Classifications

• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
  • C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
  • C23C14/34—Sputtering
  • C23C14/35—Sputtering by application of a magnetic field, e.g. magnetron sputtering
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
  • C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
  • C23C14/34—Sputtering
  • C23C14/35—Sputtering by application of a magnetic field, e.g. magnetron sputtering
  • C23C14/352—Sputtering by application of a magnetic field, e.g. magnetron sputtering using more than one target
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
  • C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
  • C23C14/50—Substrate holders
  • C23C14/505—Substrate holders for rotation of the substrates
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
  • C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
  • C23C14/56—Apparatus specially adapted for continuous coating; Arrangements for maintaining the vacuum, e.g. vacuum locks
  • C23C14/564—Means for minimising impurities in the coating chamber such as dust, moisture, residual gases
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
  • H01J37/32—Gas-filled discharge tubes
  • H01J37/34—Gas-filled discharge tubes operating with cathodic sputtering
  • H01J37/3402—Gas-filled discharge tubes operating with cathodic sputtering using supplementary magnetic fields
  • H01J37/3405—Magnetron sputtering
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
  • H01J37/32—Gas-filled discharge tubes
  • H01J37/34—Gas-filled discharge tubes operating with cathodic sputtering
  • H01J37/3411—Constructional aspects of the reactor
  • H01J37/3414—Targets
  • H01J37/342—Hollow targets

Definitions

• the invention relates to methods and apparatus for producing one or more particle-poor layers on substrates in a vacuum.
• the layers are made of cylindrical source material, optionally together with a reactive gas component
• Magnetron sputtering applied to the substrate.
• the application of the layer takes place against the
• the layers can optionally be modified by a plasma source in its structure or stoichiometric atomic composition. which source materials are provided so that several layers of different composition can be applied to the substrate in a high-speed process.
• Precision optical filters are a key component of many industrial products of optical technologies. Applications range from laser technology to medical and bioprocess engineering, display and automotive to the solar industry. Due to the ever-increasing technological demands as well as the increasing competition from low-wage countries, the demand for better, more flexible and at the same time economical production process for optical precision coatings is growing. Today's processes increasingly come up against technological limits with particularly high demands: increasing scrap, too little long-term stability and the
• Optical thin-film systems that use the principle of interference, for example for laser technology, medicine and bioprocess engineering, display and automotive technology up to the solar industry, require the most precise compliance with the specified filter properties and low absorptions and losses in the optical filter.
• the layer properties to be achieved often require conflicting process conditions.
• a high layer hardness and stable coating with a very smooth surface usually correlate with compressive layer stresses, while layers without stress are usually rough and show a strong temperature and moisture dependence (spectral shift).
• the morphology and thus the layer properties in plasma coating processes are essentially due to the type and energy distribution of both ions as well as of neutral particles, whereby the particle energies of ions and neutral particles can vary greatly depending on the plasma conditions.
• the optical properties are affected by the particle bombardment (e.g., with sputtering gas particles) of the growing layer.
• the particle bombardment e.g., with sputtering gas particles
• the incorporation of argon into oxidic or fluoridic layers causes increased absorption.
• Energetic neutral particles meeting the growing layer can, for example, induce Frenkel defects (Hisashi Arakaki, Kazutoshi Ohashi and Tomoko Sudou, "Sputter-induced defects in zn-doped GaAs Schottky diodes ", Semicond, See, Technol., 19, No. 1 (January 2004), pp. 127-132.) Nanodefects are playing an increasingly important role in high performance optics for ultra-short pulse or uv laser applications.
• a disadvantage of this dynamic stabilization is that even with optimal control small residual fluctuations of the process conditions and thus also the stoichiometry of the layer can not be avoided, which can lead to low inhomogeneities and thus to loss mechanisms.
• Inhomogeneities can be, for example, an optical loss ⁇ eg loss of intensity), dispersion deviations and / or deviations in the dispersion. Cause sorption. Especially with very high-quality optical layers such inhomogeneities cause serious problems. Therefore, in the prior art, the approach of
• a disadvantage of the "sputter-down" method is therefore that particles are accelerated by the gravitational acceleration in the direction of the substrate and are not accelerated away from the substrate, so that particles can pass unhindered onto the substrate in the sputter-down process.
• the influence of the particles on the quality of the product is neglected.
• the question of particles in coating processes is of great practical importance. Particles or general defects on the substrate degrade the coating and usually lead to exclusion. This question is becoming increasingly important in the wake of growing demands and increasing miniaturization.
• a method for producing particle-poor layers on moving substrates in a vacuum chamber by means of at least one magentron sputtering device, wherein the
• Layers of cylindrical source material are formed, in which the following steps are provided: Immobilizing the substrate by means of a substrate holder on a turntable;
• At least one plasma source can be used.
