Dry etching method, method for manufacturing semiconductor element, and cleaning method

Abstract

Provided is a dry etching method capable of etching an etching target containing copper without using plasma. A dry etching method includes a dry etching step of bringing an etching gas containing a halogen fluoride into contact with an etched member (12) having an etching target, and etching the etching target without using plasma, the halogen fluoride being a compound of bromine or iodine and fluorine, and the etching target being an object to be etched by the etching gas. The etching target contains copper. The dry etching step is performed at a temperature of 140°C or higher and 300°C or lower.

Description

TECHNICAL FIELD

[0001] The present application relates to a dry etching method, a semiconductor element manufacturing method, and a cleaning method. BACKGROUND

[0002] Copper (Cu) has high electromigration resistance and low resistivity, and is therefore commonly used as a wiring material for semiconductor elements. However, the reaction product of copper and an etching gas has almost no vapor pressure, and therefore dry etching of copper is not easy.

[0003] PRIOR ART DOCUMENTS

[0004] Patent Document 1: Japanese Patent Publication No. 3381076 SUMMARY

[0005] For example, Patent Document 1 proposes a method of performing plasma etching of copper using iodine halide as an etching gas. However, in the technology disclosed in Patent Document 1, etching needs to be performed using plasma, and therefore there is a problem in that a high-priced plasma generating device is required.

[0006] An object of the present application is to provide a dry etching method, a semiconductor element manufacturing method, and a cleaning method that can etch an etching target containing copper without using plasma.

[0007] To solve the problem, one aspect of the present application is as shown in [1] to

[15] below.

[0008] [1] A dry etching method comprising a dry etching step of bringing an etching gas containing a halogen fluoride into contact with an etched member having an etching target to be etched by the etching gas, and etching the etching target without using plasma, the halogen fluoride being a compound of bromine or iodine and fluorine, the etching target being an object to be etched by the etching gas,

[0009] the etching target containing copper,

[0010] the dry etching step is performed at a temperature of 140°C or higher and 300°C or lower.

[0011] [2] The dry etching method according to [1], wherein the etching gas is a gas composed only of a gas of the halogen fluoride, or a mixed gas containing the halogen fluoride and an inert gas.

[0012] [3] The dry etching method according to [2], wherein the inert gas is at least one selected from the group consisting of nitrogen, helium, argon, neon, krypton, and xenon.

[0013] [4] The dry etching method according to any one of [1] to [3], wherein the halide contained in the etching gas is contained in an amount of 1 vol% or more and 90 vol% or less.

[0014] [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.

[0015] [6] The dry etching method according to any one of [1] to [5], wherein the oxygen contained in the etching gas is contained in an amount of 1 vol% or less.

[0016] [7] The dry etching method according to any one of [1] to [6], wherein the dry etching process is performed under a pressure condition of 50 Pa or more and 80 kPa or less.

[0017] [8] The dry etching method according to any one of [1] to [7], wherein the etching target contains at least one of a copper compound and copper single substance, the copper compound containing at least one of an oxygen atom, a nitrogen atom, and a halogen atom and copper.

[0018] [9] The dry etching method according to any one of [1] to [8], wherein the dry etching process is performed under a temperature condition of 210°C or more and 280°C or less.

[0019]

[10] The dry etching method according to any one of [1] to [9], wherein the member to be etched has a non-etching target and the etching target, the non-etching target being not a target of etching by the etching gas,

[0020] the etching target being selectively etched as compared with the non-etching target.

[0021]

[11] The dry etching method according to

[10] , wherein the non-etching target is at least one selected from the group consisting of silicon oxide, a photoresist, and amorphous carbon.

[0022]

[12] The dry etching method according to

[10] or

[11] , wherein a ratio of an etching rate of the etching target to an etching rate of the non-etching target, that is, an etching selectivity ratio, is 5 or more.

[0023]

[13] A method of manufacturing a semiconductor element, the method of manufacturing a semiconductor element employing the dry etching method according to any one of [1] to

[12] ,

[0024] the member to be etched being a semiconductor substrate having the etching target,

[0025] the method of manufacturing including a process of removing at least a part of the etching target from the semiconductor substrate by the dry etching method.

[0026]

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

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

[0027]

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

[12] ,

[0028] the etched member is the chamber, the chamber has an adherent on an inner surface thereof, the adherent is the etching target,

[0029] the cleaning method includes a cleaning step of removing the adherent from the inner surface of the chamber using the dry etching method.

[0030] According to the present application, it is possible to etch an etching target containing copper without using plasma. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 is a schematic view of an example of an etching apparatus that explains an embodiment of the dry etching method of the present application.

[0032] Figure 2 is a view that explains a test piece used in Example 1 and the like. DETAILED DESCRIPTION

[0033] Hereinafter, an embodiment of the present application will be explained. Further, the present embodiment is an example that explains the present application, and the present application is not limited to the present embodiment. In addition, various changes or modifications can be applied in the present embodiment, and such a changed or modified embodiment can also be included in the present application.

