Large-area / wafer-scale CMOS-compatible 2D material intercalation doping tools, processes, and methods, including doping of synthetic graphene

Abstract

1. An intercalation doping apparatus comprising: a reactor chamber, wherein single or multiple wafers or substrates (SoMWoSubs) are disposed within the reactor chamber, the SoMWoSubs having a diameter or side distance of 25 mm to 450 mm; the intercalation doping apparatus comprising a heater, the heater configured to provide heat to the SoMWoSubs disposed within the reactor chamber, wherein the SoMWoSubs have a temperature of 25°C to 500°C; a pressure in the range of 2 bar to 500 bar is applied to at least one surface of the SoMWoSubs disposed within the reactor chamber; the intercalation doping apparatus comprising a dopant addition apparatus, the dopant addition apparatus comprising at least a valve and tubing for bringing dopant into the reactor chamber from outside, and at least a dopant crucible disposed within the reactor chamber; the dopant comprising a substance in a solid, liquid, or gas phase, and the dopant comprising an intercalation dopant.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application references U.S. patent application Ser. No. 17 / 863,232, entitled LOW TEMPERATURE / BEOL-COMPATIBLE HIGHLY SCALABLE GRAPHENE SYNTHESIS TOOL, filed July 12, 2022; U.S. patent application Ser. No. 17 / 857,954, entitled LOW-TEMPERATURE / BEOL-COMPATIBLE HIGHLY SCALABLE GRAPHENE SYNTHESIS TOOL, filed July 5, 2022; and U.S. provisional patent application Ser. No. 63 / 218,498, entitled WAFER-SCALE CMOS-COMPATIBLE GRAPHENE SYNTHESIS TOOL, filed July 6, 2021, as related applications, the entire contents of which are incorporated herein by reference.

[0002] This application also claims priority to U.S. patent application Ser. No. 18 / 527,043, filed December 1, 2023, entitled LARGE-AREA / WAFER-SCALE CMOS-COMPATIBLE 2D-MATERIAL DOPING TOOLS, PROCESSES, AND METHODS, INCLUDING DOPING OF SYNTHESIZED GRAPHENE, which claims the benefit of U.S. patent application Ser. No. 63 / 441,766, filed January 27, 2023, the entire contents of which are incorporated herein by reference. [Background technology]

[0003] In many applications, including microelectronics, atomically thin two-dimensional (2D) layered materials, including synthetic multilayer graphene (MLG) or any layered semiconductor material (such as molybdenum disulfide (MoS2) or tungsten disulfide (WS2)), often need to be modulated. Typically, this requires an increase in the carrier concentration of electrons, vacancies, or other charge carriers. This increase in carrier concentration can be achieved through a process called doping, which requires the insertion or adsorption of certain atoms or molecules into the host material to induce charge transfer between the dopant and the material, such as MLG. In some cases, the placement of the dopant at specific crystallographic sites that are electrically activated or ionized (thereby creating excess electrons or vacancies) can also be engineered to cause doping. Sometimes, dopants, such as arsenic (As) atoms in single-crystal silicon, require thermal annealing, which uses applied heat energy to move the As atoms from interstitial sites in the silicon to substitutional crystal sites. To integrate any MLG / layered material doping process into CMOS technology, dedicated large area (200 / 300 / 450 / XXX mm) reactors must be designed that also need to operate at high pressures (1-500 bar) below current and projected Back-End-Of-Line (BEOL) thermal budgets (<450°C). This doping acceleration can involve temperature or pressure effects or a combination of both.

[0004] In the emerging field of atomically thin two-dimensional (2D) materials, graphene or MLG (essentially single or multiple atomic layers of carbon atoms arranged in a hexagonal lattice) can now be synthesized directly on a desired substrate (typically a dielectric or metal). Previously, contamination, defect / wrinkling, and other issues with transferred graphene / MLG required a transfer step (to deposit the graphene / MLG on the desired substrate after synthesis on a metal catalyst film), which was considered unfeasible and cost-ineffective in the mainstream electronics (or CMOS) industry. Furthermore, previously, doping MLG or other 2D materials by conventional methods presented numerous challenges. A key focus of future interconnect material selection is graphene / MLG layers, which need to be doped to meet specific resistivity targets. These are the preferred materials for several BEOL (back-of-the-line) applications, particularly on-chip interconnects.

[0005] Intercalation doping may be used to minimize the bulk resistivity of single or multi-stack materials due to geometries, such as the layered structures of many 2D materials. Intercalation doping involves the insertion of dopant atoms / molecules through the sidewall surfaces of these materials by diffusion, which has been shown to enable doping for narrow geometries (linewidths) of 2D materials. Acceleration of such doping processes by application of temperature and / or pressure can make the doping process manufacturable and low-cost.

[0006] A wide range of applications, spanning microelectronics, optoelectronics, bioelectronics, quantum computing, antennas (5G / 6G / THz), and many others, require doping at relatively low temperatures (<450°C). However, enabling such doping within reasonable timescales, especially across large "wafer-scale" (e.g., 200 mm, 300 mm, 450 mm, etc.) substrates, requires the design and fabrication of novel apparatus that can enable the uniform application of wide ranges of temperature and pressure across the entire surface area of ​​a semiconductor wafer or other substrate. The core components of such apparatus would be a reactor that can not only accommodate such large-area substrates, but also have a chemically purged environment, acceptable temperature uniformity, and would also enable heating large-area substrates by gas and / or mechanical means via a simple mechanism for applying relatively large, uniform pressures to the wafer / substrate (e.g., up to 7000 psi, 500 bar, etc., but within the substrate's destruction limits). Note that atmospheric pressure can be used in some embodiments.

[0007] For example, the emerging field of atomically thin two-dimensional (2D) materials, particularly graphene or MLG, is creating a need for such large-area devices. Such graphene / MLG layers are preferred materials for several BEOL applications, particularly on-chip interconnects. However, BEOL interconnects must be effectively synthesized and doped under a strict thermal budget of <450°C to avoid any damage to the underlying active devices (e.g., transistors, diodes, etc.) due to enhanced diffusion of impurities. Therefore, the addition of pressure operation is crucial to achieve doping at such relatively lower temperatures within acceptable timescales for high-volume manufacturing environments.

[0008] The device and doping techniques described herein are extendable to a wide range of substrates of different materials (e.g., glass), geometries (e.g., square), and configurations (e.g., multilayer), and to other applications that inherently require a low thermal budget (<450°C). Summary of the Invention

[0009] In one aspect, an intercalation doping apparatus for facilitating the insertion of dopant atoms, ions, or molecules into layered 2D materials includes a reactor chamber, wherein one or more wafers or substrates are disposed within the reactor chamber, a pressure is applied to at least one surface of the single or more wafers or substrates within a range of 2 bar to 500 bar, the single or more wafers or substrates have a diameter or side distance of 25 mm to 450 mm, the intercalation doping apparatus includes a heater, and the heater is configured to heat the single or more wafers or substrates. an intercalation doping apparatus, comprising: a wafer or substrate; a wafer or substrates; a temperature of the wafer or substrates being between 25°C and 500°C; a dopant addition device including at least a valve and tubing for introducing dopant from the outside into the reactor chamber; a dopant addition device including at least a dopant crucible disposed in the reactor chamber; a dopant including a solid, liquid, or gaseous substance; and an intercalation doping agent.

[0010] In another aspect, an intercalation doping apparatus for facilitating the insertion of dopant atoms, ions, or molecules into layered 2D materials includes a reactor chamber, wherein a single or multiple wafers or substrates are disposed within the reactor chamber, a pressure is applied to at least one surface of the single or multiple wafers or substrates within a range of 2 bar to 500 bar, the single or multiple wafers or substrates have a diameter or side distance of 25 mm to 450 mm, the intercalation doping apparatus includes a heater, wherein the heater applies heat to the single or multiple wafers or substrates, and the single or multiple wafers or substrates are heated by the heater. the plurality of wafers or substrates have a temperature of 25°C to 500°C, the intercalation doping apparatus includes a dopant addition device, the dopant addition device at least includes valves and tubing for bringing dopant into the reactor chamber from the outside, the dopant addition device at least includes a dopant crucible disposed in the reactor chamber, the dopant includes a substance in a solid phase, a liquid phase, or a gas phase, the dopant includes an intercalation dopant, and the single or plurality of wafers or substrates include single-layer, few-layer, or multi-layer graphene strips.

