Method for modifying hafnium oxide film and nonvolatile memory device

Abstract

Provided are a method for modifying a hafnium oxide film, and the like, which can crystallize (modify) a hafnium oxide film into a hafnium oxide film composed mainly of an o phase. A method for modifying a hafnium oxide film includes a film formation step (S11) of forming an amorphous hafnium oxide film on a silicon substrate, and a crystallization step (S12) of irradiating the amorphous hafnium oxide film with a pulsed laser having a wavelength in the ultraviolet region, so that the amorphous hafnium oxide film is modified into a hafnium oxide film composed mainly of an o phase and coalescence of the hafnium oxide film composed mainly of an o phase does not occur.

Description

Technical Field

[0001] This disclosure relates to methods for modifying hafnium oxide films and non-volatile storage devices. Background Technology

[0002] Crystallization treatment by annealing silicon substrates with hafnium oxide films has been practiced. In addition to general resistance heating, RTA (rapid thermal annealing) and other methods have been used. For example, an example of such annealing treatment is disclosed in Patent Document 1.

[0003] References

[0004] Patent documents

[0005] [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2023-135612 Summary of the Invention

[0006] Technical issues

[0007] However, among hafnium oxide (film) which may contain multiple crystalline phases, the paraelectric m phase (monoclinic phase) is the most stable crystalline phase. Therefore, the following problems exist: it is difficult to suppress the most stable m phase, and it is difficult to crystallize (modify) hafnium oxide (film) into hafnium oxide (film) mainly composed of ferroelectric o phase (orthorhombic phase) through the above crystallization treatment.

[0008] Other issues (or objectives) and novel features will become apparent from the description in the specification and accompanying drawings of this disclosure.

[0009] Solution to the problem

[0010] The 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 a pulsed laser in the ultraviolet region, such that the amorphous hafnium oxide film is modified into a hafnium oxide film mainly composed of the o phase, and that agglomeration of the hafnium oxide film mainly composed of the o phase does not occur.

[0011] Beneficial effects of the invention

[0012] According to the embodiments, a method for modifying hafnium oxide films and a non-volatile storage device can be provided, the method being able to crystallize (modify) hafnium oxide (film) into hafnium oxide (film) mainly composed of ferroelectric O phase. Attached Figure Description

[0013] Figure 1 This is a flowchart of a method for modifying a hafnium oxide film according to this embodiment;

[0014] Figure 2AThis is a schematic diagram of the 1T1C (capacitor type) structure;

[0015] Figure 2B This is a schematic structural diagram of a 1T (transistor type);

[0016] Figure 3 This is a schematic diagram illustrating how an amorphous hafnium oxide film 20 is formed on a silicon substrate 10;

[0017] Figure 4 This is a schematic diagram illustrating how the hafnium oxide film 20 formed on the silicon substrate 10 is crystallized (modified);

[0018] Figure 5A It is a graph showing the X-ray diffraction pattern (the result of Experiment 1);

[0019] Figure 5B It is a graph showing the X-ray diffraction pattern (the result of Experiment 2);

[0020] Figure 6 This is a schematic diagram illustrating how the hafnium oxide film 20 formed on the silicon substrate 10 is crystallized (modified);

[0021] Figure 7A It is a graph showing the X-ray diffraction pattern (the result of Experiment 3);

[0022] Figure 7B It is a graph showing the X-ray diffraction pattern (the result of Experiment 4);

[0023] Figure 8 This is an SEM image of a hafnium oxide film taken by SEM.

[0024] Figure 9A It is a graph showing the X-ray diffraction pattern (the result of Experiment 5);

[0025] Figure 9B It is a graph showing the X-ray diffraction pattern (the result of Experiment 6);

[0026] Figure 10 This is an SEM image of a hafnium oxide film taken by SEM.

[0027] Figure 11A Comparative examples are shown;

[0028] Figure 11B An example is shown;

[0029] Figure 12 This is a schematic structural diagram of a non-volatile storage device M, showing a hafnium oxide film 20 modified according to the method for modifying a hafnium oxide film according to an embodiment. T+K It is applied to the non-volatile storage device M; and

[0030] Figure 13 This is an example of a flowchart for the process of manufacturing a non-volatile memory device M. Detailed Implementation

[0031] In the following description, specific embodiments will be illustrated with reference to the accompanying drawings. However, this disclosure is not limited to the embodiments shown below. Furthermore, for the sake of clarity, the following description and drawings have been appropriately simplified.

[0032] <Summary of methods for modifying hafnium oxide films>

[0033] First, a summary of a method for modifying a hafnium oxide film (hereinafter also referred to as a hafnium oxide film modification method) according to this disclosure is described.

[0034] Figure 1 This is a flowchart of a hafnium oxide film modification method according to the present disclosure.

[0035] like Figure 1 As shown, the method for modifying a hafnium oxide film according to this disclosure includes: preparing a silicon substrate 10 (step S10); a film formation step (step S11) to form an amorphous hafnium oxide film 20 on the silicon substrate 10; and a crystallization step (step S12) to irradiate the amorphous hafnium oxide film 20 with a pulsed laser with a wavelength in the ultraviolet region. In the crystallization step, the energy density, wavelength, pulse interval, and pulse width of the pulsed laser are selected such that the amorphous hafnium oxide film 20 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 (orthorhombic phase) occurs.

[0036] According to the hafnium oxide film modification method of this disclosure, the amorphous hafnium oxide film 20 formed on the silicon substrate 10 can be crystallized (modified) into a hafnium oxide film in which the most stable m phase is suppressed, that is, crystallized (modified) into a hafnium oxide film mainly composed of the ferroelectric o phase.

[0037] By evaluating the hafnium oxide film (crystalline phase) crystallized in step S12 using X-ray diffraction equipment, it can be confirmed that the amorphous hafnium oxide film has been crystallized (modified) into a hafnium oxide film with the most stable m phase suppressed, that is, crystallized (modified) into a hafnium oxide film mainly composed of the ferroelectric o phase (step S13). Note that... Figure 1 In this context, "a-HfO2" represents amorphous hafnium oxide film 20. Figure 1 The “x-HfO2” in the text represents a crystallized hafnium oxide film 20. Figure 1 In the text, “(o)-HfO2” indicates the hafnium oxide film in which the most stable m phase is suppressed, that is, it indicates the hafnium oxide film mainly composed of the ferroelectric o phase.

[0038] Hafnium oxide films that have been crystallized (modified) and whose most stable m-phase has been suppressed by the hafnium oxide film modification method according to the present disclosure, i.e., hafnium oxide films mainly composed of ferroelectric o-phase, can be applied to (i.e., for) non-volatile storage devices.

[0039] <Background of the method for forming hafnium oxide film>

[0040] Next, the background of the method for forming the hafnium oxide film according to this disclosure will be described.

[0041] In the past, in the field of non-volatile storage devices, PZT (lead zirconate titanate) and SBT (strontium bismuthate tantalate) have been used as ferroelectric materials and commercialized as 1T1C (capacitor type) materials. Figure 2A This is a schematic diagram of the 1T1C (capacitor type) structure.

[0042] In contrast, the inventors of this application applied the aforementioned conventional ferroelectric material to 1T (transistor type) in order to improve density, and studied how to reduce the thickness of the conventional ferroelectric material. Figure 2B This is a schematic diagram of a 1T (transistor type) structure.

[0043] However, it is known that when the aforementioned conventional ferroelectric materials are applied to 1T (transistor type), there are limitations to reducing the thickness of the ferroelectric materials, and there are issues regarding their affinity with the silicon substrate.

