Dry etching method, method for manufacturing a semiconductor device, and cleaning method

Abstract

The present invention provides a dry etching method which is capable of etching an etching object that contains copper without using plasma. This dry etching method comprises a dry etching step wherein an etching gas, which contains a halogen fluoride that is a compound of bromine or iodine and fluorine, is brought into contact with a member (12) to be etched, said member having an etching object that is to be subjected to etching by means of the etching gas, thereby etching the etching object without using plasma. The etching object contains copper. In addition, the dry etching step is carried out at a temperature of from 140°C to 300°C.

Description

Technical Field

[0001] The present invention relates to a dry etching method, a method for manufacturing a semiconductor device, and a cleaning method.

Background Art

[0002] Copper (Cu) is widely used as a wiring material for semiconductor devices because it has high electromigration resistance and low electrical resistivity. However, since most of the reaction products of copper and etching gas have little vapor pressure, dry etching of copper has not been easy.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] For example, Patent Document 1 proposes a method of plasma etching copper using iodine halide as an etching gas. However, in the technique disclosed in Patent Document 1, since etching is required to use plasma, there is a problem that an expensive plasma generator is required. An object of the present invention is to provide a dry etching method, a method for manufacturing a semiconductor device, and a cleaning method capable of etching an object to be etched containing copper without using plasma.

Means for Solving the Problems

[0005] To solve the above problems, one aspect of the present invention is as follows [1] to

[15] . [1] A dry etching process is provided in which an etching gas containing a halogen fluoride, which is a compound of bromine or iodine and fluorine, is brought into contact with an etched member having an object to be etched, which is the object of etching by the etching gas, and the object to be etched is etched without using plasma. The object to be etched contains copper. The dry etching method in which the dry etching process is carried out under temperature conditions of 140°C or higher and 300°C or lower.

[0006] [2] The dry etching method according to [1], wherein the etching gas is a gas consisting only of the halogen fluoride gas or a mixed gas containing the halogen fluoride and an inert gas. [3] The dry etching method according to [2], wherein the inert gas is at least one selected from nitrogen gas, helium, argon, neon, krypton, and xenon. [4] The dry etching method according to any one of [1] to [3], wherein the content of the halogen fluoride contained in the etching gas is 1% by volume or more and 90% by volume or less.

[0007] [5] The dry etching method according to any one of [1] to [4], wherein the halogen fluoride is at least one of bromine pentafluoride and iodine heptafluoride. [6] The dry etching method according to any one of [1] to [5], wherein the content of oxygen gas contained in the etching gas is 1% by volume or less. [7] The dry etching method according to any one of [1] to [6], wherein the dry etching process is carried out under pressure conditions of 50 Pa or more and 80 kPa or less.

[0008] [8] The object to be etched contains at least one of a copper compound containing at least one of an oxygen atom, a nitrogen atom, and a halogen atom and copper, and at least one of a single substance of copper according to any one of [1] to [7]. [9] The dry etching method according to any one of [1] to [8], wherein the dry etching step is performed under temperature conditions of 210°C or higher and 280°C or lower.

[10] The etched member has a non-etched object that is not an object to be etched by the etching gas and an object to be etched, The dry etching method according to any one of [1] to [9], wherein the object to be etched is selectively etched compared to the non-etched object.

[0009]

[11] The dry etching method according to

[10] , wherein the non-etched object is at least one selected from silicon oxide, photoresist, and amorphous carbon.

[12] The dry etching method according to

[10] or

[11] , wherein the etching selectivity, which is the ratio of the etching rate of the object to be etched to the etching rate of the non-etched object, is 5 or more.

[0010]

[13] A method for manufacturing a semiconductor device, which uses the dry etching method according to any one of [1] to

[12] to manufacture a semiconductor device, wherein the etched member is a semiconductor substrate having the object to be etched, and the method includes a processing step of removing at least a part of the object to be etched from the semiconductor substrate by the dry etching method.

[14] The method for manufacturing a semiconductor device according to

[13] , wherein a copper wiring is formed on the semiconductor substrate by the processing step.

[0011]

[15] A cleaning method for cleaning the inner surface of a chamber of a semiconductor device manufacturing apparatus using the dry etching method according to any one of [1] to

[12] , wherein the etched member is the chamber, the chamber has an attachment adhered to its inner surface during the operation of the semiconductor device manufacturing apparatus, and the attachment is the object to be etched, A cleaning method comprising a cleaning step of removing the deposit from the inner surface of the chamber by the dry etching method.

Effect of the Invention

[0012] According to the present invention, an object to be etched containing copper can be etched without using plasma.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Modes for Carrying Out the Invention

[0014] An embodiment of the present invention will be described below. Note that this embodiment shows an example of the present invention, and the present invention is not limited to this embodiment. Also, various changes or improvements can be made to this embodiment, and forms with such changes or improvements can also be included in the present invention.

[0015] The dry etching method according to this embodiment comprises a dry etching step of bringing an etching gas containing a halogen fluoride, which is a compound of bromine (Br) or iodine (I) and fluorine (F), into contact with an etched member having an object to be etched which is the object of etching by the etching gas, and etching the object to be etched without using plasma. The object to be etched contains copper (Cu). And in the dry etching method according to this embodiment, the dry etching step is carried out under temperature conditions of 140°C or higher and 300°C or lower. Hereinafter, an etching method without using plasma may also be referred to as "plasma-less etching".

