DESCRIPTION

ETCHING APPARATUS AND ETCHING METHOD TECHNICAL FIELD

[0001]

The present invention relates to an etching apparatus and an etching method.

BACKGROUND ART

[0002]

Conventionally, as a method for etching metals, an RIE (Reactive Ion Etching) using a chlorine gas is known. In the RIE using a chlorine gas, a substrate is heated to a high temperature and thereafter etching is performed. In addition, there is a dry etching method performed on a copper oxide film by using an organic acid.

[0003] Patent Document 1: Japanese Laid-open Patent Publication No. 2010-27788

DISCLOSURE OF INVENTION

PROBLEM TO BE SOLVED BY THE INVention

[0004]

However, in the technology described above, there is a problem in that it is difficult to appropriately etch a structure with a noble metal layer or a transition metal layer. For example, because it is necessary to heat a substrate to a high temperature in the RIE using a chlorine gas, the RIE is not applicable to a device that is weak against heat. In addition, it is impossible to etch noble metals because an appropriate etching method for noble metals has not been developed.

[0005]

The disclosed technology has been made in view of the above circumstances, and an object thereof is to provide an etching apparatus and an etching method capable of

appropriately etching a structure with a noble metal layer or a transition metal layer.

MEANS FOR SOLVING PROBLEM

[0006]

The etching method according to one embodiment of the disclosed technology includes a depressurizing process for depressurizing a chamber in which a structure with a noble metal layer or a transition metal layer is disposed.

Furthermore, the etching method of another embodiment includes an etching process for etching the structure by applying a gas cluster ion beam to the structure disposed in the chamber depressurized through the depressurizing process.

EFFECT OF THE INVENTION

[0007]

According to one embodiment of the etching apparatus disclosed herein, it is possible to appropriately etch a structure with a noble metal layer or a transition metal layer .

BRIEF DESCRIPTION OF DRAWINGS

[0008]

FIG. 1 is a cross-sectional view illustrating an overall configuration of an etching apparatus according to a first embodiment.

FIG. 2 is a diagram illustrating an example of another configuration of an organic compound gas supply unit according to the first embodiment.

FIG. 3 is a diagram illustrating an example of a structure of a substrate S with a noble metal layer or a transition metal layer according to the first embodiment.

FIG. 4 is a diagram illustrating an example of the flow of an etching process performed by the etching

apparatus according to the first embodiment.

FIG. 5 is a diagram illustrating a relationship of etching depths with predetermined ion irradiance between a case where etching was performed under vacuum and a case where etching was performed while supplying an acetic acid, on condition that the etching was performed by using an oxygen gas cluster ion beam or an argon gas cluster ion beam.

FIG. 6 is a diagram illustrating etching depths when various materials were etched by using the oxygen gas cluster ion beam.

FIG. 7 is a diagram illustrating an XPS measurement result obtained in Example 29.

FIG. 8 is a diagram illustrating the XPS measurement result obtained in Example 29.

BEST MODE(S) OF CARRYING OUT THE INVENTION

[0009]

Preferred embodiments of an etching apparatus and an etching method disclosed herein will be explained in detail below with reference to accompanying drawings. The present invention is not limited to the embodiments below. The embodiments can be arbitrarily combined within a scope that does not contradict the processing contents.

[0010]

(Etching apparatus according to a first embodiment) An etching apparatus according to a first embodiment includes, as one embodiment, a chamber in which a structure with a noble metal layer or a transition metal layer is disposed, a depressurizing unit that depressurizes the chamber, and an etching unit that etches the structure by- applying a gas cluster ion beam to the structure disposed in the chamber depressurized by the depressurizing unit.

[0011]

In the etching apparatus according to the first embodiment, as one embodiment, the etching unit applies, as the gas cluster ion beam, an oxygen gas or a mixed-gas cluster ion beam that is based on a mixture of an oxygen gas and an argon gas .

Furthermore, in the etching apparatus according to the first embodiment, as one embodiment, the structure includes a stack layer of a noble metal or a transition metal.

Furthermore, in the etching apparatus according to the first embodiment, as one embodiment, the noble metal or the transition metal is selected from a group consisting of gold, silver, platinum, palladium, rhodium, iridium, ruthenium, osmium, tantalum, tungsten or a metal alloy thereof .

[0012]

Furthermore, the etching apparatus according to the first embodiment includes, as one embodiment, an organic compound gas supply unit that supplies an organic compound gas to the inside of the chamber. Moreover, the etching unit applies a gas cluster ion beam to a structure disposed in the chamber, which is depressurized by the

depressurizing unit and in which the organic compound gas is supplied by the organic compound gas supply unit.

