US20150367480A1

US20150367480A1 - Chemical mechanical polishing conditioner

Info

Publication number: US20150367480A1
Application number: US14/721,508
Authority: US
Inventors: Jui-Lin Chou; Chia-Chun Wang; Chia-Feng CHIU; Hsin-Ying Lin
Original assignee: Kinik Co
Current assignee: Kinik Co
Priority date: 2014-06-18
Filing date: 2015-05-26
Publication date: 2015-12-24
Also published as: TW201600242A

Abstract

Provided is a CMP conditioner comprising: a substrate comprising multiple concave parts, the concave parts formed in a surface of the substrate and each concave part having a side wall; multiple fixed plates, each fixed plate comprising a bottom, a top, a concavity and an inclined plane, the bottom fixed into the concave part, the top integrated with the bottom with a contact surface formed between the top and the bottom, the concavity formed in the top and opposite the bottom, the inclined plane formed between the contact surface and the concavity, an angle and a space formed between the inclined plane and the side wall; and multiple abrasive units, each abrasive unit mounted in the concavity. When the CMP conditioner is applied to a pad, the thickness of the pad can recover to its original thickness; i.e., the cutting depth is increased to improve the dressing performance.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to a chemical mechanical polishing conditioner, especially to a chemical mechanical polishing conditioner comprising an inclined plane.
2. Description of the Prior Art(s)
Chemical Mechanical Polishing (abbreviated as CMP) is a necessary method in semiconductor process. During a CMP process, a pad is loaded on a rotating support and introduced with a suitable slurry. The rotating pad is then in contact with a wafer, so as to polish and planarize a surface of the wafer. In order to ensure the polishing efficiency of the pad, the surface roughness of the pad is required to be kept above a certain level. However, the polishing debris produced during the CMP process accumulates and stagnates on the surface of the pad, forming a hardened layer. The hardened layer deteriorates the surface roughness of the pad, and thus decreases the polishing efficiency of the pad and shortens the lifetime of the pad.
Therefore, a CMP conditioner is used during CMP process to dress the surface of the pad, so as to maintain the surface roughness of the pad and prolong the lifetime of the pad.
With reference to FIG. 10, a conventional CMP conditioner 8 comprises a substrate 80, multiple metal bars 81, multiple abrasive units 82, and multiple holes 83. The holes 83 are formed through the substrate 80. The metal bars 81 are correspondingly mounted in the holes 83. Each abrasive unit 82 is correspondingly mounted on an end of the metal bar 81 and partially protrudes from a surface of the substrate 80. When the CMP conditioner 8 is applied to a pad 90, the surface of the substrate 80 is pressed on the pad 90 and the abrasive units 82 are used to dress the surface of the pad 90. However, a cutting depth D of the CMP conditioner 8 is constrained by the dimensions of the abrasive units 82. When the cutting depth D may decrease due to the abrasion of the abrasive units 82 and the abrasive units 82 may become blunt after being used for a period of time, the dressing efficiency of the CMP conditioner 8 is thus decreased. Furthermore, the slurry cannot be mixed uniformly in the limited cutting depth D, thereby affecting the dressing efficiency of the CMP conditioner 8.
To overcome the shortcomings, the present invention provides a CMP conditioner to mitigate or obviate the aforementioned problems.

