JPH1197392A - Method and system for filling fine recess - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accelerate filling of fine recesses with ultrafine particles by supplying a material of ultrafine particle onto the surface of a basic material having fine recesses and applying ultrasonic vibration to the ultrafine particles thereby crushing an aggregation of ultrafine particles having a local bond again. SOLUTION: Valves V2, V3 are opened to supply a carrier gas into a chamber 12 from a carrier gas cylinder 19 through a storage tank 18 and to supply ultratine particles of Cu, or the like, onto the surface of a semiconductor substrate 1 from a supply nozzle 17. After pressure in the chamber 12 is regulated, an ultrasonic oscillator 16 is actuated to apply an ultrasonic wave to the semiconductor substrate 1. Ultrasonic wave is applied to an aggregation of ultrafine particles having a significantly high ratio of surface area and a local bond produced through mutual aggregation/cohesion through the semiconductor substrate 1 and thus vibrating and crushing the ultrafine particles again (microcrushing). According to the method, filling of fine recesses with ultrafine particles is accelerated and the recesses can be filled with a material having low electric resistivity, e.g. Ci, without forming any cavity.

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 a fine dent, which can be filled with a material having a small electric resistivity such as a copper alloy.

[0009]

In order to achieve the above-mentioned object, a filling method according to the present invention supplies a material of ultrafine particles to the surface of a substrate having fine depressions and applies ultrasonic vibration to the ultrafine particles. Meanwhile, a predetermined material is filled into the fine depressions.

The filling apparatus of the present invention further comprises a supply nozzle for supplying a material of ultrafine particles to the surface of a substrate having fine depressions, and an ultrasonic wave for applying ultrasonic vibration to at least one of the substrate and the ultrafine particles. And a vibrator.

According to the present invention, ultrafine particles are supplied to the surface of a substrate having fine depressions, and ultrasonic vibrations are applied to the ultrafine particles to regenerate ultrafine particle aggregates which have been locally bonded to each other. It can be crushed, and can promote the filling of ultrafine particles into the fine depressions.

[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 filling step according to the present invention, FIG.
As shown in (b), the contact hole 3 of the semiconductor substrate 1
And grooves 4 are filled with Cu and Cu is
Layer 6 is deposited. After that, chemical mechanical polishing (CM
By P), the Cu layer on the insulating film 2 is removed, and the surface of the Cu layer 6 filled in the contact hole 3 and the wiring groove 4 and the surface of the insulating film 2 are made substantially flush. 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 filling step of the filler according to the present invention. As shown in FIG. 2, the chamber 12 is connected to a vacuum pump 13 via a valve V1, and the inside thereof can be evacuated. A susceptor 15 having a heater 14 therein is provided in the chamber 12. The susceptor 15 is connected to the ultrasonic vibrator 16. Susceptor 1
A supply nozzle 17 is provided above the semiconductor substrate 1 on the top 5. The supply nozzle 17 is connected via a valve V2 to a storage tank 18 for storing ultrafine particles made of Cu or the like. The storage tank 18 has a carrier gas cylinder 1
9 is supplied with carrier gas.

Next, the step of filling the fine recesses of the semiconductor substrate 1 with copper using the apparatus shown in FIG. 2 will be described with reference to FIG. In step 1 (S1), the semiconductor substrate 1 is charged into the chamber 12. Next, in step 2 (S2), the valve V1 is opened and the vacuum pump 13 is operated to evacuate the chamber 12.

Next, in step 3 (S3), the valves V2 and V3 are opened and the carrier gas is supplied from the carrier gas cylinder 19 into the chamber 12 via the storage tank 18. Thereby, the ultrafine particles made of Cu or the like are supplied from the supply nozzle 17 to the surface of the semiconductor substrate 1. In this case, the average particle size of the ultrafine particles is 30 ° to 0.1 μm.
Next, in step 4 (S4), the pressure in the chamber 12 is adjusted by appropriately adjusting the opening of the valves V1 to V3 while keeping the vacuum pump 13 operating. Then, in step 5 (S5), the ultrafine particles are filled into the contact hole 3 and the wiring groove 4 while applying the ultrasonic wave to the semiconductor substrate 1 by operating the ultrasonic vibrator 16. In this case, the ultrasonic vibration has a frequency of 1 to 100 kHz.
z, the amplitude is 1 to 1000 μm. At the time of this filling step, the susceptor 15 may be heated by the heater 14 as needed to increase the fluidity of the ultrafine particles. In addition, apart from the contents shown in FIGS. 2 and 3, the same filling operation may be performed in a state where the ultrafine particles are suspended in a liquid.

