CN1769520A

CN1769520A - Electroless plating apparatus and method

Info

Publication number: CN1769520A
Application number: CNA200510109236XA
Authority: CN
Inventors: 定免美保; 原谦一
Original assignee: Tokyo Electron Ltd
Current assignee: Tokyo Electron Ltd
Priority date: 2004-10-15
Filing date: 2005-10-17
Publication date: 2006-05-10
Also published as: US20060081461A1; KR100751102B1; JP2006111938A; KR20060052152A

Abstract

An electroless plating solution includes a first liquid chemical containing a metal salt and a second liquid chemical containing a reducing agent. In respective liquid chemical supply lines, liquid chemical opening/closing units are installed in the vicinity of a junction therebetween, and at the same time, a plating solution opening/closing unit is provided in the vicinity of an discharge opening in supply line of an electroless plating solution after the first and the second liquid chemical are joined together. A plating solution in the supply line disposed between these opening/closing units corresponds to a discharge amount needed for a plating processing of about one time. Further, both of the liquid chemicals are mixed together only during the time period between the time when a plating processing on one substrate has been started and the time when a plaiting processing is to start on a following substrate.

Description

Electroless plating apparatus and method

Technical Field

The present invention relates to an electroless plating apparatus and method for plating a surface of a substrate, for example, a surface of a wiring metal of a semiconductor substrate, by supplying a plating solution onto the substrate.

Background

A multilayered structure of a semiconductor device is constituted by laminating a plurality of layers in which wiring is embedded in an interlayer insulating film. As a method for forming the wiring, a damascene process (damascone process) is used in which a recess including a trench in an interlayer insulating film is formed, copper is embedded in the recess, and then the remaining copper is polished by a polishing method called CMP.

There has recently been a study of the possibility of incorporating electroless plating in the implementation of such copper wiring techniques. Electroless plating is a method of forming a metal film by obtaining electrons from a reducing agent added to a plating solution without using electrolysis from the outside, and is applied to a technique of forming a seed layer (seed layer) of copper in a recessed portion before embedding copper in the recessed portion, a technique of forming a plating film made of CoWP (cobalt tungsten phosphorus) or the like as an adhesion layer of a barrier film and copper before forming the barrier film (for example, a film of silicon nitride, silicon carbide, silicon carbonitride or the like) on a copper wiring, and the like.

As for electroless plating, for example, a method is disclosed in which a semiconductor wafer (hereinafter referred to as a wafer) held by a jig at its peripheral edge is heated from both upper and lower surfaces by a temperature control plate, and an electroless plating solution is heated to a predetermined temperature, for example, a set temperature within a range from room temperature to 60 ℃, and supplied to the surface of the wafer through an upper side plate (patent document 1).

However, since the electroless plating solution contains a reducing agent as an electron supply source, metal deposition, so-called precipitation deposition, in the solution is likely to occur particularly when the solution is heated. The occurrence of precipitation changes the state of the electroless plating solution, and thus the electroless plating treatment performed between wafers also changes, and for example, the film thickness of the plating film becomes uneven, and the precipitated particles may contaminate particles and cause clogging of piping of the electroless plating apparatus. Patent document 1 has no description of such instability without an electrolyte.

[ patent document 1 ] Japanese patent laid-open No. 2004-107747 (FIG. 1 and paragraph 0026)

Disclosure of Invention

Since a reducing agent as an electron supply source is contained in the electroless plating solution and a metal precipitates in the solution to form an unstable state, particularly a heated state in the electroless plating process such as a semiconductor device manufacturing process, the present invention provides an electroless plating apparatus and method capable of stabilizing the state of the electroless plating solution and stably performing plating treatment on the surface of a substrate, based on the above-mentioned circumstances,

the electroless plating apparatus of the present invention comprises:

a substrate holding section for holding the substrate in a lateral direction;

a first chemical liquid supply tube for supplying a first chemical liquid;

a first chemical liquid supply source connected to an upstream end of the first chemical liquid supply tube;

a first chemical liquid switching unit disposed near a downstream end of the first chemical liquid supply tube and controlling a flow rate of the first chemical liquid;

a second chemical liquid supply tube for supplying a second chemical liquid;

a second chemical liquid supply source connected to an upstream end of the second chemical liquid supply tube;

a first chemical liquid switching unit disposed near the downstream end of the second chemical liquid supply tube and controlling the flow rate of the second chemical liquid;

an electroless plating solution supply tube connected to downstream ends of the first and second chemical solution supply tubes for supplying an electroless plating solution formed by mixing the first and second chemical solutions to the upper surface of the substrate and supplying the electroless plating solution to the upper surface of the substrate;

a supply pipe temperature adjusting unit for adjusting the temperature of the plating solution in the electroless plating solution supply pipe;

a plating solution switching unit disposed in the vicinity of a downstream end of the electroless plating solution supply pipe serving as a discharge port and controlling a flow rate of the electroless plating solution; and

a control unit for controlling the first chemical liquid switch unit, the second chemical liquid switch unit and the plating liquid switch unit to supply the electroless plating liquid to the upper surface of the substrate,

wherein,

the volume of the electroless plating solution supply pipe surrounding the first chemical solution switch cell, the second chemical solution switch cell, and the plating solution switch cell satisfies a discharge amount required for performing an electroless plating process on one substrate.