• the plasma source can pretreat the surface of the substrate via plasma exposure, optionally together with reactive gas (e.g., cleaning the surface).
• reactive gas e.g., cleaning the surface.
• the structure and / or the stoichiometry of the layer can be modified by plasma action of a plasma source, optionally together with reactive gas.
• the at least one plasma source can be controlled by the turntable.
• Magnetron sputtering sources have proven to be extremely powerful coating tools in recent years to produce thin film systems on an industrial scale.
• magnetron sputter sources with cylindrical source material are used. applies.
• Electrode are especially for optical coatings and the associated claims
• cylindrical sources there is no problem of planar targets in that an erosion trench forms on the surface of the targets, which leads to a change in the layer thickness distribution.
• cylindrical sources can provide an ideal layer thickness distribution over the entire
• Target life are met.
• the throughput of cylindrical sources is increased over planar sources and the process has higher long-term stability.
• the magnetron sputtering sources are used in a so-called “sputter-up” arrangement.
• “Sputtering-up w means that the cylindrical source material is deposited against the gravitational axis, ie upwards (on the substrate) As a result, heavy particles are accelerated more toward the gravitational force, that is, they are accelerated away from the substrate and are prevented from being deposited on the target (substrate) To separate the disturbance factor.
• the "sputter-up" arrangement increases the productivity of the coating process, in particular the quality of the coated components is thereby increased. siege.
• Other important reasons for the “sputter-up" arrangement with cylindrical magnetron electrodes (targets) are the long-term stability of the
• Cylindrical sources do not have a redeposition zone. This has the further advantage in reactive processes that results in a higher process cleanliness. Furthermore, the homogeneous removal of a cylindrical target changes the
• Planar targets have particularly in the "sputter-up n - configuration with respect to the cylindrical target to a further disadvantage. Particles generated by planar source materials (targets) can cause a short circuit by falling into the dark space of the target. Especially with coating concepts based on turntable arrangements, this would destroy the entire batch. Because cylindrical sources do not have dark space, they are much preferred in the "sputter-up w " configuration with turntable array versus planar sources.
• ne plasma source used for the treatment of substrate.
• An important goal of this plasma treatment is a pretreatment of the substrate before the actual coating by the immediate degradation of organic compounds on the substrate. It is necessary to pretreat the substrate so that it is as free of foreign particles as possible. As a result, the quality of the sputtered layers with regard to scattering, absorption and damage thresholds can be considerably improved. As a result, flat substrates (eg, lenses) having significantly improved properties can be provided by the method of the present invention.
• the method according to the invention is particularly advantageous for laser systems, edge filters, fluorescence filters, bandpass filters, reflectors for different wavelengths, antireflection coating, pre-reflection, cavity filters and / or UV-IR cuts.
• Layers can become one between the layers
• the interface can be supersaturated with 0 2 and / or fully reactive deposited a layer. This procedure can prevent
• the optional treatment with plasma aims at a reduction in the size of interfaces between two layers, in which mixtures of the two at the boundary layer
• the vacuum chamber within the magnetron sputtering apparatus may comprise a process pressure in the range of 3 x 10 ⁇ 4 in the inventive method and / or apparatus of the invention - comprise 5 x 10 -2 mbar.
• the partial pressure of the sputtering gas and / or of the reactive gas can be regulated or stabilized via a generator, preferably by controlling the generator power, the generator voltage and / or the generator current.
• the advantage of this regulation is that in the method according to the invention no dielectric layer is removed from the target, but the target is not covered with a dielectric layer at any time.
• This can be realized, for example, by operating metallic targets in the so-called "transition mode.”
• the cylindrical source material ⁇ target) is permanently in a metallic, oxide-free state by suitable regulation of the generator, while sufficient oxygen is available in the process space
• the above-mentioned manipulated variables are generally realized on the oxygen partial pressure or the voltage of the generator or the target, which allows the deposition of stoichiometric layers with a high deposition rate to be achieved in the process the disturbing influence of
• the turntable of the device in the method at a rate of 1-500 U-min -1, preferably 150-300 U-min "1, rotate. For a high
• the plasma source serves to reduce layer stress in a layer on the substrate, preferably by minimizing the boundary layer thickness and / or minimizing the boundary layer extent between individual layers on the substrate.
• the plasma source fulfills at least one of the following functions:
• the thickness of the layer on the substrate can be controlled by optical transmission monitoring, optionally via polarized transmission measurements, optical reflection monitoring, optionally via polarized reflection measurements, optical absorption monitoring, and / or single-wavelength ellipsometry or spectral ellipsometry.
