Punch-through-stop

Fig. 14.6. Application of ion implantations in advanced CMOS structure at several stages of the process, (a) Ion implants for retrograde well formation, punch-through-stop, and threshold voltage adjust (b) shallow source/drain (S/D) implant and (c) halo implant...

Figure 6-5 illustrates three methods of arranging the film strip. The small sketches on the right show the loaded film in relation to the incident beam, while the films laid out flat are indicated on the left. In (a), a hole is punched in the center of the film so that the film may be slipped over the beam stop the transmitted beam thus leaves through the hole in the film. The pattern is symmetrical about the center, and the 0 value of a particular reflection is obtained by measuring U, the distance apart of two diffraction lines formed by the same cone of radiation, and using the relation... 

The 0.7 value is a typical orifice coefficient which will vary with plate thickness and whether the hole was punched or drilled. If APL is smaller than the expected out of levelness of the plate, vapor will start to bubble up through the orifice holes on the high point of the plate, and the reflux flow will stop in that section of the plate. 

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