TW201447999A - Planarization method, substrate processing system, and memory manufacturing method - Google Patents

Abstract

Provided is a planarization method by which a Ru film that is formed as a memory-configuring film can be planarized. On a wafer (W), before a MTJ element is formed, a nitrogen GCIB (gas cluster ion beam) is used to irradiate the Ru film that is formed as a MRAM-configuring film.

Description

Planarization method, substrate processing system, and memory manufacturing method

The present invention relates to a planarization method, a substrate processing system, and a memory manufacturing method for planarizing a Ru film provided in a memory.

In recent years, it has been developed as a next-generation non-volatile memory that replaces the previous memory, such as DRAM (Dynamic Random Access Memory) or SRAM (Static Random Access Memory). MRAM (Magnetoresistive Random Access Memory) (magnetoresistive memory). The MRAM has an MTJ (Magnetic Tunnel Junction) element instead of a capacitor, and is memorized by the magnetization state.

The MTJ element includes, for example, an insulating film of a MgO film, and two ferromagnetic films which are opposed to each other by the MgO film, for example, a CoFeB film. However, if the MgO film is not planarized, the characteristics of the MTJ element are adversely affected, for example, This results in a decrease in the MR ratio (Magneto-Resistance ratio).

As shown in FIG. 13, the MTJ element 100 is formed on the metal film 104, but the MgO film 102 and the CoFeB films 101 and 103 are both extremely thin films, and are affected by the unevenness of the surface of the metal film 104 due to polycrystalline growth or the like. As a result, the flatness is deteriorated, and therefore, the flatness of the metal film 104 must be improved.

In the case where the flatness is improved, a planarization method using GCIB (Gas Cluster Ion Beam) (gas cluster ion beam) is known as a method of flattening without using plasma.

GCIB is a method in which a gas is blown into a vacuum atmosphere to form a cluster of molecules constituting a gas, and the cluster is ionized, and the ionized cluster is accelerated by a bias voltage to cause it to collide with the wafer (for example, Refer to Patent Document 1). Generally, in the case where the metal film 104 is planarized by GCIB, a rare atom having a large atomic amount such as argon (Ar) gas is used.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2012-104859

However, when the metal film 104 contains Ru as a noble metal which is difficult to etch, even if a GCIB of argon gas having a large atomic weight is used, it is difficult to sputter and etch the convex portion of the metal film 104, and it is difficult to planarize the metal film 104. .

An object of the present invention is to provide a planarization method, a substrate processing system, and a memory manufacturing method which can flatten a Ru film formed as a constituent film of a memory.

In order to solve the above problems, according to the present invention, a flattening method is provided, in which a Ru film formed on a substrate as a constituent film of a memory is irradiated with a GCIB (gas cluster ion beam) of nitrogen gas.

In the present invention, it is preferred that the substrate is heated before the Ru film is irradiated with the GCIB of the nitrogen gas.

In the present invention, it is preferable that the memory is an MRAM (magnetoresistive memory) having an MTJ (magnetic tunneling junction) element, and the film-formed Ru film is irradiated with the GCIB of the nitrogen gas before the formation of the MTJ element.

In the present invention, it is preferred that the GCIB of the nitrogen gas is generated by accelerating a cluster of nitrogen gas at an acceleration voltage of 20 kV or less.

In the present invention, it is preferred that the GCIB of the nitrogen gas is generated by ionizing a cluster of nitrogen gas at an ionization voltage of 100 V or more.

In order to solve the above problems, according to the present invention, there is provided a substrate processing system comprising: a film forming apparatus having a film forming processing chamber for forming a Ru film on a substrate; and a GCIB irradiation device for irradiating a GCIB of nitrogen gas; The GCIB irradiation apparatus irradiates the film-formed Ru film with the GCIB of the nitrogen gas.

In the present invention, it is preferable that the film forming apparatus and the GCIB irradiation apparatus are disposed apart from each other in the atmosphere, and the Ru film is formed on the substrate in the film forming processing chamber, and then the substrate is carried out from the film forming apparatus. The substrate is transferred to the above-mentioned GCIB irradiation apparatus by being transported in the above atmosphere.

In the present invention, after the GCIB irradiation apparatus irradiates the Ru film with the GCIB of the nitrogen gas, the substrate is carried out from the GCIB irradiation apparatus, and the substrate is conveyed in the atmosphere and carried into the film formation apparatus.

In the present invention, it is preferable to further include a heat treatment chamber for heating the substrate, wherein the heat treatment chamber heats the substrate after the film formation of the Ru film and before the GC film of the Ru film is irradiated with nitrogen gas.

In order to solve the above problems, according to the present invention, there is provided a memory manufacturing method comprising: a Ru film forming step of forming a Ru film on the substrate; and a planarization step of flattening the Ru film In the above planarization step, the film-formed Ru film is irradiated with the GCIB of the nitrogen gas.

In the present invention, it is preferable to further include an MTJ element forming step of forming an MTJ element on the Ru film, and performing the planarization step before performing the MTJ element forming step.

