Pad debris

Typically, slurry residues are due to strong adhesion of some abrasive particles to the oxide surface of the wafer. For some more complex slurry formulations, it is possible to leave organic residues [32,33] on the wafer surface as well. In some rare cases, it is also possible to leave pad residues, pad debris on the wafer surface, especially when an improper pad break-in procedure is combined with an inadequate post-CMP cleaning. Figures 17.8 and 17.9 show some representative residues on a polished oxide surface. 

Figure 17.5 PR and FM defects from CMP consumables (a) alumina abrasives (b) silica abrasives (c) ceria abrasives (d) organic residue (e) pad debris.

Pad debris caused by polishing and wearing can be another type of consumable-related FM and PR as shown in Figure 17.5(e). The surface pore structure is visible under scanning electron microscope (SEM). Such pad debris are more prevalent in the case where soft polishing pads are used in conjunction with in situ or ex situ conditioning. Most CMP polishing pads are made of polymeric material such as polyurethane. As a result, in-line SEM and EDAX with elemental spectra alone would not yield sufficient information to identify the PR as pad debris. A more subtle off-line analytical technique such as Raman spectroscopy or Fourier transform infrared spectroscopy is required to determine the chemical components [6]. 

W.-T. Tseng, E. Rill, B. Backes, M. Chace, Y. Yao, P. DeHaven, A. Ticknor, V. DevarapaUi, M. Khojasteh, D. Steber, L. Economikos, C. Truong, C. Majors, Post Cu CMP cleaning of polyurethane pad debris, ECS J. SoUd State Technol. 3 (1) (2014) N3023-N3031. 

Unsecured objects, such as bricks and gas cylinders, near the edges of elevated surfaces, such as catwalks, roof tops, and scaffolding, which may dislodge and fall on workers Debris and weeds that obstruct visibility Install skid-resistant strips and other antiskid devices on slippery surfaces Construct operation pads for mobile facilities and temporary structures Construct loading docks, processing and staging areas, and decontamination pads... 

To provide channels for the removal of polishing debris and heat from the pad surface so as to reduce the possibility of scratch and generation of other defects due to the debris accumulation on the pad surface and to avoid rapid chemical reaction at localized high temperature regions due to frictional and chemical reaction heat ... 

During STI and oxide CMP, defects can come from sources such as oversized particles, polishing debris, diamond particles from the pad conditioner, and particles trapped in the polishing pad. In addition to the techniques discussed in this chapter, could you think of additional solutions for the reduction of these defects ... 

The problem of gas traps also exists in posts and bosses. In the case of a post which is trapping gas, the usual solution is to place an ejector pin on the post similar to the one used for the ejector pin pad on the rib. Bosses use a core pin that is stationary to create the hole. While the core pin can be modified to create a vent, that vent will be stationary and can plug with debris in time. That can require a more expensive solution the use of an ejector sleeve around the core pin which then has to be fixed to the bottom plate of the mold base. 

Pad number Range (real) (m) Azimuth (deg) Debris density (kg/ra ) Debris density (p-/m2) Factor L Range (corr.) (m)... 

Figure 10.4 Comparison of recovery by 3 heated head-space enrichment methods. Sample Fire debris sample, gasoline on a charred matrix of carpet and carpet padding (Instrument 1). Top SPME, Car-boxen/PDMS fiber (70°C, 3 min extraction). Middle Static headspace enrichment (90°C,...

Debris recovered from the fire scene is often wet and burned, and may consist of material such as wood, carpet, carpet padding, tile, and other synthetic materials, all of which can contribute interfering volatile pyrolysis products that can make the identification of the accelerants difficult. The loss of accelerants through adsorption into the debris, evaporation from the heat of the blaze, and the presence of water all contribute to make the identification of accelerants a challenging task. GC can be a powerful tool in the analysis to separate and identify the accelerant in the presence of these interferences. Fultz and DeHaan have written an excellent chapter on GC in arson and explosive analysis (156). 

Ankle abscesses, which are more common in patients with diabetes mellitus, atherosclerosis and osteomyelitis of the calcaneus, present as soft-tissue collections of purulent fluid surrounded by inflamed tissue. In general, US shows a well-defined lesion characterized by a heterogeneous appearance due to the coexistence of fluid and debris, ranging from hypoechoic to hyperechoic (Lover et al. 1996 Pham et al. 2003). Swirling fluid in the abscess can be seen with probe compression. In addition, the inflammation associated with the disease process can lead to hyperemic walls of the abscess at Doppler imaging. Pericalcaneal soft-tissue spaces, the heel fat pad and the Kager fat space are most often involved (Fig. 16.95) (Ly and Bui-Mansfield 2004). 

The CO2 functions to deliver the gas to flies and to keep them anesthetized while being examined or handled. The plate is normally a shallow vessel that sits on the microscope stage. Gas is passed into this vessel and escapes through the surface of the plate, which is constructed of a white porous material, typically sintered glass or porous polyethylene. (If the surface of the CO2 pad becomes clogged with the debris of dead flies it can be cleaned with sandpaper.) Plates can be purchased from fly equipment suppliers or constructed from Perspex by a competent workshop technician. Post a large notice— HAVE YOU TURNED THE GAS OFF — that is visible to all as they leave the fly room. 

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