# US 7,444,955 B2 · Apparatus for directing plasma flow to coat internal passageways > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,444,955 B2 - Document ID: US7444955B2 - Status: Granted - Kind: B2 - Application number: 10/850,474 - Filed: 2004-05-19 - Published: 2005-11-24 - Granted: 2008-11-04 - Earliest claimed: 2004-05-19 - Assignees: Sub-One Technology, Inc. - Inventors: William John Boardman; Raul Donate Mercado; Andrew William Tudhope - Web page: https://patentgrep.com/patent/US7444955B2 ## CPC - C23C 14/325: {Electric arc evaporation} - C23C 14/046: {Coating cavities or hollow spaces, e.g. interior of tubes; Infiltration of porous substrates} - C23C 14/50: Substrate holders - H01J 37/32357: {Generation remote from the workpiece, e.g. down-stream} - 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 (making metal-coated products by extrusion B21C23/22; covering with metal by connecting pre-existing layers to articles, see the relevant places, e.g. B21D39/00, B23K; metallising of glass C03C; metallising mortars, concrete, artificial stone, ceramics or natural stone C04B41/00; enamelling of, or applying a vitreous layer to, metals C23D; treating metal surfaces or coating of metals by electrolysis or electrophoresis C25D; single-crystal film growth C30B; by metallising textiles D06M11/83; decorating textiles by locally metallising D06Q1/04) - H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H) ## Abstract An apparatus for coating surfaces of a workpiece is configured to establish a pressure gradient within internal passageways through the workpiece, so that the coating within the internal passageways exhibits intended characteristics, such as those relating to smoothness or hardness. The coating apparatus may include any or all of a number of cooperative systems, including a plasma generation system, a manipulable workpiece support system, an ionization excitation system configured to increase ionization within or around the workpiece, a biasing system for applying a selected voltage pattern to the workpiece, and a two-chamber system that enables the plasma generation to take place at a first selected pressure and the deposition to occur at a second selected pressure. ## Claims ### Claim 1 An apparatus for coating surfaces of a workpiece having at least one internal passageway comprising: a plasma source for generating a plasma which includes ions of a coating material to be deposited on said surfaces of said workpiece; a support configured to secure said workpiece in a specific orientation in spaced apart relationship with respect to said plasma source; a plasma flow system enabled to direct a controlled flow of said plasma having said ions from said plasma source into each said internal passageway and to exhaust said plasma from said workpiece when said workpiece is secured to said support; and an ionization excitation system configured to increase ionization said plasma while within said workpiece, said ionization excitation system including a biasing arrangement applied to said workpiece when said workpiece is secured to said support, said ionization excitation system further including a pressure control set to induce oscillation of electrons of said plasma within said workpiece, such that said ionization excitation system is configured to apply hollow cathode techniques within said workpiece. ### Claim 2 (depends on 1) The apparatus of claim 1 wherein said support positions said workplace in a deposition chamber and wherein said plasma flow system defines a pressure regime in which at least one internal passageway opening of said workpiece is exposed to said deposition chamber and at least one other internal passageway opening of said workpiece is exposed to a pumping system of said plasma flow system, such that flow Is directed through each said internal passageway with entrance and exit of said flow being through said internal passageway openings. ### Claim 3 (depends on 1) The apparatus of claim 1 wherein a flow rate through each said internal passageway is controllable by variation of an adjustable opening in said support from said deposition chamber to said pumping system. ### Claim 4 (depends on 1) The apparatus of claim 1 further comprising a low pressure source chamber and a high pressure deposition chamber, said plasma source being located within said low pressure source chamber, said support being positioned such that said workpiece is within said high pressure deposition chamber, said low pressure deposition chamber being connected to a vacuum source which maintains a lower pressure than within said high pressure deposition chamber. ### Claim 5 (depends on 4) The apparatus of claim 4 wherein said low pressure source chamber and said high pressure deposition chamber combine