JP2001150333A - Polishing pad - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a good circuit pattern by preventing generation of variations in wiring film thickness in finishing of polishing and avoiding the reduction of the wiring sectional area caused by the lack of a wiring pattern. SOLUTION: In this polishing pad 1 provided with a pad body 2 having an upper layer member 3 to be pressed to and brought into contact with a semiconductor wafer W and a lower layer member 4 abutting on the upper layer member 3, and for rotationally polishing the semiconductor wafer W by dropping slurry onto the pad front surface 2a, many discharge holes 2b opening on the pad front surface 2a are provided on the pad body 2, many discharge passages 4a communicated with respective discharge holes 2b are provided, and respective discharge passages 4a are positioned below the upper layer member 3 and opened in the direction of the pad rotational surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing pad suitable for polishing a wafer surface in a semiconductor device manufacturing process.

[0002]

2. Description of the Related Art In recent years, with the increasing integration and density of semiconductor devices, a technique for flattening a wafer surface with high precision has been required. One of such wafer planarization techniques is a chemical mechanical polishing (CMP) method. In this method, a wafer is pressed against a rotating polishing pad, and the surface of the wafer is polished with the polishing pad while supplying a chemical polishing liquid (slurry).

Conventionally, in this type of CMP method, a polishing pad as shown in FIG. 3 is employed. The polishing pad will be described with reference to the figure. In the figure, the polishing pad indicated by reference numeral 31 has a pad body 32 and is mounted on a platen (not shown).

[0004] The pad body 32 has an upper layer member 33 and a lower layer member 34. The upper layer member 33 is formed by a polishing layer that is pressed against and comes into contact with an object to be polished (semiconductor wafer). The upper layer member 33 is provided with a large number of concave holes 33a opened on the pad surface 32a of the pad body 32. Slurry or waste liquid is stored inside each concave hole 33a. The lower layer member 34 is formed by a base layer adjacent to the upper layer member 33.

In order to polish a semiconductor wafer as an object to be polished using such a polishing pad 31, a semiconductor wafer is mounted on an upper surface plate (wafer support) and a polishing pad is mounted on a lower surface plate (platen). After mounting the base 31, the upper and lower bases are rotated in opposite directions, and the upper and lower bases are relatively moved toward the pad surface while pressing the surface of the semiconductor wafer against the pad surface 32a.

At this time, the pad surface 3 of the pad body 32
The slurry is dropped on 2 a and supplied between the surface of the semiconductor wafer and the pad surface 32 a of the pad body 32.
After the surface of the semiconductor wafer is polished by the slurry, the slurry flows as waste liquid on the pad surface 32a and is discharged toward the pad surface (in the pad centrifugal direction).

Further, a conventional polishing pad as shown in FIG. 4 is also employed. For this polishing pad,
The polishing pad indicated by reference numeral 41 in FIG. 2 includes a pad body 42 and is mounted on a platen (not shown) similarly to the polishing pad 31 shown in FIG.

The pad body 42 has an upper layer member 43 and a lower layer member 44. The upper layer member 43 is formed by a polishing layer that is pressed against and comes into contact with an object to be polished (semiconductor wafer). The upper layer member 43 is provided with a flat lattice-shaped concave groove 4 that opens in the pad surface direction and the pad plane length and width directions.
By forming 5, a large number of convex portions 46 are provided. The lower layer member 44 is formed by a base layer adjacent to the upper layer member 43.

To polish a semiconductor wafer as an object to be polished using such a polishing pad 41, the polishing pad 3
1, the semiconductor wafer is mounted on the upper platen and the polishing pad 41 is mounted on the lower platen. Then, the upper and lower platens are rotated in directions opposite to each other, and the pad surface (each convex portion) is rotated. The upper and lower platens are relatively moved toward the pad surface while pressing the surface of the semiconductor wafer against the upper surface of the semiconductor wafer (46).