[0034] The dry etching method of the present embodiment includes a dry etching step of bringing an etching gas containing a halogen fluoride into contact with an etched member having an etching target, and etching the etching target without using plasma, the halogen fluoride being a compound of bromine (Br) or iodine (I) and fluorine (F), and the etching target being an object to be etched by the etching gas. The etching target contains copper (Cu). Further, in the dry etching method of the present embodiment, the dry etching step is performed under a temperature condition of 140°C or higher and 300°C or lower. Hereinafter, the etching method without using plasma will also be referred to as "plasma-free etching".

[0035] When the etching gas is brought into contact with the etched member, the halogen fluoride in the etching gas reacts with the copper in the etching target, and a fluoride of copper is generated. Since the fluoride of copper has volatility, etching of the etching target is performed by volatilization of the fluoride of copper.

[0036] Therefore, the dry etching method according to this embodiment eliminates the need for plasma and enables selective etching of copper-containing objects at a sufficient etching rate. In other words, it allows for selective etching of objects compared to non-etchable objects that are not etched using etching gases. Non-etchable objects will be described in detail later.

[0037] Furthermore, according to the dry etching method of this embodiment, the object to be etched can be etched without the use of plasma, so there is no need to use an expensive plasma generator for etching. Therefore, the etching of the component can be performed at a low cost. In addition, since plasma is not used, corrosion is less likely to occur in components constituting the etching apparatus (e.g., chambers), piping connected to the etching apparatus, components constituting the semiconductor element manufacturing apparatus (e.g., chambers) described later, and piping connected to the semiconductor element manufacturing apparatus described later.

[0038] Furthermore, in the embodiments of the present invention, etching refers to removing part or all of the etched object from the etched component, processing the etched component into a predetermined shape (e.g., a three-dimensional shape) (e.g., processing a copper film-like etched object into a predetermined film thickness), and also refers to removing residues and deposits composed of the etched object from the etched component and performing cleaning and back etching, etc.

[0039] The dry etching method of this embodiment can be used for the manufacture of semiconductor devices and the cleaning of the inner surface of the cavity of a semiconductor device manufacturing apparatus.

[0040] That is, the semiconductor element manufacturing method of this embodiment is a semiconductor element manufacturing method that uses the dry etching method of this embodiment to manufacture semiconductor elements. The etched component is a semiconductor substrate having an etchable object. The manufacturing method includes a processing step of removing at least a portion of the etchable object from the semiconductor substrate using the dry etching method of this embodiment.

[0041] For example, the dry etching method of this embodiment can be used for forming copper wiring on a semiconductor substrate for semiconductor devices, or for back etching to remove excess copper film. Conventionally, copper wiring is mostly formed using wet processes with CMP (chemical mechanical polishing) paste or wet etching solutions, but dry etching using etching gases offers superior microfabrication compared to wet processes. Therefore, the dry etching method of this embodiment is expected to contribute to further miniaturization and high integration of semiconductor devices.

[0042] Furthermore, when manufacturing semiconductor devices using the dry etching method of this embodiment, if the non-etching object itself (described later) is used as the structure or resist of the semiconductor device, a material that substantially does not react with halogen fluorides or reacts very slowly with halogen fluorides is used as the non-etching object. Specific examples of such a non-etching object include at least one material selected from silicon oxide (e.g., silicon dioxide (SiO2)), photoresist, and amorphous carbon.

[0043] Furthermore, as described above, the dry etching method of this embodiment can also be used for cleaning. That is, the cleaning method of this embodiment is a cleaning method that uses the dry etching method of this embodiment to clean the inner surface of the cavity of a semiconductor device manufacturing apparatus, where the component to be etched is the cavity. The inner surface of the cavity has deposits that adhere during the operation of the semiconductor device manufacturing apparatus, and these deposits are the objects to be etched. Moreover, the cleaning method of this embodiment includes a cleaning step of removing the deposits from the inner surface of the cavity using the dry etching method of the above embodiment.

[0044] For example, after performing a process of forming a film made of a copper-containing etchable object on a semiconductor substrate in a cavity whose inner surface is made of a copper-free material, and / or etching a film made of a copper-containing etchable object formed on a semiconductor substrate, the dry etching method of this embodiment can be used to remove and clean the copper-containing deposits attached to the inner surface of the cavity.

[0045] The dry etching method, semiconductor device manufacturing method, and cleaning method of this embodiment will be described in more detail below.

[0046] [Halogen fluorides]

[0047] The type of halogen fluoride is not particularly limited as long as it is a compound of bromine or iodine and fluorine, but is preferably selected from at least one of bromine monofluoride (BrF), bromine trifluoride (BrF3), bromine pentafluoride (BrF5), iodine monofluoride (IF), iodine trifluoride (IF3), iodine pentafluoride (IF5), and iodine heptafluoride (IF7). Among these halogen fluorides, from the viewpoint of stability and ease of vaporization, it is more preferably selected from at least one of bromine trifluoride, bromine pentafluoride, iodine pentafluoride, and iodine heptafluoride, and even more preferably selected from at least one of bromine pentafluoride and iodine heptafluoride.

[0048] [Etching Gas]

[0049] The etching gas is a gas containing halogen fluorides. The etching gas can be a gas consisting solely of halogen fluorides, or it can be a mixture containing halogen fluorides and other types of gases. When the etching gas is a mixture containing halogen fluorides and other types of gases, in order to etch the object at a sufficient etching rate, the content of halogen fluorides 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. Furthermore, from the viewpoint of etching stability and ease of venting, the content of halogen fluorides 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.

