ECR plasma CVD device

Abstract

The present invention avoids re-adsorption of a reaction product in self-cleaning of an ECR plasma CVD device. This ECR plasma CVD device comprises: a plasma generation chamber (102) that generates plasma by ECR; a reaction chamber (101) that is connected to the plasma generation chamber (102); a gas introduction pipe (107) that introduces a raw material gas into the reaction chamber (101); an exhaust port (108) that is provided on the reaction chamber (101) side and that discharges from the inside of the reaction chamber (101) and the inside of the plasma generation chamber (102); and an exhaust pipe (201) that is provided on the plasma generation chamber (102) side and that discharges from the inside of the reaction chamber (101) and the inside of the plasma generation chamber (102).

Description

ECR plasma CVD equipment

[0001] The present invention relates to an ECR plasma CVD apparatus.

[0002] In the fields of semiconductors and optical devices, silicon oxide (SiO ２ ) films and silicon nitride (SiN) films are widely used. For depositing such films, plasma-enhanced chemical vapor deposition (PE-CVD) devices, sputtering devices, etc. are used. Among these film deposition devices, an ECR plasma CVD device is known, which deposits films using plasma generated by electron cyclotron resonance (ECR) (Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2023-062858

[0004] In such an ECR plasma CVD apparatus, when a film is formed on a sample such as a substrate, reaction products adhere to and accumulate in the plasma generation chamber where plasma is generated by ECR and in the reaction chamber where the sample is held. If a film is formed on another sample while reaction products remain attached to the plasma generation chamber and reaction chamber, the reaction products will become foreign matter and contaminate the film-formed product. In order to prevent the reaction products adhering to the plasma generation chamber and reaction chamber from contaminating the product, it is necessary to clean the ECR plasma CVD apparatus.

[0005] Therefore, self-cleaning is sometimes performed in ECR plasma CVD equipment. In self-cleaning, plasma is generated by ECR in the ECR plasma CVD equipment, and a fluorine-based cleaning gas is supplied to the reaction chamber from the gas supply pipe that supplies the raw material gas, thereby generating F radicals (fluorine radicals) from the cleaning gas. Then, reaction products attached to the plasma generation chamber and reaction chamber are gasified by the F radicals, and the gasified reaction products are exhausted from an exhaust port in the reaction chamber. This is intended to remove the reaction products attached to the plasma generation chamber and reaction chamber. However, the process pressure for plasma generation by ECR is 10 －２ Pa to 10 －１The pressure is about 100 Pa, which means that the amount of F radicals generated is small, resulting in an insufficient cleaning rate. Furthermore, because the plasma is generated by ECR in this ECR plasma CVD apparatus, a location (hereinafter referred to as an "ECR point") is created in the plasma generation chamber on the reaction chamber side where more charged particles such as free electrons, ions, and radicals are generated than in other locations. At this ECR point, reaction products gasified by F radicals are re-generated into plasma, and the re-generated reaction products are re-adsorbed into the plasma generation chamber, reaction chamber, etc. Therefore, it is desirable to prevent the re-adsorption of reaction products in the self-cleaning of an ECR plasma CVD apparatus.

[0006] Other objects and novel features will become apparent from the description of this specification and the accompanying drawings.

[0007] An ECR plasma CVD apparatus according to one embodiment comprises a plasma generation chamber for generating plasma by ECR, a reaction chamber connected to the plasma generation chamber, a gas introduction system for introducing at least a raw material gas or a cleaning gas into the reaction chamber, a first exhaust system provided on the reaction chamber side for evacuating the inside of the reaction chamber and the inside of the plasma generation chamber, and a second exhaust system provided on the plasma generation chamber side for evacuating the inside of the reaction chamber and the inside of the plasma generation chamber.

[0008] An ECR plasma CVD apparatus according to another embodiment includes a plasma generation chamber for generating plasma by ECR, a reaction chamber connected to the plasma generation chamber, a gas introduction system for introducing a raw material gas into at least the reaction chamber, a first exhaust system provided on the reaction chamber side for evacuating the inside of the reaction chamber and the inside of the plasma generation chamber, a second exhaust system provided on the plasma generation chamber side for evacuating the inside of the reaction chamber and the inside of the plasma generation chamber, a remote plasma source for generating a cleaning gas plasma outside the reaction chamber and the plasma generation chamber, and a cleaning gas plasma introduction system for introducing the cleaning gas plasma from the remote plasma source into the reaction chamber.