[0011] In another aspect, there is provided a method of intercalation doping, wherein the intercalation doping comprises an apparatus for facilitating insertion of dopant atoms, ions, or molecules into layered 2D materials, the method comprising: providing a reactor chamber, a heater, and a dopant addition apparatus; and providing a single or multiple wafers or substrates, the single or multiple wafers or substrates being disposed in the reactor chamber, the single or multiple wafers or substrates having a diameter or side distance between 25 mm and 450 mm; the method comprising applying heat to the single or multiple wafers or substrates by the heater, the single or multiple wafers or substrates being heated to a temperature between 25° C. and 500° C. wherein the method comprises applying a pressure in the range of 2 bar to 500 bar to at least one surface of the single or multiple wafers or substrates, wherein the dopant addition device brings a dopant into the reactor chamber and / or contains the dopant within the reactor chamber, wherein the dopant comprises a substance in a solid, liquid or gas phase, wherein the dopant comprises an intercalation dopant, wherein the single or multiple wafers or substrates comprise single, few or multi-layer graphene strips, and wherein the method comprises treating the single or multiple wafers or substrates at said temperature and said pressure in the presence of at least one of the intercalation dopant.

[0012] The present application can be best understood by referring to the following description taken in conjunction with the accompanying drawings, in which like parts may be referenced by like numerals, and in which: [Brief explanation of the drawings]

[0013] [Figure 1A] FIG. 1 shows an exemplary batch / single wafer process apparatus capable of inserting gas phase dopant atoms or molecules into single-layer, few-layer, or multi-layer graphene (MLG) or any other layered or non-layered material of any geometry and thickness, synthesized by any method, and employing gas pressurization of the wafer. [Figure 1B]FIG. 1B shows an example apparatus schematic diagram of an apparatus similar to FIG. 1A with the additional feature of employing solid / liquid dopants vaporized into a gas along with gas pressurization of the substrate / wafer, according to some embodiments. [Figure 2] FIG. 1 illustrates a second exemplary apparatus schematic and process for introducing gas into a reactor chamber and pressurizing dopants (gas or liquid / solid vaporized into gas) by gas pressurization for the purpose of doping single or multiple wafers / substrates arranged horizontally, according to some embodiments. [Figure 2A] FIG. 10 shows a third exemplary apparatus schematic diagram of a process / reactor chamber in at least the apparatus of FIG. 2 using non-contact pressurized acceleration of doping by a piston over a horizontally positioned substrate / wafer in addition to various other means, according to some embodiments. [Figure 3] FIG. 10 illustrates a fourth exemplary apparatus schematic diagram using direct contact mechanical pressing of gas or solid / liquid dopant source (vaporized or not vaporized into gas), according to some embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0014] The above drawings are a representative set of implementations of the present invention and are not exhaustive.

[0015] Systems, methods, and articles of manufacture are disclosed for various low-temperature / BEOL-compatible, highly scalable doping tools configured to enable efficient doping of difficult-to-dop materials. One example of a difficult-to-dop material that is becoming a preferred choice for scaling microelectronic interconnects is single-layer or multilayer high-quality graphene. The following description is presented to enable those skilled in the art to make and use various embodiments. Descriptions of specific devices, techniques, and applications are provided by way of example only. Various modifications of the examples described herein will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other examples and applications without departing from the spirit and scope of the various embodiments.

[0016] Throughout this specification, references to "one embodiment," "an embodiment," "one example," or similar phrases mean that the particular feature, structure, or characteristic described in connection with that embodiment is included in at least one embodiment of the invention. Thus, throughout this specification, "in one embodiment," "in an embodiment," and similar phrases may, but do not necessarily, all refer to the same embodiment.

[0017] Furthermore, the described features, structures, or characteristics of the invention may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are set forth, such as programming, software modules, user selections, network transactions, database queries, database structures, hardware modules, hardware circuits, hardware chips, etc., to provide a thorough understanding of embodiments of the invention. However, one skilled in the art will recognize that the invention may be practiced without one or more of these specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations have not been shown or described in detail to avoid obscuring aspects of the invention.

[0018] The schematic flowchart diagrams included herein are generally set forth as logical flowchart diagrams. Accordingly, the depicted order and labeled steps represent one embodiment of the presented method. Other steps and methods may be conceived that are equivalent in function, logic, or effect to one or more steps, or portions thereof, of the depicted method. Furthermore, the format and symbols employed are intended to illustrate the logical steps of the method and are understood not to limit the scope of the method. While various arrow types and line styles may be employed in the flowchart diagrams, they are understood not to limit the scope of the corresponding method. In fact, some arrows or other connectors may be used to indicate only the logical flow of the method. For example, arrows may indicate waiting or monitoring periods of indefinite duration between listed steps of the depicted method. Furthermore, the order in which a particular method is performed may or may not strictly follow the order of the corresponding steps shown.

[0019] definition Back-end-of-line (BEOL) is the second part of IC fabrication where interconnects and other circuit elements (e.g., metallization layers) are formed between and on individual devices (primarily transistors) on the wafer separated by intra-layer and / or inter-layer dielectrics.

[0020] Complementary metal-oxide-semiconductor (CMOS) is a type of metal-oxide-semiconductor field-effect transistor (MOSFET) fabrication process that uses complementary, multiple times electrically symmetric p-type and n-type MOSFETs to implement at least some logic functions.

[0021] A grain boundary (GB) is the interface between two grains and / or crystallites in a polycrystalline material.

[0022] Graphene is an allotrope of carbon consisting of a single layer of atoms arranged in a two-dimensional honeycomb lattice.

[0023] Graphene nanoribons (GNRs) are strips of graphene with widths less than about 100 nm.

[0024] Graphite is a layered crystalline form of the element carbon in which the atoms are arranged and covalently bonded to form hexagonal structures within the layers.

[0025] Intercalation doping: Intercalation is when molecules or ions reversibly insert themselves between the layers of a compound (such as potassium ions between graphite layers). Doping is the addition of impurities into a material. The dopant (impurity ion) enters the lattice of the material. An N-type dopant donates electrons to the material. A P-type dopant accepts electrons from the material. This changes the charge carrier density and therefore the electronic properties of the material.

[0026] Intercalation dopants: There are many intercalation dopants in the literature. Specific ones for graphene include recent work by Kaustav Banerjee et al., e.g., J. Jiang, Jae Hwan Chu, and Kaustav Banerjee, "CMOS-Compatible Doped-Multilayer-Graphene Interconnects for Next-Generation VLSI", IEDM 2018, pp. 799-802, 34:5.1-4 and J. Jiang, et al., "Intercalation doped multilayer-graphene-nanoribbons for next-generation interconnects", Nano Letters, vol. 17, no. 3, pp. 1482-1488, 2017.

[0027] Piezoelectricity is the accumulation of electrical charge in certain solid materials in response to applied mechanical stress.

[0028] A resistance temperature detector (RTD) is a sensor used to measure temperature by monitoring the change in electrical resistance of a conductor with temperature. RTD elements can consist of a single thin wire wound on a heat-resistant ceramic or glass core, although other constructions are also used.

[0029] Silicon dioxide is an oxide of silicon and an insulator with the chemical formula SiO2.

[0030] A wafer is a thin slice of semiconductor (eg, crystalline silicon, germanium) used in the fabrication of integrated circuits and the like.

[0031] Exemplary large-area / wafer-scale low-temperature / BEOL-compatible highly scalable doping tool: batch / single; dopant = gas; substrate pressurization = gas

[0032] It should be noted that the following exemplary embodiments describe doping materials as examples, however, other doping devices or methods may be used in other exemplary embodiments.

[0033] Various exemplary apparatus and techniques for the insertion of solid / liquid or vapor phase dopant atoms or molecules into single-layer, few-layer, or multilayer graphene (MLG) or any other layered material, synthesized by any method and having any geometry and thickness, as shown at least in Figures 1A, 1B, 2, 3, and 4. Figure 1A shows a schematic diagram of an exemplary batch (although the apparatus can also accommodate a single wafer / substrate) doping apparatus and an exemplary process. For example, doping of graphene / MLG by vapor phase doping, e.g., using pressure and temperature acceleration, can be described, particularly, but not limited to, intercalation doping of MLG. This process and apparatus are not limited to intercalation doping of MLG, and many other materials can be doped with this apparatus using other methods.

