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Minimum Oxygen Content Carrier Gas for POCl(3) Deposition Process

IP.com Disclosure Number: IPCOM000074094D
Original Publication Date: 1971-Mar-01
Included in the Prior Art Database: 2005-Feb-23
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Kerr, DR: AUTHOR [+2]

Abstract

A carrier gas consisting of a mixture of oxygen and nitrogen is used in the deposition of phosphosilicate glass (PSG) passivation of field-effect transistor gates. Typically, the carrier gas consists of 9% oxygen and 91% nitrogen. Although oxygen is required for reaction with POCl(3) in the PSG process, it also is responsible for the creation of undesirable oxide charge at the silicon-silicon dioxide interface of the FET gate structure. The oxide charge build-up necessitates a high-temperature anneal to reduce the oxide charge. Unfortunately, the high-temperature anneal is responsible for a lowering of the sodium blocking ability of the phosphosilicate glass passivation.

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Minimum Oxygen Content Carrier Gas for POCl(3) Deposition Process

A carrier gas consisting of a mixture of oxygen and nitrogen is used in the deposition of phosphosilicate glass (PSG) passivation of field-effect transistor gates. Typically, the carrier gas consists of 9% oxygen and 91% nitrogen. Although oxygen is required for reaction with POCl(3) in the PSG process, it also is responsible for the creation of undesirable oxide charge at the silicon-silicon dioxide interface of the FET gate structure. The oxide charge build-up necessitates a high-temperature anneal to reduce the oxide charge. Unfortunately, the high-temperature anneal is responsible for a lowering of the sodium blocking ability of the phosphosilicate glass passivation.

Sodium resistance is improved, while other properties of the phosphosilicate glass stabilization process are maintained within desired limits by significantly reducing the oxygen content of the carrier gas for the POCl(3). An oxygen fraction of 0.2 to 2% in the nitrogen-oxygen carrier gas mixture, together with an increased POCl(3) concentration and increased deposition time, increases the amount of phosphosilicate glass deposited while decreasing the oxide charge build-up at the silicon-silicon dioxide interface of the FET gate structure. The reduced charge build-up, in turn, permits a reduction in the temperature of the annealing step with a concomitant decrease in the amount of phosphorus outdiffusion (thus maintaining sodium bl...