Manufacturing method of semiconductor substrate for memory devices

Abstract

This invention provides a method for manufacturing a high-functionality semiconductor substrate for memory devices with high production efficiency. A method for manufacturing a semiconductor substrate for memory devices includes the following steps: step (1), contacting a semiconductor substrate having a titanium-containing film, a tungsten film, and a tungsten oxide film containing at least one of titanium and titanium alloys with a pretreatment agent to remove at least a portion of the aforementioned tungsten oxide film; and step (2), contacting the semiconductor substrate after step (1) with an etchant to remove at least a portion of the aforementioned titanium-containing film; wherein the aforementioned pretreatment agent contains a tungsten oxide etchant selected from at least one of the group consisting of acids, ammonia, and ammonium salts.

Description

Technical Field

[0001] This invention relates to a method for manufacturing a semiconductor substrate for memory devices. Prior Technology

[0002] In recent years, there has been an increasing demand for further miniaturization and high functionality of memory components, and the development of technologies such as miniaturization and three-dimensional integration of semiconductor substrates is underway.

[0003] In semiconductor substrates that enable miniaturization and high functionality of memory devices as described above, tungsten metal is an ideal material choice. Tungsten metal can be deposited using CVD (chemical vapor deposition) and exhibits characteristics such as low electromigration resistance, low electrical resistance, and high heat resistance. Therefore, tungsten metal is used in memory devices such as DRAM for embedded word lines.

[0004] The aforementioned embedded character lines are known to be manufactured, for example, by the following method. Specifically, on a silicon substrate having recesses formed by etching, a silicon oxide film, a titanium-containing film (barrier film) containing titanium or a titanium alloy, and a tungsten film are sequentially formed. Then, the substrate is planarized using CMP (chemical mechanical polishing), and then the titanium-containing film and the tungsten film, or the tungsten film, are selectively etched using dry etching or the like (CMP can be omitted). Then, the titanium-containing film is selectively etched, thereby manufacturing the embedded character lines of the memory element (Non-Patent Document 1).

[0005] As mentioned above, the manufacturing method of semiconductor substrates for memory devices includes a step of selectively removing titanium and titanium alloys without damaging tungsten metal (selective etching step of titanium and titanium alloys). Therefore, when manufacturing small and high-performance memory devices using tungsten metal, an etchant that etches titanium and titanium alloys without etching tungsten metal (high Ti / W etch selectivity ratio) is required. [Previous Technical Documents] [Non-patent literature]

[0006] [Non-patent document 1] SPCC 2019 Technical Program, "Wet Etchant for DRAM Word-line Titanium Nitride Recess with Selectivity to Tungsten", Wilson et al., [https: / / www.linx-consulting.com / wp-content / uploads / 2019 / 04 / 03-15-W_Yeh-Dupont-Wet_Etchant_for_DRAM_Word_line_TiN_Recess_with_Selectivity_to_W.pdf] Summary of the Invention

[0007] [The problem that the invention aims to solve]

[0008] However, it has been found that even when using conventional etchants to manufacture semiconductor substrates for memory devices using tungsten as the material, sometimes the desired performance of the memory device cannot be obtained. One reason for this is believed to be the influence of the tungsten oxide film formed during the manufacturing process of the semiconductor substrate for memory devices due to the oxidation of the tungsten film surface. For example, in buried word lines, if the tungsten oxide film exists in the form of covering at least a portion of the surface containing a titanium film, sometimes the etchant cannot contact the titanium or titanium alloy, and thus cannot etch the titanium or titanium alloy.

[0009] Therefore, it is believed that a pretreatment agent is used to remove tungsten oxide before the selective etching step of titanium nitride using an etchant. However, if the removal rate of the tungsten oxide film by the pretreatment agent is slow, the pretreatment time required using the pretreatment agent increases, thereby reducing the production efficiency (throughput) of semiconductor substrates for memory devices. Therefore, it is advisable to use a pretreatment agent with a high tungsten oxide removal rate. By using such a pretreatment agent to quickly remove the tungsten oxide film, followed by the selective etching step of titanium or titanium alloys using an etchant, high-performance semiconductor substrates for memory devices can be manufactured with high production efficiency.

[0010] In other words, the present invention provides a method for manufacturing semiconductor substrates for high-functionality memory devices with high production efficiency. [Methods for solving problems]

[0011] The inventors of this invention have diligently researched ways to solve the aforementioned problems. They discovered that by using a predetermined pretreatment agent to remove the tungsten oxide film before the selective etching step of titanium or titanium alloys using an etchant, the aforementioned problems can be solved, thus completing this invention. That is, this invention is as follows, for example.

[0012] [1] A method for manufacturing a semiconductor substrate for memory devices, comprising the following steps: Step (1) involves contacting a semiconductor substrate having a titanium-containing film, a tungsten film, and a tungsten oxide film containing at least one of titanium and titanium alloys with a pretreatment agent to remove at least a portion of the aforementioned tungsten oxide film; and Step (2) involves bringing the semiconductor substrate from step (1) into contact with an etchant to remove at least a portion of the aforementioned titanium-containing film; The aforementioned pretreatment agent contains a tungsten oxide etchant selected from at least one of the group consisting of acids, ammonia, and ammonium salts. [2] The method for manufacturing a semiconductor substrate for memory devices as described in [1] above, wherein the pH of the aforementioned pretreatment agent is 0.1 to 13. [3] The method for manufacturing a semiconductor substrate for memory devices as described in [1] or [2] above, wherein the aforementioned tungsten oxide etchant contains at least one selected from the group consisting of hydrogen fluoride, hydrogen chloride, hydrogen bromide, hydrogen iodide, sulfuric acid, nitric acid, and phosphoric acid. [4] A method for manufacturing a semiconductor substrate for a memory element as described in any of [1] to [3] above, wherein, The aforementioned semiconductor substrate further contains a titanium oxide film, and The aforementioned step (1) further includes the step of removing at least a portion of the aforementioned titanium oxide film. [5] A method for manufacturing a semiconductor substrate for a memory element as described in any of [1] to [4] above, wherein, The aforementioned etchant contains (A) an oxidizing agent, (B) a fluorine compound, and (C) a tungsten resist. The addition ratio of the aforementioned oxidant (A) is 0.0001 to 10% by mass relative to the total mass of the aforementioned etchant. The addition ratio of the aforementioned fluorine compound (B) relative to the total mass of the aforementioned etchant is 0.005 to 10% by mass. The addition ratio of the aforementioned (C) tungsten resist is 0.0001 to 5% of the total mass of the aforementioned etchant. [6] The method for manufacturing a semiconductor substrate for memory elements as described in [5] above, wherein the aforementioned oxidant (A) contains at least one selected from the group consisting of peroxy acids, halogenated oxyacids, and salts thereof. [7] The method for manufacturing a semiconductor substrate for memory elements as described in [5] or [6] above, wherein the aforementioned (B) fluorine compound contains at least one selected from the group consisting of hydrogen fluoride (HF), tetrafluoroboric acid (HBF 4), hexafluorosilicic acid (H 2SiF 6), hexafluorozirconic acid (H 2ZrF 6), hexafluorotitanic acid (H 2TiF 6), hexafluorophosphate (HPF 6), hexafluoroaluminic acid (H 2AlF 6), hexafluorogermanic acid (H 2GeF 6), and salts thereof. [8] The method for manufacturing a semiconductor substrate for a memory element as described in any of [5] to [7] above, wherein the aforementioned (C) tungsten resist contains at least one selected from the group consisting of an ammonium salt represented by the following formula (1) and a heteroaryl salt having an alkyl group having 5 to 30 carbon atoms; [Chemistry 1] In the above formula (1), R1 is an alkyl group having 5 to 30 carbon atoms, a substituted or unsubstituted alkyl (poly)hexaalkyl group, a substituted or unsubstituted aryl (poly)hexaalkyl group, or a group represented by the following formula (2). [Chemistry 2] In the above formula, Cy represents cyclic alkyl groups with 3 to 10 carbon atoms (substituted or unsubstituted), heterocyclic alkyl groups with 2 to 10 carbon atoms (substituted or unsubstituted), aryl groups with 6 to 15 carbon atoms (substituted or unsubstituted), and heteroaryl groups with 2 to 15 carbon atoms (substituted or unsubstituted). A is an alkyl group with 1 to 5 carbon atoms, r is 0 or 1, Z is any one of the following formulas; [Chemistry 3] R2 can be an alkyl group with 1 to 18 carbon atoms, substituted or unsubstituted, or an aryl group with 6 to 20 carbon atoms, substituted or unsubstituted. X represents halide ions, hydroxide ions, organic sulfonic acid ions, tetrafluoroborate ions, and hexafluorophosphate ions. [Effects of the Invention]

[0013] According to the present invention, a method for manufacturing a semiconductor substrate for high-functionality memory devices with high production efficiency is provided. Simple Explanation of the Diagram

[0014] [Figure 1] is a schematic diagram of step (1) of the present invention. Implementation

[0015] The following is a detailed description of the form in which the present invention is carried out.

[0016] <Manufacturing Method of Semiconductor Substrates for Memory Elements> The method for manufacturing a semiconductor substrate for memory elements according to the present invention includes the following steps: step (1), contacting a semiconductor substrate having a titanium-containing film, a tungsten film, and a tungsten oxide film containing at least one of titanium and titanium alloys with a pretreatment agent to remove at least a portion of the aforementioned tungsten oxide film; and step (2), contacting the semiconductor substrate after step (1) with an etchant to remove at least a portion of the aforementioned titanium-containing film. In this case, the aforementioned pretreatment agent contains a tungsten oxide etchant selected from at least one of the group consisting of acids, ammonia, and ammonium salts.

[0017] The aforementioned pretreatment agent has a high etching rate for tungsten oxide formed on the surface of a tungsten-containing material on a semiconductor substrate, which can ideally remove the tungsten oxide, so the throughput is not reduced. Furthermore, the etching rate of tungsten metal during pretreatment is very slow, so high-performance semiconductor substrates for memory devices can be manufactured with high production efficiency.

[0018] Furthermore, regarding the aforementioned titanium alloys, there are no particular limitations as long as they are formed by adding one or more metallic or non-metallic elements other than titanium and possess metallic properties. Examples include alloys of titanium with at least one element selected from the group consisting of aluminum, nitrogen, carbon, molybdenum, vanadium, niobium, iron, chromium, nickel, tin, hafnium, zirconium, palladium, ruthenium, and platinum. Among these, titanium nitride is preferred. In addition, in this specification, "titanium alloy" means a titanium content of 20 atomic percent or more relative to the total atomic weight of the titanium alloy. Furthermore, the titanium content in the titanium alloy is preferably 20 atomic percent or more relative to the total atomic weight of the titanium alloy, more preferably 30 atomic percent, more preferably 35 atomic percent, and particularly preferably 40 to 99.9 atomic percent.

[0019] Furthermore, in this specification, "tungsten oxide" refers to tungsten oxide formed by the oxidation of metallic tungsten, and usually means tungsten oxide (VI) (WO 3).

