Horizontal furnace tube for low-pressure chemical vapor deposition

Abstract

The invention provides a horizontal furnace tube for low-pressure chemical vapor deposition, comprising: a furnace body in which a deposition process is performed; one end of the pipeline is connected with the furnace tail of the furnace body, the other end of the pipeline is connected with an exhaust pump, and the pipeline is used for conveying by-products generated in the deposition process; wherein a quick pumping valve, a slow pumping valve, a butterfly valve and a cold trap which are arranged in parallel are sequentially arranged between one end and the other end of the pipeline. According to the invention, less particles can be generated in the deposition process of the furnace tube.

Description

Technical Field

[0001] The invention relates to the field of semiconductor production and manufacturing, in particular to a horizontal furnace tube used for low-pressure chemical vapor deposition. Background Art

[0002] Semiconductor process technology is the foundation of the modern electronics industry. It involves the entire manufacturing process from raw materials to finished chips, including wafer preparation, cleaning, evaporation, deposition, lithography, etching, diffusion, annealing, electroplating, cutting and other steps. These processes require not only extremely high precision and purity, but also continuous technological innovation to meet the growing demand for electronic devices. Advances in semiconductor process technology are not only reflected in the manufacture of smaller and more complex chips, but also in improving production efficiency, reducing costs and developing new application areas. For example, the development of flexible electronic technology has made wearable health monitoring devices and smart textiles possible, while breakthroughs in quantum computing herald another leap in computing power in the future. Innovations in these areas will further promote scientific and technological development, improve our quality of life, and provide new solutions to global challenges.

[0003] In the semiconductor industry, the LP (low pressure)-TEOS (tetraethyl orthosilicate) thin film deposition process is the most common and important process. It is a process in which a layer of solid SiO2 film is deposited on the surface of the wafer by a chemical reaction of thermal decomposition of TEOS under low pressure and high temperature. This technology has a series of characteristics such as low deposition temperature (650℃~750℃), easy control of film composition and thickness, film thickness proportional to deposition time, good uniformity and repeatability, excellent step coverage, simple operation, and wide range of use. The LP-TEOS thin film deposition process is generally carried out in a horizontal furnace tube. In the deposition process, the number of particles generated by the deposition is an important indicator for evaluating the quality of the deposited film layer. The number of particles in the deposited film layer is related to whether the subsequent photolithography and etching processes can be etched cleanly, and may even cause the particles in the subsequent polycrystalline deposition process to become coarser and fogging to occur. What is more serious is that the defects such as "hillocks" or "whiskers" generated by the extension will have a great impact on the integrity and accuracy of the pattern. The particle problem of LP-TEOS thin film deposition not only affects the quality of the film layer and causes etching residue, but also causes chip short circuit, which is directly related to the performance and reliability of the device. Therefore, in the LP-TEOS thin film deposition, how to reduce the particles generated by the furnace tube in the deposition process has become a problem that technicians need to solve urgently. Summary of the invention

[0004] The present invention provides a horizontal furnace tube for low-pressure chemical vapor deposition, comprising: a furnace body, in which a deposition process is carried out; a pipeline, one end of which is connected to the furnace tail of the furnace body, and the other end is connected to an exhaust pump, and the pipeline is used to transport by-products generated in the deposition process; wherein a fast-pump valve and a slow-pump valve, a butterfly valve, and a cold trap arranged in parallel are sequentially arranged between the one end and the other end of the pipeline.

[0005] Preferably, the horizontal furnace pipe further comprises a hand valve arranged on the pipe, and the hand valve is located between the cold trap and the exhaust pump.

[0006] Preferably, the horizontal furnace tube further comprises a heat-insulating bag, and the heat-insulating bag is arranged around the quick-draw valve, the slow-draw valve, the butterfly valve and the cold trap.

[0007] Preferably, the temperature range of the insulation bag is 150°C to 200°C.

[0008] Preferably, a plurality of wafer boats for placing wafers are arranged in the furnace body.

[0009] Preferably, the furnace body has a furnace opening, and the wafer enters the furnace body through the furnace opening and is placed on the wafer boat.