[0044] Therefore, the inventors of this application investigated the use of hafnium oxide (HfO2) for ferroelectric materials used in 1T (transistor type), which exhibits ferroelectricity when formed as an extreme thin film, and the film can be formed directly on a silicon substrate.

[0045] However, among hafnium oxide, which may contain multiple crystalline phases, the paraelectric m-phase (monoclinic phase) is the most stable crystalline phase. Therefore, the inventors of this application have studied a method for suppressing the crystallization of hafnium oxide, which is the most stable m-phase. The inventors of this application conducted numerous experiments during the aforementioned research process.

[0046] As a result, the inventors of this application have discovered a method for crystallizing (modifying) an amorphous hafnium oxide film formed on a silicon substrate into a hafnium oxide film in which the most stable m phase is suppressed, i.e., crystallizing (modifying) into a hafnium oxide film mainly composed of a ferroelectric o phase (i.e., a method for forming a hafnium oxide film according to this disclosure has been discovered).

[0047] In the following description, experiments 1 to 6 conducted by the inventors of this application in order to obtain the method for forming a hafnium oxide film according to this disclosure will be described.

[0048] Experiment 1

[0049] Experiment 1 was conducted under the conditions shown in Table 1 below.

[0050] [Table 1]

[0051]

[0052] Experiment 1 will be described in detail below.

[0053] <Membrane Formation in Experiment 1>

[0054] Figure 3 This is a schematic diagram showing how an amorphous hafnium oxide film 20 is formed on a silicon substrate 10.

[0055] In Experiment 1, an amorphous hafnium oxide film 20 was formed on a silicon substrate 10 using a film formation apparatus (an ALD apparatus (demonstration unit) manufactured by JSW AFTY) via thermal ALD. ALD is an abbreviation for Atomic Layer Deposition. In the following text, the amorphous hafnium oxide film 20 formed on the silicon substrate 10 by thermal ALD will be referred to as hafnium oxide film 20. T .

[0056] Specifically, such as Figure 3 As shown, by contacting one surface (one surface or one side of a surface) of the silicon substrate 10 with a flowing source gas, oxidant, and inert gas, an extremely thin hafnium oxide film 20 with a thickness of 10 nm is formed on the silicon substrate 10, which has been preheated to 120°C by a heater. T Note that tEMAH (tetra(ethylmethylamino)hafnium) is used as the source gas; O3 is used as the oxidant; and N2 is used as the inert gas.

[0057] <Crystallization (Modification) in Experiment 1>

[0058] Figure 4 This is a schematic diagram illustrating how the hafnium oxide film 20 formed on the silicon substrate 10 is crystallized (modified);

[0059] In Experiment 1, a pulsed laser irradiation device equipped with a XeCl light source (wavelength 308 nm) (JSWAktina Systems excimer laser irradiation device (demonstration unit)) was used, with a pulsed laser in the ultraviolet region. X The hafnium oxide film 20 formed on the silicon substrate 10 was irradiated. TPulsed laser 30 X It has a wavelength of 308 nm, a pulse interval of 10 ms (100 Hz), and a pulse width (FWHM) of tens of nanoseconds, and the number of irradiations (emissions) is 200. In Experiment 1, the pulsed laser 30 X The energy density was changed to 170 mJ / cm³ 2 220mJ / cm 2 270mJ / cm 2 and 400mJ / cm 2 And 200 pulses of laser light were applied at each of these energy densities. X .

[0060] Specifically, such as Figure 4 As shown, in a nitrogen atmosphere, a pulsed laser 30 X The silicon substrate 10 (hafnium oxide film 20) conveyed by the conveying mechanism (not shown) in the direction indicated by arrow AR1 was irradiated. T Pulsed laser 30 X The width (width along the conveying direction) is approximately 400 μm (see [reference]). Figure 4 At this point, the silicon substrate 10 (hafnium oxide film 20) T The conveying speed of the silicon substrate 10 (hafnium oxide film 20) is set to 0.2 mm / s, so that when the silicon substrate 10 (hafnium oxide film 20) is transported, the conveying speed is set to 0.2 mm / s. T When it was being transported, it had already been treated with a pulsed laser for 30 seconds. X The irradiated adjacent areas overlap with each other. In the following text, the area formed on the silicon substrate 10 by thermal ALD and irradiated with a pulsed laser 30... X 20 irradiated hafnium oxide film T It will be called hafnium oxide film 20 T+X Note that in Figure 4 In the figure, reference numeral A1 indicates the area that has been irradiated with pulsed laser, and reference numeral A2 indicates the area that has not yet been irradiated with pulsed laser.

[0061] <Results of Experiment 1>

[0062] Next, the results (evaluation results) of Experiment 1 will be described.

[0063] <Evaluation conducted using X-ray diffraction equipment>

[0064] Figure 5A This is a graph showing the X-ray diffraction pattern (results of Experiment 1). Figure 5A In the attached figure, the reference numeral G XT（170） This indicates an energy density of 170 mJ / cm³. 2 A graph showing the time elapsed. (Figure label G) XT（220） This indicates an energy density of 220 mJ / cm³.2 A graph showing the time elapsed. (Figure label G) XT（270） This indicates an energy density of 270 mJ / cm³. 2 A graph showing the time elapsed. (Figure label G) XT（400） This indicates an energy density of 400 mJ / cm³. 2 A graph showing the time elapsed.

[0065] Regarding the evaluation conducted using X-ray diffraction equipment, using an X-ray diffraction device (Rigaku Corporation X-ray diffraction equipment), the above-mentioned pulsed laser 30... X 20 irradiated hafnium oxide film T+X The (crystal phase) was evaluated. X-ray diffraction equipment is also known as XRD (X-ray diffraction). Various measurement methods exist for X-ray diffraction equipment, and 2θ scans, suitable for asymmetric reflection measurements suitable for thin film evaluation, were performed. Because the thin film is evaluated at a small incident angle, the thin film method measurement is also known as GI-XRD (Grazing Incidence XRD). The measurement condition for X-ray diffraction equipment is an incident angle ω of 0.4 degrees (ω = 0.4 degrees).

[0066] As a premise, when the crystallization of the most stable m-phase is further developed, that is, when the amorphous hafnium oxide film (showing paraelectricity) formed on the silicon substrate 10 is modified into a hafnium oxide film mainly composed of the o-phase (showing ferroelectricity), the X-ray diffraction pattern of the modified hafnium oxide film obtained by X-ray diffraction equipment has a peak near 2θ, i.e., 30.35° (2θ=30.35°).

[0067] Reference Figure 5A It should be understood that in Experiment 1, curve G... XT（170） G XT（220） G XT（270） and G XT（400） In either of them, there is no peak near 2θ, i.e., 30.35° (2θ=30.35°).

[0068] In other words, it should be understood that in Experiment 1, the hafnium oxide film 20 formed on the silicon substrate 10 T The hafnium oxide film that cannot be crystallized (modified) into the most stable m phase to achieve suppression, that is, the hafnium oxide film that cannot be crystallized (modified) into a film mainly composed of ferroelectric o phase.

[0069] <Experiment 2>

[0070] Experiment 2 was conducted under the conditions shown in Table 2 below.

[0071] [Table 2]

[0072]

[0073] Experiment 2 will be described in detail below.

[0074] <Membrane Formation in Experiment 2>

[0075] In Experiment 2, an amorphous hafnium oxide film 20 was formed on a silicon substrate 10 using a film formation apparatus (an ALD apparatus (demonstration unit) manufactured by JSW AFTY) via plasma ALD. In the following text, the amorphous hafnium oxide film 20 formed on the silicon substrate 10 by plasma ALD will be referred to as hafnium oxide film 20. P .

