JP2006063386A - Method for producing semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method where, at the time when the surface of copper wiring buried into a recessed part formed at an insulation film is subjected to palladium substitution plating, the etching in the surface of the copper wiring is suppressed, and a semiconductor device capable of maintaining satisfactory electrical properties over a long period is produced. <P>SOLUTION: Copper is buried into a recessed part 200 formed by subjecting an insulation film such as an SiOC film 21 to etching, so as to form copper wiring 25. Thereafter, using a substitution plating liquid obtained by dissolving palladium into a solution of an organic acid having a carboxy group, the surface of the copper wiring 25 buried into the recessed part 200 is subjected to palladium substitution plating. Then, an adhesive layer 27 is formed on the surface of the copper wiring 25 on which a palladium film is formed using an electroless plating liquid. In this case, by the selection of the organic acid, the etching of the copper wiring 25 at the time of the palladium substitution plating can be suppressed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method of manufacturing a semiconductor device including a copper wiring embedded in an insulating film and having a barrier film formed thereon by electroless plating.

  In recent years, a wiring technique using a copper wire instead of an aluminum wire has been implemented because of a demand for improving the performance of a semiconductor device (semiconductor device). Copper has a lower resistance than aluminum and has excellent electromigration resistance (EM resistance), but also has a problem of high possibility of diffusion into a semiconductor substrate and is easily oxidized. Yes. For this reason, various barrier materials called barrier metals and protective films are used between copper and an interlayer insulating film (hereinafter abbreviated as “insulating film”) wired in a multilayer structure in a semiconductor device.

  As one of the techniques for realizing the copper multilayer wiring as described above, a barrier material (barrier such as tantalum nitride or titanium nitride) is formed on the surface of the insulating film including the recess formed for embedding the wiring in the damascene process. The wiring is covered with copper (Cu) for wiring, and the substrate surface is polished by a polishing process called CMP (Chemical Mechanical Polishing) to remove copper and the barrier material other than the recesses. . Then, a next-stage insulating film is formed so as to close the upper part of the recess.

  Here, if the next-stage insulating film is formed on the copper wiring as it is, copper diffuses into the insulating film, so that it is necessary to form a barrier film on the upper surface of the buried copper. Conventionally, silicon nitride, silicon carbide, silicon nitride carbide, or the like has been used for the barrier film. For example, when a carbon-containing silicon oxide film (hereinafter referred to as “SiOC film”) is used as the insulating film, this barrier film also serves as an etching stopper during etching.

  However, since a barrier film formed of silicon nitride, silicon carbide, silicon nitride carbide, or the like has low adhesion to copper, a portion having poor adhesion as shown in FIG. Then, the barrier film 10 cannot physically hold copper (copper atoms) of the copper wiring 1, and the copper atoms may move to form a space 11 called a void at the interface with the barrier film 10. Since the copper atoms on the surface portion of the portion where the space 11 is formed and no longer in contact with the barrier film 10 are more likely to move, the space 10 grows further and the electrical characteristics deteriorate, and finally the copper wiring 1 is disconnected. There is a concern that it will. In the figure, 12 is a barrier material, and 13 is a SiOC film which is one of insulating films.

  On the other hand, recently, it has been proposed to form an adhesion layer (adhesion film) for improving the adhesion between copper and the barrier film 10 by electroless plating (see, for example, Patent Document 1). In this method, as a pretreatment, first, a hydrochloric acid solution of palladium chloride is supplied to the surface of the semiconductor substrate on which the copper wiring is formed, and the upper surface of the copper wiring is replaced with palladium by utilizing the difference in ionization tendency between copper and palladium. To form a catalytically active layer. Subsequently, an electroless plating solution is supplied to the surface of the semiconductor substrate instead of the hydrochloric acid solution, and CoWP (cobalt containing phosphorus is formed on the upper surface of the copper wiring by utilizing the catalytic action of palladium deposited on the surface in the previous step. An adhesion layer such as tungsten) or NiWP (nickel tungsten containing phosphorus) is formed. Thereafter, the barrier film 10 is formed on the upper surface of the adhesion layer. That is, this Patent Document 1 describes that after the copper wiring is formed, plating is performed on the upper surface of copper to form an adhesion layer, and this adhesion layer provides adhesion between copper and the barrier film 10. This is effective in that it has a role of preventing copper from diffusing into the insulating film.

