Cleaning liquid for removing dry etching residue and method for manufacturing semiconductor substrate using the same

Abstract

According to the present invention, there can be provided a cleaning liquid comprising: 0.2 to 20% by mass of an amine compound (A), 40 to 70% by mass of a water-soluble organic solvent (B), and water, wherein the amine compound (A) comprises one or more selected from the group consisting of n-butylamine, hexylamine, octylamine, 1,4-butanediamine, dibutylamine, 3-amino-1-propanol, N,N-diethyl-1,3-diaminopropane, and bis(hexamethylene)triamine, and the viscosity of the water-soluble organic solvent (B) at 20° C. is 10 mPa·s or less, and the pH of the cleaning liquid is in the range of 9.0 to 14.

Description

Technical Field

[0001] The present invention relates to a cleaning liquid for suppressing damage to a metal wiring layer and an interlayer insulating film containing cobalt and removing dry etching residues and a dry etching stop layer on a processed surface in a manufacturing process of a semiconductor substrate, and a manufacturing method of a semiconductor substrate using the cleaning liquid. Background Art

[0002] The manufacturing process of semiconductor substrates includes a dry etching process, which includes a process of selectively removing a specific material relative to other materials. At this time, the dissolved residues of etching, metal slag, etc., which are called dry etching residues, remain on the surface after the etching process, and a cleaning liquid is used to remove them.

[0003] In recent years, copper is used as a wiring material in semiconductor substrates, and a low dielectric constant film (hereinafter referred to as "Low-k film") is used as an interlayer insulating film. However, as the miniaturization of wiring progresses, electromigration becomes more likely to occur, and the problem of reduced reliability of copper wiring has attracted attention. Therefore, cobalt is advocated as an alternative material for improving electromigration resistance. On the other hand, when dry etching is performed on a substrate containing the wiring material, organic and silicon dry etching residues remain on the surface of the processed substrate. In addition, in order to prevent damage to the wiring material caused by dry etching, the semiconductor substrate sometimes includes a dry etching barrier layer such as aluminum oxide.

[0004] Therefore, a cleaning technology is required to prevent the wiring material and interlayer insulation film of the substrate from corroding and remove the dry etching residue and the dry etching stop layer. Furthermore, it is necessary to suppress the side etching of the dry etching stop layer such as aluminum oxide, which is an undesirable phenomenon in the film forming process after cleaning.

[0005] In order to weaken the dry etching residue, a redox agent is sometimes used in the cleaning solution. However, the redox agent has problems such as inducing decomposition of components in the cleaning solution, resulting in performance degradation, and changes in the material of the substrate surface.

[0006] In addition, in order to prevent the wiring material from being damaged, an anticorrosive agent is sometimes used. The anticorrosive agent adsorbed on the wiring material surface needs to be removed so that the film forming process after cleaning does not cause any adverse conditions. Nitrogen-containing heterocyclic compounds are representative anticorrosive agents for cobalt, and are not easily removed from the wiring material surface using conventional cleaning solutions.

[0007] For cleaning liquids for substrates containing cobalt wiring materials, there is a known method of using a chemical solution containing a hydroxylamine compound, a nitrogen-containing compound of a specific structure, an organic solvent, and water for cleaning (Patent Document 1). However, in order to dissolve the residue, a hydroxylamine compound is used as a reducing agent. In addition, if a nitrogen-containing heterocyclic compound is not added as an anticorrosive agent, damage to cobalt cannot be fully suppressed.

[0008] As for the cleaning liquid for substrates containing cobalt wiring materials, there is a known technique of using a chemical solution containing an alkali metal compound, a peroxide, an alkaline earth metal and water for cleaning (Patent Document 2). However, in order to dissolve the dry etching residue, peroxide is used as an oxidant, and if an anticorrosive agent is not added, damage to cobalt cannot be suppressed.

[0009] Prior art literature

[0010] Patent Literature

[0011] Patent Document 1: International Publication No. 2017-119350

[0012] Patent Document 2: International Publication No. 2016-076033 Summary of the invention

[0013] Problem that the invention aims to solve

[0014] The present invention aims to provide a cleaning liquid that can prevent the corrosion of metal wiring layers and interlayer insulating films containing cobalt and remove dry etching residues and dry etching stop layers, which are difficult to deal with by conventional methods, and a method for manufacturing a semiconductor substrate containing cobalt using the cleaning liquid.

[0015] Solutions for solving problems

[0016] The present inventors have conducted intensive studies and have found that the above-mentioned problems can be solved by using a cleaning liquid containing a specific amine compound (A), a water-soluble organic solvent (B) and water.

