A method for preparing a single crystal silicon ingot and a wafer sliced therefrom are provided. The ingots and wafers comprise nitrogen at a concentration of at least about 1×10.sup.14 atoms/cm.sup.3 and/or germanium at a concentration of at least about 1×10.sup.19 atoms/cm.sup.3, interstitial oxygen at a concentration of less than about 6 ppma, and a resistivity of at least about 1000 ohm cm.

A method for preparing a single crystal silicon ingot and a wafer sliced therefrom are provided. The ingots and wafers comprise nitrogen at a concentration of at least about 1×10.sup.14 atoms/cm.sup.3 and/or germanium at a concentration of at least about 1×10.sup.19 atoms/cm.sup.3, interstitial oxygen at a concentration of less than about 6 ppma, and a resistivity of at least about 1000 ohm cm.

A method for preparing a single crystal silicon ingot and a wafer sliced therefrom are provided. The ingots and wafers comprise nitrogen at a concentration of at least about 1×10.sup.14 atoms/cm.sup.3 and/or germanium at a concentration of at least about 1×10.sup.19 atoms/cm.sup.3, interstitial oxygen at a concentration of less than about 6 ppma, and a resistivity of at least about 1000 ohm cm.

A seed crystal holder for pulling up a single crystal is made of a carbon fiber-reinforced carbon composite material, and has a substantially cylindrical shape with a hollow space having a shape matching an outer shape of a substantially rod-shaped seed crystal. A direction of carbon fibers at a part in contact with at least an outer peripheral surface of the seed crystal has isotropy as viewed from a central axis of the hollow space.

Methods for preparing single crystal silicon substrates for epitaxial growth are disclosed. The methods may involve control of the (i) a growth velocity, v, and/or (ii) an axial temperature gradient, G, during the growth of an ingot segment such that v/G is less than a critical v/G and/or is less than a value of v/G that depends on the boron concentration of the ingot. Methods for preparing epitaxial wafers are also disclosed.

Methods for preparing an ingot in an ingot puller apparatus are disclosed. Thermal simulations are performed with the length of the ingot puller apparatus side heater being varied in the thermal simulations. A side heater is selected based on the thermal simulations. An ingot puller apparatus having the selected side heater length is provided. A seed crystal is lowered into a melt within a crucible of the ingot puller apparatus and an ingot is withdrawn from the melt.

An apparatus for manufacturing a single crystal according to a Czochralski method, including: a main chamber housing crucibles for a raw-material melt and heater for heating the raw-material melt; a pulling chamber at an upper portion of the main chamber and a single crystal pulled from the raw-material melt; a cooling cylinder extending from a ceiling portion of the main chamber toward a surface of the raw-material melt to surround the single crystal; an auxiliary cooling cylinder inside the cooling cylinder; and a diameter-enlargement member to fit into the auxiliary cooling cylinder. The auxiliary cooling cylinder has a slit penetrating in an axial direction to come into close contact with the cooling cylinder by pushing the diameter-enlargement member into the auxiliary cooling cylinder to enlarge the diameter of the auxiliary cooling cylinder. This enables efficient cooling of a growing single crystal and increases the growth rate of the single crystal.

An apparatus for manufacturing a single crystal according to a Czochralski method, including: a main chamber housing crucibles for a raw-material melt and heater for heating the raw-material melt; a pulling chamber at an upper portion of the main chamber and a single crystal pulled from the raw-material melt; a cooling cylinder extending from a ceiling portion of the main chamber toward a surface of the raw-material melt to surround the single crystal; an auxiliary cooling cylinder inside the cooling cylinder; and a diameter-enlargement member to fit into the auxiliary cooling cylinder. The auxiliary cooling cylinder has a slit penetrating in an axial direction to come into close contact with the cooling cylinder by pushing the diameter-enlargement member into the auxiliary cooling cylinder to enlarge the diameter of the auxiliary cooling cylinder. This enables efficient cooling of a growing single crystal and increases the growth rate of the single crystal.

A method for preparing a single crystal silicon ingot and a wafer sliced therefrom are provided. The ingots and wafers comprise nitrogen at a concentration of at least about 1×10.sup.14 atoms/cm.sup.3 and/or germanium at a concentration of at least about 1×10.sup.19 atoms/cm.sup.3, interstitial oxygen at a concentration of less than about 6 ppma, and a resistivity of at least about 1000 ohm cm.

Methods for preparing single crystal silicon substrates for epitaxial growth are disclosed. The methods may involve control of the (i) a growth velocity, v, and/or (ii) an axial temperature gradient, G, during the growth of an ingot segment such that v/G is less than a critical v/G and/or is less than a value of v/G that depends on the boron concentration of the ingot. Methods for preparing epitaxial wafers are also disclosed.