JP2008038215A - Substrate-treating method and substrate-treating apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently form a high-quality protection film for wiring on the surface of wires without deteriorating electrical characteristics of the wires. <P>SOLUTION: This treatment method comprises the steps of: preparing a substrate that has embedded wiring formed in an insulation film so as to expose its surface outward and has been dried; pretreating the surface of the substrate with a chemical solution prior to a plating step; and selectively forming an electroless-plated protective film on the exposed surface of the wires immediately after the pretreatment. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a substrate processing method and a substrate processing apparatus, and in particular, an exposed surface of an embedded wiring formed 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. In particular, the present invention relates to a substrate processing method and a substrate processing apparatus used for forming a wiring protective film covering the wiring 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, it has recently been studied to selectively cover the exposed surface of the embedded wiring with a wiring protective film made of a cobalt alloy, nickel alloy or the like to prevent thermal diffusion, electromigration and oxidation of the wiring. ing. This wiring protective 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 Low-K material deposited on the surface of a substrate W such as a semiconductor wafer, and TaN is formed on the surface. A barrier layer 6 made of, for example, is formed, and a seed layer 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 copper is formed inside the insulating film 2. Next, a wiring protective film (cover material) 9 made of a CoWP alloy, for example, obtained by electroless plating is selectively formed on the surface of the wiring (copper) 8 to protect the wiring 8.

A process of selectively forming such a wiring protective film (covering material) 9 made of a CoWP 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 CoWP plating solution having a liquid temperature of 80 ° C. for about 120 seconds to activate the surface of the activated wiring 8. Selective electroless plating is performed, 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 CoWP alloy film is selectively formed on the exposed surface of the wiring 8 to protect the wiring 8.

  If the time until the start of electroless plating is long after the pretreatment of plating, the formation of metal oxide proceeds on the surface of the wiring metal, which becomes an inhibitory factor in the start of plating, and this causes uneven plating.

  Further, the wiring protective film made of cobalt alloy or nickel alloy formed by electroless plating is slightly dissolved in a processing solution such as a cleaning solution. In particular, when a CoWBP alloy that can be electrolessly plated without applying a catalyst is used as a wiring protective film, this phenomenon appears remarkably. Even if a trace amount of the wiring protective film is dissolved in the processing solution, and the dissolved wiring protective film moves on the insulating film between the wirings, particularly in the case of thin pit wiring, there is a leakage current between the wirings. Cause.

  The present invention has been made in view of the above circumstances, and provides a substrate processing method and a substrate processing apparatus capable of efficiently forming a high-quality wiring protective film on the surface of a wiring without deteriorating electrical characteristics. For the purpose.

According to the first aspect of the present invention, a substrate is prepared by forming an embedded wiring with the surface exposed inside the insulating film and dried, and a pretreatment for plating with a chemical solution is performed on the surface of the substrate. The substrate processing method is characterized in that an electroless plating is immediately performed to selectively form a wiring protective film on the exposed surface of the wiring.
In this way, immediately after the completion of the pre-plating process, the electroless plating is performed immediately to selectively form the wiring protective film on the exposed surface of the wiring. Can be prevented as much as possible, and a wiring protective film by electroless plating can be more uniformly formed on the surface of the wiring.
The invention according to claim 2 is the substrate processing method according to claim 1, wherein the time from the end of the pre-plating process to the start of electroless plating is within 10 seconds.

According to a third aspect of the present invention, there is provided a substrate obtained by forming a buried wiring having a surface exposed inside an insulating film and drying the substrate, and performing a plating pretreatment with a chemical solution on the surface of the substrate. The substrate processing method is characterized in that electroless plating is performed on the surface of the wiring to selectively form a wiring protective film on the exposed surface of the wiring, and the substrate is dried immediately after the electroless plating is completed.
In this way, after the electroless plating is finished, the wiring protective film made of, for example, a cobalt alloy or a nickel alloy is dissolved in a processing solution such as a cleaning solution by immediately drying the substrate without cleaning it with a chemical solution (cleaning solution). Can be reduced as much as possible, and the risk of leakage current between the wirings can be reduced.
The invention according to claim 4 is the substrate processing method according to claim 3, wherein the time from the end of electroless plating to the start of drying of the substrate is within 10 seconds.

  According to the fifth aspect of the present invention, the drying of the substrate is performed by supplying a highly volatile liquid and pure water to the rotating substrate to remove liquid components from the substrate, and a cyclic organic containing N atoms in the rotating substrate. 5. The substrate processing method according to claim 3, wherein the substrate processing method is carried out by at least one of methods of supplying pure water to which a compound is added and removing the liquid component from the substrate.

  In this way, by supplying highly volatile liquid and pure water to the rotating substrate, removing the liquid components from the substrate and drying the substrate, the plating solution remaining on the surface of the substrate is removed, and the drying time itself Can be further shortened. Examples of the highly volatile liquid include IPA (isopropyl alcohol) and ethanol. In addition, by supplying pure water to which a cyclic organic compound containing N atoms is added to a rotating substrate and removing the liquid component from the substrate and drying the substrate, the wiring solution is removed while removing the plating solution remaining on the surface of the substrate. The surface of the protective film can be prevented from corrosion. Examples of the cyclic organic compound containing an N atom include anticorrosive agents such as BTA (benzotriazole), quinaldine, and glycine.

According to the sixth aspect of the present invention, the substrate dried after electroless plating is subjected to a modification treatment to modify the wiring protective film or its surface, and then the substrate is subjected to a post-plating treatment to dry the substrate again. 6. The substrate processing method according to claim 3, wherein the substrate processing method is performed.
Thereby, it can suppress that a wiring protective film melt | dissolves in a washing | cleaning liquid during the post-plating process (washing | cleaning) which used cleaning liquid (chemical | medical solution) or ultrapure water, for example.

