JPH1192953A - Method for packing microrecesses and apparatus therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the use of materials, such as copper and copper alloys, having a low specific electric resistance as a packing material by supplying liquid having high wetting power or penetrating power into microrecesses to wet the inside surfaces of the recesses before a plating liquid is brought into contact with a base material. SOLUTION: A liquid phase plating stage is executed in the following manner: A pump 17 is operated to transfer the high-penetrating power liquid in a high- penetrating power liquid reservoir 13 into a tank 10. The semiconductor base material 1 in this tank 10 is held for a prescribed time in the state of immersing the material into this liquid. Next, the liquid is discharged from the tank 10 and thereafter, the plating liquid in a plating liquid reservoir 12 is transferred into the tank 10 and the semiconductor base material 1 is held for the prescribed time in the state of immersing the material into the plating liquid. As a result, the copper may be packed into the microrecesses of the semiconductor base material 1. In such a case, the opening width of the microrecesses is specified to >=50×10<-10> to <10000×10<-10> m and the ratio of the opening width and depth of the microrecesses is specified to >=0.1 to <1.0. The liquid having the excellent wetting and penetrating power is particularly exemplified by a surfactant.

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 dent, and more particularly to a method and an apparatus for filling a fine dent such as a wiring groove of a semiconductor element with a metal such as copper (Cu). .

[0002]

2. Description of the Related Art Conventionally, aluminum (Al) or an aluminum alloy has been used as a wiring material for forming a wiring pattern as a conductive line of a semiconductor element.
However, in a wiring process of a semiconductor element, there is a strong demand for establishment of a fine pattern forming technique using a low electric resistance material instead of aluminum or an aluminum alloy due to a demand for further increasing the degree of integration.

[0003] This is because, as the degree of integration increases, the current density increases, so that the temperature rise and the resulting thermal stress both increase to a nonnegligible level. As a result, in conventional Al or Al alloys, stress migration or electromigration occurs. This is largely due to the increased risk of disconnection. In order to avoid this, addition of Cu to Al or Al alloy and lamination with a high melting point metal are being performed, but this is not perfect.

[0004] Therefore, in order to avoid excessive heat generation due to energization, it is inevitably required to employ a material having good conductivity, which is fundamentally different from conventional Al or Al alloy, for forming the wiring. Among the current materials, copper (Cu) and silver (Ag) are materials having lower electric resistivity than Al-based materials.
Among them, silver is expensive, has low strength and low corrosion resistance, and has the disadvantage that constituent atoms are easily diffused. Therefore, copper and copper alloy are most suitable as wiring materials.

Conventionally, to form a wiring pattern,
A method using a combination of sputtering film formation and chemical dry etching has been used, but in sputtering film formation, metal is filled or buried in a wiring groove or hole having a high aspect ratio (ratio of depth to diameter or width). In addition, there has been a problem that chemical dry etching has not been technically established for copper or copper alloy.

Further, there is a CVD method as a means for embedding in a fine wiring groove. However, there is a problem that incorporation of carbon (C) from an organic raw material into a deposited film is unavoidable.

[0007]

That is, in any of the conventional methods, a material having a small electric resistivity such as Cu or a Cu alloy is filled in a fine wiring groove or hole having a high aspect ratio. There was a problem that it was not possible.

The present invention has been made in view of the above circumstances, and it is possible to use a material having a low electric resistivity such as copper or a copper alloy as a filling material, and to insert copper into a fine depression such as a fine wiring groove. Another object of the present invention is to provide a method and an apparatus for filling fine pits by a liquid phase process such as a liquid phase plating process, which can fill a material having a small electric resistivity such as a copper alloy.

[0009]

In order to achieve the above-mentioned object, a filling method of the present invention is a method of filling a fine dent on the surface of a base material with a material different from the base material through a liquid phase. Before contacting with the base material, a liquid having a strong wetting or osmotic power is supplied into the fine depression to wet the inner surface of the fine depression.

Further, the filling device of the present invention fills a fine dent on the surface of a base material with a material different from the base material through a liquid phase. It is configured to be able to sequentially supply, before contacting the plating solution with the base material, a liquid having a strong wetting force or penetrating force is supplied into the fine dent, so that the inner surface of the fine dent is wetted. It is a feature.

