JP2007126756A - Electroless plating apparatus and electroless plating method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electroless plating apparatus capable of reducing the initial cost and the running cost thereof, and efficiently forming a high-quality protective film on the surface of a metal region without needing a wide installation space. <P>SOLUTION: The electroless plating apparatus comprises: a pretreatment unit having a treatment unit; an electroless plating unit having a plating tank; and a postcleaning unit, and the pretreatment unit and the electroless plating unit have a common substrate holding head provided with an attraction head 234 and a substrate receiver 236 surrounding the attraction head. An attraction ring 250 with a recess 250a capable of evacuation extending along the circumferential direction is fitted to the attraction head. The substrate receiver has a seal ring 254a disposed on an inner circumferential end thereof and projecting inwardly, and the seal ring is pressed against the peripheral edge of the substrate by the attraction head to seal the peripheral edge of the substrate with the seal ring, so as to hold the substrate. Then, the recess of the attraction ring is evacuated, and, while sealing the peripheral edge of the substrate with the attraction ring, the substrate is attracted and held, so as to release the substrate from the substrate receiver. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electroless plating apparatus and an electroless plating method, and in particular, exposure of wiring constituted by embedding a conductor such as copper or silver in a fine concave portion for wiring provided on the surface of a substrate such as a semiconductor wafer. The present invention relates to an electroless plating apparatus and an electroless plating method used for forming a metal alloy film such as a magnetic film covering a wiring on the surface by electroless plating.

  As a wiring formation process of a semiconductor device, a process (so-called damascene process) in which a metal (conductor) is embedded in a wiring groove and a contact hole is being used. This is because, after embedding a metal such as copper or silver in a wiring groove or contact hole previously formed in an interlayer insulating film, the excess metal is removed by chemical mechanical polishing (CMP) and planarized. Process technology.

  Conventionally, this type of wiring, for example, copper wiring using copper as the wiring material, prevents thermal diffusion of wiring (copper) to the interlayer insulating film and improves electromigration resistance for improved reliability. Prevents the wiring (copper) from oxidizing in an oxidizing atmosphere when a barrier film is formed on the bottom and side surfaces of the wiring, and then a semiconductor device having a multilayer wiring structure is formed by laminating an insulating film (oxide film) For this reason, a method such as forming an antioxidant film is employed. Conventionally, a metal such as tantalum, titanium or tungsten or a nitride thereof is generally employed as this type of barrier film, and a nitride or carbide of silicon is generally employed as an antioxidant film.

  As an alternative to this, recently, a wiring protective film made of cobalt alloy, nickel alloy, etc., selectively covers the bottom and side surfaces of exposed wiring or exposed surfaces to prevent thermal diffusion, electromigration and oxidation of the wiring. To be considered. In the nonvolatile magnetic memory, when the memory cell density is increased and the design rule is reduced, the current density of the copper wiring is increased, resulting in an electromigration problem. Further, in this writing, in addition to an increase in the write current when the cell becomes small, the cell approaches and crosstalk becomes a problem. In order to solve this problem, it is considered that a yoke structure in which a magnetic film such as a cobalt alloy or a nickel alloy is provided around the copper wiring is effective. This magnetic film is obtained, for example, by electroless plating.

For example, as shown in FIG. 1, a fine recess 4 for wiring is formed inside an insulating film 2 made of SiO ₂ or the like deposited on the surface of a substrate W such as a semiconductor wafer, and a barrier layer made of TaN or the like on the surface. 6 is formed, and a copper seed film 7 is formed on the surface of the barrier layer 6 as necessary. Then, copper plating is performed, a copper film is formed on the surface of the substrate W, and copper is embedded in the recesses 4, and then the surface of the substrate W is flattened by CMP (chemical mechanical polishing). Thus, the wiring 8 made of a copper film is formed inside the insulating film 2. Next, on the surface of the wiring (copper film) 8, a wiring protective film (cover material) 9 made of, for example, electroless plating and made of a Co—WP alloy film is selectively formed to protect the wiring 8 To do.

A process of selectively forming such a wiring protective film (covering material) 9 made of a Co—WP alloy film on the surface of the wiring 8 by general electroless plating will be described. First, a substrate W such as a semiconductor wafer subjected to CMP treatment is immersed in, for example, room temperature dilute sulfuric acid or dilute hydrochloric acid for about 1 minute to remove impurities such as CMP residues such as metal oxide film and copper on the surface of the insulating film 2. To do. Then, after cleaning the surface of the substrate W with a cleaning solution such as pure water, the substrate W is immersed in, for example, a PdCl ₂ / HCl mixed solution at room temperature for about 1 minute, whereby Pd as a catalyst is formed on the surface of the wiring 8. The exposed surface of the wiring 8 is activated by adhering.

  Next, after cleaning (rinsing) the surface of the substrate W with pure water or the like, for example, the substrate W is immersed in a Co—WP plating solution having a liquid temperature of 80 ° C. for about 120 seconds to activate the wiring. The surface of 8 is subjected to selective electroless plating, and then the surface of the substrate W is cleaned with a cleaning liquid such as pure water. Thus, the wiring protection film 9 made of a Co—WP alloy film is selectively formed on the exposed surface of the wiring 8 to protect the wiring 8.

By the way, when forming a wiring protective film (covering material) made of a Co—WP alloy film by electroless plating, as described above, a catalyst applying treatment for applying a catalyst such as Pd to the surface of the wiring is performed. Before performing, for example, an oxide film on the wiring is removed, and in order to prevent an alloy film from being formed on the insulating film, a pre-cleaning of removing a CMP residue made of copper or the like remaining on the insulating film ( A (cleaning) process is generally performed. This pre-cleaning treatment is generally performed using a pre-cleaning solution made of an inorganic acid such as HF, H ₂ SO ₄ or HCl. However, such a pre-cleaning solution has an etching power for copper, and therefore, at the same time as the pre-cleaning, a part of the copper wiring is damaged (etched), and the damage causes an increase in wiring resistance. There is.

