Method for controlling forming voltage in resistive random access memory device

Abstract

A method for controlling a forming voltage of a dielectric film in a resistive random access memory (ReRAM) device. The method includes depositing a dielectric film containing intrinsic defects on a substrate, forming a plasma-excited H2-containing process gas, and exposing the dielectric film to the plasma-excited process gas to create additional defects in the dielectric film without substantially changing a physical thickness of the dielectric film, wherein the additional defects lower the forming voltage required to create a conductive filament on the dielectric film. The dielectric film can include a metal oxide film and a microwave plasma source can be used to form the plasma-excited process gas.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to U.S. Patent Application No. 16 / 428,554, filed May 31, 2019, entitled “METHOD FOR CONTROLLING THEFORMING VOLTAGE IN RESISTIVE RANDOM ACCESS MEMORY DEVICES”, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This invention relates to semiconductor processing and semiconductor devices, and more particularly to resistive random access memory (ReRAM) devices and manufacturing methods. Background Technology

[0004] ReRAM devices are a class of memory devices that have attracted considerable attention due to the potential payout for high-density, low-cost, and low-power non-volatile memory. The basic idea behind ReRAM devices is to enable current to be conducted through a normally insulating dielectric film via filaments or conductive pathways (formed by applying a sufficiently high voltage (called the formation voltage) to the film). These pathways can be generated by various mechanisms, including vacancy or metal defect migration. Generally, the formation voltage decreases linearly with decreasing dielectric film thickness, but it is difficult to adjust the formation voltage without changing the dielectric film thickness. Furthermore, changing the dielectric film thickness may lead to other device performance issues or necessitate a switch to a different dielectric material. Therefore, a method is needed to adjust the formation voltage without significantly affecting the dielectric film thickness. Summary of the Invention

[0005] Embodiments of the present invention provide a method for controlling the formation voltage of a dielectric film through a post-deposition process. For example, the dielectric film may form part of a ReRAM device.

[0006] According to one embodiment, a method of forming a ReRAM device includes: depositing a dielectric thin film containing intrinsic defects on a substrate; forming a plasma-excited H2-containing process gas; and exposing the dielectric thin film to the plasma-excited process gas to generate additional defects in the dielectric thin film without significantly altering the physical thickness of the dielectric thin film, wherein the additional defects reduce the formation voltage required to generate conductive filaments on the dielectric thin film. In one example, the dielectric thin film comprises a metal oxide dielectric thin film and the exposure includes using a microwave plasma source to excite the process gas. In some examples, the process gas consists of H2 gas, or H2 gas and Ar gas.

[0007] According to another embodiment, a ReRAM device is described that includes a dielectric film containing intrinsic defects and additional defects that are created by exposing the dielectric film to a plasma-excited H2-containing process gas, where the additional defects are created in the dielectric film without significantly changing the physical thickness of the dielectric film, and where the additional defects lower the formation voltage required to create a conductive filament on the dielectric film. In one example, the dielectric film includes a metal oxide film that can be selected from the group consisting of Hf02, Zr02, Ti02, NiO, AI2O3, Ta2O5, and laminated films thereof. BRIEF DESCRIPTION OF DRAWINGS

[0008] The accompanying drawings incorporated in and forming a part of the specification, illustrate embodiments of the present application and, together with the general description of the application given above, and the detailed description of the application given below, serve to explain the application.

[0009] FIG. 1A and FIG. 1B A method for controlling the formation voltage of a thin film structure according to one embodiment of the present application is schematically illustrated;

[0010] FIGS. 2A-2C A method for controlling the formation voltage of a thin film structure according to another embodiment of the present application is schematically illustrated;

[0011] FIG. 3A and FIG. 3B Formation steps, reset steps, and set steps of a ReRAM device according to embodiments of the present application are illustrated;

[0012] FIG. 4 Measured formation voltages of a plasma-processed modified Hf02dielectric film in a metal-insulator-metal capacitor having an area of 10 x 10 microns according to embodiments of the present application are illustrated;

[0013] FIGS. 5-7 is an RLSA-containing TM Schematic diagram of a microwave plasma processing system with a plasma source;