According to the present invention, the Ru film formed as a constituent film of the memory can be irradiated with GCIB of nitrogen gas, and therefore, the Ru film can be planarized.

10, 57‧‧‧ substrate processing system

11‧‧‧ Film forming module

12, 58‧‧‧ film forming device

13‧‧‧ Flattening module

14‧‧‧FOUP

15‧‧‧Bearer module

16‧‧‧Transmission module

17‧‧‧Load interlock module

18‧‧‧Load埠

19, 20‧‧‧Transport arm

21‧‧‧Processing room

22‧‧‧ mounting table

23‧‧‧Electrostatic suction cup

24‧‧‧arm

25‧‧‧GCIB irradiation device

26‧‧‧Control Department

29‧‧‧Ontology

30‧‧‧Nozzles

31‧‧‧Splitter

32‧‧‧Ionizer

33‧‧‧Accelerator

34‧‧‧ permanent magnet

35‧‧‧ Orifice

36‧‧‧Pore

37, 38‧‧‧ mesh

39‧‧‧Nitrogen clusters

40‧‧‧ Argon clusters

41‧‧‧ precious metal film

42‧‧‧Atomic

43‧‧‧Nitrate molecules

44‧‧‧MRAM

45‧‧‧矽基部

46‧‧‧SiO ₂ film

47‧‧‧Cu film

48, 50, 52‧‧‧Ta film

49, 53‧‧‧Ru film

51, 100‧‧‧MTJ components

54, 102‧‧‧MgO film

55, 56, 101, 103‧‧‧CoFeB film

59‧‧‧ Annealing Module

104‧‧‧Metal film

S901‧‧‧Steps

S902‧‧‧Steps

S903‧‧‧Steps

S904‧‧‧Steps

S905‧‧‧Steps

S906‧‧‧Steps

S907‧‧‧Steps

S1201‧‧‧Steps

W‧‧‧ wafer

Fig. 1 is a plan view schematically showing a configuration of a substrate processing system according to a first embodiment of the present invention.

Fig. 2 is a cross-sectional view schematically showing the configuration of the flattening processing module of Fig. 1.

Fig. 3 is a cross-sectional view schematically showing the configuration of the GCIB irradiation apparatus of Fig. 2.

Fig. 4 is a view for explaining the case where an argon cluster collides with a noble metal film.

Fig. 5 is a view for explaining a case where a nitrogen cluster collides with a noble metal film.

Fig. 6 is a graph showing the flatness of the Ru film after GCIB irradiation when the accelerating voltage is changed.

Fig. 7 is a graph showing the flatness of the Ru film after GCIB irradiation when the ionization voltage is changed.

Fig. 8 is a cross-sectional view schematically showing the configuration of an MRAM to which the planarization method of the embodiment is applied.

Fig. 9 is a flow chart showing the MRAM manufacturing process to which the planarization method of the embodiment is applied.

Fig. 10 (A) - (D) are process diagrams of an MRAM manufacturing process to which the planarization method of the present embodiment is applied.

FIG. 11 is a plan view schematically showing a configuration of a substrate processing system according to a second embodiment of the present invention.

Fig. 12 is a flow chart showing the MRAM manufacturing process to which the planarization method of the embodiment is applied.

Fig. 13 is a cross-sectional view schematically showing a configuration of a general structure of an MRAM.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

First, a substrate processing system according to a first embodiment of the present invention will be described.

Fig. 1 is a plan view schematically showing the configuration of a substrate processing system of the embodiment. Figure.

In FIG. 1, the substrate processing system 10 includes a film forming apparatus 12 including a plurality of film forming processing modules 11 (film forming processing chambers) for performing a film forming process on the wafer W, and a flattening processing module 13 (GCIB). The irradiation device) performs a planarization process on the wafer W subjected to the film formation process. The film forming apparatus 12 and the flattening processing module 13 are disposed apart from each other in a clean room in an atmospheric atmosphere.

The film forming apparatus 12 includes a plurality of containers for accommodating the wafer W (indicated by a broken line in the figure) in addition to the plurality of film forming processing modules 11, for example, a carrier module 15 that uses the wafer W from FOUP (Front). Opening Unified Pod (front open wafer carrier) 14 is carried out; transport module 16 is configured to carry each wafer W into each film forming processing module 11 and carry out operations from each film forming processing module 11; and 2 loads The interlock module 17 is equal to the transfer of the wafers W between the carrier module 15 and the transfer module 16.

The carrier module 15 includes a substantially rectangular parallelepiped transfer chamber that is open to the atmosphere, and has a load port 18 to which the FOUP 14 can be mounted, and a transfer arm 19 (shown by a broken line in the drawing) inside the transfer chamber, the transfer arm 19 performs Each wafer W is carried into an operation of the FOUP 14 attached to the load cassette 18 and carried out from the FOUP 14.

Around the transport module 16, a plurality of film forming processing modules 11 are radially arranged and connected to the transport module 16, and the transport module 16 has a transfer chamber that is internally decompressed, and is disposed in the transport chamber. The inner transfer arm 20 (shown by a broken line in the drawing) transports each wafer W between each film formation processing module 11, the flattening processing module 13, and each load lock module 17.