[0009] According to one embodiment, re-adsorption of reaction products can be avoided in self-cleaning of an ECR plasma CVD apparatus.

[0010] It is a diagram showing a schematic configuration of an ECR plasma CVD apparatus of a comparative example. It is a diagram showing a schematic configuration of an ECR plasma CVD apparatus to which an RPS is connected. It is a diagram showing a schematic configuration of an ECR plasma CVD apparatus according to embodiment 1. It is a graph showing cleaning efficiency. It is a diagram showing a schematic configuration of an ECR plasma CVD apparatus according to a modified example.

[0011] Specific embodiments will be described in detail below with reference to the drawings. However, the present invention is not limited to the following embodiments. For clarity of explanation, the following description and drawings have been simplified as appropriate. The same elements are given the same reference numerals, and duplicate explanations will be omitted.

[0012] Embodiment 1 Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 schematically shows an ECR plasma CVD apparatus 100 of a comparative example. Note that ECR stands for electron cyclotron resonance, and CVD stands for chemical vapor deposition. In the ECR plasma CVD apparatus 100 of the comparative example, a reaction chamber 101, which is a vacuum chamber in which a substrate S, a sample to be deposited, is placed, is connected to a plasma generation chamber 102, which is a vacuum chamber in which plasma is generated.

[0013] The plasma generation chamber 102 is connected to a microwave generator (not shown) via a waveguide 103, and microwaves, e.g., with a frequency of 2.45 GHz, generated by the microwave generator are introduced into the plasma generation chamber 102. Magnetic coils 104 and 105 are provided around the plasma generation chamber 102. A magnetic field is generated in the plasma generation chamber 102 when current is supplied to the magnetic coils 104 and 105. The interaction between the magnetic field and the microwaves generates electron cyclotron resonance (ECR). In this specification, the region where ECR occurs is referred to as the "ECR region." In this ECR region, a source gas (described below) is ionized to generate plasma. Ions in the generated plasma are transported into the reaction chamber 101 by a diverging magnetic field (shown by a dashed line in FIG. 1 ) oriented toward the substrate S. In FIG. 1 , a location in the ECR region where charged particles, such as free electrons, ions, and radicals, are generated in greater numbers than in other locations is referred to as the "ECR point P."

[0014] The reaction chamber 101 is provided with a substrate support table 106, on which a substrate S, which is an object on which a film is to be formed, is placed so that the surface on which the film is to be formed faces the ECR region.

[0015] A gas inlet pipe 107 serving as a gas introduction system is connected to the reaction chamber 101, and a source gas is introduced into the reaction chamber 101 through the gas inlet pipe 107. A portion of the source gas introduced into the reaction chamber 101 is exhausted to the outside via an exhaust port 108 (described later). Another portion of the source gas introduced into the reaction chamber 101 is expected to flow into the plasma generation chamber 102. The reaction chamber 101 is also provided with an exhaust port 108, which is combined with a vacuum pump such as a dry vacuum pump (DRP) 301 or a turbomolecular pump (TMP) 302 to form a vacuum exhaust system (first exhaust system). The inside of the reaction chamber 101 and the inside of the plasma generation chamber 102 are evacuated by this vacuum exhaust system. Note that the turbomolecular pump 302 cannot be used at atmospheric pressure. Therefore, first, the valve on the dry pump 301 side is opened, and with the valves before and after the turbomolecular pump 302 closed, the inside of the reaction chamber 101 and the inside of the plasma generation chamber 102 are brought to a negative pressure by only the dry pump 301. Thereafter, the valve on the dry pump 301 side is closed, and the valves before and after the turbomolecular pump 302 are opened, and the inside of the reaction chamber 101 and the inside of the plasma generation chamber 102 are evacuated by the turbomolecular pump 302 and the dry pump 301. A gas inlet pipe 109 serving as a gas introduction system is connected to the plasma generation chamber 102, and a source gas may be introduced into the plasma generation chamber 102 from the gas inlet pipe 109. The source gas introduced into the plasma generation chamber 102 is considered to flow into the reaction chamber 101 through the ECR region. The pressure inside the reaction chamber 101 and the plasma generation chamber 102 can be measured, for example, by a pressure gauge (not shown) provided in the reaction chamber 101.

