Substrate processing method and substrate processing apparatus

Abstract

The substrate processing method comprises the following steps: preparing a substrate, wherein a titanium nitride film and a zirconium oxide film are exposed on the surface of the substrate; and selectively etching the zirconium oxide film among the titanium nitride film and the zirconium oxide film by supplying an etching solution containing hydrogen fluoride and an organic solvent to the surface of the substrate.

Description

Technical Field

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

[0002] The substrate processing method described in Patent Document 1 includes etching zirconium oxide using a processing solution containing sulfuric acid. Zirconium oxide is a material of a gate insulating film and is a high dielectric constant material. The processing solution containing sulfuric acid is preheated to a temperature in the range of 150°C to 180°C.

[0003] The substrate processing method described in Patent Document 2 includes: using a mixture of dilute hydrofluoric acid (DHF) and isopropyl alcohol (IPA) to selectively etch the lower layer between the lower layer and the upper layer, wherein the dilute hydrofluoric acid is obtained by diluting hydrofluoric acid with water. The lower layer is glass containing boron or phosphorus. The upper layer is a silicon oxide film.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2003-273066

[0007] Patent Document 2: Japanese Patent Application Publication No. 2020-140984 Summary of the invention

[0008] Problem that the invention aims to solve

[0009] One embodiment of the present disclosure provides a technique for selectively etching a zirconium oxide film between a titanium nitride film and a zirconium oxide film.

[0010] Solutions for solving problems

[0011] A substrate processing method according to one embodiment of the present disclosure includes: preparing a substrate having a titanium nitride film and a zirconium oxide film exposed on the surface of the substrate; and selectively etching the zirconium oxide film between the titanium nitride film and the zirconium oxide film by supplying an etching solution containing hydrogen fluoride and an organic solvent to the surface of the substrate.

[0012] Effects of the Invention

[0013] According to one embodiment of the present disclosure, the zirconium oxide film can be selectively etched between the titanium nitride film and the zirconium oxide film. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a cross-sectional view showing a substrate processing apparatus according to one embodiment.

[0015] Figure 2 : is a cross-sectional view showing an example of the prepared substrate.

[0016] Figure 3 1 is a flowchart showing a substrate processing method according to one embodiment.

[0017] Figure 4 This is a diagram showing an example of the relationship between the mixing ratio of the etching solution and the etching rate of the zirconium oxide film.

[0018] Figure 5 This is a diagram showing an example of the relationship between the film type (TiN, TiSiN, SiN) and the film etching rate. DETAILED DESCRIPTION

[0019] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. In addition, the same reference numerals are given to the same or corresponding structures in each of the drawings, and the description thereof may be omitted. Figure 1 In the diagram, the X-axis direction, the Y-axis direction, and the Z-axis direction are perpendicular to each other. The X-axis direction and the Y-axis direction are horizontal directions, and the Z-axis direction is a vertical direction.

[0020] Reference Figure 1 and Figure 2 A substrate processing apparatus 1 according to an embodiment will be described. The substrate processing apparatus 1 processes the surface Wa of the substrate W by supplying a processing liquid to the surface Wa of the substrate W. The substrate processing apparatus 1 in this embodiment is a single-wafer type that processes substrates W one by one, but may also be a batch type that processes a plurality of substrates W at once.

[0021] The single-wafer type substrate processing apparatus 1 rotates the substrate W while holding the substrate W horizontally with the surface Wa of the substrate W facing upward, and supplies a processing liquid to the surface Wa of the substrate W. The single-wafer type substrate processing apparatus 1 includes, for example, a processing container 10, a substrate holding unit 20, a substrate rotating unit 25, a supply unit 31, a nozzle 41, a moving unit 51, a recovery unit 60, and a control unit 90.

