Monocrystalline Silicon Dislocation Reduction via Power Threshold
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Solution Overview
Problem
Existing methods for manufacturing monocrystalline silicon, such as the CZ and MCZ methods, face challenges in reducing dislocation in the straight body of the crystal, with previous solutions requiring design alterations or being method-specific and not effectively inhibiting dislocation occurrence.
Innovation Solution
A manufacturing method that involves heating a quartz crucible to a power consumption of at least 3.6×10^17 kJ, melting silicon, dipping a seed crystal, and pulling it up to grow monocrystalline silicon, with the formation of the straight body starting at a power consumption of 10000 kWh or more, incorporating temporarily-growing and melting-back steps to reduce dislocation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the heat radiation body is raised or lowered relative to the heat shield to inhibit heat radiation, then the silicon melt can be heated to a predetermined temperature using less electrical power, but the apparatus requires design alternation allowing the heat radiation body to be provided therein
Solution Approach 1:
The patent applies preliminary action by pre-heating the silicon melt to a specific temperature range (1400°C to 1600°C) before starting the straight body formation. This preliminary heating ensures the melt is at the optimal temperature for dislocation-free crystal growth, eliminating the need for complex real-time temperature adjustment mechanisms during the pulling process.
Solution Approach 2:
The patent changes the temperature parameter of the silicon melt to a specific range (1400°C to 1600°C) and maintains it throughout the straight body formation. This parameter control prevents dislocation occurrence without requiring complex apparatus modifications, as the temperature itself becomes the controlling factor for crystal quality.
2Reliability
If the silicon melt is left still while a magnetic field is applied to form cristobalite, then occurrence of dislocation is inhibitable, but the method is not applicable to the CZ method and requires additional process steps
Solution Approach 1:
The patent creates a universal method that can be applied to both CZ and MCZ techniques by focusing on temperature control as the common denominator. The straight body formation method using controlled temperature (1400°C to 1600°C) works regardless of whether a magnetic field is applied, making it universally applicable to different monocrystalline silicon manufacturing techniques without requiring method-specific modifications.
Solution Approach 2:
The patent extracts the essential requirement for dislocation prevention from the MCZ-specific cristobalite formation process and identifies temperature control as the universal factor. By taking out the magnetic field dependency and focusing solely on temperature management during straight body formation, the method becomes applicable to both CZ and MCZ techniques.
3Productivity
If the formation of straight body is started early at low power consumption, then productivity is maintained, but dislocation occurs in the straight body of monocrystalline silicon
Solution Approach 1:
The patent changes the temperature parameter to a specific range (1400°C to 1600°C) during straight body formation, which corresponds to a specific power consumption range (80% to 120% of melting power). This parameter optimization ensures both high crystal quality (no dislocations) and maintained productivity, as the temperature is high enough to prevent dislocation but not so high as to significantly extend processing time.
Solution Approach 2:
The patent applies partial action by heating the silicon melt to a temperature slightly above the melting point (1400°C to 1600°C) rather than to maximum possible temperatures. This partial heating is sufficient to prevent dislocation during straight body formation while avoiding the excessive energy consumption and extended processing time that would result from higher temperatures, thus maintaining productivity.
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 effectively reduces dislocation in the straight body of monocrystalline silicon, is applicable to both CZ and MCZ methods, and maintains productivity by starting the formation of the straight body at a power consumption between 10000 kWh and 12000 kWh, thereby inhibiting a decrease in productivity.
Implementation Method 1
melting silicon housed in a quartz crucible into a silicon melt by heating the quartz crucible with a heating unit
Implementation Method 2
heat radiation from a silicon melt and efficiently transmitting heat of the heat radiation body to the silicon melt via the quartz crucible
Data Source
AI summary
A manufacturing method of monocrystalline silicon includes: melting silicon housed in a quartz crucible into a silicon melt by heating the quartz crucible with a heating unit; dipping a seed crystal into the silicon melt in the quartz crucible to bring the seed crystal into contact with the silicon melt; and pulling up the seed crystal to grow monocrystalline silicon. In the pulling-up, a formation of a straight body of the monocrystalline silicon is started at a power consumption of the heating unit being equal to or more than 10000 kWh to grow an entirety of the monocrystalline silicon.