High thermal resistance sandwiched structure and formation for electrostatic chucks

Abstract

The present invention includes a thermal resistant sandwiched structure and formation for electrostatic chucks. Embodiments also include a process for manufacturing an electrostatic chuck with improved interface integrity. The process can include a step of anodizing both surfaces of a plate and forming a dense layer of aluminum oxide (Al2O3). In aspects, the process uses a step of plasma electrolytic oxidation (PEO). In aspects, the electrostatic chucks described herein have a coating layer that includes Al2O3 (aluminum oxide), Y2O3 (yittrium oxide) and / or Er2O3 (erbium (III) oxide). The high thermal resistance sandwiched structure and formation for electrostatic chucks can form an ultra-stable interface between a ceramic and metal interface.

Description

HIGH THERMAL RESISTANCE SANDWICHED STRUCTURE AND FORMATION FOR ELECTROSTATIC CHUCKSTECHNICAL FIELD

[0001] The present disclosure relates generally to semiconductor manufacturing, and more specifically, to a substrate support assembly (also referred to as an electrostatic chuck assembly) that can be used for high temperature and high corrosive process environments.BACKGROUND

[0002] An integrated circuit (“IC” or microchip) is a set of electronic circuits on one small flat piece (or "chip") of semiconductor material, usually silicon. Large numbers of miniaturized transistors and other electronic components are integrated together on the chip. This results in circuits that are orders of magnitude smaller, faster, and less expensive than those constructed of discrete components, allowing a large transistor count.

[0003] Semiconductor device fabrication is the process used to manufacture semiconductor devices, typically integrated circuits (ICs) such as computer processors, microcontrollers, and memory chips that are common in electronic devices. It is a multiple-step photolithographic and physio-chemical process (with steps such as thermal oxidation, thin-film deposition, ion-implantation and etching) during which electronic circuits are created on a wafer, typically made of pure single-crystal semiconducting material. Silicon is typically used, but semiconductors of other compounds are used for specialized applications.

[0004] The fabrication process is performed in specialized semiconductor fabrication plants, also called foundries or "tabs," with the central part being the clean room. In more advanced semiconductor devices, such as modern 14 / 10 / 7 nm nodes, fabrication can take up to 15 weeks. Production in advanced fabrication facilities is typically automated and carried out in a hermetically sealed nitrogen environment to improveyield with automated material handling systems taking care of the transport of wafers from machine to machine. Wafers are transported inside special sealed plastic boxes referred to as FOUPs (Front Opening Unified Pods). All machinery and FOUPs contain an internal nitrogen atmosphere. The insides of the processing equipment and FOUPs is kept cleaner than the surrounding air in the cleanroom. Fabrication plants require large amounts of liquid nitrogen to maintain the atmosphere inside production machinery and FOUPs which are constantly purged with nitrogen.

[0005] An Electrostatic chuck (ESC) is a specialized type of clamp used to hold down or pick up objects (e.g., integrated circuits) by electrical force (i.e., attraction forces from static electricity). When the object is placed on an ESC and a bipolar voltage is applied to its internal electrodes, a directional electric field is created, and positive and negative charges drifts within the material to match the polarity of the chuck’s internal electrode. This attracting force between the ESC and the material is referred to as the electrostatic force and is the basic mechanism behind a chuck.

[0006] Electrostatic chucks are often used to hold substrates such as semiconductor wafers during portions of the manufacturing process (e.g., physical vapor deposition, etching and chemical vapor deposition). An electrostatic chuck includes a metal baseplate and a thin dielectric layer. The metal baseplate is maintained at a high- voltage relative to the wafer so that an electrostatic force clamps the wafer to it. Electrostatic chucks can have pins, or mesas, the height of which is included in the reported dielectric thickness.

[0007] The use of electrostatic chucks has obvious advantages over conventional physical or vacuum clamps. Electrostatic chucks reduce stress-induced cracks caused by mechanical clamping and allow larger areas of the substrate to be exposed for processing (i.e., without edge exclusion). They can be used in low pressure or high vacuum environments. Further, an electrostatic chuck can hold a substrate more uniformly to a chucking surface to allow a greater degree of control over substrate temperature. The use of ESC’s has become the prevailing configuration for processequipment that requires atomic precision, including plasma etch, chemical vapor deposition, ion implantation etc. The repeatability of ESC is critical to achieve the process precision within each wafer and from one wafer to another wafer.

[0008] A typical chuck includes aluminum oxide (AI2O3) plates. The conventional method of forming AI2O3 plates involves the use of a two-step sintering process. First, an AI2O3 powder is mixed with an organic binder and pressed into the desired shape. The shaped material is then sintered at a high temperature in an atmosphere of oxygen and / or ammonia to form a dense, homogeneous part. The sintered part is then machined to the desired size and thickness. Finally, the part is annealed at a lower temperature to form the desired crystalline structure of AI2O3. This process is expensive and entails long manufacturing processes. Moreover, it is difficult to produce multiple ESC’s with the same (or similar) characteristics. Further, ESC’s produced by conventional methods are heat sensitive (i.e., they are only effective within a narrow temperature range) due to the miss-match of thermal conductivity coefficient of the sintered materials to the metal baseplate.

[0009] Conventionally made chucks can display fluctuations or non-uniformities in the thickness of the dielectric layer above the electrode in spite of careful machining of the chucking surface. These fluctuations can adversely affect the operation of the chuck especially in the case of chucks for which the chucking force is inversely proportional to the square of the distance between the electrode and the workpiece. The chuck plates can produce an electrostatic force that is not uniform across its surface. Further, conventional chuck plates are only useful at certain temperatures.

