Hard mask and sputtering target material

Abstract

To provide a hard mask excellent in plasma etching tolerance, low in film stress and capable of showing transmissivity, and a sputtering target material for forming the hard mask.SOLUTION: A hard mask formed on the surface of a body to be processed subjected to plasma etching includes a nitride film containing Ti and one or more kinds of X elements selected from a group consisting of Al, Si and Ge. The atomic ratio of the X elements to the total of Ti and X elements is 10 atom% or more and 60 atom% or less.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to hardmasks and sputtering target materials. [Background technology]

[0002] In the formation of wiring patterns in semiconductor manufacturing, the demand for higher semiconductor capacity requires stacking (multi-layering) of wiring. This increases the etching load, as it is necessary to improve the etching processability of each layer. In response to the increased etching load, etching using a hard mask is beginning to be used, instead of the conventional etching using a resist as a mask. There are metal hard masks and insulating film hard masks, and TiN is generally used as the former metal hard mask.

[0003] For example, in Patent Document 1, a metal hard mask (MHM) 14a is used as a mask to perform CHF 3 / Ar / N 2 The mixed gas is used to plasma etch the silicon oxide film 13 and the low dielectric constant (low-k) layer 12. TiN is used as the metal hard mask (MHM).

[0004] Patent Document 2 shows that by stacking metal films HM1 and HM2 that apply stresses in opposite directions to the insulating film, it is possible to prevent the insulating film including the low dielectric constant layer LF1 after etching from being deformed by the stress from the metal films HM1 and HM2. It also shows that the metal film HM1 is a hard mask film and is made of, for example, TiN or TaN, and the metal film HM2 is a hard mask film and is made of, for example, W, WSi, WN, or TiW.

[0005] Patent Document 3 discloses a hard mask that is formed on the surface of a processing object to limit the processing range when the processing object is subjected to a predetermined processing, the hard mask having an underlayer and a tungsten-containing film laminated on the underlayer, the underlayer having a surface roughness Ra of 0.35 nm or less, and is composed of at least one film selected from a Ti film, a TiN film, a WN film, and a TiWN film.

[0006] Patent Document 4 discloses a metal hard mask for etching a film to be etched that exists on a processing object, the metal hard mask being made of an amorphous alloy film formed by a thin film forming technique. It is shown that by using an amorphous alloy film formed by a thin film forming technique as a metal hard mask, film stress can be significantly reduced compared to the case of using a crystalline film such as a TiN film. It is also shown that the amorphous alloy film is made of an alloy selected from the group consisting of Al-Si, Si-Ti, Nb-Ni, Ta-Zr, Ti-W, and Zr-W.

[0007] Patent Document 5 discloses a method for manufacturing a semiconductor device, which includes the steps of forming a wiring film on a substrate by laminating a titanium nitride (TiN) film and a sputtered silicon film in this order, and heating the substrate, forming a mask in the wiring formation region, dry etching the wiring film to form wiring, and then over-etching to remove residues of the sputtered silicon film, and removing residues of the titanium nitride film by wet etching using the sputtered silicon film as a hard mask. 4 OH, H 2 O 2 and H 2 O) is shown to be wet etched.

[0008] Patent Document 6 discloses a method for manufacturing a ferroelectric element, which includes the steps of: forming a laminated film for forming a capacitor on a base, in which a first conductive layer, a ferroelectric layer made of a metal oxide dielectric, and a second conductive layer are laminated in this order; forming a hard mask including a TiAlN mask layer on the laminated film for forming a capacitor; processing the first conductive layer, the ferroelectric layer, and the second conductive layer into a lower electrode, a ferroelectric thin film, and an upper electrode, respectively, by etching using the hard mask, thereby forming a ferroelectric capacitor from the laminated film for forming a capacitor; performing a heat treatment in a nitrogen atmosphere to recover the crystal structure of the TiAlN mask layer remaining on the ferroelectric capacitor; and performing a heat treatment in an oxygen atmosphere to recover the crystal structure of the ferroelectric thin film. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] JP 2013-98193 A [Patent Document 2] JP 2014-78579 A [Patent Document 3] Patent Publication No. 2022-27215 [Patent Document 4] International Publication No. 2016 / 047245 [Patent Document 5] Japanese Patent Application Publication No. 9-321052 [Patent Document 6] JP 2007-299889 A Summary of the Invention [Problem to be solved by the invention]

[0010] As wiring is layered (multi-layered), the aspect ratio of the etching shape increases when forming wiring patterns. In order to obtain an etching shape with a high aspect ratio, plasma etching must be performed under stricter conditions. Therefore, the hard mask formed as an etching mask is required to sufficiently suppress etching during plasma etching, that is, to have excellent plasma etching resistance. In addition, from the viewpoint of forming highly accurate wiring patterns, the hard mask is also required to have a film stress equal to or less than that of conventional TiN films.

[0011] Furthermore, with the advancement of miniaturization, there is a demand to suppress misalignment with the underlayer (to improve alignment accuracy). Laser or image-based alignment methods are often used to achieve high overlay accuracy with the underlayer. When an image-based alignment method is used, the hard mask is also required to exhibit transparency (also called "transparency").

[0012] In conventional technology, hard masks made of TiN are mainly used, but it is difficult for a hard mask made of TiN to have both of these characteristics.In addition, hard masks made of metal films such as amorphous alloy films can cause strong interference depending on the surface condition, which can degrade the alignment accuracy.

[0013] The present disclosure has been made in consideration of the above circumstances, and an object of the present disclosure is to provide a hard mask having excellent plasma etching resistance, a film stress equal to or less than that of a conventional TiN film, and further exhibiting transparency, and a sputtering target material for forming the hard mask. [Means for solving the problem]

[0014] Aspect 1 of the present invention is A hard mask formed on a surface of a workpiece to be subjected to a plasma etching process, A nitride film containing Ti and one or more X elements selected from the group consisting of Al, Si, and Ge; The hard mask has an atomic ratio of the X element to the total of Ti and the X element of 10 atomic % or more and 60 atomic % or less.

