Substrate processing device and substrate processing method

Abstract

The substrate processing device includes an ultraviolet irradiation unit, a holding unit, and a liquid supply unit. The ultraviolet irradiation unit irradiates ultraviolet rays to the surface of a substrate having a tungsten film and a titanium nitride film formed on the surface, thereby forming an oxide film on the surface of the substrate. The holding unit holds the substrate. The liquid supply unit supplies a chemical liquid to the surface of the substrate held by the holding unit, removes the oxide film by the chemical liquid, and etches the titanium nitride film selectively with respect to the tungsten film by the chemical liquid.

Description

Technical Field

[0001] The present disclosure relates to a substrate processing device and a substrate processing method. Background Art

[0002] The etching method described in Patent Document 1 includes a step of performing wet etching after forming a titanium nitride film on a substrate provided with a component including tungsten. In the wet etching step, the ratio of the etching rate of the titanium nitride film to the etching rate of tungsten is 5 or more.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2003-234307 Summary of the invention

[0006] Problem that the invention aims to solve

[0007] One embodiment of the present disclosure provides a technology for increasing the ratio of the etching rate of a titanium nitride film to the etching rate of a tungsten film.

[0008] Solutions for solving problems

[0009] A substrate processing device according to one embodiment of the present disclosure includes an ultraviolet irradiation unit, a holding unit, and a liquid supply unit. The ultraviolet irradiation unit irradiates ultraviolet light to the surface of a substrate having a tungsten film and a titanium nitride film formed on the surface, thereby forming an oxide film on the surface of the substrate. The holding unit holds the substrate. The liquid supply unit supplies a chemical liquid to the surface of the substrate held by the holding unit, removes the oxide film by the chemical liquid, and etches the titanium nitride film selectively with respect to the tungsten film by the chemical liquid.

[0010] Effects of the Invention

[0011] According to one embodiment of the present disclosure, the ratio of the etching rate of the titanium nitride film to the etching rate of the tungsten film can be increased. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a cross-sectional view showing a substrate processing apparatus according to one embodiment.

[0013] Figure 2 FIG. 1 is a diagram showing an example of a tungsten film and a tungsten oxide film formed on the surface of the tungsten film.

[0014] Figure 3 This is a diagram showing an example of the relationship between the presence or absence of a tungsten oxide film and the etching amount of the tungsten film.

[0015] Figure 4This is a plan view showing an example of ultraviolet scanning.

[0016] Figure 5 It is a top view showing another example of ultraviolet scanning.

[0017] Figure 6 1 is a flowchart showing a substrate processing method according to one embodiment.

[0018] Figure 7 TABLE 1 is a graph showing the results of Table 1. DETAILED DESCRIPTION

[0019] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. In addition, in some cases, the same reference numerals are given to the same or corresponding structures in each drawing and the description thereof is omitted. Figure 1 , Figure 4 as well as Figure 5 , the Z-axis direction is the vertical direction.

[0020] Reference Figure 1 A substrate processing apparatus 1 according to an embodiment is described. The substrate processing apparatus 1 supplies a chemical solution to the surface Wa of the substrate W to process the substrate W. A tungsten film and a titanium nitride film are formed on the surface Wa of the substrate W, and both are exposed. The tungsten film and the titanium nitride film are present in different regions of the surface Wa of the substrate W. The chemical solution selectively etches the titanium nitride film relative to the tungsten film. In this embodiment, the substrate processing apparatus 1 is a single-sheet type substrate processing apparatus that processes substrates one by one.

[0021] In addition, the substrate processing apparatus 1 may also be a batch type substrate processing apparatus that processes a plurality of substrates W simultaneously. The batch type substrate processing apparatus 1 has a processing tank, and immerses a plurality of substrates W in a chemical solution stored in the processing tank at the same time. In this case, each of the plurality of substrates W is immersed in the chemical solution in a vertically upright state, for example.

[0022] like Figure 1 As shown, a single-sheet substrate processing device 1, for example, comprises: a processing container 10; a holding portion 20, which holds the substrate W horizontally; a rotating portion 21, which rotates the holding portion 20 around a vertical rotating axis 22; a liquid supply portion 30, which supplies a processing liquid L such as a chemical solution to the upper surface of the substrate W held by the holding portion 20; and a cup 40, which is used to recover the processing liquid L supplied to the substrate W.