[0016] Next, an operation for forming a film on the surface of the substrate S will be described. Here, a case where a silicon nitride (SiN) film is formed will be described. Silicon hydride (Silane: SiH) is introduced as a source gas from the gas introduction pipe 107 and the gas introduction pipe 109. ４ ) and nitrogen (N ２A mixed gas of these and argon (Ar) is introduced into the reaction chamber 101 and the plasma generation chamber 102 at a predetermined flow rate ratio, while the chambers are evacuated. This maintains the pressure in the reaction chamber 101 and the plasma generation chamber 102 at a predetermined pressure. The source gas may be introduced only through the gas inlet pipe 107. In this state, the source gas is ionized by ECR plasma generated by the interaction between a magnetic field generated by supplying current to the magnetic coils 104 and 105 and the microwaves introduced into the plasma generation chamber 102, thereby generating plasma.

[0017] Ions in the plasma are transported to the reaction chamber 101 and adhere to and deposit on the surface of the substrate S. The material thus deposited on the surface of the substrate S forms a SiN film.

[0018] As described above, in the ECR plasma CVD apparatus 100, when a film is formed on a sample, reaction products and the like adhere and deposit on the inner walls of the plasma generation chamber 102 and reaction chamber 101, the substrate support table 106, and the like. Therefore, self-cleaning is performed in the ECR plasma CVD apparatus 100. In self-cleaning, a fluorine-based cleaning gas is supplied from the gas inlet pipe 107 or from the gas inlet pipes 107 and 109, and an ECR region is generated in the ECR plasma CVD apparatus 100 by ECR. Then, reaction products adhered to the inner walls of the plasma generation chamber 102 and reaction chamber 101, the substrate support table 106, and the like are gasified by F radicals contained in the plasma generated in the ECR region, and the gasified reaction products are exhausted from the exhaust port 108. This aims to remove reaction products adhered to the reaction chamber 101 and the plasma generation chamber 102. However, the process pressure for plasma generation by ECR is 10 －２ Pa to 10 －１The pressure is about 100 Pa, which means that the amount of F radicals generated is small, resulting in an insufficient cleaning rate. Furthermore, since plasma is generated by ECR in the ECR plasma CVD apparatus 100, the reaction products gasified by the F radicals are re-generated into plasma at the ECR point P, and the re-plasmaized reaction products are re-adsorbed onto the inner walls of the plasma generation chamber 102 and reaction chamber 101, the substrate support table 106, etc. Since the reaction products gasified in the plasma generation chamber 102 are always exhausted through the ECR point P, the re-adsorption of the reaction products onto the plasma generation chamber 102 is a particular problem.

[0019] Therefore, it is considered effective to supply a cleaning gas plasma (hereinafter referred to as "cleaning gas plasma") from a remote plasma source (RPS) 110 to the ECR plasma CVD apparatus, as shown in FIG. 2. Specifically, the ECR plasma CVD apparatus 100A shown in FIG. 2 differs from the ECR plasma CVD apparatus 100 shown in FIG. 1 in that it further includes a remote plasma source 110 and a cleaning gas introduction pipe 111. The remote plasma source 110 generates cleaning gas plasma outside the ECR plasma CVD apparatus 100A. The cleaning gas introduction pipe 111 is connected to the reaction chamber 101 and introduces cleaning gas plasma from the remote plasma source 110 into the reaction chamber 101. Thus, the cleaning gas introduction pipe 111, in combination with the remote plasma source 110, constitutes a cleaning gas plasma introduction system. It is considered that a portion of the cleaning gas plasma introduced into the reaction chamber 101 flows into the plasma generation chamber 102. When self-cleaning of the ECR plasma CVD apparatus 100A is performed, the valves (not shown) of the gas inlet pipes 107 and 109 are closed.

[0020] The process pressure of the remote plasma source 110 is approximately 66 Pa to 667 Pa, and the amount of F radicals generated is overwhelmingly greater than that of an ECR plasma CVD apparatus. Furthermore, since ECR is not generated in an ECR plasma CVD apparatus, the ECR point P is not generated, and it was thought that re-adsorption of reaction products due to the gasified reaction products passing through the ECR point P could be avoided. However, in practice, it was found that the self-cleaning of the ECR plasma CVD apparatus 100A is insufficient to remove reaction products. This is thought to be because the width of the plasma generation chamber 102 of the ECR plasma CVD apparatus is narrower than that of the reaction chamber 101, and the plasma generation chamber 102 has a shape that extends long toward the waveguide 103. In other words, this shape of the plasma generation chamber 102 is thought to make it difficult for the cleaning gas plasma introduced into the reaction chamber 101 from the cleaning gas inlet pipe 111 to flow into the plasma generation chamber 102.

