JP2002129385A - Plating method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plating method which forms an adequately covered film, as a result of delivering a plating solution into a concave such as a contact hole, which is shaped on a surface to be plated of a workpiece such as a semiconductor wafer. SOLUTION: The plating method comprises the first step of wetting the concave 80 shaped on the surface to be plated of the workpiece W with deionized water 82 by contacting the surface with the deionized water 82, and the second step of forming a copper film on the surface to be plated of the workpiece in wetting condition with an electroplating after immersing the workpiece in a plating solution 14. This method of wetting an inner face of the concave 80 by contacting the surface of the workpiece with deionized water as a pre- treatment of electroplating, makes the plating solution easily get into the concave, and prevents failure of the formed film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technology for manufacturing semiconductor devices and the like, and more particularly to an electrolytic plating method used for forming a metal film such as copper.

[0002]

2. Description of the Related Art In recent years, high integration and miniaturization of semiconductor devices have been rapidly progressing, and there is a steady transition from the present sub-half micron to sub-quarter micron. In response to such demands for higher integration and miniaturization of semiconductor devices, copper, which has low resistance and excellent electromigration resistance, has attracted attention as a wiring material, and has been practically put into practical use.

There are various methods for forming a copper wiring film, such as a sputter reflow method and a CVD method, and an electrolytic plating method has been widely adopted because a relatively good embedding property can be obtained at a low cost and a high throughput. I have.

[0004] Conventional general copper electroplating apparatuses include:
A face-down type as shown in FIG. 2 is known. In the plating apparatus 10, the semiconductor wafer W is immersed in the plating solution 14 in the liquid tank 12 with its surface on which the film is to be formed facing downward. Is applied, a copper film is formed on the semiconductor wafer W.

[0005]

By the way, in the electrolytic plating method, it is essential that the plating solution is sufficiently distributed to concave portions such as contact holes and wiring grooves formed on the surface on which the semiconductor wafer W is formed. Condition. That is, when air bubbles remain in the concave portion, copper does not adhere to that portion, resulting in a film having poor embedding properties.

For this reason, conventionally, the semiconductor wafer W is charged into the plating solution while being tilted and rotated so that air does not accumulate on the film formation surface of the semiconductor wafer W.

However, due to the high integration and miniaturization of semiconductor devices, it has become difficult to reliably fill a contact hole or the like with a plating solution.

Accordingly, an object of the present invention is to provide a plating solution that sufficiently spreads over a concave portion such as a contact hole formed on a surface to be processed of an object to be processed such as a semiconductor wafer to form a film having a good embedding property. An object of the present invention is to provide a plating method that can be performed.

[0009]

Means for Solving the Problems To achieve the above object, a plating method according to the present invention provides a plating method in which pure water, a plating solution, and other plating solutions are mixed on a film-forming surface of an object to be processed. A first step of adhering a liquid that maintains the component ratio of the above, and wetting the inner surface of the concave portion formed on the film formation surface of the object with the liquid, and after the first step, the film formation surface of the object is And dipping the object in a plating solution in a wet state and forming a metal film on the surface of the object to be formed by electrolytic plating.

As described above, as a pretreatment of the electrolytic plating treatment, a liquid such as pure water or a plating solution is adhered to the film formation surface of the object to be processed, and the inner surface of the concave portion such as a contact hole or a wiring groove is exposed to the liquid. When the liquid to be treated is immersed in the plating solution, the plating solution easily penetrates into the concave portions, and the occurrence of film formation failure can be suppressed or prevented.

As a method for adhering a liquid such as pure water, it is effective that the liquid is atomized and the object to be processed is brought into contact with the atomized liquid. This is because the liquid is distributed to the inner surface of the fine concave portion by using the mist-like liquid.

The method of adhering the liquid may be performed by immersing the object in the liquid stored in the liquid tank. In such a case, it is preferable to apply vibration to the liquid while the object to be processed is immersed in the liquid tank in order to crush and remove air bubbles that have entered the concave portion. For the same purpose, vibration may be applied to the object after the liquid is attached to the object.

