Adjustable guide tube and semiconductor crystal growth device

Abstract

The present invention provides an adjustable guide tube and a semiconductor crystal growth device, wherein the guide tube comprises a fixing part and an adjusting part, the guide tube is barrel-shaped and arranged around the crystal rod, wherein the portion extending outward from the upper end of the fixing part is fixed on the semiconductor growth device, the portion extending downward from the fixing part is an inclined surface gradually approaching the crystal, and the bottom of the fixing part is a plane close to the liquid surface to control the minimum distance from the liquid surface; the adjusting part is located on the inclined surface of the fixing part, and the adjusting part is fixed on the inclined surface of the fixing part by a fixing device, and the adjusting part is used to adjust the minimum distance from the crystal rod as needed. In the present invention, the oxygen content of the crystal can be adjusted by changing the adjusting part of the guide tube without changing other parameters, thereby controlling the quality of the crystal.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor manufacturing, and in particular to an adjustable flow guide tube and a semiconductor crystal growth device. Background Art

[0002] The Czochralski method (Cz) is an important method for preparing silicon single crystals for semiconductors and solar energy. The high-purity silicon material placed in the crucible is heated and melted by a thermal field composed of carbon materials. Then, the seed crystal is immersed in the melt and goes through a series of process steps (seedling, shouldering, equal diameter, finishing, cooling) to finally obtain a single crystal rod.

[0003] During the crystal pulling process, heat shield devices, such as guide tubes (or reflective screens), are often set around the generated silicon crystal rods. On the one hand, they are used to isolate the heat radiation generated by the quartz crucible and the silicon melt in the crucible to the crystal surface during the crystal growth process, so that the axial temperature gradient of the crystal rod is increased and the radial temperature distribution is as balanced as possible, so that the growth rate of the crystal rod is controlled within an appropriate range, and the internal defects of the crystal are controlled at the same time; on the other hand, they are used to guide the inert gas introduced from the upper part of the crystal growth furnace so that it passes through the surface of the silicon melt at a higher flow rate, thereby achieving the effect of controlling the oxygen content and impurity content in the silicon crystal rod.

[0004] In the design process of semiconductor crystal growth equipment, it is often necessary to consider the distance between the heat shield device and the silicon melt liquid surface and the crystal rod to control the axial temperature gradient and radial temperature distribution of the crystal rod. Specifically, in the design process, it is often necessary to consider two important parameters: the minimum distance of the heat shield device liquid surface (hereinafter referred to as the liquid surface distance D2) and the minimum distance between the heat shield device and the crystal rod (hereinafter referred to as the crystal rod distance D1). Figure 1 As shown. Among them, D2 controls the stable growth of silicon crystals between the crystal pulling liquid levels, and D1 controls the temperature gradient of the silicon crystal rod in the axial direction. In order to achieve the stable growth of silicon crystals between the silicon crystal rod and the silicon melt liquid level, the rising speed of the crucible is often controlled to control D2 to be stable within a suitable range. When the heat shield device is fixed, the shape and position of the guide tube are fixed. When the diameter of the silicon crystal rod is constant, D1 must be further reduced to achieve a larger axial temperature gradient of the silicon crystal, and the current traditional guide tube D1 cannot be changed. For example, CN109554750A, a prior art, discloses a method for adjusting the height of the outer screen of a guide tube for a single crystal furnace, and an outer screen and a guide tube of the guide tube. The outer screen and inner screen of the guide tube are assembled in a modular manner, and have the characteristics of adjustable height, which can meet the needs of different thermal fields, and can be replaced separately to save costs, but it only changes D2, but fails to change D1.

[0005] Therefore, it is necessary to provide an adjustable guide tube and a semiconductor crystal growth device to solve the above problems. Summary of the invention

[0006] A series of simplified concepts are introduced in the Summary of the Invention, which will be further described in detail in the Detailed Description of the Invention. The Summary of the Invention does not mean to attempt to define the key features and essential technical features of the claimed technical solution, nor does it mean to attempt to determine the scope of protection of the claimed technical solution.