  In addition, when pre-cleaning, the copper constituting the wiring may be dissolved in a small amount, and if the dissolved copper moves on the insulating film between the wirings and adheres to the insulating film, there is a risk of leak current parsing. There is. Furthermore, after the pre-cleaning, when the insulating film is rinsed with pure water after being treated with the pre-cleaning chemical solution, if the insulating film is exposed to the chemical solution or the rinsing liquid for a long time, the insulating property of the insulating film is reduced and the leakage current is reduced. May rise. Further, if the chemical solution remains on the substrate surface after the chemical solution treatment, the in-plane uniformity of the film formation is also adversely affected, and it is necessary to remove it quickly.

  On the other hand, from the viewpoint of the apparatus, if each of the above steps is performed by a dedicated unit, not only the number of processing tanks in each step is increased, but there is a limit to shortening the substrate transfer time by the transfer robot. As a result, not only the apparatus footprint increases and the processing throughput decreases, but also the process control between each process becomes complicated. In particular, if the substrate is left in an oxygen atmosphere for a long time between catalyst application and rinsing, or between rinsing and plating, the surface state of the substrate is likely to change, which may adversely affect the electrical characteristics of the wiring on the treated substrate. is there.

  The present invention has been made in view of the above circumstances, can reduce the initial cost and running cost of the apparatus, and can efficiently form a high-quality alloy film on the surface of the metal part without requiring a large installation space. An object of the present invention is to provide an electroless plating apparatus and an electroless plating method.

  The invention according to claim 1 is an electroless plating apparatus for forming a wiring protective film on a metal part, which is a wiring formed on the surface of a substrate, by electroless plating, a pretreatment unit having a treatment tank, and plating A common substrate holding head having an electroless plating unit having a tank and a post-cleaning unit, the pretreatment unit and the electroless plating unit having a suction head and a substrate receiver surrounding the suction head The suction head is attached with a suction ring having a concave portion that can be evacuated and extends along the circumferential direction, and the substrate receiver protrudes inward and has a seal ring at the inner peripheral end. The sealing ring is pressed against the peripheral edge of the substrate by the suction head, the peripheral edge of the substrate is sealed with the seal ring to hold the substrate, and the concave portion of the suction ring is evacuated. , Is an electroless plating apparatus characterized by detaching the substrate is attracted and held substrate while sealing the peripheral portion of the substrate by the suction ring from the substrate receiving.

  As a result, the entire process becomes compact compared to the case where each processing step is performed in a separate unit (processing section), a large installation space is not required, the initial cost and the running cost of the apparatus can be reduced, and the processing is short. An alloy film can be formed in time. In particular, since the waiting time or transfer time of the substrate between the steps can be adjusted to be extremely short, a high quality alloy film can be formed without deteriorating electrical characteristics. In addition, an alloy film having a stable film quality can be formed by adjusting the interval from the completion of the rinsing process of the pretreatment liquid to the start of the plating process to be extremely short. In addition, the number of times the substrate is transferred by a transfer robot hand or the like can be reduced, and contamination and damage on the back surface of the substrate can be avoided. Further, for example, the front edge of the substrate is sealed and the plating pretreatment by the pretreatment unit is sealed, and the peripheral edge of the back surface of the substrate is sealed and the rinse treatment by the pretreatment unit and the plating treatment by the electroless plating unit are respectively performed. By carrying out, it can prevent that an abnormal plating film is produced | generated by the peripheral part of a board | substrate.

The invention according to claim 2 is the electroless plating apparatus according to claim 1, further comprising a nozzle for injecting a rinsing liquid for cleaning the seal ring.
The invention according to claim 3 is characterized in that the substrate holding head is attached to a free end of a swingable swingable arm and moves between the pretreatment unit and the electroless plating unit. The electroless plating apparatus according to claim 1.

In the pretreatment unit, the pretreatment unit cleans the surface of the substrate, and at the same time, applies a catalyst to the metal part to activate the surface of the metal part, and pretreatment for plating. 2. The electroless plating apparatus according to claim 1, wherein a rinsing process for rinsing the pretreatment liquid remaining on the surface of the subsequent substrate is performed.
Thereby, it is possible to remove the oxide film on the surface of the metal part or remove impurities such as a metal residue remaining on the interlayer insulating film at the same time as applying a catalyst to the surface of the metal part in the plating pretreatment. it can.

The invention according to claim 5 is characterized in that the pretreatment unit, the electroless plating unit, and the substrate holding head are arranged inside a housing capable of adjusting an internal atmosphere independently of the entire apparatus. The electroless plating apparatus according to claim 4.
As a result, the substrate during processing is exposed to an atmosphere in which the substrate being processed is easily oxidized, for example, by performing the operation while transporting the substrate after rinsing of the pretreatment liquid to the plating processing unit in an atmosphere having a lower oxygen composition than the atmosphere. Thus, an alloy film having a stable film quality can be obtained.

  The invention according to claim 6 is an electroless plating method in which a wiring protective film is formed by electroless plating on a metal part which is a wiring formed on the surface of the substrate, and the peripheral portion of the substrate surface is formed on the substrate holding head. Pre-plating treatment is performed by bringing a pre-treatment liquid into contact with the substrate surface in a state of being sealed with a seal ring, and rinsing and electroless plating treatment are performed while adsorbing and holding the substrate only on the back surface of the substrate by the substrate head. This is an electroless plating method.