  However, when palladium displacement plating is performed using a hydrochloric acid solution of palladium chloride, since the hydrochloric acid has a strong oxidizing power, the substitution reaction between copper and palladium proceeds. For example, as shown in FIG. In some cases, so-called crevice corrosion is promoted at a portion in contact with the barrier material 12 formed on the surface, particularly the side peripheral surface, and copper is dissolved. From the viewpoint of ionization, copper is considered to be a substance that does not dissolve in hydrochloric acid. However, since the barrier material 12 contains a metal such as tantalum (a different metal from copper), this promotes crevice corrosion. I guess. Even if the adhesion layer is formed, the space 11 remains unfilled. As a result, the space 11 may be formed between the barrier material 12 and the copper wiring 1, and the space 11 is formed as described above. It can be a cause of deterioration of electrical characteristics and disconnection.

  Here, in recent years, semiconductor devices have been increasingly miniaturized and highly integrated, and accordingly, the line width of the copper wiring 1 is also targeted to be 65 nm or less, further 45 nm or less, for example. If the line width is large, the deterioration of the electrical characteristics caused by the formation of the space 11 is rarely regarded as a problem. However, when the line width is reduced in this way, even if the space has the same size, the line width is reduced. Since the ratio increases, the degree of deterioration of the electrical characteristics increases accordingly. Furthermore, for example, it has become possible to find something that breaks after being used for several tens of hours. For this reason, the effect of this space 11 cannot be ignored.

  As a technique for electroless plating, Patent Document 2 describes that pretreatment with an aqueous palladium solution is performed before electroless nickel plating is performed on the surface of aluminum which is an input / output terminal of a semiconductor chip. However, there is no description relating to electroless plating on copper wiring.

JP 2001-230220 A (paragraphs 0012 to 0015) JP 7-183327 A (paragraph 0020)

  The present invention has been made based on such circumstances, and its purpose is that the surface of the copper wiring is etched when the surface of the copper wiring embedded in the recess formed in the insulating film is plated with palladium. It is an object of the present invention to provide a method for manufacturing a semiconductor device capable of manufacturing a semiconductor device capable of suppressing the above and maintaining good electrical characteristics over a long period of time.

  The method of manufacturing a semiconductor device of the present invention includes a step of etching a dielectric film to form a recess, a step of embedding copper in the recess to form a copper wiring, and dissolving palladium in an organic acid solution having a carboxyl group. And a step of performing palladium displacement plating on the copper surface embedded in the recess using a displacement plating solution and a step of forming an adhesion layer on the surface of the copper subjected to palladium displacement plating using an electroless plating solution. It is characterized by that. Examples of the copper surface embedded in the recess include the surface of a copper wiring having a damascene structure.

  The organic acid solution may contain at least one of malic acid or malonic acid, for example. In addition, a barrier material containing a metal different from copper may be interposed between the copper wiring and the insulating film.

  According to the present invention, since the surface of the copper wiring is subjected to palladium displacement plating using a displacement plating solution in which palladium is dissolved in an organic acid solution having a carboxyl group, the organic acid has a low oxidizing power. Copper is less likely to be etched at the surface of the copper wiring, particularly at the interface with the barrier material, during plating. For this reason, a space is hardly formed between the barrier material and the copper wiring, and as a result, a semiconductor device including a copper wiring capable of maintaining good electrical characteristics over a long period can be manufactured.

