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Monocrystalline Silicon Growth Furnace Molybdenum Guide Tube And Processing Method Thereof
- Jan 05, 2019 -

The invention belongs to the technical field of special equipment for single crystal silicon.

Background technique:

At present, a large number of raw materials required for the semiconductor and photovoltaic industries - monocrystalline silicon and monocrystalline silicon materials are produced by special equipment "monocrystalline silicon crystal growth furnace" to improve the production capacity of monocrystalline silicon and reduce the production of monocrystalline silicon. Cost is a technical issue that crystal manufacturers have been solving for a long time through equipment improvement and optimization. Increasing the crystal pulling speed is one of the important means to effectively increase production efficiency and control production costs. In recent years, crystal manufacturers at home and abroad have added a layer of molybdenum guide tubes (also called guide tube molybdenum bushings) in the graphite guide tube. The application of this technology and products not only serves as the direct radiation for isolating graphite and ingots. And effectively control the temperature of the ingot, and further increase the pulling speed. Through a large number of technical investigations, all kinds of furnace-type molybdenum guide tubes for producing single crystal silicon at home and abroad are made of "flat molybdenum plate" to make the guide tube. At present, the flat-plate guide tube and the wavy linear baffle selected by the pull crystal market can only solve the problem of preventing photothermal radiation, but in the presence of radiation, the central high temperature region in the guide tube is concentrated on the pulled single crystal rod, and there is a single The temperature center of the ingot is too high, which seriously affects the crystal pulling speed problem, and the life is also low, resulting in high manufacturing cost of single crystal silicon.

Technical realization elements:

The object of the present invention is to provide a molybdenum guide tube and a processing technology for a single crystal silicon growth furnace, so that the molybdenum guide tube not only improves the performance of the flow guiding and cooling, but also the central high temperature region of the guiding tube (the single crystal rod is located) The position is displaced to the vicinity of the inner wall of the draft tube to lower the temperature of the central region, thereby achieving optimization of the pulling rate.

Briefly, the present invention utilizes the principle of optical slow radiation to change the high temperature distribution inside the draft tube due to the conical deformation of the side wall of the guide tube and the increase of the unit area by the tapered shape of the guide tube itself.

Specifically, a molybdenum guide tube of a single crystal silicon growth furnace has a conical cylinder made of a metal molybdenum plate, which has uniformly distributed convex points or alternately uniformly distributed grooves on the side wall of the conical cylinder. Raised point.

The metal molybdenum plate has a thickness of 0.05-1.5 mm, and the groove and the convex point are equally distributed and evenly distributed on the side wall of the cone, and the depth of the groove and the height of the convex point are 0.5-3 mm.

The grooves and/or raised points are evenly distributed at a density of 80-120 per square centimeter.

The concave and convex shapes of the groove and the convex point are uniformly unified, and are one or a combination of the following shapes: a triangle, a diamond, a quadrangle, a square, a circle, and a polygon.

The processing technology of the molybdenum guide tube is firstly pressed by the upper mold and the lower mold to hold the metal molybdenum plate vertically, and is formed by hot pressing or cold pressing or heat treatment forming process, and the metal molybdenum plate is pressed into a concave plate of a design shape. Reworked into a cone; the upper and lower dies are respectively formed with correspondingly shaped grooves and raised points.

The processing process of the molybdenum guide tube may be that the metal molybdenum plate is first pressed into a concave plate by a drum type circumferential forming process, and then rolled into a cone; the drum is provided with uniformly arranged convex points, metal The molybdenum plate is lowered to hold the special material as a backing plate and the metal molybdenum plate is pressed by the roller to form grooves and raised points.

The processing process of the molybdenum guide tube may also be that the columnar material is first fixed on the surface of the metal molybdenum plate to form a uniformly distributed convex point, and then rolled into a cone. The surface of the metal molybdenum plate is fixed by a conventional spot welding or welding column material.

The invention utilizes the principle of optical slow radiation to increase the unit area and perform the deformation of the concave and convex, and utilizes the tapered shape of the guide tube itself to achieve the temperature control and the displacement of the high temperature region, so that the center portion of the circumference of the draft tube ( Both the temperature of the single crystal rod and the high temperature zone are transferred to the vicinity of the wall of the draft tube. Therefore, the temperature of the single crystal rod in the pulling is lowered, and the peripheral edge displacement of the high temperature region makes the cooling effect of the guiding current more obvious, and the guiding gas directly acts on the high temperature region around the guiding tube, so that the pulling speed is rapidly increased by more than 10%. In addition, the rib structure of the unevenness improves the high temperature resistance of the draft tube, and the invention achieves the purpose of prolonging the life of the draft tube, saving energy, improving production efficiency, and reducing production cost. The embossed plate type design adopted by the invention completely solves the problem of displacement of the high temperature zone in the draft tube, and is a problem that cannot be solved by various existing shape molybdenum guide tubes.

