Method for removing titanium oxide film and substrate processing device

Abstract

The purpose of the present invention is to remove a titanium oxide film provided on the surface of a substrate. This method for removing a titanium oxide film on the surface of a substrate includes: a step for supplying a mixed gas containing hydrogen fluoride gas and ammonia gas to the surface of the titanium oxide film to chemically react the titanium oxide film with the mixed gas, and thereby generate a gaseous reaction product from the titanium oxide film to remove the titanium oxide film from the surface of the substrate; and a step for heating the substrate to remove deposits adhering to the substrate when the reaction product is generated.

Description

Titanium oxide film removal method and substrate processing apparatus

[0001] The present disclosure relates to a method for removing titanium oxide films and a substrate processing apparatus.

[0002] The manufacturing process of a semiconductor device includes a step of forming a metal film as a wiring layer on the upper side of a layer containing a metal, such as TiN (titanium nitride) or W (tungsten), on a semiconductor wafer (hereinafter referred to as "wafer"), which is a substrate. When forming such a metal film, an oxide film may be formed in the lower metal-containing layer at a portion that forms a contact with the wiring layer. Because such an oxide film can increase contact resistance, a process of removing the oxide film may be required.

[0003] For example, Patent Document 1 discloses SiO ２ The film is treated with HF (hydrogen fluoride) gas and NH ３ (ammonia) gas was supplied to produce ammonium silicofluoride ((NH ４ ) ２ SiF ６ , AFS) is generated, and AFS is sublimated by heating to produce SiO ２ Etching the film is described.

[0004] Japanese Patent Application Laid-Open No. 2021-180281

[0005] The present disclosure provides a technique capable of removing a titanium oxide film formed on the surface of a substrate.

[0006] The method for removing a titanium oxide film on a surface of a substrate according to the present disclosure comprises the steps of: supplying a mixed gas containing hydrogen fluoride gas and ammonia gas to the surface of the titanium oxide film, causing a chemical reaction between the titanium oxide film and the mixed gas, generating a gaseous reaction product from the titanium oxide film, and removing the gaseous reaction product from the surface of the substrate; and heating the substrate to remove any deposits that have adhered to the substrate when the reaction product was generated.

[0007] According to the present disclosure, it is possible to remove a titanium oxide film formed on the surface of a substrate.

[0008] FIG. 1 is a plan view illustrating a substrate processing apparatus according to a first embodiment; FIG. 2 is a longitudinal sectional side view illustrating a COR processing module of the substrate processing apparatus; FIG. 3 is a longitudinal sectional side view illustrating a PHT processing module of the substrate processing apparatus; FIG. 4 is a view showing a surface layer of a substrate that changes due to processing in the first embodiment; FIG. 5 is a view showing a surface layer of a substrate that changes due to processing in the first embodiment; FIG. 6 is a view showing a surface layer of a substrate that changes due to processing in the first embodiment; FIG. 7 is a view showing a chemical reaction caused by a mixed gas; FIG. 8 is a view showing a TiF ４、 NH ４ FIG. 1 is a graph showing the vapor pressure of F. FIG. 2 is a diagram showing the surface layer of the substrate that changes due to oxide film removal in the second embodiment. FIG. 3 is a diagram showing the surface layer of the substrate that changes due to oxide film removal in the second embodiment. FIG. 4 is a graph showing the atomic composition percentage of various elements of the wafer in Example 1. FIG. 5 is a first graph for comparing the results of Experiment 1. FIG. 6 is a second graph for comparing the results of Experiment 1. FIG. 7 is a graph for comparing the results of Experiment 2.

[0009] (First embodiment)

[0010] 1 illustrates a substrate processing apparatus according to a first embodiment. The substrate processing apparatus 1 is a multi-chamber system including multiple processing modules 101, 102, and 103 configured to perform a film formation process on a substrate W to form a Ru (ruthenium) film as a metal film that will serve as a wiring layer. The processing module 103 is a Ru film formation processing module for forming the Ru film, and the processing modules 101 and 102 are processing modules for removing a Ti (titanium) oxide film formed on the surface of the substrate W as a pre-processing step for the Ru film formation. The structure of the surface layer of the substrate W to be processed will be described later with reference to FIGS. 4A to 4D.

[0011] The processing module 101 is configured to perform a COR (Chemical Oxide Removal) process for removing a Ti (titanium) oxide film from the surface of a substrate W. Specifically, the substrate W is subjected to a COR process using HF (hydrogen fluoride) gas and NH ３A mixed gas containing (ammonia) gas is supplied to the processing module 101. The Ti oxide film chemically reacts with the mixed gas to become a gaseous reaction product, which is then removed from the substrate W. The processing module 102 performs a PHT (Post Heat Treatment) process, which heats the substrate W to remove deposits that adhere to the substrate W when the reaction product is generated. Hereinafter, the processing modules 101, 102, and 103 may also be referred to as the COR processing module 101, the PHT processing module 102, and the Ru film formation processing module 103.

[0012] 1, in addition to the processing modules 101 to 103, the substrate processing apparatus 1 also includes a loader module 61, a load lock module 62, first and second vacuum transfer modules 63 and 64, and a connection module 65. The loader module 61, the load lock module 62, the first vacuum transfer module 63, the connection module 65, and the second vacuum transfer module 64 are arranged linearly in the front-to-rear direction in this order in a plan view. In the following description of the substrate processing apparatus 1, the side where the loader module 61 is located will be referred to as the front side, and the side where the second vacuum transfer module 64 is located will be referred to as the rear side.