According to the present invention, before the semiconductor substrate is brought into contact with the plating solution, the surface energy in the dent can be reduced by supplying a liquid having a strong wetting or penetrating power into the fine dent. Then, after the surface energy in the depression is reduced, the semiconductor substrate is brought into contact with the plating solution, so that the fine depression can be filled with a predetermined metal.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method and an apparatus for filling a fine dent according to the present invention will be described below with reference to FIGS. FIG. 1 is an explanatory view showing a manufacturing process of a semiconductor device manufactured by a method for filling a fine recess. As shown in FIG. 1A, an insulating film 2 made of SiO ₂ is formed on a conductive layer 1a on a semiconductor substrate 1 on which a semiconductor element is formed.
Is deposited, a contact hole 3 and a wiring groove 4 are formed by lithography / etching technology. Then, a barrier layer 5 made of TiN or the like is formed.

Next, in the liquid phase plating process according to the present invention, as shown in FIG. 1B, the contact holes 3 and the grooves 4 of the semiconductor substrate 1 are filled with Cu and the insulating film 2 is formed.
A Cu layer 6 is deposited thereon. Thereafter, the Cu layer on the insulating film 2 is removed by chemical mechanical polishing (CMP), so that the surface of the Cu layer 6 filled in the contact hole 3 and the trench 4 for wiring and the surface of the insulating film 2 are almost completely removed. Make them coplanar. As a result, a wiring made of the Cu layer 6 is formed as shown in FIG.

FIG. 2 is a schematic view showing one embodiment of the structure of an apparatus for performing the liquid phase plating step of the present invention. As shown in FIG. 2, the bottom of the tank 10 is connected to a plating liquid reservoir 12 and a high osmotic liquid reservoir 13, respectively. The plating solution in the plating solution reservoir 12 is supplied to the tank 10 by the pump 14. Reference numeral 15 denotes a filter. The high osmotic liquid in the high osmotic liquid reservoir 13 is supplied to the tank 10 by the pump 17. Reference numeral 18 denotes a filter. FIG. 2 shows the case of electroless plating. In the case of electrolytic plating, an anode made of Cu is further added in the tank 10 of FIG.

The semiconductor substrate 1 is mounted on the mounting portion 19 in the tank 10. The composition of the plating solution L stored in the plating solution reservoir 12 is shown in Table 1.

[Table 1] Table 2 shows the plating conditions.

[Table 2] Tables 1 and 2 show both the cases of electrolytic plating and electroless plating.

Next, a method for performing the liquid phase plating step of the present invention using the apparatus shown in FIG. 2 will be described. The pump 17 is operated from the state shown in FIG. 2 to transfer the high osmotic liquid in the high osmotic liquid reservoir 13 into the tank 10, and the semiconductor substrate 1 in the tank 10 is moved.
Is kept in a state of being immersed in the high osmotic liquid for a predetermined time.

Next, after the highly osmotic liquid is discharged from the tank 10, the pump 14 is operated to transfer the plating liquid in the plating solution reservoir 12 to the tank 10, and the semiconductor substrate 1 in the tank 10 is plated. Immerse in liquid. The semiconductor substrate 1 can be held in a state of being immersed in the plating solution for a predetermined time, and copper can be filled in the fine dents of the semiconductor substrate 1. In this case, the opening width of the fine depression is 50 ° or more and 10,000 °, and the ratio of the opening width to the depth of the fine depression is 0.1 or more and less than 1.0.

In the example shown in FIGS. 1 and 2, the case where copper (Cu) is filled in the fine dent on the semiconductor substrate has been described as an example. It can be widely applied when a material is formed into a film via a liquid phase. Therefore, next, the mechanism of the film forming step including the contacting step using the highly osmotic liquid and the contacting step using the film forming liquid will be described.

In general, the finer the depression, the greater the difference between the volume force and the interfacial force acting on the liquid used for film formation, and it becomes extremely difficult for a normal liquid to penetrate from the outside into the inside of the depression. In wet film formation, the target portion of the substrate on which the film is to be deposited needs to be wetted with the film formation liquid. Therefore, a liquid having an extremely low interfacial tension than the film formation liquid is infiltrated in advance, and With the surface energy reduced sufficiently,
What is necessary is just to make it contact a film-forming liquid. Here, since the surface energy of the dent is low, the film-forming liquid easily penetrates into the dent and gradually replaces the liquid having a low interfacial tension existing with the passage of time thereafter. Finally, the film formation target surface can be wetted.