[0016] When the etching gas is brought into contact with the member to be etched, the fluoride in the etching gas reacts with the copper in the object to be etched, generating copper fluoride. Since copper fluoride is volatile, the etching of the object to be etched proceeds as the copper fluoride volatilizes.

[0017] Therefore, according to the dry etching method of the present embodiment, an object to be etched containing copper can be selectively etched at a sufficient etching rate without using plasma. That is, the object to be etched can be selectively etched compared to a non-etching object that is not the object of etching by the etching gas. The non-etching object will be described in detail later.

[0018] Further, according to the dry etching method of the present embodiment, since the object to be etched can be etched without using plasma, it is not necessary to use an expensive plasma generation device for etching. Therefore, the etching of the member to be etched can be performed at low cost. Also, since plasma is not used, members constituting the etching device (e.g., a chamber), pipes connected to the etching device, members constituting the semiconductor element manufacturing device to be described later (e.g., a chamber), and pipes connected to the semiconductor element manufacturing device to be described later are less likely to be corroded.

[0019] Note that the etching in the embodiment of the present invention means removing part or all of the object to be etched of the member to be etched to process the member to be etched into a predetermined shape (e.g., a three-dimensional shape) (e.g., processing a film-shaped object to be etched made of copper to a predetermined film thickness), and also means cleaning by removing residues and deposits composed of the object to be etched from the member to be etched, and etch back and the like.

[0020] The dry etching method according to the present embodiment can be used for the manufacture of semiconductor elements and the cleaning of the inner surface of the chamber of a semiconductor element manufacturing device. That is, the method for manufacturing a semiconductor device according to the present embodiment is a method for manufacturing a semiconductor device using the dry etching method according to the present embodiment, wherein the member to be etched is a semiconductor substrate having an object to be etched, and the method includes a processing step of removing at least a part of the object to be etched from the semiconductor substrate by the dry etching method according to the present embodiment.

[0021] For example, the dry etching method according to the present embodiment can be used for forming copper wiring on a semiconductor substrate of a semiconductor device and for etch-back for removing an excessive copper film. Conventionally, the formation of copper wiring has often been performed by a wet process using a CMP (chemical mechanical polishing) slurry or a wet etching solution. However, dry etching using an etching gas is superior in microfabrication to the wet process. Therefore, the dry etching method according to the present embodiment can be expected to contribute to further miniaturization and high integration of semiconductor devices.

[0022] In addition, when manufacturing a semiconductor device using the dry etching method according to the present embodiment and using the non-etching object itself described later as a structure or a resist of the semiconductor device, a material that does not substantially react with a fluoride or a material that reacts extremely slowly with a fluoride is used as the non-etching object. As a specific example of such a non-etching object, at least one material selected from silicon oxide (for example, silicon dioxide (SiO2)), photoresist, and amorphous carbon can be used.

[0023] Also, as described above, the dry etching method according to this embodiment can also be used for cleaning. That is, the cleaning method according to this embodiment is a cleaning method for cleaning the inner surface of the chamber of a semiconductor device manufacturing apparatus using the dry etching method according to this embodiment, and the member to be etched is the chamber. The chamber has deposits adhering to its inner surface due to the operation of the semiconductor device manufacturing apparatus, and these deposits are the objects to be etched. And the cleaning method according to this embodiment includes a cleaning step of removing the deposits from the inner surface of the chamber by the dry etching method according to this embodiment.

[0024] For example, after performing a step of forming a film made of an object to be etched containing copper on a semiconductor substrate or a step of etching a film made of an object to be etched containing copper and formed on a semiconductor substrate in a chamber whose inner surface is made of a material not containing copper, the deposits containing copper adhering to the inner surface of the chamber can be removed and cleaned by the dry etching method according to this embodiment.

[0025] Hereinafter, the dry etching method, the semiconductor device manufacturing method, and the cleaning method according to this embodiment will be described in more detail. [Halogen fluoride] The type of halogen fluoride is not particularly limited as long as it is a compound of bromine or iodine and fluorine, but at least one selected from bromine monofluoride (BrF), bromine trifluoride (BrF3), bromine pentafluoride (BrF5), iodine monofluoride (IF), iodine trifluoride (IF3), iodine pentafluoride (IF5), and iodine heptafluoride (IF7) is preferable. Among these halogen fluorides, from the viewpoints of stability and ease of vaporization, at least one selected from bromine trifluoride, bromine pentafluoride, iodine pentafluoride, and iodine heptafluoride is more preferable, and at least one selected from bromine pentafluoride and iodine heptafluoride is even more preferable.

[0026] [Etching gas] The etching gas is a gas containing a halogen fluoride. The etching gas may be a gas consisting only of a halogen fluoride gas, or may be a mixed gas containing a halogen fluoride and another type of gas. When the etching gas is a mixed gas containing a halogen fluoride and another type of gas, the content of the halogen fluoride contained in the etching gas is preferably 1% by volume or more, more preferably 5% by volume or more, and even more preferably 10% by volume or more in order to etch the object to be etched at a sufficient etching rate. Also, the content of the halogen fluoride contained in the etching gas is preferably 90% by volume or less, more preferably 60% by volume or less, and even more preferably 40% by volume or less from the viewpoints of etching stability and ease of exhaust gas treatment.