The load lock module 17 includes a standby room that can switch the interior to an atmospheric environment and a reduced pressure environment. The transfer arm 19 of the carrier module 15 and the transfer arm 20 of the transfer module 16 are each loaded via the load lock module 17 The intersection of the round W.

Each of the film forming processing modules 11 has a processing chamber in which the inside of the film forming chamber is decompressed, and the wafer W is stored in a single sheet, and the wafer W is subjected to a film forming process by sputtering of plasma generated in the processing chamber.

The substrate processing system 10 is provided with a control unit 26, which is required to be implemented, for example. The process recipe formula controls the operation of each component of the substrate processing system 10 to perform processing corresponding to the required process recipe for each wafer W. In addition, in FIG. 1, the control unit 26 is connected to the carrier module 15 and the flattening processing module 13, but the control unit 26 may be connected to any of the components of the substrate processing system 10, and any of the constituent elements may be The control unit 26 is further provided, and the control unit 26 may be configured as an external server provided at a position different from the substrate processing system 10.

Fig. 2 is a cross-sectional view schematically showing the configuration of the flattening processing module of Fig. 1.

In FIG. 2, the flattening processing module 13 disposed apart from the film forming apparatus 12 includes a processing chamber 21 that houses the wafer W, a mounting table 22 that is disposed below the processing chamber 21, and an electrostatic chuck 23, Mounted on the upper surface of the mounting table 22 and electrostatically adsorbing the wafer W; the arm portion 24 separates the electrostatic chuck 23 from the electrostatically adsorbed wafer W from the mounting table 22; and the GCIB irradiation device 25 The GCIB is disposed to the side wall portion of the processing chamber 21 to illuminate the nitrogen gas substantially horizontally.

In the flattening processing module 13, the arm portion 24 moves the electrostatic chuck 23 away from the mounting table 22 such that the electrostatically adsorbed wafer W and the GCIB irradiation device 25 face each other, and the GCIB irradiation device 25 irradiates the opposite wafer W with nitrogen gas. GCIB.

The electrostatic chuck 23 may have a refrigerant flow path and a heater (none of which are shown) to cool the wafer W that is electrostatically adsorbed, and heat the wafer W.

Fig. 3 is a cross-sectional view schematically showing the configuration of the GCIB irradiation apparatus of Fig. 2.

In Fig. 3, the GCIB irradiation device 25 includes a tubular body 29 that is disposed substantially horizontally and internally decompressed, a nozzle 30 disposed at one end of the body 29, a plate-shaped shunt 31, an ionizer 32, and an accelerator. 33. Permanent magnet 34 and orifice plate 35.

The nozzle 30 is disposed along a central axis of the horizontal direction of the body 29 along which, for example, nitrogen gas is ejected. The flow divider 31 is disposed to cover a cross section in the body 29, and the center portion protrudes along the center axial direction of the body 29, and has a fine hole 36 at the top of the protruding portion. The orifice plate 35 is also disposed to cover the cross section in the body 29 to correspond to the center of the body 29 A portion of the shaft has a screen opening 37, and the other end of the body 29 also has a screen opening 38 at a portion corresponding to the central axis of the body 29.

The ionizer 32, the accelerator 33, and the permanent magnets 34 are all disposed to surround the central axis of the body 29. The ionizer 32 emits electrons toward the central axis of the body 29 by heating the built-in filaments, and the accelerator 33 is disposed along the body 29. The central axis generates a potential difference, and the permanent magnet 34 generates a magnetic field near the central axis of the body 29. In the following, the voltage applied to the ionizer 32 for heating the filament is referred to as "ionization voltage", and the voltage applied to the accelerator 33 in order to generate the potential difference is hereinafter referred to as "acceleration voltage".

In the GCIB irradiation device 25, the nozzle 30, the flow divider 31, the ionizer 32, the accelerator 33, the orifice plate 35, and the permanent magnet are sequentially disposed from one end side (left side in the drawing) to the other end side (right side in the drawing) of the body 29. 34.

When the nozzle 30 discharges nitrogen gas into the inside of the body 29 which is decompressed, the volume of nitrogen gas rapidly increases, and the nitrogen gas rapidly ignites to rapidly cool the nitrogen molecules. When each nitrogen molecule is quenched, the kinetic energy is lowered and the intermolecular force (van der Waals force) acting between the respective nitrogen molecules is in close contact with each other, whereby a plurality of nitrogen clusters 39 containing a plurality of nitrogen molecules are formed.

The flow divider 31 filters only the nitrogen clusters 39 moving along the central axis of the body 29 of the plurality of nitrogen clusters 39 by the pores 36. The ionizer 32 moves the nitrogen clusters along the central axis of the body 29 by collision of electrons. 39, the nitrogen cluster 39 is ionized, the accelerator 33 accelerates the ionized nitrogen cluster 39 toward the other end side of the body 29 by the potential difference, and the orifice plate 35 screens only the accelerated nitrogen cluster through the mesh 37. In the 39, a nitrogen cluster 39 is moved along the central axis of the body 29, and the permanent magnet 34 is changed by a magnetic field to change a relatively small nitrogen cluster 39 (a monomer containing ionized nitrogen molecules). In the permanent magnet 34, although the relatively large nitrogen cluster 39 is also affected by the magnetic field, its mass is not changed by the magnetic force due to its large mass, and continues to move along the central axis of the body 29.

