CN101127295A - Substrate processing method and apparatus, semiconductor device manufacturing method - Google Patents

Abstract

A method for treating a substrate having an insulating film and a metal layer on the substrate, the method comprising the steps of supplying carboxylic anhydride to the substrate, and heating the substrate during supplying the carboxylic anhydride to the substrate.

Description

Substrate processing method and apparatus, semiconductor device manufacturing method

field of invention

The present invention generally relates to substrate processing technology, and more particularly, to a method of processing a substrate carrying a metal layer thereon. Furthermore, the present invention relates to a method of manufacturing a semiconductor device having a metal interconnection, and a substrate processing apparatus for processing a substrate having a metal layer.

Background technique

With the development of semiconductor technology, the latest high-performance semiconductor devices usually use low-resistance Cu for interconnection. Thus, there is concern about oxidation of the exposed Cu pattern, since Cu is a material that is easily oxidized.

Reference 1 Japanese Patent No. 3,373,499

Reference 2 J.Phys.Chem.Ref.Data7, p.363 (1993)

Reference 3 J.Electrochem.Soc.150, p.G300, (2003)

Contents of the invention

Therefore, in the related art of the present invention, it is proposed to remove Cu oxide by causing a reduction reaction using a reducing gas such as NH ₃ or H ₂ , thereby forming such a Cu interconnection pattern.

However, in the case of using _NH3 or _H2 for this, it is necessary to use very high processing temperature to realize the reduction reaction of Cu, and possibly in the interlayer insulating film of the so-called low-K material existing around the Cu interconnect pattern cause damage.

In view of this, it has been proposed in another related art of the present invention to perform a reduction reaction at a low temperature using a treatment gas formed by evaporating formic acid or acetic acid.

However, when such formic acid or acetic acid vapor is used, monomers and dimers constituting the vapor may coexist, and thus the reduction reaction becomes unstable. For example, there are cases where the ratio of monomers and dimers formed from formic acid or acetic acid changes significantly when the processing conditions change slightly, resulting in instability of the Cu reduction reaction.

Accordingly, an object of the present invention is to provide a novel and useful substrate processing method, a semiconductor device manufacturing method, and further a substrate processing apparatus in which the above-mentioned problems are eliminated.

Thus, the present invention provides a substrate processing method and a substrate processing apparatus capable of stably and efficiently removing an oxide film from a metal layer on a substrate.

Furthermore, the present invention provides a method of manufacturing a semiconductor device in which an oxide film formed on a metal interconnection pattern during the manufacturing of the semiconductor device is stably and efficiently removed.

In a first aspect, the present invention provides a method of processing a substrate carrying an insulating film and a metal layer thereon, the method comprising the steps of:

providing the substrate with carboxylic anhydride; and

The substrate is heated during the step of providing the substrate with the carboxylic anhydride.

In a second aspect, the present invention provides a method of manufacturing a semiconductor device having a metal interconnection pattern and an interlayer insulating film, the method comprising the following processing steps:

providing carboxylic acid anhydride to the substrate having the metal interconnection pattern and the interlayer insulating film; and

The substrate is heated during the step of providing the substrate with the carboxylic anhydride.

In another aspect, the present invention provides a substrate processing apparatus for processing a substrate having an insulating film and a metal layer thereon, comprising:

a stage supporting and heating the substrate;

a processing vessel housing the rack therein;

supplying process gas to a gas supply within the process vessel; and

an extraction means for extracting gas from said processing vessel,

The process gas described therein contains carboxylic acid anhydride.

According to the present invention, a substrate processing method and a substrate processing apparatus capable of stably and efficiently removing an oxide film formed on a metal layer on a substrate to be processed can be provided.

Furthermore, according to the present invention, it is possible to provide a method of manufacturing a semiconductor device in which an oxide film formed on a metal interconnection pattern during the manufacturing of the semiconductor device is stably and efficiently removed.

Other objects and further features of the present invention will become apparent from the following detailed description when read in conjunction with the accompanying drawings.

Description of drawings

Figure 1 is a graph comparing melting and boiling points of materials;

Figure 2 is a graph showing the proportion of dimers in formic acid;

Figure 3 is a graph showing the proportion of dimers in acetic acid;

Figure 4 is a graph showing the vapor pressure of carboxylic anhydrides;

FIG. 5 is a diagram showing a substrate processing apparatus according to a first embodiment of the present invention;

The graph in Figure 6 shows the method for measuring film thickness by ellipsometry;

7 is a graph comparing the results of thermal desorption spectroscopy (TDS) measurement of the outgassing amount of a substrate on which an insulating film and a metal layer are formed before and after the acetic anhydride treatment of the present invention;

Figure 8 is a graph comparing the dielectric constants of various interlayer insulating films before and after the acetic anhydride treatment of the present invention;

FIG. 9 is a diagram showing a substrate processing apparatus according to a second embodiment of the present invention;

10 is a diagram showing a substrate processing apparatus according to a third embodiment of the present invention;

11 is a diagram showing a substrate processing apparatus according to a fourth embodiment of the present invention;

12 is a diagram showing a substrate processing apparatus according to a fifth embodiment of the present invention;

13A to 13E are diagrams showing a semiconductor device manufacturing method (substrate processing method) according to a sixth embodiment of the present invention.

Detailed ways

Embodiments of the present invention are explained below.

[principle]

The present invention provides a method for treating a substrate on which an insulating film and a metal layer are carried, the method comprising the steps of providing the substrate with carboxylic anhydride, and heating the substrate while providing the substrate with the carboxylic anhydride. Substrate steps.

According to the substrate processing method of the present invention in which an oxide film is removed from a metal layer (such as a Cu layer) using carboxylic anhydride instead of formic acid or acetic acid, removal processing can be performed stably and reproducibly.

The detailed reasons for using carboxylic anhydride as the process gas are explained below.

Figure 1 compares the melting and boiling points of various substances that may be able to reduce metal oxide films.

Referring to FIG. 1, it can be seen that acetic acid, formic acid used in the related art is characterized by a high melting point. Therefore, acetic acid or formic acid tends to solidify compared with carboxylic acid anhydride or ester, and it is very difficult to stably supply these substances in a vaporized state to a substrate processing apparatus (processing container).