The invention according to claim 7 is the substrate processing method according to claim 6, wherein the modification process is an annealing process or a plasma process.
For example, by performing plasma treatment using a mixed gas of H ₂ and N ₂ to form a metal nitride on the surface of the wiring protective film, for example, during post-plating treatment (cleaning) using a cleaning solution (chemical solution) In addition, it is possible to prevent the wiring protective film from being dissolved in the cleaning liquid.

  According to an eighth aspect of the present invention, there is provided a pre-processing unit for performing pre-plating treatment with a chemical solution on a surface of a substrate that has been formed by drying an embedded wiring having a surface exposed inside an insulating film, and the surface of the substrate for pre-plating treatment The substrate processing apparatus further comprises an electroless plating unit that performs electroless plating to selectively form a wiring protective film on the exposed surface of the wiring, and then dries the substrate.

The invention according to claim 9 is the substrate processing apparatus according to claim 8, wherein the pretreatment unit and the electroless plating unit are arranged inside a housing whose internal atmosphere can be controlled. .
Thereby, by adjusting the oxygen concentration in the housing, dissolution of the wiring protective film in the liquid during a series of processes for forming the wiring protective film can be further suppressed.

  The invention described in claim 10 further includes a modification unit for modifying the wiring protective film or the surface thereof, and a post-treatment unit for performing a post-plating treatment on the wiring protective film or the substrate having the modified surface. A substrate processing apparatus according to claim 8 or 9.

  According to the present invention, the surface of the wiring formed by exposing the surface inside the insulating film is reliably covered with the wiring protective film having a more uniform thickness while reducing the risk of leakage current between the wirings. Wiring can be protected.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following example, by using a plating solution containing DMAB (dimethylamine borane) as a reducing agent on the exposed surface of the wiring 8 shown in FIG. 1, without applying a catalyst to the exposed surface of the wiring 8, An example in which the wiring 8 is selectively covered with a wiring protective film (covering material) 9 made of a CoWBP alloy that can be formed by electroless plating so that the wiring 8 is protected by the wiring protective film 9 is shown.

  FIG. 2 is a plan layout view of the wiring forming apparatus according to the embodiment of the present invention. As shown in FIG. 2, the wiring forming apparatus includes a rectangular apparatus frame 20 and a load / unload unit 22 attached to the apparatus frame 20. A control unit 24 is provided on the outer wall of the apparatus frame 20. Is installed. Inside the apparatus frame 20, a sealable casing 26 having an exhaust system and a function capable of adjusting the internal atmosphere independently of the entire apparatus is stored, and plating pretreatment with a chemical solution of the substrate is provided at four corners of the casing 26. A first pretreatment unit 28 and a second pretreatment unit 30 for performing electroless plating on the surface of the substrate and drying the substrate after completion of the electroless plating, and post-plating treatment (post-cleaning) A post-processing unit 34 to perform is arranged.

  In this example, an example in which the first pretreatment unit 28 and the second pretreatment unit 30 perform two-stage plating pretreatment that does not include the catalyst application treatment is shown. As shown, when the wiring is covered and protected with a wiring protective film made of a CoWP alloy, one of the pretreatment units 30 can be used as a catalyst application unit. Alternatively, one pretreatment unit 30 may be omitted and the plating pretreatment may be performed in one stage.

  Inside the apparatus frame 20, a reforming unit 36 that is located outside the housing 26 and that modifies the substrate on which the wiring protective film is formed to modify the wiring protective film or its surface, and post-plating processing A drying unit 38 for rinsing and drying the subsequent substrate is disposed. Further, the first substrate transfer robot 40 is located between the reforming unit 36 and the drying unit 38, and the first pretreatment unit 28, the second pretreatment unit 30, the electroless plating unit 32, and the rear part inside the housing 26. A second substrate transfer robot 42 is disposed at a position surrounded by the processing unit 34.

  Next, details of each unit provided in the substrate processing apparatus shown in FIG. 2 will be described below. The first pretreatment unit 28 and the second pretreatment unit 30 have the same configuration except that different treatment liquids are used. The first pretreatment unit 28 and the second pretreatment unit 30 adopt a two-liquid separation system that prevents mixing of different liquids, and are transported in a face-down manner. The peripheral edge of the lower surface which is the surface (surface to be processed) is sealed, and the back surface is pressed to fix the substrate W. Hereinafter, the first pretreatment unit 28 will be described.

  As shown in FIGS. 3 to 5, the first pretreatment unit 28 (second pretreatment unit 30) moves up and down relatively with respect to the fixed frame 52 attached to the upper part of the frame 50. As shown in FIG. 6, a processing head 60 having a bottomed cylindrical housing portion 56 opened downward and a substrate holder 58 is suspended and supported on the moving frame 54. . In other words, the head rotating servo motor 62 is attached to the moving frame 54, and the housing portion 56 of the processing head 60 is connected to the lower end of the output shaft (hollow shaft) 64 that extends below the servo motor 62.

  As shown in FIG. 6, a vertical shaft 68 that rotates integrally with the output shaft 64 is inserted into the output shaft 64 via a spline 66, and a ball joint 70 is attached to the lower end of the vertical shaft 68. The substrate holder 58 of the processing head 60 is connected through the via. The substrate holder 58 is located inside the housing portion 56. The upper end of the vertical shaft 68 is connected to a fixed ring elevating cylinder 74 fixed to the moving frame 54 via a bearing 72 and a bracket. As a result, the vertical shaft 68 moves up and down independently of the output shaft 64 in accordance with the operation of the lifting cylinder 74.

  As shown in FIGS. 3 to 5, the fixed frame 52 is attached with a linear guide 76 that extends in the vertical direction and serves as a guide for raising and lowering the moving frame 54, and the head raising and lowering cylinder (not shown) is operated. Thus, the moving frame 54 moves up and down using the linear guide 76 as a guide.