[0076] Specifically, similar to Experiment 1 (see...) Figure 3 By contacting one side surface of the silicon substrate 10 with a 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 surface) which had been preheated to 120°C by a heater. P Note that tEMAH (tetra(ethylmethylamino)hafnium) is used as the source gas; O2 plasma is used as the oxidant; and N2 is used as the inert gas.

[0077] <Crystallization (Modification) in Experiment 2>

[0078] In Experiment 2, similar to Experiment 1 (see...) Figure 4 Using a pulsed laser irradiation device equipped with an XeCl light source (wavelength 308nm) (JSW Aktina Systems excimer laser irradiation device (demonstration unit)), a pulsed laser with a wavelength in the ultraviolet region of 308nm was used. X The hafnium oxide film 20 formed on the silicon substrate 10 was irradiated. P Pulsed laser 30 X It has a wavelength of 308 nm, a pulse interval of 10 ms (100 Hz), and a pulse width of tens of nanoseconds (FWHM), and is subjected to 200 irradiations. In Experiment 2, the pulsed laser 30 X The energy density was changed to 170 mJ / cm³ 2 220mJ / cm 2 270mJ / cm 2 and 400mJ / cm 2 And 200 pulses of laser light were applied at each of these energy densities. X .

[0079] Specifically, similar to Experiment 1 (see...) Figure 4In a nitrogen atmosphere, using a pulsed laser for 30... X The silicon substrate 10 (hafnium oxide film 20) conveyed by the conveying mechanism (not shown) in the direction indicated by arrow AR1 was irradiated. P Pulsed laser 30 X The width (width along the conveying direction) is approximately 400 μm (see [reference]). Figure 4 At this point, the silicon substrate 10 (hafnium oxide film 20) P The conveying speed of the silicon substrate 10 (hafnium oxide film 20) is set to 0.2 mm / s, so that when the silicon substrate 10 (hafnium oxide film 20) is transported, the conveying speed is set to 0.2 mm / s. P When it was being transported, it had already been treated with a pulsed laser for 30 seconds. X The irradiated adjacent areas overlap with each other. In the following text, the area formed on the silicon substrate 10 by plasma ALD and irradiated with a pulsed laser 30 is described. X 20 irradiated hafnium oxide film P It will be called hafnium oxide film 20 P+X .

[0080] <Results of Experiment 2>

[0081] Next, the results (evaluation results) of Experiment 2 will be described.

[0082] <Evaluation conducted using X-ray diffraction equipment>

[0083] Figure 5B This is a graph showing the X-ray diffraction pattern (results of Experiment 2). Figure 5B In the attached figure, the reference numeral G XP（170） This indicates an energy density of 170 mJ / cm³. 2 A graph showing the time elapsed. (Figure label G) XP（220） This indicates an energy density of 220 mJ / cm³. 2 A graph showing the time elapsed. (Figure label G) XP（270） This indicates an energy density of 270 mJ / cm³. 2 A graph showing the time elapsed. (Figure label G) XP（400） This indicates an energy density of 400 mJ / cm³. 2 A graph showing the time elapsed.

[0084] Regarding the evaluation using X-ray diffraction equipment, similar to Experiment 1, X-ray diffraction equipment (Rigaku Corporation X-ray diffraction equipment) was used to evaluate the X-ray diffraction results obtained above using pulsed laser 30. X 20 irradiated hafnium oxide film P+X The (crystal phase) was evaluated. The X-ray diffraction equipment was used under the following conditions: incident angle ω = 0.4deg.

[0085] Reference Figure 5B It should be understood that in Experiment 2, curve G...XP（170） G XP（220） G XP（270） and G XP（400） In either of them, there is no peak near 2θ, i.e., 30.35° (2θ=30.35°).

[0086] In other words, it should be understood that in Experiment 2, the hafnium oxide film 20 formed on the silicon substrate 10 P The hafnium oxide film that cannot be crystallized (modified) into the most stable m phase to achieve suppression, that is, the hafnium oxide film that cannot be crystallized (modified) into a film mainly composed of ferroelectric o phase.

[0087] <Verification of Experiments 1 and 2>

[0088] As mentioned above, in both Experiment 1 and Experiment 2, no peak appeared near 2θ, i.e., 30.35° (2θ=30.35°) (see [reference]). Figure 5A and Figure 5B This is believed to be due to the lack of lattice vibrations for further development of amorphous hafnium oxide film crystallization. Therefore, to compensate for the lack of lattice vibrations, experiments 3 to 6 were conducted, in which pulsed laser irradiation equipment with a KrF light source having a photon kinetic energy greater than that of the XeCl light source was used.

[0089] Experiment 3

[0090] Experiment 3 was conducted under the conditions shown in Table 3 below.

[0091] [Table 3]

[0092]

[0093] Experiment 3 will be described in detail below.

[0094] <Membrane Formation in Experiment 3>

[0095] In Experiment 3, similar to Experiment 1, an amorphous hafnium oxide film 20 was formed on a silicon substrate 10 using a film formation apparatus (an ALD apparatus (demonstration unit) manufactured by JSW AFTY) via thermal ALD. T .

[0096] Specifically, similar to Experiment 1 (see...) Figure 3 By contacting one surface of the silicon substrate 10 with a 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, which had been preheated to 120°C by a heater. T Note that tEMAH (tetra(ethylmethylamino)hafnium) is used as the source gas; O3 is used as the oxidant; and N2 is used as the inert gas.

[0097] <Crystallization (Modification) in Experiment 3>

[0098] Figure 6 This illustrates how a hafnium oxide film 20 is formed on a silicon substrate 10. T A schematic diagram of crystallization (modification).

[0099] In Experiment 3, a pulsed laser irradiation device equipped with a KrF light source (wavelength 248 nm) (JSWAktina Systems excimer laser irradiation device (demonstration unit)) was used, with a pulsed laser wavelength in the ultraviolet region of 30 nm. K The hafnium oxide film 20 formed on the silicon substrate 10 was irradiated. T Pulsed laser 30 K It has a wavelength of 248 nm, a pulse interval of 10 ms (100 Hz), and a pulse width of tens of nanoseconds (FWHM), and the number of irradiations is 1 (1 shot). In Experiment 3, the pulsed laser 30 K The energy density was changed to 300 mJ / cm³ 2 350mJ / cm 2 400mJ / cm 2 and 450mJ / cm 2 And each of these energy densities was subjected to a single (1) pulse of laser light. K .

[0100] Specifically, such as Figure 6 As shown, using a pulsed laser irradiation device (JSW Aktina Systems excimer laser irradiation device (demonstration unit)), in a nitrogen atmosphere supplied to chamber 41, a pulsed laser 30 was used. K The silicon substrate 10 (hafnium oxide film 20) disposed in the chamber 41 was irradiated through anhydrous quartz 42. T Chamber 41 is transported by conveyor 40 along the X (+X, -X) and Y (+Y, -Y) directions. Figure 6 Move in a direction perpendicular to the paper. For example... Figure 6 As shown, chamber 41 is formed by combining multiple chamber components 41a, 41b, 41c, etc., and is sealed by sealing materials 43 and 44 and cushioning material 45. Cushioning material 45 is a Teflon (registered trademark) cushioning material provided to prevent direct interference between the anhydrous quartz 42 and chamber component 41a (made of stainless steel). Figure 6 In the attached drawing, reference numeral 47 indicates a valve located in the nitrogen supply pipe 46, and reference numeral 49 indicates a valve located 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.

[0101] Pulsed laser 30 K The dimensions (cross-sectional dimensions) are 3mm × 3mm. Furthermore, each application of a single pulsed laser lasts 30 seconds. K At this time, the chambers 41 are all moved so that adjacent areas that have been irradiated by the pulsed laser 30 do not overlap with each other. In the following text, the areas formed on the silicon substrate 10 by thermal ALD and irradiated by the pulsed laser 30... K 20 irradiated hafnium oxide film T It will be called hafnium oxide film 20 T+K .

