Plating method, plating system and storage medium

This Application is a U.S. national phase application under 35 U.S.C. § 371 of PCT Application No. PCT/JP2013/054504 filed on Feb. 22, 2013, which claims the benefit of Japanese Patent Application No. 2012-065489 filed on Mar. 22, 2012, the entire disclosures of which are incorporated herein by reference.

The embodiments described herein pertain generally to a plating method and a plating system of performing a plating process on a substrate, and a storage medium.

Recently, semiconductor devices such as a LSI or the like have been required to have higher density in order to meet requirements for reducing the mounting space or for improving the processing rate. As an example of a technology that achieves the high density, there has been known a multilayer wiring technology of manufacturing a multilayer substrate, such as a three-dimensional LSI or the like, by stacking multiple wiring substrates.

According to the multilayer wiring technology, a through-via-hole, which penetrates the wiring substrates and in which a conductive material such as copper (Cu) is buried, is typically formed in the wiring substrate in order to obtain electrical connection between the wiring substrates. As an example of a technology for forming the through-via-hole in which a conductive material is buried, there has been known an electroless plating method.

As a specific method of producing a wiring substrate, there is known a method in which a substrate having a recess is prepared, a barrier film is formed as a Cu diffusion barrier film within the recess of the substrate, and a seed film is formed on the barrier film by electroless Cu plating. Thereafter, Cu is buried in the recess by electrolytic Cu plating, and the substrate in which the Cu is buried is then thinned by a polishing method such as chemical mechanical polishing. Through this process, a wiring substrate having a through-via-hole in which the Cu is buried is manufactured.

To form the barrier film of the aforementioned wiring substrate, by adsorbing a catalyst onto the substrate in advance, a catalyst adsorption layer is formed, and by performing a plating process on the catalyst adsorption layer, a barrier film formed of Co—W—B layers is obtained. The barrier film is then baked, so that moisture within the barrier film is removed and the bond between metals is strengthened.

Patent Document 1: Japanese Patent Laid-open Publication No. 2010-185113

Problems to be Solved by the Invention

As stated above, the barrier film as the Cu diffusion barrier film is formed through the plating process, and by being baked thereafter, moisture within the barrier film is removed and the bond between the metals is enhanced.

During the baking process, however, a stress may be generated between the barrier film and the substrate, so that adhesivity between the barrier film and the substrate may be weakened.

In view of the foregoing problems, example embodiments provide a plating method and a plating system of forming a barrier film on a substrate through a plating process and maintaining adhesivity between the barrier film and the substrate even when the barrier film is baked, and a storage medium.

Means for Solving the Problems

In one example embodiment, a plating method of performing a plating process on a substrate includes a substrate preparing process of preparing the substrate; a plating layer forming process of forming a plating layer having a preset function by performing the plating process on the substrate with a plating liquid; and a plating layer baking process of baking the plating layer by heating the substrate. Further, by repeating the plating layer forming process and the plating layer baking process at least twice, a plating layer stacked body having a first plating layer obtained through a first plating layer forming process and a first plating layer baking process and a second plating layer obtained through a second plating layer forming process and a second plating layer baking process is formed.

In another example embodiment, a plating system of performing a plating process on a substrate includes a plating layer forming unit configured to form a plating layer having a preset function by performing the plating process on the substrate with a plating liquid; a plating layer baking unit configured to bake the plating layer by heating a base; a substrate transfer unit configured to transfer the substrate between the plating layer forming unit and the plating layer baking unit; and a controller configured to control the plating layer forming unit, the plating layer baking unit and the substrate transfer unit. Further, by repeating a plating layer forming process in the plating layer forming unit and a plating layer baking process in the plating layer baking unit at least twice, a plating layer stacked body having a first plating layer obtained through a first plating layer forming process and a first plating layer baking process and a second plating layer obtained through a second plating layer forming process and a second plating layer baking process is formed.

In yet another example embodiment, a computer-readable storage medium has stored thereon computer-executable instructions that, in response to execution, cause a plating system to perform a plating method. Further, the plating method includes a substrate preparing process of preparing a substrate; a plating layer forming process of forming a plating layer having a preset function by performing a plating process on the substrate with a plating liquid; and a plating layer baking process of baking the plating layer by heating the substrate. Furthermore, by repeating the plating layer forming process and the plating layer baking process at least twice, a plating layer stacked body having a first plating layer obtained through a first plating layer forming process and a first plating layer baking process and a second plating layer obtained through a second plating layer forming process and a second plating layer baking process is formed.