[0010] Therefore, a need exists for electrostatic chucks that have more uniform chucking force across their chucking surface. There is also a need to reduce / abrogate the incidence of interface cracking between the ceramic and metal (e.g., AI2O3) interface of chucks.SUMMARY OF INVENTION

[0011] The following summary is provided to facilitate an understanding of some of the innovative features unique to the disclosed embodiment and is not intended to be a full description. A full appreciation of the various aspects of the embodiments disclosed herein can be gained by taking into consideration the entire specification, claims, drawings, and abstract as a whole.

[0012] Embodiments of the invention include a plasma electrolytic oxidation (PEO) coating. The coating can be used on electronic assembly components (e.g., electrostatic chucks). In aspects, the coating provides an ultra-hard surface, high electrical insulation and enhanced corrosion protection.

[0013] Embodiments also include a heat resistant sandwiched structure (i.e., surface coating) and formation for a substrate such as an electrostatic chuck. In aspects, the surface coating improves heat resistance (e.g., increases resistance to cracking and / or delamination caused by thermal cycling).

[0014] Embodiments also include a method of increasing the heat resistance at an interface (or coefficient of thermal expansion) between two surfaces. In aspects, a ceramic surface and a metal surface join at the interface. In aspects, the method reduces the incidence of interface cracking (and other defects) between the two surfaces. In aspects, the interface forms the surface of an electrostatic chuck.

[0015] Additional aspects include a process for manufacturing an electrostatic chuck with improved interface integrity. The process can include steps of (a) machining an aluminum (Al) plate to form an electrode pattern, (b) cleaning and polishing the plate, (c) forming a coating of aluminum oxide (AI2O3) on the plate using a plasma electrolytic process by immersing the plate in an electrolytic solution and applying a voltage, (d) doping the plate, and (e) polishing surface layers of the plate.

[0016] Embodiments also include an electrostatic chuck with a coating layer that includes AI2O3 (Aluminium oxide), and additional chemical resistance materials such as Y2O3 (Yittrium Oxide) and / or Er20s (Erbium (III) oxide).

[0017] Embodiments also include a method of improving dielectric breakdown voltage (DBV) and / or chucking forces of an electrostatic chuck. The method can include a step of forming a coating of aluminum oxide (AI2O3) on the chuck using a plasma electrolytic process by immersing the plate in an electrolytic solution and applying a voltage. In aspects, the method includes a doping step to improve one or more of its electrical, optical and structural properties.

[0018] Embodiments also include an anodization process to form a dense coating of AI2O3 on both sides of a surface (e.g., a plate for an electrostatic chuck). In aspects, anodization uses a plasma electrolytic process. In aspects, the substrate is immersed in an electrolytic solution that includes potassium hydroxide and sodium hydroxide.

[0019] In aspects, the voltage ranges from 500 V to 1500 V with current at 100 A to 500 A to form the crystalline AI2O3 coating. In other aspects, the voltage ranges from 300 V to 1500 V with current at 0.01 to 0.1 amps (A) per cm2.

[0020] In aspects, the current mode is varied between alternating current (AC), direct current (DC), unipolar, and bipolar current modes.

[0021] In aspects, the coating of AI2O3 forms a dense layer for improved functionality of a substrate (i.e., chuck). In aspects, the coating layer has a thickness of about 50 pm to about 100 pm. In aspects, the coating layer has a thickness of about 100 pm to about 150 pm. In aspects, the coating layer has a thickness of about 10 pm to 200 pm.

[0022] In aspects, the high thermal resistance sandwiched structure and formation for electrostatic chucks forms an “ultrastable” interface between a ceramic and metal. In aspects, this increases the thermal operating window of the electrostatic chucks (i.e., allows their use at higher temperatures).

[0023] In aspects, use of the electrostatic chuck described herein improves the process of manufacturing semiconductor wafers by, for example, reducing the complexity of the manufacturing process and / or lowering costs.

[0024] The present disclosure relates also relates to the use of an electrostatic chuck to secure a substrate, for example, an electrostatic chuck which holds, and fixes, a substrate subject to a treatment in a vacuum processing apparatus such as a charged particle beam exposure apparatus, and to a substrate fixing method using the electrostatic chuck.

[0025] In aspects, use of the electrostatic chuck described herein improves the quality of semiconductor wafers. In aspects, use of the electrostatic chuck described herein produces an improved semiconductor wafer and / or a wafer with fewer imperfections (e.g., fluctuations, bends, scratches, non-uniformities, etc.). In aspects, the dielectric breakdown voltage (DBV) of the material and chucking forces of the chuck are superior to chucks produced by conventional methods.

[0026] In some cases, the formed structure resides on the peripheral of electrostatic chuck and form chemical resistance structure to hold the edge rings.

[0027] In aspects, the electrostatic chuck (ESC) produced by the methods described herein has improved qualities such as improved film structure, cracking resistance, heat resistance, heat conductivity, film composite, hardness, NF3 plasma etch rate and / or DBV compared to those produced by conventional methods.BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings illustrate aspects of the present invention. In such drawings:

[0029] FIG. 1 depicts a typical reaction ion etching (RIE) chamber for producing integrated circuits.

[0030] FIG. 2 depicts an electrostatic chuck (E-Chuck) support for manufacturing an integrated circuit.

[0031] FIG. 3 is a flowchart that shows steps in a method of producing an electrostatic chuck according to embodiments.

[0032] FIG. 4 is a flowchart that shows steps of an anodization method using a plasma electrolytic process according to aspects of the invention.

