Hafnium oxide film modification method and nonvolatile memory device

Abstract

To provide a hafnium oxide film modification method etc., capable of crystallizing (modifying) an amorphous hafnium oxide film into a hafnium oxide (film) consisting principally of ferroelectric o phase (orthorhombic phase).SOLUTION: There is provided a hafnium oxide film modification method, which comprises: a film deposition process S11 of depositing an amorphous hafnium oxide film on a silicon substrate; and a crystallization process S12 of irradiating the amorphous hafnium oxide film with pulse laser light having a wavelength in the ultraviolet range so that the amorphous hafnium oxide film is modified into a hafnium oxide film consisting principally of an o phase and the hafnium oxide film consisting principally of the o phase does not cohere.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a method for modifying a hafnium oxide film and a non-volatile memory device.

Background Art

[0002] A crystallization process of annealing a silicon substrate with a hafnium oxide film is performed. In addition to normal resistance heating, there is also RTA (Rapid Thermal Annealing), etc. An example of the annealing process is described in Patent Document 1, for example.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, since hafnium oxide, which can have multiple crystal phases, has the paraelectric m phase (monoclinic phase) as the most stable crystal phase, it is difficult to suppress the most stable m phase and crystallize (modify) it into a hafnium oxide (film) mainly composed of the ferroelectric o phase (orthorhombic phase) by the above crystallization process.

[0005] Other problems and novel features will become apparent from the description of this specification and the accompanying drawings.

Means for Solving the Problems

[0006] A method for modifying a hafnium oxide film according to an embodiment includes a film forming step of forming an amorphous hafnium oxide film on a silicon substrate, and a crystallization step of irradiating the amorphous hafnium oxide film with pulsed laser light having a wavelength in the ultraviolet region so that the amorphous hafnium oxide film is modified into a hafnium oxide film mainly composed of the o-phase and no aggregation occurs in the hafnium oxide film mainly composed of the o-phase.

Effects of the Invention

[0007] According to the above embodiment, it is possible to provide a method for modifying a hafnium oxide film capable of crystallizing (modifying) a hafnium oxide (film) mainly composed of the ferroelectric o-phase, and a non-volatile memory device.

Brief Description of the Drawings

[0008]

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Mode for Carrying Out the Invention

[0009] Hereinafter, specific embodiments will be described in detail with reference to the drawings. However, the present invention is not limited to the following embodiments. Also, for clarity of explanation, the following description and drawings are appropriately simplified.

[0010] <Outline of the Hafnium Oxide Film Modification Method> First, the outline of the hafnium oxide film modification method of the present disclosure will be described.

[0011] FIG. 1 is a flowchart of the hafnium oxide film modification method of the present disclosure.

[0012] As shown in FIG. 1, the hafnium oxide film modification method of the present disclosure includes preparing a silicon substrate 10 (step S10), a film forming step (step S11) of forming an amorphous hafnium oxide film 20 on the silicon substrate 10, and a crystallization step (step S12) of irradiating the amorphous hafnium oxide film 20 with pulsed laser light having a wavelength in the ultraviolet region (crystallizing the hafnium oxide film). In the crystallization step, the energy density, wavelength, pulse interval, and pulse width of the pulsed laser light are selected so that the amorphous hafnium oxide film 20 is modified into a hafnium oxide film mainly composed of the o-phase and aggregation of the hafnium oxide film mainly composed of the o-phase (orthorhombic phase) does not occur.

[0013] According to the method for modifying a hafnium oxide film of the present disclosure, an amorphous hafnium oxide film 20 formed on a silicon substrate 10 can be crystallized (modified) into a hafnium oxide film in which the most stable m-phase is suppressed, that is, a hafnium oxide film mainly composed of a ferroelectric o-phase.

[0014] That the hafnium oxide film has been crystallized (modified) into a hafnium oxide film in which the most stable m-phase is suppressed, that is, a hafnium oxide film mainly composed of a ferroelectric o-phase, can be confirmed by evaluating the hafnium oxide film (crystalline phase) crystallized in step S12 using an X-ray diffractometer (step S13). In FIG. 1, "a-HfO2" represents the amorphous hafnium oxide film 20. In FIG. 1, "x-HfO2" represents the crystallized hafnium oxide film 20. In FIG. 1, "(o)-HfO2" represents a hafnium oxide film in which the most stable m-phase is suppressed, that is, a hafnium oxide film mainly composed of a ferroelectric o-phase.

[0015] The hafnium oxide film in which the most stable m-phase is suppressed and which has been crystallized (modified) by the method for modifying a hafnium oxide film of the present disclosure, that is, the hafnium oxide film mainly composed of a ferroelectric o-phase, can be applied to a non-volatile memory device.

[0016] <Background leading to the method for modifying a hafnium oxide film> Next, the background leading to the method for modifying a hafnium oxide film of the present disclosure will be described.

[0017] Conventionally, in the field of non-volatile memory devices, PZT (lead zirconate titanate), SBT (strontium bismuth tantalate), etc. have been used as ferroelectric materials and have been commercialized in the form of 1T1C (capacitor type). FIG. 2(a) is a schematic configuration diagram of 1T1C (capacitor type).

[0018] On the other hand, for the purpose of increasing the density, the present inventors applied the above-mentioned conventional ferroelectric material to 1T (transistor type) and also studied thinning the above-mentioned conventional ferroelectric material film. FIG. 2(b) is a schematic configuration diagram of 1T (transistor type).

[0019] However, when applying the above-mentioned conventional ferroelectric material to 1T (transistor type), it has been known that there are limitations in thinning the film and there are problems with the affinity with a silicon substrate.

[0020] Therefore, the inventors of the present invention considered using hafnium oxide (HfO2) that exhibits ferroelectricity in an extremely thin film and can be directly formed on a silicon substrate as a ferroelectric material of 1T (transistor type).

[0021] However, since hafnium oxide that can have multiple crystal phases has the m phase (monoclinic phase) of paraelectricity as the most stable crystal phase, the inventors of the present invention studied a method for crystallizing hafnium oxide in which the m phase of the most stable phase is suppressed. The inventors of the present invention conducted a plurality of experiments in the process of this study.

[0022] As a result, the inventors of the present invention found a method for crystallizing (modifying) an amorphous hafnium oxide film formed on a silicon substrate into a hafnium oxide film in which the m phase of the most stable phase is suppressed, that is, a hafnium oxide film mainly composed of the ferroelectric o phase (the method for modifying a hafnium oxide film of the present disclosure).

[0023] Hereinafter, Experiments 1 to 6 conducted by the inventors of the present invention to lead to the method for modifying a hafnium oxide film of the present disclosure will be described.

[0024] <Experiment 1> Experiment 1 was carried out under the conditions shown in Table 1 below.

[0025]

Table 1

[0026] <Film formation in Experiment 1> FIG. 3 is a schematic diagram showing a state in which an amorphous hafnium oxide film 20 is being formed on a silicon substrate 10.

[0027] In Experiment 1, using a film-forming apparatus (ALD apparatus (demo machine) manufactured by JSW Affti), an amorphous hafnium oxide film 20 was formed on a silicon substrate 10 by the thermal-ALD method. ALD is an abbreviation for Atomic Layer Deposition and is also called atomic layer deposition. Hereinafter, the amorphous hafnium oxide film 20 formed on the silicon substrate 10 by the thermal-ALD method will be referred to as the hafnium oxide film 20 T is described.