[0015] Aspect 2 of the present invention is The hard mask according to embodiment 1, further comprising one or more Z elements selected from the group consisting of B (boron) and C (carbon).

[0016] Aspect 3 of the present invention is The hard mask according to embodiment 2, wherein an atomic ratio of the Z element to the total of Ti, the X element, and the Z element is greater than an atomic ratio of the X element to the total of Ti, the X element, and the Z element.

[0017] A fourth aspect of the present invention is The hard mask according to any one of aspects 1 to 3, wherein the element X is Al, and the atomic ratio of Al to the total of Ti and Al is 10 atomic % or more and 35 atomic % or less.

[0018] A fifth aspect of the present invention is The hard mask according to any one of aspects 1 to 4, wherein in an X-ray diffraction pattern, the half-width of a peak within a diffraction angle 2θ range of 36° to 38° is 4° or more, or no peak is observed within said range.

[0019] A sixth aspect of the present invention is The hard mask according to any one of aspects 1 to 5, wherein when the hard mask has a thickness of 70 to 150 nm, the transmittance of light with a wavelength of 500 nm is 10% or more.

[0020] A seventh aspect of the present invention is The hard mask according to any one of aspects 1 to 6, wherein the internal stress is 80% or less of the internal stress of a titanium nitride film formed under the same conditions as the hard mask.

[0021] Aspect 8 of the present invention is A sputtering target material for forming a hard mask, Contains Ti and one or more X elements selected from the group consisting of Al, Si, and Ge; The sputtering target material has an atomic ratio of the X element to the total of Ti and the X element of 10 atomic % or more and 60 atomic % or less.

[0022] A ninth aspect of the present invention is The sputtering target material according to embodiment 8, further comprising one or more Z elements selected from the group consisting of B (boron) and C (carbon).

[0023] A tenth aspect of the present invention is A sputtering target material according to embodiment 9, wherein an atomic ratio of the Z element to the total of Ti, the X element, and the Z element is greater than an atomic ratio of the X element to the total of Ti, the X element, and the Z element.

[0024] An eleventh aspect of the present invention is The sputtering target material according to any one of aspects 8 to 10, wherein the X element is Al, and the atomic ratio of Al to the total of Ti and Al is 10 atomic % or more and 35 atomic % or less. Effect of the Invention

[0025] According to the present disclosure, it is possible to provide a hard mask having excellent plasma etching resistance, a film stress equal to or less than that of a conventional TiN film, and further exhibiting transparency, and a sputtering target material for forming the hard mask. [Brief description of the drawings]

[0026] [Figure 1] FIG. 1 is a schematic cross-sectional view illustrating a wiring pattern formation process using a hard mask. [Diagram 2] FIG. 2 is an explanatory diagram showing defects in a wiring pattern when the crystal structure of a hard mask is polycrystalline. [Diagram 3] FIG. 3 is a diagram showing the plasma etching rate for each chemical composition of the metal nitride film in the examples. [Figure 4] FIG. 4 is a diagram showing the plasma etching rate for each chemical composition of the metal film in the examples. [Diagram 5]FIG. 5 is a diagram showing the results of measuring the transmittance of TiN in the examples. [Figure 6] FIG. 6 is a diagram showing the transmittance measurement results of Ti50Al50N in the example. [Figure 7] FIG. 7 is a diagram showing the transmittance measurement results of Ti40Al60N in the example. [Figure 8A] FIG. 8A is a diagram showing thin film stress (internal stress) which is the film stress of a metal nitride film and a Ti film (nitrogen partial pressure concentration: 26%) in an example. [Figure 8B] FIG. 8B is a diagram showing thin film stress (internal stress) which is the film stress of the metal nitride film and the Ti film (nitrogen partial pressure concentration 89%) in the example. [Figure 9] FIG. 9 is a diagram showing thin film stress (internal stress) which is the film stress of the metal oxide film, TiN, and AlN in the examples. [Figure 10] FIG. 10 is a diagram showing the relationship between the amount of Al and the amount of B in the metal nitride film and the amount of wet etching in the examples. [Figure 11] FIG. 11 is a diagram showing the relationship between the amount of Al and the amount of B in the metal nitride film and the plasma etching rate in the examples. [Figure 12] FIG. 12 is a diagram showing the transmittance measurement results in the examples. [Figure 13] FIG. 13 is a diagram showing another transmittance measurement result in the example. [Figure 14] FIG. 14 is a diagram showing an X-ray diffraction pattern of TiAlBN in an example. [Figure 15] FIG. 15 is a graph showing the relationship between the hot pressing temperature (temperature under sintering conditions) and the relative density of the sintered body (sputtering target material) in the examples. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] 1. Hard Mask 1-1. Chemical composition of hard mask The characteristics required for the hard mask of this embodiment will be described with reference to FIG. 1. FIG. 1 is a cross-sectional explanatory diagram that shows a schematic example of a wiring pattern formation process using a hard mask. Note that FIG. 1 is a diagram used for explaining the characteristics required for the hard mask of this embodiment, and the wiring pattern formation process is not limited to this. FIG. 1A shows a laminate in which a base 1, an electrode (poly-Si) 2, a Low-k (SiOF, etc.) 3, a first insulating film 4, a second insulating film 5, and a hard mask 6 are laminated in this order. A resist material is formed on the surface of the laminate, and a resist pattern 7 is formed by performing photolithography (FIG. 1B). In the process of FIG. 1B, in order to suppress misalignment with the film below the hard mask 6 (improving alignment accuracy), the hard mask 6 is required to exhibit transparency. Next, the hard mask 6 is etched (FIG. 1C), and the resist pattern 7 is removed (FIG. 1D). Next, plasma etching is performed to etch the Low-k (SiOF, etc.) 3, the first insulating film 4, and the second insulating film 5. In order to obtain a highly accurate etching shape, the hard mask 6 needs to maintain its shape while suppressing defects and distortions, and is required to have excellent plasma etching resistance and a film stress equal to or less than that of a conventional TiN film.

