JPH11246980A - Plating apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plating apparatus which is capable of packing material, such as copper or copper alloy, having small electrical resistance, into fine recesses, such as grooves for fine wiring, uniformly over the entire surface of a substrate by simple constitution. SOLUTION: This apparatus has a plating vessel 15 forming a plating chamber 12, a holding table 10 for holding the substrate W within the plating chamber and plating liquid supply sections 20a and 20b for forming the vortex flow of the plating liquid along the surface to be plated of the substrate within the plating chamber. The plating chamber has a plating liquid discharge port 22 in the position offcentered from the center near the center of the surface to be plated of the substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plating apparatus for a substrate, and more particularly to a filling method and apparatus for filling a wiring groove or the like formed in a semiconductor substrate with a metal such as copper (Cu).

[0002]

2. Description of the Related Art Conventionally, in order to form a wiring circuit on a semiconductor substrate, a film is formed on the substrate surface by sputtering or the like, and then the film is formed by chemical dry etching using a pattern mask such as a resist. Unnecessary parts were removed.

[0003] Materials for forming a wiring circuit include:
Aluminum (Al) or aluminum alloy is used, but as the degree of integration increases, the wiring becomes thinner,
The increase in current density causes thermal stress and temperature rise.
This becomes more remarkable as Al or the like is diluted by stress migration or electromigration, and eventually there is a risk of disconnection.

Therefore, in order to avoid excessive heat generation due to energization, it is necessary to employ a material having higher conductivity for forming the wiring. Among the current materials, copper (Cu) and silver (Ag) are materials having lower electric resistivity than Al-based materials.

[0005] However, it is difficult to dry-etch Cu or its alloy, and it is difficult to employ the above-described method of forming a pattern after forming the entire surface. Therefore, a process of forming a wiring groove in a predetermined pattern in advance and filling the groove with Cu or an alloy thereof may be considered. According to this, a step of removing the film by etching is unnecessary, and a polishing step for removing a surface step may be performed. Further, there is an advantage that a portion called a plug that connects the upper and lower sides of the multilayer circuit can be formed at the same time.

[0006]

However, the shape of such a wiring groove or plug has a considerably high aspect ratio (ratio of depth to diameter or width) as the wiring width becomes finer. It was difficult to uniformly fill the metal. Further, a vapor phase growth (CVD) method is used as a film forming means of various materials. However, it is difficult to prepare an appropriate gaseous raw material with Cu or an alloy thereof. However, there is a problem that carbon (C) is mixed into the deposited film to increase the migration property.

Further, a method has been proposed in which a substrate is immersed in a plating solution to perform electroless or electrolytic plating.
Insufficient circulation of liquid and supply of ions to the bottom of the groove or hole, resulting in slower film growth at the bottom than at the edge of the groove, resulting in a clogging of the top of the groove and a void at the bottom. For example, uniform filling was difficult.

For this reason, it is conceivable that the relative rotation of the substrate and the plating solution promotes the inflow of the plating solution into the fine depressions on the substrate surface or the flow of the metal ions to be plated. In this case, it is necessary to separately provide a mechanism or the like for relatively rotating the substrate and the plating solution, which not only complicates the apparatus, but also causes a stagnation of the plating solution almost in the center of the plating chamber, The plating film thickness and plating characteristics in the central part of the substrate are different from those in the peripheral part.

The present invention has been made in view of the above circumstances, and a material having a small electric resistance such as copper or a copper alloy is uniformly applied to a fine recess such as a fine wiring groove over the entire surface of a substrate by a simple structure. An object is to provide a plating apparatus that can be filled.

[0010]

According to a first aspect of the present invention, there is provided a plating container for forming a plating chamber, a holding table for holding a substrate inside the plating chamber, and plating of the substrate in the plating chamber. A plating solution supply unit that forms a vortex flow of the plating solution along the surface, wherein the plating chamber has a plating solution discharge port near the center of the surface to be plated of the substrate and at a position eccentric from the center. It is a characteristic plating apparatus.