[0020] The present invention will now be described with reference to the drawings. Furthermore, the drawings may sometimes be exaggerated for illustrative purposes and may differ from the actual dimensions.

[0021] Figure 1 is a schematic diagram of step (1) of the present invention. The semiconductor substrate (before step (1)) 10 has: a silicon substrate 11 with recesses, an insulating film 12 made of silicon oxide, a barrier film 13 made of titanium nitride, and a tungsten film 14. The semiconductor substrate (before step (1)) 10 can be manufactured by sequentially forming the insulating film made of silicon oxide, the barrier film made of titanium nitride, and the tungsten film on the silicon substrate with recesses, and performing planarization using CMP (chemical mechanical polishing) and selective etching of the barrier film and the tungsten film using dry etching (CMP can also be omitted). Here, the semiconductor substrate (before cleaning) 10 has a tungsten oxide film 15 formed by the oxidation of tungsten on the barrier film 13 and the tungsten film 14. The tungsten oxide film 15 exists in the form of covering the surface of the barrier film 13. Therefore, even if the barrier film 13 composed of titanium nitride is selectively etched, there are sometimes situations where the etchant cannot ideally contact the barrier film 13, and the barrier film 13 cannot be etched. Here, referring to the enlarged view in FIG1, a titanium oxide film 16 is formed on the surface of the barrier film 13 composed of titanium nitride. The aforementioned titanium oxide film 16 may be formed due to the loose film density of the tungsten oxide film 15, allowing the oxygen of the tungsten oxide film 15 to pass through to the surface of the barrier film 13, causing the titanium nitride to oxidize. In addition, the aforementioned titanium oxide film 16 may be formed due to the oxidation of titanium nitride caused by an ashing step that is not necessary during the manufacturing process of the semiconductor substrate for memory devices.

[0022] The tungsten oxide film 15 can be removed by using a pretreatment agent on the semiconductor substrate 10 (before cleaning) with such a structure. At this time, the etching rate of the tungsten oxide by the aforementioned pretreatment agent is high, so the throughput will not decrease and high production efficiency can be achieved. In addition, the etching of tungsten metal during pretreatment can be prevented or suppressed. As a result, the semiconductor substrate 20 obtained after pretreatment (after step (1)) will have the following stacked structure: a silicon substrate 21 with recesses, an insulating film 22 made of silicon oxide, a barrier film 23 made of titanium nitride, and a tungsten metal film 24. Therefore, if an etchant is used in step (2), the etchant can ideally contact the barrier film 23. As a result, titanium nitride can be selectively etched, and the semiconductor substrate 30 obtained (after step (2)) has the following stacked structure: a silicon substrate 31 with recesses, an insulating film 32, an etched barrier film 33, and a tungsten metal film 34.

[0023] Furthermore, in a preferred embodiment, the pretreatment agent does not cause or hardly causes galvanic corrosion (dissimilar metal contact corrosion). In the case of titanium, titanium alloys, and tungsten contact, depending on the processing environment, galvanic corrosion can sometimes easily occur in tungsten, which has a relatively lower intrinsic potential compared to titanium and titanium alloys. However, in a preferred embodiment of the present invention, by using a suitable pretreatment agent, galvanic corrosion can be prevented or inhibited.

[0024] Furthermore, in a preferred embodiment, the pretreatment agent can remove at least a portion of the titanium oxide film 16 along with the tungsten oxide film 15. This allows the etchant to contact titanium and titanium alloys more effectively. Consequently, titanium and titanium alloys can be selectively etched further, enabling the fabrication of high-performance semiconductor substrates.

[0025] The following is a detailed explanation of each step.

[0026] [Step (1)] Step (1) involves contacting a semiconductor substrate having a titanium-containing film, a tungsten film, and a tungsten oxide film containing at least one of titanium and titanium alloys with a pretreatment agent to remove at least a portion of the aforementioned tungsten oxide film.

[0027] (Semiconductor substrate) The semiconductor substrate has a titanium-containing film, a tungsten film, and a tungsten oxide film containing at least one of titanium and titanium alloys. The structure of the semiconductor substrate is not particularly limited, and known structures may be appropriately used.

[0028] For example, when used in embedded word lines of memory elements, the semiconductor substrate may have a structure obtained by sequentially stacking an insulating film, a barrier film made of titanium and / or titanium alloy, and a tungsten film on a silicon substrate with recesses. In this case, the barrier film and the tungsten film are usually arranged adjacent to each other.

[0029] The aforementioned semiconductor substrate further contains a tungsten oxide film formed by the oxidation of tungsten on the surface of the tungsten film. The shape of the aforementioned tungsten oxide film is not particularly limited. For example, a film with uniform thickness or a film with non-uniform thickness can be formed. Furthermore, it can be a single continuous film or multiple discontinuous films. In addition, the volume of tungsten oxide increases with the oxidation of tungsten, so the tungsten oxide film can also exist on the surface of adjacent films of the tungsten film, such as a barrier film. Furthermore, in step (1), the aforementioned tungsten oxide film is ideally removed by a pretreatment agent.

[0030] The aforementioned semiconductor substrate may further contain a titanium oxide film formed by the oxidation of titanium or titanium alloy on the surface of the titanium-containing film. This titanium oxide film may be formed by the natural oxidation of titanium or titanium alloy on the surface of the titanium-containing film. In this case, even if the surface of the titanium-containing film is covered by a tungsten oxide film, if the film density of the tungsten oxide film is loose, oxygen can still pass through the tungsten oxide film, so natural oxidation of the surface of the titanium-containing film may occur. Furthermore, the titanium oxide film may also be formed by the oxidation of titanium or titanium alloy due to an unnecessary ashing step during the manufacturing process of the semiconductor substrate for memory devices. The shape of the aforementioned titanium oxide film is not particularly limited. For example, a film with uniform thickness may be formed, or a film with non-uniform thickness may be formed. Furthermore, it may be a single continuous film, or multiple discontinuous films may exist. It is preferable to remove the aforementioned titanium oxide film in step (1) by means of a pretreatment agent. That is, a preferred embodiment is that the semiconductor substrate further contains a titanium oxide film, and step (1) further includes a step of removing at least a portion of the aforementioned titanium oxide film. Furthermore, in this specification, "titanium oxide" refers to titanium oxide formed by the oxidation of titanium nitride, and generally means titanium oxide (IV) (TiO 2), titanium oxynitride (TiO xN y) (where x is 0.01~2 and y is 0~1), and combinations thereof.

[0031] (Pretreatment agent) The pretreatment agent contains tungsten oxide etchant. At least a portion of the aforementioned tungsten oxide film can be removed by using the aforementioned pretreatment agent. Therefore, the aforementioned pretreatment agent can be considered a treatment agent for removing tungsten oxide films.

[0032] Tungsten oxide etchant The tungsten oxide etchant contains at least one of the group consisting of acids, ammonia, and ammonium salts.

[0033] The aforementioned acids are not particularly limited and can be listed as follows: inorganic acids such as hydrogen fluoride, hydrogen chloride, hydrogen bromide, hydrogen iodide, sulfuric acid, nitric acid, and phosphoric acid; and organic acids such as acetic acid, methanesulfonic acid, trifluoromethanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, and 10-camphorsulfonic acid.

[0034] The aforementioned ammonium salts are not particularly limited, but may include: ammonium fluoride (NH₄F); ammonium hydrogen fluoride (NH₄F·HF); tetraethylammonium hydroxide (TEAH), tetramethylammonium hydroxide (TMAH), ethyltrimethylammonium hydroxide, diethyldimethylammonium hydroxide, triethylmethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, and other tetraalkylammonium hydroxides; benzyltrimethylammonium hydroxide, benzyltriethylammonium hydroxide, and other aryl-containing ammonium hydroxides; trimethyl(2-hydroxyethyl)ammonium hydroxide, triethyl(2-hydroxyethyl)ammonium hydroxide, tripropyl(2-hydroxyethyl)ammonium hydroxide, trimethyl(1-hydroxypropyl)ammonium hydroxide, and other hydroxyl-containing ammonium hydroxides, etc.

[0035] Among the above, the view that tungsten oxide etchants can prevent or inhibit galvanic corrosion is that they are preferably acids, ammonium fluoride, or ammonium hydrogen fluoride, more preferably inorganic acids, and even more preferably hydrogen fluoride, hydrogen chloride, hydrogen bromide, hydrogen iodide, sulfuric acid, nitric acid, or phosphoric acid. The view that they can ideally remove titanium oxide is that they are best made of hydrogen fluoride.

[0036] The aforementioned tungsten oxide etchant can be used alone or in combination of two or more. That is, in one embodiment, the tungsten oxide etchant, to prevent or inhibit galvanic corrosion, preferably contains at least one selected from the group consisting of acids, ammonium fluoride, and ammonium bifluoride, more preferably contains at least one inorganic acid, even more preferably contains at least one selected from the group consisting of hydrogen fluoride, hydrogen chloride, hydrogen bromide, hydrogen iodide, sulfuric acid, nitric acid, and phosphoric acid, particularly preferably contains at least one selected from the group consisting of hydrogen fluoride, hydrogen chloride, hydrogen bromide, hydrogen iodide, sulfuric acid, and nitric acid, and to ideally remove titanium oxide, it most preferably contains hydrogen fluoride.

[0037] The content of tungsten oxide etchant relative to the total mass of the pretreatment agent is preferably 0.001 to 50% by mass, more preferably 0.01 to 10% by mass, even more preferably 0.03 to 3% by mass, and particularly preferably 0.05 to 1% by mass. If the content of tungsten oxide etchant is 0.001% by mass or more, the etching rate of tungsten oxide increases, which is ideal. On the other hand, if the content of tungsten oxide etchant is 50% by mass or less, the etching of metallic tungsten can be prevented or suppressed in step (1), which is also ideal.

[0038] solvent The pretreatment agent should preferably contain a solvent. The aforementioned solvent has the functions of uniformly dispersing the various components contained in the pretreatment agent and diluting them.

[0039] Examples of solvents mentioned above include water and organic solvents.

[0040] The aforementioned water is not particularly limited, but should be water obtained by removing metal ions, organic impurities, and particulate matter through distillation, ion exchange, filtration, or various adsorption treatments. It should be pure water, and especially ultrapure water.

[0041] The aforementioned organic solvents are not particularly limited and may include: methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, tributanol, etc.; ethylene glycol, propylene glycol, neopentyl glycol, 1,2-hexanediol, 1,6-hexanediol, 2-ethylhexane-1,3-diol, glycerol, etc.; diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, dipropylene glycol monomethyl ether, tripropylene glycol monomethyl ether, dipropylene glycol dimethyl ether, dipropylene glycol monoethyl ether, propylene glycol n-propyl ether, dipropylene glycol n-propyl ether, tripropylene glycol n-propyl ether, propylene glycol n-butyl ether, dipropylene glycol n-butyl ether, tripropylene glycol n-butyl ether, propylene glycol phenyl ether, etc.