[0028] The present inventors have conducted extensive research into materials constituting a hard mask in order to provide a hard mask that has excellent plasma etching resistance, low film stress, and further exhibits transparency. As a result, they have found that a hard mask formed on a surface of a workpiece to be subjected to plasma etching treatment should be a nitride film containing Ti and one or more X elements selected from the group consisting of Al, Si, and Ge, and the atomic ratio of the X element to the total of Ti and the X element is 10 atomic % or more and 60 atomic % or less. The chemical composition of this hard mask will be described.

[0029] The hard mask of this embodiment is a nitride film containing Ti and one or more X elements selected from the group consisting of Al, Si, and Ge, and the atomic ratio of the X element to the total of Ti and the X element is 10 atomic % or more and 60 atomic % or less. The X element (Al, Si, Ge) contained together with Ti improves the oxidation resistance of the hard mask, in particular, the oxidation resistance of the hard mask when used in plasma etching with a CF-based gas containing oxygen (CF 4 / O 2 X element is an element that exhibits oxidation resistance against oxygen (e.g., oxygen gas) and enhances the plasma etching resistance of the hard mask. In addition, X element has a wide band gap for visible light and contributes to ensuring the transparency of the hard mask. Furthermore, X element is also an element that forms a low-stress nitride film. X element is preferably Al and / or Si, and more preferably Al, or Al and Si.

[0030] By making the ratio (atomic ratio) of the X element to the total of Ti and X element 10 atomic % or more, excellent plasma etching resistance is exhibited. The atomic ratio of the X element to the total of Ti and X element is preferably 15 atomic % or more, more preferably 20 atomic % or more. On the other hand, if the ratio (atomic ratio) of the X element is too high, exceeding 60 atomic %, the plasma etching resistance is rather decreased. Therefore, the ratio of the X element is set to 60 atomic % or less. The atomic ratio of the X element to the total of Ti and X element is preferably 50 atomic % or less, more preferably 40 atomic % or less.

[0031] As an embodiment of the hard mask of the present disclosure, it may be composed of a nitride of Ti and element X. In this case, the chemical composition (metal ratio) of the hard mask of this embodiment, excluding nitrogen, is represented by the composition formula: Ti 100-a X a In the composition formula, "X" is the X element, and a is the atomic ratio (atomic %) of the X element to the total of Ti and the X element. In the above composition formula, the atomic ratio a of the X element may be 10 atomic % or more and 60 atomic % or less.

[0032] The hard mask of this embodiment may further contain one or more Z elements selected from the group consisting of B (boron) and C (carbon). By containing the Z element, the crystal structure of the hard mask is easily changed from crystalline to amorphous. In addition, by containing the Z element, the ease of removing the hard mask with a chemical such as APM (referred to as "chemical removability") can be increased. The reason for this is considered to be that by containing B, the hard mask surface is easily made porous, and by making the hard mask surface porous, the chemical is easily permeated. In addition, C is considered to have a similar effect. The Z element is preferably B. The Z element B and / or C may be present in the nitride film constituting the hard mask of this embodiment by substituting N, etc.

[0033] In this specification, elements other than nitrogen that constitute the nitride film (including the Z element, if present) may be collectively referred to as "metal".

[0034] In one embodiment of the hard mask of the present disclosure, the hard mask is substantially composed of a nitride of element Z, Ti, and element X. In this case, the chemical composition of the hard mask of this embodiment, excluding nitrogen, is represented by the composition formula: (Ti 100-a X a ) 100-b Z b In the composition formula, "X" is the X element, "Z" is the Z element, a is the atomic ratio (atomic %) of the X element to the total of Ti and the X element, and b is the atomic ratio (atomic %) of the Z element to the total of Ti, the X element, and the Z element.

[0035] When the hard mask of this embodiment is represented by the above composition formula, the atomic ratio b of the Z element is preferably 20 atomic % or more, more preferably 25 atomic % or more, from the viewpoint of making the crystal structure amorphous and improving the chemical removal property. The hard mask of this embodiment is preferable because the Z element is not at an unavoidable impurity level, and contains a certain amount or more of the Z element in this way, and thus has both the above-mentioned characteristics. On the other hand, if the Z element is too much, it is likely to cause a deterioration in the controllability of the chemical composition of the film and the controllability of the chemical removal rate, so the atomic ratio b of the Z element is preferably 50 atomic % or less, more preferably 40 atomic % or less.

[0036] The hard mask of the present embodiment may also contain elements other than Ti, the X element, and the Z element, and is not limited to the above composition formula.

[0037] In the hard mask of this embodiment, the atomic ratio of the Z element to the total of Ti, X element, and Z element is preferably greater than the atomic ratio of the X element to the total of Ti, X element, and Z element. This relationship between the atomic ratios of the X element and the Z element is preferable because it is easier to improve the chemical removability.

[0038] When the Z element is contained, the X element is preferably Al, and the atomic ratio of Al to the total of Ti and Al is 10 atomic % or more and 35 atomic % or less. By containing the Al element in this amount together with the Z element, particularly high chemical solution removability can be obtained. The atomic ratio of Al to the total of Ti and Al is more preferably 20 atomic % or more. On the other hand, the atomic ratio of Al to the total of Ti and Al can be more preferably 30 atomic % or less. In this case, the Z element is preferably B.

[0039] The amount of nitrogen in the chemical composition of the hard mask of this embodiment is not particularly limited.

[0040] 1-2.Hard mask thickness The thickness of the hard mask is not limited and may be determined depending on the location where the hard mask is formed, and may be, for example, 5 to 150 nm.

[0041] 1-3.Hardmask characteristics The hard mask of this embodiment has excellent plasma etching resistance, a film stress equal to or less than that of a conventional TiN film, and further exhibits transparency. These properties of the hard mask of this embodiment will be described in detail below.