Here, the first and second chemical solution switch units may be used as one chemical solution switch unit. The electroless plating apparatus may further include flow rate adjusting units for adjusting flow rates of the first and second chemical solutions.

The present invention mixes the first chemical liquid and the second chemical liquid as much as possible before performing the electroless plating process, and controls the amount of the chemical liquid used as much as possible, based on the following viewpoints: after the treatment of one substrate is started and the process is shifted to the next substrate, the two chemical solutions are mixed, and the mixed solution (electroless plating solution) is completely used up in the next substrate treatment. Therefore, the liquid chemical switching units provided in the vicinity of the confluence point of the first liquid chemical supply tube and the second liquid chemical supply tube are as close as possible to the confluence point of the two liquid chemical supply tubes within the allowable range of the component structure. When the distance between the confluence point and each chemical solution switch cell is large, the mixture of the two chemical solutions fills the gap as the chemical solutions are diffused, but the mixing action occurs in a static state after the chemical solution switch cells are closed, so that the two mixed solutions are not sufficiently mixed and supplied to the substrate, and the uniformity of electroless plating is reduced. Therefore, in other words, even if each of the chemical solution switch cells is spaced apart from the confluence point in view of restrictions on the configuration and arrangement of the components, it is "in the vicinity of the confluence point" as long as it is within a range in which non-uniformity of electroless plating due to insufficient mixing is not caused.

Further, the meaning of "the volume (V1) in the supply pipe between the chemical solution switch cell and the plating liquid switch cell corresponds to the discharge amount (V2) required for performing the electroless plating process on one substrate" is V1 and V2. V2 is the sum of the volume of the liquid contained in the surface and the volume from the plating liquid switch cell to the discharge port, for example, for electroless plating of the surface of the substrate. The relationship between V1 and V2 will be described below, and when V1 is larger than V2, the solution remaining in the tube for supplying the electroless plating solution is discharged as V2, and when the discharge amount is V1, the solution is discharged in excess of the required amount, which results in waste of the chemical solution. On the other hand, if V1 is smaller than V2, the first chemical solution and the second chemical solution respectively located in the two chemical solution supply pipes are discharged as V2, and therefore, the uniformity of the plating liquid on the substrate is lowered. Thus, it is desirable that V1 and V2 are equal to each other, but there are cases where a difference in design occurs to some extent. Even in this case, V1 and V2 are "identical" as long as the uniformity of the electroless plating process is ensured, and in addition, the design concept of minimizing the waste of the chemical solution is considered.

As one of preferred embodiments of the present invention, there is provided a battery pack comprising: an upper temperature control member facing the substrate surface held by the substrate holding portion, having an effective area larger than that of the substrate, and having the discharge port formed on a lower surface thereof; and a moving mechanism for relatively moving the upper temperature control member between a treatment position for filling the electroless plating solution between the substrate surfaces and a standby position spaced apart from the treatment position. In this case, the upper temperature control member has a circulation chamber containing a temperature control liquid, and the entire electroless plating solution supply pipe is disposed in the circulation chamber of the temperature control member, whereby the supply pipe temperature control unit can control the temperature of the electroless plating solution by heat exchange between the temperature control liquid and the electroless plating solution. The first and second chemical liquid supply pipes are filled with the chemical liquid to be supplied to the electroless plating liquid supply pipe, and the portions are also provided in the circulation chamber of the temperature control member. In this case, part or all of the supply pipe for the electroless plating solution is disposed in the upper temperature-regulating body, and part or all of the supply pipe temperature-regulating unit is also used as the upper temperature-regulating body.

The upper temperature control member is configured as a circulation chamber for a temperature control liquid, and the supply pipe temperature control means can be used by arranging all the supply pipes for the electroless plating liquid in the circulation chamber for exchanging heat between the electroless plating liquid and the temperature control liquid.

Further, in the present invention, the first and second chemical liquid supply pipes are also provided with a temperature adjusting unit for adjusting the temperature of the portion filled with the chemical liquid to be supplied to the electroless plating supply pipe. When the inside of the temperature control body is configured as a circulation chamber for the temperature control fluid, the circulation chamber may be used as a means for temperature control of a portion filled with the chemical solution.

In the electroless plating supply tube of the present invention, a lower temperature adjusting body is disposed, and the electroless plating supply tube is provided with a substrate temperature adjusting unit which is disposed to face the lower surface of the substrate and adjusts the temperature of the substrate. Here, it is preferable that the substrate temperature adjusting unit adjusts the temperature by a liquid filled between the lower temperature adjusting body and the substrate, the liquid temperature having been adjusted by the lower temperature adjusting body.

In another aspect of the present invention, there is provided an electroless plating method using the electroless plating apparatus of the present invention, wherein the first chemical liquid is a solution containing a metal salt of a plating metal, and the second chemical liquid is a solution containing a reducing agent as an electron supply source.

In a third aspect of the present invention, there is provided an electroless plating method using the electroless plating apparatus of the present invention, wherein the switching operations of the switch unit for the first chemical liquid, the switch unit for the second chemical liquid, and the plating solution switching power supply are simultaneously completed.

