Plasma-Enhanced Chemical Vapor Deposition for Structurally Complex Substrates

Abstract

The substrate includes a first outer surface, a second outer surface opposite the first outer surface, and a region having a volume extending from the first outer surface to the second outer surface. At least a part of the volume of this region defines voids at interstitial positions, the interstitial positions being defined by walls having surfaces, the surfaces including a plasma-forming deposition layer.

Description

Technical Field

[0001] The present disclosure relates to plasma-enhanced chemical vapor deposition for structurally complex substrates.

Background Art

[0002] The description of the background art provided herein is for the purpose of generally presenting the content of the present disclosure. The research of the inventors, now named, is not admitted as prior art to the present disclosure, either explicitly or implicitly, to the extent that it may not be eligible as prior art at the time of filing in the same manner as the aspects of the description that are described in this background art section.

[0003] Chemical vapor deposition (CVD) is often used in the manufacture of microtechnology and nanotechnology. For example, CVD can be used in the manufacture of integrated circuits and optoelectronic devices. During the CVD manufacturing process, desired species are generated by chemical reactions, and those species are deposited on a substrate. Although homogeneous reactions (i.e., gas-phase reactions) can occur before the gas molecules reach the substrate, generally, modern techniques require heterogeneous reactions to occur on the surface of the substrate. This process forms a solid at the reaction site (i.e., on the surface of the substrate), resulting in the deposition of a solid on the substrate.

Summary of the Invention

Means for Solving the Problems

[0004] This section provides a general overview of the present disclosure and is not an all-inclusive disclosure of its full scope or all of its features.

[0005] One aspect of the present disclosure provides a method of depositing a material on a substrate. The substrate has a first outer surface, a second outer surface opposite the first outer surface, and a thickness portion extending between the first outer surface and the second outer surface. The substrate includes a charge-neutral ion deposition state within the volume of the thickness portion. The method of depositing a material on the substrate includes doping the substrate with plasma to generate a charged ion deposition state in the substrate. The charged ion deposition state has a non-zero electric field within the volume of the thickness portion. The method further includes depositing ions on the plasma-doped substrate at one or more interstitial positions within the volume of the thickness portion.

[0006] In some examples, doping the substrate with plasma may include exposing the substrate to nuclear radiation. In some implementations, doping the substrate with plasma is performed using a particle-based ionization mechanism, and depositing ions on the plasma-doped substrate is performed using an electrically generated plasma in a chemical vapor deposition chamber. In some examples, doping the substrate with plasma uses an ionization mechanism initiated by charged particles. In these examples, the charged particles may be alpha particles or the charged particles may be beta particles. In some examples, doping the substrate with plasma uses an ionization mechanism initiated by photons. The ionization mechanism initiated by photons may be performed using gamma radiation. In some configurations, in the charged deposition state, the substrate is in a state of radioactive decay.

[0007] In some examples, the method further provides that depositing on a substrate doped with plasma is performed in a plasma enhanced chemical vapor deposition reactor, and doping the substrate with plasma to create a charged ion deposition state is performed outside the plasma enhanced chemical vapor deposition reactor. Depositing ions on a substrate doped with plasma may include supplying a source gas into a chamber containing the substrate doped with plasma, and applying a voltage to a high frequency electrode for a predetermined time period. The predetermined time period may correspond to the deposition rate of ions at one or more interstitial positions within the volume of the substrate. The substrate may include a set of voids each defined by an aperture greater than about 10 microns.

[0008] Another aspect of the present disclosure provides a substrate including a first outer surface, a second outer surface opposite the first outer surface, and a region having a volume extending from the first outer surface to the second outer surface. At least a portion of the volume of this region defines voids at interstitial positions, the interstitial positions being defined by walls having surfaces, and the surfaces including a plasma-forming deposition layer.

[0009] The plasma-forming deposition layer may be formed by a plasma disposed within the voids, the plasma having an ionization state initiated by charged particles. The charged particles can be alpha particles or beta particles. The plasma-forming deposition layer may be formed by a plasma disposed within the voids. Here, the plasma disposed within the voids may have an ionization state initiated by photons or by gamma radiation. The voids at the interstitial positions may be defined by apertures greater than about 10 microns.

[0010] The present disclosure further provides a system including a chamber, an electrode, and a plasma doping substrate. The chamber has a source gas inlet port and an exhaust outlet port. The electrode is electrically coupled to a voltage source. The plasma doping substrate faces the electrode. The plasma doping substrate has a first outer surface, a second outer surface opposite the first outer surface, and a region having a volume extending from the first outer surface to the second outer surface, wherein at least a portion of the volume defines a cavity at an interstitial position, and further includes a plasma disposed within the cavity.

[0011] In some examples, charged particles initiate an ionization state that defines a plasma. The charged particles can be alpha particles. The charged particles can be beta particles. In some implementations, photons initiate an ionization state that defines a plasma. In some configurations, gamma radiation initiates an ionization state that defines a plasma. The cavity at the interstitial position can be defined by an aperture greater than about 10 microns.

[0012] The present disclosure also provides a system including a plurality of plasma cells. Each plasma cell includes a plasma formed from a non-reactive gas species, a first wall, a second wall facing the first wall, a third wall extending between the first wall and the second wall, and a fourth wall facing the third wall and extending between the first wall and the second wall. The third wall has a voltage equal to the potential of the plasma. The fourth wall has a second voltage lower than the potential of the plasma. The first wall and the second wall form a first pair of opposing walls that are electrically insulated and grounded. The plasma occupies the volume of each plasma cell between each of the first wall, the second wall, the third wall, and the fourth wall. The plurality of plasma cells are stacked in a configuration such that all of the third walls are on the same side as the stack while facing all of the fourth walls on the opposite side of the stack.

[0013] In some implementations, the configuration of all the third walls facing the same side of all the fourth walls aligns all the third walls in a straight line. This configuration may form a first terminal configured to maintain a first voltage in parallel with each third wall of a plurality of plasma cells. This configuration may also form a second terminal configured to receive a second voltage and supply the second voltage in parallel to each fourth wall of the plurality of plasma cells. In some examples, the plasma is formed from a non-reactive gas species by charged particle ionization. At least one of the first voltage or the second voltage may be selectively applied. Selectively applying at least one of the first voltage or the second voltage may selectively apply a resultant force on the system.

