Cylindrical silicon ingot manufacturing method

Abstract

To provide a cylindrical silicon ingot manufacturing method.SOLUTION: A cylindrical ingot manufacturing method according to the present invention includes the steps of: supplying silicon raw material into a crucible and heating the crucible to melt the silicon raw material; supplying a seed crystal having one end fastened to a seed shaft into the crucible; and moving the seed crystal from a lower part to an upper part of the crucible as the crucible rotates in one direction relative to the seed shaft and the seed shaft moves up while rotating in the other direction.EFFECT: According to the present invention, a cylindrical silicon ingot for growing a ring-shaped seed crystal can be manufactured, and since the cylindrical ingot having an inner diameter is formed, a wafer ring can be manufactured from the ingot without coring work, thereby, an amount of raw material fed into the crucible can be reduced to lower the prime cost, thereby minimizing workers' injury, decreasing the number of process steps, improving process speed and efficiency, and minimizing the rejection rate.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method for producing an ingot, and more particularly to a method for producing a cylindrical silicon ingot. [Background technology]

[0002] Silicon ingot manufacturing technology for producing wafers, the basic material for semiconductor devices, has remained vital throughout the semiconductor industry, and is used to manufacture 12-inch wafers as well as wafer retainer rings, showerheads, and other products.

[0003] Most of the silicon ingots produced are used in wafers. Wafers are made by slicing single crystal ingots, which are manufactured by growing silicon (Si) or gallium arsenide (GaAs) using the Czochralski method, through a wire process, and then polishing them to use as substrates for manufacturing chips.

[0004] The showerhead is manufactured to be thicker than the wafer, and has fine through-holes formed on the entire surface except for the edges to allow gas to flow during semiconductor manufacturing.

[0005] In this way, the wafer and showerhead are manufactured in a columnar shape without an inner diameter, and have only an outer diameter and a thickness.

[0006] However, manufacturing a wafer retaining ring with an inner diameter using a cylindrical ingot manufactured using conventional silicon ingot manufacturing technology poses various problems due to the additional process of removing the inner core. Specifically, before performing the coring process to remove the inner core to form the inner diameter of the wafer retaining ring, an additional cutting process is required to reduce the length of the ingot to fit the coring process. If the core hole cup cannot maintain its perpendicularity while penetrating the ingot during the coring process, the inner diameter may be incorrectly sized. To solve this problem, the ingot must be turned upside down and the coring process performed twice, which requires an additional process step. However, even after this additional step, it is difficult to accurately align the surfaces. This means there is a risk of a high defect rate during the ingot coring process. In addition, the inner material removed after the coring process is discarded entirely because it cannot be used in many applications due to its size, resulting in a large amount of wasted raw material.

[0007] In order to solve the above-mentioned problems, the present invention provides a method for manufacturing a cylindrical silicon ingot. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Republic of Korea Patent No. 10-1631368 (Registered June 10, 2016) [Patent Document 2] Republic of Korea Patent No. 10-1714751 (registered on March 3, 2017) Summary of the Invention [Problem to be solved by the invention]

[0009] A technical object of the present invention is to provide a method for manufacturing a cylindrical ingot that can manufacture a wafer retainer ring having an inner diameter without a coring operation.

[0010] Another technical object of the present invention is to provide a method for growing a ring-shaped seed crystal to produce a cylindrical ingot. [Means for solving the problem]

[0011] To achieve the above object, the present invention provides a method for producing an ingot, comprising the steps of: supplying a silicon raw material into a crucible and heating the crucible to melt the silicon raw material; fastening one end of a seed crystal having a ring-shaped cross section to a seed shaft and supplying the seed crystal into the crucible; and rotating the crucible in one direction around the seed shaft and moving the seed crystal from the bottom to the top of the crucible by rotating the crucible in the other direction and raising the seed shaft. [Effects of the Invention]

[0012] According to the present invention, a cylindrical silicon ingot can be produced for growing a ring-shaped seed crystal.

