SiC Crucible Recessed Center Heating for Source Efficiency
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Solution Overview
Problem
Existing SiC single crystal growth apparatuses face inefficiencies in heating the source material within the crucible, particularly at the central portion, leading to inadequate sublimation and reduced use efficiency of source materials, especially as the diameter of the single crystal increases.
Innovation Solution
A crucible with a recess in the center to house an inner heating device, combined with an outer heating device, allows for uniform heating of the crucible, using a resistance heating method and potentially induction heating, and includes a moving mechanism for the inner heating device to ensure efficient sublimation of the source material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a rod-shaped graphite is provided inside a crucible and heated by thermal conduction, then the growth rates of single crystal at central and outer peripheral portions are stabilized, but the source material in the center of the crucible cannot be sufficiently heated
Solution Approach 1:
The heating function is segmented into two independent heating devices: an outer heating device for heating the crucible outer periphery and an inner heating device for heating the source material in the center. This segmentation allows each heating device to independently control the temperature of its respective region, resolving the contradiction between stabilizing growth rates and sufficiently heating the source material.
Solution Approach 2:
The inner heating device acts as an intermediary heating element placed directly within the crucible to heat the source material from the inside. This intermediary device bridges the gap between the outer heating device and the source material, enabling sufficient heating of the source material while the outer heating device maintains the overall temperature stability for crystal growth.
2Use of energy by moving object
If rod-like graphite is heated by induction heating with high frequency coil, then heating efficiency is improved, but the high frequency is absorbed by the outer periphery of the crucible preventing sufficient heating of the rod-shaped graphite
Solution Approach 1:
The inner heating device serves as an intermediary that directly contacts or closely approaches the source material and rod-shaped graphite, enabling efficient energy transfer. This intermediary positioning allows the heating energy to be delivered directly to the target without being absorbed by the crucible outer periphery, resolving the energy absorption problem.
Solution Approach 2:
The heating approach transitions from external induction heating (heating from outside the crucible) to internal heating (heating from inside the crucible). This dimensional change in heating location allows the inner heating device to deliver energy directly to the source material and rod-shaped graphite without the crucible outer periphery intercepting the energy.
3Length of stationary object
If the diameter of SiC single crystal is increased to reduce device price, then more source material is required, but source material use efficiency decreases
Solution Approach 1:
The temperature distribution parameters within the crucible are optimized by introducing the inner heating device. This parameter change enables more uniform and efficient heating of the source material, increasing the sublimation efficiency and ensuring that more source material is effectively converted into single crystal, thereby improving source material use efficiency even when producing larger diameter crystals.
Solution Approach 2:
The patent maintains a controlled atmosphere environment (inert or vacuum) that prevents unwanted chemical reactions and material loss. This inert environment ensures that source material is lost only through the intended sublimation process for crystal growth, minimizing waste when producing large diameter single crystals that require substantial source material.
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 configuration ensures efficient sublimation of the source material across the crucible, reducing temperature differences and increasing the use efficiency of source materials, even at larger diameters and higher sublimation temperatures.
Implementation Method 1
the inner heating device uses a resistance heating method
Implementation Method 2
the rod-like graphite may be heated by induction heating
Implementation Method 3
A sublimation gas obtained by subliming a source material powder in the crucible is supplied to the seed crystal
Data Source
AI summary
The present invention provides a crucible and a SiC single crystal growth apparatus capable of improving the efficiency of using source materials. The crucible includes a lid and a container. The container includes a bottom facing the lid. The bottom includes a recess which is recessed towards the lid.