Etching agent composition

Abstract

The present invention relates to an etchant composition, in particular to an aqueous mask layer etchant composition, which is used to remove a tungsten-doped carbon mask layer from the surface of a substrate (e.g., a semiconductor wafer). The composition comprises: (a) 10 to 40 wt.% of hydrogen peroxide based on the total weight of the composition; and (b) 0.1 to 2.0 wt.% of one or more corrosion inhibitors based on the total weight of the composition.

Description

Technical Field

[0001] The present invention relates to an etchant composition, and particularly, but not exclusively, to an aqueous mask layer etchant composition for removing a tungsten-doped carbon mask layer from a surface of a substrate (eg, a semiconductor wafer). Background Art

[0002] Dry etching of semiconductor wafers generally uses a hard mask layer to protect certain areas of the semiconductor wafer during etching. The hard mask must then be removed in order for the semiconductor to be further processed into a final product.

[0003] Hydrogen peroxide can be used to remove such a hard mask layer. However, hydrogen peroxide is corrosive and may corrode existing copper, such as copper contacts used on semiconductor wafers. It is known to add less than 0.01 wt.% of a copper corrosion inhibitor, such as benzotriazole or tolyltriazole, to hydrogen peroxide.

[0004] The present invention is designed based on the above reasons. Summary of the invention

[0005] The inventors of the present invention have found that an aqueous etchant composition comprising hydrogen peroxide and less than 0.01 wt.% of a copper corrosion inhibitor exhibits a certain reduction in the etch rate of copper when compared to hydrogen peroxide alone. However, the etch rates of other metals, particularly cobalt, are greatly increased.

[0006] In its most basic aspect, the present invention provides an aqueous etchant composition comprising hydrogen peroxide and at least 0.1 wt. % of one or more corrosion inhibitors, based on the total weight of the composition, for etching a mask layer on a substrate surface.

[0007] According to a first aspect, the present invention provides an aqueous etchant composition, comprising:

[0008] a. 10 to 40 wt.% hydrogen peroxide, based on the total weight of the composition; and

[0009] b. 0.1 to 2.0 wt. % of one or more corrosion inhibitors, based on the total weight of the composition.

[0010] The inventors of the present invention have found that such a composition provides a good etch rate for mask layers, especially tungsten-doped carbon mask layers, while exhibiting low etch rates for copper and cobalt. Thus, the composition exhibits good etch selectivity for the mask layer relative to semiconductor wafer components, such as copper and cobalt.

[0011] According to a second aspect, the present invention provides a wet etching method for removing a mask layer from a surface of a substrate, the method comprising the following steps:

[0012] a. applying the aqueous etchant composition of the first aspect to the surface of the mask layer on the substrate to etch at least a portion of the mask layer.

[0013] The present invention includes combinations of the described aspects and preferred features unless such combinations are expressly impermissible or explicitly avoided. DETAILED DESCRIPTION

[0014] Aspects and embodiments of the present invention will now be discussed. Additional aspects and embodiments will be apparent to those skilled in the art. Unless expressly stated otherwise, any weight percentage (wt.%) of any ingredient described herein is based on the total weight of the composition.

[0015] Aqueous composition

[0016] The etchant composition is an aqueous composition. The amount of water in the composition can be the remaining amount for reaching 100% after the other ingredients are included in the composition. In certain embodiments, water can be added to the composition. Any water added to the composition can be deionized water or purified water.

[0017] In certain embodiments, the etchant composition is a mask layer etchant composition, which is used to etch a mask layer on a substrate. In a specific embodiment, the etchant composition is a hard mask layer etchant composition, which is used to etch a hard mask layer on a substrate. In a more specific embodiment, the etchant composition is a tungsten-doped carbon mask layer etchant composition, which is used to etch a tungsten-doped carbon mask layer on a substrate.

[0018] Hydrogen Peroxide

[0019] The aqueous mask layer etchant composition comprises 10 to 40 wt.% hydrogen peroxide. In certain embodiments, the aqueous mask layer etchant composition comprises 10 to 35 wt.% hydrogen peroxide. In a specific embodiment, the aqueous mask layer etchant composition comprises 25 to 32 wt.% hydrogen peroxide.