[0033] Corresponding reference characters indicate corresponding components throughout the several views of the drawings. Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various embodiments of the present disclosure. Also, common but well-understood elements that are useful or necessary in a commercially feasible embodiment are often not depicted in order to facilitate a less obstructed view of these various embodiments of the present disclosure.LIST OF REFERENCE NUMBERS100 reaction ion etching (RIE) chamber105 gas distribution plate115 wafer120 electrostatic chuck (E-Chuck)125 pumping plate130 pumping port200 electrostatic chuck support205 micro-bumps210 ceramic material215 electrodes220 aluminum (Al) baseplateDefinitions

[0034] Reference in this specification to "one embodiment / aspect" or "an embodiment / aspect" means that a particular feature, structure, or characteristic described in connection with the embodiment / aspect is included in at least one embodiment / aspect of the disclosure. The use of the phrase "in one embodiment / aspect" or "in another embodiment / aspect" in various places in the specification are not necessarily all referring to the same embodiment / aspect, nor are separate or alternative embodiments / aspects mutually exclusive of other embodiments / aspects. Moreover, various features are described which may be exhibited by some embodiments / aspects and not by others. Similarly, various requirements are described which may be requirements for some embodiments / aspects but not other embodiments / aspects. Embodiment and aspect can in certain instances be used interchangeably.

[0035] The terms used in this specification generally have their ordinary meanings in the art, within the context of the disclosure, and in the specific context where each term is used. Certain terms that are used to describe the disclosure are discussed below, or elsewhere in the specification, to provide additional guidance to the practitioner regarding the description of the disclosure. It will be appreciated that the same thing can be said in more than one way.

[0036] The term “chuck” refers to a clamp for holding an object or objects. More specifically, it is a specialized type of claim used to hold an object with radial symmetry. Similarly, a “chuck for positioning objects” refers to a chuck having a configuration that can be used for substantially arranging objects on the chuck in a selected pattern. Instead of jaws, a chuck can use magnetism, vacuum, or collets, which are flexible collars or sleeves that fit closely around the tool or workpiece and grip it when squeezed.

[0037] The term “electrostatic chuck” or “ESC” refers to a clamp for holding an object or objects using electrostatic force whereas a “mechanical chuck” refers to a chuck thatuses compression to hold an object. A “non-mechanical chuck” refers to a chuck that does not use compression to hold an object, including a chuck that uses electrostatic or vacuum (i.e., negative pressure) means for such holding.

[0038] The term “integrated circuit,” “IC" or “wafer” refers to a small complex of electronic components and their connections that is produced in or on a small slice of material such as silicon.

[0039] The term “semiconductor chip,” as used herein, refers to an integrated circuit or monolithic integrated circuit (also referred to as an IC, a chip, or a microchip) which is a set of electronic circuits on one small plate ("chip") of semiconductor material, normally silicon.

[0040] The term “sintering” refers to a heat treatment process used to make ceramic materials denser, stronger, and more durable. It involves the application of heat to ceramic powder to cause the particles to bond together, resulting in a strong, homogeneous, and uniform ceramic material. The process of sintering typically involves the following steps: (a) pre-heating, (b) sintering, (c) cooling, (d) annealing and (e) post-sintering. During pre-heating, the ceramic powder is heated to a specific temperature for a predetermined amount of time. During sintering, the ceramic material is heated further until it reaches a temperature just below its melting point, causing the particles to bond together. During cooling, the material is cooled to room temperature. During annealing, the material is cooled even further to improve its strength and durability. Finally, during post-sintering, the material is heated again to ensure its homogeneity and uniformity.

[0041] The term “sintered” refers to a material or article having a dense, coherent mass. A sintered substrate can be produced by shaping or molding a ceramic material into a suitable form or dye, followed by sintering.

[0042] The term “anodizing" refers to an electrolytic passivation process used to increase the thickness of the natural oxide layer on the surface of metal parts. Theprocess is called anodizing because the part to be treated forms the anode electrode of an electrolytic cell. Anodizing can be used to form a protective oxide layer on the surface of a metal such as a chuck. In generally, the process involves submerging the metal in an electrolyte solution and then running an electric current through the solution. The current causes the metal to oxidize, creating a thick, protective layer on the surface. Anodization can be done on a variety of metals, including aluminum, titanium, and zinc. The most commonly used anodic oxidation coatings in industrial anodizing provide electrical and thermal insulation. This layer of aluminum oxide consists of hydrated aluminum oxide that is considered impervious to corrosion. The process also protects the metal from corrosion, improves its appearance and can also be used to dye it different colors. Specific methods of anodizing include chromic acid type I anodizing, boric-sulfuric acid subtype I anodizing, sulfuric acid type II anodizing and sulfuric acid type III hard anodizing.

[0043] The term “doping” refers to a process of increasing the conductivity of metal by adding an appropriate amount of suitable impurity. The process can modulate electrical, optical and structural properties of the metal. It can be performed with an impurity that is electron-rich or electron-deficient than the intrinsic semiconductor silicon or germanium.

[0044] The term “dielectric thickness” refers to the distance between the embedded electrode and the chucking surface of the chuck, (i.e., its surface). Dielectric thickness d can be measured at different points across electrostatic chuck. Variations can be expressed in terms of standard deviation for a set of measurements. A range representing the difference between the minimum dielectric thickness and the maximum dielectric thickness over the entire chucking surface also can be determined from these measurements. In comparison to standard deviation, range takes into account the outliers which do not impact standard deviation significantly but which can indicate that a risk of exposing the electrode through the dielectric exists.