[0022] The processing container 10 accommodates a substrate holding portion 20 and the like. A gate 12 and a gate valve 13 for opening and closing the gate 12 are provided on the side wall of the processing container 10. A substrate W is carried into the processing container 10 through the gate 12 by a transport device (not shown). Then, the substrate W is processed by a processing liquid in the processing container 10. Thereafter, the substrate W is carried out of the processing container 10 through the gate 12 by the transport device.

[0023] The substrate holding portion 20 is disposed inside the processing container 10 and is used to horizontally hold the substrate W. The substrate holding portion 20 has, for example, a claw portion 21 for holding the outer peripheral portion of the substrate W. A plurality of claw portions 21 are provided at equal intervals in the circumferential direction of the substrate W. In addition, although not shown in the figure, the substrate holding portion 20 may also perform vacuum adsorption on the lower surface of the substrate W.

[0024] The substrate rotating part 25 rotates the substrate holding part 20 to rotate the substrate W together with the substrate holding part 20. The substrate holding part 20 holds the substrate W so that the rotation center line of the substrate W coincides with the center of the surface Wa of the substrate W.

[0025] The supply unit 31 supplies the processing liquid to the surface Wa of the substrate W via the nozzle 41. The supply unit 31 includes, for example, a common line 31a connected to the nozzle 41, a plurality of individual lines 31b branching from the common line 31a, and a device 31c provided for each individual line 31b. The device 31c includes, for example, an on-off valve, a flow meter, and a flow controller. The nozzle 41 ejects a plurality of processing liquids in sequence, but the nozzle 41 may be provided for each type of processing liquid, and the number of the nozzles 41 may be plural.

[0026] The treatment liquid is, for example, HF (hydrogen fluoride), IPA (isopropyl alcohol), or DIW (deionized water). HF is supplied in the form of an aqueous solution. An HF aqueous solution is generally referred to as hydrofluoric acid. The HF concentration in the HF aqueous solution is, for example, 40 mass % to 65 mass %. The nozzle 41 may also spray a mixture of a plurality of treatment liquids, for example, a mixture of an HF aqueous solution and IPA. The supply unit 31 may also have a mixing device (not shown) for mixing the HF aqueous solution with the IPA.

[0027] The moving part 51 moves the nozzle 41 in the horizontal direction and the vertical direction. The moving part 51 includes, for example, an arm 51a and a rotating mechanism (not shown). The rotating mechanism moves the nozzle 41 in the horizontal direction by rotating the arm 51a. In addition, the rotating mechanism moves the nozzle 41 in the vertical direction by raising and lowering the arm 51a. In addition, the moving part 51 may also include a guide rail and a direct-acting mechanism instead of the arm 51a and the rotating mechanism. The direct-acting mechanism moves the nozzle 41 in the horizontal direction and the vertical direction along the guide rail.

[0028] The recovery part 60 recovers the processing liquid supplied to the substrate W. The recovery part 60 has, for example, a cup body 61. The cup body 61 surrounds the outer periphery of the substrate W held by the substrate holding part 20, and is used to receive the processing liquid scattered from the outer periphery of the substrate W. The cup body 61 does not rotate together with the substrate holding part 20 in the present embodiment, but may rotate together with the substrate holding part 20. A drain pipe 62 and an exhaust pipe 63 are provided at the bottom of the cup body 61. The drain pipe 62 discharges the liquid stored in the interior of the cup body 61. The exhaust pipe 63 discharges the gas stored in the interior of the cup body 61.

[0029] The control unit 90 is, for example, a computer, and includes a computing unit 91 such as a CPU (Central Processing Unit) and a storage unit 92 such as a memory. The storage unit 92 stores programs for controlling various processes executed in the substrate processing apparatus 1. The control unit 90 controls the operation of the substrate processing apparatus 1 by causing the computing unit 91 to execute the programs stored in the storage unit 92.

