JPH1167695A - Liquid-filling method/device into fine hollow and plating method into fine hollow - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid filling method and a device into a fine hollow and to provide a plating method into the fine follow, which can fill the fine hollow provided on the surface of a base material with the various liquids of plating liquid. SOLUTION: The space round a semiconductor wafer 100 is sealed in a plating processing layer 1, and a vacuum evacuation means 3 vacuum-evacuates air. The gas with a large solubility (ammonia gas, sulfurous acid gas and carbon dioxide) is introduced in a gas supply means 5. Gas remains in the fine hollow provided on the surface of the semiconductor wafer 100 is dissolved in plating liquid, and the fine hollow is filled with plating liquid by introducing plating liquid into the plating processing layer 1 in a liquid supply means 7. Thus, the inner part of the fine hollow is filled with plating.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for filling a fine recess suitable for filling a desired liquid such as a plating solution into a fine recess provided on the surface of a base material such as a semiconductor wafer. The present invention relates to a method for plating fine recesses.

[0002]

2. Description of the Related Art Heretofore, aluminum alloys have been generally used as wiring for semiconductor devices. However, as the wiring width becomes finer, the electrical resistance of the aluminum alloy cannot be ignored and its switching speed is limited. In addition, there is a fear that the wiring may be disconnected due to migration of aluminum alloy constituent atoms (stress migration, electromigration).

In recent years, attention has been paid to a copper material having an electric resistivity smaller than that of an aluminum alloy, and it has been considered to use the copper material for wiring of a semiconductor element. Although silver also has a small electrical resistivity, copper is preferred because it is expensive, has low strength and low corrosion resistance, and is easily diffused.

Since a practical dry etching technique has not been established for copper materials, it is not possible at present to use a wiring forming method in which this is combined with sputtering film formation as in the case of conventional aluminum alloys. The insulating layer with a hole, followed by chemical mechanical polishing (CMP)
The method of forming wirings, plugs, and the like by using (method) has attracted attention.

That is, for example, as shown in FIG. 5A, a groove 203 for wiring and a cylindrical contact hole 201 connected to the lower conductive layer 221 are formed in the SiO ₂ insulating layer 202 on the surface of the semiconductor wafer 100. Formed on the barrier layer 2
The one on which 05 is formed is prepared. The barrier layer 205 is provided for preventing copper diffusion described below.

Next, as shown in FIG. 5B, the semiconductor wafer 100 is immersed in a plating solution and then washed with water to form a copper layer 207 on the entire surface thereof.
03 and the inside of the contact hole 201 are completely filled with copper.

Next, as shown in FIG. 5C, the copper layer 207 on the surface of the insulating layer 202 and the barrier layer 2 are formed by chemical mechanical polishing.
05 is removed, and thereby the wiring 211 in which copper is buried.
And a plug 213 are formed.

[0008]

By the way, the widths of the recesses such as the trenches 203 and the contact holes 201 for forming the wiring 211 and the plug 213 are becoming increasingly narrower due to miniaturization due to the integration of semiconductor elements. 0.18μm
And a width of about 0.13 μm is required.

However, when the recesses such as the groove 203 and the contact hole 201 are miniaturized, even if the semiconductor wafer 100 is immersed in a plating solution,
There is an increased possibility that air existing in the contact hole 3 or the contact hole 201 remains as it is due to surface tension or the like.
In particular, since the contact hole 201 and the like are deeper than the width thereof (for example, the aspect ratio [depth / width]) ≒ 5
Etc.), air tends to remain inside.

In order to perform proper plating, it is necessary to sufficiently wet the inner surface of the dent with a plating solution, and if air remains, the groove 203 or the contact hole 201 is not removed.
As a result of preventing the plating solution from penetrating into the inside, it becomes impossible to bury copper inside the recess by plating.

The present invention has been made in view of the above points, and has as its object to provide a method and an apparatus for filling a fine dent with a liquid capable of filling various liquids such as a plating solution inside the fine dent, and It is an object of the present invention to provide a plating method for fine depressions.