[0034] As shown in FIG. 1A , the batch process apparatus 100 includes, but is not limited to, a reactor chamber 102, a reactor chamber door and seal 104, a substrate / wafer 105, a paddle 106, a dopant process gas / mist inlet 108, a full reactor process chamber volume 110, a multi-way high pressure valve 112, a piston chamber volume 114, a pump purge and pressure gas 116, a pressurization / exhaust pump 118, a piston movement shaft 120, a piston chamber 122, a solenoid or screw motor 124, a piston 126, a chamber sidewall heater 130, additional mechanisms for gases 3 and 4, if needed, 132, a pump-to-chamber valve 134, a gas panel 140, a dopant gas mixing block 142, an MFC (mass flow controller) ISO valve-output 146, an MFC (mass flow controller) 148, and an MFC (mass flow controller) 149. At least an ISO valve-input 150, a gas regulator 152, a particulate filter 154, a dopant 1 gas cylinder 156, a dopant 2 gas cylinder 157, and a cleanroom gas service facility 158 may be included.

[0035] The reactor chamber 102 can include both a sealed steel pressure vessel capable of withstanding the applied pressure and temperature, and a tubular liner, which can be made of materials such as high-quality, high-purity quartz. The reactor chamber 102 can include openings, such as a reactor chamber door and seal 104, a dopant process gas / mist inlet 108 (which may be integrated with a high-pressure shut-off valve), and an opening for pressurized equipment through a multi-way, high-pressure valve 112. The reactor chamber door and seal 104 can be opened (after the reactor chamber 102 has been evacuated of toxic gases and then brought to atmospheric pressure), and the substrates / wafers 105 can be loaded onto a paddle 106, which can include a quartz "boat" (not shown) with slots to hold the substrates / wafers 105 in a desired position, typically parallel with spacing determined by uniformity through engineering calculations and considerations. However, there are many options for holding and processing the substrates and wafers. In this exemplary FIG. 1, the batch processing apparatus 100 is shown in a horizontal configuration. An alternative batch process apparatus 100 can be rotated 90 degrees to become a vertical high-pressure process chamber. The reactor chamber 102 may include a system for mixing input gases and / or transferring and exhausting process gases (not shown), which may be located on the alternate end from which the gas input occurs.

[0036] The paddle 106, reactor chamber door and seal 104, and substrate / wafer 105 can be moved into the reactor chamber 102 until the reactor chamber door and seal 104 is closed and sealed. The movement of the paddle 106 and the loading of the substrate / wafer 105 onto the boat and then onto the paddle 106 can be performed by a robotic machine (not shown) to minimize at least the introduction of defects (quartz dust) and human labor. The substrate / wafer 105 is now completely within the reactor chamber 102. At least the temperature of the substrate / wafer 105 can be allowed to equilibrate. Dopant gases and / or a mixture of single or multiple gases suitable for doping the substrate / wafer 105 can be introduced into the reactor chamber 102 via different MFCs. Note that these gases may be heated, or may be at about room temperature (to provide at least a portion of the desired pressurization from the fixed volume and heated gas), or may be at an elevated pressure, or the reactor chamber 102 internal volume of the full reactor process chamber 110 may be at some or all of the desired elevated pressure. Pressure adjustment can be achieved by moving the multi-way high-pressure valve 112 to the desired position and using a pressurizing pump 118 (using pressurized gas from the pump purge and pressure gas 116) with the pump-to-chamber valve 134 open. Alternatively, or in combination, the desired pressure may be achieved by using a piston 126 moved along the piston movement axis 120 by a solenoid or screw motor 124 to change volume (reducing V increases P for a given T) and thereby adjust the pressure of the internal volume of the full reactor process chamber 110. The pressure of the doping gas within the interior volume of the full reactor process chamber 110 will accelerate the probability of dopant atoms implanting into the surface and sidewalls of the structures (eg, interconnect lines, etc.) of the substrate / wafer 105 .

[0037] The acceleration of dopant atoms impinging on the surface of the substrate / wafer 105 and the resulting solid-state diffusion rate through portions of the substrate / wafer 105 can also be accelerated / increased by increasing the temperature of the substrate / wafer 105 and the dopant gas added into the interior volume of the full reactor process chamber 110 through the dopant process gas / mist inlet 108, at least via the chamber sidewall heater 130. Note: The dopant gas injected into the interior volume of the full reactor process chamber 110 through the dopant process gas / mist inlet 108 may be preheated or cooled if desired by engineering and chemical calculations and considerations. The temperature range at equilibrium of the interior volume of the full reactor process chamber 110, and at least the substrate / wafer 105, is from about 25°C to about 500°C with a uniformity of less than ±5°C. The interior volume of the full reactor process chamber 110 is designed to accommodate substrates / wafers 105 up to at least 450 mm in diameter for round wafers or up to 450 mm on a side for square / rectangular substrates. The pressure range of the interior volume of the full reactor process chamber 110 may be about 20 psi, about 30 psi, about 40 psi, about 50 psi, about 60 psi, about 70 psi, about 80 psi, about 90 psi, about 100 psi, about 110 psi, about 120 psi, about 130 psi, about 150 psi, about 200 psi, about 250 psi, about 300 psi, about 350 psi, about 400 psi, about 450 psi, and may be greater than about 500 psi or between 1 and 500 bar depending on engineering and design objectives, choices and considerations.

[0038] Gas pressure acceleration of dopant migration can be achieved in at least four ways: 1) by heating gas within at least the fixed volume of the reactor process chamber 110; 2. by adding additional gas molecules to at least the fixed volume of the reactor process chamber 110; 3. by reducing the combined volume of the reactor process chamber 110 and the piston chamber volume 114 ("piston-type"); and 4. by using a pressure / exhaust pump 118 to pump gas through / from a pump purge and pressure gas 116, thereby increasing the pressure within at least the reactor process chamber 110.

[0039] The supply of dopants into the interior volume of the full reactor process chamber 110 can include a gas panel 140 and a cleanroom gas service facility 158. While gas dopant delivery is shown in FIG. 1 , liquid dopants can also be delivered to the full reactor process chamber 110 by bubbling a carrier gas, such as at least N, Ar (non-reactive), or a reactive carrier gas, such as O, with a liquid dopant, such as POCl. A typical gas panel can include a set of MFC ISO valve-output 146, MFC (mass flow controller) 148, MFC ISO valve-input 150, gas regulator 152, and particle filter 154. Each “line” of these components can be supplied with dopant gas from a dopant 1 gas cylinder 156 and a dopant 2 gas cylinder 157, which can be located within the cleanroom gas service facility 158. If desired, additional mechanisms 132 for gases 3 and 4 can include liquid dopants as well as solid dopants (e.g., a powder may be heated to release the dopant metal, and then an inert carrier gas may "carry" the dopant injection gas) to the dopant gas mixing block 142 and ultimately to the dopant process gas / mist inlet 108 into the interior volume of the full reactor process chamber 110.

[0040] For the example materials used herein, the doping process can proceed as follows: The substrate / wafer 105 is loaded onto the paddle 106, and then the entire assembly is moved and loaded into the interior volume of the reactor chamber 102 and full reactor process chamber 110. The substrate / wafer 105 has an MLG interconnect layer lithographically patterned as needed, and the MLG is etched to expose the MLG sidewalls for intercalation doping. Dopant gases, such as PH3 and O2, can be flowed to fill the interior volume of the full reactor process chamber 110, for example, while the reactor chamber temperature is equilibrated at, for example, about 400°C. The pressure can be made appropriate for the MLG interconnect line size on the substrate / wafer 105. The pressure in the interior volume of the full reactor process chamber 110 can be held for a period of time, typically 10-60 minutes or even longer, again depending on engineering calculations and considerations, to dope MLG lines of various geometries to the desired sheet resistance. The pressure is reduced, the tube is purged of dopants and reactive gases, and the paddle 106 can then be safely removed from the reactor chamber 102 and the substrate / wafer 105 can be removed for further processing.

[0041] Alternative embodiments of large area / wafer scale low temperature / BEOL compatible highly scalable doping tool: batch / single; dopant = solid / liquid vaporized to gas; substrate pressurization = gas

[0042] FIG. 1B shows a schematic diagram of an exemplary batch (although the apparatus can also accommodate single wafers / substrates) doping apparatus and an exemplary process. FIG. 1B and the embodiments therein have aspects of the embodiment of FIG. 1A therein. For example, doping of graphene / MLG by, for example, solid / liquid phase doping (vaporized to gas) using gas pressure and temperature acceleration, particularly, but not limited to, intercalation doping of MLG, can be described. This process and apparatus are not limited to intercalation doping of MLG only, and many materials can be doped with this apparatus using other methods.