In a fourth aspect of the present invention, there is provided an electroless plating method using the electroless plating apparatus of the present invention, wherein the supply tube temperature adjuster and the upper temperature adjuster are temperature-adjusted at a temperature in the plating process.

In a fifth aspect of the present invention, there is provided an electroless plating method using the electroless plating apparatus of the present invention, wherein the temperature of the supply pipe temperature adjuster and the temperature adjusters provided on the first and second chemical liquid supply pipes adjust the temperature at the plating process.

In a sixth aspect of the present invention, there is provided an electroless plating method using the electroless plating apparatus of the present invention, wherein the supply tube temperature adjuster and the substrate temperature adjuster are adjusted in temperature in the plating step.

In the present invention, the chemical solution opening and closing means is provided in the vicinity of the confluence point of the first and second chemical solution supply pipes, and the plating solution opening and closing means is provided in the vicinity of the discharge port of the electroless plating solution supply pipe, wherein the volume of the supply pipe interposed between these valves is approximately equal to the discharge amount necessary for one plating process. Further, after the start of the plating process on the substrate, the two chemical solutions can be mixed only before the start of the electroless plating process on the next substrate next to the substrate, that is, before the start of the electroless plating process, so that the electroless plating solution can be prevented from being kept in an unstable state as much as possible, and precipitation, for example, can be prevented. The result is: in general, an electroless plating solution in the same state can be supplied to a substrate to perform stable electroless plating, thereby improving uniformity of film thickness and film quality between substrates.

Drawings

The objects and features of the present invention will be more clearly described by describing preferred embodiments of the present invention based on the following drawings.

FIG. 1 is a longitudinal sectional side view showing the entire configuration of an electroless plating apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram showing important parts of the electroless plating apparatus.

FIGS. 3(a) to 3(c) are explanatory views showing the surface structure of a wafer used for electroless plating.

FIGS. 4(a) and 4(b) are explanatory views showing a state in which a wafer is processed by the above-mentioned electroless plating apparatus in stages.

FIGS. 5(a) and 5(b) are explanatory views showing a state in which a wafer is processed by the above-mentioned electroless plating apparatus in stages.

FIGS. 6(a) and 6(b) are explanatory views showing a state in which a wafer is processed by the above-mentioned electroless plating apparatus in stages.

Fig. 7(a) and 7(b) are schematic side views showing modifications of the structure in the vicinity of the confluence point of the first chemical liquid supply tube and the second chemical liquid supply tube in the above embodiment.

Fig. 8 is a schematic perspective view showing important parts of another embodiment of the present invention.

Fig. 9 is a longitudinal sectional side view schematically showing the inside of the upper temperature adjuster shown in fig. 8.

Description of the symbols:

11 a wafer holder; a 12-segment section; 16 a tilt mechanism; 17. 18 a nozzle; 21 a cover body; 3 an upper temperature regulator; 30 a moving mechanism; 31 a circulation chamber; 41 a supply pipe for electroless plating solution; 42 an exhaust port; 43 a valve; 5 a first chemical liquid supply tube; a 51 valve; 6 a second chemical liquid supply tube; a 61 valve; 71 a pure water supply pipe; 73 a valve; 302 copper wiring; 304 a catalyst layer composed of palladium; 305 electroless plating film

Detailed Description

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a view showing the entire configuration of an electroless plating apparatus according to an embodiment of the present invention. In fig. 1, reference numeral 11 denotes a wafer chuck 11 having a flat cylindrical substrate holding portion with an open upper portion, and a step portion 12 for holding a peripheral portion of a wafer W as a substrate is formed around the entire upper peripheral portion of the wafer chuck 11. A cylindrical rotation shaft 13 is provided in the center of the wafer 11, and a rotation driving unit such as a hollow motor 14 is connected to the rotation shaft 13. The wafer holder 11 is rotatable around a vertical axis while supporting the wafer W by the hollow motor 14. The hollow motor 14 is fixed to a base plate 15, and the base plate 15 is attached to a tilting mechanism 16 so as to be tiltable.

A liquid-receiving lid 21 is provided on the outer side of the wafer chuck 11 so as to surround the wafer chuck 11, and the lid 21 is configured to be movable up and down with respect to the base 15 by an unillustrated lifting mechanism. The upper end portion around the side surface of the lid 21 is bent inward, and when the wafer W rotates, the excess liquid is returned by back flushing. An opening 22 is formed in the center of the bottom surface of the lid 21, and a drain discharge portion 23 that penetrates the rotation shaft 13 and discharges liquid overflowing from the wafer W at a nearby portion as drain is provided in the opening 22 at the periphery of the bottom surface. A hole, not shown, is formed in the bottom surface away from the center of the wafer chuck 11 so that the liquid overflowing the wafer chuck 11 flows into the lid 21.