In addition, when formic acid and acetic acid are used, there is a problem of simultaneous formation of monomers and dimers in their vaporized state. See J. Phys. Chem. Ref. Data 7, p. 363 (1993) (Reference 2).

FIG. 2 shows the ratio (composition ratio) of dimers in formic acid described in the aforementioned Reference 2, and FIG. 3 shows the composition ratio of dimers in acetic acid also described in the aforementioned Reference 2. In Fig. 2 and Fig. 3, it should be noted that the composition ratio of dimer is normalized based on the total amount of monomer and dimer.

Referring to Figures 2 and 3, it can be seen that the monomer/dimer composition ratio in formic acid or acetic acid changes significantly with changes in temperature or pressure.

In the case of formic acid in FIG. 2, it can be seen that at a temperature of 300K, formic acid at 1 atm contains dimers with a composition ratio of 90% or more. On the other hand, when the temperature is raised to 500K in this state, it can be seen that the composition ratio of the monomer increases to about 90%.

In addition, it can be seen that the composition ratio of the dimer decreases when the formic acid pressure is decreased from 1 atm to 0.1 atm and the temperature is kept at 300 K.

In addition, when the pressure changes from 1 atm to 0.1 atm, the dimer composition ratio changes more at 400K than at 300K.

As shown in Figure 3, this change in the compositional ratio of monomers and dimers can also be seen in the case of acetic acid.

Among substances for reducing metal oxides, when the composition ratio of monomers and dimers is changed with such a slight change in temperature or pressure, metal oxides such as CuOx are removed from the metal surface by the reduction reaction caused by the substance Processes such as Cu removal inevitably become unstable.

Thus, the inventors of the present invention investigated the reason why the monomer/dimer composition ratio in formic acid or acetic acid changes so dramatically with slight changes in the treatment conditions.

The results of the study found that the dimer was formed due to the hydrogen bonding of the monomers via the -COOH groups contained in the formic acid or acetic acid monomers.

In the presence of multiple monomers, for example, a dimer is formed when an oxygen atom in the -C=O bond of one monomer bonds with a hydrogen atom in the HO-C- bond of another monomer .

In order to overcome this problem, the inventors of the present invention conducted intensive research and found that the use of carboxylic anhydride instead of formic acid or acetic acid can eliminate the problem of unstable substrate handling.

Furthermore, as shown in Figure 1, carboxylic acid anhydride has another advantageous feature of low melting point, which is 80°C to 100°C lower than formic acid or acetic acid. Therefore, the carboxylic anhydride can be stably supplied to the reaction vessel in a gas (vapor) state.

Figure 4 shows the vapor pressure curves of carboxylic anhydride, formic acid, acetic acid and other compounds (esters).

Referring to FIG. 4, the carboxylic anhydride of the present invention exhibits a vapor pressure that is by no means inferior to that of any conventional formic acid or acetic acid, indicating that substrate treatment (metal reduction) can be performed stably and efficiently using the carboxylic anhydride of the present invention.

In addition, as shown in FIG. 4, an ester may be used instead of formic acid or acetic acid as a processing gas for substrate processing (metal reduction).

[First Embodiment]

FIG. 5 shows a substrate processing apparatus according to a first embodiment of the present invention.

Referring to FIG. 5 , the substrate processing apparatus 100 of this embodiment has a processing container 101 in which a processing space 101A is formed, and a stage 103 supporting a substrate W to be processed is placed in the processing space 101A.

A heater 103A for heating the substrate W is embedded in the stage 103 , wherein the heater 103A is connected to a power source 104 to heat the wafer W on the stage 103 to a desired temperature.

The processing container 101A is evacuated to a vacuum state through an exhaust pipe 105 connected to the processing container 101, and can be kept in a reduced pressure state. The suction pipe 105 is connected to the suction pump 106 via a pressure regulating valve 105A, and thereby sets the processing space 101A to a depressurized state having a desired pressure.

In addition, on the side of the processing container 101 facing the bench 103 , there is provided a gas supply unit 102 with a showerhead structure, for example, for supplying processing gas to the processing space 101A in the processing container 101 . The gas supply unit 102 is connected to a gas supply pipe 107 for supplying carboxylic acid anhydride or ester treatment gas.

The gas supply line 107 is equipped with a valve 108 and a mass flow controller (MFC) 109, and is connected to a source material supply unit 110 containing a carboxylic anhydride or ester source material 110a.

The source material supply unit 110 is equipped with a heater 110A, wherein the source material 110a evaporates while being heated by the heater 110A. The vapor of the source material 110 a thus formed is then supplied to the gas supply part 102 via the gas supply pipe 107 .

Since carboxylic acid anhydride or ester is in a liquid form at room temperature, and since the solidification temperature of carboxylic anhydride or ester is lower than that of acetic acid or formic acid, compared with the case of using acetic acid or formic acid as a processing gas, carboxylic anhydride or ester can be used as a processing stability. The elevated process gas is supplied to the process space 101A.

Furthermore, it is preferable to configure the gas supply pipe 107 so that the gas supply pipe 107 can be heated to a temperature higher than the vaporization temperature of the source material. With this configuration, it is possible to prevent gas from condensing inside the gas supply pipe 107 .

The processing gas supplied to the gas supply part 102 is supplied to the processing space 101A via the plurality of air holes 102A formed in the gas supply part 102, whereby the processing gas supplied to the processing space 101A reaches the substrate W, which is held by the heater 103A at Predetermined temperature. Thus, the desired removal of the oxide film from the Cu interconnect pattern formed on the substrate W is achieved by the reduction of Cu.

Furthermore, in the case of gasifying the source material 110a and supplying the gasified source material (processing gas) 110a to the processing space 101A, it may be configured such that the processing gas is mixed with a carrier gas (such as Ar gas, N ₂ gas, or He gas) are supplied to the processing space 101A together.

As the carrier gas, other chemically inert gases such as Ne gas, Kr gas, Xe gas or the like can also be used. In addition, such a rare gas used as a carrier gas can be recovered from the tail gas using a rare gas separation device.

