Memc Electronic Materials, Inc.

Robert A Falster

Joseph C Holzer

Paolo Mutti

Bayard K Johnson

Seamus A McQuaid

Steve A Markgraf

Massimiliano Olmo

Marco Cornara

Daniela Gambaro

The present invention relates to a process for growing a single crystal silicon. The process including controlling a growth velocity, v, and an average axial temperature gradient, G, during the growth of the constant diameter portion of the crystal over the temperature range from solidification to a temperature of no less than about 1325&#xb0; C., to cause the formation of a first axially symmetrical region in which vacancies, upon cooling of the ingot from the solidification temperature, are the predominant intrinsic point defect and which is substantially free of agglomerated intrinsic point defects, wherein the first axially symmetric region has a width of at least about 50% of the radius of the constant diameter portion of the ingot.

Vacancy, dominsated, defect-free silicon

The present invention relates to an epitaxial wafer comprising single crystal silicon substrate and an epitaxial layer deposited thereon. The substrate comprises an axially symmetric region which is free of agglomerated intrinsic point defects and wherein silicon self-interstitials are the predominant intrinsic point defect in the axially symmetric region. The present invention further relates to a process for producing such an epitaxial wafer.

Low defect density epitaxial wafer and a process for the preparation thereof

The present invention is directed to a process for producing a silicon wafer which, during the heat treatment cycles of essentially any arbitrary electronic device manufacturing process, may form an ideal, non-uniform depth distribution of oxygen precipitates and may additionally contain an axially symmetric region which is substantially free of agglomerated intrinsic point defects. The process including growing a single crystal silicon ingot from molten silicon, and as part of the growth process, controlling (i) a growth velocity, v, (ii) an average axial temperature gradient, G , during the growth of a constant diameter portion of the crystal over a temperature range from solidification to a temperature of no less than about 1325&deg; C., and (iii) a cooling rate of the crystal from a solidification temperature to about 1,050&deg; C., in order to cause the formation of an axially symmetrical segment which is substantially free of agglomerated intrinsic point defects. A silicon wafer is then sliced from the ingot, subjected to a heat-treatment to form crystal lattice vacancies in the front surface and bulk layers of the wafer and cooled at a rate sufficient to cause a non-uniform vacancy concentration profile in the wafer such that a thermal treatment at a temperature in excess of 750&deg; C., is capable of forming in the wafer a denuded zone in the front surface layer and oxygen clusters or precipitates in the bulk zone with the concentration of the oxygen clusters or precipitates in the bulk layer being primarily dependant upon the concentration of vacancies.

Process for producing low defect density, ideal oxygen precipitating silicon

The present invention relates a process for the preparation of single crystal silicon, which contains an axially symmetric region which is free of agglomerated intrinsic point defects. The process for growing the single crystal silicon including controlling the ratio v/G , where v is the growth velocity and G is the average axial temperature gradient during the growth of a constant diameter portion of the crystal over a temperature range from solidification to a temperature of no less than about 1325&deg; C., and a cooling rate of the crystal from a solidification temperature to about 1,050&deg; C., in order to cause the formation of an axially symmetrical segment which is substantially free of agglomerated intrinsic point defects. The control of V/G accomplished by controlling heat transfer at the melt/solid interface.

Low defect density, self-interstitial dominated silicon

The present invention relates to single crystal silicon, in ingot or wafer form, which contains an axially symmetric region in which vacancies are the predominant intrinsic point defect and which is substantially free of agglomerated vacancy intrinsic point defects, wherein the first axially symmetric region has a width which is at least about 50% of the length of the radius of the ingot, and a process for the preparation thereof.

Vacancy dominated, defect-free silicon

The present invention relates to single crystal silicon, in ingot or wafer form, which contains an axially symmetric region which is free of agglomerated intrinsic point defects, and a process for the preparation thereof. The process for growing the single crystal silicon ingot comprises controlling (i) a growth velocity, v, (ii) an average axial temperature gradient, G,, during the growth of a constant diameter portion of the crystal over a temperature range from solidification to a temperature of no less than about 1325&deg; C., and (iii) a cooling rate of the crystal from a solidification temperature to about 1,050&deg; C., in order to cause the formation of an axially symmetrical segment which is substantially free of agglomerated intrinsic point defects. This axially symmetric region extends inwardly from the circumferential edge of the ingot, has a width as measured from the circumferential edge radially toward the central axis of the ingot which is at least about three-tenths the length of the radius of the ingot, and has a length as measured along the central axis of at least about two-tenths the length of the constant diameter portion of the ingot.

Low defect density self-interstitial dominated silicon

A single crystal silicon wafer which, during the heat treatment cycles of essentially any electronic device manufacturing process, will form an ideal, non-uniform depth distribution of oxygen precipitates. The wafer is characterized in that is has a non-uniform distribution of crystal lattice vacancies, the concentration of vacancies in the bulk layer being greater than the concentration of vacancies in the surface layer and the vacancies having a concentration profile in which the peak density of the vacancies is at or near a central plane with the concentration generally decreasing from the position of peak density in the direction of a front surface of the wafer. In one embodiment, the wafer is further characterized in that it has a first axially symmetric region in which vacancies are the predominant intrinsic point defect and which is substantially free of agglomerated intrinsic point defects, wherein the first axially symmetric region comprises a central axis or has a width of at least about 15 mm. In another embodiment, the wafer is further characterized in that it has an axially symmetric region which is substantially free of agglomerated intrinsic point defects, the axially symmetric region extending radially inwardly from a circumferential edge of the wafer and having a width, as measured from the circumferential edge radially toward a center axis, which is at least about 40% the length of a radius of the wafer.

Low defect density, ideal oxygen precipitating silicon

The present invention relates to single crystal silicon, in ingot or wafer form, which contains an axially symmetric region in which vacancies are the predominant intrinsic point defect and which is substantially free of agglomerated vacancy intrinsic point defects, wherein the first axially symmetric region comprises the central axis or has a width of at least about 15 mm, and a process for the preparation thereof.

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London, United Kingdom

Robert A Falster