6939results about "Ion implantation coating" patented technology

The invention discloses a partitioned multifunctional metal double-cavity vacuum coating process and system, and belongs to the technical field of material surface treatment. The process comprises the steps of base material pretreatment, double-cavity preparation, vacuum inspection, first cavity bottom layer deposition, vacuum transfer, second cavity functional layer deposition and cooling, the double cavities are provided with corresponding target materials respectively, and parallel operation and vacuum seamless transfer are supported; the system comprises double coating cavities, a vacuum transmission channel, a vacuum acquisition and control module, a coating deposition module, a workpiece bearing module and a process parameter regulation and control module, and each of the double cavities is provided with a multi-target mounting rack and carries a real-time monitoring unit and an intelligent control system. Integrated preparation of the composite film layer and synchronous production of multifunctional workpieces are achieved, operation gaps are eliminated, the compactness and adhesive force of the film layer are improved, parameter deviation and the reject ratio are reduced, and batch production requirements are met.

The invention discloses a crystal resonator sputter coating device and a preparation method of a crystal resonator, and belongs to the field of electronic components, the crystal resonator sputter coating device comprises a bottom plate, a lower electrode mask plate, a positioning plate, an upper electrode mask plate and a magnetic cover plate in sequence, the positioning plate is provided with a wafer positioning groove, a wafer is installed in the wafer positioning groove, and the magnetic cover plate is provided with a magnet. The upper electrode mask plate and the lower electrode mask plate are both provided with electrode holes, the thickness of the positioning plate is recorded as h < definite >, and one surface of at least one of the upper electrode mask plate and the lower electrode mask plate, which faces a wafer, is provided with a diffusion prevention bulge for preventing diffusion of electrode particles during film coating, and the thickness of the diffusion prevention bulge is recorded as h < definite >. The size of the dispersion preventing protrusion is matched with the size of the wafer positioning groove, the dispersion preventing protrusion is located in the wafer positioning groove during assembly, the thickness of the wafer is recorded as h wafer, and h wafer lt is smaller than or equal to 0.017 mm; and h, setting. The sputtering coating device solves the problem of electrode diffusion of the high-frequency crystal resonator in the existing sputtering coating device for the crystal resonator due to too small wafer thickness.

The invention relates to a preparation method of an etching-resistant and wear-resistant Y2O3-AlxOy composite coating. The preparation method comprises the following steps: carrying out ultrasonic cleaning on a corrosion-resistant matrix; performing plasma bombardment cleaning activation on the surface of the corrosion-resistant matrix; a Y2O3 coating and an AlxOy coating are alternately deposited on a corrosion-resistant base body in a double-target magnetron sputtering mode to form the Y2O3-AlxOy composite coating, the sputtering power of a Y target is larger than that of an Al target, and the ratio of x to y in the AlxOy coating is larger than 1. According to the method, the amorphous AlxOy coating dominated by the metal state is introduced into the Y2O3 coating, growth of Y2O3 columnar crystals is continuously broken, crystal grains are refined, formation of intergranular easy-to-etch point locations is inhibited, and an yttrium aluminum oxide composite strengthening phase is formed at an interface, so that plasma etching resistance is improved; the thickness of a single-layer coating in the composite coating is very thin; under the action of growth stress, the structure of the coating presents a wave-shaped microstructure and a soft and hard alternate mechanical structure, and the soft and hard alternate mechanical structure is beneficial to inhibiting generation of transverse cracks, guiding friction crack level expansion, prolonging the friction life of the coating and reducing the wear rate.

The invention discloses an oxide thin film post-processing method based on multi-stage cooling annealing, and aims to actively regulate and control thin film stress while repairing oxygen vacancies through a precisely designed heat treatment process. According to the method, the problem that stress control and defect repair are difficult to consider in the annealing process is solved, and a solid theoretical basis and scientific basis are laid for preparing low-absorption and high-stability oxide intense laser thin film devices.

