Vertical furnace tube arrangement

Abstract

The utility model provides a vertical furnace pipe device belongs to semiconductor equipment field, including the outer tube, the outer tube one end is closed and presents the convex arc surface shape, the other end is open, is equipped with the exhaust port on the pipe wall of outer tube, the variable diameter inner tube, the variable diameter inner tube both ends are open, are coaxial in the inside of outer tube, and the variable diameter inner tube middle part exists the diameter change, make the upper end inner diameter of variable diameter inner tube less than the lower end inner diameter, the crystal boat for bearing multilayer wafer, its upper half part is located in the narrow area of variable diameter inner tube, the base is used for supporting the crystal boat, and will send the crystal boat into the variable diameter inner tube and close the open end of outer tube, the lifting assembly drives the base to move along the outer tube axial movement, the heating assembly surrounds the setting in the outside of outer tube, and this scheme is through the variable diameter inner tube structure design, reduces the space between top wafer and inner tube makes the time of gas diffusion to top shorter, and then makes the thickness uniformity of top wafer better, solved the problem of the poor control effect of the thickness uniformity of top wafer in prior art crystal boat.

Description

Technical Field

[0001] This utility model relates to the field of semiconductor equipment technology, and specifically to a vertical furnace tube device. Background Technology

[0002] In the low-pressure chemical vapor deposition (LPCVD) high-temperature oxidation (HTO) process in semiconductor manufacturing, dichlorosilane (DCS, SiH2Cl2) and nitrous oxide (N2O) are typically used as reactant gases to grow a silicon dioxide thin film on the wafer surface through a chemical reaction. This process is completed in a vertical furnace tube.

[0003] The existing vertical furnace tube structure includes a heater, an outer tube, and an inner tube. The inner tube is used to house a crystal boat containing multiple layers of wafers. The wafers are stacked vertically in the crystal boat. The entire high-temperature oxidation process is completed in a vacuum environment. N2 and SiH2Cl2 are introduced from the bottom of the furnace tube through an inlet pipe, while a vacuum pump is used to evacuate the cavity to achieve a vacuum state. Due to the layout and construction of the heater, outer tube, and inner tube, the gas flows from the bottom upwards to cover the wafers during the process.

[0004] However, in the existing technology, the airflow diffuses to the top slowly and takes a long time, and the uniformity of the wafer film thickness is related to the flow rate of the airflow under vacuum conditions. Therefore, the thickness uniformity of the wafer on the upper part of the crystal boat is difficult to control.

[0005] In other words, existing technologies suffer from poor control over the uniformity of wafer thickness at the top of the wafer boat. Utility Model Content

[0006] The purpose of this invention is to provide a vertical furnace tube device to solve the problems mentioned in the background art.

[0007] To achieve the above objectives, this utility model provides the following technical solution:

[0008] A vertical furnace tube device, characterized in that it comprises:

[0009] The outer tube is closed at one end and has a convex arc shape, while the other end is open. The outer tube has an exhaust port on its wall.

[0010] The inner tube with a variable diameter has open ends and is coaxially located inside the outer tube. The inner tube has a diameter change in the middle, so that the inner diameter of the upper end of the inner tube is smaller than the inner diameter of the lower end.

[0011] A crystal boat is used to carry multilayer wafers, and its upper part is located in the upper region of the variable diameter inner tube.

[0012] The base is used to support the crystal boat, and to send the crystal boat into the variable diameter inner tube and close the open end of the outer tube;

[0013] The lifting assembly drives the base to move axially along the outer tube.

[0014] Heating components are arranged around the outside of the outer tube.

[0015] Preferably, the diameter of the variable-diameter inner tube is varied in a stepped or tapered manner.

[0016] Preferably, the wall thickness of the upper diameter-changing region of the variable-diameter inner tube is the same as the wall thickness of the lower diameter-changing region of the variable-diameter inner tube.

[0017] Preferably, a heat-insulating cavity is formed between the outer tube and the inner tube with a variable diameter.

[0018] Preferably, the lifting assembly adopts a mechanical structure driven by a cylinder or servo motor.

[0019] Preferably, the exhaust port is connected to a vacuum pump system to maintain a vacuum environment inside the furnace tube.

[0020] Preferably, the crystal boat has multiple wafer placement slots, which are arranged at equal intervals along the vertical direction.

[0021] Preferably, the distance between the upper part of the crystal boat and the inner wall of the variable-diameter inner tube is in the range of 3 to 10 mm.