[0013] Further, general plating maintenance is provided with a plating apparatus using an electrolytic plating method and a cleaning apparatus for cleaning an object to be film-formed by a plating solution apparatus with pure water. Before transporting the object to be plated to the plating apparatus, the pure water is attached to the film formation surface of the object to be processed in the cleaning apparatus, thereby effectively utilizing the equipment.
preferable.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a schematic sectional view showing an embodiment of equipment capable of performing the plating method according to the present invention. The plating equipment 100 shown in FIG. 1 includes a housing 200 in which the inside is
And an electrolytic plating apparatus 10 disposed therein. In the illustrated embodiment, a plurality of plating apparatuses 10 are provided so that a plurality of semiconductor wafers (objects) W can be processed simultaneously.

The plating apparatus 10 has the same configuration as the conventional apparatus described above with reference to FIG. Therefore, referring to FIG. 2 again, the plating apparatus 10 includes the liquid tank 1.
2, a disk-shaped copper plate 16 as a film forming material source disposed below the liquid tank 12, and a wafer holder 18 for holding the semiconductor wafer W downward.

A plating solution supply port 20 is provided at the bottom of the solution tank 12. An external pump 22 is connected to the plating solution supply port 20, whereby the plating solution 14 is supplied into the solution tank 12 from the bottom and flows upward. Further, the periphery of the liquid tank 12 is surrounded by an outer tank 24, so that the plating liquid 14 overflowing from the liquid tank 12 can be received and the plating liquid 14 can be collected in an external tank 26. . Since the tank 26 is connected to the suction port of the pump 22, the plating solution 14 is circulated.

The copper plate 16 is disposed substantially coaxially and horizontally at the bottom of the substantially cylindrical liquid tank 12, and an annular gap is formed between the inner wall surface of the liquid tank 12 and the copper plate 16. I have. Therefore, the plating solution 14 supplied from the supply port 20 at the bottom of the liquid tank 12 rises in the liquid tank 12 through this gap.

Above the copper plate 16, a wafer holder 18 for holding the semiconductor wafer W and immersing it in the plating solution 14 stored in the solution tank 12 is arranged. Wafer holder 1
The wafer holding surface 8 is horizontal and downward, and the film formation surface of the semiconductor wafer W held on this holding surface also faces downward. The wafer holder 18 is connected to a rotation drive source 28 so as to be driven to rotate about a vertical center axis of the liquid tank 12.

The wafer holder 18 is further provided with an elevating / tilting mechanism (not shown), which can move the semiconductor wafer W above the liquid tank 12 for wafer exchange or the like. Can be inclined.

The wafer holder 18 is provided with an electric terminal 30 which is in contact with the edge of the semiconductor wafer W held on the wafer holding surface.
Are connected. A thin copper seed layer (conductive film) is previously formed on the film formation surface of the semiconductor wafer W to be copper-plated by a PDV method or the like, and this copper seed layer functions as a cathode. The anode of the power supply 32 is connected so that the copper plate 16 functions as an anode.

The plating equipment 100 further includes a housing 2
The loading station 300 is provided adjacent to the outside of the loading station 300. Loading station 3
In 00, a wafer cassette 50 accommodating a plurality of semiconductor wafers W is set. An unprocessed semiconductor wafer W is transferred from the wafer cassette 50 to an appropriate robot device 60,
It is taken out using 62 and set on the wafer holder 18 of the plating apparatus 10. After the film forming process in the plating apparatus 10, the processed wafer is returned to the wafer cassette 50.

In the housing 200, a cleaning device 70 for cleaning the plating solution from the processed semiconductor wafer W is provided.
Is provided. The cleaning device 70 also functions as an intermediate station for transferring the semiconductor wafer W between the blades of the robot devices 60 and 62, and has a support 72 that supports the semiconductor wafer W. The support 72 is rotatable in the cleaning device 70, and the semiconductor wafer W is cleaned by the pure water sprayed from the spray nozzle 74 while rotating in the cleaning device 70. Further, a spray nozzle 7 is provided inside the cleaning device 70.
6 are provided. The spray nozzle 76 can spray pure water in a mist state on the surface of the semiconductor wafer W on which the film is to be formed.

A method for forming a copper film on the semiconductor wafer W in such a configuration will be described with reference to FIG.