[0010] In the present invention, the cold trap is arranged at the furnace tail away from the furnace body, and a quick-draw valve and a butterfly valve are arranged between the cold trap and the furnace tail. In this way, even if there is a fluctuation in the airflow, the by-products generated during the deposition process are difficult to be recoiled back to the furnace tail and generate particles. Therefore, more by-products will accumulate in the cold trap, thereby ensuring that the furnace tube generates fewer particles during the deposition process.

[0011] In the present invention, by placing the insulation bag around the quick-draw valve, the slow-draw valve, the butterfly valve and the cold trap, the by-products generated during the deposition process can be prevented from being quickly cooled and attached to the quick-draw valve, the slow-draw valve and the butterfly valve, thereby preventing the by-products from clogging the valves. At the same time, it can be ensured that the generated by-products are basically all attached to the cold trap, thereby keeping the front end of the cold trap clean.

[0012] In the present invention, a manual valve is arranged between the cold trap and the exhaust pump, thereby ensuring the convenience of preventive maintenance and increasing the service life of the exhaust pump. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 A schematic diagram of a horizontal furnace tube for low pressure chemical vapor deposition according to an embodiment of the present invention is shown;

[0014] Figure 2 A schematic diagram of a horizontal furnace tube with a heat preservation bag according to an embodiment of the present invention is shown;

[0015] Figure 3 A schematic diagram of a heat preservation bag according to an embodiment of the present invention is shown;

[0016] Figure 4 A schematic diagram showing the particle state of a horizontal furnace tube during a deposition process according to the prior art;

[0017] Figure 5 A schematic diagram showing the state of particles in a horizontal furnace tube according to the present invention during a deposition process. DETAILED DESCRIPTION

[0018] The following specific embodiments illustrate the implementation of the present invention, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. Although the description of the present invention will be introduced in conjunction with the preferred embodiment, this does not mean that the features of this invention are limited to this implementation. On the contrary, the purpose of introducing the invention in conjunction with the implementation is to cover other options or modifications that may extend based on the claims of the present invention. In order to provide a deep understanding of the present invention, the following description will include many specific details. The present invention can also be implemented without using these details. In addition, in order to avoid confusion or blurring the focus of the present invention, some specific details will be omitted in the description. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0019] It should be noted that in this specification, similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings.

[0020] In order to make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0021] Figure 1 Schematic diagram of a horizontal furnace tube for low pressure chemical vapor deposition according to an embodiment of the present invention. Figure 1 As shown, the horizontal furnace tube 10 includes a furnace body 101, and a deposition process is performed in the furnace body 101.

[0022] A plurality of wafer boats 102 for placing wafers are arranged in the furnace body 101. Figure 1 Six wafer boats 102 are shown in FIG. It is understandable that the number of wafer boats 102 can be any number without limitation.

[0023] The furnace body 101 has a furnace opening 1011 and a furnace tail 1012 . Wafers enter the furnace body 101 through the furnace opening 1011 and are placed on the wafer boat 102 .

[0024] In the furnace body 101, a deposition process is performed, that is, TEOS gas is thermally decomposed under low pressure and high temperature to deposit a layer of solid SiO2 film on the surface of the wafer.

[0025] The horizontal furnace tube 10 includes a pipeline 110, such as Figure 1 As shown, one end of the pipe 110 (ie, Figure 1 The left end of the furnace body 101 is connected to the furnace tail 1012, and the other end (i.e., Figure 1 The pipe 110 is connected to the exhaust pump 108 at the right end of the horizontal furnace tube 10. During the deposition process, a large amount of unreacted by-products are generated, and these by-products are waste gases generated by TEOS gas. The pipe 110 is used to transport the by-products generated in the deposition process, and finally discharges them out of the horizontal furnace tube 10 through the exhaust pump 108.

[0026] like Figure 1 As shown, the horizontal furnace pipe 10 includes a fast-pump valve 104, a slow-pump valve 105, a butterfly valve 106, and a cold trap 103. Specifically, between one end and the other end of the pipe 10, the fast-pump valve 104, the slow-pump valve 105, the butterfly valve 106, and the cold trap 103 are sequentially arranged in parallel.