[0007] In view of the deficiencies in the prior art, the present invention proposes an adjustable guide tube, which includes a fixing portion and an adjusting portion. The guide tube is barrel-shaped and is arranged around the crystal rod, wherein the portion of the upper end of the fixing portion extending outward is fixed on a semiconductor growth device, the portion of the fixing portion extending downward is an inclined surface gradually approaching the crystal, and the bottom of the fixing portion is a plane close to the liquid surface to control the minimum distance from the liquid surface; the adjusting portion is located on the inclined surface of the fixing portion, and the adjusting portion is fixed to the inclined surface of the fixing portion by a fixing device, and the adjusting portion is used to adjust the minimum distance from the crystal rod as needed.

[0008] Optionally, the fixing portion and the adjusting portion are integrally formed, and the adjusting portion is a portion cut from the fixing portion.

[0009] Optionally, the fixing part and the adjusting part are made of graphite material.

[0010] An adjustable flow guide tube, comprising a fixed portion, a middle portion and an adjusting portion, the flow guide tube being barrel-shaped and arranged around a crystal rod, wherein the portion extending outward from the upper end of the fixed portion is fixed on a semiconductor growth device, the portion extending downward from the fixed portion is an inclined surface gradually approaching the crystal, and the bottom of the fixed portion is a plane close to the liquid surface to control the minimum distance from the liquid surface; the middle portion is located on the inclined surface of the fixed portion, the middle portion is suspended on the fixed portion, and the bottom of the middle portion is flush with the bottom of the fixed portion to control the minimum distance from the liquid surface; the adjusting portion is located on the inclined surface of the middle portion, the adjusting portion is fixed to the inclined surface of the middle portion by a fixing device, and the adjusting portion is used to adjust the minimum distance from the crystal rod as needed.

[0011] Optionally, the middle portion and the adjusting portion are integrally formed, and the adjusting portion is a portion cut from the middle portion.

[0012] Optionally, the fixing portion, the middle portion and the adjusting portion are made of graphite material.

[0013] Optionally, the fixing device is a bolt.

[0014] Optionally, the fixing portion further includes an intermediate carbon material solidified felt located in the middle thereof.

[0015] Optionally, the guide tube is formed by splicing one or more arc-shaped components.

[0016] A semiconductor crystal growth device comprises a furnace body, a crucible, a pulling device and the above-mentioned adjustable flow guide tube.

[0017] The present invention provides an adjustable guide tube and a semiconductor crystal growth device, which can flexibly change the guide tube accessory adjustment part of the distance from the crystal rod. Without changing other parameters, the distance between the guide tube and the crystal rod can be changed by changing the adjustment part of the guide tube, thereby adjusting the oxygen content of the crystal, thereby controlling the quality of the crystal. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The following drawings of the present invention are used as part of the present invention for understanding the present invention. The drawings show embodiments of the present invention and their descriptions, and are used to explain the device and principle of the present invention. In the drawings,

[0019] Figure 1 It is a structural schematic diagram of a guide tube and a semiconductor crystal growth device according to an embodiment of the prior art;

[0020] Figure 2 It is a schematic structural diagram of a guide tube and a semiconductor crystal growth device according to an embodiment of the present invention;

[0021] Figure 3A A schematic structural diagram of a guide tube according to an embodiment of the prior art;

[0022] Figure 3B For Figure 3A A schematic structural diagram of an adjustable guide tube according to an embodiment of the present invention;

[0023] Figure 4A is a schematic structural diagram of a flow guide tube according to an embodiment of the present invention;

[0024] Figure 4B For Figure 4A A schematic diagram of the structure of the middle part of the guide tube can be adjusted on the basis of FIG.

[0025] Figure 4C For Figure 4B A schematic diagram of a structure of an adjustment portion of an adjustable guide tube according to the present invention;

[0026] Figure 5 is a three-dimensional diagram of a guide tube according to an embodiment of the present invention;

[0027] Figure 6 This is a comparison diagram of oxygen content before and after adjustment of the adjustment portion of the guide tube according to one embodiment of the present invention;

[0028] Among them: 1—crystal rod;

[0029] 2—melt;

[0030] 3—guide tube;

[0031] 31 - fixed part;

[0032] 32—Regulation Department;

[0033] 33—bolt;

[0034] 34—middle part;

[0035] 35—intermediate carbon material solidified felt;

[0036] 4—Crucible. DETAILED DESCRIPTION

[0037] In the following description, a large number of specific details are provided to provide a more thorough understanding of the present invention. However, it is apparent to those skilled in the art that the present invention can be implemented without one or more of these details. In other examples, in order to avoid confusion with the present invention, some technical features well known in the art are not described.