[0043] As shown in FIG. 1B, a batch (although single substrate / wafer processing is also possible) process tool 101 includes, but is not limited to, at least a reactor chamber 102 (dashed section), a reactor chamber door and seal 104, a substrate / wafer 105, a paddle 106, a dopant process gas / mist inlet 108, the volume of the full reactor process chamber 110, a multi-way high pressure valve 112, a piston chamber volume 114, a pump purge and pressure gas 116, a pressurization / evacuation pump 118, a piston movement shaft 120, a piston chamber 122, a solenoid or screw motor 124, a piston 126, a chamber sidewall heater 130, a temperature control for the solid source 131, additional mechanisms for gases 3 and 4, if needed, 132, a pump-to-chamber valve 134, a solid source-to-chamber valve 135, a gas panel 140, a dopant gas mixing block 142, and an MFC. It may include an ISO valve-output 146, an MFC (mass flow controller) 148, an MFC ISO valve-input 150, a gas regulator 152, a particulate filter 154, a dopant 1 gas cylinder 156, a dopant 2 gas cylinder 157, a clean room gas service facility 158, a solid source crucible 160, and a solid / slurry / liquid source material 162.

[0044] The reactor chamber 102 can include both a sealed steel pressure vessel capable of withstanding the applied pressure and temperature, and a tubular liner, which can be made of materials such as high-quality, high-purity quartz. The reactor chamber 102 can include openings, such as a reactor chamber door and seal 104, a dopant process gas / mist inlet 108 (which may be integrated with a high-pressure shut-off valve), and one or more openings for pressurization equipment through a multi-way high-pressure valve 112 (and one possible placement of solid / slurry / liquid source material 162 through a solid-source-to-chamber valve 135). The reactor chamber door and seal 104 can be opened (after the reactor chamber 102 has been evacuated of toxic / reactive gases and then brought to atmospheric pressure), and the substrates / wafers 105 can be loaded onto a paddle 106, which can include a quartz “boat” (not shown) with slots to hold the substrates / wafers 105 in a desired position, typically parallel with spacing determined by uniformity requirements from engineering calculations and considerations.

[0045] However, there are many options for how to hold and process substrates and wafers. In this illustrative FIG. 1B , the batch processing apparatus 100 is shown in a horizontal configuration. As an alternative, additional embodiments, the batch processing apparatus 100 can be rotated 90 degrees in the z-direction to become a vertical high-pressure processing chamber. The reactor chamber 102 can include a system for mixing input gases (perhaps a dopant gas mixing block 142) and / or for providing process gas (not shown) movement and exhaust (and purging gas during idle or door-open conditions), which may be located on an alternate end from which the gas input occurs. The dopant process gas / mist inlet 108 can have many alternative configurations, such as a showerhead, quartz injector, heating or cooling gas tubing, etc., due to engineering and chemistry considerations and choices.

[0046] The paddle 106, reactor chamber door and seal 104, and substrate / wafer 105 may be moved into the reactor chamber 102 until the reactor chamber door and seal 104 is closed and sealed. Manual and / or automatic latches, cogs, or the like (not shown) may be used to provide a mechanical seal of sufficient strength for the reactor chamber door and seal 104 to maintain reactor chamber 102 pressure and for safe operation. The movement of the paddle 106 and the loading of the substrate / wafer 105 onto the boat and then onto the paddle 106 may be performed by a robotic machine (not shown) to minimize at least the introduction of defects (quartz dust) and human labor. The substrate / wafer 105 is now completely within the reactor chamber 102. At least the temperature of the substrate / wafer 105 may be equilibrated.

[0047] Dopant gases and / or mixtures of gaseous mixtures containing liquids suitable for doping the substrate / wafer 105 can be introduced into the reactor chamber 102 via different MFCs. Note that these gases may be heated, or may be at about room temperature (to provide at least a portion of the desired pressurization from a fixed volume and heated gas), or may be at elevated pressure, or may place the reactor chamber 102 internal volume of the full reactor process chamber 110 at some or all of the desired elevated pressure. Pressure adjustment can be achieved by moving the multi-way high-pressure valve 112 to the desired position and using a pressure pump 118 (using pressurized gas from the pump purge and pressure gas 116) with the pump-to-chamber valve 134 open. Alternatively, or in combination, the desired pressure can be achieved by using a piston 126 moved along the piston movement axis 120 by a solenoid or screw motor 124 to change volume (reducing V increases P for a given T) and thereby adjust the pressure of the internal volume of the full reactor process chamber 110.

[0048] The pressure of the doping gas within the interior volume of the full reactor process chamber 110 accelerates the probability of dopant atom implantation into the surface and sidewalls of the structures (e.g., interconnect lines, etc.) of the substrate / wafer 105, along with sources coming from solids or liquids in contact with the superstructure of the substrate / wafer 105. For example, a doped SOG (e.g., P-SOG, B-SOG, BP-SOG, etc.) can be applied to the substrate / wafer 105 prior to the T and P acceleration of the tool process apparatus 101. For example, a solid layer saturated or nearly saturated with the desired dopant atoms can be deposited on the substrate / wafer 105 before it is processed in the process apparatus 101. Additionally, the formation of a doped layer covering at least the substrate / wafer 105 can be part of a process within the process apparatus 101, such as bubbling a carrier gas with O2 plus POCl3 flowed into the reactor chamber 102 to form a deposited phosphorus-doped glass (PSG) deposited on the substrate / wafer 105 and on the interior surfaces of the reactor chamber 102. Alternatively, a solid dopant, such as arsenic or FeCl powder or slurry, as a solid / slurry / liquid source material 162 may be placed in the solid-source crucible 160 and then appropriately heated by the solid-source temperature control 131 to outgas and thereby achieve solid-source doping via gaseous means by temperature and pressure acceleration. The solid / slurry / liquid source material 162 may optionally be placed within the reactor chamber 102, although separate temperature control of the solid / slurry / liquid source material 162 is thereby lost. Note that significant pressure can be achieved simply by heating gas within the fixed volume of the closed / isolated reactor chamber 102.

[0049] Increasing the temperature of the substrate / wafer 105 and dopant gas can also accelerate / increase the acceleration of dopant atoms impinging on the surface of the substrate / wafer 105 and the resulting solid-state diffusion rate through a portion of the substrate / wafer 105. These are added through the dopant process gas / mist inlet 108 into the interior volume of the full reactor process chamber 110, which is heated by at least the chamber sidewall heater 130. Note: The dopant gas injected into the interior volume of the full reactor process chamber 110 through the dopant process gas / mist inlet 108 may be preheated or cooled if desired by engineering and chemical calculations and considerations. The temperature range at equilibrium of the interior volume of the full reactor process chamber 110, and at least the substrate / wafer 105, is from about 25°C to about 500°C with a uniformity of less than ±5°C. The interior volume of the full reactor process chamber 110 is designed to accommodate substrates / wafers 105 up to at least 450 mm in diameter for round wafers or up to 450 mm on a side for square / rectangular substrates. The tool process equipment 101 may be modified to accommodate substrates in continuous format. The pressure range of the interior volume of the full reactor process chamber 110 may be about 20 psi, about 30 psi, about 40 psi, about 50 psi, about 60 psi, about 70 psi, about 80 psi, about 90 psi, about 100 psi, about 110 psi, about 120 psi, about 130 psi, about 150 psi, about 200 psi, about 250 psi, about 300 psi, about 350 psi, about 400 psi, about 450 psi, or even greater than about 500 psi, or 1-500 bar, depending on engineering and design objectives, choices, and considerations.

[0050] The supply of gases and material dopants that can form solids / liquids (glass is simply a viscous liquid) as dopants into the interior volume of the full reactor process chamber 110 can include a gas panel 140 and a cleanroom gas service facility 158. While gas dopant delivery is shown in FIG. 1B , liquid dopants can also be delivered to the full reactor process chamber 110 by bubbling a carrier gas, such as at least N or Ar (non-reactive), or by including a reactive carrier gas, such as O, with a liquid dopant, such as POCl. A typical gas panel can include a set of MFC ISO valve-output 146, MFC (mass flow controller) 148, MFC ISO valve-input 150, gas regulator 152, and particle filter 154. Each “line” of these components can be supplied with dopant gas from an exemplary Dopant 1 gas cylinder 156 and an exemplary Dopant 2 gas cylinder 157, each of which can be located within the cleanroom gas service facility 158. If desired, the additional mechanism 132 for gases 3 and 4 can further include liquid dopants as well as solid dopants (e.g., a powder may be heated to release the dopant metal, and then an inert carrier gas may "carry" the dopant injection gas) to the dopant gas mixing block 142 and ultimately to the dopant process gas / mist inlet 108 into the interior volume of the full reactor process chamber 110.

