Feed Tube Liquid Doping for Semiconductor Melt Thermal Shock

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Solution Overview

Problem

The use of solid dopants in the Czochralski method for semiconductor or solar-grade material processing leads to thermal shock, quartz particle formation, contamination, and inefficient dopant use due to evaporation, resulting in crystal defects and assembly damage.

Innovation Solution

A liquid doping system that melts solid dopants within a feed tube and introduces the liquid dopant below the surface of the melt, using a dopant feeding device and feed tube with a restrictor nozzle to prevent solid dopant passage and ensure liquid dopant introduction, thereby reducing thermal shock and evaporation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If solid dopants are added directly to the molten source material, then the doping process is simple, but thermal shock occurs causing floating boats and quartz particle formation

Engineering Contradiction:

Improvedoping process simplicityVSAvoidthermal shock effects

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

A feed tube is introduced as an intermediary component between the dopant addition point and the melt. The feed tube is submerged below the melt surface, allowing dopants to be introduced at depth rather than directly onto the surface, thereby preventing thermal shock and floating boat formation while maintaining process simplicity

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The feed tube is pre-positioned and maintained in a specific configuration before dopant addition. The tube extends below the melt surface in advance, creating a protected introduction path that prevents thermal shock before the dopant actually contacts the melt

Inventive Principle:

Principle #10Preliminary action

2Productivity

If solid dopants are added to the molten source material, then doping can be performed, but contamination of the monocrystalline growing assembly occurs

Engineering Contradiction:

Improvedoping capabilityVSAvoidassembly contamination

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The feed tube serves as a protected conduit that isolates the dopant introduction process from the surrounding assembly components. By channeling dopants through the submerged tube, direct contact between dopants and assembly surfaces is prevented, eliminating contamination while maintaining doping functionality

Inventive Principle:

Principle #24Intermediary (Mediator)

3Productivity

If solid dopants with high evaporation rates are placed in the crucible prior to melting, then doping is achieved, but significant dopant evaporation occurs reducing efficiency

Engineering Contradiction:

Improvedoping effectivenessVSAvoiddopant evaporation loss

Core Design Contradiction:

ProductivityVSLoss of substance

Solution Approach 1:

The feed tube is pre-positioned below the melt surface before dopant addition. This preliminary configuration creates a protected introduction path that immediately directs dopants into the melt interior, preventing evaporation at the surface and maximizing dopant utilization efficiency

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The submerged feed tube acts as a protective intermediary that shields volatile dopants from direct exposure to the atmosphere during introduction. The tube confines the dopant introduction path, preventing evaporative loss while ensuring effective doping

Inventive Principle:

Principle #24Intermediary (Mediator)

4Ease of manufacture

If solid dopants are added to the melt, then doping is performed, but splashing occurs damaging assembly components

Engineering Contradiction:

Improvedoping operationVSAvoidmelt splashing damage

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The feed tube serves as a protective intermediary that channels dopant introduction away from the melt surface. This prevents direct impact between solid dopants and the melt surface, eliminating splashing and potential damage to assembly components while maintaining the doping operation

Inventive Principle:

Principle #24Intermediary (Mediator)

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

This method inhibits thermal shock, reduces evaporation, and minimizes contamination, leading to improved crystal growth with reduced defects and efficient dopant utilization.

Implementation Method 1

The feed tube is configured to receive solid dopant from the dopant feeding device and dispense liquid dopant into the melt

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

many have relatively high evaporation rates, such as indium or antimony

Methodology Applied

Scientific EffectEvaporation: Evaporation

Data Source

PatentUS11346016B2System for introducing dopant into a melt of semiconductor or solar-grade material via a feed tube

Publication Date: 2022.05.31 GLOBALWAFERS CO LTD

AI summary

A method of growing a doped monocrystalline ingot using a crystal growing system is provided. The crystal growing system includes a growth chamber, a dopant feeding device, and a feed tube. The method includes preparing a melt of semiconductor or solar-grade material in a crucible disposed within the growth chamber, introducing a solid dopant into the feed tube with the dopant feeding device, melting the solid dopant within the feed tube to a form a liquid dopant, introducing the liquid dopant into the melt below a surface of the melt, and growing a monocrystalline ingot from the melt by contacting the melt with a seed crystal and pulling the seed crystal away from the melt.