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
  • C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
  • C23G5/00—Cleaning or de-greasing metallic material by other methods; Apparatus for cleaning or de-greasing metallic material with organic solvents
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B08—CLEANING
  • B08B—CLEANING IN GENERAL; PREVENTION OF FOULING IN GENERAL
  • B08B7/00—Cleaning by methods not provided for in a single other subclass or a single group in this subclass
  • B08B7/02—Cleaning by methods not provided for in a single other subclass or a single group in this subclass by distortion, beating, or vibration of the surface to be cleaned

Definitions

• the present invention proposes a device and a method for cleaning surfaces with a gas beam in a vacuum and ultra high vacuum.
• the device and method disclosed by the present invention are based on the bombardment of molecules and aggregates, and not of ionized particles, as is the case in the state of the art. This entails significant advantages and avoids the disadvantages of the devices and methods associated with the state of the art.
• the scope of the present invention is any where cleaning of a surface with controlled surface contamination is required.
• Some fields of application are found in the chemistry and pharmacy sectors, in rubber and plastic materials, metallurgy and manufacturing of metal products, electrical, electronic and optical material and equipment and nanotechnology, among many others.
• the ions are accelerated to the surface to be cleaned thanks to an electric potential of hundreds to thousands of electron volts. Due to their great kinetic energy, the ions erode the surface tearing away the impurities present. This method of cleaning surfaces is very effective, but produces defects; in addition, some argon ions are implanted on the surface and it is necessary to remove them by heating.
• the most advanced models of ion cannons have their own differential pumping to pump the non-ionized noble gas and thus avoid its introduction into vacuum or ultra-high vacuum devices.
• the device proposed in the present invention is based on a beam of argon molecules or other noble gas which, by its aggregation and kinetic energy, is capable of cleaning the surfaces of the object to be cleaned.
• the molecule cannon or gas cannon (so called in the present invention) does not need the emission of electrons to ionize the noble gas molecules or ion acceleration potential, which represents an advantage at the time of its use.
• the molecule cannon is based on a chamber with a noble gas and a funnel ⁇ skimmer), differentially pumped. The high pressure in the gas chamber, together with the funnel and differential pumping, produce a bundle of gas aggregates capable of reaching a kinetic energy large enough to tear molecules from the surface to be cleaned by inelastic shocks, thus obtaining mode clean the surface of contaminants.
• the present invention has the following advantages over prior art devices: • It is compatible with vacuum and ultra high vacuum.
• the present invention has two aspects.
• the first aspect of the invention is a device for cleaning surfaces with a gas beam in a vacuum and ultra high vacuum.
• the device of the present invention is connectable with a vacuum or ultrahigh vacuum system that comprises at least the surface of an object to be cleaned.
• the device comprises:
• a funnel comprising an outlet connectable with the differential pumping system and with the vacuum system or ultra high vacuum;
• the molecules of the non-ionized gas enter the aggregation zone, where they are accelerated by differential pumping, so that the molecules collide with each other forming a bundle of molecular aggregates, which cross the funnel outlet until they collide with the surface of the object to be cleaned.
• the high pressure in the chamber together with the funnel give the molecular aggregates enough kinetic energy to cause inelastic shocks that release contaminants from the surface to be cleaned.
• differential pumping operates according to the physical principle known as the "Venturi effect". Due to the Venturi effect, The narrowing of the funnel outlet causes the acceleration of the molecular aggregate beam. The speed and kinetic energy of the aggregate beam molecules are controllable through the efficiency of differential pumping.
• the diameter of the molecular aggregate beam is also controllable by the diameter of the funnel outlet. Alternatively or jointly, the diameter of the molecular aggregate beam is also determined by the surface area of the object to be cleaned.
• the device of the present invention further comprises a cooling system
• the chamber further comprises walls cooled by the cooling system to a predetermined temperature that increases the amount of molecular aggregates.
• the device of the present invention further comprises a pressure meter connectable with the chamber for controlling the pressure in the aggregation zone.
• the non-ionized gas is a noble gas.
• the non-ionized gas is argon gas.
• the other aspect of the present invention is a method for cleaning surfaces with a gas beam in a vacuum and ultra high vacuum.
• the method comprises the following steps: i) inserting a non-ionized gas into a chamber, where the non-ionized gas is composed of molecules;
• i) produce a bundle of molecular aggregates by a combined action of high pressure and a funnel connected to a differential pumping system; iii) channel the molecular aggregates through the funnel and pass them through a hole in the chamber until they reach a surface of an object to be cleaned located in a vacuum system so that the molecular aggregates produce inelastic shocks on the surface and remove contaminants of the surface of the object to be cleaned.
• step ii) comprises increasing the number of molecular aggregates by cooling the chamber walls. This increases the capacity of the device of the present invention to clean the surface of the object to be cleaned. Brief description of the figures.
