Method for reducing oxygen content in reaction chamber

Abstract

The invention provides a method for reducing the content of oxygen in a reaction chamber, which comprises the following steps: S1, continuously introducing process gas into the reaction chamber, collecting the internal pressure of the reaction chamber and the external pressure at a wafer transfer port, and enabling the internal pressure of the reaction chamber to be higher than the external pressure at the wafer transfer port; s2, opening a wafer conveying opening, conveying the wafers into a reaction chamber, placing the wafers on a lifting pin, and arranging the wafers above a bearing ring at intervals at the moment; s3, closing the wafer conveying port, starting an exhaust device, and continuously introducing process gas; s4, collecting the oxygen concentration in the reaction chamber, and when the oxygen concentration reaches a preset value, descending the lifting pin to enable the wafer to fall on the bearing ring; and S5, starting the process. According to the method, excessive oxygen can be prevented from entering the reaction chamber, and oxygen residues between the back of the wafer and the base station at the bottom of the reaction chamber can be avoided, so that the oxygen clearing time is shortened, and the equipment productivity is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor equipment, and more particularly, relates to a method for reducing the oxygen content in a reaction chamber. Background Art

[0002] The control of oxygen concentration in the rapid annealing (RTA) process is a key factor, which directly affects the processing quality of semiconductor materials and the final performance of the product. Since the wafer transfer process of the RTA equipment is carried out under normal pressure, oxygen will enter the reaction chamber through the wafer transfer port, and if the oxygen cannot be effectively controlled, it will directly affect the process performance. At present, the existing processing method is to transfer the wafer under normal pressure, and the pressure inside and outside the wafer transfer port is the same. When the wafer is transferred into the reaction chamber, the gate valve of the wafer transfer port is closed, and the lifting pin used to support the wafer falls, so that the wafer falls on the support ring. At this time, nitrogen is introduced into the reaction chamber, and a large flow of nitrogen is used to purge the reaction chamber and a pump is used to evacuate the air. At the same time, the oxygen concentration in the reaction chamber is monitored, and the process starts when the oxygen concentration reaches the specified requirement of 3~5ppm. However, when transferring the wafer, too much oxygen enters the reaction chamber along with the wafer, which causes a long time for the oxygen concentration to drop to the specified requirement, resulting in low wafer production capacity. In addition, after the wafer falls on the support ring, a large flow of nitrogen is purged into the reaction chamber. At this time, a small amount of oxygen will be difficult to remove in a certain space formed under the wafer and the support ring, affecting the production efficiency of the equipment and reducing production capacity. Summary of the invention

[0003] The purpose of the embodiment of the present invention is to provide a method for reducing the oxygen content in a reaction chamber, aiming to solve the technical problem that after the wafer transfer is completed, it takes a long time for the oxygen concentration in the reaction chamber to drop, and there is a small amount of oxygen between the bottom of the wafer and the supporting ring, which affects the production efficiency of the equipment and reduces production capacity.

[0004] To achieve the above object, the present invention provides a method for reducing the oxygen content in a reaction chamber, comprising the following steps: Step S1. continuously introduce process gas into the reaction chamber, collect the internal pressure of the reaction chamber and the external pressure at the film transfer port, so that the internal pressure of the reaction chamber is higher than the external pressure at the film transfer port; Step S2. Open the wafer transfer port, transfer the wafer into the reaction chamber, and place it on the lifting pins. At this time, the wafer is spaced above the supporting ring; Step S3. Close the film transfer port, open the exhaust device, and continue to introduce process gas; Step S4. Collecting the oxygen concentration in the reaction chamber, when the oxygen concentration reaches a preset value, lowering the lifting pins to allow the wafer to fall onto the supporting ring; Step S5. Start the process.

[0005] Optionally, in step S1, the internal pressure of the reaction chamber is controlled to be higher than the external pressure at the film transfer port by 5 Torr.

[0006] Optionally, in step S4, the oxygen concentration in the reaction chamber is continuously monitored by an oxygen analyzer, wherein the preset value range of the oxygen concentration in the reaction chamber is 3-5 ppm.

[0007] Optionally, the process gas is nitrogen.

[0008] Optionally, a first air inlet is arranged on a side wall of the reaction chamber, and the first air inlet is arranged opposite to the film transfer port.

[0009] Optionally, the exhaust device includes an exhaust pipeline, the exhaust pipeline is arranged outside the reaction chamber, and the exhaust pipeline is connected to the film transfer port.