[0027] When the etching gas is a mixed gas containing a halogen fluoride and another type of gas, it is preferable to use an inert gas as the other type of gas. That is, the etching gas may be a mixed gas containing a halogen fluoride and an inert gas. As the inert gas, at least one selected from nitrogen gas (N2), helium (He), argon (Ar), neon (Ne), krypton (Kr), and xenon (Xe) can be used. The content of the inert gas contained in the etching gas is not particularly limited, but can be more than 0% by volume and 99% by volume or less, and is more preferably 60% by volume or more and 97% by volume or less from the viewpoint of ease of handling of the etching gas.

[0028] The content of oxygen gas (O2) contained in the etching gas is preferably 1% by volume or less, more preferably less than 1000 ppm by volume, and even more preferably less than 300 ppm by volume. If the content of oxygen gas is 1% by volume or less, it is difficult for a copper oxide film to be formed on the surface of copper, so the etching rate of copper tends to be high. Also, problems such as the generation of etching residues and an increase in wiring resistance due to the diffusion of oxygen atoms from the copper oxide film into the interior are less likely to occur.

[0029] 〔Pressure Conditions in the Dry Etching Process〕 The pressure conditions in the dry etching process of the dry etching method according to this embodiment are not particularly limited as long as the halogen fluoride can exist in a gaseous state at the temperature and pressure during etching. However, it is preferably 50 Pa or more and 80 kPa or less, more preferably 200 Pa or more and 70 kPa or less, and even more preferably 500 Pa or more and 60 kPa or less.

[0030] For example, an etching member can be arranged in the chamber, and etching can be performed while flowing an etching gas through the chamber. However, the pressure inside the chamber during the flow of the etching gas can be 10 Pa or more and 100 kPa or less. The flow rate of the etching gas can be appropriately set according to the size of the chamber and the capacity of the exhaust equipment for reducing the pressure inside the chamber so that the pressure inside the chamber is kept constant.

[0031] 〔Temperature Conditions in the Dry Etching Process〕 The temperature conditions in the dry etching process of the dry etching method according to this embodiment need to be 140°C or more and 300°C or less. Here, the temperature in the temperature conditions refers to the temperature of the etching member, but the temperature of the stage that supports the etching member and is installed inside the chamber of the etching apparatus can also be used.

[0032] If the temperature conditions in the dry etching process are 140°C or more, the halogen fluoride can exist in a gaseous state, and the etching rate of copper is more likely to be higher. Note that the temperature conditions in the dry etching process are preferably 160°C or more, and more preferably exceed 200°C. Particularly if it is 210°C or more, the etching rate of the copper compound increases, and it is likely to greatly contribute to the improvement of the efficiency of the etching process.

[0033] On the one hand, if the temperature condition of the dry etching process is 300°C or lower, etching can be performed without requiring excessive time and energy, the load on the etching apparatus and the semiconductor device manufacturing apparatus is small, and it is possible to suppress the etching of portions that should not be etched originally (for example, non-etching objects described later). Incidentally, the temperature condition of the dry etching process is preferably 280°C or lower, and more preferably 260°C or lower.

[0034] Halide hardly reacts with non-etching objects such as silicon oxide, photoresist, and amorphous carbon in the absence of plasma and under temperature conditions of 300°C or lower. Therefore, when the member to be etched has both an object to be etched and a non-etching object, by using the dry etching method according to the present embodiment, the object to be etched can be selectively etched with hardly any etching of the non-etching object. Thus, the dry etching method according to the present embodiment can be used in a method of processing an object to be etched into a predetermined shape by using a patterned non-etching object as a mask.

[0035] Furthermore, if the temperature of the object to be etched and the non-etching object is 300°C or lower, the etching selectivity tends to be high. For example, the etching selectivity ratio, which is the ratio of the etching rate of the object to be etched to the etching rate of the non-etching object, is likely to be 5 or more. The etching selectivity ratio is more preferably 10 or more, and even more preferably 20 or more.

[0036] 〔Member to be etched〕 The member to be etched etched by the dry etching method according to the present embodiment has an object to be etched that is the target of etching by the etching gas, but may or may not have a non-etching object that is not the target of etching by the etching gas.

[0037] When the member to be etched has an object to be etched and an object not to be etched, the member to be etched may be a member having a portion formed of the object to be etched and a portion formed of the object not to be etched, or may be a member formed of a mixture of the object to be etched and the object not to be etched. The member to be etched may also have something other than the object to be etched and the object not to be etched. The shape of the member to be etched is not particularly limited, and may be, for example, a plate, a foil, a film, a powder, a lump, etc. An example of the member to be etched is the above-mentioned semiconductor substrate.

[0038] [Object to be etched] The etching target to be etched by the etching gas contains copper, but may also contain at least one of a copper compound containing copper and at least one atom selected from oxygen atoms, nitrogen atoms, and halogen atoms (e.g., copper oxide, copper nitride, copper oxynitride, copper halide), and copper as a simple substance. In more detail, the etching target may be, for example, a simple substance of copper, a copper compound, a mixture containing a simple substance of copper, or a mixture containing a copper compound.

[0039] The copper content in the etching object is preferably 1 mol% or more, more preferably 10 mol% or more, and even more preferably 40 mol% or more. The shape of the entire etching object and the shape of the part of the etching object that is made of only copper are not particularly limited, and may be, for example, a foil, a film, a powder, or a lump.

[0040] [Non-etching objects] As described above, the member to be etched may have a non-etching object that is not an object to be etched by the etching gas. Since the non-etching object is hardly etched by the etching method according to the present embodiment, the etching of the object to be etched by the etching gas can be suppressed by the non-etching object.

