Electric beam melting and directional solidification combined device for polycrystalline silicon powder and method

Abstract

The invention relates to an electric beam melting and directional solidification combined device for polycrystalline silicon powder and a method for melting polycrystalline silicon by using the device, belongs to the field of electric beam melting. The invention provides the electric beam melting polycrystalline silicon powder device capable of supplementing materials in the melting process and mainly provides a charging device; the charging device is compact in structure, does not affect the integral size of smelting equipment and the whole melting process is sustainable. The device is provided with an ingot pulling system simultaneously for achieving the directional solidification purification technique while the impurity phosphorus element is removed from polycrystalline silicon by electric beam melting; phosphorus impurity and metal impurities can be removed simultaneously by using one piece of equipment, so that the quantity of used equipment is reduced, unnecessary waste on vacuumizing time when the equipment is used is reduced, and the loss and secondary pollution of a silicon material in an intermediate link when the equipment is used are reduced.

Description

technical field [0001] The invention relates to a device for combining electron beam smelting polysilicon powder with directional solidification and a method for polysilicon smelting using the device, belonging to the field of electron beam smelting. Background technique [0002] The technology of electron beam smelting to remove volatile impurities in polysilicon, refractory metals and rare metals is relatively mature. The high energy density, high melting temperature and local overheating of electron beams can effectively remove volatile impurities in raw materials. . At present, because the working environment of electron beam smelting technology is a vacuum condition, the addition and replenishment of raw materials is in the form of lumps with a certain particle size. [0003] However, due to the surface heating characteristics of the electron beam, that is, although the heating local temperature can reach more than 3000°C, the penetration zone of the heating melt is on...

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Problems solved by technology

[0003] However, due to the surface heating characteristics of the electron beam, that is, although the heating local temperature can reach more than 3000°C, the penetration zone of the heating melt is only a dozen millimeters, at most tens of millimeters, which will cause the first block to be added. The solid material will fall into the bottom layer of the raw material melt, and the electron beam cannot directly act on the added bulk material, but gradually melts the first added bulk material through the radiant heat of the electron beam heating the upper melt, among which The volatile impurities are also gradually diffused from the bottom layer to the surface layer by diffusion and removed. This process leads to a longer melting time and increases the energy consumption of electron beam melting.

[0004] The current purification technology generally uses directional solidification equipment to remove metal impurities in polysilicon, then takes out the silicon ingot, removes the skin, breaks it to a specified size and cleans it, and then uses electron beam melting equipment to remove phosphorus impurities in polysilicon. The process requires two devices to be carried out separately. When the two technologies are docked, polysilicon needs to be crushed, resulting in the loss of silicon materials. At the same time, there is a possibility of secondary pollution during the crushing process.

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