Single crystal furnace

Abstract

The utility model discloses a single crystal furnace which comprises a crucible; the water cooling screen is located above the crucible and is provided with a middle channel penetrating up and down, and the middle channel is arranged opposite to the opening of the crucible; the feeding cylinder is fixedly arranged relative to the water cooling screen, and a bottom opening of the feeding cylinder is opposite to a middle channel of the water cooling screen and is higher than the top surface of the middle channel of the water cooling screen; and the ceramic cone can be controlled to move upwards so as to block the bottom opening of the feeding cylinder, and can be controlled to move downwards so as to release the bottom opening of the feeding cylinder. The supplementing and mixing amount is accurate and controllable.

Description

Technical Field

[0001] This utility model relates to the field of semiconductor manufacturing equipment, specifically to a single crystal furnace. Background Technology

[0002] In existing single-crystal furnaces, the bottom of the feeding cylinder is close to the bottom of the water-cooled screen, and the bottom of the water-cooled screen is close to the opening of the crucible, used to add silicon (or other semiconductor materials) and dopants to the crucible. The dopants are, for example, doped master alloys or pure elements. The dopants are used to control the resistivity of the pulled single-crystal silicon.

[0003] The inventors discovered that some dopants (such as high-purity antimony) have low melting points. For example, during the melting process, dopants are prone to volatilization and require replenishment. During the replenishment process, dopants may also melt or volatilize, and some dopants may adhere to the bottom of the feeding cylinder, making it difficult to accurately control the doping amount. Utility Model Content

[0004] This invention provides a single crystal furnace for precisely controlling the doping amount during supplementary doping.

[0005] The technical solution of this utility model is as follows: A single crystal furnace, comprising:

[0006] crucible;

[0007] A water-cooled screen, located above the crucible, has a central channel running vertically through the crucible, and the central channel is positioned opposite to the opening of the crucible.

[0008] A feeding cylinder is fixedly installed relative to the water-cooled screen, with its bottom opening opposite to the middle channel of the water-cooled screen and higher than the top surface of the middle channel of the water-cooled screen.

[0009] The ceramic cone is capable of being controlled to move upward to block the bottom opening of the feeding cylinder, and is capable of being controlled to move downward to release the bottom opening of the feeding cylinder.

[0010] Optionally, the vertical distance between the bottom opening of the feeding cylinder and the top surface of the middle channel of the water-cooled screen is 20 to 40 cm.

[0011] Optionally, it also includes a valve chamber and a load-bearing flange, the load-bearing flange being fixedly disposed around the feeding cylinder and relative to the feeding cylinder, the valve chamber being fixed above the water-cooled screen, and the load-bearing flange being overlapped on the valve chamber.

[0012] Optionally, the ceramic cone is conical with its tip pointing upwards, and the tip is connected to a vertically extending control rod.

[0013] Optionally, it also includes a flow guide tube surrounding the water-cooled screen and located above the crucible.

[0014] Optionally, it also includes an upper insulation barrel surrounding the flow guide tube and located above the crucible.

[0015] Optionally, a main heater may also be provided around the outer peripheral surface of the crucible.

[0016] Optionally, the feeding cylinder, the water-cooled screen, and the crucible are concentric in the orthographic projection of the plane in which the single crystal furnace is located.

[0017] When the ceramic cone moves downwards in a controlled manner, opening the feeding tube, the additional dopant can fall into the crucible through the feeding tube. Because the temperature in the area where the water-cooled screen is located is lower than the temperature inside the crucible, even dopant with a low melting point will not melt or vaporize inside the feeding tube, thus almost all of it falls into the crucible as molten semiconductor material. The amount of dopant added is precisely controllable. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the single crystal furnace of this utility model.

[0019] The attached diagram is labeled as follows: 1. Feeding cylinder; 11. Load-bearing flange; 12. Valve chamber; 2. Ceramic cone; 21. Control rod; 3. Water-cooled screen; 4. Flow guide cylinder; 5. Insulation tank; 6. Main heater. Detailed Implementation

[0020] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0021] refer to Figure 1 An embodiment of this utility model provides a single crystal furnace, including: a crucible, a water-cooled screen 3, a feeding cylinder 1, and a ceramic cone 2.

[0022] The crucible is Figure 1 Not shown in the diagram, it is located directly below the guide tube 4, and the main heater 6 surrounds the outer circumference of the crucible.

[0023] The water-cooled screen 3 is located above the crucible and has a central channel running vertically through it, positioned opposite the crucible's opening. The water-cooled screen 3 serves as a single-crystal thermal field component; flowing water passes through it to remove heat, increasing the temperature gradient within the single-crystal furnace and facilitating crystal pulling. The temperature near the upper part of the water-cooled screen 3 is lower than the temperature at the crucible opening.

[0024] The feeding cylinder 1 is a cylindrical structure extending vertically. The feeding cylinder 1 is fixedly positioned relative to the water-cooled screen 3. Specifically, the feeding cylinder 1 is fixed within a vertically extending channel at the top of the single crystal furnace. The bottom opening of the feeding cylinder 1 is opposite to and higher than the top surface of the middle channel of the water-cooled screen 3. When a dopant with a low melting point (e.g., high-purity antimony) is added into the feeding cylinder 1 through the top opening, the dopant falls to the bottom of the feeding cylinder 1 and does not melt or vaporize.

[0025] Specifically, during use, the feeding cylinder 1 is placed inside the single crystal furnace, and its position remains fixed. After the doping is completed, the feeding cylinder 1 is lifted and removed from the single crystal furnace.