SUMMARY OF THE INVENTION

The main objective of the present invention is to provide a CMP conditioner to mitigate the limitation of cutting depth constrained by the dimension of the abrasive unit. The other objective of the present invention is to provide a CMP conditioner to mitigate the problem of decreased dressing efficiency caused by the abrasion of the abrasive units.
To achieve the abovementioned objective, the present invention provides a CMP conditioner. The CMP conditioner comprises: a substrate comprising multiple concave parts, multiple fixed plates, and multiple abrasive units. The concave parts are formed in a surface of the substrate, each concave part having a side wall. Each fixed plate comprises a bottom, a top, a concavity and an inclined plane, and the bottom is fixed into the concave part. The top is formed on the bottom in an integral configuration and a contact surface is formed between the top and the bottom. The concavity is formed in the top and opposite the bottom. The inclined plane is formed between the contact surface and the concavity. A space is formed between the inclined plane and the side wall, and an angle is formed between the inclined plane and the side wall, the angle ranging from 30° to 60°, inclusive. Each abrasive unit is mounted in the concavity. Each abrasive unit and the top form a pyramidal structure.
When the CMP conditioner is applied to a pad, the slurry introduced on a surface of the pad is fluctuated in turbulence and irregularly moved within the space, allowing the concentration of the slurry to become more uniform in the space. Furthermore, the thickness of the pad can also be recovered to its original thickness in the space. That is to say, a cutting depth of the abrasive units applied to the pad is not further limited by the dimension of the abrasive units, and thus the cutting depth is increased to improve the dressing performance of the CMP conditioner.
Preferably, each fixed plate is fixed into the concave part through a binding layer and the binding layer is consisted of a ceramic material, a brazing material, an electroplating material, a metallic material, or a polymeric material. More preferably, the brazing material is selected from the group consisting of iron, cobalt, nickel, chromium, manganese, silicon, aluminum, and any combination thereof. More preferably, the polymeric material is epoxy resin, polyester resin, polyacrylate resin, or phenol resin.
Preferably, each fixed plate is fixed into the concave part by a ceramic sintering method, a brazing method, an electroplating method, a metallic sintering method, or a polymeric curing method through the binding layer.
Preferably, the concave parts are arranged on the surface of the substrate in concentric circles. Alternatively, the concave parts are arranged on the surface of the substrate in a radial pattern.
Preferably, the concave parts are formed through the substrate.
Preferably, the inclined plane is formed between the contact surface and the concavity by a surface processing method. The surface processing method is a mechanical polishing method, a chemical etching method, or a laser processing method.
Preferably, each abrasive unit has a tip opposite the concavity, and a vertical distance between the surface of the substrate and the tip of each abrasive unit ranges from 20 μm to 300 μm, inclusive. More preferably, the vertical distance between the surface of the substrate and the tip of each abrasive unit ranges from 100 μm to 300 μm, inclusive.
Preferably, the chemical mechanical polishing conditioner has at least two vertical distances between the surface of the substrate and the tip of each abrasive unit, a difference between the vertical distances ranges from 20 μm to 100 μm, inclusive.
Preferably, the CMP conditioner has a first vertical distance between the surface of the substrate and the tip of each abrasive unit, defined as an exposing degree H, and a second vertical distance between the surface of the substrate and the tip of each abrasive unit, defined as an exposing degree H′. A difference between the first vertical distance and the second vertical distance ranges from 20 μm to 100 μm, inclusive. More preferably, the difference between the first vertical distance and the second vertical distance ranges from 40 μm to 60 μm, inclusive.
When the pad to be dressed has a non-uniform thickness, i.e., the surface of the pad is not smooth, using the CMP conditioner, which has two different exposing degrees H, H′ and said arrangement of the fixed plates, provides a more uniform dressing performance of the CMP conditioner.
Preferably, the abrasive units are consisted of artificial diamond, natural diamond, polycrystalline diamond, or cubic boron nitride.
Preferably, dimensions of the abrasive units range from 30 μm to 2000 μm, inclusive. More preferably, the dimensions of the abrasive units range from 600 μm to 1000 μm, inclusive, and the diameter of the smallest dimension of the abrasive unit is 80% to the diameter of the largest dimension of the abrasive unit.
Preferably, each abrasive unit is mounted on the concavity of the top by an electroplating method, a sintering method, or a brazing method.
Preferably, each abrasive unit is processed by a surface processing method to form a specific cutting angle, a crystal structure, a tip height, and an alignment direction. The surface processing method is a mechanical grinding or lapping method, a chemical etching method, or a laser processing method.
Preferably, the cutting angle of each abrasive unit ranges from 30° to 150°, inclusive. More preferably, the cutting angle of each abrasive unit is 60° or 90°.
Preferably, the crystal structure of each abrasive unit is hexahedral or octahedral.
Preferably, the substrate is a stainless steel substrate, a die steel substrate, a metal alloy substrate, a ceramic substrate, or a plastic substrate.
Preferably, number of the concave parts ranges from 50 to 300, inclusive. More preferably, the number of the concave parts ranges from 60 to 100, inclusive.
Preferably, a shape of a cross-section of each concave part is circular. A diameter of the cross-section of each concave part ranges from 2.6 mm to 3.6 mm, inclusive.
Preferably, a shape of each fixed plate is cylindrical and the fixed plates are consisted of stainless steel. A cross-section of each fixed plate ranges from 2.6 mm to 3.6 mm, inclusive.
Other objectives, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a CMP conditioner in accordance with Embodiment 1 of the present invention;