Effect of the Invention

In accordance with the example embodiments, a plating layer stacked body, having a first plating layer obtained through a first plating layer forming process and a first plating layer baking process and a second plating layer obtained through a second plating layer forming process and a second plating layer baking process, is formed. Thicknesses of the first plating layer and the second plating layer of the plating layer stacked body are smaller than a thickness of the plating layer stacked body, and a strong adhesion layer is previously formed when baking the first plating layer. Accordingly, it is possible to suppress the peeling off due to a stress of the second plating layer generated when baking the second plating layer, as compared to a case of baking a plating layer having the same thickness as that of the plating layer stacked body. Therefore, the adhesivity between the underlying layer and the first plating layer and the second plating layer can be enhanced.

FIG. 1 is a block diagram illustrating a plating system in accordance with an example embodiment.

FIG. 2 is a flowchart for describing a plating method in accordance with the example embodiment.

FIG. 3A to FIG. 3F are diagrams illustrating a substrate on which the plating method of the example embodiment is performed.

FIG. 4 is a cross sectional view illustrating a plating layer stacked body as a Cu diffusion barrier film.

FIG. 5 is a side cross sectional view illustrating a plating layer forming unit.

FIG. 6 is a plane view illustrating the plating layer forming unit.

FIG. 7 is a side cross sectional view illustrating a plating layer baking unit.

FIG. 8 is a cross sectional view showing a plating layer stacked body as a seed film, which is illustrated as a modification example of the example embodiment.

Plating System

Referring to FIG. 1 to FIG. 7 , an example embodiment will be described.

First, a plating system in accordance with the example embodiment will be elaborated with reference to FIG. 1 .

As depicted in FIG. 1 , the plating system 10 is configured to perform a plating process on a substrate (silicon substrate) 2 , such as a semiconductor wafer, having a recess 2 a.

The plating system 10 includes a cassette station 18 configured to mount thereon a cassette (not shown) which accommodates the substrate 2 ; a substrate transfer arm 11 configured to take out the substrate 2 from the cassette on the cassette station 18 and transfer the substrate 2 ; and a moving path 11 a along which the substrate transfer arm 11 is moved.

Arranged at one side of the moving path 11 a are an adhesion layer forming unit 12 configured to form an adhesion layer 21 to be described later by adsorbing a coupling agent such as a silane coupling agent onto the substrate 2 ; a catalyst adsorption layer forming unit 13 configured to form a catalyst adsorption layer 22 to be described later by adsorbing a catalyst onto the adhesion layer 21 of the substrate; and a plating layer forming unit 14 configured to form plating layers 23 a and 23 b serving as a Cu diffusion barrier film (barrier film) to be described later on the catalyst adsorption layer 22 of the substrate 2 .

Further, arranged at the other side of the moving path 11 a are a plating layer baking unit 15 configured to bake the plating layers 23 a and 23 b formed on the substrate 2 ; and an electroless Cu plating layer forming unit 16 configured to form an electroless copper (Cu) plating layer 24 , serving as a seed film to be described later, on the plating layers 23 a and 23 b formed on the substrate 2 .

Further, an electrolytic Cu plating layer forming unit 17 configured to fill the recess 2 a of the substrate 2 with an electrolytic Cu plating layer 25 while using the electroless Cu plating layer 24 as a seed film is provided adjacent to the plating layer baking unit 15 .

After the first plating layer 23 a is formed in the plating layer forming unit 14 , the first plating layer 23 a is baked in the plating layer baking unit 15 . Then, in the plating layer forming unit 14 , the second plating layer 23 b is formed on top of the baked first plating layer 23 a , and the second plating layer 23 b is then baked in the plating layer baking unit 15 .

Through these processes, the plating layer stacked body 23 in which the first plating layer 23 a and the second plating layer 23 b are stacked is formed on the catalyst adsorption layer 22 of the substrate 2 .

Each of the first plating layer 23 a and the second plating layer 23 b of the plating layer stacked body 23 having the above-described structure serves as a Cu diffusion barrier film (barrier film).