In addition, a gas that does not affect the substrate material or other chemically reducing gas may be added to the carboxylic acid anhydride or ester treatment gas. For such other reducing gases, _H2 , _NH3 and the like can be used.

The operation of the substrate processing apparatus 100 for performing substrate processing is controlled by the control unit 100A, which in turn is controlled by a program stored in the computer 100B. In FIG. 5, it should be noted that various interconnections between the computer 100B, the control unit 100A, and the components of the substrate processing apparatus 100 are omitted.

It should be noted that the control unit 100A includes a temperature control unit 100a, a gas control unit 100b, and a pressure control unit 100c, wherein the temperature control unit 100a controls the temperature of the rack 103 by controlling the power supply 104, and this temperature control of the rack 103 provides In order to control the temperature of the substrate W, the substrate W is heated by the stage 103 .

On the other hand, the gas control unit 100b supervises the opening and closing of the valve 108 and the flow rate control of the MFC 109, and further controls the state of the processing gas supplied to the processing space 101A.

In addition, the pressure control unit 100c controls the valve opening degree of the suction pump 106 and the pressure regulating valve 105A, and controls the pressure in the processing space 101A to a predetermined pressure.

As noted, the control unit 100A is under the control of the computer 100B, and thus, the substrate processing apparatus 100 is actually run by the computer 100B. The computer 100B includes a CPU 100d, a recording medium 100e, an input device 100f, a memory 100g, a communication device 100h, and a display device 100i as usual.

In one embodiment, a program for substrate processing is recorded in the recording medium 100e, and substrate processing is performed according to such program. In addition, the program is loaded through the communication device 100h or through the input device 100f.

Next, experiments of such substrate processing by the substrate processing apparatus 100 will be described in detail below.

In this experiment, acetic anhydride vapor was used as the process gas.

In preparation for substrate processing, an acetic anhydride liquid formed with a purity of 90% or higher is charged into the source material supply unit 110 as the source material 110a in a state where the source material 110a is not exposed to air.

In addition, according to Henry's law, it is expected that the gas in the air may dissolve into the acetic anhydride liquid, and vacuum degassing treatment is performed to obtain and provide almost 100% acetic anhydride vapor.

Furthermore, by heating the source material 110a to a temperature of 303-323K (30-50°C) by using the heater 110A around the source material supply unit 110, the source material acquires sufficient vapor pressure. In this experiment, the temperature of the source material 110a was set to 318K (45°C).

The following substrate treatments were performed according to the procedure explained above.

Firstly, the substrate W with the metal layer to be processed on at least a part thereof is placed on the stage 103, and the temperature control unit 100b controls the heater 103A to heat the substrate W to 303-323K (30-50° C.).

Next, the valve 108 is opened to uniformly supply the process gas from the gas supply part 102 onto the substrate W, wherein the time required for the temperature of the substrate W to rise (during which heat is transferred from the stage 103 to the substrate W) is taken into consideration, from The substrate W is placed on the stage 103 to start timing, and the valve 108 is opened after 2 minutes.

In this embodiment, the MFC 109 is controlled by the gas control unit 100b, and the acetic anhydride vapor is supplied to the processing container 101 at a flow rate of 10-1000 sccm by the gas control unit 100b.

In addition, the pressure regulating valve 105A is controlled using the pressure control unit 100c to control the pressure of the processing space 101A at 10-1000Pa.

In this embodiment, the flow rate of acetic anhydride was set to 100 sccm, and the pressure of the processing space 101A was set to 400 Pa.

Thereby, the substrate W supported on the stage 103 was subjected to substrate processing for 1 minute under the conditions of controlled processing pressure and controlled gas supply rate.

Thereafter, the valve 108 is closed, and the remaining processing gas in the processing space is evacuated by the pump 106 . Thus, the processing is completed, and the substrate W is taken out from the processing container 101 .

Next, with respect to the substrate W thus processed, the amount of reduction of the metal layer (Cu layer), and thus the amount of removal of the oxide film from the Cu layer was evaluated.

Hereinafter, the measurement method of the oxide film thickness on the metal layer and the results of evaluation by the aforementioned measurement method are briefly explained.

Fig. 6 shows the relationship between the parameters ψ (Psi) and Δ (Delta) obtained by visible light ellipsometry, which uses visible light to measure the temperature of an oxide film (copper oxide film) formed on a Cu layer. Film thickness, wherein it should be noted that the relationship of FIG. 6 shows the result of changing the thickness t of the copper oxide film from 0 nm to 30 nm.

Referring to FIG. 6, it can be seen that the polarization angle of visible light ellipsometry changes according to the thickness of the oxide film. In FIG. 6, it should be noted that the values of ψ and Δ were calculated by setting the optical constants of Cu and copper oxide to 0.23577+3.42087i and 2.63595+0.224295i, respectively. For the optical constants used here, see J. Electrochem. Soc. 150, p. G300, 2003 (Reference 3).

Thus, before substrate processing, a Cu thin film was formed on a part of the substrate W, and the surface state of the Cu thin film thus formed was studied using visible light ellipsometry, where Polarization state ρ of visible light

ρ=tanψ·exp(iΔ)

The measurement results confirmed that the parameters ψ and Δ values of the Cu thin film in the state before the substrate processing were -100.23 and 43.82, respectively. According to the relationship shown in FIG. 6, the results indicate that copper oxide was formed with a thickness of 3-4 nm on the surface of the Cu thin film on the substrate W in the state before the treatment.

In the thickness measurement of such thin oxide films, the variation of the film thickness is mainly manifested in the value of the parameter Δ. Therefore, for the present embodiment, the parameter Δ is used to evaluate the surface treatment state of the substrate W, and thereby evaluate the thickness of copper oxide.

Substrate W was subsequently treated by acetic anhydride at a pressure of 400 Pa and a temperature of 523 K (250° C.) as explained in the previous embodiment.

More specifically, the Cu surface on the substrate W was measured again using the visible light ellipsometry technique after the aforementioned substrate treatment was performed for 1 minute.

