Generally, as shown in FIG. 1, a silicon ingot growth apparatus includes a chamber unit 10, in which polysilicon is melted, and a growth tower unit 20, in which the molten polysilicon is brought into contact with a seed crystal, which slowly rises and thus grows as a silicon ingot having a predetermined diameter.
Furthermore, a quartz crucible 12, which melts polysilicon, is rotatably installed in the chamber unit 10. A heater 14 is provided outside the quartz crucible to heat it. A thermal shield wall 16 is provided outside the heater to prevent heat from being emitted to the outside of the chamber unit.
Typically, the chamber unit 10, having the above-mentioned construction, includes a base plate, a main body and a lid. Each of the base plate, the main body and the lid has a cooling system therein to prevent it from being heated by the heater.
The base plate of the conventional technique is shown in FIGS. 2 and 3.
Referring to these drawings, the conventional base plate 100 includes an upper plate 110 and a lower plate 120 which are spaced apart from each other by a predetermined distance such that cooling water flows in a space defined between them. The base plate 100 further includes a side plate 130 which forms the sidewall of the base plate 100 and seals it.
Furthermore, a shaft coupling hole 140, through which a shaft to rotate the quartz crucible is inserted, is formed at a central position through the base plate 100. Electrode rod assembly holes 150 and 152, through which electrode rods to heat the quartz crucible are mounted, are formed at predetermined positions through the base plate 100. As well, vacuum creation holes 160, to which a vacuum pump to create a vacuum in the chamber is connected, are formed at predetermined positions through the base plate 100. The electrode rod assembly holes 150 and 152 are classified into the side electrode rod assembly holes 150 and the lower electrode rod assembly holes 152.
The cooling system is provided in the base plate 100 having the above-mentioned structure. In detail, an injection hole 102, through which cooling water is injected into the chamber, is formed in the base plate 100 at a position adjacent to the center thereof. A discharge hole 104, through which the cooling water is discharged, is formed in the base plate 100 at a predetermined position adjacent to the outer edge of the base plate 100. Furthermore, a guide line 170 is provided in the base plate 100, such that the flow path of cooling water, which is injected through the injection hole 102, forms a spiral configuration while the cooling water flows to the discharge hole 104, thus preventing the cooling water from directly and linearly flowing towards the discharge hole 104. Therefore, cooling water, which is injected into the chamber through the injection hole 102, flows along the guide line 170 and evenly spreads throughout the overall area of the base plate 100 before being discharged through the discharge hole 104. Of course, a cooling water circulation system, in which the discharged cooling water is again supplied to the injection hole 102 after passing through a separate process, is provided.
However, in the conventional base plate having the cooling system, because the guide line has an unevenly curved shape due to the electrode rod assembly holes and the vacuum pump connection holes, there is a problem in that stagnation due to vortices occurs near unevenly curved parts of the guide line. Particularly, stagnation mainly occurs in portions (H) indicated by hatching in FIG. 2. Such stagnation causes a partial temperature drop in the chamber, thus resulting in a relatively sudden temperature rise, so that problems, such as defective products, may occur during a production process. Furthermore, with the passage of time, due to metal corrosion, cooling water leakage may occur.
Meanwhile, the lid of the chamber unit according to the conventional technique is shown in FIG. 4.
Referring to this drawing, the conventional lid 300 defines therein a space, in which cooling water flows.
Furthermore, an observation window 310 is provided at a predetermined position in the lid 300 to allow a user to observe the interior of the chamber unit 10. A typical camera port 320, a diameter control port 330, a polysilicon passing port 340, and a lift port 350 are provided at predetermined positions in the lid 300.
The lid 300 having the above-mentioned structure has a cooling system therein. In detail, an injection hole 302, through which cooling water is supplied, is formed at a lower position in the lid 300. A discharge hole 304, through which the cooling water is discharged, is formed at an upper position in the lid 300. Thus, the cooling water, which is injected through the injection hole 302, flows in a clockwise direction, as indicated by the arrows in the drawing, and spreads upwards throughout the overall area of the lid 300 before being discharged through the discharge hole 304. Of course, a cooling water circulation system, in which the discharged cooling water is again supplied to the injection hole 302 after passing through a separate process, is provided.
However, in the conventional lid with the cooling system having the above-mentioned structure, when cooling water, which is injected through the injection hole, spins in the direction indicated by the arrows of the drawing and spreads upwards, because this is backflow, that is, flow from a lower position to an upper position, the flow speed of the cooling water changes. Thereby, vortices occur. As well, because the ports interfere with the flow of the cooling water while the cooling water is discharged through the discharge hole, stagnation due to vortices occurs near curved parts of the ports.
Particularly, FIG. 4 shows that stagnation mainly occurs in portions (H) indicated by hatching. Of course, such stagnation causes a partial temperature drop in the chamber, thus resulting in a relatively sudden temperature rise, so that problems, such as defective products, may occur during a production process. Furthermore, with the passage of time, due to metal corrosion, cooling water leakage may occur.