Thus, a vortex flow of the plating solution is formed along the surface to be plated of the substrate to promote the inflow of the plating solution into the fine depressions on the substrate surface or the flow of metal ions to be plated. By discharging the plating solution to the outside from a position near the center of the surface to be plated and eccentric from the center,
It is possible to prevent stagnation of the plating solution at the center of the surface to be plated.

The invention according to claim 2 is characterized in that a rotating body is rotatably housed in the plating chamber, and the plating solution discharge port is provided in the rotating body. It is a plating apparatus of description. Thus, the position of the plating solution discharge port changes with the rotation of the rotating body, so that the position of the discharge port, which is a singular point, can be changed to reduce the effect.

The invention according to claim 3 is the plating apparatus according to claim 2, wherein the rotating body is provided with a rotating mechanism for rotating the rotating body by a plating solution flow. . Thus, the rotating body can be rotated using the fluid force of the plating solution introduced into the plating chamber.

According to a fourth aspect of the present invention, a plurality of the plating solution outlets are provided at positions eccentric from the center of the plating chamber, and switching means for selectively switching these plating solution outlets is provided. The plating apparatus according to claim 1, wherein: Thus, by alternately discharging the plating solution in the plating chamber from a position eccentric from the center of the plating chamber, it is possible to disperse the singularity and reduce the influence.

According to a fifth aspect of the present invention, after plating using the plating apparatus according to any one of the first to fourth aspects, unnecessary portions of the metal adhered to the substrate are polished by a chemical / mechanical polishing apparatus. And removing the substrate.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIGS. 1 and 2 show a plating apparatus according to a first embodiment. The plating apparatus includes a base 10 having a circular substrate holding surface 10a for mounting and holding a substrate W, and a base 10 having a circular shape. And a rectangular top plate (cap) 14 that forms a plating chamber 12 extending horizontally in a disc shape between the base 10 and the base 10 in a watertight manner. . This top plate 14
Is provided so that the plating chamber 12 can be opened and closed with respect to the base 10 by, for example, a hinge or the like, thereby facilitating the taking in and out of the substrate W and maintenance.

The cap 14 comprises a cap body 16 and a block 18 watertightly connected to the upper end surface of the camping body 16. The cap body 16 has a lower top plate portion 17a and a disk portion 17a. And a cylindrical portion 17b extending upward from the center of the cylinder. The substrate W is fixed to the substrate holding surface 10a by a cap 14 via a packing 19. A concave portion 16a is provided on the lower surface of the disk portion 17a,
A plating chamber 12 is formed between this and the substrate holding surface 10a. A hollow portion 16 extending along the axis of the cylindrical portion 17b and opening to the concave portion 16a via a tapered portion 16c is provided.
b is provided.

The cap body 16 is provided with a pair of plating solution introduction passages 20a and 20b for introducing a plating solution from the tangential direction into the plating chamber 12, and inside the block 18, a plating solution communicating with the hollow portion 16b. A liquid discharge path 22 is provided. Outside the plating container 15, the plating solution discharge passage 22 communicates with the suction side of the pump 26, branches off at the discharge side of the pump 26, and flows through the plating solution introduction passages 20a, 20b via flow controllers 28a, 28b, respectively. Is provided with a plating solution supply device 21 having a plating solution circulation line 24 connected to the plating solution.

Thus, with the driving of the pump 26,
A plating solution is introduced into the plating chamber 12 from the plating solution supply paths 20a and 20b. At this time, the plating solution is applied to the plating chamber 12.
Flows in the directions facing each other along the peripheral wall of the plating chamber 12, a rotating force is applied to the plating solution in the plating chamber 12, swirls, flows upward from substantially the center of the plating chamber 12, and is discharged to the outside.