In this measurement, the values of the parameters Δ and ψ were confirmed to be -106.63 and 43.79, and these values indicated that the thickness of the copper oxide film was reduced to 1-2 nm.

From the above results, it was confirmed that the copper oxide film can be removed by the substrate treatment using acetic anhydride even if the treatment is performed at a low substrate temperature of 250° C. or less.

Next, in another experiment, substrate treatment was similarly performed using acetic anhydride as described above but at a pressure of 100 Pa and a substrate temperature of 250°C or higher, and copper oxide was measured by visible light ellipsometry similarly to the previous case thickness of.

The results of the foregoing measurements confirm that a substrate temperature higher than 250° C. can be used to increase the rate of copper oxide film thickness reduction.

From this experiment it can be seen that treatment with acetic anhydride of the present invention is effective at both low and high temperatures. Therefore, the substrate treatment of the present invention can be performed at a high temperature of 250° C. or higher as long as it does not cause damage to the insulating film.

In order to confirm the effect of reducing the thickness of the residual copper oxide film, ellipsometry was performed on the substrate subjected to the aforementioned treatment for 10 minutes.

The measurement results confirmed that the value of the parameter Δ was -110, which indicated that there was no copper oxide film on the Cu film.

Although the foregoing experiment was performed using acetic anhydride to remove the Cu oxide film (reduction of Cu), the present invention is not limited to the case of using acetic anhydride, but other carboxylic anhydrides having similar reactivity may also be used.

The carboxylic acid anhydride that can be used as a processing gas can be generally expressed as R1-CO-O-CO-R2, wherein R1 and R2 are hydrogen atoms, hydrocarbon groups, or any of the functional groups in which at least a part of the hydrogen atoms constituting the hydrocarbon group are substituted by halogen atoms. A sort of.

Thus, the hydrocarbyl group may be any of an alkyl, alkenyl, alkynyl, aryl, or similar group. As the halogen atom, any of fluorine, chlorine, bromine and iodine can be used.

Furthermore, as the carboxylic anhydride, acetic anhydride, formic anhydride, propionic anhydride, acetic formic anhydride, butyric anhydride, valeric anhydride, and the like can be used. Since formic anhydride and acetic formic anhydride are relatively unstable substances, it is more preferable to use a carboxylic anhydride other than formic anhydride or acetic formic anhydride.

In addition, similar treatment can also be achieved by using esters with properties close to those of carboxylic anhydrides instead of carboxylic anhydrides as the treatment gas. This ester can be generally expressed as R3-COO-R4, wherein R3 is any one of a hydrogen atom, a hydrocarbon group or a functional group in which at least a part of the hydrogen atoms constituting the hydrocarbon group are replaced by a halogen atom, and R4 is a hydrocarbon group or a hydrogen atom constituting the hydrocarbon group A functional group in which at least a part is substituted by a halogen atom.

More specifically, such hydrocarbyl groups may be any of alkyl, alkenyl, alkynyl, aryl, or the like. As the halogen atom, any of fluorine, chlorine, bromine and iodine can be used.

In addition, for the aforementioned esters, methyl formate, ethyl formate, propyl formate, butyl formate, benzyl formate, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, amyl acetate, hexyl acetate, Esters, Octyl Acetate, Phenyl Acetate, Benzyl Acetate, Allyl Acetate, Propyl Acetate, Methyl Propionate, Ethyl Propionate, Butyl Propionate, Amyl Propionate, Benzyl Propionate, Butyric Acid Methyl ester, ethyl butyrate, amyl butyrate, butyl butyrate, methyl valerate, ethyl valerate and the like.

Regarding the reduction reaction by the aforementioned carboxylic acid anhydride or ester, the reduction reaction can be initiated by the following mechanism.

One possibility is that the C=O bond in the carboxylic acid anhydride or ester contributes to the aforementioned reduction reaction. Furthermore, considering the fact that the processability improves when water (H ₂ O) is added, it is possible that water chemisorbed in the oxide film on the metal layer or water physically adsorbed on the surface of the oxide film contributes to the reduction reaction. In addition, water may also adsorb on the metal layer.

In addition, it should be noted that the aforementioned substrate treatment (reduction reaction) can be used to remove the oxide film formed on the metal interconnect pattern, especially the Cu interconnect pattern, during the semiconductor device manufacturing process.

In such a semiconductor device, an interlayer insulating film embedded with a metal interconnection pattern is generally formed on a substrate to be processed. Thus, in the reduction reaction caused by the above-mentioned carboxylic acid anhydride or ester, water (H ₂ O) adsorbed on the interlayer insulating film is highly likely to contribute to the reaction. In this case, by performing the substrate treatment of the present invention, dehydration of the interlayer insulating film can be performed while removing the oxide film from the metal interconnection pattern. In this case, water that contributes to the reduction reaction of the metal interconnection pattern is obtained from the interlayer insulating film.

7 is a graph comparing the results of thermal desorption spectroscopy (TDS) for degassing a processed substrate carrying an insulating film thereon before and after substrate treatment with acetic anhydride according to the present invention. In FIG. 7, the horizontal axis represents the temperature of the substrate to be processed, and the vertical axis represents the degassing intensity, and it should be noted that this intensity is proportional to the amount of degassing.

Referring to FIG. 7 , it can be seen that in the entire temperature region, the outgassing amount decreased after the substrate treatment with acetic acid compared to the substrate before treatment.

In Fig. 7, it should be noted that the amount of outgassing was compared under the same conditions except that substrate treatment was performed with acetic anhydride in one group and without such substrate treatment in the other group. Therefore, the aforementioned spectral differences are attributed to the presence and absence of substrate treatment with acetic acid.

Therefore, it is believed that the results of FIG. 7 reflect that the amount of degassing by heating is reduced due to the outgassing of substances contained in the interlayer insulating film, which in turn is caused by the substrate treatment using acetic anhydride. As noted above, such substances include water.

In addition, since the evolution of water vapor occurs in the temperature range of 100-600° C. included in FIG. 7 , as shown in FIG. 7 , the gas evolution by heating includes the evolution of water or water vapor. Therefore, based on the above, we believe that the substrate treatment with acetic anhydride causes accelerated dehydration of the interlayer insulating film. With such dehydration of the interlayer insulating film, effects such as improvement in withstand voltage of the interlayer insulating film can be obtained.