[0014] The present disclosure will be more fully understood from the following detailed description in conjunction with the accompanying drawings.

Brief Description of the Drawings

[0015]

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[0016] In the drawings, reference numbers may be reused to identify similar and / or identical elements.

[0017] Plasma-enhanced chemical vapor deposition Chemical vapor deposition (CVD), or the process of chemically depositing gas species onto a substrate, can have many forms or variations. Each type of CVD (i.e., variation) may be characterized by operating conditions (e.g., at atmospheric pressure, low pressure, ultra-high vacuum pressure, etc.), type of gas (e.g., aerosol-assisted or direct injection), and / or activation means. Activation refers to the initiation of a reaction that results in deposition on the substrate. In this sense, the activation energy corresponds to the input energy that drives or catalyzes the reaction that results in deposition. Generally speaking, many of the variations of CVD use heat as the activation energy. For example, these variations may use a hot-wall CVD reactor (e.g., surrounded by a furnace), or a cold-wall reactor in which the substrate itself is heated.

[0018] However, there are limitations to using heat as the activation energy for CVD. The heat used in the CVD process may require a large heat load and / or energy consumption to perform the deposition. For example, when using a cold-wall reactor where CVD heats the substrate to promote deposition, the substrate needs to be thermally stable at the desired temperature. This means that the type of substrate that can be used for cold-wall reactor CVD is limited to substrates that are not deformed (i.e., thermally stressed) by the heat applied to activate the CVD process. Additionally, the substrate may have temperature non-uniformities based on heat transfer (e.g., heat transfer rate) and the structure of the substrate, causing the possibility of non-uniform deposition (i.e., coating thickness) from the CVD process.

[0019] Alternatively, some types of CVD use plasma (e.g., ionized gas) rather than heat as the activation energy source. These CVD variants are called plasma-based CVD or plasma-enhanced CVD (PECVD). By utilizing plasma as the activation energy source instead of thermal energy, PECVD can be performed at lower temperatures than heat-based CVD. This means that, for example, PECVD may not require a high-temperature furnace and can thus be used with temperature-sensitive substrates that cannot withstand and / or would otherwise be damaged by high-temperature CVD. For example, PECVD can be performed at temperatures in the range from room temperature (e.g., 10 to 30 degrees Celsius) to several hundred degrees Celsius (e.g., 200 to 400 degrees Celsius) such that the actual temperature of the gas and ions in the plasma can be approximately the same.

[0020] Here, plasma refers to the fourth state of matter. In the fourth state of matter, namely the "plasma state", electrons are dissociated from atoms to form an ionized gas. Referring to FIGS. 1 and 2, the environment 100 shows the plasma 10 occupying the chamber 20. The behavior of the plasma 10 can vary at different positions within the chamber 20. For purposes of illustration, the plasma 10 is shown as having a bulk region 10a (also referred to as the bulk 10a) and a sheath region 10b (also referred to as the sheath 10b). The bulk 10a may be disposed between the sheaths 10b and / or in other cases may be surrounded by the sheaths 10b. In the bulk 10a, the plasma 10 can be charge-neutral in that the number of ions and the number of electrons are relatively the same. In contrast, the sheath 10b refers to a region along the boundary of the shape containing the plasma 10 (e.g., the shape of the chamber 20). In other words, in FIGS. 1 and 2, the sheath 10b is the boundary near the wall 22 of the chamber 20.

[0021] As shown in the example of FIG. 1, the sheath 10b can contain excess ions represented by "+" that generate a positive charge density and a positive potential. This results in an electric field that points towards or is directed towards the adjacent wall 22. For example, in the first sheath 10b1 shown on the left side of the bulk 10a, the electric field points towards the left wall 22a of the chamber 20. Similarly, in the second sheath 10b2 shown on the right side of the bulk 10a, the electric field points towards the right wall 22b of the chamber 20. At the positive potential where the electric field is directed towards each adjacent wall 22, the ions of the plasma 10 are accelerated in the direction of the electric field towards the wall 22. As an example, FIG. 2 shows, in an enlarged view, the ions within the sheath 10b2 as having an acceleration in the direction of the arrow towards the wall 22b.

[0022] The width w of the sheath 10b can vary according to the overall charge density of the plasma 10 and / or the voltage applied to the wall 22. For example, as the voltage applied to the wall 22 increases, the width w of the sheath 10b can increase (e.g., increase proportionally at a certain ratio). In contrast, the overall charge density of the plasma 10 and the width w of the sheath 10b can have an inverse relationship. That is, as the charge density increases, the width w of the sheath 10b can decrease. Here, the charge density refers to the number of charged particle species (e.g., ions) per unit volume of the chamber 20. The sheath width w can be from several tens of microns (i.e., micrometers) to several hundreds of microns (e.g., 10 μm, 50 μm, 100 μm, 200 μm, 500 μm, etc.).

[0023] Based on the above, PECVD can manipulate the electric field to promote (i.e., cause) the deposition of ions onto the substrate. Figure 2 is an example of this concept. In this example, the electric field accelerates the ions towards the wall 22. Here, the wall 22 can refer to a boundary such as the surface of a substrate (e.g., the substrate 130 in Figure 3) configured to receive the deposition of precursor materials supplied to the PECVD reactor. Due to the acceleration caused by the electric field, the ions may neutralize with electrons at the wall 22. Thereby, atoms are embedded (i.e., adhered) onto the surface through a chemical reaction (i.e., ion deposition) in which the residual energy is dissipated as heat. For example, Figure 2 shows ions 12 chemically adhered to the surface. Regarding electrons, higher-energy electrons overcome the repulsive force of the electric field based on their kinetic energy, resulting in these electrons contacting the wall 22. The wall 22 dissipates the excess energy from the contact between the electrons and the wall 22 as heat.

