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The mechanical properties of chemical-mechanical planarization (CMP) pads are very important to their performance. In this paper, pads are described in terms of their bulk properties and the properties of their asperity layer for applications in copper CMP. In particular, the elastic properties of these layers are studied. Pads were soaked in a copper polishing slurry or water for specified times and changes in their elastic moduli were measured. In general, pad immersion in water reduced the bulk modulus because the water penetrated the pads and disrupted hydrogen bonds between adjacent polyurethane chains. In addition, it was found that surface grooving affected the pad elastic modulus, especially that of the asperity layer. To evaluate the effect of use in copper CMP on the pad properties, the elastic moduli of the bulk and asperity layers on a pad were measured following pad use in a commercial polisher. The periodic loads during CMP were believed to facilitate the penetration of water into the pads, lowering their bulk elastic moduli. A slight increase in the elastic modulus of the asperity layer was seen as a result of pad use in copper CMP. The inherent variations in modulus measurements for dry pads were also measured. Index Terms--Chemical-mechanical planarization (CMP), CMP pad, elastic modulus, groove effect, statistical analysis.

Two mycocardial infarction biomarkers, myoglobin (MG) and cardiac troponin I (cTnI), were quantified at biological levels and in undiluted serum without sample pretreatment using surface plasmon resonance (SPR) sensors. To achieve detection of biomarkers in undiluted serum (72 mg/mL total protein concentration), minimization of the nonspecitic signal from the serum protein was achieved by immobilizing the antibody for the biomarkers on an N-hydroxysuccinimide activated 16-mercaptohexadecanoic acid self-assembled monolayer. This monolayer reduces the nonspecific signal from serum proteins in such a manner that short exposure of the sensor to serum prior to analysis prevents any further nonspecific adsorption during analysis. Thus, sensing of MG and cTnI was achieved on the basis of the difference between signals from the active sensor and a reference sensor that captured background interference. This resulted in direct measurement of these biomarkers in undiluted serum. Detection limits for both markers were below 1 ng/mL, which is below the threshold needed to detect myocardial infarction. Detecting biomarkers in the low ng/mL range without signal amplification in such a complex matrix as serum corresponds to a selectivity of [10.sup.8]. The root-mean-square-error (RMSE) of calibration was below 2 ng/mL.

Sensing of three cytokines related to chronic wound healing, interleukin-1 (IL-1), interleukin-6 (IL-6), and tumor necrosis factor-a (TNF-[alpha]), with detection limits at or below 1 ng/mL in buffered saline solution and spiked cell culture medium (CCM) has been achieved. Fiber-optic surface plasmon resonance (SPR) sensors are coated with an antibody binding layer and antibodies specific to the cytokine of interest are covalently attached to this layer. To achieve such detection limits in a complex medium such as CCM, total protein content of 4 mg/mL, the use of a novel N-hydroxysuccinimide ester of 16-mercaptohexadecanoic acid (NHS-MHA) is necessary. A comparison of the detection limits for IL-6 using currently widely used CM-dextran and NHS-MHA shows an improvement by a factor of 3 using NHS-MHA. The detection limits for the monitoring of cytokines in spiked saline solutions and CCM were similar for TNF-[alpha] and slightly higher for IL-1 and IL-6. The detection of each cytokine in the presence of interfering agents resulted in concentration prediction well within the error of calibration. The SPR sensors are stable in CCM after 20 min of pretreatment in CCM, minimizing the reliance on a reference sensor to quantify the cytokines in complex media. This technique enables a major advancement in the field of real-time monitoring of biologically relevant molecules in complex biological fluids.