[0013]

Furthermore, in the etching apparatus according to the first embodiment, the etching unit applies a gas cluster ion beam to a structure coated with a mask. Moreover, for example, the etching apparatus according to the first embodiment etches a magnetic layer of the structure. [0014]

FIG. 1 is a cross -sectional view illustrating an overall configuration of an etching apparatus according to the first embodiment. An etching apparatus 1 is a gas cluster ion beam radiation device for applying a gas cluster ion beam (GCIB: Gas Cluster Ion Beam) to a

substrate.

[0015]

The etching apparatus 1 includes a source chamber 2 and a target chamber 3. In the source chamber 2 , a gas serving as a source gas is ejected and a cluster flow is generated. In the target chamber 3, a substrate S as a target of etching is disposed. In the target chamber 3, the cluster flow generated in the source chamber 2 is used as a cluster beam and etching is performed by applying the cluster beam to the substrate S as a target. The source chamber 2 and the target chamber 3 are separated from each other by a partition wall 4.

[0016]

The etching apparatus 1 includes a GCIB radiation mechanism 10. The GCIB radiation mechanism 10 includes a nozzle 5, a nozzle pipe 6, a skimmer 7, an ionizer 11, an accelerator 12, a first aperture 13, a permanent magnet 14, and a second aperture 15. The etching apparatus 1 also includes vacuum pumps 21 and 22, an organic compound gas supply unit 30, a manometer 34, and a control unit 40.

[0017]

The GCIB radiation mechanism 10 applies a gas cluster ion beam to a structure disposed in a depressurized chamber to thereby etch the structure. The GCIB radiation

mechanism 10 may be referred to as "the etching unit".

[0018]

The nozzle 5 is arranged inside the source chamber 2 and is connected to the nozzle pipe 6 through which a gas is supplied from a gas source located outside the source chamber 2. The nozzle 5 ejects a gas flow. The pressure of the gas ejected from the nozzle 5 is controlled by a regulator not illustrated in FIG. 1. A few to tens of thousands of molecules of the gas ejected from the nozzle 5 are aggregated and form clusters due to the van der Waals' force. The nozzle pipe 6 is connected to the nozzle 5 arranged inside the source chamber 2. The nozzle pipe 6 supplies the gas to the nozzle.

[0019]

The skimmer 7 is arranged inside the source chamber 2 so as to face the nozzle 5. The skimmer 7 is arranged on the partition wall 4 so as to protrude toward the nozzle 5 side, includes an aperture through which the cluster flow ejected from the nozzle 5 passes, and prevents shock waves. The cluster flow is introduced into the target chamber 3 through the aperture of the skimmer 7.

[0020]

The ionizer 11 includes a plurality of annular

electrodes. The annular electrodes of the ionizer 11 are arranged inside the target chamber 3 along the cluster flow introduced from the source chamber 2. The ionizer 11 ionizes the cluster flow. The accelerator 12 is arranged on the downstream side of the ionizer 11 inside the target chamber 3. In the target chamber 3, the cluster flow is ionized by the ionizer 11 and accelerated by the

accelerator 12, so that a gas cluster ion beam (GCIB) is produced.

[0021]

The first aperture 13, the permanent magnet 14, and the second aperture 15 are arranged on the downstream side of the accelerator 12 inside the target chamber 3. The first aperture 13 and the second aperture 15 adjust the diameter of the GCIB. The permanent magnet 14 bends the orbits of low-mass particles, such as monomer ions or low- mass cluster particles, so that the GCIB with an

appropriate size passes through the second aperture 15.

[0022]

An XY stage 20 is arranged on the downstream side of the second aperture 15 inside the target chamber 3. The XY stage 20 holds the substrate S and scans the substrate S two-dimensionally. The substrate S is introduced and removed via, for example, an entrance (not illustrated) arranged inside the target chamber 3. The entrance

arranged in the target chamber 3 can be opened and closed by a gate valve not illustrated in FIG. 1.

[0023]

The etching apparatus 1 includes the vacuum pumps 21 and 22. The vacuum pumps 21 and 22 reduce the pressure inside the chamber in which a structure with a noble metal layer or a transition metal layer is disposed.

Specifically, the vacuum pumps 21 and 22 perform vacuuming in the source chamber 2 and the target chamber 3 ,

respectively, to thereby create a predetermined level of vacuum inside the source chamber 2 and the target chamber 3. The vacuum pumps 21 and 22 may be referred to as a

depressurizing unit.

[0024]

The organic compound gas supply unit 30 supplies an organic compound gas to the target chamber 3. The organic compound gas supply unit 30 includes a storage container 31 for storing an organic compound, a pipe 32 for guiding an organic compound gas that is generated by evaporation in the storage container 31 due to vacuuming in the target chamber 3 into the target chamber 3, and a flow adjustment valve 33 arranged on the pipe 32. An end of the pipe 32 serves as a nozzle 32a for guiding the organic compound gas to the vicinity of the substrate S. In the example

illustrated in FIG. 1, a case is illustrated in which the nozzle 32a is provided near the substrate S; however, the present invention is not limited to this example. For example, an acetic acid (CH ₃ COOH) is stored as an organic compound in the storage container 31, and the acetic acid is vaporized and supplied to the vicinity of the substrate S.

