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

Patent metadata

Field	Value
Publication number	US-11060202-B2
Application number	US-201716322729-A
Country	US
Kind code	B2
Filing date	Sep 28, 2017
Priority date	Oct 10, 2016
Publication date	Jul 13, 2021
Grant date	Jul 13, 2021

Abstract

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 t 1 until a point in time t 2 , 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 t 1 until the point in time t 2 during the pulling of the initial cone is predetermined by means of an iterative computation process.

First claim

The invention claimed is:

1. A method for pulling a single crystal composed of semiconductor material having a constant diameter portion with a target diameter Dcrs from a melt contained in a crucible, comprising
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 a diameter Dcr of the initial cone of the single crystal and calculating a 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 t 1 until a point in time t 2 , wherein following t 2 the pulling of the cylindrical section of the single crystal in conjunction with the target diameter Dcrs begins, wherein a profile of the pulling rate vp(t) from the point in time t 1 until the point in time t 2 is predetermined, and a difference Δt=t 2 −t 1 is changed during the pulling of the initial cone by iteratively evaluating equations
∂Men H/∂t=vp ( t )− vcr ( t )

∂ Dcr/∂t=vcr ( t )*2 tan β cr ( t )

until the point in time t 2 matches an attainment of the target diameter Dcrs, wherein MenH, vcr and βcr denote a meniscus height, a growth rate of the single crystal and a crystal angle, respectively.

2. The method of claim 1 , further comprising:
feeding heat to a phase boundary between an edge of the single crystal and the melt by open-loop control of a heating power LstR(t) of a ring-shaped heating device arranged above the melt, and
predetermining a profile of the heating power LstR(t) of the ring-shaped heating device from the point in time t 1 until the point in time t 2 by iteratively evaluating the equations such that the growth rate of the single crystal at the point in time t 2 has a target value vcrs.

Assignees

• Siltronic Ag

Inventors

• Schroeck Thomas
• Heuwieser Walter

Classifications

• C30B15/203 Primary

  the relationship of pull rate (v) to axial thermal gradient (G) · CPC title

• C30B15/20 Primary

  Controlling or regulating (controlling or regulating in general G05) · CPC title

• C30B15/14

  Heating of the melt or the crystallised materials · CPC title

• C30B15/26

  using television detectors; using photo or X-ray detectors · CPC title