[0102] <Results of Experiment 3>

[0103] Next, the results (evaluation results) of Experiment 3 will be described.

[0104] <Evaluation conducted using X-ray diffraction equipment>

[0105] Figure 7A This is a graph showing the X-ray diffraction pattern (results of Experiment 3). Figure 7A In the attached figure, the reference numeral G KT（300） This indicates an energy density of 300 mJ / cm³. 2 A graph showing the time elapsed. (Figure label G) KT（350） This indicates an energy density of 350 mJ / cm³. 2 A graph showing the time elapsed. (Figure label G) KT（400） This indicates an energy density of 400 mJ / cm³. 2 A graph showing the time elapsed. (Figure label G) KT（450） This indicates an energy density of 450 mJ / cm³. 2 A graph showing the time elapsed.

[0106] Regarding the evaluation using X-ray diffraction equipment, similar to Experiment 1, X-ray diffraction equipment (Rigaku Corporation X-ray diffraction equipment) was used to evaluate the X-ray diffraction results obtained above using pulsed laser 30. K 20 irradiated hafnium oxide film T+K The (crystal phase) was evaluated. The X-ray diffraction equipment was used under the following conditions: incident angle ω = 0.4deg.

[0107] Reference Figure 7A It should be understood that in Experiment 3, curve G... KT（400） G KT（450） In either of them, there is a peak near 2θ, i.e., 30.35° (2θ=30.35°).

[0108] In other words, based on the evaluation conducted using X-ray diffraction equipment, it should be understood that the amorphous hafnium oxide film 20 formed by the thermal ALD method... TIn this case, by selecting a wavelength of 248 nm and an energy density of 400 mJ / cm², 2 Or higher pulsed laser 30 K It can make the hafnium oxide film 20 T The most stable m phase is crystallized (modified) to obtain a suppressed hafnium oxide film, that is, a hafnium oxide film mainly composed of ferroelectric o phase is crystallized (modified).

[0109] <Evaluation conducted by SEM>

[0110] Figure 8 The upper and middle rows are hafnium oxide films obtained by SEM. T+K The SEM image. SEM is an abbreviation for Scanning Electron Microscope, also known as scanning electron microscopy.

[0111] Using SEM (Scanning Electron Microscope manufactured by Hitachi High Technology Co., Ltd.), the hafnium oxide film 20 T+K Surface shape was evaluated. Relatively bright areas in each SEM image represent coalescence sites (hafnium oxide coalescence sites), while relatively dark areas represent thinner areas within the hafnium oxide film. Elemental identification in the brighter areas revealed further coalescence. Note that brightness was not normalized for all images; therefore, the evaluation was based on contrast within the SEM images.

[0112] Therefore, when SEM images include relatively bright and relatively dark areas, the hafnium oxide film 20 can be evaluated. T+K Aggregation. On the other hand, when the SEM image does not include relatively bright and relatively dark areas (e.g., when it only includes one of the brighter and darker areas), the hafnium oxide film 20 can be evaluated. T+K Do not gather together.

[0113] Reference Figure 8 The upper-middle row, with an energy density of 450 mJ / cm³ 2 In this case, the energy density is 450 mJ / cm³. 2 The SEM image includes relatively bright and relatively dark areas (a mixture of two areas). Therefore, at an energy density of 450 mJ / cm², 2 Under these circumstances, the hafnium oxide film 20 can be evaluated. T+K Agglomeration. This is due to the shape of the hafnium oxide film (primarily the hafnium oxide film 20 after formation). T The surface shape was not maintained, so the hafnium oxide film 20 agglomerated as described above... T+K It is not suitable as a ferroelectric material for use in non-volatile storage devices.

[0114] Conversely, at an energy density of 400 mJ / cm2 In this case, the energy density is 400 mJ / cm³. 2 The SEM images do not include relatively bright and relatively dark areas. Therefore, at an energy density of 400 mJ / cm², 2 Under these circumstances, the hafnium oxide film 20 can be evaluated. T+K It does not coalesce. This is because of the shape of the hafnium oxide film (primarily the hafnium oxide film 20 after formation). T The surface shape is maintained, so as described above, the hafnium oxide film 20 does not agglomerate. T+K Suitable as a ferroelectric material for use in non-volatile storage devices.

[0115] As stated above, based on Experiment 3, it should be understood that the amorphous hafnium oxide film 20 formed by the thermal ALD method... T In this case, by selecting a wavelength of 248 nm and an energy density of 400 mJ / cm², 2 Or higher pulsed laser 30 K It can make the hafnium oxide film 20 T The hafnium oxide film is suppressed by crystallization (modification) into the most stable m phase, that is, the hafnium oxide film is mainly composed of ferroelectric o phase without the aggregation of hafnium oxide film.

[0116] <Experiment 4>

[0117] Experiment 4 was conducted under the conditions shown in Table 4 below.

[0118] [Table 4]

[0119]

[0120] Experiment 4 will be described in detail below.

[0121] <Membrane formation in Experiment 4>

[0122] In Experiment 4, similar to Experiment 2, an amorphous hafnium oxide film 20 was formed on a silicon substrate 10 using a film formation apparatus (an ALD apparatus (demonstration unit) manufactured by JSW AFTY) via plasma ALD. P .

[0123] Specifically, similar to Experiment 1 (see...) Figure 3 By contacting one side surface of the silicon substrate 10 with a flowing source gas, oxidant, and inert gas, an extremely thin hafnium oxide film 20 with a thickness of 10 nm is formed on one side surface of the silicon substrate 10, which has been preheated to 120°C by a heater. P Note that tEMAH (tetra(ethylmethylamino)hafnium) is used as the source gas; O2 plasma is used as the oxidant; and N2 is used as the inert gas.

[0124] <Crystallization (Modification) in Experiment 4>

[0125] In Experiment 4, similar to Experiment 3, a pulsed laser irradiation device equipped with a KrF light source (wavelength 248nm) (JSW Aktina Systems excimer laser irradiation device (demonstration unit)) was used, with a pulsed laser in the ultraviolet region. K The hafnium oxide film 20 formed on the silicon substrate 10 was irradiated. P Pulsed laser 30 K It has a wavelength of 248 nm, a pulse interval of 10 ms (100 Hz), and a pulse width of tens of nanoseconds (FWHM), and the number of irradiations is 1 (1 shot). In Experiment 4, the pulsed laser 30 K The energy density was changed to 300 mJ / cm³ 2 350mJ / cm 2 400mJ / cm 2 and 450mJ / cm 2 And each of these energy densities was subjected to a single (1) pulse of laser light. K .

[0126] Specifically, it is similar to Experiment 3 (see Figure 6 Using a pulsed laser irradiation device (an excimer laser irradiation device (demonstration unit) manufactured by JSW Aktina Systems), in a nitrogen atmosphere supplied to chamber 41, a pulsed laser 30 K The silicon substrate 10 (hafnium oxide film 20) disposed in chamber 41 was irradiated through anhydrous quartz 42. Chamber 41 was transported by conveying mechanism 40 along the X (+X, -X) direction and the Y (+Y, -Y) direction. Figure 6 Move in a direction perpendicular to the paper.

[0127] Pulsed laser 30 K The dimensions (cross-sectional dimensions) are 3mm × 3mm. Furthermore, each application of a single pulsed laser lasts 30 seconds. K At this time, the chambers 41 are all moved so that adjacent areas that have been irradiated by the pulsed laser 30 do not overlap with each other. In the following text, the regions formed on the silicon substrate 10 by plasma ALD and irradiated by the pulsed laser 30... K 20 irradiated hafnium oxide film P It will be called hafnium oxide film 20 P+K .