  Furthermore, according to the present invention, by selecting an organic acid having a carboxyl group, for example, even if a natural oxide film is formed on the surface of the copper wiring before the palladium substitution plating, this oxidation is performed without dissolving copper. The film can be removed. For this reason, palladium can be deposited uniformly on the upper surface of the copper wiring, and as a result, an adhesive layer having high adhesion can be uniformly formed on the surface of the copper wiring by utilizing the catalytic action of palladium. For this reason, since it is suppressed that copper diffuses in a board | substrate, a favorable electrical property can be maintained more reliably over a long period of time.

A method for manufacturing a semiconductor device according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2 are cross-sectional views of the surface portion of the semiconductor device. First, a substrate to be processed such as a semiconductor wafer (hereinafter referred to as “wafer”) W on which a semiconductor device is formed will be described. For example, as shown in FIG. A silicon nitride film (SiN) 22 having a thickness of 400 mm, for example, is formed as an etch stopper layer on the upper surface of the underlying insulating film such as a silicon oxide film (SiO ₂ ) 20, and the next stage having a thickness of 700 mm, for example, is further formed on the upper surface. An insulating film such as a SiOC film (carbon-containing silicon oxide film) 21 is laminated.

Here, an example of a method for forming the silicon oxide film 20, the SiOC film 21, and the SiN film 22 will be described. All of these films are plasma film forming processes, specifically, in a vacuum vessel in which the wafer W is evacuated. Then, a film can be formed by converting the predetermined film forming gas supplied into the vacuum vessel into plasma.

For such a wafer W, first, the SiOC film 21 is etched into a predetermined pattern using, for example, CF ₄ gas or C ₄ F ₈ gas as an etching gas. At this time, the underlying SiN film 22 functions as an etching stopper. Thereby, for example, as shown in FIG. 1B, a recess (contact hole) 200 having a line width of 64 nm or less, particularly 45 nm or less, for embedding copper for wiring in the SiOC film 21 is formed.

  Subsequently, for example, as shown in FIG. 1C, the surface of the SiOC film 21 including the recess 200 is covered with a barrier material (barrier metal) 24 such as tantalum nitride or titanium nitride. Subsequently, after embedding copper in the recess 200 by, for example, sputtering, for example, by performing CMP polishing to supply free abrasive grains to the surface and chemically polish, for example, as shown in FIG. Copper other than the recess 200 and the barrier material 24 are removed, and the copper wiring 25 is formed in the recess 200.

  Subsequently, the wafer W is supplied with a replacement plating solution obtained by dissolving palladium in an organic acid solution containing at least one of a carboxyl group-containing organic acid such as malic acid or malonic acid, such as an organic acid aqueous solution. Then, palladium is selectively deposited on the upper surface of the copper wiring 25 without being deposited on the SiOC film 21 and the barrier material 24, thereby forming a palladium film 26 (palladium displacement plating). Here, the displacement plating solution used for palladium displacement plating will be described. For example, a predetermined amount of an organic acid is added to a solvent such as water to obtain an organic acid aqueous solution, and the temperature of the organic acid aqueous solution is adjusted to 60 ° C., for example. However, it is possible to use a powder prepared by adding and dissolving powdery palladium sulfate, for example, at 0.1 g / liter. When the concentration of the organic acid is increased, the reaction that forms a complex by reacting with palladium is promoted and the precipitation of palladium is suppressed. Therefore, the concentration is set such that the complex formation reaction is not promoted, for example, 15 to 25 g / liter. Is preferred.

