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Deposition of Phosphosilicate Glass Layers Having Uniform Thickness and Dopant Concentration Onto Semiconductor Substrates

IP.com Disclosure Number: IPCOM000047206D
Original Publication Date: 1983-Oct-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 2 page(s) / 20K

Publishing Venue

IBM

Related People

Hottin, C: AUTHOR [+3]

Abstract

Typical open-tube diffusion processes involve gas reactions in the tube to form a doped glass which deposits on the wafers. Gas reactions are: O2 + BBr3 for boron-doped glass, O2 + POCl3 for phosphorous-doped glass. The reacting gases are carried into the tube via a carrier gas (typically, argon). A typical diffusion process sequence involves three phases: I Furnace recovery and temperature equilibrium with: Ar carrier gas + O2 No source (BBr3 or POCl3) II Doped glass deposition: Ar carrier gas + O2 Source (BBr3 or POCl3) III Drive in: Ar carrier gas + O2 It is assumed that the small oxygen flow rate during phase I is enough to form a small nonuniform layer of oxide onto the wafers which, in turn, results in non-uniform thickness and doping of the doped glass layer.

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Deposition of Phosphosilicate Glass Layers Having Uniform Thickness and Dopant Concentration Onto Semiconductor Substrates

Typical open-tube diffusion processes involve gas reactions in the tube to form a doped glass which deposits on the wafers. Gas reactions are:

O2 + BBr3 for boron-doped glass,

O2 + POCl3 for phosphorous-doped glass. The reacting gases are carried into the tube via a carrier gas (typically, argon). A typical diffusion process sequence involves three phases: I Furnace recovery and temperature equilibrium with:

Ar carrier gas + O2

No source (BBr3 or POCl3)

II Doped glass deposition:

Ar carrier gas + O2

Source (BBr3 or POCl3)

III Drive in:

Ar carrier gas + O2 It is assumed that the small oxygen flow rate during phase I is enough to form a small nonuniform layer of oxide onto the wafers which, in turn, results in non-uniform thickness and doping of the doped glass layer. Probably, eliminating the oxygen flow during phase I suppresses the formation of this non-uniform oxide layer. It has been demonstrated that delaying introduction of the oxygen until phase II takes place, considerably improves the process. Various experiments have been carried out on POCl3 diffusions, and very accurate and reproducible sheet resistivities were obtained. Also, because of the better glass uniformity, the lifetime of the POCl3 container has been increased. With standard processing, Rs started shifting as soon as the level of POCl3 in the container was half the maximu...