[0023] The holding portion 20 is accommodated in the processing container 10. The processing container 10 has a door 11 and a gate valve 12 for opening and closing the door 11. The substrate W is carried into the processing container 10 through the door 11 by the conveying device 2, is processed by the processing liquid L in the processing container 10, and then is carried out to the outside of the processing container 10 by the conveying device 2 through the door 11.

[0024] The holding unit 20 holds the substrate W carried into the processing container 10 in a horizontal position. The holding unit 20 holds the substrate W in a horizontal position so that the surface Wa of the substrate W faces upward and the center of the substrate W coincides with the rotation center line of the rotation shaft 22. Figure 1 The mechanical chuck is shown in the figure, but it may be a vacuum chuck or an electrostatic chuck, etc. The holding portion 20 may be a rotatable spin chuck.

[0025] The rotating part 21 includes, for example, a vertical rotating shaft 22 and a rotating motor 23 that rotates the rotating shaft 22. The rotational driving force of the rotating motor 23 may be transmitted to the rotating shaft 22 via a rotation transmission mechanism such as a timing belt or gears. When the rotating shaft 22 is rotated, the holding part 20 is also rotated.

[0026] The liquid supply unit 30 ejects the processing liquid L onto the surface Wa of the substrate W held by the holding unit 20. The liquid supply unit 30 includes, for example, a nozzle 31 that ejects the processing liquid L toward the surface Wa of the substrate W, a supplier 32 that supplies the processing liquid L to the nozzle 31, and a nozzle moving unit 33 that moves the nozzle 31.

[0027] The nozzle 31 includes a discharge port, and the discharge port discharges the processing liquid L toward the substrate W held by the holding portion 20. The nozzle 31 is disposed above the substrate W, for example, with the discharge port facing downward, and supplies the processing liquid L toward the center of the substrate W. The processing liquid L is supplied to the center of the rotating substrate W, and is wetted and spread on the entire upper surface of the substrate W by centrifugal force to form a liquid film.

[0028] The processing liquid L includes, for example, a chemical liquid, a rinsing liquid, and a drying liquid. One nozzle 31 may eject multiple processing liquids L in sequence, or multiple nozzles 31 may eject different processing liquids L in sequence. Multiple chemical liquids may be supplied to the substrate W in sequence, or the rinsing liquid may be supplied to the substrate W between them.

[0029] The chemical solution includes an etching solution that selectively etches the titanium nitride film relative to the tungsten film. The etching solution is, for example, a mixed solution containing sulfuric acid and water. Specifically, the mixed solution is, for example, SPM (aqueous solution containing sulfuric acid and hydrogen peroxide) or dilute sulfuric acid.

[0030] Unlike dilute sulfuric acid, SPM has a high etching rate for titanium nitride film even at a spraying temperature below 120°C. For example, the etching rate of titanium nitride film by SPM at a spraying temperature of 45°C is about the same as the etching rate of titanium nitride film by dilute sulfuric acid at a spraying temperature of 160°C.

[0031] As described above, SPM, unlike dilute sulfuric acid, has a high etching rate for titanium nitride film even at a spraying temperature of 120°C or less. Therefore, the mixed solution preferably contains hydrogen peroxide. The mixed solution may contain ozone instead of hydrogen peroxide, or may contain ozone in addition to hydrogen peroxide. In addition, the spraying temperature of SPM may exceed 120°C.

[0032] SPM is obtained by mixing sulfuric acid and hydrogen peroxide water, for example. The mixing ratio of sulfuric acid and hydrogen peroxide water (sulfuric acid: hydrogen peroxide water) is, for example, 2:1 to 20:1 by volume. The hydrogen peroxide water contains 10% to 40% by mass of hydrogen peroxide.

[0033] The nozzle 31 may also eject the SPM mixed with water vapor. The water vapor efficiently increases the ejection temperature of the SPM to increase the etching rate of the titanium nitride film. For example, although not shown, the nozzle 31 has a first ejection port for ejecting the SPM, a second ejection port for ejecting the water vapor, and a third ejection port for ejecting a mixed fluid of the SPM ejected from the first ejection port and the water vapor ejected from the second ejection port.