[0045] Essentially flat electrodes which are essentially parallel to the chucking surface, or electrostatic chucks having an essentially uniform dielectric thickness arecharacterized by small standard deviations and a small ranges. Generally, the electrostatic chucks of the invention present standard deviations and ranges which are smaller than those observed in comparable electrostatic chucks which employ bulk metal electrodes. Examples of bulk metal electrodes include mesh, plate, foil, perforated plate or perforated foil electrodes and others known in the art. In one embodiment, the electrostatic chucks of the invention have a dielectric thickness variation expressed as a range which is less than about 700 pm, preferably less than about 300 pm. In another embodiment, the electrostatic chucks of the invention have dielectric thickness variation expressed as a standard deviation which is less than about 150 pm, preferably less than about 50 pm.

[0046] The term “porosity-free” refers to an absence of pores, pinholes, voids, or cracks along the whole depth of the coating as measured by transmission electron microscopy (TEM). The TEM can be performed using a 100 nm thick TEM lamella prepared by focused ion beam milling, with the TEM operated at 200 kV in bright-field, dark-field, or high-resolution mode.

[0047] The term “micro bumps” refers to formed protrusions on a metal part. They can also be called micro divots, cavities, depressions, or precision dimples. A three- dimensional micro bump interface enables an interconnect of a chuck to a silicon via wafer.

[0048] The term “plasma etching” refers to a form of plasma processing used to fabricate integrated circuits (ICs). It involves a high-speed stream of glow discharge (plasma) of an appropriate gas mixture being shot (in pulses) at a sample. The plasma source, known as etch species, can be either charged (ions) or neutral (atoms and radicals). During the process, the plasma generates volatile etch products at room temperature from the chemical reactions between the elements of the material etched and the reactive species generated by the plasma. Eventually the atoms of the shot element embed themselves at or just below the surface of the target, thus modifying the physical properties of the target.

[0049] The term “plasma electrolytic oxidation," “PEO,” “electrolytic plasma oxidation,” “EPO” or “microarc oxidation” refers to an electrochemical surface treatment process for generating oxide coatings on metals. It is similar to anodizing, but it employs higher potentials, so that discharges occur and the resulting plasma modifies the structure of the oxide layer. This process can be used to grow thick (i.e., tens or hundreds of micrometers), largely crystalline, oxide coatings on metals such as aluminium, magnesium and titanium. Because they can present high hardness and a continuous barrier, these coatings can offer protection against wear, corrosion or heat as well as electrical insulation. The coating is a chemical conversion of the substrate metal into its oxide and grows both inwards and outwards from the original metal surface. Because it grows inward into the substrate, it has excellent adhesion to the substrate metal. A wide range of substrate alloys can be coated, including all wrought aluminum alloys and most cast alloys, although high levels of silicon can reduce coating quality.DETAILED DESCRIPTION

[0050] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the subject technology as claimed. Additional features and advantages of the subject technology are set forth in the description below, and in part will be apparent from the description, or may be learned by practice of the subject technology. The advantages of the subject technology will be realized and attained by the methods and systems particularly pointed out in the written description and claims hereof.

[0051] Electrostatic chucks (ESCs), and / or susceptors, are employed to support a wafer, substrate or another type of workpiece during the manufacture of semiconductor devices. In one arrangement, wafers are secured to a chucking surface by an electrostatic force generated between an external electrode and an electrode embedded in a dielectric chuck body.

[0052] ESCs function by creating a strong electrostatic attraction between the chuck and the object (e.g., a wafer or metal part). The chuck typically includes a metal plate or grid that is electrically charged. This creates a strong electrostatic field that attracts the object to the chuck, allowing it to be held in place during machining. The electrostatic chuck is most commonly used in computerized numerical control (CNC) machining and laser cutting but can also be used in other processes such as drilling and grinding. It is also used in vacuum systems to hold parts in place. The electrostatic chuck is a versatile tool that can be used for a variety of applications in semiconductor processes.

[0053] A typical semiconductor processing chamber 100 is depicted in FIG. 1 . Vacuum chambers are necessary for semiconductor manufacturing processes. Conditions within the chamber are particularly important for depositing thin films on the surface of a wafer. The chamber utilizes a plasma source. Also shown are the ion flux controller (IFC), gas distribution plate 105, pumping plate 125 and pumping port 130.

[0054] Process gases are pumped into the chamber under vacuum and ionized using a high-power microwave (MF) source to create a plasma. A radio frequency (RF) electromagnetic field accelerates the resulting ionized species towards the electrode, where they interact both chemically and physically with the wafer, etching away the exposed surface. The etch rate and profile obtained are determined in a complex and nonlinear fashion by the plasma chemistry and energy as well as several process variables including gas flow rates and RF power. A wafer 115 is supported by the electrostatic chuck assembly (E-Chuck) 120. A cooling mechanism (backside cooling helium) is coupled to the chuck assembly (not shown). An electrostatic chuck support can hold / stabilize the wafer during the manufacture of semiconductor devices.

[0055] FIG. 2 depicts the components of a chuck support 200 including an aluminum baseplate 220, ceramic material 210 and micro-bumps 205. The wafer is secured to a chucking surface by an electrostatic force generated between an external electrode and an electrode embedded in a dielectric chuck body 215. As can be appreciated, it is essential that the chuck support has a flat smooth substrate surface, free of irregularities, corrugations, asperities, waves and / or undulations. Such a surface isconventionally prepared by machining, for example, by grinding, polishing or smoothing the sintered substrate, as is known in the art.Ultra-stable Coating Layer

[0056] Embodiments include a high thermal resistance sandwiched structure or “ultrastable” interface between a ceramic and metal. The interface can form a surface coating on a substrate such as an electrostatic chuck. In aspects, this increases the thermal operating window of the electrostatic chucks (i.e. , allows their use at higher temperatures).

