Source: http://www.google.com/patents/US7516536?dq=6,595,873
Timestamp: 2014-07-26 17:22:48
Document Index: 93841799

Matched Legal Cases: ['art.\n5', 'Application No. 2004', 'art 58', 'art 58', 'art 58', 'art 58', 'art 58', 'art 58', 'art 58', 'arts 58', 'arts 58', 'arts 58', 'arts 58', 'arts 58', 'arts 58', 'arts 58', 'arts 58', 'arts 58', 'arts 58', 'arts 58', 'arts 58', 'arts 58', 'arts 58', 'arts 58', 'arts 58', 'arts 58', 'arts 58', 'arts 58', 'arts 58', 'arts 58', 'arts 58', 'arts 58', 'arts 58', 'arts 58', 'arts 58', 'arts 58', 'arts 58', 'arts 58', 'arts 58', 'arts 58', 'arts 58', 'arts 58', 'arts 58', 'art 58', 'art 58']

Patent US7516536 - Method of producing polishing pad - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign in<nobr>Advanced Patent Search</nobr>PatentsA method of manufacturing a grooved polishing pad wherein a large number of grooves, extending parallel to each other, are fabricated at specific intervals on at least one of a front surface and a back surface of a polishing pad substrate through a groove cutting process on the polishing pad substrate...http://www.google.com/patents/US7516536?utm_source=gb-gplus-sharePatent US7516536 - Method of producing polishing padAdvanced Patent SearchPublication numberUS7516536 B2Publication typeGrantApplication numberUS 11/301,361Publication dateApr 14, 2009Filing dateDec 12, 2005Priority dateJul 8, 1999Fee statusPaidAlso published asUS20060154577Publication number11301361, 301361, US 7516536 B2, US 7516536B2, US-B2-7516536, US7516536 B2, US7516536B2InventorsTatsutoshi SuzukiOriginal AssigneeToho Engineering Kabushiki KaishaExport CitationBiBTeX, EndNote, RefManPatent Citations (64), Non-Patent Citations (1), Referenced by (1), Classifications (10), Legal Events (2) External Links: USPTO, USPTO Assignment, EspacenetMethod of producing polishing padUS 7516536 B2Abstract A method of manufacturing a grooved polishing pad wherein a large number of grooves, extending parallel to each other, are fabricated at specific intervals on at least one of a front surface and a back surface of a polishing pad substrate through a groove cutting process on the polishing pad substrate which is made from a synthetic resin material, the method comprising the steps of: cutting, by using a multi-edged tool having a plurality of pad groove machining cutting parts, arrayed at equal spacing p with the spacing p being an integer multiple no less than 2 of a desired spacing d of the grooves, a plurality of the grooves; and repeating the cutting of the plurality of grooves through shifting the multi-edged tool in a direction in which the pad groove machining cutting parts are arrayed, in order to fabricate the large number of grooves, extending parallel to each other, with the desired spacing d.
1. A method of manufacturing a grooved polishing pad wherein a number of grooves, extending parallel to each other, are fabricated at specific intervals on at least one of a front surface and a back surface of a polishing pad substrate through a groove cutting process on the polishing pad substrate, which is made from a synthetic resin material, the method comprising the steps of:
cutting, by using a multi-edged tool having a plurality of pad groove machining cutting parts, arrayed at equal spacing p with the spacing p being an integer multiple no less than 2 of a desired spacing d of the grooves, a plurality of the grooves; and
repeating the cutting of the plurality of grooves through shifting the multi-edged tool in a direction in which the pad groove machining cutting parts are arrayed, in order to fabricate the number of grooves, extending parallel to each other, with the desired spacing d.
2. A method of manufacturing a grooved polishing pad according to claim 1, wherein the cutting of the plurality of grooves is performed by using the multi-edged tool, and wherein the spacing p of the plurality of cutting pats for fabricating the grooves, which are arrayed in the multi-edged tool, is twice the spacing d of the grooves to be cut into the polishing pad substrate.
3. A method of manufacturing a grooved polishing pad according to claim 1, wherein the plurality of grooves formed on the polishing pad substrate are circumferential grooves extending in a direction of a circumference of the polishing pad substrate.
