Patent Description:
As magnetic materials and wiring line materials constituting semiconductor elements, such as non-volatile memory elements, transition metal elements, such as iron (Fe), cobalt (Co), nickel (Ni), selenium (Se), molybdenum (Mo), rhodium (Rh), palladium (Pd), tungsten (W), rhenium (Re), iridium (Ir), and platinum (Pt) are used in some cases. In a semiconductor element production step, a sputtering method or a wet etching method is used in some cases when a metal thin film on a substrate is etched to form wiring lines. <CIT> Al discloses a dry etching method for etching a metal element using no plasma, a chamber cleaning method, wherein the metal deposits are removed (etched), and a semiconductor element manufacturing method. The dry etching method for etching a metal element comprises contacting a fluorine-containing interhalogen compound processing gas with the metal element to generate a metal fluoride; and then heating the metal fluoride under an inert gas atmosphere or in a vacuum environment to vaporize the metal fluoride.

However, the sputtering method or the wet etching method has posed a risk of etching even a part of the semiconductor element which should basically not be etched, resulting in a loss of the characteristics of the semiconductor element.

PTL <NUM> discloses a method for dry etching a metal thin film on a substrate using an etching gas excited by plasma, but the etching method using plasma has had a problem of high cost.

It is an object of the present invention to provide a metal removal method, a dry etching method, and a production method for a semiconductor element, which can be implemented at a low cost.

According to the present invention, metal removal and dry etching can be carried out at a low cost.

The present invention will now be described below.

As a result of various examinations to solve the above-described problem, the present inventors have found that a fluoride-containing interhalogen compound is brought into contact with a metal element, such as W or Ir, to generate metal fluoride which is a reaction product of the metal element and the fluoride-containing interhalogen compound, and then the metal fluoride is heated in a reduced pressure environment or the like to volatilize the metal fluoride, thereby enabling the removal of a metal-containing material containing the metal element, and thus have completed the present invention.

A metal removal method according to the present invention includes a reaction step of bringing a treatment gas containing a fluorine-containing interhalogen compound and a metal-containing material containing a metal element into contact with each other to generate metal fluoride which is a reaction product of the fluorine-containing interhalogen compound and the metal element and a volatilization step of heating the metal fluoride under an inert gas atmosphere or in a vacuum environment for volatilization. The metal element contained in the metal-containing material is at least one kind selected from the group consisting of iron, cobalt, nickel, selenium, molybdenum, rhodium, palladium, tungsten, rhenium, iridium, and platinum. In the metal removal method, the metal may be removed by alternately repeating the reaction step and the volatilization step. Alternatively, the reaction step and the volatilization step may be performed at the same time.

In the reaction step, the fluorine-containing interhalogen compound (e.g., BrF<NUM>) in the treatment gas reacts with the metal element contained in the metal-containing material to generate metal fluoride which is presumed to be a fluorine-containing halogen-containing metal complex (e.g., [BrF<NUM>][MF<NUM>]), in which M is a metal element). Therefore, a remarkable mass increase arises in the metal-containing material. Such metal fluoride has a vapor pressure higher than that of simple substances, oxides, nitrides, and the like of the metal elements, and therefore is volatilized and removed by heating in the volatilization step.

The metal removal method of the present invention has no necessity of bringing the fluorine-containing interhalogen compound into an excited state, such as plasma, and therefore metal removal can be carried out at a low cost and corrosion is unlikely to occur in a reaction vessel, piping, and the like used in the metal removal method.

According to the metal removal method of the present invention, even stable metals, such as iron, cobalt, nickel, selenium, molybdenum, rhodium, palladium, tungsten, rhenium, iridium, and platinum, can be easily removed.

By the use of the metal removal method of the present invention, metal deposits can be removed from members or devices for cleaning. For example, when metal deposits containing the metal elements mentioned above are deposited on the inner surface of a chamber (for example, a chamber constituting a semiconductor producing device) in which a reaction involving the metal elements mentioned above, such as Ir and W, is performed, the metal deposits deposited on the inner surface of the chamber can be removed (cleaned) at a low cost by implementing the metal removal method of this embodiment in the chamber. For example, in the case of a chamber constituting a semiconductor producing device, the above-described cleaning may be performed as a post-step of a step of forming a metal-containing material containing the metal elements mentioned above on a semiconductor substrate to form a metal-containing layer or a post step after a step of etching the metal-containing layer.