[0027] The quick-pump valve 104 is installed on the pipeline 10, and the slow-pump valve 105 is arranged in parallel with the quick-pump valve 104. The quick-pump valve 104 can be used to quickly exhaust gas, and the slow-pump valve 105 can be used to finely control the flow rate of the exhaust gas. In the process of exhausting the exhaust gas, the quick-pump valve 104 and the slow-pump valve 105 can be combined to meet different application requirements.

[0028] The butterfly valve 106 is installed on the pipeline 10 and is located after the fast-pump valve 104 and the slow-pump valve 105 , and can be used to adjust the flow rate of the exhaust gas.

[0029] The cold trap 103 is installed on the pipeline 10 and is located after the butterfly valve 106 , so as to allow the by-products to accumulate in the cold trap 103 .

[0030] During the deposition process, unreacted by-products are generated, which are discharged from the furnace tail 1012, pass through the quick-draw valve 104 and the butterfly valve 106, and then enter the cold trap 103 and accumulate in the cold trap 103. Since the cold trap 103 is farther away from the furnace tail 1012 and is isolated from the furnace tail 1012 by the quick-draw valve 104 and the butterfly valve 106, even if there is a fluctuation in the air flow, the by-products are difficult to be recoiled back to the furnace tail 1012 and generate particles. Therefore, more by-products will accumulate in the cold trap 103 behind the butterfly valve 106. In this way, it can be ensured that the furnace tube 10 generates fewer particles during the deposition process.

[0031] In an embodiment of the present invention, Figure 1As shown, the horizontal furnace tube 10 further includes a hand valve 107 disposed on the pipeline 110 , and the hand valve 107 is located between the cold trap 103 and the exhaust pump 108 .

[0032] When the horizontal furnace tube 10 is to be subjected to preventive maintenance, the cold trap 103 needs to be disassembled and cleaned. If there is no hand valve 107, the exhaust pump 108 needs to be turned off before the operation. As is well known, frequent switching of the exhaust pump 108 will affect the service life of the exhaust pump 108. Therefore, through the hand valve 107, when performing preventive maintenance, there is no need to frequently switch the exhaust pump 108, so the hand valve 107 can ensure the convenience of preventive maintenance and increase the service life of the exhaust pump 108.

[0033] In an embodiment of the present invention, Figure 2 As shown, the horizontal furnace tube 10 further includes a heat preservation bag 109 , which is arranged around the fast-pumping valve 104 , the slow-pumping valve 105 , the butterfly valve 106 and the cold trap 103 . Figure 3 A schematic diagram of a heat preservation bag 109 according to an embodiment of the present invention is shown.

[0034] By providing the heat preservation belt 109 in this way, the byproducts generated during the deposition process can be prevented from being rapidly cooled and attached to the fast-draw valve 104, the slow-draw valve 105 and the butterfly valve 106, thereby preventing the byproducts from clogging the valves. At the same time, it can be ensured that substantially all of the generated byproducts are attached to the cold trap 103, thereby keeping the front end of the cold trap 103 clean.

[0035] Preferably, the temperature range of the insulation belt 109 is 150-200°C. If the temperature is set too high or too low, it cannot ensure that the by-products generated by the deposition process are mainly deposited in the cold trap 103. Because the temperature is too low, most of the by-products will be deposited at the front end of the cold trap 103, and if the temperature is too high, most of the by-products will be deposited at the rear end of the cold trap 103.

[0036] Figure 4 A schematic diagram showing the particle state of a horizontal furnace tube during a deposition process according to the prior art is shown. Figure 5 A schematic diagram showing the state of particles in a horizontal furnace tube according to the present invention during a deposition process.

[0037] During the deposition process in the horizontal furnace tube of the prior art, fixed simulation baffles are placed on the No. 1 and No. 6 wafer boats in the furnace body, and a particle monitoring sheet is placed on each of the No. 2, 3, 4, and 5 wafer boats, such as Figure 4 As shown in the figure, the particle monitoring values ​​of each wafer boat are very high. After a lot of experiments and analysis, it was confirmed that the particle composition is silicon dioxide.

