KR20040036254A - Polishing Pad For Semiconductor Wafer - Google Patents

Abstract

PURPOSE: A polishing pad for polishing semiconductor wafer is provided to remove a difference between polishing rates of a center part and an outer part of a wafer and a left side and remove the difference between the polishing rates of micro-planarizers located at both sides of a conditioner. CONSTITUTION: A polishing pad for polishing semiconductor wafers includes a hard pad layer(401) and a soft pad layer. The hard pad layer(401) includes a plurality of spiral grooves(402). The spiral grooves(402) are formed on a surface of the polishing pad. The spiral grooves are projected to the rotating direction of the polishing pad. The soft pad layer is adhered on a bottom part of the hard pad layer(401). The spiral groove(402) has a predetermined tilt angle.

Description

Polishing Pad For Semiconductor Wafer

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing pad, and more particularly, to a polishing pad used in a chemical-mechanical polishing process (CMP), which is a planarization process of a semiconductor wafer.

As the semiconductor device becomes more dense and finer and the wiring structure is increased, the level difference increases. In order to planarize the surface level, planarization methods such as spin on glass, etching back, and reflow have been developed. Although it has been used in the process, many problems have arisen, and the chemical mechanical polishing (CMP) technology has been developed for perfect planarization. CMP is a technique of planarizing the surface of a wafer through chemical and physical reactions.

1 is a schematic front view of an IPEC 776 chemical mechanical polishing apparatus manufactured by Speedfam-Ipec. On the lower surface of the rotary 102, a wafer (not shown) is mounted. The orbital 101 is provided below the rotary 102, and the polishing pad 105 is mounted on the upper surface of the orbital 101. The wafer-mounted rotary 102 moves downward to contact the polishing pad on the orbital 101.

In the drawing, both the left and right rotary 102 rotates in the counterclockwise direction, and the orbital 101 also moves to draw an elliptic trajectory in the center of the counterclockwise direction. The rotation of the rotary 102 and the orbital 101 By movement, the wafer (not shown) and the polishing pad 105 generate friction to polish the wafer (not shown). The pair of rotary 102 and orbital 101 is referred to as a micro plunger (MP). Speedfam-Ipec's IPEC 776 chemical mechanical polishing machine is equipped with a pair of micro planarizers (MP) in the front and a pair of micro planarizers (MP) in the rear, for a total of four microplanarizers. have.

At the time of polishing, the injector 103 injects a liquid to make polishing easier.

The conditioner 104 repeatedly polishes the roughened polishing pad.

2 is a plan view of a conventional Rodel IC1000 polishing pad.

Conventional Rodel IC1000 polishing pads have k-grooves (203) for increasing the removal rate on x-grooves (201) and y-grooves (202). ) Was used. The shape of the k-groove is substantially parallel to the y-groove at the center of the polishing pad, and is formed in a diagonal direction connecting the edges of the x-groove and the y-groove toward the outer portion of the polishing pad, thereby increasing the polishing rate. It is polished more at the outer edge than at the center of the wafer. In addition, there is a problem that the polishing rate of the micro-plunger on the left and the micro-plunger on the right are different.

FIG. 3A is a plan view illustrating a case in which the polishing pads 204 of FIG. 2 are symmetrically disposed on the micro planarizers 1 and 2 of the polishing apparatus of FIG. 1, and FIG. 3B is a microplanarizer 1 of the polishing apparatus of FIG. 1. 2 and 2 are plan views showing a case where the polishing pads 204 of FIG. 2 are arranged side by side. When the shape of the k-groove 203 is symmetrically arranged (FIG. 3A), the shape of the polishing pad 204 is symmetrical while the orbital 101 and the rotary 102 have the same direction of movement, so that the polishing rate is different. In the case where the shape of the k-groove 203 is equally disposed on the left and right micro planarizers (FIG. 3B), the conditioner (in the condition of the conditioner 104 located between the polishing pads 105) It is thought that the removal rate is changed by the difference in the movement of 104).

4 is a graph showing the polishing rate of a pair of micro planarizer in the case of Figure 3b.

The y-axis is the etched thickness in units of angstroms, and the x-axis represents the sampled point radially from the center of the wafer. For convenience, the microplanarizer located on the left side of the conditioner is referred to as MP2 and the microplanarizer located on the right side is referred to as MP1.

As shown in the graph, MP1 and MP2 have different polished thicknesses. In particular, in the case of MP1, the polished thicknesses are different at each point of the wafer. In the case of MP1, about 3600 kW was polished near the center of the wafer, but about 4000 kW was polished on the outer side of the wafer.

As such, the conventional Rodel IC1000 polishing pad has a k-groove which is adopted to improve the polishing rate, and is substantially parallel with the y-groove at the center thereof, so that the polishing rate is lowered. It is formed in a diagonal direction connecting the corners of the y-groove to increase the polishing rate, there was a disadvantage that the polishing rate of the center and the outer portion of the wafer is different. In addition, the polishing rate between the micro planarizers located on the left and right sides of the conditioner also had different disadvantages.