[0042] Of the above, water is preferred as the solvent. Furthermore, the aforementioned solvents can be used alone or in combination of two or more.

[0043] Regarding the addition ratio of solvent, especially water, it should preferably be 50% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and most preferably 95% by mass or more, relative to the total mass of the pretreatment agent.

[0044] additive The pretreatment agent may also contain additives. These additives are not particularly limited and may include, for example, lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, beryllium hydroxide, magnesium hydroxide, calcium hydroxide, strontium hydroxide, barium hydroxide, and other pH adjusters. These additives may be used alone or in combination of two or more.

[0045] Properties of pretreatment agents The view that the pH of the pretreatment agent should be 0.1~13 to prevent or inhibit galvanic corrosion is preferred to be 0.5~10, more preferably 0.5~5, and especially preferably 0.4~2.5.

[0046] The etching rate of the tungsten oxide in the pretreatment agent should preferably be 15 Å / min or higher, more preferably 20~500 Å / min, even more preferably 20~100 Å / min, and particularly preferably 20~50 Å / min. An etching rate of 15 Å / min or higher in the pretreatment agent does not reduce the throughput and prevents etching of the metallic tungsten during pretreatment, thus it is more ideal. Furthermore, the etching rate of the tungsten oxide in the pretreatment agent refers to the value measured by the method described in the examples.

[0047] The etching rate of the tungsten metal in the pretreatment agent should preferably be below 10 Å / min, more preferably below 7.5 Å / min, even more preferably below 5.0 Å / min, particularly preferably below 3.0 Å / min, and most preferably 0.1~2.8 Å / min. An etching rate of 10 Å / min or less in the tungsten metal of the pretreatment agent can prevent etching of the tungsten metal in step (1) (during pretreatment), which is ideal. Furthermore, the etching rate of the tungsten metal in the pretreatment agent refers to the value measured by the method described in the examples.

[0048] The etching rate of the titanium or titanium alloy in the pretreatment agent should preferably be below 10 Å / min, more preferably below 6 Å / min, and even more preferably below 2 Å / min. If the etching rate of the titanium or titanium alloy in the pretreatment agent is below 10 Å / min, the etching in step (2) described later can be performed ideally, which is therefore more desirable. Furthermore, the etching rate of the titanium or titanium alloy in the pretreatment agent refers to the value measured by the method described in the examples.

[0049] The etching rate of the insulating layer material of the pretreatment agent should preferably be 3.0 Å / min or less, more preferably 1.0 Å / min or less, even more preferably 0.3 Å / min or less, particularly preferably 0.2 Å / min or less, and most preferably 0.1 Å / min or less. When the etching rate of the insulating layer material of the pretreatment agent is 3.0 Å / min or less, the shape of the semiconductor substrate is maintained and the performance of the semiconductor device is improved, which is ideal. Furthermore, the aforementioned insulating layer material is not particularly limited, and silicon oxide (e.g., th-Ox) can be cited as an example. Also, the etching rate of the insulating layer material of the pretreatment agent refers to the value measured by the method of the embodiment.

[0050] The WO3 / W etch selectivity of the pretreatment agent should preferably be 5 or higher, more preferably 10-100, even better 15-100, particularly preferably 30-100, and most preferably 50-90. A WO3 / W etch selectivity of 5 or higher is ideal for manufacturing semiconductor substrates for high-performance memory devices. Furthermore, in this specification, "WO3 / W etch selectivity" refers to the etch selectivity ratio of tungsten oxide to tungsten metal, specifically the ratio of the etch rate of tungsten oxide to the etch rate of tungsten metal (etch rate of tungsten oxide / etch rate of tungsten metal).

[0051] The corrosion potential of the tungsten (W) pretreatment agent is preferably -1000 to -50 mV, more preferably -500 to -50 mV, even more preferably -300 to -50 mV, particularly preferably -150 to -60 mV, and most preferably -115 to -70 mV. Furthermore, the corrosion potential of the tungsten (W) pretreatment agent refers to the value measured by the method described in the examples.

[0052] The corrosion potential of the titanium or titanium alloy in the pretreatment agent is preferably -500 to -20 mV, more preferably -350 to -20 mV, even more preferably -200 to -20 mV, particularly preferably -130 to -30 mV, and most preferably -100 to -40 mV. Furthermore, the corrosion potential of the titanium or titanium alloy in the pretreatment agent refers to the value measured by the method described in the examples.

[0053] The corrosion potential difference (corrosion potential of tungsten (W) and titanium / titanium alloy) in the pretreatment agent is not particularly limited, but is preferably -50~300mV, more preferably -50~200mV, even more preferably -30~100mV, particularly preferably -30~50mV, and most preferably -10~40mV. A corrosion potential difference within the above range can prevent or inhibit galvanic corrosion of tungsten (W), and is therefore ideal.

[0054] (touch) Regarding the contact method between the semiconductor substrate and the pretreatment agent, there are no particular limitations, and known techniques can be appropriately employed. Specifically, the semiconductor substrate can be immersed in the pretreatment agent, or the pretreatment agent can be sprayed onto the semiconductor substrate, or it can be dripped (e.g., single-wafer rotation processing). In this case, the aforementioned immersion can be repeated more than twice, the spraying can be repeated more than twice, the dripping can be repeated more than twice, or a combination of immersion, spraying, and dripping can be used.

[0055] There are no particular restrictions on the contact temperature, but it is preferable to be 0~90℃, more preferably 15~80℃, and even more preferably 20~70℃.

[0056] There is no particular limitation on the contact time, but it is advisable to be 0 seconds to 3 hours, preferably 10 seconds to 1 hour, even better 10 seconds to 45 minutes, and ideally 20 seconds to 5 minutes.

[0057] At least a portion of the tungsten oxide film can be removed by contacting the semiconductor substrate with a pretreatment agent.

[0058] [Step (2)] Step (2) is a step of removing at least a portion of the aforementioned titanium-containing film by bringing the semiconductor substrate after step (1) into contact with an etchant.

[0059] (Semiconductor substrate after step (1)) The semiconductor substrate after step (1) has a titanium-containing film and a tungsten oxide film. The tungsten oxide film should preferably be completely removed in step (1), but some may remain. Also, when the semiconductor substrate before step (1) contains a titanium oxide film, the titanium oxide film should preferably be completely removed in step (1), but some or all may remain. In the semiconductor substrate after step (1), since at least a portion of the tungsten oxide film has been removed due to step (1), the titanium-containing film can ideally contact the etchant in step (2), and selective etching of titanium and titanium alloys can be ideally performed.

[0060] (Etching agent) Regarding the etchant, there are no particular restrictions as long as it slowly etches tungsten and also etches titanium and titanium alloys (high Ti / W etching selectivity), and known etchants can be used. The etchant preferably contains (A) an oxidant, (B) a fluorine compound, and (C) a tungsten resist. In this case, the addition ratio of the aforementioned (A) oxidant, relative to the total mass of the aforementioned etchant, should preferably be 0.0001 to 10% by mass. Furthermore, the addition ratio of the aforementioned (B) fluorine compound, relative to the total mass of the aforementioned etchant, should preferably be 0.005 to 10% by mass. Moreover, the addition ratio of the aforementioned (C) tungsten resist, relative to the total mass of the aforementioned etchant, should preferably be 0.0001 to 5% by mass. The preferred etchant will be described in detail below. Furthermore, in this specification, "Ti / W etching selectivity" refers to the etching selectivity ratio of titanium / titanium alloys to tungsten, specifically, the ratio of the etching rate of titanium / titanium alloys to the etching rate of tungsten (etching rate of titanium / titanium alloys / etching rate of tungsten).

[0061] (A) Oxidizing agent (A) Oxidizing agents have the function of changing the oxidation number of titanium in titanium and titanium alloys to 4 and dissolving it in etchants.

[0062] (A) The oxidizing agent is not particularly limited, but can be listed as peroxyacid, halogenated oxyacid, and their salts.

[0063] Examples of peroxyacids mentioned above include: hydrogen peroxide, persulfate, percarbonate, perphosphoric acid, peracetic acid, perbenzoic acid, and m-chloroperbenzoic acid.

[0064] The aforementioned halogenated oxyacids can be listed as follows: hypochlorous acid, chlorite, chloric acid, perchloric acid, and other chlorine-containing oxyacids; hypobromous acid, bromous acid, bromic acid, perbromic acid, and other bromine-containing oxyacids; hypoiodic acid, iodous acid, iodic acid, periodic acid, and other iodine-containing oxyacids.

[0065] The aforementioned salts can be categorized as follows: alkali metal salts such as lithium, sodium, potassium, rubidium, and cesium salts of the aforementioned peroxy acids or halogen oxyacids; alkaline earth metal salts such as beryllium, magnesium, calcium, strontium, and barium salts of the aforementioned peroxy acids or halogen oxyacids; metal salts such as aluminum, copper, zinc, and silver salts of the aforementioned peroxy acids or halogen oxyacids; and ammonium salts of the aforementioned peroxy acids or halogen oxyacids.

[0066] The oxidant in (A) above is preferably hydrogen peroxide or an oxyacid of iodine, more preferably hydrogen peroxide, iodic acid, or periodic acid. Considering the viewpoint of improving the Ti / W etching selectivity, hydrogen peroxide or periodic acid is even more preferred, and periodic acid is especially preferred.

[0067] The aforementioned oxidizing agent (A) can be used alone or in combination of two or more. That is, in one embodiment, the oxidizing agent (A) preferably contains at least one selected from the group consisting of peroxyacids, halogen oxyacids, and their salts, more preferably containing at least one selected from the group consisting of hydrogen peroxide and iodine oxyacids, even more preferably containing at least one selected from the group consisting of hydrogen peroxide, iodic acid, and periodic acid, particularly preferably containing at least one selected from the group consisting of hydrogen peroxide and periodic acid, and most preferably containing periodic acid.

[0068] (A) The addition ratio of the oxidant relative to the total mass of the aforementioned etchant is preferably 0.0001 to 10% by mass, more preferably 0.001 to 5% by mass, even more preferably 0.003 to 3% by mass, and especially preferably 0.01 to 2% by mass.

[0069] (B) Fluorine compounds (B) Fluorine compounds have the function of promoting the etching of titanium and titanium alloys.

[0070] The aforementioned (B) fluorine compounds are not particularly limited, and examples include hydrogen fluoride (HF), tetrafluoroboric acid (HBF4), hexafluorosilicic acid (H2SiF6), hexafluorozirconic acid (H2ZrF6), hexafluorotitanic acid (H2TiF6), hexafluorophosphate (HPF6), hexafluoroaluminic acid (H2AlF6), hexafluorogermanic acid (H2GeF6), and salts thereof.

[0071] At this point, ammonium salts such as ammonium fluoride (NH4F), ammonium hydrogen fluoride (NH4F·HF), ammonium tetrafluoroborate (NH4BF4), ammonium hexafluorosilate ((NH4)2SiF6), and tetramethylammonium tetrafluoroborate (N(CH3)4BF4) can be listed as examples of the aforementioned salts.