At this time, the slurry is dropped on the pad surface of the pad body 42 and supplied between the surface of the semiconductor wafer and the pad surface of the pad body 42. After the surface of the semiconductor wafer is polished by the slurry, the slurry flows as waste liquid on the pad surface and in the concave groove 45 and is discharged toward the pad surface (pad centrifugal direction).

[0011]

However, in the former case (in which the pad body is provided with a concave hole), a passage for discharging the slurry waste liquid is not formed in the pad body 32,
Therefore, the slurry and the waste liquid were mixed during polishing, and the polishing rate was unstable. On the other hand, in the latter case (a groove provided on the pad body), since the groove 45 in the form of a plane lattice is opened on the pad surface, the corners (edges) of the groove 45 are polished during polishing. The polished object was subjected to stress concentration, and erosion and dishing occurred in the polished object.

As a result, Cu, W or A
When a wiring member such as l is included, not only does the wiring thickness vary at the end of polishing, but also the wiring cross-sectional area decreases in accordance with the loss of the wiring pattern, and a good circuit pattern cannot be obtained. was there.

Japanese Patent Application Laid-Open No. H11-058218 discloses a prior art as "Polishing Pad and Polishing Apparatus", which discloses "a polishing pad having a plurality of through holes for discharging polishing liquid, And a polishing liquid discharge mechanism having a polishing liquid discharge pipe communicating with each of the polishing liquid discharge through-holes. "

The present invention has been made in view of such circumstances, and it is possible to prevent the occurrence of a variation in the wiring film thickness at the end of polishing and to prevent a reduction in the wiring cross-sectional area due to a defective wiring pattern. It is an object of the present invention to provide a polishing pad which can obtain a good circuit pattern.

[0015]

In order to achieve the above object, a polishing pad according to a first aspect of the present invention has an upper layer member which is pressed against and comes into contact with an object to be polished and a lower layer member which is adjacent to the upper layer member. Then, in a polishing pad provided with a pad body for rotating and polishing an object to be polished by dripping slurry onto the pad surface, the pad body is provided with a large number of discharge holes opened on the pad surface and communicates with each of these discharge holes. A large number of discharge paths are provided, and each of these discharge paths is located below the upper layer member and is opened in the pad rotation surface direction. Therefore, the slurry waste liquid flows out of each discharge hole into each discharge path during polishing, and is discharged out of the pad from each discharge path by the action of centrifugal force accompanying the rotation of the pad.

According to a second aspect of the present invention, in the polishing pad of the first aspect, each of the discharge holes is formed of a round hole formed over the upper layer member and the lower layer member.
Therefore, each discharge hole is formed by performing a round hole processing on the upper layer member and the lower layer member.

The third aspect of the present invention is the first or second aspect.
In the polishing pad described above, each discharge path is configured by a concave groove that opens on a surface opposite to the layer surface of the lower layer member. Therefore, each discharge path closes the opening on the side opposite to the layer surface of the lower layer member in the pad use state and opens only in the layer surface direction of the lower layer member.

According to a fourth aspect of the present invention, in the polishing pad according to the first, second or third aspect, the respective discharge paths are arranged at positions parallel to each other. Therefore, at the time of polishing, the slurry waste liquid flows along each discharge path, and is discharged from each of these discharge paths in the layer surface direction of the lower layer member.

According to a fifth aspect of the present invention, in the polishing pad according to any one of the first to fourth aspects, the opening size of each discharge hole and the opening size of each discharge path are set to the same size. There is a set configuration. Therefore, at the time of polishing, the flow of the slurry waste liquid from each discharge hole to each discharge path is performed smoothly.

According to a sixth aspect of the present invention, in the polishing pad according to any one of the first to fifth aspects, the lower layer member is formed of a continuous foaming resin.
Therefore, the slurry waste liquid flows out of each discharge hole at the time of polishing, and then is discharged to the outside of the pad through each discharge path and the lower layer member.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described.
This will be described with reference to the drawings. FIGS. 1A and 1B are a perspective view and a sectional view showing a polishing pad according to a first embodiment of the present invention, and FIG. 2 is a front view showing a use state of the polishing pad according to the first embodiment of the present invention. FIG. In FIGS. 1 and 2, the polishing pad denoted by reference numeral 1 includes a pad body 2 and is mounted on a platen (lower surface plate) 21.