[0025]

As the organic compound, any material may be employed as long as the material can be supplied, as it is or as a gas by being heated, to the target chamber 3 under vacuum. For example, an organic acid may be used. As the organic acid, a carboxylic acid may be used (general formula: R- COOH (R is hydrogen or a straight-chain or branched C1-C20 alkyl group or alkenyl group, or more preferably, methyl, ether, propyl, butyl, pentyl, or hexyl) ) that is

represented by, for example, an acetic acid as described above. Examples of the carboxylic acid other than the acetic acid include a formic acid (HCOOH) , a propionic acid (CH ₃ CH ₂ COOH) , a butyric acid (CH ₃ (CH ₂ ) ₂ COOH) , and a valeric acid (CH ₃ (CH ₂ ) 3COOH) . Among the carboxylic acids, a formic acid (HCOOH) , an acetic acid (CH ₃ COOH) , and a propionic acid (CH ₃ CH ₂ COOH) are much preferable. It may also be possible to use alcohol or other organic compounds.

[0026]

The manometer 34 measures the pressure in a region where a substrate is arranged in the target chamber 3. The manometer 34 is, for example, an ion gauge or a capacitance manometer. A pressure control unit 35 adjusts the flow adjustment valve 33 so that the pressure measured by the manometer 34 reaches a predetermined value. The supply- amount of the organic compound gas may be set to an

arbitrary amount as long as organic compound molecules can be adsorbed on the surface of the substrate S. The

pressure inside the target chamber 3, in other words, the partial pressure of the organic compound gas is preferably set to, for example, 10 ^~2 to 1CT ⁴ pascal.

[0027]

In the etching apparatus according to the first

embodiment, heat needed for the etching is supplied by collision of the GCIB. In addition, the substrate S is maintained at a normal temperature without being heated. Therefore, the organic compound supplied to the target chamber 3 is more likely to be adsorbed compared with the case where the substrate S is heated. Consequently, it becomes possible to set the partial pressure of the organic compound in the target chamber 3 to a low value, such as 10 ^~2 to 10 ^~4 pascal order.

[0028]

Furthermore, in the etching apparatus according to the first embodiment, etching is performed without heating.

Therefore, unlike a method including heating of a substrate, it becomes possible to etch a material that is weak against heat. For example, it is possible to etch a material of an MRAM (Magnetoresistive Random Access Memory) without

exceeding a Curie temperature of 250 degrees.

[0029]

FIG. 2 is a diagram illustrating an example of another configuration of the organic compound gas supply unit of the first embodiment. In the example illustrated in FIG. 2, the organic compound gas supply unit 30 includes an

intermediate container 36 and a tank 37 for storing an organic compound, and a valve 37a is provided on a pipe 36a that connects the intermediate container 36 and the tank 37. In the example illustrated in FIG. 2, the organic compound is supplied from the intermediate container 36 to the target chamber 3 via the pipe 32, and a variable leak valve 38 is provided on the pipe 32. In addition, a sensor, such as a fluid level sensor 39, for detecting the amount of the organic compound in the intermediate container 36 is

provided in the intermediate container 36, and detects the amount of the organic compound gas in the intermediate container 36. If the fluid level is lowered and the fluid level sensor 39 detects the fluid level, the variable leak valve 38 enables isolation from the vacuum region, and the valve 37a is opened so as to supply the organic compound from the tank 37 to the intermediate container 36.

[0030]

The etching apparatus 1 also includes the control unit 40 that controls the entire apparatus. The control unit 40 controls, for example, ejection of a gas from the nozzle 5, controls the ionizer 11, the accelerator 12, and the

apertures 13 and 15, controls scanning of the substrate S by the XY stage 20, controls supply of the organic compound gas, and controls discharge of air from the vacuum pumps 21 and 22.

[0031]

The control unit 40 includes, for example, an ASIC (Application Specific Integrated Circuit) , an FPGA (Field Programmable Gate Array) , a CPU (Central Processing Unit) , an MPU (Micro Processing Unit) , and the like. The control unit 40 also includes, in the example illustrated in FIG. 1, a controller 41, a user interface 42, and a storage unit 43. The controller 41 controls each of the units of the etching apparatus 1. The user interface 42 provides an interface to a user and receives instructions from the user. [0032]

The storage unit 43 stores therein data used for various types of processing. The storage unit 43 may be, for example, a semiconductor memory device such as a RAM (Random Access Memory) , a ROM (Read Only Memory) , or a flash memory (Flash Memory) , or may be a hard disk, an optical disk, or the like. The storage unit 43 stores therein, for example, a control program, i.e., a processing recipe, for causing each of the constituting units of the etching apparatus 1 to perform predetermined processing according to processing conditions.