  According to the present invention, a series of processes for selectively forming an alloy film by electroless plating is continuously performed on the surface of the metal part on the substrate surface, whereby each processing step is performed as a separate unit (processing unit). Compared with the case where it is carried out in (1), the whole is compact, does not require a large installation space, the initial cost and running cost of the apparatus can be reduced, and the alloy film can be formed in a short processing time. In particular, the waiting time or transfer time of the substrate between each process can be adjusted to be extremely short, or by performing a series of processes of surface cleaning, catalyst application, rinsing and plating in an atmosphere that is not easily oxidized, It is possible to prevent deterioration of performance and form a high quality alloy film.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 2 is a plan layout view of the electroless plating apparatus according to the embodiment of the present invention. As shown in FIG. 2, this electroless plating apparatus includes a substrate cassette containing a substrate W (see FIG. 1, the same applies hereinafter) in which wiring 8 made of copper or the like is formed in a wiring recess 4 formed on the surface. A load / unload unit 12 on which 10 is placed and accommodated is provided. Although only one cassette 10 is accommodated in the load / unload unit 12 shown in FIG. 2, a plurality of cassettes may be accommodated.

  A pretreatment unit 18 is located inside a rectangular housing 16 provided with an exhaust system, and performs pretreatment for plating the substrate W, for example, cleaning treatment and catalyst application treatment simultaneously using the same pretreatment liquid. , An electroless plating unit 20 that performs electroless plating on the surface (surface to be processed) of the substrate W, and a protective film (alloy film) 9 formed on the surface of the wiring 8 by the electroless plating (see FIG. 1, the same applies hereinafter) And a post-cleaning unit (post-processing unit) 24 for post-cleaning and drying the substrate W after the plating process. Further, the first transfer robot 26 is located between the load / unload unit 12 and the film thickness / film quality measurement unit 22, and the pretreatment unit 18, the electroless plating unit 20, the film thickness / film quality measurement unit 22, and the back. The second transfer robots 28 are respectively disposed at positions sandwiched by the cleaning unit 24.

  In this example, as the plating pretreatment, the substrate surface cleaning treatment and the metal catalyst catalyst application treatment are simultaneously performed using the same pretreatment liquid. This pre-plating treatment is a treatment in which a chemical solution is brought into contact with the surface of the substrate to modify the entire surface with the chemical solution, that is, in this example, the surface of the insulating film 2 and the surface of the wiring 8 which is a metal part are different. What is necessary is just to perform simultaneously with the same chemical | medical solution.

  A revolving shaft 30 that can be moved up and down and swiveled is erected on the side of the pretreatment unit 18 and the electroless plating unit 20, and a swing arm 32 is fixed to the upper end of the revolving shaft 30. A motor 34 is attached downward to the free end of the swing arm 32, and a substrate holding head 38 for detachably holding the substrate W is attached downward to the lower end of the output shaft 36 of the motor 34. ing. As a result, the swing arm 32 swings in the horizontal direction as the swing shaft 30 rotates, and the swing of the swing arm 32 causes the substrate holding head 38 to move to the position immediately above the pretreatment unit 18 and the electroless plating. Accordingly, the pretreatment unit 18 and the electroless plating unit 20 are configured to have a common substrate holding head 38. The substrate holding head 38 rotates as the motor 34 is driven.

  As shown in FIG. 6, the pretreatment unit 18 and the electroless plating unit 20, as well as the pivot shaft 30, the swing arm 32, and the substrate holding head 38 are provided with an air supply / exhaust system 40 and are hermetically sealed during the electroless plating process. It is arranged inside a housing 42 that can control the atmosphere uniquely.

  The pre-processing unit 18 performs pre-plating processing of the substrate W, that is, cleaning processing for cleaning the surface of the embedded wiring 8 and the surface of the insulating film 2 formed on the surface of the substrate W, and at the same time, the wiring 8 after the cleaning processing. This is for performing a rinsing process in which a catalyst is applied to the surface of the substrate to be activated and activated, and the pretreatment liquid (chemical solution) used for applying the catalyst is rinsed with a rinsing liquid. These processes are performed by a single pre-processing unit 18.

  This pretreatment unit 18 employs a two-liquid separation system that prevents mixing of different liquids, and has an inner diameter slightly larger than the outer diameter of the substrate holding head 38 as shown in FIGS. A treatment tank 100 (see FIG. 6) having an open inner tank 100a and an outer tank 100b is provided. A pair of leg portions 104 attached to the lid 102 is rotatably supported on the outer peripheral portion of the inner tank 100a. Further, a crank 106 is integrally connected to the leg 104, and a free end of the crank 106 is rotatably connected to a rod 110 of the lid moving cylinder 108.

  Accordingly, the lid 102 is configured to move between a processing position that covers the upper end opening of the inner tank 100a and a side retracted position in accordance with the operation of the lid moving cylinder 108. . On the surface (upper surface) of the lid 102, pure water or electrolytic ion water having a reducing power, or an aqueous solution prepared by mixing one component or a plurality of components constituting an electroless plating solution, as described below, A nozzle plate 112 having a large number of spray nozzles 112a for spraying the rinsing liquid outward (upward) is provided.