  Such a replacement plating solution is temperature-controlled at a predetermined temperature, for example, a temperature selected within a range from room temperature to 60 ° C., and is supplied to the surface of the wafer W, for example, temperature-controlled to the same temperature as the plating solution. . Thus, for example, as schematically shown in FIG. 3, copper having a low redox potential in relation to copper and palladium at the interface between the copper wiring 25 and the displacement plating solution is palladium having a high redox potential. Electrons are transferred to and dissolved, and palladium receiving the electrons is deposited on the surface of the copper wiring 25. At this time, when a natural oxide film (copper oxide) is formed on the surface of the copper wiring 25, it is dissolved by the presence of a carboxyl group. That is, using the difference in ionization tendency between copper and palladium, palladium substitution plating is selectively performed on the surface of the copper wiring 25 to form, for example, a palladium film 26 having a film thickness of 10 mm. The surface of the wiring 25 is activated by the catalyst. In addition, palladium substitution should just deposit the quantity which acts as a catalyst for forming the contact | adherence layer mentioned later, In this example, although the word the palladium film | membrane 26 is used for convenience, the upper surface of the copper wiring 25 is actually used. Even if a film covering the whole is not formed, an amount acting as a catalyst may be deposited.

  Subsequently, after cleaning is performed by supplying a cleaning liquid such as pure water to the surface of the wafer W, a predetermined electroless plating solution for forming an adhesion layer (adhesion film) is formed on the surface of the wafer W (for convenience of explanation, the following “ In the above process, palladium deposited on the surface acts as a catalyst to selectively form phosphorus (P) on the surface of the copper wiring 25, for example, NiWP. An adhesion layer 27 having a thickness of 100 to 200 mm, such as NiP, CoP, or CoWP, is formed. As the treatment liquid, a metal salt containing a component that forms the adhesion layer 27 (first metal salt and second metal salt in the case of an alloy), so that metal ions do not precipitate as hydroxide under strong alkalinity. A complexing agent for complexing metal, a reducing agent for catalytically reducing and precipitating metal ions, and a pH adjusting agent for adjusting the pH of the liquid. Depending on the type of adhesion layer 27 to be formed, at least one of the components listed below is selected as a metal salt, complexing agent, reducing agent and pH adjuster, and a solvent such as pure water is used. It is prepared by adding at a predetermined ratio.

That is, for example, cobalt sulfate, cobalt chloride, nickel sulfate, nickel chloride can be selected as the first metal salt, and for example, tungstic acid, sodium tungstate, and ammonium tungstate can be selected as the second metal salt. For example, citric acid, sodium citrate, reducing agent such as hypophosphorous acid, sodium hypophosphite, ammonium hypophosphite, pH adjusting agent, sodium hydroxide, TMAH (tetramethylammonium hydroxide) can be selected it can. Note that the listed components are examples, and these components are not necessarily used. Further, a stabilizer such as boric acid, carbonic acid, or oxycarboxylic acid may be added to suppress the change in pH when the reduction reaction proceeds. Furthermore, additives such as thiosulfuric acid and 2-MBT for promoting or suppressing the deposition of the plating film and modifying the plating film may be added. Furthermore, a surfactant such as polyalkylene glycol or polyethylene glycol may be added to reduce the surface tension of the solution so that the plating solution is uniformly disposed on the surface of the wafer W.

  Such a processing liquid is adjusted to a predetermined temperature, for example, a temperature selected within a range of 60 to 90 ° C., and supplied to the surface of the wafer W adjusted to the same temperature as the processing liquid, for example. Palladium acts as a catalyst on the surface of the copper wiring 25 substituted with palladium, and a predetermined metal ion in the liquid is deposited to form an adhesion layer 27 having a thickness of, for example, 100 to 200 mm.

  Thereafter, the wafer W is cleaned using a cleaning liquid such as pure water and further dried, and then, for example, a silicon nitride film 28 is formed on the surface of the wafer W using the above-described method (FIG. 2C). A next-stage insulating film such as a SiOC film 21 is formed on the upper surface (FIG. 2D). The processing described above is performed on the SiOC film 21 in substantially the same manner, thereby forming the next-stage copper wiring.