[0128] <Results of Experiment 4>

[0129] Next, the results (evaluation results) of Experiment 4 will be described.

[0130] <Evaluation conducted using X-ray diffraction equipment>

[0131] Figure 7B This is a graph showing the X-ray diffraction pattern (results of Experiment 4). Figure 7B In the attached figure, the reference numeral G KP（300） This indicates an energy density of 300 mJ / cm³. 2 A graph showing the time elapsed. (Figure label G) KP（350） This indicates an energy density of 350 mJ / cm³. 2 A graph showing the time elapsed. (Figure label G) KP（400） This indicates an energy density of 400 mJ / cm³. 2 A graph showing the time elapsed. (Figure label G) KP（450） This indicates an energy density of 450 mJ / cm³. 2 A graph showing the time elapsed.

[0132] Regarding the evaluation using X-ray diffraction equipment, similar to Experiment 1, X-ray diffraction equipment (an X-ray diffraction equipment manufactured by Rigaku Holdings Corporation) was used to evaluate the X-ray diffraction equipment as described above, which had already been subjected to pulsed laser 30... K 20 irradiated hafnium oxide film P+K The (crystal phase) was evaluated. The X-ray diffraction equipment was used under the following conditions: incident angle ω = 0.4deg.

[0133] Reference Figure 7B It should be understood that in Experiment 4, curve G... KP（350） G KP（400）和 G KP（450） In either of them, there is a peak near 2θ, i.e., 30.35° (2θ=30.35°).

[0134] In other words, based on the evaluation conducted using X-ray diffraction equipment, it should be understood that the amorphous hafnium oxide film 20 formed by plasma ALD method... P In this case, by selecting a wavelength of 248 nm and an energy density of 350 mJ / cm², 2 Or higher pulsed laser 30 K It can make the hafnium oxide film 20 P The most stable m phase is crystallized (modified) to obtain a suppressed hafnium oxide film, that is, a hafnium oxide film mainly composed of ferroelectric o phase is crystallized (modified).

[0135] <Evaluation conducted by SEM>

[0136] Figure 8 The lower and middle rows are hafnium oxide films obtained by SEM. P+K SEM image.

[0137] Similar to Experiment 3, the hafnium oxide film 20 was examined using SEM (scanning electron microscope manufactured by Hitachi High Technology Co., Ltd.). P+K The surface shape was evaluated.

[0138] Reference Figure 8 The middle and lower rows, at an energy density of 300 mJ / cm³ 2 350mJ / cm 2 400mJ / cm 2 and 450mJ / cm 2 In this case, each SEM image includes relatively bright and relatively dark areas (a mixture of two areas). Therefore, at an energy density of 300 mJ / cm², 2 350mJ / cm 2 400mJ / cm 2 and 450mJ / cm 2 Under these circumstances, the hafnium oxide film 20 can be evaluated. T+K Agglomeration. This is due to the shape of the hafnium oxide film (primarily the hafnium oxide film 20 after formation). P The surface shape was not maintained, so the hafnium oxide film 20 agglomerated as described above... P+K It is not suitable as a ferroelectric material for use in non-volatile storage devices.

[0139] As described above, based on Experiment 4, it should be understood that the amorphous hafnium oxide film 20 formed by plasma ALD method... P In this case, although by selecting a wavelength of 248 nm and an energy density of 400 mJ / cm², 2 Or higher pulsed laser 30 K It can make the hafnium oxide film 20 P The most stable m phase is crystallized (modified) to obtain a suppressed hafnium oxide film, that is, crystallized (modified) to form a hafnium oxide film mainly composed of ferroelectric o phase, but the aggregation of hafnium oxide film will occur.

[0140] <Verification of Experiments 3 and 4>

[0141] Experiments 3 and 4 are examples of applications using the following conditions: a pulsed laser irradiation device equipped with a KrF light source was used; the number of irradiations was fixed at 1 (1 shot); and a pulsed laser with altered energy density 30 was applied. K Furthermore, they have peaks near 2θ, i.e., 30.35° (2θ = 30.35°) (see [reference]). Figure 7A and Figure 7B ).

[0142] In thermal ALD (Experiment 3), the m phase was completely suppressed, while in plasma ALD (Experiment 4), the crystallization of the m phase further developed slightly (see [link to experiment 4]). Figure 7A and Figure 7B It is speculated that this difference in deposition methods is caused by differences in film density. The density in plasma ALDs is often higher than that in thermal ALDs. Higher density means that lattice vibrations propagate more easily.

[0143] It can be inferred that in thermal ALD, due to the relatively low density and the difficulty in propagating lattice vibrations, the structural changes do not reach the lower symmetry m-phase. Conversely, it can be inferred that in plasma ALD, due to the relatively high density and the ease of propagation of lattice vibrations, the structural changes reach the lower symmetry m-phase.

[0144] Furthermore, crystallization in thermal ALD (Experiment 3) requires 400 mJ / cm². 2 Or even higher energy densities, while crystallization in plasma ALD (Experiment 4) requires 350 mJ / cm². 2 Or higher energy density. It is believed that this difference is also caused by the difference in density.

[0145] In thermal ALD (Experiment 3), when the energy density is 400 mJ / cm³ 2 At or higher levels, crystallization has progressed further, and the m-phase has been suppressed. However, as shown by SEM results, at 450 mJ / cm², crystallization still occurs. 2 At energy densities below a certain level, coalescence begins. Simultaneously, in plasma ALD (Experiment 4), coalescence occurs at an energy density of 350 mJ / cm². 2 At or above 300 mJ / cm², crystallization has progressed further, but at 300 mJ / cm², it is still relatively low. 2 Agglomeration has already occurred at the energy density.

[0146] Based on the above facts, it should be understood that the process of preventing agglomeration, that is, maintaining the shape of the hafnium oxide film (mainly the surface shape of the hafnium oxide film after formation) while simultaneously suppressing the crystallization of the m-phase, requires the use of thermal ALD film formation technology and necessitates a process with a speed of 400 mJ / cm². 2 The energy density is applied to a pulsed laser with a wavelength of 248 nm in the ultraviolet region (KrF source).

[0147] <Experiment 5>

[0148] Experiment 5 was conducted under the conditions shown in Table 5 below.

[0149] [Table 5]

[0150]

[0151] Experiment 5 will be described in detail below.

[0152] <Membrane formation in Experiment 5>

[0153] In Experiment 5, similar to Experiment 1, an amorphous hafnium oxide film 20 was formed on a silicon substrate 10 using a film formation apparatus (an ALD apparatus (demonstration unit) manufactured by JSW AFTY) via thermal ALD. T .

[0154] Specifically, similar to Experiment 1 (see...) Figure 3 By contacting one surface of the silicon substrate 10 with a 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, which had been preheated to 120°C by a heater. T Note that tEMAH (tetra(ethylmethylamino)hafnium) is used as the source gas; O3 is used as the oxidant; and N2 is used as the inert gas.

[0155] <Crystallization (Modification) in Experiment 5>

[0156] In Experiment 5, similar to Experiment 3, the hafnium oxide film 20 formed on the silicon substrate 10 was irradiated with a pulsed laser irradiation device (JSW Aktina Systems excimer laser irradiation device (demonstration unit)) equipped with a KrF light source (wavelength 248nm) to the ultraviolet region. T Pulsed laser 30 K It features a wavelength of 248nm, a pulse interval of 10ms (100Hz), a pulse width of tens of nanoseconds (FWHM), and 400mJ / cm. 2 The energy density. In Experiment 5, the pulsed laser 30 K It was applied zero times (deposited state), 1 time (1 shot), 2 times (2 shots), 20 times (20 shots), and 200 times (200 shots).