[0072] Of the above, (B) the fluorine compound is preferably hydrogen fluoride (HF), tetrafluoroboric acid (HBF4), hexafluorosilicic acid (H2SiF6), and salts thereof, more preferably hydrogen fluoride (HF), ammonium fluoride (NH4F), ammonium hydrogen fluoride (NH4F·HF), and hexafluorosilicic acid (H2SiF6). Considering the high etching rate of titanium and titanium alloys, hydrogen fluoride (HF) and ammonium hydrogen fluoride (NH4F·HF) are more preferred, and ammonium hydrogen fluoride (NH4F·HF) is especially preferred.

[0073] In addition, the above-mentioned (B) fluorine compounds can be used alone or in combination of two or more. That is, in a preferred embodiment, (B) the fluorine compound preferably contains at least one selected from the group consisting of hydrogen fluoride (HF), tetrafluoroboric acid (HBF4), hexafluorosilicic acid (H2SiF6), hexafluorozirconic acid (H2ZrF6), hexafluorotitanic acid (H2TiF6), hexafluorophosphate (HPF6), hexafluoroaluminic acid (H2AlF6), hexafluorogermanic acid (H2GeF6), and salts thereof, preferably containing at least one selected from the group consisting of hydrogen fluoride (HF), tetrafluoroboric acid (HBF4), hexafluorosilicic acid (H2SiF6), and salts thereof, more preferably containing a selected from the group consisting of hydrogen fluoride (HF), ammonium fluoride (NH4F), ammonium hydrogen fluoride (NH4F·HF), and hexafluorosilicic acid (H2SiF6). 6) At least one of the constituent groups, preferably containing at least one of the constituent groups consisting of hydrogen fluoride (HF) and ammonium hydrogen fluoride (NH4F·HF), most preferably containing ammonium hydrogen fluoride (NH4F·HF).

[0074] (B) The addition ratio of fluorine compound relative to the total mass of the etchant is preferably 0.005 to 10% by mass, more preferably 0.01 to 5% by mass, even more preferably 0.01 to 3% by mass, and especially preferably 0.03 to 1% by mass.

[0075] (C) Tungsten metal corrosion inhibitor (C) Tungsten metal resist has the function of adsorbing onto tungsten metal to form a protective film and preventing or inhibiting etching by etchants.

[0076] The aforementioned (C) tungsten metal resist is not particularly limited, and examples include ammonium salts represented by the following formula (1) and heteroaryl salts with alkyl groups having 5 to 30 carbon atoms.

[0077] [Chemistry 4]

[0078] In the above formula, R1 is an alkyl group with 5 to 30 carbon atoms, a substituted or unsubstituted alkyl (poly)hexaalkyl group, a substituted or unsubstituted aryl (poly)hexaalkyl group, or a group represented by the following formula (2).

[0079] [Chemistry 5]

[0080] Here, in formula (2), Cy is a substituted or unsubstituted heterocyclic alkyl group, a substituted or unsubstituted heteroaryl group, A is an alkyl group with 1 to 5 carbon atoms, r is 0 or 1, and Z is any of the following formulas.

[0081] [Chemistry 6]

[0082] At this point, * indicates the position of the bond with the nitrogen (N) atom in formula (1). This facilitates adsorption onto tungsten metal and enhances its corrosion resistance.

[0083] Alkyl groups with 5 to 30 carbon atoms are not particularly limited, and examples include pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecanyl, octadecyl, nonadecanyl, and eicosyl.

[0084] Alkyl (poly)heteroalkyl groups are represented by -(CnH2n-Z-)mR3. Here, n is 1 to 5, preferably 1 to 3, and more preferably 1 to 2. m is 1 to 5, preferably 1 to 2. Z is an oxygen atom (O), sulfur atom (S), or phosphorus atom (P), preferably an oxygen atom (O). R3 is an alkyl group with 1 to 30 carbon atoms, such as methyl, ethyl, propyl, isopropyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecanyl, octadecyl, nonadecanyl, eicosyl, etc.

[0085] Alkyl (poly)hexaalkyl groups may also have substituents. These substituents typically replace the hydrogen atom of R3. The substituents used in alkyl (poly)hexaalkyl groups are not particularly limited, and examples include: aryl groups with 6 to 20 carbon atoms such as phenyl and naphthyl; alkoxy groups with 1 to 6 carbon atoms such as methoxy, ethoxy, and propoxy; hydroxyl; cyano; nitro, etc. Furthermore, there may be one or more substituents.

[0086] Aryl (poly)heteroalkyl groups are represented by -(CnH2n-Z-)m-Ar. Here, n is 1 to 5 independently, preferably 1 to 3, and more preferably 1 to 2. m is 1 to 5, preferably 1 to 2. Z is an oxygen atom (O), sulfur atom (S), or phosphorus atom (P), preferably an oxygen atom (O). Ar is an aryl group with 6 to 18 carbon atoms, such as phenyl, naphthyl, anthracene, etc.

[0087] Aryl (poly)hexaalkylene groups may also have substituents. These substituents typically replace the hydrogen atoms of Ar. The substituents used in aryl (poly)hexaalkylene groups are not particularly limited and can include: alkyl groups with 1 to 10 carbon atoms such as methyl, ethyl, propyl, isopropyl, butyl, 1,1-dimethylbutyl, 2,2-dimethylbutyl, and 1,1,3,3-tetramethylbutyl; alkoxy groups with 1 to 6 carbon atoms such as methoxy, ethoxy, and propoxy; hydroxyl; cyano; and nitro. Furthermore, there may be one or more substituents.

[0088] In formula (2), Cy represents a cycloalkyl group with 3 to 10 carbon atoms (substituted or unsubstituted), a heterocycloalkyl group with 2 to 10 carbon atoms (substituted or unsubstituted), an aryl group with 6 to 15 carbon atoms (substituted or unsubstituted), or a heteroaryl group with 2 to 15 carbon atoms (substituted or unsubstituted). The aforementioned cycloalkyl groups with 3 to 10 carbon atoms are not particularly limited, and examples include cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl. The aforementioned heterocycloalkyl groups with 2 to 10 carbon atoms are not particularly limited, and examples include pyrrolidinyl, piperidinyl, tetrahydrofuranyl, tetrahydropyranyl, and tetrahydrothiopheneyl. The aforementioned aryl groups with 6 to 15 carbon atoms are not particularly limited, and examples include phenyl. The aforementioned heteroaryl groups with 2 to 15 carbon atoms are not particularly limited, and examples include pyrrole, imidazolyl, pyrazolyl, acezolyl, isoxazolyl, thiazolyl, isothiazolyl, pyridyl, pyridine, pyridine, pyridyl, pyrimidinyl, quinolinyl, isoquinolinyl, etc.

[0089] The substituents for the aforementioned cycloalkyl groups with 3 to 10 carbon atoms, heterocycloalkyl groups with 2 to 10 carbon atoms, aryl groups with 6 to 15 carbon atoms, and heteroaryl groups with 2 to 15 carbon atoms are not particularly limited. Examples include: alkyl groups with 1 to 10 carbon atoms such as methyl, ethyl, propyl, isopropyl, and butyl; alkoxy groups with 1 to 6 carbon atoms such as methoxy, ethoxy, and propoxy; alkenyloxy groups such as vinyloxy, but-1-enoxy, and -OC(CF3)=C{CF(CF3)2}2; aryloxy groups with 6 to 10 carbon atoms such as phenyl and tolyl; heteroaryl groups with 3 to 10 carbon atoms such as pyrrole, pyridyl, imidazolyl, succinyl, isozolyl, pyrimidinyl, and 4-amino-2-sideoxy-1,2-dihydropyrimidin-1-yl; hydroxyl; cyano; nitro; and alkoxy groups with 1 to 6 carbon atoms such as methoxy, ethoxy, and propoxy. In addition, there can be one or more substituents.

[0090] A is an alkyl group with 1 to 5 carbon atoms. The aforementioned alkyl groups with 1 to 5 carbon atoms are not particularly limited, and examples include methylene (-CH 2-), ethyl alkyl (-C 2H 4-), propyl alkyl (-C 3H 6-), isopropyl alkyl (-CH(CH 3)CH 2-), etc.

[0091] Also, r is either 0 or 1.

[0092] Furthermore, Z can be any of the following formulas.

[0093] [Chemistry 7]

[0094] At this point, one or two hydroxyl groups from the structure derived from monophosphate or diphosphate may also be in anionic form. Specifically, the following structures may also be present.

[0095] [Chemistry 8]

[0096] At this time, in equation (1), there will be a relative ion of ammonium cation in R 1, so sometimes there will be a case where there is no ammonium salt X -.

[0097] As a basis for the expression of equation (2), the following structures can be listed. [Chemistry 9]

[0098] Among these, R1 is preferably an alkyl group having 6 to 20 carbon atoms, a substituted or unsubstituted aryl(poly)oxyalkyl group, more preferably an alkyl group having 8 to 18 carbon atoms, a substituted or unsubstituted phenyl(poly)oxyalkyl group, and even more preferably octyl, decyl, dodecyl, tetradecyl, hexadecyl, octadecyl, phenyloxyethyl (Ph-OC 2H 4-), phenyl di(oxyethyl) (Ph-(OC 2H 4) 2-), p-(1,1,3,3-tetramethylbutyl)phenyl di(oxyethyl) (p-CH 3C(CH 3) 2CH 2C(CH 3) 2-Ph-(OC 2H 4) 2-).

[0099] The aforementioned R2 are each independently an alkyl group with 1 to 18 carbon atoms, substituted or unsubstituted, or an aryl group with 6 to 20 carbon atoms, substituted or unsubstituted.

[0100] Alkyl groups having 1 to 18 carbon atoms are not particularly limited, and examples include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, dibutyl, tributyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl, tetradecyl, hexadecyl, octadecyl, etc.

[0101] Examples of substituents that are alkyl groups with 1 to 18 carbon atoms include: aryl groups with 6 to 20 carbon atoms such as phenyl and naphthyl; alkoxy groups with 1 to 6 carbon atoms such as methoxy, ethoxy, and propoxy; hydroxyl; cyano; and nitro.

[0102] There are no particular restrictions on aryl groups with 6 to 20 carbon atoms; examples include phenyl, naphthyl, and biphenyl.

[0103] Substituents that are aryl groups with 6 to 20 carbon atoms include: alkyl groups with 1 to 10 carbon atoms such as methyl, ethyl, propyl, and isopropyl; alkoxy groups with 1 to 6 carbon atoms such as methoxy, ethoxy, and propoxy; hydroxyl; cyano; and nitro.

[0104] In these embodiments, R2 is preferably an alkyl group of 1 to 18 carbons, substituted or unsubstituted, more preferably methyl, ethyl, propyl, isopropyl, hexyl, octyl, decyl, dodecyl, tetradecyl, hexadecyl, octadecyl, benzyl, hydroxymethyl, 2-hydroxyethyl, more preferably methyl, ethyl, benzyl, 2-hydroxyethyl, especially methyl, benzyl, and most preferably methyl. Furthermore, in another embodiment, R2 is preferably an alkyl group of 1 to 10 carbons substituted with an aryl group of 6 to 20 carbons, more preferably an alkyl group of 1 to 5 carbons substituted with a phenyl group, more preferably benzyl, phenylethyl, and especially preferably benzyl.