[0012]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention relates to a method for filling a fine dent provided in a fine dent provided on the surface of a substrate with a desired liquid, the method comprising: The space around the portion provided with the fine depression is replaced with a gas having high solubility, and the gas remaining in the fine depression is introduced by introducing a desired solution into the space replaced with the gas. The solution was dissolved in the solution, and as a result, the solution was filled in the fine depression. The present invention also provides a liquid filling apparatus for filling a desired liquid into a fine dent provided on the surface of a base material, wherein at least a space around a portion of the base material where the fine dent is provided is covered. A tank, a gas supply means for introducing a gas having high solubility into the processing tank, and a liquid supply means for filling the processing tank with a desired liquid and dissolving the gas remaining in the fine depression. It was decided to.

[0013]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is an overall schematic configuration diagram showing an embodiment in which the present invention is applied to a plating apparatus that fills a fine recess for a plug or wiring formed on the surface of a semiconductor wafer with plating.

As shown in FIG. 1, this apparatus is constituted by connecting a vacuum evacuation means 3, a gas supply means 5 and a liquid supply means 7 to a sealed plating tank 1. Hereinafter, each component will be described.

The plating tank 1 has a structure in which the semiconductor wafer 100 is housed and the surrounding space is sealed.
And a temperature adjusting means 13 attached thereto.

The vacuum exhaust means 3 is connected to the plating tank 1 by a pipe 3
1 and a vacuum pump 35 connected via a valve 33.

The gas supply means 5 is connected to the plating tank 1 by a pipe 5
1 and a gas supply source 55 connected via a valve 53. As a gas to be supplied here, a gas having high solubility in the following solution (pure water in this embodiment) may be used. For example, ammonia gas (NH ₃ )
Or hydrogen chloride gas (HCl), sulfurous acid gas (SO ₂ ), carbon dioxide gas (CO ₂ ), or the like.

The liquid supply means 7 includes a preliminary liquid tank 71 for storing a plating solution for copper plating, a pump 73 and a filter 75.
And a pipe 77 for supplying a solution (pure water in this embodiment) is connected to a pipe 77 between the plating tank 1 and the filter 75 by a pipe 77. A pipe 81 for drainage is connected to a pipe 77 between the plating tank 1 and the preparatory liquid tank 71.
Valves 83 and 85 are connected to the connection between
Valves 87 and 89 are connected to the connection between the pipe 77 and the pipe 81. The preliminary liquid tank 71 has a preliminary liquid tank 7.
A temperature adjusting means 72 for adjusting the plating solution in 1 to a predetermined temperature is attached.

Next, the operation procedure of the plating apparatus will be described with reference to FIGS. That is, first, each of the valves 33, 53, 8
3, 85, 87 and 89 are closed, and the plating tank 1
The semiconductor wafer 100 in which the inside of the fine recess for plug or wiring is to be filled with plating is stored therein (step 1).

Next, the valve 33 is opened and the vacuum pump 35 is driven to exhaust the air in the plating bath 1 (step 2).

Next, after closing the valve 33, the valve 53 is opened to fill the plating tank 1 with gas from the gas supply source 55, and at the same time, the pressure returns to the atmospheric pressure (step 3). As a result, the gas is filled also in the fine recess provided on the surface of the semiconductor wafer 100. Since the gas is filled, the influence of the surface tension and the like is extremely small as compared with the case of the liquid, and the gas easily penetrates into the fine depression. Further, if necessary, the operation of evacuating and introducing gas is repeated to realize a sufficient degree of internal gas replacement.

Next, after closing the valve 53, the valve 85 is opened to inject a solution (pure water) into the plating tank 1.
The semiconductor wafer 100 is immersed in the solution (step 4). Since the solution is a liquid, the gas in the fine depression remains without being easily discharged due to surface tension.

Then, it waits for a predetermined time to elapse in this state (step 5). During this waiting time, the gas G in the fine dent 101 provided on the surface of the semiconductor wafer 100 as shown in FIG. 3 is dissolved in the solution Q and gradually replaced, and as a result, the fine dent is formed. 101 is filled with a solution.

Here, the amount of gas G dissolved in water is about 10,000 with respect to the amount of air dissolved in water.
Times, hydrogen chloride gas about 5,000 times, sulfur dioxide gas about 8 times
00 times, carbon dioxide gas is about 20 times.

That is, for example, when sulfur dioxide is used, the dissolution rate in water is about 1.26 cm ³ / (cm ² s). This means that when water and sulfur dioxide gas are in contact with each other with a contact area of 1 cm ² , 1.26 cm ³ of sulfur dioxide gas is dissolved in water in 1 ^second . This means that when a sulfuric acid gas is filled in a depression having a diameter of 12 mm at an opening having a diameter of 12 mm and water is present on the opening, the water reaches the bottom of the depression after 1 s. In other words, the inside of the fine depression 101 having a volume much smaller than this is filled with the solution at a considerably high speed.