Fig. 8 is a graph comparing the dielectric constants of various interlayer insulating films before and after the acetic anhydride treatment of the present invention. In FIG. 8, it should be noted that interlayer insulating films 1 and 2 are made of a low-k material, while interlayer insulating films 3 and 4 are made of, for example, a diffusion barrier used as a Cu multilayer interconnect structure cap layer (cap layer). layer formation.

Referring to FIG. 8, it can be seen that there is little change in the dielectric constants of the interlayer insulating films 1 and 2 before and after the substrate processing. In addition, it should be noted that even after such substrate treatment with acetic anhydride, these interlayer insulating films maintained a low dielectric constant lower than that of _SiO2 .

In addition, it was confirmed that the dielectric constants of the insulating films 3 and 4 did not change at all. Furthermore, it can be seen that the insulating films 3 and 4 conventionally used as diffusion barrier layers maintain a low dielectric constant lower than that of SiNx.

Therefore, it was confirmed that the substrate treatment using acetic anhydride of the present invention is a treatment that does not cause a change in the dielectric constant of the insulating film. The fact that the dielectric constant of the insulating film does not change means that the substrate treatment using acetic anhydride of the present invention is a treatment that does not cause damage to the treated insulating film.

It should be noted that such an improvement in electrical properties of the insulating film caused by dehydration is particularly enhanced in the case where the interlayer insulating film is a low-K (low dielectric constant) material characterized by strong water absorption. Such a film of a low-K material used as a low-k interlayer insulating film includes a porous film and a fluorine-containing film such as a CxFy film or a SiOF film.

In addition, it was confirmed that in the case of using acetic anhydride as the process gas, for the materials used for the device, including quartz, alumina, aluminum nitride, anodized aluminum (JIS A5052 and A5052 treated with OGF (registered trademark) ), stainless steel (JIS SUS304 and SUS316), nickel, Hastelloy (trademark), and the like, do not cause a meaningful quality change even if they are exposed to acetic anhydride at 300°C and 100Pa.

In addition, the results of total reflection X-ray fluorescence measurements performed on silicon wafers exposed to an acetic anhydride environment confirmed that metal contamination by the aforementioned device materials was below the detection limit of total reflection X-ray fluorescence. From this result it was concluded that acetic anhydride did not cause significant corrosion to the device materials.

[Second Embodiment]

In order to improve the efficiency of the reduction reaction, H ₂ O can also be actively added into the reaction vessel.

The following describes the configuration of the second embodiment of the present invention in which an H ₂ O supply unit is added to the substrate processing apparatus 100 to supply water vapor into the processing container 101 .

FIG. 9 is a diagram showing the configuration of a substrate processing apparatus 100P according to a second embodiment of the present invention, in which components corresponding to the aforementioned components are denoted by the same reference numerals, and descriptions thereof are omitted.

Referring to FIG. 9, the structure of the substrate processing apparatus 100P of this embodiment is similar to that of the substrate processing apparatus 100 in _FIG . steam (H ₂ O).

Thus, the substrate processing apparatus 100P of the present embodiment _{is equipped with the gas mixing unit 102A connected to the gas supply unit 102, and the gas mixing unit 102A is supplied with water vapor (H 2 O} ). Additionally, the gas mixing component 102A is configured to receive water vapor from the water vapor generator 112 .

Using the configuration of FIG. 9 , water is supplied to the reaction promotion chamber 102B formed inside the gas mixing part 102A from the gas supply pipe 111 connected to the reaction promotion chamber 102B together with the gas supply pipe 107 . Thus, in the reaction promotion chamber 102B, both carboxylic acid anhydride or ester and H ₂ O are supplied and mixed with each other.

A mixed gas of carboxylic anhydride or ester and H ₂ O is supplied to the processing space 101A via the gas supply means 102 . In addition, a heater 102b is installed outside the reaction promoting chamber 102B to heat the mixed gas of carboxylic anhydride or ester and _H2O to a predetermined temperature, which may be higher than the substrate temperature.

In addition, the steam generator 112 is supplied with oxygen and hydrogen via gas lines 113 and 117 , respectively, wherein the gas line 113 is connected to an oxygen source 116 via a valve 114 and an MFC 115 . Similarly, gas line 117 is connected to hydrogen source 117 via valve 118 and MFC 119 .

Thus, for this embodiment, the gas supply unit 100b further controls the switching operations of the valves 114 and 118, controls the MFCs 115 and 117, and further controls the steam generator 112, thereby controlling the gas supply via the gas supply pipeline 111 through the gas control unit 100b. of water vapor.

By performing substrate processing using the substrate processing apparatus 100P of this embodiment, water vapor can be supplied to the processing space 101A in addition to carboxylic acid anhydride or ester. Therefore, the metal oxide film on the metal interconnection pattern can be removed in less time than in the case of not supplying water vapor.

In order to perform the dehydration treatment of the interlayer insulating film or the insulating film simultaneously with the present embodiment, it is desirable to control the amount of water vapor supplied thereby in consideration of the insulating film dehydration effect.

Therefore, in the case where the interlayer insulating film is formed of a highly water-absorbing material, the amount of water vapor supplied to the processing space 101A is set to be small or even 0, while in the case where the interlayer insulating film is formed of a material having little water absorption In the case of material formation, the amount of water vapor supplied to the processing space 101A may be increased to increase the removal efficiency of the metal layer.

[Third Embodiment]

FIG. 10 shows the configuration of a substrate processing apparatus 100Q according to a third embodiment of the present invention, in which components corresponding to the aforementioned components are denoted by the same reference numerals, and descriptions thereof are omitted.

Referring to FIG. 10 , the structure of the substrate processing apparatus 100Q of this embodiment is similar to that of the substrate processing apparatus 100P of _FIG .

In the illustrated example, the H ₂ O detection unit includes an infrared source 121A and an infrared detector 122B disposed on the processing container 101 to face each other across the processing space 101A. In addition, the processing container 101 is equipped with infrared windows 122A and 122B corresponding to the infrared source 121A and the infrared detector 121B, respectively.