[0013] The loader module 61 includes a housing whose interior is at atmospheric pressure, a transport mechanism 61a for substrates W provided within the housing, and load ports 68. In this example, four load ports 68 are provided side by side on the front side of the housing. A transport container C called a FOUP (Front Opening Unified Pod) for storing substrates W is placed on each load port 68. The transport mechanism 61a is formed of, for example, an articulated arm that can move left and right, and is capable of transporting substrates W between the transport container C on each load port 68 and each load lock module 62.

[0014] In this example, three load lock modules 62 are provided side by side as viewed from the front. Each load lock module 62 has a housing, and the housing is connected to the loader module 61 and the first vacuum transfer module 63 via gate valves (not shown) provided on the front and rear sides of the housing. Each load lock module 62 can freely change the pressure inside the housing between atmospheric pressure and vacuum pressure when the gate valves on the front and rear sides of the housing are closed. A stage on which a substrate W is placed is also provided within the housing. The stage has a plurality of substrate support pins that can protrude from its surface, allowing the substrate W to be transferred to and from the transfer mechanism 61a and the vacuum transfer mechanism 69 (described later), which each access the load lock module 62.

[0015] The first and second vacuum transfer modules 63, 64 are similarly configured and each include a housing 63a, 64a and a vacuum transfer mechanism 69 provided in the housing 63a, 64a. One end of an exhaust pipe is connected to the housing 63a, 64a, and the inside of the housing 63a, 64a is evacuated by a vacuum exhaust mechanism connected via the exhaust pipe, thereby maintaining a vacuum atmosphere. The vacuum exhaust mechanism uses, for example, a turbo molecular pump to create a high vacuum (for example, 1.33×10) inside the housing 63a, 64a. ―５ Pa (1 x 10 ―７ By keeping the pressure at the pressure lower than the pressure in the vacuum chamber (less than 1000 MPa (Torr)), oxidation of the underlying layer before the Ru film is formed may be suppressed.

[0016] In this example, two connection modules 65 are provided side by side. Each connection module 65 has a housing, which is connected to the housings 63 a, 64 a of the vacuum transfer modules 63, 64. By exhausting air using the vacuum exhaust mechanism, the inside of the housing of the connection module 65 is also created into a vacuum atmosphere with the same pressure as the inside of the housings 63 a, 64 a. Each connection module 65 is provided with a stage configured similarly to the stage of the load lock module 62 described above, and is configured to be able to transfer the placed substrate W between the vacuum transfer mechanisms 69 of the first and second vacuum transfer modules 63, 64.

[0017] A COR processing module 101 and a PHT processing module 102 are provided on both the left and right sides of the housing 63a of the first vacuum transfer module 63 when viewed from the front side. The COR and PHT processing modules 101 and 102 are connected to the housing 63a via gate valves G1. Substrates W are transferred between the COR and PHT processing modules 101 and 102 and the load lock module 62 by a vacuum transfer mechanism 69, which is formed by, for example, an articulated arm that can move back and forth and left and right. The vacuum transfer mechanism 69 also transfers substrates W between the COR and PHT processing modules 101 and 102, and from the connection module 65 to the load lock module 62.

[0018] Two Ru film formation processing modules 103 are arranged side by side in front and behind on the left and right sides of the housing 64a of the second vacuum transfer module 64 when viewed from the front side. Each Ru film formation processing module 103 is connected to the housing 64a via a gate valve G1. The transfer of substrates W between these Ru film formation processing modules 103 and the connection module 65 is performed by, for example, the vacuum transfer mechanism 69 of the second vacuum transfer module 64.

[0019] The substrate processing apparatus 1 includes a control unit 200, which is a computer, and the control unit 200 includes a program. The program incorporates instructions (steps) for carrying out each of the above-described processes of removing an oxide film from a substrate W, heating, forming a film, and transporting the substrate 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 200.

[0020] The control unit 200 outputs control signals to each part of the substrate processing apparatus 1 according to the program, and controls the operation of each part. Specifically, the control unit 200 controls the operation of the processing modules 101 to 103, opening and closing of the gate valve G1 and the like, the operation of the transfer mechanism 61a and the vacuum transfer mechanism 69, the operation of the exhaust mechanism, and switching of the pressure in the load lock module 62. The control of the operation of the processing modules 101 to 103 includes, for example, temperature control of the substrate W by supplying power to a heater or the like (to be described later), control of the power supplied by a high-frequency power supply (to be described later), and control of the supply and cut-off of each gas into the processing vessel 51.

[0021] Here, we will explain the transport path of the substrate W in the substrate processing apparatus 1. The substrate W is first transported in the order of the transport container C → loader module 61 → load lock module 62 → first vacuum transport module 63 → COR processing module 101. Then, the substrate W that has undergone COR processing in the COR processing module 101 is transported in the order of the COR processing module 101 → first vacuum transfer module 63 → PHT processing module 102.

[0022] The substrate W on which the PHT processing has been performed in the PHT processing module 102 is transported in the following order: PHT processing module 102 → first vacuum transfer module 63 → connection module 65 → second vacuum transfer module 64 → Ru film formation processing module 103. The substrate W on which the Ru film has been formed in the Ru film formation processing module 103 is transported in the following order: Ru film formation processing module 103 → second vacuum transfer module 64 → connection module 65 → first vacuum transfer module 63 → load lock module 62 → loader module 61, and then returned to the transfer container C.