The surfactant obtains the wetting and osmotic power by lowering the interfacial tension. As an example of a liquid having excellent humid and osmotic power, a surfactant used for washing, such as sulfo-succinic acid, is used. Examples include dialkyl acid esters, tipol type surfactants, sulfated ricinoleate, and nonylphenol polyoxyethylene ether. Dialkyl sulfo succinate esters are

Embedded image Is expressed, Tipol type surfactant,

Embedded image Is represented by the following formula:

Embedded image It is expressed as

FIG. 3 is a graph showing the wetting / penetrating power of nonylphenol / polyoxyethylene / ether.
In FIG. 3, the horizontal axis indicates the number of moles of added ethylene oxide, and the lower the value on the vertical axis, the greater the wetting power. In addition, as shown in FIG. 3, the surfactant (liquid) has a tendency to have a maximum osmotic force at a certain ethylene oxide addition mole number. That is, at either temperature, 1
It shows that the wettability is maximized near the number of moles of 0 mol added. In the above-described case, since the penetrating power increases as the particle diameter of the liquid decreases, the liquid may be supplied to the semiconductor substrate 1 in the form of a mist. In addition, the liquid penetrates more as it receives heat or vibration energy.
The liquid may be vibrated with an energy of 5 Hz to 5 MHz, or the temperature of the liquid and / or the substrate may be increased from room temperature to 100 ° C.

In the apparatus shown in FIG. 2, the high osmotic liquid and the plating liquid are sequentially supplied into the tank 10, but the tank for storing the high osmotic liquid and the tank for storing the plating liquid are separately provided. Alternatively, the semiconductor substrate 1 may be immersed in the high osmotic liquid in the high osmotic liquid tank and then immersed in the plating liquid in the plating liquid tank.

In the description of this embodiment, the case where copper is filled in the fine pits has been described. However, by applying the present invention, it is possible to fill the fine pits with another electrical ratio such as silver (Ag) or gold (Au). A material having a low resistance can also be filled. In the embodiments, the case of electroless plating and electrolytic plating has been described. However, the present invention can also be applied to doping plating, molten salt plating, chemical conversion, sol-gel method, deposition method (LPD), and the like. In addition, any material other than a semiconductor substrate can be filled with the material according to the present invention, as long as it has a fine recess.

[0024]

As described above, according to the present invention,
Prior to the material filling step using a liquid phase such as a liquid phase plating step, by supplying a liquid having a strong osmotic power to the fine depressions, a material having a small electric resistivity such as Cu is hollowed in the fine depressions on the base material. (Voids) can be filled.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a manufacturing process of a semiconductor device manufactured by a method for filling a fine dent according to the present invention.

FIG. 2 is a schematic view showing a configuration of an apparatus for performing a liquid phase plating step of the present invention.

FIG. 3 is a graph showing the wetting / penetrating power of nonylphenol / polyoxyethylene / ether.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor base material 2 Insulating film 3 Contact hole 4 Groove 5 Barrier layer 6 Cu layer 10 Tank 12 Plating solution reservoir 13 High osmotic fluid reservoir 14 Pump 15 Filter 17 Pump 18 Filter

Claims (10)

[Claims] 1. A method of filling a material having a material different from that of a substrate into a fine depression on a surface of a substrate through a liquid phase, wherein a wetting force or a penetration force is applied to the plating solution before contacting the substrate with the substrate. And filling the inner surface of the fine dent with a liquid having a strong indentation. 2. The method according to claim 1, wherein an opening width of the fine depression is not less than 50 ° and less than 10,000 °. 3. The ratio of the opening width to the depth of the fine recess is:
The method according to claim 1, wherein the value is 0.1 or more and less than 1.0. 4. The method according to claim 1, wherein the liquid having a strong wetting or osmotic power is a solution of a surfactant and / or hydrofluoric acid. 5. The method according to claim 1, wherein the liquid having a strong wetting or penetrating power is supplied as a mist. 6. The liquid having a strong wetting or osmotic power and / or
2. The method according to claim 1, wherein the temperature of the substrate is in a range from room temperature to 100 ° C. 7. The method according to claim 1, wherein the substrate is vibrated with energy having a frequency of 25 Hz to 5 MHz when the liquid having a strong wetting or penetrating force is supplied. 8. The method according to claim 1, wherein after filling the material into the fine depression, the surface of the filled material is flattened by chemical mechanical polishing (CMP). 9. A film forming method for depositing a material different from a substrate into a film via a liquid phase inside a fine depression on a surface of a substrate, wherein a film forming liquid is brought into contact with the substrate. A method of forming a film inside the fine cavities, comprising supplying a liquid having a strong wetting or osmotic power into the fine cavities to wet the inner surface of the fine cavities. 10. An apparatus for filling a fine dent on the surface of a base material with a material different from the base material via a liquid phase, so that a liquid having a strong wetting or penetrating power and a plating solution can be sequentially supplied into the tank. And, before contacting the plating solution with the substrate, supplying a strong wetting or osmotic liquid in the fine recess,
An apparatus for filling a fine dent, wherein an inner surface of the fine dent is wetted.