  As shown in FIG. 6, in the inner tank 100a, a plurality of spray nozzles 124a for injecting upward the pretreatment liquid supplied from the pretreatment liquid tank 120 as the pretreatment liquid supply pump 122 is driven. Are arranged in a state where the spray nozzles 124a are more evenly distributed over the entire cross section of the inner tank 100a. A drain pipe 126 for discharging the pretreatment liquid (drainage liquid) to the outside is connected to the inner tank 100a of the treatment tank 100. A three-way valve 128 is provided in the middle of the drain pipe 126, and this pretreatment liquid (drainage) is provided as necessary via a return pipe 130 connected to one outlet port of the three-way valve 128. Can be returned to the pretreatment liquid tank 120 for reuse.

  Here, the plating pretreatment liquid removes impurities including catalyst metal ions and metal residues remaining on the surface of the metal oxide film on the surface of the metal part or the surface of the metal part and other insulating films on the substrate. It is prepared by mixing acid having a cleaning function, and this pretreatment liquid is brought into contact with the surface of the substrate to apply a catalyst to the wiring surface, and at the same time, remove the oxide film of the wiring metal or interlayer insulating film The upper metal residue can be removed. Specifically, as a plating pretreatment liquid, at least one of palladium hydrochloride, palladium sulfate and palladium acetate and at least one of hydrochloric acid, sulfuric acid, hydrofluoric acid, acetic acid, oxalic acid, formic acid, citric acid and tartaric acid were mixed. An aqueous solution may be mentioned.

  Furthermore, in this example, the nozzle plate 112 provided on the surface (upper surface) of the lid body 102 is connected to the rinsing liquid supply source 132, and the rinsing process for the pretreatment liquid remaining on the substrate surface after the pretreatment for plating (see FIG. The cleaning process is performed using the rinse liquid, for example, pure water. A drain pipe 127 that discharges the rinse liquid (waste liquid) to the outside is connected to the outer tank 100b of the processing tank 100.

  In this example, pure water, for example, is used as the rinsing liquid for the pretreatment liquid, but electrolytic ionic water having reducing power or reducing water ionized by an arbitrary method is used. The pretreatment liquid remaining on the substrate may be rinsed (cleaned) efficiently while preventing the wiring from being oxidized. Further, the rinsing treatment of the pretreatment liquid may be performed by washing the surface of the substrate with an aqueous solution in which one component or a plurality of components constituting the electroless plating solution is mixed. This also oxidizes the wiring. This prevents the pretreatment liquid remaining on the substrate from being washed efficiently.

  Accordingly, the substrate holding head 38 holding the substrate W is lowered to position the substrate holding head 38 inside the inner tank 100a of the processing tank 100, and in this state, the nozzle plate 124 disposed inside the inner tank 100a. By spraying the pretreatment liquid from the spray nozzle 124a toward the substrate W, the pretreatment liquid is uniformly sprayed over the entire lower surface (treatment surface) of the substrate W, and the pretreatment liquid is scattered to the outside. The pretreatment liquid can be discharged from the drain pipe 126 to the outside while preventing the above.

  Further, the substrate holding head 38 is raised, and the upper end opening of the inner tank 100a of the processing tank 100 is closed by the lid 102, and the substrate holding head 38 is directed to the upper surface of the lid 102 toward the substrate W held by the substrate holding head 38. By spraying rinse water such as an aqueous solution prepared by mixing pure water, electrolytic ion water having a reducing power, or one component or a plurality of components constituting an electroless plating solution from the spray nozzle 112a of the nozzle plate 112 disposed. Then, the pretreatment liquid remaining on the substrate surface after applying the catalyst is rinsed (cleaning treatment). The rinse liquid (waste liquid) after processing is collected in the outer tank 100b of the processing tank 100 and discarded through the drain pipe 127. Thus, the rinse liquid such as electrolytic ionic water having the reducing power is prevented from flowing into the inner tank 100a, and the two liquids are not mixed.

  According to this pretreatment unit 18, as shown in FIG. 3, the substrate holding head 38 is raised and the substrate W is inserted and held therein, and then, as shown in FIG. The holding head 38 is lowered to be positioned in the inner tank 100a (see FIG. 6) of the processing tank 100. Then, while rotating the substrate holding head 38 and rotating the substrate W held by the substrate holding head 38, the pretreatment liquid is directed toward the substrate W from the spray nozzle 124 a of the nozzle plate 124 disposed inside the inner tank 100 a. By spraying, the pretreatment liquid is sprayed uniformly over the entire surface of the substrate W. Further, the substrate holding head 38 is raised and stopped at a predetermined position, and the lid 102 that has been in the retracted position is moved to a position that covers the upper end opening of the inner tank 100a of the processing tank 100 as shown in FIG.

  Then, in this state, pure water or electrolytic ion water having a reducing power from the spray nozzle 112a of the nozzle plate 112 disposed on the upper surface of the lid 102 toward the substrate W held and rotated by the substrate holding head 38, Alternatively, a rinse liquid such as a spray of an aqueous solution prepared by mixing one component or a plurality of components constituting the electroless plating solution is sprayed. Accordingly, the aqueous solution prepared by mixing the cleaning treatment and the catalyst application treatment of the substrate W with the pretreatment liquid, and pure water or electrolytic ionic water having a reducing power, or one component or a plurality of components constituting the electroless plating solution. The rinsing process using a rinsing liquid such as spraying can be performed while preventing the two liquids from mixing.

  Further, the pretreatment liquid tank 120 measures the concentration of impurities such as copper mixed in the pretreatment liquid by the plating pretreatment, and before removing the impurities when the concentration of the impurities reaches a predetermined value. A treatment liquid purification apparatus 140 is provided. Thereby, contamination of the pretreatment liquid used for the plating pretreatment can be suppressed, and the pretreatment liquid can always have stable catalytic power and cleaning power. In addition, it is preferable to maintain the temperature, composition, and concentration of each component within a predetermined range, so that a catalyst having a stable nuclear density is imparted to the wiring surface, the film quality is stable, and the film thickness is uniform. A simple alloy film can be formed.