[0157] Specifically, it is similar to Experiment 3 (see Figure 6 Using a pulsed laser irradiation device (an excimer laser irradiation device (demonstration unit) manufactured by JSW Aktina Systems), in a nitrogen atmosphere supplied to chamber 41, a pulsed laser 30 K The silicon substrate 10 (hafnium oxide film 20) disposed in the chamber 41 was irradiated through anhydrous quartz 42. T Chamber 41 is transported by conveyor 40 along the X (+X, -X) and Y (+Y, -Y) directions. Figure 6 Move in a direction perpendicular to the paper.

[0158] Pulsed laser 30 KThe dimensions (cross-sectional dimensions) are 3mm × 3mm. Furthermore, each predetermined number of pulsed laser pulses (30) K At that time, chambers 41 were all moved so that the pulsed laser 30 had been applied. K Adjacent irradiated areas do not overlap. In the following text, the area formed on the silicon substrate 10 by thermal ALD and irradiated with a pulsed laser 30... K 20 irradiated hafnium oxide film T It will be called hafnium oxide film 20 T+K .

[0159] <Results of Experiment 5>

[0160] Next, the results (evaluation results) of Experiment 5 will be described.

[0161] <Evaluation conducted using X-ray diffraction equipment>

[0162] Figure 9A This is a graph showing the X-ray diffraction pattern (results of Experiment 5). Figure 9A In the attached figure, the reference numeral G KT（0shot） A graph showing the number of irradiations (emissions) when it is zero. (Figure label G) KT（1shot） A graph showing the number of irradiations (emissions) when it is 1. (Figure label G) KT（2shot） The graph represents the number of irradiations (emissions) when it is 2. (Figure label G) KT（20shot） A graph showing the number of irradiations (emissions) when the number of irradiations is 20. (Figure label G) KT（200shot） The graph represents the number of irradiations (emissions) when the number of irradiations is 200.

[0163] Regarding the evaluation using X-ray diffraction equipment, similar to Experiment 1, X-ray diffraction equipment (Rigaku Corporation X-ray diffraction equipment) was used to evaluate the X-ray diffraction results obtained above using pulsed laser 30. K 20 irradiated hafnium oxide film T+K The (crystal phase) was evaluated. The X-ray diffraction equipment was used under the following conditions: incident angle ω = 0.4deg.

[0164] Reference Figure 9A It should be understood that in Experiment 5, curve G... KT（1shot） G KT（2shot） G KT（20shot） and G KT（200shot） In either of them, there is a peak near 2θ, i.e., 30.35° (2θ=30.35°).

[0165] In other words, based on the evaluation conducted using X-ray diffraction equipment, it should be understood that the amorphous hafnium oxide film 20 formed by the thermal ALD method... TIn this case, by selecting a wavelength of 248nm and an energy density of 400mJ / cm², 2 Pulsed laser 30 or higher and with one or more irradiations K It can make the hafnium oxide film 20 T The most stable m phase is crystallized (modified) to obtain a suppressed hafnium oxide film, that is, a hafnium oxide film mainly composed of ferroelectric o phase is crystallized (modified).

[0166] <Evaluation conducted by SEM>

[0167] Figure 10 The upper and middle rows are hafnium oxide films obtained by SEM. T+K SEM image.

[0168] Similar to Experiment 3, the hafnium oxide film 20 was examined using SEM (scanning electron microscope manufactured by Hitachi High Technology Co., Ltd.). T+K The surface shape was evaluated.

[0169] Reference Figure 10 The upper-middle row, with an energy density of 400 mJ / cm³ 2 In this case, the SEM images from 1, 2, 20, and 200 shots do not include relatively bright and relatively dark areas. Therefore, at an energy density of 400 mJ / cm², 2 In this case, it can be evaluated that as long as the number of irradiations is 200 or less, the hafnium oxide film 20 T+K It will not coalesce. This is because of the shape of the hafnium oxide film (primarily the hafnium oxide film 20 after formation). T The surface shape is maintained, so as described above, the hafnium oxide film 20 does not agglomerate. T+K Suitable as a ferroelectric material for use in non-volatile storage devices.

[0170] <Experiment 6>

[0171] Experiment 6 was conducted under the conditions shown in Table 6 below.

[0172] [Table 6]

[0173]

[0174] Experiment 6 will be described in detail below.

[0175] <Membrane Formation in Experiment 6>

[0176] In Experiment 6, similar to Experiment 2, an amorphous hafnium oxide film 20 was formed on a silicon substrate 10 using a film formation apparatus (an ALD apparatus (demonstration unit) manufactured by JSW AFTY) via plasma ALD. P .

[0177] Specifically, similar to Experiment 1 (see...) Figure 3 By contacting one surface of the silicon substrate 10 with a 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, which had been preheated to 120°C by a heater. P Note that tEMAH (tetra(ethylmethylamino)hafnium) is used as the source gas; O2 plasma is used as the oxidant; and N2 is used as the inert gas.

[0178] <Crystallization (Modification) in Experiment 6>

[0179] In Experiment 6, similar to Experiment 5, the hafnium oxide film 20 formed on the silicon substrate 10 was irradiated with a pulsed laser irradiation device (JSW Aktina Systems excimer laser irradiation device (demonstration unit)) equipped with a KrF light source (wavelength 248nm) to the ultraviolet region. P Pulsed lasers have a wavelength of 248 nm, a pulse interval of 10 ms (100 Hz), a pulse width of tens of nanoseconds (FWHM), and a power output of 400 mJ / cm². 2 The energy density. In Experiment 6, the pulsed laser 30 K It was applied zero times (deposited state), 1 time (1 shot), 2 times (2 shots), 20 times (20 shots), and 200 times (200 shots).

[0180] Specifically, it is similar to Experiment 5 (see Figure 6 Using a pulsed laser irradiation device (an excimer laser irradiation device (demonstration unit) manufactured by JSW Aktina Systems), in a nitrogen atmosphere supplied to chamber 41, a pulsed laser 30 K The silicon substrate 10 (hafnium oxide film 20) disposed in the chamber 41 was irradiated through anhydrous quartz 42. P Chamber 41 is transported by conveyor 40 along the X (+X, -X) and Y (+Y, -Y) directions. Figure 6 Move in a direction perpendicular to the paper.

[0181] Pulsed laser 30 K The dimensions (cross-sectional dimensions) are 3mm × 3mm. Furthermore, each predetermined number of pulsed laser pulses (30) K At that time, chambers 41 were all moved, thus allowing the pulsed laser 30 to be used. K Adjacent irradiated areas do not overlap with each other. In the following text, the area formed on the silicon substrate 10 by plasma ALD and irradiated with a pulsed laser 30... K 20 irradiated hafnium oxide film PIt will be called hafnium oxide film 20 P+K .

[0182] <Results of Experiment 6>

[0183] Next, the results (evaluation results) of Experiment 6 will be described.

[0184] <Evaluation conducted using X-ray diffraction equipment>

[0185] Figure 9B This is a graph showing the X-ray diffraction pattern (results of Experiment 6). Figure 9B In the attached figure, the reference numeral G KP（0shot） A graph showing the number of irradiations (emissions) when it is zero. (Figure label G) KP（1shot） A graph showing the number of irradiations (emissions) when it is 1. (Figure label G) KP（2shot） The graph represents the number of irradiations (emissions) when it is 2. (Figure label G) KP（20shot） A graph showing the number of irradiations (emissions) when the number of irradiations is 20. (Figure label G) KP（200shot） The graph represents the number of irradiations (emissions) when the number of irradiations is 200.