Further, according to this method, since the phenomenon of dissolving gas into the solution is used, the solution can be formed without any hindrance caused by so-called surface tension, no matter how fine the depression is. It can easily penetrate into the fine depression 101, which is a great advantage of the present invention.

It is known that the amount of dissolved gas generally increases as the temperature decreases and the system pressure increases. Therefore, if necessary, the temperature of the solution can be cooled by the temperature adjusting means 13 and 72, or the like. By using the vacuum pump 35 as a pressurizing pump on the contrary (or by attaching a pressurizing means separately from the vacuum pump 35), a sufficient dissolving capacity can be obtained.

Next, the solution in the plating tank 1 is discharged by closing the valve 85 and opening the valve 89 (step 6). At this time, the surface of the semiconductor wafer 100 is exposed to air, but the solution filled in the fine dents 101 remains as it is.

Next, the valve 89 is closed and the valves 83 and 87 are closed.
Is opened, the plating solution is introduced into the plating bath 1 by driving the pump 73, and the semiconductor wafer 100 is immersed in the plating solution (step 7). The temperature of the plating solution is adjusted by the temperature adjusting means 13 and 72 to, for example, 25 in the case of electrolytic plating.
C. and 50 ° C. for electroless plating. The interfacial tension acts between the dissolving solution and the plating solution filled in the fine dents 101, but since both solutions are mutually soluble, the value is small. Therefore, the plating solution easily penetrates into the fine recesses 101, and replacement of the solution is easily achieved.

Here, it is also possible to directly inject the plating solution whose concentration has been adjusted into the processing tank 1 filled with the dissolving solution and to reach a predetermined plating solution concentration while circulating the plating solution with an external supply system. .

In the case of electroless plating, the surface of the semiconductor wafer 100 that is in contact with the plating solution is plated with copper as it is. In the case of electrolytic plating, electrolytic plating is performed by applying an electric field between the semiconductor wafer 100 and a copper material (not shown) in the plating bath 1. In any case, since the plating solution is filled in the minute dent 101, the inside of the minute dent 101 can be reliably filled with copper plating. This can be easily formed (step 8).

As a plating solution for electrolytic plating, for example, an aqueous solution containing CuSO ₄ .5H ₂ O, sulfuric acid, an additive and chlorine ions is used. As a plating solution for electroless plating, for example, CuSO ₄ .5H ₂ An aqueous solution containing O, EDTA · 4Na (sodium ethylenediaminetetraacetate), TMAH (tetramethylammonium hydride oxide) and formalin is used.

After plating for a predetermined time, the semiconductor wafer 100 is taken out of the plating bath 1 (step 9).

In the above embodiment, the plating tank 1
The solution is once filled with a solution (pure water) and then replaced with a plating solution. However, a plating solution may be directly used as the solution. In this case, pipes 79 and 8 shown in FIG.
1 and the valves 85 and 89 become unnecessary.

This embodiment will be described with reference to FIGS. 1 and 4. First, the semiconductor wafer 100 is stored in the plating bath 1 (step 1), and then the vacuum pump 35 is driven to drive the plating bath 1 Exhaust the air inside (Step 2)
Next, a gas is supplied from the gas supply source 55 into the plating tank 1 (step 3), whereby the gas is also filled into the fine recess provided on the surface of the semiconductor wafer 100, and then the valve 53 is closed. Open the valves 85 and 87 and set the pump 73
Is driven to introduce a plating solution into the plating tank 1 (step 4). Then, it waits for a predetermined time to elapse in this state (step 5). Then, the gas remaining in the fine dent 101 during this waiting time is dissolved in the plating solution and replaced, thereby filling the inside of the fine dent 101 with the plating solution. The gas dissolution rate by the plating solution shows basically the same value as that of the pure water.

In the case of electroless plating, the surface of the semiconductor wafer 100 that is in contact with the plating solution during step 5 is copper plated as it is. In the case of electrolytic plating, after step 5 (or during step 5), electrolytic plating is performed by applying an electric field between the semiconductor wafer 100 and a copper material (not shown) in the plating bath 1. In any of the platings, the plating solution is filled in the fine recesses 101, so that the fine recesses 101 can be reliably filled with copper plating (step 6).