Further, the respective constituent components of the above-described plating system, for example, the cassette station 18 , the substrate transfer arm 11 , the adhesion layer forming unit 12 , the catalyst adsorption layer forming unit 13 , the plating layer forming unit 14 , the plating layer baking unit 15 , the electroless Cu plating layer forming unit 16 and the electrolytic Cu plating layer forming unit 17 are controlled by a controller 19 according to various types of programs recorded in a storage medium 19 A provided in the controller 19 , so that various processes are performed on the substrate 2 . Here, the storage medium 19 A stores thereon various kinds of setup data or various kinds of programs such as a plating method to be described later. The storage medium 19 A may be implemented by a computer-readable memory such as a ROM or a RAM, or a disk-type storage medium such as a hard disk, a CD-ROM, a DVD-ROM or a flexible disk, as commonly known in the art.

Below, the plating layer forming unit 14 and the plating layer baking unit 15 configured to form the first plating layer 23 a and the second plating layer 23 b , which serve as the Cu diffusion barrier film (barrier film), and the electroless Cu plating layer forming unit 16 will be further elaborated.

Among these, each of the plating layer forming unit 14 and the electroless Cu plating layer forming unit 16 may be implemented by a plating apparatus as illustrated in FIG. 5 and FIG. 6 .

These plating apparatuses 14 and 16 are as depicted in FIG. 5 and FIG. 6 .

That is, each of the plating apparatuses 14 and 16 includes, as shown in FIG. 5 and FIG. 6 , a substrate holding/rotating device (substrate accommodating unit) 110 configured to hold and rotate the substrate 2 within a casing 101 ; liquid supplying devices 30 and 90 configured to supply a plating liquid, a cleaning liquid or the like onto a surface of the substrate 2 ; a cup 105 configured to collect the plating liquid, the cleaning liquid or the like dispersed from the substrate 2 ; draining openings 124 , 129 and 134 configured to drain the plating liquid or the cleaning liquid collected by the cup 105 ; liquid draining devices 120 , 125 and 130 configured to drain the liquids collected in the draining openings; and a controller 160 configured to control the substrate holding/rotating device 110 , the liquid supplying devices 30 and 90 , the cup 105 and the liquid draining devices 120 , 125 and 130 .

(Substrate Holding/Rotating Device)

The substrate holding/rotating device 110 includes, as illustrated in FIG. 5 and FIG. 6 , a hollow cylindrical rotation shaft 111 vertically extended within the casing 101 ; a turntable 112 provided on an upper end portion of the rotation shaft 111 ; a wafer chuck 113 disposed on a peripheral portion of a top surface of the turntable 112 to support the substrate 2 ; and a rotating device 162 configured to rotate the rotation shaft 111 . The rotating device 162 is controlled by the controller 160 , and the rotation shaft 111 is rotated by the rotating device 162 . As a result, the substrate 2 supported on the wafer chuck 113 is rotated.

(Liquid Supplying Device)

Now, the liquid supplying devices 30 and 90 configured to supply a plating liquid, a cleaning liquid, or the like onto the surface of the substrate 2 will be explained with reference to FIG. 5 and FIG. 6 . The liquid supplying device 30 is a plating liquid supplying device configured to supply a plating liquid for performing a plating process on the surface of the substrate 2 . The liquid supplying device 90 is a cleaning liquid supplying device configured to supply a cleaning liquid onto the surface of the substrate 2 .

As depicted in FIG. 5 and FIG. 6 , a discharge nozzle 32 is provided at a nozzle head 104 . The nozzle head 104 is provided at a leading end portion of an arm 103 . The arm 103 is provided at a supporting shaft 102 rotated by a rotating device 165 to be moved in a vertical direction. A plating liquid supplying line of the plating liquid supplying device 30 is embedded within the arm 103 . With this configuration, it is possible to discharge the plating liquid onto a target position on the surface of the substrate 2 through the discharge nozzle 32 from a required supply height.

(Cleaning Liquid Supplying Device 90 )

The cleaning liquid supplying device 90 is configured to perform a cleaning process on the substrate 2 as will be described later. As illustrated in FIG. 5 , the cleaning liquid supplying device 90 includes a nozzle 92 provided at the nozzle head 104 . In this configuration, either a cleaning liquid or a rinse liquid is selectively discharged onto the surface of the substrate 2 from the nozzle 92 .