[0013] According to the present invention, a cylindrical silicon ingot having an inner diameter is formed, so that a wafer retainer ring can be manufactured from the ingot without a coring operation.

[0014] According to the present invention, since wafer retainer rings are manufactured from cylindrical ingots, the amount of raw material put into the crucible can be reduced, thereby reducing costs.

[0015] According to the present invention, by manufacturing a cylindrical ingot using a small amount of raw material, the size of the crucible is reduced, and accordingly, the size of the refractory material and heater surrounding the crucible is also reduced, thereby minimizing the cost of building manufacturing facilities.

[0016] According to the present invention, a cylindrical silicon ingot having an inner diameter is formed, eliminating the need for a coring process, thereby minimizing injuries to workers, reducing process steps to improve process speed and efficiency, minimizing the defect rate, and reducing manufacturing costs. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a flowchart of a conventional method for producing a cylindrical ingot. [Figure 2] 1 is a flowchart of a method for manufacturing a cylindrical ingot according to an embodiment of the present invention. [Figure 3] 1A and 1B are perspective and cross-sectional views of a seed crystal according to an embodiment of the present invention; [Figure 4] 1 is a perspective view of an ingot produced according to the prior art and an embodiment of the present invention; FIG. [Figure 5] 1 is a diagram illustrating a process for manufacturing a cylindrical ingot according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0018] The objects and advantages of the present invention will become more apparent through the following detailed description, but the objects and advantages of the present invention are not limited to the following description. Furthermore, in the description of the present invention, if it is determined that a detailed description of a known technology related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description will be omitted.

[0019] Generally, single crystal growth involves growing a crystal by contacting a single crystal seed with a polycrystal melt.

[0020] At this time, the characteristics of the single crystal are formed depending on the seed used, and unit crystals are formed based on this.

[0021] The seed is generally provided in the form of a square rod with a width of 10 mm, a length of 100 mm, and is connected to the upper rotating shaft of a crucible and brought into contact with the molten solution to grow into an ingot.

[0022] In the present invention, instead of the general square rod-shaped seed as described above, a cylindrical ingot is manufactured by growing a crystal using a ring-shaped seed having an inner diameter in cross section.

[0023] Furthermore, the present invention is not limited to growing a polycrystalline molten solution, and can be carried out using any silicon raw material, regardless of whether it is a single crystal or a polycrystal.

[0024] Specifically, the seed shaft, to which the seed is fastened, and the crucible shaft, which supports the crucible containing the molten material, rotate in opposite directions, and the seed shaft is pulled upward to form a single crystal ingot.

[0025] At this time, if the ingots grow larger due to the capillary effect, the inner diameter may disappear and the lower part may become a rod-like shape with no inner diameter. This can be prevented by adjusting the rotation speed and pulling speed of the seed shaft.

[0026] In addition, since the ingot manufacturing method according to the present invention uses a ring-shaped seed crystal, the rotation speed and pulling speed of the ingot are increased by 10 to 40% compared to the conventional manufacturing method, and the ingot can be grown at a speed that is 10 to 40% faster than the conventional manufacturing method, thereby preventing the ingot from losing its inner diameter.

[0027] Hereinafter, a method for manufacturing a cylindrical ingot according to an embodiment of the present invention will be described in more detail with reference to the accompanying drawings.

[0028] In the drawings, parts not related to the present invention are omitted in order to clearly disclose the present invention, and the same or similar reference numerals in the drawings indicate the same or similar components.

[0029] This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth below.

[0030] FIG. 1 is a flow chart of a conventional method for producing a cylindrical ingot, and FIG. 4 is a perspective view of an ingot produced by the conventional method and an embodiment of the present invention.

[0031] Referring to FIG. 1, the conventional cylindrical ingot manufacturing method is also comprised of a melting step (S100), a supplying step (S200), and a growing step (S300), similar to the ingot manufacturing method according to the embodiment of the present invention.