Inside the plating chamber 12, a rotating body 35 having a disk portion 30, a tapered portion 32 and a shaft portion 34 is rotatably accommodated. That is, the shaft portion 34 is
b, and is supported by bearings 36a and 36b such as magnetic bearings disposed between the two.

Inside the rotating body 35, there is provided a plating solution internal passage 38 which connects the plating chamber 12 with the plating solution discharge passage 22. The plating solution internal passage 38 is provided in the disc portion 3.
The lower portion 0 is open at a position eccentric from the center, extends the tapered portion 32 spirally toward the center, and then extends inside the shaft portion 34 along the axis. Also,
A plurality of blades 40 for rotating the rotating body 35 by the flow of the plating solution introduced into the plating chamber 12 are radially arranged on the lower surface of the disk portion 30.

The operation of the plating apparatus configured as described above will be described for the case of plating Cu or an alloy thereof for forming a wiring circuit on a semiconductor substrate. As shown in FIG. 3A, a substrate W to be processed includes a conductive layer 52 and SiO ₂ on a semiconductor substrate 50 on which a semiconductor element is formed.
After depositing an insulating layer 54 made of Ti, a contact hole 56 and a trench 58 for wiring are formed by lithography and etching technology, and a barrier layer 6 made of TiN or the like is formed thereon.
0 is formed.

After the substrate W is placed on the substrate holding surface 10a of the base 10 and covered with the cap 14, the pump 2
6, the plating solution is circulated from the plating solution supply paths 20a and 20b to the plating chamber 12, the plating solution discharge path 22, and the pump 26. The plating solution introduced from the tangential direction into the plating chamber 12 forms a vortex in the plating chamber 12 and flows on the upper surface of the substrate W to perform plating on the surface.

The plating solution collides with the blades 40 and, in the course of flowing through the plating solution internal passage 38, applies its rotational force to the rotating body 38 to rotate it in one direction. Since the suction port 38a is located near the center of the plating chamber 12 and is eccentric from the center, the plating chamber 12 is formed while forming a vortex.
In particular, stagnation of the plating solution at the center is prevented. Also,
Since the rotating body 38 is rotating at a predetermined radius, the suction port 3
The position of 8a changes, and the unevenness due to the position in the circumferential direction is also corrected.

By the steps described above, as shown in FIG. 3B, the contact hole 56 and the groove 5 of the substrate W are formed.
The flow of the plating solution into the inside 8 or the flow of the metal ions to be plated is promoted, and at the same time, the gas generated by plating on the surface of the substrate W is quickly removed. Therefore, the contact hole 56 and the groove 58 of the semiconductor substrate W are filled with Cu, and the Cu layer 62 is deposited on the insulating film 54.

As described above, by rotating the rotating body 38 using the force of the flow of the plating solution itself, it is possible to reduce the size and size of the apparatus without providing a separate driving apparatus.
In addition, the plating solution is discharged from the substantially central portion of the plating chamber 12 so that the plating solution is removed from the plating chamber 12 and thus the substrate W.
Can be prevented from stagnating at the center of the camera.
In this embodiment, the generation of particles from the bearing can be suppressed by rotatably supporting the rotating body 30 via the magnetic bearing.

Thereafter, the Cu layer on the insulating film 54 is removed by chemical mechanical polishing (CMP) to remove the surface of the Cu layer 62 and the surface of the insulating film 54 filled in the contact hole 56 and the groove 58 for wiring. And the same. As a result, a wiring made of the Cu layer 62 is formed as shown in FIG.

FIGS. 4 and 5 show a plating apparatus according to a second embodiment of the present invention. This plating apparatus comprises a rectangular base having a circular substrate holding surface 70a for holding a substrate W. And a plating chamber 7 which covers the upper portion of the base 70 in a water-tight manner and extends horizontally in a disk shape between the base 70 and the plating chamber 7.
2 is mainly composed of a rectangular cap 74 forming the second cap. A circular recess 76 is formed in the center of the lower surface of the cap 74.