  As shown in FIG. 6, the peripheral wall of the housing part 56 of the processing head 60 is provided with a substrate insertion window 56a for inserting the substrate W therein. Further, as shown in FIGS. 7 and 8, a peripheral portion is sandwiched between a main frame 80 made of, for example, polyether ether ketone and a guide frame 82, below the housing portion 56 of the processing head 60. 84 is arranged. The seal ring 84 abuts on the peripheral edge of the lower surface of the substrate W and seals it.

  A substrate fixing ring 86 is fixed to the periphery of the lower surface of the substrate holder 58, and a cylindrical pusher 90 is attached to the substrate fixing ring through the elastic force of a spring 88 disposed inside the substrate fixing ring 86 of the substrate holder 58. Projects downward from the lower surface of 86. Further, a bendable cylindrical bellows plate 92 made of, for example, Teflon (registered trademark) is hermetically sealed between the upper surface of the substrate holder 58 and the upper wall portion of the housing portion 56. Yes. Further, the substrate holder 58 is provided with a covering plate 94 that covers the upper surface of the substrate held by the substrate holder 58.

  Accordingly, the substrate W is inserted into the housing portion 56 from the substrate insertion window 56a with the substrate holder 58 raised. Then, the substrate W is guided by a tapered surface 82 a provided on the inner peripheral surface of the guide frame 82, positioned, and placed at a predetermined position on the upper surface of the seal ring 84. In this state, the substrate holder 58 is lowered, and the pusher 90 of the substrate fixing ring 86 is brought into contact with the upper surface of the substrate W. Then, by further lowering the substrate holder 58, the substrate W is pressed downward by the elastic force of the spring 88, and is thereby brought into pressure contact with the peripheral portion of the surface (lower surface) of the substrate W by the seal ring 84, While sealing, the substrate W is sandwiched and held between the housing portion 56 and the substrate holder 58.

  In this way, when the head rotating servomotor 62 is driven while the substrate W is held by the substrate holder 58, the output shaft 64 and the vertical shaft 68 inserted into the output shaft 64 are connected via the spline 66. The housing portion 56 and the substrate holder 58 are also rotated integrally.

  A processing tank 100 (see FIG. 9) having an outer tank 100a and an inner tank 100b, which is located below the processing head 60 and opens upward having an inner diameter slightly larger than the outer diameter of the processing head 60, is provided. Yes. A pair of leg portions 104 attached to the lid 102 is rotatably supported on the outer peripheral portion of the inner tank 100b. Further, as shown in FIGS. 3 to 5, 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 a lid moving cylinder 108. Yes. Accordingly, the lid body 102 is configured to move between a processing position covering the upper end opening of the inner tank 100b and a side retracted position in accordance with the operation of the lid body moving cylinder 108. . The surface (upper surface) of the lid 102 is provided with a nozzle plate 112 having a large number of injection nozzles 112a for injecting pure water outward (upward), for example.

  Further, as shown in FIG. 9, the first processing liquid supplied from the first processing liquid tank 120 as the first processing liquid pump 122 is driven is directed upward in the inner tank 100 b of the processing tank 100. The nozzle plate 124 having a plurality of spray nozzles 124a for spraying is disposed in a state where the spray nozzles 124a are more evenly distributed over the entire cross section of the inner tank 100b. A drain pipe 126 for discharging the first processing liquid (drainage) to the outside is connected to the bottom surface of the inner tank 100b. A three-way valve 128 is provided in the middle of the drain pipe 126, and the first treatment liquid (drainage liquid) 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 first treatment liquid tank 120 for reuse.

  The nozzle plate 112 provided on the surface (upper surface) of the lid 102 is connected to the second processing liquid supply source 132. Thereby, the second processing liquid is sprayed from the spray nozzle 112a toward the surface of the substrate. A drain pipe 127 is also connected to the bottom surface of the outer tub 100a.

  As a result, the processing head 60 holding the substrate is lowered, and the upper end opening of the inner tank 100b of the processing tank 100 is covered with the processing head 60, and in this state, the inside of the inner tank 100b of the processing tank 100 is covered. By spraying the first processing liquid from the spray nozzle 124a of the arranged nozzle plate 124 toward the substrate W, the first processing liquid is sprayed uniformly over the entire lower surface (processing surface) of the substrate W, and The first processing liquid is discharged from the drain pipe 126 to the outside while preventing the first processing liquid from scattering to the outside.

  Further, the processing head 60 is raised, and the upper end opening of the inner tank 100b of the processing tank 100 is closed with the lid 102, and is disposed on the upper surface of the lid 102 toward the substrate W held by the processing head 60. By spraying the second processing liquid from the spray nozzle 112a of the nozzle plate 112, the second processing liquid is sprayed uniformly over the entire lower surface (processing surface) of the substrate W. Since the second treatment liquid passes between the outer tank 100a and the inner tank 100b and is discharged through the drain pipe 127, the second treatment liquid is prevented from flowing into the inner tank 100b and becomes the first treatment liquid. Mixing is prevented.

  According to the first pretreatment unit 28 (second pretreatment unit 30), as shown in FIG. 3, with the processing head 60 raised, the substrate W is inserted and held therein, and thereafter As shown in FIG. 4, the processing head 60 is lowered and is positioned to cover the upper end opening of the inner tank 100 b of the processing tank 100. Then, while the processing head 60 is rotated and the substrate W held by the processing head 60 is rotated, the first processing is performed from the injection nozzle 124a of the nozzle plate 124 disposed inside the inner tank 100b as shown in FIG. By spraying the liquid toward the substrate W, the first processing liquid is sprayed uniformly over the entire surface of the substrate W. Then, the processing head 60 is raised and stopped at a predetermined position, and the lid body 102 that is in the retracted position is moved to a position that covers the upper end opening of the inner tank 100b of the processing tank 100 as shown in FIG. In this state, the second processing liquid is ejected from the ejection nozzle 112 a of the nozzle plate 112 disposed on the upper surface of the lid 102 toward the substrate W held and rotated by the processing head 60. Thereby, the process by the 1st process liquid and the 2nd process liquid of the board | substrate W can be performed, keeping two liquids not mixing.