[0041] Therefore, the etching method according to the present embodiment can be used in methods such as using the patterned non-etching object as a mask to process the object to be etched into a predetermined shape (for example, processing the film-shaped object to be etched of the member to be etched to a predetermined film thickness), and thus can be suitably used for the manufacture of semiconductor elements.

[0042] In addition, since the non-etching object is hardly etched, the non-etching object can suppress the etching of the portion of the semiconductor element that should not be etched, and can prevent the characteristics of the semiconductor element from being lost due to etching. The non-etching object is a material that does not substantially react with a halogen fluoride or a material that reacts extremely slowly with a halogen fluoride, and is, for example, at least one selected from silicon oxide, photoresist, and amorphous carbon.

[0043] A photoresist means a photosensitive composition whose physical properties such as solubility change by light, an electron beam, or the like. For example, there are photoresists for g-line, h-line, i-line, KrF, ArF, F2, EUV, and the like. The composition of the photoresist is not particularly limited as long as it is generally used in the semiconductor manufacturing process. For example, a composition containing a polymer synthesized from at least one monomer selected from chain olefins, cyclic olefins, styrene, vinylphenol, (meth)acrylic acid, (meth)acrylate, epoxy, melamine, and glycol can be mentioned. Note that (meth)acrylic acid means one or both of acrylic acid and methacrylic acid, and (meth)acrylate means one or both of acrylate and methacrylate.

[0044] Next, with reference to FIG. 1, an example of the configuration of an etching apparatus capable of implementing the dry etching method according to the present embodiment and an example of a copper dry etching method using the etching apparatus will be described. The etching apparatus of FIG. 1 is a plasma-less etching apparatus that does not use plasma. First, the etching apparatus of FIG. 1 will be described.

[0045] The etching apparatus of FIG. 1 includes a chamber 10 in which etching is performed, a stage 11 that supports an etching target member 12 to be etched inside the chamber 10, a thermometer 14 that measures the temperature of the etching target member 12, an exhaust pipe 13 for discharging the gas inside the chamber 10, a vacuum pump 15 provided in the exhaust pipe 13 that decompresses the inside of the chamber 10, and a pressure gauge 16 that measures the pressure inside the chamber 10.

[0046] Further, the etching apparatus shown in FIG. 1 includes an etching gas supply unit that supplies etching gas inside the chamber 10. This etching gas supply unit includes a fluoride gas supply unit 1 that supplies a fluoride gas, an inert gas supply unit 2 that supplies an inert gas, a fluoride gas supply pipe 5 that connects the fluoride gas supply unit 1 and the chamber 10, and an inert gas supply pipe 6 that connects the inert gas supply unit 2 to an intermediate portion of the fluoride gas supply pipe 5.

[0047] Furthermore, the fluoride gas supply pipe 5 is provided with a pressure gauge 7 that measures the pressure of the fluoride gas and a fluoride gas flow control device 3 that controls the flow rate of the fluoride gas. Further, the inert gas supply pipe 6 is provided with an inert gas pressure control device 8 that controls the pressure of the inert gas and an inert gas flow control device 4 that controls the flow rate of the inert gas.

[0048] When supplying a fluoride gas as the etching gas to the chamber 10, the fluoride gas is sent from the fluoride gas supply unit 1 to the fluoride gas supply pipe 5, and the fluoride gas is supplied to the chamber 10 through the fluoride gas supply pipe 5.

[0049] When supplying a mixed gas of a fluoride gas and an inert gas as the etching gas, the fluoride gas is sent from the fluoride gas supply unit 1 to the fluoride gas supply pipe 5, and the inert gas is sent from the inert gas supply unit 2 to the fluoride gas supply pipe 5 through the inert gas supply pipe 6. As a result, the fluoride gas and the inert gas are mixed in the intermediate portion of the fluoride gas supply pipe 5 to form a mixed gas, and this mixed gas is supplied to the chamber 10 through the fluoride gas supply pipe 5.

[0050] Note that the configurations of the fluoride gas supply unit 1 and the inert gas supply unit 2 are not particularly limited, and for example, they may be cylinders or cylinders. Further, as the fluoride gas flow rate controller 3 and the inert gas flow rate controller 4, for example, a mass flow controller, a flow meter, or the like can be used.

[0051] When supplying the etching gas to the chamber 10, it is preferable to supply the etching gas while maintaining the supply pressure of the etching gas (that is, the value of the pressure gauge 7 in FIG. 1) at a predetermined value. That is, the supply pressure of the etching gas is preferably 1 kPa or more and 1.0 MPa or less, more preferably 10 kPa or more and 0.5 MPa or less, and still more preferably 30 kPa or more and 0.3 MPa or less. If the supply pressure of the etching gas is within the above range, the supply of the etching gas to the chamber 10 is smoothly performed, and the load on the components (for example, the various devices and the piping) of the etching apparatus of FIG. 1 is small.

[0052] Further, from the viewpoint of uniformly etching the surface of the member to be etched 12, the pressure of the etching gas supplied into the chamber 10 is preferably 50 Pa or more and 80 kPa or less, and more preferably 500 Pa or more and 60 kPa or less. If the pressure of the etching gas in the chamber 10 is within the above range, a sufficient etching rate can be obtained, and the etching rate ratio with respect to the object not to be etched, that is, the etching selectivity ratio, tends to be high.

[0053] The pressure in the chamber 10 before supplying the etching gas is not particularly limited as long as it is equal to or lower than the supply pressure of the etching gas, or lower than the supply pressure of the etching gas. For example, it is preferably 1 Pa or more and less than 10 kPa, and more preferably 10 Pa or more and 5 kPa or less.