  It should be noted that by adjusting the descending position of the substrate holding head 38 and adjusting the distance between the substrate W held by the substrate holding head 38 and the nozzle plate 124, the pretreatment sprayed from the spray nozzle 124 a of the nozzle plate 124. The region where the liquid hits the substrate W and the injection pressure can be arbitrarily adjusted.

  The above-described example corresponds to the case where one type of processing solution is used for the plating pretreatment. When multiple types, for example, two types of processing solutions are used for the plating pretreatment, it can be handled by providing three independent systems in the pretreatment unit so that three types of chemical solutions (including pure water) can be used. it can. That is, the three systems of the first system dedicated to the first plating pretreatment liquid, the second system dedicated to the second plating pretreatment liquid, and the third system dedicated to the rinse liquid are individually connected to the same unit.

  As shown in FIG. 6, the electroless plating unit 20 includes a plating tank 200 that stores therein a plating solution controlled to a predetermined temperature (for example, 80 ° C.). The plating tank 200 extends from the plating solution supply tank 202 at the bottom, and is connected to a plating solution supply pipe 208 having a plating solution supply pump 204 and a three-way valve 206 in the middle, and a plating solution recovery groove 210 in the peripheral wall portion. Is provided. Thus, during the plating process, the plating solution is supplied into the plating tank 200 from the bottom, and the overflowing plating solution is recovered from the plating solution recovery groove 210 to the plating solution supply tank 202, thereby providing the plating solution. Can be circulated.

  Near the bottom of the plating tank 200, the temperature of the plating solution introduced into the plating tank 200 is measured, and a temperature measuring device 214 for controlling the heater 216 and the flow meter 218 described below based on the measurement result. Is installed.

  Further, in this example, water heated by using a separate heater 216 and passed through the flow meter 218 is used as a heat medium, and the heat exchanger 220 is installed in the plating solution in the plating solution supply tank 202. Then, a heating device 222 for indirectly heating the plating solution and a stirring pump 224 for circulating and stirring the plating solution in the plating solution supply tank 202 are provided. This is because, in electroless plating, the plating solution may be used at a high temperature (about 80 ° C.), and this is to cope with this. According to this method, compared to the in-line heating method. Further, it is possible to prevent unnecessary substances from being mixed into the very delicate plating solution.

  In the electroless plating unit 20, the substrate W held by the substrate holding head 38 is lowered while being rotated while the plating solution in the plating tank 200 is circulated, and the substrate W is lowered. Immerse in the plating solution inside. At this time, the temperature of the plating solution, the composition of the plating solution, and the concentration of each component are maintained within a predetermined range by the plating solution management device 240 and the heating device 222 attached to the plating tank 200. Then, after the substrate W is immersed in the plating solution for a predetermined time, the substrate W is pulled up to a position above the plating tank 200, the rotation of the substrate holding head 38 is stopped, and the plating process is finished. In this way, by controlling the processing time, the film thickness of the alloy film formed on the substrate surface to be processed of the substrate is adjusted.

  As shown in detail in FIGS. 7 to 9, the substrate holding head 38 includes a suction head 234 and a substrate receiver 236 that surrounds the periphery of the suction head 234. The suction head 234 and the substrate receiver 236 rotate together as the motor 34 is driven via the spline structure, but relatively move up and down as the cylinder (not shown) operates. It is configured.

An adsorption ring 250 that adsorbs and holds the substrate W with the lower surface serving as a sealing surface is attached to the lower surface periphery of the adsorption head 234 via a pressing ring 251, and is provided continuously on the lower surface of the adsorption ring 250 in the circumferential direction. The concave portion 250 a and the vacuum line 252 extending through the suction head 234 communicate with each other through a communication hole 250 b provided in the suction ring 250. Thus, the substrate W is sucked and held by evacuating the concave portion 250a. Thus, by holding the substrate W by evacuating it with a small width (in the radial direction), The influence (deflection etc.) on the substrate W due to the vacuum can be minimized. The substrate W is released by supplying N ₂ and / or pure water to the vacuum line 252.

  On the other hand, the substrate receiver 236 is formed in a bottomed cylindrical shape that opens downward, a peripheral wall is provided with a substrate insertion window 236a for inserting the substrate W therein, and a disc protruding inward at the lower end. A substrate-shaped substrate guide portion 254 is provided, and a seal ring 254 a is provided at the inner peripheral end of the substrate guide portion 254 so as to protrude slightly upward. Further, a protrusion piece 256 having a taper surface 256 a serving as a guide for the substrate W on the inner peripheral surface is provided on the upper portion of the substrate guide portion 254.

  As a result, as shown in FIG. 7, the substrate W is inserted into the substrate receiver 236 from the substrate insertion window 236a with the substrate receiver 236 lowered. Then, the substrate W is guided by the tapered surface 256 a of the projection piece 256, positioned, and placed and held at a predetermined position on the upper surface of the substrate guide portion 254. In this state, the relative positions of the substrate receiver 236 and the suction head 234 are moved closer to each other, and the upper surface of the substrate W placed and held on the substrate guide portion 254 of the substrate receiver 236 is placed on the suction head 234 as shown in FIG. The seal ring 254a of the substrate guide portion 254 is brought into pressure contact with the lower surface of the peripheral edge portion of the substrate W by being brought into contact with the suction ring 250 and further approaching the relative position. As a result, the lower surface of the peripheral edge of the substrate W is sealed with the seal ring 254a to hold the substrate W.

