CMP. Based upon a direct correlation between the type of Cu species formed and the level of H2O2 concentration in the slurry, the pH and H2O2 concentration of the slurry should be carefully formulated to obtain optimal results for TWI fabrication. The interaction plots between slurry pH and H2O2 concentration also provide a possible optimization level to achieve the maximum copper removal rate while minimizing WIWNU

Existing methods for the detection and measurement of volatile organic compounds (VOCs) in the vadose zone are often hampered by issues associated with ease of use, accuracy, and cost. As a result, there remains a need for inexpensive, minimally invasive, real-time instrumentation and sensor systems that can be used for characterizing or long-term monitoring of contaminated sites. A new sensor system to meet this need is under development at Boise State University, in collaboration with Washington State University. A miniature Ion Mobility Spectrometer (IMS) has been fabricated from a machinable ceramic material and has been shown to have a resolving power comparable to a commercial IMS. The IMS system will be packaged in a probe housing for deployment using direct push methods and will be ultimately equipped with water content, temperature, and pressure sensors. The proposed system is designed for use in multi-probe arrays and features wireless transmission of data directly to the user. To our knowledge, an in-situ IMS for detection of subsurface gaseous VOCs has not been previously developed. VOCs in Unsaturated Soils If a VOC enters unsaturated soil as a result of a spill, it can be present in four different phases: gas (air), water, solid (soil), and as a free phase liquid. Partitioning

Recent studies have been conducted investigating the effects of slurry chemistry on the copper CMP process. Slurry pH and hydrogen peroxide concentration are two important variables that must be carefully formulated in order to achieve desired removal rates and uniformity. In applications such as throughwafer vertical interconnects, slurry chemistry effects must be thoroughly understood when copper plating thicknesses can measure up to 20 microns thick. The species of copper present on the surface of the wafer can be controlled through formulation of the slurry chemistry resulting in minimizing non-uniformity while aggressively removing copper.Using a design of experiments (DOE) approach, this study was performed investigating the interaction between the two variables during CMP.Using statistical analysis techniques, a better understanding of the interaction behavior between the two variables and the effect on removal rate and uniformity is achieved.

A fast and reproducible isothermal gas chromatographic-mass spectrometric method for validating a small ion mobility spectrometer (IMS) sensor for detection of gaseous volatile organic compounds (VOCs) is presented. This method utilizes an automated cyclic valving (CV) sampling technique coupled to a gas chromatographmass spectrometer (GC/MS) in selected ion monitoring (SIM) mode (CV/GC/MS/ SIM). The sampling time is considerably reduced by operating the GC isothermally at 3008C. This approach provides rapid measurements with 15 times more data points than the conventional GC/MS methods in which the column temperature is ramped, then cooled before the next sample can be injected. With the mass spectrometer operated in SIM mode, pre-selected ions that represent the primary quantitation and secondary ions of toluene and a BTX (benzene, toluene, o-, m-, and p-xylene) mixture were monitored and their corresponding breakthrough curves for flow through partially saturated soil columns were generated. The small variation in measured steady state mean concentrations (SSMC) from run to run demonstrates the reproducibility of this new method. A comparison of the transient concentration profiles of toluene from a BTX mixture and toluene alone obtained under identical test conditions shows a linear correlation with R 2 ¼ 0.997. This result suggests that the new method can be used to analyze and quantify some mixtures of co-eluting gaseous analytes.

Abstract-Electro-plating methods currently used to deposit Cu in through-wafer interconnect applications result in the formation of a thick Cu layer with large amounts of topographical variation. In this paper, alternative methods for thick Cu removal are investigated using a two-step slurry CMP approach.