[0014] FIG. 8 Electron temperature versus gap distance for a microwave plasma processing system is illustrated; and

[0015] FIG. 9 Electron density versus gap distance for a microwave plasma processing system is illustrated. DETAILED DESCRIPTION

[0016] Embodiments of the invention provide a method for controlling the formation voltage of a dielectric film by post-deposition processing of the dielectric film. For example, the dielectric film can form part of a ReRAM device that includes a stack of a first electrode film (e.g., TiN), a dielectric film, and a second electrode film (e.g., TiN). The post-deposition processing includes plasma processing of the dielectric film, where the plasma processing provides highly controllable control of the formation voltage without significantly reducing the thickness of the dielectric film or changing other important dielectric parameters. In ReRAM devices, resistance switching is controlled by the formation and disappearance of conducting filaments in the dielectric film. For metal-oxide dielectric films, the resistance switching mechanism is attributed to the displacement of charged oxygen vacancies that act as local dopants.

[0017] According to one embodiment, a method of forming a ReRAM device is described, where the method includes depositing a dielectric film containing intrinsic defects on a substrate, forming a plasma-excited H2-containing process gas, and exposing the dielectric film to the plasma-excited process gas to create additional defects in the dielectric film, where the additional defects lower the formation voltage required to create a conducting filament on the dielectric film.

[0018] According to another embodiment, the method includes depositing a dielectric film containing intrinsic defects on a substrate, forming a plasma-excited H2-containing process gas, exposing the dielectric film to the plasma-excited process gas to create additional defects in the dielectric film, and applying a formation voltage on the dielectric film to create a conducting filament.

[0019] FIG. 1A and FIG. 1B A method for controlling the formation voltage of a film structure according to one embodiment of the invention is schematically illustrated. FIG. 1AA thin film structure 1 is shown that includes a substrate 100 and a dielectric film 102 on the substrate 100. The substrate 100 can include a first electrode film (e.g., TiN) on a base material (e.g., an interlayer dielectric film). The dielectric film 102 can be deposited by vapor deposition (e.g., atomic layer deposition (ALD)) or chemical vapor deposition (CVD). The dielectric film 102 contains intrinsic defects 104 (also referred to as non-stoichiometric defects) that can be caused by ion dislocations and / or ion vacancies formed during deposition or formation of the dielectric film 102. In one example, a metal oxide dielectric film in a deposited state can include intrinsic defects such as oxygen vacancies, oxygen dislocations, or both. For example, the dielectric film 102 can include a metal oxide film selected from the group consisting of Hf02, Zr02, Ti02, NiO, Al203, Ta205, and laminated films thereof. In some examples, the dielectric film 102 can have a thickness between about 2 nm and about 20 nm, between about 2 nm and about 10 nm, between about 2 nm and about 5 nm, between about 5 nm and about 20 nm, or between about 10 nm and about 20 nm.

[0020] FIG. 1B A thin film structure 1 is shown that includes a substrate 100 and a dielectric film 102 on the substrate 100. The substrate 100 can include a first electrode film (e.g., TiN) on a base material (e.g., an interlayer dielectric film). The dielectric film 102 can be deposited by vapor deposition (e.g., atomic layer deposition (ALD)) or chemical vapor deposition (CVD). The dielectric film 102 contains intrinsic defects 104 (also referred to as non-stoichiometric defects) that can be caused by ion dislocations and / or ion vacancies formed during deposition or formation of the dielectric film 102. In one example, a metal oxide dielectric film in a deposited state can include intrinsic defects such as oxygen vacancies, oxygen dislocations, or both. For example, the dielectric film 102 can include a metal oxide film selected from the group consisting of Hf02, Zr02, Ti02, NiO, Al203, Ta205, and laminated films thereof. In some examples, the dielectric film 102 can have a thickness between about 2 nm and about 20 nm, between about 2 nm and about 10 nm, between about 2 nm and about 5 nm, between about 5 nm and about 20 nm, or between about 10 nm and about 20 nm. FIGS. 5-7 An exemplary microwave plasma source is described. The microwave plasma source generates a plasma having a low electron temperature and a high electron density to efficiently introduce additional defects 108 into the dielectric film 102 without significantly changing the thickness of the dielectric film 102 or causing severe damage to the dielectric film 102. The microwave plasma is thus well suited for highly controllable introduction of additional defects 108 into the dielectric film 102. According to another embodiment, a capacitively coupled plasma (CCP) source or an inductively coupled plasma (ICP) source can be used for plasma excitation.