[0030] As described above, the substrate processing apparatus 1 may also be a batch type that processes a plurality of substrates W in a unified manner. Although not shown in the figure, the batch type substrate processing apparatus 1 holds a plurality of substrates W in a vertically upright manner and immerses the plurality of substrates W in a processing liquid stored in a processing tank, thereby processing the plurality of substrates W in a unified manner. The batch type substrate processing apparatus 1 includes: a substrate holding portion that holds a plurality of substrates W; and a supply portion that supplies the processing liquid to the substrates W by supplying the processing liquid to the inside of the processing tank.

[0031] Next, refer to Figure 2 An example of the prepared substrate W is described below. The substrate W includes, for example, a base substrate W1 such as a silicon wafer, a titanium nitride film W2, a conductive film W3, a silicon nitride film W4, and a zirconium oxide film W5 in this order. The laminated structure of the substrate W is not limited to Figure 2 For example, the substrate W may have a functional layer (not shown) between the base substrate W1 and the titanium nitride film W2.

[0032] The titanium nitride film W2, the conductive film W3, the silicon nitride film W4, and the zirconium oxide film W5 are stacked in this order on the base substrate W1. An opening OP is formed that penetrates the zirconium oxide film W5, the silicon nitride film W4, the conductive film W3, and the titanium nitride film W2. For example, the opening OP is formed by dry etching using the zirconium oxide film W5 as a hard mask. The opening OP is, for example, a groove.

[0033] There is no particular limitation on the use of the substrate W, and it is, for example, a semiconductor memory such as a DRAM. In this case, the titanium nitride film W2 is a bit line contact, and the conductive film W3 is a bit line. The titanium nitride film W2 may contain silicon (Si) or may not contain silicon. The conductive film W3 may include, for example, a Ru film, a W film, or a Mo film, preferably a Ru film. The conductive film W3 may be composed of a plurality of films, and for example, these films may be provided in the order of a TiSiN film and a Ru film on the titanium nitride film W2. The silicon nitride film W4 is a protective film for protecting the conductive film W3.

[0034] The substrate processing apparatus 1 removes the unnecessary zirconium oxide film W5 after forming the opening OP. The substrate processing apparatus 1 selectively etches the zirconium oxide film W5 among the plurality of films W2 to W5 exposed on the surface Wa of the substrate W by supplying an etching liquid to the surface Wa of the substrate W. Thus, the zirconium oxide film W5 can be removed while suppressing pattern collapse.

[0035] In addition, generally speaking, sulfuric acid is used as an etching solution for the zirconium oxide film W5 as described in Patent Document 1. However, sulfuric acid also etches the titanium nitride film W2. Therefore, when sulfuric acid is used, there is a problem that the concave-convex pattern on the substrate surface Wa collapses. In addition, it is also considered to use dilute hydrofluoric acid (DHF) obtained by diluting hydrofluoric acid (HF aqueous solution, HF concentration is 40% to 65% by mass) with water, but DHF has a problem that it completely removes the silicon nitride film W4 before completely removing the zirconium oxide film W5.

[0036] Therefore, in the present embodiment, hydrofluoric acid (HF aqueous solution, HF concentration is 40 mass % to 65 mass %) is diluted with an organic solvent and used as an etching solution. The etching solution contains, for example, 0.7 mass % to 6.5 mass % of hydrogen fluoride (HF), 87.0 mass % to 98.6 mass % of an organic solvent, and 0.7 mass % to 6.5 mass % of water. In addition, the less the water content in the etching solution, the better. If pure HF can be prepared instead of the HF aqueous solution, the water content in the etching solution is preferably 0.0 mass %.

[0037] Unlike Patent Document 1, hydrofluoric acid is used instead of sulfuric acid, thereby preventing the titanium nitride film W2 from being etched, thereby preventing the concave-convex pattern from collapsing. Also, unlike Patent Document 2, hydrofluoric acid is diluted with an organic solvent instead of water, thereby preventing the silicon nitride film W4 from being etched.

[0038] The equilibrium state of HF in the HF aqueous solution is as follows.