[0021] 3, the ECR plasma CVD apparatus 200 according to the first embodiment further includes an exhaust pipe 201 connected to the plasma generation chamber 102. The exhaust pipe 201 is combined with a vacuum pump such as a dry pump (DRP) 301 to form a vacuum exhaust system (second exhaust system). The inside of the reaction chamber 101 and the inside of the plasma generation chamber 102 can be evacuated via the exhaust pipe 201. A rotary pump may be used instead of or in addition to the dry pump 301. The size (diameter) of the exhaust pipe 201 is larger than that of the gas introduction pipe 109. When self-cleaning of the ECR plasma CVD apparatus 200 is performed, valves (not shown) of the gas introduction pipe 107 and the gas introduction pipe 109 are closed.

[0022] Next, self-cleaning in the ECR plasma CVD apparatus 200 according to the first embodiment will be described. Cleaning gas plasma is introduced into the reaction chamber 101 from the remote plasma source 110. A portion of the cleaning gas plasma introduced into the reaction chamber 101 flows into the plasma generation chamber 102. Thereafter, F radicals contained in the cleaning gas plasma gasify reaction products adsorbed on the inner walls of the plasma generation chamber 102 and the reaction chamber 101, and on the substrate support table 106, and the gasified reaction products are exhausted from the reaction chamber 101 and the plasma generation chamber 102 via the exhaust port 108 and the exhaust pipe 201. In the present invention, the cleaning gas refers to NF ３ , C.F. ４ , C ２ F ６ , C ３ F ８ , C ４ F ８ , SF ６ It is a gas containing the following:

[0023] In the ECR plasma CVD apparatus 200 according to the first embodiment, gasified reaction products are exhausted from the reaction chamber 101 and the plasma generation chamber 102 not only through the exhaust port 108 connected to the reaction chamber 101 but also through the exhaust pipe 201 connected to the plasma generation chamber 102. This facilitates the flow of cleaning gas plasma from the reaction chamber 101 into the plasma generation chamber 102. Furthermore, since the ECR plasma CVD apparatus 200 does not generate ECR, the ECR point P is not generated, and re-adsorption of reaction products caused by the gasified reaction products passing through the ECR point P can be avoided. This makes it possible to avoid re-adsorption of reaction products during self-cleaning of the ECR plasma CVD apparatus 200.

[0024] Next, an experiment examining the cleaning efficiency of the ECR plasma CVD apparatus 200 according to the first embodiment will be described. FIG. 4 shows a graph illustrating the experimental results. The horizontal axis of the graph in FIG. 4 represents the pressure (Pa) inside the reaction chamber 101 and the plasma generation chamber 102, and the vertical axis represents the etching rate (nm / min) of the reaction products. Specifically, a substrate on which a film of reaction products was formed was placed on the substrate support table 106 of the ECR plasma CVD apparatus 200, and the etching rate of the reaction products from the substrate was measured. In the experiment, cleaning gas plasma was introduced into the reaction chamber 101 from the remote plasma source 110 of the ECR plasma CVD apparatus 200 via the cleaning gas introduction pipe 111. The circular legends in the graph in FIG. 4 indicate experimental data obtained when exhaust was performed using only the exhaust port 108. The triangular legends in the graph in FIG. 4 indicate experimental data obtained when exhaust was performed using both the exhaust port 108 and the gas introduction pipe 109. Furthermore, the square legends in the graph shown in FIG. 4 indicate experimental data obtained when exhaust was performed using the exhaust port 108 and the exhaust pipe 201. As can be seen from the circular legends in FIG. 4 , there was no significant difference in the etching rate (nm / min) whether the pressure was approximately 170 to 180 (Pa) or approximately 300 (Pa). In other words, even if the pressure inside the reaction chamber 101 and the plasma generation chamber 102 increased, the inflow of cleaning gas plasma into the plasma generation chamber 102 was not promoted. Furthermore, as can be seen from a comparison of the triangular legends and circular legends when the pressure was approximately 170 to 180 (Pa), there was no significant difference in the etching rate (nm / min) even when exhaust was performed via the gas introduction pipe 109, which was originally connected to the plasma generation chamber 102, in addition to exhaust via the exhaust port 108. In contrast, as can be seen from the legend of the squares at pressures of approximately 170 to 180 (Pa), the etching rate (nm / min) became significantly faster when exhaust through the exhaust pipe 201 was added to exhaust through the exhaust port 108. Specifically, the etching rate (nm / min) was approximately eight times higher in the case of exhaust through the exhaust port 108 and the exhaust pipe 201, in the case of exhaust through the exhaust port 108 only, and in the case of exhaust through the exhaust port 108 and the gas introduction pipe 109.That is, it was found that when exhausting through the exhaust port 108 and the exhaust pipe 201, the cleaning efficiency was significantly improved compared to when exhausting through only the exhaust port 108 and when exhausting through the exhaust port 108 and the gas inlet pipe 109. This is thought to be because exhausting using the exhaust pipe 201 greatly promoted the inflow of cleaning gas plasma into the plasma generation chamber 102. Furthermore, when exhausting through the exhaust port 108 and the gas inlet pipe 109, the etching rate (nm / min) was not improved compared to when exhausting through only the exhaust port 108. This is thought to be because the thickness (diameter) of the gas inlet pipe 109 was small. Therefore, it is preferable that the thickness (diameter) of the exhaust pipe 201 is at least larger than that of the gas inlet pipe 109. The suitable thickness (diameter) of the exhaust pipe 201 is determined appropriately depending on the position where the exhaust pipe 201 is connected to the plasma generation chamber 102, the pressure inside the reaction chamber 101 and the plasma generation chamber 102, etc.