  The electroless plating unit 32 is shown in FIGS. The electroless plating unit 32 includes a plating tank 200 (see FIGS. 14 and 16), a substrate head 204 disposed above the plating tank 200 to detachably hold the substrate W, and a side of the plating tank 200. Has a drying tank 202 (see FIG. 15).

  As shown in detail in FIG. 10, the substrate head 204 includes a housing portion 230 and a head portion 232, and the head portion 232 mainly includes a suction head 234 and a substrate receiver 236 that surrounds the suction head 234. It is configured. The housing portion 230 houses a substrate rotation motor 238 and a substrate receiving drive cylinder 240. The upper end of the output shaft (hollow shaft) 242 of the substrate rotation motor 238 is at the rotary joint 244, and the lower end is at the lower end. The rods of the substrate receiving drive cylinder 240 are connected to the suction head 234 of the head unit 232, respectively, and are connected to the substrate receiver 236 of the head unit 232. A stopper 246 that mechanically restricts the rise of the substrate receiver 236 is provided inside the housing portion 230.

  Here, a spline structure is adopted between the suction head 234 and the substrate receiver 236, and the substrate receiver 236 moves up and down relative to the suction head 234 in accordance with the operation of the substrate receiver driving cylinder 240. When the output shaft 242 is rotated by driving the rotation motor 238, the suction head 234 and the substrate receiver 236 are configured to rotate integrally with the rotation of the output shaft 242.

As shown in detail in FIG. 11 to FIG. 13, a suction ring 250 that sucks and holds the substrate W with the lower surface as a sealing surface is attached to the suction head 234 via a pressing ring 251. A concave portion 250 a provided continuously in the circumferential direction on the lower surface of the nozzle and a vacuum line 252 extending in the suction head 234 communicate with each other through a communication hole 250 b provided in the suction ring 250. Thereby, the substrate W is sucked and held by evacuating the concave portion 250a. Thus, by holding the substrate W by vacuuming in a circumferential manner with a small width (radial direction), By minimizing the influence (deflection, etc.) on the substrate W due to the vacuum and immersing the adsorption ring 250 in the electroless plating solution, not only the surface (lower surface) but also the edge of the substrate W are all electroless. It becomes possible to immerse in the plating solution. The substrate W is released by supplying N ₂ 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 claw portion 254 is provided. Further, a projection 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 claw portion 254.

  Thus, as shown in FIG. 11, 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 protrusion piece 256, positioned, and placed and held at a predetermined position on the upper surface of the claw portion 254. In this state, the substrate receiver 236 is raised, and the upper surface of the substrate W placed and held on the claw portion 254 of the substrate receiver 236 is brought into contact with the suction ring 250 of the suction head 234 as shown in FIG. Next, the concave portion 250 a of the suction ring 250 is evacuated through the vacuum line 252, and the substrate W is sucked and held while the peripheral portion of the upper surface of the substrate W is sealed to the lower surface of the suction ring 250. When performing the electroless plating process, as shown in FIG. 13, the substrate receiver 236 is lowered by several mm, the substrate W is separated from the claw portion 254, and the suction ring 250 alone is held by suction. Thereby, it can prevent that the peripheral part of the surface (lower surface) of the board | substrate W stops being plated by presence of the nail | claw part 254. FIG.

  FIG. 14 shows the details of the plating tank 200. The plating tank 200 is connected to a plating solution supply pipe 308 (see FIG. 16) at the bottom, and is provided with a plating solution recovery groove 260 in the peripheral wall portion. Two rectifying plates 262 and 264 that stabilize the flow of the electroless plating solution flowing upward are disposed inside the plating tank 200, and are further introduced into the plating tank 200 at the bottom. A temperature measuring device 266 that measures the temperature of the electroless plating solution is installed. Moreover, the pH is 6 in the inside of the plating tank 200 located slightly above the liquid surface of the electroless plating solution held in the plating tank 200 on the outer peripheral surface of the peripheral wall of the plating tank 200 and slightly obliquely upward in the diameter direction. An injection nozzle 268 for injecting a stop liquid composed of a neutral liquid of -7.5, for example, pure water, is installed. Thus, after the electroless plating is finished, the substrate W held by the head portion 232 is pulled up slightly above the liquid surface of the electroless plating solution and stopped temporarily. In this state, pure water is supplied from the spray nozzle 268 toward the substrate W. (Stopping liquid) is sprayed to immediately cool the substrate W, thereby preventing the electroless plating from proceeding with the electroless plating solution remaining on the substrate W.

  Further, the upper end opening of the plating tank 200 is closed when the plating process is not performed at the time of idling or the like, so that the upper end opening of the plating tank 200 is closed and wasteful evaporation and heat dissipation of the plating solution in the plating tank 200 is performed. A plating tank cover 270 to be prevented is installed so as to be openable and closable.

  As shown in FIG. 16, the plating tank 200 extends from the plating solution storage tank 302 at the bottom, and is connected to a plating solution supply pipe 308 provided with a plating solution supply pump 304, a filter 305, and a three-way valve 306 in the middle. Yes. Further, the plating solution recovery groove 260 of the plating tank 200 is connected to a plating solution recovery pipe extending from the plating solution storage tank 302. Thus, during the plating process, the electroless plating solution is supplied into the plating tank 200 from the bottom, and the electroless plating solution overflowing the plating tank 200 is transferred from the plating solution recovery groove 260 to the plating solution storage tank 302. By collecting, the electroless plating solution can be circulated. A plating solution return pipe 312 that returns to the plating solution storage tank 302 is connected to one outlet port of the three-way valve 306. Thus, the electroless plating solution can be circulated even when waiting for plating.

