Siltronic Ag

Thomas Schroeck

Wilfried Von Ammon

Walter Heuwieser

Thomas Aubrunner

Claus Kropshofer

Single crystal semiconductor ingots are pulled from a melt contained in a crucible by a method of controlling the pulling the single crystal in a phase in which an initial cone of the single crystal is grown until a phase in which the pulling of a cylindrical section of the single crystal is begun, by measuring the diameter Dcr of the initial cone of the single crystal and calculating the change in the diameter dDcr/dt; pulling the initial cone of the single crystal from the melt at a pulling rate vp(t) from a point in time tuntil a point in time t, starting from which the pulling of the cylindrical section of the single crystal in conjunction with a target diameter Dcrs is begun, wherein the profile of the pulling rate vp(t) from the point in time tuntil the point in time tduring the pulling of the initial cone is predetermined by means of an iterative computation process.

Method for pulling a single crystal composed of semiconductor material from a melt contained in a crucible

FZ single crystals are pulled by melting a polycrystal with electromagnetic melting apparatus and then recrystallizing. First, a lower end of the polycrystal is melted; second, a monocrystalline seed is attached to the lower end of the polycrystal and melted beginning from an upper end thereof; third, between a lower section of the seed and the polycrystal, a thin neck is formed whose diameter (d) is smaller than that (d) of the seed; and fourth, between the thin neck section and the polycrystal, a conical section is formed. Before the conical growth, a switchover position (h') of the polycrystal, the position at which the rate of polycrystal movement relative to the melting apparatus is to be reduced is determined, and the rate is reduced, in amount when the switchover position (h&#x2032;) is reached.

Method and apparatus for pulling a single crystal by the FZ method

A single crystal is pulled by an FZ method, in which a polycrystal is melted by means of an electromagnetic melting apparatus and then recrystallized, wherein a first phase (P) a lower end of the polycrystal, which is moved toward the melting apparatus, is melted by the melting apparatus to form a drop, and in a second phase (P) a monocrystalline seed is attached to the lower end of the polycrystal and is melted beginning from an upper end of the seed, where a power (P) of the melting apparatus during the first phase (P) and during the second phase (P) is predetermined at least temporarily in dependence on a temperature and/or geometrical dimensions of crystal material used which comprises the drop and/or the seed and/or the polycrystal.

Method for pulling a single crystal by the FZ method comprising reducing the power of a melting apparatus based on geometrical dimensions of the drop

A single crystal is pulled by the FZ method, in which in a first phase, a lower end of the polycrystal is melted by the melting apparatus, in a second phase, a monocrystalline seed is attached to the lower end of the polycrystal, and in a third phase, between a lower section of the seed and the polycrystal, a thin neck section is formed whose diameter is smaller than that of the seed, where the power of the melting apparatus before the third phase is dynamically adapted in dependence on a position of a lower phase boundary (P) between liquid material and solid material on the part of the seed, and where the power of the melting apparatus during the third phase is dynamically adapted in dependence on the position of an upper phase boundary (P) between liquid material and solid material on the part of the polycrystal plant.

Method for pulling a single crystal by the FZ method comprising dynamically adapting the power of a melting apparatus based on a position of lower and upper phase boundaries

The diameter (d) of a cylindrical section and of an end cone of a single crystal being pulled from a melt in a crucible, is determined by measuring the diameter (d) of the single crystal at an interface with the melt while taking into account a lowering rate (v) of a surface of the melt relative to the crucible, a lifting rate (v) with which the crystal is raised relative to the crucible, and a conservation of mass, wherein a diameter of a cylindrical section of the single crystal, determined by means of observing a bright ring on the surface of the melt, and is used for a correction, a plausibility check or a comparison of the diameter (d) of the single crystal.

Method for determining and regulating a diameter of a single crystal during pulling of the single crystal

The diameter of a single crystal is controlled to a set point diameter during pulling of the single crystal from a melt contained in a crucible and which forms a meniscus at a phase boundary on the edge of the single crystal, the meniscus having a height which corresponds to the distance between the phase boundary and a level of the surface of the melt outside the meniscus, comprising repeatedly:

Method for controlling the diameter of a single crystal to a set point diameter

Single crystal composed of silicon with a section having a diameter that remains constant, are pulled by a method wherein the single crystal is pulled with a predefined pulling rate vhaving the units [mm/min]; and the diameter of the single crystal in the section having a diameter that remains constant is regulated to the predefined diameter by regulating the heating power of a first heating source which supplies heat to the single crystal and to a region of the melt that adjoins the single crystal and is arranged above the melt, such that diameter fluctuations are corrected with a period duration T that is not longer than (2&#xb7;18 mm)/v.

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Kastl, Germany

Thomas Schroeck