Metal embedding method and substrate processing apparatus

Abstract

To form a metal-containing film on a semiconductor wafer to suppress defects in the shape of metal wiring formed in a recess and reduce the specific resistance of the wiring.SOLUTION: A method disclosed herein is a method for embedding a metal in a recess formed in a substrate, and includes the steps of forming a metal nitride film on the substrate in which the recess is formed and embedding the metal nitride in the recess, and then forming a metal film of a metal contained in the metal nitride on the upper surface side of the metal nitride film, and diffusing nitrogen atoms from the metal nitride film side to the metal film side, thereby embedding the metal with a reduced nitrogen content in the recess.SELECTED DRAWING: Figure 2E

Description

[Technical Field]

[0001] The present disclosure relates to a method for embedding metal and a substrate processing apparatus. [Background technology]

[0002] The wiring that constitutes the circuits in a semiconductor device is formed by depositing a metal film on a semiconductor wafer (hereinafter referred to as "wafer") with a recessed portion, for example, by chemical vapor deposition (CVD) or atomic layer deposition (ALD). Meanwhile, as semiconductor devices become increasingly highly integrated, the difficulty of forming wiring is increasing due to the trend toward thinner lines and narrower spacing between wires. Furthermore, because thinner wiring increases resistance, the use of metal materials with low resistivity is being considered.

[0003] For example, Patent Document 1 describes a memory array of a semiconductor memory device. The memory cell array is composed of a laminated body in which a metal layer serving as a control electrode, an intermediate layer, and an insulating layer are stacked. The document describes that the metal layer is a molybdenum layer with low resistance that serves as a control electrode. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-201407 Summary of the Invention [Problem to be solved by the invention]

[0005] The present disclosure provides a technique for suppressing shape defects in metal wiring formed in recesses by depositing a metal-containing film on a semiconductor wafer, and reducing the resistivity of the wiring. [Means for solving the problem]

[0006] The method of the present disclosure is a method for filling a recess formed in a substrate with a metal, the method comprising the steps of: forming a metal nitride film on the substrate having the recesses formed therein and filling the recesses with the metal nitride; Next, a step of forming a metal film of a metal contained in the metal nitride on the upper surface side of the metal nitride film, and diffusing nitrogen atoms from the metal nitride film side to the metal film side, thereby filling the recesses with the metal having a reduced nitrogen content; Contains: [Effects of the Invention]

[0007] According to the present disclosure, it is possible to suppress shape defects in metal wiring formed in recesses by forming a metal-containing film on a semiconductor wafer, and to reduce the resistivity of the wiring. [Brief explanation of the drawings]

[0008] [Figure 1A] 1 is an SEM image showing the surface layer of a wafer to be processed. [Figure 1B] 10 is an SEM image showing the surface layer of a wafer on which a metal film is formed by a method of the comparative example. [Figure 2A] FIG. 2 is a first longitudinal side view of a wafer according to an embodiment of the present invention; [Figure 2B] FIG. 10 is a second longitudinal side view of the wafer according to the embodiment of the process. [Figure 2C] FIG. 10 is a third vertical cross-sectional side view of a wafer according to an embodiment of the present invention; [Figure 2D] FIG. 10 is a fourth longitudinal side view of a wafer according to an embodiment of the present invention; [Figure 2E] FIG. 10 is a fifth longitudinal side view of a wafer according to an embodiment of the present invention; [Figure 2F] FIG. 10 is a sixth longitudinal side view of a wafer according to the embodiment of the process. [Figure 3] 1 is a plan view of a substrate processing apparatus according to an embodiment; [Figure 4] FIG. 2 is a vertical sectional side view showing a processing module of the substrate processing apparatus. [Figure 5A] 1 is a first graph showing test results of Experiment 1. [Figure 5B]2 is a second graph showing the test results of Experiment 1. [Figure 5C] 3 is a third graph showing the test results of Experiment 1. [Figure 5D] 4 is a fourth graph showing the test results of Experiment 1. [Figure 6] 6 is a sixth graph showing the test results of Experiment 1. [Figure 7A] 1 is a first SEM image showing test results for Experiment 2. [Figure 7B] 10 is a second SEM image showing the test results of Experiment 2. [Figure 7C] 10 is a third SEM image showing the test results of Experiment 2. [Figure 8A] 1 is a first SEM image showing test results of a reference example. [Figure 8B] 10 is a second SEM image showing the test results of the reference example. DETAILED DESCRIPTION OF THE INVENTION

[0009] In the following embodiment, a method for filling recesses of a wafer W (hereinafter referred to as a metal filling method) according to the present disclosure will be described based on a processing example in which metal wiring constituting buried word line structures (bWL) of a DRAM is formed on a wafer W made of a Si (silicon) substrate. First, the configuration of the wafer W to be processed will be described with reference to FIG. 1A. FIG. 1A is an SEM image showing a cross section of the surface layer of the wafer W to be processed.

[0010] The detailed shape will be described with reference to FIG. 2A and other figures. The surface layer portion of the wafer W is composed of, for example, a Si layer 10 on the surface of the wafer W and an SiOx film (silicon oxide film) 10a formed on the Si layer 10, with the SiOx film 10a serving as an interlayer insulating layer. As shown in FIG. 2A, which is a schematic cross-sectional view of the surface layer portion, the surface of the Si layer 10 has an array of multiple uneven shapes formed by etching, and these uneven surfaces are covered with the SiOx film 10a. The thickness of the SiOx film 10a is relatively thick, for example, about 60 nm, at the upper end of the sidewall 14, and is relatively thin, about 1 to 3 nm, in other portions. The surface layer portion of the wafer W composed of the Si layer 10 and the SiOx film 10a in this manner includes the recess 11 and the sidewalls 14 on both sides that define the recess 11.

[0011] Each of these recesses 11 is a vertically elongated trench that extends in a direction perpendicular to the paper surface and opens toward the upper surface. As shown in FIG. 1A, the recesses 11 are arranged at intervals of, for example, about 20 to 50 nm, and each recess is a relatively deep and narrow groove. The recesses are formed with an opening width of about 10 to 20 nm and a depth of about 100 to 250 nm. The width of the recess 11 is narrowest at the bottom end, widens toward the top, and is widest at the opening. The width of the sidewalls 14 on both sides that make up the recess 11 is widest at the bottom end, narrows toward the top, and is narrowest at the tip.