[0039]

[0040] HF2 - It is an etching factor for both the silicon nitride film W4 and the zirconium oxide film W5. Non-dissociated HF is an etching factor for the zirconium oxide film W5. Therefore, by increasing the amount of non-dissociated HF in the processing liquid, the etching selectivity of the zirconium oxide film W5 relative to the silicon nitride film W4 (etching speed of W5 / etching speed of W4) can be improved. When increasing the amount of non-dissociated HF, it is sufficient to increase the HF concentration in the etching solution, but in this method, since the SiN etching amount will increase accordingly, it is limited.

[0041] In a solvent with a high dielectric constant (high polarizability) such as DIW, HF can obtain F- or HF2 - In contrast, in a solvent with a low dielectric constant (small polarization) such as an organic solvent, solvation is difficult to occur, and HF is in a non-dissociated state. In this embodiment, by utilizing this phenomenon, hydrofluoric acid is diluted with an organic solvent, thereby increasing the amount of non-dissociated HF, thereby improving the etching selectivity of the zirconium oxide film W5 to the silicon nitride film W4 (etching speed of W5 / etching speed of W4).

[0042] The organic solvent constituting the etching solution is not particularly limited as long as it is compatible with water and has a relative dielectric constant lower than that of water, and may include, for example, IPA, EG (ethylene glycol), acetic acid, ethanol or methanol. The relative dielectric constant of the organic solvent is preferably less than 1 / 2 of the relative dielectric constant of DIW. The relative dielectric constant of IPA is about 1 / 4 of the relative dielectric constant of DIW.

[0043] Next, refer to Figure 4 An example of the relationship between the mixing ratio of the etching solution and the etching rate of the zirconium oxide film W5 is described below. Figure 4 In the formula, the mixing ratio indicates the volume ratio of HF aqueous solution with HF concentration of 50 wt% to the organic solvent (HF aqueous solution: organic solvent). Figure 4 The greater the slope of the straight line, the greater the etching rate of the zirconium oxide film W5. Figure 4 R1~R4 shown or according to Figure 4 As shown in R5 to R6, the greater the HF content, the faster the etching rate of the zirconium oxide film W5. Figure 4 From R3 and R6 shown, it can be seen that when the volume ratio of the HF aqueous solution to the organic solvent is the same, the etching rate is faster when IPA is used as the organic solvent than when EG is used as the organic solvent.

[0044] Next, refer to Figure 5 An example of the relationship between the film type (TiN, TiSiN, SiN) and the film etching rate is described below. Figure 5 In the Figure 4 R1 is shown as the etching solution. Figure 5 In the above, the "upper limit" is the upper limit of the etching amount that does not cause the concave-convex pattern to collapse. Figure 5 In FIG. 1 , the white circle indicates the amount of SiN etched when DHF (dilute hydrofluoric acid) is used as the etching solution. Figure 5 It is found that the collapse of the concavo-convex pattern can be suppressed by diluting the HF aqueous solution with an organic solvent and using it as an etching solution.

[0045] In addition, as described above, the etching solution contains an organic solvent. Therefore, the zirconium oxide film W5 preferably contains an organic substance to increase the etching rate. The organic substance is derived from an organic zirconium compound, for example. The zirconium oxide film W5 is formed by applying a liquid obtained by dissolving an organic zirconium compound in an organic solvent, drying it, and firing it.

[0046] When the etching liquid is supplied, the temperature of the substrate W is, for example, 50° C. or less, preferably 30° C. or less. When hydrofluoric acid is diluted with an organic solvent and used as an etching liquid, unlike the case of using sulfuric acid, there is no need to heat the substrate W. When the etching liquid is supplied, the temperature of the substrate W may be above room temperature, for example, 5° C. or more, preferably 20° C. or more.

[0047] Next, refer to Figure 3 A substrate processing method according to an embodiment of the present invention is described below. Figure 3 As shown, the substrate processing method includes, for example, steps S101 to S107. Steps S101 to S107 are performed under the control of the control unit 90. When a transport device (not shown) carries the substrate W into the processing container 10, the processing in and after step S101 starts.