The invention discloses a magnetron sputtering device for coating and a using method thereof.The magnetron sputtering device for coating comprises a sputtering chamber, a heating assembly and a cooling assembly, the sputtering chamber is used for coating a substrate, the magnetron sputtering device further comprises a bearing module and a conveying module, the bearing module is arranged in the sputtering chamber, and the conveying module is used for conveying the substrate to the substrate; the carrying module is used for carrying a substrate to be coated, and the conveying module is used for selectively driving one of the heating assembly and the cooling assembly to be far away from the carrying module and the other one of the heating assembly and the cooling assembly to be close to the carrying module so as to heat or cool the substrate. The conveying module drives the heating assembly and the cooling assembly to be matched with the bearing module, so that the temperature of the substrate can be adjusted and controlled in a limited space, the influence between the heating assembly and the cooling assembly can be effectively reduced, and the heating and cooling efficiency is guaranteed.

The invention provides a preparation method of a bipolar current collector based on a selective double-sided modified masking film. The preparation method comprises the following steps: depositing a Ni-Cr alloy layer on a single side surface of an aluminum substrate; one side of the masking film is etched to form a roughened surface, and the other side of the masking film is hydrophobic to form a hydrophobic surface; the roughened surface of the masking film and the surface, without the Ni-Cr alloy layer, of the aluminum matrix are pressed, and the edge is coated with curing glue; and placing the pressed and glued sample in an electroplating solution to electroplate a copper layer, finally cutting off an edge glue sealing area, and stripping the masking film. According to the preparation method, the masking film used for protecting the back surface of the aluminum substrate is subjected to double-sided differential treatment, the edge sealing technology is matched, and the Ni-Cr alloy is adopted for bottoming, so that the adhesive force between the copper plating layer and the aluminum substrate is improved, the risk of causing corrosion of a primary battery is reduced, the bipolar current collector which is firmly combined and has a pure interface can be prepared, and the service life of the bipolar current collector is prolonged. And a feasible solution is provided for realizing light-weight and high-performance current collectors for electronic devices such as lithium batteries and the like.

The embodiment of the invention provides a deposition rate control method and device, a storage medium and a program product. Belongs to the technical field of semiconductor devices. The method comprises the following steps: periodically acquiring a deposition rate, wherein the deposition rate corresponds to a data acquisition moment; determining a deposition rate change rate corresponding to the data acquisition moment according to the deposition rate corresponding to the data acquisition moment; according to the deposition rate corresponding to the data acquisition moment and the deposition rate change rate, whether a power threshold value is increased or not is judged; if it is judged that the power threshold value is increased, the power output minimum value and the power output maximum value are increased; and carrying out light-emitting layer deposition by adopting output power which is greater than the power output minimum value and less than the power output maximum value. According to the method, the problems that the deposition rate is unstable and defects are increased due to the fact that the adjustment range of the power is large when the power output is dynamically adjusted are solved.

The invention discloses a wide-temperature-range wear-resistant high-entropy alloy coating as well as a preparation method and application thereof, and belongs to the technical field of wear-resistant materials. The wide-temperature-range wear-resistant high-entropy alloy coating comprises a high-entropy alloy bottom layer and a high-entropy alloy oxide surface layer, the high-entropy alloy in the high-entropy alloy bottom layer comprises at least four elements of Ti, Nb, Cr, Mo, V and Ta; the high-entropy alloy oxide surface layer is formed after high-entropy alloy in the surface area in the high-entropy alloy bottom layer is subjected to in-situ oxidation. The wide-temperature-range wear-resistant high-entropy alloy coating has high hardness and wide-temperature-range mechanical property stability, has excellent wear resistance and corrosion resistance in the range of room temperature to 700 DEG C, and can greatly improve the use performance and prolong the service life of a high-temperature moving part.

The invention discloses an electroplating process method for preparing a deep-etching thick metal mask, and belongs to the technical field of micro electro mechanical system electroplating processes. Comprising the following steps: firstly, carrying out photoetching and patterning on the surface of a wafer by using positive photoresist; then, carrying out seed layer sputtering on the wafer subjected to pattern photoetching, and forming a to-be-electroplated region with a preset pattern through a stripping process; then, photoetching is carried out on the to-be-electroplated area through negative photoresist, and a thick photoresist layer with the thickness larger than that of a preset metal coating is formed; and finally, the electroplating area is electroplated, and the metal coating with the preset thickness is obtained. According to the method, the negative photoresist process is adopted, so that the transverse growth of the metal coating is effectively inhibited, the perpendicularity of the side wall of the metal coating is improved, and meanwhile, the damage to the surface of the wafer when the seed layer in the non-electroplating area is removed is avoided. The problems that mushroom-shaped protrusions are easily formed on the edge of a plating layer, crystal grains are coarsened and the like in the electroplating process of an existing electroplating method are solved.