[0033]

For example, when receiving an instruction from a user, the control unit 40 performs etching based on the received instruction. The processing recipe may be transmitted from other devices instead of being stored in the storage unit 43 of the control unit 40.

[0034]

The structure as a target of etching by the etching apparatus 1 will be explained below. FIG. 3 is a diagram illustrating an example of the substrate S with a noble metal layer or a transition metal layer according to the first embodiment. In the structure, a metal, such as a platinum group element or an iron group element is

deposited. The substrate S as the structure with a noble metal layer or a transition metal layer is, for example, an MRAM material. In the example illustrated in FIG. 3, an underlayer 101, a first deposited layer 102, a first magnetic layer 103, a tunnel barrier layer 104, a second magnetic layer 105, a second deposited layer 106, and a mask layer 107 are deposited in this order.

[0035]

The underlayer 101 is made of, for example, silicon. Each of the first deposited layer 102 and the second deposited layer 106 is a layer on which at least one type of a noble metal or a transition metal is deposited. For example, each of the first deposited layer 102 and the second deposited layer 106 includes at least one type of a noble metal. The first deposited layer 102 and the second deposited layer 106 may be made of different metals or may be made of the same metal .

[0036]

The first magnetic layer 103 and the second magnetic layer 105 are made of, for example, CoFe (cobalt iron) . The tunnel barrier layer 104 is made of, for example, MgO (magnesium oxide) . The mask layer 107 is made of an arbitrary material that cannot be etched while the first deposited layer 102, the second deposited layer 106, the first magnetic layer 103, the tunnel barrier layer 104, and the second magnetic layer 105 are etched by using a gas cluster ion beam. For example, the mask layer 107 is made of silicone nitride (SiN) , silicone dioxide (Si0 ₂ ) , or titanium nitride (TiN) . In the example illustrated in FIG. 3, the substrate S is formed such that the first magnetic layer 103 and the second magnetic layer 105 sandwiching the tunnel barrier layer 104 are sandwiched between the first deposited layer 102 and the second deposited layer 106 on both of which the noble metal or the transition metal is deposited.

[0037]

A metal that forms the first deposited layer 102 and the second deposited layer 106 will be explained in detail below. The noble metal is, for example, gold (Au) , silver (Ag) , platinum (Pt) , palladium (Pd) , rhodium (Rh) , iridium (Ir) , ruthenium (Ru) , or osmium (Os) . The noble metal that forms the first deposited layer 102 or the second deposited layer 106 of the substrate S is preferably platinum or ruthenium. The transition metal that forms the first deposited layer 102 or the second deposited layer 106 is, for example, tantalum, tungsten or the like. For example, the first deposited layer 102 or the second deposited layer 106 includes at least the noble metal. In other words, the etching apparatus 1 etches the structure on which at least the noble metal is deposited.

[0038]

FIG. 4 is a diagram illustrating an example of the flow of an etching process performed by the etching

apparatus according to the first embodiment. As

illustrated in FIG. 4, when receiving an instruction from a user (YES at Step S101) , the etching apparatus 1 reduces the pressure inside the chamber in which a structure with a noble metal layer or a transition metal layer is disposed (Step S102) . For example, the control unit 40 causes the vacuum pumps 21 and 22 to perform vacuuming in the source chamber 2 and the target chamber 3, respectively, so that a predetermined level of vacuum is created inside the source chamber 2 and the target chamber 3.

[0039]

The etching apparatus 1 supplies an organic compound gas to the inside of the chamber (Step S103) . For example, the control unit 40 controls the organic compound gas supply unit 30 so as to vaporize the acetic acid stored in the storage container 31 and supply the gas to the vicinity of the structure disposed inside the target chamber 3.

[0040]

The etching apparatus 1 applies a gas cluster ion beam to the structure disposed inside the depressurized chamber to thereby etch the structure (Step S104) . For example, the control unit 40 controls the GCIB radiation mechanism 10 so as to apply the oxygen gas cluster ion beam to the structure inside the target chamber 3 which is

depressurized and in which the organic compound gas is supplied.

[0041]

The above processing procedure does not necessarily have to be performed in the order as described above, and the order may be changed appropriately within a scope that does not contradict the processing contents. For example, Steps S102 and S103 as described above may be performed in parallel. Furthermore, in the example illustrated in FIG. 4, a case has been illustrated that a series of processes is performed upon reception of an instruction from a user; however, the present invention is not limited to this example. It may be possible to start the processes at an arbitrary timing as a trigger. For example, it may be possible to perform the series of processes when the structure is disposed in the target chamber 3.

[0042]

(Etching method according to the first embodiment) An example of an etching method performed by the etching apparatus 1 to etch the structure with a noble metal layer or a transition metal layer will be explained below.