Therefore, with the configuration of FIG. 10 , an infrared lamp or the like is provided as an infrared source 121A at a position corresponding to the infrared window 122A, and an interference filter 123 and an infrared detector 121B are provided at a position corresponding to the infrared window 122B.

The measurement of water vapor is performed by the aforementioned _H2O detection unit as follows.

First, in the evacuated state of the processing container 101, the infrared beam IR is irradiated into the processing space 101A from the infrared source 121A, and the transmission intensity of the infrared beam passing through the processing space 101A in this state is measured by the infrared detector 121B.

Next, with water vapor supplied to the processing space 101A, the intensity of the infrared beam passing through the processing space 101A is measured by emitting the infrared beam from the infrared source 121A and detecting the infrared beam with the infrared detector 121B.

Thereby, the attenuation of the infrared beam caused by the water vapor added to the processing space 101A can be measured, and accordingly the amount of H ₂ O in the processing container 101 can be detected.

For the interference filter 123, it is preferable to use a filter element having a transmission band in a wavelength in which a decrease in the transmission intensity of the infrared beam occurs due to absorption of _H2O . Preferably, the transmission band of the infrared filter 123 is 3 microns to 6-7 microns. Furthermore, a plurality of filter elements having different wavelength bands may be provided for the interference filter 123 . Using this configuration, the H ₂ O component can be detected with higher precision.

In addition, the infrared source 121A and the infrared detector 121B may be configured by a unitary body using a multiple mirror.

Furthermore, it may be configured to control the amount of water vapor supplied from the water vapor generator 112 based on the detection value of the infrared detector 121B, which together with the infrared source 121A constitutes a _H2O detection unit.

In this case, the gas control unit 100b controls the water vapor generator 112 so that the detected value of water vapor is kept constant at an optimum value. In addition, the H ₂ O detection unit can also be used to measure the dehydration effect of the interlayer insulating film.

Furthermore, the amount of water vapor supplied to the processing container 101 can be controlled in consideration of the degree of dehydration of the interlayer insulating film. For example, when a substance with strong water absorption is used as the interlayer insulating film, the amount of supplied water vapor can be controlled to be small or zero, and when the interlayer insulating film is formed of a substance with low water absorption, the amount of supplied water vapor can be increased. amount.

In addition, the substrate processing apparatus 100 of the first embodiment may be equipped with the H ₂ O detection unit of the present embodiment. In this case, the amount of H ₂ O added to the processing container 101 in a state adsorbed on the substrate can be detected, and the pretreatment of the substrate processing of the present invention can be optimized, for example, the adsorption can be changed according to the detected value of H ₂ O. water method.

[Fourth Embodiment]

FIG. 11 is a diagram showing the configuration of a substrate processing apparatus 100R according to a fourth embodiment of the present invention, in which components corresponding to the aforementioned components are denoted by the same reference numerals, and descriptions thereof are omitted.

Referring to FIG. 11 , the structure of the substrate processing apparatus 100R of this embodiment is similar to that of the substrate processing apparatus 100Q of the previous embodiment, except that the H ₂ O detection unit is assembled on the exhaust pipe 105 this time.

Therefore, for the present embodiment, the infrared source 121A and the infrared detector 121B are provided for the air extraction duct 105 so as to face each other, and the air extraction duct 105 is provided with infrared windows 122A and 122B respectively corresponding to the infrared source 121A and the infrared detector 121B. .

Furthermore, similarly to the substrate processing apparatus 100Q of the previous embodiment, an infrared lamp is provided as the infrared source 121A corresponding to the infrared window 122A, and a noise filter 123 and an infrared detector 121B are provided corresponding to the infrared window 122B.

Furthermore, in the case of providing the H ₂ O detection unit for the pumping duct 105 , it is preferable to provide an infrared source 121A and an infrared detector 121B as shown in FIG. 11 in order to increase the optical path length. Therefore, it is preferable to arrange the infrared source 121A and the infrared detector 121B to face each other at a predetermined distance in the suction direction of the suction duct 105 .

By arranging the infrared source 121A and the infrared detector 121B as described above, a very long optical path length is ensured between the infrared source 121A and the infrared detector 121B, and even if the light absorption generated therein is small, it is possible to Detect the amount of water vapor. Additionally, multiple mirrors can be used to increase the optical path length.

It should be noted that the H ₂ O detection unit is not limited to the above configuration, but other configurations such as a configuration using an oscillator and a millimeter wave detector may be used. In this case, the oscillation wavelength can be set to coincide with the absorption band of _H2O .

In addition, a _H2O monitor may be provided on the wall of the evacuated part of the processing vessel 101, which measures the amount of _H2O by detecting the capacitance change of the polymer film caused by the absorption of water.

[Fifth Embodiment]

FIG. 12 shows the configuration of a substrate processing apparatus 100S according to a fifth embodiment of the present invention, in which components corresponding to the aforementioned components are denoted by the same reference numerals, and descriptions thereof are omitted.

Referring to FIG. 12 , a substrate processing apparatus 100S is similar in configuration to the substrate processing apparatus 100 of FIG. 5 except that a source material supply unit 310 is provided instead of the source material supply unit 110 of the substrate processing apparatus 100 .

Referring to FIG. 12 , the source material supply unit 310 is a bubbling unit in which the vapor of the source material 110 a is supplied to the processing space 101A inside the processing container 101 via the gas supply pipe 107 after gasification or sublimation is caused therein.

Thus, an inert gas is supplied from the gas pipe 311 to the source material supply unit 310 as a carrier gas, and the vapor of the source material formed by vaporization or sublimation is supplied to the processing container 101 together with the carrier gas.

Also in this embodiment, the substrate processing apparatus 100S can be used similarly to the substrate processing apparatus 100 of the first embodiment with a similar effect.

Furthermore, vaporization (supply) of the source material 110a may be performed by (direct) liquid injection.

