Crystal Growing Unit with Dual Insulation for Gradient Control
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Solution Overview
Problem
Existing methods for producing large single crystals face challenges in achieving uniform temperature distribution, leading to thermally induced stresses and increased defect density due to limited control over radial temperature gradients.
Innovation Solution
A crystal growing unit with a crucible surrounded by dual thermal insulations of varying thermal conductivities, along with controlled heat flow and emissivity settings, to achieve uniform axial and minimized radial temperature gradients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single uniform thermal insulation is used around the crucible, then the device structure is simple, but the radial temperature gradient cannot be sufficiently minimized leading to thermally induced stresses and dislocations
Solution Approach 1:
The thermal insulation is divided into multiple segments with different thermal conductivities: a first thermal insulation layer with lower thermal conductivity and a second thermal insulation layer with higher thermal conductivity. This segmentation allows each layer to perform a specific function in controlling the temperature field, with the lower conductivity layer providing stronger radial insulation and the higher conductivity layer allowing controlled heat flow, thereby minimizing radial temperature gradients while maintaining structural feasibility.
Solution Approach 2:
Different regions of the thermal insulation system are assigned different thermal conductivities tailored to local requirements. The first thermal insulation layer (with lower thermal conductivity) is positioned where stronger radial temperature control is needed, while the second thermal insulation layer (with higher thermal conductivity) is positioned where controlled heat flow is beneficial. This local differentiation of thermal properties enables precise control of the temperature field to minimize dislocation formation.
2Manufacturing precision
If high thermal insulation is used to minimize radial temperature gradient, then temperature uniformity improves, but axial temperature gradient control becomes difficult affecting crystal growth
Solution Approach 1:
The thermal conductivity parameter of the insulation system is varied spatially by using two different insulation materials with different thermal conductivities. The first insulation material has lower thermal conductivity for stronger radial insulation, while the second insulation material has higher thermal conductivity to facilitate axial heat flow. This parameter change allows independent optimization of radial and axial temperature gradients, enabling precise control of both temperature uniformity and axial gradient for crystal growth.
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 setup minimizes thermally induced stresses and defect formation, enabling the production of high-quality large single crystals with controlled temperature distribution.
Implementation Method 1
The crystal growing unit has a first thermal insulation with a first thermal conductivity and a second thermal insulation with a second thermal conductivity. The first thermal insulation is preferably a high thermal insulation. The second thermal insulation is preferably a medium-high thermal insulation.
Implementation Method 2
The second thermal conductivity is greater than the first thermal conductivity. This ensures that, on the one hand, (i) the hotter source material evaporates and crystallizes in the colder spot on the growing single crystal and that, on the other hand, (ii) the heat of crystallization which is released at the crystallization growth front is dissipated through the growing single crystal.
Implementation Method 3
In practice, numerous single crystals are produced for use in electronic components or for utilization as semiprecious stones by evaporating a source material at high temperatures and by deposition or crystallization in a slightly colder spot according to the so-called PVT (physical vapor transport) method.
Implementation Method 4
by evaporating a source material at high temperatures and by deposition or crystallization in a slightly colder spot according to the so-called PVT (physical vapor transport) method.
Implementation Method 5
by evaporating a source material at high temperatures and by deposition or crystallization in a slightly colder spot according to the so-called PVT (physical vapor transport) method.
Implementation Method 6
the heat of crystallization (=latent heat) which is released at the crystallization growth front is dissipated through the growing single crystal
Data Source
AI summary
The invention relates to a crystal growing unit comprising a crucible for producing and/or enlarging a single crystal. The crystal growing unit has a first thermal insulation with a first thermal conductivity and a second thermal insulation with a second thermal conductivity. The crucible has a crucible base, a crucible side wall and a crucible cover. The crucible side wall is indirectly or directly surrounded by the first thermal insulation. The second thermal insulation is arranged indirectly or directly above the crucible cover. The second thermal conductivity is greater than the first thermal conductivity.