[0038] In order to fully understand the present invention, detailed steps will be presented in the following description to illustrate the structure proposed by the present invention. Obviously, the implementation of the present invention is not limited to the specific details familiar to those skilled in the art. The preferred embodiments of the present invention are described in detail below, but in addition to these detailed descriptions, the present invention may also have other embodiments.

[0039] It should be understood that when the terms "include" and / or "comprises" are used in this specification, they indicate the existence of the stated features, integers, steps, operations, elements and / or components, but do not exclude the existence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0040] The adjustable guide tube and the semiconductor crystal growth device of the present invention are further described below in conjunction with the accompanying drawings.

[0041] The guide tube is used as a thermal field component to reflect the surface heat of the solution and adjust the temperature gradient to obtain different crystal qualities. It also has a great influence on the flow of argon gas. The performance of argon gas flow affects the distribution of oxygen concentration in the crystal. Therefore, without changing other parameters, changing the structure of the guide tube can adjust the oxygen content of the crystal.

[0042] like Figure 1As shown in the figure, the distance D2 between the guide tube and the liquid surface and the distance D1 between the guide tube and the crystal are the key factors affecting the flow rate of the argon gas flow over the melt surface. Usually, after the guide tube is installed, since the target crystal rod diameter is stable, the guide tube is a ring-shaped fixture, D1 cannot change, and D2 can change as the guide tube rises or falls.

[0043] like Figure 2 As shown, in an embodiment of the adjustable flow guide tube, the flow guide tube 3 includes a fixing portion 31 and an adjusting portion 32, the flow guide tube is barrel-shaped and is arranged around the crystal rod 1, wherein the portion of the upper end of the fixing portion extending outward is fixed on the crucible 4, the portion of the fixing portion extending downward is an inclined surface gradually approaching the crystal, and the bottom of the fixing portion is a plane close to the liquid surface of the melt 2 to control the minimum distance D2 from the liquid surface; the adjusting portion is located on the inclined surface of the fixing portion, the adjusting portion is fixed on the inclined surface of the fixing portion by a fixing device, and the adjusting portion is used to adjust the minimum distance D1 between the fixing portion and the crystal rod as needed.

[0044] like Figure 3A As shown, the fixing part and the adjusting part are integrally formed. Figure 3B As shown, the adjusting portion is a portion cut from the fixing portion, that is, a strip-shaped portion cut from the fixing portion of the existing guide tube is used as the adjusting portion.

[0045] In one embodiment, the fixing portion and the adjusting portion are made of graphite material.

[0046] like Figures 4A-4C As shown, an adjustable guide tube, the guide tube 3 includes a fixed part 31, a middle part 34 and an adjusting part 32, the guide tube is barrel-shaped and is arranged around the crystal rod 1, wherein the part extending outward from the upper end of the fixed part is fixed on the semiconductor growth device, the part extending downward from the fixed part is an inclined surface gradually approaching the crystal, and the bottom of the fixed part is a plane close to the liquid surface to control the minimum distance from the liquid surface; the middle part is located on the inclined surface of the fixed part, the middle part is suspended on the fixed part, and the bottom of the middle part is flush with the bottom of the fixed part to control the minimum distance from the liquid surface; the adjusting part is located on the inclined surface of the middle part, the adjusting part is fixed on the inclined surface of the middle part by a fixing device, and the adjusting part is used to adjust the minimum distance from the crystal rod as needed.

[0047] In one embodiment, the fixing portion, the middle portion and the adjusting portion are made of graphite material.

[0048] like Figure 4C As shown, in one embodiment, the fixing device is a bolt 33. The position of the adjusting portion can be adjusted as needed.

[0049] like Figure 4AAs shown, in one embodiment, the fixing portion further includes an intermediate carbon material solidified felt 35 located in the middle thereof.

[0050] like Figure 5 As shown, in one embodiment, the guide tube is formed by splicing one or more arc-shaped components, which is a circular arc-shaped component here.

[0051] A semiconductor crystal growth device comprises a furnace body, a crucible 4, a pulling device and the above-mentioned adjustable flow guide tube 3.