[0051] In one example of materials used herein to form MLGs followed by intercalation doping, the doping process can proceed as follows: The substrate / wafer 105 is loaded onto the paddle 106, and then the entire assembly is moved and loaded into the interior volume of the reactor chamber 102 and full reactor process chamber 110. The substrate / wafer 105 has an MLG interconnect layer lithographically patterned as needed, and the MLG is etched to expose the MLG sidewalls for intercalation doping. Dopant gases, such as PH3 and O2, can be flowed to fill the interior volume of the full reactor process chamber 110, and can be configured to form a doped glass, with the reactor chamber temperature equilibrated at, for example, about 400°C. The pressure can be appropriate for the interconnect line size of the MLGs on the substrate / wafer 105. (See at least four methods of pressure increase in the preceding paragraphs of this specification.) The pressure in the internal volume of the full reactor process chamber 110 may be held for a period of time typically between 10 and 60 minutes or even longer, again depending on engineering calculations and considerations, to dope MLG wires of various geometries to the desired sheet resistance. The pressure is reduced, the tube is evacuated / purged of dopants and reactive gases, and the paddle 106 can then be safely removed from the reactor chamber 102 and the substrate / wafer 105 can be removed for further processing.

[0052] Another example of a large-area / wafer-scale low-temperature / BEOL-compatible highly scalable doping tool: Platen - single / multiple; Dopant = solid / liquid vaporized to gas; Substrate pressurization = gas

[0053] 2 shows an exemplary schematic diagram of one embodiment of a non-contact pressure system using a solid / liquid dopant (vaporized to a gas) and piston-type generation of gas pressure with a horizontal single or multi-wafer / substrate platen. The exemplary piston-type gas pressure generation system 200 can include, but is not limited to, a substrate / wafer 202, a slit 206, a process chamber volume 204, a heated bottom disk 208, a valve 207, a piston 218, a minimum volume process chamber 210, a solenoid or screw motor 212, a piston volume 214, a piston movement shaft 220, a chamber sidewall heater 230, a solid source temperature control 231, a solid source-to-chamber valve 235, a solid source crucible 260, and a solid source material 262. The exemplary piston-type gas pressure generation system 200 can also include a gas system depicted in small blue shading, which can be similar to that shown in FIG. 1B.

[0054] The exemplary piston-type gas pressure generation system 200 uses composite gas laws to allow a machine operator, typically via software control means, to manipulate volume and temperature to affect pressure applied to the top surface of a substrate / wafer 202, which can accelerate the diffusion of dopant atoms or molecules through a material that is desired to be doped, for example, graphene, such as a single-layer or few-layer graphene structure or a multi-layer graphene (MLG) structure. The doping of the graphene layer can be from the sidewalls of the graphene wire or ribbon structure to achieve more efficient and effective doping, primarily by intercalation doping.

[0055] As described in more detail herein, the substrate / wafer 202 enters the minimum volume process chamber 210 through a slot 206 and can be placed on a heated bottom disk 208. Thermal control of the wafer and gases can be achieved by at least the heated bottom disk 208 and various chamber sidewall heaters 230, selected through engineering choices and considerations / trade-offs. Alternative methods of heating the gases and wafers can include, for example, heat lamps. The heated bottom disk 208 can include a rotation feature to enable improved temperature uniformity for thermal processes, which can include doping processes, the use of intercalating agents, and some film formation processes. This rotation feature of the heated bottom disk 208 can be combined with most any of the non-contact pressure features to achieve doping processes, such as diffusion acceleration of diffusion couples and intercalation doping. In this disclosure, the terms process chamber and reactor chamber may be used interchangeably.

[0056] The pressure on the substrate / wafer 202 can be controlled by the piston system (and the pressure that increases as the gas heats up within a fixed volume) shown in Figure 2. The process chamber volume 204 plus the piston volume 214 can be changed from its initial volume (204 + 214) to its final volume (204 + 214 - the volume at which the piston 218 is inserted) by moving the piston 218 along the piston movement axis 220 with a solenoid or screw motor 212. This changes the total volume without increasing the size of the container walls, thus increasing the pressure in the process chamber volume 204 and the piston volume 214.

[0057] Another exemplary operation of the process chamber 210 will now be described. A clean, dry substrate / wafer 202 can be placed onto the heated bottom disk 208 through the slit 206. A small vacuum pump (not shown) can bring the process chamber 204 to 100-300 millitorr (mtorr), and the heated bottom disk 208 can bring the substrate / wafer 202 to approximately 200°C to dry the wafer. The vacuum pump (not shown) can also be used to firmly maintain the wafer / substrate 202 on the heated bottom disk 208 and assist in the substrate / wafer 202 dehydration process. The substrate / wafer 202 can have a dopant layer already deposited thereon, or the piston-type gas pressure generation system 200 can be configured to deposit a doped layer, such as POCl3-doped SiO2, as described in more detail herein at least in the description of FIG. 1B. Gas pressure, in addition to temperature, can then be used to accelerate the migration of dopant atoms from the doping layer of the wafer 202 through the material being doped, e.g., single-crystal silicon or MLG. The temperature and duration of applied gas pressure can be controlled to result in the desired dopant migration. As described herein at least in FIG. 1A, dopant delivery to the surface of the substrate / wafer 202 can be provided from a gas (not shown in FIG. 2 but shown in FIG. 1) injected into the reactor chamber 210. The gas and / or the reactor chamber can be pressurized to increase the probability that the dopant atoms will be on the substrate / wafer 202 surface and implant and diffuse into the desired superstructure, region, or layer of the wafer / substrate 202. Note: The heated bottom disk 208 may be configured as a multi-wafer / substrate holder, such as a wafer platen, to process multiple wafers simultaneously, thereby increasing the productivity of the tool (see partial top-down breakout view).

[0058] Additionally, other embodiments of the present invention include a vertical orientation of the pressurized cylinder piston volume 214 and moving piston 218, rather than horizontal as in the example shown in FIG. 2. Furthermore, the pressurized cylinder piston volume 214 and moving piston 218 may be positioned directly above each wafer / substrate 202 and heated bottom disk 208, similar to the large internal combustion engine cylinders in, for example, a six-cylinder automobile engine. An exemplary schematic diagram of one embodiment of one such non-contact pressure system using a piston-cylinder above the substrate / wafer for gas pressure generation, with gas / solid / liquid dopants and a single or multi-wafer / substrate platen, as shown in FIG. 2A, illustrates a portion of the overall tool. The embodiment of FIG. 2A can include many of the embodiments of both FIG. 2 and FIG. 1B.

[0059] An exemplary piston-cylinder gas pressure generation system 299 may include, but is not limited to, a substrate / wafer 202, a slit 206 (see FIG. 2), a process chamber / reactor interior volume 204, a heated bottom disk 208, a valve 207 (see FIG. 2), a piston 266, a solenoid or screw motor 268, a shaft 264 from the piston 266 to the motor 268, a piston movement direction 270, a process chamber sidewall 262, a chamber sidewall heater 230 (see FIG. 2), a heated bottom disk 208 shaft 280, a heated bottom disk 208 support structure 278, solid vaporization structures 235, 231, 260, 262 (see FIG. 2), a main substrate / wafer 272, a dopant layer 276 (optional), an exemplary structure to be doped 274 (or a substrate of interest such as glass), and a substrate (typically silicon) 272. The example piston-cylinder gas pressure generation system 299 may also include a gas system depicted in small blue shading, which may be taken from and similar to FIG. 1B, as well as a pump and solid / slurry / liquid dopant source section depicted in small blue shading, which may be taken from and similar to FIG. 1B.

[0060] The optional dopant layer 276 (if configured for solid / liquid doping) may be formed by depositing a heavily doped layer used as a dopant source (e.g., POCl) via a doped CVD or PECVD process, for example, in a diffusion tube. The optional dopant layer 276 may also be formed by depositing a thin layer of oxide and doping the oxide via a PLAD process or conventional ion implantation. The optional dopant layer 276 may also include a spin-on layer of doped glass (d-SOG) or other organic material, which may or may not be baked and outgassed before applying pressure, thereby remaining “soft.” An exemplary doped structure 274 may include an MLG interconnect structure after etching and cleaning, such that the MLG edges are exposed to the optional dopant layer 276 or a bare, exposed structure exposed to the process chamber / reactor interior volume 204. NOTE: Figure 2A shows only the process reactor / chamber portion of the tool / apparatus and can be combined with portions of Figure 2 to show a substantially complete tool-level schematic.