[0024] FIG. 3 is an example of a PECVD reactor 100a as the environment 100. In terms of deposition, a reactor broadly refers to a device that hosts a chemical reaction that results in deposition on a substrate. Here, the reactor 100a includes a chamber 110 defined by a wall 112 that encloses a certain volume of space. The chamber 110 includes an inlet port 114 through which a source gas (e.g., one or more precursor materials) is supplied into the chamber 110, and an outlet port 116 through which a product or gas is discharged from the chamber 110 (e.g., after the deposition process is complete). Depending on the desired deposition, the precursor material or source gas may be one or more gases (e.g., provided by a tank in fluid communication with the inlet port 114) that react to form a deposition layer 120 on the substrates 130, 130a.

[0025] Regarding PECVD, the source gas is excited within the chamber 110 to become a plasma 10 (e.g., an ionized gas). In some configurations, the plasma is electrically generated from the source gas. For example, FIG. 3 shows that the source gas is ionized in response to high-frequency (RF) electrodes 140, 140a. In other words, the reactor 100a is configured to include an electrode system 140 having an RF electrode 140a that oscillates at a high frequency to excite the atoms of the source gas to form the plasma 10. In this configuration, the source gas is supplied into the chamber 110, and a voltage is applied to the RF electrode 140a to ionize the source gas within the chamber 110. The substrate 130 typically sits on another electrode 140, 140b (e.g., a platen or a ground electrode) within the chamber 110, and a sheath 10b of the plasma 10 is formed along with an electric field adjacent to the substrate 130 to facilitate a chemical reaction that deposits the deposition layer 120 on the surface of the substrate 130.

[0026] In some exemplary configurations, an electrical ground 150, a voltage source 152 (e.g., an RF voltage source), and / or a capacitor 154 (e.g., a blocking capacitor) can be electrically connected to the electrode system 140 (see, for example, FIGS. 3-5). The electrical ground 150 can be disposed between the RF electrode 140a and the voltage source 152. The voltage source 152 can be disposed between the electrical ground 150 and the capacitor 154. The capacitor 154 can be disposed between the voltage source 152 and the electrode 140b.

[0027] The thickness of the deposition layer 120 can be controlled by ionizing the source gas over a specified period. In other words, the chemical reaction results in a deposition rate that can control the deposition time and thus control the thickness of the deposition layer 120. For example, controlling the time period during which the voltage source 152 is applied to generate electricity for plasma controls the length of time during which deposition occurs on (or within) the substrate 130. In FIG. 3, the deposition layer 120 is shown as a layer on the surface of the substrate 130 facing the RF electrode 140a.

[0028] PECVD has been used in thin film and two-dimensional (2D) applications. That is, this process cannot form the deposition layer 120 on any surface of the substrate 130a other than the outer surface. For example, referring to FIG. 3, ion deposition by the PECVD reactor 100a is effective when the surface of the substrate 130a faces the electric field directly. This means that even if the substrate 130 can have a more complex structure such as a three-dimensional shape (shown in FIGS. 4 and 5), the surfaces of that structure that do not face the electric field do not receive the deposition layer 120. In the case of an electrically single topology with no electric field within its volume, there can be no electrically generated plasma within that volume.

[0029] In conventional PECVD, the drive electrode 140 (e.g., an RF electrode) has a predetermined voltage. Due to the drive voltage, the substrate 130 within the electrode system 140 can have the same predetermined voltage across all surface regions. An electric field between the immediate surface of the substrate 130 facing the reference electrode 140a and the reference electrode 140a can generate the plasma 10. Any internal cavities or inter-lattice gaps 132 of the substrate 130, particularly of a 3D substrate (e.g., substrates 130, 130b), form an equipotential surface (i.e., the voltage is constant and the electric field is zero), lacking an electric field for generating plasma within the volume of the substrate, which hinders the ability to deposit ions (generated by the plasma) on the surfaces within the volume of the substrate 130. This means that a complex substrate 130 can have cavities or inter-lattice gaps 132, 132a~n defined by the surface regions of the substrate that can receive the deposition layer, but the surface regions defining these inter-lattice gaps 132 remain uncoated from conventional PECVD.

[0030] For illustration purposes, FIG. 4 shows substrates 130, 130b as a material having a thickness portion t with lattice gaps 132a - n throughout the volume of the thickness portion t. This structurally complex substrate 130b can be any 3D substrate (i.e., micro - material and macro - material) that includes voids (i.e., openings) for its lattice gaps 132 that are larger than about 10 microns. For example, these lattice gaps 132a - n are shown as a repeating lattice pattern of five chambers arranged in an X - shape to form a material matrix. Here, each chamber or lattice gap 132 can be at least partially defined by a wall surface area that can receive a deposition layer. Further, if the voltage across the outer surface region of the substrate 130b is uniform, there may be no gradient voltage potential across the thickness portion of the 3D material, and as a result, there is no charge density within the substrate 130b. According to Gauss's law of electrostatics, if there is no charge density inside the substrate 130, there can be no electric field within that substrate 130. Without an electric field, the ion deposition process of PECVD cannot occur within the volume of the substrate 130. In other words, there is no transfer medium for accelerating ions to the surface regions within the substrate (e.g., the walls forming the lattice gaps 132 of the 3D substrate). Without an electric field or a charge - neutral plasma within the substrate 130, ion deposition by PECVD may not deposit ions within the volume of any material that is larger than a few microns in thickness.

[0031] However, when the plasma 10 is present in front of or regardless of an electrical drive source, there is an electric field or a gradient voltage potential caused by the plasma 10. Based on this principle, when a plasma distribution is disposed or injected into a substrate 130 undergoing a PECVD process, the substrate 130 has a non-zero electric field within the volume of its thickness. Due to the non-zero electric field within the substrate 130, the substrate 130 has a charged ion deposition state in which ion deposition can occur within the volume of its thickness. In other words, the substrate 130 typically has an initial ion deposition state within the volume of its thickness that does not allow ion deposition, but this initial ion deposition state can be changed by doping the substrate 130 with the plasma 10 (e.g., before the PECVD process), enabling the PECVD process to deposit ions on the plasma-doped substrate 130 (e.g., substrate 130b) at one or more interstitial positions 132 within the volume of the substrate 130.