[0034] The nozzle 31 may include a temperature regulator (not shown) for regulating the discharge temperature of the processing liquid L. The temperature regulator is, for example, a heater.

[0035] The rinse liquid is, for example, DIW (deionized water). The rinse liquid is used to remove the chemical liquid. The rinse liquid is supplied to the center of the rotating substrate W, and is spread over the entire upper surface of the substrate W by centrifugal force to rinse the chemical liquid remaining on the upper surface of the substrate W. As a result, a liquid film of the rinse liquid is formed on the upper surface of the substrate W. The rinse liquid may be supplied to the substrate W after one chemical liquid is supplied to the substrate W and before another chemical liquid is supplied to the substrate W.

[0036] The drying liquid is, for example, an organic solvent such as IPA (isopropyl alcohol). The organic solvent has a surface tension lower than that of the rinsing liquid. Therefore, the collapse of the concave-convex pattern caused by the surface tension can be suppressed. The drying liquid is supplied to the center of the rotating substrate W, and is wetted and diffused on the entire upper surface of the substrate W by the centrifugal force to replace the rinsing liquid remaining on the upper surface of the substrate W. As a result, a liquid film of the drying liquid is formed on the upper surface of the substrate W. In addition, the drying liquid may not be used.

[0037] The nozzle 31 is stopped just above the center of the substrate W during the supply of the processing liquid L, but may be moved in the radial direction of the substrate W. The nozzle 31 may be a rod-shaped nozzle that is long in the radial direction of the substrate W. The rod-shaped nozzle has a length of, for example, about the radius of the substrate W, and supplies the processing liquid L from the center of the substrate W to the periphery at the same time.

[0038] The supplier 32 includes a supply line 32a connected to the nozzle 31. Although not shown in the figure, a flow meter for measuring the flow rate of the processing liquid L, a flow controller for controlling the flow rate of the processing liquid L, an on-off valve for opening and closing the flow path of the processing liquid L, etc. are provided in the middle of the supply line 32a. A temperature regulator for regulating the temperature of the processing liquid L may also be provided in the middle of the supply line 32a. The temperature regulator is, for example, a heater.

[0039] The nozzle moving unit 33 moves the nozzle 31 in the radial direction of the substrate W, for example. The nozzle moving unit 33 moves the nozzle 31 between a supply position for supplying the processing liquid L to the substrate W and a standby position for standing by radially outside the substrate W. The nozzle moving unit 33 may also move the nozzle 31 in the vertical direction.

[0040] The cup 40 surrounds the periphery of the substrate W held by the holding portion 20, and receives the processing liquid L scattered from the periphery of the substrate W. In the present embodiment, the cup 40 does not rotate together with the rotating shaft 22, but may rotate together with the rotating shaft 22. A drain pipe 41 for discharging the liquid accumulated in the cup 40 and an exhaust pipe 42 for discharging the gas accumulated in the cup 40 are provided on the bottom wall of the cup 40.

[0041] The substrate processing apparatus 1 includes an ultraviolet irradiation unit 50. The ultraviolet irradiation unit 50 irradiates ultraviolet light to the surface Wa of the substrate W before etching the titanium nitride film selectively with respect to the tungsten film, thereby forming an oxide film on the surface Wa of the substrate W. The internal space of the processing container 10 contains oxygen gas, and the ultraviolet light generates ozone gas from the oxygen gas. The ozone gas forms an oxide film on the surface Wa of the substrate W.

[0042] For example, Figure 2 As shown, the ultraviolet irradiation unit 50 irradiates ultraviolet rays onto the surface of the tungsten film W1 to form a tungsten oxide film W2 on the surface of the tungsten film W1. Although not shown in the figure, the ultraviolet irradiation unit 50 also irradiates ultraviolet rays onto the surface of the titanium nitride film to form a titanium nitride oxide film on the surface of the titanium nitride film. By forming an oxide film, the ratio of the etching rate of the titanium nitride film to the etching rate of the tungsten film can be increased, and the details will be described later. Hereinafter, this ratio will also be referred to as the "selectivity ratio". The selectivity ratio is, for example, greater than 7, preferably greater than 10, and more preferably greater than 20. The higher the selectivity ratio, the more preferred it is, but it can also be less than 40.