[0042] (Plasma etching resistance) The hard mask of this embodiment has excellent plasma etching resistance. Excellent plasma etching resistance means that, as described in the examples below, when plasma etching is performed to measure the amount of film loss and the plasma etching rate (E / R) is calculated, the plasma etching rate is equal to or smaller than the plasma etching rate of TiN measured under the same conditions. The plasma etching rate of TiN measured under the same conditions may have a numerical range, for example, when measured 2 to 5 times, but it is sufficient that the plasma etching rate is equal to or smaller than the upper limit of the numerical range. The plasma etching rate of the hard mask of this embodiment is preferably 10 nm / min or less, more preferably 9 nm / min or less, and even more preferably 8 nm / min or less.

[0043] (Membrane stress) The hard mask of this embodiment has a film stress equal to or smaller than that of a conventional TiN film, and the hard mask of this embodiment has an internal stress of 100% or less, preferably 80% or less, of the internal stress of a titanium nitride film formed under the same conditions as the hard mask. The internal stress is an average value (absolute value) obtained by the method described in the examples described later. "Formed under the same conditions as the hard mask" means that the substrate, substrate temperature, gas atmosphere, DC power, and gas pressure are the same. The average value of the internal stress of the TiN film obtained under these conditions may vary slightly, for example, when the number of n is different between 2 and 5 times, and the average value may have a numerical range. In this case, the average value of the internal stress of the TiN film may be an index of the average value of the upper limit of the numerical range. The internal stress of the hard mask of this embodiment is more preferably 70% or less, and even more preferably 60% or less, of the internal stress of a titanium nitride film formed under the same conditions as the hard mask.

[0044] (transparency) The hard mask of this embodiment exhibits transparency. The term "transparency" means that when the transmittance of light having a wavelength of 500 nm is measured when the thickness of the hard mask is 70 to 150 nm by the method described in the examples below, the transmittance is 7% or more. This allows the hard mask to be superimposed with, for example, a lower layer with high accuracy when a laser or image alignment method is adopted to improve the superimposition accuracy between the hard mask and, for example, a layer (lower layer) below the hard mask. The transmittance is preferably 10% or more, more preferably 30% or more, and even more preferably 40% or more. Considering the chemical composition of the material, the upper limit of the transmittance may be, for example, about 60%. Note that the thickness of the hard mask in the evaluation of the transmittance: 70 to 150 nm is a measurement condition for measuring the transmittance, and does not limit the film thickness of the hard mask of this embodiment. The film thickness of the hard mask of this embodiment is as described above, and the range is different from the thickness of the hard mask in the evaluation of the transmittance.

[0045] (microcrystalline and / or amorphous phase) In the hard mask of the present embodiment, preferably, in the X-ray diffraction pattern, the half-width of the peak ((111) peak) in the range of the diffraction angle 2θ of 36° to 38° is 4° or more, or no peak is observed within the range. The fact that the half-width of the peak is 4° or more or that the peak is not observed means that at least a part of the crystal structure is a microcrystalline and / or amorphous phase. FIG. 2 is a schematic diagram showing plasma etching of a hard mask having a polycrystalline crystal structure from the top of the hard mask. When plasma etching is performed on a hard mask having a polycrystalline crystal structure as shown in FIG. 2A, the grain boundaries of the crystals are eroded by plasma etching as shown in FIG. 2B, and as shown in FIG. 2C, unevenness (roughness 11) is likely to occur on the side walls of the wiring pattern, making it difficult to realize a fine wiring pattern. Therefore, when a finer wiring pattern is required, it is preferable that at least a part of the crystal structure of the hard mask is a microcrystalline and / or amorphous phase, since unevenness on the side walls of the wiring pattern can be suppressed. More preferably, the entire crystal structure of the hard mask is microcrystalline and / or amorphous. Note that Patent Document 6 shows that the crystal structure of TiAlN is restored by performing heat treatment in a nitrogen atmosphere, and does not have a microcrystalline and / or amorphous phase in at least a part of the crystal structure, unlike the hard mask of the present embodiment.

[0046] (Chemical removal ability) The hard mask of the present embodiment preferably exhibits high chemical removability. As shown in the examples described later, high chemical removability means a high removability of the APM chemical (ammonia:H 2 O 2 The wet etching amount is more preferably 80 nm or more, and even more preferably 90 nm or more, when a 100 nm thick film is immersed in DIW (ultrapure water) (volume ratio) = 1:10:10 (70°C) for 16 seconds, the amount of film loss is measured, and the amount of wet etching is calculated.

[0047] 1-4. Hard mask manufacturing The method for manufacturing the hard mask of this embodiment is not particularly limited as long as a nitride film having a predetermined chemical composition is formed. One method for manufacturing the hard mask of this embodiment is to form the film by reactive sputtering using nitrogen gas as a reactive gas. In the reactive sputtering, a mixed gas of nitrogen gas and an inert gas can be used. Examples of the inert gas include argon gas and neon gas, and among these, argon gas is preferred.

[0048] For example, the film may be formed by DC magnetron sputtering under the conditions of substrate temperature: room temperature to 300°C, pressure: 1 mTorr to 5 mTorr, nitrogen partial pressure concentration: 16 to 89%, and DC power: 200 to 500 W. The hard mask of this embodiment is preferably formed by using a sputtering target made of a sputtering target material described later. Film formation using a sputtering target is preferable because it is easier to form a thin film having excellent in-plane uniformity of components and film thickness than a thin film formed by an ion plating method, an electron beam deposition method, or a vacuum deposition method. If a sputtering target containing the above-mentioned elements and having the same chemical composition as the desired hard mask is used as the sputtering target, a hard mask having a desired chemical composition can be formed without the risk of composition deviation.