4. A method of manufacturing a grooved polishing pad according to claim 1, wherein the cutting of the plurality of grooves is performed by using the multi-edged tool, wherein the spacing p for the plurality of pad groove machining cutting parts, which are arrayed in the multi-edged tool, are such that 0.5 mm ≦p≦30 mm, and wherein at least one of the cutting parts is a two-stage cutting part having two wedge angles leading to a cutting edge of the respective cutting part.
5. A method of manufacturing a grooved polishing pad according to claim 1, wherein the plurality of grooves are formed on the polishing pad substrate while blowing a cooling fluid onto the pad groove machining cutting parts.
6. A method of manufacturing a grooved polishing pad according to claim 5, wherein the cooling fluid comprises an ionic air.
7. A method of manufacturing a grooved polishing pad according to claim 1, wherein the cutting of the plurality of grooves is performed by using the multi-edged tool, and wherein each of the pad groove machining cutting parts includes a curve at a position between 0.05 mm and 1.0 mm high from a blade edge on a front clearance face thereof, and has a wedge angle θ1, on a blade edge side of the curve, in the range of 25�≦θ1≦87�, while has a wedge angle θ2, on a base part side of the curve, being such that θ2<θ1.
8. A method of manufacturing a grooved polishing pad according to claim 7, wherein the cutting of the plurality of grooves is performed by using the multi-edged tool, and wherein a surface roughness of a region on the blade edge side of the curve on the front clearance face has an Ry value of no more than 3 μm.
9. A method of manufacturing a grooved polishing pad according to claim 7, wherein the cutting of the plurality of grooves is performed by using the multi-edged tool, and wherein a surface processing is performed on a blade edge side region of the curve on the front clearance face so that the surface roughness of the blade edge side region is less than that of a base part side region, on an other side of the curve.
10. A method of manufacturing a grooved polishing pad according to claim 7, wherein the cutting of the plurality of grooves is performed by using the multi-edged tool, and wherein a front clearance angle αof the blade edge side of the curve in each of the pad groove machining cutting parts is in a range of 3�≦α≦60�.
11. A method of manufacturing a grooved polishing pad according to claim 7, wherein the cutting of the plurality of grooves is performed by using the multi-edged tool, and wherein a surface treatment by lapping, using diamond particles of 10 μm or less, is performed on the blade edge side region of the curve on the front clearance face.
12. A method of manufacturing a grooved polishing pad according to claim 7, wherein the cutting of the plurality of grooves is performed by using the multi-edged tool, and wherein at a position on the multi-edged tool where a height is 2.0 mm in a direction of a depth of each groove from a blade edge on the front clearance face, the position is at a distance of separation of no more than 2.5 mm from the blade edge in a direction of cutting.
13. A method of manufacturing a grooved polishing pad according to claim 7, wherein the cutting of the plurality of grooves is performed by using the multi-edged tool, and wherein a nose radius R of the blade edge in each of the pad groove machining cutting parts is such that R ≦0.05 mm.
14. A method of manufacturing a grooved polishing pad according to claim 7, wherein the cutting of the plurality of grooves is performed by using the multi-edged tool, and wherein side clearance angles are provided on both end faces, in a width direction of the respective cutting part, in the pad groove machining cutting parts.
15. A method of manufacturing a grooved polishing pad according to claim 7, wherein the cutting of the plurality of grooves is performed by using the multi-edged tool, and wherein the cutting of the plurality of grooves is performed by using the multi-edged tool wherein the pad groove machining cutting parts are fabricated from an alloy or a steel.
16. A method of manufacturing a grooved polishing pad according to claim 7, further comprising the step of upon shifting the multi-edged tool in a direction in which the pad groove machining cutting parts are arrayed, shifting the multi-edged tool by a distance more than a distance between outermost end cutting parts of the multi-edged tool with respect to the polishing pad substrate. Description
CROSS-REFERENCE TO RELATED APPLICATION This is a Continuation-in-Part of application Ser. No. 10/830,567 filed Apr. 23, 2004, now U.S. Pat. No. 7,104,868, incorporated herein by reference and which is a Divisional of application Ser. No. 10/026,504 filed Dec. 19, 2001, now U.S. Pat. No. 6,869,343.