[0057] Individual layers form the surface coating on a chuck. In aspects, a conductive layer is sandwich between an outer dense layer and an aluminum oxide (AI2O3) layer. The thickness of each layer can be from about 10 pm to about 200 pm. In aspects, the dense layer has a thickness of about 1 .0 - 10.0 pm. The dense coating layer can also include AI2O3 (aluminum oxide) and / or additional chemical resistance materials such as Y2O3 (yittrium oxide) and Er20s (erbium (III) oxide). In aspects, the coating layer is substantially porosity free.

[0058] The ratio of the aluminum oxide to the additional material can vary (e.g., from about 200:1 to 1 :200). The total thickness, thickness of each layer, and ratio of materials can be selected according to specific chamber applications.

[0059] In aspects, the electrostatic chuck with the coating described herein can be used at high temperatures (i.e., between about 0 to 300°C or about 0 to 400°C). Further, the lower limit of the temperature can be reduced (i.e., to about 0 to - 10°C or about 0 to - 50°C).

[0060] In embodiments, the coating is substantially uniform on the surface of a chuck (e.g., with a thickness variation of about +1-5% or less). In aspects, the coating is dense with a porosity of about 0%. In aspects, the coating is resistant to corrosion and erosion from plasma etch chemistries (e.g., CCI4 / CHF3 plasma etch chemistries, HChSi etch chemistries and NF3 etch chemistries). Further, the coatings described herein canbe resistant to cracking and delamination at high temperatures (i.e. , up to and / or above 300° C). For example, a chuck that has the coating can be used in processes that include heating to temperatures greater than 250° C. The chuck can be exposed to thermal cycles between - 10°C and 300° C without introducing any cracks or delamination in the coating.Method of Producing an Electrostatic Chuck

[0061] The conventional method of forming AI2O3 plates produces electrostatic chucks with limitations (e.g., heat sensitivity, defective chips, etc.). Embodiments include a method of producing an electrostatic chuck that overcomes the limitations of conventional designs. FIG. 3 is a flowchart that shows the steps according to embodiments.

[0062] First, an aluminum (AL) plate is machined to form an electrode pattern 305. The plate is then cleaned 310 and polished 315 using common methods known in the art. Next, an anodization process 320 is used to form a dense coating of AI2O3 on both sides of the plate. This forms a dense layer for improved functionality.

[0063] In aspects, the anodization process involves oxidizing the surface of the object using a plasma electrolytic process. The plate is immersed in an electrolytic solution that includes potassium hydroxide or sodium hydroxide or their mixtures.

[0064] In aspects, the current is varied between alternating current (AC), direct current (DC), unipolar, and bipolar current modes. Primary parameters like electric current density, electric voltage intensity, pulse oscillation, and positive / negative duty cycle impact the plasma electrolytic oxidation (PEO) procedure and obtained coating attributes. These parameters also influence PEO process characteristics such as developed voltage breakdown, local melting and oxidation of the substrate, quenching, and recrystallization processes and in turn influence the coating’s microstructure and related properties. In a PEO process, a wide range of voltages (e.g., 95 V to 750 V) can be employed along with an AC or DC electrical supply between the cathode and anode.

[0065] As explained in detail below (Example 1 ), this anodization process entails repeating steps of applying a positive voltage to the substrate placed in an electrolytic bath and discharge. This forms a protective anodic oxide layer on the chuck.

[0066] In the final step, the plate is polished to remove surface layers 325. Holes can be drilled into the plate for an electrical connection 330. A quality check can be performed to ensure integrity of the plate 335. Finally, the plate is bonded to the aluminum baseplate 340.

[0067] FIG. 4 is a flowchart that shows details of the anodization process 320 according to embodiments. The process can include a pre-treatment step 350 followed by etching 352. Thereafter, the PEG coating process 360 is implemented in an electrolyte solution 355 using an electric regime 355, 365.

[0068] Common salts for the PEG of aluminum, magnesium, titanium, and their alloys in alkaline media are, amongst others, silicates, phosphates, aluminates, fluorides, borates and stannates. Especially for the PEG of magnesium and its alloys, acidic or pH-neutral electrolyte compositions are used instead of alkaline electrolytes, e.g., fluoric acid, phosphoric acid, and / or boric acid in combination with organic additives. By incorporating elements provided by the electrolyte, the composition of the oxide can be altered substantially.

[0069] The electric regime during PEG can be determined by the control parameter (current density or cell voltage), the type of the supplied parameter (direct, alternating, pulse current / voltage), and the definition of the regime (frequency, breaks, limits etc.). Under direct current or voltage, the discharge events become ever more intense during the progression of the process. This can include large discharges with long life periods, which can have a deteriorating effect on both, the formed oxide and the substrate and thus lead to irreparable defects. This behavior results from excessive energy transfer and heat release. Therefore, pulse or alternating current or voltage regimes can beused to limit the effect of the strong discharges and to facilitate the formation of thick oxide coatings up to a few hundred microns.

[0070] A doping step 370 can be used to enhance the electrical, optical and / or structural properties of the outer layer. Trace amount of dopants to the formed AI2O3 can be added to the film formation process to tune the resistivity of the formed ceramic layers, in the range of 109- 1013ohm-cm, or in the range of 1011- 1015ohm-cm. The dopants can include, for example, elemental magnesium and phosphorus.

[0071] After the PEO coating process, the substrate can undergo post-treatment 375 to produce the coating with desired morphology / composition 380.EXAMPLES

[0072] The following non-limiting examples are provided for illustrative purposes only in order to facilitate a more complete understanding of representative embodiments now contemplated. These examples are intended to be a mere subset of all possible contexts in which the components of the formulation may be combined. Thus, these examples should not be construed to limit any of the embodiments described in the present specification, including those pertaining to the type and amounts of components of the formulation and / or methods and uses thereof.Anodization Process

[0073] As the aluminum (Al) part is immersed in the chemical bath and the current is running through it, the Al atoms are slowly extracted from the surface of the metal. In this example, a multi-step anodization process is used to anodize the surfaces of a substrate (i.e., chuck). Referring to FIG. 4, this process 320 forms a dense layer of aluminum oxide on both sides of the Al substrate.

