Thin film deposition method and thin film deposition apparatus

Abstract

To provide a technique that can appropriately control the amount of doping of a desired metal when manufacturing a silicon nitride film.SOLUTION: A film-forming method is forming a silicon nitride film doped with a desired metal on a substrate. This film-formation method includes a step (a) of supplying a silicon-containing gas into a processing container in which the substrate is housed, a step of (b) supplying a metal-containing gas containing the desired metal into the processing container, and a step (c) of supplying a nitrogen-containing gas into the processing container after carrying out the step (a) at least once and carrying out the step (b) at least once.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present disclosure relates to a film forming method and a film forming apparatus.

Background Art

[0002] For example, in 3D-NAND memory, a semiconductor with a stacked silicon nitride film (SiN film) is used to trap high-density charges. The SiN film has a trade-off relationship between charge writing / erasing characteristics and charge holding characteristics. In recent years, in order to improve these characteristics, the development of SiN films doped with a desired metal such as aluminum (Al) has been promoted.

[0003] For example, Patent Document 1 discloses a method for forming a metal-doped layer in which a metal is doped in a low-concentration region when forming the metal-doped layer. Thus, when forming a SiN film doped with a desired metal, it is required to appropriately control the doping amount of the desired metal.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The present disclosure provides a technique capable of appropriately controlling the doping amount of a desired metal during the production of a silicon nitride film.

Means for Solving the Problems

[0006] According to one aspect of the present disclosure, a method for forming a silicon nitride film doped with a desired metal on a substrate, comprising: (a) supplying a silicon-containing gas into a processing container containing the substrate; (b) supplying a metal-containing gas containing the desired metal into the processing container; and (c) performing step (a) at least once, and after performing step (b) at least once, supplying a nitrogen-containing gas into the processing container. The process involves performing steps (a), (b), and (c) to produce a metal-doped layer doped with the desired metal, and further includes a step to produce an undoped layer formed of silicon nitride that is not doped with the desired metal. The process of producing the undoped layer and the process of producing the metal-doped layer are repeated to form a laminated structure of the undoped layer and the metal-doped layer. A film formation method is provided. [Effects of the Invention]

[0007] According to one embodiment, the amount of doping with a desired metal can be appropriately controlled during the production of a silicon nitride film. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic cross-sectional diagram illustrating the overall configuration of a film deposition apparatus according to one embodiment. [Figure 2] Figure 2(A) is a schematic cross-sectional view showing the layered structure of a silicon nitride film. Figure 2(B) is a schematic cross-sectional view showing the single-layer structure of a silicon nitride film. [Figure 3] Figure 3(A) is a flowchart showing the process for manufacturing a layered silicon nitride film. Figure 3(B) is a flowchart showing the process for manufacturing a single-layer silicon nitride film. [Figure 4] This is a flowchart showing the process of forming a SiAlN pattern in the metal-doped layer formation process. [Figure 5] Figure 5(A) is a flowchart showing the AlSiN pattern process in the metal doping layer formation process. Figure 5(B) is a flowchart showing the SiAlSiN pattern process in the metal doping layer formation process. [Figure 6] Figure 6(A) is a graph comparing the amount of Al doping in the AlN layer, AlSiN layer, and SiAlN layer. Figure 6(B) is a graph comparing the amount of Al doping in the SiAlN layer and the SiAlSiN layer. [Figure 7]This is an explanatory diagram illustrating the general effect on the substrate when a SiAlN pattern is implemented. [Figure 8] This is an explanatory diagram illustrating the general effect on the substrate when a SiAlSiN pattern is implemented. [Figure 9] This graph shows the amount of Al doping in the depth direction for SiAlN and SiAlSiN layers. [Modes for carrying out the invention]

[0009] The following describes embodiments for implementing this disclosure with reference to the drawings. In each drawing, the same reference numerals are used for identical components, and redundant explanations may be omitted.

[0010] One embodiment of the present disclosure describes a film deposition method in which a silicon nitride film (SiN film 102; see Figures 2(A) and (B)) doped with a desired metal is deposited on the surface of a substrate 100 using, for example, a film deposition apparatus 1 (substrate processing apparatus) as shown in Figure 1. In order to facilitate understanding of the present disclosure, the configuration of the film deposition apparatus 1 will be described below.

[0011] The film deposition apparatus 1 comprises a processing container 10 for accommodating multiple substrates 100, a gas supply unit 30 for supplying gas into the processing container 10, a gas discharge unit 40 for discharging the gas from the processing container 10, a heating element 50 for heating the processing container 10, and a control unit 80 for controlling each component of the apparatus. Furthermore, this film deposition apparatus 1 is a thermal ALD (Atomic Layer Deposition) apparatus that performs film deposition by heating the substrates 100 with the heating element 50 without using plasma.

[0012] The processing container 10 is formed in a vertically extending cylindrical shape to arrange multiple substrates 100 in a vertical line. For example, the processing container 10 includes a cylindrical inner cylinder 11 with a flat ceiling and an open lower end, and a cylindrical outer cylinder 12 that covers the outside of the inner cylinder 11 and has a dome-shaped ceiling and an open lower end. The inner cylinder 11 and the outer cylinder 12 are made of a heat-resistant material such as quartz and exhibit a double-walled structure with their axes arranged coaxially. The processing container 10 is not limited to a double-walled structure; it may also be a single-walled structure or a multi-walled structure consisting of three or more cylinders.