[0105] The aforementioned X can be a halide ion (fluoride ion, chloride ion, bromide ion, iodide ion, etc.), hydroxide ion, organic sulfonic acid ion (methanesulfonate ion, p-toluenesulfonate ion, etc.), tetrafluoroborate ion, or hexafluorophosphate ion. Among these, X is preferably a halide ion, and more preferably a chloride ion or bromide ion.

[0106] Specific examples of ammonium salts containing alkyl groups having 5 to 30 carbon atoms include: hexyltrimethylammonium bromide and other hexyl ammonium salts; tetraheptylammonium bromide and other heptyl ammonium salts; octyltrimethylammonium chloride, octyldimethylbenzylammonium chloride and other octyl ammonium salts; decyltrimethylammonium chloride, decyldimethylbenzylammonium chloride and other decyl ammonium salts; dodecyltrimethylammonium chloride, dodecyltrimethylammonium bromide, dodecylethyldimethylammonium chloride, dodecylethyldimethylammonium bromide, benzyldodecyldimethylammonium chloride, benzyldodecyldimethylammonium bromide, tris(dodecyl)methylammonium chloride, tris(dodecyl)methylammonium bromide, etc. Ammonium salts containing dodecyl groups include: tetradecyltrimethylammonium bromide, benzyl dimethyltetradecyl ammonium chloride, etc.; hexadecyltrimethylammonium chloride, hexadecyltrimethylammonium bromide, p-toluenesulfonic acid hexadecyltrimethylammonium, hexadecyltrimethylammonium hydroxide, ethylhexadecyldimethylammonium chloride, ethylhexadecyldimethylammonium bromide, benzyl dimethylhexadecyl ammonium chloride, etc.; and trimethyloctadecylammonium chloride, trimethyloctadecylammonium bromide, dimethyl di(octadecyl)ammonium chloride, dimethyl di(octadecyl)ammonium bromide, benzyl dimethyloctadecyl ammonium chloride, etc., which contain octadecyl groups.

[0107] Specific examples of ammonium salts containing substituted or unsubstituted alkyl (poly)heteroalkyl groups include trimethylpropyl di(oxyethyl)ammonium chloride, trimethylpropyloxyethylthioethylammonium chloride, etc.

[0108] Specific examples of ammonium salts containing substituted or unsubstituted aryl (poly)hexylene groups include benzyl dimethyl-2-{2-[4-(1,1,3,3-tetramethylbutyl)phenoxy]ethoxy}ethyl ammonium chloride (benzethonium chloride), benzyl dimethylphenyl di(oxyethyl) ammonium chloride, etc.

[0109] Specific examples of ammonium salts having the base represented by formula (2) can be listed as the following compounds with the following structures.

[0110] [Chemistry 10]

[0111] The heteroaryl salt having an alkyl group having 5 to 30 carbon atoms is not particularly limited, but can be listed as a heteroaryl cation formed by at least one nitrogen atom of a substituted or unsubstituted heteroaryl ring having a nitrogen atom bonded to an alkyl group having 5 to 30 carbon atoms.

[0112] The aforementioned nitrogen-containing heteroaryl rings are not particularly limited, and may include rings such as imidazole, pyrazole, acetazole, isoxazole, thiazole, isothiazole, pyridine, pyridine, pyrazine, pyrazine, pyrimidine, quinoline, isoquinoline, etc.

[0113] Substituents that are substituents in a nitrogen-containing heteroaryl ring include: alkyl groups with 1 to 4 carbon atoms such as methyl, ethyl, propyl, and isopropyl; aryl groups with 6 to 20 carbon atoms such as phenyl and naphthyl; alkoxy groups with 1 to 6 carbon atoms such as methoxy, ethoxy, and propoxy; hydroxyl; cyano; and nitro.

[0114] Alkyl groups with 5 to 30 carbon atoms are not particularly limited, and examples include pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecanyl, octadecyl, nonadecanyl, and eicosyl.

[0115] Of these, the alkyl group having 5 to 30 carbon atoms is preferably an alkyl group having 6 to 20 carbon atoms, more preferably an alkyl group having 8 to 18 carbon atoms, and even more preferably an octyl, decyl, dodecyl, tetradecyl, hexadecyl, or octadecyl.

[0116] The relative anions of heteroaryl cations having alkyl groups having 5 to 30 carbon atoms are not particularly limited, and examples include: halide ions such as fluoride ions, chloride ions, bromide ions, and iodide ions; hydroxide ions; organic sulfonic acid ions such as methanesulfonate ions and p-toluenesulfonate ions; tetrafluoroborate ions; and hexafluorophosphate ions. Among these, the aforementioned relative anions are preferably halide ions, and more preferably chloride ions or bromide ions.

[0117] Specific examples of heteroaryl salts having alkyl groups having 5 to 30 carbon atoms include: 1-methyl-3-hexylimidazolium chloride, 1-octyl-3-methylimidazolium chloride, 1-octyl-3-methylimidazolium bromide, 1-octyl-3-methylimidazolium tetrafluoroborate, 1-decyl-3-methylimidazolium chloride, 1-decyl-3-methylimidazolium bromide, 1-decyl-3-methylimidazolium tetrafluoroborate, 1-dodecyl-3-methylimidazolium chloride, 1-dodecyl-3-methylimidazolium bromide, and 1-tetradecyl... Imidazolium salts including 3-methylimidazolium chloride, 1-tetradecyl-3-methylimidazolium bromide, 1-hexadecyl-3-methylimidazolium chloride, 1-hexadecyl-3-methylimidazolium bromide, 1-octadecyl-3-methylimidazolium chloride, and 1-octadecyl-3-methylimidazolium bromide; acezolium salts including 3-dodecyl acezolium chloride, 3-dodecyl acezolium bromide, 3-tetradecyl acezolium chloride, and 3-hexadecyl acezolium chloride; and 3-dodecylthiazolyl chloride, 3-dodecylthiazolyl bromide, and acezolium chloride. Thiazolium salts such as 3-dodecyl-4-methylthiazolyl, 3-tetradecylthiazolyl chloride, and 3-hexadecylthiazolyl chloride; pyridinium salts such as 1-hexylpyridinium chloride, 1-octylpyridinium chloride, 1-decylpyridinium chloride, 1-dodecylpyridinium chloride, 1-dodecylpyridinium bromide, 1-tetradecylpyridinium chloride, 1-tetradecylpyridinium bromide, 1-hexadecylpyridinium chloride, 1-hexadecylpyridinium bromide, 1-octadecylpyridinium chloride, and 1-octadecylpyridinium bromide; chlorinated Pyrimidine onion salts such as 1-hexylpyrimidine onion, 1-hexylpyrimidine onion hexafluorophosphate, 1-octylpyrimidine onion chloride, 1-decylpyrimidine onion chloride, 1-dodecylpyrimidine onion chloride, 1-tetradecylpyrimidine onion chloride, and 1-hexadecylpyrimidine onion chloride; quinoline onion salts such as dodecylquinoline onion chloride, dodecylquinoline onion bromide, tetradecylquinoline onion chloride, and hexadecylquinoline onion chloride; and isoquinoline onion salts such as dodecylisoquinoline onion chloride, dodecylisoquinoline onion bromide, tetradecylisoquinoline onion chloride, and hexadecylisoquinoline onion chloride. Furthermore, these can also be used in hydrate form.

[0118] Of these, (C) the tungsten resist, from the viewpoint of high Ti / W etching selectivity, is preferably an ammonium salt represented by formula (1) (here, R1 is an alkyl group with 6 to 20 carbons, R2 is an alkyl group with 1 to 10 carbons, or an alkyl group with 1 to 10 carbons substituted with an aryl group with 6 to 20 carbons), an ammonium salt having substituted or unsubstituted aryl (poly)heteroalkyl groups, or a heteroaryl salt having an alkyl group with 5 to 30 carbons, preferably an ammonium salt represented by formula (1) (here, R1 is an alkyl group with 8 to 20 carbons, R2 is an alkyl group with 6 ... 2 is an alkyl group having 1 to 5 carbon atoms, an alkyl group having 1 to 5 carbon atoms substituted with a phenyl group, an ammonium salt having a substituted or unsubstituted phenyl (poly)oxyalkylene group, or an imidazolium salt having an alkyl group having 8 to 20 carbon atoms; more preferably, it is an octyltrimethylammonium salt, an octyldimethylbenzylammonium salt, a decyltrimethylammonium salt, a decyldimethylbenzylammonium salt, a dodecyltrimethylammonium salt, a dodecyldimethylbenzylammonium salt, a tetradecyltrimethylammonium salt, a tetradecyldimethylbenzylammonium salt, a hexadecyltrimethylammonium salt, a hexadecyldimethylbenzylammonium salt, an octadecyltrimethylammonium salt, an octadecyldimethylbenzylammonium salt, an octyltriethylammonium salt, or an octyl Diethylbenzylammonium salt, decyltriethylammonium salt, decyldiethylbenzylammonium salt, dodecyltriethylammonium salt, dodecyldiethylbenzylammonium salt, tetradecyltriethylammonium salt, tetradecyldiethylbenzylammonium salt, hexadecyltriethylbenzylammonium salt, hexadecyldiethylbenzylammonium salt, octadecyltriethylammonium salt, octadecyldiethylbenzylammonium salt, octylethylmethylbenzylammonium salt, decylethylmethylbenzylammonium salt, dodecylethylmethylbenzylammonium salt, tetradecylethylmethylbenzylammonium salt, hexadecylethylmethylbenzylammonium salt, octadecylethylmethylbenzylammonium salt, trimethyl-2-{2-[4-(1, 1,3,3-Tetramethylbutyl)phenoxy]ethoxy}ethyl ammonium chloride, benzyldimethyl-2-{2-[4-(1,1,3,3-tetramethylbutyl)phenoxy]ethoxy}ethyl ammonium chloride (benzoxonyl chloride), 1-octylimidazolium chloride, 1-decylimidazolium chloride, 1-dodecylimidazolium chloride, 1-tetradecylimidazolium chloride, 1-hexadecylimidazolium chloride, 1-octadecylimidazolium chloride, 1-octyl-3-methylimidazolium chloride, 1-decyl-3-methylimidazolium chloride, 1-dodecyl-3-methylimidazolium chloride, 1-tetradecyl-3-methylimidazolium chloride Azazole, 1-hexadecyl-3-methylimidazolium chloride, 1-octadecyl-3-methylimidazolium chloride, preferably octyl dimethyl benzyl ammonium salt, decyl dimethyl benzyl ammonium salt, dodecyl dimethyl benzyl ammonium salt, tetradecyl dimethyl benzyl ammonium salt, hexadecyl dimethyl benzyl ammonium salt, octadecyl dimethyl benzyl ammonium salt, 1-octyl-3-methylimidazolium chloride, 1-decyl-3-methylimidazolium chloride, 1-dodecyl-3-methylimidazolium chloride, 1-tetradecyl-3-methylimidazolium chloride, 1-hexadecyl-3-methylimidazolium chloride, 1-octadecyl-3-methylimidazolium chloride.

