JP2008229775A - CMP pad conditioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a CMP (Chemical Mechanical Polishing) pad conditioner capable of improving abrasive grain fixing strength, preventing aggregation of slurry and preventing elution of metals. <P>SOLUTION: Abrasive grains 4 are arranged on base metal 3 formed by stainless steel, etc. and the abrasive grains 4 are electrodeposited and fixed by a nickel plating layer 5. Parts having the grain diameters ≥55% and ≤80% of the abrasive grains 4 are buried in the nickel plating layer 5. A water-repelling coat 6 is formed on an upper surface of the nickel plating layer 5. The water-repelling coat 6 is a composite plating layer made of nickel and water-repelling resin. Content of the water-repelling resin for forming the water-repelling coat 6 is ≥45 vol.% and ≤80 vol.% in relation to the whole volume of the water-repelling coat 6. <P>COPYRIGHT: (C)2009,JPO&INPIT

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 planarizing the surface of a silicon wafer or the like, chemical mechanical polishing (hereinafter abbreviated as “CMP”) has been often used in recent years.
FIG. 4 shows the configuration of a conventional CMP apparatus.

  In FIG. 4, 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. A 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 the 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 elastic urethane 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 conditioning disk in which the outer peripheral side of the base metal 71 is flattened up in a ring shape, and abrasive grains 73 are regularly arranged on the flat portion of the ring portion 72. In a CMP process under an acidic atmosphere, a resin is applied to the conditioning disk surface in order to prevent metal elution from the metal portion of the conditioning disk.

  However, in the case where the resin is applied, the adhesion of the coat is weak, so that the coat is easily peeled off during polishing, and scratches are likely to occur due to the peeling of the coat. In addition, since the resin coated by the spraying method is coated to the upper surface of the abrasive grains, the coat on the upper surface part of the abrasive grains is peeled off by friction during use, and the cutting edge of the abrasive grains appears, and the sharpness is It fluctuates greatly. Therefore, it is necessary to perform a process for mechanically peeling off the coat on the upper surface portion of the abrasive grains, resulting in a problem that the adhesion of the coat in the vicinity of the portion where the coat is removed is poor and the coat is easily peeled off. Further, nickel in the plating layer for fixing the abrasive grains penetrates from the interface from which the coat has been removed, erodes the abrasive grain interface, and the adhesive strength of the abrasive grains decreases.

As a method of applying the resin, a method of electrodepositing the resin on the underlying nickel layer before applying the resin can be adopted, but since only the resin is electrodeposited, the affinity with the nickel layer is low. It is easy to corrode from the interface, and the adhesive strength of abrasive grains is weak.
In the field of electrodeposition grinding stones, a metal matrix composite plating layer is formed on the upper surface of the metal plating layer, and this metal matrix composite plating layer disperses a fluororesin, which is a material having a smaller friction coefficient than the main plating metal. This is described in Patent Document 1.

JP 2002-331460 A

  However, in the electrodeposition grindstone described in Patent Document 1, the content of the material having a smaller friction coefficient than that of the plated metal in the metal-based composite plating layer is set to 35% by volume. Although it can be expected as a water repellent effect, there are problems that it is not suitable for chemical resistance and suppression of contamination by metal elution. When the metal is eluted, the interface of the abrasive grains is eroded, the holding power of the abrasive grains is lowered, and the grinding performance is adversely affected. On the other hand, when there is too much content of a material with a small friction coefficient, the affinity with a base plating layer will fall and the problem that a metal group composite plating layer will peel will arise. When such a metal matrix composite plating layer is peeled off in the CMP pad conditioner, the slurry permeates from the interface between the metal matrix composite plating layer and the abrasive grains, erodes the underlying plating layer, and the abrasive adhesion force decreases. The removal of abrasive grains is a factor that causes the occurrence of scratches, but in CMP pad conditioners, the occurrence of scratches is a serious problem, and means for preventing the removal of abrasive grains is indispensable.

  The present invention has been made to solve the above-described problems, and improves the adhesion of abrasive grains, prevents slurry aggregation, prevents metal elution, and effectively prevents the generation of scratches. An object of the present invention is to provide a CMP pad conditioner capable of satisfying the requirements.

  In order to solve the above problems, a CMP pad conditioner according to the present invention includes a conditioning disk having a grinding portion formed by electrodepositing abrasive grains in a region where the outer peripheral side of the base metal is raised in a ring shape. In the CMP pad conditioner provided, a water-repellent coat is formed on the upper surface of the plating layer, and the water-repellent coat is a composite plating layer made of nickel and a water-repellent resin, and the water-repellent resin that forms the water-repellent coat The content of is characterized by being 45 volume% or more and 80 volume% or less with respect to the volume of the entire water-repellent coat.

  A water-repellent coat is formed on the upper surface of the plating layer, and the water-repellent coat is a composite plating layer made of nickel and a water-repellent resin, so that the plating layer of the conditioning disk, in particular, the interface between the abrasive grains and the plating layer. The coating has a high affinity and excellent adhesion, and the coat is not peeled off even during the CMP process in an acidic atmosphere. Since this water-repellent coat suppresses the elution of the plating metal from the plating layer, the abrasive grain interface is not eroded, and the adhesive strength of the abrasive grains does not decrease.

Moreover, since the composite plating layer is formed, the sharpness does not fluctuate greatly because the upper surface of the non-conductive abrasive grains is not coated as in the case where the resin is applied by the spraying method.
Moreover, since the coat is water-repellent, it is difficult for the slurry to adhere, and the occurrence of scratches due to this can be prevented.