As shown in FIG. 2, an upper surface plate 22 having a wafer support table 22a is disposed above the platen 21. A semiconductor wafer W as an object to be polished is mounted on a wafer support 22 a of the upper surface plate 22. Reference numeral 23 denotes a pad surface 2a of the pad body 2 during polishing.
Is a nozzle for dropping the slurry.

The pad body 2 has an upper layer member 3 and a lower layer member 4. The upper layer member 3 is formed by a polishing layer made of a closed-cell foaming urethane (for example, “IC1000 manufactured by Rodale”) or the like that comes into contact with the object to be polished (semiconductor wafer). The upper layer member 3 is provided with a large number of discharge holes 2 b opening on the pad surface 2 a of the pad body 2 over the lower layer member 4. Each discharge hole 2b is formed by a round hole having an axis in a direction perpendicular to the layer surface of the upper layer member 3 (lower layer member 4). This prevents the semiconductor wafer W from being subjected to stress concentration from the edge of the discharge hole 2b during polishing.

The lower layer member 4 is formed of a base layer made of a closed cell urethane or the like adjacent to the upper layer member 3. The lower layer member 4 is provided with a large number of discharge paths 4a, which are located at positions parallel to each other and communicate with some of the discharge holes 2b. Each discharge path 4a opens in the direction of the pad rotation surface of the pad body 2 (the peripheral surface of the lower layer member 4), and is opposite to the pad surface 2a (the lower layer member 4).
(The surface opposite to the layer surface). As a result, the centrifugal force associated with the rotation of the pad during polishing acts on the waste liquid in each discharge path 4a, and these waste liquids are discharged from the discharge path 4a to the outside of the pad (in the plane of the pad).

The groove width of each discharge passage 4a and each discharge hole 2b
When the pore diameter is too small, sufficient conductance for drainage of slurry waste liquid or the like cannot be obtained, and when it is too large, sufficient pad hardness cannot be obtained. It is desirable that the size is set to about 7 mm (discharge path).

The formation of each discharge passage 4a is determined by each discharge hole 2a.
After bonding the upper layer member 3 and the lower layer member 4 so as to communicate with each other, the pad surface 2a of the opening of each discharge path 4a
The lower layer member 5 is attached to a platen (lower surface plate) 21 so as to close the opening on the opposite side to the above.

The object to be polished is polished using the polishing pad 1 having the above-described structure in the same manner as in the prior art. That is, after mounting the semiconductor wafer W as an object to be polished on the upper platen 22 and mounting the polishing pad 1 on the lower platen 21, the upper and lower platens 21 and 22 are rotated in directions opposite to each other, and While pressing the surface of the semiconductor wafer W against the pad surface 2 a of the pad body 2,
22 is relatively moved toward the pad surface.

At this time, the pad surface 2a of the pad body 2
When the slurry is dropped from the nozzle 23, the slurry is supplied between the surface to be polished of the semiconductor wafer W and the polishing surface (pad surface 2a) of the pad body 2. Then, after the surface of the semiconductor wafer W is polished with the slurry, the slurry flows as waste liquid from the pad surface 2a into the discharge hole 2b and flows out into the discharge path 4a. (Pad centrifugal direction).

Therefore, in the present embodiment, a passage for discharging the waste slurry is ensured in the pad body 2, so that the slurry and the waste are not mixed during the polishing as in the prior art, and a stable polishing rate is obtained. be able to. Further, in the present embodiment, since a part of the path for discharging the waste liquid of the slurry is the discharge hole 2b (round hole) opened on the pad surface 2, the object to be polished is removed from the edge of the discharge hole 2b during polishing. There is no stress concentration, and no erosion or dishing occurs on the object to be polished.