[0048] In addition, the substrate processing method may not include all steps of steps S101 to S107, and may include at least steps S101 and S103. Next, the case where IPA is used as the organic solvent constituting the etching solution in step S103 is described. In steps S102, S103, and S104, the same organic solvent is preferably used, but different organic solvents may also be used.

[0049] First, the substrate holding unit 20 holds the substrate W horizontally with the surface Wa of the substrate W facing upward (step S101). The substrate holding unit 20 holds the substrate W in such a manner that the rotation center line of the substrate W passes through the center of the surface Wa of the substrate W. Thereafter, the substrate rotating unit 25 rotates the substrate W together with the substrate holding unit 20. Hereinafter, the surface Wa of the substrate W is sometimes referred to as the substrate surface Wa.

[0050] While the substrate W is being rotated, steps S102 to S107 are performed on the substrate surface Wa. First, the nozzle 41 supplies IPA to the substrate surface Wa (step S102). The nozzle 41 supplies IPA to the center of the substrate surface Wa. The IPA flows radially outward of the substrate surface Wa by centrifugal force, and forms a liquid film on the entire substrate surface Wa.

[0051] Next, the nozzle 41 supplies an etching liquid to the substrate surface Wa (step S103). The etching liquid contains HF and IPA, and is obtained by diluting the HF aqueous solution with IPA. The nozzle 41 supplies the etching liquid to the center of the substrate surface Wa. The etching liquid replaces the IPA remaining on the substrate W while flowing radially outward of the substrate surface Wa by centrifugal force, forming a liquid film on the entire substrate surface Wa.

[0052] Next, the nozzle 41 supplies IPA to the substrate surface Wa (step S104). The nozzle 41 supplies IPA to the center of the substrate surface Wa. While displacing the etching liquid remaining on the substrate W, the IPA flows radially outward of the substrate surface Wa by centrifugal force, forming a liquid film on the entire substrate surface Wa.

[0053] Next, the nozzle 41 supplies a mixture of IPA and DIW to the substrate surface Wa (step S105). The nozzle 41 supplies the mixture of IPA and DIW to the center of the substrate surface Wa. The mixture of IPA and DIW replaces the IPA remaining on the substrate W while flowing radially outward of the substrate surface Wa by centrifugal force to form a liquid film on the entire substrate surface Wa. In step S104, the content of IPA may be reduced in stages or continuously, and the content of DIW may be increased in stages or continuously over time.

[0054] Next, the nozzle 41 supplies DIW to the substrate surface Wa (step S106). The nozzle 41 supplies pure DIW to the center of the substrate surface Wa. While displacing the IPA remaining on the substrate W, the DIW flows radially outward of the substrate surface Wa by centrifugal force, forming a liquid film on the entire substrate surface Wa. By supplying pure DIW, fluorine ions from the etching solution can be removed.

[0055] After the supply of all the processing liquids is completed, the substrate rotating unit 25 rotates the substrate W together with the substrate holding unit 20, thereby spin-drying the substrate W (step S107). When the substrate W is spin-dried, IPA may be supplied again after DIW is supplied to form a liquid film of IPA on the substrate surface Wa. Since IPA has a lower surface tension than DIW, it is possible to suppress the collapse of the concave-convex pattern. The drying method of the substrate W is not limited to spin drying, and may be, for example, supercritical drying or hydrophobic drying using a silylating agent.

[0056] According to this embodiment, at least one of before and after the etching solution is supplied (step S103) Figure 3 In the embodiment of the present invention, an organic solvent substantially free of water is supplied to the substrate surface Wa. In the present specification, the organic solvent substantially free of water means that the water content is 0.0 mass % to 3.0 mass %.

[0057] If an organic solvent is supplied to the substrate surface Wa in advance in step S102 before step S103, the etching liquid can easily wet the substrate surface Wa in step S103. Here, the organic solvent substantially free of water is used to suppress the etching of the silicon nitride film W4 due to the influence of water remaining on the substrate W in step S103.