Therefore, an object of the present invention is to equalize the polishing rate of the center portion and the outer portion of the wafer, and to equalize the polishing rate between the microplanarizers located on the left and right sides of the conditioner.

1 is a schematic front view of an IPEC 776 chemical mechanical polishing apparatus manufactured by Speedfam-Ipec,

Figure 2 is a plan view of a conventional Rodel IC1000 polishing pad,

3A is a plan view illustrating a case in which the polishing pads of FIG. 2 are symmetrically disposed on the micro planarizers 1 and 2 of the polishing apparatus of FIG. 1, respectively.

3B is a plan view illustrating a case in which the polishing pads of FIG. 2 are arranged side by side on the micro planarizers 1 and 2 of the polishing apparatus of FIG. 1, respectively.

4 is a graph showing the polishing rate of a pair of micro planarizer in the case of Figure 3b,

5a is a plan view of a polishing pad according to the present invention;

FIG. 5B is an enlarged side view of region A of FIG. 5A.

※ Brief description of the main parts of the drawing ※

101: Orbital 102: Rotary

103: injector 104: conditioner

201: x-groove 202: y-groove

203: k-groove 204: IC1000 polishing pad

401: hard pad layer 402: spiral groove

403: soft pad layer

The wafer polishing pad according to the present invention for achieving the above object has a hard pad layer including a plurality of spiral grooves, the surface of which is formed to block in the rotational direction of the polishing pad, and at the bottom of the hard pad layer. It is characterized by including an adhesive Soft Pad layer.

Preferably, the groove is characterized in that it is formed obliquely.

More preferably, the groove spacing is 0.055 to 0.065 inches along the circumference of the polishing pad, the depth is 0.0145 to 0.0155 inches, the width of the groove is 0.005 to 0.015 inches, and inclined 34.5 to 35.5 degrees from the horizontal plane. It features.

Hereinafter, the present invention will be described in detail with reference to the drawings.

Figure 5a is a plan view of a polishing pad according to the present invention. The polishing pad consists of a hard pad layer 401 including a plurality of spiral grooves 402 and a soft pad layer (not shown) that is adhered to the opposite side of the hard pad layer 401. As the wafer rotates, the polishing pad contacts the polishing pad, and the center portion is formed at an angle to the movement direction so that the contact surface with the wafer (not shown) is inclined more. Near the apex of the grove, in other words, the center of the polishing pad and the center of the circumference are polished almost perpendicular to the direction of motion. The center is therefore sharper than the peak of the groove. This phenomenon is easy to see, for example, when the vandal swords used in the Middle East are better cut than the linear swords used in the West.

By increasing the polishing rate at the center of the polishing pad in this way, the polishing rate attributable to the relatively low linear velocity can be compensated for, so that the polishing rate at the center and the outer portion of the wafer can be made even.

In addition, by providing a conditioner in each of the left and right micro planarizers, the left and right micro planarizers may have the same etching rate.

FIG. 5B is an enlarged side view of region A of FIG. 5A.

The spiral groove 402 in the present invention is formed at 0.055 to 0.065 inch interval d ₁ along the circumference of the polishing pad. The depth d ₂ of the spiral groove is formed to be 0.0145 to 0.0155 inches deep, and the width d ₄ of the spiral groove is formed to be in the range 0.005 to 0.015 inches, with a parallelogram inclined at 34.5 to 35.5 degrees from the horizontal plane. Is formed. Thus, by making the spiral grooves incline, the polishing rate can be increased. If the angle is smaller than this, the polishing rate can be increased, but the life of the polishing pad is reduced.

On the other hand, embodiments of the invention disclosed in the specification and drawings are merely illustrative of specific examples for the purpose of understanding and are not intended to limit the scope of the invention. It is apparent to those skilled in the art that other modifications based on the technical idea of the present invention can be carried out in addition to the embodiments disclosed herein.

The present invention has the effect of equalizing the polishing rate of the center portion and the outer portion of the wafer and equalizing the polishing rate between the micro planarizers located on the left and right sides of the conditioner.

Claims (3)

In the disc shaped wafer polishing pad, The surface of the polishing pad is a hard pad layer including a plurality of spiral grooves formed to block in the rotation direction of the polishing pad; And And a soft pad layer adhered to the bottom of the hard pad layer. The wafer polishing pad of claim 1, wherein the spiral groove is formed to be inclined. The method of claim 2, wherein the spiral grooves have a spacing of 0.055 to 0.065 inches along the circumference of the polishing pad, a depth of 0.0145 to 0.0155 inches, a groove width of 0.005 to 0.015 inches, and 34.5 to 35.5 degrees from the horizontal plane. Wafer polishing pad, characterized in that inclined.