US20160121454A1 - Cmp pad conditioner and method for manufacturing the same - Google Patents

Abstract

Provided is a chemical mechanical polishing (CMP) pad conditioner including a substrate including a plurality of protrusions formed on at least one surface thereof and made of ceramic or hard metal alloy. The plurality of protrusions may be formed through laser processing so as not to have angled edges on an upper end and an inclined side thereof. The chemical mechanical polishing pad conditioner further includes a diamond thin film deposited so as to cover the plurality of protrusions, wherein the diamond thin film includes a rough polishing surface on which micro protrusions having a size of several μm are formed.

Description

BACKGROUND
• 1. Technical Field
• The present disclosure relates to a chemical mechanical polishing (CMP) pad conditioner and a method for manufacturing the same, and more particularly, to a chemical mechanical polishing (CMP) pad conditioner manufactured by forming protrusions having a size of several ten to several hundred μm on a surface of a substrate through laser processing and a diamond thin films including micro protrusions having a size of several μm on the protrusions, and a method for manufacturing the same.
• 2. Description of the Related Art
• A chemical mechanical polishing (CMP) process is used to polish a surface of a specific workpiece in various industries. Particularly, the CMP process has been mainly used to polish ceramic, silicon, glass, quartz, metal, and/or a wafer thereof in a manufacturing field such as a semiconductor device, a micro electronic device, a computer product, or the like. In the CMP process, a CMP pad rotating while facing the workpiece such as a wafer, or the like, is used. In addition, during the CMP process, a polishing particle and a liquid slurry containing a chemical material are added to the CMP pad.
• In a manufacturing field of a semiconductor device, yield and productivity of the semiconductor device is deteriorated due to a scratch or a defect generated on a wafer during the CMP process. Particularly, in the CMP process in which a wafer having a relatively large diameter is planarized using a CMP pad having a large size corresponding to the diameter of the wafer, impact and stress applied to the wafer and the CMP pad further increase, and the frequency of pollution by slurry and foreign material and a defect such as scratch, or the like, increases.
• In polishing quality by the CMP process, distribution of polished particles maintained in a state of being widely spread over the entire CMP pad is particularly important. An upper portion of the CMP pad generally supports the polished particles by a mechanism such as a fiber or a small void, which determine performance of the CMP pad. Therefore, in order to maintain performance of the CMP pad, an upper fiber structure of the CMP pad needs to be maintained in an upright state as flexible as possible, and extra voids capable of receiving new polished particles therein need to be sufficiently secured. To this end, a conditioning or dressing process of the CMP pad by a CMP pad conditioner is required.
• According to the related art, research into technologies for allowing a polishing pad to effectively perform polishing using small pressure and preventing surface roughness and separation of diamond particles has been conducted. As one of the technologies, a technology of manufacturing a CMP pad conditioner by forming protrusions having a regular arrangement separated by a ditch traversing a width/height and an approximately quadrangular pyramid shape on a substrate such as ceramic, hard metal alloy, or the like, through mechanical grinding or cutting processing and depositing a diamond on surfaces of the protrusion has been suggested (KR 10-0387954). According to a technical feature of the related art, sharp edges are provided on the protrusions of the substrate and the CMP pad is dressed using a cutting property by the edges. Here, in order to enhance a material, diamond thin films having high strength are deposited.
• However, in the case in which there are angled edges in the protrusions, the diamond thin films stacked on the protrusion may be easily separated/delaminated due to the edges. This is the reason that when the thin films are formed by depositing a diamond material on a surface of a substrate, the deposition is satisfactorily performed on a flat surface; however, the deposition or growth of the diamond is not satisfactorily performed on the sharp edge.FIG. 10 is a photograph showing a phenomenon in which a diamond thin film is delaminated at a protrusion formed by mechanical processing.
• In addition, according to the related art, even though the protrusion is formed on the surface of the substrate through the cutting processing, it is substantially impossible to freely adjust shapes of the protrusions as desired or differently control sizes of the protrusions.
BRIEF SUMMARY
• Embodiments of the present invention provide a chemical mechanical polishing (CMP) pad conditioner including protrusions on a surface of a substrate and diamond thin films deposited thereon and having an improved structure in which the protrusions are formed on the surface of the substrate so that they do not have angled edges to thereby reliably form the diamond thin film covering the protrusions, and protrusions having a size of several μm are formed at the time of growth of the diamond thin film are mainly used for polishing, and a method for manufacturing the same.
Technical Solution
