US 6,686,260 B2Granted

Process for producing thermally annealed wafers having improved internal gettering

AssigneeMEMC Electronics Materials, Inc.

InventorsRobert J. Falster, Martin Jeffrey Binns, Harold W. Korb

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Abstract

A process for heat-treating a single crystal silicon wafer to dissolve agglomerated vacancy defects and to influence the precipitation behavior of oxygen in the wafer in a subsequent thermal processing step. The process includes subjecting the wafer to a heat treatment to dissolve agglomerated vacancy defects, rapid thermally annealing the heat-treated wafer to cause the formation of crystal lattice vacancies throughout the wafer and controlling the cooling rate of the annealed wafer to allow some, but not all, of the crystal lattice vacancies to diffuse to the front surface to produce a wafer having a nonuniform vacancy concentration with the concentration of vacancies in the bulk of the wafer being greater than the concentration in the surface layer.

Claims30

Dependent claims

A process for heat-treating a single crystal silicon wafer to dissolve agglomerated vacancy defects and to influence the precipitation behavior of oxygen in the wafer in a subsequent thermal processing step, the silicon wafer having two major, generally parallel surfaces, one of which is the front surface of the wafer and the other of which is the back surface of the wafer, a central plane between the front and back surfaces, a circumferential edge joining the front and back surfaces, a stratum extending from the front surface to a distance, Ds, measured from the front surface and toward the central plane, a surface layer which, at least in part is coextensive with the stratum and which comprises the region of the wafer between the front surface and a distance, D, measured from the front surface and toward the central plane, and a bulk layer which comprises the region of the wafer between the central plane and the surface layer, the process comprising:

thermally annealing the wafer in an atmosphere to dissolve pre-existing agglomerated vacancy defects in the stratum;
heat-treating the annealed wafer to form crystal lattice vacancies in the surface and bulk layers;
and,
controlling the cooling rate of the heat-treated wafer to produce a wafer having a vacancy concentration profile in which the peak density is at or near the central plane with the concentration generally decreasing in the direction of the front surface of the wafer, the difference in the concentration of vacancies in the surface and bulk layers being such that a thermal treatment of the wafer at a temperature in excess of 750° C. is capable of forming a denuded zone in the surface layer and oxygen clusters or precipitates in the bulk layer with the concentration of the oxygen clusters or precipitates in the bulk layer being primarily dependant upon the concentration of vacancies.

1 more element

A process for heat-treating a single crystal silicon wafer to dissolve agglomerated vacancy defects and to influence the precipitation behavior of oxygen in the wafer in a subsequent thermal processing step, the silicon wafer having a front surface, a back surface, a central plane between the front and back surfaces, a stratum extending from the front surface to a distance, Ds, measured from the front surface and toward the central plane, a surface layer which, at least in part, is coextensive with the stratum and which comprises the region of the wafer between the front surface and a distance, D, measured from the front surface and toward the central plane, and a bulk layer which comprises the region of the wafer between the central plane and surface layer, the process comprising the steps of:

heat-treating the wafer in an atmosphere to form crystal lattice vacancies in the surface and bulk layers;
controlling the cooling rate of the heat-treated wafer to produce a wafer having a vacancy concentration profile in which the peak density is at or near the central plane with the concentration generally decreasing in the direction of the front surface of the wafer and the difference in the concentration of vacancies in the surface and bulk layers being such that a thermal treatment of the wafer at a temperature in excess of 750° C. is capable of forming a denuded zone in the surface layer and oxygen clusters or precipitates in the bulk layer with the concentration of the oxygen clusters or precipitates in the bulk layer being primarily dependant upon the concentration of vacancies;
stabilizing oxygen precipitate nucleation centers present in the cooled wafer by heating the cooled wafer to a temperature of about 650 to about 850° C. for about 1 hour to about 4 hours;
and,
thermally annealing the stabilized wafer in an atmosphere to dissolve agglomerated vacancy defects present within a region extending from the front surface to a depth of at least about 5 microns.

2 more elements

Dependencies are inferred from the claim text.

Facts

Application: 10/067,070Filed 4 Feb 2002 · division
Priority: 2 Sep 1998
Published: US 2002/0170631 A121 Nov 2002
Granted: 3 Feb 2004
Term ends: Not estimatedThe source records don’t support an estimate.

Classification2 codes

H10P 36/20
Gettering within semiconductor bodies: intrinsic gettering, i.e. thermally inducing defects by using oxygen present in the silicon body
H10P
Generic processes or apparatus for the manufacture or treatment of devices covered

Family

Application60/098,921Us provisional application · filed 2 Sep 1998
Application09/385,108Parent of this division · filed 27 Aug 1999
US 2002/0170631 A1Pre-grant publication · published 21 Nov 2002
US 6,361,619 B1Parent of this division
US 6,686,260 B2This patent

From the US filing history. Foreign family members aren’t listed.