Results 1 - 10 of 2092
Results 1 - 10 of 2092. Search took: 0.026 seconds
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[en] Several techniques to predict pad failure during tungsten CMP were investigated for a specific consumable set. These techniques include blanket polish rate measurements and metrics derived from two endpoint detection schemes. Blanket polish rate decreased significantly near pad failure. Metrics from the thermal endpoint technique included change in peak temperature, change in the time to reach peak temperature, and the change in the slope of the temperature trace just prior to peak temperature all as a function of pad life. Average carrier motor current before endpoint was also investigated. Changes in these metrics were observed however these changes, excluding time to peak process temperature, were either not consistent between pads or too noisy to be reliable predictors of pad failure
[en] Distribution forms of abrasives in the chemical mechanical polishing (CMP) process are analyzed based on experimental results. Then the relationships between the wafer, the abrasive and the polishing pad are analyzed based on kinematics and contact mechanics. According to the track length of abrasives on the wafer surface, the relationships between the material removal rate and the polishing velocity are obtained. The analysis results are in accord with the experimental results. The conclusion provides a theoretical guide for further understanding the material removal mechanism of wafers in CMP. (semiconductor technology)
[en] This paper details the analysis of vibration monitoring for end-point control in oxide CMP processes. Two piezoelectric accelerometers were integrated onto the backside of a stainless steel polishing head of an IPEC 472 polisher. One sensor was placed perpendicular to the carrier plate (vertical) and the other parallel to the plate (horizontal). Wafers patterned with metal and coated with oxide material were polished at different speeds and pressures. Our results show that it is possible to sense a change in the vibration signal over time during planarization of oxide material on patterned wafers. The horizontal accelerometer showed more sensitivity to change in vibration amplitude compared to the vertical accelerometer for a given polish condition. At low carrier and platen rotation rates, the change in vibration signal over time at fixed frequencies decreased approximately ampersand frac12; - 1 order of magnitude (over the 2 to 10 psi polish pressure ranges). At high rotation speeds, the vibration signal remained essentially constant indicating that other factors dominated the vibration signaL These results show that while it is possible to sense changes in acceleration during polishing, more robust hardware and signal processing algorithms are required to ensure its use over a wide range of process conditions
[en] Defect centers generated in vacuum-ultraviolet irradiated chemical-mechanical polished oxides have been characterized using electron paramagnetic resonance and C-V analysis. Both oxide trap Eγ and interface trap Pb0 centers were detected in unpolished and polished oxides. In addition, another interface defect center known as the Pb1 center was only identified in the polished oxides, suggesting that the polishing process altered the SiO2/Si interface
[en] Niobium (Nb) is the most popular material that has been employed for making superconducting radio frequency (SRF) cavities to be used in various particle accelerators over the last couple of decades. One of the most important steps in fabricating Nb SRF cavities is the final chemical removal of 150 μm of Nb from the inner surfaces of the SRF cavities. This is usually done by either buffered chemical polishing (BCP) or electropolishing (EP). Recently a new Nb surface treatment technique called buffered electropolishing (BEP) has been developed at Jefferson Lab. It has been demonstrated that BEP can produce the smoothest surface finish on Nb ever reported in the literature while realizing a Nb removal rate as high as 10 μm/min that is more than 25 and 5 times quicker than those of EP and BCP(112) respectively. In this contribution, recent advance in optimizing and understanding BEP treatment technique is reviewed. Latest results from RF measurements on BEP treated Nb single cell cavities by our unique vertical polishing system will be reported.
[en] An observation on the relationship between stick-slip phenomena and chatter scratch generation during chemical-mechanical polishing (CMP) was made using finite element analysis. The motivation for this work is based on the questions about the possibility of the stickslip phenomena in the CMP process and the quantitative relation between the stick-slip behaviors and the formation characteristics of the scratch. The finite element simulation results showed that stick-slip friction could occur during CMP and it could be seen only in the case of the interactions with the particles trapped inside pad surface. Also, the stick-slip period increased with the density of interacting wafer surface material and the particle size had a significant effect on the stick-slip period and magnitude. It is expected that this work will aid the development of chatter scratch reduction technology.
[en] We demonstrate in this paper for the first time the use of conductive atomic force microscopy (AFM) to measure surface leakage between copper structures with varying line width and spacing in the micro and sub micrometer ranges. Conducting atomic force microscopy allows subsequent measurement of the topography as well as the electrical properties of surfaces. The feasibility and interest of these measurements will be shown by studying the impact of chemical mechanical polishing (CMP) of an electrical interface bearing different micrometric copper structures. As expected the polishing time has a crucial impact on the current determined between closely spaced copper structures. This paper will also deal with issues observed during the measurement
[en] Chemical-mechanical polishing of n-PbTe and n-Pb/sub 1-x/Sn/sub x/Te crystals (x approximately 0.2) with a solution containing potassium hexacyanoferrate (III), sodium hydroxide, glycerol or ethylenglycol has been studied varying the process parameters, such as support pressure, duration, rotation rate of the polishing disk and NaOH concentration. It was found that the solution can be applied. Mirror-like surfaces were obtained
[en] Three instruments measuring the quality of mirrors used in high-energy laser applications are described: an optical instrument employing a Coblentz sphere for scattering and reflectance measurements at a whole series of laser wavelengths; a polarization-modulated ellipsometer; and an interferometric surface scanner. Factors reducing mirror reflectivity are discussed and the development of the bowl-feed polishing technique which leads to the reduction of surface irregularities is described. (U.S.)