[0012] As described above, the sidewall 14 has a long dimension from the base end to the top end and a thin width, and thus has a shape that is easily bent. In this embodiment, a metal-containing film (metal film) 12 is formed in the recess 11 formed by such sidewall 14 to form a wiring metal (metal) 13 having a relatively low resistivity. In this example, as described in the examples below, the objective is to form a metal wiring having a resistivity equal to or higher than that of TiN (titanium nitride), which has been conventionally used. From this perspective, attention was focused on Mo (molybdenum) as a wiring material that can achieve a resistivity lower than that of TiN.

[0013] Before describing the metal filling method of the present disclosure, a comparative method to be compared with the metal filling method of the present disclosure will be described with reference to FIG. 1B. FIG. 1B is an SEM image showing the surface layer of a wafer W on which a metal film 12M has been formed by the comparative method. Note that the metal film 12M has been formed under conditions that result in a film thickness of 10 nm when formed on a flat wafer W. Hereinafter, even when a film is formed on a wafer W having a recess 11 formed therein, it may be simply referred to as a film having a film thickness of 10 nm.

[0014] The metal film 12M is made of Mo (molybdenum). In the comparative metal filling method, the metal film 12M is formed on the wafer W including the structure shown in FIG. 1A using an ALD method for isotropic film formation so as to completely fill the entire recess 11. At this time, the thickness of the metal film 12M formed on the sidewall 14 of the recess 11 increases along the surface of the sidewall 14. Therefore, the metal films 12M formed on opposing sidewall 14 surfaces move closer to each other as their thickness increases.

[0015] Here, it has been confirmed that when the opposing metal films 12M in the recess 11 reach a thickness of, for example, about 10 nm and the gap between them narrows, as shown in FIG. 1B , the two sidewalls 14 constituting the recess 11 bend toward the center of the recess 11 as if they are attracted to each other, thereby narrowing the opening width of the recess 11. This phenomenon is thought to be caused by the metal films 12M growing along the sidewalls 14 being attracted to each other by van der Waals forces. On the other hand, as described above, when the sidewalls 14 bend toward the center of the recess 11 and the opening width narrows, the sidewalls 14 of the recess 11 adjacent to the relevant recess 11 bend outward, thereby widening the opening width. This phenomenon is also called line bending, as it occurs along the extension direction of the trench formed by the recess 11.

[0016] 1B, recesses 11 with narrower opening widths and recesses 11 with wider opening widths are arranged roughly alternately. If metal film 12M is formed in recesses 11 that have been deformed in this way until the entire recesses 11 are filled, the wiring metal in recesses 11 will have both narrow and wide wiring widths, resulting in a defective shape. As described above, it has been found that the metal filling method of this comparative example, in which metal Mo is filled in trenches formed by recesses 11, can reduce the resistivity of the wiring metal compared to TiN, but may result in a defective shape.

[0017] Below, we briefly describe several other comparative configurations that were investigated. To prevent shape defects caused by the metal film 12M in the comparative configurations, a method of forming a metal nitride film with weaker van der Waals forces than a metal film, as in the example described below (FIG. 7A), is considered. The metal nitride film contains Mo and N (nitrogen) as components and does not contain any other elements, and is specifically composed of Mo2N (molybdenum nitride).

[0018] Because metal nitride films have weaker van der Waals forces than metal films, even when formed on the inner surfaces of recesses 11, they exert less force to bend the opposing sidewalls 14, thereby suppressing variations in the width of the wiring metal. However, metal nitride films have a higher resistivity than metal films, specifically about 100 times that of metal films, and therefore, when used to form extremely narrow wiring metals as in this embodiment, the resistance becomes high.

[0019] Therefore, in order to eliminate the high resistivity, we investigated the possibility of performing multiple annealing processes after forming a metal nitride film to release nitrogen from the metal nitride film. However, as shown in the reference examples (FIGS. 8A and 8B) described below, the metal nitride film after the annealing process significantly shrunk and suffered structural damage. As described above, performing multiple annealing processes on the metal nitride film did not solve the problem of the present disclosure.

[0020] As another approach, we also considered depositing a metal film after depositing a metal nitride film. We assumed that providing a metal nitride film on the surface of the sidewall 14, which is thin in the width direction and long in the depth direction, would reinforce the sidewall 14 and make it less likely to bend. We then attempted to suppress the resistivity of the wiring metal itself by depositing a metal film on the metal nitride film. However, because the van der Waals forces between the opposing metal films in the recess 11 are relatively strong, the sidewalls 14 still bend as if attracting each other, and we were unable to suppress the shape defects of the wiring metal due to the metal nitride film and the metal film.

[0021] As described above, after examining various comparative examples, we discovered the process of this embodiment, which can solve the problems of poor shape and reduced resistivity of the wiring metal 13. The wiring technique of this embodiment will be described below with reference to FIGS. 2A to 2F. FIGS. 2A to 2F are enlarged cross-sectional views showing the recess 11 and its two sidewalls 14. As shown in FIG. 2D, the metal-containing film 12 formed in this embodiment includes a lower metal film 12a, a metal nitride film 12b, and an upper metal film 12c. Hereinafter, the lower metal film 12a and the upper metal film 12c may be referred to as metal films 12a and 12c, and the lower metal film 12a, the metal nitride film 12b, and the upper metal film 12c may be simply referred to as films 12a, 12b, and 12c.

[0022] In this embodiment, the process involves depositing a lower metal film 12a (FIG. 2A), a metal nitride film 12b (FIGS. 2B and 2C), and an upper metal film 12c (FIG. 2D) in this order on the wafer W shown in FIG. 1A, followed by an annealing process (FIG. 2E) to form the wiring metal 13 (FIG. 2F).

[0023] Like the metal film 12M of the comparative embodiment, the lower metal film 12a is composed of Mo and does not contain N (nitrogen) or other metals as components. As shown in FIG. 2A, the lower metal film 12a is formed on the surface of the wafer W before processing by, for example, ALD, as in the comparative embodiment. At this time, as in the comparative embodiment described above, the lower metal film 12a is formed to a thickness that does not cause bending of the sidewall 14, i.e., a relatively thin thickness. Specifically, the thickness of the lower metal film 12a is preferably, for example, about 2 to 3 nm, and may be about 7.5 nm if formed thicker. The thickness of the lower metal film 12a that does not cause bending of the sidewall 14 can be determined in advance by a preliminary test or the like.

[0024] As shown in Figure 2A, the lower metal film 12a formed under these film thickness conditions is formed with a substantially uniform thickness on the surface of the SiOx film 10a, specifically, on the inner surface of the recess 11 and on the surface of the SiOx film 10a other than the recess 11. The thin lower metal film 12a reduces the van der Waals force acting between the opposing films 12a, suppressing bending of the sidewall 14. Meanwhile, by providing the lower metal film 12a with a relatively low resistivity so as to contact the SiOx film 10a that forms the side and bottom surfaces of the recess 11, the resistance value of the interface region between the wiring metal 13 (Figure 2F) and the SiOx film 10a can be reduced.