  For example, when the pretreatment of the substrate W is performed, as described above, the concave portion 250a of the suction ring 250 is evacuated through the vacuum line 252, so that the peripheral portion of the upper surface of the substrate W is placed on the lower surface of the suction ring 250. The substrate W is sucked and held while sealing. In this state, the substrate is pretreated by spraying a pretreatment liquid toward the surface (lower surface) of the substrate W. Thereby, it is possible to prevent the catalyst from being applied to the peripheral portion of the substrate W. Further, at the time of rinsing and plating, as shown in FIG. 9, the relative position between the substrate receiver 236 and the suction head 234 is separated by, for example, several mm to several tens mm, and the substrate W is separated from the substrate guide portion 254. Separated, the suction ring 250 is held by suction only. Thereby, the peripheral part of the surface (lower surface) of the substrate W is purified by the rinse liquid. Furthermore, even when the peripheral portions of the front and back surfaces of the substrate are not sealed during the plating process, the catalyst does not adhere to the peripheral portions, so that the contamination of the peripheral portion of the substrate due to plating can be prevented.

  In this example, as shown in FIG. 10A, the seal ring 254a of the substrate guide portion 254 is pressed against the lower surface of the peripheral portion of the substrate W, and the lower surface of the peripheral portion of the substrate W is sealed with the seal ring 254a. Then, as described above, a pretreatment liquid is sprayed from the spray nozzle 124a of the nozzle plate 124 toward the substrate W onto the region (lower surface) sealed by the seal ring 254a, so that the substrate W is pretreated, that is, is cleaned. And a catalyst provision process is performed.

  Further, as shown in FIG. 10B, the substrate W is sucked and held while the peripheral portion of the upper surface of the substrate W is sealed with the lower surface of the suction ring 250, and the substrate W is separated from the substrate guide portion 254. Then, a rinsing liquid such as an aqueous solution prepared by mixing pure water, electrolytic ion water having a reducing power, or one or more components constituting the electroless plating solution from the spray nozzle 112a of the nozzle plate 112 is directed toward the substrate W. A rinsing process for rinsing the pretreatment liquid adhering to the substrate W is performed. At that time, the sealing ring 254a of the substrate guide portion 254 and the outer peripheral portion of the substrate surface are cleaned by spraying a rinsing liquid from a dedicated nozzle (not shown).

  Further, as shown in FIG. 10C, the substrate W is sucked and held while the peripheral portion of the upper surface of the substrate W is sealed by the lower surface of the suction ring 250, and the substrate W is separated from the substrate guide portion 254. Thus, the substrate surface is plated by immersing the substrate W in the plating solution in the plating tank 200.

It is preferable that the time from the completion of the plating pretreatment to the start of the rinsing treatment be within 5 seconds, whereby the continuous reaction by the residual liquid after the plating pretreatment and the oxidation of the activated metal surface are performed. Can be minimized.
Further, the interval from the completion of the rinsing process of the pretreatment liquid remaining on the substrate surface to the start of the electroless plating process is preferably within 15 seconds, whereby the surface of the metal part after the plating pretreatment is Reoxidation due to the influence of the external atmosphere can be minimized.

  Although not shown in FIG. 6, the plating tank 200 may have a double structure substantially similar to the pretreatment tank 100. Thus, by making the plating tank 200 have a double structure, immediately after the plating process, the substrate can be transferred from the inner tank to the outer tank, and the primary rinse cleaning can be performed immediately. In this example, an electroless plating unit 20 that does not have a rinsing function is used. Immediately after the plating process, the substrate is transferred from the plating tank 200 to the plating pretreatment unit 18, and the plating pretreatment unit 18. Primary rinse cleaning is performed in the outer tank 100b.

  The post-cleaning unit 24 removes the plating solution remaining on the surface of the substrate W plated by the electroless plating unit 20 or unnecessary precipitates on the insulating film by secondary cleaning, and simultaneously cleans the back surface of the substrate W. Further, the substrate W is rotated at a high speed and can be spin-dried.

  That is, the post-cleaning unit 24 includes a substrate stage that detachably holds the substrate W via a clamping mechanism and rotates the substrate W at a high speed, and pure water or both on both the front and back surfaces of the substrate held by the substrate stage. A cleaning liquid supply nozzle for supplying a cleaning liquid such as a chemical liquid is provided. Then, while rotating the substrate held by the substrate stage, by supplying a cleaning liquid such as pure water or chemicals to both the front and back surfaces of the substrate W, unnecessary deposition on the surface of the substrate W or the insulating film is prevented. The substrate W after the post-cleaning is spin-dried by removing the objects, simultaneously cleaning the back surface of the substrate, and further rotating the substrate W at a high speed through the substrate stage.

  Next, a series of electroless plating processes by the electroless plating apparatus will be described with further reference to FIG. In this example, as shown in FIG. 1, a case where an alloy film (wiring protective film) 9 made of a Co—WP alloy is selectively formed to protect the wiring 8 will be described.

  First, a substrate W (see FIG. 1, the same applies hereinafter) having wiring 8 formed on the surface thereof is stored in a substrate cassette 10 mounted on a load / unload unit 12 with the surface of the substrate W facing upward (face up). The single substrate W is taken out by the first transfer robot 26 and transferred to the film thickness / film quality measurement unit 22. Then, the substrate W placed on the film thickness / film quality measuring unit 22 is received by the second transfer robot 28, inverted by 180 °, and then transferred to the substrate holding head 38. That is, as described above, with the substrate receiver 236 lowered, the substrate W is inserted into the substrate receiver 236 from the substrate insertion window 236a, the substrate receiver 236 is raised, and the seal ring 254a of the substrate guide portion 254 is moved to the substrate. The substrate W is held in pressure contact with the lower surface of the peripheral edge of W.