[0017] That is, the present invention is as follows.

[0018] <1> A cleaning solution comprising: 0.2 to 20% by mass of an amine compound (A), 40 to 70% by mass of a water-soluble organic solvent (B), and water.

[0019] The amine compound (A) contains one or more selected from the group consisting of n-butylamine, hexylamine, octylamine, 1,4-butanediamine, dibutylamine, 3-amino-1-propanol, N,N-diethyl-1,3-diaminopropane, and bis(hexamethylene)triamine, the viscosity of the water-soluble organic solvent (B) at 20° C. is 10 mPa·s or less, and the pH of the cleaning liquid is in the range of 9.0 to 14.

[0020] <2> For the above <1> The cleaning liquid, wherein the content of the amine compound (A) is 0.2 to 4.0% by mass.

[0021] <3> For the above <1> or <2> The cleaning liquid, wherein the content of the water is 28 to 59% by mass.

[0022] <4> For the above <1> ~ <3> The cleaning solution described above, wherein the water-soluble organic solvent (B) contains one or more selected from the group consisting of diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, dipropylene glycol monomethyl ether, and N,N-dimethylisobutyramide.

[0023] <5> For the above <1> ~ <4> The cleaning liquid described above, wherein the amine compound (A) contains one or more selected from the group consisting of 3-amino-1-propanol, N,N-diethyl-1,3-diaminopropane, and bis(hexamethylene)triamine.

[0024] <6> For the above <1> ~ <5> The cleaning solution described in any one of the above is used to remove dry etching residues.

[0025] <7> A method for manufacturing a semiconductor substrate, comprising using the above <1> ~ <6> A step of cleaning a semiconductor substrate containing cobalt using any one of the cleaning solutions.

[0026] <8> For the above <7> The method for manufacturing a semiconductor substrate, wherein the semiconductor substrate comprises: a metal wiring layer containing cobalt, an interlayer insulating film, and a dry etching stop layer containing aluminum oxide.

[0027] Effects of the Invention

[0028] According to the present invention, there can be provided: a cleaning liquid which can suppress damage to a metal wiring layer and an interlayer insulating film containing cobalt and can selectively remove dry etching residues and a dry etching stop layer on the surface of a substrate during the manufacturing process of a semiconductor substrate, and a method for manufacturing a semiconductor substrate using the cleaning liquid. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 FIG. 1 is a schematic cross-sectional view showing an example of a semiconductor substrate containing cobalt before removal of dry etching residue. DETAILED DESCRIPTION

[0030] The cleaning liquid of the present invention contains a specific amine compound (A), a water-soluble organic solvent (B), and water. These will be described in detail below.

[0031] [Amine compound (A)]

[0032] From the viewpoint of the cobalt corrosion prevention property, the amine compound (A) used in the present invention contains one or more selected from specific amine compounds.

[0033] Specifically, n-butylamine, hexylamine, octylamine, 1,4-butylene diamine, dibutylamine, 3-amino-1-propanol, N,N-diethyl-1,3-diaminopropane and bis(hexamethylene)triamine can be listed. Among these, 3-amino-1-propanol, N,N-diethyl-1,3-diaminopropane and bis(hexamethylene)triamine, which are less volatile even under high temperature conditions, are preferred. These can be easily obtained commercially and can be used appropriately.

[0034] The content of the amine compound (A) in the cleaning solution is in the range of 0.2 to 20% by mass, preferably in the range of 0.2 to 8.0% by mass, more preferably in the range of 0.2 to 4.0% by mass, and particularly preferably in the range of 0.5 to 4.0% by mass. By being in the above range, both the removability of dry etching residues and the removability of the dry etching stop layer containing aluminum oxide can be taken into account.

[0035] When the amount is too large, the removal of the dry etching stop layer containing aluminum oxide may be increased, and the side etching of the dry etching stop layer containing aluminum oxide may increase. On the other hand, when the amount is too small, the removal of dry etching residue and the dry etching stop layer containing aluminum oxide may become insufficient.

[0036] [Water-soluble organic solvent (B)]

[0037] The water-soluble organic solvent (B) used in the present invention is a solvent soluble in water and having a viscosity at 20° C. of 10 mPa·s or less.

[0038] Specifically, preferably diethylene glycol monomethyl ether (hereinafter referred to as DGME), diethylene glycol monobutyl ether (hereinafter referred to as DGMB), triethylene glycol monomethyl ether (hereinafter referred to as TGME), dipropylene glycol monomethyl ether (hereinafter referred to as DPGMG), and N, N-dimethyl isobutylamide (hereinafter referred to as DMIB) can be listed. These can be easily obtained commercially, and can be used appropriately, or two or more can be used in combination.