[0025] 1A is heated to, for example, 580°C, and the lower metal film 12a is formed by alternately supplying a molybdenum-containing gas and a reducing gas, which are raw material gases, to the wafer W via a purge gas. The molybdenum-containing gas is, for example, MoO2Cl2 (molybdenum dioxide dichloride) gas, the reducing gas is, for example, H2 gas, and the purge gas is, for example, an inert gas such as Ar (argon) gas. The molybdenum-containing gas, reducing gas, and purge gas do not contain nitrogen as components.

[0026] Next, as shown in FIG. 2B, a metal nitride film 12b is formed on the surface of the lower metal film 12a by, for example, ALD. The metal nitride film 12b contains Mo and N as components, but does not contain any other elements, and is specifically composed of MoN (molybdenum nitride). MoN, which constitutes the metal nitride film 12b, has a higher resistivity and weaker van der Waals forces than Mo. Therefore, even if the metal nitride film 12b is formed on the inner surface of the recess 11, it is possible to prevent the sidewalls 14 facing each other across the recess 11 from bending as if they are attracting each other.

[0027] As the thickness of the metal nitride film 12b on the lower metal film 12a increases, the metal nitride gradually fills the recess 11, eventually completely filling the entire recess 11 (FIG. 2C). The vertical cross section of the metal nitride film 12b that has completely filled the recess 11 has a wedge shape that narrows downward.

[0028] Filling the entire recess 11 with the metal nitride film 12b means that the internal space of the recess 11 is almost completely filled with the metal nitride film 12b, but it is also acceptable for the upper portion of the internal space of the recess 11 to remain slightly after the formation of the metal nitride film 12b. When the entire recess 11 is completely filled with the metal nitride film 12b, the formation of the metal nitride film 12b is completed.

[0029] The metal nitride film 12b is formed by, for example, ALD, by alternately supplying source gases, molybdenum-containing gas and nitrogen-containing gas, to the wafer W shown in FIG. 1A via a purge gas while the wafer W is heated to, for example, 400°C. The molybdenum-containing gas is, for example, MoO2Cl2 gas, and the nitrogen-containing gas is, for example, NH3 (ammonia) gas. The nitrogen-containing gas may also be N2 (nitrogen) gas. The purge gas is, for example, an inert gas such as Ar (argon) gas. The molybdenum-containing gas and purge gas may contain nitrogen as a component, and when a nitrogen-containing purge gas is supplied, the supply of the nitrogen-containing gas described above may not be necessary.

[0030] Next, as shown in FIG. 2D , an upper metal film 12c is formed on the surface of the metal nitride film 12b by the ALD method to a generally uniform thickness. In this case, the upper metal film 12c may be formed by other anisotropic film formation methods. Like the lower metal film 12a, the upper metal film 12c contains Mo as a component but does not contain nitrogen or other metals. Because the upper metal film 12c is formed on the surface of the metal nitride film 12b, there is no need to limit its thickness, as there is for the lower metal film 12a. The lower metal film 12a is preferably formed to a thickness sufficient to perform a process for releasing nitrogen atoms from the metal nitride film 12b, which will be described later. Specifically, the thickness of the upper metal film 12c is preferably approximately 10 to 30 nm. However, the thickness of the upper metal film 12c may be approximately the same as that of the lower metal film 12a, as long as nitrogen atoms can be released from the metal nitride film 12b.

[0031] The metal nitride film 12b, located between the upper and lower metal films 12a and 12c, has its lower and upper surfaces in contact with the upper and lower metal films 12a and 12b, which have a lower nitrogen concentration than the metal nitride film 12b. Therefore, nitrogen in the metal nitride film 12b diffuses into the metal films 12a and 12c through the interface regions between the metal films 12a and 12c and the metal nitride film 12b (solid arrows in FIG. 2E). When the concentration of the diffused nitrogen in the upper metal film 12c, which is in contact with an atmosphere such as a clean reduced-pressure atmosphere or air, increases to a certain level, nitrogen is released from the surface of the upper metal film 12c. To ensure this phenomenon occurs throughout the entire metal-containing film 12, the wafer W on which the upper metal film 12c is formed is subjected to an annealing process.

[0032] In the annealing process, the wafer W placed in a reduced pressure atmosphere is heated to, for example, 580°C, and a reducing gas is supplied. The reducing gas, such as H2 (hydrogen) gas, can suppress oxidation of the metal-containing film 12. This annealing process diffuses nitrogen from the entire region, including the deep portion, of the metal nitride film 12b provided in the recess 11 with a relatively large aspect ratio, thereby equalizing the nitrogen concentration throughout the entire region, including the deep portion, of the metal-containing film 12. The annealing process also promotes the release of nitrogen from the surface of the upper metal film 12c. In this nitrogen release, nitrogen atoms are directly released from the surface of the upper metal film 12c, and also reaction products (nitrogen compounds) of nitrogen and oxygen contained in the film, which originate from, for example, the reducing gas or the molybdenum-containing gas raw material, are released.

[0033] Due to this release, nitrogen continuously diffuses from the metal nitride film 12b, which has a relatively high nitrogen concentration, into the upper metal film 12c, which has a relatively low nitrogen concentration. As a result, the nitrogen concentration in the metal nitride film 12b decreases. The nitrogen concentration in the lower metal film 12a, which is in contact with the metal nitride film 12b, also temporarily increases due to diffusion from the metal nitride film 12b. However, the direction of nitrogen diffusion then changes toward the metal nitride film 12b, where the nitrogen concentration is decreasing, and the nitrogen concentration decreases again.

[0034] By annealing the wafer W on which the upper metal film 12c has been formed as described above, the nitrogen content can be reduced, resulting in the formation of a metal wiring 13 with low resistivity. In this example, the metal wiring 13 is composed of the lower metal film 12a and the metal nitride film 12b. However, the upper metal film 12c may be embedded in the upper region of the recess 11, so that, for example, the upper central portion of the upper metal film 12c is formed. Furthermore, unnecessary upper metal film 12c may be removed by etching or the like. According to the method of this embodiment, after the recess 11 is filled with the metal nitride film 12b, which has relatively low van der Waals forces, the upper metal film 12c is formed on the metal nitride film 12b, and nitrogen is diffused and removed. This reduces the resistivity of the metal wiring 13 and allows the formation of a metal wiring 13 with a uniform width and good shape.