[0032] For comparison, FIG. 5 shows the same substrate as FIG. 4, except that the substrate 130b is doped with the plasma 10. When this plasma-doped substrate 130b undergoes PECVD, the plasma 10 present within the substrate 130b facilitates ion deposition. In other words, the plasma 10 within the substrate 130b can have a sheath 10b having an electric field that accelerates the ions deposited on the walls of the interstitial positions 132 within the volume of the substrate 130. Since any voids in the substrate 130 are of a size accessible to the plasma 10 (e.g., greater than about 10 microns), any microporous or macroporous material can receive ion deposition within its volume in addition to or instead of ion deposition on its outer surface.

[0033] Plasma Doping of Substrate A plasma-doping substrate generally refers to a substrate (e.g., substrate 130b) whose three-dimensional volume contains a plasma (e.g., plasma 10). That is, an ionized gas can be disposed within the volume of the substrate. Processes such as PECVD use an electric field (e.g., from the electrode system shown in FIG. 3) to generate a plasma, but the electric field is not the only way to generate a plasma. Since a plasma is an ionized gas, a process that stimulates ionization can introduce or dope the substrate with a plasma. One way ionization can occur is by ionizing radiation. When energy is emitted from a source, the process is called radiation. Ionizing radiation is a type of radiation in which the energy emitted by an atom travels in the form of electromagnetic waves (e.g., gamma rays or X-rays) or particles (e.g., neutrons, beta, or alpha). For example, ionizing radiation can occur from nuclear processes (also called nuclear radiation) such as radioactive decay (gamma decay, beta decay, alpha decay).

[0034] In some examples, when ionizing radiation occurs, charged particles with high energy can escape from the material and move into the gas. The charged particles in the gas can ionize the gas to generate a plasma. In this sense, the plasma is not electrically generated, but rather is generated by physical particles (referred to as particle-based) or electromagnetic waves (referred to as wave-based) as ionization mechanisms. Using this ionization mechanism, a substrate can be plasma-doped by being activated by particles or electromagnetic waves. For example, the substrate can be plasma-doped with a particle-based ionization mechanism. Some types of particles that can be used for particle-based ionization are alpha particles (e.g., particles with two protons and two neutrons) and beta particles (e.g., electrons, i.e., particles with the size and mass of an electron or a positron). In contrast, when the substrate is plasma-doped with a wave-based ionization mechanism, the wave can be generated from gamma radiation (e.g., by photons) or X-ray radiation (e.g., energy with a wavelength from 10 picometers to 10 nanometers). Since neutrons are not charged particles that interact electrically, neutrons do not directly ionize the gas, so neutrons may be used to facilitate ionization indirectly. Thus, neutrons facilitate a nuclear reaction (e.g., by absorption), followed later by radioactive decay that ionizes the gas (e.g., via alpha, beta, or gamma radiation).

[0035] When this concept is combined with PECVD, if the substrate is plasma-doped before the electric field is applied by the PECVD process, the substrate can receive ion deposition within its structure (i.e., not only on its surface). One approach to doping the substrate with plasma before the PECVD process is to direct ionizing radiation (e.g., from a nuclear process) onto the substrate. For example, the substrate is placed within a nuclear reactor such that the ionizing radiation generated by the nuclear process within the reactor "activates" or plasma-dopes the substrate. Here, the activated substrate (i.e., the plasma-doped substrate) begins to decay, but the substrate material can be selected such that the decay rate of the substrate allows the PECVD process to occur using the plasma-doped substrate before the decay is complete and the substrate ceases to be plasma-doped. For example, a nuclear reactant such as copper can capture neutrons and beta decay to generate plasma within its volume. The plasma-doped copper can then receive ion deposition from the PECVD process (e.g., as shown in FIG. 5) and can have a deposition layer 120 formed on the surface region within the volume (e.g., in addition to on its outer surface). Broadly speaking, this means that the substrate can be introduced to a charged particle ionization source to bring its initial ion deposition state within its volume to a charged ion deposition state.

[0036] Application to Structurally Complex Substrates Structurally complex substrates (also called "foams") that can undergo ion deposition (i.e., plating) at those inter-lattice positions (i.e., plated foams) can be used in a wide range of applications. One such application is that the plated foam can be used for one or more electrodes of a structured plasma cell energy converter (also called an energy converter). As described in U.S. Patent Application No. 17 / 202,952, entitled "Structured plasma Cell Energy Converter for a Nuclear Reactor", which is incorporated herein by reference, a structured plasma cell energy converter can generate electricity (i.e., power) based on the amount of electrons (or charge density) that successfully move from an emitting electrode to a collecting electrode. In some examples, the electricity may drive an electrical load 182 (see, for example, FIGS. 6 and 7). The higher the current density, the more electricity the energy converter generates. Further, the charge density also depends on the surface areas of both the emitter electrode (e.g., emitter electrode 160) and the collector electrode (e.g., collector electrode 170). Increasing the surface area of the emitter electrode increases the amount of electrons emitted, and increasing the surface area of the collector electrode increases the collection area for collecting the emitted electrons.

[0037] As can be seen by comparing FIG. 6 (non-foam energy converter system 180a) with FIG. 7 (foam energy converter system 180b), to increase the available surface area of the electrodes, the energy converter may use a plated foam having ion deposition at its inter-lattice positions as the emitter electrode and / or collector electrodes 160, 170. (Rather than just a surface-deposited thin film as in FIG. 6) By leveraging this type of complex substrate, FIG. 8 shows that the current density of the plated foam can be approximately 350% greater than the current density of a solid substrate formed from the same material as the plated foam, which means that the power generated by an energy converter using a plated foam for the electrodes can increase (e.g., by several times).

[0038] Even more generally, the output voltage of the energy converter, and thus the output power, is based on the difference in work function between the collector electrode 170 and the emitter electrode 160. To produce electrodes with a desired difference in work function, the energy converter may use a PECVD process with a plasma-doped substrate. That is, a foam of a first material type or a first shape may be used for the emitter electrode 160, while a foam of a second material type or a second shape may be used for the collector electrode 170. Using two different materials (or material shapes), a net amount of energy can be collected from the plasma itself. For example, experiments using materials with different work functions have shown that there is an open-circuit voltage equal to the difference between the work functions, even without applying a current to the system to facilitate the flow of electrons. This means that the heat source can collect energy across the plasma between the emitter and the collector based on the ionization state of the plasma, without boiling and evaporating electrons at the emitter.