[0023] The configurations of the process modules 101 to 103 will be described with reference to Figures 2 and 3, which show longitudinal side views of the representative COR process module 101 and PHT process module 102. Regarding the configuration of the common parts, the process modules 101 to 103 each include a process vessel 51 that is evacuated to create a vacuum atmosphere inside, a shower head 52 provided at the top of the process vessel 51, and a substrate mounting table 53 provided within the process vessel 51.

[0024] The shower head 52 is disposed in the processing vessel 51 so as to face the substrate mounting table 53, and its interior forms a gas diffusion space (not shown). The lower part of the shower head 52 constitutes a shower plate, and the shower plate has a plurality of through holes formed therein so as to uniformly release various gases supplied to the gas diffusion space toward the surface of the substrate W mounted on the substrate mounting table 53. An outlet hole to which a gas supply mechanism (described later) is connected is formed in the center of the upper part of the shower head 52.

[0025] Three substrate support pins (not shown) are provided to be movable up and down on the substrate mounting table 53 in the processing vessel 51. The substrate support pins are inserted into through holes formed in the substrate mounting table 53 and protrude and retract relative to the upper surface of the substrate mounting table 53, thereby enabling the transfer of the substrate W between the vacuum transfer mechanism 69 shown in FIG.

[0026] An exhaust pipe 54 having an exhaust hole at its upstream end is connected to the bottom of the processing vessel 51, and a pressure control valve, such as an APC valve (not shown), is provided in the exhaust pipe 54. An exhaust mechanism 55 is provided at the downstream end of the exhaust pipe 54. Each of the processing modules 101 to 103 includes a gas supply mechanism for supplying various gases into the processing vessel 51 via the shower head 52, and is configured to perform various processes on a substrate W placed on a substrate mounting table 53.

[0027] 2, the COR processing module 101 includes a mixed gas supply mechanism 7A as a gas supply mechanism. The mixed gas supply mechanism 7A supplies HF gas and NH ３ a HF gas supply mechanism 71, an NH ３ The HF gas supply mechanism 71 includes an HF gas supply source 71a, a pipe 71b for supplying HF gas to the shower head 52, and a flow rate adjusting mechanism M1 provided on the pipe 71b for adjusting the supply flow rate of HF gas. ３ The gas supply mechanism 72 supplies NH ３The mixed gas supply mechanism 7A includes a gas supply source 72a, a pipe 72b, and a flow rate adjustment mechanism M2. As will be described later in an embodiment, the mixed gas supply mechanism 7A described above may include an inert gas supply mechanism (not shown) so as to supply a mixed gas containing an inert gas.

[0028] HF gas and NH ３ The supply flow rates of the inert gases are, for example, the same, 10 sccm (standard cubic centimeters / min) to 200 sccm, and specifically, 20 sccm. ２ ) is supplied at a flow rate higher than that of the mixed gas, for example, about 130 sccm for each. The mixed gas and the inert gas are supplied simultaneously for, for example, 50 seconds or more, preferably 100 to 400 seconds, specifically 300 seconds. The pressure atmosphere in the processing vessel 51 is set to, for example, 13.3 Pa (0.1 Torr) to 133 Pa (1 Torr), specifically 66.6 Pa (0.5 Torr).

[0029] The substrate mounting table 53 of the COR processing module 101 has a mechanism for controlling the temperature of the substrate W. The sidewall of the processing container 51 of the COR processing module 101 and the shower head 52 are provided with heaters (not shown) for setting the temperature to a preset value, such as 60° C.

[0030] As shown in FIG. 3, the gas supply mechanism 7B of the PHT processing module 102 is ２ A gas supply mechanism 73 is provided. ２ The gas supply mechanism 73 supplies N ２ The gas supply mechanism 7B is composed of a gas supply source 73a, a pipe 73b, and a flow rate adjusting mechanism M3. ２ In addition to the gas supply mechanism 73, it is preferable to provide a supply mechanism for reducing gas. ２ (Hydrogen) gas supply mechanism 74 and NH ３ A gas supply mechanism 75 is provided.

[0031] N ２ The gas supply flow rate is, for example, 100 sccm to 5000 sccm, and specifically, 4000 sccm. ２The gas supply flow rate is, for example, 100 sccm to 5000 sccm, and specifically, 2000 sccm. ３ The gas supply flow rate is, for example, 100 sccm to 5000 sccm, specifically 4000 sccm. These gases are supplied simultaneously for, for example, 10 to 100 seconds, specifically 20 seconds. The pressure inside the processing chamber 51 is set to, for example, 133 Pa (1 Torr) to 4000 Pa (30 Torr), specifically 1333 Pa (10 Torr).

[0032] The processing vessel 51 and substrate mounting table 53 of the PHT processing module 102 are both grounded. The shower head 52 is attached to the processing vessel 51 via a ring-shaped insulating member 57 and connected to a high-frequency power supply 79 via a matching box 78 to function as an upper electrode. The matching box 78 matches the internal impedance of the high-frequency power supply 79 with the load impedance, and the high-frequency power supply 79 applies power to the shower head 52 at a preset frequency so as to convert various gases supplied by the gas supply mechanism 7B into plasma. The substrate mounting table 53 is attached to the bottom of the processing vessel 51 via the insulating member 58 and functions as a lower electrode.