FIG. 2 is a cross-sectional view in partial section of a fixed plate of the CMP conditioner in accordance with Embodiment 1 of the present invention;

FIG. 3 is an exploded cross-sectional view of the fixed plate and the abrasive unit of the CMP conditioner in accordance with Embodiment 1 of the present invention;

FIG. 4 is a scanning electron microscope image of the fixed plate and the abrasive unit of the CMP conditioner in accordance with Embodiment 1 of the present invention;

FIG. 5 is an operational view of the CMP conditioner in accordance with Embodiment 1 of the present invention with a pad;

FIG. 6 is a cross-sectional view of a CMP conditioner in accordance with Embodiment 2 of the present invention;

FIG. 7 is a cross-sectional view in partial section of the CMP conditioner in accordance with Embodiment 2 of the present invention;

FIG. 8 is a cross-sectional view in partial section of a CMP conditioner in accordance with Embodiment 3 of the present invention;

FIG. 9 is a cross-sectional view in partial section of a fixed plate of a CMP conditioner in accordance with Embodiment 4 of the present invention;

FIG. 10 is an operational view of a conventional CMP conditioner with a pad.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiment

1

With reference to FIG. 1 and FIG. 2, the chemical mechanical polishing conditioner 1 (abbreviated as CMP conditioner) of Embodiment 1 comprises a substrate 10, multiple fixed plates 20, and multiple abrasive units 30.
A shape of the substrate 10 is circular, and the substrate 10 has multiple concave parts 11. The concave parts 11 are formed in a surface of the substrate 10. Each concave part 11 has a side wall 111. In the present embodiment, the substrate 10 is consisted of stainless steel and has a thickness of 6.35 mm. The number of the concave parts 11 is sixty-six, and the concave parts 11 are arranged on the surface of the substrate 10 in concentric circles. More specifically, thirty-six of the concave parts 11 are arranged at the outer circle, and the other thirty concave parts 11 are arranged at the inner circle. It can be seen that FIG. 1 is merely a schematic view for illustration. Each concave part 11 has a circular cross-section with a diameter of 2.6 mm.
The fixed plates 20 are mounted in the concave parts 11, and each fixed plate 20 has a bottom 21, a top 22, a concavity 23, and an inclined plane 24. In the present embodiment, the fixed plate 20 made of stainless steel is formed as a cylindrical structure, and a diameter C of a cross-section of each fixed plate 20 is 2.5 mm.
The bottoms 21 of the fixed plates 20 are each respectively fixed into the concave parts 11 through binding layers 40. In the present embodiment, the bottoms 21 of the fixed plates 20 are each respectively fixed into the concave parts 11 by a brazing method through the binding layers 40. The binding layer 40 is consisted of a brazing material. The brazing material is aluminum.
The top 22 is formed on the bottom 21 in an integral configuration, and a contact surface is formed between the top 22 and the bottom 21. The concavity 23 is formed in the top 22 and opposite the bottom 21. The inclined plane 24 is formed obliquely and inwardly from the contact surface toward the concavity 23. A space 25 is formed between the inclined plane 24 and the side wall 111, and an angle α is formed between an extending plane of the inclined plane 24 and the side wall 111. In the present embodiment, the angle α is 45°.
With reference to FIG. 3 and FIG. 4, the abrasive units 30 are each respectively mounted in the concavities 23 to form a pyramidal structure. In the present embodiment, each of the abrasive units 30 is mounted in the concavity 23 by a brazing method and has a tip 31. The abrasive units 30 are consisted of artificial diamond. A dimension of each abrasive unit 30 is 800 μm. The tip 31 of each abrasive unit 30 is opposite the concavity 23. A vertical distance between the surface of the substrate 10 and the tip of each abrasive unit 30 is defined as an exposing degree H of each abrasive unit 30, being 100 μm. Each abrasive unit 30 has a specific cutting angle θ and a crystal structure. In the present embodiment, the cutting angle θ of each abrasive unit 30 is 60° as shown in FIG. 3, and the crystal structure of each abrasive unit 30 is hexahedral. A ratio of the exposing degree H of each abrasive unit 30 to the diameter C of the cross-section of each fixed plate 20 is 1:25. A ratio of the dimension of each abrasive unit 30 to the diameter C of the cross-section of each fixed plate 20 is 8:25.
With reference to FIG. 5, when the CMP conditioner 1 is applied to a pad 90, the slurry introduced on a surface of the pad 90 is fluctuated in turbulence and irregularly moved within the space 25, allowing the concentration of the slurry to become more uniform in the space 25. Furthermore, the thickness of the pad 90 can also be recovered to its original thickness in the space 25. That is to say, a cutting depth D of the abrasive units 30 applied to the pad 90 is not further limited by the dimension of the abrasive units 30, and thus the cutting depth D is increased to improve the dressing performance of the CMP conditioner 1.

