JPH09277163A - Polishing method and polishing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain the even penetration of a polishing fluid into a gap between a polishing object and a polishing pad and lessen polishing unevenness by forming a groove on the surface of a surface plate and mounting the polishing pad thereon for implementing a polishing process. SOLUTION: A spiral groove 40 is formed on the surface of a surface plate 10 in the direction from a center toward an outer end. The groove 40 is formed to have breadth and depth larger than the thickness of a polishing pad 12, and the edge of the groove 40 on the surface plate surface is chamfered to have curvature. In this case, the cross sectional form of the groove 40 is not limited specifically, but may have a V-shaped form, a U-shaped form, an inverted trapezoidal form or the like. Also, the gap of the spiral groove 40 is not limited specifically, but too small a gap hinders sufficient grinding. On the contrary, too large a gap causes insufficiency in the even penetration of a polishing fluid.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing method and a polishing apparatus capable of satisfactorily polishing a surface of an object to be polished such as a wafer.

[0002]

2. Description of the Related Art In an LSI manufacturing process, for example, it is important to flatten an interlayer insulating film or another film. Although various means have been proposed as a technique for planarization, in recent years, a CMP (Chemical Mechanical Polishing) method applying a mirror polishing technique for a silicon wafer has attracted attention and is being utilized. Have been developed.

For example, the conventional polishing apparatus shown in FIG. 7 has a surface plate 10 having a polishing pad 12 mounted on its surface and a wafer holder 20 having a porous chuck 22.
The surface plate 10 rotates about the rotation axis 14, while the wafer holder 20 rotates about the rotation axis 24. The wafer 1 is held by the wafer holder 20 by being attracted to the porous chuck 22 that is evacuated (26).
Then, the polishing liquid containing abrasive grains is supplied from the nozzle 30 to the polishing pad 1.
When the surface plate and the wafer holder 20 are rotated while being supplied onto the surface 2, the surface 1a (lower surface in the figure) of the wafer 1 is polished by the CMP method.

[0004]

However, in the conventional polishing apparatus, the surface of the surface plate is formed flat. Therefore, when the polishing pad is mounted on this surface and the wafer is pressed against the surface, the polishing liquid is removed. There is a problem that the polishing rate in the plane of the wafer becomes non-uniform because it does not penetrate uniformly between the wafer and the wafer. Therefore, it has also been attempted to form a groove on the polishing pad to improve the permeability of the polishing liquid, but there is a problem that the fibers are likely to jump out and cause polishing scratches because the edges of the groove are sharply cut. there were. Also,
Since the polishing pad is a consumable item, there is a problem in that it is costly to groove all the polishing pads.

The present invention has been made in view of the above situation, and enhances the uniformity of penetration of a polishing liquid between an object to be polished such as a wafer and a polishing pad to reduce unevenness in polishing,
An object of the present invention is to provide a polishing method and a polishing apparatus that are excellent in planarization in-plane uniformity.

[0006]

In order to achieve the above object, a polishing method of the present invention is such that a polishing surface of an object to be polished is pressed against a polishing pad, and a polishing liquid is provided between the polishing surface and the polishing pad. In the polishing method for polishing the polishing surface while supplying the polishing surface, a groove is formed on the surface plate surface on which the polishing pad is mounted, and the polishing pad is mounted on the surface plate surface for polishing. .

When a polishing pad is mounted on a surface plate having grooves formed on its surface, the polishing pad is partially recessed following the grooves on the surface of the surface plate. Therefore, an object to be polished is pressed against this polishing pad for polishing. If done, the polishing liquid will sufficiently penetrate into the recessed portion. As a result, the in-plane polishing rate of the object to be polished becomes uniform, the unevenness of polishing is small, and the polishing object having excellent in-plane uniformity of planarization can be obtained.

In the polishing method of the present invention, it suffices to mount the polishing pad on the surface of the surface plate and press the object to be polished. It is more preferable to perform polishing in a state where the polishing pad is pressed along the groove and grooves are formed in the polishing pad. This is because if the polishing pad is made to follow the grooves on the surface of the surface plate in advance before polishing, the permeation uniformity of the polishing liquid is further enhanced.

The above object is to provide a polishing apparatus having a polishing pad for pressing a polishing surface of an object to be polished and a surface plate on which the polishing pad is mounted, wherein a groove is formed on the surface of the surface plate. It can also be achieved by a polishing apparatus characterized in that Similar to the above-mentioned polishing method, when a polishing pad is mounted on a surface plate having a groove formed on the surface, the polishing pad partially dents following the groove on the surface plate, so the object to be polished is pushed onto this polishing pad. When applied and polished, the polishing liquid sufficiently penetrates into the recessed portion. As a result, the in-plane polishing rate of the object to be polished becomes uniform, the unevenness of polishing is small, and the polishing object having excellent in-plane uniformity of planarization can be obtained.

