JP2006187847A - Cmp pad conditioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a CMP pad conditioner capable of improving polishing efficiency and the life of a polishing pad by enhancing the slurry retention capacity of a pad face of the polishing pad. <P>SOLUTION: A grinding part 2 is provided to the outer peripheral side of a conditioning disk 1. The grinding part 2 is formed by electro-depositing abrasive grains 4 on a base metal to form a plated layer. Diamond or the like can be used as the abrasive grains 4. Preferably, the abrasive grains have a regular hexahedral or octahedral shape in a well-controlled crystal form. Protruding parts 7 having a thick plating layer are formed at a prescribed rate. The abrasive grains 4 are fixed to each protruding part 7 and each flat part 8 other than the protruding parts 7. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a CMP pad conditioner used in a CMP apparatus used for planarizing a surface of a silicon wafer or the like.

As a method for flattening the surface of a silicon wafer or the like, chemical mechanical polishing (hereinafter abbreviated as “CMP”) has been frequently used in recent years.
FIG. 7 shows the configuration of a conventional CMP apparatus.

  In FIG. 7, the CMP apparatus 51 includes a polishing head 54 and a conditioner 55 provided on a rotary table 53 that rotates about a rotary table rotary shaft 52. An elastic urethane polishing pad 56 is formed on the upper surface of the rotary table 53.

The polishing head 54 includes a polishing head rotating shaft 57 and a disk-shaped wafer carrier 58, and a wafer 59 is attracted to the lower surface of the wafer carrier 58. The disk-shaped wafer carrier 58 rotates around the polishing head rotating shaft 57.
The conditioner 55 includes a conditioner rotating shaft 60 and a disk-shaped conditioning disk 61. The conditioning disk 61 rotates about the conditioner rotation shaft 60.

  From the slurry supply unit 62, a slurry 63 that is an abrasive is supplied onto the elastic urethane polishing pad 56, and the slurry 63 is taken into a contact surface between the wafer 59 and the elastic urethane polishing pad 56. The surface of the wafer 59 comes into contact with the elastic urethane polishing pad 56 on the surface of the rotary table 53 and is polished by the slurry 63.

  Abrasive grains made of diamond or the like are fixed to the outer peripheral side lower surface of the conditioning disk 61, and the surface of the elastic urethane polishing pad 56 is ground by rubbing the abrasive grains against the polishing pad 56. Thereby, the state where the surface of the elastic urethane polishing pad 56 is fluffed can be maintained, and the polishing state can be kept constant.

An example of a conventional conditioning disk is shown in FIG.
This is a conditioner in which the outer peripheral side of the base metal 71 is raised in a ring shape and abrasive grains 73 are regularly arranged on the flat portion of the ring portion 72.

In conditioning using a CMP pad conditioner, retention of the slurry, suppression of scratches by the slurry, and flatness of the processed surface are important. If the cutting edge state of the abrasive grain tip of the CMP pad conditioner is not sharp, the elastic urethane polishing pad will not be sharp, the holding power of the slurry will be poor, and the polishing efficiency, flatness and homogeneity will decrease. Furthermore, if the slurry cannot be sufficiently dispersed, micro scratches will be induced.
On the other hand, if the cutting edge state of the abrasive tip of the CMP pad conditioner is sharp, the sharpening of the elastic urethane polishing pad proceeds, but the expensive elastic urethane polishing pad is consumed more than necessary, the processing cost increases, and frequently It is necessary to replace the pad.

  Patent Document 1 discloses a technique of an elastic urethane polishing pad capable of polishing a wafer with high efficiency by increasing slurry holding power in a CMP pad conditioner. Further, Patent Document 2 describes a CMP pad conditioner in which a step is provided on a base metal in order to maintain sharpness.

JP 2002-154051 A JP 2004-130475 A

  However, according to the technique described in Patent Document 1, since the pad itself has a slurry holding function, there is a problem that a desired polishing ability cannot be exhibited depending on whether the conditioning is good or bad. Further, in the CMP pad conditioner described in Patent Document 2, the effect of maintaining the sharpness of the conditioner itself is exhibited, but since the slurry pocket is not formed on the pad surface, the effect of retaining the slurry on the pad surface cannot be expected.

As described above, in the conditioning using the CMP pad conditioner, it is difficult to judge how sharp the cutting edge state of the abrasive grain tip is appropriate, and the elastic urethane polishing pad is sufficiently sharpened. Therefore, if increasing the retention force of the slurry depends only on the state of the cutting edge at the tip of the abrasive grain, a CMP pad conditioner having good conditioning cannot be realized.
The present invention has been made in order to solve the above problems, and during conditioning, a groove functioning as a slurry pocket is formed on the surface of the elastic urethane polishing pad, and the holding power of the slurry on the pad surface is enhanced, thereby improving the polishing efficiency. An object of the present invention is to provide a CMP pad conditioner capable of improving the service life.