The relatively large nitrogen gas cluster 39 having passed through the permanent magnet 34 passes through the mesh hole 38 at the other end of the body 29, and is emitted as a nitrogen gas GCIB to the outside of the body 29 to be irradiated onto the wafer W.

In addition, the inventors of the present invention have confirmed that the surface of the noble metal film, such as the Ta film, the Ru film, and the PtMn film, which is polished by CMP (Chemical Mechanical Polishing), such as a Ta film, a Ru film, and a PtMn film, is irradiated with argon. GCIB of gas and GCIB of nitrogen, as a result, in the case of GCIB irradiated with argon gas, the flatness of the Ta film, the Ru film, and the PtMn film are all deteriorated, and on the other hand, in the case of GCIB irradiated with nitrogen, the Ta film The flatness of the Ru film and the PtMn film are all improved.

It is confirmed that, for example, when the flatness of the Ta film after polishing by CMP is Ra=1.11 nm, the flatness is deteriorated to Ra=1.128 nm when the argon gas is irradiated with GCIB. In the case of GCIB irradiated with nitrogen, the flatness was increased to Ra = 0.23 nm.

Further, it was confirmed that when the flatness of the Ru film after polishing by CMP was Ra = 0.46 nm, the flatness was deteriorated to be Ra = 0.876 nm when the argon gas was irradiated with GCIB. In the case of GCIB irradiated with nitrogen, the flatness was increased to Ra = 0.13 nm.

Further, it has been confirmed that when the flatness of the PtMn film after CMP polishing is Ra = 0.59 nm, the flatness is deteriorated to Ra = 1.368 nm when the argon gas is irradiated with GCIB. In the case of GCIB irradiated with nitrogen, the flatness was increased to Ra = 0.30 nm.

The present inventors have obtained the following findings based on the above findings: even in the case of a noble metal film which is difficult to etch, the flatness of the noble metal film can be improved by irradiating GCIB of nitrogen gas.

Based on the above findings, the inventors of the present invention have deteriorated the flatness of the noble metal film which is difficult to etch by the GCIB using argon gas. However, the reason why the flatness of the noble metal film which is difficult to etch is improved by GCIB using nitrogen gas is estimated as follows.

It is known that, in general, GCIB has a side-sputtering effect, that is, when a gas cluster in the GCIB collides with a metal film or the like, the molecules are scattered from the gas cluster along the surface of the metal film and actively sputtered from the The convex part of the surface, but the argon molecule has a relatively strong van der Waals The argon molecules in the argon cluster 40 are firmly adhered to each other. Therefore, as shown in FIG. 4, when the argon cluster 40 collides with the noble metal film 41, it is difficult for the argon molecules to scatter along the surface of the noble metal film 41, and the argon gas cluster is reversed. 40 directly hits the surface of the noble metal film 41. As a result, the noble metal film 41 is broken by sputtering by the argon gas cluster 40, and further, the atom 42 of the scattered noble metal adheres to the surface of the noble metal film, whereby the flatness of the noble metal 41 is deteriorated.

On the other hand, the van der Waals force of the nitrogen molecule is weaker than the van der Waals force of the argon molecule, and the nitrogen molecules in the nitrogen cluster 39 are not so tightly bonded, and therefore, as shown in FIG. 5, in the nitrogen cluster When the noble metal film 41 collides with the noble metal film 41, the nitrogen molecules 43 easily scatter along the surface of the noble metal film 41, and the scattered nitrogen molecules 43 actively sputter the convex portions protruding from the surface of the noble metal film 41.

That is, the inventors of the present invention concluded that the reason why the flatness of the noble metal film is increased by the GCIB of nitrogen gas is that the GCIB of nitrogen gas composed of nitrogen molecules having a weak vana potential has a high side sputtering effect.

Further, the inventors of the present invention also confirmed the influence of the ionization voltage or the acceleration voltage at the time of generating GCIB of nitrogen on the flatness of the Ru film.

First, when the flatness of the initial value (the flatness by CMP polishing) is the case where the Ru film of Ra = 0.46 nm is irradiated with the GCIB of nitrogen gas, the acceleration voltage setting of the accelerator 33 to be applied to the GCIB irradiation device 25 is measured. For the flatness after irradiation at 5 kV, 10 kV, and 20 kV, the measured flatness is shown as a "●" in the graph of FIG. 6, and further, ionization to be applied to the GCIB irradiation device 25 is measured. The ionization voltage of the device 32 was set to a flatness after irradiation at 50 V, 100 V, and 170 V, and the measured flatness was shown as a "●" in the graph of Fig. 7 as an example.