[0074] In embodiments, the first step is referred to as “pre-treatment” 350. The pretreatment process involves achieving a visible finish and a clean work part. This step includes cleaning which is important to remove residual grease, oils, and otherimpurities from a previous fabrication process like extrusion or CNC aluminum machining to avoid impurities and inconsistencies in the finished part. Next, the substrate surface oxidation layer is etched 352. The surface finish of a part before anodizing is relevant because it will dictate the quality of the final result. “Tweaking” the desired surface finish can be done through polishing or etching, where minor imperfections on the surface are corrected while being prepared for anodizing.

[0075] The next step can be referred to as “electrolytic oxidation, “anodizing” or “anodic oxidation” 360. After the surface is prepared, the substrate will go through the anodizing step, submerged into a bath of sulfuric acid electrolyte solution (which may vary depending on the type of anodizing process chosen). The composition of this electrolyte bath is what makes the process unique, as the bath composition determines the resultant coating characteristics. In this example, the batch includes potassium hydroxide (KOH) and sodium hydroxide (NaOH). Both the KOH and / or NaOH are at concentration ranging from 0.01 M to 0.5M. The time is controlled to achieve a thickness range in between 10 to 60 minutes, but can be longer or shorter.

[0076] The electrolyte solution has many positive and negative ions and is an electrically conductive solution. The positive ions can attract the negative plates and the negative ions to the positive anode. The negative ion attracts the aluminum parts, which is the positive anode. The aluminum parts will serve as an anode. At the same time, a cathode is installed within the tank to allow an active passing of electrical current through the system and induce the release of oxygen ions from the electrolytic solution. This process creates aluminum oxide in the substrate (i.e., a barrier layer) that is generally rougher than the aluminum surface. Higher voltages and different electrical regimes can be used in the processing methodology for plasma electrolytic oxidation (PEO). This helps create plasma discharges, which modifies the coating during the growth process.

[0077] In this example, the voltage ranges from 500 V to 1500 V with current ranging from 100 A to 500 A. These relatively high voltage and high current conditions are used to form the crystalline AI2O3 phases.

[0078] The next step can be referred to as “doping” 370. The formed aluminum oxide layer is dense but the characteristics of the outer layer (i.e., its electrical, optical and structural properties.) can be “tuned” through a doping process. Trace amounts of elements are added to tune the resistivity of the formed oxidation layer.

[0079] The final step can be referred to as “polishing” 375. The formed Aluminium oxide is porous on the surface layer and may contain large pores or defects. A polishing step can be applied to remove the loose and porous layer. Nanoparticles can be used in the last steps to seal the pores of the coated materials. Finally, the coating composition and morphology can be characterized 380.

[0080] In embodiments, the electrostatic chuck (ESC) produced has characteristics as shown in Table 1 (below). For reference, characteristics of a conventionally produced chuck (i.e., by anodization) are provided.Table 1

[0081] In embodiments, the electrostatic chuck (ESC) produced by the methods described herein has improved qualities (e.g., film structure, cracking resistance, heat resistance, heat conductivity, film composite, hardness, NF3 plasma etch rate and / or DBV) compared to an ESC produced by conventional methods.

[0082] In embodiments, the methods described herein use a plasma electrolytic process with a solution on potassium hydroxide (KOH) and / or sodium hydroxide (NaOH). In aspects, the concentration of KOH is 0.05%, 0.10%, 0.15%, 0.2%, 0.5%, 1.0%, 1.5%, 2.5%, 5.0%, 10%, 15%, 20%, 25%, 30%, 35% or 45%. In aspects, the concentration of NaOH is 0.05%, 0.10%, 0.15%, 0.2%, 0.5%, 1.0%, 1.5%, 2.5%, 5.0%, 10%, 15%, 20%, 25%, 30%, 35% or 45%.

[0083] In embodiments, the substrate is immersed in a plasma electrolytic process (and a voltage is applied) for period of about 5 minutes, about 7 minutes, about 10 minutes, about 20 minutes, about 40 minutes, about 1 hour, about 1 .5 hours, about 2 hours or longer.

[0084] In embodiments, a range of voltages (i.e., 95 V to 750 V) is employed along with an AC or DC electrical supply between the cathode and anode. In aspects, the voltage ranges from 500 to 1500 volts (V) with a current of 100 to 500 amps (A). In aspects, the current mode is varied between alternating current (AC), direct current (DC), unipolar, and bipolar current modes to modify the surface. In aspects, one or more of electric current density, electric voltage intensity, pulse oscillation, and positive / negative duty cycle are used to tune the microstructure and / or properties of the outer surface.* * *

[0085] In closing, it is to be understood that although aspects of the present specification are highlighted by referring to specific embodiments, one skilled in the art will readily appreciate that these disclosed embodiments are only illustrative of the principles of the subject matter disclosed herein. For example, it should be understood that any of the other chamber components (e.g., chamber walls, showerheads, gas lines, electrostatic chucks, nozzles, etc.) can also be coated with the dense coating described herein. Therefore, it should be understood that the disclosed subject matter is in no way limited to a particular compound, composition, article, apparatus, methodology, protocol, and / or reagent, etc., described herein, unless expressly stated as such. In addition, those of ordinary skill in the art will recognize that certain changes, modifications, permutations, alterations, additions, subtractions and sub-combinationsthereof can be made in accordance with the teachings herein without departing from the spirit of the present specification. It is therefore intended that the following appended claims and claims hereafter introduced are interpreted to include all such changes, modifications, permutations, alterations, additions, subtractions and sub-combinations as are within their true spirit and scope.