[0039] In some embodiments, the energy converter uses a plasma-doped and plated foam to remove plasma from the inner electrode gap. In other words, in the configuration described in U.S. Patent Application No. 17 / 202,952, the inner electrode gap may include plasma as a way to prevent a space charge effect from occurring between the electrodes. Since the plated foam may already be plasma-doped, the plasma-doped portion of the substrate may function to facilitate electron transfer to the collector without the plasma playing a similar role in the inner electrode gap. In some exemplary configurations, the insulator 184 may be disposed within the inner electrode gap (see, for example, FIG. 7). The insulator 184 may be configured to provide electrical insulation between the emitter electrode 160 and the collector electrode 170.

[0040] Referring to FIG. 9, the stopping power or energy deposition per unit length can be used to indicate the optimal properties (e.g., shape or thickness) of the substrate, and the plasma doping of the substrate can be successfully achieved. In other words, when the stopping power is high, waves (e.g., photons) or particles generally have an insufficient penetration depth into the substrate. However, when the stopping power is low, waves (e.g., photons) or particles have a high penetration depth into the substrate. When the penetration depth is large, high-energy particles have a more uniform and complete deposition of energy that promotes good ionization of the gas within the substrate. The ionization mechanism for plasma doping the substrate can occur when waves (e.g., photons) or particles interact with the solid portion of the substrate, moving electrons from the solid portion of the substrate to the porous region (e.g., having interstitial spaces), and imparting energy to the gas occupying the volume of the porous region.

[0041] Propellable plasma cell In contrast to FIG. 2 showing the ion behavior of the plasma generated from chemically reactive species, FIG. 10 shows the ion behavior of the plasma generated from non-chemically reactive species. Here, non-chemically reactive species refer to a gas having molecules that do not chemically react (i.e., are chemically inert) when ionized. In non-chemically reactive environments 100, 100b, the electric field of the sheath 10b accelerates ions towards the wall 22. When ions (e.g., shown as "i" p + ") reach the wall, the ions neutralize with electrons (e.g., shown as "e" p - ") at the wall 22. When the gas species forming the plasma are non-reactive, the neutralization between ions and electrons at the wall 22 does not form chemical adhesion (i.e., ion deposition) on the wall 22 like reactive species. Instead, it results in neutral atoms (a combination of ions and electrons) bouncing back from the wall 22. The residual energy from this elastic collision of the ions with the wall 22 dissipates into the gas as heat. FIG. 10 shows this bouncing collision, and the black circles are neutral atoms.

[0042] An elastic collision with the wall 22 means that there was a net momentum transferred to the wall 22 by the ions. Due to this momentum, the colliding ions exert a pressure on the wall 22. Here, the pressure on the wall 22 can be expressed by the following equation.

Number

Number

[0043] In some examples, such as FIG. 11, a plasma cell 200 capable of propulsion can be constructed using a plasma generated from non-reactive species. In these examples, the plasma cell 200 refers to the volume of space that the plasma 10 can occupy, surrounded by a plurality of walls 210. For example, the arrangement of the walls 210 is three-dimensionally similar to the arrangement of a right prism as shown in FIG. 11, and thus two-dimensionally similar to a box. For simplicity of explanation, the electrostatics of the plasma cell 200 is described with respect to a two-dimensional four-wall box. Further, these same surfaces of the plasma cell 200 represented by FIG. 11 can be implemented for a 3D structure such as a right prism or another 3D shape (e.g., a cylindrical structure).

[0044] In some configurations, such as FIG. 11, the plurality of walls 210 includes a first wall 210a, a second wall 210b, a third wall 210c, and a fourth wall 210d. In this exemplary arrangement, the first wall 210a faces the second wall 210b, and the third wall 210c faces the fourth wall 210d. For example, the first wall 210a is arranged parallel to the second wall 210b, and the third wall 210c is arranged parallel to the fourth wall 210d. As shown in FIG. 11, the third and fourth walls 210c, d extend between the first and second walls 210a, b. For example, FIG. 11 shows the third and fourth walls 210c, d as being perpendicular to the first and second walls 210a, b. In an example of forming a cylindrical shape, the first wall 210a and the second wall 210b may correspond to two opposing portions of a curved wall.

[0045] Generally speaking, since the sheath 10b of the plasma 10 generates an electric field that accelerates ions towards the wall, a box having a sheath 10b along each surface may mean that the pressure exerted by the acceleration of ions on the four walls such as those in FIG. 11 can be overall balanced with respect to the plasma cell 200. For example, forces are exerted on the first wall 210a and the third wall 210c by the acceleration of ions, but the forces exerted on the second wall 210b and the fourth wall 210d cancel out those forces, resulting in a zero resultant force on the container of the plasma cell 200. In further contrast, if the electric field within the sheath corresponding to one or more walls 210 is selectively manipulated, the result can be a non-zero resultant force exerted on the plasma cell 200.

[0046] Based on this approach, FIG. 11 shows an example of a single plasma cell 200 where different walls (e.g., walls 210a - 210d) have different applied voltages or no voltage potential at all (e.g., are grounded) to propel ions towards a specific wall 210. Thus, the selected configuration may create a resultant force acting on the plasma cell 200. Referring specifically to FIG. 11, the first wall 210a and the second wall 210b may be electrically insulated and grounded, while the third wall 210c and the fourth wall 210d may each have an applied voltage that enables the resultant force to act on the plasma cell 200.

[0047] In some configurations, the third wall 210c has an applied voltage V equal to the potential of the plasma 10. By having an applied voltage V equal to the potential of the plasma 10, the sheath 10b along the third wall 210c behaves more similarly to the plasma bulk region in that the constant voltage potential does not create an electric field (i.e., the electric field is zero). This means that when the opposing wall, the fourth wall 210d, has an electric field from a voltage potential gradient, there is a pressure on the fourth wall 210d that is not canceled out by the third wall 210c. In other words, the ion acceleration within the sheath 10b at the fourth wall 210d adds a resultant force in that direction to the plasma cell 200. In FIG. 11, a voltage V lower than the potential of the plasma 10 is applied to the fourth wall 210d, creating a potential gradient and an electric field within the sheath 10b that accelerates ions towards the fourth wall 210d.