(Liquid Draining Device)

Now, the liquid draining devices 120 , 125 and 130 configured to drain out the plating liquid or the cleaning liquid dispersed from the substrate 2 will be elaborated with reference to FIG. 5 . As shown in FIG. 5 , the cup 105 , which can be moved up and down by an elevating device 164 and has the draining openings 124 , 129 and 134 , is disposed within the casing 101 . The liquid draining devices 120 , 125 and 130 are configured to drain out the liquids collected in the draining openings 124 , 129 and 134 , respectively.

As depicted in FIG. 5 , the plating liquid draining devices 120 and 125 include collecting flow paths 122 and 127 and waste flow paths 123 and 128 , which are switched by flow path switching devices 121 and 126 , respectively. Here, the plating liquid is collected and reused through the collecting flow paths 122 and 127 , while the plating liquid is drained out through the waste flow paths 123 and 128 . Further, as shown in FIG. 5 , the processing liquid draining device 130 is only equipped with a waste flow path 133 .

Further, as depicted in FIG. 5 and FIG. 6 , the collecting flow path 122 of the plating liquid draining device 120 configured to drain the plating liquid is connected to an outlet side of the substrate accommodating unit 110 , and a cooling buffer 120 A configured to cool the plating liquid is provided at a portion of the collecting flow path 122 in the vicinity of the outlet side of the substrate accommodating unit 110 .

Now, the plating layer baking unit 15 will be elaborated.

The plating layer baking unit 15 includes, as illustrated in FIG. 7 , an airtightly sealed casing 15 a ; and a hot plate 15 A provided within the airtightly sealed casing 15 a.

The airtightly sealed casing 15 a of the plating layer baking unit 15 is provided with a transfer opening (not shown) through which the substrate 2 is transferred. An N 2 gas is supplied into the airtightly sealed casing 15 a through an N 2 gas supply opening 15 c.

Concurrently, the inside of the airtightly sealed casing 15 a is evacuated through an exhaust opening 15 b , and by supplying the N 2 gas into the airtightly sealed casing 15 a , the inside of the airtightly sealed casing 15 a can be maintained under an inert gas atmosphere.

An operation of the example embodiment having the above-described configuration will be explained with reference to FIG. 2 to FIG. 3F .

First, in a pre-process, a recess 2 a is formed on a substrate (silicon substrate) 2 such as a semiconductor wafer or the like. The substrate 2 having thereon the recess 2 a is then transferred into the plating system 10 in accordance with the example embodiment.

Within the adhesion layer forming unit 12 of the plating system 10 , an adhesion layer 21 is formed on the substrate 2 having the recess 2 a ( FIG. 2 and FIG. 3A ).

Here, as a method of forming the recess 2 a on the substrate 2 , a commonly known method in the art may be appropriately employed. Specifically, as a dry etching technique, for example, a general-purpose technique using a fluorine-based gas or a chlorine-based gas may be employed. Especially, in order to form a hole having a high aspect ratio (a hole depth/a hole diameter), a method using an ICP-RIE (Inductively Coupled Plasma Reactive Ion Etching) technique, which can perform a deep etching process with a high speed, may be more appropriately adopted. Especially, a Bosch process in which an etching process using sulfur hexafluoride (SF 6 ) and a protection process using a teflon-based gas such as C 4 F 8 are repeatedly performed may be appropriately utilized.

Further, the adhesion layer forming unit 12 has a decompression chamber (not shown) equipped with a heating unit. Within the adhesion layer forming unit 12 , a coupling agent such as a silane coupling agent is adsorbed onto the substrate 2 having the recess 2 a , so that the adhesion layer 21 is formed on the substrate 2 (SAM process). The adhesion layer 21 formed by adsorbing the silane coupling agent is configured to improve adhesivity between the substrate 2 and a catalyst adsorption layer 22 to be described later.

The substrate 2 on which the adhesion layer 21 is formed in the adhesion layer forming unit 12 is then transferred into the catalyst adsorption layer forming unit 13 by the substrate transfer arm 11 . In the catalyst adsorption layer forming unit 13 , Pd ions that may serve as a catalyst are adsorbed on the adhesion layer 21 of the substrate 2 , so that the catalyst adsorption layer 22 is formed ( FIG. 3B ).