First, a dry unprocessed semiconductor wafer W is taken out of the wafer cassette 50 by the robot device 60 and placed on the support 72 of the cleaning device 70. Then, the support 72 is rotated inside the cleaning device 70, and atomized pure water is sprayed from the spray nozzle 76 onto the film formation surface of the semiconductor wafer W. Pure water is in the form of a mist,
Since the semiconductor wafer W is rotated, minute recesses 8 such as contact holes and wiring grooves formed on the surface on which the film is to be formed are formed.
The pure water 82 is sufficiently distributed even within 0, and the entire surface on which the semiconductor wafer W is formed is wet with the pure water 82 without bubbles remaining (see FIG. 3A).

Thereafter, before the pure water dries, the robot device 6
2, the semiconductor wafer W is set from the cleaning device 70 to the wafer holder 18 of the plating device 10. And, going up and down
By controlling a tilting mechanism (not shown), the semiconductor wafer W is immersed diagonally in the plating solution 14 in the solution tank 12, and at the same time,
The rotation driving source 28 is driven to rotate the semiconductor wafer W at a low speed. In this state, no air accumulates on the lower surface of the semiconductor wafer W, and in addition, since the inner surface of the concave portion 80 of the film formation surface of the semiconductor wafer W is wet with pure water 82, copper sulfate is mainly used. The water-soluble plating solution 14 as a component easily penetrates into the concave portion 80, and is filled with the plating solution 14 without gaps (see FIG. 3B). In addition. Since the plating solution 14 is water-soluble, the concentration or composition of the plating solution 14 does not significantly change due to a slight amount of pure water 82 attached to the surface of the semiconductor wafer W. There is no effect on the process.

Next, the position of the wafer holder 18 is adjusted so that the film formation surface of the semiconductor wafer W and the upper surface of the copper plate 16 are parallel, and the pump 22 is driven to move the plating solution 14 into the solution tank 1.
2 and circulated through the outer tank 24 and the tank 26. Then, when the power supply 32 is turned on while the semiconductor wafer W is rotated at a low speed, the copper ions in the liquid tank 12 are reduced on the film formation surface (copper seed layer) of the semiconductor wafer W as a cathode and grow as a copper film. I will do it. Of course, plating solution 14
Are spread in the recess 80 such as a contact hole, so that voids caused by insufficient penetration of the plating solution 14 are not formed in the copper film.

After the desired copper film is formed in this way, the semiconductor wafer W is taken out of the liquid tank 12, transferred to the cleaning device 70, and cleaned therein. Then, after drying, the semiconductor wafer W is returned to the wafer cassette 50.

In the above embodiment, the cleaning device 70, which is a post-processing device of the plating process, is used for the pre-processing of pure water spraying, but a pre-processing chamber may be provided separately from the cleaning device 70. In such a case, a liquid other than pure water, for example, a plating solution or another liquid such as a solvent for the plating solution (even if a small amount is mixed with the plating solution, the component ratio other than the solvent (water) of the plating solution is substantially maintained. , Which does not have any effect on the plating process).

It is not essential to provide the spray nozzle 76 in the pretreatment chamber or the cleaning device 70. An atmosphere in which mist-like pure water or the like exists is formed by, for example, ultrasonic waves, and the semiconductor wafer W is exposed there. Or just

Further, according to the present invention, before sending the unprocessed semiconductor wafer W to the plating apparatus 10, the pretreatment is performed to wet the film formation surface thereof with pure water or the like without any gap. As a pretreatment method, pure water or the like may be applied to the film formation surface of the semiconductor wafer W without atomization, or a pretreatment liquid tank (not shown) may be prepared, and the semiconductor wafer W may be stored in the pure water or the like stored therein. May be adopted. However,
In such a method, it is conceivable that bubbles 84 remain in the concave portions 80 of the semiconductor wafer W as shown in FIG. Therefore, after the semiconductor wafer W is pulled up from the liquid tank, or after the supply of pure water or the like to the semiconductor wafer W is completed, the semiconductor wafer W is vibrated to remove the bubbles 84 remaining in the concave portion 80 of the semiconductor wafer W. It is desirable to crush and remove. A similar effect can be obtained by attaching a vibration generator (not shown) to the pretreatment liquid tank and applying vibration to the liquid while the semiconductor wafer W is immersed in the liquid such as pure water.