In this embodiment, the case where the lower layer member 4 has the discharge path 4a as a path for discharging the waste liquid of the slurry has been described. However, the present invention is not limited to this, and the lower layer member may be formed of a continuous foaming material. If it is formed of polyurethane or nonwoven fabric, the waste liquid of the slurry is discharged from the pad surface to the outside through the discharge hole and the lower layer member, so that it is not necessary to form a discharge path in the pad body. Is formed of continuous foaming polyurethane or the like, and a discharge passage is formed in this lower layer member, whereby the discharge effect can be further enhanced.

In this embodiment, the upper layer member 3
And a discharge hole 2b opening on the pad surface 2a across the lower layer member 4 and in a direction perpendicular to the surface opposite to the layer surface of the lower layer member 4 and in a direction parallel to the pad surface direction (with the peripheral surface of the lower layer member 4). Discharge path 4 opening at right angles)
Although the case where a is provided in the lower layer member 4 has been described, the present invention is not limited to this, and the upper layer member is provided with a discharge hole opened on the pad surface and the layer surface, and in a direction parallel to the pad surface direction and the layer surface of the lower layer member. The same effect as that of the embodiment can be obtained by providing the lower layer member with a discharge path (not opening the mounting surface of the pad body to the platen) that opens to the bottom.

[0032]

As described above, according to the present invention, the pad body is provided with a large number of discharge holes opened on the pad surface, and a large number of discharge paths communicating with the respective discharge holes are provided. Since the passage is located below the upper layer member and is opened in the direction of the pad rotation surface, the slurry waste liquid flows out from each discharge hole to each discharge passage during polishing, and each discharge passage is operated by centrifugal force accompanying the pad rotation. From the pad.

Therefore, since a path for discharging the waste liquid of the slurry is secured in the pad body, the slurry and the waste liquid are not mixed at the time of polishing as in the prior art, and a stable polishing rate can be obtained. In addition, since a part of the passage for discharging the waste liquid of the slurry is a discharge hole opened on the surface of the pad, the object to be polished is not subjected to stress concentration from the edge of each discharge hole during polishing. Erosion and dishing do not occur.

Therefore, it is possible to prevent the occurrence of variations in the wiring film thickness at the end of polishing and to prevent the reduction of the wiring cross-sectional area due to the loss of the wiring pattern. Can be.

[Brief description of the drawings]

FIGS. 1A and 1B are a perspective view and a sectional view showing a polishing pad according to a first embodiment of the present invention.

FIG. 2 is a front view showing a use state of the polishing pad according to the first embodiment of the present invention.

FIG. 3 is a perspective view showing a conventional polishing pad (1).

FIG. 4 is a perspective view showing a conventional polishing pad (2).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Polishing pad 2 Pad main body 2a Pad surface 2b Discharge hole 3 Upper layer member 4 Lower layer member 4a Discharge path 21 Lower platen 22 Upper platen 22a Wafer support 23 Nozzle W Semiconductor wafer

Claims (6)

[Claims] 1. A polishing apparatus comprising: an upper layer member which comes into contact with an object to be polished by pressing, and a lower layer member adjacent to the upper layer member; and a pad body which is provided with a slurry which is dropped on a pad surface and rotationally polishes the object to be polished. In the pad, the pad main body is provided with a large number of discharge holes opened to the pad surface, and a large number of discharge paths communicating with the respective discharge holes are provided, and each of the discharge paths is located below the upper layer member. A polishing pad characterized by being opened in the direction of the pad rotation surface. 2. The polishing pad according to claim 1, wherein each of the discharge holes comprises a round hole formed over the upper layer member and the lower layer member. 3. The polishing pad according to claim 1, wherein each of the discharge paths comprises a concave groove opened on a surface opposite to a layer surface of the lower layer member. 4. The polishing pad according to claim 1, wherein said discharge paths are arranged at positions parallel to each other. 5. The polishing pad according to claim 1, wherein an opening dimension of each of the discharge holes and an opening dimension of the discharge path are set to be equal to each other. . 6. The polishing pad according to claim 1, wherein the lower layer member is formed of a continuous foaming resin.