[0052] The semiconductor crystal growth device includes a furnace body, a crucible 4 is arranged in the furnace body, a heater for heating the crucible 4 is arranged outside the crucible 4, and a silicon melt 2 is contained in the crucible 4. A pulling device is arranged on the top of the furnace body, and the seed crystal is pulled out of the silicon melt liquid surface by the pulling device, and a heat shield device is arranged around the silicon crystal rod. Exemplarily, the heat shield device can be a guide tube 3, which is set to a conical barrel shape. As a heat shield device, on the one hand, it is used to isolate the heat radiation generated by the quartz crucible and the silicon melt in the crucible to the crystal surface during the crystal growth process, improve the cooling rate and axial temperature gradient of the crystal rod, and increase the number of crystal growth. On the other hand, it affects the thermal field distribution on the surface of the silicon melt, and avoids the axial temperature gradient difference between the center and the edge of the crystal rod is too large, so as to ensure the stable growth between the crystal rod and the silicon melt liquid surface; at the same time, the guide tube is also used to guide the inert gas introduced from the upper part of the crystal growth furnace, so that it passes through the silicon melt surface at a larger flow rate, so as to achieve the effect of controlling the oxygen content and impurity content in the crystal. The minimum distance between the bottom of the guide tube and the silicon melt surface is the minimum distance between the heat shield device and the silicon melt, called the liquid surface distance, denoted by D2; the minimum distance between the guide tube closest to the silicon crystal rod and the silicon crystal rod is the minimum distance between the heat shield device and the silicon crystal rod, called the crystal rod distance, denoted by D1.

[0053] In order to achieve stable growth of silicon crystal rods, a driving device for driving the crucible to rotate and move up and down is also provided at the bottom of the furnace body. The driving device drives the crucible to keep rotating during the crystal pulling process in order to reduce the thermal asymmetry of the silicon melt and make the silicon crystal column grow with equal diameter; the driving device drives the crucible to move up and down in order to control the liquid level distance D2 within a reasonable range and maintain the thermal radiation stability of the silicon melt liquid surface to meet the requirements of stable growth of silicon crystal rods. Exemplarily, the driving device drives the crucible to move up and down to control the liquid level distance D2 between 20mm and 80mm.

[0054] However, when the heat shield device is fixed, the shape and position of the guide tube are fixed, and the shape of the silicon crystal rod is constant, it is difficult to further reduce D1 to achieve a larger axial temperature gradient of the silicon crystal rod through the control of the device itself.

[0055] For this purpose, see Figure 2In the semiconductor crystal growth device of the present invention, an adjustment part is provided at the lower end of the guide tube, which serves as a heat shield device to adjust the thermal field distribution between the silicon melt liquid surface and the crystal rod. Compared with the case without the adjustment part, the minimum distance D1 between the heat shield device and the silicon crystal rod changes from the initial minimum distance between the guide tube and the crystal rod to the minimum distance between the adjustment part and the crystal rod, thereby reducing the minimum distance D1 between the heat shield device and the crystal rod, and allowing the heat shield device to re-adjust the radiation energy between the silicon crystal rod and the heat shield device, and between the heat shield device and the silicon melt liquid surface, thereby adjusting the heat flow rate intensity and distribution on the crystal surface, increasing the axial temperature gradient of the center and edge of the silicon crystal rod, and effectively improving the crystal growth rate; at the same time, the difference in the axial temperature gradient between the center and the edge is reduced, which is conducive to the stable growth of the crystal on the silicon melt liquid surface. At the same time, the adjustment device also reduces the channel size for argon to flow through the guide tube to the silicon melt surface, thereby adjusting the gas flow rate of argon from the silicon melt surface in the radial direction, regulating the oxygen content of the growing crystal, and further improving the quality of crystal pulling.

[0056] Furthermore, when the adjustment portion is provided, the minimum distance D1 between the heat shield device and the silicon crystal rod is reduced, so that the radiation heat transfer from the silicon melt liquid surface to the crystal rod is reduced, and the axial temperature gradient of the crystal rod is increased, which is beneficial to improving the growth rate of the crystal. At the same time, the power consumption of the heater for crystal growth can also be reduced; the adjustment portion is provided between the guide tube and the crystal rod, which can also reduce the radiation heat transfer from the guide tube to the crystal rod, thereby reducing the difference in the axial temperature gradient between the center and edge of the crystal rod, so that the process window (pulling speed range) of crystal growth is widened, and the yield of the product is improved.