[0043]

The etching method according to the first embodiment includes, as one embodiment, a depressurizing process for reducing the pressure inside the chamber in which the structure with a noble metal layer or a transition metal layer is disposed. For example, the gate valve of the target chamber 3 is opened to introduce the substrate S via the entrance (not illustrated) and holds the substrate S by the XY stage 20. Subsequently, the etching apparatus 1 reduces the pressure inside the chamber in which the structure with a noble metal layer or a transition metal layer is disposed. More specifically, the vacuum pumps 21 and 22 perform vacuuming in the source chamber 2 and the target chamber 3, respectively, to create a high-level vacuum .

[0044]

Furthermore, the etching method according to the first embodiment includes, as one embodiment, an organic compound gas supply process for supplying an organic compound gas to the inside of the chamber. For example, a vacuum is created in the target chamber 3, so that the organic compound inside the storage container 31 is evaporated and the gas is supplied to the target chamber 3. For example, if an acetic acid is stored in the storage container 31, an acetic acid gas is supplied to the target chamber 3.

[0045]

At this time, the pressure control unit 35 controls the degree of openness of the flow adjustment valve 33 based on a measurement value of the manometer 34 to control the amount of evaporation of the organic compound so that the pressure of the organic compound gas inside the target chamber 3 becomes, for example, a predetermined value of 10 ^"2 to 10 ^"4 pascal order. Meanwhile, a heating means is not provided in the XY stage 20, and the substrate S is held at a normal temperature without being heated and organic compound molecules are adsorbed on the surface of the substrate S, that is, on the surface of the second magnetic layer 105.

[0046]

The etching method according to the first embodiment also includes, as one embodiment, an etching process for applying a gas cluster ion beam to the structure disposed in the chamber depressurized through the depressurizing process to thereby etch the structure. Specifically, the etching apparatus 1 applies the gas cluster ion beam to the structure with a noble metal layer or a transition metal layer.

[0047]

For example, in the etching process, the gas cluster ion beam is applied to the structure disposed in the

chamber, which is depressurized through the depressurizing process and in which the organic compound gas is supplied through the organic compound gas supply process . For another example, in the etching process, the gas cluster ion beam is applied to the structure provided with a

patterned mask. For still another example, in the etching process, an oxygen gas cluster ion beam is applied as the gas cluster ion beam.

[0048]

For example, in the etching apparatus 1, the nozzle 5 in the source chamber 2 ejects a gas to generate a cluster flow, and the cluster flow is applied as the GCIB to the substrate S supported by the XY stage 20 in the target chamber 3.

[0049]

Incidentally, the gas cluster ion beam has the

straightness, so that anisotropic etching becomes possible. In addition, in the gas cluster ion beam, each cluster is formed such that a few to tens of thousands of molecules are loosely bounded by the van der Waals' force and is large in size. Therefore, when the clusters collide with the structure, the clusters can hardly be introduced into the structure and the collision energy acts on a surface portion of the structure where a reaction occurs.

Consequently, in the etching using the gas cluster ion beam, it becomes possible to reduce the damage on the base of the structure .

[0050]

Furthermore, as described above, by reducing the supply amount of the organic compound or by applying the gas cluster ion beam under vacuum, it is possible to reduce the possibility that the clusters of the gas cluster ion beam collide with the organic compound, so that the high reaction efficiency can be achieved. Moreover, it is not needed to heat the substrate, so that the acetic acid gas molecules can easily be adsorbed on the surface. Therefore, the supply amount of the acetic acid gas can be reduced, and at the same time, a cluster ion can be applied under high vacuum. Namely, it is possible to simultaneously perform cluster ion application and acetic acid gas

introduction.

[0051]

To form the GCIB, the cluster flow supplied from the source chamber 2 to the target chamber 3 is ionized by the ionizer 11 and accelerated by the accelerator 12, so that the GCIB is obtained. The beam diameter of the GCIB is adjusted while the GCIB passes through the first aperture 13 and the second aperture 15, and low-mass particles are eliminated from the beam pathway by the permanent magnet 14, so that the size of the cluster can be controlled

appropriately. The GCIB whose beam diameter and whose cluster size are controlled is applied to the substrate S, so that the substrate S is etched.

[0052]

As described above, an acetic acid as an organic compound is supplied to the inside of the target chamber 3, and the substrate S is irradiated with the GCIB while the substrate S is maintained at a normal temperature without being heated. Therefore, it becomes possible to perform anisotropic etching on the deposited layer of the substrate S. Moreover, it becomes possible to etch a noble metal, such as Pt or Ru, a noble metal alloy, a high melting point metal, such as Ta or , or a transition metal, such as CoFe, at high speed. Furthermore, the etching is performed without using a halogen, so that it becomes possible to omit a post cleaning process after etching.

[0053]

(Mechanism for etching)

The mechanism for etching a noble metal will be

briefly explained below. For example, in the case of platinum, lighter and smaller oxygen penetrates the inside of a membrane, so that a metallic bond is broken and the platinum as a simple substance or a cluster is discharged into a space. Consequently, the etching proceeds.

