Silicon Crystal Pulling Apparatus with Movable Heater Shield
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Solution Overview
Problem
Conventional silicon single crystal pulling apparatuses face issues with controlling oxygen concentration and thermal history due to limitations in the vertical movement of heaters and shields, leading to inefficient cooling and heating, and a complex, costly structure.
Innovation Solution
A silicon single crystal pulling apparatus with a vertically movable supporting member that allows the heater and shield to move together, simplifying the mechanism and enabling efficient adjustment of thermal history and oxygen concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If only the position of the heater is changed while the position of the shield is fixed, then oxygen concentration control is improved, but the heat insulating effect becomes too high to efficiently cool the silicon single crystal
Solution Approach 1:
The heater and shield are coupled together on a common supporting member, allowing them to move vertically as a unified assembly. This merging enables coordinated adjustment of both components to achieve optimal oxygen concentration control while maintaining adequate cooling efficiency through the water-cooled chamber.
Solution Approach 2:
The supporting member is made movable vertically, transforming the static heater-shield assembly into a dynamic system. This allows real-time adjustment of the heater position relative to the melt surface during crystal pulling, enabling control of oxygen concentration and thermal history while maintaining cooling capability.
2Manufacturing precision
If the position of shield is lowered to improve heating of upper part of melt, then oxygen concentration reduction is improved, but heat insulating effect becomes too low to sufficiently heat the melt
Solution Approach 1:
By coupling the heater and shield on the same movable supporting member, the system enables coordinated positioning of both components. This allows the shield to be lowered to improve oxygen concentration control while the heater can be simultaneously positioned to maintain adequate melt temperature, resolving the trade-off between cooling and heating effects.
3Manufacturing precision
If both the heater and shield are made vertically movable to solve control problems, then oxygen concentration control and thermal history adjustment are improved, but the apparatus structure becomes extremely complicated
Solution Approach 1:
Instead of providing separate vertical movement mechanisms for the heater and shield, the invention merges them into a single movable supporting member assembly. This unified structure eliminates the need for duplicate drive systems, reducing mechanical complexity while maintaining the ability to control both components' positions relative to the crucible.
Solution Approach 2:
The movable supporting member serves multiple functions: it holds both the heater and shield, provides vertical movement for both components, and enables coordinated adjustment of their relative positions. This multi-functionality reduces the overall number of separate mechanisms required in the apparatus.
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 enhances the pulling rate and reduces oxygen concentration while maintaining a simple apparatus structure, reducing malfunctions and operational costs.
Implementation Method 1
heated with a graphite heater to melt the raw materials
Implementation Method 2
a shield disposed between the heater and the main chamber for shielding a radiant heat from the heater
Implementation Method 3
a region below the shield, which has been inside the shield, is exposed to a water cooled chamber to efficiently cool the interior of the water cooled chamber
Data Source
AI summary
The present invention is a silicon single crystal pulling apparatus based on Czochralski method, including a crucible for receiving a raw material, a heater for heating the raw material into a raw material melt, a main chamber accommodating the crucible and the heater, a shield disposed between the heater and the main chamber for shielding a radiant heat from the heater, and a supporting member holding the heater and the shield from below, the supporting member being movable vertically whereby the heater and the shield can move vertically together. As a result, there is provided a silicon single crystal pulling apparatus that facilitates the adjustment of thermal history, the improvement of pulling rate of a silicon single crystal, and the reduction in oxygen concentration.