[0021] In some examples, the plasma exposure of the dielectric film 102 can be performed at a substrate temperature of about 200 °C or greater, such as between about 200 °C and about 500 °C, between about 200 °C and about 300 °C, between about 300 °C and about 400 °C, between about 300 °C and about 500 °C, between about 400 °C and about 500 °C. In one example, the substrate temperature can be about 400 °C.

[0022] According to one embodiment, during the plasma exposure, the processing conditions can include a substrate temperature of about 400 °C, a processing chamber pressure of about 0.95 Torr, and a microwave power of about 1700 W.

[0023] According to one embodiment, the deposition of the dielectric film and the post-deposition treatment can be performed by interrupting the deposition of the dielectric film at least once and performing a plasma exposure before continuing the deposition of the dielectric film. This is schematically shown in FIGS. 2A-2C .

[0024] FIGS. 2A-2C A method for controlling the formation voltage of a thin film structure according to one embodiment of the present application is schematically shown. The thin film structure 2 is similar to the thin film structure 1 in FIG. 1A and includes a substrate 200 and a dielectric film 202 deposited on or formed on the substrate 200. The substrate 200 can include a first electrode film (such as TiN) on a base material (such as an interlayer dielectric film). The dielectric film 202 can be thinner than the dielectric film 102 in FIG. 1A and contains intrinsic defects 204. For example, the dielectric film 202 can include a high-k metal oxide selected from the group consisting of Hf02, Zr02, Ti02, NiO, AI2O3, Ta2O5, and laminated films thereof. In some examples, the thickness of the dielectric film 202 can be between about 1 nm and about 10 nm, between about 2 nm and about 10 nm, between about 2 nm and about 5 nm, between about 5 nm and about 10 nm, or between about 5 nm and about 20 nm.

[0025] FIG. 2BA thin film structure 2 is shown with a gaseous exposure to a plasma excited process gas 206. In some examples, the process gas 206 can contain or consist of H2gas, or H2gas and an inert gas such as Ar. The plasma exposure introduces additional defects 208 into the dielectric thin film 202 without significantly changing the physical thickness of the dielectric thin film 202. The resulting dielectric thin film 202 contains intrinsic defects 204 and additional defects 208. Additionally, when only H2gas, or H2gas and Ar gas is used, only H2(or H), or H2(or H) and Ar are introduced into the dielectric thin film 102 by the plasma exposure. The plasma exposure and the reduction in the formation voltage are highly controllable and the process conditions (such as plasma source power, exposure time, and substrate temperature) can be selected such that a controllable amount of additional defects 208 are introduced into the dielectric thin film 202. According to one embodiment, a microwave plasma source can be used for the plasma excitation. According to another embodiment, a CCP source or an ICP source can be used for the plasma excitation.

[0026] FIG. 2C A thin film structure 2 is shown after an additional dielectric thin film 210 is deposited on the dielectric thin film 202, where the additional dielectric thin film 210 contains intrinsic defects 212. In one example, the additional dielectric thin film 210 can contain a similar dielectric material as the dielectric thin film 202. In another example, the additional dielectric thin film 210 can contain a different dielectric material than the dielectric thin film 202. According to one embodiment, an additional plasma exposure on the additional dielectric thin film 210 introduces additional additional defects in the additional dielectric thin film 210.