[0010] Optionally, the exhaust pipe is located below the film transfer port.

[0011] Optionally, a second air inlet is provided at the bottom of the reaction chamber.

[0012] Optionally, there are multiple second air inlets.

[0013] Optionally, the plurality of second gas inlets are evenly distributed along the circumference of the bottom of the reaction chamber.

[0014] Compared with the prior art, the method for reducing the oxygen content in a reaction chamber provided by the present invention has the following beneficial effects: During the wafer transfer process, by creating a certain pressure difference between the inside and outside of the reaction chamber and controlling the internal pressure of the reaction chamber to be higher than the external pressure at the wafer transfer port, it is possible to prevent excessive oxygen from entering the reaction chamber, which would cause the oxygen concentration to drop for a long time. When the wafer is placed on the lifting pins, process gas is continuously introduced to purge the reaction chamber. When the oxygen concentration in the reaction chamber reaches a preset value, the lifting pins are lowered to allow the wafer to fall on the support ring before the process is started, so as to avoid residual oxygen between the back of the wafer and the bottom base of the reaction chamber. By combining the above methods, it is possible not only to prevent oxygen from entering the reaction chamber, but also to prevent oxygen from remaining, so that the oxygen concentration in the chamber drops rapidly, which can significantly reduce the process time, thereby effectively improving the equipment capacity, and improving the efficiency and economic benefits of semiconductor manufacturing. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0016] Figure 1 A schematic diagram of the structure of a reaction chamber of a rapid annealing device provided in an embodiment of the present invention; Figure 2 A schematic flow chart of a method for reducing oxygen content in a reaction chamber provided in an embodiment of the present invention.

[0017] The reference numerals in the above drawings are as follows: 10. Reaction chamber; 11. Bottom base; 12. Support ring; 13. Wafer; 14. Lifting pin; 15. Wafer transfer port; 16. Gate valve; 17. First air inlet; 18. Exhaust pipeline; 19. Second air inlet. DETAILED DESCRIPTION

[0018] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0019] In the description of the present invention, it should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0020] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0021] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0022] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0023] For ease of understanding, the present invention is described using a rapid annealing device as an example. Figure 1 As shown, a rapid annealing device includes a reaction chamber 10 for completing a process, a bottom base 11 is arranged in the reaction chamber 10, a supporting ring 12 is arranged above the bottom base 11, the supporting ring 12 is a hollow ring structure, which is used to carry a wafer 13, a lifting pin 14 that can be lifted and lowered is penetrated inside the bottom base 11, and the lifting pin 14 is used to lift the wafer 13 or make the wafer 13 fall completely on the bottom base 11 when the wafer 13 is conveyed into the reaction chamber 10; a film transfer port 15 for transferring the wafer 13 into or out of the reaction chamber 10 is arranged on the side wall of the reaction chamber 10, and a gate valve 16 for opening and closing the film transfer port 15 is arranged outside the film transfer port 15.

[0024] Please refer to Figure 2 As shown, in an embodiment of the present invention, a method for reducing the oxygen content in a reaction chamber is provided, comprising the following steps: Step S1 . continuously introduce process gas into the reaction chamber 10 , collect the internal pressure of the reaction chamber 10 and the external pressure at the film transfer port 15 , and make the internal pressure of the reaction chamber 10 higher than the external pressure at the film transfer port 15 .

[0025] Before the wafer 13 is transferred, the internal pressure of the reaction chamber 10 can be controlled by the lower computer to be higher than the external pressure at the transfer port 15. Since the internal pressure of the reaction chamber 10 is higher than the external pressure at the transfer port 15, it can be prevented that excessive oxygen enters the reaction chamber 10 through the transfer port 15 after the gate valve 16 is opened during transfer. Among them, the lower computer can be a computer that directly controls the equipment to obtain the equipment status, including a PLC control program, a remote data acquisition module, a sensor, etc. In this embodiment, a pressure gauge is provided outside the transfer port 15 and inside the reaction chamber 10 to monitor the pressure in real time. After the lower computer obtains the pressure at the two positions, it controls the pressure control unit device (such as a pressure regulating valve, etc.) through the PLC program to control the internal and external pressure difference of the reaction chamber 10.