  According to the above-described embodiment, for example, palladium sulfate is dissolved in an organic acid solution having a carboxyl group to prepare a replacement plating solution, and this replacement plating solution is supplied to the surface of the wafer W to perform palladium replacement. As a result, since the organic acid has a small oxidizing power, for example, even when copper contacts the barrier material 24 (a different metal depending on the type of the barrier material), the copper is less likely to dissolve due to crevice corrosion at the interface during displacement plating. For this reason, a space (corresponding to the space 11) is rarely formed between the barrier material 24 and the copper wiring 25. As a result, the copper wiring 25 capable of maintaining good electrical characteristics over a long period of time is provided. A semiconductor device can be manufactured.

  Furthermore, according to the above-described embodiment, by selecting an organic acid having a carboxyl group, such as malic acid or malonic acid, this carboxyl group has an action of dissolving copper oxide. Even if the wafer W before being exposed to an atmosphere containing oxygen and a natural oxide film is formed on the upper surface of the copper wiring 25, the copper oxide may be dissolved and removed without dissolving the copper during substitution plating. it can. As described above, displacement plating is performed using the difference in ionization tendency between copper and palladium. Therefore, if the surface is covered with copper oxide, the exchange of electrons between copper and palladium is suppressed. As a result, the precipitation of palladium may not proceed. Therefore, by removing the copper oxide with the carboxyl group contained in the displacement plating solution as in this example, the substitution reaction proceeds to favorably deposit palladium on the surface of copper, which is a highly oxidizable metal. It is extremely effective in that it can be done. In other words, it is possible to simplify the means and management for preventing the natural oxide film from being formed on the wafer W without being exposed to, for example, an atmosphere containing oxygen.

  That is, as described above, when a wiring is formed by embedding a metal in the recess 200 formed in the SiOC film 21, the surface of the recess 200 is covered with the barrier material 24 and then the metal is embedded, so that replacement plating is performed. Different types of dissimilar metals of the wiring metal and the barrier material 24 are in contact with the surface of the wafer W. In addition to this, it is necessary to select an acid that can dissolve palladium in order to prepare a palladium-containing solution (when the present inventors select oxalic acid, it dissolves once, but after time passes, It is confirmed that palladium is deposited on the surface of the barrier material 24), and copper at the interface with the barrier material 24 is easily corroded.

  In other words, when performing palladium displacement plating on copper wiring, paying attention to the trade-off problem of suppressing copper etching and stably dissolving palladium, palladium dissolves but copper does not dissolve The present invention in which an organic acid is selected is extremely effective as a technique for maintaining good electrical characteristics over a long period of time.

As described above, it is possible to suppress the etching of the copper wiring by selecting an organic acid solution having a low oxidizing power as a solvent for palladium. However, the replacement plating solution should not contain hydrochloric acid or sulfuric acid at all. If the base of the solution is an organic acid, the effect of the present invention can be obtained even if it contains trace amounts of hydrochloric acid and sulfuric acid as additives. Therefore, this case is also included in the technical scope of the present invention.

  Finally, an example of an apparatus used for the process of performing palladium displacement plating on the surface of the copper wiring and the process of forming the adhesion layer 27 by electroless plating in the above manufacturing process will be described with reference to FIG. . However, this does not limit the present invention. In the figure, reference numeral 3 denotes a wafer chuck that forms a substrate support portion having a plurality of support tongues 30 for horizontally supporting the peripheral portion of the wafer W as a semiconductor device from the back surface side. The central portion of the bottom plate of the wafer chuck 3 is connected to a rotation drive unit, for example, a hollow motor 32 via, for example, a cylindrical rotation shaft 31. The substrate chuck 3 supports the wafer W by the hollow motor 32 and rotates around the vertical axis. It is configured to be rotatable.