[0049] 2. Sputtering target material 2-1. Chemical composition of sputtering target materials The present disclosure also includes a sputtering target material for forming a hard mask, the sputtering target material including Ti and one or more X elements selected from the group consisting of Al, Si, and Ge, and the atomic ratio of the X element to the total of Ti and the X element is 10 atomic % or more and 60 atomic % or less. The sputtering target material may further include one or more Z elements selected from the group consisting of B (boron) and C (carbon). When the sputtering target material includes the Z element, it is preferable that the atomic ratio of the Z element to the total of Ti, the X element, and the Z element is greater than the atomic ratio of the X element to the total of Ti, the X element, and the Z element. When the sputtering target material includes the Z element, it is preferable that the X element is Al, and the atomic ratio of Al to the total of Ti and Al is 10 atomic % or more and 35 atomic % or less. The range of the chemical composition of the sputtering target material, the reason for setting it, the preferred range, etc. are as described above in "1. Hard mask". The sputtering target material of this embodiment may be a sputtering target material having the same chemical composition as the desired layer.

[0050] The shape of the sputtering target material includes any shape (such as a square plate, a circular plate, a doughnut plate, or a cylinder) that is processed according to the shape and structure of the sputtering device.

[0051] 2-2. Manufacturing of sputtering target materials The method for producing a sputtering target material described below is merely one example, and the present invention is not limited to this method.

[0052] Examples of methods for producing sputtering target materials include a melt casting method, a powder sintering method, and a spray forming method. In particular, in the spray forming method, a preform (an intermediate body before obtaining a final dense body) made of an alloy is produced, and then the preform is densified by a densification means to obtain a dense body.

[0053] Specifically, the powder sintering method includes a step of blending raw material powders, a step of mixing the blended powders to obtain a mixed powder, and a step of sintering the mixed powder to obtain a sintered body. In the step of blending raw material powders, a metal constituting the sputtering target material or a compound containing the metal (e.g., boride) can be used as the raw material powder. In the step of mixing the blended powders, the mixing means is not particularly limited, and a well-known method, such as a V-type mixer, can be used. In addition, in order to suppress oxidation, dry mixing can be performed in an Ar atmosphere. In the step of sintering the mixed powder, sintering can be performed by, for example, a hot press method.

[0054] The higher the relative density of the sputtering target material, the more stable the sputtering can be achieved, and the relative density of the sputtering target material is preferably 85.0% or more. The relative density is a value calculated by calculated density / theoretical density, as shown in the examples described later. When sintering by the hot press method, the hot press temperature, which is the sintering temperature, is preferably 600°C or more, more preferably 620°C or more, from the viewpoint of obtaining a high relative density sputtering target material with a relative density of 85.0% or more, as shown in the examples described later. From the viewpoint of increasing the relative density of the sputtering target material, the higher the hot press temperature, which is the sintering temperature, the more preferable it is, but from the viewpoint of preventing the melting of the Al powder used as the raw material powder, it is preferable to set the temperature to 660°C or less, which is the melting point of Al. Sintering is preferably performed in an Ar atmosphere to suppress oxidation.

[0055] An ingot obtained by a melt casting method, a sintered body obtained by a powder sintering method, or a dense body obtained by a spray forming method can be subjected to forming processing as necessary to obtain a processed body having a predetermined dimension and, for example, the above-mentioned shape. The processing method is not particularly limited, but examples thereof include a method of machining using a lathe or a milling machine.

[0056] The processed body obtained in the above-mentioned processing step as a sputtering target material can be bonded to a backing plate, for example, to obtain a sputtering target. The bonding method is not particularly limited, but for example, a method of bonding using a bonding agent can be mentioned. The type of bonding agent is not particularly limited, but for example, indium can be mentioned. The bonding method is not particularly limited, but for example, a method of heating the processed body and the backing plate on a hot plate to a temperature at which the bonding agent melts, applying the molten bonding agent to the bonding surface of the backing plate, bonding the bonding surfaces of the processed body together, and then cooling can be mentioned. EXAMPLES

[0057] The present disclosure will be described in more detail below with reference to examples. The present disclosure is not limited to the following examples, and may be modified as appropriate within the scope of the above and below-described aims, and all such modifications are within the technical scope of the present disclosure.

[0058] Example 1: Evaluation of the effect of adding X element on plasma etching resistance In Example 1, the chemical composition of the hard mask was changed to CF 4 / O 2 The plasma etching resistance using gas was evaluated.

[0059] [Formation of Metal Nitride Film] Metal nitride films (thickness 100 nm) with the metal ratios shown in Table 1 were formed on substrates (glass or Si) by magnetron sputtering. In Table 1, the numbers to the right of each element are in atomic percent. 2 The experiment was carried out with an argon gas / Ar mixed gas (argon gas flow rate: 14 sccm, nitrogen gas flow rate: 5 sccm), DC power: 500 W, substrate temperature: 23° C., and gas pressure: 1 mTorr.

[0060] [Table 1]

[0061] [Evaluation of Plasma Etching Resistance] Using a RIE dry etching device, the gas flow rate CF 4 / O 2 The metal nitride film was etched for 5 minutes under the conditions of flow rate = 35 / 28 (sccm), pressure 2 Pa, and RF power 100 W. The amount of film loss of the metal nitride film after etching was measured using a step gauge (a stylus profiler such as Alpha-Step manufactured by ULVAC, Inc.) and the plasma etching rate (E / R) was calculated. The lower the plasma etching rate, the higher the resistance to plasma etching. The results are shown in Table 1. Figure 3 shows the plasma etching rates by composition.

[0062] In order to confirm whether the difference in plasma etching resistance between metal nitride films is due to the metal elements that compose the metal nitride films, metal films were formed as follows, and plasma etching of the metal films was also performed. 50 Al 50 , Ti 40 Al 60 , Ti 75 S 25 , Ti 62 S 38 , Ti 48 S 52 , Ti 35 S 65 A metal film (thickness 100 nm) of each of the above (values ​​are all atomic %) was formed by sputtering. Ar gas was used during sputtering. Other sputtering conditions were the same as for the metal nitride film. Plasma etching was then performed as described above, and the plasma etching rate was determined. Figure 4 shows the plasma etching rate for each type of metal film. The further to the right in Figure 4, the higher the Al or Si content.