[0048] With a configuration such as the plasma cell 200 in FIG. 11, the voltage can be selectively applied to selectively add a resultant force to the plasma cell 200. In other words, by controlling the electric field of the sheath with or without applying a specific voltage, the resultant force of the plasma cell 200 can be switched off or on like a switch. When a resultant force exists, it can function in the form of a thrust that pushes or propels the plasma cell 200 in the direction opposite to the resultant force, according to Newton's third law of action and reaction.

[0049] For a single plasma cell 200, the resultant force that can be generated by the configuration as shown in FIG. 11 may appear to be almost negligible. For example, an electrically driven plasma (i.e., a plasma generated via an electric field, i.e., an electrically generated plasma) has an ion density of n i = 10 18 m -3 , an electron temperature of at least kT e = 1.6×10 -19 J (1 eV), and a sheath voltage of V s = 1.6×10 -18 J (10 V). These values for the electrically driven plasma according to Equation (1) result in a pressure or resultant force of

Equation

[0050] Fortunately, a plasma cell as shown in FIG. 11 can have a unit cell length in the range of approximately 10 micrometers to approximately 100 micrometers (about 10 - 100 μm). At this size, it is possible to stack multiple plasma cells 200 in an array to achieve a non - negligible resultant force of the array. For example, an array of plasma cells can contain tens of thousands to hundreds of thousands (10 4 ~10 5 ) plasma cells. Using the previous exemplary estimate for an electrically driven plasma where each plasma cell 200 produces 2 N per square meter, the array can generate a force exceeding 200,000 N (e.g., 2 N×(10 4 ~10 5 ).

[0051] Conventionally, electrically driven plasmas require a large surface area and energy costs that are likely to be extremely expensive in the formation of plasma cell arrays. For example, plasma cell 200 cannot achieve a unit cell length of about 10 micrometers to about 100 micrometers using an electrically driven plasma. Plasma cell 200 can ionize the gas within its volume using a specific charged ionization without the need to electrically ionize the gas. In other words, similar to the plasma doping process of the substrate described with respect to FIG. 5, charged particles can be used to ionize the gas within plasma cell 200 in order to avoid the need to electrically generate plasma within plasma cell 200. In other words, each plasma cell 200 (or the entire array of plasma cells 200) can be exposed to ionizing radiation (i.e., an ionizing radiation source) to ionize the gas within plasma cell 200, and as a result, plasma can be formed within plasma cell 200. When the gas is ionized, an appropriate voltage can be applied to the wall 210 of plasma cell 200 to selectively apply a resultant force to cell 200 or the sum of the resultant forces of the array of cells 200.

[0052] FIG. 12 shows an example of an array of plasma cells 200a - n. In this example, the plasma cells 200a - n are arranged in a stacked configuration. Here, the stacked configuration is such that all of the third walls 210c of the individual plasma cells 200 can be stacked on the same side of the array, while all of the fourth walls 210d can be stacked on the opposite side of the array. For example, FIG. 12 aligns all of the third walls 210c and / or all of the fourth walls 210d of the plasma cells 200 in the array in a straight line. In some configurations, the plasma cells 200 of the array are arranged such that the first terminal receives an applied voltage (e.g., a voltage equal to or less than the plasma potential) and supplies that applied voltage in parallel to a particular wall of each plasma cell 200. In these configurations, it may be spatially advantageous to arrange all of the third walls 210c on the same side of the array in order to enable the first terminal to supply the applied voltage in parallel to each third wall 210c. Similarly, the plasma cells 200 of the array may have a second terminal that receives an applied voltage and supplies that applied voltage in parallel to each fourth wall 210d of the plasma cell 200. With this two - terminal configuration, the array can essentially have one voltage bus that applies the plasma potential to each plasma cell 200 and another voltage bus that applies a voltage less than the plasma potential to each plasma cell 200.

[0053] The following clauses provide exemplary configurations for embedding and related methods, as described above.

[0054] Clause 1: In a method of depositing a material on a substrate having a first outer surface, a second outer surface opposite the first outer surface, and a thickness portion extending between the first outer surface and the second outer surface, the substrate includes a charge - neutral ion deposition state within the volume of the thickness portion, and the method includes doping the substrate with a plasma to generate a charged - ion deposition state in the substrate, wherein the charged - ion deposition state has a non - zero electric field within the volume of the thickness portion, and depositing ions on the plasma - doped substrate at one or more interstitial lattice positions within the volume of the thickness portion.

[0055] Clause 2: The method according to Clause 1, wherein the step of doping the substrate with plasma includes exposing the substrate to nuclear radiation.

[0056] Clause 3: The method according to Clause 1 or 2, wherein the step of doping the substrate with plasma is performed using a particle-based ionization mechanism, and the step of depositing ions on the substrate doped with plasma is performed using an electrically generated plasma in a chemical vapor deposition chamber.

[0057] Clause 4: The method according to any one of Clauses 1 to 3, wherein the step of doping the substrate with plasma uses an ionization mechanism initiated by charged particles.

[0058] Clause 5: The method according to Clause 4, wherein the charged particles are alpha particles.

[0059] Clause 6: The method according to Clause 4 or 5, wherein the charged particles are beta particles.

[0060] Clause 7: The method according to any one of Clauses 1 to 6, wherein the step of doping the substrate with plasma uses an ionization mechanism initiated by photons.

[0061] Clause 8: The method according to Clause 7, wherein the ionization mechanism initiated by photons is performed using gamma radiation.

[0062] Clause 9: The method according to Clause 1, wherein the substrate is in a state of radioactive decay in the charged ion deposition state.

[0063] Clause 10: The method according to any one of Clauses 1 to 9, wherein the step of depositing ions on the substrate doped with plasma is performed in a plasma-enhanced chemical deposition reactor, and the step of doping the substrate with plasma to generate a charged ion deposition state is performed outside the plasma-enhanced chemical deposition reactor.

[0064] Clause 11: The step of depositing ions on a substrate doped with plasma includes supplying a source gas into a chamber containing the substrate doped with plasma and applying a voltage to a high-frequency electrode for a predetermined time period, and the method according to any one of Clauses 1 to 10.