In the case where the Ru film of the initial value of the flatness of Ra=0.46 nm is irradiated with the GCIB of argon gas, the flatness after the irradiation of the acceleration voltage applied to the accelerator 33 is set to 5 kV, 10 kV, and 20 kV is measured. The measured flatness is shown as a "■" in the graph of FIG. 6 as a comparative example, and further, the flatness after the irradiation of the ionization voltage applied to the ionizer 32 to 50 V, 100 V, and 170 V was measured. Degree, the determination will be The flatness is shown in the graph of Fig. 7 as "■" as a comparative example.

It is confirmed from the graphs of FIG. 6 and FIG. 7 that, in the case of the GCIB in which the Ru film is irradiated with argon gas, the flatness after the irradiation is deteriorated from the initial value regardless of the acceleration voltage and the ionization voltage. On the other hand, in the case of irradiating the Ru film with GCIB of nitrogen gas, the flatness of each of the acceleration voltage and the ionization voltage is higher than the initial value when the ionization voltage is 50 V. .

Further, from the graph of Fig. 6, it was confirmed that when the Ru film was irradiated with GCIB of nitrogen gas, the acceleration voltage was decreased, and the flatness after the irradiation was increased.

It is presumed that the reason is that if the accelerating voltage is increased, the nitrogen cluster 39 is accelerated more than necessary, and the nitrogen cluster 39 collides with the Ru film and is sputtered before the nitrogen molecules are scattered from the nitrogen cluster 39 along the surface of the Ru film. Ru film, on the other hand, if the accelerating voltage is reduced, the nitrogen cluster 39 is not accelerated more than necessary, and before the nitrogen cluster 39 collides with the Ru film, the nitrogen molecules 43 are from the nitrogen cluster 39 along the Ru film. The surface is scattered.

Further, from the graph of Fig. 7, it was confirmed that when the Ru film was irradiated with GCIB of nitrogen gas, the ionization voltage was increased, and the flatness after the irradiation was increased.

It is presumed that the reason is that if the ionization voltage is increased, a plurality of multivalent nitrogen ions can be generated in the nitrogen cluster 39, and the energy of the nitrogen cluster 39 can be easily increased by the accelerating voltage, and therefore, the edge can be improved. The surface of the Ru film scatters the energy of the nitrogen molecules 43 and can be more actively sputtered by the high-energy nitrogen molecules 43 from the convex portions protruding from the surface of the Ru film.

As described above, when the ionization voltage is set to at least 100 V or more, or the acceleration voltage is set to at least 20 kV or less, the flatness of the nitrogen cluster 39 after irradiation with the Ru film is improved as compared with the flatness of the initial value.

In the present embodiment, based on the above findings, in the manufacturing process of a memory such as an MRAM, the film formed Ru is irradiated with a GCIB containing nitrogen gas of a nitrogen gas cluster 39 before the formation of the MTJ element, and the Ru film is planarized.

Fig. 8 is a view schematically showing the construction of an MRAM to which the planarization method of the embodiment is applied. The resulting profile. Although a plurality of MRAMs are formed on the surface of the wafer W, FIG. 8 shows an MRAM obtained by performing a processing for removing excess portions, for example, plasma etching, on a laminated structure of a plurality of metal films. Furthermore, the following Fig. 10 also shows the state after the excess portion is removed.

The MRAM is an electronic device having an MTJ element, and the MTJ element is generally formed by a structure in which an oxide film is sandwiched between a ferromagnetic layer as a fixed layer (the magnetization direction is fixed) and a ferromagnetic layer as a free layer (free in the magnetization direction). The film usually contains AlOx or MgO, and the ferromagnetic layer contains a NiFe alloy, a CoFe alloy or a CoFeB alloy.

In FIG. 8, the MRAM 44 (MRAM device) includes a Cu film 47 buried in a SiO ₂ film 46 formed on the base portion 45 of the wafer W, and a Ta film 48 formed on the Cu film 47; 49, which is formed on the Ta film 48; a Ta film 50 formed on the Ru film 49; an MTJ element 51 formed on the Ta film 50; and a Ta film 52 formed on the MTJ element The Ru film 53 is formed on the Ta film 52. The MTJ element 51 includes a MgO film 54 and two CoFeB films 55 and 56 opposed to each other via the MgO film 54. The Cu film 47 to the Ta film 50 constitute a lower electrode, and the Ta film 52 and the Ru film 53 constitute an upper electrode.

The Cu film 47 is formed by forming a film by plasma etching equal to SiO ₂ film forming 46 grooves, embedding Cu into the groove by plating or the like, and grinding the buried portion by CMP. The surface of Cu. Each of the Ta film 48 to the Ta film 50 and the Ta film 52 to the CoFeB film 56 is formed by sputtering of plasma in each of the film forming processing modules 11.

In the MRAM 44, in order to maintain the characteristics of the MTJ element 51, it is preferable to planarize the MgO film 54, and the film thickness of the MgO film 54 is fixed, for example, about 1 nm.