[0020] In a specific embodiment, the aqueous mask layer etchant composition comprises 30 to 32 wt. % hydrogen peroxide. In a specific embodiment, the aqueous mask layer etchant composition comprises about 31 wt. % hydrogen peroxide.

[0021] Corrosion Inhibitors

[0022] The composition may comprise 0.1 to 2.0 wt. % of one or more corrosion inhibitors, based on the total weight of the composition. In certain embodiments, one or more of the corrosion inhibitors is an optionally substituted azole.

[0023] Azoles are five-membered heterocyclic compounds that contain a nitrogen atom and at least one other non-carbon atom (such as nitrogen, sulfur, or oxygen) as part of the ring. Specific examples of compounds within the azole class include:

[0024] - azoles having only nitrogen heteroatoms in the five-membered ring: imidazole; pyrazole; 1,2,3-triazole; 1,2,4-triazole; tetrazole; and pentazole;

[0025] - azoles having nitrogen and oxygen heteroatoms in the five-membered ring: oxazole; isoxazole; oxadiazole; furazan; and 1,3,4-oxadiazole;

[0026] - Azoles having nitrogen and sulfur heteroatoms in the five-membered ring: thiazole; isothiazole; 1,2,3-thiadiazole; 1,2,4-thiadiazole; 1,2,5-thiadiazole; and 1,3,4-thiadiazole.

[0027] One or more of the corrosion inhibitors may be an unsubstituted azole selected from the group consisting of: imidazole; pyrazole; 1,2,3-triazole; 1,2,4-triazole; tetrazole; pentazole; oxazole; isoxazole; oxadiazole; furazan; 1,3,4-oxadiazole; thiazole; isothiazole; 1,2,3-thiadiazole; 1,2,4-thiadiazole; 1,2,5-thiadiazole; and 1,3,4-thiadiazole.

[0028] Additionally or alternatively, one or more of the corrosion inhibitors may be substituted azoles. Any substituent in the substituted azole generally replaces the hydrogen atoms in one or more -NH and / or -CH groups of the azole group. In a specific embodiment, the substituted azole group is an optionally substituted fused bicyclic heterocycle comprising an azole group. Specific examples of optionally substituted fused bicyclic heterocycles comprising an azole group include, but are not limited to, optionally substituted benzotriazoles, optionally substituted benzothiazoles, and optionally substituted benzimidazoles.