Dry etching is performed utilizing the metal removal method of the present invention.

A semiconductor element can be produced using the dry etching method of the present invention. A production method for a semiconductor element according to another aspect of the present invention includes a dry etching step of removing at least one portion of a metal-containing layer containing at least one kind of metal element selected from the group consisting of iron, cobalt, nickel, selenium, molybdenum, rhodium, palladium, tungsten, rhenium, iridium, and platinum from a semiconductor substrate having the metal-containing layer by the above-described dry etching method.

The metal-containing layer is formed on the semiconductor substrate, a mask having a predetermined pattern is formed on the metal-containing layer, and then the etching is performed by the above-described dry etching method. Then, one part of the metal-containing layer is removed from the semiconductor substrate, and the pattern mentioned above is transferred to the metal-containing layer, so that wiring lines or the like can be formed on the semiconductor substrate.

The production method for a semiconductor element of the present invention has no necessity of using plasma, and therefore a semiconductor element can be produced at a low cost. When a wet etching method is adopted, there is a problem that even a part of the semiconductor element which should basically not be etched may be etched, resulting in a loss of the characteristics of the semiconductor element. However, in the production method for a semiconductor element of the present invention, the metal-containing layer is removed by the dry etching method, and therefore the above-described problem is unlikely to occur.

Hereinafter, the metal removal method of the present invention is described in more detail.

The metal-containing material containing the metal elements may be simple metal of the metal elements mentioned above, may be a compound of the metal elements mentioned above (for example, metal oxides, metal nitrides, metal halides, metal salts), or may be an alloy of two or more kinds of the metal elements mentioned above.

The metal-containing material containing the metal elements may contain only the simple metals, compounds, and alloys mentioned above or may contain other components. More specifically, the metal-containing material containing the metal elements may be a mixture of at least one of the simple metals, compounds, and alloys mentioned above and other components. Examples of this mixture include alloys of the metal elements mentioned above and different kinds of metal elements and compositions containing at least one of the simple metals, compounds, and alloys mentioned above and other components. In this mixture, the composition ratio of the simple metals, compounds, and alloys mentioned above is preferably <NUM>% by mass or more and more preferably <NUM>% by mass or more.

The shape of the metal-containing material containing the metal elements is not particularly limited and may be a thin film shape, a foil shape, a powder shape, or a lump shape.

The type of the fluorine-containing interhalogen compound is not particularly limited and at least one kind selected from the group consisting of chlorine monofluoride (ClF), bromine monofluoride (BrF), chlorine trifluoride (ClF<NUM>), iodine trifluoride (IF<NUM>), chlorine pentafluoride (ClF<NUM>), bromine pentafluoride (BrF<NUM>), and iodine heptafluoride (IF<NUM>) is usable. Among the above-described fluorine-containing interhalogen compounds, bromine pentafluoride and iodine heptafluoride are more preferable.

The reaction temperature of the fluorine-containing interhalogen compound and the metal element in the reaction step needs to be a temperature at which the fluorine-containing interhalogen compound contained in the treatment gas can be present in a gaseous state (temperature equal to or more than the boiling point of the fluorine-containing interhalogen compound). The reaction temperature of the fluoride-containing interhalogen compound and the metal element in the reaction step is preferably <NUM> or more and <NUM> or less, more preferably <NUM> or more and <NUM> or less, and still more preferably <NUM> or more and <NUM> or less.

When the reaction temperature is within the ranges mentioned above, the reaction rate of the reaction between the fluoride-containing interhalogen compound and the metal element is likely to be sufficiently high, and, in addition thereto, a reaction between the fluorine-containing interhalogen compound and substances other than the metal elements mentioned above (for example, substances which should basically not be reacted) is unlikely to occur.