[0043] like Figure 3As shown in FIG. 1 , it takes time to remove the tungsten oxide film W2 by the chemical solution, thereby delaying the start of etching of the tungsten film W1. The titanium nitride oxide film is easier to be removed by the chemical solution than the tungsten oxide film W2, and the start of etching of the titanium nitride film is hardly delayed. As a result, the ratio of the etching speed of the titanium nitride film to the etching speed of the tungsten film can be increased.

[0044] In addition, the tungsten film has a higher resistance to SPM or dilute sulfuric acid than the titanium nitride film, but it is not completely unetched. As a result, the tungsten film is etched while being oxidized by SPM or dilute sulfuric acid. It is believed that the irradiation of ultraviolet rays delays the start of etching of the tungsten film W1 by forming a dense tungsten oxide film W2 compared to the supply of SPM or dilute sulfuric acid.

[0045] When the surface Wa of the substrate W is not irradiated with ultraviolet rays but the surface Wa is etched by SPM, the selectivity is about 4 to 6, which will be described in detail in the embodiment column. On the other hand, when the surface Wa of the substrate W is irradiated with ultraviolet rays and then etched by SPM, the selectivity is 7 or more.

[0046] The irradiation of ultraviolet rays is also effective when etching the surface Wa of the substrate W by dilute sulfuric acid. Dilute sulfuric acid has an oxidizing power weaker than that of SPM, so it can slow down the etching speed of the tungsten oxide film and improve the selectivity compared to SPM. In addition, as described above, SPM has the advantage of being able to lower the ejection temperature compared to dilute sulfuric acid.

[0047] In addition, the substrate W may have a tantalum nitride film or the like instead of the titanium nitride film on the surface Wa of the substrate W. In other words, the substrate W only needs to have a metal nitride film on the surface Wa of the substrate W. As long as the ultraviolet irradiation unit 50 oxidizes the surface Wa of the substrate W before the chemical solution selectively etches the metal nitride film relative to the tungsten film, the ratio of the etching rate of the metal nitride film to the etching rate of the tungsten film can be increased.

[0048] like Figure 1 As shown, the ultraviolet irradiation unit 50 includes, for example, an ultraviolet light source 51 provided inside the processing container 10. A mercury lamp, an excimer lamp, or an ultraviolet LED is used as the light source 51. The wavelength of the ultraviolet light is, for example, 100 nm to 230 nm.

[0049] The ultraviolet irradiation unit 50 includes a moving unit 52 that moves the light source 51 and the holding unit 20 relative to each other. The moving unit 52 moves the ultraviolet irradiation area on the surface Wa of the substrate W held by the holding unit 20 by moving the light source 51 and the holding unit 20 relative to each other, thereby irradiating the entire surface Wa of the substrate W with ultraviolet rays. The cumulative irradiation amount of ultraviolet rays is, for example, 30 mJ / cm 2 ~950mJ / cm 2 .

[0050] like Figure 4 As shown in FIG. 1 , for example, the light source 51 is in the shape of a rod and has a length equal to or greater than the diameter of the substrate W. The moving portion 52 moves the light source 51 or the holding portion 20 (in Figure 4 The light source 51 in the center is translated along a direction perpendicular to the longitudinal direction of the light source 51 and in the radial direction of the substrate W to irradiate the entire surface Wa of the substrate W with ultraviolet rays.

[0051] like Figure 5 As shown, the light source 51 may also be in the shape of a rod and have a length greater than the radius of the substrate W. The moving part 52 moves the light source 51 or the holding part 20 (in Figure 5 The holding portion 20 (in the figure) is rotationally moved in the circumferential direction of the substrate W to irradiate the entire surface Wa of the substrate W with ultraviolet rays. The rotating portion 21 is used as the moving portion 52 that rotationally moves the holding portion 20.

[0052] In this embodiment, the light source 51 is as follows Figure 1 Although the light source 51 is provided inside the processing container 10 as shown in the figure, it may be provided outside the processing container 10, for example, it may be provided in the transport path of the transport device 2 for transporting the substrate W. In this case, the light source 51 irradiates the surface Wa of the substrate W with ultraviolet light during the transport of the substrate W. Therefore, in this case, the transport device 2 plays the role of the moving part 52.