[0026] The ceramic cone 2 is a cone-shaped element with its tip pointing upwards. The ceramic cone 2 can be controlled to move upwards to block the bottom opening of the feeding cylinder 1, and can also be controlled to move downwards to release the bottom opening of the feeding cylinder 1. When dopant replenishment is needed, the ceramic cone 2 moves downwards in a controlled manner, and the dopant falls along the inclined surface of the ceramic cone 2 into the crucible.

[0027] Since the temperature at the bottom of the feeding cylinder 1 is significantly lower than the temperature near the crucible opening, the low-melting-point and low-boiling-point dopants will not melt or vaporize, nor will they stick to the bottom of the feeding cylinder 1, thus allowing for precise control of the amount of dopant added.

[0028] Optionally, the vertical distance (i.e., height difference) between the bottom opening of the feeding cylinder 1 and the top surface of the middle channel of the water-cooled screen 3 is 20 to 40 cm. Preferably, this height difference is around 30 cm. Since the dopant slides down the ceramic cone 2, it has an initial lateral velocity. If the height difference is too large, the dopant may fall outside the water-cooled screen 3. If the height difference is too small, the vaporization and melting of the dopant will be more pronounced.

[0029] Optionally, the system also includes a valve chamber 12 and a load-bearing flange 11. The load-bearing flange 11 surrounds the feeding cylinder 1 and is fixed relative to the feeding cylinder 1 (e.g., the load-bearing flange 11 is welded to the outer circumferential surface of the feeding cylinder 1). The valve chamber 12 is fixed above the water-cooled screen 3 (specifically, the valve chamber 12 is fixed at the vertically extending channel at the top of the single crystal furnace), and the load-bearing flange 11 overlaps the valve chamber 12. The valve chamber 12 is, for example, a radially protruding shell along the vertically extending channel at the top of the single crystal furnace. When the feeding cylinder 1 is inserted, the valve chamber 12 defines the lowest downward position of the feeding cylinder 1.

[0030] Optionally, the ceramic cone 2 is cone-shaped with its tip pointing upwards, and the tip is connected to a vertically extending control rod 21. The upper end of the control rod 21 extends upwards beyond the feeding cylinder 1, and the upper end of the control rod 21 is moved up and down by a mechanical device, thereby moving the ceramic cone 2 up and down.

[0031] Optionally, it also includes a flow guide 4 surrounding the water-cooled screen 3 and located above the crucible. The function of the flow guide 4 is to guide the airflow.

[0032] Optionally, it also includes an upper insulation container 5 surrounding the flow guide cylinder 4 and located above the crucible. The insulation container 5 is used for heat preservation.

[0033] Optionally, a main heater 6 is also included, which is disposed around the outer peripheral surface of the crucible.

[0034] Optionally, the feeding cylinder 1, the water-cooled screen 3, and the crucible are concentric in the orthographic projection of the plane in which the single crystal furnace is located.

[0035] When the ceramic cone 2 moves downwards in a controlled manner, opening the feeding cylinder 1, the additional dopant can fall into the crucible through the feeding cylinder 1. Since the temperature in the area where the water-cooled screen 3 is located is lower than the temperature inside the crucible, even dopant with a low melting point will not melt or vaporize inside the feeding cylinder 1, thus almost all of it falls into the crucible as molten semiconductor material. The amount of dopant added is precisely controllable.

[0036] The various embodiments in this utility model are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0037] The scope of protection of this utility model is not limited to the above-described embodiments. Obviously, those skilled in the art can make various modifications and variations to this utility model without departing from its scope and spirit. If these modifications and variations fall within the scope of the claims of this utility model and their equivalents, then the intent of this utility model also includes these modifications and variations.

Claims

1. A single crystal furnace, characterized in that, include: crucible; A water-cooled screen, located above the crucible, has a central channel running vertically through the crucible, and the central channel is positioned opposite to the opening of the crucible. A feeding cylinder is fixedly installed relative to the water-cooled screen, with its bottom opening opposite to the middle channel of the water-cooled screen and higher than the top surface of the middle channel of the water-cooled screen; The ceramic cone is capable of being controlled to move upward to block the bottom opening of the feeding cylinder, and is capable of being controlled to move downward to release the bottom opening of the feeding cylinder.

2. The single crystal furnace according to claim 1, characterized in that, The vertical distance between the bottom opening of the feeding cylinder and the top surface of the middle channel of the water-cooled screen is 20 to 40 cm.

3. The single crystal furnace according to claim 1, characterized in that, It also includes a valve chamber and a load-bearing flange, the load-bearing flange being fixedly disposed around the feeding cylinder and relative to the feeding cylinder, the valve chamber being fixed above the water-cooled screen, and the load-bearing flange being overlapped on the valve chamber.

4. The single crystal furnace according to claim 1, characterized in that, The ceramic cone is cone-shaped with its tip pointing upwards, and the tip is connected to a vertically extending control rod.

5. The single crystal furnace according to claim 1, characterized in that, It also includes a flow guide tube surrounding the water-cooled screen and located above the crucible.

6. The single crystal furnace according to claim 5, characterized in that, It also includes an upper insulation barrel that surrounds the flow guide tube and is located above the crucible.

7. The single crystal furnace according to claim 1, characterized in that, It also includes a main heater disposed around the outer circumference of the crucible.

8. The single crystal furnace according to claim 1, characterized in that, The feeding cylinder, the water-cooled screen, and the crucible are concentric in the orthographic projection of the plane in which the single crystal furnace is located.

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