[0186] Regarding the evaluation using X-ray diffraction equipment, similar to Experiment 3, X-ray diffraction equipment (Rigaku Corporation X-ray diffraction equipment) was used to evaluate the X-ray diffraction equipment as described above, which had already been subjected to pulsed laser 30. K 20 irradiated hafnium oxide film P+K The (crystal phase) was evaluated. The X-ray diffraction equipment was used under the following conditions: incident angle ω = 0.4deg.

[0187] Reference Figure 9B It should be understood that in Experiment 6, curve G... KP（1shot） G KP（2shot）和 G KP（20shot） In either of them, there is a peak near 2θ, i.e., 30.35° (2θ=30.35°).

[0188] In other words, based on the evaluation conducted using X-ray diffraction equipment, it should be understood that the amorphous hafnium oxide film 20 formed by plasma ALD method... P In this case, by selecting a wavelength of 248nm and an energy density of 400mJ / cm², 2 Or higher and with 1 to 20 pulsed lasers 30 K The hafnium oxide film 20 can suppress the crystallization (modification) of the most stable m phase. P That is, crystallization (modification) to form a hafnium oxide film mainly composed of ferroelectric o phase.

[0189] <Evaluation conducted by SEM>

[0190] Figure 10 The lower and middle rows are hafnium oxide films obtained by SEM. P+K SEM image.

[0191] Similar to Experiment 3, the hafnium oxide film 20 irradiated with the pulsed laser as described above, which was the result of Experiment 5, was examined using SEM (Scanning Electron Microscope manufactured by Hitachi High Technology Co., Ltd.). P+K The surface shape was evaluated.

[0192] Reference Figure 10 The middle and lower rows, at an energy density of 400 mJ / cm³ 2 In this case, the SEM images from 1, 2, 20, and 200 shots each include relatively bright and relatively dark areas. Therefore, at an energy density of 400 mJ / cm², 2 Under these circumstances, the hafnium oxide film 20 can be evaluated. P+K It had already coalesced during the first irradiation. This is because of the shape of the hafnium oxide film (primarily the hafnium oxide film 20 after formation). P The surface shape was not maintained, so the hafnium oxide film 20 agglomerated as described above... P+K It is not suitable as a ferroelectric material for use in non-volatile storage devices.

[0193] <Testing Experiments 5 and 6>

[0194] Experiments 5 and 6 are examples of applications using pulsed laser irradiation with a KrF light source; the energy density was fixed at 400 mJ / cm². 2 Furthermore, pulsed laser 30 was applied while varying the number of irradiations (emissions). K Furthermore, they have peaks near 2θ, i.e., 30.35° (2θ = 30.35°) (see [reference]). Figure 9A and Figure 9B ).

[0195] In the deposited state, no crystallization (amorphous) occurred in either thermal ALD (Experiment 5) or plasma ALD (Experiment 6).

[0196] In the first-shot case, crystallization was further developed in both thermal ALD (Experiment 5) and plasma ALD (Experiment 6), and a spectrum with the o phase as the dominant phase (mainly composed of the o phase) was obtained. Note that in the first-shot case, a (smaller) peak of the m phase was observed in plasma ALD (Experiment 6).

[0197] In thermal ALD (Experiment 5), even when the number of irradiations was increased to two or more, the o phase still existed.

[0198] In contrast, in plasma ALD (Experiment 6), when the number of irradiations was increased to two or more, the peak of the o-phase decreased with increasing irradiation number, and the m-phase became the dominant phase (mainly composed of the m-phase). The fact that plasma ALD depends on the number of irradiations means that the process of injecting photons into an amorphous hafnium oxide film is different from the process of injecting photons into a single-phase hafnium oxide film where the o-phase is dominant. It can be inferred that even when lattice vibrations are generated from the amorphous hafnium oxide film, the structural change cannot reach the m-phase, and the state where the o-phase is dominant still exists; however, when lattice vibrations are generated from the o-phase hafnium oxide film, the structural change reaches the m-phase, thus causing the o-phase to be replaced by the m-phase. It is not assumed that the o-phase disappears and the m-phase is generated.

[0199] Furthermore, it is speculated that the crystallization of the m phase will not develop further in the thermal ALD (Experiment 5) because the density is lower than that in the plasma ALD (Experiment 6), which makes it more unlikely (difficult) for lattice vibrations to propagate.

[0200] Regarding the confirmation of the number of irradiations and surface shape, in plasma ALD, coalescence (hafnium oxide coalescence) occurs after the first irradiation, so coalescence still exists even with increased irradiation numbers. Conversely, even with increased irradiation numbers in thermal ALD, coalescence does not further develop.

[0201] <Conditions for Modification>

[0202] Based on Experiments 1 to 6 above, the conditions for modifying the amorphous hafnium oxide film (showing paraelectricity) formed on the silicon substrate 10 into a hafnium oxide film (showing ferroelectricity) mainly composed of the o phase are as follows.

[0203] (Condition 1)

[0204] An amorphous hafnium oxide film was formed on a silicon substrate using the thermal ALD method. T Note that the hafnium oxide film 20 T The membrane thickness can be appropriately set according to the required degree of densification.

[0205] (Condition 2)

[0206] The hafnium oxide film 20 formed under the aforementioned condition 1 was irradiated with a pulsed laser in the ultraviolet region. T At this point, the energy density, wavelength, pulse interval, and pulse width of the pulsed laser are selected to achieve the desired effect on the amorphous hafnium oxide film at 20 nm. T Hafnium oxide film 20 modified to be mainly composed of the o phase T+K And no hafnium oxide film forms 20 T+KThe coalescing. An example of pulsed laser energy density, wavelength, pulse interval, and pulse width is 400 mJ / cm². 2 The energy density, wavelength of 248 nm (e.g., KrF source), pulse interval of 10 ms, and pulse width of tens of nanoseconds are all parameters that can be considered. However, these values ​​may vary. Note that when using CW lasers instead of pulsed lasers, the o-phase is not considered the dominant phase, thus the use of pulsed lasers is necessary.

[0207] As a guideline for selecting the energy density, wavelength, pulse interval, and pulse width of a pulsed laser, it is desirable to select a pulsed laser with a pulse density of 30... K The energy density, wavelength, pulse interval, and pulse width were adjusted to ensure that the hafnium oxide film obtained by X-ray diffraction was 20 μm thick. T+K The X-ray diffraction pattern of the hafnium oxide film has a peak near 2θ, i.e., 30.35° (2θ=30.35°), and the hafnium oxide film obtained by scanning electron microscopy has a peak. T+K The SEM images do not include those evaluated as hafnium oxide films. T+K The relatively bright and relatively dark parts of the aggregate.

[0208] <Effect compared with the comparative example>

[0209] Next, the effects of the embodiments will be described in comparison with those of the comparative examples.

[0210] Figure 11A A comparative example is shown. Figure 11B An example is shown.

[0211] In Comparative Example 1, the entire silicon substrate with a hafnium oxide film formed was subjected to continuous annealing. When the entire silicon substrate with a hafnium oxide film is subjected to continuous annealing, as... Figure 11A As shown, the hafnium oxide film transforms into a film comprising multiple crystalline phases, including the m-phase and the o-phase. In Figure 11A The "o, m, etc." in the text indicate this fact. As mentioned above, hafnium oxide films containing multiple crystalline phases are not suitable as ferroelectric materials for non-volatile storage devices.