[0063] 〔result〕 As shown in Figure 3, by adding Al to TiN, and further by adding Si, the plasma etching rate decreased, that is, the plasma etching resistance increased. Furthermore, the plasma etching resistance increased as the amount of Al added increased. Within the range of the amount of Si added of 10 to 30 atomic %, the plasma etching resistance increased as the amount of Si added increased.

[0064] Furthermore, in FIG. 4, which is related to the metal film, the plasma etching rate of the metal film in which Al is added to Ti is decreased, that is, the plasma etching resistance is increased. This is due to the fact that the vapor pressure of Al fluoride is lower than that of Ti fluoride. It is considered that the plasma etching rate of the metal nitride film is decreased, that is, the plasma etching resistance is increased, due to the fact that the vapor pressure of Al fluoride is low, as in the case of the metal film. On the other hand, in FIG. 4, in the TiSi metal film, the plasma etching rate tends to increase when the Si content is in the range of 25 to 65 atomic %. This is because Si has high oxidation resistance like Al, and when the amount of Si added is small, high plasma etching resistance is shown, but the vapor pressure of Si fluoride is higher than that of Al fluoride, and lower than that of Ti fluoride but close to that of Ti fluoride, so when the amount of Si added is high, the plasma etching rate increases and the plasma etching resistance decreases. It is considered that the same phenomenon occurs in the metal nitride film containing Si.

[0065] Although some metal films exhibit excellent plasma etching resistance, they are not suitable for use as a hard mask because they do not exhibit the transparency required in this embodiment.

[0066] [Example 2: Evaluation of the effect of adding X element on permeability and membrane stress] (1) Evaluation of permeability [Formation of Metal Nitride Film] TiN, Ti 50 Al 50 N, Ti 40 Al 60A metal nitride film (thickness: 100 nm) of each of the metals, N, and N was formed on a glass substrate by sputtering. In Example 2, the sputtering gas was N 2 A nitrogen partial pressure concentration during sputtering deposition was changed within the range of 0% to 89%. The other sputtering conditions were the same as those in Example 1.

[0067] [Measurement of visible light transmittance] The transmittance of light with wavelengths of 250 nm to 800 nm was measured using an ultraviolet-visible-infrared spectrophotometer (V-770DS (manufactured by JASCO Corporation)). The transmittance and reflectance were measured, and the transmittance was used for evaluation. The results are shown in Figure 5 for TiN and Figure 6 for Ti. 50 Al 50 For N, see Fig. 6. For Ti 40 Al 60 N is shown in FIG.

[0068] 〔result〕 In Fig. 5, the transmittance of TiN for light with a wavelength of 500 nm was less than 7%, whereas in Figs. 6 and 7, the transmittance of Ti 50 Al 50 N and Ti 40 Al 60 The transmittance of light with a wavelength of 500 nm for TiN was 7% or more in all cases. TiAlN showed a higher transmittance than TiN in all cases where the nitrogen partial pressure concentration was 26% or more. The transmittance of TiAlN increased with the amount of Al added, and 40 Al 60 N is Ti 50 Al 50It showed a higher transmittance than TiN. This is because AlN has a wider band gap than TiN, so it is thought that the transmittance increased by adding Al to TiN. SiNx also has a wide band gap, so it is thought that the transmittance would be improved by adding Si. TiAlN showed high transmittance at nitrogen partial pressure concentrations of 26% or more, and the transmittance was highest at a nitrogen partial pressure concentration of 26%. In addition, as shown in "Theoretical study of the insulating oxides and nitrides: SiO2, GeO2, Al2O3, Si3N4, and Ge3N4", Cem Sevik et al., Journal of Materials Science volume 42, 2007, p6555-6565, Ge nitrides also have a wide band gap like SiNx, so it is thought that the transmittance would be improved by adding Ge.

[0069] (2) Evaluation of membrane stress [Formation of Metal Nitride Film] The same evaluation of visible light transmittance was performed for TiN and Ti 50 Al 50 N, Ti 40 Al 60 The metal nitride films (thickness: 100 nm) of each of the metals were formed on the surface of a Si substrate by reactive sputtering. The sputtering gas was N 2 A mixed gas of SiO2 / Ar was used, and the nitrogen partial pressure concentrations were set to 26% and 89%. The other sputtering conditions were the same as in Example 1.

[0070] [Membrane stress measurement] The thin film stress (internal stress) of each metal nitride film was measured at room temperature using a thin film stress measurement device (Toho Technology Co., Ltd., device name: FLX2320S). The thin film stress (internal stress), which is the film stress, was calculated by calculating the change in the radius of curvature from the reflection angle of the laser and using Stoney's formula (Reference: GGStoney; Proc. R. Soc. London, Series A, 82, 172 (1909)). In the measurement, the thin film stress (internal stress) was measured and calculated 2 to 5 times for one metal nitride film. The average value (ave) and standard deviation (std) of the thin film stress (internal stress) (unit: MPa) obtained by the 2 to 5 measurements and calculations were then calculated. The results are shown in Figure 8A (nitrogen partial pressure concentration 26%) and Figure 8B (nitrogen partial pressure concentration 89%). For reference, the film stress was also evaluated for Al oxide film, TiN, AlN, and Ti oxide film. The results are shown in Figure 9. In Fig. 9, the Al oxide film is indicated as "AlO" and the Ti oxide film is indicated as "TiO." In Fig. 8A, Fig. 8B and Fig. 9, the bar graphs show the average value (ave) of the thin film stress (internal stress), and the error bars show the standard deviation (std).