INCORPORATED BY REFERENCE The disclosure of Japanese Patent Application No. 2004-359025 filed on Dec. 10, 2004 including the specification, drawings and abstract is incorporated herein by reference in its entirety.
The present invention relates to technologies relating to polishing pads used in, for example, the CMP method (chemical-mechanical polishing method), and, in particular, relates to a method for manufacturing grooved polishing pads wherein a multiple grooves are formed on the front surface and/or back surface thereof in order to increase the polishing precision.
Conventionally, technologies have been known for polishing processes for high precision polishing of objects using polishing pads in the form of thin disks of synthetic resin materials. For example, in recent years there has been a great deal of interest in providing technologies for performing CMP of semiconductor wafers and devices with multilayer structures such as conductive layers on the surface of semiconductor layers. In particular, given increases in the density of the electronic components to be polished, there is the need for greater precision and greater efficiency polishing processes, and in CMP in particular. There have been reports of not only improvement in polishing devices, slurries, polishing pad materials, and so forth, to this end, but also reports of the effectiveness of forming grooves of the appropriate shapes on the front and or back surfaces of the polishing pads.
These types of polishing pads used in CMP are conventionally made from synthetic resin materials, and, typically, the grooves of appropriate shapes are molded at the same time as the fabrication of the polishing pads. However, given the increasingly rigorous requirements for polishing precision, the present inventors, aware of the limitations in the fabrication of grooves using molding, have been the first to propose the fabrication of grooves using a cutting (machining) process. Moreover, in this type of cutting of grooves, typically a large number of grooves adjacent one another in parallel are cut simultaneously through a multi-edged tool that is equipped with a plurality of blade edge parts arranged in parallel to one another in order to raise the efficiency of the machining cycle.
However, in order to achieve high precision polishing, as well as in order to achieve effective cutting with respect to a soft polishing pad, it is desirable to form a large number of grooves with a small pitch and a small width onto a surface of the polishing pad, as pointed out in the previous application by the present inventors. In particular, the groove widths and groove pitches have been miniaturized to their limits in order to respond to recent requirements for high levels of high precision polishing performance.
At this point, in machining of polishing pads using conventional multi-edged tools, the gaps between the individual blade edge parts provided in the multi-edged tools have become narrow due to the narrowing of the desired groove pitch. Because of this, the frictional heating that occurs repetitively in the blade edge parts due to the friction with the polishing pads is concentrated on the narrow parts positioned between the blade edge parts in the polishing pads, with the risk of causing problems such as thermal deformation of the polishing pads, which are made from synthetic resin.
Further, the narrower gaps between the individual blade edge parts will cause low air flows flowing through the gaps. This may cause deterioration in cooling performance by means of the air flows flowing through the gaps, thereby enhancing the risk of the heating problems. In order to address the heating problems, the cutting speed must be decreased, thereby lowering the machining rate.
Moreover, where the individual blade edge parts make small in the width length and the gap distance, manufacturing of the blade edge parts becomes difficult, and defects or dimensional errors of the blade edge parts may occur readily.
In addition, the narrower gaps between the individual blade edge parts may readily cause the sticking of the cutting parts against the gaps. This may further deteriorate air flows through the gaps between the individual blades, so that the resultant insufficient cooling may cause additional problems. The cutting parts stuck to gaps between adjacent blade edge parts may be welded due to the heat of the blade edge parts, thereby ragging the cutting surfaces of the grooves, leading readily to deterioration in cutting accuracy of the grooves.
SUMMARY OF THE INVENTION It is therefore one object of this invention to provide a new method of manufacturing a grooved polishing pad, capable of fabricating a large number of grooves with a narrow groove gap and capable of producing a polishing pad that provides high-precision polishing.
The above and/or optional objects of this invention may be attained according to at least one of the following modes of the invention. The following modes and/or elements employed in each mode of the invention may be adopted at any possible optional combinations.