[0053] In addition, the ultraviolet irradiation section 50 may be provided separately from the processing container 10 and beside the transport path of the transport device 2 for transporting the substrate W. In this case, the substrate W is transported into the ultraviolet irradiation section 50 by the transport device 2, and then, after being processed by the ultraviolet irradiation section 50, it is transported out of the ultraviolet irradiation section 50 and transported to the processing container 10. Thereafter, etching is performed inside the processing container 10.

[0054] The substrate processing apparatus 1 includes a control unit 90. The control unit 90 is, for example, a computer, and includes a CPU (Central Processing Unit) 91 and a storage medium 92 such as a memory. The storage medium 92 stores a program for controlling various processes performed in the substrate processing apparatus 1. The control unit 90 controls the operation of the substrate processing apparatus 1 by causing the CPU 91 to execute the program stored in the storage medium 92.

[0055] Next, refer to Figure 6 An example of processing performed by the substrate processing apparatus 1 will be described. Figure 6 Each of the steps S101 to S107 shown is implemented under the control of the control unit 90 .

[0056] First, the transport device 2 carries the substrate W into the processing container 10 (step S101 ). After placing the substrate W on the holder 20 , the transport device 2 withdraws from the processing container 10 . The holder 20 holds the substrate W.

[0057] Next, the ultraviolet irradiation unit 50 irradiates ultraviolet rays to the surface Wa of the substrate W to form an oxide film on the surface Wa of the substrate W (step S102). The ultraviolet irradiation unit 50 forms an oxide film on the entire surface Wa of the substrate W. Thereafter, the rotating unit 21 rotates the substrate W together with the holding unit 20. In addition, as described above, the rotating unit 21 may be used as the moving unit 52, or the rotating unit 21 may rotate the substrate W together with the holding unit 20 from before step S102.

[0058] Next, the nozzle 31 supplies the chemical solution to the center of the rotating substrate W (step S103). The chemical solution wets and spreads on the entire upper surface of the substrate W by centrifugal force to form a liquid film. The chemical solution removes the oxide film formed in the above step S102 and selectively etches the titanium nitride film relative to the tungsten film. After the above step S103, the tungsten film W1 is exposed on the surface Wa of the substrate W again.

[0059] Next, the nozzle 31 supplies the rinse liquid to the center of the rotating substrate W (step S104). The rinse liquid wets and spreads on the entire upper surface of the substrate W by centrifugal force to rinse the chemical solution remaining on the upper surface of the substrate W. As a result, a rinse liquid film is formed on the upper surface of the substrate W.

[0060] Next, the nozzle 31 supplies drying liquid to the center of the rotating substrate W (step S105). The drying liquid wets and spreads over the entire upper surface of the substrate W by centrifugal force, thereby washing away the residual washing liquid on the upper surface of the substrate W. As a result, a liquid film of the drying liquid is formed on the upper surface of the substrate W.

[0061] Next, the rotating unit 21 rotates the substrate W to shake off the drying liquid remaining on the upper surface of the substrate W, thereby drying the substrate W (step S106). After drying the substrate W, the rotating unit 21 stops the rotation of the substrate W. In addition, step S105 (supply of drying liquid) may be omitted. In this case, in step S106 (drying of substrate), the rinsing liquid remaining on the upper surface of the substrate W is shaken off.

[0062] Finally, the holding unit 20 releases the holding of the substrate W, and then the transport device 2 receives the substrate W from the holding unit 20 and carries the received substrate W out of the processing container 10 (step S107 ). Thereafter, the current processing is completed.

[0063] In addition, the light source 51 of the ultraviolet irradiation unit 50 may be provided outside the processing container 10 as described above, and the control unit 90 may perform step S102 (forming an oxide film) before step S101 (carrying in a substrate).

[0064] [Example]

[0065] Next, refer to Table 1 and Figure 7 To illustrate the experimental data.

[0066] [Table 1]

[0067]

[0068] In Example 1, using Figure 1 The substrate processing apparatus 1 shown in Table 1 was subjected to the processing conditions shown in Table 1. Figure 6 Steps S101 to S107 are shown. In step S103, SPM is supplied to the surface Wa of the substrate W. Regarding SPM, the mixing ratio of sulfuric acid and hydrogen peroxide water (sulfuric acid: hydrogen peroxide water) is 6:1 by volume. Hydrogen peroxide water containing 31% by mass of hydrogen peroxide is used. The ejection temperature of SPM is 104°C. In Example 1, the selection ratio is 12.1.