[0119] In addition, the above-mentioned (C) tungsten metal resist can be used alone or in combination of two or more. That is, in a preferred embodiment, (C) the tungsten resist preferably contains at least one selected from the group consisting of an ammonium salt having an alkyl group having 5 to 30 carbon atoms, an ammonium salt having a substituted or unsubstituted aryl (poly)hexaalkyl group, and a heteroaryl salt having an alkyl group having 5 to 30 carbon atoms. From the viewpoint of high Ti / W etch selectivity, it is more preferably to contain at least one selected from the group consisting of an ammonium salt represented by formula (1) (here, R1 is an alkyl group having 6 to 20 carbon atoms, R2 is an alkyl group having 1 to 10 carbon atoms, or an alkyl group having 1 to 10 carbon atoms substituted with an aryl group having 6 to 20 carbon atoms), an ammonium salt having a substituted or unsubstituted phenyl (poly)oxyalkyl group, and a heteroaryl salt having an alkyl group having 5 to 30 carbon atoms. More preferably, it contains an ammonium salt represented by formula (1) (here, R1 is an alkyl group having 8 to 20 carbon atoms, R2 ... 2 is at least one of the group consisting of alkyl groups having 1 to 10 carbon atoms, alkyl groups having 1 to 5 carbon atoms substituted with phenyl groups, and imidazolium salts having 8 to 20 carbon atoms, particularly preferably containing a salt selected from octyltrimethylammonium salt, octyldimethylbenzylammonium salt, decyltrimethylammonium salt, decyldimethylbenzylammonium salt, dodecyltrimethylammonium salt, dodecyldimethylbenzylammonium salt, tetradecyltrimethylammonium salt, tetradecyldimethylbenzylammonium salt, hexadecyltrimethylammonium salt, hexadecyldimethylbenzyl Ammonium salts, octadecyltrimethylammonium salt, octadecyldimethylbenzylammonium salt, octyltriethylammonium salt, octyldiethylbenzylammonium salt, decyltriethylammonium salt, decyldiethylbenzylammonium salt, dodecyltriethylammonium salt, dodecyldiethylbenzylammonium salt, tetradecyltriethylammonium salt, tetradecyldiethylbenzylammonium salt, hexadecyltriethylammonium salt, hexadecyldiethylbenzylammonium salt, octadecyltriethylammonium salt, octadecyldiethylbenzylammonium salt, octylethylmethylbenzylammonium salt, decylethyl Methylbenzylammonium salt, dodecylethylmethylbenzylammonium salt, tetradecylethylmethylbenzylammonium salt, hexadecylethylmethylbenzylammonium salt, octadecylethylmethylbenzylammonium salt, trimethyl-2-{2-[4-(1,1,3,3-tetramethylbutyl)phenoxy]ethoxy}ethylammonium chloride, benzyldimethyl-2-{2-[4-(1,1,3,3-tetramethylbutyl)phenoxy]ethoxy}ethylammonium chloride (benzoxonine chloride), 1-octylimidazolium chloride, 1- At least one of the group consisting of decylimidazolium, 1-dodecylimidazolium chloride, 1-tetradecylimidazolium chloride, 1-hexadecylimidazolium chloride, 1-octadecylimidazolium chloride, 1-octyl-3-methylimidazolium chloride, 1-decyl-3-methylimidazolium chloride, 1-dodecyl-3-methylimidazolium chloride, 1-tetradecyl-3-methylimidazolium chloride, 1-hexadecyl-3-methylimidazolium chloride, and 1-octadecyl-3-methylimidazolium chloride.Preferably, it contains at least one salt selected from the group consisting of octyl dimethyl benzyl ammonium salt, decyl dimethyl benzyl ammonium salt, dodecyl dimethyl benzyl ammonium salt, tetradecyl dimethyl benzyl ammonium salt, hexadecyl dimethyl benzyl ammonium salt, octadecyl dimethyl benzyl ammonium salt, 1-octyl-3-methylimidazolium chloride, 1-decyl-3-methylimidazolium chloride, 1-dodecyl-3-methylimidazolium chloride, 1-tetradecyl-3-methylimidazolium chloride, 1-hexadecyl-3-methylimidazolium chloride, and 1-octadecyl-3-methylimidazolium chloride.

[0120] (C) The addition ratio of tungsten metal resist relative to the total mass of the aforementioned etchant is preferably 0.0001 to 5% by mass, more preferably 0.001 to 1% by mass, even more preferably 0.003 to 0.5% by mass, and particularly preferably 0.004 to 0.08% by mass.

[0121] pH adjuster The etchant may also contain a pH adjuster if necessary. As such a pH adjuster, for example, acids or bases other than (A) oxidants and (B) fluorine compounds can be used.

[0122] Examples of the aforementioned acids include hydrogen chloride, hydrogen bromide, hydrogen iodide, sulfuric acid, nitric acid, methanesulfonic acid, trifluoromethanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, 10-camphorsulfonic acid, and their salts. Examples of the aforementioned salts include ammonium salts such as ammonium chloride, ammonium bromide, ammonium iodide, ammonium sulfate, and ammonium nitrate; and alkyl ammonium salts such as methylamine hydrochloride, dimethylamine hydrochloride, dimethylamine hydrobromide, and methylamine sulfate.

[0123] Examples of alkalis mentioned above include lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, beryllium hydroxide, magnesium hydroxide, calcium hydroxide, strontium hydroxide, barium hydroxide, ammonia, and triethylamine.

[0124] Among the above, the pH adjuster should preferably be hydrogen chloride, hydrogen bromide, hydrogen iodide, sulfuric acid, nitric acid, methanesulfonic acid, or ammonia, with sulfuric acid, nitric acid, or ammonia being more preferred, and sulfuric acid or nitric acid being even more desirable.

[0125] solvent The etchant should preferably contain a solvent. The aforementioned solvent has the functions of uniformly dispersing the various components contained in the etchant and diluting it.

[0126] Examples of solvents mentioned above include water and organic solvents.

[0127] The aforementioned water is not particularly limited, but should be water obtained by removing metal ions, organic impurities, and particulate matter through distillation, ion exchange, filtration, or various adsorption treatments. It should be pure water, and especially ultrapure water.

[0128] The aforementioned organic solvents are not particularly limited and may include: methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, tributanol, etc.; ethylene glycol, propylene glycol, neopentyl glycol, 1,2-hexanediol, 1,6-hexanediol, 2-ethylhexane-1,3-diol, glycerol, etc.; diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, dipropylene glycol monomethyl ether, tripropylene glycol monomethyl ether, dipropylene glycol dimethyl ether, dipropylene glycol monoethyl ether, propylene glycol n-propyl ether, dipropylene glycol n-propyl ether, tripropylene glycol n-propyl ether, propylene glycol n-butyl ether, dipropylene glycol n-butyl ether, tripropylene glycol n-butyl ether, propylene glycol phenyl ether, etc.

[0129] Of the above, water is preferred as the solvent. Furthermore, the aforementioned solvents can be used alone or in combination of two or more.

[0130] Regarding the addition ratio of solvent, especially water, it should be 50% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more, and most preferably 90 to 99.5% by mass relative to the total mass of the etchant.

[0131] Iodine scavenging agent When the oxidant in (A) above contains an oxyacid with iodine, the etchant should preferably contain an iodine scavenger.

[0132] Iodine-scavenging agents are not particularly limited and can include: acetone, butanone, 2-methyl-2-butanone, 3,3-dimethyl-2-butanone, 4-hydroxy-2-butanone, 2-pentanone, 3-pentanone, 3-methyl-2-pentanone, 4-methyl-2-pentanone, 2-methyl-3-pentanone, 5-methyl-3-pentanone, 2,4-dimethyl-3-pentanone, 5-hydroxy-2-pentanone, 4-hydroxy-4-methyl-2-pentanone, 2-hexanone, 3-hexanone, 2- Aliphatic ketones include heptanone, 3-heptanone, 4-heptanone, 5-methyl-2-heptanone, 5-methyl-3-heptanone, 2,6-dimethyl-4-heptanone, 2-octanone, 3-octanone, 4-octanone, cyclohexanone, 2,6-dimethylcyclohexanone, 2-acetylated cyclohexanone, menthone, cyclopentanone, and dicyclohexyl ketone; aliphatic diketones include 2,5-hexanedione, 2,4-pentanedione, and acetylated acetone; and aromatic ketones include acetophenone, 1-phenylethylone, and diphenylone. Among these, the iodine scavenging agent is preferably an aliphatic ketone, more preferably 4-methyl-2-pentanone, 5-methyl-3-pentanone, 2,4-dimethyl-3-pentanone, or cyclohexanone, and even more preferably 4-methyl-2-pentanone. Furthermore, these iodine scavenging agents can be used alone or in combination of two or more.

[0133] Low dielectric constant passivating agent The etchant may also contain a low-dielectric-constant passivating agent. Low-dielectric-constant passivating agents prevent or inhibit the etching of low-dielectric-constant films, such as insulating films.

[0134] Low dielectric constant passivating agents are not particularly limited, and examples include: boric acid; borates such as ammonium pentaborate and sodium tetraborate; and carboxylic acids such as 3-hydroxy-2-naphthoic acid, malonic acid, and iminodiacetic acid.

[0135] These low dielectric constant passivating agents can be used alone or in combination of two or more.

[0136] The addition ratio of the low dielectric constant passivator relative to the total mass of the aforementioned etchant is preferably 0.01 to 2% by mass, more preferably 0.02 to 1% by mass, and even more preferably 0.03 to 0.5% by mass.

[0137] additive Etching agents may also contain additives. Examples of such additives include surfactants, chelating agents, defoamers, and silicone compounds.

[0138] Physical properties of etchants The pH of the etchant should be 0.5~5.0, preferably 1.0~4.0, and even more preferably 1.0~3.0.

[0139] The etching rate of the tungsten metal in the etchant should preferably be below 5.0 Å / min, more preferably below 3.0 Å / min, even more preferably below 2.0 Å / min, particularly preferably below 1.5 Å / min, and most preferably 0.1~1.0 Å / min. A tungsten etching rate of below 5.0 Å / min improves the Ti / W etch selectivity, which is therefore desirable. Furthermore, the tungsten etching rate in the etchant refers to the value measured by the method described in the examples.

[0140] The etching rate of the titanium or titanium alloy etchant should preferably be 10 Å / min or higher, more preferably 30 Å / min or higher, even more preferably 50 Å / min or higher, and most preferably 80 Å / min or higher. An etching rate of 10 Å / min or higher for titanium or titanium alloys improves the Ti / W etching selectivity, which is therefore desirable. Furthermore, the etching rate of the titanium or titanium alloy etchant refers to the value measured by the method described in the examples.