[0013] A housing portion 13 for accommodating a gas nozzle 31 is provided at a desired circumferential position on the inner cylinder 11, oriented vertically. As an example, the inner cylinder 11 has a convex portion 14 that protrudes radially outward from a part of its side wall and extends vertically, and the housing portion 13 is formed inside this convex portion 14.

[0014] In the inner cylinder 11, a vertically elongated opening 15 is formed in the side wall opposite to the housing section 13. The opening 15 exhausts the gas inside the inner cylinder 11 into the space P1 between the inner cylinder 11 and the outer cylinder 12. The vertical length of the opening 15 is preferably the same as the vertical length of the wafer boat 16 (or longer vertically than the wafer boat 16).

[0015] The lower end of the processing container 10 is supported by a cylindrical manifold 17 made of stainless steel. A flange 18 is formed at the upper end of the manifold 17, projecting radially outward. The flange 18 supports the flange 12f at the lower end of the outer cylinder 12. A sealing member 19 is provided between the flange 12f and the flange 18 to airtightly seal the inside of the outer cylinder 12 and the manifold 17.

[0016] Further, the manifold 17 has an annular support portion 20 protruding radially inward on the upper inner wall. The support portion 20 supports the lower end of the inner cylinder 11. The opening at the lower end of the manifold 17 is hermetically closed by a lid body 21 via a seal member 22. The lid body 21 is formed, for example, as a flat plate from stainless steel.

[0017] A rotating shaft 24 that rotatably supports the wafer boat 16 passes through the central portion of the lid body 21 via a magnetic fluid seal portion 23. The rotating shaft 24 rotates about its axis based on a rotational driving force from a driving source and a drive transmission portion (not shown), thereby rotating the wafer boat 16 about the vertical axis.

[0018] The lower portion of the rotating shaft 24 is supported by an arm 25A of a lifting mechanism 25 constituted by a boat elevator or the like. The film forming apparatus 1 can move the lid body 21 and the wafer boat 16 up and down integrally by lifting and lowering the arm 25A of the lifting mechanism 25, and insert and remove the wafer boat 16 into and from the processing container 10.

[0019] A rotating plate 26 is provided at the upper end of the rotating shaft 24, and the wafer boat 16 that holds the substrate 100 via a heat insulating unit 27 is placed on this rotating plate 26. The wafer boat 16 is a substrate holder that holds the substrate 100 at predetermined intervals in the vertical direction. By the wafer boat 16, each substrate 100 is held along the horizontal direction.

[0020] The gas supply unit 30 is inserted into the processing container 10 via the manifold 17. The gas supply unit 30 introduces gases such as a processing gas, a purge gas, and a cleaning gas into the inner cylinder 11. For example, the gas supply unit 30 has a gas nozzle 31 for introducing a processing gas and a gas nozzle 33 for introducing a purge gas.

[0021] The gas nozzles 31 and 33 are injector tubes made of quartz, extending vertically within the inner cylinder 11 and bending in an L-shape at their lower ends to penetrate the inside and outside of the manifold 17. The gas nozzle 31 has multiple gas holes 32 spaced at regular intervals along the vertical direction, and discharges processing gas horizontally through each gas hole 32. Similarly, the gas nozzle 33 has multiple gas holes 34 spaced at regular intervals along the vertical direction, and discharges purge gas horizontally through each gas hole 34. The spacing between the gas holes 32 and 34 is set to be the same as, for example, the spacing between the substrates 100 supported on the wafer boat 16. In addition, the vertical position of each gas hole 32 and 34 is set to be located midway between adjacent substrates 100 in the vertical direction. This allows the gas holes 32 and 34 to smoothly circulate gas in the space between the substrates 100.

[0022] The gas supply unit 30 supplies the processing gas to the gas nozzle 31 inside the processing container 10 while controlling the flow rate of the processing gas outside the processing container 10. In this embodiment, the film deposition apparatus 1 supplies silicon-containing gas, metal-containing gas, and nitrogen-containing gas as processing gases at different timings in order to deposit a metal-doped SiN film.

[0023] The silicon-containing gas is used to deposit silicon (Si) onto the surface of the substrate 100. Suitable silicon-containing gases include silane compounds such as dichlorosilane (DCS: SiH2Cl2), monochlorosilane (MCS: SiClH3), trichlorosilane (TCS: SiHCl3), silicon tetrachloride (STC: SiN14), and hexachlorodisilane (HCD: Si2Cl6).

[0024] The metal-containing gas is a gas containing the desired metal to dope the SiN film 102. Examples of these desired metals include aluminum (Al), titanium (Ti), zirconium (Zr), and hafnium (Hf). The metal-containing gas is a gas that contains these desired metals and is available for distribution (e.g., a chloride). For example, when doping with Al, aluminum chloride (AlCl3) can be used as the metal-containing gas. Similarly, when doping with Ti, titanium chloride (TiCl4) can be used as the metal-containing gas.

[0025] The nitrogen-containing gas is selected appropriately depending on the silicon-containing gas, metal-containing gas, etc. For example, when the silicon-containing gas and metal-containing gas are chloride-based gases, the nitrogen-containing gas can be ammonia gas (NH3 gas), hydrazine (N2H4) gas, or its derivatives, such as monomethylhydrazine (MMH) gas. Note that the nitrogen-containing gas in this embodiment does not include elemental nitrogen molecules (N2).