[0029] The one or more corrosion inhibitors may be selected from the group consisting of: tolyltriazole (TTA); benzotriazole (BTA); hydroxyl-benzotriazole (HBTA); 2-mercapto-benzotriazole (MBT); methylbenzotriazole (C1-BTA), especially 1H-methylbenzotriazole; butylbenzotriazole (C4-BTA); hexylbenzotriazole (C6-BTA); octylbenzotriazole (C8-BTA); dodecylbenzotriazole (C12-BTA); 5-chloro-benzotriazole (5Cl-BTA); 4-carboxy-benzotriazole (C6-BTA); 5-chloro-benzotriazole (5Cl-BTA); 4-carboxy-benzotriazole (C8-BTA); 5-chloro-benzotriazole (5Cl ... Triazole (4-CBT, 4-carboxy-benzotriazole); 5-carboxy-benzotriazole (5-CBT); 1-(2,3-dicarboxypropyl)benzotriazole (BT-250); bis-(1-benzotriazoylmethylene)-(2,5-thiadiazolyl) disulphide (BBTD, bis-(1-benzotriazoylmethylene)-(2,5-thiadiazolyl) disulphide); 3-aminotriazole (ATA, 3-amino-triazole); 3-aminomercaptotriazole (AMT, 3-aminomercapto-triazole); 3-amino-5-methylthiotriazole (AMTT, 3-amino 5-methylthio-triazole); bromobenzyl-carboxy-triazole (BCT); 2-mercapto-benzothiazole (MBTh); imidazole (IMD); 4-methylimidazole (MI); 1-phenyl-4-methylimidazole (PMI); 1-(p-tolyl)-4-methylimidazole (TMI); 4-Methyl-5-hydroxymethylimidazole (MHMI); 2-mercapto-1-methylimidazole (MMI); 4-methyl-5-imidazolecarbaldehyde (MIC); ethyl-4-methyl-imidazolecarboxylate (EMIC);4-methyl-1(4-methoxyphenyl)imidazole (MMPI, 4-methyl-1(4-methoxyphenyl)imidazole); benzimidazole (BI, benzimidazole); 2-mercapto-benzimidazole (MBI, 2-mercapto-benzimidazole); 2-amino-5-ethylthio-1,3,4-thiadiazole (AETD, 2-amino-5-ethylthio-1,3,4-thiadiazole); 2-amino-5- 2-amino-5-ethyl-1,3,4-thiadiazole (AETDA); 5-(phenyl)-4H-1,2,4-triazole (PTAT); 5-benzylidene-2,4-dioxotetrahydro-1,3-thiazole (BDT); 5-(4'-isopropylbenzylidene) -2,4-dioxotetrahydro-1,3-thiazole (IPBDT, 5-(4'-isopropylbenzylidene)-2,4-dioxotetrahydro-1,3,-thiazole); 5-(3'-thienyl)-2,4-dioxotetrahydro-1,3-thiazole (TDT, 5-(3'-thenylidene)-2,4-dioxotetrahydro-1,3-thiazole); 5-(3',4'-dimethoxybenzylidene)-2,4 MBDT, 5-(3',4'-dimethoxybenzylidene)-2,4-dioxotetrahydro-1,3-thiazole; tetrazole (T, tetratrazole); 5-mercapto-1-methyltetrazole (5Mc-1Me-T); 5-mercapto(Na salt)-1-methyltetrazole (5NaMc-1Me-T, 5-mercapto(Na salt)-1-methyl-tetrazole); 5-mercapto-1-acetic acid (Na salt)-tetrazole (5Mc-1Ac-T, 5-mercapto-1-acetic acid (Na salt)-tetrazole); 5-mercapto-1-phenyl-tetrazole (5Mc-1Ph-T, 5-mercapto-1-phenyl-tetrazole); 1-phenyl-tetrazole (1PH-T, 1-phenyl-tetrazole); 5-phenyl-tetrazole (5Ph-T, 5-phenyl-tetrazole);and 5-aminotetrazolyl (5NH; 2 -T, 5-amino-tetrazole).

[0030] In a specific embodiment, the composition comprises benzotriazole, C1 to C12 alkyl-benzotriazole (CX-BTA), or a mixture thereof. In certain embodiments, the composition comprises one of benzotriazole or C1 to C12 alkyl-benzotriazole as a sole corrosion inhibitor.

[0031] Benzotriazole has a known structure and may be substituted at one or more of several positions with a C1 to C12 alkyl group.

[0032] C1 to C12 alkyl-benzotriazole can exist in the form of two or more structural isomers. Unless a specific isomer or a mixture of isomers is explicitly stated, C1 to C12 alkyl-benzotriazole can be any one of the isomers or any combination of isomers. The composition can include a single isomer or a mixture of isomers. For example, when the composition includes 1H-methylbenzotriazole, the composition can include a single isomer selected from 1H-4-methylbenzotriazole, 1H-5-methylbenzotriazole, 1H-6-methylbenzotriazole, 1H-7-methylbenzotriazole, or a mixture of two, three or four of these isomers. In particular, the term tolyltriazole (TTA) is generally used for a commercial mixture consisting of all four 1H-methylbenzotriazole isomers (i.e., 1H-4-methylbenzotriazole, 1H-5-methylbenzotriazole, 1H-6-methylbenzotriazole and 1H-7-methylbenzotriazole). TTA generally contains approximately equal amounts of 4-methylbenzotriazole and 5-methylbenzotriazole and small amounts of the 6-methyl isomer and the 7-methyl isomer.

[0033] In certain embodiments, (C1 to C12 alkyl) y -Benzotriazole is a 1H-C1 to C12 alkyl-benzotriazole. In other words, the nitrogen atom in the benzotriazole ring is protonated.