[0061] A typical process flow using the tool of Figures 2A+2 may include the following: A substrate / wafer 202 may be placed on the heated bottom disk 208 through the slits 206 with the pins raised (not shown). The pins may be retracted, bringing the backside of the substrate / wafer 202, the main substrate / wafer 272, into firm contact with the heated bottom disk 208. At least the process chamber sidewalls 262 and piston 266 are retracted upward so as not to interfere with the loading of the substrate / wafer 202. At least the process chamber sidewalls 262 are then lowered to contact and seal with the heated bottom disk 208. (This sealing may be less important by having a pressure chamber that encloses most of the exemplary piston-cylinder gas pressure generation system 299.) During the doping layer deposition step, a gap between the process chamber sidewalls 262 and the heated bottom disk 208 may be left intact. The process chamber / reactor internal volume 204 can be purged, evacuated, and cycled as dictated by engineering data and preference. A heated bottom disk 208 and chamber sidewall heaters 230 can bring the substrate / wafer 202 to a desired temperature. A piston 266 can be moved by a solenoid or screw motor 268 via a shaft 264 from the piston 266 to the motor 268 to reduce the volume of the process chamber / reactor internal volume 204 and thereby increase the gas pressure within the process chamber / reactor internal volume 204 and on the top surface of the optional dopant layer 276 or, in the case of direct gas doping, on the example structure to be doped 274. The position of the piston 266 can be adjusted to obtain the desired pressure in the process chamber / reactor internal volume 204 and on the top surface of the example structure to be doped 274 or on the example dopant layer 276. This can be maintained or adjusted by varying the applied pressure, by oscillating or moving the piston 266 to achieve the desired pressure (and temperature) acceleration of doping of the example structure to be doped 274.

[0062] Another example of a large-area / wafer-scale low-temperature / BEOL-compatible highly scalable doping tool: Platen - single / multiple; Dopant = gas, vaporized to gas, or non-vaporizable solid / liquid; Substrate pressure = direct contact mechanical

[0063] 3 shows a schematic diagram of an exemplary batch (although the apparatus can also accommodate single wafers / substrates) doping apparatus and an exemplary process for introducing gases into a process chamber 310 to dope an exemplary substrate / wafer 202 and using mechanical pressure and temperature to accelerate the doping process. The mechanical pressure in this exemplary tool / apparatus 300 is by direct contact mechanical pressure. While the exemplary substrate / wafer 202 can include many materials in many different compositions susceptible to doping, the example used is the substrate / wafer 202 as a single crystal silicon wafer with a thick oxide structure formed thereon with openings etched down to the silicon. The in-situ doping tool / apparatus 300 includes at least, but is not limited to, a heated top disk 340, a heated bottom disk 208, a process or reactor chamber 310, a substrate / wafer 202 comprising silicon with an oxide structure on a top layer, a motor 302, a mechanical / turbo pump 304, a shaft 305 from the motor 302 to the top disk 340, a control valve 306, an exhaust section 308, a purge section 311, a bottom heating power supply 350, a shaft 354 from the bottom heating power supply 350 to the heated bottom disk 208, a gas showerhead 312, a dopant gas mixing block 314, an MFC ISO valve-output 316, an MFC (mass flow controller) 318, and an MFC It may include an ISO valve-input 320, a gas regulator 322, a particle filter 324, a dopant 1 gas cylinder 326, a dopant 2 gas cylinder 327, a cleanroom gas service facility 328, a gas panel 330, and additional features for gases 3 and 4, if needed. This example apparatus and process involves introducing a carrier gas with a dopant into the chamber at an appropriate pressure to allow diffusion / migration of the dopant into the silicon oxide structure. This can be done directly in the process chamber of the present disclosure with top and bottom heating disks or in another one of the chamber embodiments described herein.If a plasma is required to enhance the process, an electrode can be provided on each disk to accomplish this, or a remote / downstream plasma source can be considered. This above-described approach can also be implemented in other chamber embodiments described in this application (e.g., the pressurized batch chamber in at least FIG. 1 herein).

[0064] For example, by additional dopant insertion into the top single-crystal silicon surface via physical contact with a solid dopant material (as is traditionally done in the industry with a boron disk in contact with Si for boron doping). Again, a solid dopant disk (similar in function to optional dopant layer 276) can be placed, for example, in a chamber with top and bottom heaters after the wafer with the single-crystal silicon and oxide structure is placed therein. The solid dopant disk can be placed on top of the wafer on which the single-crystal silicon and oxide structure is formed. Next, the upper heater disk is first gently applied, then increased to the desired pressure, to press the doped disk against the front (top) surface of substrate / wafer 202. The pressure level is set to a value that optimizes dopant diffusion. Heaters and electric fields (not shown) can be applied as needed to facilitate the process. As shown at least in FIG. 2A and related specification herein, if a liquid or solid dopant source is desired to be used, the substrate / wafer 202 can include at least a dopant layer 276 (optional), an exemplary structure 274 to be doped (or a substrate of interest such as glass), and a substrate (typically silicon) 272.

[0065] The pressure on the substrate / wafer 202 can be achieved mechanically by pressing a heated top disk 340 against the top of a solid dopant disk over the structures desired to be doped, such as the exemplary MLG interconnect structures described herein and this embodiment of single crystal silicon and oxide structures, thereby forcing the dopants into the device single crystal silicon and oxide structures and regions. High temperatures, as described above, can also be applied to help induce doping of the desired single crystal silicon and oxide structures and regions. This process may be subject to stringent surface cleaning requirements and may be more defect-prone than the more advanced doping processes disclosed herein. The solid dopant disk may comprise a layer of a relatively softer doped material, e.g., PECVD BPSG or PSG, or a doped SOG (spin-on-glass) layer that is soft enough to be pressed into the spaces between the exposed interconnect lines of the substrate / wafer 202 containing a molecular alignment material, e.g., MLG, from pressure applied by, e.g., the heated top disk 340, so as to promote some intercalation doping from / through the sidewalls of the MLG interconnect lines.

[0066] Illustrative Embodiments Other reactor configurations are now described that provide other forms of heat and / or pressure on the substrate. Note that the above configuration is only one of many. Alternative configurations may include, among others:

[0067] - a heated membrane subjected to high pressure (for example air or water pressure),

[0068] - Clamshell configuration with high temperature and pressure heating N2, Ar, other such gases,

[0069] - A large batch reactor with the same characteristics as those described above

[0070] - Clamshells that can use a combination of the techniques detailed above to heat and pressure the substrate, for example, hot pressurized gas can be supplied, high pressure can be supplied with a bottom heater used to heat the substrate, the bottom heater heats the hot gas to perform the pressure function and maintain the temperature, etc.

[0071] - a quartz body having an inductively heated substrate placed on a susceptor, the pressure load being achieved using high-pressure gas; and

[0072] - An array of lamps may also be included in the quartz body for final temperature control.

[0073] Each section below presents a particular sequence of operations for the system and the desired material structure, composition, etc. parameter ranges for optimal process results.

[0074] It should be noted that the reactor can be implemented as a batch reactor and / or a single substrate (wafer) reactor. It should be noted that the single substrate configuration allows for finer substrate-to-substrate process control than a batch reactor. A method for producing batch processing with a single wafer architecture can also be achieved by employing a stack of wafers between two heaters.

[0075] Alternative Doping Methods Because the chamber infrastructure allows for such operation, other disclosed equipment systems can also be used to introduce dopants into wafers and structures on / within the wafer. This document lists at least six methods of material carrier doping: 1) boron or nitrogen substitutional doping, 2) alkali metal atom deposition, 3) absorption of gases such as NO2, 4) charge transfer from conjugated organic molecules, 5) solution-phase interaction of graphene molecules with dopant molecules, and 6) spin-coating of a mixture of, for example, TCNQ and PMMA. References in the above doping list include at least Hans He et al., "Uniform doping of graphene close to the Dirac point by polymer-assisted assembly of molecular dopants," Nature Communications, 27 September 2018, pp. 1-7, and V. Narendar, et al., "First Principle Study of Doped Graphene for FET Applications," Silicon vol. 11, pp. 277-286 (2019), and R. Ishikawa, et al., "Doping graphene films via chemically mediated charge transfer," Nanoscale Research Letters, vol. 6, pp. 111-116 (2011), all of which are incorporated by reference in their entirety.Intercalation doping has been described at least in W. Liu, J. Kang, and K. Banerjee, "Characterization of FeCl3 Intercalation Doped CVD Few-Layer Graphene," IEEE Electron Device Letters, Vol. 37, No. 9, pp. 1246-1249, September 2016, and J. Jiang, JH Chu, and K. Banerjee, "CMOS-compatible doped-multilayer-graphene interconnects for next-generation VLSI," IEEE IEDM, 2018, pp. 34.5.1-34.5.4, the entire contents of which are incorporated by reference. Many of these may not be practical for certain types of doping challenges, such as charge transfer due to surface absorption doping.