[0026] Furthermore, the gas supply unit 30 supplies purge gas to the gas nozzle 33 inside the processing container 10 while controlling the flow rate of the purge gas outside the processing container 10. As the purge gas, for example, an inert gas such as elemental nitrogen (N2) gas or argon (Ar) gas can be used.

[0027] The gas supply unit 30 is not limited to a configuration that supplies processing gas and purge gas into the processing container 10 by two gas nozzles 31 and 33, as shown in Figure 1. The gas supply unit 30 may also be configured to supply silicon-containing gas, metal-containing gas, nitrogen-containing gas, and purge gas separately by three or more (for example, four) gas nozzles. Conversely, the gas supply unit 30 may be configured to supply silicon-containing gas, metal-containing gas, nitrogen-containing gas, and purge gas by a single common gas nozzle.

[0028] The gas discharge section 40 exhausts the gas inside the processing container 10 to the outside. The gas supplied by the gas supply section 30 flows out from the opening 15 of the inner cylinder 11 into the space P1 between the inner cylinder 11 and the outer cylinder 12, and is exhausted through the gas outlet 41. The gas outlet 41 is located on the upper side wall of the manifold 17, above the support section 20. The exhaust passage 42 of the gas discharge section 40 is connected to the gas outlet 41, and in this exhaust passage 42, a pressure regulating valve 43 and a vacuum pump 44 are provided in order from upstream to downstream. The gas discharge section 40 adjusts the pressure (internal pressure) inside the processing container 10 by sucking the gas inside the processing container 10 with the vacuum pump 44 and adjusting the flow rate of the exhausted gas with the pressure regulating valve 43.

[0029] Furthermore, a temperature sensor (not shown) is provided inside the processing container 10 to detect the temperature inside the processing container 10. The temperature sensor can be a thermocouple, resistance thermometer, or the like, and transmits the detected temperature to the control unit 80.

[0030] The heating element 50 is formed in a cylindrical shape that surrounds the processing container 10 and heats each substrate 100 inside the processing container 10 under the control of the control unit 80. The heating element 50 may also be equipped with a temperature control function that supplies cooling gas between the processing container 10 and the heating element 50 in order to cool each substrate 100 inside the processing container 10.

[0031] The control unit 80 can be a computer having a processor 81, memory 82, input / output interfaces (not shown), etc. The processor 81 is a combination of one or more of the following: CPU (Central Processing Unit), GPU (Graphics Processing Unit), ASIN (Application Specific Integrated Circuit), FPGA (Field-Programmable Gate Array), circuit consisting of multiple discrete semiconductors, etc. The memory 82 is a combination of volatile memory and non-volatile memory (e.g., compact disc, DVD (Digital Versatile Disc), hard disk, flash memory, etc.).

[0032] Memory 82 stores the program for operating the film deposition apparatus 1, the process conditions for substrate processing, and other recipes. The processor 81 controls each component of the film deposition apparatus 1 by reading and executing the program from memory 82. The control unit 80 may be composed of a host computer or multiple client computers that communicate information via a network.

[0033] Next, the structure of the SiN film 102 deposited by the above-described film deposition apparatus 1 will be explained with reference to Figure 2.

[0034] The substrate 100 after film formation has a base substrate 101 placed in the processing container 10 before the film formation method is carried out, and a SiN film 102 that is laminated on the surface of the base substrate 101 during film formation. As described above, the SiN film 102 is a film in which SiN having a desired metal is deposited on the base substrate 101, and below we will describe in detail the case in which aluminum (Al) is applied as the desired metal. The SiN film 102 may be formed as a laminated structure 102A in which a plurality of layers are laminated as shown in Figure 2(A), or as a single-layer structure 102B consisting of a single layer as shown in Figure 2(B).

[0035] Specifically, the laminated structure 102A shown in Figure 2(A) alternates between an undoped layer 103 deposited without Al doping and a metal-doped layer 104 deposited adjacent to the undoped layer 103 with Al doping. The thickness of the undoped layer 103 and the metal-doped layer 104 are not particularly limited, but are preferably set in the range of several Å to several nm, for example. In Figure 2(A), the bottom layer adjacent to the base substrate 101 and the top layer of the SiN film 102 are undoped layers 103, but the laminated structure 102A is not limited to this, and the bottom layer may be a metal-doped layer 104, or the top layer may be a metal-doped layer 104.

[0036] The undoped layer 103 of the SiN film 102 is a layer of SiN that does not contain Al, and a well-known method for forming a SiN film can be used. For example, the film deposition apparatus 1 forms the undoped layer 103 by supplying a silicon-containing gas such as DCS from the gas supply unit 30 with each substrate 100 contained in the processing container 10, and then supplying a nitrogen-containing gas such as NH3 after this step.

[0037] The metal-doped layer 104 of the SiN film 102 is a layer of SiN containing Al. There are several methods for forming this metal-doped layer 104, which will be described in detail later, and an appropriate pattern can be selected depending on the amount of Al doping in the SiN film 102 as a whole.

[0038] On the other hand, the single-layer structure 102B shown in Figure 2(B) is formed by continuously depositing a metal-doped layer 105, which is Al-doped, onto a base substrate 101. The method for forming this metal-doped layer 105 can also be appropriately adopted from the patterns described later.