[0034] As defined herein, the C1 to C12 alkyl group may be straight chain or branched. In certain embodiments, the C1 to C12 alkyl group is a straight chain alkyl group. As defined herein, the C1 to C12 alkyl group may be saturated or unsaturated. In a specific embodiment, the C1 to C12 alkyl group is a saturated alkyl group.

[0035] In certain embodiments, the composition comprises tolyltriazole (TTA), benzotriazole (BTA), or a mixture thereof.

[0036] In a specific embodiment, the composition comprises a mixture of tolyltriazole (TTA) and benzotriazole (BTA) as corrosion inhibitor. In another specific embodiment, the composition comprises tolyltriazole (TTA) as the sole corrosion inhibitor.

[0037] The composition comprises 0.1 to 2.0 wt.% of one or more corrosion inhibitors. In other words, the minimum amount of corrosion inhibitors in the composition is 0.1 wt.% based on all corrosion inhibitors present, and the maximum amount of corrosion inhibitors in the composition is 2.0 wt.% based on all corrosion inhibitors present. The composition may comprise a single corrosion inhibitor or a mixture of corrosion inhibitors. When the composition comprises a single corrosion inhibitor, the composition comprises 0.1 wt.% to 2.0 wt.% of a single corrosion inhibitor. In one embodiment, the composition comprises 0.1 wt.% to 2.0 wt.% of one of benzotriazole or C1 to C12 alkyl-benzotriazole as a single corrosion inhibitor, in particular 0.1 wt.% to 2.0 wt.% of tolyltriazole (TTA) as a single corrosion inhibitor. When the composition comprises a mixture of two or more corrosion inhibitors, the composition comprises 0.1 wt.% to 2.0 wt.% of all corrosion inhibitors.

[0038] In certain embodiments, the composition comprises from 0.25 to 0.75 wt. % of one or more corrosion inhibitors. In a particular embodiment, the aqueous mask layer etchant composition comprises from 0.4 to 0.6 wt. % of tolyltriazole (TTA).

[0039] In certain embodiments, the composition is acidic. In other words, the composition may have a pH value of 6.9 or lower. In certain embodiments, the composition has a pH value in the range of 1 to 6.9. In a specific embodiment, the composition has a pH value in the range of 4 to 6.9.

[0040] Other Etchant Additives

[0041] In certain embodiments, the composition comprises one or more layer etchant additives. In a specific embodiment, the composition comprises 0.0001 to 1 wt.% of a layer etchant additive. In a more specific embodiment, the composition comprises 0.0001 to 0.1 wt.% of a layer etchant additive.

[0042] In certain embodiments, the composition is substantially free of additional etchant additives. In certain embodiments, the composition is substantially composed of:

[0043] a. 10 to 40 wt.% hydrogen peroxide, based on the total weight of the composition; and

[0044] b. 0.1 to 2.0 wt. % of one or more corrosion inhibitors, based on the total weight of the composition;

[0045] The balance is water.

[0046] In a particular embodiment, the composition consists essentially of:

[0047] a. 30 to 32 wt.% hydrogen peroxide;

[0048] b. 0.4 to 0.6 wt.% tolyltriazole (TTA); and

[0049] c. 0.001 to 0.002 wt.% of benzotriazole (BTA);

[0050] The balance is water.

[0051] In another embodiment, the composition consists essentially of:

[0052] a. 30 to 32 wt.% hydrogen peroxide; and

[0053] b. 0.4 to 0.6 wt.% tolyltriazole (TTA);

[0054] The balance is water.

[0055] These compositions consisting essentially of hydrogen peroxide and one or more corrosion inhibitors avoid the use of excess ingredients and still achieve good etching performance of tungsten-doped carbon mask layers (as demonstrated in the following examples). This allows cost savings and avoids the use of other potentially hazardous chemicals.

[0056] Methods of using the composition

[0057] The present invention also provides a wet etching method for removing a mask layer from a surface of a substrate, the method comprising the following steps:

[0058] a. applying an aqueous etchant composition as described herein to the surface of the mask layer on the substrate to etch at least a portion of the mask layer.

[0059] In a specific embodiment, the mask layer is a hard mask layer. In a more specific embodiment, the mask layer is a tungsten-doped carbon mask layer. In these embodiments, the tungsten-doped carbon mask layer may contain amorphous carbon and tungsten in an atomic concentration range of 30 to 70 atomic %.

