Cleaning method for reaction cavity of high-density plasma chemical vapor deposition machine table

Abstract

The invention discloses a method for cleaning a reaction cavity of a high-density plasma chemical vapor deposition machine, which comprises the following steps of: arranging a ceramic disc for loading radio frequency on a wafer bearing device in the reaction cavity, arranging a fixed seat on the periphery of the wafer bearing device, and lifting the ceramic disc along the axis direction to generate a first distance with the wafer bearing device; first gas is introduced into the reaction cavity for cleaning treatment; and after cleaning is completed, opening an air hole of the wafer bearing device to introduce a second gas so as to form a cooling air flow between the wafer bearing device and the ceramic disc, and depositing a protective dielectric film into the reaction cavity at the same time. According to the cleaning method provided by the invention, electrostatic damage caused by high-density plasma bombardment can be prevented, and the service life of the wafer bearing device is guaranteed, so that the airflow stability during airflow cooling is further guaranteed, the temperature and pressure stability in the reaction cavity is improved, and the operation stability of a machine table is effectively guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of semiconductor manufacturing, and in particular to a cleaning method for a reaction chamber of a high-density plasma chemical vapor deposition machine. Background Art

[0002] Plasma enhanced processes, such as plasma enhanced chemical vapor deposition (PECVD) processes, high density plasma chemical vapor deposition (HDPCVD) processes, plasma immersion ion implantation processes (P3I) and plasma etching processes have become indispensable in semiconductor processing.

[0003] In the reaction chamber of a high-density plasma chemical vapor deposition machine, the electrostatic chuck (ESC) is a workpiece that is in direct contact with the wafer and realizes the adsorption and desorption of the wafer, and is crucial in the process. During the plasma treatment, the reaction chamber, ceramic disc and electrostatic chuck (ESC) need to be cleaned. After cleaning, the wafer is sent into the reaction chamber. In order to reduce particle contamination, a protective dielectric film (Season Film) needs to be deposited on the exposed inner wall surface of the reaction chamber and the surface of the ceramic disc. However, in the existing processing process, the residual film in the cavity is bombarded by high-density plasma, which causes the edge of the electrostatic chuck and the chuck fixing to be easily damaged. On the one hand, it leads to a short life of the electrostatic chuck and high cost of frequent replacement. On the other hand, it leads to instability during subsequent airflow cooling, which further leads to unstable air pressure and temperature in the cavity.

[0004] Therefore, there is a need in the prior art for an improved cleaning method for a reaction chamber of a high-density plasma chemical vapor deposition machine. Summary of the invention

[0005] In view of this, the purpose of an embodiment of the present invention is to propose a cleaning method for a reaction chamber of a high-density plasma chemical vapor deposition machine, by automatically lifting the ceramic disc so that the cleaning gas can more thoroughly clean the oxide film at the bottom of the disc and the edge of the electrostatic chuck, and when depositing the protective dielectric film, a cooling air flow is introduced from the bottom of the electrostatic chuck to the surface to prevent the protective dielectric film from being deposited on the surface of the electrostatic chuck and contaminating the wafer in subsequent processes.

[0006] Based on the above purpose, an embodiment of the present invention provides a cleaning method for a high-density plasma chemical vapor deposition machine reaction chamber, wherein a ceramic disc for loading radio frequency is provided on a wafer carrier in the reaction chamber, and a fixing seat is provided on the periphery of the wafer carrier. The cleaning method comprises the following steps:

[0007] Lifting the ceramic disc along the axis direction to create a first distance between the ceramic disc and the wafer supporting device;

[0008] Introducing a first gas into the reaction chamber for cleaning;

[0009] After cleaning is completed, the air holes of the wafer carrier are opened to introduce the second gas to form a cooling airflow between the wafer carrier and the ceramic disc, and at the same time, a protective dielectric film is deposited into the reaction chamber.

[0010] In some embodiments, the wafer carrier is an electrostatic chuck.

[0011] In some embodiments, the first spacing is 0.8-1.2 cm.

[0012] In some embodiments, the first gas is nitrogen trifluoride.

[0013] In some embodiments, the introduction time of nitrogen trifluoride is 20 to 30 seconds.

[0014] In some embodiments, the second gas is helium.

[0015] In some embodiments, a plurality of retractable pins are disposed between the electrostatic chuck and the ceramic disc, and the plurality of retractable pins are deployed along the axis of the ceramic disc through an automatic program of the machine to lift the ceramic disc.

[0016] In some embodiments, the protective dielectric film deposition location includes: an inner wall of a reaction chamber and a surface of a ceramic disk.

[0017] In some embodiments, the protective dielectric film is a silicon oxide film.

[0018] In some embodiments, the distance between the top plane of the fixing base and the top plane of the wafer carrying device is 0.5-1 mm.