[0039] Next, a film deposition method for depositing a SiN film 102 on a base substrate 101 using the above-described film deposition apparatus 1 will be explained with reference to Figure 3. In forming the laminated structure 102A, as shown in Figure 3(A), the film deposition apparatus 1 performs the following steps in this order: undoped layer formation step (step S100), purging step (step S200), metal-doped layer formation step (step S300), and purging step (step S400). The undoped layer formation step is a step in which the above-described undoped layer 103 that does not contain Al is deposited. The metal-doped layer formation step is a step in which a metal-doped layer 104 containing Al is deposited. The purging step is a step in which, after each of the undoped layer formation step and the metal-doped layer formation step is performed, a purge gas is supplied to the processing container 10 to discharge the gas remaining in the processing container 10.

[0040] Furthermore, in the film deposition method, a decision is made (step S500) whether or not to terminate the film deposition process based on the thickness of the SiN film 102, the number of process repetitions, or the process time. If the film deposition process is to be continued (step S500: NO), the process returns to step S100 and the same steps are repeated. On the other hand, if the film deposition process is to be terminated (step S500: YES), the current film deposition method is terminated. Note that, as described above, if the uppermost layer of the laminated structure 102A is to be an undoped layer 103, the undoped layer formation step should be performed after the YES determination in step S500.

[0041] Thus, by forming the multilayer structure 102A, the film deposition method makes it possible to easily control the thickness of both the undoped layer 103 and the metal-doped layer 104. For example, by varying the process time of the undoped layer 103, the relative thickness of the undoped layer 103 to the metal-doped layer 104 can be changed, thereby adjusting the overall amount of Al doping in the SiN film 102. In other words, by adopting the multilayer structure 102A, the film deposition method makes it easier to control the overall amount of Al doping.

[0042] Then, in the metal dope layer formation process (step S300), the film formation method can be one of the following three manufacturing patterns (a) to (c), depending on the order in which the processing gases are supplied. (a) SiAlN pattern: A metal-doped layer 104 is formed by supplying silicon-containing gas, metal-containing gas, and nitrogen-containing gas in that order. (b) AlSiN pattern: A metal-doped layer 104 is formed by supplying a metal-containing gas, a silicon-containing gas, and a nitrogen-containing gas in that order. (c) SiAlSiN pattern: A metal-doped layer 104 is formed by supplying silicon-containing gas, metal-containing gas, silicon-containing gas, and nitrogen-containing gas in this order.

[0043] Furthermore, the metal doping layer formation process can employ various patterns other than the manufacturing patterns (a) to (c). For example, another pattern for the metal doping layer formation process may involve sequentially supplying a metal-containing gas, a silicon-containing gas, a metal-containing gas, and a nitrogen-containing gas. Alternatively, the SiAlN pattern may involve repeatedly supplying a silicon-containing gas and a metal-containing gas multiple times, followed by the supply of a nitrogen-containing gas. Similarly, the AlSiN pattern may involve repeatedly supplying a metal-containing gas and a silicon-containing gas multiple times, followed by the supply of a nitrogen-containing gas. The SiAlSiN pattern may also involve repeatedly supplying a silicon-containing gas, a metal-containing gas, and a silicon-containing gas multiple times, followed by the supply of a nitrogen-containing gas.

[0044] More specifically, the SiAlN pattern in (a) is formed by sequentially performing the steps shown in Figure 4 in the film deposition method. First, the film deposition apparatus 1 performs a silicon-containing gas supply step in which silicon-containing gas is supplied into the processing container 10 (step S310). After performing this silicon-containing gas supply step for a predetermined period, the film deposition apparatus 1 stops the supply of silicon-containing gas and performs a purging step in which purge gas is supplied into the processing container 10 to discharge the gas inside the processing container 10 (step S311).

[0045] For example, the process conditions in the silicon-containing gas supply process (step S310) may be set to the following conditions. Processing gas: Silicon-containing gas Temperature inside processing container 10: 550℃~630℃ Pressure inside processing container 10: 3 Torr ~ 8 Torr (≒ 400 Pa ~ 1.07 kPa) Flow rate of processed gas: 100 sccm to 3000 sccm

[0046] Subsequently, the film deposition apparatus 1 performs a metal-containing gas supply process, which involves supplying a metal (Al)-containing gas into the processing container 10 (step S312). After performing this metal-containing gas supply process for a predetermined period, the film deposition apparatus 1 stops supplying the metal-containing gas and performs a purging process, which involves supplying a purge gas into the processing container 10 to discharge the gas from the processing container 10 (step S313).

[0047] For example, the process conditions in the metal-containing gas supply process (step S312) may be set to the following conditions. Processing gas: Metal-containing gas (in the case of aluminum-containing gas) Temperature inside processing container 10: 400℃~640℃ Pressure inside processing container 10: 0.1 Torr ~ 5 Torr (≒ 13.3 Pa ~ 667 Pa) Flow rate of processed gas: 100 sccm to 500 sccm

[0048] Furthermore, the film deposition apparatus 1 performs a nitrogen-containing gas supply process in which it supplies nitrogen-containing gas into the processing container 10 (step S314). After performing this nitrogen-containing gas supply process for a predetermined period, the film deposition apparatus 1 stops supplying nitrogen-containing gas and performs a purging process in which it supplies purge gas into the processing container 10 to discharge the gas inside the processing container 10 (step S315).