[0060] In certain embodiments, the aqueous etchant composition is applied to the mask layer at a temperature of 50°C or higher. In certain embodiments, the composition is applied to the mask layer at a temperature in the range of 50 to 100°C. In a specific embodiment, the composition is applied to the mask layer at a temperature in the range of 60 to 80°C. In order to bring the aqueous etchant composition to a temperature in the above range, the method may include the step of heating the composition to a temperature of 50°C or higher, in the range of 50 to 100°C, or in the range of 60 to 80°C.

[0061] In some embodiments, the method further comprises a step (b) of rinsing the substrate with a rinsing liquid after the step of applying the aqueous etchant composition (step (a)). The rinsing liquid can be any rinsing liquid suitable for rinsing the etched substrate (e.g., semiconductor wafer). In one embodiment, the rinsing liquid is deionized water. The rinsing liquid can be an aqueous rinsing liquid comprising one or more rinsing liquid additives.

[0062] In a particular embodiment, the method further comprises one or more steps of drying the substrate. The first drying step may be followed by step (a) to remove excess aqueous etchant composition from the substrate. When present, a second or optional drying step may follow after step (b) to remove excess rinsing liquid from the substrate. The method of drying the substrate in any drying step is not particularly limited. In some embodiments, the drying step comprises the flow of a gas above the surface of the substrate to be dried. In these embodiments, the gas may be heated. In these embodiments, the drying step may comprise a gas flow, wherein the gas is at a temperature in the range of 20°C to 100°C. The temperature of the gas may be in the range of 30°C to 80°C, or 40°C to 60°C.

[0063] The mask layer on the surface of the substrate may be exposed to the aqueous etchant composition in the range of 10 seconds to 2 minutes. In certain embodiments, the mask layer on the surface of the substrate may be exposed to the aqueous etchant composition in the range of 20 seconds to 40 seconds.

[0064] In a specific embodiment, the step of applying the aqueous etchant composition to the surface of the substrate uses a liquid spin process (also known as spin etching or wet spin processing). Non-limiting examples of equipment used for liquid spin processes can be found in US 4,903,717 and WO 2006 / 027332.

[0065] In this liquid spinning process, the substrate is generally held on a rotatable platform and an aqueous etchant composition is applied to the mask layer at the same time. The surface of the substrate with the mask layer (the surface to be treated) is generally flat, and the substrate can be held horizontally relative to the plane. The platform and the substrate rotate around the rotation axis. The rotation axis is generally perpendicular to the plane of the surface of the mask layer to which the aqueous etchant composition is applied.

[0066] The axis of rotation generally intersects the center of the surface of the substrate to which the aqueous etchant composition is applied, and the aqueous etchant composition is applied to the center of the surface of the substrate. In this way, the aqueous etchant composition as described herein can be moved from the center (or inner region) of the substrate surface to the outer region of the substrate surface by centrifugal force. Additionally or alternatively, the impact point of the aqueous etchant composition on the mask layer located on the surface of the substrate is moved across the surface of the substrate in a time sequence.

[0067] In certain embodiments, the volume flow rate of the aqueous etchant composition to the surface of the rotating substrate is at least 0.05 l / min. In a specific embodiment, the volume flow rate of the aqueous etchant composition to the surface of the rotating substrate is at least 0.5 l / min. In certain embodiments, the aqueous etchant composition is applied to the mask layer on the surface of the substrate as a continuous liquid stream.

[0068] In certain embodiments, when the aqueous etchant composition is applied to the mask layer of the substrate, the rotation speed of the platform and the substrate is 60 rpm or higher. In a specific embodiment, when the aqueous etchant composition is applied to the mask layer of the substrate, the rotation speed of the platform and the substrate is 300 rpm or higher.