Furthermore, in the case of ruthenium, there is a known reaction such that Ru + 0 ₂ —> Ru0 ₄ .

[0054]

The mechanism for etching a transition metal will be briefly explained below. The transition metal is oxidized by being irradiated with an oxygen gas cluster ion beam and reacts with an acetic acid. The energy needed at this time is supplied from the heat energy obtained by radiation of the gas cluster ion beam. The acetic acid surrounds the metal oxide and is discharged into a space from a solid, so that the etching proceeds. Meanwhile, the acetic acid is illustrated by way of example only.

[0055]

As for an insulator, when the energy of the cluster is 20 keV, lighter elements are slightly subjected to physical sputter etching. The insulator is inactive against an oxygen cluster or an acetic acid gas, and therefore, it can be regarded that a chemical reaction does not occur.

[0056]

(Other Embodiments)

The etching apparatus and the etching method according to the first embodiment have been explained above; however, the present invention is not limited to the first

embodiment. For example, in the embodiment described above, an example is illustrated in which the substrate is etched at a normal temperature without being heated; however, the present invention is not limited to this example. For example, the substrate may be cooled.

[0057]

Specifically, the etching apparatus may further

include a cooling unit that cools the structure, and the etching unit may apply the gas cluster ion beam to the structure cooled by the cooling unit. In this case, the possibility that the organic compound supplied to the target chamber 3 exists on the surface of the substrate increases compared with the case where a normal temperature is used. Therefore, the etching efficiency can be improved. Furthermore, the cooling unit may be mounted on the XY stage and cool the substrate S mounted on the XY stage.

[0058]

Furthermore, for example, the mechanism for radiating the GCIB, the radiation condition, and the method for supplying the organic compound are not limited to those described in the above embodiment, and an arbitrary

embodiment may be applied. Moreover, in the embodiment described above, an example has been explained that a noble metal or a transition metal serving as an MRAM material is used as a target of etching; however, the present invention is not limited to this example. For example, a noble metal or a transition metal serving as a material of an arbitrary semiconductor device may be used as a target of etching.

[0059]

Moreover, in the embodiment described above, an example has been explained that oxygen or argon is applied independently as a gas applied as the gas cluster ion beam; however, the present invention is not limited to this example. For example, it may be possible to mix two or more types of gases at an arbitrary ratio and apply the mixed gas. For example, when oxygen is applied, it may be possible to mix argon with oxygen and apply the mixed gas. For example, the mixing ratio of oxygen and argon may be 1:1. Alternatively, oxygen may be mixed with argon of 0.5% or at an arbitrary ratio. It may also be possible to use a gas based on materials other than oxygen and argon.

[0060]

Furthermore, in the embodiment described above, an example has been explained in which the organic compound gas is supplied to the chamber, and the gas cluster ion beam is applied to the structure disposed in the chamber which is depressurized and in which the organic compound gas is supplied; however, the present invention is not limited to this example. For example, it may be possible to apply a gas cluster ion beam without supplying the organic compound gas .

[0061]

Moreover, in the embodiment described above, an example has been explained that the etching is performed by applying the gas cluster ion beam; however, the present invention is not limited to this example. For example, it may be possible to perform etching by ion milling.

Furthermore, when performing the ion milling, it may be possible to perform etching on the organic compound under atmosphere. For example, it may be possible to perform etching by the ion milling while supplying an acetic acid.

[0062]

The etching method of the disclosed technology will be explained in detail below with reference to Examples.

However, the etching method of the disclosed technology is not limited to the Examples described below.

[0063]

(Examples 1 to 4)

A substrate, in which a film made of a noble metal or transition metal X is formed on the surface by

electrodeposition, was disposed in the target chamber, and a vacuum was created in the target chamber. Subsequently, the substrate was maintained at a normal temperature

without being heated and etched by applying an oxygen gas cluster ion beam. The conditions used to apply the oxygen gas cluster ion beam were as follows.

[0064]

Accelerating voltage Va of an accelerator: 20 kV

Dose of the oxygen gas cluster ion beam: 2xl0 ¹⁶

(ions/cm ² )

Ionized electron voltage: 185 V

[0065]

As the noble metal or transition metal X in Examples 1 to 4, the following metals were used.

Example 1: Pt (platinum)

Example 2: Ru (ruthenium)

Example 3: Ta (tantalum)

Example 4: CoFe (cobalt iron)

[0066]

After the etching was performed, the depth etched by application of the oxygen gas cluster ion beam was measured. The measurement conditions were as follows.

Measurement device: surface profiler Dektak 3 manufactured by Veeco Instruments Inc.

At the measurement, the gas cluster ion beam was applied across a patterned stainless mask, and the initial height that was not etched because of being covered with the mask and the height of a bottom surface that was etched because of not being covered with the mask were measured by the surface profiler.