[0086] Certain embodiments of the present invention are described herein, including the best mode known to the inventors for carrying out the invention. Of course, variations on these described embodiments will become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventor expects skilled artisans to employ such variations as appropriate, and the inventors intend for the present invention to be practiced otherwise than specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described embodiments in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.

[0087] Groupings of alternative embodiments, elements, or steps of the present invention are not to be construed as limitations. Each group member may be referred to and claimed individually or in any combination with other group members disclosed herein. It is anticipated that one or more members of a group may be included in, or deleted from, a group for reasons of convenience and / or patentability. When any such inclusion or deletion occurs, the specification is deemed to contain the group as modified thus fulfilling the written description of all Markush groups used in the appended claims.

[0088] Unless otherwise indicated, all numbers expressing a characteristic, item, quantity, parameter, property, term, and so forth used in the present specification and claims are to be understood as being modified in all instances by the term “about.” As used herein, the term “about” means that the characteristic, item, quantity, parameter,property, or term so qualified encompasses a range of plus or minus ten percent above and below the value of the stated characteristic, item, quantity, parameter, property, or term. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the specification and attached claims are approximations that may vary. For instance, as mass spectrometry instruments can vary slightly in determining the mass of a given analyte, the term "about" in the context of the mass of an ion or the mass / charge ratio of an ion refers to + / -0.50 atomic mass unit. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical indication should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

[0089] Use of the terms “may" or “can” in reference to an embodiment or aspect of an embodiment also carries with it the alternative meaning of “may not” or “cannot.” As such, if the present specification discloses that an embodiment or an aspect of an embodiment may be or can be included as part of the inventive subject matter, then the negative limitation or exclusionary proviso is also explicitly meant, meaning that an embodiment or an aspect of an embodiment may not be or cannot be included as part of the inventive subject matter. In a similar manner, use of the term “optionally” in reference to an embodiment or aspect of an embodiment means that such embodiment or aspect of the embodiment may be included as part of the inventive subject matter or may not be included as part of the inventive subject matter. Whether such a negative limitation or exclusionary proviso applies will be based on whether the negative limitation or exclusionary proviso is recited in the claimed subject matter. Further, the use of the terms “include,” “includes” and “including” means include, includes and or including as well as include, includes and including, but not limited to.

[0090] Notwithstanding that the numerical ranges and values setting forth the broad scope of the invention are approximations, the numerical ranges and values set forth in the specific examples are reported as precisely as possible. Any numerical range or value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements. Recitation ofnumerical ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate numerical value falling within the range. Unless otherwise indicated herein, each individual value of a numerical range is incorporated into the present specification as if it were individually recited herein.

[0091] The terms “a,” “an,” “the” and similar references used in the context of describing the present invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Further, ordinal indicators - such as “first,” “second,” “third,” etc. - for identified elements are used to distinguish between the elements, and do not indicate or imply a required or limited number of such elements, and do not indicate a particular position or order of such elements unless otherwise specifically stated. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein is intended merely to better illuminate the present invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the present specification should be construed as indicating any non-claimed element essential to the practice of the invention.

[0092] When used in the claims, whether as filed or added per amendment, the open- ended transitional term “comprising” (and equivalent open-ended transitional phrases thereof like including, containing and having) encompasses all the expressly recited elements, limitations, steps and / or features alone or in combination with unrecited subject matter; the named elements, limitations and / or features are essential, but other unnamed elements, limitations and / or features may be added and still form a construct within the scope of the claim. Specific embodiments disclosed herein may be further limited in the claims using the closed-ended transitional phrases “consisting of” or “consisting essentially of” in lieu of or as an amended for “comprising.” When used in the claims, whether as filed or added per amendment, the closed-ended transitional phrase “consisting of” excludes any element, limitation, step, or feature not expresslyrecited in the claims. The closed-ended transitional phrase “consisting essentially of" limits the scope of a claim to the expressly recited elements, limitations, steps and / or features and any other elements, limitations, steps and / or features that do not materially affect the basic and novel characteristic(s) of the claimed subject matter. Thus, the meaning of the open-ended transitional phrase “comprising” is being defined as encompassing all the specifically recited elements, limitations, steps and / or features as well as any optional, additional unspecified ones. The meaning of the closed-ended transitional phrase “consisting of” is being defined as only including those elements, limitations, steps and / or features specifically recited in the claim whereas the meaning of the closed-ended transitional phrase “consisting essentially of’ is being defined as only including those elements, limitations, steps and / or features specifically recited in the claim and those elements, limitations, steps and / or features that do not materially affect the basic and novel characteristic(s) of the claimed subject matter. Therefore, the open-ended transitional phrase “comprising” (and equivalent open-ended transitional phrases thereof) includes within its meaning, as a limiting case, claimed subject matter specified by the closed-ended transitional phrases “consisting of’ or “consisting essentially of.” As such embodiments described herein or so claimed with the phrase “comprising” are expressly or inherently unambiguously described, enabled and supported herein for the phrases “consisting essentially of” and “consisting of.”

[0093] All patents, patent publications, and other publications referenced and identified in the present specification are individually and expressly incorporated herein by reference in their entirety for the purpose of describing and disclosing, for example, the compositions and methodologies described in such publications that might be used in connection with the present invention. These publications are provided solely for their disclosure prior to the filing date of the present application. Nothing in this regard should be construed as an admission that the inventors are not entitled to antedate such disclosure by virtue of prior invention or for any other reason. All statements as to the date or representation as to the contents of these documents is based on the information available to the applicants and does not constitute any admission as to the correctness of the dates or contents of these documents.