[0026] In some embodiments, the internal pressure of the reaction chamber 10 is controlled to be 5 Torr higher than the external pressure at the film transfer port 15. Of course, the pressure difference is not limited to 5 Torr, but it should not be too high. If the pressure difference between the inside and outside of the reaction chamber 10 is too large, the high-temperature gas in the reaction chamber 10 will flow out from the film transfer port 15 to the atmosphere, which may damage other devices.

[0027] In some embodiments, see Figure 1As shown, a first gas inlet 17 is provided on the side wall of the reaction chamber 10, and the first gas inlet 17 is used to communicate with an external gas source to introduce process gas, and the exhaust device is used to exhaust the gas in the reaction chamber out of the reaction chamber. The process gas can be nitrogen.

[0028] Step S2 . Open the wafer transfer port 15 , transfer the wafer 13 into the reaction chamber 10 , and place it on the lifting pins 14 . At this time, the wafer 13 is spaced above the supporting ring 12 .

[0029] In some embodiments, when the internal pressure of the reaction chamber 10 is higher than the external pressure at the film transfer port 15 by 5 Torr, the gate valve 16 is opened to transfer the film. Figure 1 As shown, in this embodiment, the first air inlet 17 is arranged opposite to the wafer transfer port 15, and nitrogen enters the reaction chamber 10 through the first air inlet 17. During the wafer transfer process, air enters the reaction chamber 10 along with the wafer 13 through the wafer transfer port 15. Since the nitrogen enters the reaction chamber 10 from the opposite side of the wafer transfer port 15 and continues to purge, it will collide with the air entering through the wafer transfer port 15, thereby preventing excessive oxygen from entering the reaction chamber 10, which is beneficial to reducing the oxygen removal time.

[0030] Step S3: close the film transfer port 15, open the exhaust device, and continue to introduce process gas.

[0031] In some embodiments, after the wafer 13 is placed on the lifting pins 14, the gate valve 16 is closed, and the external air is blocked outside the wafer transfer port 15. At this time, the exhaust device is opened to suck the gas in the reaction chamber 10 and exhaust it outside the reaction chamber 10. The exhaust device includes an exhaust pipeline 18, which is arranged outside the reaction chamber 10 and communicated with the wafer transfer port 15. Optionally, the exhaust pipeline 18 is located below the wafer transfer port 15, such as Figure 1 As the exhaust pipe 18 is disposed below the film conveying port 15, the oxygen entering through the film conveying port 15 can be quickly sucked out, and at the same time, the nitrogen entering from the opposite direction can be discharged after passing through the reaction chamber 10, which is conducive to fully removing the oxygen in the reaction chamber 10.

[0032] In some optional embodiments, a second air inlet 19 is provided at the bottom of the reaction chamber 10. There are multiple second air inlets 19, and the multiple second air inlets 19 are evenly distributed along the circumference of the bottom of the reaction chamber. Through the above arrangement, a large flow of nitrogen can enter from different positions and purge the reaction chamber 10, thereby increasing the purge area, and achieving full purge of the bottom of the reaction chamber 10 and the space formed between the wafer 13 and the bottom base 11 to avoid residual oxygen. A large flow of nitrogen enters the reaction chamber 10 from the first air inlet 17 opposite to the wafer transfer port 15 and the second air inlet 19 at the bottom of the reaction chamber 10 and continues to purge, which can increase the purge area and avoid residual oxygen. The gas flow direction is as follows: Figure 1 As shown, oxygen can be exhausted to the outside of the reaction chamber 10 through the exhaust pipe 18 together with nitrogen, so as to quickly reduce the oxygen concentration in the reaction chamber 10 .

[0033] Step S4 . Collect the oxygen concentration in the reaction chamber 10 . When the oxygen concentration reaches a preset value, lower the lifting pins 14 to allow the wafer 13 to fall onto the supporting ring 12 .

[0034] It can be understood that when the lifting pin 14 descends and the wafer 13 falls on the supporting ring 12, since there is a certain space between the supporting ring 12 and the bottom base 11, the reaction chamber 10 is purged before the wafer 13 falls on the supporting ring 12 on the lifting pin 14. This can avoid that the small amount of oxygen in the back space of the wafer 13 is difficult to be purged after the wafer 13 is transferred into the reaction chamber 10 and immediately falls on the supporting ring 12, resulting in a longer time for the oxygen concentration to drop to the target concentration.