• According to an exemplary embodiment of the present invention, there is provided a chemical mechanical polishing (CMP) pad conditioner including: a substrate including a plurality of protrusions formed on at least one surface thereof and made of ceramic or hard metal alloy, the plurality of protrusions being formed through laser processing so as not to have angled edges on an upper end and an inclined side thereof and a diamond thin film deposited so as to cover the plurality of protrusions, wherein the diamond thin film includes a rough polishing surface on which micro protrusions having a size of several μm are formed.
• Each of the protrusions may have a mountain shape in which an upper end thereof has an area smaller than that of a lower end thereof, and the upper end may have an area of 100 μm²or less.
• The diamond thin film may be formed through chemical vapor deposition (CVD).
• Each of the protrusions may have an angle of 100 degrees or more between a tangent line of the upper end thereof and a tangent line of the side thereof.
• The plurality of protrusions may have a height difference of 20 μm or less.
• A concave-convex pattern in which ridges and valleys are repeated may be formed in the vicinity of each of the protrusions.
• The substrate may be made of ceramic containing Si₃N₄.
• Two or more kinds of protrusions having different heights and sizes may be formed as a group.
• According to another exemplar embodiment of the present invention, there is provided a method for manufacturing CMP pad conditioner, the method including: (a) forming a plurality of protrusions on a surface of a substrate made of ceramic or hard metal alloy; and (b) depositing a diamond thin film so as to cover the plurality of protrusions, wherein in step (a), the protrusions are formed through laser processing so as not to have angled edges on an upper end and a side thereof.
• In step (a), the protrusions may be formed by a method for irradiating a laser beam while changing an overlapped interval at the time of irradiation of the laser beam on the surface of the substrate. More specifically, a laser beam spot has strength distribution having Gaussian distribution, such that when the laser beam is irradiated on the surface of the substrate, a ditch having a slope is formed as shown inFIG. 9. Here, a depth and a shape of the ditch by one-time irradiation are determined according to basic characteristics, an output, an irradiation time, or the like, of the laser beam. InFIG. 9, the protrusion is formed by processing a Si₃N₄sintered body with a solid laser beam. When the laser beam is irradiated in the vicinity of the protrusion in an overlapped scheme, a shape of the protrusions and a concave-convex pattern (ridge, valley) in the vicinity of the protrusion may be adjusted according to a condition such as a beam irradiation interval, or the like.
• In step (a), a concave-convex pattern may be formed in the vicinity of the protrusion by irradiating a laser beam on the surface of the substrate in an overlapped scheme.
• In step (a), the protrusions are formed so that an upper end of each of the protrusions has an area of 100 μm²or less.
• The protrusions may be formed so that each of the protrusions has an angle of 100 degrees or more between a tangent line of the upper end thereof and a tangent line of the side thereof.
• In step (b), the diamond thin film having micro protrusions may be deposited on the surface of the substrate through CVD.
• The entirety or a portion of the substrate may be processed by an acid/base solution in order to remove an oxide film or a residual after the laser processing in step (a).
• The method may further include machining the protrusions in order to separate the protrusions before or after the laser processing in step (a). The laser processing may be performed using a CO2 gas laser beam, an Nd solid laser beam, or a fiber laser beam.
• In step (b), a hot filament CVD method may be used.
Advantageous Effects
• As set forth above, according to the exemplary embodiments of the present invention, the plurality of protrusions that do not have the angled edge may be formed on the surface of the substrate through the laser processing, thereby making it possible to reliably form the diamond thin film on the surface on which the protrusions are formed. Unlink the CMP pad conditioner according to the related art in which the edge of the protrusion mainly performs a polishing function, in the case of the CMP pad conditioner according to the exemplary embodiments of the present invention, the micro protrusions having a size of several μm on the diamond thin film formed on the protrusion that does not have the angled edge mainly perform the polishing function. Therefore, performance of the CMP pad conditioner may be improved, and the separation/delamination of the diamond thin film due to obstruction of deposition and/or growth of the diamond thin film in the vicinity of the edge of the existing angled protrusion may be suppressed. In addition, the CMP pad conditioner according to the exemplary embodiments of the present invention includes the concave-convex pattern formed in the vicinity of the protrusions of the substrate through the laser processing. This concave-convex pattern satisfactorily mixes the slurry, thereby making it possible to improve the performance of the CMP pad conditioner.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
• FIG. 1 is a partially enlarged cross-sectional view of a CMP pad conditioner according to an exemplary embodiment of the present invention;
• FIG. 2 is an enlarged cross-sectional view of a substrate of the CMP pad conditioner shown inFIG. 1;
• FIGS. 3A and 3B are images showing surfaces of substrates on which protrusions are formed through laser processing according to an exemplary embodiment of the present invention;
• FIGS. 4A and 4B are views describing a method for forming protrusions and concave-convex patterns on a surface of a substrate through laser processing;
• FIGS. 5A and 5B are views describing several exemplary examples of a protrusion pattern formed on a surface of a substrate;