[0032] However, since the conventional technique uses a square rod-shaped seed crystal 20', it produces a cylindrical ingot 30' having only a first diameter d1, which is the outer diameter, rather than a cylindrical ingot having an inner diameter d3.

[0033] Specifically, in Figure 4 1, an ingot 30' produced by the ingot production method according to the prior art is produced in a cylindrical shape having a first diameter d1.

[0034] On the other hand, in Figure 4 1, the ingot 30 manufactured by the ingot manufacturing method according to one embodiment of the present invention is manufactured in a cylindrical shape having a second diameter d2 and an inner diameter d3.

[0035] Typically, the wafer retainer ring used in the 12-inch wafer manufacturing process has an inner diameter of 296 mm, so it would be preferable for the ingot 30 manufactured by the ingot manufacturing method according to one embodiment of the present invention to also be formed so that the inner diameter d3 is 296 mm.

[0036] Also, it would be preferable to form the second diameter d2 to have a value of 350 mm.

[0037] Hereinafter, the shape of the seed crystal and the method for manufacturing the cylindrical ingot according to one embodiment of the present invention will be described in detail with reference to FIGS. 2, 3 and 5. FIG.

[0038] FIG. 2 is a flowchart of a cylindrical ingot manufacturing method according to one embodiment of the present invention, FIG. 3 is an oblique view and a cross-sectional view of a seed crystal according to one embodiment of the present invention, and FIG. 5 is a step diagram of a cylindrical ingot manufacturing method according to one embodiment of the present invention.

[0039] Referring first to FIG. 5, a cylindrical ingot manufacturing method according to one embodiment of the present invention comprises a melting step (S100), a supplying step (S200), and a growing step (S300), and the growing step (S100) may be performed including a first speed adjusting step (S310) and a second speed adjusting step (S320).

[0040] The melting step (S100) is a step of supplying silicon raw material 10 into the crucible 100 and heating the crucible 100 to melt the silicon raw material 10, and the supplying step (S200) is a step of supplying a seed crystal 20, one end of which is fastened to a seed shaft 21, into the crucible.

[0041] In this case, it is preferable that the seed crystal 20 has a ring-shaped cross section, and that the lower surface has an inner diameter in the range of 270 to 290 mm and an outer diameter in the range of 350 to 600 mm.

[0042] The specific shape of the seed crystal 20 will be described later with reference to FIG.

[0043] The growth step (S300) is a step in which the crucible 100 rotates in one direction based on the seed axis 21, and the seed axis 21 rotates in the other direction and rises, thereby moving the seed crystal 20 from the bottom to the top of the crucible 100.

[0044] In a preferred embodiment, the growth step (S300) may be implemented to further include a first speed adjustment step (S310) for adjusting the speed at which the seed shaft 21 rotates in the other direction so that the seed crystal 20 forms an ingot according to a predetermined shape, and a second speed adjustment step (S320) for adjusting the speed at which the seed shaft 21 moves from the bottom to the top of the crucible 100.

[0045] At this time, it is preferable that the rotation speed is in the range of 10 to 30 rpm and the pulling speed is in the range of 0.3 to 0.8 mm / min.

[0046] In this way, by providing the first speed control step (S310) and the second speed control step (S320), it is possible to prevent the ingots 30 growing in the growth step (S300) from becoming larger due to the capillary effect, which would otherwise cause the inner diameter to disappear, and to form the ingots 30 according to a predetermined shape.

[0047] In order to form the cylindrical ingot 30 having such an inner diameter, the seed crystal 20 according to the embodiment of the present invention is provided so that its cross section has a ring shape.

[0048] Specifically, the seed shaft 21 is provided so that a cross section cut perpendicular to the longitudinal direction thereof has a ring shape.

[0049] More specifically, the seed crystal 20 is shown in FIG. 3, the upper surface of the flattened hemispherical shape is shown. 3, may be implemented with a frustoconical profile, as shown in FIG. <c>As shown in FIG.