An upper temperature controller 3 is provided above the wafer holder 11 so as to face the surface of the wafer W held by the wafer holder 11. The upper temperature control member 3 is constituted by: the outer shape is a flat cylindrical shape having a size slightly larger than that of the wafer W, and the elevating mechanism 30 as a moving mechanism can elevate and lower the wafer W between a treatment position at which the electroless plating solution is supplied to the wafer W and a standby position slightly above the treatment position. The upper temperature controller 3 may be larger than the effective area (integrated circuit formation area) of the wafer W, but in recent years, the integrated circuit is formed as close as possible to the periphery of the wafer W, and therefore, it is preferable to be the same size as or larger than the wafer W. A lower temperature control member 24 is disposed in the wafer chuck 11, and the lower temperature control member 24 is configured to face the back surface of the wafer W held by the wafer chuck 11 and to be movable up and down by a support shaft 25 penetrating the rotary shaft 13 by an unshown lifting mechanism. The upper temperature controller 3 and the lower temperature controller 24 may be formed of a plate made of, for example, ceramic provided with a heater formed of a resistance heating body, or may be a plate through which a heat medium flows.

One end of a pure water supply pipe 26 as a supply pipe for temperature-controlled water such as pure water is inserted into the central portion of the lower surface of the lower temperature-controlling body 24, and the pure water supply pipe 26 is arranged in the support shaft 25, and the other end thereof is connected to a pure water tank 29 through a valve 27 and a valve 28. Further, the pure water can also be used as a rinse solution on the back surface side.

The elevating mechanism 30 of the upper temperature controller 3 and the elevating mechanism, not shown, of the lower temperature controller 24 are fixed to the base plate 15, and then the upper temperature controller 3, the wafer W, and the lower temperature controller 24 are tilted integrally by the tilting mechanism 16. The purpose of these inclinations is to remove the bubbles mixed in the treatment liquid such as the electroless plating liquid by moving the bubbles to the upper portion side when the space between the temperature control member 3 and the wafer W is filled with the treatment liquid as described later, but in this embodiment, the inclination mechanism 16 may not be provided because the bubbles are hard to enter.

Next, a system for supplying the electroless plating solution will be described with reference to FIG. 2. The upper temperature controller 3 has a central portion on which one end of an electroless plating solution supply pipe 41, for example, a pipe body is disposed, and a lower end of the pipe body is provided with a discharge port 42 for the electroless plating solution which is flush with the lower surface of the upper temperature controller 3. A valve 43 corresponding to a plating liquid switching valve for supplying a liquid to block the supply pipe 41 is provided on the upper side of the upper temperature control member 3 of the electroless plating liquid supply pipe 41, and the plating liquid supply pipe 41 is branched into a first chemical liquid supply pipe 5 and a second chemical liquid supply pipe 6 on the upstream side. That is, the first chemical liquid supply pipe 5 and the second chemical liquid supply pipe 6 are joined at the upstream end of the electroless plating liquid supply pipe 41. The electroless plating liquid supply pipe 41 is surrounded by a supply pipe temperature control unit 44, and the electroless plating liquid in the supply pipe 41 is set to a predetermined temperature, for example, a temperature selected from the range of room temperature to 60 ℃. In this example, the supply pipe temperature control unit 44 is configured to circulate a heat medium, such as pure water, through the cylindrical case 45 by the heat medium supply pipe 46 and the heat medium discharge pipe 47. A heater 48 constituting a part of the supply pipe temperature control unit 44 is provided around the valve 43, and the temperature of the electroless plating solution in the valve 43 can be adjusted.

The first chemical liquid supply pipe 5 and the second chemical liquid supply pipe 6 are supply pipes through which the first chemical liquid and the second chemical liquid, which are mixed with each other to form the electroless plating solution, flow, respectively, and

valves

51 and 61 as chemical liquid opening and closing means are provided in the vicinity of a confluence point (an upper end of the electroless plating solution supply pipe 41). These

valves

51 and 61 are disposed at positions as close as possible to the confluence point within the range allowed by the arrangement of the components. The reason is to uniformly diffuse and mix the chemical solution as much as possible in a standby state for the next wafer W.

The first chemical supply pipe 5 is provided with a chemical supply source 52, a pump 53, and a flow rate adjusting part 54 in this order from the upstream side, and the second chemical supply pipe 6 is provided with a chemical supply source 62, a pump 63, and a flow rate adjusting part 64 in this order from the upstream side. The first liquid medicine contains: a metal salt having a component for forming an electroless plating film; a complexing agent which complexes the metal with metal ions as a hydroxide and in a non-precipitating manner under strong alkalinity; a pH regulator for regulating the pH of the liquid.

When the film component is an alloy, the metal salt is composed of a first metal salt and a second metal salt containing the alloy component thereof. As specific examples of the components of the first chemical solution, cobalt sulfate, cobalt chloride, nickel sulfate, and nickel chloride can be selected as the first metal salt, tungstic acid and ammonium tungstate can be selected as the second metal salt, citric acid and sodium citrate can be selected as the complexing agent, and sodium hydroxide and TMAH (tetramethylammonium hydroxide) can be selected as the pH adjuster.

The second liquid medicine contains a reducing agent for catalytically reducing and precipitating metal ions and a pH regulator for regulating the pH value of the liquid. Examples of the reducing agent include DMAB (dimethylammonium borohydride), and the like. The first and second medical fluids are stored, for example, at room temperature, maintaining a pH of 10. In addition, the listed ingredients are examples, and these ingredients may not be used.