[0065] Clause 12: The method according to Clause 11, wherein the predetermined time period corresponds to the deposition rate of ions at one or more interstitial positions within the volume of the substrate.

[0066] Clause 13: The method according to any one of Clauses 1 to 12, wherein the substrate includes a set of voids each defined by an aperture greater than about 10 microns.

[0067] Clause 14: A substrate comprising a first outer surface, a second outer surface opposite the first outer surface, and a region having a volume extending from the first outer surface to the second outer surface, wherein at least a portion of the volume defines a void at an interstitial position, the interstitial position being defined by a wall having a surface, and the surface includes a plasma-forming deposition layer.

[0068] Clause 15: The substrate according to Clause 14, wherein the plasma-forming deposition layer is formed by a plasma disposed within the void, and the plasma has an ionized state initiated by charged particles.

[0069] Clause 16: The substrate according to Clause 15, wherein the charged particles are alpha particles.

[0070] Clause 17: The substrate according to Clause 15 or 16, wherein the charged particles are beta particles.

[0071] Clause 18: The substrate according to any one of Clauses 14 to 17, wherein the plasma-forming deposition layer is formed by a plasma disposed within the void, and the plasma has an ionized state initiated by photons.

[0072] Clause 19: The plasma-formed deposition layer is formed by plasma disposed within the cavity, and the plasma has an ionized state initiated by gamma radiation, on the substrate according to any one of Clauses 14 to 18.

[0073] Clause 20: The cavity at the interstitial position is defined by an opening larger than about 10 microns, on the substrate according to any one of Clauses 14 to 19.

[0074] Clause 21: In a system comprising a chamber having a source gas inlet port and an exhaust outlet port, an electrode electrically coupled to a voltage source, and a plasma doping substrate facing the electrode, the plasma doping substrate has a first outer surface, a second outer surface opposite the first outer surface, and a region having a volume extending from the first outer surface to the second outer surface, wherein at least a portion of the volume defines a cavity at the interstitial position, and the system includes plasma disposed within the cavity.

[0075] Clause 22: Charged particles initiate the ionized state defining the plasma, in the system according to Clause 21.

[0076] Clause 23: The charged particles are alpha particles, in the system according to Clause 22.

[0077] Clause 24: The charged particles are beta particles, in the system according to Clause 22 or 23.

[0078] Clause 25: Photons initiate the ionized state defining the plasma, in the system according to any one of Clauses 22 to 24.

[0079] Clause 26: Gamma radiation initiates the ionized state defining the plasma, in the system according to any one of Clauses 21 to 25.

[0080] Clause 27: The cavity at the interstitial position is defined by an opening larger than about 10 microns, in the system according to any one of Clauses 21 to 26.

[0081] Clause 28: In a system comprising a plurality of plasma cells, each plasma cell includes a plasma formed from a non-reactive gas species, a first wall, a second wall facing the first wall, a third wall extending between the first wall and the second wall and having a first voltage equal to the potential of the plasma, and a fourth wall facing the third wall and extending between the first wall and the second wall and having a second voltage lower than the potential of the plasma. The first wall and the second wall form a first pair of opposing walls that are electrically insulated and grounded. The plasma occupies the volume of each plasma cell between each of the first wall, the second wall, the third wall, and the fourth wall. The plurality of plasma cells are stacked in a configuration such that all of the third walls are on the same side as the stack while facing all of the fourth walls on the side opposite the stack.

[0082] Clause 29: The system according to clause 28, wherein the configuration of all of the third walls facing the same side of all of the fourth walls aligns all of the third walls in a straight line.

[0083] Clause 30: The system according to clause 28 or 29, wherein the configuration forms a first terminal configured to maintain the first voltage in parallel with each third wall of the plurality of plasma cells, and a second terminal configured to receive the second voltage and supply the second voltage in parallel with each fourth wall of the plurality of plasma cells.

[0084] Clause 31: The system according to any one of clauses 28 to 30, wherein the plasma is formed from a non-reactive gas species by ionization of charged particles.

[0085] Clause 32: The system according to any one of clauses 28 to 31, wherein at least one of the first voltage or the second voltage is selectively applied.

[0086] Clause 33: The system according to any one of clauses 28 to 32, wherein a resultant force is selectively applied to the system by selectively applying at least one of the first voltage or the second voltage.

[0087] Conclusion The foregoing description is essentially exemplary only and is not intended to limit the disclosure, its application, or its use in any way. The broad teachings of the disclosure can be implemented in a variety of forms. Accordingly, while the disclosure includes specific examples, upon review of the drawings, the specification, and the following claims, other modifications will become apparent, and the true scope of the disclosure should not be so limited. In the described description and claims, one or more steps within a method may be performed in a different order (or simultaneously) without changing the principles of the disclosure. Similarly, one or more instructions stored on a non-transitory computer-readable medium may be executed in a different order (or simultaneously) without changing the principles of the disclosure. Unless otherwise indicated, the numbering or other labeling of instructions or method steps is for convenience of reference and does not indicate a fixed order.

[0088] Furthermore, each of the embodiments has been described above as having certain features, but any one or more of those features described with respect to any embodiment of the disclosure may be implemented in and / or combined with any of the features of other embodiments, even if the combination is not explicitly described. In other words, the described embodiments are not mutually exclusive, and substitution of one or more embodiments for one another remains within the scope of the disclosure.

[0089] Spatial and functional relationships between elements (e.g., between modules, between circuit elements, between semiconductor layers, etc.) are described using various terms including "connected," "engaged," "coupled," "adjacent," "next to," "above," "over," "below," and "disposed." Unless explicitly stated to be "direct," when a relationship between a first element and a second element is described in the above disclosure, the relationship encompasses both a direct relationship where no other intervening elements exist between the first and second elements and an indirect relationship where one or more intervening elements exist between the first and second elements.

[0090] The phrase "at least one of A, B, or C" should be interpreted to mean the logic (A OR B OR C) using non-exclusive logical OR, and should not be interpreted to mean "at least one of A, at least one of B, and at least one of C". The term "set" does not necessarily exclude the empty set. In other words, depending on the situation, a "set" can have zero elements. The term "non-empty set" may be used to indicate the exclusion of the empty set. In other words, a non-empty set always has one or more elements. The term "subset" does not necessarily require a proper subset. In other words, a "subset" of a first set may have the same extent as (be equal to) the first set. Further, the term "subset" does not necessarily exclude the empty set, and depending on the situation, a "subset" can have zero elements.