The cap 74 has a pair of plating solution introduction passages 80a and 80b for introducing a plating solution into the plating chamber 72 from a side tangential direction, and a pair of eccentric positions formed from the center of the recess 76. It has plating solution discharge paths 82a and 82b. Then, the respective plating solution introduction paths 80a, 80
b is connected to the discharge side of the pump 86 of the plating solution circulation line 84 via flow controllers 88a and 88b, and the plating solution discharge paths 82a and 82b are also connected to the suction side of the pump 86 via on-off valves 90a and 90b. Connected to each other.

In the plating apparatus of this embodiment,
Plating is performed while opening and closing valves 90a and 90b alternately at predetermined timings. As a result, the plating solution that has flowed along the peripheral wall of the plating chamber 72 from the plating solution supply passages 80a and 80b in opposition to each other with the driving of the pump 86 is alternately discharged from the two plating solution discharge passages 82a and 82b. Therefore, the discharge paths 82a and 82b which are singular points with respect to the flow of the plating solution are not fixed, and the influence of such singular points can be minimized.

[0031]

As described above, according to the present invention,
A vortex of the plating solution is formed along the surface of the substrate to be plated, so that the plating solution flows into the fine depressions on the substrate surface or promotes the flow of metal ions to be plated, and near the center of the surface to be plated. In addition, the plating solution is discharged to the outside from a position eccentric from the center, and it is possible to prevent the stagnation of the plating solution from occurring in the center of the surface to be plated. Accordingly, a material having a low electric resistance such as copper or a copper alloy is uniformly and efficiently formed over the entire surface of the substrate by a simple structure in a fine depression such as a fine wiring groove. The present invention can provide a useful technique for promoting the practical use of a semiconductor integrated circuit having a higher density.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view (a cross-sectional view taken along the line AA in FIG. 2) illustrating an overall outline of a plating apparatus according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along line BB of FIG.

FIG. 3 is a cross-sectional view illustrating an example of a step of performing plating by the plating apparatus of the present invention.

FIG. 4 is a cross-sectional view (a cross-sectional view taken along the line CC in FIG. 5) illustrating an overall outline of a plating apparatus according to a second embodiment of the present invention.

FIG. 5 is a sectional view taken along line DD of FIG. 4;

[Explanation of symbols]

 10, 70 Base 12, 72 Plating chamber 14, 74 Cap 15 Plating container 20a, 20b, 80a, 80b Plating solution introduction path 21 Plating solution supply device 22, 82a, 82b Plating solution discharge path 30 Disk part 32 Rotating body 38 Plating solution internal passage 40 Blade 90a, 90b On-off valve

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Akihiro Jia 4-2-1 Motofujisawa, Fujisawa-shi, Kanagawa Inside Ebara Research Institute, Ltd.

Claims (5)

[Claims] 1. A plating container for forming a plating chamber, a holding table for holding a substrate inside the plating chamber, and plating for forming a vortex flow of a plating solution along a surface to be plated of the substrate in the plating chamber. A plating solution supply unit, wherein the plating chamber has a plating solution discharge port near the center of the surface to be plated of the substrate and at a position eccentric from the center. 2. The plating apparatus according to claim 1, wherein a rotator is rotatably housed in the plating chamber, and the plating solution discharge port is provided in the rotator. 3. The plating apparatus according to claim 2, wherein the rotating body is provided with a rotating mechanism for rotating the rotating body by a plating solution flow. 4. The plating solution discharge port is provided in a plurality of positions eccentric from the center of the plating chamber, and a switching means for selectively switching these plating solution discharge ports is provided. Item 2. A plating apparatus according to Item 1. 5. After plating using the plating apparatus according to claim 1, unnecessary portions of the metal adhered to the substrate are removed by polishing with a chemical / mechanical polishing apparatus. Substrate processing method.