  In an inner region surrounded by the plurality of support tongues 30 of the wafer chuck 3, for example, a temperature adjustment plate 33 having substantially the same size as the wafer W is provided so as to be movable up and down, facing the back surface of the wafer W through a gap. It has been. The temperature control plate 33 includes heating means (not shown) such as a heater inside. Further, the central portion of the back surface side is supported by, for example, a tubular support member 34 that is suspended, and the lower side of the support member 34 is connected to an elevator unit (not shown) for raising and lowering the temperature adjustment plate 33. A temperature adjustment liquid for adjusting the wafer W to a predetermined temperature by supplying it to the back surface of the wafer W, for example, a small diameter for discharging temperature-controlled pure water, is provided at the center of the front surface of the temperature control plate 33. A discharge port 35 is formed. The discharge port 35 is connected to a temperature adjusting liquid supply source 38 via a liquid flow path 36 which is an internal space of the tubular support member 34 and a liquid supply path 37 connected to the liquid flow path 36, for example, a pipe. In the middle of the liquid supply path 37, a flow rate adjusting unit and a valve (not shown) are provided.

  A liquid receiving cup body 4 is provided so as to be able to move up and down so as to surround the side of the wafer W supported by the wafer chuck 3, and the liquid spilled from the wafer W is discharged to the bottom of the cup body 4 as a drain. A drain outlet 41 is provided for this purpose. In addition, although illustration is abbreviate | omitted, the housing | casing which makes | forms an apparatus exterior body is provided so that the circumference | surroundings of the said cup body 4 may be enclosed, and in order to suppress that copper oxidizes in this housing | casing, it fills with inert gas. It is configured as follows.

  The upper surface side of the wafer W supported by the wafer chuck 3 is opposed to the surface of the wafer W with a gap within a range of, for example, 0.1 to 2 mm, and is the same as or more than the wafer W. A large liquid supply plate 5 is provided to be movable up and down. The liquid supply plate 5 includes heating means (not shown) such as a heater. A plurality of ejection holes 51 for supplying either the processing liquid or the cleaning liquid to the surface of the wafer W are uniformly formed in the surface of the liquid supply plate 5. The liquid supply plate 5 is provided with a liquid storage section (not shown) for supplying the processing liquid and the cleaning liquid to the discharge holes 51, and a liquid supply path 52, for example, one end of a pipe is connected to the liquid storage section. The other end side of the liquid supply path 52 is connected to a processing liquid supply source 53 and a cleaning liquid supply source 54, respectively, and a flow rate adjusting unit and a valve (not shown) are provided in the middle thereof. In the figure, reference numeral 55 denotes a three-way valve operated by a switching unit, for example, a control unit (not shown) for switching the flow path of the processing liquid and the cleaning liquid.

  More specifically, the upper surface side of the wafer W is formed to have a length more than half of the width of the wafer W, that is, a length longer than the radius, for supplying the above-described displacement plating solution to the surface of the wafer W. A liquid supply nozzle 6 having a slit-like discharge port 60 is provided to be movable up and down and back and forth. The liquid supply nozzle 6 is connected to a replacement plating solution supply source 62 through a supply path 61, for example, a pipe, and a flow rate adjusting unit and a valve (not shown) are provided in the middle thereof.

  Further, on the upper surface side of the wafer W, for example, a length of more than half of the width of the wafer W for supplying a drying gas, for example, an inert gas such as nitrogen whose temperature and humidity are adjusted, to the surface of the wafer W; That is, the gas supply nozzle 70 having the slit-like discharge port 70 formed with a length longer than the radius is provided so as to be movable up and down and back and forth. The gas supply nozzle 7 is connected to a gas supply source 72 for drying via a supply path 71 such as a pipe, and a flow rate adjusting unit and a valve (not shown) are provided in the middle of the gas supply nozzle 7.

  A procedure for forming the palladium layer 26 and the adhesion layer 27 on the surface of the wafer W using the above-described semiconductor device manufacturing apparatus will be described. First, in a state where the liquid supply plate 5 is set at the raised position and the cup body 4 is set at the lowered position so as not to interfere with the wafer W carried in / out from the outside of the apparatus by a substrate transfer arm (not shown), for example, FIG. d) The described wafer W is loaded, transferred to the wafer chuck 3 and held in a horizontal position.