The flow rates of the first chemical solution and the second chemical solution are adjusted by the respective flow

rate adjusting portions

54 and 64 so as to have a predetermined mixing ratio, for example, a ratio of 9: 1 of the first chemical solution to the second chemical solution, and the discharge amount of the electroless plating solution for processing one wafer W is adjusted to, for example, 50 cc.

Here, the volume V1 of the electroless plating solution supply pipe 41 between the

valves

51 and 61 of the chemical solution switch cell and the valve 43 of the plating solution switch cell is designed to correspond to the discharge volume V2 (50 cc in this example) required for the electroless plating of one wafer W. The relationship between V1 and V2 will be described in detail below, and for example, the discharge amount V2 is the amount of liquid passing through the valve 43 (the amount of liquid required to process a single wafer W) when the electroless plating liquid is filled between the wafer W and the upper temperature control member 3 in a state where no liquid is present on the downstream side of the valve 43. In other words, the sum of the volume between the wafer W and the upper temperature control member 3 and the volume from the valve 43 to the discharge port 42 corresponds to the sum. In this case, since the electroless plating solution is wasted from the valve 43 to the discharge port 42, it is preferable that the valve 43 be as close to the discharge port 42 as possible, and for example, a valve of a type in which a flow path is opened and closed by a piezoelectric element is provided in the upper temperature-adjusting body 3.

A pure water supply pipe 71 as a cleaning liquid is disposed in the vicinity of the electroless plating liquid supply pipe 41 of the upper temperature control member 3, and a discharge port 72 opened to the lower surface of the upper temperature control member 3 is formed at the downstream end of the pure water supply pipe 71 and a pure water tank 73 is provided at the upstream end thereof. The downstream end of the pure water supply pipe 71 may be opened between the valve 43 and the discharge port 42 of the electroless plating liquid supply pipe 41. Reference numeral 74 denotes a pump, and 75 denotes a valve for supplying and blocking pure water from the pure water supply pipe 71. The electroless plating apparatus further includes a control unit 100 configured by a computer, for example, and the control unit 100 includes a sequence program for controlling operations of the

pumps

53, 63, and 74 and the

valves

43, 51, 61, and 75.

In fig. 1, the electroless plating apparatus includes a plurality of nozzles that are movable between a supply position and a standby position of a fluid above a wafer W held by a wafer chuck 11. In fig. 1, 2

nozzles

17, 18 are shown for convenience. For example, the nozzle 17 is connected to a supply source of the replacement plating liquid through a pipe, not shown, for supplying the replacement plating liquid to the surface of the wafer W prior to the electroless plating liquid. The nozzle 18 is used to supply a drying gas such as an inert gas, and is connected to a supply source of the drying gas through a pipe not shown. These

nozzles

17 and 18 are provided with, for example, a strip-shaped discharge port having a length equal to or greater than the radius of the wafer W, and are movable up and down by a drive mechanism, not shown, and in the lateral direction, for example, are rotatable.

Next, the operation of the above embodiment will be described. First, the upper temperature controller 3 is kept in standby at the standby position, the wafer holder 11 is lowered, the front surface of the wafer W is sucked by a transport unit (not shown), the wafer W is transported to the upper side of the wafer holder 11, the wafer holder 11 is raised, and the wafer W in the transport unit is transferred to the wafer holder 11 (fig. 1 state). As shown in fig. 3(a), the surface of the wafer W is in a state where the copper wiring 302 is embedded in a recess of the interlayer insulating film 301. Reference numeral 303 denotes a barrier film provided to prevent copper in the recess from diffusing into the insulating film 301.

Next, as shown in fig. 4(a), the pretreatment liquid is supplied onto the wafer W while the wafer W is rotated by the nozzle 17 via the wafer chuck 11, for example, to form a slurry of the pretreatment liquid. The pretreatment liquid is, for example, a substitution plating liquid for palladium substitution plating, and a solution obtained by dissolving a palladium salt composed of palladium sulfate, palladium chloride or the like in an acid solution such as sulfuric acid or hydrochloric acid can be used as the substitution plating liquid. By adjusting the temperature of the substitution plating solution to a temperature selected from, for example, room temperature to 60 ℃, and then supplying the solution to the surface of the wafer W, as shown in fig. 3(b), copper having a lower oxidation-reduction potential than palladium is transferred to palladium at the interface between the copper wiring 302 and the substitution plating solution, and a catalyst layer 304 made of palladium receiving electrons is selectively deposited on the surface of the copper wiring 302. The catalyst layer 304 is used as a catalyst for electroless plating in a subsequent step, but in some cases, the catalyst is not needed depending on the electroless plating solution, and in this case, an organic acid solution is supplied from the nozzle 17 to the wafer W for pretreatment. Thereafter, as shown in fig. 4(b), a cleaning liquid, for example, deionized water is supplied from the nozzle 18 to the wafer W while rotating the wafer W, thereby removing the pretreatment liquid.

In this way, the nozzle 18 is retracted from above the wafer W, and the upper temperature controller 3 is lowered, and the distance between the lower surface thereof and the surface of the wafer W is set to a position of, for example, 0.1mm to 2 mm. At this time, the lower temperature adjuster 24 is also raised and set at a position spaced apart from the back surface of the wafer W by a distance of 0.1mm to 2 mm. The pure water as the temperature control liquid is supplied by the pump 28 and heated to a predetermined set temperature in the lower temperature control member 24 through the pure water supply pipe 26.