[0027] FIG. 3A and FIG. 3B Formation steps, reset steps, and set steps of a ReRAM device according to embodiments of the present application are shown. FIG. 3A Experimental results of forming a conductive filament in a dielectric thin film of a ReRAM device are shown. In the formation step, the initial leakage current through the ReRAM stack is low, but as the bias voltage applied on the dielectric thin film is increased, the leakage current suddenly increases. The leakage current reaches a compliance current set by an external device (such as a transistor). In the reset step, the conductive filament is removed and the device is converted to a high resistance state. In the set step, the conductive filament is formed again and the device is converted to a low resistance state. In the formation step, the conductive filament is formed and the device is converted to a low resistance state. During a subsequent voltage scan towards the opposite polarity, a transition to a high resistance state occurs at a certain threshold voltage, as shown in FIG. 3A In one example, the compliance current is about 100 μΑ.

[0028] FIG. 3B Experimental results of reset steps and set steps of a ReRAM device are shown. In the formation step of FIG. 3A the conductive filament is formed and the device is converted to a low resistance state. During a subsequent voltage scan towards the opposite polarity, a transition to a high resistance state occurs at a certain threshold voltage, as shown in FIG. 3BThe operation is called reset and it destroys the filament. Then, by scanning toward the opposite polarity voltage, the device resistance state is switched from reset to low resistance state. This operation is called set. The applied bias required in the set step is less than that required in the formation step because the set step does not need to create the entire filament, only to reestablish the connection.

[0029] FIG. 4 The measured formation voltage of plasma treated modified HfO2dielectric films according to embodiments of the present application is shown. All HfO2dielectric films were about 5 nm thick and the metal-insulator-metal capacitor area was 10 x 10 microns. For HfO2dielectric films, when oxygen vacancies line up in the HfO2dielectric film, intrinsic defects and additional defects introduced by post-deposition treatment form a conducting filament and the formation voltage is strongly affected by the total number of intrinsic defects and additional defects.

[0030] In FIG. 4 , HfO2dielectric films 102, 104, 106, and 108 were treated by the method described in FIG. 1A and FIG. 1B , and HfO2dielectric films 101 and 103 were treated by the method described in FIGS. 2A-2C . HfO2dielectric films were deposited at a substrate temperature of about 3000C using alternating gas exposures of Hf(NEtMe)4and H2O in a thermal ALD process.

[0031] HfO2dielectric film 100 was a reference sample in as-deposited state without post-deposition treatment and its measured formation voltage was about 3.4 V. HfO2dielectric films 102 to 108 were exposed to a microwave plasma excited treatment gas consisting of H2gas and Ar gas. The plasma exposure of HfO2dielectric films 102, 104, 106, and 108 was 30 sec, 40 sec, 50 sec, and 60 sec, respectively. The measured formation voltage of HfO2dielectric films 102 to 108 monotonically decreased from about 3.1 V to about 2.85 V.

[0032] HfO2dielectric film 101 was prepared by depositing a first HfO2dielectric film of 4 nm on a substrate, exposing the first HfO2dielectric film to a microwave plasma excited process gas consisting of H2gas and Ar gas for 30 sec, and thereafter depositing an additional second HfO2dielectric film of 1 nm on the first HfO2dielectric film. HfO2dielectric film 103 was prepared by depositing a first HfO2dielectric film of 2 nm on a substrate, exposing the first dielectric HfO2material to a microwave plasma excited process gas consisting of H2gas and Ar gas for 30 sec, and thereafter depositing an additional second HfO2dielectric film of 3 nm on the first HfO2dielectric film. After the plasma treatment and deposition of the second HfO2dielectric film, the measured formation voltage of HfO2dielectric films 101 and 103 were about 3.0 V and about 2.8 V, respectively.

[0033] FIG. 4 The experimental results show that the formation voltage of a 5 nm thick HfO2dielectric film is controllably reduced from about 3.4 V to about 2.8 V using plasma exposure between 30 sec and 60 sec. In addition, interrupting the deposition of the HfO2dielectric material when the first HfO2dielectric film reaches an initial thickness, plasma exposing the first HfO2dielectric film, and depositing a second HfO2dielectric film until a desired thickness (i.e., 5 nm) is reached more effectively reduces the formation voltage. It was observed that the thinner the first HfO2dielectric film, the more effectively the formation voltage is reduced.

[0034] Secondary ion mass spectroscopy (SIMS) depth profiling of the plasma treated HfO2dielectric films showed a significant increase in hydrogen (H) concentration compared to the reference sample.