• Figure 1 shows a block diagram of the device associated with the present invention. That is, a device for cleaning surfaces with gas beam in vacuum and ultra high vacuum.
• Figure 2 shows an example of cleaning the platinum surface with the Argon molecular aggregates beam produced by the device of the present invention compared to the result obtained by an ion device.
• Figure 3 shows a flow chart of the method associated with the present invention. That is, a method for cleaning surfaces with a gas beam in vacuum and ultra high vacuum.
• the device of the present invention 1 comprises a system compatible with vacuum or ultra high vacuum, as presented in Figure 1.
• the device 1 of the present invention or gas cannon is connected to another vacuum system or ultra high vacuum 2 where the surface 3 of the object to be cleaned is placed 4.
• the gas barrel 1 has a gas inlet 7 through which a high pressure gas is injected, which in the case shown in figure 1, is argon 11 (non-ionized gas ).
• argon 11 non-ionized gas
• gas flows are typically regulated with a mass controller (not shown).
• the aggregation zone 8 of the chamber 6 is refrigerated to favor the formation of the aggregates.
• a cooling system 13 is used that cools the walls 14 of the chamber 6.
• the cooling system 13 can use water or liquid nitrogen as a refrigerant.
• the aggregation zone 8 is differentially pumped by a differential pumping system 5 comprising a set of pumps: a turbomolecular and a primary pump, although in other examples other types of pumps can be used, depending on the desired pressure ranges obtained in the aggregation zone 8.
• the pressure is controlled indirectly in the aggregation zone 8 thanks to a pressure gauge 15, as shown in Figure 1.
• the molecular aggregate beam 12 of Argon gas leaves the aggregation zone 8 through the outlet 10 of the funnel 9, the outlet 10 being located between the aggregation zone 8 and the vacuum system or ultra high vacuum 2 where the surface 3 of the object to be cleaned is placed 4.
• the diameter of the orifice of the funnel outlet 10 can be modified to vary the diameter of the beam of molecular aggregates 12 and, therefore, the cleaned area of the surface 3.
• the aggregates are able to remove contaminants from the surface such as adsorbed molecules and oxides.
• the kinetic energy, as well as the aggregate flow, is regulated by the argon flow, the pumping power and the opening of the hole between the aggregation zone and the vacuum system or ultra high vacuum where the surface to be cleaned is placed.
• the dimensions of the gas cannon are adaptable to the needs.
• the device of the present invention (gas cannon) has an approximate diameter of 30 cm and an approximate length of 50 cm. These dimensions can be modified, provided that the conditions of gas dynamics are preserved for the generation of aggregates of gas molecules and their subsequent injection into the vacuum system where the surface of the object to be cleaned is placed.
• Figure 2 shows an example of cleaning the platinum surface with the beam of argon molecular aggregates produced by the device of the present invention (gas cannon). The quantification of the contamination on the surface has been carried out by means of photoemission.
• the photoemission measurement equipment is an ultra-high vacuum equipment independent of the gas cannon, so, after exposure to the flow of argon aggregates, the surfaces were extracted from the ultra-high vacuum system connected to the gas cannon and exposed to the atmosphere during its transfer and introduction into the ultra high vacuum photoemission system. Despite its exposure to air (which increases the presence of contaminants and surface oxides), it has been observed that the surfaces exposed to the flow of Argon aggregates were cleaner than the original surfaces without cleaning treatment (reference surface ).
• Figure 2 shows the photoemission spectra of the Pt4f levels of the reference surface (contaminated and oxidized) and the surface exposed to the gas cannon for 150 minutes with an Argon input flow of 35 sccm ⁇ standard cubic centimeters per minute, standard cubic centimeters per minute). Differences can be observed between the spectra and, in particular, in the intensity of the different components of the photoemission peaks obtained after a deconvolution analysis.
• the peaks associated with oxides and metallic platinum have been shown in Figure 2.
• the quantification of metallic and oxidized platinum on the surface is presented in Table 1.
• the photoemission spectra of a similar surface exposed to a flow of argon ions of energy 1.4 keV during 150 are also presented minutes (ion cannon, classic surface cleaning method) and the corresponding quantification in table 1.
• Figure 3 shows a flow chart of the method associated with the present invention.
• the method for cleaning surfaces with a gas beam in a vacuum and ultra high vacuum comprises the following steps: i) inserting a non-ionized gas into a chamber, where the non-ionized gas is composed of molecules; ii) produce 17 a bundle of molecular aggregates by a combined action of high pressure and a funnel connected to a differential pumping system; and, iii) channeling 18 the molecular aggregates through the funnel and passing them through a hole in the chamber to reach a surface of an object to be cleaned, located in a vacuum system such that the molecular aggregates produce inelastic shocks on the surface and remove contaminants from the surface of the object to be cleaned.
• step ii) comprises, as a sub-step, increasing the number of molecular aggregates by cooling the walls of the chamber. In this way we increase the ability of the device of the present invention to clean the surface of the object to be cleaned.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Cleaning In General (AREA)

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Citations (1)

• 2013
  • 2013-07-08 WO PCT/ES2013/070486 patent/WO2014009583A1/fr not_active Ceased

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