• FIG. 6 is a view describing a specific dimension and shape of a protrusion formed through laser processing according to an exemplary embodiment of the present invention;
• FIG. 7 is an enlarged image of a protrusion formed through laser processing;
• FIG. 8 is an image showing a state in which a diamond thin film is deposited on a surface of a protrusion;
• FIG. 9 is an image describing characteristics of a protrusion formed by a laser beam; and
• FIG. 10 is an image showing a problem such as a delamination phenomenon of the related art in which a diamond thin film is formed on a protrusion including an angled edge.
DETAILED DESCRIPTION
• FIG. 1 is a partially enlarged cross-sectional view of a CMP pad conditioner according to an exemplary embodiment of the present invention. Referring toFIG. 1, a CMP pad conditioner1 according to the present embodiment includes a plate shapedsubstrate10 made of ceramic or hard metal alloy, for example, cemented carbide and a diamondthin film20 deposited on a surface of thesubstrate10. When thesubstrate10 is made of a ceramic material, it may be mainly made of Si₃N₄. A plurality ofprotrusions11 having a height difference of approximately 20 μm or less, that is, a relatively uniform height is formed on one surface of thesubstrate10 through laser processing. The diamondthin film20 is formed by depositing a diamond material on the surface of thesubstrate10 using a chemical vapor deposition (CVD) process. The diamondthin film20 includes a rough polishing surface on whichmicro protrusions21 having several μm (approximately 1 μm or more) are formed.
• FIG. 2 is an enlarged cross-sectional view of a substrate of the CMP pad conditioner shown inFIG. 1. Referring toFIG. 2, theprotrusion11 on the surface of the substrate is shown in a state in which it is enlarged. Theprotrusion11 has a mountain shape in which an upper end thereof has an area smaller than that of a lower end thereof. The upper end has a significantly small area of 100 μm²or less. An angle A between a tangent line L1 of the upper end and a tangent line L2 of an inclined side of each of theprotrusions11 is defined as approximately 100 degrees or more.
• Therefore, each of theprotrusions11 may be formed to have an approximately pointed shape. However, the upper end of theprotrusions11 may be formed to have a smooth curved surface without a sharp apex. There are no angled edges on the upper end and the inclined side of theprotrusions11, which is possible by forming theprotrusion11 through the laser processing. A method for forming theprotrusions11 through the laser processing will be described in detail below.
• In addition, theparent material10 includes a concave-convex pattern in which ridges r and valleys v are continuously formed repeatedly on a surface of the substrate in the vicinity of theprotrusion11. When a shape, a size, and the like, of the concave-convex pattern is adjusted, a slurry may be appropriately mixed during a conditioning process of a CMP pad to thereby contribute to improving CMP conditioning performance of the CMP pad conditioner (SeeFIG. 3B). The repeated pattern of the ridges r and the valleys v, that is, the concave-convex pattern may also be easily formed through the laser processing. That is, the repeated pattern of the ridges r and the valleys may be formed by continuously irradiating a laser beam on the surface of thesubstrate10 in an overlapped scheme.
• Again referring toFIG. 1, the diamondthin film20 is formed to have an approximately uniform thickness so as to cover all of theprotrusions11, and theprotrusions11 do not have the angled edges. Therefore, the diamondthin film20 may be more reliably deposited on theprotrusions11 by the CVD process. That is, a concave-convex surface existing in theprotrusion11 in a concave-convex surface of the diamondthin film20 or the micro protrusions mainly perform a polishing function. Therefore, the CMP pad conditioner1 according to the present embodiment may sufficiently improve conditioning performance of the CMP pad without having a sharp edge in theprotrusion11.
• FIGS. 3A and 3B are images showing surfaces of substrates of a CMP pad conditioner on which protrusions are formed through laser processing according to an exemplary embodiment of the present invention. Referring toFIGS. 3A and 3B, it may appreciated that there are no angled edges in both of an upper end and a side of a protrusion shown at the center of an image and protruding to be the highest from a surface of a substrate. In addition, it may be appreciated that there is a concave-convex pattern in which ridges and valleys are repeatedly formed in the vicinity of the protrusion shown at the center of the image. The protrusion and the concave-convex pattern are formed by irradiating the laser beam on the surface of the substrate to cut the surface of the surface of the substrate, and more specifically, irradiating the laser beam in an overlapped scheme. In addition, when the laser beam is irradiated on the concave-convex pattern and the surface of the substrate in the overlapped scheme, in the case of changing an output of the laser beam, more shapes may be implemented.
• In order to manufacture the CMP pad conditioner according to the exemplary embodiment of the present invention, a plate shaped substrate made of ceramic or hard metal alloy is first prepared. Then, a plurality of protrusions and a concave-convex pattern are formed on a surface of the substrate through laser processing. Next, a diamond thin film is formed to have a thickness in μm on the surface of the substrate having the protrusions formed thereon through the CVD.
• FIGS. 4A and 4B are views describing a method for forming protrusions and concave-convex patterns on a surface of a substrate through laser processing.