[0033] The PHT processing module 102 as described above converts various gases supplied between the shower head 52 and the substrate mounting table 53 into plasma and supplies the plasma to the substrate W. The substrate mounting table 53 of the PHT processing module 102 is provided with a heater 56 that utilizes, for example, resistance heat, and the heater 56 heats the temperature of the placed substrate W to a temperature higher than the temperature of the substrate W in the COR processing, for example, 400°C within a range of 100 to 500°C.

[0034] The Ru film forming module 103 is configured to form a Ru film by, for example, thermal CVD (individual components are not shown). The gas supply mechanism of the Ru film forming module 103 includes, for example, a CO (carbon monoxide) gas supply mechanism and a Ru source gas supply mechanism. The Ru source gas supply mechanism supplies Ru source gas, for example, using CO gas as a carrier gas. ３ (CO) １２The Ru film forming module 103 is configured to supply a dodecacarbonyltriruthenium (DTC) gas into the processing chamber. The gas supply mechanism supplies a Ru source gas and a CO gas, for example, simultaneously. In the Ru film forming module 103, a heater provided on the substrate mounting table heats the substrate W to a temperature in the range of, for example, 150°C to 200°C.

[0035] In the substrate processing apparatus 1 of the present disclosure having the above-described configuration, removal of a Ti oxide film formed on the surface of a substrate W and formation of a Ru film are performed. These processing operations will be described with reference to FIGS. 1 to 3. The first and second vacuum transfer modules 63 and 64 are first conditioned to a vacuum atmosphere at a preset pressure, and in the processing modules 101 to 103, the exhaust mechanism 55 adjusts the pressure inside the processing vessel 51 to the preset vacuum atmosphere. In the PHT processing module 102 and the Ru film formation processing module 103, the substrate mounting table 53 is first heated to the aforementioned temperature.

[0036] 4A to 4D are longitudinal side views showing the surface layer of a substrate W to be processed in the oxide film removal process and film formation process of the present disclosure. As shown in Fig. 4A, the surface layer of the substrate W before processing includes, for example, a TiN (titanium nitride) layer 11 and a SiOx layer 12 formed on the TiN layer 11. The SiOx layer 12 has a plurality of vertically elongated recesses 13 formed by etching. Note that Figs. 4A to 4D show only one recess 13.

[0037] The recess 13 is provided for forming a wiring layer and opens to the surface of the substrate W. The lower end of the recess 13 reaches the TiN layer 11. The surface of the TiN layer 11 exposed in the recess 13 is naturally oxidized to form a Ti oxide film 11a by contact with the atmosphere during transport of the substrate W to the substrate processing apparatus 1, for example. The TiN layer 11 can be referred to as a metal-containing layer in the claims and can be said to correspond to the base of the Ti oxide film 11a. The Ti oxide film 11a contains, for example, O (oxygen), N (nitrogen), and Ti (titanium).

[0038] 1, the substrate W with the exposed Ti oxide film 11a is received by the vacuum transfer mechanism 69 in the first vacuum transfer module 63 and transferred to the COR processing module 101. The gate valve G1 of the COR processing module 101 is then opened, and the vacuum transfer mechanism 69 causes the substrate W to enter the processing vessel 51 through the loading port. The substrate W is then transferred to the substrate mounting table 53, and the vacuum transfer mechanism 69 is then moved out of the processing vessel 51, and the gate valve G1 is closed.

[0039] As described above, the substrate mounting table 53 of the COR processing module 101 has a temperature control mechanism, and the temperature of the substrate W mounted on the substrate mounting table 53 is, for example, within a range of 20 to 100°C, specifically, room temperature of 35°C. The pressure inside the processing vessel 51 is adjusted based on a recipe, and a mixed gas and an inert gas are supplied. This causes a chemical reaction between the Ti oxide film 11a and the mixed gas, generating a gaseous reaction product 11b from the Ti oxide film 11a, thereby removing the Ti oxide film 11a from the surface of the substrate W (step of generating a reaction product and removing it from the surface of the substrate, FIG. 4B ).

[0040] The chemical reaction between the Ti oxide film 11a and the mixed gas will be described with reference to Fig. 5. As shown in Fig. 5(a), on the surface of the substrate W, a chemical reaction occurs between the HF gas in the mixed gas and the Ti oxide film 11a, resulting in the formation of TiF as a reaction product 11b. ４ (titanium fluoride), and water (H ２ O) is produced.

[0041] FIG. 6 shows the TiF ４ and NH, which will be described later. ４ 1 is a graph showing the vapor pressure of TiF (ammonium fluoride). ４ The water vapor has a relatively high vapor pressure and becomes a gas under the temperature and pressure in the processing vessel 51, and is removed from the processing vessel 51 by exhausting using the exhaust mechanism 55. The reaction product 11b, which is a gas, is removed from the substrate W after being generated. Although not shown in FIG. 6, the water vapor has a relatively high vapor pressure and becomes a gas under the temperature and pressure in the processing vessel 51, and the by-product 11c is TiF ４In this way, the Ti oxide film 11a is removed from the substrate W by reacting with the HF molecules in the mixed gas. ４ and moisture, which is mostly removed from the substrate W (FIG. 5A), exposing the TiN layer 11 (FIG. 5B).