  In particular, in this example, by controlling the plating solution supply pump 304, the flow rate of the electroless plating solution that circulates during the plating standby and the plating process can be individually set. That is, the circulation flow rate of the electroless plating solution during plating standby is, for example, 2 to 20 L / min, and the circulation flow rate of the electroless plating solution during plating is set, for example, to 0 to 10 L / min. This ensures a large circulation flow rate of the electroless plating solution during plating standby, keeps the temperature of the plating bath in the cell constant, and reduces the circulation flow rate of the electroless plating solution during the plating process. A wiring protective film (plating film) having a uniform thickness can be formed.

  In the vicinity of the bottom of the plating tank 200, the temperature of the electroless plating solution introduced into the plating tank 200 is measured, and the temperature measurement for controlling the heater 316 and the flow meter 318 described below based on the measurement result. A vessel 266 is provided.

  In this example, the temperature is raised using a separate heater 316, the water passed through the flow meter 318 is used as a heat medium, and the heat exchanger 320 is installed in the electroless plating solution in the plating solution storage tank 302. Then, a heating device 322 for indirectly heating the plating solution and a stirring pump 324 for circulating and stirring the electroless plating solution in the plating solution storage tank 302 are provided. This is because, in electroless plating, the electroless plating solution may be used at a high temperature (about 80 ° C.), and this is to cope with this. According to this method, the in-line heating method is used. Compared to the above, it is possible to prevent unnecessary substances and the like from being mixed into a very delicate electroless plating solution.

  According to this example, when the electroless plating solution is plated in contact with the substrate W, the solution temperature is set so that the temperature of the substrate W is 70 to 90 ° C., and the variation range of the solution temperature is ± It is controlled to be within 2 ° C.

  The electroless plating unit 32 includes a plating solution extraction unit 330 that extracts the electroless plating solution in the plating solution storage tank 302 and the composition of the plating solution that the extracted electroless plating unit 32 has, for example, an absorptiometric method. , A plating solution composition analysis unit 332 for analyzing by titration, electrochemical measurement, or the like is provided. The plating solution composition analysis unit 332 measures the cobalt ion concentration by, for example, absorbance analysis, ion chromatography analysis, capillary electrophoresis analysis, or chelate titration analysis of the plating solution.

  The higher the temperature of the electroless plating solution is, the higher the plating speed becomes. If the temperature is too low, the plating reaction does not occur. Therefore, it is generally 60 to 95 ° C, preferably 65 to 85 ° C, and preferably 70 to 85 ° C. More preferably, it is 75 ° C. Basically, it is desirable not to lower the temperature once it is raised, regardless of whether or not plating is actually performed, and it is desirable to keep it at 55 ° C. or higher.

  FIG. 18 shows the details of the drying tank 202 attached to the side of the plating tank 200. A plurality of injection nozzles 280 for injecting a rinsing liquid such as pure water upward are mounted on the nozzle plate 282 at the bottom of the drying tank 202, and the nozzle plate 282 is arranged at the upper end of the nozzle vertical shaft 284. It is connected to. Further, the nozzle vertical shaft 284 moves up and down by changing the screwing position of the nozzle position adjusting screw 287 and the nut 288 screwed to the screw 287, whereby the jet nozzle 280 and the jet nozzle 280 are moved. The distance from the substrate W arranged above can be adjusted optimally.

  In this drying tank 202, the substrate W held by the head portion 232 of the substrate head 204 is placed at a predetermined position in the drying 202, and is rotated from the injection nozzle 280 to a pure position while rotating at a relatively high speed of about 500 rpm, for example. Rinsing liquid such as water is sprayed to replace the plating solution remaining on the surface of the substrate W with a rinsing liquid such as pure water, and the rinsing liquid is removed from the substrate and dried. It is. At this time, a rinsing liquid such as pure water is simultaneously ejected from the head rinsing nozzle 286, and at least a portion in contact with the electroless plating solution of the head portion 232 of the substrate head 204 is rinsed with the rinsing liquid. It is possible to prevent deposits from accumulating in the portion immersed in the electrolytic plating solution.

  As the rinsing liquid, a mixed liquid of a highly volatile liquid and pure water may be used. As a result, the drying time itself can be further shortened while removing (substituting) the plating solution remaining on the surface of the substrate with the rinse solution. Moreover, you may use the pure water which added the cyclic organic compound containing N atom as a rinse liquid. Thereby, the surface of the wiring alloy protective film can be prevented from corrosion while removing (substituting) the plating solution remaining on the surface of the substrate with the rinse solution. Examples of the cyclic organic compound containing an N atom include anticorrosive agents such as BTA (benzotriazole).

In the electroless plating unit 32, the substrate W is adsorbed and held by the head portion 232 of the substrate head 204 at the position where the substrate head 204 is raised as described above, and the electroless plating solution in the plating tank 200 is retained. Keep circulating.
When performing the plating process, the plating tank cover 270 of the plating tank 200 is opened, the substrate head 204 is lowered while rotating, and the substrate W held by the head portion 232 is immersed in the electroless plating solution in the plating tank 200. .

  Then, after immersing the substrate W in the plating solution for a predetermined time, the substrate head 204 is raised, the substrate W is lifted from the electroless plating solution in the plating tank 200, and if necessary, as described above, the substrate The substrate W is immediately cooled by spraying pure water (stop liquid) from the spray nozzle 268 toward W, and the substrate head 204 is further lifted to raise the substrate W to a position above the plating tank 200, so that the substrate head 204 Stop rotation.

  Next, the substrate head 204 is moved to a position directly above the drying tank 202 while the substrate W is sucked and held by the head portion 232 of the substrate head 204. Then, the substrate head 204 is lowered to a predetermined position in the drying tank 202 while rotating at a relatively high speed, and includes pure water, a mixture of highly volatile liquid and pure water, or N atoms from the spray nozzle 280. The substrate W is dried while being rinsed by spraying a rinse liquid such as pure water to which a cyclic organic compound is added. At the same time, a rinsing liquid such as pure water is ejected from the head rinsing nozzle 286 to rinse at least a portion of the head portion 232 of the substrate head 204 that is in contact with the electroless plating solution with the rinsing liquid.