In the polishing apparatus of the present invention, the shape of the groove is not particularly limited, and may be formed in a spiral shape from the center of the surface plate to the outer edge, in a lattice shape, or in a radial shape from the center of the surface plate to the outer edge. it can. Further, in the polishing apparatus of the present invention, it is more preferable that the edge of the groove on the surface of the surface plate is chamfered in a curved shape. This is because the copying of the polishing pad becomes smoother and the occurrence of polishing scratches can be prevented.

Further, in the polishing apparatus of the present invention, it is more preferable that the width and the depth of the groove are larger than the thickness of the polishing pad. By doing so, when the polishing pad is made to follow the groove, the polishing pad is sufficiently recessed without protruding from the general surface, and the permeation uniformity of the polishing liquid is further improved.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a polishing apparatus and a polishing method of the present invention will be described in detail with reference to the embodiments shown in the drawings. 1 is a cross-sectional view of an essential part showing an embodiment of a polishing apparatus of the present invention, FIG. 2 is a plan view showing the surface plate of FIG. 1, FIG. 3 is a cross-sectional view of the same surface plate, and FIGS. FIG. 5 is a cross-sectional view of a main part showing a method of attaching a polishing pad, FIG. 5 is a plan view showing another embodiment of a surface plate according to the present invention, and FIG. 6 is a sectional view of the surface plate.

As shown in FIG. 1, the polishing apparatus of this embodiment is an apparatus for polishing the surface 1a of a wafer 1 to be polished, and the polishing apparatus rotates about a rotary shaft 14. It has a surface plate 10 and a wafer holder 20 located above the surface plate 10 and serving as a holding means for holding the wafer 1.

A polishing pad 12 made of a porous viscoelastic material such as foamed polyurethane is attached to the surface of the surface plate 10. The polishing pad 12 is used for polishing the surface 1 of the wafer 1.
It is mounted on the entire surface of the surface plate 10 with an area larger than a.
Then, the polishing liquid is supplied onto the polishing pad 12 from the substantially center of the surface plate 10 by the nozzle 30. The polishing liquid is not particularly limited, and examples thereof include an amine-based polishing liquid or a liquid in which abrasive grains such as powdery silicon oxide SiO ₂ are added if necessary.

On the other hand, the wafer holder 20 is provided so as to rotate about a rotary shaft 24 by a spindle motor (not shown) and move vertically with respect to the surface plate 10. The holding portion 20a of the wafer holder 20 is provided with a porous chuck 22, and the wafer 1 is held by the wafer holder 20 by being attracted to the porous chuck 22 which is evacuated (26).

In the polishing apparatus of this embodiment, a spiral groove 40 extending from the center to the outer edge is formed on the surface 10a of the surface plate 10. The groove 40 has a width w and a depth h larger than the thickness t of the polishing pad 12, and the edge 40a of the groove 40 on the surface plate 10a is chamfered in a curved shape. The cross-sectional shape of the groove 40 is not particularly limited,
It is formed in a V shape, a U shape, or an inverted trapezoid. Also, the interval between the spiral grooves 40 is not particularly limited, but if the width is too narrow, the polishing cannot be sufficiently performed, and conversely, if it is too wide, the penetration uniformity of the polishing liquid becomes insufficient, so this point should be noted.

The groove 40 according to the present invention is not limited to the embodiment shown in FIGS. 2 and 3 and can be variously modified.
For example, as shown in FIGS. 4 and 5, it may be a grid-shaped groove 40. Further, although not shown, radial grooves extending from the center of the surface plate 10 in the radial direction may be formed.

Next, the operation will be described. First, the polishing pad 12
Is pasted on the surface plate surface 10a. In this case, an adhesive is applied to the back surface of the polishing pad 12 and / or the surface 10a of the surface plate, and the flat polishing pad 12 is stretched and attached as shown in FIG. 4 (A). Next, using the rotating roller 50 having a width smaller than the groove width w, the groove 40 is removed from above the polishing pad 12.
The polishing pad 40 is pressed along the
Is made to follow the groove 40. As a result, on the surface of the polishing pad 12, a smooth concave groove 42 is formed along the groove 40.

Next, after the parallelism between the wafer holder 20 and the surface plate 10 is obtained, the wafer 1 is placed on the porous chuck 22.
After adsorbing and holding the wafer holder 20, the wafer holder 20 and the surface plate 10 are rotated, and the wafer holder 20 is pressure-bonded to the surface plate 10 while supplying the polishing liquid onto the polishing pad 12 from the nozzle 30. As a result, the surface 1a of the wafer 1 is
The surface 1a of the wafer 1 is chemically polished by an alkaline component in the polishing liquid and mechanically polished by polishing particles such as silica having a diameter of about 0.1 μm. Further, due to these synergistic polishing effects, mechanochemical polishing (CMP) is favorably performed.