  While the substrate transfer means that delivered the wafer W moves backward, the cup body 4 is set at the raised position (position shown in FIG. 4), and the temperature control plate 33 heated to a predetermined temperature by the internal heater is the wafer W. For example, the temperature adjustment liquid adjusted to a predetermined temperature is discharged from the discharge port 35 formed on the surface thereof toward the back surface of the wafer W. Discharge. The temperature adjusting liquid supplied to the back surface of the wafer W spreads from the center to the outside through the gap between the wafer W and the temperature adjusting plate 33, and the temperature adjusting liquid spreads over the entire back surface. Is adjusted to a predetermined temperature, for example, a temperature selected from a room temperature to 60 ° C.

  Subsequently, for example, after supplying pure water to the surface of the wafer W as necessary, the liquid supply nozzle is set so that the projection region of the slit-like discharge port 60 is set at, for example, a position extending from the center of the wafer W to the outer edge. 6, while the displacement plating solution adjusted to a predetermined temperature, for example, the same temperature as the wafer W is discharged from the discharge port 60 toward the surface of the wafer W at a predetermined flow rate, the wafer W is moved vertically by the hollow motor 32. Rotate around at least one turn. As a result, the replacement plating solution is supplied to the entire surface of the wafer W, and a liquid film (paddle) of the replacement plating solution having a thickness of 2 mm, for example, is formed by surface tension. While the liquid supply nozzle 6 that has stopped discharging is retracted, the substitutional plating reaction of copper and palladium proceeds as described above in detail by holding the state in which the displacement plating solution is accumulated on the surface for a predetermined time, for example, 30 seconds. Thus, the palladium layer 26 is formed on the upper surface of the copper wiring 25.

  Thereafter, for example, the liquid supply plate 5 heated to a predetermined temperature by an internal heater is lowered to the predetermined height position, and the cleaning liquid adjusted to a predetermined temperature, for example, 60 to 90 ° C. is discharged through the discharge holes 51 to the wafer. By supplying toward W, the displacement plating solution is removed from the surface of the wafer W. At the same time, by changing the temperature of the temperature adjustment liquid from the discharge port 35 of the temperature adjustment plate 33 to set the wafer W to a predetermined temperature in electroless plating, for example, 60 to 90 ° C., the temperature of the wafer W is set to the temperature. adjust.

  Subsequently, by switching the liquid discharged from the discharge hole 51 of the liquid supply plate 5 from the cleaning liquid to the processing liquid, the cleaning liquid on the surface of the wafer W is replaced with the processing liquid, and in the gap between the wafer W and the liquid supply plate 5. Is filled with the treatment liquid by surface tension. Then, by holding the state where the treatment liquid is accumulated on the surface for a predetermined time, for example, 60 seconds, the electroless plating reaction proceeds by the catalytic action of palladium as described above in detail, and the adhesion layer is formed on the upper surface of the copper wiring 25. 27 is formed.

  After that, the liquid discharged from the discharge holes 51 is switched again to the cleaning liquid, and the processing liquid is removed from the surface of the wafer W and cleaned. Subsequently, the gas supply nozzle 7 is disposed so that the projection area of the slit-like discharge port 70 is set, for example, at a position extending from the center of the wafer W to the outer edge, and drying with temperature and humidity adjusted from the discharge port 70. While discharging the working gas, the hollow motor 32 rotates the substrate 2 around the vertical axis at a high speed to perform spin drying to shake off the liquid, thereby drying the wafer W. The dried wafer W (this wafer W corresponds to that shown in FIG. 2B) is unloaded from the apparatus by a substrate transfer arm (not shown) and transferred to the apparatus for performing the next process.

Examples carried out to confirm the effects of the present invention will be described below.
Example 1
This example is an example in which after performing palladium displacement plating using the above displacement plating solution, washing with water, supplying a treatment solution, and forming an adhesion layer 27 by electroless plating to obtain a semiconductor device. . Detailed test conditions are listed below. The results of imaging the surface of the wafer W after the palladium displacement plating and after the formation of the adhesion layer 27 by SEM are shown in FIGS. 5 and 6, respectively.