[0212] Conversely, according to the method for modifying the hafnium oxide film according to the embodiment (e.g., see conditions 1 and 2 shown above), the amorphous hafnium oxide film 20 formed on the silicon substrate 10 can be modified. T Crystallization (modification) to the most stable m-phase resulted in the suppression of hafnium oxide film 20. T+K That is, crystallization (modification) to form a hafnium oxide film mainly composed of a ferroelectric o-phase 20 T+K (Additionally, no hafnium oxide film forms.) T+K (The aggregation.) This hafnium oxide film 20 T+K Suitable as a ferroelectric material for use in non-volatile storage devices.

[0213] Non-volatile storage devices

[0214] Next, an example of a non-volatile storage device will be described, using a hafnium oxide film 20 modified according to the hafnium oxide film modification method described above in the embodiment. T+K It is applied to this non-volatile storage device.

[0215] Figure 12 This is a schematic structural diagram of a non-volatile storage device M, showing a hafnium oxide film 20 modified by the hafnium oxide film modification method according to the embodiment. T+K It is applied to the non-volatile storage device M.

[0216] like Figure 12 As shown, the non-volatile memory device M includes a silicon substrate 10 and at least one ferroelectric gate transistor 50 formed on the silicon substrate.

[0217] The ferroelectric gate transistor 50 includes: a source region 51 formed on one side surface of the silicon substrate 10 and exposed therefrom; a drain region 52 formed on one side surface of the silicon substrate 10 at a location away from the source region 51 and exposed therefrom; and a hafnium oxide film 53, which is mainly composed of the o-phase (hafnium oxide film 20). T+K The components are: a source region 51 and a drain region 52, which are formed on one side surface of the silicon substrate 10; a gate electrode 54, which is formed on the hafnium oxide film 53; a source electrode 55, which is electrically connected to the source region 51 through a first contact hole H1, which is formed in the hafnium oxide film 53 in a manner corresponding to the source region 51; and a drain electrode 56, which is inserted into a second contact hole H2 and electrically connected to the drain region 52, which is formed in the hafnium oxide film 53 in a manner corresponding to the drain region 52.

[0218] Next, an example of the process for manufacturing a non-volatile storage device M having the above-described structure will be described.

[0219] Figure 13 This is an example of a flowchart for the process of manufacturing a non-volatile memory device M.

[0220] First, prepare (step S10) and clean (step S11) the silicon substrate 10. The silicon substrate 10 may be, for example, a p-type silicon substrate with a Miller index of (100).

[0221] Next, source region 51 and drain region 52 are formed on silicon substrate 10 (step S12). For example, source region 51 and drain region 52 are formed on one side surface of silicon substrate 10 by n-doping, and are exposed from that one surface. Note that annealing can be performed at this stage, or it can be omitted.

[0222] Next, using a film forming apparatus, an amorphous hafnium oxide film 20 is formed on the silicon substrate 10 by thermal ALD. T (Step S13). Specifically, the amorphous hafnium oxide film 20 T It is formed on one side surface of the silicon substrate 10 in such a way that it covers the source region 51 and the drain region 52. Amorphous hafnium oxide film 20 T The film thickness is, for example, 10 nm.

[0223] Next, the amorphous hafnium oxide film 20 was irradiated with a pulsed laser equipped with an ultraviolet light source (e.g., a KrF light source). T Crystallization (step S14). In this manner, an amorphous hafnium oxide film 20 T Hafnium oxide film 53, modified to consist mainly of the o phase (i.e., modified to consist of hafnium oxide film 20) T+K ).

[0224] Next, contact holes H1 and H2 are formed in the hafnium oxide film 53, which is mainly composed of the o phase (step S15).

[0225] Subsequently, electrode materials are stacked on the hafnium oxide film 53, which is mainly composed of the o phase (step S16), to form the source electrode, drain electrode and gate electrode (step S17).

[0226] Through the above series of processes, a non-volatile storage device can be manufactured, and the hafnium oxide film 20 modified by the hafnium oxide film modification method according to the embodiment can be used. T+K It is applied to the non-volatile storage device. Note that the hafnium oxide film modification method described above according to the embodiment is not limited to the non-volatile storage device M described above, but can also be applied to non-volatile storage devices that include a hafnium oxide film but have a different type of structure.

[0227] As described above, according to this embodiment, hafnium oxide (film) mainly composed of ferroelectric o phase can be crystallized (modified).

[0228] Although the invention made by the inventors of this application has been described in a specific manner based on embodiments, the invention is of course not limited to the above embodiments, and various modifications can be made without departing from the scope and spirit of the invention.

[0229] This application is based on and claims priority to Japanese Patent Application No. 2024-007913, filed on January 23, 2024, the entire disclosure of which is incorporated herein by reference.

[0230] List of reference numerals 10 Silicon substrate 20 Hafnium oxide film 30-pulse laser 40 Conveying mechanism 41 chambers 42 Anhydrous Quartz 50 Ferroelectric gate transistor 51 source region 52 Leakage Zones 53 Hafnium oxide film 54 gate electrode 55 Source Electrode 56 Drain electrode A1 is the area that has been irradiated with pulsed laser. A2 Area not yet irradiated by pulsed laser H1 First contact hole H2 Second Contact Hole M Non-volatile storage device

Claims

1. A method for modifying a hafnium oxide film, comprising: The film formation step involves forming an amorphous hafnium oxide film on a silicon substrate; as well as In the crystallization step, the amorphous hafnium oxide film is irradiated with a pulsed laser in the ultraviolet region, thereby modifying the amorphous hafnium oxide film into a hafnium oxide film mainly composed of the o phase, without the aggregation of the hafnium oxide film mainly composed of the o phase.

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

3. The method for modifying a hafnium oxide film according to claim 2, wherein: The pulsed laser has a wavelength of 248 nm, a pulse interval of 10 ms, and a pulse width of tens of nanoseconds.

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

5. The method for modifying a hafnium oxide film according to claim 1, wherein, The X-ray diffraction pattern of the hafnium oxide film modified by the crystallization step, obtained by X-ray diffraction equipment, has a peak near 30.35° of 2θ, i.e., 2θ = 30.35°, and... The SEM images of the hafnium oxide film modified by the crystallization step, obtained by scanning electron microscopy, do not include the relatively bright and relatively dark regions that are evaluated as agglomerations of the hafnium oxide film.

6. A non-volatile memory device comprising a silicon substrate and a hafnium oxide film formed on the silicon substrate, wherein, The hafnium oxide film is a hafnium oxide film mainly composed of the o phase, and is formed by performing the following steps: The film formation step involves forming an amorphous hafnium oxide film on the silicon substrate; and In the crystallization step, the amorphous hafnium oxide film is irradiated with a pulsed laser in the ultraviolet region, thereby modifying the amorphous hafnium oxide film into a hafnium oxide film mainly composed of the o phase, without the aggregation of the hafnium oxide film mainly composed of the o phase.

7. The non-volatile storage device according to claim 6, comprising: A source region is formed on one side surface of the silicon substrate and is exposed from the other side surface. A drain region is formed on one side surface of the silicon substrate at a location remote from the source region, while being exposed from the one side surface; A gate electrode is formed on the hafnium oxide film; A source electrode is electrically connected to the source region through a first contact hole, the first contact hole being formed in the hafnium oxide film in a manner corresponding to the source region; as well as A drain electrode, which is electrically connected to the drain region through a second contact hole formed in the hafnium oxide film in a manner corresponding to the drain region, wherein... In the film formation step, an amorphous hafnium oxide film is formed on one side surface of the silicon substrate such that the amorphous hafnium oxide film covers the source region and the drain region, and In the crystallization step, the amorphous hafnium oxide film is irradiated with a pulsed laser in the ultraviolet region, thereby modifying the amorphous hafnium oxide film into a hafnium oxide film mainly composed of the o phase, and preventing the aggregation of the hafnium oxide film mainly composed of the o phase.

Images