Embodiment 2

With reference to FIG. 6 and FIG. 7, the CMP conditioner 1A of Embodiment 2 is similar to the CMP conditioner 1 of Embodiment 1. The differences between these two embodiments are described hereinafter.
In the instant Embodiment, the substrate 10A is made of a ceramic material. The concave parts 11A are formed through the substrate 10A. The number of the concave parts 11A is one hundred, and the concave parts 11A are arranged on the surface of the substrate in a radial pattern. The diameter of the cross-section of each concave part 11A is 3.6 mm.
The diameter C of a cross-section of each fixed plate 20A is 3.5 mm. The bottoms 21A of the fixed plates 20A are each respectively fixed into the concave parts 11A by a polymeric curing method through the binding layer 40A made of a polymeric material. The polymeric material is epoxy resin.
The abrasive units 30A made of cubic boron nitride are mounted on the concavities 23A by a sintering method. A dimension of each abrasive unit 30A is 2000 μm. The exposing degree H of each abrasive unit 30A is 300 μm. The cutting angle θ of each abrasive unit 30A is 90°. It can be seen that FIG. 7 is a schematic view for illustration. The crystal structure of each abrasive unit 30A is octahedral. The ratio of the exposing degree H of each abrasive unit 30A to the diameter C of the cross-section of each fixed plate 20A is 3:35. The ratio of the dimension of each abrasive unit 30A to the diameter C of the cross-section of each fixed plate 20A is 4:7.

Embodiment 3

With reference to FIG. 8, the CMP conditioner 1B of Embodiment 3 is similar to the CMP conditioner 1 of Embodiment 1. The differences between these two embodiments are described hereinafter.
In the instant Embodiment, the CMP conditioner 1B has two different exposing degrees of the abrasive units 30B, the first exposing degree H of the abrasive units 30B and the second exposing degree H′ of the abrasive units 30B. A distance between the first exposing degree H of the abrasive units 30B and the second exposing degree H′ of the abrasive units 30B ranges from 20 μm to 100 μm. The ratio of the dimension of each abrasive unit 30B to the diameter of the cross-section of each fixed plate 20B is 1:2.
When the pad 90 to be dressed has a non-uniform thickness, i.e., the surface of the pad 90 is not smooth, using the CMP conditioner 1B, which has two different exposing degrees H, H′ and said arrangement of the fixed plates 20B, provides a more uniform dressing performance of the CMP conditioner 1B.

Embodiment 4

With reference to FIG. 9, the CMP conditioner 1C of Embodiment 4 is similar to the CMP conditioner 1 of Embodiment 1. The differences between these two embodiments are described hereinafter.
Each fixed plate 20C of the instant Embodiment has two concavities 23C and the inclined plane 24C. The concavities 23C are formed in the top 22C. The inclined plane 24C is formed obliquely and inwardly from the contact surface toward the concavities 23C. The abrasive units 30C made of polycrystalline diamond are mounted on the concavities 23C. The dimension of each abrasive unit 30C is 300 μm. The diameter of the cross-section of each fixed plate 20C is 2.5 mm. The ratio of the dimension of each abrasive unit 30C to the diameter of the cross-section of each fixed plate 20C is 1:8. In the present embodiment, each fixed plate 20C is mounted with more abrasive units 30C than in the Embodiment 1 to improve the dressing efficiency when the CMP conditioner 1C is applied to the pad.