[0028] Specifically, as shown in FIG. 3, by bringing one side of the silicon substrate 10 heated to 120 degrees by a heater into contact with the flowing source gas, oxidizing agent, and inert gas, an extremely thin hafnium oxide film 20 with a film thickness of 10 nm was formed on the silicon substrate 10 T was formed. TEMAH (Tetrakis(EthylMethylAmido)Hafnium) was used as the source gas, O3 was used as the oxidizing agent, and N2 was used as the inert gas.

[0029] <Crystallization (modification) of Experiment 1> FIG. 4 is a schematic diagram showing the state of crystallizing (modifying) the hafnium oxide film 20 formed on the silicon substrate 10.

[0030] In Experiment 1, a pulsed laser irradiation apparatus (excimer laser irradiation apparatus (demo machine) manufactured by JSW Actina System) with a XeCl light source (wavelength 308 nm) was used to irradiate the hafnium oxide film 20 formed on the silicon substrate 10 T with pulsed laser light 30 having a wavelength in the ultraviolet region X The pulsed laser light 30 X has a wavelength of 308 nm, a pulse interval of 10 ms (100 Hz), a pulse width (FWHM) of several tens of ns, and the number of irradiation times (shot number) of 200 times (200 shots). In Experiment 1, the pulsed laser light 30 X was irradiated 200 times (200 shots) with the energy density changed to 170 mJ / cm 2 , 220 mJ / cm 2 , 270 mJ / cm 2 , 400 mJ / cm 2 respectively.

[0031] Specifically, as shown in FIG. 4, a silicon substrate 10 (hafnium oxide film 20 T ) is irradiated with pulsed laser light 30 X in a nitrogen atmosphere. The width of the pulsed laser light 30 X (width in the transport direction) is about 400 μm (see FIG. 4). At that time, as the silicon substrate 10 (hafnium oxide film 20 T ) is transported, the irradiated regions of the pulsed laser light 30 X adjacent to each other overlap, and the transport speed of the silicon substrate 10 (hafnium oxide film 20 T ) is set to a speed of 0.2 mm / s. Hereinafter, a film is formed on the silicon substrate 10 by the thermal-ALD method, and the hafnium oxide film 20 X irradiated with the pulsed laser light 30 T is referred to as the hafnium oxide film 20 T+X . In FIG. 4, reference numeral A1 represents the region irradiated with the pulsed laser light, and A2 represents the region not irradiated with the pulsed laser light.

[0032] <Experimental Results of Experiment 1> Next, the experimental results (evaluation results) of Experiment 1 will be described.

[0033] <Evaluation by X-ray Diffractometer> FIG. 5(a) is a graph showing an X-ray diffraction pattern (experimental results of Experiment 1). In FIG. 5(a), reference numeral G XT(170) represents a graph for the case of an energy density of 170 mJ / cm 2 . Reference numeral G XT(220) represents a graph for the case of an energy density of 220 mJ / cm 2 . Reference numeral G XT(270) represents a graph for the case of an energy density of 270 mJ / cm 2 . Reference numeral G XT(400) represents a graph for the case of an energy density of 400 mJ / cm 2 .

[0034] The evaluation by the X-ray diffraction device was carried out using an X-ray diffraction device (manufactured by Rigaku Corporation) and pulsed laser light 30 X Irradiated hafnium oxide film 20 T+X The crystalline phase was evaluated. X-ray diffractometers are also called XRD (X-ray diffraction). X-ray diffractometers have a variety of measurement methods, and a 2θ scan, an asymmetric reflection measurement suitable for evaluating thin films, was performed. Because thin films are evaluated at a small angle of incidence, this method is also called thin film measurement or GI-XRD (Grazing Incidence XRD). The measurement conditions for the X-ray diffractometer are an incident angle ω = 0.4 deg.

[0035] As a premise, when crystallization of a hafnium oxide film in which the most stable m phase is suppressed progresses, that is, when an amorphous hafnium oxide film (exhibiting paraelectricity) formed on a silicon substrate 10 is modified into a hafnium oxide film (exhibiting ferroelectricity) mainly composed of o phase, the X-ray diffraction pattern of the modified hafnium oxide film measured by an X-ray diffractometer will have a peak near 2θ=30.35°.

[0036] Referring to Figure 5(a), in Experiment 1, graph G XT(170) , G XT(220) , G XT(270) , G XT(400) It can be seen that none of the samples has a peak near 2θ=30.35°.

[0037] That is, in Experiment 1, the hafnium oxide film 20 formed on the silicon substrate 10 T It can be seen that the hafnium oxide film cannot be crystallized (modified) into a hafnium oxide film in which the most stable m-phase is suppressed, that is, a hafnium oxide film mainly composed of the ferroelectric o-phase.

[0038] <Experiment 2> Experiment 2 was carried out under the conditions shown in Table 2 below.

[0039] [Table 2] Experiment 2 will be explained in detail below.

[0040] <Film Formation in Experiment 2 In Experiment 2, an amorphous hafnium oxide film 20 was formed on a silicon substrate 10 by the plasma-ALD method using a film formation apparatus (ALD apparatus (demo machine) manufactured by JSW Affti). Hereinafter, the amorphous hafnium oxide film 20 formed on the silicon substrate 10 by the plasma-ALD method is referred to as the hafnium oxide film 20 P as described.

[0041] Specifically, similar to Experiment 1 (see Fig. 3), by bringing one side of the silicon substrate 10 heated to 120 degrees by a heater into contact with the flowing source gas, oxidant, and inert gas, an extremely thin hafnium oxide film 20 with a thickness of 10 nm was formed on the silicon substrate 10 (one side) P Note that TEMAH (Tetrakis(EthylMethylAmido)Hafnium) was used as the source gas, O2 plasma was used as the oxidant, and N2 was used as the inert gas.

[0042] <Crystallization (Modification) in Experiment 2 In Experiment 2, similar to Experiment 1 (see Fig. 4), a XeCl light source (wavelength 308 nm) pulsed laser irradiation apparatus (excimer laser irradiation apparatus (demo machine) manufactured by JSW Actina System) was used, and the hafnium oxide film 20 formed on the silicon substrate 10 P was irradiated with pulsed laser light 30 having a wavelength in the ultraviolet region X The wavelength of the pulsed laser light 30 X is 308 nm, the pulse interval is 10 ms (100 Hz), the pulse width (FWHM) is several tens of ns, and the number of irradiation times is 200 times (200 shots). In Experiment 2, the energy density of the pulsed laser light 30 X was changed to 170 mJ / cm 2 , 220 mJ / cm 2 , 270 mJ / cm 2 , 400 mJ / cm 2 respectively, and irradiated 200 times (200 shots).