[0022] The beneficial effects of the above-mentioned technical solution of this utility model are as follows:

[0023] This solution employs a variable-diameter inner tube structure design, making the upper diameter of the inner tube smaller than the lower diameter. This shortens the distance between the top wafer of the crystal boat and the upper end of the inner tube. The reduced space between the top wafer and the inner tube allows the gas to flow upwards from the bottom faster and the time for the gas to diffuse to the top to be shorter. This results in better thickness uniformity of the top wafer, improving wafer quality and solving the technical problem of poor control over wafer thickness uniformity at the top of the crystal boat in existing technologies. Attached Figure Description

[0024] The above and other objects, features, and advantages of the present invention will become readily understood by reading the following detailed description of exemplary embodiments with reference to the accompanying drawings. In the drawings, several embodiments of the present invention are shown by way of example and not limitation, and like or corresponding reference numerals denote like or corresponding parts, wherein:

[0025] Figure 1 This is a schematic diagram of the overall structure of this utility model.

[0026] Explanation of reference numerals in the attached figures:

[0027] 1. Outer tube; 2. Inner tube with variable diameter; 3. Crystal boat; 4. Wafer; 5. Base; 6. Lifting assembly. Detailed Implementation

[0028] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Those skilled in the art should understand that the embodiments described below are only some, not all, of the embodiments disclosed. All other embodiments obtained by those skilled in the art based on the embodiments of the present utility model without creative effort are within the scope of protection of the present utility model.

[0029] To address the uneven heating of a wafer caused by relying solely on zoned temperature control and waiting for the heat source to cool naturally to the target temperature when a certain area of ​​the wafer needs to be cooled, this solution provides an internal structure for a wafer annealing furnace.

[0030] In this solution, a variable-diameter design is used to make the upper diameter of the variable-diameter inner tube 2 smaller than its lower diameter. This shortens the distance between the top wafer 4 in the crystal boat 3 and the upper end of the variable-diameter inner tube 2. The reduced space between the top wafer 4 and the variable-diameter inner tube 2 increases the upward flow speed of gas and shortens the time it takes for gas to diffuse to the top of the variable-diameter inner tube 2. This results in better thickness uniformity of the top wafer 4, improving the quality of the wafer 4 and solving the technical problem of poor thickness uniformity control of the top wafer in the crystal boat in existing technologies.

[0031] After introducing the basic principles of this utility model, various non-limiting embodiments of this utility model are described in detail below. Any quantity of elements in the accompanying drawings is for illustrative purposes only and not for limitation, and any naming is for distinction only and has no limiting meaning.

[0032] The principles and spirit of this utility model will be explained in detail below with reference to several representative embodiments.

[0033] Example 1

[0034] A vertical furnace tube device, such as Figure 1 As shown, it includes an outer tube 1, a variable-diameter inner tube 2, a crystal boat 3, a base 5, a lifting assembly 6, and a heating assembly.

[0035] One end of the outer tube 1 is closed and has a convex arc shape, while the other end is open. The outer tube 1 has an exhaust port on its wall. The exhaust port is used to discharge gas when a chemical reaction occurs inside the furnace tube.

[0036] The aforementioned variable-diameter inner tube 2 is open at both ends and coaxially disposed inside the outer tube 1. The variable-diameter inner tube 2 has a diameter change in the middle, such that the inner diameter of the upper end of the variable-diameter inner tube 2 is smaller than the inner diameter of the lower end.

[0037] Optionally, the aforementioned diameter variation method can be a stepped or tapered gradual change, such as... Figure 1 The diameter change method shown is a tapered gradual change. When the diameter change method described above is stepped, it can be understood that... Figure 1 The conical region (represented by diagonal lines in two dimensions) will transform into a stepped shape.

[0038] In addition, the aforementioned crystal boat 3 is used to carry multi-layered wafers 4. Specifically, the crystal boat 3 has multiple wafer placement slots, and each wafer placement slot can hold one wafer.

[0039] The upper part of the crystal boat 3 is located in the narrower upper region of the variable diameter inner tube 2; the base 5 is used to support the crystal boat 3, and to send the crystal boat 3 into the variable diameter inner tube 2, and to seal the open end of the closed outer tube 1; the lifting assembly 6 is used to drive the base 5 to move axially along the outer tube (1).

[0040] It should be noted that the heating component (not shown in the figure) is arranged around the outside of the outer tube 1.

[0041] Understandably, the crystal boat 3 is supported on the base 5, which is used to feed the crystal boat into the variable diameter inner tube 2 and to close the open end of the outer tube 1 so as to facilitate the chemical reaction of growing thin films inside the furnace tube.

[0042] It is worth noting that in this embodiment, the upper half of the wafer in the crystal boat 3 is located in the narrower part of the variable diameter inner tube.

[0043] Preferably, the distance between the crystal boat 3 and the inner tube wall is 3mm-10mm.

[0044] It is understood that the outer tube 1 and the variable diameter inner tube 2 remain in a fixed position and do not move. The base 3 is equipped with a lifting assembly 6 to drive the base to move along the axial direction of the outer tube.