[0054] The differential pressure between the supply pressure of the etching gas and the pressure in chamber 10 before supplying the etching gas is preferably 1.0 MPa or less, more preferably 0.5 MPa or less, and even more preferably 0.3 MPa or less. If the differential pressure is within the above range, the supply of the etching gas to chamber 10 is likely to be carried out smoothly.

[0055] When supplying the etching gas to chamber 10, it is preferable to supply while maintaining the temperature of the etching gas at a predetermined value. That is, the supply temperature of the etching gas is preferably 10°C or higher and 150°C or lower. The temperature of the member 12 to be etched during etching is set to 140°C or higher and 300°C or lower. Within this temperature range, the etching of the object to be etched of the member 12 to be etched proceeds smoothly, the load on the etching apparatus is small, and the life of the etching apparatus is likely to be long.

[0056] The etching processing time (hereinafter, may also be referred to as "etching time") can be arbitrarily set according to how much the object to be etched of the member 12 to be etched is desired to be etched. However, considering the production efficiency of the semiconductor element manufacturing process, it is preferably within 30 minutes, more preferably within 20 minutes, and even more preferably within 10 minutes. Note that the etching processing time refers to the time from introducing the etching gas into the inside of chamber 10 to exhausting the etching gas inside chamber 10 to finish the etching.

[0057] The dry etching method according to the present embodiment can be carried out using a general plasma-less etching apparatus used in a semiconductor element manufacturing process, such as the etching apparatus of FIG. 1, and the configuration of the usable etching apparatus is not particularly limited. For example, the positional relationship between the halogen fluoride gas supply pipe 5 and the member to be etched 12 is not particularly limited as long as the etching gas can be brought into contact with the member to be etched 12. Also, regarding the configuration of the temperature adjustment mechanism of the chamber 10, as long as the temperature of the member to be etched 12 can be adjusted to an arbitrary temperature, a configuration in which the temperature adjustment mechanism is directly provided on the stage 11 may be used, or heating or cooling may be performed on the chamber 10 from the outside of the chamber 10 using an external temperature regulator.

[0058] Also, the material of the etching apparatus in FIG. 1 is not particularly limited as long as it has corrosion resistance to the halogen fluoride used and can be depressurized to a predetermined pressure. For example, for the parts that come into contact with the etching gas, metals such as nickel, nickel-based alloys, aluminum, stainless steel, platinum, etc., ceramics such as alumina, and fluororesins can be used. Specific examples of nickel-based alloys include Inconel (registered trademark), Hastelloy (registered trademark), Monel (registered trademark), etc. Also, examples of fluororesins include polytetrafluoroethylene (PTFE), polychlorotrifluoroethylene (PCTFE), ethylene tetrafluoride-perfluoroalkoxyethylene copolymer (PFA), polyvinylidene fluoride (PVDF), Teflon (registered trademark), Viton (registered trademark), Kalrez (registered trademark), etc.

Example

[0059] Examples and comparative examples are shown below to explain the present invention in more detail. The purity of bromine pentafluoride and iodine heptafluoride used in the following examples and comparative examples was analyzed using a Fourier transform infrared spectrophotometer Nicolet iS5 manufactured by Thermo Fisher Scientific, a double-beam spectrophotometer U-2900 manufactured by Hitachi High-Technologies Corporation, and a gas chromatograph GC-2014 manufactured by Shimadzu Corporation, and it was confirmed that the purity was 99% by mass or more in each case.

[0060] (Example 1) Using an etching apparatus having substantially the same configuration as the etching apparatus of FIG. 1, etching (plasma-less etching) of the member to be etched was performed. The test piece (member to be etched) used in Example 1 will be described with reference to FIG. 2.

[0061] A titanium (Ti) film 22 with a thickness of 100 nm was formed on a silicon substrate 21 having a square shape with a side length of 2 inches, and a copper film 23 with a thickness of 600 nm was formed on the titanium film 22 (manufactured by C.S.T. World Co., Ltd.). On the copper film 23, a rectangular silicon dioxide substrate 24 with dimensions of 1 inch × 2 inches was adhered using grease (Demnum Grease L-200 manufactured by Daikin Industries, Ltd.), and this was used as the test piece. As shown in FIG. 2, the silicon dioxide substrate 24 was adhered so as to cover approximately half of the copper film 23.

[0062] This test piece was placed on the stage inside the chamber of the etching apparatus, and the temperature of the stage was raised to 160°C. Next, bromine pentafluoride gas with a flow rate of 50 mL / min and argon with a flow rate of 450 mL / min were mixed to form a mixed gas, and this mixed gas was used as the etching gas. Then, this etching gas was supplied into the chamber at a flow rate of 500 mL / min and circulated for 10 minutes to perform etching. As a result, the exposed portion of the copper film 23 that was not covered by the silicon dioxide substrate 24 was etched. The pressure inside the chamber during the circulation of the etching gas was 10 kPa, and the partial pressure of the bromine pentafluoride gas was 1 kPa. When the circulation of the etching gas was completed, the heating of the stage was terminated, and the inside of the chamber was replaced with argon.