[0043] Specifically, similar to Experiment 1 (refer to Fig. 4), a silicon substrate 10 (hafnium oxide film 20 P ) is irradiated with pulsed laser light 30 X in a nitrogen atmosphere. The width of the pulsed laser light 30 X (width in the transport direction) is about 400 μm (refer to Fig. �). At that time, as the silicon substrate 10 (hafnium oxide film 20 P ) is transported, the transport speed of the silicon substrate 10 (hafnium oxide film 20 X ) is set to a speed of 0.2 mm / s so that the irradiated regions of the pulsed laser light 30 P adjacent to each other overlap. Hereinafter, the hafnium oxide film 20 X formed on the silicon substrate 10 and irradiated with the pulsed laser light 30 P is referred to as the hafnium oxide film 20 P+X .

[0044] <Experimental Results of Experiment 2> Next, the experimental results (evaluation results) of Experiment 2 will be described.

[0045] <Evaluation by X-ray Diffractometer> Fig. 5(b) is a graph showing the X-ray diffraction pattern (experimental results of Experiment 2). In Fig. 5(b), the symbol G XP(170) represents the graph for the case of an energy density of 170 mJ / cm 2 . The symbol G XP(220) represents the graph for the case of an energy density of 220 mJ / cm 2 . The symbol G XP(270) represents the graph for the case of an energy density of 270 mJ / cm 2 . The symbol G XP(400) represents the graph for the case of an energy density of 400 mJ / cm 2 .

[0046] The evaluation by the X-ray diffractometer is the same as in Experiment 1. Using an X-ray diffractometer (Rigaku X-ray diffractometer), the hafnium oxide film 20 X irradiated with the pulsed laser light 30 P+X(The crystalline phase) was evaluated. The measurement conditions of the X-ray diffractometer were an incident angle ω = 0.4 deg.

[0047] Referring to Fig. 5(b), in Experiment 2, in graph G XP(170) , G XP(220) , G XP(270) , G XP(400) it can be seen that none of them have a peak around 2θ = 30.35°.

[0048] That is, in Experiment 2, it can be seen that the hafnium oxide film 20 P formed on the silicon substrate 10 cannot be crystallized (modified) into a hafnium oxide film in which the most stable m phase is suppressed, that is, a hafnium oxide film mainly composed of the ferroelectric o phase.

[0049] <Consideration of Experiments 1 and 2> As described above, in neither Experiment 1 nor Experiment 2 did a peak appear around 2θ = 30.35° (see Fig. 5(a) and Fig. 5(b)). This is considered to be because there is insufficient lattice vibration to promote the crystallization of the amorphous hafnium oxide film. Therefore, in order to compensate for the lack of lattice vibration, Experiments 3 to 6 were carried out using a pulsed laser irradiation device with a KrF light source, which has a higher photon kinetic energy than the XeCl light source.

[0050] <Experiment 3> Experiment 3 was carried out under the conditions described in Table 3 below.

[0051]

Table 3

[0052] <Film formation in Experiment 3> In Experiment 3, similar to Experiment 1, a film formation apparatus (ALD apparatus (demo machine) manufactured by JSW Affti Co., Ltd.) was used, and an amorphous hafnium oxide film 20 T was formed on the silicon substrate 10 by the thermal-ALD method.

[0053] Specifically, similar to Experiment 1 (refer to Figure 3), by bringing one side of the silicon substrate 10 heated to 120 degrees by a heater into contact with the flowing source gas, oxidant, and inert gas, an ultrathin hafnium oxide film 20 with a film thickness of 10 nm is formed on the silicon substrate 10. T TEMAH (Tetrakis(EthylMethylAmido)Hafnium) was used as the source gas, O3 was used as the oxidant, and N2 was used as the inert gas.

[0054] <Crystallization (modification) of Experiment 3> Figure 6 is a schematic diagram showing the state of crystallizing (modifying) the hafnium oxide film 20 formed on the silicon substrate 10. T

[0055] In Experiment 3, a pulsed laser irradiation device of a KrF light source (wavelength 248 nm) (an excimer laser irradiation device (demo machine) manufactured by JSW Actina System Co., Ltd.) was used, and the hafnium oxide film 20 formed on the silicon substrate 10 T was irradiated with pulsed laser light 30 having a wavelength in the ultraviolet region. K The pulsed laser light 30 K has a wavelength of 248 nm, a pulse interval of 10 ms (100 Hz), a pulse width (FWHM) of several tens of ns, and the number of irradiation times is 1 time (1 shot). In Experiment 3, the energy density of the pulsed laser light 30 K was changed to 300 mJ / cm 2 , 350 mJ / cm 2 , 400 mJ / cm 2 , 450 mJ / cm 2 respectively, and each was irradiated 1 time (1 shot).

[0056] Specifically, using a pulsed laser irradiation device (an excimer laser irradiation device (demo machine) manufactured by JSW Actina System Co., Ltd.), as shown in Figure 6, the silicon substrate 10 (hafnium oxide film 20 T ) arranged in the chamber 41 moved in the X (+X, -X) direction and the Y (+Y, -Y) direction (directions perpendicular to the plane of the paper in Figure 6) by the transfer mechanism 40 was irradiated with pulsed laser light 30 through anhydrous quartz 42 in a nitrogen atmosphere supplied into the chamber 41.K It was irradiated. As shown in FIG. 6, the chamber 41 is composed by combining a plurality of chamber components 41a, 41b, 41c, etc., and is sealed by sealing materials 43, 44, and a buffer material 45. The buffer material 45 is a Teflon (registered trademark) buffer material provided to prevent the direct interference between the anhydrous quartz 42 and the chamber component 41a (made of stainless steel). In FIG. 5, reference numeral 47 represents a valve provided in the nitrogen supply pipe 46, and reference numeral 49 represents a valve provided in the nitrogen discharge pipe 48. Nitrogen is supplied into the chamber 41 through the nitrogen supply pipe 46 and discharged to the outside of the chamber 41 through the nitrogen discharge pipe 48.

[0057] The pulsed laser light 30 K has a size (cross-sectional size) of 3 mm × 3 mm. And each time the pulsed laser light 30 K is irradiated once (1 shot), the chamber 41 is moved so that the irradiated regions of the pulsed laser lights 30 adjacent to each other do not overlap. Hereinafter, a hafnium oxide film 20 K formed on the silicon substrate 10 by the thermal-ALD method and irradiated with the pulsed laser light 30 T is referred to as the hafnium oxide film 20 T+K .

[0058] <Experimental Results of Experiment 3> Next, the experimental results (evaluation results) of Experiment 3 will be described.

[0059] <Evaluation by X-ray Diffractometer> FIG. 7(a) is a graph showing an X-ray diffraction pattern (experimental results of Experiment 3). In FIG. 7(a), reference numeral G KT(300) represents a graph in the case of an energy density of 300 mJ / cm 2 . Reference numeral G KT(350) represents a graph in the case of an energy density of 350 mJ / cm 2 . Reference numeral G KT(400) represents a graph in the case of an energy density of 400 mJ / cm 2 . Reference numeral G KT(450) represents a graph in the case of an energy density of 450 mJ / cm 2represents the graph in the case of.

[0060] The evaluation by the X-ray diffractometer was carried out in the same manner as in Experiment 1. Using an X-ray diffractometer (Rigaku X-ray diffractometer), the hafnium oxide film 20 K irradiated with the pulsed laser light 30 T+K (crystalline phase) was evaluated. The measurement conditions of the X-ray diffractometer were an incident angle ω = 0.4 deg.