• a heatable element is attached to the lid of the device in a preferred embodiment of the device.
• the temperature of the heatable element on the lid of the device is preferably set as a function of the layer to be produced.
• the temperature can also be changed during the coating process to meet the requirements of a particular layer, the temperature of the heatable element on the lid can be controlled to a value of 50 to 450 ° C.
• the temperature of the substrate can be adjusted in a range of room temperature (about 20 ° C) and 300 ° C.
• the lid is thermally insulated from the rest of the device.
• the device according to the invention for producing particle-poor layers on at least one moving substrate in vacuo by means of magnetron sputtering comprises the following features: at least one magnetron sputtering device with cylindrical source material, a generator, sputtering gas and optionally reactive gas;
• a lid preferably with heatable element; such as
• the device is characterized in that the
• Lid closes the device gas-tight and the turntable, the at least one magnetron sputtering gas-tight manner.
• the at least one magnetron sputtering device is designed in such a way. tet, that it precipitates source material, optionally together with a component of reactive gas, against gravity towards the substrate.
• the device contains at least one plasma source, which optionally has reactive gas.
• the at least one plasma source can be closed in a gastight manner by means of the turntable of the device with an effective gas separation for gases of 1:25, preferably of 1: 100.
• the turntable is located above the plasma source.
• the turntable is preferably located above the magnetron sputtering means and, if present in a preferred embodiment, the plasma source.
• the magnetron electrode can be a target containing or consisting of a material selected from the group consisting of ceramic material or mixtures of materials, thermally sprayed material or mixtures of materials, crystalline material, metallic material or material mixtures and / or an oxide-containing material, or also
• the magnetron electrode preferably consists of a target containing or consisting of ceramic material.
• TERIAL The already mentioned compressive stresses in optical layers are of great importance. They lead to bending of the optics or also to the delamination of the layer or even to the breakage of the substrate. With ceramic targets offers in the
• the magnetron electrode may contain or consist of a target containing or consisting of oxide-containing material.
• Oxide-containing materials have the advantage of providing an oxygen source. Sometimes extra oxygen is needed in the sputtering area, for example because the oxygen of the plasma source is not sufficient for oxidation or because higher coating rates are to be achieved.
• the rate is independent of the coverage with an oxide layer.
• Preferred oxide-containing materials are TiO x , TaO x , NbO x , ZrO x , ZrO x : Y, HfO x , AlO x , SiO x , ZnO x , lnSnO x and / or SnO x , with x being particularly preferably chosen in that the target has just a conductivity, but at the same time x is close to the stoichiometry.
• the distance from the magnetron electrode to the substrate may be 2 to 10 cm, preferably 6 to 8 cm, more preferably 7 cm.
• the advantage of this distance is that a homogeneous coating of small components with high density and high precision is possible. At higher magnetron electrode to substrate distances, the precision of the coating process decreases.
• a distance of 0.1 to 5 mm, preferably 1 to 3 mm, particularly preferably 2 mm, is provided according to the invention.
• the magnetron sputtering device may comprise a single magnetron arrangement.
• the magnetron sputtering device preferably has a double magnetron arrangement.
• the advantage of this arrangement is that more of the source material can be deposited per time spent by the substrate on the magnetron sputtering device compared to a single magnetron arrangement. The result is a much higher efficiency of the sputtering process.
• the use of double magnetron arrangements with bipolar excitation can ensure better long-term stabilities due to the "non-vanishing anode" and higher plasma densities in combination with denser (but also more strongly strained) layers.
• Pulsed DC is particularly good for coating temperature-sensitive substrates such as polymers, where the pulse frequency is also in the mid-frequency range due to the lower ion energy and ion current density of a pulsed DC plasma compared to an MF plasma.
• RF sputtering can also be used for insulating target materials. This is for example the Case for SiO x , A10 X , but also other oxides, nitrides or even fluoridic targets. Thus, for example, gF 2 or other fluorides could be sputtered. Therefore, the process stability can be increased again, since it can be used with stoichiometric targets. It is advantageous in this case that the forming (insulating) back coating regions cause no problems due to discharging (arcing), the layers can thus be deposited very particle-free.
• the device may advantageously include a DC power supply, pulsed DC power supply, or a device for generating HIPIMS, center frequency, or RF discharges.
• the device preferably contains two, optionally also three, magnetron sputtering devices.
• the advantage of such embodiments arises especially in the case of ultilayer coatings, ie in the coating of a substrate with several different layers.
• two magnetron sputtering devices can generate stacks of two types of layers which have different material (source material).
• source material material
• three magnetron sputtering devices it is possible to sputter stacks of three types of layers onto the substrate, each having a different material.