[0035] A substrate processing apparatus 1 capable of carrying out the above series of processes will be described with reference to the plan view of FIG. 3. The substrate processing apparatus 1 is configured, for example, as a multi-chamber vacuum processing apparatus. The substrate processing apparatus 1 includes an atmospheric pressure transfer chamber 22, which is maintained under atmospheric pressure. A load port 21 is provided in front of the atmospheric pressure transfer chamber 22 for transferring a wafer W to and from a transfer container C containing the wafer W. A door 27 is provided on the front wall of the atmospheric pressure transfer chamber 22, and is opened when transferring the wafer W to and from the transfer container C. A transfer arm 25 for transferring the wafer W is also provided within the atmospheric pressure transfer chamber 22. When viewing the atmospheric pressure transfer chamber 22 from the load port 21 side of the atmospheric pressure transfer chamber 22, an alignment chamber 26 for adjusting the orientation and eccentricity of the wafer W is provided on the left wall of the atmospheric pressure transfer chamber 22.

[0036] Two load lock chambers 23, lined up on the left and right, are connected to the wall of the atmospheric pressure transfer chamber 22 opposite the load port 21. The load lock chambers 23 have the function of switching the internal atmosphere between an atmospheric pressure atmosphere and a vacuum atmosphere while accommodating a wafer W. When viewed from the atmospheric pressure transfer chamber 22, a vacuum transfer chamber 24 is disposed at the rear of these load lock chambers 23. The atmospheric pressure transfer chamber 22 and the vacuum transfer chamber 24 are connected to each load lock chamber 23 via a gate valve 29.

[0037] An exhaust mechanism (not shown) is connected to the vacuum transfer chamber 24, and its internal space is kept under vacuum. A transfer arm 28 is provided in the internal space. Process modules 101 to 104 are connected to the sidewall of the vacuum transfer chamber 24, lined up in this order clockwise. Process module 101 is configured to deposit a lower metal film 12a, process module 102 is configured to deposit a metal nitride film 12b, and process module 103 is configured to deposit an upper metal film 12c. Process module 102 corresponds to a metal nitride film deposition module, and process module 103 corresponds to a metal film deposition module. Wafers W are transferred between the process modules 101 to 104 and each load lock chamber 23 by the transfer arm 28.

[0038] Each of the processing modules 101 to 104 includes a processing vessel 51 that is evacuated to create a vacuum atmosphere inside, and a substrate mounting table 55 (FIG. 4) that is provided within the processing vessel 51 and on which a wafer W is placed, and each processing is performed within the processing vessel 51.

[0039] The substrate processing apparatus 1 includes a control unit 20, which is a computer, and the control unit 20 includes a program. The program includes instructions (steps) for carrying out the above-described processing of the wafer W and the transport process of the wafer W. The program is stored in a storage medium, such as a compact disc, a hard disk, a DVD, or a nonvolatile memory, and is read from the storage medium and installed in the control unit 20.

[0040] The control unit 20 outputs control signals according to the program to each part of the substrate processing apparatus 1 to control the operation of each part, specifically, the operations of the processing modules 101 to 104, the opening and closing of each gate valve 29, the operation of the transfer arm 25, the operation of the transfer arm 28, the operation of the exhaust mechanism, the switching of the pressure in the load lock chamber 23, etc.

[0041] Regarding the transfer path of the wafer W in the substrate processing apparatus 1, the wafer W is first transferred in the following order: transfer container C → load port 21 → atmospheric pressure transfer chamber 22 → load lock chamber 23 → vacuum transfer chamber 24 → processing module 101. Then, the wafer W on which the lower metal film 12a has been formed in the processing module 101 is transferred in the following order: processing module 101 → vacuum transfer chamber 24 → processing module 102. The wafer W on which the metal nitride film 12b has been formed in the processing module 102 is transferred in the following order: processing module 102 → vacuum transfer chamber 24 → processing module 103.

[0042] Then, the wafer W on which the upper metal film 12c has been formed in the processing module 103 is transferred in the order of processing module 103 → vacuum transfer chamber 24 → processing module 104. The wafer W which has been annealed in the processing module 104 is transferred in the order of processing module 104 → vacuum transfer chamber 24 → load lock chamber 23 → atmospheric pressure transfer chamber 22, and is returned to the transfer container C.

[0043] Next, a configuration example of the process module 101 will be described using the vertical cross-sectional side view of FIG. 4 as a representative of the process modules 101-104. The process vessel 51 of the process module 101 is made of, for example, aluminum. A transfer port for the wafer W is formed in a sidewall of the process vessel 51, and a gate valve G1 for opening and closing the transfer port is provided. An exhaust duct 52 having, for example, a circular shape with a rectangular cross section is disposed in the upper part of the sidewall of the process vessel 51. A slit 52a is formed along the inner peripheral surface of the exhaust duct 52, and an exhaust port 52b is formed in the outer wall of the exhaust duct 52. A ceiling wall 54 is provided on the upper surface of the exhaust duct 52 so as to close the upper opening of the process vessel 51 via an insulating member 53, and the gap between the exhaust duct 52 and the insulating member 53 is airtightly sealed with a seal ring.

[0044] A substrate mounting table 55 for horizontally supporting a wafer W is provided inside the processing vessel 51. The substrate mounting table 55 is formed in a disk shape from a ceramic material such as aluminum nitride (AlN) or a metal material such as an aluminum or nickel alloy. In this example, a heater 56A for heating the wafer W is embedded in the substrate mounting table 55, and the heater 56A heats the wafer W, for example, to the aforementioned film formation temperature. The outer peripheral region and side surfaces of the upper surface of the substrate mounting table 55 are covered with a cover member made of ceramic such as alumina.

[0045] The substrate mounting table 55 is connected via a support member to an elevating mechanism 57 provided below the processing vessel 51 and is configured to be freely raised and lowered between a processing position indicated by a solid line in FIG. 4 and a wafer W transfer position indicated by a dashed line below that. In FIG. 4, reference numeral 52c denotes a partitioning member that, together with the substrate mounting table 55 raised to the processing position, divides the interior of the processing vessel 51 into upper and lower sections. Three support pins 58 (only two are shown) are provided below the substrate mounting table 55 in the processing vessel 51 so that they can be raised and lowered by an elevating mechanism provided below the processing vessel 51. The support pins 58 are inserted into through holes in the substrate mounting table 55 at the transfer position and are configured to be able to protrude and retract relative to the upper surface of the substrate mounting table 55. These support pins 58 are used to transfer the wafer W between the transfer arm 28 of the vacuum transfer chamber 24 shown in FIG. 3 and the substrate mounting table 55. In the figure, reference numeral 59 denotes a bellows that separates the atmosphere inside the processing chamber 51 from the outside air and expands and contracts in accordance with the vertical movements of the substrate mounting table 55 and the support pins 58, respectively.