[0057] like Figure 3B As shown in Figure 2, when the adjustable flow guide tube adjusts D1 to D1', the oxygen content decreases significantly. Figure 6 By reducing D1, the flow rate of the surface inert gas argon gas increases, the pressure on the surface of the crystal rod decreases, oxygen overflows from the silicon, and the oxygen content in the crystal decreases. During the crystal growth process, D1 is adjusted to change the distribution of oxygen content.

[0058] The present invention can flexibly change the guide tube attachment at a distance from the crystal rod, can fix the adjustment part with bolts, and can increase the possibility of setting different process parameters D1.

[0059] The original structure of the integral heat shield is a ring structure of inner graphite, outer graphite and middle carbon material solidified felt, and the three are assembled from the inside to the outside. Now it is changed to a separate fixed part and a suspended middle part. For this purpose, the inner graphite is changed into two parts and connected with bolts. At this time, different inner diameters are replaced to obtain different D1 effects.

[0060] The size design of the adjustment part can be changed and replaced according to the shape of the guide tube and the required D1.

[0061] Unless otherwise defined, the technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art in the technical field of the present invention. The terms used herein are only for describing specific implementation purposes and are not intended to limit the present invention. Terms such as "setting" and the like appearing in this article can indicate that one component is directly attached to another component, or that one component is attached to another component through an intermediate. Features described in this article in one embodiment may be applied to another embodiment alone or in combination with other features, unless the feature is not applicable in the other embodiment or otherwise specified.

[0062] The present invention has been described by the above embodiments, but it should be understood that the above embodiments are only for the purpose of example and description, and are not intended to limit the present invention to the scope of the described embodiments. In addition, it can be understood by those skilled in the art that the present invention is not limited to the above embodiments, and more variations and modifications can be made according to the teachings of the present invention, and these variations and modifications all fall within the scope of the protection claimed by the present invention. The protection scope of the present invention is defined by the attached claims and their equivalents.

Claims

1. An adjustable guide tube, characterized in that: The guide tube includes a fixing part and an adjusting part. The guide tube is barrel-shaped and is arranged around the crystal rod. The portion of the fixing portion extending outward from the upper end is fixed on the semiconductor growth device, the portion of the fixing portion extending downward is an inclined surface gradually approaching the crystal, and the bottom of the fixing portion is a plane close to the liquid surface to control the minimum distance from the liquid surface; The adjusting part is located on the inclined surface of the fixing part, and the adjusting part is fixed on the inclined surface of the fixing part by a fixing device. The adjusting part is used to adjust the minimum distance between the adjusting part and the crystal rod as needed; the fixing part and the adjusting part are integrally formed, and the adjusting part is a part cut from the fixing part.

2. The adjustable guide tube according to claim 1, characterized in that: The fixing part and the adjusting part are made of graphite material.

3. An adjustable guide tube, characterized in that: The guide tube includes a fixing part, a middle part and an adjusting part. The guide tube is barrel-shaped and arranged around the crystal rod. The portion of the fixing portion extending outward from the upper end is fixed on the semiconductor growth device, the portion of the fixing portion extending downward is an inclined surface gradually approaching the crystal, and the bottom of the fixing portion is a plane close to the liquid surface to control the minimum distance from the liquid surface; The middle part is located on the inclined surface of the fixed part, the middle part is suspended on the fixed part, and the bottom of the middle part is flush with the bottom of the fixed part to control the minimum distance from the liquid surface; The adjusting portion is located on the inclined surface of the middle portion, and the adjusting portion is fixed on the inclined surface of the middle portion by a fixing device. The adjusting portion is used to adjust the minimum distance between the adjusting portion and the crystal rod as needed; the middle portion and the adjusting portion are integrally formed, and the adjusting portion is a portion cut from the middle portion.

4. The adjustable guide tube according to claim 3, characterized in that: The fixing portion, the middle portion and the adjusting portion are made of graphite material.

5. The adjustable flow guide tube according to any one of claims 1 to 4, characterized in that: The fixing device is a bolt.

6. The adjustable flow guide tube according to any one of claims 1 to 4, characterized in that: The fixing portion further includes an intermediate carbon material solidified felt located in the middle thereof.

7. The adjustable flow guide tube according to any one of claims 1 to 4, characterized in that: The guide tube is formed by splicing one or more arc-shaped parts.

8. A semiconductor crystal growth device, characterized in that: The invention comprises a furnace body, a crucible, a pulling device and an adjustable flow guide tube according to any one of claims 1 to 7.

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