In order to solve the above-described problems, the present invention provides a CMP pad conditioner in which a plating layer is formed on a base metal by electrodeposition and the abrasive grains are fixed, and convex portions having a thick plating layer are formed at a predetermined ratio. Then, the CMP pad conditioner is characterized in that abrasive grains are fixed to the convex portion and a flat portion which is a region other than the convex portion.
The abrasive grains fixed to the convex portion, which is a region where the thickness of the plating layer is increased, act on the pad surface of the polishing pad to form a groove on the pad surface. By forming the groove, the slurry is sufficiently held in the groove, and a stable polishing efficiency can be obtained. Since the polishing pad is made of an elastic material such as elastic urethane, and the abrasive grains are difficult to wear out, the abrasive grains fixed on the area where the thickness of the plating layer is thickened are applied to the pad surface. A groove for holding the slurry can be effectively formed.

  In the present invention, the difference in thickness between the convex portion and the flat portion is preferably 10% or more and 30% or less of the average particle size of the abrasive grains. If the difference in thickness is less than 10% of the average grain size of the abrasive grains, it is impossible to form a groove enough to hold the slurry on the pad surface, and if it exceeds 30%, the pad surface The shape of the surface is destroyed, and the uniformity of the surface is impaired.

  In this invention, it is preferable that the area which the abrasive grain fixed to the convex part of the said plating layer occupies is 20% or more and 50% or less of the total fixed area of the abrasive grain. If the area occupied by the abrasive grains fixed to the convex portion of the plating layer is less than 20% of the total fixed area of the abrasive grains, it is impossible to form grooves enough to hold the slurry on the pad surface. If it exceeds 50%, the shape of the pad surface is destroyed, and the uniformity of the surface is impaired.

  In this invention, it is preferable that the space | interval of the convex part of the said plating layer is 5 to 15 times the average particle diameter of the said abrasive grain. When the interval between the convex portions of the plating layer is less than 5 times the average particle size of the abrasive grains, the slurry discharging ability is lowered, and the condensed slurry causes scratches. On the other hand, if it exceeds 15 times, a groove that can forcibly hold the slurry cannot be formed on the pad surface.

  According to the present invention, it is possible to realize a CMP pad conditioner capable of improving the polishing efficiency and life by increasing the retention force of the slurry on the pad surface of the polishing pad.

Hereinafter, a CMP pad conditioner of the present invention will be described based on an embodiment thereof.
FIG. 1 shows a configuration of a CMP pad conditioner according to an embodiment of the present invention. FIG. 1A shows a conditioning disk of a CMP pad conditioner, and a grinding part 2 is provided on the outer peripheral side of the conditioning disk 1. The detail of the grinding part 2 is shown in FIG.1 (b). The grinding part 2 is formed by fixing abrasive grains 4 on a base metal 3 by forming a plating layer by electrodeposition, and diamond or the like can be used as the abrasive grains 4, and the grain size is about 200 μm. And it is preferable that it is a hexagonal octahedron grain having a uniform crystal shape with a major axis / minor axis ratio of 1.1 or less.

  Protrusions 7 having a thick plating layer are formed at a predetermined ratio, and abrasive grains 4 are fixed to the convex parts 7 and flat parts 8 other than the convex parts 7. The step height H, which is the difference between the thickness of the convex portion 7 and the thickness of the flat portion 8, is 10% or more and 30% or less of the average particle size of the abrasive grains 4. Further, the area occupied by the abrasive grains 4 arranged on the convex portions 7 is set to 20% to 50% of the total fixed area of the abrasive grains 4. Further, the interval for forming the step is set to be 5 to 15 times the average particle diameter of the abrasive grains 4.

  Here, the meaning of the fixed area of the abrasive grains 4 will be described with reference to FIG. In FIG. 1C, black circles indicate the area occupied by the abrasive grains 4 arranged on the convex portions 7, and white circles indicate the areas other than the convex portions 7. The area occupied by the abrasive grains 4. When the area occupied by the abrasive grains 4 arranged on the convex portion 7 is 20% or more of the total fixed area of the abrasive grains 4, the area displayed by the black circle is displayed by the area displayed by the black circle and the white circle. Means 20% or more of the total area. Further, the area occupied by the abrasive grains 4 arranged on the convex portions 7 is 50% or less of the total fixed area of the abrasive grains 4 is that the area displayed with black circles is the area displayed with black circles and white circles. This means that it is 50% or less of the total displayed area.

  FIG. 1 (d) shows how conditioning is performed using the CMP pad conditioner of the present invention. Grooves 9 for holding the slurry are formed in the polishing pad 6 by the abrasive grains 4 arranged on the projections 7 provided on the plating layer 5 of the conditioning disk 1.

  Such a CMP pad conditioner can be manufactured through the following steps. First, the non-electrodeposit portion of the base metal is masked, and the insulating sheet is mounted so that the portion for fixing the abrasive grains is exposed. Next, Ni plating is deposited so that a necessary step is formed on the exposed portion. Thereafter, the insulating sheet is removed, the abrasive grains are dispersed, the abrasive grains are temporarily fixed by Ni plating, and then the abrasive grains are permanently fixed by Ni plating to remove masking.