Experimental Embodiment

The CMP conditioner of Embodiment 1 and the conventional CMP conditioner described in background of the invention, as a control sample, are respectively applied to two pads, and the thicknesses of the pads are recorded at different dressing time (x, unit: hour). Results are listed in Table 1.
The dressing efficiency is calculated by dividing the thickness difference of the pad before and after dressing by the dressing time. The average dressing efficiencies of the CMP conditioner 1 of Embodiment 1 and of the conventional CMP conditioner are also listed in Table 1.

TABLE 1

	CMP conditioner of	CMP conditioner of
	Embodiment 1	Control Sample

Thicknesses	x = 0	2031	μm	1993	μm
of the pad	x = 1	1912	μm	1898	μm
	x = 2	1800	μm	1815	μm
	x = 3	1668	μm	1723	μm
	x = 4	1563	μm	1634	μm

Average dressing

118

μm per hour

89.7

μm per hour

efficiency

The average dressing efficiency of the CMP conditioner of Embodiment 1 was 118 μm per hour. Compared to the conventional CMP conditioner, the average dressing efficiency of the conventional CMP conditioner was 90 μm per hour; the average dressing efficiency of the CMP conditioner of Embodiment 1 was improved by 31%. When the CMP conditioner of Embodiment 1 is applied to the pad, the space between the inclined plane and the side wall of the concave part makes the thickness of the pad recover to its original thickness; hence, the cutting depth is increased and the dressing performance of the CMP conditioner is also improved.
Even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and features of the invention, the disclosure is illustrative only. Changes may be made in the details, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.

Claims

What is claimed is:

1. A chemical mechanical polishing conditioner comprising:

a substrate comprising multiple concave parts, the concave parts formed in a surface of the substrate, and each concave part having a side wall;

multiple fixed plates, each fixed plate comprising a bottom, a top, a concavity and an inclined plane, the bottom fixed into the concave part, the top formed on the bottom in an integral configuration with a contact surface formed between the top and the bottom, the concavity formed in the top and opposite the bottom, the inclined plane formed between the contact surface and the concavity, a space formed between the inclined plane and the side wall, an angle formed between the inclined plane and the side wall, the angle ranging from 30° to 60°, inclusive; and

multiple abrasive units, each abrasive unit mounted in the concavity.

2. The chemical mechanical polishing conditioner as claimed in claim 1, wherein each fixed plate is fixed into the concave part through a binding layer, the binding layer is consisted of a ceramic material, a brazing material, an electroplating material, a metallic material, or a polymeric material.

3. The chemical mechanical polishing conditioner as claimed in claim 1, wherein each fixed plate is fixed into the concave part through a binding layer, the binding layer is selected from the group consisting of iron, cobalt, nickel, chromium, manganese, silicon, aluminum, and any combination thereof.

4. The chemical mechanical polishing conditioner as claimed in claim 1, wherein each fixed plate is fixed into the concave part through a binding layer, the binding layer is consisted of epoxy resin, polyester resin, polyacrylate resin, or phenol resin.

5. The chemical mechanical polishing conditioner as claimed in claim 1, wherein the concave parts are arranged on the surface of the substrate in concentric circles.

6. The chemical mechanical polishing conditioner as claimed in claim 1, wherein each abrasive unit has a tip opposite the concavity, and a vertical distance between the surface of the substrate and the tip of each abrasive unit ranges from 20 μm to 300 μm, inclusive.

7. The chemical mechanical polishing conditioner as claimed in claim 6, wherein the vertical distance between the surface of the substrate and the tip of each abrasive unit ranges from 100 μm to 300 μm, inclusive.

8. The chemical mechanical polishing conditioner as claimed in claim 1, wherein the chemical mechanical polishing conditioner has at least two vertical distances between the surface of the substrate and the tip of each abrasive unit, a difference between the vertical distances ranges from 20 μm to 100 μm, inclusive.

9. The chemical mechanical polishing conditioner as claimed in claim 1, wherein a cutting angle of each abrasive unit ranges from 30° to 150°, inclusive.

10. The chemical mechanical polishing conditioner as claimed in claim 1, wherein a crystal structure of each abrasive unit is hexahedral or octahedral.

11. The chemical mechanical polishing conditioner as claimed in claim 1, wherein the concave parts are formed through the substrate.