[0058] By supplying an organic solvent to the substrate surface Wa in step S104 after step S103, the etching liquid remaining on the substrate W can be removed. Here, the organic solvent substantially free of water is used to suppress etching of the silicon nitride film W4 by HF and water remaining on the substrate W in step S104.

[0059] In addition, according to the present embodiment, after supplying the etching liquid (step S103), these processes are performed in the order of supplying an organic solvent substantially free of water to the substrate surface Wa (step S104), supplying a mixed liquid of an organic solvent and water to the substrate surface Wa (step S105), and supplying pure water to the substrate surface Wa (step S106). Thus, the composition of the liquid film can be changed from the organic solvent to pure water in stages.

[0060] The above is a description of the embodiments of the substrate processing method and substrate processing device involved in the present disclosure, but the present disclosure is not limited to the above embodiments, etc. 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.

[0061] This application claims the priority of Special Application No. 2022-135695 filed with the Japan Patent Office on August 29, 2022, and all the contents of Special Application No. 2022-135695 are incorporated herein by reference.

[0062] Description of Reference Numerals

[0063] 1: substrate processing device; 20: substrate holding part; 25: substrate rotating part; 31: supply part; 90: control part; W: substrate; W2: titanium nitride film; W5: zirconium oxide film; Wa: surface.

Claims

1. A substrate processing method, comprising: preparing a substrate, on the surface of which a titanium nitride film and a zirconium oxide film are exposed; as well as By supplying an etching solution containing hydrogen fluoride and an organic solvent to the surface of the substrate, the zirconium oxide film is selectively etched between the titanium nitride film and the zirconium oxide film.

2. The substrate processing method according to claim 1, wherein: A silicon nitride film is also exposed on the surface of the substrate. The substrate processing method includes supplying the etching solution to the surface of the substrate to selectively etch the zirconium oxide film among the titanium nitride film, the silicon nitride film, and the zirconium oxide film.

3. The substrate processing method according to claim 2, wherein: A conductive film, a silicon nitride film, and a zirconium oxide film are stacked in this order on the titanium nitride film. An opening is formed that penetrates the zirconium oxide film, the silicon nitride film, the conductive film, and the titanium nitride film.

4. The substrate processing method according to claim 3, wherein: The conductive film includes a Ru film, a W film, or a Mo film.

5. The substrate processing method according to any one of claims 1 to 4, wherein: The etching solution contains 0.7% to 6.5% by mass of hydrogen fluoride, 87.0% to 98.6% by mass of an organic solvent, and 0.7% to 6.5% by mass of water.

6. The substrate processing method according to any one of claims 1 to 4, wherein: The zirconium oxide film contains organic matter.

7. The substrate processing method according to any one of claims 1 to 4, wherein: The etching solution contains isopropyl alcohol (IPA), ethylene glycol, acetic acid, ethanol or methanol as an organic solvent.

8. The substrate processing method according to any one of claims 1 to 4, wherein: When the etching solution is supplied, the temperature of the substrate is 50° C. or less.

9. The substrate processing method according to any one of claims 1 to 4, wherein: include: An organic solvent substantially containing no water is supplied to the surface of the substrate at least one of before and after the etching solution is supplied.

10. The substrate processing method according to any one of claims 1 to 4, wherein: After supplying the etching solution, the processes of supplying an organic solvent substantially free of water to the surface of the substrate, supplying a mixed solution of an organic solvent and water to the surface of the substrate, and supplying pure water to the surface of the substrate are included in this order.

11. A substrate processing device comprising: a substrate holding portion that holds a substrate on a surface of which the titanium nitride film and the zirconium oxide film are exposed; and A supply unit supplies an etching solution containing hydrogen fluoride and an organic solvent to the surface of the substrate held by the substrate holding unit, thereby selectively etching the zirconium oxide film between the titanium nitride film and the zirconium oxide film.

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