The invention belongs to the technical field of flexible transparent film electrodes, and particularly relates to a flexible indium tin oxide film electrode, a preparation method and a flexible solar cell. According to the flexible indium tin oxide thin film electrode provided by the invention, after the processes of pre-treating substrates such as PET, covering an acrylic resin hard coating, depositing a SiO2 transition layer and the like, the adhesive force of the indium tin oxide conductive thin film is improved through the indium tin oxide conductive thin film deposited through alternate radio frequency magnetron sputtering and direct current pulse magnetron sputtering; the bottom layer deposited by radio frequency magnetron sputtering is used for providing an interface seed layer for the fluorine-doped indium tin oxide conductive thin film layer deposited by direct current pulse magnetron sputtering and having high carrier concentration and low resistance, and the top layer is used for providing protection, so that the conductivity, environmental stability and other properties of the flexible indium tin oxide thin film electrode are improved; the conductive performance is not easy to attenuate, the long-term use stability is good, and the technical problem that in the prior art, a flexible transparent film electrode is low in performance is solved.

The invention belongs to the technical field of vacuum coating, and relates to an electron gun and ion source collaborative evaporation coating method, a control method and a control system. The electronic gun and ion source collaborative evaporation coating control method comprises the steps that key parameters in the coating process are continuously collected, and an electronic gun beam initial value and an ion source gas flow initial value are dynamically generated according to state diagnosis results of all the parameters; the beam current value of the electron gun and the gas flow value of the ion source are corrected in real time to inhibit the disturbance of the ion source to the beam current of the electron gun, and the electron gun and the ion source are cooperatively regulated and controlled to ensure the precise control of the coating uniformity; the invention further discloses an electron gun and ion source collaborative evaporation coating method, local hot spot compensation and global uniformity compensation are carried out by adopting a film thickness compensation mechanism so as to accurately control the film thickness. According to the invention, the cooperative control of the electron gun evaporation and ion bombardment process is realized, the film adhesion is enhanced, the evaporation coating rate is improved, and the film thickness uniformity is improved.

The invention relates to a preparation method of a diamond-copper composite heat sink with a high-heat-conduction passage. According to the method, a diamond / copper composite heat conduction framework with a bionic fractal structure is prepared through an extrusion type additive manufacturing technology, and then the diamond / copper composite heat sink with high heat conduction, high communication and high density is obtained through degreasing, sintering and infiltration processes. The problem that a complex structure is difficult to achieve through a traditional processing method is solved, meanwhile, a high-speed heat conduction channel with preferred orientation is constructed in the heat sink, and therefore the heat dissipation performance of the composite material is remarkably improved, and the composite material is suitable for heat management of high-power electronic equipment.

The invention relates to a film system structure for partitioned film coating. The film system structure comprises a glass substrate, a first film stack and a second film stack, the first film stack is formed by alternately depositing a medium-refractive-index material and a low-refractive-index material in a vacuum chamber, the film system design structure of the first film stack is SUBM + L +... + M + LAir, SUB represents a substrate, M represents a medium-refractive-index material film layer, L represents a low-refractive-index material film layer, and Air represents air; the second film stack is a film stack formed by alternately depositing a high-refractive-index material and a low-refractive-index material in the vacuum chamber, the film system design structure of the second film stack is SUB first film stack + H + L... + H + LAir, SUB represents a substrate, H represents a high-refractive-index material film layer, L represents a low-refractive-index material film layer, and Air represents air. Compared with the prior art, the method has the advantages of reducing the manufacturing cost, improving the boundary definition and the like.

Disclosed herein are methods for producing electrodes comprising single-layer 1T′-transition metal dichalcogenide (TMD) nanosheets. The method includes filtering a suspension of single-layer 1T′-TMD nanosheets over a polymeric substrate to produce the electrode, wherein, the single-layer 1T′-TMD nanosheets of the electrode are no more than 1,000 nm in thickness; the electrode comprises at least 70% 1T′-phase; and the electrode has a calculated electrochemical active surface area (ECSA) that is about 10-fold higher than that of a control electrode, which comprises 2H-TMD nanosheets. Also disclosed herein are methods for deionizing a fluid. The method includes steps of discharging the fluid in an electrochemical capacitor at a constant voltage of no more than 0.5 V to deionize the fluid, wherein the electrochemical capacitor is characterized in having the electrode comprising single-layer 1T′-TMD nanosheets produced by the present method.