[0042] In parallel with the chemical reaction of the Ti oxide film 11a, HF gas and NH ３ The gas reacts chemically to form NH ４ F (ammonium fluoride) is also produced. ４ Because F has a relatively low vapor pressure ( FIG. 6 ), it does not become a gas under the temperature and pressure conditions within the processing vessel 51. Instead, it remains as deposits 11d on the surface of the substrate W, specifically on the surface of the TiN layer 11 exposed by removing the Ti oxide film 11a ( FIG. 4B ). As shown in FIG. 5( c ), the deposits 11d on the surface of the TiN layer 11 prevent the moisture (by-product 11c) generated during the supply of the mixed gas from coming into contact with the TiN layer 11, thereby preventing oxidation of Ti, which is a metal in the TiN layer 11. The deposits 11d also include gas molecules in the mixed gas, such as HF molecules. The HF molecules attached to the surface of the TiN layer 11 also have the effect of preventing moisture from oxidizing Ti.

[0043] After the Ti oxide film 11a is removed by supplying the mixed gas, the substrate W is unloaded from the COR processing module 101 by the vacuum transfer mechanism 69 of the first vacuum transfer module 63 and transferred to the waiting PHT processing module 102. At this time, since the substrate W is transferred via the first vacuum transfer module 63, which is in a vacuum atmosphere, oxidation of the surface of the TiN layer 11 is suppressed in addition to the effect of the deposits 11d described above.

[0044] The PHT processing module 102 heats the substrate W placed on the substrate placement table 53 to 400° C. as described above, thereby sublimating and removing the deposits 11 d (step of removing deposits, FIG. 4C). ２ Gas, H ２ Gas, NH ３While supplying the gas, high frequency power is supplied to the shower head 52 by the high frequency power supply 79 to form a plasma-like supply gas atmosphere, thereby effectively removing the deposits 11d and preventing oxidation of the TiN layer 11.

[0045] The substrate W, from which the deposits 11d have been removed and the TiN layer 11 is exposed as described above, is transferred from the PHT processing module 102 by the vacuum transfer mechanism 69 of the first vacuum transfer module 63 and transferred to the second vacuum transfer module 64 via the connection module 65. Since the substrate W is transferred via the connection module 65 and the first and second vacuum transfer modules 63 and 64, which are in a vacuum atmosphere, the adhesion of molecules that may cause oxidation or impurities to the surface of the exposed TiN layer 11 is suppressed. The Ru film formation processing module 103 into which the substrate W has been transferred by the second vacuum transfer module 64 supplies Ru source gas and CO gas based on a Ru film formation recipe, and forms a Ru film on the surface of the substrate W, thereby forming a wiring layer 14 in the recess 13 ( FIG. 4D ). Since the PHT processing module 102 removes the deposits 11d from the surface of the substrate W, it is possible to suppress the effects on film formation, such as a decrease in the film formation efficiency of the Ru film, and it is also possible to suppress the deterioration of the electrical performance of the wiring layer 14 due to the incorporation of impurities into the wiring layer 14.

[0046] As described above, according to the film formation method and film formation apparatus of the present disclosure, by supplying a mixed gas to the substrate W in the COR process module 101, a gaseous reaction product 11b and a gaseous by-product 11c are generated and removed by a chemical reaction between the Ti oxide film 11a and the mixed gas. As a result, the Ti oxide film 11a is removed. Then, by attaching a deposit 11d generated by the chemical reaction of the supplied mixed gas to the surface of the TiN layer 11 exposed after the Ti oxide film 11a is removed, oxidation of the TiN layer 11 is suppressed.

[0047] Next, in the PHT processing module 102, the substrate W with the deposits 11d attached thereto is heated to sublimate and remove the deposits 11d, thereby exposing the TiN layer 11. Furthermore, in the PHT processing module 102, the substrate W is exposed to the above-mentioned plasma gas atmosphere, thereby effectively removing the deposits 11d and preventing oxidation of the TiN layer 11. Next, in the Ru film formation processing module 103, a Ru film is formed on the exposed TiN layer 11 in this manner, thereby suppressing an increase in resistance due to the Ti oxide film 11a and the deposits 11d and suppressing their influence on the Ru film formation.

[0048] In the prior art different from the present disclosure, the Ti oxide film 11a is removed using a chlorine-based dry etching gas, for example, Cl ２ A method using (chlorine) gas is known. In this regard, the inventors have found that after removing the Ti oxide film 11a using a dry etching gas containing chlorine, the formation of a Ru film may be hindered. They speculate that this is because the chlorine remaining on the surface of the substrate W inhibits the adsorption of the Ru source gas. In this regard, according to the present disclosure, a chlorine-based dry etching gas is not supplied, so that no Cl molecules that inhibit the formation of a Ru film remain, and a Ru film can be effectively formed.

[0049] (Modification) The metal-containing layer is not limited to the TiN layer 11. For example, it may be a layer containing Ti as a constituent element, or it may not contain Ti as a constituent element, as shown in the second embodiment described later. The Ti oxide film 11a may contain Ti and O as constituent elements, and may contain other elements, for example, without N. The Ru film, which is a metal film, is not limited to this, and may be, for example, another metal film with a relatively low resistivity. In this case, the other metal film is expected to contain at least one metal, such as Al (aluminum), copper (Cu), W (tungsten), Ti (titanium), silver (Ag), or Mo (molybdenum), as a constituent element.