Further, immediately after the semiconductor wafer W is immersed in the plating solution 14 in the solution tank 12 of the plating apparatus 10, vibration is applied to the solution tank 12, and hence the plating solution 14, so that the semiconductor wafer W The remaining bubbles may be removed. Alternatively, the semiconductor wafer W may be vibrated through the wafer holder 18. Thus, the plating apparatus 10
By performing the pre-processing in the apparatus, it is not necessary to prepare a special pre-processing apparatus.

Although the preferred embodiments of the present invention have been described in detail, it goes without saying that the present invention is not limited to the above embodiments. For example, the plating apparatus of the above embodiment is a face-down type in which the film formation surface of the semiconductor wafer W faces downward, but the present invention is also applicable to a face-up type and other plating apparatuses. Can also be a metal other than copper.

[0034]

As described above, according to the present invention, when an object to be processed such as a semiconductor wafer is immersed in a plating solution of a plating apparatus, contact holes and wiring grooves formed on the surface on which the film is to be formed are formed. The plating solution spreads even in the minute concave portions without gaps. As a result, the problem of poor film formation due to the remaining bubbles is significantly reduced or eliminated, a good metal film is formed, and the semiconductor device contributes to high speed, high performance, and miniaturization, and also contributes to improvement in yield. .

[Brief description of the drawings]

FIG. 1 is an explanatory view schematically showing a plating facility capable of performing a plating method according to the present invention.

FIG. 2 is an explanatory view schematically showing a plating apparatus used in the plating facility of FIG.

FIGS. 3A to 3C are explanatory diagrams showing states of pure water and a plating solution with respect to a concave portion of a semiconductor wafer.

[Explanation of symbols]

10 ... Plating apparatus, 12 ... Liquid tank, 14 ... Plating solution, 16
... copper plate, 18 ... wafer holder, 20 ... plating solution supply port,
28: rotation drive source, 50: wafer cassette, 60, 62
... robot device, 70 ... cleaning device, 76 ... spray nozzle,
80: recess, 82: pure water, W: semiconductor wafer (object to be processed), 100: plating equipment, 200: housing, 30
0 ... Loading station.

Continuing on the front page (72) Inventor Ryoho Ito 14-3, Shingeizumi, Narita-shi, Chiba Applied Materials Japan Co., Ltd. (72) Ikuo Suzuki 14-3, Shingeizumi, Shinzumi, Narita-shi, Chiba Pref. Applied Materials Japan Co., Ltd. F term (reference) 4K024 AA09 AB01 BA11 BB12 BC10 CA12 CB02 DA01 DA04 DA10 DB10 GA16 4M104 BB04 DD52 HH13

Claims (6)

[Claims] A pure water, a plating solution,
A first step of attaching a liquid that maintains the component ratio of the plating solution when mixed with the plating solution, and wetting the inner surface of a concave portion formed on the film forming surface of the object to be processed with the liquid; After one step, the object to be processed is immersed in a plating solution in a state where the surface of the object to be processed is wet, and a metal film is formed on the surface of the object to be processed by an electrolytic plating method. A second step of forming a film. 2. The plating method according to claim 1, wherein the liquid is attached by atomizing the liquid and bringing the object to be treated into contact with the atomized liquid. 3. The plating method according to claim 1, wherein the adhesion of the liquid is performed by immersing the object to be processed in the liquid stored in a liquid tank. 4. The plating method according to claim 3, wherein the liquid is vibrated while the object is immersed in the liquid in the liquid tank. 5. After attaching the liquid to the object to be processed,
2. The method according to claim 1, wherein the object to be processed is vibrated.
5. The plating method according to any one of Items 4 to 4. 6. A plating method using plating equipment comprising: a plating apparatus by an electrolytic plating method; and a cleaning apparatus for cleaning an object to be processed, which has been formed by the plating solution apparatus, with pure water. A plating method, wherein pure water is adhered to a film formation surface of the object to be processed in the cleaning device before the object is transferred to the plating apparatus.