[0063] In addition, when the oxygen gas content contained in the etching gas was measured by gas chromatography, it was less than 100 volume ppm. The measurement conditions are as follows. Measuring instrument: GC-2014 manufactured by Shimadzu Corporation GC column: Shincarbon ST 6m Carrier gas: He (20 mL / min) GC sample loop: 5 mL Injection temperature: 150 °C Column temperature: 50 °C Detector: Thermal conductivity detector (TCD) Detection temperature: 200 °C Current: 180 mA

[0064] When the etching was completed, the chamber was opened, the test piece was taken out, the silicon dioxide substrate 24 was removed from the taken-out test piece, and the adhesive surface was washed with ethanol to remove the grease. Then, using an atomic force microscope VN-8010 manufactured by Keyence Corporation, the height difference between the covered surface 23a of the copper film 23 that was not etched and covered by the silicon dioxide substrate 24 and the etched surface 23b of the copper film 23 that was not covered by the silicon dioxide substrate 24 was measured. The copper etching rate (nm / min) was calculated by dividing the measured height difference (nm) by the etching time (min). The results are shown in Table 1.

[0065] Note that the measurement conditions for the height difference by the atomic force microscope are as follows. Measurement pressure: Atmospheric pressure (101.3 kPa) Measurement temperature: 28 °C Measurement atmosphere: Air Scanning range: Width 80.0 μm, height 20.0 μm, angle 0°

[0066]

Table 1

[0067] (Examples 2 - 10) Except that the conditions were as shown in Table 1, the test pieces were etched in the same manner as in Example 1, and the copper etching rate was calculated. The results are shown in Table 1. (Example 11) A silicon substrate with a square shape of 2 inches on each side, on which a silicon oxide film with a thickness of 2000 nm was formed (manufactured by K.S.T. World Co., Ltd.), was prepared. On the silicon oxide film, a rectangular silicon dioxide substrate with dimensions of 1 inch × 2 inches was adhered using grease (Demnum Grease L-200 manufactured by Daikin Industries, Ltd.) so as to cover approximately half of the silicon oxide film, and it was used as a test piece. Further, a test piece having a copper film similar to that in Example 1 was prepared. Then, these two types of test pieces were placed on the stage inside the chamber of the etching apparatus, and the etching of the two types of test pieces was simultaneously performed under the same conditions as in Example 1, and the etching rates of copper and silicon oxide were calculated. The results are shown in Table 1.

[0068] (Example 12) The test piece was etched in the same manner as in Example 11, except that the silicon oxide film with a thickness of 2000 nm in Example 11 was replaced with a photo resist cured film with a thickness of 300 nm, and the etching rates of copper and the photo resist cured film were calculated. The results are shown in Table 1. The photo resist cured film formed on the copper film 23 was formed by applying photo resist TSCR (registered trademark) manufactured by Tokyo Ohka Kogyo Co., Ltd. on the copper film 23, exposing it, and curing it.

[0069] (Example 13) The test piece was etched in the same manner as in Example 11, except that the silicon oxide film with a thickness of 2000 nm in Example 11 was replaced with an amorphous carbon film with a thickness of 500 nm, and the etching rates of copper and amorphous carbon were calculated. The results are shown in Table 1.

[0070] (Example 14) The test piece was etched in the same manner as in Example 1, except that a copper oxide film with a thickness of 50 nm was formed on the titanium film 22 instead of the copper film 23, and the etching rate of copper oxide was calculated. The results are shown in Table 1. Note that the copper oxide in Example 14 is copper(I) oxide (Cu2O). (Example 15) Except for forming a copper oxide film with a film thickness of 50 nm instead of the copper film 23 on the titanium film 22, the test piece was etched in the same manner as in Example 1, and the etching rate of copper oxide was calculated. The results are shown in Table 1. Note that the copper oxide in Example 15 is copper(II) oxide (CuO).

[0071] (Example 16) Except for forming a copper nitride (Cu3N) film with a film thickness of 100 nm instead of the copper film 23 on the titanium film 22, the test piece was etched in the same manner as in Example 1, and the etching rate of copper nitride was calculated. The results are shown in Table 1.

[0072] (Example 17) Except for using a mixed gas of bromine pentafluoride gas with a flow rate of 50 mL / min, argon with a flow rate of 445 mL / min, and oxygen gas with a flow rate of 5 mL / min as the etching gas, the test piece was etched in the same manner as in Example 1, and the etching rate of copper was calculated. The results are shown in Table 1.

[0073] (Comparative Example 1) Except for setting the temperature of the stage to 130°C, the test piece was etched in the same manner as in Example 1, and the etching rate of copper was calculated. The results are shown in Table 1. (Comparative Example 2) Except for using fluorine gas (F2 gas) instead of bromine pentafluoride gas and using a mixed gas of fluorine gas with a flow rate of 50 mL / min and argon with a flow rate of 450 mL / min as the etching gas, the test piece was etched in the same manner as in Example 1, and the etching rate of copper was calculated. The results are shown in Table 1.

[0074] (Comparative Example 3) Except for performing normal plasma etching in which the plasma of the etching gas is generated in the chamber and etching is performed in the chamber by the plasma of the etching gas, and setting the etching conditions as follows, the test piece was etched in the same manner as in Example 1.

[0075] As test pieces, a substrate (manufactured by C. S. Technology Co., Ltd.) on which a copper film with a thickness of 100 nm was formed, a substrate (manufactured by C. S. Technology Co., Ltd.) on which a silicon oxide film with a thickness of 2000 nm was formed, a substrate having a photoresist cured film with a thickness of 300 nm formed by applying, exposing, and curing a photoresist (TSCR (registered trademark) manufactured by Tokyo Ohka Kogyo Co., Ltd.), and a substrate (manufactured by C. S. Technology Co., Ltd.) on which an amorphous carbon film with a thickness of 500 nm was formed were prepared. Then, these four types of test pieces were placed on the stage inside the chamber of the etching apparatus, and the etching of the four types of test pieces was performed simultaneously, and the etching rates of the four types of films were measured. The results are shown in Table 1.