[0076] Intercalation doping applications generally require access to the "edges" of layered structures because doping directly through the dense matrix of layered atoms is extremely difficult. Therefore, the desired lithography and etching processes for that particular interconnect layer using layered materials, such as graphene / MLG, can be performed. The wafer can then be cleaned, and a layer of dopant source can be deposited in a separate machine or within the process chamber of the apparatus described herein. The apparatus of the present disclosure can then be used to drive dopants into the exposed MLG sidewalls using the temperature and pressure capabilities of the apparatus described herein. The wafer can then be removed from the process chamber, and the dopant layer can be selectively removed, or, depending on the application, left on the wafer as a capping layer to mitigate dopant outdiffusion from the MLG lines.

[0077] The apparatus described at least in FIGS. 1-3 can include a transfer chamber for loading substrates / wafers X02 into the reactor / process chamber and can be used to pretreat the substrates / wafers X02 before they are moved from the transfer chamber to the reactor / process chamber. Substrate / wafer X02 pretreatment can include, for example, rotational and / or translational movement of the wafer to correct the alignment of a "notch" or "flat" or some other substrate (wafer) crystal orientation marking for aligning the wafer to a fixed or variable position before transfer into the reactor / process chamber. Wafer pretreatment can include heating the wafer, perhaps to dry moisture from the wafer and / or to prepare the wafer's temperature so that the process occurring in the reactor / process chamber can be shortened or enhanced by the increased heat. Wafer pretreatment can include purging the transfer chamber with an inert gas, such as N, Ar, or He, or a reactive gas, such as O or O. Wafer pre-treatment can include various exposures to the electromagnetic spectrum, e.g., UV, X-ray, IR, etc., that can be used to activate or excite certain atoms, e.g., RTA (Rapid Thermal Anneal) or RTO (Rapid Thermal Oxide). Wafer pre-treatment can include exposing the wafer to plasma, e.g., to clean the wafer surface or to chemically activate portions of the wafer surface for other processing (e.g., growing an oxide, passivating the wafer surface, etc.).

[0078] Various combinations or subcombinations of at least the pre-treatment options disclosed above can be used to effect the pre-treatment, such as heating the wafer and exposing the wafer to UV light using an O2 or O3 purge / atmosphere to form a thin oxide film on some or all of the wafer's surface (oxidizing, reducing atmospheres are also useful, particularly for wafer cleaning).

[0079] A "substrate / wafer" can include a variety of sizes (e.g., diameters of about 450 mm, about 400 mm, about 300 mm, about 200 mm, about 150 mm, etc.). A substrate / wafer can include, for example, circular, square, rectangular, or other overall shapes (disregarding cutouts, flats, etc.) when viewed from above the substrate / wafer. Substrate / wafer compositions can include materials such as, for example, crystalline materials such as elemental silicon, germanium, and aluminum, copper alloys, SiGe, aluminum, h-BN, various glasses (amorphous or crystalline), amorphous forms of Si, Ge, etc. A substrate / wafer can include multiple materials, for example, SOI (silicon on insulator), GeOI, etc. An operator / user / robot can place the wafer / substrate into the transfer chamber. The machine can be configured to perform this loading automatically, including the use of wafer containers such as FOUPs.

[0080] The reactor / process chamber and the transfer chamber can be connected via a slit structure. The machine control software can be configured to automatically open the slit once the pressures inside the two chambers are equalized. The apparatus may also include a hardwired backup control system with redundant pressure transducers to ensure safe transfer of the wafer only when the pressures in the reactor / process chamber and the transfer chamber are equal.

[0081] In addition to accelerating dopant diffusion, the reactor / process chamber can also serve as the primary chamber (or reactor) for the growth or deposition of various layers on the wafer, such as doping layers. However, the growth of many materials, such as graphene (and / or other carbon materials), requires dedicated chambers due to contamination and particle issues. Substrates slightly larger than 450 mm in size can be placed in the reactor / process chamber. The reactor / process chamber can be equipped with a heater system for heating the reactor / process chamber interior walls, which not only accommodates process requirements but also makes cleaning maintenance easier or less frequent. Depending on the process details, gases used, and other engineering considerations, the reactor / process chamber interior walls may also include a cooling system to suppress bypass deposition of process gas reactions, thereby enabling longer chamber cleaning maintenance cycles and suppressing in-situ process and film defects due to particle deposition from the interior walls that are dropped or blown onto the wafer from the process gas flow.

[0082] A heated top plate or disk can also be disposed in the reactor / process chamber (see, e.g., heated top disk 340). The heated top disk 340 and / or heated bottom disk 208 can include their own heating mechanism (e.g., heating power supply 350 shown for bottom disk 208). In this manner, both the lower disk, on which the wafer rests, and the heated top disk can be independently heated and have separate temperature control by machine software. For example, the lower disk can be heated while the top is maintained at approximately room temperature (or vice versa). The heated top and / or bottom disks can also be configured to include independently controllable zones on the disk, e.g., concentric rings of different temperature control, pizza-like slices as temperature-controlled zones, etc. Combinations of the above are also possible.

[0083] The linear surfaces (which cover the disks, e.g., the heated top disk 340 and / or the heated bottom disk 208, and the interior walls of the reactor / process chamber 310) can be formed of graphite, although other materials, such as aluminum nitride, quartz, and silicon carbide-coated graphite, are also possible. Several such materials are contemplated, generally speaking, materials that allow for high heat conduction and pressure distribution. Particle formation is also affected by surface finish, adhesion of deposited films, thermal expansion coefficients, and the like. The reactor / process chamber 310 and the like described herein may also include the capability to ignite plasmas, e.g., using NF3 and Ar, to provide an in-situ internal chamber surface cleaning procedure, which can be useful in minimizing particulate contamination or the formation of embedded film defects on the wafer surface, thereby extending chamber maintenance cycles.

[0084] A mechanical / turbo pump 304 can be used to control the pressure in the reactor / process chamber 310 and / or the transfer chamber (not shown). The mechanical pump reduces the pressure in the reactor / process chamber (e.g., 10 -3 torr). Turbo pumps can be used to further reduce the pressure (e.g., 10 -7 torr), a more powerful pump may be used. Low pressure is desirable to purge impurities from the chamber during some periods of the operating cycle.

[0085] The heating power supply 350 can heat and control the temperature on the heated bottom disk 208. This can be done with ±5°C uniformity (and / or near-zero non-uniformity) across the heated bottom disk 208. The heated top disk 340 and the heated bottom disk 208 can each include multiple thermocouples or alternative temperature-sensing devices embedded within each disk to provide temperature input to a temperature control system, such as a proportional feedback control system. The heated bottom disk 208 can generate heat by resistive current from the heating power supply 212, or it can be water heated over some temperature range (not shown), or it can be heated by a lamp light source (not shown) positioned inside the reactor / process chamber 310 to illuminate at least the heated bottom disk 208.

[0086] The heated top disk 340 can move up and down along an axis 352 perpendicular to the bottom area surface of the heated top disk 340 and the top area surface of the heated bottom disk 208. The heated top disk 340 can have an independent heating source. The heated top disk 340 can be operated to generate mechanical pressure on the substrate / wafer, for example, by movement of a shaft 305, a motor, a screw jack, etc. Gas pressure can also be used in addition to or as an alternative to mechanical pressure. The purpose of the applied pressure is to enable higher dopant diffusion in the upper layer of the dopant in the substrate / wafer 202 or a higher diffusivity of the dopant into the base material of the substrate / wafer 202, such as single crystal silicon, SiO2 as glass (as a network modifier), etc.

