A method for growing a single crystal silicon ingot by the Czochralski method having reduced deviation in diameter is disclosed.

Single crystal silicon with <100> orientation is doped with n-type dopant and comprises a starting cone, a cylindrical portion and an end cone, a crystal angle being not less than 20° and not greater than 30° in a middle portion of the starting cone, the length of which is not less than 50% of a length of the starting cone, and edge facets extending from a periphery of the single crystal into the single crystal, the edge facets in the starting cone and in the cylindrical portion of the single crystal in each case having a length which is not more than 700 μm.

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.

A mono-crystalline silicon growth method includes: providing a furnace, a supporting base and a crucible which do not rotate relative to the furnace, and a heating module disposed at an outer periphery of the supporting base. After solidifying a liquid surface of a silicon melt in the crucible to form a crystal, the heating power of the heating module is successively reduced to appropriately adjust the temperature around the crucible to effectively control a temperature gradient of a thermal field around the crucible, so as to form a mono-crystalline silicon ingot by solidifying the silicon melt.

A semiconductor wafer made of single-crystal silicon has an oxygen concentration (new ASTM) of not less than 4.9×10.sup.17 atoms/cm.sup.3 and not more than 6.5×10.sup.7 atoms/cm.sup.3 and a nitrogen concentration (new ASTM) of not less than 8×10.sup.12 atoms/cm.sup.3 and not more than 5×10.sup.13 atoms/cm.sup.3, wherein a frontside of the semiconductor wafer is covered with an epitaxial layer made of silicon, wherein the semiconductor wafer comprises BMDs of octahedral shape whose mean size is 13 to 35 nm, and whose mean density is not less than 3×10.sup.8 cm.sup.−3 and not more than 4×10.sup.9 cm.sup.−3, as determined by IR tomography.

A method for pulling a cylindrical crystal from a melt by a crystal pulling unit includes measuring an actual value of a diameter of the crystal at a surface of the melt, comparing the actual value with a setpoint value for the diameter of the crystal, and setting a height of the annular gap as a function of a deviation between the actual value and the setpoint value using a first controller which has a first readjustment time.

A crystal puller apparatus comprises a pulling assembly to pull a crystal from a silicon melt at a pull speed; a crucible that contains the silicon melt; a heat shield above a surface of the silicon melt; a lifter to change a gap between the heat shield and the surface of the silicon melt; and one or more computing devices to determine an adjustment to the gap using a Pv-Pi margin, at a given length of the crystal, in response to a change in the pull speed. The computer-implemented method by a computing device comprises determining a pull-speed command signal to control a diameter of the crystal; determining a lifter command signal to control a gap between a heat shield and a surface of a silicon melt from which the crystal is grown; and determining an adjustment to the gap, in response to a different pull-speed, using a Pv-Pi margin.

A mono-crystalline silicon growth apparatus is provided. The mono-crystalline silicon growth apparatus includes a furnace, a support base disposed in the furnace, a crucible disposed on the support base, and a heating module. The support base and the crucible do not rotate relative to the heating module, and an axial direction is defined to be along a central axis of the crucible. The heating module is disposed at an outer periphery of the support base and includes a first heating unit, a second heating unit, and a third heating unit. The first heating unit, the second heating unit, and the third heating unit are respectively disposed at positions with different heights corresponding to the axial direction.

A silicon wafer having a layer of oxygen precipitates and method of manufacturing thereof wherein the wafer exhibiting robustness characterized as having a ratio of a first average density from a first treatment that to a second average density from a second treatment is between 0.74 to 1.02, wherein the first treatment includes heating the wafer or a portion of the wafer at about 1150° C. for about 2 minutes and then between about 950 to 1000° C. for about 16 hours, and the second treatment includes heating the wafer or a portion of the wafer at about 780° C. for about 3 hours and then between about 950 to 1000° C. for about 16 hours. The wafer exhibits heretofore unattainable uniformity wherein a ratio of an oxygen precipitate density determined from any one cubic centimeter in the BMD layer of the wafer to another oxygen precipitate density from any other one cubic centimeter in the BMD layer of the wafer is in a range of 0.77 to 1.30.

Nitrogen-doped CZ silicon crystal ingots and wafers sliced therefrom are disclosed that provide for post epitaxial thermally treated wafers having oxygen precipitate density and size that are substantially uniformly distributed radially and exhibit the lack of a significant edge effect. Methods for producing such CZ silicon crystal ingots are also provided by controlling the pull rate from molten silicon, the temperature gradient and the nitrogen concentration. Methods for simulating the radial bulk micro defect size distribution, radial bulk micro defect density distribution and oxygen precipitation density distribution of post epitaxial thermally treated wafers sliced from nitrogen-doped CZ silicon crystals are also provided.