When a fluorine gas is used, highly volatile metal fluoride can be generated and removed by a reaction between the fluorine gas and the metal elements. However, when plasma is not used, a high temperature of <NUM> or more is required for the reaction between the fluorine gas and the metal elements mentioned above. Under such a high temperature condition, the fluorine gas may react with silicon, silicon oxide, and the like (equivalent to the "substances which should basically not be reacted"), making it difficult to apply the metal removal method and the dry etching method of this embodiment to a semiconductor element production step.

The treatment gas used in the reaction step may be formed only of the fluorine-containing interhalogen compound or may be a mixed gas containing the other kinds of gases. When the treatment gas is a mixed gas, the concentration of the fluorine-containing interhalogen compound in the treatment gas is preferably <NUM> vol% or more, more preferably <NUM> vol% or more, and still more preferably <NUM> vol% or more in order to obtain a sufficient reaction rate.

As the other kinds of gases used when the treatment gas is a mixed gas, at least one kind of inert gas selected from the group consisting of nitrogen gas (N<NUM>), helium (He), neon (Ne), argon (Ar), krypton (Kr), and xenon (Xe) is usable. The concentration of the inert gas in the treatment gas can be set in the range of <NUM> vol% or more and <NUM> vol% or less, for example.

The atmospheric pressure in the reaction step is not particularly limited and can be set to <NUM> kPa or more and <NUM> kPa or less, for example. The flow rate of the treatment gas may be determined as appropriate within a range where the atmospheric pressure can be kept constant according to the size of a reaction vessel and the capacity of an evacuator for reducing the pressure inside the reaction vessel.

The volatilization step is carried out by heating the metal fluoride under an inert gas atmosphere or in a vacuum environment.

The heating temperature of the metal fluoride in the volatilization step is preferably set to be higher than the reaction temperature of the fluoride-containing interhalogen compound and the metal element in the reaction step in order to rapidly volatilize the metal fluoride. For example, the heating temperature of the metal fluoride in the volatilization step is set to preferably a temperature higher by <NUM> or more, more preferably a temperature higher by <NUM> or more, and still more preferably a temperature higher by <NUM> or more than the reaction temperature of the fluoride-containing interhalogen compound and the metal element in the reaction step.

The heating temperature of the metal fluoride in the volatilization step is not particularly limited insofar as the metal fluoride can be volatilized and is preferably <NUM> or more and <NUM> or less, more preferably <NUM> or more and <NUM> or less, still more preferably <NUM> or more and <NUM> or less, and yet still more preferably <NUM> or more and <NUM> or less.

When the heating temperature of the metal fluoride in the volatilization step is within the ranges mentioned above, the volatilization rate of the metal fluoride is likely to be sufficiently high, and, in addition thereto, the time and the energy required for the volatilization of the metal fluoride are unlikely to be excessive.

As the inert gas, at least one kind selected from the group consisting of nitrogen gas, helium, neon, argon, krypton, and xenon is usable, for example. The inert gas atmosphere is preferably an atmosphere in which the inert gas is circulated at a pressure of <NUM> kPa or more and <NUM> kPa or less. The vacuum environment in the volatilization step is preferably an environment in which the pressure is reduced to <NUM> Pa or more and <NUM> Pa or less.

The fluorine-containing interhalogen compound, such as BrF<NUM>, in a non-excited state hardly reacts with silicon oxides and silicon nitrides at temperatures equal to or less than <NUM>. Therefore, when the treatment gas is brought into contact with both a silicon-containing material containing at least one of silicon oxides and silicon nitrides and the metal-containing material containing the metal elements mentioned above in the reaction step, the silicon-containing material containing at least one of silicon oxides and silicon nitrides is hardly removed, and the metal-containing material containing the metal elements mentioned above is selectively removed.

Therefore, when the dry etching using the metal removal method of the invention is applied to the semiconductor substrate having the metal-containing layer containing the metal elements mentioned above and the silicon-containing layer containing at least one of silicon oxides and silicon nitrides, a semiconductor element can be produced with at least one part of the metal-containing layer being etched and with the silicon-containing layer being hardly etched.

Hereinafter, the present invention is described in more detail by illustrating Examples, Comparative Examples, and Reference Examples. First, the structure of a reactor <NUM> used in Examples, Comparative Examples, and Reference Examples is described with reference to <FIG>.