1. Palladium displacement plating ・ Plating solution Malic acid; 20 g / liter Palladium sulfate; 1 g / liter ・ Processing temperature: 60 ° C.
Processing time: 30 seconds Electroless plating ・ Composition of treatment solution (cobalt sulfate, tungstic acid, citric acid, hypophosphorous acid, TMAH)
・ Processing temperature: 60 ℃
・ Processing time: 60 seconds

(Comparative Example 1)
This example is a comparative example in which a semiconductor device was obtained by performing the same process as in Example 1 except that a sulfuric acid solution of palladium was used as the displacement plating solution. Detailed conditions of the plating solution are listed below. The imaging results of the surface of the wafer W after the palladium substitution plating and after the formation of the adhesion layer 27 are shown in FIGS. 7 and 8, respectively.

・ Plating solution composition Sulfuric acid; 4.8% sulfuric acid in appropriate amount Palladium sulfate; 1 g / liter

(Results and discussion of Example 1 and Comparative Example 1)
As is clear from the image results shown in FIGS. 5 and 7, in Example 1, the copper wiring 25 after palladium substitution plating was not etched, and no space was formed at the interface with the barrier material 24. On the other hand, in Comparative Example 1, the upper side surface of the copper wiring 25 is etched to form a space between the barrier material 24 and the upper surface. As is apparent from the results shown in FIGS. 6 and 8, if a space is formed during displacement plating, the space remains unfilled even if the adhesion layer 27 is formed. That is, if a displacement plating solution in which palladium is dissolved in malic acid is used, the copper wiring is prevented from being etched during palladium displacement plating, and a space is formed between the barrier material 24 and the barrier material 24. It was confirmed that there was no or very little if any.

(Example 2)
In this example, in order to confirm the action of the carboxyl group, the substitution plating solution of Example 1 was supplied to the wafer W that was exposed to the air atmosphere and had a natural oxide film formed on the surface. As a result, it was confirmed that the copper film was not etched on the surface of the copper wiring 25 after the treatment, but the oxide film was removed. That is, it was confirmed that if an organic acid having a carboxyl group is selected, even if there is an oxide film on the surface of the copper wiring 25, it can be removed and palladium can be deposited.

It is explanatory drawing which shows the mode of the wafer processed with the manufacturing method of the semiconductor device of this invention. It is explanatory drawing which shows the mode of the wafer processed with the manufacturing method of the semiconductor device of this invention. It is explanatory drawing which shows the mode of the surface of the wafer by which displacement plating is carried out. It is a longitudinal cross-sectional view which shows the apparatus used for the manufacturing method of the said semiconductor device. It is a characteristic view which shows the Example performed in order to confirm the effect of this invention. It is a characteristic view which shows the Example performed in order to confirm the effect of this invention. It is a characteristic view which shows the Example performed in order to confirm the effect of this invention. It is a characteristic view which shows the Example performed in order to confirm the effect of this invention. It is explanatory drawing which shows a mode that the space was formed between copper wiring and barrier material. It is explanatory drawing which shows the mode of the copper wiring which carried out displacement plating using the hydrochloric acid solution of palladium.

Explanation of symbols

W wafer 21 SiOC film 24 Barrier material 25 Copper wiring 26 Palladium film 27 Adhesion layer

Claims (3)

Etching the insulating film to form a recess;
Forming copper wiring by embedding copper in the recess;
A step of performing palladium displacement plating on the surface of copper embedded in the recess using a displacement plating solution obtained by dissolving palladium in an organic acid solution having a carboxyl group;
Forming an adhesion layer on the surface of the palladium-plated copper using an electroless plating solution.   The method of manufacturing a semiconductor device according to claim 1, wherein the organic acid solution contains at least one of malic acid and malonic acid.   3. The method of manufacturing a semiconductor device according to claim 1, wherein a barrier material including a metal different from copper is interposed between the copper wiring and the insulating film.

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