• material mixtures can also be produced from the respective source materials, ie mixed layers can be deposited.
• the use of two magnetron sputtering devices for optimizing the layer properties is very advantageous.
• three or more magnetron sputtering devices may prove advantageous.
• Sputtering device is prevented from entering a further magnetron sputtering device of the same device.
• the amount of inert gas and / or reactive gas can be adjusted more precisely to a certain predefined value and / or kept constant by the effective gas space separation.
• Plasmas based on magnetron discharges typically consist of more than 99% non-ionized particles. These can have high energies and therefore contribute greatly to layer stresses. They can be influenced indirectly, for example by changing the magnetic field design or by using alternative sputtering gases.
• the sputtering gas may contain or consist of a noble gas. Preferred noble gases are argon, neon, xeon and krypton. Noble gas mixtures are also possible.
• the reactive gas may according to the invention contain or consist of an oxidizing gas. Preferred reactive gases are oxygen, nitrogen, tetrafluoromethane, octafluorocyclobutane, carbon dioxide and fluorine-hydrogen. Mixtures of these gases can also be used.
• the device preferably contains a photometer and / or an ellipsometry flanges. This makes it possible to photometrically control the thickness of the layer on the substrate during the sputtering process. For this, a fast broadband measurement (e.g., from 300 to 1000 ⁇ m) of the transmission or reflection can be performed. By comparison with the theoretically expected spectrum, the layer thickness can be determined and controlled. In some cases, an oscillating quartz may additionally be used, for example in cavity filters in which, for certain layers, only a slight signal change of the transmission is expected.
• an ellipsometry measurement can also be performed. This must be done at an angle of incidence between about 55 ° and 75 ° degrees to the normal, preferably at 65 °.
• In-situ ellipsometry is also very advantageous in order to determine the dispersion of the refractive index (and, if appropriate, absorption index), since this must be known exactly in broadband monitoring with transmission or reflection measurement.
• Tp and Ts are the component of the transmission polarized parallel or perpendicular to the plane of incidence
• Rp and Rs are the components of the reflection which are polarized parallel or perpendicular to the plane of incidence.
• the monitoring of the layer also takes place at an oblique angle of incidence.
• ellipsometry is often too slow, especially at the high rotational frequencies sought here. Therefore, the measurement of the Rp and Rs components (or Tp and Ts) can be used very advantageously here.
• the measurement can be carried out at 45 ° angle of incidence, wherein a statically arranged polarizer is used. Two beam paths can be used for two polarizations.
• a component of the polarization can be selected and the spectrum can be combined with the transmission measured at vertical incidence. This achieves the same short measurement time (in the msec range) as in the transmission measurement.
• the polarization of the measurement with polarized light is also particularly suitable for controlling thin metallic layers (eg silver or aluminum), which are used, for example, in polarizing beam splitters.
• the substrate superconductor of the turntable comprises or consists of polyetheretherketone.
• polyetheretherketone has the advantage that particle formation is reduced.
• Fig. 1 shows a sketch of a preferred device according to the invention without turntable in the
• Fig. 2 shows a sketch of a preferred device according to the invention with turntable in plan view.
• Fig. 3 shows a sketch of a preferred device according to the invention with turntable in the side view.
• Figure 1 shows schematically in plan view a preferred device according to the invention without turntable.
• the device comprises three magnetron sputtering devices 2, 3, 4, one of which is in the single Magnetronanordung 2 and two in the Doppelmagnetronan extract 3, 4 are configured.
• the magnetron sputtering apparatus 2 includes a
• Magnetron electrode 5 Magnetron electrode 5, sputtering gas 11, optionally reactive gas 8 and is in a vacuum 1. Die
• Magnetron sputtering devices 3, 4 each contain two magnetron electrodes 6, 7, sputtering gas 11, optionally reactive gas 8 and are in vacuum 1. In the vicinity of the magnetron sputtering devices 2, 3, 4 there is a plasma source 12 and a photometer 16 and / or an ellipsometry flanges 17.
• Figure 2 shows schematically in plan view a preferred embodiment of the turntable.
• the turntable 10 is located in the device and has ten identical substrate holders 9 in this example.
• Figure 3 shows schematically in side view a preferred embodiment of the device with turntable 10. It is the cross section of a
• Magnetron sputtering visible which contains two cylinders of source material 6, 7
• the magnetron sputtering device is on the sides of boundary walls 14, 15 and top defined by the turntable 10 gas-tight from the rest of the device, contains sputtering gas 11, optionally reactive gas 8, and is under vacuum 1.
• Two substrate holders 9 of the turntable 10 are in represented or visible in the cross section. Above the turntable 10 is a lid

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