The reactor <NUM> in <FIG> is provided with a chamber <NUM> in which the reaction is carried out. In this chamber <NUM>, a stage <NUM> on which a sample <NUM> is placed is installed. The chamber <NUM> is provided with a gas introduction port <NUM> introducing a treatment gas (hereinafter, a gas reacting with metal among treatment gases is sometimes referred to as "etching gas") into the chamber <NUM>, a gas discharge port <NUM> discharging the treatment gas and the metal fluoride from the inside of the chamber <NUM>, a pressure reducing device (not illustrated) reducing the pressure inside the chamber <NUM>, and a pressure gauge <NUM> measuring the pressure inside the chamber <NUM>.

The stage <NUM> further has a function as a heating device, and thus the sample <NUM> on the stage <NUM> can be heated to a desired temperature. The reactor <NUM> is further provided with a heating device (not illustrated) heating the outer wall of the chamber <NUM>, and thus the inside of the chamber <NUM> can be controlled to a desired temperature.

The sample <NUM> is placed on the stage <NUM>, and then heat is applied by at least one of the stage <NUM> and the above-described heating device and the treatment gas is introduced into the chamber <NUM> from the gas introduction port <NUM> are performed. Then, the treatment gas is brought into contact with the sample <NUM> under a predetermined temperature condition, so that metal of the sample <NUM> reacts with the treatment gas. Thereafter, in order to volatilize metal fluoride generated in the reaction, the inside of the chamber <NUM> is reset to a predetermined temperature, and then a gas containing the metal fluoride is discharged from the gas discharge port <NUM> to the outside of chamber <NUM> to be removed. It may be acceptable that, during the removal of the metal fluoride, the treatment gas is always introduced from the gas introduction port <NUM> into the chamber <NUM> and the gas discharge port <NUM> is opened to discharge a gas containing the treatment gas or the metal fluoride to the outside of the chamber <NUM>.

Dry etching of metal can be performed using the reactor <NUM> and using the treatment gas as the etching gas. By the dry etching of metal using the reactor <NUM>, a metal thin film (metal-containing layer) on a semiconductor substrate having a silicon-containing material can be etched to form wiring lines, and therefore the reactor <NUM> is usable for producing a semiconductor element.

Next, metal removal treatment of Examples, Comparative Examples, and Reference Examples performed using the reactor <NUM> is described.

Ir powder (manufactured by Furuya Metal Co. , average particle size of <NUM>, purity of <NUM>%), which is the sample <NUM>, was placed on the stage <NUM>, and then the sample <NUM> was heated to <NUM> by the stage <NUM>. BrF<NUM>, which is the treatment gas, was discharged to the outside of the chamber <NUM> having an internal volume of <NUM><NUM> from the gas discharge port <NUM> while introducing BrF<NUM> into the chamber <NUM> from the gas introduction port <NUM>, thereby circulating the treatment gas in the chamber <NUM> (reaction step). The treatment gas was circulated for <NUM> minutes at a flow rate of <NUM> sccm. The pressure inside the chamber <NUM> was set to <NUM> kPa. Herein, sccm is the volumetric flow rate (cm<NUM>) per minute standardized under the condition of <NUM> and <NUM> atm.

When the circulation of the treatment gas was completed, the pressure inside the chamber <NUM> was reduced to <NUM> Pa or less and the sample <NUM> was heated to <NUM> by the stage <NUM> (volatilization step). The heating of the sample <NUM> was performed for <NUM> minutes, the inside of the chamber <NUM> was replaced with nitrogen gas, the sample <NUM> was taken out, and then the mass of the sample <NUM> was measured. Then, the mass reduction rate of the sample <NUM> was calculated by the following expression. The results are shown in Table <NUM>.

The average particle size of powder, such as the Ir powder, was determined on a volume basis by a laser diffraction/scattering particle size distribution analyzer Partica LA-<NUM> manufactured by Horiba Ltd.

The metal removal treatment was performed in the same manner as in Example <NUM>-<NUM>, except that the etching gas was set to IF<NUM>, and then the mass reduction rate was calculated. The result is shown in Table <NUM>.