[0076] The etching conditions are as follows. As the etching apparatus, a parallel plate type plasma CVD apparatus RIE-800iPC manufactured by Samco Inc. was used, the source power was 500 W, and the bias power was 100 W. As the etching gas, a mixed gas of bromine pentafluoride gas with a flow rate of 5 mL / min and argon with a flow rate of 45 mL / min was used. The etching time was 30 seconds, the temperature of the stage was 30 °C, and the pressure inside the chamber was 3 Pa.

[0077] (Comparative Example 4) The test piece was etched in the same manner as in Comparative Example 4 except that the halogen fluoride was iodine heptafluoride and a mixed gas of iodine heptafluoride gas with a flow rate of 5 mL / min and argon with a flow rate of 45 mL / min was used as the etching gas, and the etching rates of the four types of films were calculated. The results are shown in Table 1.

[0078] (Example 21) Etching was performed in the same manner as in Example 1 except that copper(II) fluoride powder (manufactured by Kanto Chemical Co., Inc., average particle size 0.3 μm, purity 99.5%) was used as the object to be etched. After the flow of the etching gas was completed, the inside of the chamber was replaced with argon, the object to be etched was taken out, and the mass of the object to be etched was measured.

[0079] Then, the mass reduction rate of the object to be etched was calculated by dividing the mass of the object to be etched reduced by etching by the mass of the object to be etched before etching. The results are shown in Table 2. The average particle diameter of powders such as copper(II) fluoride powder is the volume-based average particle diameter, and was measured using a laser diffraction / scattering particle size distribution analyzer Partica LA-960 manufactured by Horiba, Ltd.

[0080] [Table 2]

[0081] (Example 22) Etching was performed in the same manner as in Example 21, except that the halogen fluoride was iodine heptafluoride, and a mixed gas in which iodine heptafluoride gas with a flow rate of 50 mL / min and argon with a flow rate of 450 mL / min were mixed was used as the etching gas, and the mass reduction rate of the object to be etched was calculated. The results are shown in Table 2.

[0082] (Comparative Example 11) Etching was performed in the same manner as in Example 21, except that fluorine gas was used instead of bromine pentafluoride gas, and a mixed gas in which fluorine gas with a flow rate of 50 mL / min and argon with a flow rate of 450 mL / min were mixed was used as the etching gas, and the mass reduction rate of the object to be etched was calculated. The results are shown in Table 2.

[0083] (Example 23) Etching was performed in the same manner as in Example 21, except that copper(I) bromide powder (manufactured by Nacalai Tesque, Inc., average particle diameter 0.5 μm, purity 97.5%) was used as the object to be etched, and the mass reduction rate of the object to be etched was calculated. The results are shown in Table 2. (Example 24) Except that the halogen fluoride was iodine heptafluoride and a mixed gas obtained by mixing iodine heptafluoride gas with a flow rate of 50 mL / min and argon with a flow rate of 450 mL / min was used as the etching gas, etching was performed in the same manner as in Example 23, and the mass reduction rate of the object to be etched was calculated. The results are shown in Table 2.

[0084] (Comparative Example 12) Except that fluorine gas was used instead of bromine pentafluoride gas and a mixed gas obtained by mixing fluorine gas with a flow rate of 50 mL / min and argon with a flow rate of 450 mL / min was used as the etching gas, etching was performed in the same manner as in Example 23, and the mass reduction rate of the object to be etched was calculated. The results are shown in Table 2.

[0085] (Example 25) Except that copper(I) iodide powder (manufactured by Nacalai Tesque, Inc., average particle size 0.7 μm, purity 99.5%) was used as the object to be etched instead of copper(II) fluoride powder, etching was performed in the same manner as in Example 21, and the mass reduction rate of the object to be etched was calculated. The results are shown in Table 2. (Example 26) Except that the halogen fluoride was iodine heptafluoride and a mixed gas obtained by mixing iodine heptafluoride gas with a flow rate of 50 mL / min and argon with a flow rate of 450 mL / min was used as the etching gas, etching was performed in the same manner as in Example 25, and the mass reduction rate of the object to be etched was calculated. The results are shown in Table 2.

[0086] (Comparative Example 13) Except that fluorine gas was used instead of bromine pentafluoride gas and a mixed gas obtained by mixing fluorine gas with a flow rate of 50 mL / min and argon with a flow rate of 450 mL / min was used as the etching gas, etching was performed in the same manner as in Example 25, and the mass reduction rate of the object to be etched was calculated. The results are shown in Table 2.

[0087] From the results of Examples 1, 2, and 3, it can be seen that the higher the temperature of the stage, the higher the etching rate of copper. From the results of Examples 2, 4, and 5, it can be seen that the higher the proportion of fluoride in the etching gas, the higher the etching rate of copper. From the results of Examples 2, 6, and 7, it can be seen that the higher the pressure inside the chamber, the higher the etching rate of copper. The reason is considered to be that as the partial pressure of the fluoride gas inside the chamber increases, the frequency of contact between the copper surface and the fluoride increases, and the rate at which copper is converted into an etching product (a reaction product generated as a result of copper etching) is improved.