Hereinafter, specific production examples and test examples are shown.
A CMP pad conditioner having an abrasive grain layer having the shape shown in FIG. The step size is 15% of the average grain size of the abrasive grains, the area for forming the level difference is 35% of the fixed area of the abrasive grains, and the interval for forming the level difference is 5 times the average grain size of the abrasive grains. is there. A performance comparison was made between the product of the present invention and a conventional product without a step. The specifications of both the inventive product and the conventional product are 100D-4T-10W, and by using an electrodeposition method, abrasive grains having a particle size of about 200 μm and a major axis / minor axis ratio of 1.1 or less are used. Arranged in layers.
Table 1 shows the polishing test conditions.

FIG. 2 shows the result of the polish test. In FIG. 2, the wafer polish rate index is an amount defined with the initial polish rate of the conventional product as 100. As can be seen from FIG. 2, in the conventional product, since the initial wafer polish rate is low, the wafer polish rate index drops to 80 after 30 hours. In contrast, the invention product can form a groove on the polished surface to hold the slurry, so that the initial polishing efficiency is high, and even after 45 hours, the wafer polish rate index is 100, which is a high level. It is maintained and the lifetime is improved.
Next, Table 2 shows the conditions of the pad removal test.

  FIG. 3 shows the result of the pad removal rate test. In FIG. 3, the pad removal rate index is an amount defined with the initial pad removal rate of the conventional product as 100. As can be seen from FIG. 3, the inventive product always shows a high pad removal rate from the beginning as compared with the conventional product, and the pad removal rate does not decrease for a long time and is stable.

Next, FIG. 4 shows a test result when a polish test is performed by changing the height of the step of the plating layer. Also in FIG. 4, the pad removal rate index is an amount defined with the initial pad removal rate of the conventional product as 100, and the same applies to FIGS. 5 and 6 below.
When the height of the step is 10% or more and 30% or less of the average grain size of the abrasive grains, the wafer polish rate index is superior to the conventional product, whereas when 5%, the slurry can be retained. Since this groove cannot be formed, the wafer polish rate is comparable to that of the conventional product. On the other hand, when it exceeded 30%, the shape of the pad surface was destroyed, resulting in poor surface uniformity.

FIG. 5 shows the test results when the polish test is performed by changing the area occupied by the abrasive grains fixed to the convex portions of the plating layer.
When the area occupied by the abrasive grains fixed to the convex portion of the plating layer is 20% or more and 50% or less of the total fixed area of the abrasive grains, the wafer polish rate index is superior to the conventional product, At 10%, the wafer polish rate is lowered because grooves sufficient to forcibly hold the slurry on the pad surface cannot be formed. On the other hand, when it exceeded 50%, the shape of the pad surface was destroyed, and the uniformity of the surface occurred.

FIG. 6 shows a test result when a polish test is performed by changing the interval between the convex portions of the plating layer.
When the interval between the convex portions of the plating layer is 5 to 15 times the average grain size of the abrasive grains, the wafer polish rate index is superior to the conventional product, whereas the interval between the convex portions of the plating layer is Is less than 5 times the average particle size of the abrasive grains, the slurry discharge capacity is reduced, and the condensed slurry generates scratches. On the other hand, when it is 17 times, a groove enough to forcibly hold the slurry cannot be formed on the pad surface, and the wafer polish rate is lowered.

  INDUSTRIAL APPLICABILITY The present invention can be used as a CMP pad conditioner capable of improving the polishing efficiency and the life by increasing the holding power of the slurry on the pad surface of the polishing pad.

It is a figure which shows the structure of the CMP pad conditioner concerning embodiment of this invention. It is a figure which shows the result of a polish test. It is a figure which shows the result of a pad removal rate test. It is a figure which shows the test result when performing the polish test by changing the height of the level | step difference of a plating layer. It is a figure which shows the test result when changing the area which the abrasive grain fixed to the convex part of a plating layer occupies, and performing the polish test. It is a figure which shows the test result when changing the space | interval of the convex part of a plating layer, and performing the polish test. It is a figure which shows the structure of the CMP apparatus used conventionally. It is a figure which shows an example of the conditioning disk used conventionally.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Conditioning disk 2 Grinding part 3 Base metal 4 Abrasive grain 5 Plating layer 6 Polishing pad 7 Convex part 8 Flat part 9 Groove

Claims (4)

  In a CMP pad conditioner in which a plating layer is formed by electrodeposition on the base metal and the abrasive grains are fixed, convex portions with a thick plating layer are formed at a predetermined ratio. A CMP pad conditioner characterized in that abrasive grains are fixed to a flat portion.   The CMP pad conditioner according to claim 1, wherein a difference in thickness between the convex portion and the flat portion is 10% or more and 30% or less of an average particle size of the abrasive grains.   3. The CMP pad conditioner according to claim 1, wherein the area occupied by the abrasive grains fixed to the convex portions of the plating layer is 20% or more and 50% or less of the total fixed area of the abrasive grains.   4. The CMP pad conditioner according to claim 1, wherein the interval between the convex portions of the plating layer is 5 to 15 times the average grain size of the abrasive grains. 5.

Images