[0046] A shower head 61 for supplying various gases into the processing vessel 51 in a shower-like manner is provided in the processing vessel 51, facing the substrate mounting table 55. The shower head 61 includes a main body fixed to the ceiling wall 54 of the processing vessel 51 and a shower plate 62 connected below the main body, with the interior forming a gas diffusion space 63. A circular protrusion that protrudes downward is formed on the periphery of the shower plate 62, and gas discharge holes 64 are formed on the flat inner surface of the circular protrusion. A gas supply mechanism 6A is connected to the ceiling wall 54 and the main body of the shower head 61.

[0047] The gas supply mechanism 6A includes a source gas supply unit 71A configured to supply a source gas to the processing vessel 51, and a reducing gas supply unit 72A configured to supply a reducing gas. The gas supply mechanism 6A further includes two purge gas supply units 73A configured to supply a purge gas. The source gas supply unit 71A includes a source gas supply source 74A and a supply path 75A, and the supply path 75A is provided with, from upstream, a flow rate adjuster M1A, a storage tank T1A, and a valve V1A.

[0048] The reducing gas supply unit 72A includes a reducing gas supply source 76A and a supply path 77A. The supply path 77A is provided with, from upstream to downstream, a flow rate adjuster M2A, a storage tank T2A, and a valve V2A. Each purge gas supply unit 73A includes a purge gas supply source 78A and a supply path 79A. Each supply path 79A is provided with a flow path adjuster M3A and a valve V3A. The supply path 79A of one purge gas supply unit 73A is connected to the source gas supply path 75A to purge the source gas, and the supply path 79A of the other purge gas supply unit 73A is connected to the reducing gas supply path 77A to purge the reducing gas. As described above, the source gas supply unit 71A, the reducing gas supply unit 72A, and the purge gas supply unit 73A are configured to individually supply the source gas, reducing gas, and purge gas into the processing vessel 51, respectively.

[0049] The processing vessel 51 is connected to a vacuum exhaust line 66 via the exhaust port 52b, and a vacuum exhaust unit 67, such as a vacuum pump, is provided downstream of the vacuum exhaust line 66 and configured to evacuate the gas inside the processing vessel 51. A pressure control valve, such as an APC valve (not shown), is provided in the vacuum exhaust line 66 between the processing vessel 51 and the vacuum exhaust unit 67.

[0050] The other process modules 102 to 104 have substantially the same configuration as the process module 101 described above, but differences from the process module 101 will be briefly described below. The process module 102 that forms the metal nitride film 12b has a nitrogen-containing gas supply unit instead of the reducing gas supply unit 72A in Fig. 4, and the supply source 76A becomes a nitrogen-containing gas supply source. The process module 104 that performs the annealing process does not need to be provided with the raw material gas supply unit 71A.

[0051] Using the substrate processing apparatus 1 having the above-described configuration, the operation of performing a series of processes on a wafer W will be described with reference to FIGS. 3 and 4 showing the apparatus 1 and FIGS. 2A to 2F showing film changes. First, the transfer arm 28 receives the wafer W to be processed from the load lock chamber 23 shown in FIG. 3 and transfers the wafer W to the processing module 101 located on the front left. Thereafter, the gate valve G1 of the processing module 101 shown in FIG. 4 is opened, and the transfer arm 28 moves the wafer W into the processing vessel 51 through the loading port. The wafer W is then transferred from the transfer arm 28 to the substrate mounting table 55 using the support pins 58, and the transfer arm 28 is then withdrawn from the processing vessel 51, and the gate valve G1 is closed.

[0052] As described above, the lower metal film 12a is formed in the processing module 101. Based on a recipe for forming the lower metal film 12a to a predetermined thickness, the pressure in the processing vessel 51 and the temperature of the wafer W are adjusted, and a source gas, a reducing gas, and a purge gas are repeatedly supplied to the processing vessel 51 in a predetermined order. This allows the lower metal film 12a to be formed to a predetermined thickness while suppressing bending of the sidewall 14 ( FIG. 2A ) (step of forming a base film).

[0053] Then, the wafer W on which the lower metal film 12a has been formed is unloaded from the processing module 101 in the reverse order of the loading procedure. The wafer W is then transported toward the processing module 102, which is located clockwise from the processing module 101. Thereafter, the wafer W is loaded into the processing module 102 in the same order as the loading procedure into the processing module 101, and a metal nitride film 12b is formed. Based on a recipe for film formation so as to completely fill the recess 11, the pressure in the processing chamber 51 and the temperature of the wafer W are adjusted, and the source gas, nitrogen-containing gas, and purge gas are repeatedly supplied to the processing chamber 51 in a predetermined order. In this way, the metal nitride film 12b is formed to completely fill the entire recess 11 while suppressing bending of the sidewall 14 (FIGS. 2B and 2C) (step of filling the recess 11 with metal nitride).

[0054] Next, the wafer W on which the metal nitride film 12b has been formed is unloaded from the processing module 102 in the same procedure as in the processing module 101, and loaded into the processing module 103 on the clockwise side of the processing module 102, where the upper metal film 12c is formed. The pressure in the processing chamber 51 and the temperature of the wafer W are adjusted based on a preset recipe for forming a film with a predetermined thickness, and the source gas, reducing gas, and purge gas are repeatedly supplied to the processing chamber 51 in a predetermined order. In this way, the upper metal film 12c with a predetermined thickness is formed.

[0055] Thereafter, the wafer W on which the upper metal film 12c has been formed is similarly unloaded from the processing module 103 and loaded into the processing module 104 on the clockwise side of the processing module 103 for annealing. The pressure in the processing chamber 51 and the temperature of the wafer W are adjusted based on a recipe for forming the wiring metal 13 from which nitrogen has been sufficiently removed, and a reducing gas and a purge gas are simultaneously supplied for a predetermined time, such as 3 to 8 hours (a hydrogen gas supply step). This allows nitrogen to be sufficiently diffused and released throughout the entire region, ensuring that nitrogen is more reliably removed from the entire metal-containing film 12 (FIG. 2E). When the wiring metal 13 with reduced resistivity is formed (FIG. 2F), the annealing step is completed (a step of diffusing nitrogen atoms to fill the recesses 11 with a metal having a reduced nitrogen content).

[0056] The wafer W on which the metal wiring 13 has been formed by the annealing process is loaded into the load lock chamber 23 and then returned to the transfer container C via the load port 21. As described above, the substrate processing apparatus 1 and the metal filling method according to the present disclosure can reduce the resistivity and form the metal wiring 13 with a good shape.