[0067]

(Examples 5 to 8)

A substrate, in which a film made of a noble metal or transition metal X is formed on the surface by

electrodeposition, was disposed in the target chamber, and a vacuum was created in the target chamber. Subsequently, the substrate was maintained at a normal temperature without being heated, an acetic acid was supplied to the vicinity of the substrate, and the substrate was etched by applying an oxygen gas cluster ion beam. The conditions used to apply the oxygen gas cluster ion beam were as follows .

[0068]

Accelerating voltage Va of the accelerator: 20 kV Dose of the oxygen gas cluster ion beam: 2xl0 ¹⁶

(ions/cm ² )

Ionized electron voltage: 185 V

Partial pressure of the acetic acid in the target chamber: 5xl0 ^"3 Pa (pascal)

[0069]

In Examples 5 to 8, the following metals were used as the noble metal or transition metal X.

Example 5 : Pt (platinum)

Example 6: Ru (ruthenium)

Example 7: Ta (tantalum)

Example 8: CoFe (cobalt iron) [0070]

After the etching was performed, the depth of the substrate etched by application of the oxygen gas cluster ion beam was measured. The measurement conditions were as follows .

Measurement device: surface profiler Dektak3

manufactured by Veeco Instruments Inc.

At the measurement, the gas cluster ion beam was applied across a patterned stainless mask, and the initial height that was not etched because of being covered with the mask and the height of a bottom surface that was etched because of not being covered with the mask were measured by the surface profiler.

[0071]

(Examples 9 to 16)

In Examples 9 to 16, unlike Examples 1 to 8 , an argon gas cluster ion beam was used instead of the oxygen gas cluster ion beam. In examples 9 to 16, other conditions were the same as those of Examples 1 to 8.

[0072]

(Result in Examples 1 to 16)

FIG. 5 is a diagram illustrating a relationship of etching depths with predetermined ion irradiance between a case where etching was performed under vacuum and a case where etching was performed while supplying an acetic acid, on condition that the etching was performed by using the oxygen gas cluster ion beam or the argon gas cluster ion beam.

[0073]

As illustrated in FIG. 5, by applying the oxygen gas cluster ion beam in the vacuum state, platinum group elements such as platinum and ruthenium, tantalum, and an iron group element such as cobalt iron were etched. Furthermore, by applying the oxygen gas cluster ion beam while supplying an acetic acid, platinum, ruthenium, tantalum, and cobalt iron were etched deeper than in the vacuum state.

[0074]

Furthermore, as illustrated in FIG. 5, by applying the argon gas cluster ion beam, ruthenium, tantalum, and cobalt iron were etched. Moreover, by applying the argon gas cluster ion beam while supplying an acetic acid, ruthenium, tantalum, and cobalt iron were etched deeper than in the vacuum state. When the argon gas cluster ion beam was applied, platinum was hardly etched in both of the vacuum state and the acetic acid supply state.

[0075]

Moreover, as illustrated in FIG. 5, in the case of etching platinum, ruthenium, and cobalt iron, the etching depths were the greatest when the oxygen gas cluster ion beam was applied while supplying an acetic acid.

Furthermore, in the case of etching tantalum, the etching depth was the greatest when the argon gas cluster ion beam was applied while supplying an acetic acid.

[0076]

Furthermore, as illustrated in FIG. 5, tantalum was etched even when the oxygen gas cluster ion beam was

applied while supplying an acetic acid. Therefore, as illustrated in FIG. 5, all of platinum, ruthenium, tantalum, and cobalt iron could be etched by applying the oxygen gas cluster ion beam while supplying an acetic acid.

[0077]

(Examples 17 to 22)

In Examples 17 to 22, unlike Examples 1 to 4 , a

substrate, in which a film made of a material Y was formed on the surface by electrodeposition was disposed in the target chamber. In Examples 17 to 22, other conditions are the same as those of Examples 1 to 8.

[0078]

In Examples 17 to 22, the following materials were used as the material Y.

Example 17: SiN (silicon nitride)

Example 18: thermally-oxidized Si0 ₂ (silicon dioxide) Example 19: TiN (titanium nitride)

Example 20: C (carbon)

Example 21: (tungsten)

Example 22: PVD (Physical Vapor Deposition) - Cu

(copper)

[0079]

(Examples 23 to 28)

In Examples 23 to 28, unlike Examples 5 to 8 , a substrate, in which a film made of the material Y was formed on the surface by electrodeposition, was disposed in the target chamber. In Examples 23 to 28, other conditions are the same as those of Examples 1 to 8. In addition, as described below, the material Y used in Examples 23 to 28 are the same as the material Y used in Examples 17 to 22, respectively.

[0080]

Specifically, in Examples 23 to 28, the following materials were used as the material Y.