The invention provides a wafer-level cluster coplanar waveguide electrode array, a preparation method and a test system. The coplanar waveguide electrode array comprises an insulating substrate and a plurality of coplanar waveguide electrodes which are arranged in a periodic array; each coplanar waveguide electrode comprises a central transmission section, a probe pad and a gradual transition section; through the design of the central transmission section and the gradual transition section of the coplanar waveguide configuration, the whole-course impedance matching from an external probe to a nano gap is ensured, so that nanosecond and even picosecond-level ultrafast electric pulses can be transmitted to the cluster function unit with extremely low loss and distortion; through overlay and multi-step photoetching and in combination with a negative feedback electromigration technology, a nano gap is manufactured with high success rate, and a cluster function unit is integrated; besides, a test system integrating a coplanar waveguide electrode array and a high-end test instrument is used for exciting and capturing the ultrafast response of a cluster functional unit, and the single write-in time of a cluster device is directly pushed to a subnanosecond level (lt;

The embodiment of the invention provides a connecting layer, a composite layer, a solar cell and a laminated cell. The connecting layer comprises a first transparent conductive layer and a hole transport layer which are stacked; and the hole transport layer is an alloy film containing Ga, Al, In, Sn, O and N elements. Component regulation and control are carried out on the hole transport layer, P-type doping is realized by utilizing a co-doping strategy, the hole concentration of a traditional tin oxide material layer is improved, long wavelength absorption is not remarkably increased, and in addition, multi-component doping can also avoid that a single component is easy to separate out and split phases.

The present invention provides a substrate with a coating comprising, in order: a) a substrate; b) a primer layer comprising a first transition metal or an oxide thereof; c) one or more corrosion resistant layers, each layer comprising a first sub-layer, a second sub-layer and a third sub-layer, the sub-layers comprising the first transition metal and a second transition metal, where the ratio of the first transition metal and the second transition metal varies between the sub-layers; d) a conductive layer comprising the second transition metal, or a nitride thereof and / or an oxide thereof. The invention also describes a method for producing such a substrate with a coating. The coated substrate has good electrical conductivity and corrosion resistance.

The invention discloses a system and a method for rapidly detecting trace active ingredients of a medicine, belongs to the technical field of medicine detection, and relates to cross application of surface enhanced Raman spectroscopy and artificial intelligence. The system comprises a sample preparation module, a micro-fluidic enrichment module, a Raman spectrum acquisition module, a self-adaptive spectrum analysis module, a multi-component identification module and an intelligent report generation module, and efficient enrichment and nanogram-level detection of drug molecules are realized through an enhanced surface Raman scattering micro-fluidic chip. Intelligent identification and accurate quantification of complex spectral characteristics are realized by adopting a deep learning algorithm and a self-adaptive weight calculation method, synchronous detection of 5-10 active pharmaceutical ingredients is supported, the detection sensitivity reaches nanogram / milliliter level, the quantification error is less than 5%, the detection time of the whole process is 5-10 minutes, and the detection accuracy is high. The sensitivity, the accuracy and the efficiency of medicine quality detection are obviously improved.

Disclosed are a semiconductor comprising amorphous tellurium oxide, thin film transistor and method of fabricating same. In detail, a semiconductor comprising a chalcogen atom comprising at least one selected from the group consisting of a sulfur atom (S) and a selenium atom (Se); and tellurium composite comprising a tellurium (Te) atom and tellurium oxide. A thin film transistor (TFT) fabricated based on the TeOx channel layer according to the present disclosure exhibits excellent output / transfer characteristics and superior electrical performance with high hole field-effect mobility and a high on / off current ratio of ˜107.