[0057] The annealing process, which requires a processing time of several hours, is not limited to being performed in the single-wafer processing module 104. For example, after the upper metal film 12c is formed in the processing module (metal film deposition module) 103, the wafer W is returned to the transfer container C, and the processing in the substrate processing apparatus 1 is completed. After that, a large number of wafers W may be annealed at once in, for example, a batch-type annealing apparatus.

[0058] Furthermore, the substrate processing apparatus 1 is not limited to being equipped with the single-wafer processing modules 101-103. For example, the substrate processing apparatus 1 may be configured with a batch-type heat treatment module that performs film formation and annealing processes consecutively. In this case, after a large number of wafers W before film formation are loaded into the batch-type heat treatment module, the gas supplied to the heat treatment module is sequentially switched to form the lower metal film 12a, the metal nitride film 12b, and the upper metal film 12c in this order. Thereafter, the gas supplied to the heat treatment module is switched to a reducing gas (H2 gas) and the annealing process is performed.

[0059] (Variation) As described in the above embodiment, forming the lower metal film 12a and the metal nitride film 12b in separate process modules 101 and 102 is preferable because it eliminates the need to adjust the pressure and temperature based on the recipe for each film formation process, thereby improving film formation efficiency. However, this is not limited to this. The lower metal film 12a and the metal nitride film 12b may be formed in either process module 101 or process module 102, which reduces the footprint of the substrate processing apparatus 1. For example, when forming the films 12a and 12b in the common process module 101, the gas supply mechanism 6A may be provided with the nitrogen-containing gas supply unit described above. Furthermore, by forming the metal film 12c in process module 101, all of the films 12a to 12c may be formed in process module 101 alone, and annealing may also be performed.

[0060] In the embodiment of the present disclosure, it is preferable that the lower metal films 12a to 12c are formed isotropically; however, as shown in this example, if the side shape of the recess 11 is not perpendicular to the surface but is an inclined surface that widens upward, the films can also be formed by an anisotropic film formation method such as a CVD method.

[0061] The annealing process performed in this embodiment is not limited to the process recipe described above, and the process recipe is appropriately changed depending on the composition, shape, and thickness of the metal-containing film 12. Furthermore, the annealing process is not essential to the method disclosed herein, and other means may be used. An example of such other means is heat treatment of the wafer W in a reduced pressure atmosphere without supplying a reducing gas. Another example is heat treatment of the wafer W in an air atmosphere without supplying a reducing gas. It has been found through experiments and the like that heat treatment is effective for diffusing and removing nitrogen in the metal-containing film 12, and that the temperature of the wafer W may be higher than 580°C and lower than or equal to 850°C. However, the temperature range is not limited to this range, and it is highly likely that the process can be carried out even if the temperature is somewhat outside this range, and it is believed that temperatures up to about 550°C to 900°C are possible.

[0062] The recess 11 in the embodiment of the present disclosure does not necessarily have to be a trench. The metal filling method of the present disclosure is also useful, for example, when providing wiring metal in a via. In particular, when the via is extremely thin and long and the sidewalls that make up the via are thin, the method of the present disclosure can form wiring metal with reduced resistivity and a good shape.

[0063] In the embodiment of the present disclosure, metal-containing film 12 contains Mo as a metal, but is not limited thereto and may be made of other metals with relatively low resistivity, such as aluminum (Al), copper (Cu), tungsten (W), titanium (Ti), silver (Ag), or alloys thereof. In this case, lower metal film 12a and upper metal film 12c do not contain nitrogen as a constituent element.

[0064] In the embodiment of the present disclosure, the lower metal film 12a is formed to reduce the resistance of the wiring metal 13, but this is not an essential condition, and the lower metal film 12a may not be formed. The metal nitride film 12b is formed so as to completely fill the recess 11, but this is not an essential condition, and the upper metal film 12c may be provided in the upper space within the recess 11 without completely filling the upper space. In this case, the metal nitride film 12b should be formed to a thickness sufficient to prevent the sidewall 14 from bending due to the van der Waals force of the upper metal film 12c during film formation.

[0065] Although the upper metal film 12c is formed to cover the entire surface of the metal nitride film 12b in order to efficiently diffuse nitrogen from the metal nitride film 12b, it is merely preferable to cover the entire surface of the metal nitride film 12b as widely as possible, and this does not exclude the case where the upper metal film 12c covers only a portion of the surface of the metal nitride film 12b. The upper metal film 12c may be formed to cover only the opening region of the recess 11 in order to diffuse and release nitrogen from the metal nitride film 12b arranged in the recess 11 upward.

[0066] It should be noted that the embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive, and various omissions, substitutions, modifications, and combinations may be made to the above-described embodiments without departing from the scope and spirit of the appended claims. [Example]

[0067] (Experiment 1) The nitrogen removal effect of the metal nitride film was confirmed for wafers with a metal film formed on the metal nitride film. Specifically, metal films of different thicknesses were formed on the metal nitride film formed on the surface of bare wafers, and the difference in nitrogen removal effect was confirmed. A. Experimental conditions Four unpatterned, flat bare wafers were prepared. Each wafer had a Mo nitride film composed of MoN formed on a SiO2 surface layer, as in the embodiment, and Mo films of varying thicknesses composed of Mo formed on the Mo nitride film. The Mo nitride film was 15 nm thick, and the Mo films were 0 nm (no Mo film formed), 5 nm, 10 nm, and 20 nm thick. These wafers were not annealed, but instead were subjected to a heat treatment under the same conditions in a reduced-pressure atmosphere to sufficiently diffuse and remove nitrogen. After the heat treatment, the surface region of each wafer was subjected to composition analysis using X-ray photoelectron spectroscopy (XPS), and the sheet resistance was measured.

[0068] B. Experimental Results (1) Composition analysis results Figures 5A to 5D show the results of composition analysis of the surface region of each wafer on which a Mo film was formed. Specifically, they show the atomic percentage (At%) at the depth relative to the top surface of each wafer, and these atomic percentages exclude Si (silicon) atoms. Figure 5A shows the results of composition analysis of a wafer on which a Mo film was not formed. A boundary line is shown at the position corresponding to the interface between the Mo nitride film and the SiO2 film. The region shallower than the interface corresponds to the Mo nitride film, and the region deeper than the interface corresponds to the SiO2 film.

[0069] In the Mo nitride film far enough from the interface, the proportions of Mo atoms and N atoms were approximately 50% and slightly higher than 40%, respectively, and the proportion of O (oxygen) atoms was around 5%, and these proportions were roughly constant with depth. The O atoms in this region were presumed to be derived from the source gas mentioned above.