[0061] Referring to Fig. 7(a), in Experiment 3, it can be seen that in the graphs G KT(400) , G KT(450) have a peak near 2θ = 30.35°.

[0062] That is, based on the evaluation by the X-ray diffractometer, in the case of the amorphous hafnium oxide film 20 T formed by the thermal-ALD method, by selecting the wavelength of the pulsed laser light 30 K to be 248 nm and the energy density to be 400 mJ / cm 2 or more, it can be seen that the hafnium oxide film 20 T can be crystallized (modified) into a hafnium oxide film in which the most stable m phase is suppressed, that is, a hafnium oxide film mainly composed of the ferroelectric o phase.

[0063] <Evaluation by SEM> The upper part in Fig. 8 is an SEM image of the hafnium oxide film 20 T+K taken by SEM. SEM is an abbreviation for Scanning Electron Microscope and is also called a scanning electron microscope.

[0064] Using an SEM (scanning electron microscope manufactured by Hitachi High-Tech Corporation), the hafnium oxide film 20 T+K (surface shape) was evaluated. The relatively bright parts in each SEM image represent the agglomerated parts (agglomerated parts of hafnium oxide), and the relatively dark parts represent the parts where the hafnium oxide film is thin. From the elemental identification of the bright parts, it was found that agglomeration had progressed. Note that the brightness cannot be unified for each imaging, and it is an evaluation of the contrast within the SEM image.

[0065] Therefore, when the SEM image includes relatively bright portions and relatively dark portions, it can be evaluated that the hafnium oxide film 20 T+K is aggregated. On the other hand, when the SEM image does not include relatively bright portions and relatively dark portions (for example, when it includes only one of the portions), it can be evaluated that the hafnium oxide film 20 T+K is not aggregated.

[0066] Referring to the upper part of FIG. 8, in the case of an energy density of 450 mJ / cm 2 the SEM image of the energy density of 450 mJ / cm 2 includes relatively bright portions and relatively dark portions (both portions are mixed). Therefore, in the case of an energy density of 450 mJ / cm 2 it can be evaluated that the hafnium oxide film 20 T+K is aggregated. The hafnium oxide film 20 aggregated in this way T+K is not suitable as a ferroelectric material of the non-volatile memory device because the shape of the hafnium oxide film (mainly, the surface shape of the hafnium oxide film 20 T at the time of completion of film formation) is not maintained.

[0067] On the other hand, in the case of an energy density of 400 mJ / cm 2 the SEM image of the energy density of 400 mJ / cm 2 does not include relatively bright portions and relatively dark portions. Therefore, in the case of an energy density of 400 mJ / cm 2 it can be evaluated that the hafnium oxide film 20 T+K is not aggregated. The hafnium oxide film 20 not aggregated in this way T+K is suitable as a ferroelectric material of the non-volatile memory device because the shape of the hafnium oxide film (mainly, the surface shape of the hafnium oxide film 20 T at the time of completion of film formation) is maintained.

[0068] As described above, according to Experiment 3, in the case of the amorphous hafnium oxide film 20 formed by the thermal-ALD method T the pulsed laser light 30K With a wavelength of 248 nm and an energy density of 400 mJ / cm 2 By selecting these conditions, the hafnium oxide film 20 formed on the silicon substrate 10 T can be crystallized (modified) into a hafnium oxide film in which the most stable m-phase is suppressed, that is, a hafnium oxide film mainly composed of the ferroelectric o-phase, and moreover, it can be seen that aggregation of the hafnium oxide film does not occur.

[0069] <Experiment 4> Experiment 4 was carried out under the conditions described in Table 4 below.

[0070]

Table 4

[0071] <Film formation in Experiment 4> In Experiment 4, similar to Experiment 2, an amorphous hafnium oxide film 20 was formed on the silicon substrate 10 by the plasma-ALD method using a film formation apparatus (ALD apparatus (demo machine) manufactured by JSW Affinity Co., Ltd.). P was formed.

[0072] Specifically, similar to Experiment 1 (see Figure 3), by bringing one side of the silicon substrate 10 heated to 120 degrees by a heater into contact with the flowing source gas, oxidant, and inert gas, an extremely thin hafnium oxide film 20 with a film thickness of 10 nm was formed on the silicon substrate 10 (one side). P was formed. TEMAH (Tetrakis(EthylMethylAmido)Hafnium) was used as the source gas, O2 plasma was used as the oxidant, and N2 was used as the inert gas.

[0073] <Crystallization (modification) in Experiment 4> In Experiment 4, similar to Experiment 3, a pulsed laser irradiation apparatus (excimer laser irradiation apparatus (demo machine) manufactured by JSW Actina System Co., Ltd.) with a KrF light source (wavelength 248 nm) was used, and the hafnium oxide film 20 formed on the silicon substrate 10 P was irradiated with pulsed laser light 30 having a wavelength in the ultraviolet region.K was irradiated. The pulsed laser light 30 K had a wavelength of 248 nm, a pulse interval of 10 ms (100 Hz), a pulse width (FWHM) of several tens of ns, and the number of irradiation times was 1 time (1 shot). In Experiment 4, the pulsed laser light 30 K had an energy density of 300 mJ / cm 2 , 350 mJ / cm 2 , 400 mJ / cm 2 , 450 mJ / cm 2 was changed, and each was irradiated 1 time (1 shot).

[0074] Specifically, using a pulsed laser irradiation device (an excimer laser irradiation device (demo machine) manufactured by JSW Actina System Co., Ltd.), similar to Experiment 3 (see Fig. 6), the pulsed laser light 30 was irradiated onto the silicon substrate 10 (amorphous hafnium oxide film 20) placed in the chamber 41 that was moved in the X (+X, -X) direction and Y (+Y, -Y) direction (directions perpendicular to the plane of the paper in Fig. 6) by the transport mechanism 40 through anhydrous quartz 42 under a nitrogen atmosphere supplied into the chamber 41. K was irradiated.

[0075] The pulsed laser light 30 K had a size (cross-sectional size) of 3 mm × 3 mm. And each time the pulsed laser light 30 K was irradiated 1 time (1 shot), the chamber 41 was moved so that the irradiated regions of the pulsed laser light 30 adjacent to each other did not overlap. Hereinafter, a film was formed on the silicon substrate 10 by the plasma-ALD method, and the hafnium oxide film 20 K irradiated with the pulsed laser light 30 P is referred to as the hafnium oxide film 20 P+K .

[0076] <Experimental Results of Experiment 4> Next, the experimental results (evaluation results) of Experiment 4 will be described.

[0077] <Evaluation by X-ray Diffractometer> Fig. 7(b) is a graph showing the X-ray diffraction pattern (experimental results of Experiment 4). In Fig. 7(b), the symbol GKP(300) represents the graph in the case of an energy density of 300 mJ / cm 2 . The symbol G KP(350) represents the graph in the case of an energy density of 350 mJ / cm 2 . The symbol G KP(400) represents the graph in the case of an energy density of 400 mJ / cm 2 . The symbol G KP(450) represents the graph in the case of an energy density of 450 mJ / cm 2 .