The fundamental problem in the solar photovoltaic power generation industry is high production costs and high one-time investment, so market promotion requires government support. As the single crystal silicon power generation with the highest PV conversion rate, the high production cost of monocrystalline silicon itself determines the overall operating cost. How to continuously and continuously pass the technological innovation process, the innovation reduces the production cost of monocrystalline silicon. The industry has long shared the issue of joint research and development. Although the invention uses the principle of optical slow radiation to change the shape of the molybdenum guide tube, it has a considerable advantage in saving and controlling the production cost of the single crystal silicon from the aspects of the quality of the single crystal silicon crystal growth and shortening the production cycle. It has far-reaching industrial promotion significance and industrial significance of energy saving and environmental protection.

The invention not only changes the structure, environment and conditions of the original furnace body, but only utilizes the optical principle of the concave-convex type of the guide tube, so that the pulling speed can be improved by more than 10% on the original basis.

DRAWINGS

Figure 1 is a schematic view showing the structure of a guide tube of the present invention.

Fig. 2 is an enlarged view of a portion B of Fig. 1.

Figure 3 is a partial schematic view (diamond) of the upper and lower molds of the present invention.

Figure 4 is a partial schematic view (diamond) of the drum mold of the present invention.

Figure 5 is a schematic view of a single-sided diamond-shaped concave-convex plate of the present invention.

Figure 6 is a schematic view of a double-sided diamond-shaped concave-convex plate of the present invention

Detailed ways

Embodiment 1: A molybdenum guide tube of a single crystal silicon growth furnace, having a cone 1 made of a metal molybdenum plate, the metal molybdenum plate having a thickness of 0.05-1.5 mm, which is formed on the side wall of the cone 1 The groove and the convex point 2 (the groove and the convex point alternately form a concave-convex shape) and are evenly distributed uniformly on the inner side wall of the tapered cylinder, and the concave-convex depth and the height of the convex point 2 are 0.5-3 mm, the single groove and The distribution density of the convex points is 80-120 per square decimeter, and the grooves and convex points are one or a combination of the following shapes: triangular, rhombic, quadrangular, square, circular, and polygonal. In Fig. 1, 3 is a single crystal placed in the draft tube.

Embodiment 2: A molybdenum plate (after the process) is manufactured into a fixed concave-convex shape having a uniform shape and uniform distribution by a molding process using a special material, and then rolled into a cone. The height of the concave-convex shape vertical concave starting point is 0.5-3 mm, and the monomer concave-convex shape or the convex point distribution density is 80-120 per square centimeter.

Embodiment 3: The processing technology of the molybdenum guide tube according to Embodiment 1 is that the metal molybdenum plate is firstly pressed by the upper mold and the lower mold, and the metal molybdenum plate is formed by hot pressing or cold pressing or heat treatment. Pressing into a concave plate of a certain shape, and then forming a conical cylinder by a certain processing process; the upper and lower molds respectively have correspondingly shaped grooves and convex points, which is a concave and convex molding process. Figure 3 shows a schematic of the mold using the upper and lower mold process.

Embodiment 4: The processing process of the molybdenum guide tube according to Embodiment 1 may further be: firstly pressing a metal molybdenum plate into a concave plate by a drum-type circumferential forming process, and then rolling into a cone; The bumps are evenly arranged, the metal molybdenum plate is lowered to lay a special material as a backing plate, and the metal molybdenum plate is pressed by the roller to form a certain shape of irregularities or grooves and raised points. Figure 4 is a schematic view of the principle of the drum mold.

Embodiment 5: First, spot-welding or welding the columnar material on the surface of the metal molybdenum plate to form a uniformly distributed convex point, and then rolling into a tapered cylinder.

The core of the invention is to form a convex shape with uniform shape, uniform size and evenly distributed on the side wall of the conical tube rolled on the molybdenum metal plate, and the optical slow radiation principle is adopted. The tapered shape of the draft tube itself causes the side wall of the draft tube to deform due to the unevenness and increase the unit area, thereby changing the high temperature distribution inside the draft tube. The description of the parameters such as the shape and the number of the concave and convex and the preparation process are not limited to the present invention. Any uniform uneven shape is formed on the side wall of the tapered cylinder rolled by the molybdenum metal plate to increase the unit area to change the flow. The technical means for the high temperature distribution inside the cylinder are all within the scope of the present invention.