  After the cleaning of the substrate W is completed, the rotation of the substrate head 204 is stopped, the substrate head 204 is raised, the substrate W is pulled up to a position above the drying tank 202, and the substrate head 204 is further moved to the second substrate transfer robot 42. The substrate W is transferred to the second substrate transfer robot 42 and transferred to the next process.

The reforming unit 36 includes, for example, an annealing unit that performs an annealing process, or a plasma processing unit that performs a plasma process. As the reforming unit 36, for example, a plasma processing unit having a parallel plate plasma chamber and performing plasma processing using a mixed gas of H ₂ and N ₂ is used. When the nitride is formed and the substrate is wet-processed again, the wiring protective film can be prevented from being dissolved in the processing solution.

  FIG. 17 shows the post-processing unit 34. The post-processing unit 34 is a unit that forcibly removes particles and unnecessary materials on the substrate W with a roll-shaped brush. The post-processing unit 34 sandwiches the outer periphery of the substrate W and holds the substrate W, and a roller 410. Are provided with a chemical solution nozzle 412 for supplying a chemical solution (two systems) to the surface of the substrate W held in step 1 and a pure water nozzle (not shown) for supplying pure water (one system) to the back surface of the substrate W. Yes.

  As a result, the substrate W is held by the roller 410, the roller drive motor is driven to rotate the roller 410 to rotate the substrate W, and at the same time, a predetermined chemical solution is applied to the front and back surfaces of the substrate W from the chemical solution nozzle 412 and the pure water nozzle. Then, the substrate W is sandwiched and washed from above and below with an upper and lower roll sponge (roll brush) (not shown). The cleaning effect can be increased by rotating the roll sponge alone.

  Further, the post-processing unit 34 is provided with a sponge 419 that rotates while contacting the edge (outer peripheral portion) of the substrate W, and the sponge 419 is applied to the edge of the substrate W to scrub clean it. .

  FIG. 18 shows the drying unit 38. The drying unit 38 is a unit that first performs chemical cleaning and pure water cleaning, and then completely drys the cleaned substrate W by rotating the spindle. The drying unit 38 includes a clamp mechanism 420 that grips an edge portion of the substrate W. A substrate stage 422 and a substrate attaching / detaching lifting plate 424 for opening and closing the clamp mechanism 420 are provided. The substrate stage 422 is connected to the upper end of a spindle 428 that rotates at a high speed as the spindle rotation motor 426 is driven.

Further, a mega jet nozzle 430 that is located on the upper surface side of the substrate W gripped by the clamp mechanism 420 and that supplies pure water with enhanced cleaning effect by transmitting ultrasonic waves when passing through a special nozzle by an ultrasonic oscillator; A rotatable pencil-type cleaning sponge 432 is attached and arranged on the free end side of the swivel arm 434. Accordingly, the cleaning sponge 432 is supplied to the surface of the substrate W while supplying the pure water from the mega jet nozzle 430 toward the cleaning sponge 432 while rotating the swivel arm 434 while holding the substrate W by the clamp mechanism 420 and rotating it. The surface of the substrate W is cleaned by rubbing. A cleaning nozzle (not shown) for supplying pure water is also provided on the back surface side of the substrate W, and the back surface of the substrate W is simultaneously cleaned with pure water sprayed from the cleaning nozzle.
The substrate W thus cleaned is spin-dried by rotating the spindle 428 at a high speed.

Further, a cleaning cup 436 is provided that surrounds the periphery of the substrate W gripped by the clamp mechanism 420 and prevents the processing liquid from being scattered. The cleaning cup 436 moves up and down in accordance with the operation of the cleaning cup lifting and lowering cylinder 438. It has become.
Further, when the drying process in the drying unit is performed, drying efficiency is improved by supplying an inert gas such as N ₂ or Ar gas to the surface to be processed. At the same time, the oxidation of the deposited metal surface is minimized by filling the drying unit with inert gas.
The drying unit 38 may also be equipped with a cavitation function using cavitation.

Next, a series of substrate processing (wiring formation processing) by this substrate processing apparatus will be described with reference to FIG.
First, the substrate W having the wiring 8 formed on the surface thereof is stored in the load / unload unit 22 with the surface of the substrate W facing upward (face up), and one substrate W is transferred to the first substrate. The robot 40 takes it out and conveys it to the first pretreatment unit 28.

  In the first pretreatment unit 28, the substrate W is held face down by the substrate holder 58 of the first pretreatment unit 28, and first precleaning (first plating pretreatment) with a cleaning liquid (chemical solution) is performed on the surface of the substrate. Then, for example, an anticorrosive made of an organic compound such as BTA (benzotriazole) is oxidatively decomposed and removed from the surface of the substrate. That is, as shown in FIG. 3, the processing head 60 is positioned at a position covering the upper end opening of the inner tank 100b, and the spray nozzle 112a of the nozzle plate 112 disposed in the inner tank 100b is placed in the first processing liquid tank 120. The first processing liquid is ejected toward the substrate W. For example, ozone water having a concentration of 10 ppm or more is used as the first treatment liquid. The problem here is not to damage the wiring itself such as copper. Since wiring such as copper is very easily oxidized (corroded), it is not preferable to use an acidic ozone water, and the ozone water itself is preferably used in an alkaline manner. Thereby, organic substances can be decomposed without corroding copper or the like. Moreover, it is not preferable to apply ultrasonic waves because ozone gas easily escapes.

  In the first pretreatment unit 28, the surface of the substrate subjected to the first precleaning is washed (rinsed) with pure water. That is, the substrate holder 58 holding the substrate W is raised to above the inner tank 100b, the upper part of the inner tank 100b is covered with the lid body 102, and then the second from the injection nozzle 112a of the nozzle plate 112 provided on the lid body 102. The processing liquid is ejected toward the substrate W. As the second treatment liquid, preferably degassed pure water is used, and thereby the surface of the substrate W is cleaned (rinsed) with pure water.