Next, the swing arm 32 is swung to move the substrate holding head 38 to a position directly above the pretreatment unit 18. Next, in a state where the lid 102 is moved from the position covering the upper end opening of the inner tank 100a to the retracted position, the substrate holding head 38 is lowered and positioned inside the inner tank 100a of the processing tank 100 to hold the substrate. A pretreatment liquid is sprayed toward the substrate W from the spray nozzle 124a of the nozzle plate 124 disposed inside the inner tank 100a toward the substrate W held and rotated by the head 38, whereby the surface of the wiring 8 is Is pre-processed. As this pretreatment liquid, for example, at a liquid temperature of 25 ° C., a mixed liquid of 0.005 g / L PdCl ₂ and 0.2 ml / L HCl, or 0.04 g / L PdSO ₄ and 20 ml / L A mixed solution of H ₂ SO ₄ may be mentioned.

Thereby, the metal oxide film on the surface of the wiring 8 is removed, or the CMP residue remaining on the surfaces of the wiring 8 and the insulating film 2 is removed, and at the same time, Pd as a catalyst is attached to the surface of the wiring 8. That is, Pd nuclei as catalyst nuclei (seed) are formed on the surface of the wiring 8 to activate the exposed surface of the wiring 8. As described above, the pretreatment liquid purification device measures the concentration of impurities such as copper mixed in the pretreatment liquid by the catalyst application treatment and removes the impurities when the concentration of the impurities reaches a predetermined value. By providing 140, the used pretreatment liquid can be circulated and reused.
It is preferable to rotate the substrate W at the time of the pre-plating treatment, whereby the uniformity of the chemical reaction over the entire surface of the substrate can be improved.

Then, the substrate holding head 38 is once lifted, and if necessary, the substrate W is rotated at a high speed to shake off the pretreatment liquid, and then the peripheral portion of the upper surface of the substrate W is attached to the suction ring 250 as described above. The substrate W is sucked and held while sealing the lower surface, and the substrate W is separated from the substrate guide portion 254. Thereafter, the lid 102 is positioned so as to cover the upper end opening of the processing bath 100, and a rinsing liquid such as pure water or electrolytic ion water having reducing power is sprayed toward the substrate W from the spray nozzle 112 a of the nozzle plate 112. Then, a rinsing process for rinsing the pretreatment liquid adhering to the substrate is performed.
It is preferable to rotate the substrate W also at the time of the rinsing process, thereby improving the uniformity of cleaning with respect to the entire surface of the substrate.

  Next, the substrate holding head 38 is moved to a position directly above the electroless plating unit 20 while the substrate W is held by the substrate holding head 38 as described above. Then, an electroless plating process is performed on the surface of the substrate W in a state where the plating solution in the plating tank 200 is circulated. That is, for example, the substrate W is immersed in a Co—WP plating solution having a liquid temperature of 80 ° C. for about 120 seconds, for example, and the surface of the activated wiring 8 is selectively electroless plated (electroless Co). -W-P lid plating) is performed, and then the substrate holding head 38 is raised and primary rinsing after plating is performed. As a result, an alloy film (wiring protective film) 9 made of a Co—WP alloy is selectively formed on the surface of the wiring 8 to protect the wiring 8. Examples of the composition of the plating solution include the following.

Plating solution composition / CoSO ₄ · 7H ₂ O: 14 g / L
_{· Na 3 C 6 H 5 O} 7 · 2H 2 O: 70g / L
・ H ₃ BO ₃ : 40 g / L
・ Na ₂ WO ₄ · 2H ₂ O: 12 g / L
_{· NaH 2 PO 2 · H 2} O: 21g / L
-PH: 9.5 (adjusted with NaOH)
The capacity, temperature, and each composition component of the plating solution are maintained within a predetermined range by the plating solution management device 240.

  Here, the inside of the housing 42 is filled or circulated with an inert gas or a reducing gas to make the inside of the housing 42 an atmosphere having at least less oxygen component than the atmosphere. In this state, the substrate is pretreated and rinsed. It is preferable to perform plating treatment. As a result, an oxide film is prevented from being regenerated on the surface of the wiring 8 subjected to the catalyst application treatment, and a protective film is prevented from being oxidized during the film formation, thereby forming an alloy film having a stable film quality. can do.

  The substrate after the plating process is received from the substrate holding head 38 by the second transfer robot 28, inverted by 180 °, and then transferred to the post-cleaning unit 24. Thereafter, the cleaning unit 24 supplies the cleaning liquid such as pure water to both the front and back surfaces of the substrate W while holding and rotating the substrate W on the substrate stage to clean the front and back surfaces of the substrate W, and further through the substrate stage. By rotating the substrate W at a high speed, the substrate W after post-cleaning is spin-dried.

  Next, the substrate W after the spin drying is transported to the film thickness / film quality measuring unit 22 by the second transport robot 28, and is formed on the surface of the wiring 8 as needed by the film thickness / film quality measuring unit 22. At least one of the film thickness and film quality of the alloy film 9 is measured, and the substrate W after the film thickness or film quality measurement is returned to the substrate cassette 10 mounted on the load / unload unit 12 by the first transfer robot 26.

  Then, the measurement result obtained by measuring the film thickness or film quality of the protective film 9 formed on the exposed surface of the wiring 8 is fed back before the next substrate is subjected to the electroless plating process. Accordingly, for example, by adjusting the processing time of the plating process for the next substrate or the components of the plating solution, the film thickness and film quality of the alloy film formed on the substrate surface to be processed are controlled.