[0050] The PHT processing module 102 is supplied with the aforementioned H ２ , N.H. ３ , N ２However, the present invention is not limited to this combination. ２ , N.H. ３ , N ２ Alternatively, the PHT processing module 102 may supply plasma of at least one gas selected from the group consisting of the above. The PHT processing module 102 need not supply a reducing gas, as long as it can heat the substrate W and remove the deposits 11 d. Even if a reducing gas is supplied, it is not essential that the reducing gas be turned into plasma.

[0051] In the COR process module 101 of the present disclosure, HF gas and NH ３ However, simultaneous supply of these gases is not essential. For example, HF gas and NH ３ The supply of the gases may be performed sequentially, or these gases may be supplied alternately and repeatedly. Although a heating mechanism is provided on the substrate mounting table 53 of the COR processing module 101, a heating mechanism may not be provided, and the substrate W may not be heated.

[0052] In the substrate processing apparatus 1 of the present disclosure, it is not essential to provide the first and second vacuum transfer modules 63, 64 and the connection module 65. For example, the second vacuum transfer module 63 and the connection module 65 may not be provided, and the processing modules 101 to 103 may be arranged around the first vacuum transfer module 63.

[0053] Second Embodiment The oxide film removal of the present disclosure is not limited to the substrate W having the above-described surface layer structure. The oxide film removal of the substrate W1 having the following different surface layer structure can also be performed using HF gas and NH ３ While utilizing the Ti oxide film removal technique using a mixed gas containing a TiO 2 gas, other types of oxide films can also be removed. Figures 7A to 7C are longitudinal side views showing the surface layer of a substrate W1 that changes as a result of oxide film removal according to the second embodiment. The substrate W1 shown in Figure 7A has a W (tungsten) layer 15 provided as an underlying metal-containing layer, and a W oxide film 15a formed by natural oxidation of the surface of the W layer 15 is exposed within the recess 13.

[0054] The substrate processing apparatus 1 in this embodiment includes a processing module (not shown) that forms a Ti film as a pre-processing step for the oxide film removal process performed by the COR and PHT processing modules 101 and 102. The processing module is, for example, a film-forming module for an anisotropic Ti film, and has a structure capable of converting a processing gas into plasma, similar to the PHT processing module 102. However, the gas supply mechanism supplies TiCl, which is a raw material gas for the Ti film, as the processing gas. ４ gas and reactive gas H ２ The heater 56 heats the substrate W to, for example, 300° C. to 600° C. The heater 56 is configured to supply gas.

[0055] In this embodiment, first, the substrate W1 shown in Fig. 7A is heated in the processing module based on a preset Ti film formation recipe. Then, TiCl ４ Gas and H ２ Gas is supplied and turned into plasma, and a Ti film 16 is formed on the W oxide film 15a (FIG. 7B). Immediately after deposition, the Ti film 16 contains almost no oxygen and has a relatively high reducing power. However, because the substrate W is heated, the reducing power is further increased, making it more susceptible to oxidation. As a result, the Ti film 16 absorbs oxygen from the W oxide film 15a and becomes a Ti oxide film 16a, while the W oxide film 15a loses oxygen and is reduced, returning to the W layer 15 (FIG. 7C).

[0056] The Ti oxide film 16a provided to cover the surface of the W layer 15 effectively prevents re-oxidation of the W layer 15. The Ti oxide film 16a is removed in the COR and PHT processing modules 101 and 102 by the same method as that shown in the first embodiment. Note that, for example, if the oxidation of the Ti film 16 is insufficient and unoxidized Ti film 16 remains, O ２ (Oxygen) gas and O ３ After forming the Ti oxide film 16a using (ozone) gas, the Ti oxide film may be removed.

[0057] According to the oxide film removal method of this embodiment, the W oxide film 15a constituting the surface of the W layer 15 is reduced by the Ti film 16 formed on the W oxide film 15a to form the W layer 15. The Ti oxide film 16a, which is the result of oxidation of the Ti film 16, can then be removed by the Ti oxide film removal using the COR and PHT processing modules 101 and 102 shown in the first embodiment.

[0058] As described above, according to the oxide film removal method of the present disclosure, an oxide film provided on the surface of a metal-containing layer can be removed by using the Ti oxide film removal method of the first embodiment. Even if the metal-containing layer does not contain, for example, Ti as a constituent element, as shown in this embodiment, a Ti film can be formed on the oxide film on the surface, the oxide film of the metal-containing layer can be reduced to return it to the metal-containing layer, and then the Ti oxide film underlying the metal-containing layer can be removed by the Ti oxide film removal method shown in the first embodiment.

[0059] Therefore, the metal-containing layer is not limited to those containing Ti or W as a constituent element, and may be one containing at least one of Al (aluminum), copper (Cu), silver (Ag), Mo (molybdenum), etc. Also, although it is preferable to form a Ti film 16 having a relatively high reducing power on the surface of the W oxide film 15a, a Ti-containing film other than the Ti film 16 and containing an element other than oxygen (for example, nitrogen N) as a constituent element may be formed as long as it has a reducing power.