The metal removal treatment was performed in the same manner as in Example <NUM>-<NUM>, except that the reaction temperature in the reaction step was set to <NUM> and the pressure inside the chamber <NUM> was set to <NUM>-<NUM> MPa, and then the mass reduction rate was calculated. The result is shown in Table <NUM>.

The metal removal treatment was performed in the same manner as in Example <NUM>-<NUM>, except that the reaction temperature in the reaction step was set to <NUM>, and then the mass reduction rate was calculated. The result is shown in Table <NUM>.

The metal removal treatment was performed in the same manner as in Example <NUM>-<NUM>, except that the etching gas and the flow rate were set to BrF<NUM>/Ar = <NUM> sccm/<NUM> sccm, and then the mass reduction rate was calculated. The result is shown in Table <NUM>.

The metal removal treatment was performed in the same manner as in Example <NUM>-<NUM>, except that the etching gas and the flow rate were set to BrF<NUM>/He = <NUM> sccm/<NUM> sccm, and then the mass reduction rate was calculated. The result is shown in Table <NUM>.

The metal removal treatment was performed in the same manner as in Example <NUM>-<NUM>, except that the etching gas and the flow rate were set to BrF<NUM>/N<NUM> = <NUM> sccm/<NUM> sccm, and then the mass reduction rate was calculated. The result is shown in Table <NUM>.

The metal removal treatment was performed in the same manner as in Example <NUM>-<NUM>, except that the etching gas and the flow rate were set to IF<NUM>/Ar = <NUM> sccm/<NUM> sccm, and then the mass reduction rate was calculated. The result is shown in Table <NUM>.

The metal removal treatment was performed in the same manner as in Example <NUM>-<NUM>, except that the etching gas and the flow rate were set to IF<NUM>/He = <NUM> sccm/<NUM> sccm, and then the mass reduction rate was calculated. The result is shown in Table <NUM>.

The metal removal treatment was performed in the same manner as in Example <NUM>-<NUM>, except that the etching gas and the flow rate were set to IF<NUM>/N<NUM> = <NUM> sccm/<NUM> sccm, and then the mass reduction rate was calculated. The result is shown in Table <NUM>.

The metal removal treatment was performed in the same manner as in Example <NUM>-<NUM>, except that the etching gas was set to F<NUM>, and then the mass reduction rate was calculated. The result is shown in Table <NUM>.

The metal removal treatment was performed in the same manner as in Example <NUM>-<NUM>, except that the volatilization step was not carried out and, after the completion of the reaction step, the inside of the chamber <NUM> was replaced with nitrogen gas, the sample <NUM> was taken out, and then the mass of the sample <NUM> was measured, and then the mass reduction rate was calculated. The result is shown in Table <NUM>.

W powder (manufactured by The Nilaco Corporation, average particle size of <NUM>, purity of <NUM>%) was used as the sample <NUM> and the treatment was performed under the conditions shown in Table <NUM>. The results are shown in Table <NUM>.

Se powder (manufactured by NACALAI TESQUE, INC. , average particle size of <NUM>, purity of <NUM>%) was used as the sample <NUM> and the treatment was performed under the conditions shown in Table <NUM>. The results are shown in Table <NUM>.

Mo powder (manufactured by A. , average particle size of <NUM>, purity of <NUM>%) was used as the sample <NUM> and the treatment was performed under the conditions shown in Table <NUM>. The results are shown in Table <NUM>.

Rh powder (manufactured by Kojundo Chemical Lab. , average particle size of <NUM>, purity of <NUM>%) was used as the sample <NUM> and the treatment was performed under the conditions shown in Table <NUM>. The results are shown in Table <NUM>.

Pd powder (manufactured by Aida chemical Industries Co. , average particle size of <NUM>, purity of <NUM>%) was used as the sample <NUM> and the treatment was performed under the conditions shown in Table <NUM>. The results are shown in Table <NUM>.

Re powder (manufactured by New Metals and Chemicals Corporation, Ltd. , average particle size of <NUM>, purity of <NUM>%) was used as the sample <NUM> and the treatment was performed under the conditions shown in Table <NUM>. The results are shown in Table <NUM>.