[0050] Thus, the seed crystal 20 according to the present invention is not limited by its external shape, but may simply have a cavity formed therein and have a ring-shaped cross section cut perpendicular to the longitudinal direction of the seed axis 21.

[0051] Furthermore, since the seed shaft 21 rotates, the cross section of the seed crystal 20 does not have to be ring-shaped, but may be formed with a cavity therein and have an outer diameter and an inner diameter.

[0052] Also, the seed crystal 20 is preferably provided with one or more hollows H penetrating at least one of the peripheral surface or the top surface.

[0053] Specifically, the seed crystal 20 is< / c> and 3, the hollow H is formed so as to penetrate the peripheral surface of the seed crystal 20. <c>When the seed crystal 20 has a cylindrical outer shape as shown in FIG.

[0054] However, without being limited thereto, the hollow H can maintain a vacuum atmosphere inside the ingot formed by discharging gas generated during ingot growth through the hollow H, thereby preventing bubbles from being generated on the surface of the ingot.

[0055] At this time, the hollow H may be formed like a pinhole, but is not limited thereto, and may be formed to have various shapes and diameters.

[0056] In addition, it is preferable that the hollow H be formed at a position symmetrical with respect to the center of the seed crystal so that the seed crystal can rotate while maintaining balance during the process of growing an ingot and form an ingot of a uniform shape.

[0057] The above-described preferred embodiments of the present invention have been disclosed for illustrative purposes, and those skilled in the art having ordinary skill in the art will be able to make various modifications, changes, and additions within the spirit and scope of the present invention, and it should be understood that such modifications, changes, and additions fall within the scope of the following claims.

[0058] Furthermore, since various substitutions, modifications and changes can be made by a person having ordinary knowledge in the technical field to which the present invention pertains without departing from the technical spirit of the present invention, the present invention is not limited to the above-described embodiments and the accompanying drawings.

[0059] In the exemplary systems described above, methods are described based on flowcharts with a series of steps or blocks, but the present invention is not limited to the order of steps, and some steps may occur in a different order or simultaneously with other steps than those described above. Additionally, those skilled in the art will understand that the steps shown in the flowcharts are not exclusive, and that other steps may be included or one or more steps in the flowcharts may be omitted without affecting the scope of the present invention. [Explanation of symbols]

[0060] 100: Crucible 10: Silicon raw materials 20: Seed crystal 21: Seed axis 30: Ingot d1: 1st diameter d2: 2nd diameter d3: inner diameter H:Hollow< / c>

Claims

1. A melting step (S100) of supplying a silicon raw material into a crucible and heating the crucible to melt the silicon raw material; A step (S200) of fastening one end of a seed crystal having a ring-shaped cross section to a seed shaft and supplying the seed crystal into the crucible; and A growing step (S300) in which the crucible rotates in one direction based on the seed axis and the seed axis rotates in the other direction while ascending, thereby moving the seed crystal from the bottom to the top of the crucible; Including, The seed crystal is It has a cylindrical shape, A method for producing a cylindrical ingot, characterized in that the ingot has one or more hollows extending through its top surface.

2. The growth step (S300) The seed crystal forms an ingot according to a predetermined shape. a first speed adjusting step (S310) of adjusting the speed at which the seed shaft rotates in the other direction; and a second speed adjusting step (S320) of adjusting the speed at which the seed shaft moves from the bottom to the top of the crucible; 2. The method of claim 1, further comprising:

3. The speed at which the seed shaft rotates in the other direction is in the range of 10 to 30 rpm; 2. The method for manufacturing a cylindrical ingot according to claim 1, wherein the speed at which the seed axis moves from the bottom to the top of the crucible is in the range of 0.3 to 0.8 mm / min.

4. The lower surface of the seed crystal is an inner diameter in the range of 270 to 290 mm; and outer diameter in the range of 350-600 mm; 2. The method for manufacturing a cylindrical ingot according to claim 1, comprising:

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