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Electroless plating apparatus and methodRelated Patent Categories: Chemistry: Electrical And Wave Energy, Apparatus, Electrolytic, Cells, With Feeding And/or Withdrawal MeansElectroless plating apparatus and method description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20060081461, Electroless plating apparatus and method. Brief Patent Description - Full Patent Description - Patent Application Claims
FIELD OF THE INVENTION [0001] The present invention relates to an electroless plating apparatus and method for plating a surface of a substrate, e.g., a surface of a wiring metal of a semiconductor substrate by supplying an electroless plating solution thereonto. BACKGROUND OF THE INVENTION [0002] A multilayered structure of a semiconductor device is formed by stacking interlayer insulating films, into which wirings are embedded, at multiple levels. As a typical wiring material that is resistant to electromigration, a copper has been preferably used. Further, as a method for forming the wiring, there has been employed a damascene process: wherein a recess portion having a groove is formed in an interlayer insulating film to be filled with a copper; and a residual copper is polished by a so-called CMP (chemical mechanical polishing). [0003] Recently, as a technology for carrying out such a copper wiring, a possibility of introducing an electroless plating method has been studied. An electroless plating is a method for forming a metal film by using electrons supplied from a reducing agent added in a plating solution without using an electrolysis from the outside; and the method is applied in a technology for forming a copper seed layer in a recess portion before it is filled with the copper, or in a technology for forming a coating made of CoWP (cobalt tungsten phosphide) as an adhesion layer between a barrier film and the copper before forming the barrier film on a copper wiring (e.g., a film such as silicon nitride, silicon carbide, silicon carbon nitride or the like). [0004] As for the electroless plating, reference 1 discloses that, e.g., both upper and lower sides of a semiconductor wafer (hereinafter, referred to as a wafer), a periphery of which is supported by a chuck, are heated by temperature control plates, and at the same time an electroless plating solution heated to a predetermined temperature, e.g., a set temperature within a range between room temperature and 60.degree. C., is supplied onto a surface of the wafer through an upper plate. [0005] However, since the reducing agent as an electron supply source is included in the electroless plating solution, so-called precipitation in solution, i.e., precipitation of a metal in solution, is likely to be produced in case when the reducing agent is used, particularly when it is heated. If precipitation in solution is produced, the condition of the electroless plating solution becomes changed, and therefore, the electroless plating processing of inter-wafer is changed accordingly. For example, a film thickness of a coating becomes non-uniform, and precipitated particles may cause a particle contamination and bring about clogging of pipe in the electroless plating apparatus. Reference 1 hasn't paid any attention on such an unstability of the electroless plating solution. [0006] Reference 1: Japanese Patent Laid-open Application No. 2004-107747 (FIG. 1 and paragraph 0026) SUMMARY OF THE INVENTION [0007] The present invention has been made under such a background, and it is, therefore, an object of the present invention to provide an electroless plating apparatus and method capable of stabilizing a status of an electroless plating solution and stably performing a plating processing on a surface of a substrate, since a reducing agent as an electron supply source is included in an electroless plating solution and a metal is precipitated in solution to thereby be in an unstable state, particularly when it is heated, in an electroless plating processing of, e.g., a semiconductor device fabrication processing. [0008] In accordance with one aspect of the present invention, there is provided an electroless plating apparatus, including: a substrate supporting unit for supporting a substrate at a substantially horizontal position; a first liquid chemical supply line for supplying a first liquid chemical therethrough; a first liquid chemical supply source communicating with an upstream end of the first liquid chemical supply line; a first liquid chemical opening/closing unit, installed in the vicinity of a downstream end of the first liquid chemical supply line, for controlling a flow of the first liquid chemical; a second liquid chemical supply line for supplying a second liquid chemical therethrough; a second liquid chemical supply source communicating with an upstream end of the second liquid chemical supply line; a second liquid chemical opening/closing unit, installed in the vicinity of a downstream end of the second liquid chemical supply line, for controlling a flow of the second liquid chemical; an electroless plating solution supply line, communicating with the downstream ends of the first and the second liquid chemical supply line, for supplying an electroless plating solution therethrough, which is formed by mixing the first and the second liquid chemical together, to supply it to a top surface of the substrate; a supply line temperature control unit for adjusting a temperature of a plating solution in the electroless plating solution supply line; a plating solution opening/closing unit, installed in the vicinity of a downstream end of the electroless plating solution supply line as a discharge opening thereof, for controlling a flow of the electroless plating solution; and a control unit for controlling the first liquid chemical opening/closing unit, the second liquid chemical opening/closing unit and the plating solution opening/closing unit to supply the electroless plating solution to the top surface of the substrate, wherein a volume in the electroless plating solution supply line surrounded by the first liquid chemical opening/closing unit, the second liquid chemical opening/closing unit and the plating solution opening/closing unit corresponds to a discharge amount required for performing an electroless plating processing on one substrate. Here, the first and the second liquid chemical opening/closing unit may be also used as one liquid chemical opening/closing unit. This electroless plating apparatus may have, e.g., flow rate adjusting units for adjusting flow rates of the first and the second liquid chemical, respectively. [0009] It is an object of the present invention to mix the first and the second liquid chemical right before the electroless plating processing if possible, and to reduce the amount of the liquid chemicals to be used as much as possible. Further, the present invention is based on an idea that both of the liquid chemicals are mixed together while a processing is carried out on one substrate until a processing on a subsequent substrate is started, and then, a mixed solution (an electroless plating solution) is used up in the processing on the subsequent substrate. Thus, the liquid chemical opening/closing units are provided in the vicinity of the junction between the first and the second liquid chemical supply line, i.e., they may be disposed as close as possible to the junction in a permissible range of a component layout. If a distance between the junction and the respective liquid chemical opening/closing units is large, both of the solutions are mixed together by diffusion to become a solution filling therebetween. However, since such a mixing operation is carried out at a