  In addition, by controlling the water-repellent resin content to be 45% by volume or more and 80% by volume or less, while suppressing the elution of the plating metal, the effect of preventing the water-repellent coat from floating and peeling off is enhanced, and the chemical resistance effect Can be increased. If the content of the water repellent resin is less than 45% by volume, the elution of the plating metal cannot be sufficiently suppressed, and the abrasive grains easily fall off due to the erosion of the abrasive grain interface, and the chemical resistance is also inferior. Become. On the other hand, if it exceeds 80% by volume, the affinity with the underlying plating layer is poor, and the slurry penetrates from the interface between the water-repellent coat and the abrasive grains and erodes the underlying plating layer. For this reason, the adhesive strength of the abrasive grains is reduced, leading to falling off of the abrasive grains and causing scratches, which is not preferable. Thus, in order to effectively prevent the abrasive grains from falling off, it is extremely important to set the content of the water-repellent resin within an appropriate range.

  According to the present invention, it is possible to realize a CMP pad conditioner capable of improving abrasive grain adhesion, preventing slurry aggregation, preventing metal elution, and effectively preventing the generation of scratches. .

Hereinafter, a CMP pad conditioner of the present invention will be described based on an embodiment thereof.
FIG. 1 shows a conditioning disk of a CMP pad conditioner according to an embodiment of the present invention. On the outer peripheral side of the conditioning disk 1, the grinding part 2 is provided by raising the outer peripheral side of the base metal 3 in a ring shape.

  Details of the grinding section 2 are shown in FIG. The grinding part 2 is formed by fixing abrasive grains 4 to a base metal 3 by electrodeposition, and diamond or the like can be used as the abrasive grains 4. The abrasive grains 4 are electrodeposited and fixed by a nickel plating layer 5, and the abrasive grains 4 are embedded in the nickel plating layer 5 at a portion of 55% to 80% of the grain size.

  A water repellent coat 6 is formed on the upper surface of the nickel plating layer 5. The water repellent coat 6 is a composite plating layer made of nickel and a water repellent resin. Teflon (registered trademark) can be used as the water-repellent resin, and the particle size of the Teflon particles is 0.3 μm to 5.0 μm. In addition, the content of the water-repellent resin forming the water-repellent coat is 45% by volume or more and 80% by volume or less with respect to the volume of the entire water-repellent coat.

Test examples are shown below.
It was immersed for 60 hours in a mixture of polishing liquid (iron nitrate of pH 2 + H ₂ O ₂ (5%)) and abrasive particles, and the amount of metal (Ni) eluted from the conditioning disk of the CMP pad conditioner was measured. Further, when the water-repellent resin content was changed, the adhesion of the water-repellent coat at the abrasive grain interface and the erosion state of the abrasive grain interface due to the underlying Ni were observed.
The results are shown in Table 1.

  From the above results, when the content of the water-repellent resin is less than 45% by volume, the elution amount of Ni increases rapidly, so that the erosion of the abrasive grain interface is promoted. For this reason, the abrasive grain holding power is reduced, and the abrasive grains will eventually fall off. Therefore, in order to suppress elution of Ni and prevent the abrasive grains from falling off due to the erosion of the abrasive grain interface, the content of the water repellent resin needs to be 45% by volume or more.

On the other hand, when the content of the water-repellent resin exceeds 80% by volume, the affinity with the underlying Ni is lowered and the adhesion is weakened. For this reason, a floating phenomenon of the water repellent coat occurs. Further, when the volume is 90% by volume, the peeling phenomenon of the water-repellent coat occurs. Therefore, in order to suppress the floating phenomenon and peeling phenomenon of the water repellent coat, it is necessary that the content of the water repellent resin is 80% by volume or less.
From the above, by setting the content of the water-repellent resin to 45% by volume or more and 80% by volume or less, it is possible to prevent the water-repellent coat from being lifted or peeled while suppressing the elution of Ni.

Next, a test in which the sharpness of the water repellent coat formed as in the present invention and the one coated by the spraying method were compared will be described.
Table 2 shows the test conditions.

The test results are shown in FIG.
As shown in FIG. 3, in the case of coating by the spraying method, the cutting edge on the abrasive grain surface is covered with the coating in the initial stage of grinding, so the sharpness is poor, and the coating on the abrasive grain surface occurs during grinding. Then, the sharpness starts to rise and the pad scraping rate fluctuates rapidly. However, in the case where a water repellent coat is formed as in the present invention (developed product), such fluctuation does not occur, and the sharpness can be stably maintained from the beginning.

  INDUSTRIAL APPLICABILITY The present invention can be used as a CMP pad conditioner that can improve abrasive grain adhesion, prevent agglomeration of slurry, prevent metal elution, and effectively prevent generation of scratches.

It is a figure which shows the structure of the conditioning disk of CMP pad conditioner which concerns on embodiment of this invention. It is a figure which shows the detail of the grinding part of the conditioning disk of FIG. It is a figure which shows the test result which compared sharpness about what formed the water-repellent coat, and what was coated by the spraying method. 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 Nickel plating layer 6 Water-repellent coating

Claims (1)

  In the CMP pad conditioner having a conditioning disk having a grinding part formed by electrodepositing abrasive grains in a region where the outer peripheral side of the base metal is raised in a ring shape, a water repellent coating is provided on the upper surface of the plating layer. The formed water-repellent coat is a composite plating layer made of nickel and a water-repellent resin, and the content of the water-repellent resin forming the water-repellent coat is 45% by volume with respect to the total volume of the water-repellent coat. A CMP pad conditioner characterized by being 80 volume% or less.

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