[0050] When the etching gas is a mixture containing halogenated fluorides and other types of gases, it is preferable to use an inert gas as the other type of gas. That is, the etching gas can be a mixture containing halogenated fluorides and an inert gas. As the inert gas, at least one selected from nitrogen (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, and can be more than 0% by volume and less than 99% by volume. From the viewpoint of ease of processing the etching gas, it is more preferable to be more than 60% by volume and less than 97% by volume.

[0051] The oxygen (O2) content in the etching gas is preferably less than 1% by volume, more preferably less than 1000 ppm by volume, and even more preferably less than 300 ppm by volume. If the oxygen content is less than 1% by volume, it is difficult to form a copper oxide film on the copper surface, thus the etching rate of copper tends to be higher. In addition, it is less likely to cause problems such as etching residue and increased wiring resistance due to oxygen atoms diffusing from the copper oxide film into the interior.

[0052] [Pressure conditions for dry etching process]

[0053] The pressure conditions of the dry etching process in the dry etching method of 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. Preferably, it is 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.

[0054] For example, the component to be etched can be placed inside the chamber, allowing etching gas to flow through the chamber while etching occurs. The pressure inside the chamber during etching gas flow can be above 10 Pa and below 100 kPa. The flow rate of the etching gas is appropriately set according to the size of the chamber and the capacity of the exhaust equipment for depressurizing the chamber, so that the pressure inside the chamber is maintained at a constant level.

[0055] Temperature conditions for dry etching process

[0056] In this embodiment of the dry etching method, the temperature conditions for the dry etching process must be 140°C or higher and 300°C or lower. Here, the temperature condition refers to the temperature of the component being etched, but the temperature of the stage that supports the component being etched and is located within the chamber of the etching apparatus can also be used.

[0057] If the temperature conditions for the dry etching process are above 140°C, the halogen fluoride can exist in a gaseous state, and the etching rate of copper tends to be higher. Furthermore, the temperature conditions for the dry etching process are preferably above 160°C, and more preferably above 200°C. In particular, if the temperature is above 210°C, the etching rate of copper compounds increases, which can significantly contribute to improving the efficiency of the etching process.

[0058] On the other hand, if the temperature conditions of the dry etching process are below 300°C, it has advantages such as being able to perform etching without excessive time and energy, placing less load on the etching equipment and semiconductor device manufacturing equipment, and suppressing the etching of parts that should not be etched (such as non-etchable objects described later). Furthermore, the temperature conditions of the dry etching process are preferably below 280°C, and more preferably below 260°C.

[0059] Halogen fluorides show almost no reaction with non-etchable materials such as silicon oxide, photoresist, and amorphous carbon under conditions of absence of plasma and temperatures below 300°C. Therefore, when the etched component has both etchable and non-etchable materials, the dry etching method of this embodiment allows for selective etching of the etchable material with almost no etching of the non-etchable material. Consequently, the dry etching method of this embodiment can be used for methods such as using patterned non-etchable materials as masks to process the etchable material into a predetermined shape.

[0060] Furthermore, if the temperature of the object to be etched and the non-object to be etched is below 300°C, the etching selectivity tends to be higher. For example, the ratio of the etching rate of the object to be etched to the etching rate of the non-object to be etched, i.e., the etching selectivity ratio, tends to become 5 or higher. More preferably, the etching selectivity ratio is 10 or higher, and even more preferably 20 or higher.

[0061] [Etched component]

[0062] The etched component etched by the dry etching method of this embodiment may have an object etched by the etching gas, i.e., an etched object, or may have a non-etched object that is not etched by the etching gas, or may not have a non-etched object.

[0063] When the etched component has an etchable object and a non-etchable object, the etched component can be a component having a portion formed by the etchable object and a portion formed by the non-etchable object, or it can be a component formed by a mixture of the etchable object and the non-etchable object. Additionally, the etched component may also have portions other than the etchable object and the non-etchable object.

[0064] Furthermore, the shape of the etched component is not particularly limited; for example, it can be plate-shaped, foil-shaped, film-shaped, powder-shaped, or block-shaped. As an example of the etched component, the semiconductor substrate can be cited.

[0065] [Etched object]

[0066] The object to be etched by the etching gas contains copper, and may also contain at least one of copper compounds (e.g., copper oxides, copper nitrides, copper oxynitrides, copper halides) and elemental copper, wherein the copper compound contains at least one atom selected from oxygen, nitrogen, and halogen atoms, and copper. More specifically, the object to be etched may be composed of elemental copper, the copper compound, a mixture containing elemental copper, or a mixture containing the copper compound.

[0067] The copper content in the etched object is preferably 1 mol% or more, more preferably 10 mol% or more, and even more preferably 40 mol% or more. Furthermore, the overall shape of the etched object and the shape of the portion of the etched object formed solely of elemental copper are not particularly limited; for example, it can be in the form of foil, film, powder, or block.

[0068] [Non-etched objects]

[0069] As described above, the etched component may have a non-etchable object that is not etched by the etching gas. Since the non-etchable object is hardly etched in the etching method of this embodiment, it is possible to utilize the non-etchable object to suppress the etching of the etchable object by the etching gas.