At this time, the polishing liquid supplied onto the polishing pad 12 flows through the smooth concave groove 42 formed on the surface of the polishing pad 12, and penetrates sufficiently and uniformly between the wafer 1 and the polishing pad 12. It will be. Therefore, the polishing rate on the wafer surface becomes uniform, and as a result, uneven polishing is eliminated, the in-plane uniformity of planarization is improved, and the quality of the polished wafer 1 is improved.

Further, since the edge 40a of the groove 40 of the surface plate 10 is chamfered in a curved shape, the concave groove 42 formed in the polishing pad 12 becomes a very smooth surface, and as a result, the polishing surface 1a of the wafer 1 is formed. There is no risk of scratches on the skin. Further, if grooves are formed in all the polishing pads 12 that are consumables, the cost required for polishing increases, but in the present embodiment, since the grooves 40 are formed in the surface plate 10 that is a durable product, this problem is also solved. it can.

The present invention is not limited to the above-mentioned embodiments, but can be modified in various ways. For example, the means for causing the polishing pad 12 to follow the groove 40 of the surface plate 10 is not limited to the rotating roller 50, and it is also possible to press and press or form a notch in the polishing pad and press it.

[0023]

As described above, according to the polishing method and the polishing apparatus of the present invention, since the polishing pad is partially recessed following the groove on the surface of the surface plate, the polishing liquid sufficiently penetrates into the recessed portion. Will be done. As a result, the in-plane polishing rate of the object to be polished becomes uniform, the unevenness of polishing is small, and the polishing object having excellent in-plane uniformity of planarization can be obtained. Also,
In the present invention, since the grooves are formed on the surface plate which is a durable product instead of the polishing pad which is a consumable product, once the grooves are formed on the surface plate, it is possible to carry out polishing permanently in the latter half thereof, which increases the cost. Can be prevented. Further, since the groove is formed in the polishing pad through the groove formed in the surface plate, the groove formed in the polishing pad becomes extremely smooth, and there is no fear that polishing scratches will occur.

Further, the polishing method of the present invention in which the polishing pad is mounted on the surface of the surface plate, and the polishing pad is pressed along the grooves formed on the surface of the surface plate to form a groove in the polishing pad. According to the method, the polishing pad is made to follow the groove on the surface of the surface plate before the polishing, whereby the permeation uniformity of the polishing liquid is further enhanced.

Further, according to the polishing apparatus of the present invention in which the edge of the surface of the groove on the surface plate is chamfered in a curved shape, the copying of the polishing pad becomes smoother and the occurrence of polishing scratches can be prevented. Further, according to the polishing apparatus of the present invention in which the width and depth of the groove are formed larger than the thickness of the polishing pad, when the polishing pad is made to follow the groove, the polishing pad is sufficiently recessed without protruding from the general surface. Therefore, the penetration uniformity of the polishing liquid is further enhanced.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part showing an embodiment of a polishing apparatus of the present invention.

FIG. 2 is a plan view showing the surface plate of FIG.

FIG. 3 is a cross-sectional view showing the surface plate of FIG.

FIG. 4 is a cross-sectional view of essential parts showing a method of attaching a polishing pad.

FIG. 5 is a plan view showing another embodiment of the surface plate according to the present invention.

6 is a cross-sectional view showing the surface plate of FIG.

FIG. 7 is a plan view of an essential part showing a conventional polishing apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Wafer (object to be polished) 1a ... Wafer surface (polishing surface) 10 ... Surface plate 10a ... Surface plate surface 12 ... Polishing pad 14 ... Rotating shaft 20 ... Wafer holder 20a ... Holding part 24 ... Rotating shaft 30 ... Nozzle 40 ... Groove 40a ... Edge 42 ... Recessed groove 50 ... Rotating roller

Claims (8)

[Claims] 1. A polishing method in which a polishing surface of an object to be polished is pressed against a polishing pad and the polishing surface is polished while a polishing liquid is supplied between the polishing surface and the polishing pad. A polishing method comprising forming a groove on the surface of a surface plate to be mounted, and mounting the polishing pad on the surface of the surface plate to perform polishing. 2. The polishing pad is mounted on the surface plate surface, and the polishing pad is pressed along a groove formed on the surface plate surface to perform polishing in a state where the groove is formed on the polishing pad. The polishing method according to claim 1, wherein: 3. A polishing apparatus having a polishing pad for pressing a polishing surface of an object to be polished and a surface plate on which the polishing pad is mounted, wherein a groove is formed on the surface of the surface plate. Polishing device characterized by. 4. The groove is formed in a spiral shape extending from the center of the surface plate to the outer edge thereof.
The polishing apparatus according to the above. 5. The polishing apparatus according to claim 3, wherein the grooves are formed in a grid pattern. 6. The groove is formed radially from the center of the surface plate toward the outer edge.
The polishing apparatus according to the above. 7. The polishing apparatus according to claim 3, wherein an edge of the groove on the surface of the surface plate is chamfered in a curved shape. 8. The polishing apparatus according to claim 3, wherein the width and the depth of the groove are larger than the thickness of the polishing pad.