Silicon processing

Li, S. H. and Miller, R., Chemical Mechanical Polishing in Silicon Processing, Semiconductor Semimet., Vol. 63, New York Academic Press, 2000. 

At present, defect-free silicon crystals have been achieved at only at diameters of 200 mm. Comparisons of crystal quality were made among three techniques a typical conventional Czrochralski crystal growth technique, a slow-cooled controlled reaction and the perfect silicon process. The quality levels achieved in D-defect levels of the material is... 

This process contrasts with the elemental-silicon processes sometimes used for alkyl silicates (8) and the elemental-silicon processes generally used for oligomeric and polymeric organosi-loxanes ( ,7) Since the silicon in these processes is obtained from quartz, these processes entail, in terms of bond cleavage, the destruction of four silicon-oxygen bonds per silicon and the subsequent reformation of the required number of such bonds. In terms of oxidation number, they entail the reduction of the silicon from four to zero and then its reoxidation back to four, Figures 2 and 3. 

Figure 2. Variation of oxidation number of silicon with step and variation of number of oxygens bonded to silicon with step in direct or elemental-silicon process for (EtOJ Si.

Silicone process oils mixed with liquid chlorine confined in a stainless steel bomb reacted explosively on heating polydimethysiloxane at 88-118°C, and poly-methyltrilluoropropylsiloxane at 68-114°C. Previously, leakage of a silicone pump oil into a liquid chlorine feed system had caused rupture of a stainless steel ball valve under a pressure singe of about 2 kbar. 

Before the invention of the planar transistor, many photoresist processes were developed for the manufacture of circuit boards. Experience gained in this area was rapidly transferred to silicon processing, and much of the early work in integrated circuit lithography can be traced directly to circuit board manufacturing. 

In reflectometry, the light passes through the films to be measured. Beneath the transparent films, there must be an opaque substrate through which light does not pass. The substrate characteristics must be modeled correctly to calculate the thicknesses of the films above. In silicon processing, theoretically, any of the commonly used metal materials, such as the titanium nitride (TiN), aluminum (Al), and tungsten (W), can be used as substrates. However, in reality, whereas a PMD oxide can be measured on the polysilicon material used in poly interconnections, an ILD oxide can not be measured directly on TiN, because the TiN layer used is too thin to be opaque. TiN is semitransparent if its thickness is less than 1000 A. A thin... 

Four-point probe is the most commonly used method to measure sheet resistance for metal films in silicon processing. Given known resistivities of each material, the film thickness can be obtained. Table VI lists the resistivities for the films often used in the back-end interconnect processes. The theory in four-point prohe originally comes from Ohm s law ... 

S. Wolf, Silicon Processing for the VLSI Era (Volume 2, Process Integration, Lattice Press, Sunset Beach, CA, 1990) p. 186. 

Figure 7.39 Process sequence used to form silicon wafer electronic substrates. Reprinted, by permission, from S. Wolf and R. N. Tauber, Silicon Processing for the VLSI Era, Vol. 1, p. 6. Copyright 1986 by Lattice Press.

Various mixtures of wet chemical acid solutions are used in plastic baths in locally exhausted etch stations. The primary acids in use are sulfuric hydrofluoric, hydrochloric and phosphoric. As in silicon processing, hydrogen peroxide used with sulfuric acid and ammonium hydroxide (NH OH) provides a caustic etch. 

Strausscr. Y.E. Characterization in Silicon Processing. B utter worth-Hcincm ann. Inc, Woburn, MA, 1993. 

The Role of Point Defects in Silicon Processing. The Balancing Act in Silicon Processing. Both silicon oxidation and the diffusion of impurities occur at high temperatures and involve point defects such as va-... 

Figure 8. The point defect balancing act in silicon processing. (Reproduced with permission from reference 118. Copyright 1988 Noyes Publications.)...

Wolf S, Tauber RN (1986) Silicon processing, vol 1. Lattice, Sunset Beach, CA... 

S. Wolf, R.N. Tauber, Silicon processing for the VLSI era, Sunset Beach, CA Lattice Press (2000). 

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