Pt powder (manufactured by The Nilaco Corporation, average particle size of <NUM>, purity of <NUM>%) was used as the sample <NUM> and the treatment was performed under the conditions shown in Table <NUM>. The results are shown in Table <NUM>.

Fe powder (manufactured by The Nilaco Corporation, average particle size of <NUM>, purity of <NUM>%) was used as the sample <NUM> and the treatment was performed under the conditions shown in Table <NUM>. The results are shown in Table <NUM>.

Co powder (manufactured by Merck, average particle size of <NUM>, purity of <NUM>%) was used as the sample <NUM> and the treatment was performed under the conditions shown in Table <NUM>. The results are shown in Table <NUM>.

Ni powder (manufactured by The Nilaco Corporation, average particle size of <NUM>, purity of <NUM>%) was used as the sample <NUM> and the treatment was performed under the conditions shown in Table <NUM>. The results are shown in Table <NUM>.

The metal removal treatment was performed in the same manner as in Example <NUM>-<NUM>, except that SF<NUM>, NF<NUM>, SiF<NUM>, CF<NUM>, CHF<NUM>, or a mixture of each of the etching gases and NH<NUM> was used as the etching gas. A mass reduction was not observed in each case of using any of the etching gases. In addition, when the treatment was performed by changing the temperature condition in the reaction step from <NUM> to <NUM> or <NUM> or when the temperature condition in the volatilization step was changed from <NUM> to <NUM> or <NUM>, a reduction in the mass of the Ir powder was not observed. These results were all the same not only when the Ir powder was used as the sample <NUM> but when W, Se, Mo, Rh, Pd, Re, Pt, Fe, Co, and Ni powders were used.

SiO<NUM> powder (manufactured by Marutou CO. , average particle size of <NUM>, purity of <NUM>%) was used as the sample <NUM> and the treatment was performed under the conditions shown in Table <NUM>. The results are shown in Table <NUM>.

Si<NUM>N<NUM> powder (manufactured by UBE INDUSTRIES, LTD. , average particle size of <NUM>, purity of <NUM>%) was used as the sample <NUM> and the treatment was performed under the conditions shown in Table <NUM>. The results are shown in Table <NUM>.

As is understood from Examples <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, and <NUM>-<NUM>, the etching of Ir was able to be achieved by performing the reaction at <NUM> or <NUM> using BrF<NUM> or IF<NUM> as the etching gas in the reaction step and performing the heating to <NUM> in the vacuum environment in the volatilization step.

On the other hand, as is understood from Comparative Example <NUM>-<NUM>, when F<NUM> was used as the etching gas in the reaction step, the etching of Ir did not proceed. As is understood from Comparative Example <NUM>-<NUM>, even in the case of using BrF<NUM> as the etching gas, when only the reaction step was performed without performing the volatilization step, Ir was not be able to be etched and the mass of the sample <NUM> increased.

As is understood from the results of Examples <NUM>-<NUM> to <NUM>-<NUM>, the etching of Ir was able to be achieved even when the treatment gas in which inert gas was mixed with BrF<NUM> or IF<NUM> was used in the reaction step.

As is understood from Examples <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, the etching of W, Mo, Rh, Re, and Pt was able to be achieved by performing the reaction using BrF<NUM> or IF<NUM> as the etching gas at <NUM> in the reaction step and performing the heating to <NUM> in the vacuum environment in the volatilization step.

On the other hand, as is understood from Comparative Examples <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, when F<NUM> was used as the etching gas in the reaction step, the etching of W, Mo, Rh, Re, and Pt did not proceed.

As is understood from Examples <NUM>-<NUM>, <NUM>-<NUM>, the etching of Se was able to be achieved by performing the reaction using BrF<NUM> or IF<NUM> as the etching gas at <NUM> in the reaction step and performing the heating to <NUM> in the vacuum environment in the volatilization step.

On the other hand, as is understood from Comparative Example <NUM>-<NUM>, when F<NUM> was used as the etching gas in the reaction step, the etching of Se did not proceed.