After plating for a predetermined time, the semiconductor wafer 100 is taken out of the plating bath 1 (step 7).

The semiconductor wafer 100 plated according to each of the above embodiments has the plating embedded in the fine dent 101 (in FIG. 5, the wiring groove 203 and the contact hole 201) as described with reference to FIG. Wiring and plugs are formed by removing the remaining plating on the surface of the semiconductor wafer 100 by chemical mechanical polishing.

More specifically, as shown in FIG. 6, the semiconductor wafer 100 is held on the lower surface of the top ring 300 with the surface provided with the fine recesses 101 facing downward, and the top ring 3
Turntable 350 that rotates separately while rotating 00
The polishing cloth 351 affixed to the upper surface is polished while being in contact with the polishing liquid while supplying the polishing liquid.
The wiring layer and the plug are formed by removing the plating layer on the zero surface and leaving only the plating embedded in the fine dent 101.

Although the embodiments of the present invention have been described in detail, the present invention is not limited to these embodiments, and for example, the following various modifications are possible. In the above embodiment, an example in which copper plating is performed on a semiconductor wafer has been described. However, the present invention is not limited to copper plating, and can be used for plating with other various materials.

In the above embodiment, the present invention is used for plating a semiconductor wafer. However, the present invention may be used for filling a desired liquid into fine depressions provided in other various base materials. Needless to say, it's good.

In the above embodiment, the entire semiconductor wafer is immersed in the solution. However, the present invention is not limited as long as at least the portion of the base material having the fine depressions is immersed in the solution.

[0043]

As described above in detail, according to the present invention, there is an excellent effect that various liquids such as a plating solution can be easily and reliably filled in a fine recess.

[Brief description of the drawings]

FIG. 1 is an overall schematic configuration diagram showing one embodiment in which the present invention is applied to a plating apparatus for a semiconductor wafer.

FIG. 2 is an explanatory diagram of an operation procedure of a plating apparatus.

FIG. 3 is an explanatory diagram of a state change in a fine depression 101;

FIG. 4 is an explanatory diagram of another operation procedure of the plating apparatus.

FIG. 5 is a view showing a method of forming a wiring 211 and a plug 213 on the surface of the semiconductor wafer 100 by a chemical mechanical polishing method.

FIG. 6 is a view showing a method of polishing the semiconductor wafer 100 by chemical mechanical polishing.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Plating tank (processing tank) 3 Vacuum exhaust means 5 Gas supply means 7 Liquid supply means 100 Semiconductor wafer (base material) 101 Fine recess

Claims (7)

[Claims] 1. A liquid filling method for filling a fine recess into a fine recess provided on a surface of a base material, wherein at least a space around a portion of the base material provided with the fine recess has a solubility. By replacing the gas with a large gas and introducing a desired solution into the space replaced with the gas, the gas remaining in the fine depression is dissolved in the solution and the solution is discharged into the fine depression. A method for filling a liquid into a fine depression, characterized by filling. 2. The method according to claim 1, wherein the dissolving solution is used as a plating solution, so that the surface of the base material is plated with the plating solution, and at the same time, the inside of the fine recesses is filled with plating. A plating method for fine depressions, characterized in that: 3. The method according to claim 1, wherein the gas is dissolved in the dissolving solution by using the dissolving solution as a gas-absorbing liquid in the method for filling liquid into the fine depressions, and then the dissolving solution is replaced with a plating solution. A method of plating the surface of the base material, and at the same time, filling the inside of the fine depression with plating. 4. The plating on the surface of the base material is removed by polishing the surface of the plated base material by chemical mechanical polishing, leaving the plating in the fine recesses.
2. A method for plating fine pits according to the above. 5. A liquid filling apparatus for filling a desired liquid into a fine recess provided on a surface of a base material, wherein at least a space around a portion of the base material provided with the fine recess is covered. A tank, gas supply means for introducing a gas having high solubility into the processing tank, and liquid supply means for filling a desired liquid into the processing tank and dissolving the gas remaining in the fine depression. Characteristic device for filling liquid into fine depressions. 6. The liquid filling apparatus according to claim 5, wherein the liquid supplied by the liquid supply means is a plating liquid for plating a base material. 7. The liquid filling apparatus according to claim 5, wherein the liquid supplied by the liquid supply means is a liquid for gas absorption and a plating liquid for substrate plating.