[0070] Therefore, the etching method of this embodiment can be used to process a patterned non-etched object as a mask and to process the etched object into a predetermined shape (for example, to process the film-like etched object of the etched component into a predetermined film thickness), and thus can be appropriately used in the manufacture of semiconductor devices.

[0071] In addition, since the non-etched object is hardly etched, it is possible to suppress the etching of parts of the semiconductor device that should not be etched in the first place by using the non-etched object, and to prevent the semiconductor device from losing its characteristics due to etching.

[0072] The non-etched object is a material that does not substantially react with halogen fluorides or reacts with halogen fluorides very slowly, for example, at least one selected from silicon oxide, photoresist and amorphous carbon.

[0073] Photoresist refers to a photosensitive composition whose physical properties, such as solubility, change due to light or electron beams. Examples include photoresists for g-lines, h-lines, i-lines, KrF, ArF, F2, and EUV. The composition of a photoresist is not particularly limited as long as it is generally used in semiconductor manufacturing processes. For example, compositions containing polymers synthesized from at least one monomer selected from linear olefins, cyclic olefins, styrene, vinylphenol, (meth)acrylic acid, (meth)acrylates, epoxy resins, melamine, and glycols can be cited. Furthermore, (meth)acrylic acid refers to one or both of acrylic acid and methacrylic acid, and (meth)acrylates refer to one or both of acrylates and methacrylates.

[0074] Next, refer to Figure 1 This section describes an example of the structure of an etching apparatus capable of implementing the dry etching method of this embodiment and an example of a dry etching method for copper using the etching apparatus. Figure 1 The etching apparatus is a plasma-free etching apparatus that does not use plasma. First, for Figure 1 The etching apparatus will be described.

[0075] Figure 1 The etching apparatus includes a chamber 10, a stage 11, a thermometer 14, an exhaust pipe 13, a vacuum pump 15, and a pressure gauge 16. The etching is performed inside the chamber 10. The stage 11 supports the etched component 12 inside the chamber 10. The thermometer 14 measures the temperature of the etched component 12. The exhaust pipe 13 is used to exhaust the gas inside the chamber 10. The vacuum pump 15 is located in the exhaust pipe 13 and reduces the pressure inside the chamber 10. The pressure gauge 16 measures the pressure inside the chamber 10.

[0076] in addition, Figure 1 The etching apparatus includes an etching gas supply unit that supplies etching gas to the interior of the chamber 10. This etching gas supply unit comprises a halogen fluoride gas supply unit 1, an inert gas supply unit 2, a halogen fluoride gas supply pipe 5, and an inert gas supply pipe 6. The halogen fluoride gas supply unit 1 supplies halogen fluoride gas, the inert gas supply unit 2 supplies inert gas, the halogen fluoride gas supply pipe 5 connects the halogen fluoride gas supply unit 1 to the chamber 10, and the inert gas supply pipe 6 connects to the inert gas supply unit 2 at the middle of the halogen fluoride gas supply pipe 5.

[0077] Furthermore, the halogen fluoride gas supply pipe 5 is equipped with a pressure gauge 7 for measuring the pressure of the halogen fluoride gas and a halogen fluoride gas flow control device 3 for controlling the flow rate of the halogen fluoride gas. In addition, the inert gas supply pipe 6 is equipped with an inert gas pressure control device 8 for controlling the pressure of the inert gas and an inert gas flow control device 4 for controlling the flow rate of the inert gas.

[0078] Furthermore, when supplying halogenated fluoride gas as an etching gas to the chamber 10, halogenated fluoride gas is supplied to the chamber 10 via the halogenated fluoride gas supply pipe 5 by sending halogenated fluoride gas from the halogenated fluoride gas supply section 1 to the halogenated fluoride gas supply pipe 5.

[0079] Furthermore, when a mixture of halogen fluoride gas and inert gas is supplied as the etching gas, halogen fluoride gas is supplied from the halogen fluoride gas supply unit 1 to the halogen fluoride gas supply pipe 5, and inert gas is supplied from the inert gas supply unit 2 to the halogen fluoride gas supply pipe 5 via the inert gas supply pipe 6. Thus, the halogen fluoride gas and inert gas mix in the middle of the halogen fluoride gas supply pipe 5 to form a mixed gas, which is then supplied to the chamber 10 via the halogen fluoride gas supply pipe 5.

[0080] Furthermore, the structures of the halogen fluoride gas supply unit 1 and the inert gas supply unit 2 are not particularly limited; for example, they can also be gas cylinders or gas storage cylinders. In addition, the halogen fluoride gas flow control device 3 and the inert gas flow control device 4 can be, for example, mass flow controllers or flow meters.

[0081] When supplying etching gas to chamber 10, it is preferable to supply the etching gas at a pressure that is (i.e., the pressure of the etching gas supply) Figure 1 The etching gas is supplied while maintaining the value of the pressure gauge 7 in the chamber 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 even 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 etching gas to the chamber 10 proceeds smoothly, and... Figure 1 The components of the etching apparatus (e.g., the various devices or the piping) have low loads.

[0082] Furthermore, from the viewpoint of uniformly etching the surface of the etched component 12, the pressure of the etching gas supplied to the chamber 10 is preferably 50 Pa or more and 80 kPa or less, 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 selectivity ratio, i.e., the ratio of etching rate to the non-etched object, can easily become higher.