As the catalyst adsorbing process, a process of discharging an aqueous solution of palladium chloride through a nozzle and adsorbing Pd ions serving as the catalyst onto the surface of the substrate 2 may be employed. To elaborate, tin ions are adsorbed onto the surface of the substrate 2 by discharging a stannous chloride solution onto the substrate 2 , and, then, by discharging the palladium chloride solution onto the surface 2 to replace the tin ions, the Pd ions are adsorbed onto the substrate 2 . Then, by discharging sodium hydroxide onto the substrate 2 , the tin ions remaining on the substrate 2 are removed.

After the catalyst adsorption layer 22 is formed on the substrate 2 in the catalyst adsorption layer forming unit 13 as stated above, the substrate 2 is then transferred into the plating layer forming unit 14 by the substrate transfer arm 11 .

Subsequently, in the plating layer forming unit 14 , a first plating layer 23 a serving as a Cu diffusion barrier film (barrier film) is formed on the catalyst adsorption layer 22 of the substrate 2 ( FIG. 3C and FIG. 4 ).

In this case, the plating layer forming unit 14 is implemented by the plating apparatus as illustrated in FIG. 5 and FIG. 6 . The first plating layer 23 a can be formed by performing an electroless plating process on the catalyst adsorption layer 22 of the substrate 2 .

When forming the first plating layer in the plating layer forming unit 14 , a plating liquid containing, for example, Co—W—B may be used, and a temperature of the plating liquid is maintained at 40° C. to 75° C. (desirably, 65° C.).

By supplying the plating liquid containing the Co—W—B onto the substrate 2 , the first plating layer 23 a containing the Co—W—B is formed on the catalyst adsorption layer 22 of the substrate 2 through the electroless plating process.

Thereafter, the substrate 2 in which the first plating layer 23 a is formed on the catalyst adsorption layer 22 is transferred from the plating layer forming unit 14 into the airtightly sealed casing 15 a of the plating layer baking unit 15 by the substrate transfer arm 11 . Within the airtightly sealed casing 15 a of the plating layer baking unit 15 , the substrate 2 is heated on the hot plate 15 A under an inert gas atmosphere of N 2 gas in order to suppress the substrate 2 from being oxidized. Accordingly, the first plating layer 23 a of the substrate 2 is baked (baking process).

When baking the first plating layer 23 a in the plating layer baking unit 15 , a baking temperature may be set to be in the range from, e.g., 150° C. to 200° C., and a baking time is set to be in the range from, e.g., 10 minutes to 30 minutes.

By baking the first plating layer 23 a on the substrate 2 as described above, moisture within the first plating layer 23 a can be removed, and, at the same time, the bond between metals within the first plating layer 23 a can be enhanced. The substrate 2 heated in the plating layer baking unit 15 is delivered back to the plating layer forming unit 14 by the substrate transfer arm 11 . Then, within the plating layer forming unit 14 , an electroless plating process is performed on the substrate 2 . Accordingly, the second plating layer 23 b is formed on the first plating layer 23 a through the autocatalytic plating.

When forming the second plating layer 23 b on the first plating layer 23 a , a plating liquid containing Co—W—B may be used, as in the case of forming the first plating layer 23 a . A temperature of the plating liquid is maintained at 40° C. to 75° C. (desirably, 65° C.), as in the case of forming the first plating layer 23 a.

Alternatively, when forming the second plating layer 23 b in the plating layer forming unit 14 , unlike when forming the first plating layer 23 a , a plating liquid containing Co—W—P may be used instead of the plating liquid containing the Co—W—B, and a temperature of the plating liquid may be in the range from, e.g., 40° C. to 80° C., desirably, 70° C.

In any cases, when forming the second plating layer 23 b , a plating liquid containing the same metals (Co—W) as the first plating layer 23 a is used, and the second plating layer 23 b formed as described above serves as a Cu diffusion barrier film (barrier film).

Further, in the above, though the plating liquids containing the Co—W are used when forming the first plating layer 23 a and the second plating layer 23 b , the example embodiment may not be limited thereto. By way of example, a plating liquid containing Co may be used to form the first plating layer 23 a , while using a plating liquid containing Co—W to form the second plating layer 23 b . Alternatively, a plating liquid containing Co—W may be used to form the first plating layer 23 a , while using a plating liquid containing Co to form the second plating layer 23 b . A combination of a plating liquid for forming the first plating layer 23 a and a plating liquid for forming the plating liquid for forming the second plating layer 23 b can be selected among any of plating liquids containing cobalt-based materials, e.g., a Co—P containing plating liquid, a Co—B containing plating liquid, a Co—W containing liquid, a Co—W—P containing plating liquid, a Co—W—B containing plating liquid, and so forth.