[0141] The etching rate of the insulating layer material in the etchant should preferably be 5.0 Å / min or less, more preferably 3.0 Å / min or less, even more preferably 2.0 Å / min or less, particularly preferably 1.5 Å / min or less, and most preferably 1.0 Å / min or less. An etching rate of 5.0 Å / min or less for the insulating layer material is ideal because it maintains the shape of the semiconductor substrate and improves the performance of the semiconductor device. Furthermore, the etching rate of the insulating layer material in the etchant refers to the value measured by the method described in the embodiments.

[0142] The Ti / W etch selectivity ratio (etching rate of titanium and titanium alloys / etching rate of tungsten) of the etchant should preferably be 10 or higher, more preferably 30 or higher, even better 35 or higher, exceptionally good 70 or higher, and ideally 100 or higher. A Ti / W etch selectivity ratio of 10 or higher is ideal for manufacturing high-performance semiconductor substrates for memory components.

[0143] (touch) Regarding the contact method between the semiconductor substrate and the etchant after step (1), there are no particular limitations, and known techniques can be appropriately used. Specifically, the semiconductor substrate can be immersed in the etchant, or the etchant can be sprayed onto the semiconductor substrate, or it can be dropped (single-wafer rotation processing, etc.). At this time, the aforementioned immersion can be repeated more than twice, the spraying can be repeated more than twice, the dropping can be repeated more than twice, or immersion, spraying, and dropping can be combined.

[0144] There are no particular restrictions on the contact temperature, but it is advisable to be 0~90℃, preferably 15~70℃, and even more preferably 20~60℃.

[0145] There is no particular limitation on the contact time, but it is advisable to be 10 seconds to 3 hours, preferably 30 seconds to 1 hour, even better 1 to 45 minutes, and ideally 1 to 5 minutes.

[0146] Selective etching of titanium and titanium alloys can be performed by contacting the semiconductor substrate after step (1) with an etchant. At this time, since at least a portion of the tungsten oxide film has been removed in step (1), selective etching of titanium and titanium alloys using the etchant will be more ideal.

[0147] (Semiconductor substrate for memory components) The semiconductor substrate for memory devices obtained by step (2) can be used in memory devices such as DRAM. The memory devices obtained by step (2) can be miniaturized and highly functional.

[0148] <Set> According to one aspect of the present invention, a kit is provided. The kit contains the aforementioned pretreatment agent and the aforementioned etchant. That is, the kit can be used for manufacturing semiconductor substrates for memory devices. By making the pretreatment agent and etchant into a kit, it is helpful to perform the above steps (1) and (2) when selectively etching titanium or titanium alloys onto a semiconductor substrate having a tungsten oxide film. [Example]

[0149] The present invention will be specifically described below with examples, but the present invention is not limited thereto.

[0150] [Example 1] (Step (1)) Prepare a substrate with a tungsten oxide (WO3) film, a substrate with a tungsten metal (W) film, a substrate with a titanium nitride (TiN) film, and a substrate with a silicon oxide (th-Ox) film. Perform step (1) on each substrate and measure the etching rate of each film by the pretreatment agent.

[0151] Preparation of the pretreatment agent. Specifically, hydrogen fluoride (HF), used as a WO3 etchant, was added to pure water and stirred to prepare the pretreatment agent. The addition ratio of the aforementioned hydrogen fluoride was 0.1% by mass relative to the total mass of the pretreatment agent. Furthermore, the pH of the pretreatment agent was 2.2. The pH was determined by measuring the pH of the pretreatment agent at 23°C using a benchtop pH meter (F-71) and pH electrode (9615S-10D) manufactured by Horiba Manufacturing Co., Ltd.

[0152] (1-A) Treatment of substrates with tungsten oxide (WO3) film Tungsten oxide (WO3) films with a thickness of 3000 Å were deposited on silicon wafers using physical vapor deposition and then cut into 1 cm × 1 cm (immersion treatment area: 1 cm 2) sizes to obtain tungsten oxide film samples.

[0153] The tungsten oxide film sample was immersed in 10g of the prepared pretreatment agent at a predetermined processing temperature for 5 minutes. The pretreatment agent was then diluted 10-20 times with 1% (w / w) nitric acid aqueous solution to obtain the test sample. The tungsten concentration in the test sample was measured using an ICP emission spectrometer (ICP-OES) namely an Avio200 (manufactured by PerkinElmer).

[0154] At this time, the samples for the calibration curve are prepared by the following method. That is, the tungsten standard solution (tungsten concentration: 1000 ppm, manufactured by Fujifilm and Hikvision) is diluted with 1% by mass nitric acid aqueous solution to obtain calibration curve samples with tungsten concentrations of 25 ppb, 12.5 ppb and 2.5 ppb.

[0155] The tungsten concentration before dilution is calculated from the tungsten concentration of the test sample obtained by using the calibration line. The tungsten concentration before dilution and the amount of pretreatment agent used in the test (the amount of the test sample before dilution) are then substituted into the following formula to calculate the etching amount of the tungsten oxide film.

[0156] [Number 1]

[0157] In addition, in the above formula, 231.84 (g / mol) is the molecular weight of tungsten oxide (WO3), 7.16 (g / cm3) is the density of tungsten oxide, 1cm2 is the immersion treatment area of ​​the tungsten oxide film sample, and 183.84 (g / mol) is the molecular weight of metallic tungsten (W).

[0158] The etch rate (ER) of the tungsten oxide film was calculated by dividing the calculated etching amount by the immersion time using the pretreatment agent. The ER of the tungsten oxide film was found to be 31 Å / min.

[0159] (1-B) Processing of substrates with tungsten (W) film Tungsten (W) films with a thickness of 1000 Å were deposited on silicon wafers using physical vapor deposition and then cut into 1 cm × 1 cm (immersion treatment area: 1 cm 2) sizes to obtain metallic tungsten film samples.

[0160] Except for using tungsten metal film samples and immersion time of 2 minutes, the test samples were prepared using the same method as the etching rate determination method for tungsten oxide films, and the tungsten concentration in the test samples was determined.

[0161] The tungsten concentration before dilution is calculated from the tungsten concentration of the test sample obtained by using the calibration line, and the tungsten concentration before dilution and the amount of pretreatment agent used in the test (the amount of the test sample before dilution) are substituted into the following formula to calculate the etching amount of the tungsten film.

[0162] [Number 2]

[0163] In addition, 19.25 (g / cm 3) in the above formula is the density of metallic tungsten, and 1 cm 2 is the immersion treatment area of ​​the tungsten film sample.

[0164] The etch rate (ER) of the tungsten film was calculated by dividing the calculated etching amount by the immersion time using the pretreatment agent. The ER of the tungsten film was found to be 2.5 Å / min.

[0165] (1-C) Treatment of substrates with titanium nitride (TiN) films Titanium nitride (TiN) films with a thickness of 1000 Å were deposited on silicon wafers using physical vapor deposition and then cut into 2 cm × 2 cm (immersion treatment area: 4 cm 2) sizes to obtain titanium nitride film samples.

[0166] The thickness of titanium nitride films was determined using a fluorescence X-ray apparatus EA1200VX (manufactured by Hitachi High-Tech).

[0167] The titanium nitride film sample was immersed in 10g of the prepared pretreatment agent at a predetermined treatment temperature for 5 minutes.

[0168] The film thickness of the titanium nitride film sample after impregnation with the pretreatment agent was determined using the same method as described above.

[0169] The difference in film thickness between the titanium nitride film samples before and after the pretreatment agent impregnation was calculated, and then divided by the impregnation time using the pretreatment agent to calculate the etching rate (ER) of the titanium nitride film. The ER of the titanium nitride film obtained by the pretreatment agent was found to be 5 Å / min.

[0170] (1-D) Processing of substrates with silicon oxide (th-Ox) films Silicon oxide films with a thickness of 1000 Å are formed by thermal oxidation of silicon wafers and then cut into 1 cm × 1 cm (immersion treatment area: 1 cm 2) sizes to obtain silicon oxide film samples.

[0171] The thickness of silicon oxide film samples was measured using an optical thickness gauge, n&k1280 (manufactured by n&k Technologies).

[0172] The silicon oxide film sample was immersed in 10g of the prepared pretreatment agent at a predetermined treatment temperature for 30 minutes.

[0173] The film thickness of the silicon oxide film sample after impregnation was determined using the same method as described above.

[0174] The difference in film thickness between the silicon oxide film samples before and after treatment was calculated, and then divided by the time of immersion treatment with the pretreatment agent to calculate the etching rate (ER) of the silicon oxide film. The ER of the silicon oxide film treated with the pretreatment agent was found to be 2.8 Å / min.

[0175] (1-E) Calculate the WO 3 / W etching selectivity ratio The WO3 / W etch selectivity was calculated by dividing the etch rate (ER) of the pretreatment agent on the tungsten oxide film by the etch rate (ER) of the pretreatment agent on the tungsten metal film. The result was a WO3 / W etch selectivity of 12.

[0176] (Step (2)) Step (2) was performed on a substrate with a tungsten (W) film, a substrate with a titanium nitride (TiN) film, and a substrate with a silicon oxide (th-Ox) film, and the etching rate of the etchant on each film was measured. Furthermore, for the substrate with a titanium nitride (TiN) film, a titanium nitride film sample prepared in step (1) was used. Also, for the substrate with a tungsten (W) film and the substrate with a silicon oxide (th-Ox) film, newly prepared tungsten film samples and silicon oxide film samples were used using the same method as in step (1).

[0177] An etchant was prepared. Specifically, iodic acid (HIO3) as an oxidant, hydrogen fluoride (HF) as a fluorine compound, and 1-dodecylpyridinium chloride (DPC) as a tungsten metal resist were added to pure water and stirred to obtain the etchant. The addition ratios of iodic acid, hydrogen fluoride, and 1-dodecylpyridinium chloride (DPC) relative to the total mass of the etchant were 0.018%, 0.05%, and 0.005% by mass, respectively. Furthermore, the pH of the etchant was 2.4.

[0178] (2-A) Processing of substrates with tungsten (W) films The tungsten film sample was immersed in 10g of the prepared etchant at a predetermined processing temperature for 2 minutes. Then, the etching rate (ER) of the tungsten film was calculated using the same method as described in (1-B) above. The etchant ER of the tungsten film was found to be 2.1 Å / min.

[0179] (2-B) Treatment of the substrate with titanium nitride (TiN) film after step (1) The titanium nitride film sample prepared in step (1) was immersed in 10g of the prepared etchant at a predetermined processing temperature for 2 minutes. Then, the etching rate (ER) of the titanium nitride film was calculated using the same method as described in (1-C). As a result, the etching rate (ER) of the titanium nitride film by the etchant was 85 Å / min.