The present invention relates to a method of manufacturing a grooved polishing pad. A first mode of the invention provides a method of manufacturing a grooved polishing pad wherein a large number of grooves, extending parallel to each other, are fabricated at specific intervals on at least one of a front surface and a back surface of a polishing pad substrate through a groove cutting process on the polishing pad substrate which is made from a synthetic resin material, the method comprising the steps of: cutting, by using a multi-edged tool having a plurality of pad groove machining cutting parts, arrayed at equal spacing p with the spacing p being an integer multiple no less than 2 of a desired spacing d of the grooves, a plurality of the grooves; and repeating the cutting of the plurality of grooves through shifting the multi-edged tool in a direction in which the pad groove machining cutting parts are arrayed, in order to fabricate the large number of grooves, extending parallel to each other, with the desired spacing d.
Given this type of method of manufacturing a grooved polishing pad according to the present form of embodiment, a multi-edged tool that has a relatively large blade edge spacing can be used even when fabricating grooves with a small groove spacing. Consequently, it is possible to avoid the concentration at a narrower area on the polishing pad substrate of the heat due to the friction between the pad groove cutting parts and the polishing pad substrate. That is, because the blade edge spacing in the multi-edged tool is large, the heat due to friction between the cutting parts and the polishing pad substrate can be dispersed into the relatively large area of the polishing pad substrate, making it possible to avoid machining defects due to the deformation and melting of the pad, and possible to improve the machining efficiency.
Moreover, because a multi-edged tool with a large cutting edge spacing can be used, the air flow in the cutting edge spacing can be utilized to increase the cooling rate, not only making it possible to more effectively avoid machining defects due to heating of the cutting edges, but also making it possible to reduce the wear of the blade edge parts of the multi-edged tools due to heating, thereby making it possible to beneficially extend the useful life of the tool.
Furthermore, even if the groove spacing are to be made smaller, because the blade edge spacing in the multi-edged tool is an integer multiple (two times or more) of the groove spacing, the blade edge spacing can still be comparatively large. Because of this, even in those multi-edged tools that are used when fabricating grooves with narrow groove spacing, the machining can be done with relative ease when compared to the cutting edge parts for which the machining tends to be difficult, making it possible to achieve effectively the manufacturing of a multi-edged tool that is able to produce effectively the desired grooves with lower labor and high manufacturing precision.
A second mode of the invention provides a method of manufacturing a grooved polishing pad according to the aforementioned first mode, wherein the cutting of the plurality of grooves is performed by using the multi-edged tool wherein the spacing p of the plurality of cutting parts for fabricating the grooves, which are arrayed in the multi-edged tool, is twice the spacing d of the aforementioned grooves to be cut into the aforementioned polishing pad substrate.
The method for manufacturing a grooved polishing pad according to the present mode enables the fabrication of grooves in a polishing pad substrate at half the spacing of the pad groove machining cutting part, enabling the grooves that are fabricated with the desired groove spacing d to be achieved with superior machining efficiency with a relatively small number of machining steps as well as a reduced number of dislocation of the multi-edged tool in the widthwise direction.
A third mode of the invention provides a method of manufacturing a grooved polishing pad according to the aforementioned first or second mode, wherein the the plurality of grooves formed on the polishing pad substrate are circumferential grooves extending in a direction of a circumference of the polishing pad substrate.
Given the method for manufacturing grooved polishing pads according to the present mode, having the grooves that are formed in the polishing pad substrates be circumferential grooves that extend in the circumferential direction enables the specific grooves to be achieved easily through a turning process. Note that the �circumferential grooves that extend in the circumferential direction of the polishing pad substrate� in the present mode are, for example, grooves that extend in concentric circles, grooves that extend in a spiral shape, grooves that extend windingly in the circumferential direction in a petal shape, a star shape and a polygon shape, and so forth.
A fourth mode of the invention provides a method of manufacturing a grooved polishing pad according to any one of the first through third modes, wherein the cutting of the plurality of grooves is performed by using the multi-edged tool wherein the spacing p for the plurality of pad groove machining cutting parts, which are arrayed in the multi-edged tool, are such that 0.5 mm≦p≦30 mm.