Subsequently, the substrate 2 on which the second plating layer 23 b is formed in the plating layer forming unit 14 is delivered back to the plating layer baking unit 15 from the plating layer forming unit 14 by the substrate transfer arm 11 . The substrate 2 is heated on the hot plate 15 A within the airtightly sealed casing 15 a of the plating layer baking unit 15 , so that the second plating layer 23 b is baked.

A baking temperature and a baking time for baking the second plating layer 23 b are set to be the substantially same as the baking temperature and the baking time for baking the first plating layer 23 a . However, the baking temperature and the baking time for the second plating layer 23 b may be set to be different from the baking temperature and the baking time for the first plating layer 23 a . By baking the second plating layer 23 b on the substrate 2 , moisture within the second plating layer 23 b can be removed, and, at the same time, the bond between metals within the second plating layer 23 b can be enhanced.

Through the above-described processes, it is possible to obtain a plating layer stacked body 23 having the first plating layers 23 a and the second plating layer 23 b and serving as a Cu diffusion barrier film (barrier film).

In general, although the bonds between the metals in the first plating layer 23 a and the second plating layer 23 b can be enhanced by baking the plating layers 23 a and 23 b , if the thicknesses of the baked plating layers are large, a stress accompanied by deformation of the plating layers may be generated between an underlying layer and the plating layers.

In accordance with the present example embodiment, however, the plating layer stacked body 23 serving as the barrier film is formed of the first plating layer 23 a obtained by the first plating layer forming process and the first plating layer baking process and the second plating layer 23 b obtained by the second plating layer forming process and the second plating layer baking process. Thus, the thickness of the plating layer baked in the first baking process or in the second baking process can be made small, as compared to the entire thickness of the plating layer stacked body 23 .

Accordingly, when baking the respective plating layers 23 a and 23 b , a stress generated between these layers and the underlying layer (for example, the catalyst adsorption layer 22 ) can be decreased, so that adhesivity between the plating layers 23 a and 23 b and the underlying layer can be increased.

Further, in order to enhance the adhesivity between the plating layers 23 a and 23 b and the underlying layer 22 by reducing the stress generated therebetween, it may be desirable to set the thickness of the first plating layer 23 a to be smaller than the thickness of the second plating layer 23 b . Further, in the baking processes of the plating layers 23 a and 23 b , it is desirable to remove moisture sufficiently by setting the baking temperature for the first plating layer 23 a to be higher than the baking temperature for the second plating layer 23 b or by setting the baking times for the first plating layer 23 a to be longer than the baking times for the second plating layer 23 b.

Further, the plating layer stacked body 23 may not be limited to the structure including the first plating layer 23 a and the second plating layer 23 b . For example, the plating layer stacked body 23 may include a third plating layer and a fourth plating layer in addition to the first plating layer 23 a and the second plating layer 23 b.

The substrate 2 having the plating layer stacked body 23 serving as the barrier film is then sent to the electroless Cu plating layer forming unit 16 by the substrate transfer arm 11 .

Subsequently, in the electroless Cu plating layer forming unit 16 , an electroless Cu plating layer 24 serving as a seed film for forming an electrolytic Cu plating layer 25 is formed on the plating layer stacked body 23 of the substrate 2 ( FIG. 3D ).

Here, the electroless Cu plating layer forming unit 16 is implemented by the plating apparatus as illustrated in FIG. 5 and FIG. 6 . By performing the electroless plating process on the plating layer stacked body 23 of the substrate 2 , the electroless Cu plating layer 24 can be formed.

The electroless Cu plating layer 24 formed in the electroless Cu plating layer forming unit 16 serves as the seed film for forming the electrolytic Cu plating layer 25 . A plating liquid used in the electroless Cu plating layer forming unit 16 may contain a copper salt as a source of copper ions, such as copper sulfate, copper nitrate, copper chloride, copper bromide, copper oxide, copper hydroxide, copper pyrophosphate, or the like. The plating liquid may further contain a reducing agent and a complexing agent for the copper ions. Further, the plating liquid may further contain various kinds of additives for improving stability or speed of the plating reaction.