[0049] For example, the process conditions in the nitrogen-containing gas supply process (step S314) may be set to the following conditions. Processing gas: Nitrogen-containing gas Temperature inside processing container 10: 550℃~630℃ Pressure inside processing container 10: 8 Torr ~ 100 Torr (≒ 1.07 kPa ~ 13.3 kPa) Flow rate of processed gas: 100 sccm to 13000 sccm

[0050] The film deposition apparatus 1 and film deposition method can form a metal-doped layer 104 with the target thickness by sequentially performing each step of the SiAlN pattern described in (a) above. In the following, the metal-doped layer 104 deposited with the SiAlN pattern described in (a) will also be referred to as the SiAlN layer.

[0051] Furthermore, for the AlSiN pattern in (b), the film deposition method is carried out in the order of the steps shown in Figure 5(A). In this case, the film deposition apparatus 1 first performs a metal-containing gas supply step in which a metal (Al)-containing gas is supplied into the processing container 10 (step S320). The process conditions for the metal-containing gas supply step for the AlSiN pattern are the same as those for the metal-containing gas supply step for the SiAlN pattern described above. After performing the metal-containing gas supply step for a predetermined period, the film deposition apparatus 1 stops the supply of the metal-containing gas and performs a purging step in which a purge gas is supplied into the processing container 10 to discharge the gas inside the processing container 10 (step S321).

[0052] Subsequently, the film deposition apparatus 1 performs a silicon-containing gas supply process, which involves supplying silicon-containing gas into the processing container 10 (step S322). The process conditions for the silicon-containing gas supply process for the AlSiN pattern are the same as those for the silicon-containing gas supply process for the SiAlN pattern described above. After performing the silicon-containing gas supply process for a predetermined period, the film deposition apparatus 1 stops supplying the silicon-containing gas and performs a purging process, which involves supplying purge gas into the processing container 10 to discharge the gas from the processing container 10 (step S323).

[0053] Furthermore, the film deposition apparatus 1 performs a nitrogen-containing gas supply process, which involves supplying nitrogen-containing gas into the processing container 10 (step S324). The process conditions for the nitrogen-containing gas supply process for the AlSiN pattern can be the same as those for the SiAlN pattern. After performing the nitrogen-containing gas supply process for a predetermined period, the film deposition apparatus 1 stops supplying nitrogen-containing gas and performs a purging process, which involves supplying purge gas into the processing container 10 to discharge the gas from the processing container 10 (step S325).

[0054] The film deposition apparatus 1 and film deposition method can also form a metal-doped layer 104 with the target thickness by sequentially performing each step of the AlSiN pattern described in (b) above. In the following, the metal-doped layer 104 deposited using the AlSiN pattern in (b) will also be referred to as the AlSiN layer.

[0055] Furthermore, for the SiAlSiN pattern in (c), the film deposition method is carried out by sequentially performing the steps shown in Figure 5(B). In this case, the film deposition apparatus 1 first performs a silicon-containing gas supply step, which involves supplying silicon-containing gas into the processing container 10 (step S330). The process conditions for the silicon-containing gas supply step for the SiAlSiN pattern are the same as those for the silicon-containing gas supply step for the SiAlN pattern described above. After performing this silicon-containing gas supply step for a predetermined period, the film deposition apparatus 1 stops supplying the silicon-containing gas and performs a purging step, which involves supplying purge gas into the processing container 10 to discharge the gas inside the processing container 10 (step S331).

[0056] Then, the film deposition apparatus 1 performs a metal-containing gas supply process, which involves supplying a metal (Al)-containing gas into the processing container 10 (step S332). The process conditions for the metal-containing gas supply process for the SiAlSiN pattern can be the same as those for the metal-containing gas supply process for the SiAlN pattern described above. After performing the metal-containing gas supply process for a predetermined period, the film deposition apparatus 1 stops supplying the metal-containing gas and performs a purging process, which involves supplying a purge gas into the processing container 10 to discharge the gas from the processing container 10 (step S333).

[0057] Subsequently, the film deposition apparatus 1 performs a silicon-containing gas supply process in which silicon-containing gas is supplied again into the processing container 10 (step S334). The process conditions for this silicon-containing gas supply process may be the same as those for step S330, or they may be different. For example, the process conditions may be such that the amount of silicon-containing gas supplied is increased and the internal pressure inside the processing container 10 is increased. After performing this silicon-containing gas supply process for a predetermined period, the film deposition apparatus 1 stops the supply of silicon-containing gas and performs a purging process in which purge gas is supplied into the processing container 10 to discharge the gas inside the processing container 10 (step S335).

[0058] Furthermore, the film deposition apparatus 1 performs a nitrogen-containing gas supply process, which involves supplying nitrogen-containing gas into the processing container 10 (step S336). The process conditions for the nitrogen-containing gas supply process for the SiAlSiN pattern can be the same as those for the nitrogen-containing gas supply process for the SiAlN pattern described above. After performing the nitrogen-containing gas supply process for a predetermined period, the film deposition apparatus 1 stops supplying nitrogen-containing gas and performs a purging process, which involves supplying purge gas into the processing container 10 to discharge the gas from the processing container 10 (step S337).

[0059] The film deposition apparatus 1 and film deposition method can also form a metal-doped layer 104 with a desired thickness by sequentially performing each step of the SiAlSiN pattern in (c) above. In the following, the metal-doped layer 104 deposited with the SiAlSiN pattern in (c) will also be referred to as the SiAlSiN layer.