Example 23: SiN (silicon nitride)

Example 24: thermally-oxidized Si0 ₂ (silicon dioxide) Example 25: TiN (titanium nitride)

Example 26: C (carbon)

Example 27: W (tungsten) ^■

Example 28: PVD (Physical Vapor Deposition) - Cu

(copper)

[0081] (Result in Examples 17 to 28)

FIG. 6 is a diagram illustrating etching depths obtained when various materials were etched by using the oxygen gas cluster ion beam. In the example illustrated in FIG. 6, for convenience of explanation, the results in Examples 1 to 8 are also illustrated. Specifically, the etching depths obtained by applying the oxygen gas cluster ion beam to the noble metal or transition metal under vacuum or with the supply of an acetic acid are also illustrated.

[0082]

As illustrated in FIG. 6, the etching depths of SiN and Si0 ₂ are lower than the etching depths of the noble metals and the transition metals. Therefore, it can be seen that these materials are effective as a material of a mask used to etch the noble metals or the transition metals by applying the gas cluster ion beam.

[0083]

For example, in the case of etching platinum,

ruthenium, and cobalt iron by applying the oxygen gas cluster ion beam, the etching depth of SiN or Si0 ₂ was lower than the depths of platinum, ruthenium, and cobalt iron in both of the vacuum state and the acetic acid supply state. Therefore, it can be seen that, in the case of etching platinum, ruthenium, or cobalt iron by applying the oxygen gas cluster ion beam, it is effective to use SiN or Si0 ₂ as the mask in both of the vacuum state and the acetic acid supply state.

[0084]

Furthermore, for example, in the case of etching tantalum by applying the oxygen gas cluster ion beam, the etching depth of SiN or Si0 ₂ was lower than the etching depth of tantalum in the acetic acid supply state. Therefore, it can be seen that, in the case of etching tantalum, it is effective use SiN or Si0 ₂ as the mask in the acetic acid supply state.

[0085]

As a result, as illustrated in FIG. 6, when applying the oxygen gas cluster ion beam while supplying an acetic acid, it is possible to etch platinum, ruthenium, tantalum, and cobalt iron by using SiN or Si0 ₂ as the mask.

[0086]

(Example 29)

A substrate, in which CoFe (cobalt iron) was formed on the surface by PVD (physical vapor deposition, was disposed in the target chamber, and a vacuum was created in the target chamber. Subsequently, an oxygen gas cluster ion beam was applied to the substrate at a room temperature without heating the substrate, and then XPS measurement was performed. In Example 29, the partial pressure of the acetic acid gas was set to 4xl0 ^-6 Torr (5xl0 ^~4 Pa) .

[0087]

(Comparative Examples 1 and 2)

In Comparative Example 1, a substrate, in which CoFe (cobalt iron) was formed on the surface by PVD (physical vapor deposition, was disposed in the target chamber, and a vacuum was created in the target chamber. Subsequently, XPS measurement was performed. In Comparative Example 2, unlike Example 29, an argon gas cluster ion beam was applied to the substrate for 30 seconds without supplying an acetic acid gas, and thereafter, XPS measurement was performed. The other conditions in Comparative example 2 were the same as those of Example 29.

[0088]

(Result in Example 29)

FIG. 7 and FIG. 8 are diagrams illustrating an XPS measurement result obtained in Example 29. In FIG. 7 and FIG. 8, the vertical axis represents a relative intensity and the horizontal axis represents a binding energy. In FIG. 7, biding energies corresponding to Fe ₂ 0 ₃ , FeO, and Fe are specified. Similarly, in FIG. 8, binding energies corresponding to Co(OH) ₂ , CoO, and Co are specified. In FIG. 7 and FIG. 8, the XPS measurement results in

Comparative Example 1 and Comparative Example 2 are also illustrated.

[0089]

As illustrated in FIG. 7, when the partial pressure of the acetic acid gas was set to 4xl0 ^"6 Torr (5xl0 ^~4 Pa) , the relative intensities of FeO and Fe ₂ 0 ₃ were higher than the relative intensity of Fe. Similarly, as illustrated in FIG. 8, the relative intensities of Co(OH) ₂ and CoO were higher than the relative intensity of Co. As described above, when the partial pressure of the acetic acid gas was set to

4xl0 ^~6 Torr (5xl0 ^"4 Pa), the amount of Fe ₂ 0 ₃ or Co(OH) ₂ , which are oxidized Fe or Co, on the surface of the

substrate was greater than that of Fe or Co. Therefore, an acetic acid was adequately supplied to the surface of the substrate .

EXPLANATIONS OF LETTERS OR NUMERALS

[0090]

1 Etching apparatus

2 Source chamber

3 Target chamber

5 Nozzle

6 Nozzle pipe

10 GCIB radiation mechanism

20 XY stage

21 Vacuum pump Vacuum pump

Organic compound gas supply unit Underlayer

First deposited layer

First magnetic layer

Tunnel barrier layer

Second magnetic layer

Second deposited layer

Mask layer