[0070] The region encompassing the aforementioned interface, including both the shallow and deep regions, is the interface between the Mo nitride film and the SiO2 film. In this interface region, atoms other than O rapidly decreased toward the SiO2 film, while O atoms increased. At the SiO2 film far enough from the interface, the Mo atoms were below 10%, the N atoms were nearly zero, and the O atoms were approximately 65%.

[0071] Figure 5B shows the results of a composition analysis of a wafer with a 5-nm Mo film. From this figure, the proportions of Mo, N, and O atoms were roughly constant with depth in the Mo nitride film and Mo film, located far enough from the interface with the SiO2 film. This indicates that N atoms are sufficiently diffused in the Mo nitride film and Mo film. The detailed concentration of each atom shows that the proportion of O atoms increased slightly by 1-2% compared to Figure 5A, the proportion of Mo atoms increased to approximately 65%, and the proportion of N atoms decreased to just under 30%.

[0072] To consider the N atom ratio in this test, we calculated a reference value for the approximate ratio of N atoms that would be uniform in both films if the N atoms in the Mo nitride film were sufficiently diffused into a Mo film with a thickness 1 / 3 of the Mo nitride film. Specifically, based on Figure 5A, we calculated the reference value for the ratio of N atoms that was 42% in the Mo nitride film with a thickness of 1 and then diffused into the Mo nitride film and the Mo film with a thickness of 1 + 1 / 3. Assuming the number of N atoms remains constant before and after diffusion, the relationship 4 / 3 × (reference value) = 1 × 42 holds. Based on this relationship, the reference value for the uniform N atom ratio was 31.5%. In contrast, Figure 5B shows that the N atom ratio was slightly lower than 30%, as previously mentioned. Therefore, we inferred that the number of N atoms in this test decreased due to the release of N atoms from the Mo film.

[0073] Figure 5C shows the results of a composition analysis of a wafer with a 10-nm Mo film, twice the thickness shown in Figure 5B. The figure reveals a concentration gradient of each atom with depth in the Mo nitride film and Mo film, excluding the interface region with the SiO2 film. At the depth corresponding to the Mo film, the proportion of Mo atoms is high, exceeding 95%, especially in the surface region, and decreases with increasing depth from the Mo film. The proportion of N atoms is just under 5% in the Mo film, increases with increasing depth from the interface region between the Mo film and the Mo nitride film, and reaches approximately 15% at an intermediate depth in the Mo nitride film.

[0074] As in Figure 5B, we calculated the reference value for the N atom ratio homogenized in the Mo film by sufficiently diffusing N atoms in the Mo nitride film into a Mo film with a thickness of 2 / 3 of the Mo nitride film. If the N atom ratio, 42% in the Mo nitride film with a thickness of 1, is assumed to have diffused and homogenized in the Mo nitride film and the Mo film with a thickness of 1 + 2 / 3, the relationship 5 / 3 × (reference value) = 1 × 42 holds. The reference value for the homogenized N atom ratio is 25.2%, whereas the N atom ratio in the composition analysis results, as mentioned above, was significantly lower than this reference value at all depths. Therefore, the composition analysis results suggest that doubling the Mo film thickness increased the amount of N atoms released from the Mo film. The O atom ratio was zero in the Mo film, especially at the surface, and increased with increasing depth. This is thought to be due to the release of oxygen along with the release of nitrogen from the Mo film.

[0075] Figure 5D shows the composition analysis results for a wafer with a 20-nm Mo film, four times thicker than that shown in Figure 5B. As shown in Figure 5D, the Mo atom ratio was 100%, while the N and O atom ratios were zero in the region shallower than the intermediate depth of the Mo nitride film. Assuming that the N atom ratio, which was 42% in the Mo nitride film with a thickness of 1, diffused and homogenized in the Mo nitride film and the Mo film with a thickness of 1 + 4 / 3, the relationship 7 / 3 × (reference value) = 1 × 42 holds. The reference value for the homogenized N atom ratio based on this would be 18%, but the N atom ratio in this composition analysis was zero at both depths. Thus, by increasing the Mo film thickness four times, making it thicker than the Mo nitride film, the amount of N atoms released from the Mo film was further increased, and almost all N atoms were removed, essentially converting the Mo nitride film into a Mo film.

[0076] (2) Sheet resistance measurement results Figure 6 is a graph showing the sheet resistance of each wafer with Mo films of different thicknesses. For comparison, the figure also shows the sheet resistance of bare wafers with Mo films and Mo nitride films of varying thicknesses formed on SiO2 films formed on the wafer surfaces, as well as the sheet resistance of TiN (titanium nitride) with a resistivity of, for example, 50 μΩcm and a thickness of 20 nm.

[0077] The sheet resistance of a 5-nm-thick Mo film and a 15-nm-thick Mo nitride film was approximately intermediate between the sheet resistance of the Mo nitride film and that of the Mo film, and the resistivity of the 5-nm-thick Mo film and the Mo nitride film was approximately intermediate between the sheet resistance of the Mo nitride film and that of the Mo film. The sheet resistance of a 10-nm-thick Mo film and a 15-nm-thick Mo nitride film was close to that of a TiN film, and the resistivity of the 10-nm-thick Mo film and the Mo nitride film was comparable to that of a TiN film. The sheet resistance of a 20-nm-thick Mo film and a 15-nm-thick Mo nitride film was reduced to the same level as that of the Mo film, and the resistivity of the 20-nm-thick Mo film and the Mo nitride film was also reduced to the same level as that of the Mo film. These sheet resistance measurements also confirmed that the Mo film removed nitrogen from the Mo nitride film, thereby reducing its resistivity. Furthermore, it was confirmed that increasing the Mo film thickness effectively removed nitrogen, resulting in sheet resistance and resistivity comparable to those of the Mo film.

[0078] (Experiment 2) For wafers with multiple recesses formed on the surface of an SiO2 film, the resistivity and shape changes were checked for the unformed film, Mo film, Mo nitride film, mixed film of Mo film and nitride film, and the mixed film after annealing. A. Experimental conditions Five wafers with multiple recesses similar to those in the embodiment were prepared. One wafer was left uncoated, and two wafers were coated with a Mo film and a Mo nitride film, each with a thickness of 20 nm. The remaining two wafers were coated with a mixed film. The mixed film was formed by a recipe that deposited a 7.5 nm Mo film, a 15 nm Mo nitride film, and a 15 nm Mo film, in that order. One of the wafers was subjected to the annealing treatment (580°C, 3 hours) described in the embodiment. The film-formed portions of each wafer were photographed using a scanning electron microscope (SEM) to confirm changes in shape, and the resistivity was measured. Note that the resistivity was measured using a film formed using the same film-formation recipe on a flat wafer without recesses.