[0019] The present invention has at least the following beneficial technical effects:

[0020] The method of the present invention focuses on the problem of electrostatic damage that is prone to occur at the edge of the wafer carrier in the prior art, and improves the cleaning method of the machine reaction chamber. The ceramic disc is automatically lifted during the cleaning process to expose the wafer carrier, so that the back of the ceramic disc and multiple edge positions of the wafer carrier are thoroughly cleaned during gas cleaning, and the oxide layer remaining in the wafer deposition process is removed, preventing electrostatic damage caused by high-density plasma bombardment, and ensuring the life of the wafer carrier, thereby further ensuring the stability of the airflow during airflow cooling, thereby improving the stability of the temperature and pressure in the reaction chamber, and effectively ensuring the stability of the machine operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other embodiments can be obtained based on these drawings without paying creative work.

[0022] Figure 1 A schematic diagram of a device in a reaction chamber that is damaged in the prior art;

[0023] Figure 2 A flow chart of an embodiment of a high-density plasma chemical vapor deposition machine reaction chamber cleaning method provided by the present invention;

[0024] 1. Wafer; 2. Wafer carrier; 3. Fixed seat. DETAILED DESCRIPTION

[0025] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the embodiments of the present invention are further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field of the present invention; the terms used in this specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. For example, the directions or positions indicated by the terms "length", "width", "up", "down", "left", "right", "front", "back", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. are based on the directions or positions shown in the drawings, which are only for the convenience of description and should not be understood as limitations on the present technical solution.

[0027] The terms "including" and "having" and any variations thereof in the specification and claims of the present invention and the above-mentioned drawings are intended to cover non-exclusive inclusions; the terms "first", "second", etc. in the specification and claims of the present invention or the above-mentioned drawings are used to distinguish different objects rather than to describe a specific order. "Multiple" means two or more, unless otherwise clearly and specifically defined.

[0028] In the specification and claims of the present invention and the above-mentioned drawings, when an element is referred to as being "fixed to" or "mounted on" or "disposed on" or "connected to" another element, it may be directly or indirectly located on the other element. For example, when an element is referred to as being "connected to" another element, it may be directly or indirectly connected to the other element.

[0029] In addition, reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present invention. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0030] In the process of high-density plasma chemical vapor deposition (HDP-CVD) equipment, arc discharge is easy to occur between the back of the wafer outer edge and the electrostatic chuck, accompanied by excessive leakage current, which will damage the base and its peripheral components, seriously threatening the stability and safety of the lower electrode assembly. Figure 1 The figure shows a schematic diagram of a device in a reaction chamber that is damaged, wherein a ceramic disc (not shown) for loading radio frequency is provided on a wafer carrier 2 in the reaction chamber, and a fixing seat 3 is arranged on the periphery of the wafer carrier 2. Electrostatic damage is easily caused at the contact position between the fixing seat 3, the wafer carrier 2 and the wafer 1, resulting in edge damage. Therefore, the present invention provides a method for cleaning a reaction chamber of a high-density plasma chemical vapor deposition machine, such as Figure 2 The method flow is shown, and the cleaning method specifically includes:

[0031] S1, lifting the ceramic disc along the axis direction to create a first distance between the ceramic disc and the wafer supporting device;

[0032] S2, introducing a first gas into the reaction chamber for cleaning;

[0033] S3. After cleaning is completed, the air holes of the wafer carrier are opened to introduce the second gas to form a cooling airflow between the wafer carrier and the ceramic disc, and at the same time, a protective dielectric film is deposited into the reaction chamber.

[0034] Furthermore, in S1, the wafer carrying device is an electrostatic chuck (ESC), and the ceramic disc is lifted along the axial direction to create a distance of 0.8 to 1.2 cm from the electrostatic chuck, preferably 1 cm. Among them, the electrostatic chuck is one of the more valuable components in semiconductor equipment. Taking the etching equipment as an example, during the wafer processing process, it mainly provides support for the back of the wafer, ensures its fixation by electrostatic adsorption, and provides a dynamic constant temperature for the wafer. After the wafer enters the reaction chamber, a clamping voltage (3600 to 4000V) is first generated to ensure adsorption between the wafer and the ESC.

[0035] Furthermore, in S1, the ceramic disc can be automatically lifted and lowered by an automatic program. There are multiple retractable pins between the electrostatic chuck and the ceramic disc. The multiple retractable pins are unfolded along the axial direction of the ceramic disc by the automatic program of the machine to lift the ceramic disc.

[0036] Further, in S2, nitrogen trifluoride is introduced into the reaction chamber for cleaning. In some embodiments, the nitrogen trifluoride is introduced for 20 to 30 seconds. After the cleaning gas is introduced, it can react with the silicon dioxide film originally deposited and remaining in the reaction chamber to remove the silicon dioxide film.

