Memc Electronic Materials, Inc.

Mohsen Banan

Jeffrey Louis Libbert

Milind S Kulkarni

Lee William Ferry

Robert J Falster

Richard Joseph Phillips

Steven Lawrence Kimbel

Zheng Lu

Robert H Fuerhoff

Carl F Cherko

Luciano Mule'Stagno

Richard L Hansen

Ying Tao

Hiroyo Haga

Stephen J Brunkhorst

Chang Bum Kim

Takaaki Aoshima

John D Holder

Harold W Korb

Hariprasad Sreedharamurthy

Vladimir V Voronkov

Richard G Schrenker

Kyong-Min Kim

Christopher Vaughn Luers

Vladimir V Vornokov

Charles Whitmer, Ii

The present invention relates to a process for forming single crystal silicon ingots or wafers that contain an axially symmetric region in which vacancies are the predominant intrinsic point defect, that are substantially free of oxidation induced stacking faults, and are nitrogen doped to stabilize oxygen precipitation nuclei therein.

Nitrogen-doped silicon substantially free of oxidation induced stacking faults

The present invention relates to a process for preparing a single crystal silicon ingot, as well as to the ingot or wafer resulting therefrom. The process comprises controlling (i) a growth velocity, v, (ii) an average axial temperature gradient, G, and (iii) a cooling rate of the crystal from solidification to about 750&#xb0; C., in order to cause the formation of a segment having a first axially symmetric region extending radially inward from the lateral surface of the ingot wherein silicon self-interstitials are the predominant intrinsic point defect, and a second axially symmetric region extending radially inward from the first and toward the central axis of the ingot. The process is characterized in that v, Gand the cooling rate are controlled to prevent the formation of agglomerated intrinsic point defects in the first region, while the cooling rate is further controlled to limit the formation of oxidation induced stacking faults in a wafer derived from this segment, upon subjecting the wafer to an oxidation treatment otherwise suitable for the formation of such faults.

Low defect density silicon having a vacancy-dominated core substantially free of oxidation induced stacking faults

A process for imparting controlled oxygen precipitation behavior to a single crystal silicon wafer. Specifically, prior to formation of the oxygen precipitates, the wafer bulk comprises dopant stabilized oxygen precipitate nucleation centers. The dopant is selected from a group consisting of nitrogen and carbon, and the concentration of the dopant is sufficient to allow the oxygen precipitate nucleation centers to withstand thermal processing, such as an epitaxial deposition process, while maintaining the ability to dissolve any grown-in nucleation centers.

Process for making silicon wafers with stabilized oxygen precipitate nucleation centers

A single crystal silicon, ingot or wafer form, which contains an axially symmetric region in which vacancies are the predominant intrinsic point defect, is substantially free of oxidation induced stacking faults and is nitrogen doped to stabilize oxygen precipitation nuclei therein, and a process for the preparation thereof.

A single crystal silicon ingot having a constant diameter portion that contains arsenic dopant atoms at a concentration which results in the silicon having a resistivity that is less than about 0.003 &#x3a9;&#xb7;cm.

Single crystal silicon ingot having a high arsenic concentration

A process for the preparation of a silicon single ingot in accordance with the Czochralski method. 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&#xb0; C. to initially produce in the constant diameter portion of the ingot a series of predominant intrinsic point defects including vacancy dominated regions and silicon self interstitial dominated regions, alternating along the axis, and cooling the regions from the temperature of solidification at a rate which allows silicon self-interstitial atoms to diffuse radially to the lateral surface and to diffuse axially to vacancy dominated regions to reduce the concentration intrinsic point defects in each region.

Method for the production of low defect density silicon

The present invention provides for a process for preparing a single crystal silicon ingot by the Czochralski method. The process comprises selecting a seed crystal for Czochralski growth wherein the seed crystal comprises vacancy dominated single crystal silicon.

Seed crystals for pulling single crystal silicon

A silicon wafer having a controlled oxygen precipitation behavior such that a denuded zone extending inward from the front surface and oxygen precipitates in the wafer bulk sufficient for intrinsic gettering purposes are ultimately formed. Specifically, prior to formation of the oxygen precipitates, the wafer bulk comprises dopant stabilized oxygen precipitate nucleation centers. The dopant is selected from a group consisting of nitrogen and carbon and the concentration of the dopant is sufficient to allow the oxygen precipitate nucleation centers to withstand thermal processing such as an epitaxial deposition process while maintaining the ability to dissolve any grown-in nucleation centers.

Silicon wafers with stabilized oxygen precipitate nucleation centers and process for making the same

A crystal puller and method for growing monocrystalline silicon ingots includes first and second electrical resistance heaters in the crystal puller in longitudinal, closely spaced relationship with each other to radiate heat toward the ingot as the ingot is pulled upward within the housing. In one embodiment, the first heater is powered when the ingot is pulled upward to a first axial position above the surface of the molten silicon and the second heater is powered when the ingot is pulled upward to a second axial position above the first axial position. In another embodiment the first and second heaters are powered until the ingot is separated from the molten silicon and then the heating power output of the first and second heaters is reduced to substantially increase the cooling rate at which the ingot is cooled. An adapter mounting the heaters may also be provided for adapting existing crystal pullers to incorporate the heaters.

Crystal puller and method for growing monocrystalline silicon ingots

A heat shield assembly for use in a crystal puller has an outer reflector interposed between the ingot and the crucible as the ingot is pulled from the molten source material. A cooling shield is interposed between the ingot and the outer reflector whereby the cooling shield is exposed to heat radiated from the ingot for increasing the rate at which the ingot is cooled, thereby increasing the axial temperature gradient of the ingot. In a further embodiment, an inner shield panel is disposed generally intermediate the cooling shield and the ingot in radially spaced relationship with the cooling shield and is constructed of a material substantially transparent to radiant heat from the ingot.

Heat shield assembly for crystal puller

A crystal puller for growing monocrystalline silicon ingots includes first and second electrical resistance heaters in the crystal puller in longitudinal, closely spaced relationship with each other to radiate heat toward the ingot as the ingot is pulled upward within the housing. An adapter mounting the heaters may also be provided for adapting existing crystal pullers to incorporate the heaters.

Crystal puller for growing monocrystalline silicon ingots

A method and apparatus for preparing molten silicon melt from polycrystalline silicon in a crystal pulling apparatus entails loading an amount of polycrystalline silicon loaded into the crucible less than a predetermined total amount of polycrystalline silicon to be melted. The crucible is heated to form a partially melted charge in the crucible having an island of unmelted polycrystalline silicon exposed above an upper surface of melted silicon. Granular polycrystalline silicon is fed from a feeder onto the island of unmelted polycrystalline silicon until the predetermined total amount of polycrystalline silicon has been loaded into the crucible. The position of the island relative to the crucible side wall is electronically determined as granular polycrystalline silicon is fed onto the island. The feed rate at which granular polycrystalline silicon is fed from the feeder onto the island of unmelted polycrystalline silicon is controlled in response to the determined position of the island relative to the crucible side wall.

Method for preparing molten silicon melt from polycrystalline silicon charge

A method of lowering the resistivity of resultant silicon crystal from a Czochralski crystal growing process by adding arsenic dopant to the melt in multiple stages.

Growing community of inventors

Grover, MO, United States of America

Mohsen Banan