• First, as shown inFIG. 4A, a process of definingregions2 at which the protrusions is to be formed on the surface of thesubstrate10 is performed. The process of defining the regions may include inputting the regions as coordinates to a laser processing device. Furthermore, the process of defining the regions may further include indicating outlines of the regions by drawing a line on the surface of the substrate with the laser beam. Theregion2 shown inFIG. 4A is a region of which an outline is indicated using a laser beam. AlthoughFIG. 4A shows a case in which the region has a rectangular shape, the region may also have a circular shape, a triangular shape, a pentagonal shape, or another geometrical shape. InFIG. 3B, which is a real processing example, the region has a rectangular outline. It may be appreciated fromFIG. 3B that the protrusion is formed without the edge according to characteristics of the laser beam.
• As shown inFIG. 4B, the laser beam B is irradiated on the surface of thesubstrate10 in an overlapped scheme, such that theprotrusion11 and the concave-convex pattern are formed. The concave-convex pattern has a shape in which the ridges r and valleys v are continuously repeated as described above. For convenience of illustration and understanding, only some of the laser beams B irradiated in an overlapped scheme in order to form theprotrusions11 and the concave-convex pattern are shown inFIG. 4B. At the time of formation of theprotrusions11, small protrusions may be additionally formed by slightly differently changing the outputs of the overlapped laser beams. These protrusions increase a contact area with a pad at the time of polishing, thereby improving polishing characteristics of the pad.
• In the present embodiment, the protrusions and the concave-convex pattern are formed on the surface of the substrate using an Nd solid laser beam having a wavelength of 1064 nm as a laser light source. However, the present invention is not limited thereto. Other laser light sources such as a CO₂gas laser beam, a fiber laser beam, or the like, may be used.
• FIG. 6 shows a specific dimension and shape of a protrusion formed through laser processing according to an exemplary embodiment of the present invention. In the Table shown inFIG. 6, a portion represented by Seg. 3 indicates an upper portion of the protrusion. Therefore, the upper portion of the protrusion has a horizontal distance of approximate 15 μm and a height of approximate 115 μm.
• FIG. 7 is an enlarged image of a protrusion formed through laser process; andFIG. 8 is an image showing a state in which a diamond thin film is deposited on a surface of a protrusion. Referring toFIGS. 7 and 8, the diamond thin film is deposited on a surface of the protrusion formed without the angled edge so as to have micro protrusions, which participate in real polishing in the conditioning process of the CMP pad.
• The entirety or a portion of the substrate may be processed by an acid/base solution in order to remove an oxide film, a residual, or the like, existing on the surface of the substrate on which the protrusions are formed, after the protrusions are formed on the surface of the substrate through the laser processing and before the diamond thin film is formed in the CVD scheme. In addition, as a method for depositing the diamond thin film on the surface of the substrate on which the protrusions are formed, the CVD technology as described above, and more preferably, a hot filament CVD method is used.
• A pattern of the protrusions formed on the substrate may be variously changed according to a laser processing scheme.FIGS. 5A and 5B show several examples of patterns of protrusions.
• FIG. 5A shows an example in which protrusions11aand11bare formed to have different heights on thesubstrate10. In the case in which theprotrusions11aand11bhave different heights, when the diamond thin film20 (SeeFIG. 1) formed on theprotrusion11ahaving a higher height is worn out and thus does not perform a polishing function, the diamondthin film20 formed on theprotrusion11bhaving a lower height may perform the polishing function. AlthoughFIG. 5A shows a case in which the protrusions have a height difference of two stages, the protrusions may also have a height difference of three or more stages as needed.
• FIG. 5B shows an example of a protrusion pattern in which at least twoprotrusions11 and11 are formed on the surface of thesubstrate10 in a state in which they are grouped into a plurality of groups G1, G2, and G3. This protrusion pattern may be obtained by, for example, defining a plurality ofregions2 on the surface of the substrate10 (SeeFIG. 4A) and forming the plurality ofprotrusions11 and11 in therespective regions2 through the laser processing on therespective regions2. AlthoughFIG. 5B shows a case in which two protrusions are continuously disposed, three or more protrusions may also be continuously disposed as needed.
• The various embodiments described above can be combined to provide further embodiments. All of the U.S. patents, U.S. patent application publications, U.S. patent applications, foreign patents, foreign patent applications and non-patent publications referred to in this specification and/or listed in the Application Data Sheet are incorporated herein by reference, in their entirety. Aspects of the embodiments can be modified, if necessary to employ concepts of the various patents, applications and publications to provide yet further embodiments.
• These and other changes can be made to the embodiments in light of the above-detailed description. In general, in the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification and the claims, but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled. Accordingly, the claims are not limited by the disclosure.