[0035] The effect of substrate temperature in the plasma treatment showed that substrate temperatures above about 300 °C more effectively reduced the formation voltage of the HfO2dielectric film than temperatures at or below about 300 °C. For example, a substrate temperature of about 350 °C was more effective than a substrate temperature of about 300 °C, and a substrate temperature of about 400 °C was more effective than a substrate temperature of about 350 °C.

[0036] FIGS. 5-7 RLSA TM Schematic diagram of a microwave plasma processing system (available from Tokyo Electron Limited, Akasaka, Japan) of a plasma source. As FIG. 5As shown, the plasma processing system 10 includes a plasma processing chamber 20 (vacuum chamber), an antenna unit 50, and a substrate holder 21. Inside the plasma processing chamber 20 is generally divided into a plasma generation region Rl below the plasma gas supply unit 30, and a plasma diffusion region R2 above the substrate holder 21. The electron temperature of the plasma generated in the plasma generation region Rl can be several electron volts (eV). When the plasma is diffused to the plasma diffusion region R2 (where film processing is performed), the electron temperature of the plasma near the substrate holder 21 can drop to a value between about 1 eV and about 2 eV. FIG. 8 It is shown that this low electron temperature is a function of the gap distance between the process gas supply unit 40 and the substrate holder 21. Furthermore, as FIG. 9 It is shown that the electron density in the plasma diffusion region R2 is greater than about 1.0E+12 cm -1 .

[0037] The substrate holder 21 is located in the center of the bottom of the plasma processing chamber 20 and supports a substrate W as a substrate holder. Inside the substrate holder 21, an insulating member 21a, a cooling jacket 21b, and a temperature control unit (not shown) for controlling the temperature of the substrate are provided.

[0038] The top of the plasma processing chamber 20 is open. The plasma gas supply unit 30 is placed relative to the substrate holder 21 and attached to the top of the plasma processing chamber 20 via a sealing member such as an O-ring (not shown). The plasma gas supply unit 30 (which can also function as a dielectric window) can be made of an alumina or quartz material and has a flat surface. A plurality of gas supply holes 31 opposite the substrate holder 21 are provided on the flat surface of the plasma gas supply unit 30. The plurality of gas supply holes 31 are in communication with a plasma gas supply port 33 through a gas flow passage 32. A plasma gas supply source 34 provides plasma gas (such as Ar gas, H2 gas, or both Ar and H2, or other gases) to the plasma gas supply port 33. The plasma gas is then uniformly provided to the plasma generation region Rl via the plurality of gas supply holes 31.

[0039] The plasma processing system 10 further includes a process gas supply unit 40 located at a central position between the plasma generation region Rl and the plasma diffusion region R2 of the plasma processing chamber 20. The process gas supply unit 40 can be made of an electrically conductive material (such as an aluminum alloy including magnesium (Mg) or stainless steel). Similar to the plasma gas supply unit 30, a plurality of gas supply holes 41 are provided on a flat surface of the process gas supply unit 40. The flat surface of the process gas supply unit 40 is opposite the substrate holder 21.

[0040] The plasma processing chamber 20 further includes an exhaust line 26 connected to the bottom of the plasma processing chamber 20, a vacuum line 27 connecting the exhaust line 26 to a pressure control valve 28 and a vacuum pump 29. The pressure control valve 28 can be used to achieve a desired gas pressure in the plasma processing chamber 20.

[0041] FIG. 6 A top view of the process gas supply unit 40 is shown. As shown in this view, a grid-shaped gas flow passage 42 is formed in the process gas supply unit 40. The grid-shaped gas flow passage 42 communicates with the upper ends of a plurality of gas supply holes 41 formed in the vertical direction. The lower portions of the plurality of gas supply holes 41 are openings facing the substrate holder 21. The plurality of gas supply holes 41 communicate with a process gas supply port 43 via the grid-shaped gas flow passage 42.