According to this example, an arbitrary liquid such as pure water can be used as a rinsing liquid for rinsing the pretreatment liquid remaining on the substrate after the pretreatment for plating.
In the above example, a Co—WP alloy film is used as the alloy film (wiring protective film) 9, but Co—P, Co—WB, Co—B, Ni— A wiring protective film made of WP, Ni-P, Ni-WB, Ni-B, or the like may be used. Moreover, although the example which uses copper as a wiring material is shown, you may use a copper alloy, silver, a silver alloy, gold | metal | money, a gold alloy, etc. other than copper.

  The plating pretreatment may be performed by immersing the substrate in a pretreatment liquid, similarly to the electroless plating treatment. Thereby, the substrate can be isolated from the external atmosphere during the substrate processing, and the surface of the activated metal part can be prevented from being reoxidized. In addition, the amount of dissolved oxygen in the plating pretreatment solution can be adjusted, and the reaction rate such as catalyst application in the pretreatment for plating can be controlled.

It is sectional drawing which shows the state which formed the wiring protective film by the electroless plating. 1 is a plan layout view of an electroless plating apparatus according to an embodiment of the present invention. It is a front view at the time of the board | substrate delivery of a pre-processing unit. It is a front view at the time of the catalyst provision process of a pre-processing unit. It is a front view at the time of the cleaning process of a pre-processing unit, and the rinse process of a catalyst chemical | medical solution. It is a systematic diagram of a pretreatment unit and an electroless plating unit. It is a principal part expanded sectional view at the time of board | substrate delivery of a board | substrate holding head. FIG. 5 is an enlarged cross-sectional view of a main part in a state where the substrate holder of the substrate holding head is lifted and the seal ring of the substrate guide portion is pressed against the lower surface of the peripheral edge of the substrate to hold the substrate. FIG. 4 is an enlarged cross-sectional view of a main part in a state where the substrate is sucked and held while the peripheral edge of the upper surface of the substrate of the substrate holding head is sealed with the lower surface of the suction ring, and further the substrate is separated from the substrate guide portion. (A) shows a state in which pretreatment (cleaning treatment and catalyst application treatment) of the substrate is performed, (b) shows a state in which rinsing treatment for rinsing the chemical solution adhering to the substrate is carried out, (c) These are the schematic diagrams which respectively show the state which is performing the plating process to the board | substrate surface. It is a process flow figure in the electroless-plating apparatus shown in FIG.

Explanation of symbols

8 Wiring 9 Protective film 10 Substrate cassette 12 Load / unload unit 18 Pretreatment unit 20 Electroless plating unit 22 Film thickness / film quality measurement unit 24 Post-cleaning unit 30 Rotating shaft 32 Swing arm 38 Substrate holding head 40 Housing 100 Processing tank 102 Lid body 104 Leg part 106 Crank 108 Lid moving cylinders 112, 124 Nozzle plates 112a, 124a Spray nozzle 120 Pretreatment liquid tank 126 Drain pipe 132 Rinse liquid supply source 140 Pretreatment liquid purification device 200 Plating tank 202 Plating liquid supply Tank 210 Plating solution recovery groove 216 Heater 218 Flow meter 220 Heat exchanger 222 Heating device 224 Stirring pump 234 Suction head 236 Substrate receiver 240 Plating solution management device 250 Suction ring 252 Vacuum line 254 Substrate guide portion 254a Seal phosphorus

Claims (6)

An electroless plating apparatus for forming a wiring protection film on a metal part, which is a wiring formed on the surface of a substrate, by electroless plating,
A pretreatment unit having a treatment tank;
An electroless plating unit having a plating tank;
A post-cleaning unit,
The pretreatment unit and the electroless plating unit have a common substrate holding head including a suction head and a substrate receiver surrounding the suction head,
A suction ring having a concave portion that can be evacuated and extends along the circumferential direction is attached to the suction head,
The substrate receiver protrudes inward and has a seal ring at the inner peripheral end,
The sealing ring is pressed against the peripheral edge of the substrate by the suction head, the peripheral edge of the substrate is sealed with the seal ring, and the substrate is held.
An electroless plating apparatus, wherein the concave portion of the suction ring is evacuated, the substrate is sucked and held while the peripheral portion of the substrate is sealed with the suction ring, and the substrate is pulled away from the substrate receiver.   2. The electroless plating apparatus according to claim 1, further comprising a nozzle for injecting a rinsing liquid for cleaning the seal ring.   2. The electroless plating according to claim 1, wherein the substrate holding head is attached to a free end of a swingable swinging arm and moves between the pretreatment unit and the electroless plating unit. apparatus.   The pretreatment unit cleans the surface of the substrate, and simultaneously applies a catalyst to the metal part to activate the surface of the metal part, and before remaining on the surface of the substrate after the plating pretreatment. The electroless plating apparatus according to claim 1, wherein a rinsing process for rinsing the processing liquid is performed.   5. The electroless plating apparatus according to claim 4, wherein the pretreatment unit, the electroless plating unit, and the substrate holding head are arranged inside a housing that can adjust an internal atmosphere independently of the entire apparatus. . An electroless plating method for forming a wiring protective film on a metal part, which is a wiring formed on the surface of a substrate, by electroless plating,
In the state where the peripheral edge of the substrate surface is sealed with the seal ring of the substrate holding head, the pretreatment liquid is brought into contact with the substrate surface to perform the pretreatment for plating.
An electroless plating method comprising rinsing and electroless plating treatment while adsorbing and holding a substrate only on the back surface of the substrate by the substrate head.