The heated pure water flows into the wafer chuck 11 while filling the gap between the lower temperature adjuster 24 and the back surface of the wafer W, and flows into the cap 21 through a hole not shown. Since the upper surface of the lower temperature adjuster 24 is also maintained at the predetermined temperature, the wafer W is heated from the back surface side and maintained at the plating temperature. After the wafer W is heated for a predetermined time, for example, 10 seconds, the

pumps

53 and 63 shown in fig. 2 are driven, the

valves

43, 51, and 61 are opened simultaneously, and after the predetermined time has elapsed, the

pumps

53 and 63 are stopped, and the

valves

43, 51, and 61 are closed simultaneously. Thus, the opening and closing of the valve are performed simultaneously, and the reverse flow of the liquid medicine can be prevented. And the set time is a time required for discharging all the liquid between the

valves

43, 51 and 61 of the electroless plating liquid supply pipe 41. As a result, as shown in FIG. 5(a), the electroless plating solution is supplied into the electroless plating solution supply pipe 41 at a flow rate of, for example, 30 to 100 ml/min, and fills the space between the wafer W and the upper temperature-adjusting body 3.

When the plating liquid is supplied to a wafer W before the wafer W, the first chemical liquid and the second chemical liquid are merged by the

valves

51 and 61 from the first chemical liquid supply pipe 5 and the second chemical liquid supply pipe 6 and flow into the electroless plating liquid supply pipe 41, and are mixed by diffusion before the supply to the wafer W, thereby forming an electroless plating liquid, and the temperature of the electroless plating liquid is adjusted to a reactive state by the supply pipe temperature adjusting unit 44. The upper temperature controller 3 is also heated to, for example, the same temperature as the set temperature of the electroless plating solution, whereby the wafer W is subjected to the electroless plating process while being temperature-controlled from both the front and back surfaces. That is, in the preceding step, palladium deposited on the surface of the wafer W acts as a catalyst to cause a reaction between the electroless plating solution and copper, and as shown in fig. 3(c), an electroless plating film 305 having an adhesion layer of, for example, a film thickness of 100 to 200 , such as NiP, CoWP, NiP, CoP or the like, made of an alloy selectively containing phosphorus (P) is formed on the surface of the copper wiring 302.

Then, by this discharge of the plating liquid, the electroless plating liquid in the region sandwiched by the

valves

51, 61, and 43 of the electroless plating liquid supply pipe 41 is pushed out, and the first chemical liquid and the second chemical liquid, which are newly adjusted to the flow rate ratio of 9: 1 in the flow

rate adjustment portions

54 and 64, are respectively allowed to flow into the region through the

valves

51 and 61 in the liquid amount (V1) filling the region.

At this time, pure water serving also as cleaning water is supplied to the back surface side of the wafer W, and this pure water constitutes so-called back rinse water (back rinse) to prevent the plating liquid from returning to the back surface side of the wafer W. In addition, the wafer W is rotated by the wafer chuck 11 during the processing, and the in-plane temperature uniformity of the wafer W can be further improved. In this step, the wafer W, the upper temperature-adjusting member 3, and the lower temperature-adjusting member 24 are tilted by the tilt mechanism 16, whereby bubbles mixed in the gap can be removed from the electroless plating solution. Such processing is effective in generating gases from the reaction of the electroless plating solution with the copper, and the like.

Subsequently, the valve 75 of the pure water supply pipe 71 shown in FIG. 2 is opened, and pure water is supplied between the wafer W and the upper temperature-adjusting body 3 through the discharge port 72 as shown in FIG. 5(b), whereby the electroless plating solution on the surface of the wafer W is replaced with pure water. Then, the upper temperature controller 3 is raised, and the post-cleaning liquid is supplied to the rotating wafer W by the nozzles (18 is added when convenient) in the nozzle group represented by the

nozzles

17 and 18, and the front surface of the wafer W is cleaned as shown in fig. 6 (a). At this time, pure water is supplied as back rinse water (back rinse) to the back surface side of the wafer W. The post-cleaning is to reduce a leak current between lines, and an organic acid or a hydrofluoric acid aqueous solution may be used as the cleaning liquid. The supply of pure water after the electroless plating treatment can be performed by the nozzle 18 by raising the upper temperature adjuster 3.

Then, pure water as a cleaning liquid is supplied to the surface of the rotating wafer W from the nozzles of the nozzle group (18 is added when convenient), and thereafter, the discharge of the cleaning liquid is stopped, and the wafer W is rotated at a high speed and dried as shown in fig. 6 (b). In this case, drying can be promoted by blowing a drying gas such as an inert gas from the nozzles of the nozzle group onto the surface of the wafer W. After the series of steps is completed, the front surface of the wafer W is sucked by a transport unit, not shown, and the wafer W is carried out from the jig 11.