[0060] The SiAlN layer formed by the SiAlN pattern, the AlSiN layer formed by the AlSiN pattern, and the SiAlSiN layer formed by the SiAlSiN pattern all exhibit essentially the same composition. In other words, they have a structure in which a deposited film made of silicon nitride (SiN) is doped with the metallic aluminum (Al).

[0061] Conventionally, in film deposition methods for forming an Al-doped SiN film, the process involved repeatedly forming an undoped layer 103 through an undoped layer formation process, and forming a metal-doped layer 104 through a metal-doped layer formation process (hereinafter also referred to as the conventional doped layer formation process or AlN pattern) which sequentially performed a metal-containing gas supply process, a purging process, a nitrogen-containing gas supply process, and a purging process. In other words, in the conventional doped layer formation process, the AlN layer is formed by not supplying silicon-containing gas.

[0062] In conventional film formation methods, the amount of Al doping was adjusted by changing the ratio of the number of times the conventional doped layer formation process was performed to the number of times the undoped layer formation process was performed. For example, when the undoped layer formation process and the conventional doped layer formation process are performed in a 1:1 ratio, the amount of Al doping relative to SiN is less when the ratio is 2:1 compared to when the ratio is 1:1. However, changing the ratio to reduce the amount of Al doping increases the thickness of the undoped layer 103, and also makes it easier for the areas containing Al in the SiN film 102 to be locally unevenly distributed.

[0063] In contrast, the film formation method according to this embodiment allows for appropriate variation in the amount of Al doping to SiN by adopting SiAlN, AlSiN, and SiAlSiN patterns in the metal-doped layer formation step. Specifically, the amount of Al doping in the SiN film 102 decreases in the order of AlN layer > AlSiN layer > SiAlN layer, as shown in Figure 6(A). The graph in Figure 6(A) shows the measured amount of Al doping for each layer when the undoped layer formation step and the metal-doped layer formation step are repeated for the same number of cycles (4 cycles).

[0064] Figure 6(B) is a graph comparing the amount of Al doping in the SiAlN layer and the amount of Al doping in the SiAlSiN layer. In Figure 6(B), the SiAlN layer and the SiAlSiN layer were formed to the same thickness by performing the undoped layer formation process and the metal-doped layer formation process the same number of times. As can be seen from this graph, the SiAlSiN layer has an even lower amount of Al doping than the SiAlN layer.

[0065] The principle by which the amount of Al doping varies when a SiAlN pattern is applied versus a SiAlSiN pattern is applied will be explained in detail below with reference to Figures 7 and 8.

[0066] When a SiAlN pattern is formed in the metal-doped layer formation process, as shown in Figure 7, the film formation method first involves supplying, for example, dichlorosilane (DCS) in the silicon-containing gas supply process to deposit DCS onto the undoped layer 103. Next, the SiAlN pattern is formed by supplying, for example, aluminum chloride (AlCl3) in the metal-containing gas supply process to deposit AlCl3 onto the undoped layer 103 and onto the previously deposited DCS. In this case, because DCS is deposited first, the deposition of AlCl3 can be suppressed compared to conventional methods for forming AlN patterns.

[0067] Subsequently, in the SiAlN pattern, chlorine is removed by hydrogen through the supply of a nitrogen-containing gas, such as ammonia (NH3), to form a metal-doped layer 104 (Al-doped SiN) on the undoped layer 103. The metal-doped layer 104 formed in this way can have a lower amount of Al doping than a metal-doped layer using a conventional AlN pattern.

[0068] On the other hand, when a SiAlSiN pattern is applied in the metal-doped layer formation process, as shown in Figure 8, the film formation method results in the same state as in Figure 7 for the first silicon-containing gas supply step and the subsequent metal-containing gas supply step. In other words, DCS adheres to the undoped layer 103, and AlCl3 adheres to the undoped layer 103 and to the previously adhered DCS.

[0069] Next, the silicon-containing gas supply process is performed again in the SiAlSiN pattern. As a result, some of the previously deposited AlCl3 on the undoped layer 103 is peeled off and replaced with DCS. Therefore, the deposits on the undoped layer 103 are in the same state as before the nitrogen-containing gas supply process, with less AlCl3 than in the SiAlN pattern.

[0070] Subsequently, in the nitrogen-containing gas supply process, the SiAlSiN pattern forms a metal-doped layer 104 (Al-doped SiN) on the undoped layer 103. The metal-doped layer 104 formed in this way can have an even lower Al doping than the metal-doped layer 104 formed with the SiAlN pattern.

[0071] Figure 9 is a graph analyzing the amount of Al doping in the depth direction of the SiAlN layer formed by the SiAlN pattern in Figure 7 and the amount of Al doping in the depth direction of the SiAlSiN layer formed by the SiAlSiN pattern in Figure 8. In the graph, the amount of Al doping in the SiAlN layer is shown by a solid line, and the amount of Al doping in the SiAlSiN layer is shown by a thick line. As can be seen from this graph, the amount of Al doping in the film between the SiAlN layer and the SiAlSiN layer is distributed almost uniformly in the depth direction.

[0072] Furthermore, the amount of Al doping in the SiAlSiN layer is generally less than that in the SiAlN layer. This indicates that, as explained in Figure 8, the substitution of Al with Si occurs after the metal-containing gas supply process due to the second supply of silicon-containing gas (DCS), resulting in a decrease in Al content. By applying a semiconductor with Al-doped SiN film 102 in this way to a memory (for example, a 3D-NAND memory), the charge retention characteristics of the memory can be improved. In particular, the charge retention characteristics of the SiN film 102 are further enhanced when the amount of Al doping is low.