[0180] (2-C) Processing of substrates with silicon oxide (th-Ox) films The silicon oxide film sample was immersed in 10g of the prepared etchant at a predetermined processing temperature for 30 minutes. Then, the etching rate (ER) of the silicon oxide film was calculated using the same method as described in (1-D). The etchant ER of the silicon oxide film was found to be 0.8 Å / min.

[0181] (2-D)TiN / W Etching Selectivity The TiN / W etch selectivity was calculated by dividing the etch rate (ER) of the titanium nitride film by the etch rate (ER) of the tungsten film. The result was a TiN / W etch selectivity of 40.

[0182] [evaluate] The corrosion potential difference between tungsten (W) and titanium nitride (TiN) and the titanium oxide removal capacity were evaluated for the pretreatment agent.

[0183] (Corrosion potential difference between tungsten (W) and titanium nitride (TiN)) The corrosion potential of metallic tungsten (W) was determined using the following method: linear sweep voltammetry was performed using a Beidou Electric HZ7000 voltammeter. Specifically, a tungsten film immersed in 0.5% ammonia solution at 23°C for 1 minute was used as the working electrode; platinum was used as the relative electrode; silver / silver chloride (3.3M potassium chloride aqueous solution) was used as the reference electrode; and a salt bridge (carrageenan containing 0.5M potassium chloride) was used for measurement. Potentials were applied to the metallic tungsten at a rate of 2 mV / s from 30 mV to 200 mV lower than the corrosion potential, and the current values ​​at each potential were plotted (Tafel plot). The potential at which the current value is lowest was defined as the corrosion potential of the metallic tungsten. As a result, the corrosion potential of metallic tungsten (W) was -109 mV.

[0184] Furthermore, the corrosion potential of titanium nitride (TiN) was measured using the following method. Specifically, a linear sweep voltammetry method was performed using a Beidou Electric HZ7000 voltammeter. The method involved using a titanium nitride film immersed in a 1% (w / w) aqueous solution of hydrogen fluoride at 23°C for 1 minute as the working electrode, platinum as the relative electrode, silver / silver chloride (3.3M potassium chloride aqueous solution) as the reference electrode, and a salt bridge (carrageenan containing 0.5M potassium chloride) as the reference electrode. Potentials were applied to the titanium nitride at a rate of 2 mV / s from potentials 30 mV to 200 mV lower than the corrosion potential, and the current values ​​at each potential were plotted (Tafel plot). The potential at which the current value was lowest was defined as the corrosion potential of the titanium nitride. The corrosion potential of titanium nitride (TiN) was found to be -73 mV.

[0185] Then, the corrosion potential difference between tungsten (W) and titanium nitride (TiN) was calculated (corrosion potential of W - corrosion potential of TiN), and the result was 36mV.

[0186] (Titanium oxide removal capacity) Titanium nitride (TiN) films with a thickness of 1000 Å were deposited on silicon wafers using physical vapor deposition and cut into 2 cm × 2 cm (immersion treatment area: 4 cm²). The films were then exposed to air at 20°C for 30 days to oxidize the surface of the titanium nitride films, thus obtaining samples for titanium oxide removal capacity testing.

[0187] The titanium oxide removal capacity test sample was immersed in 10 g of the pretreatment agent (0.1% HF aqueous solution) prepared in step (1) at 30°C for 5 minutes to obtain the pretreated sample. Then, using the etchant prepared in step (2), the etching rate (ER) of the titanium nitride film was calculated in the same way as in (2-B), and the result was 85 Å / min. Furthermore, the higher the etching rate (ER) of the titanium nitride film, the more effectively the titanium oxide film can be removed in step (1) using the pretreatment agent.

[0188] [Examples 1-2~1-10] The pretreatment agent was prepared by changing the added ingredients as shown in Table 1 below. The composition of the pretreatment agent and the composition of Example 1 are shown together in Table 1 below.

[0189] [Table 1]

[0190] Furthermore, step (1) was performed in the same manner as in Example 1. The etching rates (ER) of the tungsten oxide (W) film, metallic tungsten (W) film, titanium nitride (TiN) film, and silicon oxide film; the WO3 / W etch selectivity ratio; the corrosion potential of metallic tungsten (W), the corrosion potential of titanium nitride (TiN), and the corrosion potential difference between metallic tungsten (W) and titanium nitride (TiN); and the results of the titanium oxide removal capacity measurements, along with the results of Example 1, are shown in Table 2 below. In addition, the etchant used in the measurement of titanium oxide removal capacity was the same etchant used in Example 1.

[0191] [Table 2]

[0192] As shown in Table 2, Examples 1 and 1-2 to 1-10 all exhibit high etching rates (ER) for WO3. Therefore, Examples 1 and 1-2 to 1-10 do not reduce throughput and can prevent etching of the tungsten metal during pretreatment. Thus, by using the semiconductor substrate obtained in step (1) to perform step (2), high-performance semiconductor substrates for memory devices can be manufactured with high production efficiency.

[0193] [Examples 2-2~2-10] The etchant was prepared by changing the added components as shown in Table 3 below. The composition of the etchant and the composition of the etchant in Example 1 are shown together in Table 3 below.

[0194] [Table 3]

[0195] Furthermore, the DPC, CPC, DMIC, CTAB, OMIC, and BZC used in the embodiments have the following structures.

[0196] [Chemistry 11]

[0197] Step (2) was performed on a substrate having a tungsten (W) film, a titanium nitride (TiN) film, and a silicon oxide (th-Ox) film, similar to Example 1. Furthermore, for the substrate having a titanium nitride (TiN) film, the titanium nitride film sample prepared in step (1) was used. Also, for the substrate having a tungsten (W) film and the substrate having a silicon oxide (th-Ox) film, newly prepared tungsten film and silicon oxide film samples were used using the same method as in step (1). The etching rates (ER) of the tungsten (W) film, titanium nitride (TiN) film, and silicon oxide film, as well as the TiN / W etch selectivity ratio, are shown in Table 4 below, along with the results from Example 1.

[0198] [Table 4]

[0199] As can be seen from the results in Table 4, in Examples 1 and 2-2 to 2-10, tungsten oxide was efficiently removed in step (1), so titanium nitride could be selectively etched in step (2), and semiconductor substrates for high-function memory devices could be manufactured with high production efficiency.

[0200] 10: Semiconductor substrate (before step (1)) 11: Silicon substrate with recesses 12: Insulating film 13: Barrier membrane 14: Tungsten metal film 15: Tungsten oxide film 16: Titanium oxide film 20: Semiconductor substrate (after step (1)) 21: Silicon substrate with recesses 22: Insulating film 23: Barrier membrane 24: Tungsten metal film 30: Semiconductor substrate (after step (2)) 31: Silicon substrate with recesses 32: Insulating film 33: Barrier film after etching 34: Tungsten film

Claims

1. A method for manufacturing a semiconductor substrate for memory devices, comprising the following steps: Step (1), contacting a semiconductor substrate having at least one of titanium and titanium alloys, a titanium oxide film, a tungsten metal film, and a tungsten oxide film with a pretreatment agent to remove at least a portion of the tungsten oxide film and at least a portion of the titanium oxide film; and Step (2), contacting the semiconductor substrate after Step (1) with an etchant to remove at least a portion of the titanium oxide film; wherein the pretreatment agent contains a tungsten oxide etchant selected from at least one of the group consisting of acids, ammonia, and ammonium salts.

2. A method for manufacturing a semiconductor substrate for a memory element as described in claim 1, wherein, The etchant contains (A) an oxidant, (B) a fluorine compound, and (C) a tungsten resist. The addition ratio of (A) the oxidant is 0.0001 to 10% by mass relative to the total mass of the etchant. The addition ratio of (B) the fluorine compound is 0.005 to 10% by mass relative to the total mass of the etchant. The addition ratio of (C) the tungsten resist is 0.0001 to 5% by mass relative to the total mass of the etchant.

3. A method for manufacturing a semiconductor substrate for memory elements, comprising the following steps: Step (1), contacting a semiconductor substrate having a titanium-containing film, a tungsten film, and a tungsten oxide film containing at least one of titanium and titanium alloys with a pretreatment agent to remove at least a portion of the tungsten oxide film; and Step (2), contacting the semiconductor substrate after Step (1) with an etchant to remove at least a portion of the titanium-containing film; The pretreatment agent contains a tungsten oxide etchant selected from at least one of the group consisting of acids, ammonia, and ammonium salts, the etchant containing (A) an oxidant, (B) a fluorine compound, and (C) a tungsten resist, the addition ratio of the (A) oxidant being 0.0001 to 10% by mass relative to the total mass of the etchant, the addition ratio of the (B) fluorine compound being 0.005 to 10% by mass relative to the total mass of the etchant, and the addition ratio of the (C) tungsten resist being 0.0001 to 5% by mass relative to the total mass of the etchant.

4. A method for manufacturing a semiconductor substrate for a memory element as described in any of claims 1 to 3, wherein, The pH of the pretreatment agent is 0.1~13.

5. A method for manufacturing a semiconductor substrate for a memory element as described in any of claims 1 to 3, wherein, The tungsten oxide etchant contains at least one of the group consisting of hydrogen fluoride, hydrogen chloride, hydrogen bromide, hydrogen iodide, sulfuric acid, nitric acid, and phosphoric acid.

6. A method for manufacturing a semiconductor substrate for memory elements as described in claim 2 or 3, wherein, The oxidizing agent (A) contains at least one selected from the group consisting of peroxy acids, halogenated oxyacids, and salts thereof.

7. A method for manufacturing a semiconductor substrate for memory elements as described in claim 2 or 3, wherein, The (B) fluorine compound contains at least one selected from the group consisting of hydrogen fluoride (HF), tetrafluoroboric acid (HBF4), hexafluorosilicic acid (H2SiF6), hexafluorozirconic acid (H2ZrF6), hexafluorotitanic acid (H2TiF6), hexafluorophosphate (HPF6), hexafluoroaluminic acid (H2AlF6), hexafluorogermanic acid (H2GeF6), and salts thereof.

8. A method for manufacturing a semiconductor substrate for memory elements as described in claim 2 or 3, wherein, The (C) tungsten metal resist contains at least one of the following groups: an ammonium salt represented by the following formula (1) and a heteroaryl salt having an alkyl group having 5 to 30 carbon atoms; in the above formula (1), R1 is an alkyl group having 5 to 30 carbon atoms, a substituted or unsubstituted alkyl (poly)heteroalkyl group, a substituted or unsubstituted aryl (poly)heteroalkyl group, or a group represented by the following formula (2); in the above formula, Cy is a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted heterocycloalkyl group having 2 to 10 carbon atoms, a substituted or unsubstituted aryl group having 6 to 15 carbon atoms, or a substituted or unsubstituted heteroaryl group having 2 to 15 carbon atoms, A is an alkyl group having 1 to 5 carbon atoms, r is 0 or 1, Z is any of the following formulas; R2 is an substituted or unsubstituted alkyl group having 1 to 18 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 20 carbon atoms. X represents halide ions, hydroxide ions, organic sulfonic acid ions, tetrafluoroborate ions, and hexafluorophosphate ions.

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