[0071] 〔result〕 From Figures 8A and 8B, TiAlN has a smaller film stress than TiN, and when the nitrogen partial pressure concentration is 26%, the internal stress is 18-66% of the TiN film formed under the same conditions, and when the nitrogen partial pressure concentration is 89%, the internal stress is 48-73% of the TiN film formed under the same conditions. The lower the nitrogen partial pressure concentration, the lower the film stress. In this way, the reason why the film stress is lowered by adding Al element to TiN is thought to be because AlN has a lower film stress than TiN, as shown in Figure 9. The difference in film stress (film internal stress) between AlN and TiN is thought to be due to the difference in Young's modulus, Poisson's ratio, and thermal expansion coefficient, which are the thermal properties of the thin film material. It is considered that even when Si is used, the same tendency as TiAlN is observed. In addition, Ge and Si are thought to show similar behavior, and it is considered that the same tendency as TiAlN is observed when Ge is used.

[0072] Example 3: Effects of Addition of B and C From Examples 1 and 2, it was found that adding a certain amount of X element to TiN improves plasma etching resistance, improves transmittance (ensuring transparency), and reduces film stress. In Example 3, the effects of further adding Z element (B, C) (especially chemical removability and low crystallization) were evaluated.

[0073] [Evaluation of Chemical Removability and Plasma Etching Resistance] [Formation of Metal Nitride Film] Metal nitride films (thickness: 100 nm) of TiN, TiAlN, TiAlBN, TiAlCN, TiSiN, TiSiBN, and TiTaBN with the metal ratios shown in Table 2 were formed on glass substrates or Si substrates by sputtering. The sputtering gas was N 2 The sputtering conditions other than those described above were the same as those in Example 1.

[0074] [Evaluation of Chemical Removal Ability] The metal nitride film is treated with an APM chemical (ammonia:H 2 O 2 The sample was immersed in a 1:10:10 (volume ratio) DIW (ultrapure water) (70°C) for 16 seconds, and the amount of film loss (amount of wet etching) was measured using a step gauge (a stylus profiler such as Alpha-Step manufactured by ULVAC, Inc.). The results are shown in the "Chemical removability" column of Table 2. Figure 10 is a graph showing the relationship between the amount of Al and the amount of B (both in atomic %) and the amount of wet etching, using the data in Table 2. For reference, the figure also shows data on AlN.

[0075] [Evaluation of Plasma Etching Resistance] Using a RIE dry etching device, the gas flow rate CF 4 / O 2The metal nitride film was etched for 5 minutes under the conditions of a flow rate of 35 / 28 (sccm), pressure of 2 Pa, and RF power of 100 W. The amount of film loss of the metal nitride film after etching was measured using a step gauge (a stylus profiler such as Alpha-Step manufactured by ULVAC, Inc.), and the plasma etching rate (E / R) (nm / min) was calculated. The lower the plasma etching rate, the higher the resistance to plasma etching. The results are also shown in Table 2. FIG. 11 is a graph showing the relationship between the amount of Al and the amount of B (both in atomic %) and the plasma etching rate, using the data in Table 2. For reference, the figure also shows data for AlN.

[0076] [Table 2]

[0077] [Evaluation of permeability] The permeability of the metal nitride films Nos. 1, 12 and 13 in Table 2 was measured in the same manner as in Example 2. The results are shown in Fig. 12. The permeability of the metal nitride films Nos. 15 to 27 in Table 2 was measured in the same manner as in Example 2. The results are shown in Fig. 13.

[0078] 〔result〕 It can be seen that, in addition to excellent plasma etching resistance, if chemical removability is required as necessary, it is better to add B, which is a Z element. TiN has excellent chemical removability but poor plasma etching resistance. By adding B, which is a Z element, in addition to the X element, it is possible to provide both excellent plasma etching resistance and excellent chemical removability. In particular, when B, which is a Z element, is included, the X element is Al, and the atomic ratio of Al to the total of Ti and Al is 10 atomic % or more and 35 atomic % or less, it is possible to provide both plasma etching resistance and chemical removability superior to TiAlN. Furthermore, from FIG. 12, the transmittance of light with a wavelength of 500 nm of TiAlBN was high, being 7% or more. It can also be seen that, in the case where C, which is a Z element, is added in addition to the X element, it is possible to provide both excellent plasma etching resistance and excellent chemical removability, as in the case where B is added.

[0079] No. 20, which lacked the X element Si, was unable to ensure permeability. No. 24, which contained an excess of Si as the X element, had poor plasma etching resistance and also poor chemical removability. Nos. 25 to 27, which used Ta instead of the X element, also had poor plasma etching resistance. The reason for this is thought to be that Ta has a high fluoride vapor pressure and is easily removed during plasma etching.

[0080] [Evaluation of membrane stress] [Formation of Metal Nitride Film] Metal nitride films (100 nm thick) of TiN, TiAlN, and TiAlBN with the metal ratios shown in Table 3-1 were formed on the surface of a Si substrate by reactive sputtering. The sputtering gas was N 2 A mixed gas of 10000 / Ar was used, and the nitrogen partial pressure concentration was set to 26%. The other sputtering conditions were the same as in Example 1. Note that TiAlCN, TiSiN, TiSiBN, and TiTaBN shown in Table 3-2 are the metal nitride films prepared in the above [Evaluation of chemical removability and plasma etching resistance].

[0081] [Membrane stress measurement] For the metal nitride films having the metal ratios shown in Tables 3-1 and 3-2, film stress measurements were carried out in the same manner as in Example 2. The results are shown in Tables 3-1 and 3-2.

[0082] [Table 3-1]

[0083] [Table 3-2]

[0084] 〔result〕 From Tables 3-1 and 3-2, it was found that the film stress could be sufficiently reduced compared to TiN by adding B. Note that as the amount of B increases, the film stress tends to become slightly higher, but is still sufficiently lower than TiN. Also, it was found that the addition of C also allowed for a sufficient reduction compared to TiN, just like the addition of B. Note that when C is added, the film stress also tends to become slightly higher as the amount of C increases, but is still sufficiently lower than TiN.

[0085] [Evaluation of Crystallinity] [Formation of Metal Nitride Film] A metal nitride film TiAlBN (thickness: 100 nm) with the metal ratio shown in Table 4-1 was formed on the surface of a glass substrate by reactive sputtering. The sputtering gas was N 2 A nitrogen partial pressure concentration of 26% was used in the sputtering process. The other sputtering conditions were the same as those in Example 1. The metal nitride films having the metal ratios shown in Table 4-2 are the metal nitride films prepared in the above [Evaluation of chemical removability and plasma etching resistance].