[0073] As described above, the film deposition method allows for arbitrary adjustment of the amount of Al doping by supplying a silicon-containing gas during the metal doping layer formation process and by selecting the processing gas supply pattern. Specifically, summarizing the differences in the amount of metal (Al) doping for the metal doped layers 104 formed in each of the above patterns, the amount of Al doping decreases in the order of AlN layer > AlSiN layer > SiAlN layer > SiAlSiN layer. Therefore, the film deposition method allows for stable doping of the SiN film 102 with an appropriate amount of Al by selecting a SiAlN pattern, AlSiN pattern, SiAlSiN pattern (or AlN pattern), etc., according to the total amount of Al doping in the SiN film 102.

[0074] For example, if you want to add a low concentration of Al depending on the specifications of the semiconductor to be manufactured, the film deposition method can be selected to repeat SiAlN patterns or SiAlSiN patterns to form a SiAlN layer or SiAlSiN layer. This makes it possible to obtain a SiN film 102 with a sufficiently low amount of Al doping. Conversely, if you want to add a high concentration of Al, the film deposition method can be selected to repeat AlSiN patterns (or AlN patterns) to form an AlSiN layer (or AlN layer). This makes it possible to obtain a SiN film 102 with a sufficiently high amount of Al doping.

[0075] Furthermore, even when forming the single-layer structure 102B shown in Figure 2(B), the film deposition method allows for the formation of a metal-doped layer 105 with appropriately adjusted Al doping amounts by applying the above-mentioned SiAlN pattern, AlSiN pattern, and SiAlSiN pattern. That is, as shown in Figure 3(B), the film deposition apparatus 1 immediately performs the metal-doped layer formation step (step S600) in the film deposition method for the single-layer structure 102B. During this metal-doped layer formation step, the film deposition apparatus 1 appropriately selects and repeats the SiAlN pattern, AlSiN pattern, SiAlSiN pattern (or AlN pattern). In this case, the film deposition apparatus 1 may repeat the same pattern from among the SiAlN pattern, AlSiN pattern, and SiAlSiN pattern (or AlN pattern), or it may switch to a different pattern to adjust the Al doping amount.

[0076] Furthermore, the film deposition apparatus 1 determines whether or not to terminate the film deposition process based on the film thickness of the SiN film 102, the number of process repetitions, or the process time (step S700). If the film deposition process is to be continued (step S700: NO), the process returns to step S600 and the same steps are repeated. On the other hand, if the film deposition process is to be terminated (step S700: YES), the process proceeds to step S800. In step S800, the film deposition apparatus 1 terminates the current film deposition method by performing a purging process to purge any remaining gas in the processing container 10.

[0077] As a result, even when depositing a single-layer structure 102B, the deposition apparatus 1 can selectively perform SiAlN pattern, AlSiN pattern, SiAlSiN pattern (or AlN pattern) to appropriately adjust the amount of Al doping in the SiN film 102 as a whole. Furthermore, when depositing a single-layer structure 102B, by not interposing an undoped layer 103, it becomes possible to form a thinner overall film thickness of the SiN film 102 while reducing the amount of Al doping, for example.

[0078] The technical ideas and effects of this disclosure, as described in the embodiments above, are described below.

[0079] A first aspect of the present disclosure is a film deposition method for depositing a silicon nitride film (SiN film 102) doped with a desired metal onto a substrate 100, comprising: (a) a step of supplying a silicon-containing gas into a processing container 10 containing the substrate 100 (silicon-containing gas supply step); (b) a step of supplying a metal-containing gas containing a desired metal into the processing container 10 (metal-containing gas supply step); and (c) a step of supplying a nitrogen-containing gas into the processing container 10 after performing step (a) at least once and step (b) at least once (nitrogen-containing gas supply step).

[0080] As described above, the film deposition method can appropriately control the amount of desired metal doping in the production of a silicon nitride film doped with a desired metal. That is, the film deposition method can appropriately adjust the ratio of silicon-containing gas and metal-containing gas on the substrate 100 by performing a silicon-containing gas supply step and a metal-containing gas supply step. Therefore, the film deposition method can stably adjust the amount of desired metal doping to silicon nitride by performing a nitrogen-containing gas supply step after performing the silicon-containing gas supply step and the metal-containing gas supply step at least once.

[0081] Furthermore, the film deposition method involves performing steps (a) and (b) in that order at least once, followed by step (c). This allows the film deposition method to suppress the adhesion of metal-containing gas to the substrate 100, and to reduce the amount of desired metal doping.

[0082] Furthermore, the film deposition method involves performing step (b) and step (c) in that order at least once, and then performing step (c). This allows the film deposition method to increase the adhesion of metal-containing gas to the substrate 100, making it possible to increase the amount of desired metal doping.

[0083] Furthermore, the film deposition method involves performing step (a), step (b), and step (a) in this order at least once, followed by step (c). This allows the film deposition method to replace the metal-containing gas attached to the substrate 100 with a silicon-containing gas, thereby further reducing the amount of desired metal doping.