[0035] In some embodiments, the oxygen concentration in the reaction chamber 10 is continuously monitored by an oxygen analyzer, wherein the preset value of the oxygen concentration in the reaction chamber 10 is in the range of 3-5 ppm. The preset value of the oxygen concentration is set according to the process requirements and is not limited here.

[0036] Step S5. Start the process.

[0037] In summary, the method for reducing the oxygen content in a reaction chamber provided in this embodiment has at least the following beneficial technical effects: During the wafer 13 transfer process, by making a certain pressure difference between the inside and outside of the reaction chamber 10, and controlling the internal pressure of the reaction chamber 10 to be higher than the external pressure at the wafer transfer port 15, it is possible to prevent excessive oxygen from entering the reaction chamber 10, which would cause the oxygen concentration to drop for a long time; when the wafer 13 is placed on the lifting pins 14, the process gas is continuously introduced to purge the reaction chamber 10. When the oxygen concentration in the reaction chamber 10 reaches a preset value, the lifting pins 14 are lowered to allow the wafer 13 to fall on the supporting ring 12 before the process is started, so as to avoid residual oxygen between the back of the wafer 13 and the bottom base 11 of the reaction chamber 10. By combining the above methods, not only can oxygen be prevented from entering the reaction chamber 10, but also a large flow of nitrogen gas enters from different positions and purges the reaction chamber 10, thereby increasing the purge area, avoiding residual oxygen, and causing the oxygen concentration in the reaction chamber 10 to drop rapidly, which can significantly reduce the process time, thereby effectively improving the equipment capacity, and improving the efficiency and economic benefits of semiconductor manufacturing.

[0038] The above are only preferred embodiments of the present invention, and only specifically describe the technical principles of the present invention. These descriptions are only for explaining the principles of the present invention and cannot be interpreted as limiting the scope of protection of the present invention in any way. Based on the explanations here, any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention, and other specific implementations of the present invention that can be associated with by technicians in this field without creative labor, should be included in the scope of protection of the present invention.

Claims

1. A method for reducing the oxygen content in a reaction chamber, characterized in that: The following steps are involved: Step S1. continuously introduce process gas into the reaction chamber, collect the internal pressure of the reaction chamber and the external pressure at the film transfer port, so that the internal pressure of the reaction chamber is higher than the external pressure at the film transfer port; Step S2. Open the wafer transfer port, transfer the wafer into the reaction chamber, and place it on the lifting pins. At this time, the wafer is spaced above the supporting ring; Step S3. closing the film transfer port, opening the exhaust device, and continuously introducing the process gas; Step S4. collecting the oxygen concentration in the reaction chamber, and when the oxygen concentration reaches a preset value, lowering the lifting pins to allow the wafer to fall onto the supporting ring; Step S5. Start the process.

2. The method for reducing the oxygen content in a reaction chamber according to claim 1, characterized in that: In the step S1, the internal pressure of the reaction chamber is controlled to be higher than the external pressure at the film transfer port by 5 Torr.

3. The method for reducing the oxygen content in a reaction chamber according to claim 1, characterized in that: In the step S4, the oxygen concentration in the reaction chamber is continuously monitored by an oxygen analyzer, wherein the preset value range of the oxygen concentration in the reaction chamber is 3-5 ppm.

4. The method for reducing the oxygen content in a reaction chamber according to claim 1, characterized in that: The process gas is nitrogen.

5. The method for reducing the oxygen content in a reaction chamber according to claim 1, characterized in that: A first air inlet is arranged on the side wall of the reaction chamber, and the first air inlet is arranged opposite to the film transmission port.

6. The method for reducing the oxygen content in a reaction chamber according to claim 5, characterized in that: The exhaust device comprises an exhaust pipeline, the exhaust pipeline is arranged outside the reaction chamber, and the exhaust pipeline is communicated with the film transfer port.

7. The method for reducing the oxygen content in a reaction chamber according to claim 6, characterized in that: The exhaust pipeline is located below the film transmission port.

8. The method for reducing the oxygen content in a reaction chamber according to claim 5, characterized in that: A second air inlet is arranged at the bottom of the reaction chamber.

9. The method for reducing the oxygen content in a reaction chamber according to claim 8, characterized in that: The number of the second air inlets is plural.

10. The method for reducing the oxygen content in a reaction chamber according to claim 9, characterized in that: The plurality of second gas inlets are evenly distributed along the circumference of the bottom of the reaction chamber.

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