[0045] It should be noted that, since the furnace tube in this embodiment is a vertical furnace tube, the above-mentioned lifting component 6 can drive the base 3 to move up and down, thereby moving the crystal boat 3 into or out of the variable diameter inner tube 2.

[0046] It is understandable that the aforementioned lifting assembly 6 can adopt various mechanical structures, such as mechanical structures that use cylinders or servo motors as power sources.

[0047] Furthermore, a heating element is provided around the outer tube 1 to provide the required temperature for the chemical reaction that generates a thin film on the surface of the wafer 4.

[0048] It is worth noting that the heating components control the temperature inside the vertical furnace tube by heating the outer tube 1, rather than directly heating the inner tube 2 with a variable diameter. This heating method provides more stable and precise temperature control and ensures a more uniform temperature inside the furnace tube. Furthermore, the heating components are arranged around the outer tube 1, which enhances the effect of uniform temperature control.

[0049] Furthermore, during operation, the aforementioned device sends the crystal boat 3 into the variable-diameter inner tube 2 via the base 5, while the base 5 closes the open end of the outer tube 1 to facilitate chemical reaction in the furnace tube. The reaction gas is first introduced into the device through the gas transmission system. When passing through the variable-diameter section of the wafer 4, the space between the top wafer 4 and the variable-diameter inner tube 2 is reduced, thereby increasing the speed at which the gas flows upward from the bottom and shortening the time it takes to diffuse to the top, resulting in better uniformity of the thickness of the top wafer 4.

[0050] This solution employs a variable-diameter inner tube structure design, making the upper diameter of the inner tube smaller than the lower diameter. This shortens the distance between the top wafer of the crystal boat and the upper end of the inner tube. The reduced space between the top wafer and the inner tube allows the gas to flow upwards from the bottom faster and the time for the gas to diffuse to the top to be shorter. This results in better thickness uniformity of the top wafer, improving wafer quality and solving the technical problem of poor control over wafer thickness uniformity at the top of the crystal boat in existing technologies.

[0051] Example 2

[0052] Its main difference from Example 1 is:

[0053] In this embodiment, the variable-diameter inner tube has multiple diameter changes, which makes the diameter of the variable-diameter inner tube gradually decrease from bottom to top, and the distance between the variable-diameter inner tube and the corresponding wafer gradually decrease from bottom to top, making the process of gas flowing from bottom to top more stable.

[0054] The above-described preferred embodiments of the present invention are provided as examples, but it will be apparent to those skilled in the art that such embodiments are provided merely by way of example. Many modifications, alterations, and alternatives will occur to those skilled in the art without departing from the spirit and intent of the invention. It should be understood that various alternatives to the embodiments of the invention described herein may be employed in the practice of the invention. The appended claims are intended to define the scope of protection of the invention and therefore cover the modular compositions, equivalents, or alternatives within the scope of these claims.

Claims

1. A vertical furnace tube device, characterized in that, include: The outer tube (1) is closed at one end and has a convex arc shape, while the other end is open. The outer tube (1) has an exhaust port on its wall. A variable diameter inner tube (2) is open at both ends and coaxially disposed inside the outer tube (1). The variable diameter inner tube (2) has a diameter change in the middle, so that the inner diameter of the upper end of the variable diameter inner tube (2) is smaller than the inner diameter of the lower end. A crystal boat (3) is used to carry multilayer wafers (4), the upper part of which is located in the upper region of the variable diameter inner tube (2); The base (5) is used to support the crystal boat (3), and to send the crystal boat (3) into the variable diameter inner tube (2) and close the open end of the outer tube (1); The lifting assembly (6) drives the base (5) to move axially along the outer tube (1); A heating assembly is disposed around the outside of the outer tube (1).

2. The vertical furnace tube device according to claim 1, characterized in that: The diameter of the variable inner tube (2) is either stepped or tapered.

3. The vertical furnace tube device according to claim 1, characterized in that: The wall thickness of the upper region of the variable-diameter inner tube (2) is the same as the wall thickness of the lower region of the variable-diameter inner tube (2).

4. The vertical furnace tube device according to claim 1, characterized in that: A heat-insulating cavity is formed between the outer tube (1) and the variable-diameter inner tube (2).

5. The vertical furnace tube device according to claim 1, characterized in that, The lifting assembly (6) adopts a mechanical structure driven by a cylinder or servo motor.

6. The vertical furnace tube device according to claim 1, characterized in that: The exhaust port is connected to a vacuum pump system to maintain a vacuum environment inside the furnace tube.

7. The vertical furnace tube device according to claim 1, characterized in that: The crystal boat (3) has multiple wafer placement slots, which are arranged at equal intervals along the vertical direction.

8. The vertical furnace tube device according to claim 1, characterized in that, The distance between the upper part of the crystal boat (3) and the inner wall of the variable diameter inner tube (2) ranges from 3 to 10 mm.

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