Claims (5)

1. A chemical mechanical polishing (CMP) pad conditioner comprising:

a substrate including a plurality of protrusions formed on at least one surface thereof and made of ceramic or hard metal alloy, the plurality of protrusions being formed through laser processing so as not to have angled edges on an upper end and an inclined side thereof; and

a diamond thin film deposited so as to cover the plurality of protrusions,

wherein the diamond thin film includes a rough polishing surface on which micro protrusions having a size of several μm are formed,

wherein the diamond thin film is formed through chemical vapor deposition (CVD), and

wherein the substrate is made of ceramic containing Si₃N₄.

2. The chemical mechanical polishing pad conditioner ofclaim 1, wherein each of the protrusions has a mountain shape in which an upper end thereof has an area smaller than that of a lower end thereof, and the upper end has an area of 100 μm²or less, and

wherein each of the protrusions has an angle of 100 degrees or more between a tangent line of the upper end thereof and a tangent line of the side thereof.

3. The chemical mechanical polishing pad conditioner ofclaim 1, wherein the plurality of protrusions have a height difference of 20 μm or less, and

wherein two or more kinds of protrusions having different heights and sizes are regularly formed.

4. The chemical mechanical polishing pad conditioner ofclaim 1, wherein a concave-convex pattern in which ridges and valleys are repeated is formed in a vicinity of each of the protrusions.

5. The chemical mechanical polishing pad conditioner ofclaim 1, wherein the protrusions are grouped into a plurality of groups, and each of the plurality of groups is spaced apart from each other while including at least two protrusions.

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