[Sixth Embodiment]

Next, referring to FIGS. 13A-13E , as a sixth embodiment of the present invention, a semiconductor device manufacturing method according to the substrate processing method of the present invention will be described. Hereinafter, the method may be implemented using any of the above-described substrate processing apparatuses 100 , 100P, 100Q, 100R, and 100S.

Referring to FIG. 13A, an insulating film 201, such as a silicon dioxide film, is formed on a semiconductor substrate (not shown) corresponding to the above-mentioned substrate W, so that the silicon dioxide film 201 covers active elements such as transistors (not shown) formed on the silicon substrate. show). In the silicon dioxide film 201 , an interconnection pattern (not shown) such as to be electrically connected to an active layer formed of W (tungsten) is provided, and a Cu interconnection layer 202 is formed on the silicon dioxide film 201 .

A first insulating layer (interlayer insulating film) 203 is formed on the silicon dioxide film 201 so as to cover the interconnection layer 202 .

An interconnection groove 204a and a through hole 204b are formed on the first insulating layer 203, wherein the interconnection groove 204a and the through hole 204b are filled with Cu, and are formed together by the Cu groove pattern in the interconnection groove 204a and the through hole 204b. The Cu via plugs form the interconnect pattern 204 . The interconnect pattern 204 is thus electrically connected to the interconnect layer 202 at the Cu via plugs.

In addition, it can be seen in FIG. 13A that a barrier metal film 204c is formed between the first insulating layer 203 and the interconnection pattern 204, wherein it should be noted that the role of the barrier metal film 204c is to block the diffusion of Cu atoms from the interconnection pattern 204 to The first insulating layer 203 . Furthermore, an insulating layer 205 serving as a Cu diffusion barrier is formed to cover the interconnect pattern 204 and the first insulating film 203, and a second insulating layer (interlayer insulating film) 206 is further formed on this Cu diffusion barrier 205.

A method of manufacturing a semiconductor device by forming a Cu interconnection pattern in the second insulating layer 206 using the aforementioned substrate processing method is described below. From this, it should be noted that the interconnection member 204 can also be formed by the same method described below.

Referring to FIG. 13B, a step of forming interconnect grooves 207a and via holes 207b in the second insulating layer 206 using a dry etching method or the like is performed, wherein it should be noted that the via holes 207b are formed to penetrate the insulating layer 205. Thus, a portion of the Cu interconnection pattern 204 is exposed at the via hole 207b thus formed in the second insulating layer 206, and this exposure may cause an oxide film (not shown) to be formed on the exposed surface of the Cu interconnection pattern 204. ).

Thus, in the step of FIG. 13C , by applying the substrate processing explained with reference to the first embodiment while using any of the substrate processing apparatuses 100 , 100P, 100Q, 100R, and 100S to cause a reduction reaction of Cu, proceed from exposure to A method for removing any Cu oxide film thus formed on the Cu surface. Thus, removal of the Cu oxide film is achieved by supplying vapor of carboxylic anhydride or ester to the substrate to be treated under substrate heating.

In this reduction method of the present invention, the temperature of the substrate can be lowered compared with the case where the reduction reaction is performed with _H2 or _NH3 as in the related art. For example, reduction treatment can be performed at a temperature of 573K (300°C) or lower using the present invention. This low-temperature substrate processing of the present invention enables reduction reaction processing at a low temperature such as 573K (300°C) or lower, and this low-temperature method is ideal for the case where the interlayer insulating film is formed of a low-k material that is easily damaged by heat particularly advantageous.

On the other hand, when the substrate temperature of the aforementioned substrate treatment is too low, the reduction reaction may not proceed sufficiently. Therefore, the present invention preferably uses a substrate temperature of 373K (100° C.) or higher for substrate processing. Therefore, in the substrate processing process of the present invention, it is preferable to control the substrate temperature at 373K (100°C) to 573K (300°C).

As described above, dehydration of the interlayer insulating film can be achieved while removing copper oxide from the copper interconnection pattern 204 by the method of the present invention. In this case, carboxylic acid anhydride or ester is provided to the second insulating layer 206 to promote dehydration of the layer 206 . Thus, the electrical properties of the second insulating layer 206 are improved. This improvement includes a reduction in dielectric constant, an increase in withstand voltage, and the like.

Although such improvement in electrical properties is achieved by dehydration in the case where the second insulating layer 206 is a silicon dioxide film (SiO ₂ ), when the second insulating layer 206 is made of a low-k material characterized by strong water absorption such as porous In the case of forming a film or a fluorine-containing film, the improvement effect becomes particularly remarkable.

In addition, in order to improve the removal efficiency of Cu oxide, water vapor (H ₂ O) may be supplied to the substrate to be processed while using the substrate processing apparatus 100P in this process step. Therefore, it is preferable to control the supply amount of water vapor according to the dehydration effect of the interlayer insulating film. This controlled supply of water vapor is advantageously achieved using the substrate processing apparatus 100Q or 100R. By using the substrate processing apparatus 100Q or 100R, the supply amount of water vapor can be set to be small or zero when using a highly water-absorbent material as the interlayer insulating film. In addition, when a material with little water absorption is used as the interlayer insulating film, the amount of water vapor supplied can be increased to improve the stability of the copper oxide removal reaction.

Next, in the step of FIG. 13D , on the second insulating film 206 including the inner wall surfaces of the interconnection groove 207a and the via hole 207b, and further on the exposed surface of the Cu interconnection pattern 204, formation of a barrier metal film 207c is performed. . Usually, the barrier metal film 207c is formed of a refractory metal or a nitride thereof, or a laminate of a refractory metal film and a nitride film. For example, the barrier film 207c is formed of a Ta/TaN film, a WN film, or a TiN film, and can be formed by a sputtering method or a CVD method. Furthermore, this barrier metal film 207c can be formed by a so-called ALD (Atomic Layer Deposition) method.

Next, in the step of FIG. 13E, a Cu interconnect pattern 207 is formed on the barrier metal film 207c to fill the interconnect groove 207a and the via hole 207b. Such a Cu interconnection pattern 207 may be formed by an electroplating method after forming a Cu seed layer by a sputtering method or a CVD method. In addition, the interconnection pattern 207 may be formed by a CVD method or an ALD method.