Given the method for manufacturing a grooved polishing pad according to the present embodiment, not only can the setting of the groove spacing in the range as described above enable the effective use of the air flow that flows between the pad groove machining cutting parts to have a cooling effect on the blade edge parts, but also enables the achievement of superior manufacturability through preventing any remarkable increase in the amount of machining work in the machining of the grooves in the polishing pad substrate. If the spacing p of the pad groove machining cutting parts were too small, then the amount of air flow that flows between the pad groove machining cutting parts during the cutting process would be small, making it difficult to achieve adequate cooling of the pad groove machining cutting parts. On the other hand, if the spacing p between the pad groove machining cutting parts is too large, then in order to fabricate the grooves with the desired spacing d it would require a large number of repeated machining processes comprising cutting grooves using the multi-edged tool and then moving the multi-edged tool, which could reduce the productivity. Preferably, the spacing p for the plurality of pad groove machining cutting parts, which are arrayed in the multi-edged tool, are such that 0.5 mm≦p≦30 mm, preferably, 1 mm≦p≦20 mm, more preferably, 2 mm≦p≦10 mm.
A fifth mode of the invention provides a method of manufacturing a grooved polishing pad according to any one of the first through fourth modes, wherein the plurality of grooves are formed on the polishing pad substrate while blowing a cooling fluid onto the pad groove machining cutting parts.
Given the method for manufacturing a grooved polishing pad according to the present form of embodiment, the act of blowing of a cooling fluid onto the pad groove machining cutting parts can effectively suppress the heating of the pad groove machining cutting parts by friction. In this method in particular, the spacing p between adjacent pad groove machining cutting parts is made large relatively, whereby a sufficient amount of cooling fluid can be blown through the spacing between the adjacent cutting parts, resulting in an enhanced effect of the cooling fluid. Accordingly, it is possible to fully increase the cutting speed, enabling an increase in machining efficiency.
A sixth mode of the invention provides a method of manufacturing a grooved polishing pad according to any one of the first through fifth modes, wherein the cooling fluid comprises an ionic air.
Given the method for manufacturing a grooved polishing pad according to the present mode, the blowing of the ionic air onto the pad groove machining cutting part can produce the same cooling effect as in the aforementioned fifth form of embodiment, and can improve the machining efficiency. Furthermore, the use, as the cooling fluid, of ionic air can blow ions onto the cutting positions, which can effectively suppress the static electricity that is caused by the friction between the pad groove machining cutting part and the polishing pad substrate. This provides an static electricity suppressing effect, thereby effectively preventing the electrostatic adhesion of shavings onto the polishing pad substrate, which enables the specific groove machining to be achieved with high precision.
The employed ionic air may have an opposite charge in order to suppress electric charge. Generally, since the resin pad substrate will be charged negatively, a positive ionic air can be blown effectively, and since the multi-edged tool of metal will be positively charged, a negative ionic air can be blown effectively. In the case where the pad substrate and the multi-edged tool both suffer from the problem of the electric charge, the ionic air positively charged and ionic air negatively charged can be adequately applied.
Note that while the ionic air may be blown in any direction relative to the blade edge positions, preferably the airflow should be blown towards the front from the rear in the direction of travel of the blade edge. When machining grooves in a polishing pad substrate made from a synthetic resin material, the shavings are produced in the forward direction of travel of the blade edges, and when these shavings get into the gaps between the blade edges of the pad groove machining cutting parts, these shavings may be melted by the heat of friction and adhere to the pad groove machining cutting parts, which can produce problems in that it becomes impossible to achieve an adequate cooling effect by the airflow between the blade edges of the pad groove machining cutting parts. Given this, blowing the ions towards the blade edges from behind the pad groove machining cutting parts, in the direction of travel, can effectively prevent the occurrence of the problems described above due to obstructions in the airflow due to shavings getting between the blade edges.
More preferably, the opening of a vacuum suction of a vacuum tube is positioned in front of the multi-edged tool, in the direction of travel, along with blowing off the cutting position (the pad groove machining cutting parts) from behind, in the direction of travel of the cutting parts, with the ion blow, as described above. That is, along with the ion blow preventing the shavings from getting between the blade edges, the shavings should be removed through suction, to remove the shavings as quickly as possible from the operating environment, using a negative pressure suction opening.
