No abstract

Density, Pe, and neutron-porosity measurements made while drilling are extremely sensitive to the distance between the sensors and the borehole wall (standoff). To minimize these effects, an ultrasonic transducer is positioned collinearly with the nuclear sensors. Rapid pulsing of the transducer provides frequent measurements of the standoff. These measurements are used to average the nuclear data in a manner that emphasizes the smallest standoff data. This greatly improves the quality of the density, Pe, and neutron-porosity logs. Additionally, the standoff measurements are used to correct the neutron log for residual standoff effects. Measurements from the standoff transducer are also combined with those from two other ultrasonic transducers to obtain a high-resolution caliper log. Besides providing useful borehole information, the caliper readings are used to correct the nuclear measurements for hole-size effects. This new technology is illustrated with log examples from a variety of wells. One of the examples illustrates the effectiveness of an enhanced-vertical-resolution processing technique in identifying thin beds. Introduction Density and neutron porosity logging-while-drilling (LWD) measurements have been available for several years. However, accuracy often has been inferior to that obtained by wireline tools. The lower accuracy is primarily caused by rapid variations in sensor standoff from the borehole wall due to tool rotation. Although full-gauge density sleeves reduce standoff, they hinder drilling; and standoff still occurs when the borehole is enlarged. Refs. 1-3 describe statistical and orientational techniques for emphasizing nuclear data with small standoff. This paper illustrates another technique that directly measures standoff with an ultrasonic transducer. Weighted averages are used to emphasize nuclear data having the smallest standoff. This technique also utilizes a caliper measurement that is obtained from three ultrasonic transducers located at 1200 intervals around the tool. Field examples include a comparison of unweighted and weighted data processing, as well as a comparison of standoff-weighted results to wireline. Another example shows LWD logs obtained in a 9.875-in. borehole with a tool designed for 8.5-in. bits. Directionality of the nuclear readings also is illustrated. An example with heavy mud illustrates the value of two new density-correction curves. The final example shows logs with enhanced vertical resolution. Measurement Technique Fig. 1 shows two sizes of the Density-Neutron-Standoff-Caliper (DNSC) tool, The smaller size was designed for drilling with an 8.5-in. bit and the larger with a 12.25-in. bit. Both sizes measure density, photoelectric factor (Pe), neutron porosity, tool standoff, and borehole diameter (caliper). Data is processed and stored in nonvolatile tool memory. When a mud-pulser section is included, selected results are transmitted to the surface for real-time display. The DNSC tool also can be combined with resistivity and acoustic LWD-devices. Standoff Weighting. Nuclear data is acquired in 0.02-second intervals. During each interval, standoff of the nuclear sensors from the borehole wall is measured by an ultrasonic transducer using the pulse-echo method. Weighted averages are calculated from hundreds of nuclear data samples (Fig. 2), which typically correspond to 10 seconds. As shown in Fig. 3, the weight factors decrease exponentially with standoff, and range from 65,535 down to 1. This method yields nuclear counting rates characteristic of the smallest standoffs encountered during the averaging period.

This paper was prepared for presentation at the 1998 SPE International Conference on Horizontal Well Technology held in Calgary, Alberta, Canada, 1-4 November 1998.

We describe a process to selectively remove a preadsorbed 3-mercapto-1-propane-sulfonic acid accelerator from nonrecessed areas of a damascene Cu wafer by oxidation with aqueous O 3 , prior to electroplating. Topographically, selective oxidation was achieved by exploiting competition between diffusion-controlled heterogeneous reaction and homogeneous decay of O 3 in a thin, viscous, hydrated coating on the surface of the wafer. For wide recessed features ͑10-100 m͒, the resulting differential enhancement of Cu plating approaches a limit governed only by the activity of the accelerator-suppressor combination.The influence of substrate topography on electroplating is an important issue in the fabrication of electronic circuits. In the production of high-density integrated circuits as well as some printed wiring boards, a topographically patterned surface may first be covered with a thin Cu seed layer by means of vapor phase or electroless deposition. Cu plating is then used to thicken the recessed circuit features and to fill vertical interconnections between adjacent levels of circuitry. But in the course of plating, nonrecessed areas of the substrate surface, not intended to form part of the final circuit, are generally also exposed to the electrolyte and thus become coated with a comparable thickness of Cu. Subsequent polishing or etching is then required to remove the excess and/or to level the final surface. To minimize such postprocessing, methods have been sought to enhance Cu deposition on recessed features relative to nonrecessed areas. This requires overcoming the intrinsic tendency of concentration polarization and depletion to produce exactly the opposite effect.Refinements in the use and understanding of surface-active organic additives have played a major role in the development of microelectronics plating. 1,2 In particular, the chemadsorbed accelerator 3-mercapto-1-propane-sulfonic acid ͑MPS͒, in conjunction with certain polymeric suppressors catalyze the selective "superfilling" of submicron features with high aspect ratio ͑recess depth divided by width Ͼ1͒. 2,3 This phenomenon is understood to be due to a localized, progressive increase in MPS surface coverage as the surface area within the high-aspect-ratio features decreases. 4,5 As a consequence, these small recessed features become filled with Cu much faster than deposition on nonrecessed areas. However, the phenomenon is ineffective for filling wide recessed features, with aspect ratio Ͻ1, for which the decrease in surface area is negligible.Mechanical methods have been exploited as a means to selectively deposit Cu in nonrecessed areas, regardless of feature width. Wang et al., 6 Basol and West, 7 and Basol et al. 8 described an electrochemical-mechanical deposition process whereby the wafer is continuously polished with an abrasive pad during plating. By this means, recessed features were completely filled while minimizing Cu accumulation on nonrecessed areas. The greatest selectivity was obtained for wafers with preadsorbed accelerator 8 i...

The first Measurement While Drilling (MWD) devices were used in the late 1970s and gave only directional information during drilling. Since then, MWD technology has advanced rapidly, with recent developments making reliable Logging While Drilling (L WD) and Logging After Drilling (LAD) for formation evaluation a reality. This paper discusses the development of a new L WD foolstring that accurately measures numerous petrophysical parameters and gives useful drilling information in a timely manner. The new L WD toolstring furnishes a Triple Combination Suite of logs-namely, resistivity, density, and neutron with supporting gamma ray, caliper, and directional measurements. Tool development was based on studies that used computer simulation, test formation data, scale models, and information obtained from years of experience in MWD and wireline operations. The toolstring combines features from both MWD and wireline disciplines to optimize the measurements. Important features include: q Boreho/e-compensated resistivity, density and neutron measurements q Resolution-matched symmetrical resistivity measurements . q Placement of the density sensors behind a mudexcluder device to minimize borehole effects Ultrasonic standoff and caliper measurements A P, measurement for Iithology identificationThe caliper is a three-transducer ultrasonic device that provides both standoti and borehole geometry information used in correcting the other tool measurements for environmental effects. In addition, the caliper allows borehole volume to be calculated and helps identify and characterize interuals that cause drillpipe to stick. Several features of the MWDILWD toolstring help ensure smooth drilling operations. The downho/e shock indicator gives real-time warnings of critical bottomhole assembly (BHA) vibration. The tools have been designed to easily traverse doglegs and horizontal holes. Numerous safety features ensure the reliable containment of all nuclear sources when used in the LWD tools.The new MWD/L WD toolstring provides for integrating its data with drilling, geological, and wireline data as part of a system of continuous logging services. This enables comprehensive evaluation of downhole conditions fmm spud to well abandonment.