[0025] The present invention is not limited to the above-described embodiments and may be modified as appropriate without departing from the spirit and scope of the present invention. For example, FIG. 5 shows an ECR plasma CVD apparatus 200A according to a modification of the first embodiment. As shown in FIG. 5, the ECR plasma CVD apparatus 200A does not include a remote plasma source 110, and no cleaning gas is supplied to the ECR plasma CVD apparatus 200A from the remote plasma source 110. In the ECR plasma CVD apparatus 200A, a cleaning gas is introduced into the ECR plasma CVD apparatus 200A through a gas inlet pipe 107 or through both the gas inlet pipe 107 and the gas inlet pipe 109, and is converted into plasma in the ECR plasma CVD apparatus 200A. The gasified reaction product is then exhausted from the ECR plasma CVD apparatus 200A via an exhaust port 108 and an exhaust pipe 201.

[0026] This application claims priority based on Japanese Patent Application No. 2024-035838, filed March 8, 2024, the disclosure of which is incorporated herein in its entirety by reference.

[0027] 200, 200A ECR plasma CVD apparatus 101 Reaction chamber 102 Plasma generation chamber 103 Waveguide 104, 105 Magnetic coil 106 Substrate support 107 Gas inlet pipe (gas inlet system) 108 Exhaust port (first exhaust system) 109 Gas inlet pipe (gas inlet system) 110 Remote plasma source 111 Cleaning gas inlet pipe (cleaning gas plasma inlet system) 201 Exhaust pipe (second exhaust system) 301 Dry pump 302 Turbo molecular pump P ECR point S Substrate

Claims

1. An ECR plasma CVD apparatus comprising: a plasma generation chamber that generates plasma by ECR; a reaction chamber connected to the plasma generation chamber; a gas introduction system that introduces at least a raw material gas or a cleaning gas into the reaction chamber; a first exhaust system that is provided on the reaction chamber side and evacuates the inside of the reaction chamber and the inside of the plasma generation chamber; and a second exhaust system that is provided on the plasma generation chamber side and evacuates the inside of the reaction chamber and the inside of the plasma generation chamber.

2. An ECR plasma CVD apparatus comprising: a plasma generation chamber that generates plasma by ECR; a reaction chamber connected to the plasma generation chamber; a gas introduction system that introduces at least a raw material gas into the reaction chamber; a first exhaust system that is provided on the reaction chamber side and evacuates the inside of the reaction chamber and the plasma generation chamber; a second exhaust system that is provided on the plasma generation chamber side and evacuates the inside of the reaction chamber and the plasma generation chamber; a remote plasma source that generates a cleaning gas plasma outside the reaction chamber and the plasma generation chamber; and a cleaning gas plasma introduction system that introduces the cleaning gas plasma from the remote plasma source into the reaction chamber.

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