The invention belongs to the technical field of coated glass, and particularly provides a deposition method of a metal seed layer in TGV metallization and magnetron sputtering equipment. The invention aims to solve the problem of serious surface discharge phenomenon caused by low adhesive force between a metal film and a glass substrate, low metal coverage rate and step rate in a through hole and high accumulated charge on the surface of glass in the existing TGV metallization process. The independent and controllable ion source is introduced to assist deposition, the ion source is started at different stages of metal film deposition, and directional and high-energy positive ion flow generated by the ion source is utilized to bombard the surface of the glass substrate so as to assist the magnetron sputtering process, so that the surface of the glass substrate is subjected to magnetron sputtering. Through shallow ion implantation, enhancement of surface migration energy of deposited metal atoms and neutralization of negative charges accumulated on the glass surface, the adhesive force between metal and a glass substrate is improved, the metal coverage rate and the step rate in a through hole are improved, surface discharge is inhibited, and therefore the process stability is improved.

The invention discloses a preparation control optimization method of a metal ytterbium target for an OLED (Organic Light Emitting Diode) display screen. The method comprises the following steps: acquiring impurity spectrum scanning data of a metal ytterbium raw material, analyzing impurity distribution characteristics and determining a melting control temperature; after a cast ingot is formed, the internal pore distribution condition is obtained, a pore density gradient field is constructed, a forging and pressing path planning vector is generated, and precise forging and pressing path design is achieved; in the forging and pressing process, forging and pressing vibration data and displacement data are collected in real time, the influence of vibration on cast ingot position deviation is analyzed, then vibration deviation correction is conducted on a forging and pressing path, and an optimized path plan is formed. And by iteratively optimizing the forging and pressing path, the density of the cast ingot is gradually improved and meets the preset requirement. The method effectively solves the problems of difficult impurity control, non-uniform pore distribution, forging and pressing deviation and the like in the preparation process of the metal ytterbium target material, and the purity and compactness of the target material are remarkably improved.

Methods and systems are disclosed for depositing aluminum nitride thin films by reactive sputtering using a sequence of negative-polarity voltage pulses applied to an aluminum target, followed by a positive-polarity voltage pulse. HiPIMS-type waveforms may be used to implement the negative-polarity and / or positive-polarity pulses. A substrate is provided in a sputtering chamber, a process gas comprising an inert gas and a nitrogen-containing gas is introduced, and the chamber is maintained at a reduced pressure. A sequence of negative-polarity voltage pulses is applied to an aluminum target, followed by application of a positive-polarity voltage pulse to the target. The disclosed methods and systems can produce aluminum nitride thin films exhibiting improved crystallinity, thermal conductivity, and surface quality at reduced deposition temperatures (e.g., below 200° C.) and with deposition rates of at least about 50 nm / min suitable for industrial applications.

The invention relates to the technical field of coating production, in particular to a method for improving the corrosion resistance of a coating through a PVD and ALD composite preparation technology, according to the method, the advantages of PVD and ALD preparation technologies are combined to deposit the coating, ALD intercalation layers are deposited at different positions of the coating prepared through PVD, and therefore the defects generated in the PVD coating deposition process are overcome. And analyzing the section and phase of the deposited coating by utilizing characterization equipment, and detecting electrochemical and corrosive wear properties in a 3.5 wt.% NaCl solution. The PVD coating is subjected to intermediate or surface treatment by adopting an ALD preparation technology, so that the electrochemical performance of the coating is effectively improved.

The invention discloses a flexible hydrogel neural electrode and a preparation method and application thereof. The flexible hydrogel neural electrode comprises a flexible substrate layer, an electrode layer and a packaging layer which are sequentially arranged in a stacked mode, the flexible substrate layer and the packaging layer are each of a hydrogel fiber composite film structure formed by compounding a fiber film and hydrogel, and the fiber film is embedded in the hydrogel; the fiber film is a polycaprolactam fiber film, and the hydrogel is polyvinyl alcohol hydrogel; the electrode layer comprises a plurality of metal electrodes, and each metal electrode is provided with an electrode point and a bonding pad; the packaging layer is provided with a plurality of hole structures, and the holes are arranged corresponding to the electrode points and the bonding pads and enable the electrode points and the bonding pads to be exposed. The flexible hydrogel neural electrode provided by the invention has good biocompatibility, swelling resistance and process compatibility; meanwhile, the flexible hydrogel neural electrode can be stably applied to an implantable brain-computer interface and is used for realizing long-term stable acquisition and transmission of neural signals.