[0083] The pressure inside the chamber 10 before the etching gas is supplied is not particularly limited as long as it is below 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 less than 5 kPa.

[0084] The pressure difference between the supply pressure of the etching gas and the pressure inside the chamber 10 before the etching gas is supplied 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 etching gas can be supplied to the chamber 10 smoothly and easily.

[0085] When supplying etching gas to chamber 10, it is preferable to supply the etching gas while maintaining its temperature at a predetermined value. That is, the supply temperature of the etching gas is preferably 10°C or higher and 150°C or lower.

[0086] The temperature of the etched component 12 during etching is set to be above 140°C and below 300°C. Within this temperature range, the etching of the etched object on the etched component 12 proceeds smoothly, the load on the etching apparatus is small, and the lifespan of the etching apparatus is easily extended.

[0087] The etching processing time (hereinafter sometimes referred to as "etching time") can be arbitrarily set according to the desired degree of etching of the etched object on the etched component 12, but considering the production efficiency of semiconductor device manufacturing processes, it is preferably within 30 minutes, more preferably within 20 minutes, and even more preferably within 10 minutes. Furthermore, the etching processing time refers to the time from the introduction of etching gas into the cavity 10 to the discharge of etching gas from the cavity 10 to complete the etching process.

[0088] The dry etching method of this embodiment can be used as follows: Figure 1 The etching process is carried out using a general plasma-free etching apparatus, similar to the etching apparatus used in semiconductor device manufacturing. There are no particular limitations on the structure of the etching apparatus that can be used.

[0089] For example, the positional relationship between the halogen fluoride gas supply pipe 5 and the etched component 12 is not particularly limited as long as the etching gas can contact the etched component 12. Furthermore, the structure of the temperature control mechanism for the chamber 10 is not particularly limited as long as the temperature of the etched component 12 can be adjusted to any temperature. Therefore, the temperature control mechanism can be directly mounted on the stage 11, or it can be used to heat or cool the chamber 10 from the outside via an external temperature controller.

[0090] in addition, Figure 1The material of the etching apparatus is not particularly limited, as long as it is resistant to the halogen fluoride used and can be depressurized to a predetermined pressure. For example, in the part in contact with the etching gas, nickel, nickel-based alloys, aluminum, stainless steel, platinum, alumina, ceramics, and fluoropolymers can be used. Specific examples of nickel-based alloys include Inconel (registered trademark), Hastelloy (registered trademark), and Monel (registered trademark). Furthermore, examples of fluoropolymers include polytetrafluoroethylene (PTFE), polychlorotrifluoroethylene (PCTFE), tetrafluoroethylene-perfluoroalkoxyethylene copolymer (PFA), polyvinylidene fluoride (PVDF), Teflon (registered trademark), VITON (registered trademark), and Kalrez (registered trademark).

[0091] Example

[0092] The present invention will be described in more detail below with examples and comparative examples. Furthermore, the purity of bromine pentafluoride and iodine heptafluoride used in the following examples and comparative examples was analyzed using a Nicolet iS5 Fourier transform infrared spectrophotometer (Thermo Fisher Scientific), a U-2900 dual-beam spectrophotometer (Hitachi High Technology Scientific), and a GC-2014 gas chromatograph (Shimadzu Corporation), confirming that the purity of all was 99% by mass or higher.

[0093] (Example 1)

[0094] Using structure and Figure 1 The etching apparatus is largely the same as the one used for etching, and is used to etch the component being etched (plasma-free etching). (See reference...) Figure 2 The test piece (etched component) used in Example 1 will be described.

[0095] A component (manufactured by KST World Co., Ltd.) is prepared to form a titanium (Ti) film 22 with a thickness of 100 nm on a square silicon substrate 21 with a side length of 2 inches, and a copper film 23 with a thickness of 600 nm on the titanium film 22. A rectangular silicon dioxide substrate 24 with a size of 1 inch × 2 inches is then bonded to the copper film 23 using grease (DEMNUM GREASE L-200 manufactured by Daikin Industries, Ltd.) as a test piece. Figure 2 As shown, the silicon dioxide substrate 24 is bonded in such a way that it covers approximately half of the copper film 23.

[0096] The test piece was placed on a stage inside the etching apparatus chamber, and the stage temperature was raised to 160°C. Next, a mixed gas was formed by mixing bromine pentafluoride gas at a flow rate of 50 mL / min and argon gas at a flow rate of 450 mL / min; this mixed gas was used as the etching gas. Then, the etching gas was supplied to the chamber chamber at a flow rate of 500 mL / min and allowed to circulate for 10 minutes for etching. As a result, the exposed portions of the copper film 23 not covered by the silicon dioxide substrate 24 were etched. The internal pressure of the chamber during the etching gas flow was 10 kPa, and the partial pressure of the bromine pentafluoride gas was 1 kPa. After the etching gas flow was completed, the heating of the stage was stopped, and the interior of the chamber was purged with argon.

[0097] Furthermore, the oxygen content in the etching gas was determined by gas chromatography, and the result was less than 100 ppm by volume. The determination conditions are as follows.

