Polycrystalline Silicon Reactor Electrode Surface Topology
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Solution Overview
Problem
In the Siemens method for producing polycrystalline silicon, the deposited material can peel off from electrodes due to its weight, causing damage and hindering the reaction process.
Innovation Solution
A polycrystalline silicon reactor with concavo-convex portions on the seed rod holding electrodes and a tapered portion with a specific angle (70° to 130°) to enhance bonding and prevent peeling, ensuring stable deposition and growth of polycrystalline silicon.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If polycrystalline silicon is deposited on the electrodes to grow seed rods, then productivity is improved, but the deposited silicon may peel off from the electrodes due to its own weight, causing damage to the furnace bottom
Solution Approach 1:
The electrode surface is modified with concavo-convex portions to create local variations in surface topology. These geometric features provide mechanical interlocking sites that enhance the bonding strength between the electrode and deposited polycrystalline silicon, preventing peeling off due to weight.
Solution Approach 2:
The concavo-convex portions introduce curved surface features rather than flat surfaces. The convex portions protrude outward while concave portions create recesses, forming a three-dimensional textured surface that increases mechanical interlocking capability with the deposited material.
2Reliability
If the electrode surface area is increased to improve bonding, then reliability is improved, but device complexity increases
Solution Approach 1:
Instead of uniformly increasing the entire electrode surface area, the invention locally modifies specific regions with concavo-convex portions. This approach enhances bonding strength at critical interfaces while maintaining the overall simplicity of the electrode structure and avoiding excessive complexity.
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 solution effectively prevents peeling and cracking of polycrystalline silicon, allowing for reliable and stable production by increasing the bonding interface and maintaining electrode integrity during the reaction.
Implementation Method 1
an electric current is applied to the whole silicon seed rods from the electrodes located at both ends, and the whole silicon seed rods are heated to about 1050° C. to 1100° C. which is the thermal decomposing temperature of the source gas by Joule's heat by the electric current
Implementation Method 2
The source gas supplied into the furnace contacts the surfaces of the silicon seed rods heated in this way, and is thermally decomposed or hydrogen-reduced, whereby polycrystalline silicon is deposited on the surfaces of the silicon seed rods
Implementation Method 3
the source gas composed of a mixed gas of chlorosilanes and hydrogen into contact with a heated silicon seed rod, and depositing the polycrystalline silicon on the surface of the seed rod by reaction of the source gas
Data Source
AI summary
A polycrystalline silicon reactor which can prevent polycrystalline silicon which deposits on the surface of an electrode holding a silicon seed rod from being peeled off is provided. In a polycrystalline silicon reactor which applies an electric current to a silicon seed rod provided within a furnace, thereby heating the silicon seed rod, brings a source gas supplied into the furnace into reaction, and deposits polycrystalline silicon on the surface of the silicon seed rod, the reactor includes, at a bottom plate of the furnace, an electrode holder provided so as to be electrically insulated from the bottom plate, and a seed rod holding electrode connected to the electrode holder, and holding the silicon seed rod toward the upside. Concavo-convex portions exposed to a furnace atmosphere is provided at an outer peripheral surface of the seed rod holding electrode.