[0039] The content of the water-soluble organic solvent (B) in the cleaning solution is in the range of 40 to 70% by mass, preferably in the range of 45 to 65% by mass. When the amount is too small, the removability of the dry etching barrier layer containing aluminum oxide sometimes becomes higher and the side etching of the dry etching barrier layer containing aluminum oxide increases. In addition, the corrosion resistance of cobalt sometimes becomes insufficient. On the other hand, when the amount is too large, the removability of the dry etching barrier layer containing aluminum oxide sometimes decreases and the cleaning time becomes longer.

[0040] [water]

[0041] The water used in the present invention is not particularly limited, and there may be tap water, industrial water, ground water, distilled water, ion-exchanged water, ultrapure water, etc., preferably ion-exchanged water, and more preferably ultrapure water.

[0042] The water content in the cleaning liquid is preferably in the range of 28 to 59% by mass, more preferably in the range of 34 to 54% by mass.

[0043] [Cleaning fluid]

[0044] The cleaning liquid of the present invention can be prepared by uniformly stirring the amine compound (A), the water-soluble organic solvent (B), and water by a common method.

[0045] The pH of the cleaning solution is 9.0 to 14, preferably 11 to 13. If the pH is too low, the removability of the dry etching stop layer containing aluminum oxide and the corrosion resistance of cobalt may be reduced, and if the pH is too high, the removability of the dry etching stop layer containing aluminum oxide may be increased, and the side etching of the dry etching stop layer containing aluminum oxide may increase.

[0046] The pH may be adjusted simply by adjusting the content of the amine compound (A), or an acid may be added within a range that does not impair the purpose of the present invention.

[0047] [Semiconductor substrate]

[0048] The semiconductor substrate using the cleaning solution of the present invention preferably has: a metal wiring layer containing cobalt, an interlayer insulating film, and a dry etching stop layer, and the residue after dry etching exists on the substrate surface. It is particularly effective when the semiconductor substrate has a mask pattern residue (organic compound residue) as dry etching residue. In addition, the above-mentioned interlayer insulating film may include a low dielectric constant film (Low-k film). In addition, the above-mentioned dry etching stop layer preferably includes aluminum oxide.

[0049] [Method for manufacturing semiconductor substrate]

[0050] The method for producing a semiconductor substrate of the present invention includes the step of cleaning a semiconductor substrate containing cobalt using the cleaning solution of the present invention.

[0051] For example, the cleaning solution of the present invention can be used on a semiconductor substrate after dry etching by an immersion treatment or a single-wafer treatment method. The treatment temperature is usually 10 to 70° C., preferably 40 to 60° C. The treatment time is usually 0.5 to 10 minutes, preferably 1 to 5 minutes. As a rinse solution after using the cleaning solution of the present invention, it is sufficient to rinse with water alone, but an organic solvent such as alcohol or ammonia water can also be used.

[0052] Example

[0053] Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to the following examples at all.

[0054] <Evaluation substrate>

[0055] For dry etching residue removability evaluation (Evaluation I): Lower antireflection film (film thickness: ),

[0056] For dry etching barrier layer removal evaluation (Evaluation II): Aluminum oxide film (film thickness: ), for metal wiring corrosion resistance evaluation (Evaluation III): using cobalt film (film thickness: ).

[0057] Interlayer insulation film corrosion resistance evaluation (Evaluation IV): Low-k film composed of silicon, carbon, hydrogen, and oxygen (film thickness: )

[0058] <Evaluation Substrate Preparation Method>

[0059] The lower anti-reflection film and the low-k film were each formed by spin coating on a silicon wafer.

[0060] The aluminum oxide film is formed on a silicon wafer by physical vapor deposition.

[0061] For cobalt films, on silicon wafers, Silicon oxide, The titanium is sequentially deposited and a film is formed thereon by chemical vapor deposition.

[0062] <Evaluation method>

[0063] [Processing conditions]

[0064] A test piece of the evaluation substrate having a size of 1×1 cm or 2×2 cm was immersed in 10 g of a cleaning liquid at 60° C., and the treated test piece was rinsed with water.

[0065] [Film thickness measurement]

[0066] The film thickness of the lower antireflection film, aluminum oxide film, and low-k film was measured using an optical film thickness meter n&k1280 (manufactured by n&k Technology Inc.). The film thickness reduction of cobalt was calculated from the metal concentration in the cleaning solution after treatment using ICP-AES iCAP6300 (manufactured by Thermo Scientific).