[0098] Measuring instrument: GC-2014 manufactured by Shimadzu Corporation

[0099] GC column: Shincarbon ST 6m

[0100] Carrier gas: He (20 mL / min)

[0101] GC quantification loop: 5 mL

[0102] Inlet temperature: 150℃

[0103] Column temperature: 50℃

[0104] Detector: Thermal conductivity detector (TCD)

[0105] Detection temperature: 200℃

[0106] Current: 180mA

[0107] After etching, the chamber was opened, the test piece was removed, and the silicon dioxide substrate 24 was taken off the removed test piece. The bonding surface was cleaned with ethanol to remove the grease. Then, using an atomic force microscope VN-8010 manufactured by Keyence Corporation, the size of the step on the covered surface 23a of the copper film 23 covered by the silicon dioxide substrate 24 and thus not etched, and the etched surface 23b of the copper film 23 not covered by the silicon dioxide substrate 24 and thus etched, were measured. The etching rate of copper (nm / min) was calculated by dividing the measured step size (nm) by the etching time (min). The results are shown in Table 1.

[0108] Furthermore, the conditions for determining the step size obtained by atomic force microscopy are as follows.

[0109] Measurement pressure: Atmospheric pressure (101.3 kPa)

[0110] Measurement temperature: 28℃

[0111] Atmosphere measurement: In the atmosphere

[0112] Scanning range: width 80.0 μm, height 20.0 μm, angle 0°

[0113]

[0114] (Examples 2-10)

[0115] The conditions were as shown in Table 1, except that the etching of the test piece was performed in the same manner as in Example 1, and the etching rate of copper was calculated. The results are shown in Table 1.

[0116] (Example 11)

[0117] A component (manufactured by KSTWorld Co., Ltd.) with a 2000 nm thick silicon oxide film formed on a square silicon substrate with sides of 2 inches was prepared. A rectangular silicon dioxide substrate with dimensions of 1 inch × 2 inches was bonded to this silicon oxide film using grease (DEMNUMGREASE L-200 manufactured by Daikin Industries, Ltd.) to form a test piece, covering approximately half of the silicon oxide film. Furthermore, a test piece with the same copper film as in Example 1 was prepared. Then, these two test pieces were placed on a stage inside the chamber of an etching apparatus, and etching of both test pieces was performed simultaneously under the same conditions as in Example 1. The etching rates of copper and silicon oxide were calculated. The results are shown in Table 1.

[0118] (Example 12)

[0119] The 2000 nm thick silicon oxide film in Example 11 was replaced with a 300 nm thick photoresist cured film. The etching of the test piece was performed in the same manner as in Example 11, and the etching rates of copper and the photoresist cured film were calculated. The results are shown in Table 1. Furthermore, the photoresist cured film formed on the copper film 23 was formed by coating the copper film 23 with TSCR (registered trademark) photoresist manufactured by Tokyo Ohka Kogyo Co., Ltd., followed by exposure and curing.

[0120] (Example 13)

[0121] The 2000 nm thick silicon oxide film in Example 11 was replaced with a 500 nm thick amorphous carbon film. Otherwise, the test piece was etched in the same manner as in Example 11, and the etching rates of copper and amorphous carbon were calculated. The results are shown in Table 1.

[0122] (Example 14)

[0123] A copper oxide film with a thickness of 50 nm was formed on the titanium film 22 to replace the copper film 23. Otherwise, the test piece was etched in the same manner as in Example 1, and the etching rate of the copper oxide was calculated. The results are shown in Table 1. Furthermore, the copper oxide in Example 14 was copper oxide (I)(Cu₂O).

[0124] (Example 15)

[0125] A copper oxide film with a thickness of 50 nm was formed on the titanium film 22 instead of the copper film 23. Otherwise, the test piece was etched in the same manner as in Example 1, and the etching rate of the copper oxide was calculated. The results are shown in Table 1. Furthermore, the copper oxide in Example 15 was copper(II) oxide (CuO).

[0126] (Example 16)

[0127] A copper nitride (Cu3N) film with a thickness of 100 nm was formed on the titanium film 22 to replace the copper film 23. Otherwise, the test piece was etched in the same manner as in Example 1, and the etching rate of the copper nitride was calculated. The results are shown in Table 1.

[0128] (Example 17)

[0129] A mixture of bromine pentafluoride gas (50 mL / min), argon gas (445 mL / min), and oxygen gas (5 mL / min) was used as the etching gas. The etching of the test piece was performed in the same manner as in Example 1, and the etching rate of copper was calculated. The results are shown in Table 1.

[0130] (Comparative Example 1)

[0131] The stage temperature was set to 130°C. Otherwise, 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.

[0132] (Comparative Example 2)

[0133] Fluorine gas (F2 gas) was used instead of bromine pentafluoride gas, and a mixed gas of fluorine gas at a flow rate of 50 mL / min and argon gas at a flow rate of 450 mL / min was used as the etching gas. Otherwise, the etching of the test piece was performed in the same manner as in Example 1, and the etching rate of copper was calculated. The results are shown in Table 1.

[0134] (Comparative Example 3)

[0135] Plasma of etching gas is generated in the chamber, and etching is performed in the chamber by the plasma of etching gas. Normal plasma etching is performed, and the etching conditions are set as shown below. Otherwise, the etching of the test piece is performed in the same manner as in Example 1.