A seventh mode of the invention provides a method of manufacturing a grooved polishing pad according to any one of the first through sixth modes, wherein the cutting of the plurality of grooves is performed by using the multi-edged tool wherein each of the pad groove machining cutting parts includes a curve at a position between 0.05 mm and 1.0 mm high from a blade edge on a front clearance face thereof, and has a wedge angle θ1, on a blade edge side of the curve, in the range of 25�≦θ1 ≦87�, while has a wedge angle θ2, on a base part side of the curve, being such that θ2<θ1.
In experiments and research by the present inventors, it was discovered that in pad groove machining cutting parts according to conventional structures there were the dangers of the following problems occurring depending on the pad substrate materials and depending on the machining parameters, etc:
(1) There is a tendency to produce defects due to chips in the blade edge. In particular, there is a tendency to have this problem in cutting parts made from an ultrahard alloy, more than from high-speed steel. (2) The useful life of the tooling is short. (3) It has been difficult to improve the roughness of the bottom surfaces of the grooves produced. At this point, when pad groove machining cutting parts structured as described in the present mode are used in a method for manufacturing grooved polishing pads, curves are provided on the front clearance faces of the pad groove machining cutting parts and the front clearance angles are given 2-stage structures so that the small wedge angle θ2 on the base part side will cause the front clearance faces of the cutting parts to essentially stand greatly upright, making it possible to avoid tool interferences with the groove side surfaces when machining grooves with small radii of curvature, while having the wedge angles of the blade edge parts, which have the blade edges, be large, thereby insuring strength, etc., not only (1) preventing chips in the blades, but also (2) enabling increases in the useful life of the tool.
The use of this 2-stage blade structure, which has two stages of angles on the front clearance face, as the distinctive characteristic of the structure in this way makes it possible to suppress increases in the dimensions in the direction of thickness of the blade, and thereby suppress interferences with the inner surfaces of the grooves at both of the edges of the cutting parts in the transverse direction when performing the machining of grooves with large curvatures. Namely, the wedge angle is set to be essentially small at the base part side (the side that is opposite from the blade edge) in the cutting part, and as a result, it is possible to maintain excellent machining surface precision on the inner surfaces on both sides of the grooves. Additionally, because the wedge angles are set to be essentially large angles at the cutting tool blade parts, it becomes possible to insure beneficially the strength and durability of the blade edges, and thereby possible to obtain excellent precision and surface roughness of the bottom parts of the grooves that are formed thereby.
Moreover, in the present mode in particular, the provision of the curve on the front clearance face of the cutting part, rather than a cutting face on the cutting part, makes it possible to insure a specific cutting angle. As a result, it is possible to obtain even greater effectiveness in the effect of improving the aforementioned strength and durability while insuring excellent cutting performance on polishing pads made from synthetic resin materials in particular.
Furthermore, in the present mode, the size of the wedge angle θ1 of the blade edge side is set in a specific range, making it possible to effectively demonstrate the effects described above. In other words, having the wedge angle θ1 too small makes it difficult to insure the strength of the blade edge part, while, on the other hand, having the wedge angle θ1 too large increases the amount of contact between the front clearance face and the bottom surface of the groove, along with making it impossible to avoid effectively tooling interferences when performing the cutting process, with the risk of problems such as generating frictional heating and static electricity. Preferably, the wedge angle θ1 is held in a range of 30�≦θ1≦70�.
Furthermore, in the present mode, the formation of a large wedge angle θ1 on the blade edge side makes the manufacturing of the cutting part easier by reducing the occurrence of chipped blades when manufacturing the blade edge parts of the pad groove machining cutting parts. Note that were the positioning of the curve less than 0.05 mm high, it would be difficult to fully realize the effect of improving the durability and strength of the cutting part, and, conversely, were the position more than 1.0 mm high, there would be the danger of the occurrence of problems with interferences between the side wall surfaces of the grooves and the blades when cutting grooves with tight radii of curvature.