On the other hand, in the manufacturing process of the MRAM 44, as described above, the Ta film 48 to the Ta film 50 and the Ta film 52 to the CoFeB film 56 are formed by sputtering of a plasma, and therefore, the film is not formed immediately after film formation. In the crystalline state, for example, in the Ru film 49, polycrystalline growth is performed in order to reduce the total energy, and volume shrinkage and deformation occur, and irregularities are formed on the surface of the Ru film 49.

At this time, if the surface of the Ru film 49 which is generated due to the progress of the polycrystal growth is not removed, When the Ta film 50 is formed by the unevenness, the Ta film 50 propagates the unevenness on the surface of the Ru film 49, and the respective films 54 to 56 of the MTJ element 51 are not flattened.

Therefore, in the present embodiment, the Ru film 49 is irradiated with GCIB of nitrogen gas after the unevenness is generated on the surface of the Ru film 49 due to the progress of polycrystal growth and before the Ta film 50 is formed. In this case, the unevenness of the Ru film 49 is removed by the lateral side sputtering effect of the GCIB of nitrogen gas to flatten the surface of the Ru film 49.

Fig. 9 is a flow chart showing the MRAM manufacturing process to which the planarization method of the embodiment is applied. This manufacturing process is executed by the control unit 26 controlling the operation of each component of the substrate processing system 10 in accordance with a specific program.

In FIG. 9, first, the wafer W is carried into the film formation processing module 11 of the film forming apparatus 12, and the Cu film 47 is buried in the SiO ₂ film 46, and is further carried into another film forming processing module 11 And the operation of carrying out from the other film formation processing module 11 to form the film Ta film 48 and the Ru film 49 (step S901) (Ru film formation process).

Then, the wafer W is carried out from the film forming apparatus 12, and the wafer W is transferred to the flattening processing module 13 in the clean room (step S902).

Then, in the flattening processing module 13, the wafer W is electrostatically adsorbed to the electrostatic chuck 23, and the electrostatically adsorbed wafer W is cooled to, for example, normal temperature or lower, and is electrostatically attracted to the electrostatic chuck 23 by the arm portion 24. The wafer W is opposed to the GCIB irradiation device 25, and the Ru film 49 of the wafer W is irradiated with the GCIB of nitrogen gas from the GCIB irradiation device 25.

At this time, as shown in FIG. 10(A), as shown in FIG. 10(A), irregularities are generated due to polycrystal growth. However, when the Ru film 49 is irradiated with GCIB of nitrogen gas, the convex film protrudes from the surface of the Ru film 49. The portion is removed by actively sputtering the nitrogen molecules 43 scattered from the surface of the Ru film 49 from the nitrogen cluster 39 (Fig. 10(B)), and as shown in Fig. 10(C), the Ru film 49 is planarized. (Step S903) (flattening step).

Further, when the RuB film 49 is irradiated with the GCIB of nitrogen gas from the GCIB irradiation device 25, the arm portion 24 moves the electrostatic chuck 23 in the up-down direction or the depth direction in FIG. 2 by GCIB of nitrogen gas. The entire surface of the wafer W is scanned. Further, in order to promote the planarization of the Ru film 49 by GCIB of nitrogen gas, the wafer W may be tilted with respect to the GCIB of nitrogen gas without causing the wafer W to be positive for GCIB of nitrogen.

Then, the wafer W is carried out from the flattening processing module 13, and the wafer W is transferred to the film forming apparatus 12 in the clean room (step S904), and is flattened in the film forming processing module 11. The Ta film 50 is formed on the Ru film 49 to form a lower electrode (step S905).

Then, the CoFeB film 55, the MgO film 54, and the CoFeB film 56 are sequentially formed in each of the film forming processing modules 11 to form the MTJ element 51 (step S906), and further formed in each film forming processing module 11 in order. The film Ta film 52 and the Ru film 53 form an upper electrode as shown in FIG. 10(D) (step S907), and the present process is terminated.

According to the MRAM manufacturing process of FIG. 9, the Ru film 49 which is a film formed of the MRAM is irradiated with GCIB of nitrogen gas. Since the vanadium force of the nitrogen molecules 43 is relatively small, when the Ru film 49 is irradiated with the GCIB of nitrogen gas, the nitrogen molecules 43 are easily scattered from the nitrogen clusters 39 along the surface of the Ru film 49, and the scattered nitrogen molecules 43 The convex portion protruding from the surface of the Ru film 49 is actively sputtered. Thereby, the Ru film 49 can be planarized.

In the MRAM manufacturing process of FIG. 9, the Ru film 49 is irradiated with GCIB of nitrogen gas before the formation of the MTJ element 51, and planarization is performed. For example, as described above, the flatness is improved to about Ra=0.13 nm, thereby preventing it. The flatness of the MgO film 54 of the MTJ element 51 is deteriorated by the unevenness of the surface of the Ru film 49, and the MR ratio of the MTJ element 51 can be prevented from being lowered.