After the interconnection pattern 207 is formed, the substrate is planarized by a chemical mechanical polishing (CMP) method.

In addition, after the step of FIG. 13E , a (2+n)th insulating layer (n is an integer) may be formed, and a Cu interconnection pattern may be formed in each insulating layer to form a desired multilayer interconnection structure.

Although the present embodiment has been described for the case of simultaneously forming a Cu multilayer interconnection structure using a dual damascene method, the present invention is also effective in the case of forming such a multilayer interconnection structure by a single damascene method.

In addition, although the above has been described for the case of forming a Cu interconnection pattern as a metal interconnection pattern or an interconnection layer in an insulating layer, the present invention is not limited to such a Cu interconnection pattern, but can also be used for A case where a metal interconnection pattern of Ag, W, Co, Ru, T, Ta, or the like is formed.

Therefore, according to the manufacturing method of the present embodiment, the oxide film formed on the metal interconnection pattern can be reliably and reproducibly removed. Furthermore, with this embodiment mode, dehydration of the interlayer insulating film can be performed simultaneously with removal of the oxide film from the metal interconnection pattern.

Thus, the dehydration process for removing the oxide film and the interlayer insulating film from the metal interconnection pattern can be performed simultaneously, simplifying the manufacturing method of the semiconductor device.

In addition, although the description has been made on the case where the dehydration for removing the oxide film from the metal layer and the dehydration of the interlayer insulating film are performed simultaneously, the present invention is by no means limited to this simultaneous method, and the metal oxide film can be hardly removed from the metal layer. In the case of a physical film, the dehydration process of the interlayer insulating film is performed separately. In this case, the carboxylic acid anhydrides or esters in the foregoing embodiments can be used. This method can be performed using a substrate processing method similar to that described with reference to the foregoing embodiments and a similar substrate processing apparatus.

Although the present invention has been explained with preferred embodiments, the present invention is by no means limited to such specific embodiments, and various changes and modifications can be made without departing from the scope of the present invention.

The substrate processing method of the present invention can be used not only as a method for removing the Cu oxide film from the exposed surface of the underlying Cu interconnect pattern (exposed due to the etching of the insulating layer), but also as a method for removing surface Cu oxide film in other process steps. film method. For example, the present invention can be used after forming a seed layer or an interconnection pattern or after performing a CMP method.

According to the present invention, a substrate processing method and a substrate processing apparatus capable of stably and efficiently removing an oxide film formed on a metal layer on a substrate to be processed can be provided.

Furthermore, according to the present invention, it is possible to provide a semiconductor device manufacturing method in which an oxide film formed on a metal interconnection pattern during the semiconductor device manufacturing process is stably and efficiently removed.

This application is based on Japanese Priority Applications 2006-086569 filed on March 27, 2006 and 2007-045748 filed on February 26, 2007, the entire contents of which are incorporated herein by reference.

Claims (23)

1. A substrate processing method, the substrate has an insulating film and a metal layer, the method may further comprise the steps: providing the substrate with carboxylic anhydride; and The substrate is heated during the step of providing the substrate with the carboxylic anhydride. 2. The method of claim 1, wherein the metal layer comprises a Cu layer. 3. The method according to claim 1, wherein the oxide film on the metal layer is removed in the processing step. 4. The method according to claim 3, wherein the treating step causes dehydration of the insulating film. 5. The method according to claim 4, wherein the insulating film comprises at least one of a porous film and a fluorine-containing film. 6. The method of claim 1, wherein the treating step supplies _H2O together with the carboxylic anhydride. 7. The method of claim 1, wherein the carboxylic anhydride comprises at least one of acetic anhydride, propionic anhydride, butyric anhydride, and valeric anhydride. 8. A method of manufacturing a semiconductor device having a metal interconnection pattern and an interlayer insulating film, the method comprising the following processing steps: providing carboxylic acid anhydride to the substrate having the metal interconnection pattern and the interlayer insulating film; and The substrate is heated during the step of providing the substrate with the carboxylic anhydride. 9. The method of claim 8, wherein the metal interconnection pattern comprises a Cu pattern. 10. The method according to claim 8, wherein said treating step removes an oxide film on said metal interconnection pattern. 11. The method according to claim 10, wherein the treating step causes dehydration of the interlayer insulating film. 12. The method according to claim 11, wherein the interlayer insulating film includes at least one of a porous film and a fluorine-containing film. 13. The method of claim 8, wherein the treating step supplies _H2O to the substrate along with the carboxylic anhydride. 14. The method of claim 8, wherein the carboxylic anhydride comprises at least one of acetic anhydride, propionic anhydride, butyric anhydride, and valeric anhydride. 15. A substrate processing device for processing a substrate having an insulating film and a metal layer thereon, comprising: a stage supporting and heating the substrate; a processing vessel housing the rack therein; supplying process gas to a gas supply within the process vessel; and an extraction means for extracting gas from said processing vessel, The process gas described therein contains carboxylic acid anhydride. 16. The substrate processing apparatus according to claim 15, wherein the metal layer forms a metal interconnection pattern, and wherein the insulating film forms an interlayer insulating film carrying the metal interconnection pattern. 17. The substrate processing apparatus of claim 16, wherein the processing gas removes an oxide film from the metal layer. 18. The substrate processing apparatus according to claim 17, wherein the processing gas further performs dehydration of the interlayer insulating film. 19. The substrate processing apparatus according to claim 15, further comprising an _H2O supply unit supplying _H2O into the processing container. 20. The substrate processing apparatus according to claim 19, wherein the _H2O supply unit comprises a steam generator. 21. The substrate processing apparatus according to claim 15, further comprising an _H2O detector for detecting _H2O in any one of the processing container or the exhaust means. 22. The substrate processing apparatus according to claim 19, further comprising an H ₂ O detector for detecting H 2 O in the processing container, and the substrate processing apparatus detects H ₂ O according to the detection value of the H ₂ O detection unit The amount of H ₂ O supply from the H ₂ O supply unit is controlled. 23. The substrate processing apparatus according to claim 21, wherein the _H2O detection unit comprises an infrared source and an infrared detector.

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