[0094] The flowchart and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products according to various embodiments of the present invention. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order or out of order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and / or flowchart illustration, and combinations of blocks in the block diagrams and / or flowchart illustration, can be implemented by special purpose hardware-based systems that perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.

[0095] Lastly, the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the present invention, which is defined solely by the claims. Accordingly, the present invention is not limited to that precisely as shown and described.

[0096] Although embodiments of the current disclosure have been described comprehensively in considerable detail to cover the possible aspects, those skilled in the art would recognize that other versions of the disclosure are also possible.

[0097] While the present invention has been described in terms of particular embodiments and applications, in both summarized and detailed forms, it is not intended that these descriptions in any way limit its scope to any such embodiments and applications, and it will be understood that many substitutions, changes and variations in the described embodiments, applications and details of the method andsystem illustrated herein and of their operation can be made by those skilled in the art without departing from the spirit of this invention.

Claims

CLAIMSWhat is claimed is:1 . A method of producing an electrostatic chuck, the method comprising the steps of: a) machining an aluminum (Al) plate to form an electrode pattern, b) cleaning and polishing the plate, c) forming a coating of aluminum oxide (AI2O3) on the plate by plasma electrolytic oxidation (PEO), d) polishing surface layers of the plate, and e) bonding the plate.

2. The method of claim 1 , wherein the step of forming a coating of aluminum oxide (AI2O3) on the plate by plasma electrolytic oxidation comprises steps of placing the plate in an electrolytic bath and applying a voltage to the plate.

3. The method of claim 2, wherein the electrolytic bath is comprised of solutions of potassium hydroxide and / or sodium hydroxide.

4. The method of claim 2, wherein the voltage ranges from 300 V to 1500 V with a current density of 0.01 to 0.1 A / cm2.

5. The method of claim 1 , further comprising a step adding one or more additional chemically resistant materials to the coating by anodization.

6. The method of claim 5, wherein the one or more additional chemically resistant materials are selected from Y2O3 (yittrium oxide) and E^Os (erbium (III) oxide).

7. The method of claim 1 , further comprising a step of drilling holes into the plate for an electrical connection.

8. The method of claim 1 , further comprising a doping step to improve one or more of its electrical, optical and structural properties.

9. A method of producing an integrated circuit, the method comprising a step of securing a substrate to the electrostatic chuck of claim 1 .

10. A method of increasing the heat resistance of an electrostatic chuck, the method comprising a step of forming a coating of aluminum oxide (AI2O3) on both sides of the chuck by anodization.11 . The method of claim 10, wherein the step of forming a coating of aluminum oxide (AI2O3) on both sides of the chuck comprises steps of placing the chuck in an electrolytic bath and applying a voltage to the plate.

12. The method of claim 11 , wherein the electrolytic bath is comprised of solutions of potassium hydroxide and / or sodium hydroxide.

13. The method of claim 11 , wherein the voltage ranges from 300 V to 1500 V with a current density of 0.01 to 0.1 A / cm2.

14. The method of claim 11 , further comprising adding one or more additional chemically resistant materials to the coating.

15. The method of claim 14, wherein the one or more additional chemically resistant materials are selected from Y2O3 (yittrium oxide) and EraOa (erbium (III) oxide).

16. A method of producing an electrostatic chuck, the method comprising the steps of: a) machining an aluminum (Al) plate to form an electrode pattern, b) cleaning and polishing the plate,c) forming a coating of aluminum oxide (AI2O3) on the plate using a plasma electrolytic process by immersing the plate in an electrolytic solution and applying a voltage, d) doping the plate, and d) polishing surface layers of the plate.

17. The method of claim 16, wherein the electrolytic solution is comprised of potassium hydroxide and / or sodium hydroxide.

18. The method of claim 16, wherein the voltage is from 300 V to 1500 V with a current density of 0.01 to 0.1 A / cm2.

19. The method of claim 16, further comprising a step adding one or more additional chemically resistant materials to the coating by the electrolytic process.

20. The method of claim 19, wherein the one or more additional chemically resistant materials are selected from Y2O3 (yittrium oxide) and Er20s (erbium (III) oxide).21 . A electrostatic chuck comprised of a dense coating of aluminum oxide AI2O3 on both sides of a surface.

22. The electrostatic chuck of claim 21 , wherein the dense coating further comprises one or more additional chemically resistant materials selected from Y2O3 (yittrium oxide) and Er20s (erbium (III) oxide).

23. The electrostatic chuck of claim 21 , wherein the dense coating has a thickness of about 10 pm to about 200 pm.

24. An electrostatic chuck assembly comprised of a heat resistant sandwiched structure and formation for electrostatic chucks.

25. A method of improving dielectric breakdown voltage (DBV) and / or chucking forces of an electrostatic chuck, the method comprising a step of forming a coating of aluminum oxide (AI2O3) on the chuck using a plasma electrolytic process by immersing the plate in an electrolytic solution and applying a voltage.

26. The method of claim 25, further comprising a doping step to improve one or more of its electrical, optical and structural properties.

27. The method of claim 25, wherein the electrolytic solution is comprised of potassium hydroxide and / or sodium hydroxide.

28. The method of claim 25, wherein the voltage is from 300 V to 1500 V with a current density of 0.01 to 0.1 A / cm2.

29. The method of claim 25, further comprising a step adding one or more additional chemically resistant materials to the coating by the electrolytic process.

30. The method of claim 29, wherein the one or more additional chemically resistant materials are selected from Y2O3 (yittrium oxide) and ErzOa (erbium (III) oxide).

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