[0078] For the evaluation by the X-ray diffractometer, similar to Experiment 1, an X-ray diffractometer (Rigaku X-ray diffractometer) was used, and the hafnium oxide film 20 K irradiated with the pulsed laser light 30 P+K (crystalline phase) was evaluated. The measurement conditions of the X-ray diffractometer were an incident angle ω = 0.4 deg.

[0079] Referring to Fig. 7(b), in Experiment 4, it can be seen that in the graphs G KP(350) , G KP(400) , G KP(450) , there are peaks around 2θ = 30.35°.

[0080] That is, based on the evaluation by the X-ray diffractometer, in the case of the amorphous hafnium oxide film 20 P formed by the plasma-ALD method, by selecting a wavelength of 248 nm and an energy density of 350 mJ / cm K or higher for the pulsed laser light 30 2 , it can be seen that the hafnium oxide film 20 P can be crystallized (modified) into a hafnium oxide film in which the most stable m phase is suppressed, that is, a hafnium oxide film mainly composed of the ferroelectric o phase.

[0081] <Evaluation by SEM> The lower middle part of Fig. 8 is the SEM image of the hafnium oxide film 20 P+K captured by SEM.

[0082] Similar to Experiment 3, a scanning electron microscope (SEM, manufactured by Hitachi High-Technologies Corporation) was used to evaluate the hafnium oxide film 20 P+K (surface shape).

[0083] Referring to the middle and lower parts of Fig. 8, for energy densities of 300 mJ / cm 2 , 350 mJ / cm 2 , 400 mJ / cm 2 , 450 mJ / cm 2 , each SEM image contains relatively bright areas and relatively dark areas (both areas are mixed). Therefore, for energy densities of 300 mJ / cm 2 , 350 mJ / cm 2 , 400 mJ / cm 2 , 450 mJ / cm 2 , it can be evaluated that the hafnium oxide film 20 P+K is aggregated. The aggregated hafnium oxide film 20 P+K does not maintain the shape of the hafnium oxide film (mainly the surface shape of the hafnium oxide film 20 P at the time of film formation completion), so it is not suitable as a ferroelectric material for a non-volatile memory device.

[0084] As described above, according to Experiment 4, in the case of the amorphous hafnium oxide film 20 P formed by the plasma-ALD method, by selecting the wavelength of the pulsed laser light 30 K to be 248 nm and the energy density to be 400 mJ / cm 2 , the hafnium oxide film 20 P formed on the silicon substrate 10 can be crystallized (modified) into a hafnium oxide film in which the m-phase of the most stable phase is suppressed, that is, a hafnium oxide film mainly composed of the ferroelectric o-phase, but it can be seen that aggregation of the hafnium oxide film occurs.

[0085] <Considerations of Experiments 3 and 4> Both Experiments 3 and 4 used a pulsed laser irradiation device with a KrF light source, fixed the number of irradiations at 1 time (1 shot), and changed the energy density of the pulsed laser light 30 KThis is an example of irradiation, with a peak near 2θ = 30.35° (see Figures 7(a) and 7(b)).

[0086] In thermal-ALD (Experiment 3), the m-phase is completely suppressed, while in plasma-ALD (Experiment 4), the m-phase has slightly progressed in crystallization (see Figures 7(a) and 7(b)). This difference in the film deposition method is expected to be due to the difference in film density. The density tends to be higher in plasma-ALD than in thermal-ALD. A higher density means that lattice vibrations are more likely to propagate.

[0087] In thermal-ALD, it is speculated that the structure did not displace to the m-phase with low symmetry because the density is relatively low and lattice vibrations are less likely to propagate. Conversely, in plasma-ALD, it is speculated that the structure displaced to the m-phase with low symmetry because the density is relatively high and lattice vibrations are more likely to propagate.

[0088] Also, in thermal-ALD (Experiment 3), an energy density of 400 mJ / cm 2 or higher was required for crystallization, while in plasma-ALD (Experiment 4), an energy density of 350 mJ / cm 2 or higher was required for crystallization. This is also considered to be affected by the density difference.

[0089] In thermal-ALD (Experiment 3), crystallization progressed at 400 mJ / cm 2 or higher, and the m-phase was suppressed. However, as a result of SEM evaluation, aggregation had started at 450 mJ / cm 2 On the other hand, in plasma-ALD (Experiment 4), crystallization started to progress at 350 mJ / cm 2 or higher, but aggregation had already occurred at 300 mJ / cm 2

[0090] ​Considering the above, a process that can suppress the m-phase crystallization without causing aggregation, that is, while maintaining the shape of the hafnium oxide film (mainly the surface shape of the hafnium oxide film at the end of film formation), is a film formation method by thermal-ALD, and a pulsed laser with a wavelength of 248 nm (KrF light source) in the ultraviolet region needs to be irradiated at 400 mJ / cm 2 It can be seen that irradiation is required.

[0091] <Experiment 5> Experiment 5 was carried out under the conditions described in Table 5 below.

[0092]

Table 5

[0093] <Film formation in Experiment 5> In Experiment 5, similar to Experiment 1, an amorphous hafnium oxide film 20 was formed on the silicon substrate 10 by using a film formation apparatus (ALD apparatus (demo machine) manufactured by JSW Affti Co., Ltd.) and the thermal-ALD method. T was formed.

[0094] Specifically, similar to Experiment 1 (see Figure 3), by bringing one side of the silicon substrate 10 heated to 120 degrees by a heater into contact with the flowing source gas, oxidant, and inert gas, an extremely thin hafnium oxide film 20 with a thickness of 10 nm was formed on the silicon substrate 10. T was formed. Note that TEMAH (Tetrakis(EthylMethylAmido)Hafnium) was used as the source gas, O3 was used as the oxidant, and N2 was used as the inert gas.

[0095] <Crystallization (modification) in Experiment 5> In Experiment 5, similar to Experiment 3, a pulsed laser irradiation apparatus (excimer laser irradiation apparatus (demo machine) manufactured by JSW Actina System Co., Ltd.) with a KrF light source (wavelength 248 nm) was used to irradiate the hafnium oxide film 20 formed on the silicon substrate 10. T with pulsed laser light having a wavelength in the ultraviolet region. Pulsed laser light 30 KThe wavelength is 248 nm, the pulse interval is 10 ms (100 Hz), the pulse width (FWHM) is several tens of ns, and the energy density is 400 mJ / cm 2 is. In Experiment 5, the number of irradiations of the pulsed laser light 30 K was changed to 0 times (as-deposition), 1 time (1 shot), 2 times (2 shots), 20 times (20 shots), and 200 times (200 shots), and each number of irradiations was performed.

[0096] Specifically, using a pulsed laser irradiation device (an excimer laser irradiation device (demo machine) manufactured by JSW Actina System Co., Ltd.), similar to Experiment 3 (see Fig. 6), the silicon substrate 10 (hafnium oxide film 20 T ) placed in the chamber 41 moved in the X (+X, -X) direction and the Y (+Y, -Y) direction (directions perpendicular to the plane of the paper in Fig. 6) by the transport mechanism 40 was irradiated with the pulsed laser light 30 K through anhydrous quartz 42 under a nitrogen atmosphere supplied into the chamber 41.