[0060] (Experiment 1) To confirm the effect of the oxide film removal method of the present disclosure, a process different from the oxide film removal method of the present disclosure and a process equivalent to the oxide film removal method of the first embodiment were each performed on the surface of a TiN layer on which a native oxide film had been formed. A TiN cap layer was then formed, and the content of oxygen and other elements was analyzed. The analysis used EDX (Energy Dispersive X-ray Spectroscopy) to measure the content of each element, such as oxygen and fluorine.

[0061] A. Experimental Conditions Three unpatterned, flat bare wafers were prepared, and a TiN film was uniformly formed on the surface of each bare wafer, followed by natural oxidation of the surface. Then, the surface of each wafer was subjected to Comparative Examples 1-1 and 1-2, which performed pretreatment different from the oxide film removal of the present disclosure, and Example 1, which performed treatment equivalent to the oxide film removal of the first embodiment. After that, the wafers were transported to a TiN film deposition module using a vacuum transfer module, where a TiN film was formed. In this way, a TiN+TiN layer with a Ti oxide film that had been subjected to different treatments was formed on the surface side of each wafer.

[0062] In the pretreatment of Comparative Example 1-1, a mixed gas was not supplied to the wafer, and N plasma was generated in the PHT treatment module 102 based on a predetermined recipe. ２ Gas, H ２ Gas, NH ３ The wafers were exposed to a gas supply atmosphere, and no heat treatment was performed on the substrates. In the pretreatment of Comparative Example 1-2, a mixed gas and an inert gas were supplied to the wafers in the COR treatment module 101 based on the recipe already described in the first embodiment, but treatment with plasma-converted gas as in Comparative Example 1-1 was not performed. In Example 1, a mixed gas was supplied to the wafers in the COR treatment module 101 as in Comparative Example 1-2, and then treatment with plasma-converted gas was performed in the PHT treatment module 102 as in Comparative Example 1-1. EDX was performed on each wafer provided with such a TiN+TiN layer.

[0063] B. Experimental Results Among the EDX graphs measured in Experiment 1, Figure 8 shows the change in atomic percentage (At%) of various elements versus depth on the wafer surface side for Example 1 as a representative example. In this graph, it can be seen that the intermediate depth region, where the proportion of N atoms and the proportion of Ti atoms account for the majority, is the TiN+TiN layer. As shown in this figure, not only in Example 1 but also in Comparative Examples 1-1 and 1-2, the proportions of Cl atoms and F atoms in the TiN+TiN layer were not significantly different, being almost zero.

[0064] FIG. 9 is a first graph for comparing the results of Experiment 1. Specifically, it compares the atomic composition percentage of oxygen extracted from the atomic composition percentage of various elements relative to the depth on the surface side of each wafer in Experiment 1. The proportion of oxygen atoms in the depth region corresponding to the TiN+TiN layer of each wafer was the smallest in Example 1, indicating a decrease in the oxygen content of the entire TiN stack. On the other hand, although the proportion of oxygen atoms in the stacked film of Comparative Example 1-1 was smaller than that of Comparative Example 1-2, a peak of increased oxygen atom content was observed at a position corresponding to the interface of the stacked film. This is thought to be due to the absence of COR treatment to generate and remove gaseous reaction products from the oxygen contained in the native oxide film of the underlying TiN film. In contrast, no peak was observed in the proportion of oxygen atoms in the TiN+TiN layer of Comparative Example 1-2 and Example 1, which were subjected to COR treatment. This suggests that gaseous reaction products were generated and removed from the oxygen contained in the native oxide film of the underlying TiN film.

[0065] 10 is a second graph for comparing the results of Experiment 1, which was obtained using SIMS (Secondary Ion Mass Spectrometry). Specifically, the atomic concentrations of O atoms and F atoms in the TiN+TiN layer in Experiment 1 [atoms / cm 3 ] is a bar graph comparing the O concentration of each TiN + TiN layer in Comparative Example 1-2 and Example 1, which were subjected to the COR treatment, was lower than the O concentration of the TiN + TiN layer in Comparative Example 1-1, which was not subjected to the COR treatment, confirming that the oxide film can be removed by the COR treatment. The F concentration of each TiN + TiN layer in Comparative Example 1-1 and Example 1, which were subjected to the treatment with the plasma gas, was lower than the F concentration in Comparative Example 1-2, which was not subjected to the plasma gas treatment, confirming that the fluorine can be reduced by the plasma gas treatment. Note that the F concentration in Example 1 is higher than that in Comparative Example 1-1, but this is because Comparative Example 1-1 was not subjected to the COR treatment using HF gas, which provides F atoms.

[0066] According to evaluation tests conducted other than Experiment 1, it has been found that factors that improve the effect of removing oxygen and fluorine by PHT treatment are the type and combination of supply gases in the PHT treatment and the plasma state of the supply gases. ２ NH3 rather than gas ３ Gas is preferred, more preferably NH ３ Gas and N ２ It has been confirmed that the gas supplied at the same time is converted into plasma.

[0067] For COR treatment, NH ３ It has been confirmed that the oxygen concentration is relatively high when no gas is included. This is thought to be due to the absence of deposits 11d. It has also been confirmed that the oxygen concentration tends to increase when the wafer temperature during the COR process is increased to, for example, 80°C or when the pressure inside the process chamber is set to a relatively low pressure, for example, 13.3 Pa (0.1 Torr). Furthermore, as shown in Experiment 2 below, it has been found that the oxide film can be effectively removed by using a relatively long COR process time, but in this case, the fluorine concentration does not change significantly. As described above, in the Ti oxide film removal process of the present disclosure, the conditions can be appropriately adjusted as described above to suit the desired film quality, etc.