[0038] During the deposition process in the horizontal furnace tube of the present invention, fixed simulation baffles are placed on the No. 1 and No. 6 wafer boats in the furnace body, and a particle monitoring sheet is placed on each of the No. 2, 3, 4, and 5 wafer boats, such as Figure 5 As shown, the particle monitoring values ​​of each wafer boat are very low, and the particle level has been significantly improved.

[0039] In the present invention, the cold trap is arranged at the furnace tail away from the furnace body, and a quick-draw valve and a butterfly valve are arranged between the cold trap and the furnace tail. In this way, even if there is a fluctuation in the airflow, the by-products generated during the deposition process are difficult to be recoiled back to the furnace tail and generate particles. Therefore, more by-products will accumulate in the cold trap, thereby ensuring that the furnace tube generates fewer particles during the deposition process.

[0040] In the present invention, by placing the insulation bag around the quick-draw valve, the slow-draw valve, the butterfly valve and the cold trap, the by-products generated during the deposition process can be prevented from being quickly cooled and attached to the quick-draw valve, the slow-draw valve and the butterfly valve, thereby preventing the by-products from clogging the valves. At the same time, it can be ensured that the generated by-products are basically all attached to the cold trap, thereby keeping the front end of the cold trap clean.

[0041] In the present invention, a manual valve is arranged between the cold trap and the exhaust pump, thereby ensuring the convenience of preventive maintenance and increasing the service life of the exhaust pump.

[0042] In the description provided herein, a large number of specific details are described. However, it is understood that embodiments of the present invention can be practiced without these specific details. In some instances, well-known methods, structures and techniques are not shown in detail so as not to obscure the understanding of this description.

[0043] Similarly, it should be understood that in order to streamline the present invention and aid in understanding one or more of the various inventive aspects, in the above description of exemplary embodiments of the present invention, various features of the present invention are sometimes grouped together into a single embodiment, figure, or description thereof. However, this disclosed method should not be interpreted as reflecting the intention that the claimed invention requires more features than those expressly recited in each claim. Rather, as reflected in the claims, inventive aspects lie in less than all of the features of the individual embodiments previously disclosed. Therefore, the claims that follow the detailed description are hereby expressly incorporated into the detailed description, with each claim itself serving as a separate embodiment of the present invention.

[0044] In addition, those skilled in the art will appreciate that, although some embodiments described herein include certain features included in other embodiments but not other features, the combination of features of different embodiments is meant to be within the scope of the present invention and form different embodiments. For example, in the claims, any one of the claimed embodiments may be used in any combination.

Claims

1. A horizontal furnace tube for low pressure chemical vapor deposition, characterized in that: The horizontal furnace tube comprises: a furnace body, in which a deposition process is performed; A pipeline, one end of which is connected to the furnace tail of the furnace body, and the other end is connected to an exhaust pump, and the pipeline is used to transport by-products generated in the deposition process; Wherein, between the one end and the other end of the pipeline, a quick-draw valve and a slow-draw valve, a butterfly valve and a cold trap are sequentially arranged in parallel.

2. The horizontal furnace tube according to claim 1, characterized in that: It further includes a hand valve arranged on the pipeline, wherein the hand valve is located between the cold trap and the exhaust pump.

3. The horizontal furnace tube according to claim 1 or 2, characterized in that: It further comprises a heat preservation bag, which is arranged around the quick-draw valve, the slow-draw valve, the butterfly valve and the cold trap.

4. The horizontal furnace tube according to claim 3, characterized in that: The temperature range of the heat preservation bag is 150°C to 200°C.

5. The horizontal furnace tube according to claim 1, characterized in that: A plurality of wafer boats for placing wafers are arranged in the furnace body.

6. The horizontal furnace tube according to claim 5, characterized in that: The furnace body has a furnace opening, and the wafer enters the furnace body through the furnace opening and is placed on the wafer boat.

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