[0079] B. Experimental Results (1) Shape change 7A to 7C show SEM images of the Mo nitride film, the mixed film without annealing treatment, and the mixed film with annealing treatment; SEM images of the unformed film and the Mo film are not shown. The width of the recesses was measured from the captured SEM images, and the bending displacement, which indicates the degree of bending of the sidewalls, was calculated. The width of the recesses alternates between narrow and wide widths due to the bending of the sidewalls. Therefore, the bending displacement was calculated by measuring the width of each recess and calculating the difference between the average wide width and the average narrow width.

[0080] The bending displacement was 7.5 nm for the undeposited film, 31.1 nm for the Mo film, 4.32 nm for the Mo nitride film, 11.2 nm for the unannealed mixed film, and 10.0 nm for the annealed mixed film. This means that the bending displacement of the two mixed films was significantly reduced compared to that of the Mo film, and was able to approach that of the undeposited film. Furthermore, since the bending displacement of the annealed mixed film was slightly smaller than that of the unannealed mixed film, it was thought that a good shape was obtained by the annealing treatment.

[0081] As shown in the grayscale images in Figures 7B and 7C, the unannealed mixed film shows each film as a distinct shade of gray. The annealed mixed film shows no variations in shade, resulting in a uniform film. This confirms that annealing sufficiently diffuses nitrogen within the mixed film, resulting in a uniform nitrogen content. On the other hand, Figure 7B shows that, with the above recipe, a thin, light-gray Mo film covers the sidewalls, and a dark-gray Mo nitride film is formed over the Mo film, completely filling the recess. Furthermore, the light Mo film uniformly covering the surface of the Mo nitride film is thicker than the Mo nitride film on the top of the sidewalls. This is thought to be due to nitrogen diffusion, which causes the interface between the Mo nitride film and the Mo film to become a Mo film.

[0082] (2) Specific resistance The resistance of each wafer was measured after a film was formed using the same recipe on a separate wafer with a flat surface, and the resistivity was calculated from this resistance and the resistivity of the wafer before film formation. The resistivity of the Mo film with a thickness of 20.5 nm was 14 μΩcm, and the resistivity of the Mo nitride film with a thickness of 14 nm was 1294 μΩcm. The resistivity of the non-annealed mixed film with a thickness of 24.1 nm was 15 μΩcm, and the resistivity of the annealed mixed film with a thickness of 28.8 nm was 14 μΩcm. Regardless of whether or not the film was annealed, the resistivity was similar to that of the Mo film. The resistivity of the annealed mixed film was lower than that of the non-annealed mixed film.

[0083] (Reference example) An experiment was conducted to confirm whether nitrogen in the Mo nitride film could be released and removed by annealing without providing a Mo film. In this experiment, a recipe was used to form a 15 nm thick Mo nitride film on a wafer with multiple recesses similar to those in the comparative example, and then the same annealing process as in Experiment 2 above was performed, and each part was examined using an SEM.

[0084] Figure 8A is an SEM image of the surface of the wafer, and Figure 8B is an SEM image of the side of the wafer. Cracks were observed in places on the surface of the annealed Mo nitride film. This is thought to be because the annealing treatment increased the difference in film density between the Mo nitride film and the sidewall, causing the Mo nitride film to shrink and peel off from the sidewall, resulting in fractures. It was also confirmed that stress was generated in the sidewall between the shrunken Mo nitride film and the sidewall, causing structural collapse.

[0085] The resistance of the annealed Mo nitride film was also confirmed. Specifically, the sheet resistance of the annealed Mo nitride film, which was formed on the flat surface of a flat wafer using the same film formation recipe and annealing process, was measured. The results showed that the annealed Mo nitride film had a sheet resistance and resistivity somewhere between those of the Mo nitride film and the Mo film.

[0086] As described above, annealing a Mo nitride film that is not covered with a Mo film does not achieve both the suppression of shape defects and the reduction of resistivity. In contrast, forming a Mo nitride film covered with a Mo film, as in this example, satisfies these requirements, and it was confirmed that the annealing treatment can further improve these effects. Furthermore, the reason why structural collapse was not observed in the annealed mixed film is presumably because the Mo atoms in the Mo film, which has a higher film density than the Mo nitride film, penetrate into the Mo nitride film and suppress shrinkage. As described above, the metal filling method of this example is believed to be able to form wiring metal that suppresses shape defects and reduces resistivity. [Explanation of symbols]

[0087] W wafer 12b Metal nitride film 12c Upper metal membrane 11 Recess 13 wiring metal

Claims

1. 1. A method for filling a recess formed in a substrate with metal, comprising: forming a metal nitride film on the substrate having the recesses formed therein and filling the recesses with the metal nitride; Next, a metal film of the metal contained in the metal nitride is formed on the upper surface side of the metal nitride film, and nitrogen atoms are diffused from the metal nitride film side to the metal film side, thereby filling the recesses with the metal having a reduced nitrogen content.

2. 10. The method of claim 1, wherein embedding the reduced nitrogen content metal comprises heating at a temperature in the range of 550-900° C. under a reduced pressure atmosphere.

3. The method of claim 2 , wherein the heating step includes providing hydrogen gas.

4. The method according to claim 1 , further comprising the step of forming an underlayer of the metal in the recess before the step of filling the recess with metal nitride.

5. The method according to claim 1 , wherein in the step of filling the recess with metal nitride, the metal nitride film is formed so that the metal nitride is filled entirely within the recess.

6. The method of claim 1 , wherein the metal comprising the metal nitride film and the metal film is molybdenum.

7. The method according to claim 1 , wherein the recesses are formed in a plurality of rows along a direction along the surface of the substrate, and each recess is provided so as to extend along a direction intersecting the one direction on the surface of the substrate.

8. 2. The method of claim 1, wherein the metal with reduced nitrogen content has a resistivity in the range of 10 to 50 μΩcm.

9. 1. A substrate processing apparatus for filling a recess formed in a substrate with metal, comprising: a metal nitride film deposition module for forming a metal nitride film on the substrate having the recessed portion formed thereon and filling the recessed portion with the metal nitride; a metal film deposition module for forming a metal film of a metal contained in the metal nitride on an upper surface side of the metal nitride film, and diffusing nitrogen atoms from the metal nitride film side to the metal film side, thereby filling the recesses with the metal having a reduced nitrogen content; A substrate processing apparatus comprising:

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