[0088] From the results of Examples 8 and 9, it can be seen that even when nitrogen gas or helium is used as the inert gas, the etching of copper proceeds without problems. From the result of Example 10, it can be seen that even when iodine heptafluoride is used as the etching gas, the etching of copper proceeds without problems. From the results of Examples 11, 12, and 13, it can be seen that under the condition that copper and the object not to be etched are present in the same chamber, the etching of copper proceeds selectively. From this result, it can be seen that by using the dry etching method according to the present invention, copper can be selectively etched compared to the object not to be etched.

[0089] From the results of Examples 14, 15, and 16, it can be seen that copper oxide and copper nitride can be etched. Also, from this result, it can be seen that the dry etching method according to the present invention is also applicable to the removal of the natural oxide film and nitride film on the copper surface. From the result of Example 17, it can be seen that when oxygen gas is contained in the etching gas, the etching rate of copper decreases slightly.

[0090] From the result of Comparative Example 1, it can be seen that when the temperature of the stage is outside the range of the present invention, the etching of copper hardly proceeds. From the result of Comparative Example 2, it can be seen that when fluorine gas is used as the etching gas, the etching of copper hardly proceeds. From the results of Comparative Examples 3 and 4, it can be seen that in plasma etching, although the etching of copper proceeds, the etching of non-etching targets also proceeds simultaneously.

[0091] From the results of Examples 21 to 26, it can be seen that the etching of copper halides (copper fluoride, copper bromide, copper iodide) proceeds without problems by the dry etching method according to the present invention. On the other hand, from the results of Comparative Examples 11, 12, and 13, it can be seen that when fluorine gas is used as the etching gas, the etching of copper halides is difficult to proceed.

Explanation of Signs

[0092] 1 ··· Halogen fluoride gas supply unit 2 ··· Inert gas supply unit 3 ··· Halogen fluoride gas flow rate control device 4 ··· Inert gas flow rate control device 5 ··· Pipe for supplying halogen fluoride gas 6 ··· Pipe for supplying inert gas 7, 16 ··· Pressure gauge 8 ··· Inert gas pressure control device 10 ··· Chamber 11 ··· Stage 12 ··· Member to be etched 13 ··· Exhaust pipe 14 ··· Thermometer 15 ··· Vacuum pump 21 ··· Silicon substrate 22 ··· Titanium film 23 ··· Copper film 24 ··· Silicon dioxide substrate

Claims

1. A dry etching method comprising a dry etching step of bringing an etching gas containing a halogen fluoride, which is a compound of bromine or iodine and fluorine, into contact with an etched member having an object to be etched, which is an object to be etched by the etching gas, and etching the object to be etched without using plasma, wherein the object to be etched contains copper, and the dry etching step is performed under a temperature condition of 140°C or higher and 300°C or lower.

2. The dry etching method according to claim 1, wherein the etching gas is a gas consisting only of the halogen fluoride gas or a mixed gas containing the halogen fluoride and an inert gas.

3. The dry etching method according to claim 2, wherein the inert gas is at least one selected from nitrogen gas, helium, argon, neon, krypton, and xenon.

4. The dry etching method according to any one of claims 1 to 3, wherein the content of the halogen fluoride contained in the etching gas is 1% by volume or more and 90% by volume or less.

5. The dry etching method according to any one of claims 1 to 4, wherein the halogen fluoride is at least one of bromine pentafluoride and iodine heptafluoride.

6. The dry etching method according to any one of claims 1 to 5, wherein the content of oxygen gas contained in the etching gas is 1% by volume or less.

7. The dry etching method according to any one of claims 1 to 6, wherein the dry etching step is performed under a pressure condition of 50 Pa or higher and 80 kPa or lower.

8. The dry etching method according to any one of claims 1 to 7, wherein the object to be etched contains at least one of a copper compound containing at least one of an oxygen atom, a nitrogen atom, and a halogen atom and copper, and elemental copper.

9. The dry etching method according to any one of claims 1 to 8, wherein the dry etching step is performed under a temperature condition of 210°C or higher and 280°C or lower.

10. The etched member has a non-etched object that is not an object to be etched by the etching gas and the object to be etched, and the object to be etched is selectively etched compared to the non-etched object. The dry etching method according to any one of claims 1 to 9.

11. The dry etching method according to claim 10, wherein the object not to be etched is at least one selected from silicon oxide, photoresist, and amorphous carbon.

12. The dry etching method according to claim 10 or claim 11, wherein an etching selectivity, which is a ratio of the etching rate of the object to be etched to the etching rate of the object not to be etched, is 5 or more.

13. A method for manufacturing a semiconductor device, using the dry etching method according to any one of claims 1 to 12, wherein the member to be etched is a semiconductor substrate having the object to be etched, the method for manufacturing a semiconductor device comprising a processing step of removing at least a part of the object to be etched from the semiconductor substrate by the dry etching method.

14. The method for manufacturing a semiconductor device according to claim 13, wherein a copper wiring is formed on the semiconductor substrate by the processing step.

15. A cleaning method for cleaning the inner surface of a chamber of a semiconductor device manufacturing apparatus, using the dry etching method according to any one of claims 1 to 12, wherein the member to be etched is the chamber, the chamber has deposits adhering thereto with the operation of the semiconductor device manufacturing apparatus on its inner surface, the deposits being the object to be etched, the cleaning method comprising a cleaning step of removing the deposits from the inner surface of the chamber by the dry etching method.

Images