  Next, the substrate W after the first pre-cleaning is transported to the second pre-processing unit 30, the substrate W is held face-down by the substrate holder 58 of the second pre-processing unit 30, and the cleaning liquid (chemical solution) is placed on the surface of the substrate. For example, the oxide film formed on the wiring surface is removed from the surface of the substrate. That is, as shown in FIG. 3, the processing head 60 is positioned at a position covering the upper end opening of the inner tank 100b, and the spray nozzle 112a of the nozzle plate 112 disposed in the inner tank 100b is placed in the first processing liquid tank 120. The first processing liquid is ejected toward the substrate W. As the first treatment liquid, an organic acid solution capable of removing the oxide of the wiring material or an inorganic acid solution containing a fluorine compound is used.

  In the second pretreatment unit 30, the surface of the substrate that has been subjected to the second precleaning is washed (rinsed) with pure water. That is, the substrate holder 58 holding the substrate W is raised to above the inner tank 100b, the upper part of the inner tank 100b is covered with the lid body 102, and then the second from the injection nozzle 112a of the nozzle plate 112 provided on the lid body 102. The processing liquid is ejected toward the substrate W. As the second treatment liquid, preferably degassed pure water is used, and thereby the surface of the substrate W is cleaned (rinsed) with pure water.

  Next, the substrate is transported to the electroless plating unit 32. In the electroless plating unit 32, the substrate head 204 holding the substrate W face down is lowered to immerse the substrate W in the electroless plating solution in the plating tank 200, thereby selectively forming the surface of the wiring 8. Electroless plating (electroless CoWBP lid plating) is performed.

  Then, after a predetermined time has elapsed, the substrate W is lifted from the surface of the plating solution, and a plating stop solution such as pure water is ejected from the spray nozzle 268 toward the substrate W, thereby stopping the plating solution on the surface of the substrate W. The electroless plating is stopped by substituting the solution. Next, the substrate head 204 holding the substrate W is positioned at a predetermined position in the drying tank 202, and the nozzle head 282 in the drying tank 202 is rotated while the substrate head 204 is rotated at a relatively high speed of about 500 rpm, for example. Plating remaining on the surface of the substrate W by spraying a rinsing liquid such as pure water, a mixture of highly volatile liquid and pure water, or pure water added with a cyclic organic compound containing N atoms from the spray nozzle 280 The liquid is rinsed (replaced) with a rinse liquid and dried. At the same time, a rinse liquid such as pure water is ejected from the head rinse nozzle 286 to the head part 232 to rinse the head part 232. As a result, a wiring protective film 9 made of a CoWBP alloy film is selectively formed on the surface of the wiring 8 to protect the wiring 8.

  Here, it is preferable that the wiring protective film 9 is selectively formed on the exposed surface of the wiring 8 by performing electroless plating, for example, within 10 seconds immediately after the end of the pre-plating treatment. In this way, immediately after completion of the pre-plating process, electroless plating is performed to selectively form the wiring protective film 9 on the exposed surface of the wiring 8, so that the substrate surface comes into contact with the vaporized plating solution and is plated. Can be prevented as much as possible, and the wiring protective film 9 by electroless plating can be more uniformly formed on the surface of the wiring 8.

  Further, it is preferable to dry the substrate immediately after the electroless plating is completed, for example, within 10 seconds. Thus, after the electroless plating is completed, the wiring protective film 9 made of, for example, a cobalt alloy or a nickel alloy is dissolved in a processing solution such as a cleaning solution by immediately drying the substrate without cleaning it with a chemical solution (cleaning solution). This can be suppressed as much as possible, and the risk of leakage current between the wires 8 can be reduced.

Next, the dried substrate is transported to the modification unit 36, where the surface of the substrate is subjected to a modification treatment such as annealing or plasma treatment to modify the wiring protective film 9 or the surface thereof. . For example, a metal nitride is formed on the surface of the wiring protective film 9 by plasma treatment using a mixed gas of H ₂ and N ₂ . Thereby, for example, during the post-plating process (post-cleaning) using the cleaning liquid (chemical liquid), the wiring protective film 9 is prevented from being dissolved in the cleaning liquid.

  After this modification, the substrate W is transported to the post-processing unit 34, where post-plating processing (post-cleaning) for improving the selectivity of the wiring protective film 9 formed on the surface of the substrate W and increasing the yield. Apply. In other words, a post-plating processing solution (chemical solution) is supplied to the surface of the substrate W while applying a physical force by, for example, roll scrub cleaning or pencil cleaning to the surface of the substrate W, thereby remaining on the insulating film 2. The plating residue such as fine metal particles is completely removed to improve the plating selectivity. As this processing solution, for example, an organic acid solution or an inorganic acid solution containing a fluorine compound having an etching power prepared at an etching rate of 1 to 10 nm / min with respect to the wiring protective film 9 is used. Thereby, the alloy components, impurities, etc. remaining on the insulating film between the wirings can be efficiently removed, and the selectivity of the wiring protective film 9 can be further enhanced.

Then, the post-plating substrate W is transferred to the drying unit 38, where it is rinsed as necessary, and then the substrate W is rotated at high speed and spin-dried.
The substrate W after the spin drying is returned to the substrate cassette mounted on the load / unload unit 22 by the first substrate transfer robot 40.

  During these processes, the oxygen concentration in the housing 26 in which the first pretreatment unit 28, the second pretreatment unit 30, the electroless plating unit 32, and the posttreatment unit 34 are arranged is adjusted to a predetermined value or less. Thereby, the first pre-cleaning of the substrate by the pre-processing unit 28 (first plating pre-processing), the second pre-cleaning of the substrate by the second pre-processing unit 30 (second plating pre-processing), and the wiring by the electroless plating unit 32 The wiring protective film 9 is formed by performing the formation of the protective film 9, the drying process of the substrate, and the post-cleaning (post-plating process) of the substrate by the post-processing unit 34 in the housing 26 whose oxygen concentration is adjusted to a predetermined value or less. It is possible to further suppress the dissolution of the wiring protective film 9 in the liquid during a series of processes for forming the film.