[0091] In the figure, the direction of the arrow indicated by the arrow generally indicates the flow of information (such as data or instructions) of interest in the illustration. For example, if element A and element B exchange various information and the information sent from element A to element B is relevant to the illustration, the arrow may point from element A to element B. This one-way arrow does not imply that no other information is sent from element B to element A. Further, with respect to the information sent from element A to element B, element B may send a request for information or an acknowledgment of receipt to element A.

Claims

1. In a method of depositing a material on a substrate having a first outer surface, a second outer surface opposite the first outer surface, and a thickness portion extending between the first outer surface and the second outer surface, the substrate includes a charge-neutral ion deposition state within the volume of the thickness portion, and the method includes: Doping the substrate with plasma to generate a charged ion deposition state in the substrate, wherein the charged ion deposition state has a non-zero electric field within the volume of the thickness portion; Depositing ions on the substrate doped with plasma at one or more interstitial positions within the volume of the thickness portion; A method comprising:

2. The method according to claim 1, wherein doping the substrate with plasma includes exposing the substrate to nuclear radiation.

3. The step of doping the substrate with plasma is performed using a particle-based ionization mechanism, The method according to claim 1, wherein the step of depositing ions on the substrate doped with plasma is performed using an electrically generated plasma in a chemical vapor deposition chamber.

4. The method according to claim 1, wherein the step of doping the substrate with plasma uses an ionization mechanism initiated by charged particles.

5. The method according to claim 4, wherein the charged particles are alpha particles.

6. The method according to claim 4, wherein the charged particles are beta particles.

7. The method according to claim 1, wherein the step of doping the substrate with plasma uses an ionization mechanism initiated by photons.

8. The method according to claim 7, wherein the ionization mechanism initiated by the photons is performed using gamma radiation.

9. The method according to claim 1, wherein in the charged ion deposition state, the substrate is in a state of radioactive decay.

10. The step of depositing ions on the substrate doped with plasma is performed in a plasma-enhanced chemical deposition reactor, The step of doping the substrate with plasma to generate the charged ion deposition state is performed outside the plasma-enhanced chemical deposition reactor. The method according to claim 1.

11. The step of depositing ions on the substrate doped with plasma includes: Supplying a source gas into a chamber containing the substrate doped with plasma; Applying a voltage to the high-frequency electrode during a predetermined time period The method according to claim 1, comprising:

12. The method according to claim 11, wherein the predetermined time period corresponds to the deposition rate of ions at the one or more inter-lattice positions within the volume of the substrate.

13. The method according to claim 1, wherein the substrate includes a set of voids each defined by an opening greater than about 10 microns.

14. A first outer surface, A second outer surface opposite the first outer surface, A region having a volume extending from the first outer surface to the second outer surface, at least a portion of the volume defining a void at an inter-lattice position, the inter-lattice position being defined by a wall having a surface, the surface including a plasma-forming deposition layer, A substrate comprising:

15. The substrate according to claim 14, wherein the plasma-forming deposition layer is formed by a plasma disposed within the void, the plasma having an ionized state initiated by charged particles.

16. The substrate according to claim 15, wherein the charged particles are alpha particles.

17. The method according to claim 15, wherein the charged particles are beta particles.

18. The substrate according to claim 14, wherein the plasma-forming deposition layer is formed by a plasma disposed within the void, the plasma having an ionized state initiated by photons.

19. The substrate according to claim 14, wherein the plasma-forming deposition layer is formed by a plasma disposed within the void, the plasma having an ionized state initiated by gamma radiation.

20. The substrate according to claim 14, wherein the void at the inter-lattice position is defined by an opening greater than about 10 microns.

21. A chamber having a source gas inlet port and an exhaust outlet port, An electrode electrically coupled to a voltage source, A plasma doping substrate facing the electrode In a system comprising: The plasma doping substrate, A first outer surface, A second outer surface opposite the first outer surface, A region having a volume extending from the first outer surface to the second outer surface, at least a portion of the volume defining a void at an inter-lattice position, A plasma disposed within the void A system comprising:

22. The system according to claim 21, wherein charged particles initiate an ionized state defining the plasma.

23. The system according to claim 22, wherein the charged particle is an alpha particle.

24. The system according to claim 22, wherein the charged particle is a beta particle.

25. The system according to claim 21, wherein photons initiate an ionization state that defines the plasma.

26. The system according to claim 21, wherein gamma radiation initiates an ionization state that defines the plasma.

27. The system according to claim 21, wherein the cavity at the inter-lattice position is defined by an opening greater than about 10 microns.

28. In a system comprising a plurality of plasma cells, each plasma cell comprises a plasma formed from a non-reactive gas species, a first wall, a second wall facing the first wall, a third wall extending between the first wall and the second wall and having a first voltage equal to the potential of the plasma, and a fourth wall facing the third wall, extending between the first wall and the second wall, and having a second voltage lower than the potential of the plasma wherein the first wall and the second wall form a first pair of opposing walls that are electrically insulated and grounded, the plasma occupies the volume of each plasma cell between each of the first wall, the second wall, the third wall, and the fourth wall, and the plurality of plasma cells are stacked in a configuration such that all third walls are on the same side as the stacked plasma cells while facing all fourth walls on the opposite side of the stacked plasma cells.

29. The system according to claim 28, wherein the configuration of all third walls facing the same side of all fourth walls aligns all third walls in a straight line.

30. The configuration comprises a first terminal configured to maintain the first voltage in parallel with each third wall of the plurality of plasma cells, and a second terminal configured to receive the second voltage and supply the second voltage in parallel with each fourth wall of the plurality of plasma cells The system according to claim 28.

31. The system according to claim 28, wherein the plasma is formed from the non-reactive gas species by charged particle ionization.

32. The system according to claim 28, wherein at least one of the first voltage or the second voltage is selectively applied.

33. The system according to claim 28, wherein a resultant force is selectively applied onto the system by selectively applying at least one of the first voltage or the second voltage.

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