[0086] [X-ray diffraction analysis] The obtained metal nitride film was subjected to X-ray diffraction (XRD) analysis to obtain an X-ray diffraction pattern. In the X-ray diffraction pattern, it was confirmed whether or not a (111) peak was observed within the range of a diffraction angle 2θ of 36° to 38°, and if such a peak was observed, the half-width of the (111) peak was determined. The results are shown in Tables 4-1 and 4-2. The X-ray diffraction pattern of the metal nitride film TiAlBN in Table 4-1 is shown in Figure 14.

[0087] For reference, the crystallinity of TiN and TiAlN was also confirmed. 50 Al 50 The metal nitride films (thickness: 100 nm) of each of the metals were formed on the surface of a glass substrate by reactive sputtering. The sputtering gas was N 2 The sputtering conditions other than the above were the same as in Example 1. The X-ray diffraction analysis of the obtained metal nitride film was carried out in the same manner as above. As a result, TiN, Ti 50 Al 50 In all cases, the half-width of the (111) peak was small, well below 4°, and the samples were crystalline.

[0088] [Table 4-1]

[0089] [Table 4-2]

[0090] 〔result〕 From Tables 4-1 and 4-2, it can be seen that by adding B and increasing the amount added, the crystallinity of the nitride film can be converted from crystalline to amorphous (containing a large amount of amorphous layer). Considering ensuring excellent chemical removability and making the crystal structure amorphous, it can be seen that even a B amount of about 35% is sufficiently effective. It can also be seen that by adding C and increasing the amount added, the crystallinity of the nitride film can be converted from crystalline to amorphous (containing a large amount of amorphous layer).

[0091] [Example 4: Production of sputtering target material] In the following, as an example of the sputtering target material according to this embodiment, a sputtering target having a metal ratio (atomic %) of Ti 50 Al 21 B 29 A sputtering target material having the above composition was manufactured.

[0092] (Raw powder blending process) The raw powders were Ti powder (purity 99%, 325 mesh), Al powder (purity 99.5%, 325 mesh), TiB 2 The raw powders were Ti powder 51.3 (wt%), Al powder 17.3 (wt%), TiB 2 The powder was blended at 31.4% (by weight).

[0093] (Mixing process of blended raw material powders) The raw material powders were charged into a mixer and dry-mixed in an Ar atmosphere to obtain a mixed powder.

[0094] (Sintering process of mixed powder) The mixed powder was filled into a graphite mold and sintered by hot pressing under the sintering conditions shown in Table 5 below to obtain a sintered body as a sputtering target material.

[0095] (Calculation of relative density) The weight and dimensions of the obtained sintered body were measured, and the calculated density was calculated by weight / volume. The relative density was calculated by dividing the calculated density by the theoretical density. 50 Al 21 B 29 The theoretical density of is 3.7866g / cm 3 The relative density of the sintered body obtained under each sintering condition shown in Table 5 is shown in Table 5. The relationship between the hot press temperature (temperature under the sintering conditions) shown in Table 5 and the relative density of the obtained sintered body (sputtering target material) is shown in FIG.

[0096] [Table 5]

[0097] In this embodiment, as shown in Table 5 and FIG. 15, a high relative density was obtained under the sintering condition No. 3. Therefore, the sintering condition is the following: Metal ratio (atomic %): Ti 50 Al 21 B 29 It can be seen that this is suitable for producing sputtering target materials. [Explanation of symbols]

[0098] 1. Base 2 electrodes (poly-Si) 3. Low-k (SiOF, etc.) 4. First insulating film 5 Second insulating film 6. Hard Mask 7 Resist Pattern 9 grain boundaries 11. Rough

Claims

1. A hard mask formed on a surface of a workpiece to be subjected to a plasma etching process, A nitride film containing Ti and one or more X elements selected from the group consisting of Al, Si, and Ge; A hard mask, wherein an atomic ratio of the X element to the total of Ti and the X element is 10 atomic % or more and 60 atomic % or less.

2. 2. The hard mask of claim 1, further comprising one or more Z elements selected from the group consisting of B (boron) and C (carbon).

3. The hard mask of claim 2 , wherein an atomic ratio of the Z element to the sum of Ti, the X element, and the Z element is greater than an atomic ratio of the X element to the sum of Ti, the X element, and the Z element.

4. 3. The hard mask according to claim 2, wherein the X element is Al, and the atomic ratio of Al to the total of Ti and Al is 10 atomic % or more and 35 atomic % or less.

5. 5. The hard mask according to claim 1, wherein in an X-ray diffraction pattern, a half-width of a peak within a diffraction angle 2θ range of 36° to 38° is 4° or more, or no peak is observed within said range.

6. 5. The hard mask according to claim 1, wherein the hard mask has a transmittance of 10% or more for light with a wavelength of 500 nm when the hard mask has a thickness of 70 to 150 nm.

7. 5. The hard mask according to claim 1, wherein the internal stress is 80% or less of the internal stress of a titanium nitride film formed under the same conditions as the hard mask.

8. A sputtering target material for forming a hard mask, Contains Ti and one or more X elements selected from the group consisting of Al, Si, and Ge; A sputtering target material, in which the atomic ratio of the X element to the total of Ti and the X element is 10 atomic % or more and 60 atomic % or less.

9. The sputtering target material according to claim 8, further comprising one or more Z elements selected from the group consisting of B (boron) and C (carbon).

10. 10. The sputtering target material according to claim 9, wherein an atomic ratio of the Z element to a total of Ti, the X element, and the Z element is greater than an atomic ratio of the X element to a total of Ti, the X element, and the Z element.

11. 10. The sputtering target material according to claim 9, wherein the X element is Al, and the atomic ratio of Al to the total of Ti and Al is 10 atomic % or more and 35 atomic % or less.

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