As is understood from Examples <NUM>-<NUM>, <NUM>-<NUM>, the etching of Pd was able to be achieved by performing the reaction using BrF<NUM> or IF<NUM> as the etching gas at <NUM> in the reaction step and performing the heating to <NUM> in the vacuum environment in the volatilization step.

On the other hand, as is understood from Comparative Example <NUM>-<NUM>, when F<NUM> was used as the etching gas in the reaction step, the etching of Pd did not proceed.

As is understood from Examples <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, the etching of Fe, Co, and Ni was able to be achieved by performing the reaction using BrF<NUM> or IF<NUM> as the etching gas at <NUM> in the reaction step and performing the heating to <NUM> in the vacuum environment in the volatilization step.

On the other hand, as is understood from Comparative Examples <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, when F<NUM> was used as the etching gas in the reaction step, the etching of Fe, Co, and Ni did not proceed.

As is understood from Reference Examples <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, when the reaction was performed at <NUM> using BrF<NUM> or IF<NUM> as the etching gas in the reaction step, the etching of SiO<NUM> and Si<NUM>N<NUM> did not proceed.

As is understood from Reference Examples <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, also when the reaction was performed at <NUM> using BrF<NUM> or IF<NUM> as the etching gas in the reaction step, the etching of SiO<NUM> and Si<NUM>N<NUM> only slightly proceeded.

The results above show that, when the metal removal treatment of each of Examples described above is performed, Fe, Co, Ni, Se, Mo, Rh, Pd, W, Re, Ir, and Pt can be selectively etched without etching SiO<NUM> or Si<NUM>N<NUM>.

The metal removal treatment, i.e., etching, was applied to the sample <NUM> of Example <NUM>-<NUM>, Example <NUM>-<NUM>, and Comparative Example <NUM> using the reactor <NUM> in <FIG>. The sample <NUM> used in Example <NUM>-<NUM>, Example <NUM>-<NUM>, and Comparative Example <NUM> is described with reference to <FIG>.

One was prepared in which a tungsten film <NUM> having a thickness of <NUM> was formed on a square silicon substrate <NUM> having a side of <NUM> in. (manufactured by KST World Corp. ), and a rectangular silicon dioxide substrate <NUM> having a dimension of <NUM> in. × <NUM> in. was bonded onto the tungsten <NUM> using grease (Demnum Grease L-<NUM> manufactured by Daikin Industries, Ltd. ), and the resultant substance was used as the sample <NUM>. The silicon dioxide substrate <NUM> was bonded to cover substantially the half of the tungsten film <NUM> as illustrated in <FIG>. The tungsten film <NUM> is the target to be removed, i.e., the target to be etched, and the silicon dioxide substrate <NUM> was used as a resist.

The etching was performed using the sample <NUM> under the conditions shown in Table <NUM>. The conditions other than the conditions shown in Table <NUM> are the same as those of Example <NUM>-<NUM>. When the etching was completed, the chamber was opened to take out the sample <NUM>, the silicon dioxide substrate <NUM> was removed from the taken-out sample <NUM>, and the bonded surface was cleaned with ethanol to remove the grease. Then, the size of a level difference between a covered surface 22a of the tungsten film <NUM> which was covered with the silicon dioxide substrate <NUM> and was not etched and an etched surface 22b of the tungsten film <NUM> which was not covered with the silicon dioxide substrate <NUM> and was etched was measured using an atomic force microscope VN-<NUM> manufactured by KEYENCE CORPORATION. The tungsten etching rate (nm/min) was calculated by dividing the measured level difference size (nm) by etching time (min). The results are shown in Table <NUM>.

The measurement conditions of the size of the level difference by the atomic force microscope are as follows.

Claim 1:
A metal removal method comprising:
a reaction step of bringing a treatment gas containing a fluorine-containing interhalogen compound and a metal-containing material containing a metal element into contact with each other to generate metal fluoride which is a reaction product of the fluorine-containing interhalogen compound and the metal element; and
a volatilization step of heating the metal fluoride under an inert gas atmosphere or in a vacuum environment for volatilization, wherein
the metal element is at least one kind selected from the group consisting of iron, cobalt, nickel, selenium, molybdenum, rhodium, palladium, tungsten, rhenium, iridium, and platinum.