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Pad compressibility

Polster, n. ciishion padding pad compress, Polsterung,/. upholstery padding. [Pg.344]

Additionally, on a more local level between two structures, again due to pad compressibility, polishing of the isolation area starts earlier than in the ideal case (Fig. 12.10, B), before the initial step is reduced to zero. This slows down the planarization rate after this point (B and C) and, generally, planarity is not reached at the moment the nitride layer is exposed (C). During the overpolishing step, the polishing rate of the active areas is reduced because of the nitride stop layer, but is nevertheless different from zero, especially near the... [Pg.354]

Pad Compressibility Units of (%). Pad compressibility affects how the pad conforms to the wafer surface. For planarization, the pad should not contact the low regions and thus should not be conformal, hence low compressibility is desirable for planarization. To obtain good across wafer uniformity in the polish rate, however, the pad must contact the uniformly across the wafer... [Pg.44]

Pad Thickness Units of (pm) or (mils). Pad thickness is related to compressibility. The thicker the pad, the more the pad compresses to conform to the surface. Pad thickness must be balanced to obtain optimum planarity and uniformity, as discussed above. Since pad conditioning (see Chapter 4) has become essential, the choice of pad thickness, with pad conditioning and life in mind, becomes an important COO issue. [Pg.45]

The model by Warnock uses the notion that planarity is a function of pad compression to predict planarization. Figure 5.28 illustrates the compression of a pad as it transverses the edge of a step in the wafer surface. The effect of the high region is to shade the adjacent low region from the pressure exerted by the pad. By modeling the pad response to the presence of a step (i.e., the pressure redistribution along the step), Wamock predicts the relative polish rates at each point on the surface. [Pg.160]

This model implicitly assumes that, at least to some extent, the pad makes contact with the wafer surface (i.e., the pad directly presses the abrasive against the surface) and exerts pressure directly to the surface. The abrasive then moves across the surface as a Hertzian indenter. As discussed in Chapter 4 however, it is also possible that a continuous fluid layer exists between the wafer and the pad. The pad compresses the fluid layer, which in turn exerts hydrodynamic pressure on the surface. The existence of a hydrodynamic fluid layer is an important distinction because the wear mechanisms are different for fluid-based wear as opposed to Hertzian indenter-based wear (see Chapter 4). [Pg.163]

By modifying the parameters in Equation (7.15), the effect of both pad compressibility and roughness may be taken into account. The pad is compressed as it pushes against the wafer as it rides over a recess, some of the compression is relieved. Consequently, the entire thickness of the pad does not deform. A near surface effective thickness / < /, the pad thickness, should therefore be used to account for pad compression. Indeed, if values of L = 10 pm, w = PL = 150 kPa-pm and E = 40 GPa are used with the pad thickness of r = 1.25 mm (specified by the manufacturer), a value of y = 10 pm is obtained for the deflection of the pad. However, if due to pad compression, only a near surface layer of thickness / = 1.8 pm is assumed to bend, then the deflection of the pad is equal to 100 nm, which is more in line with the dishing seen in Figme 7.32. [Pg.261]

Fig.2 shows the characteristics of planarity depending on oxide removal on upper area. The space width is 1000 M m in this case. The grinding shows the excellent planarization and almost same as the ideal curve. But CMP shows poor planarization and lOOOA of step remains after 700nm of oxide removal. Fig.3 (a) and Fig.3 (b) show the profile of the oxide surface. CMP case, not only the oxide on upper area but also the oxide on lower area is removed after the step becomes small. Because of the pad compressivity, the pad surface reached the... [Pg.20]

Polymers can be used in many mechanical applications and a few of these are bearings, gears, valves, pumps, bushes, sprockets, diaphragms, wear pads, compression rings. [Pg.2]

CVJ boots (207) conductive mbbers (208) energy management devices (207) compression spring pads (206) gun holsters (177) mn- at tire inserts (207)... [Pg.305]

A mode curve exhibiting this shape could indicate that the motor mountings, or the baseplate under the motor, are loose and that the motor is moving vertically. In fact, in the example from which this figure was taken, this is exactly what was happening. The blower s baseplate floats on a one-inch thick cork pad, which is normally an acceptable practice. However, in this example, an inlet filter/silencer was mounted without support directly to the inlet located on the right end of the machine. The weight of the filter/silencer compressed the cork pad under the blower, which lifted the motor-end of the baseplate off of the cork pad. In this mode, the motor has complete freedom of movement in the vertical plane. In effect, it... [Pg.731]

We prepare force versus compression plots in a similar fashion to force versus elongation plots. We generally perform compressive testing over a much more limited range of strain than tensile testing. Samples typically take the form of thick pads, which do not break in the same manner as tensile specimens. The limit of compressive strain can approach 100% for low density foams, but is much less for other samples. The most common property that we obtain from this mode of testing is compressive modulus. [Pg.163]

The samples most commonly tested in compression are foams and rubbers, which experience compressive forces during use. Very often, the polymer foams that experience compression are not readily visible to us, even though they are all around. Polymer foams are widely used in carpet underlay, upholstery, shoe insoles, backpack straps, bicycle helmets, and athletic pads. Solid rubbers are much more visible, including automobile and bicycle tires, gaskets and seals, soft keys on calculators, and shoe soles. [Pg.163]

The filter pad was prepared by compressing Celite (4 cm) onto a layer of sand (1.5 cm) in a fritted glass funnel (10-cm diameter). [Pg.13]


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See also in sourсe #XX -- [ Pg.33 , Pg.53 , Pg.125 , Pg.130 , Pg.353 , Pg.354 , Pg.355 ]

See also in sourсe #XX -- [ Pg.46 , Pg.261 ]




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Padding

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