Further, in the MRAM manufacturing process of FIG. 9, after the film forming process module 11 forms the Ru film 49 on the wafer W, the wafer W is carried out from the film forming apparatus 12, and the wafer is transferred to the atmosphere in the clean room. W is carried into the flattening processing module 13. Therefore, when the Ru film 49 on the wafer W is irradiated with the GCIB of nitrogen gas in the planarization processing module 13, the other crystals in the film forming processing module 11 can be used. The Ru film 49 is formed on the round W, so that the productivity can be improved. Moreover, since the Ru film 49 is not oxidized in the atmosphere, it is not necessary to consider preventing the wafer W from being formed into a film forming apparatus. The Ru film 49 is oxidized during the transfer of the flattening processing module 13 to simplify the configuration of the substrate processing system 10.

In addition, although the Ru film 49 formed by sputtering is polycrystal grown from an amorphous state and has irregularities on the surface, the polycrystalline growth system proceeds relatively slowly, so that the polycrystal is not completely grown. In the case where the Ru film 49 is irradiated with the GCIB of nitrogen gas, the Ru film 49 is also subjected to polycrystalline growth after planarization, and the unevenness may be generated again on the flattened surface.

On the other hand, in the MRAM manufacturing process of FIG. 9 , after the Ru film 49 is formed, the wafer W is carried out from the film forming apparatus 12, and the wafer W is transferred into the clean room in the atmosphere and carried into the flattening processing mode. Group 13, therefore, the Ru film 49 was not immediately irradiated with GCIB of nitrogen. In other words, the progress of the polycrystalline growth of the Ru film 49 can be delayed by the transfer and carry-in of the wafer W, and it is expected that the polycrystallization of the Ru film 49 is saturated before the GCIB of the flattening module 13 is irradiated with nitrogen. It is expected that the unevenness of the surface of the flattened Ru film 49 is prevented from occurring again.

Further, in the MRAM manufacturing process of FIG. 9, since the sputtering is not performed by the cation in the plasma, the flatness of the Ru film 49 is not deteriorated, and since the halogen gas is not used, it is not necessary. After the planarization, the cleaning for removing the halogen is performed.

Next, a planarization method and a substrate processing system according to a second embodiment of the present invention will be described.

The configuration or operation of the present embodiment is basically the same as that of the above-described first embodiment, and is different from the above-described first embodiment in that the substrate processing system further includes an annealing module. Therefore, the description of the configuration and operation of the repetition will be omitted, and the different configurations and operations will be described below.

Fig. 11 is a plan view schematically showing the configuration of a substrate processing system of the embodiment.

In FIG. 11, the substrate processing system 57 is different from the substrate processing system 10, and the film forming apparatus 58 having a configuration similar to that of the film forming apparatus 12 is provided with an annealing mold in addition to the film forming processing module 11. Group 59 (heat treatment chamber). The annealing module 59 is provided with a lamp heater (not shown) or the like to heat the accommodated wafer W.

In addition, as described above, when the Ru film 49 is irradiated with GCIB of nitrogen gas during the period in which the polycrystal of the Ru film 49 is not completely grown, the Ru film 49 is also subjected to polycrystalline growth after planarization to be planarized. The possibility of unevenness on the surface.

In the present embodiment, in this case, polycrystalline growth is promoted by actively heating the Ru film 49, and the polycrystal of the Ru film 49 is saturated before being planarized by irradiation with GCIB of nitrogen gas.

Fig. 12 is a flow chart showing the MRAM manufacturing process to which the planarization method of the embodiment is applied. Steps S901 to S907 in this processing are the same as steps S901 to S907 in the MRAM manufacturing process of FIG.

In FIG. 12, first, after performing step S901, the wafer W formed by forming the Ru film 49 by the film forming processing module 11 is carried into the annealing module 59 via the transfer module 16, and the wafer is heated by the lamp heater. W. At this time, polycrystalline growth is promoted in the Ru film 49 in an amorphous state, and polycrystallization is saturated (step S1201).

Then, step S902 and step S903 are performed. At this time, since the polycrystallization of the Ru film 49 is saturated, the Ru film 49 does not undergo polycrystalline growth after planarization, and does not cause irregularities on the flattened surface.

Then, steps S904 to S907 are executed to end the method.

According to the planarization method of FIG. 12, since the wafer W is heated before the Ru film 49 is irradiated with the GCIB of nitrogen gas, the polycrystallization of the Ru film 49 can be saturated, and the Ru film 49 can be prevented from being irradiated by GCIB. After the planarization, polycrystalline growth is performed in the Ru film 49 to lower the flatness of the Ru film 49 again.

In the substrate processing system 57 of FIG. 11 , the annealing module 59 is connected to the transfer module 16 of the film forming device 58 , but the arrangement position of the annealing module 59 is not limited thereto, and may be separated from the film forming device 58 , for example. It is disposed adjacent to the planarization processing module 13. Again, there is no need to The annealing module 59 performs heating for saturating the polycrystallization of the Ru film 49, and the heating may be performed by a heater of the electrostatic chuck 23 of the planarization processing module 13.

Although the present invention has been described above using the above embodiments, the present invention is not limited to the above embodiments.