[0097] The pulsed laser light 30 K has a size (cross-sectional size) of 3 mm × 3 mm. And each time the pulsed laser light 30 K was irradiated a predetermined number of times, the chamber 41 was moved so that the irradiated regions of the pulsed laser lights 30 K adjacent to each other did not overlap. Hereinafter, a film was formed on the silicon substrate 10 by the thermal-ALD method, and the hafnium oxide film 20 K irradiated with the pulsed laser light 30 T is referred to as the hafnium oxide film 20 T+K .

[0098] <Experimental Results of Experiment 5> Next, the experimental results (evaluation results) of Experiment 5 will be described.

[0099] <Evaluation by X-ray Diffractometer> Fig. 9(a) is a graph showing the X-ray diffraction pattern (experimental results of Experiment 5). In Fig. 9(a), the symbol G KT(0shot)represents a graph when the number of irradiations (shot number) is 0. Symbol G KT(1shot) represents a graph when the number of irradiations (shot number) is 1. Symbol G KT(2shot) represents a graph when the number of irradiations (shot number) is 2. Symbol G KT(20shot) represents a graph when the number of irradiations (shot number) is 20. Symbol G KT(200shot) represents a graph when the number of irradiations (shot number) is 200.

[0100] The evaluation by the X-ray diffractometer was carried out in the same manner as in Experiment 1. Using an X-ray diffractometer (Rigaku X-ray diffractometer), 30 pulsed laser lights were irradiated as described above K onto the hafnium oxide film 20 T+K (crystalline phase) for evaluation. The measurement conditions of the X-ray diffractometer were an incident angle ω = 0.4 deg.

[0101] Referring to Fig. 9(a), in Experiment 5, it can be seen that in graphs G KT(1shot) , G KT(2shot) , graph G KT(20shot) , G KT(200shot) there is a peak around 2θ = 30.35°.

[0102] That is, based on the evaluation by the X-ray diffractometer, in the case of the amorphous hafnium oxide film 20 T formed by the thermal-ALD method, by selecting a wavelength of 248 nm, an energy density of 400 mJ / cm K , and an irradiation number of 1 or more for the pulsed laser light 30 2 , it can be seen that the hafnium oxide film 20 T can be crystallized (modified) into a hafnium oxide film in which the most stable m phase is suppressed, that is, a hafnium oxide film mainly composed of the ferroelectric o phase.

[0103] <Evaluation by SEM> The upper part in Fig. 10 is the SEM image of the hafnium oxide film 20 T+K captured by SEM.

[0104] Similar to Experiment 3, the hafnium oxide film 20 was evaluated using an SEM (scanning electron microscope manufactured by Hitachi High-Tech Corporation). T+K (Surface shape)

[0105] Referring to the upper part of Fig. 10, in the case of an energy density of 400 mJ / cm 2 , the SEM images for 1 shot, 2 shot, 20 shot, and 200 shot each do not include relatively bright areas and relatively dark areas. Therefore, in the case of an energy density of 400 mJ / cm 2 , even when irradiated up to 200 times, it can be evaluated that the hafnium oxide film 20 T+K has not aggregated. Such a non-aggregating hafnium oxide film 20 T+K is suitable as a ferroelectric material for a non-volatile memory device because the shape of the hafnium oxide film (mainly the surface shape of the hafnium oxide film 20 T at the time of film formation completion) is maintained.

[0106] <Experiment 6> Experiment 6 was carried out under the conditions described in Table 6 below.

[0107]

Table 6

[0108] <Film formation in Experiment 6> In Experiment 6, similar to Experiment 2, an amorphous hafnium oxide film 20 was formed on the silicon substrate 10 by the plasma-ALD method using a film formation apparatus (ALD apparatus (demo machine) manufactured by JSW Affti Co., Ltd.). P was formed.

[0109] Specifically, similar to Experiment 1 (see Fig. 3), by bringing one side of the silicon substrate 10 heated to 120 degrees by a heater into contact with the flowing source gas, oxidant, and inert gas, an extremely thin hafnium oxide film 20 with a film thickness of 10 nm was formed on the silicon substrate 10 PA film was formed. TEMAH (Tetrakis(EthylMethylAmido)Hafnium) was used as the source gas, O2 plasma was used as the oxidizing agent, and N2 was used as the inert gas.

[0110] <Crystallization (Modification) of Experiment 6> In Experiment 6, similar to Experiment 5, a pulsed laser irradiation apparatus (excimer laser irradiation apparatus (demo machine) manufactured by JSW Actina System Co., Ltd.) of a KrF light source (wavelength 248 nm) was used, and the hafnium oxide film 20 formed on the silicon substrate 10 P was irradiated with pulsed laser light having a wavelength in the ultraviolet region. The wavelength of the pulsed laser light was 248 nm, the pulse interval was 10 ms (100 Hz), the pulse width (FWHM) was several tens of ns, and the energy density was 400 mJ / cm 2 is. In Experiment 6, the number of irradiations of the pulsed laser light 30 K was changed to 0 times (as-deposition), 1 time (1 shot), 2 times (2 shots), 20 times (20 shots), and 200 times (200 shots), and each number of irradiations was irradiated.

[0111] Specifically, using a pulsed laser irradiation apparatus (excimer laser irradiation apparatus (demo machine) manufactured by JSW Actina System Co., Ltd.), similar to Experiment 5 (see Fig. 6), the silicon substrate 10 (hafnium oxide film 20 P ) placed in the chamber 41 moved in the X (+X, -X) direction and the Y (+Y, -Y) direction (directions perpendicular to the plane of the paper in Fig. 6) by the transport mechanism 40 was irradiated with the pulsed laser light 30 K through anhydrous quartz 42 in a nitrogen atmosphere supplied into the chamber 41.

[0112] The pulsed laser light 30 K has a size (cross-sectional size) of 3 mm × 3 mm. And every time the pulsed laser light 30 K was irradiated a predetermined number of times, the chamber 41 was moved so that the irradiated regions of the pulsed laser lights 30 K adjacent to each other did not overlap. Hereinafter, it was formed on the silicon substrate 10 by the plasma-ALD method, and the pulsed laser light 30 K KThe hafnium oxide film 20 irradiated P is described as the hafnium oxide film 20 P+K .

[0113] <Experimental results of Experiment 6> Next, the experimental results (evaluation results) of Experiment 6 will be described.

[0114] <Evaluation by X-ray diffractometer> Figure 9(b) is a graph showing the X-ray diffraction pattern (experimental results of Experiment 6). In Figure 9(b), the symbol G KP(0shot) represents the graph when the number of irradiations (shot number) is 0. The symbol G KP(1shot) represents the graph when the number of irradiations (shot number) is 1. The symbol G KP(2shot) represents the graph when the number of irradiations (shot number) is 2. The symbol G KP(20shot) represents the graph when the number of irradiations (shot number) is 20. The symbol G KP(200shot) represents the graph when the number of irradiations (shot number) is 200.

[0115] The evaluation by the X-ray diffractometer is the same as in Experiment 3. Using an X-ray diffractometer (Rigaku X-ray diffractometer), the hafnium oxide film 20 K irradiated with the pulsed laser light 30 P+K (crystalline phase) was evaluated. The measurement conditions of the X-ray diffractometer are an incident angle ω = 0.4 deg.