In the above embodiment, the

valves

51, 61 as the opening and closing means for the chemical solution are provided in the vicinity of the confluence point of the first chemical solution supply tube 5 and the second chemical solution supply tube 6, respectively, and the valve 43 as the opening and closing means for the plating solution is provided in the vicinity of the discharge port 42 of the electroless plating solution supply tube 41, and the volume of the supply tube 41 held by these

valves

43, 51, 61 corresponds to the discharge amount required for the plating process for one wafer W. Therefore, after the plating process of the wafer W is started, the two chemical solutions can be mixed only before the plating process of the next wafer W of the wafer W is started, and the time for placing the two chemical solutions in a mixed state is short, that is, the two chemical solutions are mixed before the electroless plating process is performed. Therefore, the deposition can be prevented while maintaining the electroless plating solution in an unstable state. As a result, the surface of the wafer W can be subjected to electroless plating treatment in a stable state of the electroless plating solution, and the uniformity of the film thickness and the film quality between the wafers W can be improved. Further, since there is no risk of particle deposition, particle contamination and clogging of piping cannot occur.

Further, the standby electroless plating solution is almost entirely used for the electroless plating treatment of the wafer W, and the consumption amount of the plating solution can be reduced, which contributes to the reduction of the treatment cost because the cost of the electroless plating solution is considerably high. Further, if the valves are located at a distance from the confluence point in the first chemical liquid supply pipe 5 and the second chemical liquid supply pipe 6, the two chemical liquids cannot be sufficiently mixed, but if the

valves

51 and 61 are provided near the confluence point as in the present example, the two liquids are sufficiently mixed to make the concentration of the electroless plating solution uniform, and as a result, the treatment with high in-plane or out-of-plane uniformity can be performed. If the first chemical liquid supply tube 5 and the second chemical liquid supply tube 6 are joined in a V-shape in the longitudinal direction, no liquid stays and no air bubbles are mixed.

Here, as for the chemical

liquid supply pipes

5 and 6, the second chemical liquid supply pipe 6 is thinner than the first chemical liquid supply pipe 5 as shown in fig. 7(a), and the second chemical liquid supply pipe 6 can be joined to the first chemical liquid supply pipe 5 set up vertically in an inclined structure, or the two chemical

liquid supply pipes

5 and 6 are joined in a V-shape as shown in fig. 7(b), and a three-way valve 40 is provided at the joining point, and the three-way valve 40 is configured so that one of a state in which the two chemical

liquid supply pipes

5 and 6 and the electroless plating liquid supply pipe 41 are simultaneously connected and a state in which the two chemical liquid supply pipes are simultaneously blocked can be selected.

As means for adjusting the flow rates of the first chemical liquid and the second chemical liquid, a flow rate adjusting section is not provided, and a discharge rate controllable pump such as a bellows pump may be used to adjust the discharge rate of each chemical liquid and set the mixing ratio.

Fig. 8 and 9 are views showing important parts of another embodiment of the present invention. In this example, the upper temperature control member 3 is formed in a cylindrical shape having a size slightly larger than that of the wafer W, and the inside thereof is formed as a circulation chamber 31 through which a heat medium such as a temperature control fluid, for example, pure water flows. The heat medium supply pipe 32 is connected to the vicinity of the outer edge portion of the upper surface of the upper temperature-adjusting body 3, and the heat medium discharge pipe 33 is connected to a position symmetrical to the heat medium supply pipe 32, for example, in the center portion of the upper temperature-adjusting body 3.

In the circulation chamber 31, the first chemical liquid supply tube 5 and the second chemical liquid supply tube 6 having a tubular shape are arranged from the upper surface side, the chemical

liquid supply tubes

5 and 6 are formed in a spiral shape, for example, and are joined together in the middle, and the lower end of the electroless plating liquid supply tube 41 of the joined tube is formed as a discharge port 42 on the lower surface of the upper temperature control member 3. In this example,

valves

51 and 61 are provided near the confluence point of the first chemical liquid supply pipe 5 and the second chemical liquid supply pipe 6, and a valve 43 is provided near the discharge port 42 of the electroless plating liquid supply pipe 41, in the same manner as in the above embodiment, except that the chemical

liquid supply pipes

5 and 6 and the electroless plating liquid supply pipe 41 are disposed in the circulation chamber 31 for the heat medium of the temperature controller 3. The volume of the supply pipe 41 held by the

valves

43, 51, 61 corresponds to the discharge amount required for the electroless plating process for one wafer W. In this configuration, the temperature of the electroless plating solution changes slowly, and there is an advantage that the electroless plating solution is not excessively heated even when the temperature of the electroless plating solution is set to a high temperature.

Further, in the first chemical liquid supply pipe 5 and the second chemical liquid supply pipe 6, the chemical liquid opening and closing

valves

51 and 61 are opened, and a portion filled with the chemical liquid used for one substrate, that is, a portion filled with the chemical liquid required for processing one wafer W from the

respective valves

51 and 61 in the first chemical liquid supply pipe 5 and the second chemical liquid supply pipe 6 is located in the circulation chamber 31. By heating the chemical solution to the processing temperature of the electroless plating solution, the time from mixing the first chemical solution and the second chemical solution to the start of electroless plating can be shortened.