[0069] In certain embodiments, the aqueous etchant liquid is applied to the surface of the rotating substrate as a free liquid beam. In other words, the liquid is applied to the surface of the substrate without any physical constraints. This free liquid beam can be applied in the following manner: at a distance from the surface, the aqueous etchant composition is dispensed from an aqueous etchant composition dispenser, and a force such as gravity is allowed to bring the liquid to the surface. In certain embodiments, the method comprises dispensing the aqueous etchant composition from an aqueous etchant composition dispenser above a mask layer disposed on the surface of the substrate so that the aqueous etchant composition is applied to the mask layer on the surface of the substrate.

[0070] In certain embodiments, any material that flows off the surface of the substrate (eg, the aqueous etchant composition and / or the mask layer) may be collected by an annular liquid collector that surrounds the rotating platform and substrate.

[0071] The substrate can be held by a rotatable platform using any known substrate holding device. In a specific embodiment, the substrate is held by a rotatable platform using a vacuum chuck (or fixture), an edge clamping chuck or a Bernoulli chuck (or fixture).

[0072] In certain embodiments, the substrate is a semiconductor wafer.

[0073] The features disclosed in the above description, in the following claims, or in the accompanying drawings (expressed in their specific form or in the form of a method or process for performing the disclosed function, or for obtaining the disclosed result) may be used alone or in any combination of these features to realize the present invention in its various forms.

[0074] Although the present invention has been described in conjunction with the above exemplary embodiments, many equivalent modifications and variations will be apparent to those skilled in the art when presenting the present disclosure. Therefore, the above exemplary embodiments of the present invention are considered to be exemplary and non-restrictive. Various changes may be made to the embodiments without departing from the spirit and scope of the present invention.

[0075] In order to avoid any doubt, any theoretical explanations provided herein are proposed for the purpose of improving the reader's understanding. The inventors of this case do not wish to be bound by any of these theoretical explanations.

[0076] Any section headings used herein are for organizational purposes only and are not to be construed as limiting the subject matter described.

[0077] Throughout the specification (including the following claims), unless the context requires otherwise, the words "comprise" and "include", and variations such as "comprising", "containing", and "including"), will be understood to imply the inclusion of stated integers or steps, or groups of integers or steps, but not the exclusion of any other integers or steps, or groups of integers or steps.

[0078] It must be noted that, as used in the specification and the appended claims, the singular forms "a", "an", and "the" include plural referents unless the context clearly indicates otherwise. Herein, ranges can be expressed as from "about" one particular value and / or to "about" another particular value. When such a range is expressed, another embodiment includes from the one particular value and / or to the other particular value. Similarly, when a value is expressed as an approximation by using the antecedent "about", it is understood that the particular value forms another embodiment. The term "about" in relation to a value is optional and means, for example, + / - 10%.

[0079] Example

[0080] Example 1

[0081] Etch rates of the components of a silicon semiconductor wafer including copper, cobalt, and a tungsten-doped carbon (WDC) mask layer (with 50 atomic % W) using the following three compositions (all values ​​are presented as weight percent based on the total weight of the composition):

[0082] A B C Hydrogen Peroxide 31％ 31％ 31％ Benzotriazole (BTA) 0 0.0017％ 0.0017％ Tolyltriazole (TTA) 0 0 0.5％ water margin margin margin

[0083] Compositions A and B are comparative compositions. Composition C is a composition according to the present invention.

[0084] A silicon semiconductor wafer including copper, cobalt, and a tungsten doped carbon mask layer (with 50 atomic % W) was placed in separate beakers; each beaker containing one of compositions A to C was heated to 70° C. for about 30 seconds before the wafer was removed and rinsed. The etching rate of each of WDC, copper, and cobalt was calculated by measuring the change in thickness of the layer and dividing the thickness by the time of exposure to the aqueous etchant composition, and the etching rate of each component (presented in angstroms / minute) due to exposure to each composition is shown in the table below.

[0085] Etching rate (A / min) A B C WDC 45.4 89.1 75.3 Cu 3.1 0.7 0.3 Co 2.0 71.9 0.0

[0086] As can be observed from the table above, the small amount (less than 0.01 wt.%) addition of the BTA corrosion inhibitor in Composition B reduces the copper etch rate when compared to hydrogen peroxide alone in Composition A. However, Composition B exhibits a higher cobalt etch rate than Composition A. In contrast, Composition C (maintaining the same BTA level) comprising 0.5 wt.% TTA shows a reduction in both copper and cobalt etch rates when compared to Compositions A and B. In addition, the use of Composition C increases the etch rate of the WDC mask layer when compared to Composition A.