stationary state after the liquid chemical opening/closing units are closed, both of the liquid chemicals may be supplied onto the substrate while they are not fully mixed, and thus, lowering uniformity in plating. In other words, "the vicinity of the junction" may include a range where non-uniformity in plating due to insufficient mixing does not occur, even though the respective liquid chemical opening/closing units are slightly away from the junction due to a configuration of component, a limitation on layout or the like. [0010] Further, the phrase "a volume V1 in the electroless plating solution supply line between the liquid chemical opening/closing units and the plating solution opening/closing unit corresponds to a discharge amount V2 required for performing the electroless plating processing on one wafer" used herein means that V1 and V2 become uniform. Further, V2 means a total amount obtained by summing an amount of solution to be deposited on a corresponding surface so as to electrolessly plate, e.g., a surface of a substrate and a volume (a volume of solution) from the plating solution opening/closing unit to the discharge opening. As to a relationship between V1 and V2, in case where V1 is greater than V2, if V2 is given as a discharge amount for one time, the plating solution remains in the plating solution supply line; and, if V1 is given as a discharge amount for one time, too much solution will be discharged, thereby wasting the liquid chemicals. Contrary to this, in case where V1 is smaller than V2, given that V2 is a discharge amount for one time, the first and the second liquid chemical in the liquid chemical supply lines, respectively, are discharged without remaining in the plating solution supply line, and thus, lowering uniformity in the plating solution on the substrate. For the same reason, it is an ideal that V1 and V2 are equal to each other, but a difference therebetween may be generated somewhat on design. In this case also, uniformity in plating processing is secured, and V1 and V2 become uniform if such a design idea is adopted that waste of liquid chemicals is prevented as much as possible. [0011] In a preferred embodiment of the present invention, there may be included an upper temperature controller facing the top surface of the substrate supported by the substrate supporting unit, and at the same time, being made to be larger than an effective area of the substrate, the upper temperature controller having in a bottom surface thereof a discharge opening of the electroless plating solution supply line; and a moving mechanism for relatively moving the upper temperature controller between a processing position for filling a space between the upper temperature controller and the top surface of the substrate with an electroless plating solution and a waiting position far away from the processing position. Here, the upper temperature controller may have therein a circulation chamber of a temperature control fluid, and the entire electroless plating solution supply line may be disposed in the circulation chamber of the upper temperature controller such that the supply line temperature control unit adjusts a temperature of an electroless plating solution by a heat exchange between the temperature control fluid and the electroless plating solution. Further, in the first and the second liquid chemical supply line, parts thereof filled with liquid chemicals that will subsequently fill the electroless plating solution supply line may be disposed in the circulation chamber of the upper temperature controller. In this case, since a part or an entire part of the electroless plating solution supply line can be disposed in the upper temperature controller, a part or an entire part of the supply line temperature control unit comes to be also used by the upper temperature controller. [0012] Further, it can be configured such that the upper temperature controller has therein a circulation chamber of a temperature control fluid; and the entire part of the electroless plating solution supply line is disposed in the circulation chamber to be also used as the supply line temperature control unit such that a heat exchange is made between the electroless plating solution and the temperature control fluid. [0013] Still further, in the present invention, the first and the second liquid chemical supply line may have temperature control units for controlling temperatures of parts thereof filled with liquid chemicals that will subsequently fill the electroless plating solution supply line. In case where an inside of the upper temperature controller is formed as the circulation chamber of the temperature control fluid, the circulation chamber may be used as a means for temperature controlling the parts filled with the liquid chemicals. [0014] Still further, the electroless plating apparatus of the present invention may include a lower temperature controller, disposed to face the bottom surface of the substrate, having a substrate temperature control unit for adjusting a temperature of the substrate. Here, it is preferable that the substrate temperature control unit adjusts a temperature of the substrate by filling a space between the lower temperature controller and the substrate with a fluid, a temperature of which is adjusted in the lower temperature controller. [0015] In accordance with another aspect of the present invention, there is provided an electroless plating method using the electroless plating apparatus of the present invention, wherein the first liquid chemical is a solution containing a metal salt of a plating metal, and the second liquid chemical is a solution containing a reducing agent as an electron supply source. [0016] In accordance with still another aspect of the present invention, there is provided an electroless plating method using the electroless plating apparatus of the present invention, wherein opening and closing operations of the first liquid chemical opening/closing unit, the second liquid chemical opening/closing unit and the plating solution opening/closing unit are simultaneously carried out. [0017] In accordance with still another aspect of the present invention, there is provided an electroless plating method using the electroless plating apparatus of the present invention, wherein the supply line temperature control unit and the upper temperature controller are adjusted at a plating process temperature. [0018] In accordance with still another aspect of the present invention, there is provided an electroless plating method using the electroless plating apparatus of the present invention, wherein the supply line temperature control unit and the temperature control units installed in the first and the second liquid chemical supply line are adjusted at a plating process temperature. [0019] In accordance with still another aspect of the present invention, there is provided an electroless plating method using the electroless plating apparatus of the present invention, wherein the supply line temperature control unit and the substrate temperature control unit are adjusted at a plating process temperature. BRIEF DESCRIPTION OF THE DRAWINGS [0020] The above and other objects and features of the present invention will become apparent from the following description of preferred embodiments given in conjunction with the accompanying drawings, in which: Continue reading about Electroless plating apparatus and method... Full patent description for Electroless plating apparatus and method Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Electroless plating apparatus and method patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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