In relation to the temperature of the electroless plating process at this time, but for example, when the temperature of the electroless plating process is set high at 60 ℃, the time for preparing the electroless plating process for the surface of the next wafer W after supplying the electroless plating liquid onto the surface of one wafer W becomes short, and in the embodiment of fig. 1, some waiting time may be required for the electroless plating liquid to rise to the processing temperature in the electroless plating liquid supply pipe 41. In contrast, in this example, if the temperatures of the first chemical solution and the second chemical solution are previously heated (preheated), the time required to raise the temperature to the processing temperature is reduced when the two chemical solutions are mixed, and as a result, the throughput can be improved. In the embodiment of fig. 1, the structure for preheating the temperatures of the first chemical solution and the second chemical solution may be provided with temperature control units in the first chemical solution supply pipe 5 and the second chemical solution supply pipe 6, respectively, for example.

The first chemical liquid and the second chemical liquid of the present invention are not limited to the above examples, and may be applied to a case where precipitation or other troubles are generated after a certain time has elapsed after mixing.

From the foregoing, the present invention has been described in detail by the preferred embodiments, and it will be apparent to those skilled in the art that various changes and modifications may be made within the scope of the claims defined by the present invention.

Claims

1. An electroless plating apparatus, comprising:

a substrate holding section for holding the substrate in a lateral state;

a first chemical liquid supply tube for supplying a first chemical liquid;

a first chemical liquid switching unit provided in the vicinity of a downstream end of the first chemical liquid supply tube and controlling a flow rate of the first chemical liquid;

a second chemical liquid supply tube for supplying a second chemical liquid;

a second chemical supply source connected to an upstream end of the second chemical supply tube;

a second chemical liquid switching unit provided in the vicinity of the downstream end of the second chemical liquid supply tube and controlling the flow rate of the second chemical liquid;

an electroless plating liquid supply tube connected to downstream ends of the first and second chemical liquid supply tubes for supplying an electroless plating liquid, which is formed by mixing the first and second chemical liquids, to the upper surface of the substrate;

a plating liquid switching unit disposed in the vicinity of a downstream end of the electroless plating liquid supply tube, which is a discharge port, and configured to control a flow rate of the electroless plating liquid; and

wherein,

the volume of the electroless plating supply pipe surrounded by the first chemical solution switch cell, the second chemical solution switch cell, and the plating solution switch cell corresponds to a discharge amount required for performing electroless plating on one substrate.

2. The electroless plating apparatus according to claim 1, further comprising:

an upper temperature control member disposed opposite to the substrate surface held by the substrate holding portion, having a discharge port formed on a lower surface thereof, and having a discharge port for supplying an electroless plating solution, the discharge port being larger than an effective area of the substrate;

and a moving mechanism for moving the upper temperature control member between a processing position where the upper temperature control member and the upper surface of the substrate are filled with the electroless plating solution and a standby position located at a distance from the processing position.

3. The electroless plating apparatus according to claim 2, wherein:

the entire supply pipe for the plating liquid is disposed in the circulation chamber of the upper temperature control member, whereby the upper temperature control member controls the temperature of the electroless plating liquid by heat exchange between the temperature control liquid and the electroless plating liquid.

4. The electroless plating apparatus according to claim 2, wherein:

the upper temperature control body is provided with a circulating chamber filled with temperature control liquid;

the first and second chemical liquid supply pipes include a portion containing a chemical liquid to be supplied to the electroless plating liquid supply pipe, and the portion is disposed in the circulation chamber of the upper temperature control member.

5. The electroless plating apparatus according to claim 1, wherein:

a temperature adjusting unit is provided in the first and second chemical liquid supply pipes for adjusting the temperature of a portion containing the chemical liquid to be supplied to the electroless plating liquid supply pipe.

6. The electroless plating apparatus according to claim 1, wherein:

the first and second liquid chemical switch units may be used as one liquid chemical switch unit.

7. The electroless plating apparatus according to claim 1, further comprising flow rate adjustment units for adjusting flow rates of the first and second chemical solutions, respectively.

8. The electroless plating apparatus according to claim 1, further comprising a lower temperature adjuster provided opposite to the lower surface of the substrate, the lower temperature adjuster including a substrate temperature adjusting unit for adjusting the temperature of the substrate.

9. The electroless plating apparatus according to claim 8, wherein: the substrate temperature adjusting unit adjusts the temperature of the substrate by filling liquid which is adjusted in temperature by the lower temperature adjusting body between the lower temperature adjusting body and the substrate.

10. An electroless plating method using the electroless plating apparatus according to claim 1, characterized in that: the first chemical liquid is a solution containing a metal salt of the plating metal, and the second chemical liquid is a solution containing a reducing agent as an electron supply source.

11. An electroless plating method using the electroless plating apparatus according to claim 1, characterized in that: the first chemical solution switch unit, the second chemical solution switch unit, and the plating liquid switch unit are switched simultaneously.

12. An electroless plating method using the electroless plating apparatus according to claim 2, characterized in that: the supply pipe temperature adjusting unit and the upper temperature adjusting body are adjusted to the plating process temperature.

13. An electroless plating method using the electroless plating apparatus according to claim 5, characterized in that: the temperature regulating unit of the supply pipe and the temperature regulating unit mounted on the first and second chemical supply pipes are regulated to the temperature of the electroplating process.

14. An electroless plating method using the electroless plating apparatus according to claim 8, characterized in that: the supply pipe temperature adjusting unit and the substrate temperature adjusting unit are adjusted to the plating process temperature.