[0037] Further, in S3, after cleaning is completed, the air holes of the wafer carrier are opened to allow helium to pass through, providing helium of a certain pressure, and the space between the wafer and the ESC is gradually filled with helium. Helium, as a good heat transfer medium, takes away the excess heat on the wafer. At the same time, a protective dielectric film is deposited into the reaction chamber, and the deposition position of the protective dielectric film includes: the inner wall of the reaction chamber and the surface of the ceramic disc. In some embodiments, the protective dielectric film is a silicon oxide film.

[0038] Furthermore, the fixing seat is slightly lower than the top of the wafer supporting device. In some embodiments, the distance between the top plane of the fixing seat and the top plane of the wafer supporting device is 0.5-1 mm.

[0039] The method of the present invention lifts the ceramic disc during the cleaning step to expose the bottom of the ceramic disc, the edge of the electrostatic chuck and the edge of the fixing part of the electrostatic chuck, so that the cleaning is more thorough, and the oxide film around the electrostatic chuck is completely removed, thereby reducing electrostatic damage and effectively extending the service life of the wafer carrier, that is, the electrostatic chuck. After cleaning, the machine has a more stable thin film deposition capability, does not need to adjust the machine frequently, and the number of machine downtimes is significantly reduced.

[0040] The above are exemplary embodiments disclosed in the present invention, but it should be noted that various changes and modifications may be made without departing from the scope disclosed in the embodiments of the present invention as defined in the claims. The functions, steps and / or actions of the method claims according to the disclosed embodiments described herein do not need to be performed in any particular order. In addition, although the elements disclosed in the embodiments of the present invention may be described or required in individual form, they may also be understood as multiple unless explicitly limited to the singular.

[0041] It should be understood that, as used herein, the singular forms "a", "an" are intended to include the plural forms as well, unless the context clearly supports an exception. It should also be understood that, as used herein, "and / or" refers to any and all possible combinations including one or more of the associated listed items.

[0042] The serial numbers of the embodiments disclosed in the above embodiments of the present invention are only for description and do not represent the advantages or disadvantages of the embodiments.

[0043] A person skilled in the art should understand that the discussion of any of the above embodiments is only exemplary and is not intended to imply that the scope of the disclosure of the embodiments of the present invention (including the claims) is limited to these examples; under the concept of the embodiments of the present invention, the technical features in the above embodiments or different embodiments can also be combined, and there are many other changes in different aspects of the embodiments of the present invention as above, which are not provided in detail for the sake of simplicity. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of the present invention should be included in the protection scope of the embodiments of the present invention.

Claims

1. A method for cleaning a reaction chamber of a high-density plasma chemical vapor deposition machine, characterized in that: A ceramic disc for loading radio frequency is provided on a wafer carrier in the reaction chamber, and a fixing seat is arranged on the periphery of the wafer carrier. The cleaning method includes: Lifting the ceramic disc along the axis direction to create a first distance between the ceramic disc and the wafer supporting device; Introducing a first gas into the reaction chamber for cleaning; After cleaning is completed, the air holes of the wafer carrier are opened to introduce the second gas to form a cooling airflow between the wafer carrier and the ceramic disc, and a protective dielectric film is deposited into the reaction chamber at the same time.

2. The method for cleaning a reaction chamber of a high-density plasma chemical vapor deposition machine according to claim 1, characterized in that: The wafer carrying device is an electrostatic chuck.

3. The method for cleaning a reaction chamber of a high-density plasma chemical vapor deposition machine according to claim 1, characterized in that: The first spacing is 0.8-1.2 cm.

4. The method for cleaning a reaction chamber of a high-density plasma chemical vapor deposition machine according to claim 1, characterized in that: The first gas is nitrogen trifluoride.

5. The method for cleaning a reaction chamber of a high-density plasma chemical vapor deposition machine according to claim 4, characterized in that: The introduction time of nitrogen trifluoride is 20 to 30 seconds.

6. The method for cleaning a reaction chamber of a high-density plasma chemical vapor deposition machine according to claim 1, characterized in that: The second gas is helium.

7. The method for cleaning a reaction chamber of a high-density plasma chemical vapor deposition machine according to claim 2, characterized in that: A plurality of retractable pins are arranged between the electrostatic chuck and the ceramic disc, and the plurality of retractable pins are unfolded along the axial direction of the ceramic disc through an automatic program of the machine to lift the ceramic disc.

8. The method for cleaning a reaction chamber of a high-density plasma chemical vapor deposition machine according to claim 1, characterized in that: The protective dielectric film deposition positions include: the inner wall of the reaction chamber and the surface of the ceramic disc.

9. The method for cleaning a reaction chamber of a high-density plasma chemical vapor deposition machine according to claim 8, characterized in that: The protective dielectric film is a silicon oxide film.

10. The method for cleaning a reaction chamber of a high-density plasma chemical vapor deposition machine according to claim 1, characterized in that: The distance between the top plane of the fixing seat and the top plane of the wafer carrying device is 0.5-1 mm.

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