Memc Electronic Materials, Inc.

Paolo Mutti

Joseph C Holzer

Bayard K Johnson

Steve A Markgraf

Seamus A McQuaid

Robert J Falster

Robert A Falster

Massimiliano Olmo

Marco Cornara

Daniela Gambaro

Vladimir V Voronkov

Francesco Bonoli

Vladmir V Voronknov

Vladimir Voronkov

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 either comprises exposing the wafer's front and back surfaces to different atmospheres, or thermally annealing two wafers in a face-to-face arrangement.

Process for forming low defect density, ideal oxygen precipitating silicon

A process for producing a single crystal silicon wafer comprising a front surface, a back surface, a lateral surface joining the front and back surfaces, a central axis perpendicular to the front and back surfaces, and a segment which is axially symmetric about the central axis extending substantially from the front surface to the back surface in which crystal lattice vacancies are the predominant intrinsic point defect, the segment having a radial width of at least about 25% of the radius and containing agglomerated vacancy defects and a residual concentration of crystal lattice vacancies wherein (i) the agglomerated vacancy defects have a radius of less than about 70 nm and (ii) the residual concentration of crystal lattice vacancy intrinsic point defects is less than the threshold concentration at which uncontrolled oxygen precipitation occurs upon subjecting the wafer to an oxygen precipitation heat treatment.

Process for preparing single crystal silicon having improved gate oxide integrity

The present invention is directed to 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.

Low defect density, ideal oxygen precipitating silicon

A single crystal silicon wafer comprising a front surface, a back surface, a lateral surface joining the front and back surfaces, a central axis perpendicular to the front and back surfaces, and a segment which is axially symmetric about the central axis extending substantially from the front surface to the back surface in which crystal lattice vacancies are the predominant intrinsic point defect, the segment having a radial width of at least about 25% of the radius and containing agglomerated vacancy defects and a residual concentration of crystal lattice vacancies wherein (i) the agglomerated vacancy defects have a radius of less than about 70 nm and (ii) the residual concentration of crystal lattice vacancy intrinsic point defects is less than the threshold concentration at which uncontrolled oxygen precipitation occurs upon subjecting the wafer to an oxygen precipitation heat treatment.

Single crystal silicon having improved gate oxide integrity

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, G0, 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&#xb0; C., and (iii) a cooling rate of the crystal from a solidification temperature to about 1,050&#xb0; 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&#xb0; 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 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

A control method for use with a crystal puller for growing a monocrystalline semiconductor crystal from a melt according to the Czochralski process. The method includes defining an initial interval of time for observing growth of the crystal being pulled from the melt and determining diameter variations occurring during the interval. Based on the variations in the crystal diameter, the method defines a function r(t). By performing a best fit routine on the function r(t), the method deduces current values of crystal radius r , meniscus height h and growth rate V at the end of the observation interval. The method also includes determining pull rate and heater power parameters as a function of the growth rate to control the crystal puller to minimize variations in both crystal diameter and growth rate during subsequent growth of the crystal.

Method for controlling growth of a silicon crystal to minimize growth rate and diameter deviations

A process for growing a single crystal silicon ingot having an axially symmetric region substantially free of agglomerated intrinsic point defects. The ingot is grown generally in accordance with the Czochralski method; however, the manner by which the ingot is cooled from the temperature of solidification to a temperature which is in excess of about 900&deg; C. is controlled to allow for the diffusion of intrinsic point defects, such that agglomerated defects do not form in this axially symmetric region. Accordingly, the ratio v/G is allowed to vary axially within this region, due to changes in v or G , between a minimum and maximum value by at least 5%.

Process for growing a silicon crystal segment substantially free from agglomerated intrinsic point defects which allows for variability in the process conditions

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 growing silicon crystals which allows for variability in the process conditions while suppressing the formation of agglomerated intrinsic point defects

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

A process for growing a single crystal silicon ingot having an axially symmetric region substantially free of agglomerated intrinsic point defects. The ingot is grown generally in accordance with the Czochralski method; however, the manner by which the ingot is cooled from the temperature of solidification to a temperature which is in excess of about 900&deg; C. is controlled to allow for the diffusion of intrinsic point defects, such that agglomerated defects do not form in this axially symmetric region. Accordingly, the ratio v/G,is allowed to vary axially within this region, due to changes in v or G,, between a minimum and maximum value by at least 5%.

Process for preparing defect free silicon crystals which allows for variability in process conditions

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.

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Milan, Italy

Paolo Mutti