[0068] (Experiment 2) The effect of oxide film removal on the COR processing time in the oxide film removal of the present disclosure was confirmed.

[0069] A. Experimental Conditions As in Experiment 1, three bare wafers with uniformly formed TiN films were prepared, and the surfaces of the wafers were subjected to the COR and PHT processes similar to those in Example 1, after which a Ru film was formed. The processing times for each COR process were 300 seconds, 120 seconds, and 60 seconds.

[0070] B. Experimental Results Figure 11 is a graph comparing the atomic composition percentage of oxygen extracted from the atomic composition percentage of various elements versus depth on the wafer surface side in Experiment 2. According to this graph, after 60 seconds of COR treatment, a significant peak of oxygen element was observed in the boundary region between the Ru film and the TiN film, suggesting the presence of a relatively thick oxide film. Furthermore, after 120 seconds of COR treatment, a lower peak of oxygen element was observed in the boundary region than after 60 seconds of COR treatment, but it was confirmed that the oxide film was more effectively reduced than after 60 seconds of COR treatment. After 300 seconds of COR treatment, the oxygen percentage in the boundary region was nearly identical to the oxygen percentage in the Ru film, suggesting that the oxide film was sufficiently removed. As described above, the results of Experiment 2 confirmed that in a stacked structure of a TiN film and a Ru film, the oxide film removal method disclosed herein can remove Ti oxide film, and that the oxide film removal effect can be improved by extending the COR treatment time.

[0071] It should be noted that the embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects, 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.

[0072] W substrate 11a Ti oxide film 11b reaction product 11d deposit 16a Ti oxide film

Claims

1. A method for removing a titanium oxide film on a surface of a substrate, comprising the steps of: supplying a mixed gas containing hydrogen fluoride gas and ammonia gas to the surface of the titanium oxide film, causing a chemical reaction between the titanium oxide film and the mixed gas, generating a gaseous reaction product from the titanium oxide film, and removing the gaseous reaction product from the surface of the substrate; and heating the substrate to remove any deposits that have adhered to the substrate when the reaction product was generated.

2. The method according to claim 1, wherein the deposit adheres to the surface of the metal-containing layer underlying the titanium oxide film and inhibits the metal in the metal-containing layer from being oxidized by moisture, which is a by-product of the chemical reaction.

3. The method of claim 2, wherein the metal-containing layer is a titanium nitride layer or a tungsten layer.

4. The method of claim 1, wherein the reaction product is titanium fluoride and the deposit comprises ammonium fluoride and hydrogen fluoride.

5. The method of claim 1, wherein the step of removing the reaction products from the surface of the substrate is carried out while the temperature of the substrate is in the range of 20°C to 100°C.

6. The method of claim 1, wherein the step of removing the reaction product from the surface of the substrate is carried out under an atmosphere with a pressure in the range of 13.3 Pa to 133 Pa.

7. The method according to claim 1, wherein the step of removing the deposits comprises heating the substrate to a temperature within the range of 100°C to 500°C.

8. The method according to claim 1, wherein the step of removing the deposits is carried out in an atmosphere supplied with a plasma-converted gas.

9. The method according to claim 8, wherein the gas plasma is at least one gas selected from the group consisting of hydrogen, ammonia, and nitrogen.

10. The method according to claim 1, further comprising the step of forming a metal film on the substrate after performing the step of removing the deposits.

11. The method of claim 10, wherein the metal film is a ruthenium film.

12. A method for reducing an oxide film on a surface of a substrate, comprising: forming a titanium-containing film on the oxide film provided on the surface of a metal-containing layer of the substrate; heating the substrate to oxidize the titanium-containing film to form the titanium oxide film, thereby reducing the oxide film to form the metal-containing layer; and removing the titanium oxide film using the method of claim 1.

13. The method according to claim 12, wherein the deposit adheres to the surface of the metal-containing film and inhibits oxidation of the metal in the metal-containing layer by moisture, which is a by-product of the chemical reaction.

14. The method of claim 12, wherein the titanium-containing film is a titanium film.

15. A substrate processing apparatus comprising: a first processing module having a gas supply mechanism configured to supply a mixed gas containing hydrogen fluoride gas and ammonia gas to a substrate, for removing a titanium oxide film on a surface of the substrate; a second processing module configured to heat the substrate; and a control unit, wherein the control unit is configured to output control signals to execute the steps of: in the first processing module, supplying the mixed gas to the surface of the titanium oxide film, causing a chemical reaction between the titanium oxide film and the mixed gas, generating a gaseous reaction product from the titanium oxide film and removing it from the surface of the substrate; and in the second processing module, heating the substrate and removing any deposits that have adhered to the substrate when the reaction product is generated.

16. The substrate processing apparatus according to claim 15, further comprising a third processing module having a heating mechanism for heating the substrate and configured to deposit a titanium-containing film having reducing power on an oxide film provided on a surface of a metal-containing layer of the substrate, wherein the control unit outputs the control signal to execute, in the third processing module before the removal step in the first processing module, a step of depositing the titanium-containing film on the oxide film and a step of heating the substrate to oxidize and reduce the titanium-containing film and the oxide film to form the titanium oxide film and the metal-containing film.

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