[0136] As test specimens, four substrates were prepared: a copper film with a thickness of 100 nm (manufactured by KST World Co., Ltd.), a silicon oxide film with a thickness of 2000 nm (manufactured by KST World Co., Ltd.), a photoresist cured film with a thickness of 300 nm formed by coating with photoresist (TSCR (registered trademark) manufactured by Tokyo Ohka Kogyo Co., Ltd.) and curing it by exposure, and an amorphous carbon film with a thickness of 500 nm (manufactured by KST World Co., Ltd.). These four test specimens were then placed on a stage inside the etching apparatus chamber, and etching was performed simultaneously on all four specimens. The etching rates of the four films were measured. The results are shown in Table 1.

[0137] The etching conditions are as follows. The etching apparatus used was a Samco RIE-800iPC parallel-plate plasma CVD system with a source power of 500 W and a bias power of 100 W. The etching gas was a mixture of bromine pentafluoride gas at a flow rate of 5 mL / min and argon gas at a flow rate of 45 mL / min. The etching time was 30 seconds, the stage temperature was 30°C, and the pressure within the chamber was 3 Pa.

[0138] (Comparative Example 4)

[0139] The halogenated fluoride was designated as iodine heptafluoride, and a mixture of iodine heptafluoride gas at a flow rate of 5 mL / min and argon gas at a flow rate of 45 mL / min was designated as the etching gas. Otherwise, the test pieces were etched in the same manner as in Comparative Example 4, and the etching rates of the four films were calculated. The results are shown in Table 1.

[0140] (Example 21)

[0141] Copper(II) fluoride powder (manufactured by Kanto Chemical Co., Ltd., average particle size 0.3 μm, purity 99.5%) was used as the etching target, and etching was performed in the same manner as in Example 1. After the etching gas flow was completed, the inside of the chamber was purged with argon gas, the etched target was removed, and the mass of the etched target was measured.

[0142] The mass reduction rate of the etched object was then calculated by dividing the mass of the etched object reduced by etching by the mass of the etched object before etching. The results are shown in Table 2.

[0143] Furthermore, the average particle size of powders such as copper(II) fluoride powder is a volume-based average particle size, which was measured using a Partica LA-960 laser diffraction / scattering particle size distribution measuring device manufactured by Horiba Corporation.

[0144]

[0145] (Example 22)

[0146] The halogenated fluoride was designated as iodine heptafluoride, and a mixture of iodine heptafluoride gas at a flow rate of 50 mL / min and argon gas at a flow rate of 450 mL / min was used as the etching gas. Etching was performed in the same manner as in Example 21, and the mass reduction rate of the etched object was calculated. The results are shown in Table 2.

[0147] (Comparative Example 11)

[0148] Fluorine gas was used instead of bromine pentafluoride gas, and a mixture of fluorine gas at a flow rate of 50 mL / min and argon gas at a flow rate of 450 mL / min was used as the etching gas. Otherwise, etching was performed in the same manner as in Example 21, and the mass reduction rate of the etched object was calculated. The results are shown in Table 2.

[0149] (Example 23)

[0150] Copper bromide (I) powder (manufactured by NACALAI TESQUE Co., Ltd., average particle size 0.5 μm, purity 97.5%) was used instead of copper fluoride (II) powder as the etching target. Otherwise, etching was performed in the same manner as in Example 21, and the mass reduction rate of the etched object was calculated. The results are shown in Table 2.

[0151] (Example 24)

[0152] The halogenated fluoride was designated as iodine heptafluoride, and a mixture of iodine heptafluoride gas at a flow rate of 50 mL / min and argon gas at 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 etched object was calculated. The results are shown in Table 2.

[0153] (Comparative Example 12)

[0154] Fluorine gas was used instead of bromine pentafluoride gas, and a mixture of fluorine gas at a flow rate of 50 mL / min and argon gas at a flow rate of 450 mL / min was used as the etching gas. Otherwise, etching was performed in the same manner as in Example 23, and the mass reduction rate of the etched object was calculated. The results are shown in Table 2.

[0155] (Example 25)

[0156] Copper iodide (I) powder (manufactured by NACALAI TESQUE Co., Ltd., average particle size 0.7 μm, purity 99.5%) was used instead of copper fluoride (II) powder as the etching target. Otherwise, etching was performed in the same manner as in Example 21, and the mass reduction rate of the etched object was calculated. The results are shown in Table 2.

[0157] (Example 26)

[0158] The halogenated fluoride was designated as iodine heptafluoride, and a mixture of iodine heptafluoride gas at a flow rate of 50 mL / min and argon gas at 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 etched object was calculated. The results are shown in Table 2.

[0159] (Comparative Example 13)

[0160] Fluorine gas was used instead of bromine pentafluoride gas, and a mixture of fluorine gas at a flow rate of 50 mL / min and argon gas at a flow rate of 450 mL / min was used as the etching gas. Otherwise, etching was performed in the same manner as in Example 25, and the mass reduction rate of the etched object was calculated. The results are shown in Table 2.

[0161] The results of Examples 1, 2, and 3 show that the higher the temperature of the stage, the higher the etching rate of copper.

[0162] The results of Examples 2, 4, and 5 show that the higher the proportion of halogen fluorides in the etching gas, the higher the etching rate of copper.

