Silicon Crystal Pulling Molded Body Alignment
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Solution Overview
Problem
The alignment of central axes between the vitreous silica crucible and the susceptor in the Czochralski method is challenging, especially with large-diameter crucibles, leading to deformation and reduced single crystallization yield due to manual alignment and increased weight, causing difficulties in moving and re-adjusting the crucible.
Innovation Solution
A method involving the creation of a molded body based on three-dimensional data of the susceptor's inner surface and the crucible's outer surface to align their central axes, using heat-resistant materials like carbon to fill gaps and prevent deformation, allowing for precise alignment without manual adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the diameter of the vitreous silica crucible is increased to produce larger-diameter silicon single crystals, then the production capacity and performance are improved, but the weight of the crucible increases making it difficult to move and re-adjust
Solution Approach 1:
A molded body made of heat-resistant material is introduced as an intermediary between the crucible and the susceptor. This molded body has a cavity that receives the crucible, enabling precise positioning and alignment of the crucible's central axis with the susceptor's rotation axis without requiring manual handling of the heavy crucible itself.
Solution Approach 2:
The molded body is prepared in advance with a cavity specifically shaped to receive the crucible. This preliminary preparation of the positioning structure eliminates the need for complex manual alignment operations during the actual crucible installation, making the process simpler and more accurate.
2Measurement precision
If manual alignment of the crucible is performed to adjust the central axis, then the alignment precision can be improved, but the time consumption and operational complexity increase
Solution Approach 1:
The molded body serves as a pre-fabricated intermediary structure that provides automatic alignment through its cavity geometry. The crucible is positioned within the molded body's cavity, which is designed to align the crucible's central axis with the susceptor's rotation axis, eliminating the need for time-consuming manual alignment operations.
Solution Approach 2:
The molded body is created based on three-dimensional data of the susceptor's inner surface and the crucible's outer surface. This copying process ensures that the molded body's cavity perfectly matches the geometric characteristics of the components, enabling precise alignment without manual intervention.
3Volume of stationary object
If the distance between the heater and the center of the silicon single crystal is increased to accommodate larger crucibles, then the crucible capacity is improved, but the alignment deviation between the susceptor and crucible axes becomes more significant
Solution Approach 1:
The molded body acts as an intermediary positioning structure that compensates for the increased distance and potential alignment issues associated with larger crucibles. The cavity in the molded body is specifically designed to receive and precisely position the crucible, ensuring that the crucible's central axis aligns with the susceptor's rotation axis even when the crucible is located far from the heater center.
Solution Approach 2:
The invention changes the geometric parameters of the molded body's cavity to match the specific dimensions and characteristics of large-diameter crucibles. By adjusting the cavity's shape, size, and positioning features based on three-dimensional data, the system maintains high alignment accuracy despite the increased scale and distance from the heater.
Data Source
Figure 1(a)~2
Figure 3(a)~3(g)
Figure 4(a)~4(d)
AI summary
A pulling-up method of silicon single crystal comprises a process of laying a molded body between a susceptor's inner surface and a crucible's outer surface. The molded body is formed based on three-dimensional data of inner surface shape of the susceptor which can hold the vitreous silica crucible and three-dimensional data of the crucible so as to make the susceptor's central axis and the crucible's central axis substantially aligned when it is laid between the susceptor's inner surface and the crucible's outer surface.