[0069] In Comparative Example 1, as shown in Table 1, the substrate W was processed under the same conditions as in Example 1 except that step S102 (formation of oxide film) was not performed and the supply time of SPM was shortened so that the etching amount of titanium nitride film was similar. In Comparative Example 1, the selectivity was 4.7.

[0070] As shown in Table 1 and Figure 7 It is apparent that by performing step S102 (forming oxide film) to form a tungsten oxide film on the surface of the tungsten film, the ratio of the etching rate of the titanium nitride film to the etching rate of the tungsten film can be increased, thereby improving the selectivity.

[0071] The above describes the embodiments of the substrate processing device and the substrate processing method involved in the present disclosure, but the present disclosure is not limited to the above embodiments. Various changes, corrections, substitutions, additions, deletions and combinations can be made within the scope of the claims. These also belong to the technical scope of the present disclosure.

[0072] This application claims the priority of Japanese Patent Application No. 2021-117619 filed with the Japan Patent Office on July 16, 2021, and the entire contents of Japanese Patent Application No. 2021-117619 are incorporated herein by reference.

[0073] Description of Reference Numerals

[0074] 1: substrate processing device; 20: holding part; 30: liquid supply part; 50: ultraviolet irradiation part; W: substrate; Wa: surface.

Claims

1. A substrate processing device, comprising: an ultraviolet irradiation unit for irradiating ultraviolet rays to the surface of the substrate on which the tungsten film and the titanium nitride film are formed, so as to form a tungsten oxide film and a titanium oxynitride film on the surface of the substrate; a holding portion that holds the substrate; as well as A liquid supply unit supplies a chemical solution to the surface of the substrate held by the holding unit and having the tungsten oxide film and the titanium oxynitride film formed on the surface, removes the tungsten oxide film and the titanium oxynitride film by the chemical solution, and selectively etches the titanium nitride film relative to the tungsten film by the chemical solution, wherein the titanium oxynitride film is more easily removed by the chemical solution than the tungsten oxide film.

2. The substrate processing apparatus according to claim 1, wherein: The chemical solution is a mixed solution containing sulfuric acid and water.

3. The substrate processing apparatus according to claim 2, wherein: The mixed liquid contains hydrogen peroxide or ozone.

4. The substrate processing apparatus according to claim 3, wherein: The mixed liquid is SPM, and the SPM is an aqueous solution containing sulfuric acid and hydrogen peroxide.

5. The substrate processing apparatus according to claim 4, wherein: The liquid supply unit includes a nozzle for spraying the SPM mixed with water vapor.

6. The substrate processing apparatus according to any one of claims 1 to 5, wherein: The substrate processing apparatus includes a processing container in which the holding portion is housed. The ultraviolet irradiation unit includes: a light source of ultraviolet rays disposed inside the processing container; and a moving unit that moves the light source and the holding unit relative to each other.

7. The substrate processing apparatus according to claim 6, wherein: The light source of the ultraviolet rays is in the shape of a rod and has a length greater than the diameter of the substrate. The moving portion translates the light source or the holding portion in a direction that is orthogonal to the longitudinal direction of the light source and is a radial direction of the substrate.

8. The substrate processing apparatus according to claim 6, wherein: The light source of the ultraviolet rays is in the shape of a rod and has a length greater than the radius of the substrate. The moving portion rotationally moves the light source or the holding portion in the circumferential direction of the substrate.

9. A substrate processing method, comprising the following steps: irradiating the surface of the substrate having the tungsten film and the titanium nitride film formed on the surface with ultraviolet rays to form a tungsten oxide film and a titanium oxynitride film on the surface of the substrate; holding the substrate by a holding portion; and A chemical solution is supplied to the surface of the substrate held by the holding portion and having the tungsten oxide film and the titanium oxynitride film formed on the surface, the tungsten oxide film and the titanium oxynitride film are removed by the chemical solution, and the titanium nitride film is selectively etched relative to the tungsten film by the chemical solution, wherein the titanium oxynitride film is more easily removed by the chemical solution than the tungsten oxide film.

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