FIG. 4 is a schematic diagram showing a state in which ultrafine particles are filled in a fine recess while applying ultrasonic waves to a semiconductor substrate. As shown in FIG. 4, since the ultrasonic waves are applied to the semiconductor substrate 1, the ultrafine particles P vibrate. In general, ultrafine particles have a remarkably large ratio of surface area to volume,
Although local aggregation (cross-linking) is likely to occur due to mutual aggregation and cohesion, the ultrafine particle aggregates that have caused local bonding to each other are re-crushed (micro-crushed) to fill the inside of the fine dents. Can be promoted. In this case, the fine dent has a width W of 1 μm or less and an aspect ratio of 1 to 10 which is a ratio of the depth h to the width W. The surface of the fine depression is made of metal nitride or the like.

Even if there is an oxide film on the surface of the substrate that prevents the adhesion of metal, the oxide film is destroyed and removed by the action of a strong ultrasonic impact. Although there are many unknowns about the mechanism of film breakage, it is presumed that in the presence of an aqueous solution, strong ultrasonic vibrations cause cavitation in the liquid and the resulting high pressure destroys the film. . Although not shown in FIG. 2, the ultrafine particles may be supplied to the substrate in a state of being suspended in an aqueous solution or another liquid.

In the present invention, it suffices to apply an ultrasonic impact to the ultrafine particles, and the ultrafine particles may be present alone or may be suspended in an aqueous solution or the like. FIG. 5 is a schematic diagram showing an example in which the suspended ultrafine particles P in an aqueous solution are vibrated. In the example shown in FIG. 5, the ultrasonic transducer 16 is brought into contact with the suspended ultrafine particles P on the semiconductor substrate 1 to apply ultrasonic waves to the ultrafine particles.

In the description of the present embodiment, the case where copper is filled in the fine depression is described. However, by applying the present invention, silver (Ag), gold (Au), and platinum (P
t) and a material having a small electric resistivity composed of these alloys can be filled.

Since the present invention is configured as described above, the following effects can be obtained. The present invention is also applicable to a combination of a material base material and a deposition material that cannot be filled by other conventional methods such as plating. When applying ultrasonic waves in a vacuum, the base material and the filler come into direct contact with each other and adhere at room temperature, so that the adhesion is large. Since the ultrafine particles have a lower melting point than the bulk material, even if the filler has a defect, the defect can be eliminated by heating at a low temperature after filling. Since dry processing is possible at room temperature, it can be kept clean. That is, (1) In the case of filling by a normal dry process such as CVD or PVD, it is necessary to maintain the atmosphere at a temperature much higher than room temperature. At high temperatures, the chemical reaction on the material surface becomes extremely active, so if a trace amount of oxygen is present, local oxidation of the surface of the filling part and the inner wall of the chamber, material deterioration, and adhesion of suspended particles and molecules to the surface Violently. (2) In a wet process such as liquid phase plating, most of the inner wall of the chamber and the base material are buried in the liquid, so that cleaning after filling is troublesome and troublesome.
Since the process of the present invention can avoid the above-mentioned (1) and (2), the cleanliness is improved.

[0022]

As described above, according to the present invention,
By supplying the material to the surface of the base material in the form of ultrafine particles and applying ultrasonic vibration to the ultrafine particles, a material (such as Cu) having a small electrical resistivity, such as Cu, is formed in a void in a fine depression on the base material. Can be filled without the need.

[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 filling step of a filler according to the present invention.

FIG. 3 is a process chart showing a filling step of a filler according to the present invention.

FIG. 4 is a schematic diagram showing a state in which ultrafine particles are filled in a fine depression while applying ultrasonic waves to a semiconductor substrate.

FIG. 5 is a schematic view showing an example in which suspended ultrafine particles in an aqueous solution are vibrated.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor base material 2 Insulating film 3 Contact hole 4 Groove 5 Barrier layer 6 Cu layer 12 Chamber 13 Vacuum pump 14 Heater 15 Susceptor 16 Ultrasonic transducer 17 Supply nozzle 18 Storage tank 19 Carrier gas cylinder P Ultrafine particles V1, V2, V3 Valve

Claims (9)

[Claims] An ultrafine particle material is supplied to the surface of a substrate having fine depressions, and a predetermined material is filled into the fine depressions while applying ultrasonic vibration to the ultrafine particles. Filling method for micro pits. 2. The method according to claim 1, wherein the fine dent has a width of 1 μm or less and an aspect ratio of 1 to 10. 3. The ultrasonic vibration has a frequency of 1 to 100.
2. The method according to claim 1, wherein the frequency is 1 kHz and the frequency is 1 to 1000 [mu] m. 4. The ultrafine particles have an average particle size of 30 ° to 0.1 °.
2. The method according to claim 1, wherein the thickness is 1 [mu] m. 5. The method according to claim 1, wherein the substrate is a semiconductor substrate. 6. The material of the ultrafine particles is made of copper, silver, platinum, or an alloy thereof.
A method for filling the fine dents according to the above. 7. The method according to claim 1, wherein the surface of the fine depression is a metal nitride. 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 supply nozzle for supplying a material of ultrafine particles to a surface of a substrate having fine depressions, and an ultrasonic vibrator for applying ultrasonic vibration to at least one of the substrate and the ultrafine particles. A filling device for a fine depression.