[0087] The processing of silicon semiconductor wafers including copper, cobalt, and tungsten doped carbon mask layers was repeated using compositions B and C using a liquid spin process at 70° C. and 65° C., respectively. The etch rate of each of WDC, copper, cobalt, and bare silicon was calculated by measuring the change in thickness of the layer and dividing the thickness by the time of exposure to the aqueous etchant composition. The etch rate of each component (expressed in angstroms / minute) due to exposure to each composition is shown in the table below.

[0088] Etching rate (A / min) B C WDC 125.6 133.2 Cu 2.8 0.6 Co 71.9 0.0 Naked Si 358 36

[0089] As can be observed from the table above, composition C (composition according to the invention) provides significantly reduced etch rates for copper, cobalt and bare silicon when compared to composition B (comparative composition). The etch rates of the tungsten doped carbon mask layer are comparable for both compositions.

[0090] References

[0091] Many publications are cited above to more fully describe and disclose the present invention and the prior art in the field of technology to which the present invention belongs. The complete citations of these references are provided below.

[0092] US 4,903,717

[0093] WO 2006 / 027332

Claims

1. An aqueous etchant composition, comprising: a. 30 to 32 wt.% hydrogen peroxide, based on the total weight of the composition; and b. 0.1 to 2.0 wt. % of one or more corrosion inhibitors, based on the total weight of the composition, comprising 0.4 to 0.6 wt. % of tolyltriazole (TTA), based on the total weight of the composition, The composition is substantially free of additional etchant additives.

2. The aqueous etchant composition according to claim 1, wherein the composition has a pH of 6.9 or less.

3. The aqueous etchant composition according to claim 2, which has a pH value of 4 to 6.

9.

4. The aqueous etchant composition according to any one of claims 1 to 3, wherein the composition comprises 0.25 to 0.75 wt. % of the one or more corrosion inhibitors.

5. The aqueous etchant composition according to any one of claims 1 to 3, wherein the composition comprises 0.4 to 0.6 wt. % of tolyltriazole (TTA) as a sole corrosion inhibitor.

6. The aqueous etchant composition according to any one of claims 1 to 3, wherein the composition consists essentially of: a. 30 to 32 wt.% hydrogen peroxide; b. 0.4 to 0.6 wt.% tolyltriazole (TTA); as well as c. 0.001 to 0.002 wt. % of benzotriazole (BTA).

7. The aqueous etchant composition according to any one of claims 1 to 3, wherein the composition consists essentially of: a. 30 to 32 wt.% hydrogen peroxide; as well as b. 0.4 to 0.6 wt. % tolyltriazole (TTA).

8. A wet etching method for removing a mask layer from a surface of a substrate, the method comprising the following steps: a. applying the aqueous etchant composition according to any one of claims 1 to 7 to the surface of the mask layer on the substrate to etch at least a portion of the mask layer.

9. The method of claim 8, wherein the mask layer is a tungsten-doped carbon mask layer.

10. The method of claim 9, wherein the tungsten-doped carbon mask layer contains tungsten at an atomic concentration in the range of 30 to 70 atomic % and amorphous carbon.

11. The method according to any one of claims 8 to 10, wherein the aqueous etchant composition is applied to the mask layer at a temperature of 50°C or higher.

12. The method according to any one of claims 8 to 10, wherein the method further comprises the steps of: (i) rinsing the substrate with a rinsing liquid after the step of applying the aqueous etchant composition, and then (ii) drying the substrate.

13. The method of claim 11, wherein the method further comprises the steps of: (i) rinsing the substrate with a rinsing liquid after the step of applying the aqueous etchant composition, and then (ii) drying the substrate.

14. The method according to any one of claims 8 to 10, wherein the substrate is a semiconductor wafer.

15. The method of claim 11, wherein the substrate is a semiconductor wafer.

16. The method of claim 12, wherein the substrate is a semiconductor wafer.

17. The method of claim 13, wherein the substrate is a semiconductor wafer.