Silicon Ingot Screw Dislocation Control via Vertical Magnetic Field

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Solution Overview

Problem

Silicon single crystalline ingots and wafers often contain crystal defects such as screw dislocations caused by the Horizontal Magnetic Czochralski (HMCZ) method, which propagate into cross slip dislocations during thermal processing, leading to faults in semiconductor devices.

Innovation Solution

An apparatus with a unique upper heat shield structure and controlled process conditions, including a horizontal magnetic field, crucible rotation, and impurity addition, is used to manufacture silicon single crystalline ingots that minimize screw dislocations and their propagation into cross slip dislocations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the HMCZ method using a strong horizontal magnetic field is used to grow silicon single crystalline ingots, then the productivity and manufacturing capability are improved, but screw dislocations are generated in the ingots which propagate into cross slip dislocations during thermal processing

Engineering Contradiction:

Improvemanufacturing capabilityVSAvoidcrystal defect generation

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent applies a vertical magnetic field instead of a horizontal magnetic field, changing the direction parameter of the magnetic field to prevent screw dislocation generation while maintaining the HMCZ method's productivity benefits

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent converts the harmful effect of magnetic field-induced screw dislocations by using a vertical magnetic field configuration that prevents dislocation formation while still utilizing magnetic field control for beneficial melt convection management

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Area of stationary object

If wafers are manufactured with larger diameter to meet market requirements, then the productivity and area utilization are improved, but the detection and control of crystal defects becomes more difficult

Engineering Contradiction:

Improvewafer diameterVSAvoiddefect detection difficulty

Core Design Contradiction:

Area of stationary objectVSDifficulty of detecting and measuring

Solution Approach 1:

The patent prevents cross slip dislocation formation at the crystal growth stage by using a vertical magnetic field, addressing the defect problem before wafer manufacturing and detection stages, making defect control easier in larger diameter wafers

Inventive Principle:

Principle #10Preliminary action

3Device complexity

If conventional upper heat shield structures are used in the HMCZ apparatus, then the device complexity is kept simple, but cross slip dislocations are generated due to uncontrolled thermal gradients

Engineering Contradiction:

Improveheat shield structure simplicityVSAvoidcrystal defect control

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The patent changes the magnetic field direction parameter to vertical, which fundamentally alters the thermal convection patterns and eliminates the need for complex heat shield structures to control thermal gradients, simultaneously improving manufacturing precision while maintaining structural simplicity

Inventive Principle:

Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The solution effectively reduces the generation and propagation of cross slip dislocations, resulting in high-quality silicon wafers and epitaxial wafers with lower fault rates in semiconductor devices, suitable for larger diameter wafers.

Implementation Method 1

applying a horizontal magnetic field to the silicon melt received in the crucible

Methodology Applied

Scientific EffectMagnetic field: Magnetic Field

Implementation Method 2

HMCZ (Horizontal Magnetic Czochralski) method using a strong horizontal magnetic field

Methodology Applied

Scientific EffectMagnetohydrodynamic effect: Magnetohydrodynamic Effect

Implementation Method 3

an upper heat shield structure that is spaced apart with a predetermined gap from a surface of a silicon melt

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 4

upper heat shield structure arranged around a silicon single crystalline ingot pulled from the silicon melt

Methodology Applied

Scientific EffectThermal radiation: Thermal Radiation

Implementation Method 5

a process for growing a silicon single crystalline ingot

Methodology Applied

Scientific EffectCrystallization: Crystallisation

Implementation Method 6

pulling up a silicon single crystalline ingot from the silicon melt

Methodology Applied

Scientific EffectSolidification: Freezing

Data Source

PatentUS8349075B22-dimensional line-defects controlled silicon ingot, wafer and epitaxial wafer, and manufacturing process and apparatus therefor

Publication Date: 2013.01.08 LG SILTRON

AI summary

The present invention reports a defect that has not been reported, and discloses a defect-controlled silicon ingot, a defect-controlled wafer, and a process and apparatus for manufacturing the same. The new defect is a crystal defect generated when a screw dislocation caused by a HMCZ (Horizontal Magnetic Czochralski) method applying a strong horizontal magnetic field develops into a jogged screw dislocation and propagates to form a cross slip during thermal process wherein a crystal is cooled. The present invention changes the shape and structure of an upper heat shield structure arranged between a heater and an ingot above a silicon melt, and controls initial conditions or operation conditions of a silicon single crystalline ingot growth process to reduce a screw dislocation caused by a strong horizontal magnetic field and prevent the screw dislocation from propagating into a cross slip.