[0116] Referring to Figure 9(b), in Experiment 6, it can be seen that in the graphs G KP(1shot) , G KP(2shot) , there are peaks near 2θ = 30.35°. KP(20shot)

[0117] That is, based on the evaluation by the X-ray diffractometer, in the case of the amorphous hafnium oxide film 20 formed by the plasma-ALD method P , for the pulsed laser light 30 K with a wavelength of 248 nm and an energy density of 400 mJ / cm 2By selecting the number of irradiations from 1 to 20, the amorphous hafnium oxide film 20 formed on the silicon substrate 10 can be crystallized (modified) into a hafnium oxide film 20 in which the most stable m phase is suppressed. P That is, it can be seen that it can be crystallized (modified) into a hafnium oxide film mainly composed of the ferroelectric o phase.

[0118] <Evaluation by SEM> The lower-middle part of Fig. 10 is a SEM image of the hafnium oxide film 20 P+K captured by SEM.

[0119] Similar to Experiment 3, using a SEM (scanning electron microscope manufactured by Hitachi High-Tech Corporation), the hafnium oxide film 20 irradiated with the above-mentioned pulsed laser light, which is the experimental result of Experiment 5 P+K (surface shape) was evaluated.

[0120] Referring to the lower-middle part of Fig. 10, when the energy density is 400 mJ / cm 2 , in the case of 1 shot, 2 shots, 20 shots, and 200 shots respectively, each SEM image includes relatively bright areas and relatively dark areas. Therefore, when the energy density is 400 mJ / cm 2 , from 1 shot of the number of irradiations, it can already be evaluated that the hafnium oxide film 20 P+K is aggregated. The hafnium oxide film 20 aggregated in this way P+K does not maintain the shape of the hafnium oxide film (mainly the surface shape of the hafnium oxide film 20 P at the time of film formation completion), so it is not suitable as a ferroelectric material for a non-volatile memory device.

[0121] <Consideration of Experiments 5 and 6> Both Experiments 5 and 6 used a pulsed laser irradiation device with a KrF light source, fixed the energy density at 400 mJ / cm 2 , and are examples of irradiating pulsed laser light 30 K while changing the number of irradiations (number of shots), and have a peak near 2θ = 30.35° (see Fig. 9(a) and Fig. 9(b)).

[0122] In the case of as-deposition, no crystallization occurred (amorphous) in either thermal-ALD (Experiment 5) or plasma-ALD (Experiment 6).

[0123] In the case of 1-shot, crystallization progressed in both thermal-ALD (Experiment 5) and plasma-ALD (Experiment 6), and the o-phase became the main phase (mainly o-phase). In the case of 1-shot, a slight m-phase peak was observed in plasma-ALD (Experiment 6).

[0124] In thermal-ALD (Experiment 5), the o phase was maintained even when the number of shots was increased to more than two.

[0125] On the other hand, in plasma-ALD (Experiment 6), when the number of irradiations was increased to two or more shots, the peak of the o-phase decreased with increasing number of irradiations, and instead the m-phase became the main phase (mainly the m-phase). This dependence on the number of irradiations in plasma-ALD indicates that the process is different when photons are injected into an amorphous hafnium oxide film and when photons are injected into a hafnium oxide film with a single shot of o-phase as the main phase. Generating lattice vibrations in an amorphous hafnium oxide film did not result in a structural shift to the m-phase, and the film remained as the main phase. However, generating lattice vibrations in an o-phase hafnium oxide film results in a structural shift to the m-phase, which is presumably why the o-phase is replaced by the m-phase. It is not believed that the o-phase disappears and the m-phase appears.

[0126] The reason why the crystallization of the m-phase did not progress in thermal-ALD (Experiment 5) is thought to be that the lower density compared to plasma-ALD (Experiment 6) makes it difficult for lattice vibrations to progress.

[0127] Regarding the confirmation of the number of irradiations and the surface shape, in plasma-ALD, aggregation (aggregation of hafnium oxide) had already occurred with 1 shot, so even when the number of irradiations was increased, it remained aggregated. On the other hand, in thermal-ALD, aggregation did not progress even when the number of irradiations was increased.

[0128] <Reforming conditions> Considering the above Experiments 1 to 6, the conditions for reforming the amorphous hafnium oxide film (showing normal dielectric properties) formed on the silicon substrate 10 into a hafnium oxide film mainly composed of the o-phase (showing ferroelectric properties) are as follows.

[0129] (Condition 1) Form an amorphous hafnium oxide film 20 on the silicon substrate by the Thermal ALD method. T Note that the film thickness of the hafnium oxide film 20 T may be an appropriate film thickness according to the required degree of densification.

[0130] (Condition 2) Irradiate the hafnium oxide film 20 formed according to the above Condition 1 with pulsed laser light having a wavelength in the ultraviolet region. At this time, select the energy density, wavelength, pulse interval, and pulse width of the pulsed laser light so that the amorphous hafnium oxide film 20 T is reformed into a hafnium oxide film 20 mainly composed of the o-phase and no aggregation of the hafnium oxide film 20 T occurs. As the energy density, wavelength, pulse interval, and pulse width of this pulsed laser light, the energy density is 400 mJ / cm T+K can be exemplified by a wavelength of 248 nm (for example, a KrF light source), a pulse interval of 10 ms, and a pulse width of several tens of ns, but it may be otherwise. Note that if CW laser light is used instead of pulsed laser light, it is considered that the o-phase will not be the main phase, so it is essential to use pulsed laser light. T+K 2 2 As guidelines for selecting the energy density, wavelength, pulse interval, and pulse width of the pulsed laser light, for the hafnium oxide film 20

[0131] T+K T+KThe X-ray diffraction pattern obtained by the X-ray diffractometer has a peak near 2θ = 30.35°, and the hafnium oxide film 20 T+K The SEM image obtained by the scanning electron microscope of T+K does not include relatively bright areas and relatively dark areas evaluated as aggregation of the hafnium oxide film 20 T+K It is desirable to select the energy density, wavelength, pulse interval, and pulse width of the pulsed laser light 30 so that the hafnium oxide film 20 K does not include relatively bright areas and relatively dark areas evaluated as aggregation of T+K .

[0132] <Effect compared with comparative example> Next, the effects of the embodiment will be described in comparison with the comparative example.

[0133] FIG. 11(a) shows a comparative example, and FIG. 11(b) shows an embodiment.

[0134] In Comparative Example 1, the entire silicon substrate on which the hafnium oxide film is formed is continuously annealed. When the entire silicon substrate on which the hafnium oxide film is formed is continuously annealed, as shown in FIG. 11(a), the hafnium oxide film changes to a large number of crystal phases including the m-phase and the o-phase. "o, m, etc." in FIG. 11(a) represents this. The hafnium oxide film in which such a large number of crystal phases are mixed is unsuitable as a ferroelectric material for a non-volatile memory device.

[0135] On the other hand, according to the hafnium oxide film modification method of the embodiment (see the above conditions 1, 2, etc.), the amorphous hafnium oxide film 20 formed on the silicon substrate 10 T is crystallized (modified) into a hafnium oxide film 20 in which the most stable m-phase is suppressed T+K , that is, a hafnium oxide film 20 mainly composed of the ferroelectric o-phase T+K (moreover, aggregation of the hafnium oxide film 20 T+K does not occur). This hafnium oxide film 20 T+K is suitable as a ferroelectric material for a non-volatile memory device.