[0084] Furthermore, the film deposition method includes the steps of: generating an undoped layer 103 formed from silicon nitride that is not doped with the desired metal; and generating a metal-doped layer 104 that is doped with the desired metal by performing steps (a), (b), and (c). The steps of generating the undoped layer 103 and generating the metal-doped layer 104 are repeated to form a laminated structure 102A of the undoped layer 103 and the metal-doped layer 104. As a result, the film deposition method can stably reduce the amount of doping of the desired metal in the entire laminated structure 102A.

[0085] Furthermore, in the process of generating the undoped layer, the steps of supplying silicon-containing gas to the inside of the processing container and supplying nitrogen-containing gas to the inside of the processing container are performed one or more times. As a result, the film deposition method allows for the easy formation of a laminated structure 102A of the undoped layer 103 and the metal-doped layer 104 simply by changing the supply pattern of the processing gas in the same film deposition apparatus 1.

[0086] Furthermore, in the manufacturing method, steps (a), (b), and (c) are repeated multiple times to form a single-layer structure 102B of a metal-doped layer 105 doped with the desired metal. As a result, the manufacturing method can successfully obtain a single-layer structure 102B with precisely controlled amounts of the desired metal doping.

[0087] Furthermore, the desired metal is one or more combinations of aluminum, titanium, zirconium, and hafnium. This allows the manufacturing method to obtain a silicon nitride film with enhanced charge writing and charge retention properties.

[0088] Furthermore, a second aspect of the present disclosure is a film deposition apparatus 1 for depositing a silicon nitride film (SiN film 102) doped with a desired metal onto a substrate 100, comprising: a gas supply unit 30 for supplying a processing gas into a processing container 10 containing the substrate 100; and a control unit 80 for controlling the operation of the gas supply unit 30. The processing gas is a silicon-containing gas, a metal-containing gas containing a desired metal, and a nitrogen-containing gas. The control unit 80 performs the following steps: (a) supplying a silicon-containing gas into the processing container 10; (b) supplying a metal-containing gas into the processing container 10; and (c) performing step (a) at least once, and then performing step (b) at least once, followed by supplying a nitrogen-containing gas into the processing container 10. In this case as well, the film deposition apparatus 1 can appropriately control the amount of doping of the desired metal in the production of a silicon nitride film doped with the desired metal.

[0089] The film deposition method and film deposition apparatus 1 according to the embodiments disclosed herein are illustrative and not restrictive in all respects. The embodiments can be modified and improved in various ways without departing from the scope and spirit of the appended claims. The matters described in the above embodiments can be otherwise configured and combined in a non-consistent manner.

[0090] The film deposition apparatus of this disclosure is not limited to apparatuses that process multiple substrates, but can also be applied to apparatuses that process substrates one at a time, so-called single-wafer apparatuses. [Explanation of symbols]

[0091] 1 Film deposition equipment 10 Processing containers 30 Gas Supply Department 80 Control Unit 100 circuit boards 102 SiN film

Claims

1. A method for forming a silicon nitride film doped with a desired metal on a substrate, (a) A step of supplying a silicon-containing gas into the processing container in which the substrate is housed, (b) A step of supplying a metal-containing gas containing the desired metal into the processing container, (c) The process includes performing the step of (a) at least once, and after performing the step of (b) at least once, supplying nitrogen-containing gas to the inside of the processing container, The process of producing a metal-doped layer doped with the desired metal is carried out by performing the steps described in (a), (b), and (c). Furthermore, the process includes generating an undoped layer formed from silicon nitride that is not doped with the desired metal, The process of generating the undoped layer and the process of generating the metal-doped layer are repeated to form a laminated structure of the undoped layer and the metal-doped layer. Film formation method.

2. Perform the steps in (a) and (b) in this order at least once, and then perform the step in (c). The method for forming a film according to claim 1.

3. The steps of (b) and (c) are performed one or more times in this order, and the step of (c) is performed. The method for forming a film according to claim 1.

4. The process described in (a), the process described in (b), and the process described in (a) are repeated at least once in this order, and then the process described in (c) is performed. The method for forming a film according to claim 1.

5. In the step of generating the undoped layer, the steps of supplying a silicon-containing gas to the inside of the processing container and supplying a nitrogen-containing gas containing nitrogen to the inside of the processing container are performed one or more times. The method for forming a film according to any one of claims 1 to 4.

6. By repeating steps (a), (b), and (c) multiple times, a single-layer structure of a metal-doped layer doped with the desired metal is formed. The method for forming a film according to any one of claims 1 to 4.

7. The desired metal is one or more combinations of aluminum, titanium, zirconium, and hafnium. The method for forming a film according to any one of claims 1 to 4.

8. A film deposition apparatus for depositing a silicon nitride film doped with a desired metal onto a substrate, A gas supply unit that supplies processing gas into the processing container in which the substrate is housed, Includes a control unit that controls the operation of the gas supply unit, The processing gas is a silicon-containing gas, a metal-containing gas containing the desired metal, and a nitrogen-containing gas. The control unit, (a) A step of supplying the silicon-containing gas inside the processing container, (b) A step of supplying the metal-containing gas inside the processing container, (c) Performing the step of supplying the nitrogen-containing gas into the processing container at least once after performing the step of (a) at least once, thereby performing the step of generating a metal-doped layer doped with the desired metal, Furthermore, the process of generating an undoped layer formed of silicon nitride that is not doped with the desired metal is performed. The process of generating the undoped layer and the process of generating the metal-doped layer are repeated to form a laminated structure of the undoped layer and the metal-doped layer. Film deposition equipment.

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