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Gettering and Barrier Technique

IP.com Disclosure Number: IPCOM000086871D
Original Publication Date: 1976-Nov-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 63K

Publishing Venue

IBM

Related People

Beyer, KD: AUTHOR [+3]

Abstract

Fig 1 shows a cross section of a standard processed semiconductor wafer 5 having a silicon dioxide coating 6. The wafer is now subjected to a vapor hydrofluoric acid (HF) etch rather than conventional liquid HF or buffered HF etch to remove all the oxide.

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Gettering and Barrier Technique

Fig 1 shows a cross section of a standard processed semiconductor wafer 5 having a silicon dioxide coating 6. The wafer is now subjected to a vapor hydrofluoric acid (HF) etch rather than conventional liquid HF or buffered HF etch to remove all the oxide.

Fig. 2 illustrates one embodiment of the vapor HF etching process. The SiO(2) etch rate is approximately 1500 Angstroms/min. in the vapor. This is comparable to the buffered HF solutions now used.

A unique "seal" between the beaker 7 and the wafer 5 occurs. The surface tension between the two is sufficient to create a liquid barrier. This eliminates the HF vapor from creeping beyond the beaker dimension.

Epitaxial silicon is now grown on the wafer in the standard manner. The dielectric coating on the wafer back prevents or reduces impurities associated with the susceptor from getting into the wafer.

As the epi is deposited, a poly epi (highly disordered) layer 8 (Fig. 3) is grown over the dielectric "ring". This region now has the capabilities of "gettering" during the remaining epi cycle and further hot processing cycles. If the "ring" is, for example, 1/8", approximately 20% of the 2 1/4" wafer will have gettering capabilities in the edge region which requires it the most. This ring dimension can be altered for any pattern structure on the wafer.

The wafer is now processed according to standard procedures. The poly epi can be extensively oxidized during a subsequent oxidation pr...