The planarization method of the present invention is applied to the MRAM in each of the above embodiments. However, as long as the memory includes the Ru film, it can be applied to other memories such as ReRAM (Resistance Random Access Memory).

Further, in each of the above embodiments, the GCIB irradiation device 25 irradiates the GCIB composed only of the nitrogen clusters 39, but the irradiated GCIB may partially contain other gas clusters such as argon clusters. However, in order to maintain the side-spraying effect of the GCIB, the content of other gas clusters in the GCIB is preferably as small as possible.

Further, the object of the present invention can be achieved by supplying a memory medium on which a program code for realizing the functions of the above-described respective embodiments is recorded to a computer, for example, the control unit 26, and the CPU of the control unit 26 (Central Processing) Unit, central processing unit) executes the code stored in the memory medium and executes it.

In this case, the code itself read from the memory medium realizes the functions of the above embodiments, and the code and the memory medium in which the code is stored constitute the present invention.

Further, as the memory medium for supplying the code, for example, a RAM (Random Access Memory), NV-RAM (Non-Volatile Random Access Memory), and Floppy are used. (registered trademark) disc, hard disc, magneto-optical disc, CD-ROM (Compact Disc Read Only Memory), CD-R (Compact Disk-Recordable, recordable disc), CD-RW ( Compact Disc-Rewritable, rewritable disc, DVD (Digital Versatile Disc), DVD-ROM (Digital Versatile Disc Read Only Memory), DVD- RAM (Digital Versatile Disc Random Access Memory), DVD-RW (DVD-Rewritable, rewritable digital versatile disc), DVD+RW (DVD+Rewritable, advanced rewritable) Digital multi-function disc)) Such as CD, tape, non-volatile memory card, other ROM (Read Only Memory) can remember the above code. Alternatively, the code may be supplied to the control unit 26 by downloading from another computer or database (not shown) connected to the Internet, a commercial network, or a regional network.

Further, not only the functions of the above-described embodiments are realized by executing the code read by the control unit 26, but also the OS (Operating System) operating on the CPU based on the instruction of the code. Some or all of the actual processing, by this processing, realizes the functions of the above embodiments.

Further, the case where the code read from the memory medium is written into the function expansion board of the control unit 26 or the memory provided in the function expansion unit connected to the control unit 26, based on the instruction of the code The CPU or the like provided in the function expansion board or the function expansion unit performs part or all of the actual processing, and the functions of the above embodiments are realized by the processing.

The form of the above code may also include a target code, a code executed by an interpreter, and a script data supplied to the OS.

The present application claims priority to Japanese Patent Application No. 2013-068901, filed on March 28, 2013, the entire content of

Claims (11)

A planarization method is characterized in that a Ru film formed on a substrate as a constituent film of a memory is irradiated with a GCIB (gas cluster ion beam) of nitrogen gas. The method of planarizing according to claim 1, wherein the substrate is heated before the above-mentioned Ru film is irradiated with the GCIB of the nitrogen gas. The flattening method of claim 1, wherein the memory is an MRAM (magnetoresistive memory) having an MTJ (magnetic tunneling junction) element, and the film-formed Ru film is irradiated with the nitrogen gas before the MTJ element is formed. GCIB. The method of planarizing according to claim 1, wherein the GCIB of the nitrogen gas is generated by accelerating a cluster of nitrogen gas with an accelerating voltage of 20 kV or less. The method of planarizing according to claim 1, wherein the GCIB of the nitrogen gas is generated by ionizing a cluster of nitrogen gas with an ionization voltage of 100 V or more. A substrate processing system, comprising: a film forming apparatus having a film forming processing chamber for forming a Ru film on a substrate; and a GCIB irradiation device for irradiating a GCIB of nitrogen gas; and the GCIB irradiation device is configured to form the film The Ru film is irradiated with the GCIB of the above nitrogen gas. The substrate processing system according to claim 6, wherein the film forming apparatus and the GCIB irradiation apparatus are disposed apart from each other in the atmosphere, and the Ru film is formed on the substrate in the film forming processing chamber, and the substrate is formed from the film. The apparatus is carried out, and the substrate is transferred to the atmosphere and carried into the GCIB irradiation apparatus. The substrate processing system according to claim 7, wherein after the GCIB irradiation device irradiates the Ru film with the GCIB of the nitrogen gas, the substrate is carried out from the GCIB irradiation device, and the substrate is transferred into the atmosphere and carried into the above-mentioned atmosphere. Membrane device. The substrate processing system of claim 6, further comprising a heat treatment chamber for heating the substrate; wherein the heat treatment chamber heats the substrate after the Ru film is formed and before the Ru film is irradiated with the GCIB of the nitrogen gas. A memory manufacturing method comprising: a Ru film forming step of forming a Ru film on a substrate; and a planarization step of planarizing the Ru film; and in the planarizing step, The film-formed Ru film was irradiated with GCIB of nitrogen gas. The memory manufacturing method of claim 10, further comprising the step of forming an MTJ element forming the MTJ element on the Ru film; and performing the planarizing step before performing the MTJ element forming step.