[0163] The results of Examples 2, 6, and 7 show that the higher the internal pressure of the chamber, the higher the etching rate of copper. This is believed to be because the partial pressure of the halogen fluoride gas inside the chamber increases, the contact frequency between the copper surface and the halogen fluoride increases, and the conversion rate of copper to etching products (reaction products generated as a result of copper being etched) increases.

[0164] The results of Examples 8 and 9 show that copper etching can be performed without problems even when nitrogen or helium is used as an inert gas.

[0165] As can be seen from the results of Example 10, even when iodine heptafluoride is used as the etching gas, the etching of copper proceeds without any problems.

[0166] The results of Examples 11, 12, and 13 show that, when copper and the non-etched object are present in the same chamber, copper etching occurs selectively. These results demonstrate that, by employing the dry etching method of the present invention, copper can be etched selectively compared to the non-etched object.

[0167] The results of Examples 14, 15, and 16 demonstrate that etching of copper oxide and copper nitride is possible. Furthermore, these results indicate that the dry etching method of the present invention can also be applied to the removal of natural oxide and nitride films on copper surfaces.

[0168] As can be seen from the results of Example 17, the etching rate of copper decreases slightly when the etching gas contains oxygen.

[0169] As can be seen from the results of Comparative Example 1, copper etching is difficult to perform when the stage temperature is outside the range of the present invention.

[0170] The results of Comparative Example 2 show that copper etching is difficult to perform when fluorine gas is used as the etching gas.

[0171] The results of Comparative Examples 3 and 4 show that in plasma etching, although copper is etched, non-etched objects are also etched at the same time.

[0172] As can be seen from the results of Examples 21-26, the etching of copper halides (copper fluoride, copper bromide, copper iodide) can be carried out without any problems using the dry etching method of the present invention.

[0173] On the other hand, the results of Comparative Examples 11, 12, and 13 show that when fluorine gas is used as the etching gas, the etching of copper halide is difficult to perform.

[0174] Explanation of reference numerals in the attached figures

[0175] 1…Halogen fluoride gas supply department

[0176] 2…Inert gas supply section

[0177] 3…Halogen fluoride gas flow control device

[0178] 4…Inert gas flow control device

[0179] 5…Pipes for supplying halogenated fluoride gases

[0180] 6… Piping for inert gas supply

[0181] 7, 16… pressure gauges

[0182] 8…Inert gas pressure control device

[0183] 10…chamber

[0184] 11…Platform

[0185] 12…etched components

[0186] 13…Exhaust piping

[0187] 14…Thermometer

[0188] 15…vacuum pump

[0189] 21…Silicon substrate

[0190] 22…Titanium film

[0191] 23… Copper film

[0192] 24…Silicon dioxide substrate

Claims

1. A dry etching method comprising a dry etching step of contacting an etching gas containing a halogen fluoride with an etched member having an etching object and an unetched object, the halogen fluoride being at least one of bromine pentafluoride and iodine heptafluoride, the etched member having the etching object and the unetched object, the unetched object being an object not etched by the etching gas, the etching object being an object etched by the etching gas, the etching object containing copper, the unetched object being at least one selected from the group consisting of silicon oxide, a photoresist, and amorphous carbon, the dry etching step being performed at a temperature of 140°C or higher and 300°C or lower, and the etching object being selectively etched compared with the unetched object.

2. The dry etching method according to claim 1, wherein the etching gas is a gas composed of only the halogen fluoride, 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 the group consisting of nitrogen, helium, argon, neon, krypton, and xenon.

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

5. The dry etching method according to any one of claims 1 to 3, wherein a content of oxygen contained in the etching gas is 1 vol% or less.

6. The dry etching method according to any one of claims 1 to 3, wherein the dry etching step is performed at a pressure of 50 Pa or more and 80 kPa or less.

7. The dry etching method according to any one of claims 1 to 3, wherein the etching object contains at least one of a copper compound and copper single substance, the copper compound containing at least one of an oxygen atom, a nitrogen atom, and a halogen atom and copper.

8. The dry etching method according to any one of claims 1 to 3, wherein the dry etching step is performed at a temperature of 210°C or higher and 280°C or lower.

9. The dry etching method according to any one of claims 1 to 3, wherein a ratio of an etching rate of the etching object to an etching rate of the unetched object, that is, an etching selectivity ratio, is 5 or more.

10. A method of manufacturing a semiconductor element, the method of manufacturing a semiconductor element using the dry etching method according to any one of claims 1 to 9, the etched member being a semiconductor substrate having the etching object, the method of manufacturing a semiconductor element comprising a processing step of removing at least a part of the etching object from the semiconductor substrate using the dry etching method.

11. The method of manufacturing a semiconductor element according to claim 10, wherein a copper wiring is formed on the semiconductor substrate by the processing step.

12. A cleaning method of cleaning an inner surface of a chamber of a manufacturing apparatus for a semiconductor element using the dry etching method according to any one of claims 1 to 9. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The etching target member is the chamber having an adherent attached to an inner surface thereof as a manufacturing device of the semiconductor element is operated, and the adherent is the etching target object, The cleaning method includes a cleaning step of removing the adherent from the inner surface of the chamber by the dry etching method.

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