  In the above example, the wiring protective film 9 made of a CoWBP alloy film that can be formed by electroless plating without applying a catalyst is selectively formed on the surface of the wiring 8. As the film 9, a film made of another cobalt-based alloy such as CoWP, CoWB, CoP or CoB, or a nickel-based alloy such as NiWP, NiWB, NiP or NiB may be used. For example, when a CoWP alloy is used as the wiring protective film 9, it is necessary to apply a catalyst such as Pd to the surface of the wiring 8 prior to electroless plating. By using the catalyst application treatment liquid as the first treatment liquid in the treatment unit 30, a catalyst such as Pd can be applied to the surface of the wiring 8.

  Although one embodiment of the present invention has been described so far, it is needless to say that the present invention is not limited to the above-described embodiment, and may be implemented in various forms within the scope of the technical idea.

It is sectional drawing which shows the state in which the wiring protective film which protects wiring by electroless plating was formed. It is a plane arrangement view showing a substrate processing apparatus of an embodiment of the invention. It is the front view which abbreviate | omitted the outer tank at the time of board | substrate delivery of the pre-processing unit shown in FIG. It is the front view which abbreviate | omitted the outer tank at the time of the process by the 1st process liquid of the pre-processing unit shown in FIG. It is the front view which abbreviate | omitted the outer tank at the time of the process by the 2nd process liquid of the pre-processing unit shown in FIG. It is sectional drawing which shows the process head at the time of the board | substrate delivery of the pre-processing unit shown in FIG. It is the A section enlarged view of FIG. FIG. 7 is a view corresponding to FIG. 6 when the substrate of the pretreatment unit shown in FIG. 2 is fixed. It is a systematic diagram of the pre-processing unit shown in FIG. It is sectional drawing which shows the board | substrate head at the time of board | substrate delivery of the electroless-plating unit shown in FIG. It is the B section enlarged view of FIG. FIG. 12 is a view corresponding to FIG. 11 showing the substrate head when the electroless plating unit shown in FIG. 2 is fixed to the substrate. FIG. 12 is a view corresponding to FIG. 11 showing the substrate head during the plating process of the electroless plating unit shown in FIG. 2. FIG. 3 is a partially cut front view showing a plating tank when a plating tank cover of the electroless plating unit shown in FIG. 2 is closed. It is sectional drawing which shows the drying tank of the electroless-plating unit shown in FIG. FIG. 3 is a system diagram of the electroless plating unit shown in FIG. 2. It is a top view of the post-processing unit shown in FIG. It is a vertical front view of the drying unit shown in FIG. 3 is a flowchart showing an example of substrate processing (wiring protection film formation) of the substrate processing apparatus shown in FIG. 2.

Explanation of symbols

4 Recess 8 Wiring 9 Wiring Protective Film 20 Device Frame 22 Load / Unload Unit 24 Control Unit 26 Housings 28 and 30 Pretreatment Unit 32 Electroless Plating Unit 34 Post Treatment Unit 36 Reforming Unit 38 Drying Unit 58 Substrate Holder 60 Processing Head 84 Seal ring 86 Substrate fixing ring 92 Bellows plate 100 Processing tank 102 Lid 120 First processing liquid tank 132 Second processing liquid supply source 200 Plating tank 202 Drying tank 204 Substrate head 230 Housing section 232 Head section 234 Adsorption head

Claims (10)

Prepare a dry substrate by forming embedded wiring with exposed surface inside the insulating film,
Perform plating pretreatment with chemicals on the surface of the substrate,
A substrate processing method comprising: performing electroless plating immediately after completion of the pre-plating process to selectively form a wiring protective film on the exposed surface of the wiring.   2. The substrate processing method according to claim 1, wherein the time from the end of the pre-plating process to the start of electroless plating is within 10 seconds. Prepare a dry substrate by forming embedded wiring with exposed surface inside the insulating film,
Perform plating pretreatment with chemicals on the surface of the substrate,
Conducting electroless plating on the surface of the substrate after the plating pretreatment to selectively form a wiring protective film on the exposed surface of the wiring,
A substrate processing method comprising drying a substrate immediately after completion of electroless plating.   4. The substrate processing method according to claim 3, wherein the time from the end of electroless plating to the start of drying of the substrate is within 10 seconds.   The substrate is dried by supplying a highly volatile liquid and pure water to the rotating substrate to remove liquid components from the substrate, and supplying the rotating substrate with pure water added with a cyclic organic compound containing N atoms. 5. The substrate processing method according to claim 3, wherein the liquid component is removed by at least one of the methods for removing the liquid component from the substrate. The substrate that has been dried after electroless plating is subjected to a modification treatment to modify the wiring protective film or its surface, and then
6. The substrate processing method according to claim 3, wherein a post-plating process of the substrate is performed and the substrate is dried again.   7. The substrate processing method according to claim 6, wherein the modification process is an annealing process or a plasma process. A pre-processing unit for performing pre-plating treatment with a chemical solution on the surface of the substrate that has been formed by drying the embedded wiring with the surface exposed inside the insulating film and dried;
A substrate having an electroless plating unit for performing electroless plating on the surface of the substrate after pre-plating treatment to selectively form a wiring protective film on the exposed surface of the wiring, and then drying the substrate. Processing equipment.   The substrate processing apparatus according to claim 8, wherein the pretreatment unit and the electroless plating unit are arranged inside a casing in which an internal atmosphere can be controlled. A modification unit for modifying the wiring protective film or its surface;
10. The substrate processing apparatus according to claim 8, further comprising a post-processing unit that performs post-plating processing on the wiring protective film or a substrate whose surface is modified.