[0042] In addition, a plurality of openings 44 are formed in the process gas supply unit 40 such that the plurality of openings 44 pass through the process gas supply unit 40 in the vertical direction. The plurality of openings 44 introduce a plasma gas (such as Ar, H2, or other gas) to a plasma diffusion region R2 on the substrate holder 21. As shown, the plurality of openings 44 are formed between adjacent gas flow passages 42. Process gases can be supplied to the process gas supply port 43 from three independent process gas supply sources 45 to 47. The process gas supply sources 45 to 47 can supply H2 gas, N2 gas, and Ar gas. FIG. 6

[0043] The process gas flows through the grid-shaped gas flow passage 42 and is uniformly supplied to the plasma diffusion region R2 via the plurality of gas supply holes 41. The plasma processing system 10 further includes four valves (V1-V4) and four mass flow controllers (MFC1-MFC4) for controlling the supply of process gases.

[0044] The external microwave generator 55 provides microwaves of a predetermined frequency to the antenna unit 50 via a coaxial waveguide 54. The coaxial waveguide 54 can include an inner conductor 54B and an outer conductor 54A. The microwaves from the microwave generator 55 create an electric field just above the plasma gas supply unit 30 in the plasma generation region Rl, which in turn causes excitation of the process gas within the plasma processing chamber 20. For example, the microwave power can be between about 0.5 W / cm 2 and about 4 W / cm 2 Alternatively, the microwave power can be between about 0.5 W / cm 2 and about 3 W / cm 2 The microwave radiation can include a microwave frequency of about 300 MHz to about 10 GHz, for example 2.45 GHz.

[0045] FIG. 7 ​A partial cross-sectional view of the antenna unit 50 is shown. As shown in this view, the antenna unit 50 can include a planar antenna body 51, a radiating slot plate 52, and a dielectric plate 53 for shortening the wavelength of microwaves. The planar antenna body 51 can be circular with an open bottom surface. The planar antenna body 51 and the radiating slot plate 52 can be made of a conductive material.

[0046] A plurality of slots 56 are provided on the radiating slot plate 52 to generate a circularly polarized wave. The plurality of slots 56 are arranged in a substantially T-shape with a small gap between each slot. The plurality of slots 56 are arranged in a concentric circular pattern or a spiral pattern in a circumferential direction. Since the slots 56a and 56b are perpendicular to each other, a circularly polarized wave containing two orthogonal polarization components is radiated as a plane wave from the radiating slot plate 52.

[0047] The dielectric plate 53 located between the radiating slot plate 52 and the planar antenna body 51 can be made of a low-loss dielectric film such as aluminum oxide (AI2O3) or silicon nitride (Si3N4). A sealing member (not shown) can be used to mount the radiating slot plate 52 on the plasma processing chamber 20 such that the radiating slot plate 52 is in close contact with the cover plate 23. The cover plate 23 is located on the upper surface of the plasma gas supply unit 30 and is formed of a microwave-transmissive dielectric film such as aluminum oxide (AI2O3).

[0048] The external high-frequency power source 22 is electrically connected to the substrate holder 21 via a matching network 25. The external high-frequency power source 22 generates RF bias power of a predetermined frequency (e.g., 13.56 MHz) for controlling the energy of ions in the plasma that are attracted to the substrate W. The power source 22 is further configured to optionally provide pulses of RF bias power. The pulse frequency can be higher than 1 Hz, e.g., 2 Hz, 4 Hz, 6 Hz, 8 Hz, 10 Hz, 20 Hz, 30 Hz, 50 Hz, or higher. The power source 22 is configured to provide RF bias power between 0 W and 100 W, between 100 W and 200 W, between 200 W and 300 W, between 300 W and 400 W, or between 400 W and 500 W. Those skilled in the art will appreciate that the power level of the power source 22 is related to the size of the substrate being processed. For example, a 300 mm Si wafer requires higher energy consumption than a 200 mm wafer during processing. The plasma processing system 10 further includes a DC voltage generator 35 that can supply a DC bias between -5 kV and +5 kV to the substrate holder 21.