to form a cathodic arc system. ### Claim 6 (depends on 5) The apparatus of claim 5 wherein said cathodic arc system provides physical vapor deposition (PVD), said plasma flow system including a magnetic steering region in which a magnetic field is established to direct ionized plasma from said plasma source to said workpiece. ### Claim 7 (depends on 6) The apparatus of claim 6 wherein said plasma flow system further includes a vacuum control arrangement having a first evacuation of said low pressure source chamber and a second evacuation of said high pressure source chamber, said second evacuation being through said workpiece, such that (a) said magnetic steering region defines a first flow regime; and (b) said second evacuation defines a second flow regime. ### Claim 8 (depends on 4) The apparatus of claim 4 wherein an interface region from said high pressure source chamber to said low pressure deposition region has a decreasing cross sectional dimension. ### Claim 9 (depends on 8) The apparatus of claim 8 wherein said interface region is biased to repel ions of said plasma. ### Claim 10 (depends on 1) The apparatus of claim 1 further comprising a device for increasing ionization of said plasma in an area of said support. ### Claim 11 (depends on 10) The apparatus of claim 10 wherein said device is a microwave source. ### Claim 12 (depends on 10) The apparatus of claim 10 wherein said device is one of a radio frequency (RF) source, an electron cyclotron resonance (ECR) source or a distributed ECR source. ### Claim 13 (depends on 1) The apparatus of claim 1 wherein said biasing arrangement applies a bias to said workpiece to attract ions to surfaces of each said internal passageway of said workpiece. ### Claim 14 (depends on 13) The apparatus of claim 13 further comprising a biasing source for adjusting a bias magnitude and a duty cycle of said bias connection to said workpiece. ### Claim 15 (depends on 1) The apparatus of claim 1 wherein said support is configured to capture said workpiece having a plurality of said internal passageways in which said internal passageways have different cross sectional dimensions, said plasma flow system being cooperative with said support such that said plasma enters each of said internal passageways to form a continuous flow therethrough. ### Claim 16 (depends on 15) The apparatus of claim 15 wherein said plasma flow system is adjustable with respect to defining flow rates through said internal passageways of said workpiece. ### Claim 17 (depends on 1) The apparatus of claim 1 wherein pressure within said internal passageways obtained by using said plasma flow system results in an electron mean free path that is equal to or less than a minimum internal diameter of said at least one internal passageway, such that application of a negative bias to said workpiece by said biasing arrangement generates a hollow cathode condition for generating and maintaining ionization of a background gas, said biasing arrangement comprising a biasing source. ### Claim 18 (depends on 17) The apparatus of claim 17 wherein said biasing source has an adjustable duty cycle and magnitude to enable changes in the coating quality during deposition, said negative bias being selected to cause re-sputtering of said coating material initially deposited at each upstream end of said at least one internal passageway for redeposition downstream of said upstream end, wherein re-sputtered coating material is carried downstream with velocity of flow. ### Claim 19 A coating apparatus comprising: a plasma generation system for supplying an ionized plasma using cathodic arc techniques, said plasma generation system being configured to supply said ionized plasma to include ions of coating material to be deposited; a deposition chamber downstream of said plasma generation system with respect to plasma flow; a workpiece support system within said deposition chamber to position a workpiece such that said plasma flow necessarily and continuously is through all of a plurality of internal passageways within said workpiece; and an ionization excitation system configured to increase ionization of said coating material within said plasma flow through said internal passageways, said ionization excitation system including a biasing arrangement and pressure control configured to induce oscillations of electrons within said plasma flow, so as to apply hollow cathode techniques within each said internal passageway; wherein said internal passageways are coated via physical vapor deposition (PVD). ### Claim 20 (depends on 19) The coating apparatus of claim 19 wherein said pressure control is an element of an adjustable flow control system configured to set plasma flow rates through said internal passageways of said workpiece.