The substrate 2 on which the electroless Cu plating layer 24 is formed as described above is then sent to the electrolytic Cu plating layer forming unit 17 by the substrate transfer arm 11 . Here, the substrate 2 on which the electroless Cu plating layer 24 is formed may be sent to the electrolytic Cu plating layer forming unit 17 after baked in the baking unit 15 . Subsequently, an electrolytic Cu plating process is performed on the substrate 2 within the electrolytic Cu plating layer forming unit 17 , so that the electrolytic Cu plating layer 25 is buried within the recess 2 a of the substrate 2 while using the electroless Cu plating layer 24 as the seed film ( FIG. 3E ).

Thereafter, the substrate 2 is unloaded from the plating system 10 , and a rear surface side of the substrate 2 (opposite side to the side where the recess 2 a is formed) is polished chemically and mechanically ( FIG. 3F ).

In accordance with the present example embodiment as stated above, the plating layer stacked body 23 serving as the barrier film is formed of the first plating layer 23 a obtained by the first plating layer forming process and the first plating layer baking process and the second plating layer 23 b obtained by the second plating layer forming process and the second plating layer baking process. Accordingly, a stress between these plating layers and the underlying layer generated when baking the plating layers 23 a and 23 b can be reduced, so that adhesivity between the plating layers and the underlying layer can be enhanced.

Modification Examples

Now, modification examples of the example embodiment will be explained. In the above-described example embodiment, the plating layer stacked body 23 serving as the Cu diffusion barrier film (barrier film) is formed of the first plating layer 23 a and the second plating layer 23 b . However, the example embodiment may not be limited thereto, and the electroless Cu plating layer 24 serving as the seed film may be formed of a plating layer stacked body 23 having a first plating layer 24 a and a second plating layer 24 b ( FIG. 8 ).

In such a case, the first plating layer 24 a of the electroless Cu plating layer 24 is formed through a first plating layer forming process in the electroless Cu plating layer forming unit 16 , and, then, baked through a first plating layer baking process in the plating layer baking unit 15 . Further, the second plating layer 24 b is formed through a second plating layer forming process in the electroless Cu plating layer forming unit 16 and, then, baked through a second plating layer baking process in the plating layer baking unit 15 . Accordingly, the plating layer stacked body 24 having the first plating layer 24 a and the second plating layer 24 b and serving as the seed film for the electrolytic Cu plating layer 25 is obtained.

Further, the above-described example embodiment has been described for the case of burying the electrolytic Cu plating layer through the electrolytic Cu plating process. However, the example embodiment may not be limited thereto, and it may be possible to form the Cu plating layer through the electroless Cu plating process instead of the electrolytic Cu plating process.

Additionally, in the above-described example embodiment, when baking the first plating layer 23 a and the second plating layer 23 b , the substrate 2 is heated on the hot plate 15 A under the inert-gas atmosphere of N 2 gas within the airtightly sealed casing 15 a of the plating layer baking unit 15 . However, the example embodiment may not be limited thereto, and the substrate 2 may be heated on the hot plate 15 A after evacuating the inside of the airtightly sealed casing 15 a to a vacuum level, for in order to lower the temperature or shorten the processing time.

Furthermore, in the above-described example embodiment, the plating layer forming unit 14 and the plating baking unit 15 are configured as separate apparatuses. However, the example embodiment may not be limited thereto. By way of example, by providing a heating source such as a lamp irradiator 200 (UV light or the like) above the substrate 2 or a hot plate (not shown) covering the substrate 2 in the plating layer forming unit 14 shown in FIG. 5 , it may be possible to bake the plating layers within the plating layer forming unit 14 .

2 : Substrate

2 a : Recess

10 : Plating system

11 : Substrate transfer arm

12 : Adhesion layer forming unit

13 : Catalyst adsorption layer forming unit

14 : Plating layer forming unit

15 : Plating layer baking unit

15 A: Hot plate

15 a : Airtightly sealed casing

15 b : Exhaust opening

15 c : N 2 gas supply opening

16 : Electroless Cu plating layer forming unit

17 : Electrolytic Cu plating layer forming unit

18 : Cassette station

19 : Controller

19 A: Storage medium

21 : Adhesion layer

22 : Catalyst adsorption layer

23 : Plating layer stacked body

23 a : First plating layer

23 b : Second plating layer

24 : Electroless Cu plating layer

25 : Electrolytic Cu plating layer