Insulated Cover Member for Silicon Crystal-Pulling Crucible Meltdown
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Solution Overview
Problem
Existing crystal pulling systems experience thermal stress and damage due to non-uniform temperature gradients during the meltdown phase, leading to crucible destruction.
Innovation Solution
A cover member is introduced to partially cover the silicon charge during the initial melting phase, incorporating insulation to reduce radiant heat loss and maintain a more uniform temperature gradient, thereby reducing thermal stress on the crucible.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cover member with insulation is added to reduce radiant heat loss and maintain uniform temperature gradient, then thermal stress and damage to crucible are reduced, but device complexity increases
Solution Approach 1:
The cover member is positioned over the crucible before the meltdown phase begins, preventing thermal stress damage proactively during the melting process. This preliminary protective action avoids crucible damage before it occurs, maintaining reliability without requiring complex real-time monitoring or intervention systems.
Solution Approach 2:
The insulating cover member acts as an intermediary element between the heat source and the crucible environment. It mediates the thermal field by reducing radiant heat loss and maintaining a more uniform temperature gradient, thereby protecting the crucible from thermal stress while adding only a simple structural component rather than a complex system.
2Loss of energy
If heater power is reduced to minimize energy consumption, then energy efficiency improves, but temperature uniformity and melt stability deteriorate
Solution Approach 1:
The insulating cover member converts the potential harm of heat loss into a benefit by trapping and recycling radiant heat within the crucible environment. This reduces the need for additional heater power while maintaining temperature uniformity, as the reflected and trapped heat continuously contributes to melt stability without requiring increased energy input.
Solution Approach 2:
The cover member changes the thermal radiation parameters of the system by reflecting radiant heat back into the crucible and reducing heat loss to the environment. This parameter change in the thermal field allows the system to maintain temperature uniformity with reduced heater power, improving energy efficiency without compromising melt stability.
3Productivity
If the crucible is exposed to high radiant heat during meltdown, then melting speed increases, but thermal stress and crucible damage increase
Solution Approach 1:
The insulating cover member creates a localized modified thermal environment over the crucible, specifically addressing the radiant heat exposure issue. It allows high heat flux to maintain melting speed while simultaneously protecting the crucible walls from excessive thermal stress by reducing radiant heat loss and maintaining a more uniform temperature distribution in the melt zone.
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 use of a cover member with insulation reduces thermal stress and damage to the crucible, extending its lifetime and minimizing heat loss, while also reducing the required heater power.
Implementation Method 1
the insulating layer reduces thermal radiation losses through the cover member during meltdown
Implementation Method 2
incorporating insulation to reduce radiant heat loss and maintain a more uniform temperature gradient
Data Source
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AI summary
Crystal pulling system having a housing and a crucible assembly are disclosed. The system includes a heat shield that defines a central passage through which an ingot passes during ingot growth. A cover member is moveable within the heat shield along a pull axis. The cover member may include an insulation layer. The cover member covers at least a portion of the charge during meltdown.