[0067]

[0068] Etching rate / min] was calculated by dividing the film thickness reduction by the treatment time (1 minute for aluminum oxide film, 4 minutes for cobalt film, and 5 minutes for Low-k film).

[0069] determination:

[0070] (Evaluation I): Removability of dry etching residue

[0071] The determination was made based on the removal time of the lower antireflection film (the time from when the lower antireflection film peeled off and the base material became visible).

[0072] G: Less than 15 minutes

[0073] A: 15 minutes to less than 30 minutes

[0074] P: 30 minutes to 60 minutes

[0075] (Evaluation II): Removability of aluminum oxide film

[0076] The determination was made based on the etching rate of the aluminum oxide film.

[0077] G: / minute~less than / minute

[0078] A1: / minute~less than / minute

[0079] A2: / minute~ / minute

[0080] P1: less than / minute.

[0081] P2: Exceed / minute.

[0082] G, A1 and A2 were judged as passing.

[0083] (Evaluation III): Anticorrosion Properties of Cobalt

[0084] The determination was made based on the etching rate of the cobalt film.

[0085] G: less than / minute.

[0086] P: / minute or more.

[0087] The judgment G is recorded as passing.

[0088] (Evaluation IV): Anticorrosion Performance of Low-k Film

[0089] The determination is made based on the etching rate of the Low-k film.

[0090] G: less than / minute.

[0091] P: / minute or more.

[0092] The judgment G is recorded as passing.

[0093] [pH]

[0094] The pH of the cleaning solution was measured using pH METER F-52 manufactured by HORIBA. The measurement temperature was set at 25°C.

[0095] [Viscosity]

[0096] The viscosity of the cleaning liquid was measured using an Ubbelohde viscometer manufactured by Shibata Scientific Co., Ltd. The measurement temperature was set at 20°C.

[0097] [Examples 1 to 22 and Comparative Examples 1 to 9]

[0098] The evaluation substrate was treated and evaluated using a cleaning liquid having a composition shown in Table 1 or Table 2. The unit of concentration in Table 1 or Table 2 represents mass %. For Evaluation IV, Examples 1 to 22 were evaluated and all were judged as G.

[0099] [Table 1]

[0100]

[0101] DGME: diethylene glycol monomethyl ether (viscosity 4 mPa·s at 20°C)

[0102] DGBE: diethylene glycol monobutyl ether (viscosity at 20°C is 7 mPa·s)

[0103] TGME: triethylene glycol monomethyl ether (viscosity at 20°C is 8 mPa·s)

[0104] DPGME: dipropylene glycol monomethyl ether (viscosity 4 mPa·s at 20°C)

[0105] DMIB: N,N-dimethylisobutylamide (viscosity at 20°C is 1 mPa·s)

[0106] [Table 2]

[0107]

[0108] Glycerin: (viscosity at 20°C is 1500 mPa·s)

[0109] Description of Reference Numerals

[0110] 1: Dry etching residue

[0111] 2: Dry etching barrier layer

[0112] 3: Metal wiring layer (cobalt)

[0113] 4: Interlayer insulation film

Claims

1. A cleaning solution comprising: 0.2 to 20% by mass of an amine compound (A), 40 to 70% by mass of a water-soluble organic solvent (B), and water, The amine compound (A) contains one or more selected from the group consisting of n-butylamine, hexylamine, octylamine, 1,4-butanediamine, dibutylamine, N,N-diethyl-1,3-diaminopropane, and bis(hexamethylene)triamine, and the viscosity of the water-soluble organic solvent (B) at 20° C. is 10 mPa·s or less, and the water-soluble organic solvent (B) contains one or more selected from the group consisting of diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, dipropylene glycol monomethyl ether, and N,N-dimethylisobutyramide, and the pH of the cleaning solution is in the range of 9.0 to 14.

2. The cleaning solution according to claim 1, wherein The content of the amine compound (A) is 0.2 to 4.0% by mass.

3. The cleaning solution according to claim 1 or 2, wherein The water content is 28 to 59% by mass.

4. The cleaning solution according to claim 1 or 2, wherein The amine compound (A) contains one or more selected from the group consisting of N,N-diethyl-1,3-diaminopropane and bis(hexamethylene)triamine. The cleaning solution according to claim 1 or 2, which is used for removing dry etching residues. 6 . A method for producing a semiconductor substrate, comprising the step of cleaning a semiconductor substrate containing cobalt using the cleaning solution according to claim 1 .

7. The method for manufacturing a semiconductor substrate according to claim 6, wherein: The semiconductor substrate includes a metal wiring layer containing cobalt, an interlayer insulating film, and a dry etching stopper layer containing aluminum oxide.

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