[0049] A number of embodiments have been described for controlling the forming voltage of a ReRAM device by plasma exposure to a process gas. The foregoing description of embodiments of the application has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the application to the precise form disclosed. The description and figures are intended to be illustrative, and not restrictive. Many modifications and variations are possible in light of the above teachings. It is intended that the scope of the application be limited not with this specific embodiment but rather by the claims appended hereto.

Claims

1. A method for forming a resistive random access memory (ReRAM) device, the method comprising: depositing a dielectric film containing intrinsic defects on a substrate; forming a plasma-excited H2-containing process gas; and exposing the dielectric film to the plasma-excited process gas to create additional defects in the dielectric film, wherein the additional defects lower the formation voltage required to create a conductive filament on the dielectric film; and the method further comprising: depositing an additional dielectric film on the dielectric film after exposing the dielectric film to the plasma-excited process gas, the additional dielectric film containing intrinsic defects; and exposing the additional dielectric film to an additional plasma-excited H2-containing process gas to create additional defects in the additional dielectric film.

2. The method of claim 1, wherein, Exposing the dielectric film to the plasma-excited process gas does not significantly change the physical thickness of the dielectric film.

3. The method of claim 1, wherein, The dielectric film comprises a metal oxide film selected from the group consisting of Hf02, Zr02, Ti02, NiO, AI2O3, Ta2Os, and laminated films thereof.

4. The method of claim 1, wherein, The forming a plasma-excited process gas comprises exciting the process gas using a microwave plasma source.

5. The method of claim 1, wherein, The process gas consists of H2 gas, or H2 gas and Ar gas.

6. A method for forming a resistive random access memory (ReRAM) device, the method comprising: depositing a metal oxide dielectric film on a substrate, the metal oxide dielectric film containing intrinsic defects comprising oxygen vacancies; forming a plasma-excited H2-containing process gas, wherein the forming comprises exciting the process gas using a microwave plasma source; and exposing the metal oxide dielectric film to the plasma-excited process gas to create additional defects in the metal oxide dielectric film without significantly changing the physical thickness of the metal oxide dielectric film, wherein the additional defects lower the formation voltage required to create a conductive filament on the metal oxide dielectric film; and the method further comprising: depositing an additional metal oxide dielectric film on the metal oxide dielectric film after exposing the metal oxide dielectric film to the plasma-excited process gas, the additional metal oxide dielectric film containing intrinsic defects; exposing the additional metal oxide dielectric film to an additional plasma-excited H2-containing process gas to create additional defects in the additional metal oxide dielectric film.

7. The method of claim 6, wherein, The metal oxide film is selected from the group consisting of Hf02, Zr02, Ti02, NiO, AI2O3, Ta2Os, and laminated films thereof.

8. The method of claim 6, wherein, The process gas consists of H2, or H2 and Ar.

9. The method of claim 6, wherein, The substrate comprises a first electrode film on a base material, the method further comprising: forming a second electrode film on the metal oxide dielectric film.

10. A resistive random access memory (ReRAM) device, comprising: A dielectric film on a substrate, the dielectric film containing intrinsic defects and additional defects, the additional defects being produced by exposing the dielectric film to a plasma-excited H2-containing process gas, wherein the additional defects are produced in the dielectric film without substantially changing the physical thickness of the dielectric film, and wherein the additional defects lower the formation voltage required to produce a conductive filament on the dielectric film; and The device further comprises: An additional metal oxide dielectric film on the metal oxide dielectric film; Wherein the additional metal oxide dielectric film contains intrinsic defects and additional defects, the additional defects being produced by exposing the additional metal oxide dielectric film to an additional plasma-excited H2-containing process gas.

11. The device of claim 10, wherein, The dielectric film comprises a metal oxide film selected from the group consisting of HfO2, ZrO2, TiO2, NiO, Al2O3, Ta2O5, and laminated films thereof.

12. The device of claim 10, wherein, The process gas consists of H2 gas, or H2 gas and Ar gas.

13. The device of claim 10, wherein, The substrate comprises a first electrode film on a base material and the device further comprises a second electrode film on the dielectric film.

14. The device of claim 10, wherein, A microwave plasma source is used to excite the plasma-excited process gas. A microwave plasma source is used to excite the plasma-excited process gas.

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