[0087] At least Patent Application No. 63 / 123,587 and PCT / US Patent Application No. 21 / 61361, and at least the articles J. Jiang, et al., "Intercalation doped multilayer-graphene-nanoribbons for next generation interconnect," Nano Letters, 17(3), pp. 1482-1488, 2017; and J. Jiang, et al., "All-carbon interconnect scheme integrating graphene wires and carbon-nanotube-vias," IEEE IEDM, pp. 14.3.1-14.3.4, 2017; and J. Jiang, et al., "CMOS-Compatible Doped-Multilayer-Graphene Interconnects for Next Generation VLSI," IEEE IEDM, pp. 34.5.1-34.5.4, 2018; and K. Agashiwala, et al., "Reliability and Performance of CMOS-Compatible See "Multi-Level Graphene Interconnects Incorporating Vias" IEEE IEDM, 2020; and K. Agashiwala, et al., "Demonstration of CMOS-Compatible Multi-Level Graphene Interconnects with Metal Vias" IEEE Transactions on Electron Devices, vol. 68, No. 4, April 2021, pp. 2063-2091. All of the above are incorporated by reference in their entirety.

[0088] The heated top disk 340 can be moved to apply mechanical pressure to the substrate / wafer 202 while it is resting on the heated bottom disk 208. For example, this mechanical pressure can be about 20 psi, about 30 psi, about 40 psi, about 50 psi, about 60 psi, about 70 psi, about 80 psi, about 90 psi, about 100 psi, about 110 psi, about 120 psi, about 130 psi, about 150 psi, about 200 psi, about 250 psi, about 300 psi, about 350 psi, about 400 psi, about 450 psi, or even greater than about 500 psi, or 1-500 bar. While the heated top disk 340 applies mechanical pressure to the top surface of the substrate / wafer 202, the reactor / process chamber 310 pressure can be maintained at a low value, for example, 10 bar to prevent contamination of the diffusion process. -6 ~10 -7 The reactor / process chamber 310 pressure can be adjusted by at least a mechanical / turbo pump 216.

[0089] The pressure applied to the diffusion at the top surface of the substrate / wafer 202 can also be generated by alternative means, such as by using the reactor / process chamber 310 (or another sub-chamber therein) with pressure generated by high pressure gas applied to the interior of the reactor / process chamber 310. Another option is piston-type generation of gas pressure, which can result in a reduced particle count within the reactor / process chamber 310 and still be non-contact with the wafer top surface.

[0090] It should be noted that the substrate / wafer 202 may be compatible with a CMOS / BEOL thermal budget if it has a temperature below approximately 450°C. BEOL refers to the process steps, which are semiconductor integrated circuit fabrication steps that occur after front-end-of-line transistors are formed. After the fabrication steps build transistors on the wafer, subsequent processing steps must be within a thermal budget of approximately 450°C to avoid damaging the transistors and various junctions, which can result in shorts and reliability issues. Not all applications of the tools described herein may be subject to this temperature constraint. For example, doping junctions in single-crystal silicon, dopant diffusion through spacer materials, etc. are examples in semiconductor manufacturing where the temperature limits may be much higher, perhaps around 650°C or 900°C. Also, processing using glass substrates, such as those performed in tape-and-reel type layouts, may require temperatures above 450°C.

[0091] Reactor / process chamber pressure can be calibrated and monitored by using pressure sensors positionable on the steps of the pedestal, monitoring the current drawn by a motor that applies pressure between surfaces, using flexures configured as strain gauges embedded in wires, etc. Similarly, temperature can be monitored by using thermocouples and RTDs attached to the pedestal, using IR sensors, phosphorus-based sensors, and laser spectroscopy sensors for chemical and / or elemental analysis, etc.

[0092] conclusion Although the presently presented embodiments have been described with reference to specific exemplary embodiments, various modifications and changes can be made to these embodiments without departing from the broader spirit and scope of the various embodiments. Accordingly, the specification and drawings should be regarded in an illustrative rather than a restrictive sense.

Claims

1. 1. An intercalation doping device that facilitates the insertion of dopant atoms, ions, or molecules into a layered 2D material, comprising: A reactor chamber comprising: a single or multiple wafers or substrates are placed in the reactor chamber; applying a pressure in the range of 2 bar to 500 bar to at least one surface of said wafer or substrates; the single or multiple wafers or substrates have a diameter or side distance of 25 mm to 450 mm; the reactor chamber; A heater, the heater applies heat to the wafer or wafers or substrates; the single or multiple wafers or substrates have a temperature of 25°C to 500°C; The heater; A dopant addition device, the dopant addition device includes at least a valve and tubing for bringing dopant into the reactor chamber from the outside; the dopant addition device includes at least a dopant crucible disposed within the reactor chamber; the dopant comprises a solid, liquid, or gas phase material; the dopant comprises an intercalation dopant; the dopant adding device; An intercalation doping device comprising:

2. 10. The device of claim 1, wherein the intercalation doping refers to when atoms, molecules, or ions reversibly enter between layers of the layered 2D material.

3. The apparatus of claim 1 , wherein the pressure is applied in gas form.

4. The device of claim 1 , wherein the pressure is applied in a mechanical form.

5. The apparatus of claim 1 , wherein the reactor chamber is vertically oriented.

6. The apparatus of claim 1 , wherein the reactor chamber is oriented horizontally.

7. 10. The apparatus of claim 1, wherein the single or multiple wafers or substrates comprise single-layer, few-layer, or multi-layer graphene or other layered 2D materials.

8. 1. An intercalation doping device that facilitates the insertion of dopant atoms, ions, or molecules into a layered 2D material, comprising: A reactor chamber comprising: a single or multiple wafers or substrates are placed in the reactor chamber; applying a pressure in the range of 2 bar to 500 bar to at least one surface of said wafer or substrates; the single or multiple wafers or substrates have a diameter or side distance of 25 mm to 450 mm; the reactor chamber; A heater, the heater applies heat to the wafer or wafers or substrates; the single or multiple wafers or substrates have a temperature of 25°C to 500°C; The heater; A dopant addition device, the dopant addition device includes at least a valve and tubing for bringing dopant into the reactor chamber from the outside; the dopant addition device includes at least a dopant crucible disposed within the reactor chamber; the dopant comprises a solid, liquid, or gas phase material; the dopant comprises an intercalation dopant; the single or multiple wafers or substrates comprise single-layer, few-layer or multi-layer graphene strips; the dopant adding device; An intercalation doping device comprising:

9. 10. The device of claim 8, wherein the intercalation doping refers to when atoms, molecules, or ions reversibly enter between layers of the layered 2D material.

10. The apparatus of claim 8 , wherein the pressure is applied in gas form.

11. The device of claim 8 , wherein the pressure is applied in a mechanical form.

12. The apparatus of claim 8 , wherein the reactor chamber is oriented horizontally.

13. The apparatus of claim 8 , wherein the reactor chamber is vertically oriented.

14. The apparatus of claim 8 , wherein the single or multiple wafers or substrates comprise layered 2D material.

15. 1. A method of intercalation doping, the method comprising an apparatus for facilitating the insertion of dopant atoms, ions or molecules into layered 2D materials, the method comprising: providing a reactor chamber, a heater, and a dopant addition device; Providing a single or multiple wafers or substrates, the single or multiple wafers or substrates are placed in the reactor chamber; the single or multiple wafers or substrates have a diameter or side distance of 25 mm to 450 mm; providing said single or multiple wafers or substrates; applying heat to the wafer or substrates with the heater; applying heat to the wafer or substrates having a temperature between 25°C and 500°C; applying a pressure in the range of 2 bar to 500 bar to at least one surface of said wafer or substrates; the dopant addition device provides and / or contains dopants within the reactor chamber; the dopant comprises a substance in a solid, liquid, or gas phase; the dopant comprises an intercalation dopant; the single or multiple wafers or substrates comprise single-layer, few-layer or multi-layer graphene strips; applying pressure; treating said wafer or wafers or substrates at said temperature and said pressure in the presence of at least one of said intercalation dopants; A method comprising:

16. 16. The method of claim 15, wherein the intercalation doping refers to when atoms, molecules, or ions reversibly enter between layers of the layered 2D material.

17. further comprising treating said wafer or wafers or substrates in the presence of at least one of said intercalation dopants at said temperature and said pressure for a specified time; the specified time is at least half the maximum width of the graphene strip divided by the rate of intercalation doping; the rate of intercalation doping depends on the type of the at least one intercalation dopant used; the rate of intercalation doping depends on the temperature and the applied pressure; 16. The method of claim 15.

18. The method of claim 15 wherein the pressure is applied in gas form.

19. The method of claim 15 wherein the pressure is applied in a mechanical form.

20. 16. The method of claim 15, wherein the single or multiple wafers or substrates comprise layered 2D material.

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