[0136] <Non-volatile memory device> Next, an example of a non-volatile memory device to which the hafnium oxide film 20 modified by the hafnium oxide film modification method of the above embodiment is applied will be described. T+K

[0137] FIG. 12 is a schematic configuration diagram of a non-volatile memory device M to which the hafnium oxide film 20 modified by the hafnium oxide film modification method of the embodiment is applied. T+K

[0138] As shown in FIG. 12, the non-volatile memory device M includes a silicon substrate 10 and at least one ferroelectric gate transistor 50 formed on the silicon substrate.

[0139] The ferroelectric gate transistor 50 includes a source region 51 formed on one surface side of the silicon substrate 10 and exposed from the one surface, a drain region 52 formed on one surface side of the silicon substrate 10 and away from the source region 51 and exposed from the one surface, and an o-phase-based hafnium oxide film 53 (hafnium oxide film 20 T+K ) formed to cover the source region 51 and the drain region 52 on one surface side of the silicon substrate 10, a gate electrode 54 formed on the hafnium oxide film 53, a source electrode 55 electrically connected to the source region 51 through a first contact hole H1 formed in the hafnium oxide film 53 corresponding to the source region 51, and a drain electrode 56 inserted into a second contact hole H2 formed in the hafnium oxide film 53 corresponding to the drain region 52 and electrically connected to the drain region 52.

[0140] Next, an example of a manufacturing process of the non-volatile memory device M having the above configuration will be described.

[0141] FIG. 13 is an example of a flowchart of a manufacturing process of the non-volatile memory device M.

[0142] First, a silicon substrate 10 is prepared (step S10) and cleaned (step S11). The silicon substrate 10 may be, for example, a p-type silicon substrate with a plane index of (100).

[0143] Next, a source region 51 and a drain region 52 are formed on the silicon substrate 10 (step S12). The source region 51 and the drain region 52 are formed, for example, by n-doping so as to be exposed from one surface side of the silicon substrate 10 on one surface side. Note that annealing treatment may be performed at this stage, but the annealing treatment may be omitted.

[0144] Next, using a film forming apparatus, an amorphous hafnium oxide film 20 is formed on the silicon substrate 10 by the thermal-ALD method T (step S13). Specifically, the amorphous hafnium oxide film 20 is formed in a state of covering the source region 51 and the drain region 52 on one surface side of the silicon substrate 10. T The amorphous hafnium oxide film 20 T has a film thickness of, for example, 10 nm.

[0145] Next, using a pulsed laser irradiation apparatus of an ultraviolet light source (for example, a KrF light source), the amorphous hafnium oxide film 20 T is crystallized (step S14). As a result, the amorphous hafnium oxide film 20 T is modified into a hafnium oxide film 53 mainly composed of the o-phase (hafnium oxide film 20 T+K ).

[0146] Next, contact holes H1 and H2 are formed in the hafnium oxide film 53 mainly composed of the o-phase (step S15).

[0147] Thereafter, an electrode material is laminated on the hafnium oxide film 53 mainly composed of the o-phase (step S16), and a source electrode, a drain electrode, and a gate electrode are formed (step S17).

[0148] As described above, a nonvolatile memory device applying the hafnium oxide film 20 modified by the hafnium oxide film modification method of the above embodiment can be manufactured. Note that the hafnium oxide film modification method of the above embodiment is not limited to the nonvolatile memory device M, and may be applied to other nonvolatile memory devices including a hafnium oxide film. T+K ​

[0149] As described above, according to the present embodiment, it is possible to crystallize (modify) the ferroelectric o-phase-based hafnium oxide (film).

[0150] As described above, the invention made by the present inventor has been specifically described based on the embodiments. However, it goes without saying that the present invention is not limited to the embodiments already described, and various modifications can be made without departing from the gist thereof.

Explanation of Reference Numerals

[0151] 10... Silicon substrate 20... Hafnium oxide film 30... Pulsed laser light 40... Conveying mechanism 41... Chamber 42... Anhydrous quartz 50... Ferroelectric gate transistor 51... Source region 52... Drain region 53... Hafnium oxide film 54... Gate electrode 55... Source electrode 56... Drain electrode A1... Pulsed laser light irradiated region A2... Pulsed laser light non-irradiated region H1... First contact hole H2... Second contact hole M... Non-volatile memory device

Claims

1. A film forming step of forming an amorphous hafnium oxide film on a silicon substrate, A crystallization step of irradiating the amorphous hafnium oxide film with pulsed laser light having a wavelength in the ultraviolet region so that the amorphous hafnium oxide film is modified into a hafnium oxide film mainly composed of the o-phase and no aggregation of the hafnium oxide film mainly composed of the o-phase occurs. A method for modifying a hafnium oxide film comprising the steps of:

2. The amorphous hafnium oxide film is formed by the Thermal ALD method, The energy density of the pulsed laser light is 400 mJ / cm ２ The method for modifying a hafnium oxide film according to claim 1, wherein the energy density is 400 mJ / cm or more.

3. The method for modifying a hafnium oxide film according to claim 2, wherein the wavelength of the pulsed laser light is 248 nm, the pulse interval is 10 ms, and the pulse width is several tens of ns.

4. The method for modifying a hafnium oxide film according to claim 3, wherein the pulsed laser light is emitted from a pulsed laser irradiation device of a KrF light source.

5. The X-ray diffraction pattern of the hafnium oxide film modified by the crystallization step obtained by an X-ray diffractometer has a peak near 2θ = 30.35°, The SEM image of the hafnium oxide film modified by the crystallization step obtained by a scanning electron microscope does not include a relatively bright portion and a relatively dark portion evaluated as aggregation of the hafnium oxide film. The method for modifying a hafnium oxide film according to claim 1.

6. A non-volatile memory device comprising a silicon substrate and a hafnium oxide film formed on the silicon substrate, The hafnium oxide film is, A film forming step of forming an amorphous hafnium oxide film on the silicon substrate, A non-volatile memory device which is a hafnium oxide film mainly composed of the o-phase formed by performing a crystallization step of irradiating the amorphous hafnium oxide film with pulsed laser light having a wavelength in the ultraviolet region so that the amorphous hafnium oxide film is modified into a hafnium oxide film mainly composed of the o-phase and no aggregation of the hafnium oxide film mainly composed of the o-phase occurs.

7. A source region formed on one side of the silicon substrate and exposed from the one side, A drain region formed on one side of the silicon substrate and at a location away from the source region and exposed from the one side, A gate electrode formed on the hafnium oxide film, A source electrode electrically connected to the source region through a first contact hole formed in the hafnium oxide film corresponding to the source region, A drain electrode electrically connected to the drain region through a second contact hole formed in the hafnium oxide film corresponding to the drain region; The film formation step forms an amorphous hafnium oxide film in a state of covering the source region and the drain region on one surface side of the silicon substrate; The crystallization step irradiates the amorphous hafnium oxide film with pulsed laser light having a wavelength in the ultraviolet region so that the amorphous hafnium oxide film is modified into a hafnium oxide film mainly composed of the o-phase and aggregation of the hafnium oxide film mainly composed of the o-phase does not occur. The nonvolatile memory device according to claim 6.

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