The invention provides a liquid crystal reflection line polaroid, a preparation method thereof and an optical system.The preparation method comprises the following steps that a substrate is placed in an evaporation cavity, and a plurality of first evaporation devices and a plurality of second evaporation devices are arranged in the evaporation cavity; preparing a photo-alignment material on the substrate to form a photo-alignment layer; evaporating a liquid crystal polymer precursor material on the substrate by adopting a plurality of first evaporation devices, and controlling the thickness of the formed liquid crystal polymer film by controlling the evaporation rate and / or the evaporation time of the plurality of first evaporation devices; evaporating an isotropic polymer precursor material on the liquid crystal polymer film by adopting a plurality of second evaporation devices, and controlling the thickness of the formed isotropic polymer film by controlling the evaporation rate and / or the evaporation time of the plurality of second evaporation devices; the preparation method is simple, and the thickness of each film layer can be accurately controlled.

The invention discloses a full-plane six-dimensional force sensor based on a thin film sputtering technology. The full-plane six-dimensional force sensor is used for synchronously measuring three-dimensional orthogonal force and torque. The sensor comprises a force transmission table, an elastic body, a base, a strain gauge and the like, wherein the elastic body adopts a composite structure of an inner-layer cross beam and an outer-layer honeycomb-like parallel beam. The innovation lies in that all strain sensitive areas of the elastomer are flat planes with upper and lower surfaces to form a full-plane design, so that the requirement of a thin film sputtering process on the flatness of a substrate is met. 24 strain gauges are sputtered on an upper plane and a lower plane to form 6 groups of Wheatstone bridges, so that six-dimensional force signal detection is realized. According to the full-plane structure, the problem that a strain gauge in a traditional sensor needs to be pasted on a narrow side face or edge is avoided, full-automatic surface mounting can be achieved, the long-term stability, temperature adaptability and measurement consistency of the sensor are remarkably improved, and the sensor is suitable for high-precision force measurement in the fields of industrial robots, aerospace and the like.

The invention discloses a positioning racking system for coating a large-size optical element. The positioning racking system comprises a main body structure, a lifting mechanism, a rotary bearing platform, a movement mechanism and a safety protection mechanism. A main body structure adopts a rigid design of composite support of a tripod and a tailstock. The lifting mechanism drives double ball screws to move synchronously through a worm and gear speed reducer, and precise lifting of the bearing platform is achieved. The rotary bearing platform can freely rotate by 360 degrees and is provided with a balance weight groove to adjust the gravity center. And the movement mechanism realizes flexible movement and stable support of the system. The safety protection mechanism integrates inclination angle, overload and limiting detection. The problems that a large-size and high-surface-shape-precision optical element is difficult to mount and position and poor in operation safety in the coating process are solved, and auxiliary mounting and positioning of a tool are safely, conveniently and precisely completed outside a coating machine.

A method and system for vacuum vapor deposition of a deposition material to form, a functional thin film coating, upon an elongate substrate, such as an optical fiber or structural member, in space may utilize: a depositor for the deposition material, disposed within a shroud enclosing the substrate as it exits from a space platform.

The invention discloses a gallium-cerium co-doped ITO target material and a preparation method thereof, and belongs to the field of transparent conductive oxide ceramic target materials, and the preparation method comprises the following steps: weighing indium oxide powder raw materials, tin oxide powder raw materials, gallium oxide powder raw materials and cerium oxide powder raw materials in proportion, and performing pretreatment; the raw material powder is subjected to independent ball milling till the raw materials reach the preset particle size; mixing the four kinds of slurry, and continuously performing ball milling to obtain uniform mixed slurry; adding a binder into the mixed slurry, and carrying out ball milling and mixing to form stable formed slurry; carrying out spray granulation on the formed slurry to obtain spherical precursor powder; pressing and forming the precursor powder to obtain a biscuit, then putting the biscuit into a sintering furnace, carrying out stepped sintering in an oxygen atmosphere, and naturally cooling to obtain the gallium-cerium co-doped ITO target material. According to the gallium-cerium co-doped ITO target material prepared by the method, the relative density is greater than or equal to 99.4%, the resistivity is less than or equal to 99.4%, and the three-point bending strength is greater than or equal to 230MPa.

A rotatable drum is provided for supporting a substrate. The rotatable drum includes a curved drum surface for supporting the substrate. The curved drum surface includes a dielectric portion and an electrode coupled to a power source. The electrode is electrically coupled to the curved drum surface and capable of chucking and dechucking the substrate from the curved drum surface at one or more circumferential segments of the curved drum surface.