Note that in the present mode, the distance of the position of the curve from the blade edge is set so as to be less than the depth dimension desired for the groove to be fabricated, thereby enabling the cutting part to demonstrate the effects of suppressing interferences with the inside surfaces of the grooves on both edges of the cutting part in the transverse direction. Here the �position of 0.05 mm to 1.0 mm from the blade edge, where the curve is formed� in the present mode indicates the height position in the direction of depth of the pad groove. Consequently, the position of the curve on the face of the front clearance face is determined by the magnitude of the front clearance angle. In other words, if the front clearance angles relative to the piece being cut are different, then the height positions of the curves will also be different, even if the cutting parts have the same wedge angles.
An eighth mode of the invention provides a method of manufacturing a grooved polishing pad according to the seventh mode, wherein the cutting of the plurality of grooves is performed by using the multi-edged tool wherein a surface roughness of a region on the blade edge side of the curve on the front clearance face has an Ry value of no more than 3 μm.
In the method for manufacturing a grooved polishing pad according to the present mode, an even greater level of machining precision can be obtained on the bottom surface of the groove for the method for manufacturing a grooved polishing pad according to the aforementioned seventh form of embodiment.
In other words, in the cutting tool as shown in the seventh mode of embodiment, which has a 2-stage structure for the front clearance angle, there is the danger of the following new problems (4) through (7) occurring, where these problems can conceivably occur due to the wedge angle of the blade edge part being increased under specific conditions, such as the characteristics of the pad substrate materials:
(4) Depending on the pad substrate materials, the amount of contact between the front clearance face and the bottom surface of the grooves may increase during the cutting processes, due to elastic deformation, etc., of the pad substrate materials, which tends to cause the adherence of cutting chips or shavings (resin dust) to the machined surfaces, which is thought to be caused by static electricity that is generated by the contact. The adherence of these shavings can cause the shavings to cut into the machined surfaces during repetitive machining, which may cause the cut surfaces to be rough. (5) The amount of heat produced by the blade edge part, which is assumed to be due to frictional heating, when the cutting process is performed may prevent the cutting speed from being as fast as possible, which may reduce machining efficiency, depending on, for example, the pad substrate material. (6) There is the danger of an impact on the inside surfaces of the gaps in the pad due to heating of the blade edge parts, depending on the pad substrate materials, etc., when the cutting speed in increased. (7) There is the danger of a negative impact on the useful life of the tooling due to the production of heat in the blade edge parts when the speed of processing is increased.
Note that the present form of embodiment can solve not only the aforementioned (1) through (3), but can also solve these new problems (4) through (7) as well. More specifically, in the method for manufacturing a grooved polishing pad according to the present form of embodiment, increasing the wedge angle of the blade edge side of the curve to insure an appropriate thickness dimension for the blade edge part can insure the strength of the blade edge part, while, at the same time, reducing the wedge angle of the base part side of the curve to cause the front clearance face to greatly stand upward can reduce tooling interferences with the side wall surfaces of the grooves, as described above, in the same way as for the seventh form of embodiment. While this can avoid tooling interferences with the side surfaces of the grooves when cutting grooves with small radii of curvature, this can also not only (1) prevent chips in the blades, but also (2) increase the useful life of the tools, while, by reducing the surface roughness of the blade edge side of the curve on the front clearance face, (3) the roughness of the bottom surface of the groove can be reduced.
Furthermore, in the present form of embodiment, making the surface of the blade edge side of the curve smooth can (4) increase the machining precision of the cut surface by suppressing the adhesion of shavings through reducing the occurrence of static electricity due to the increases in the amount of contact between the blade edge part and the surface of the bottom of the grooves, even when using those polishing pads that are made from materials for which static electricity has been a problem, such as synthetic resin materials. In addition, reducing the heat that is produced at the blade edge part when performing the machining can (5) increase the cutting speed and increase the cutting efficiency, and can not only (6) reduce the negative impact on the inside surfaces of the pad grooves, but can also (7) achieve an improvement in the useful life of the tooling, and thus even through this particular structure, that is, a structure having a 2-stage structure in the front clearance angle, is used, it is possible to avoid effectively the new problems, described above, resulting therefrom.
Note that a variety of machining processes for improving the surface roughness may be used as the surface processing on the region on the blade edge side on the front clearance face, where, along with lapping, polishing, buff finishing, ultrasonic treatments, plating, and the like, may be used. In the present mode, more preferably Ry≦1.0 μm, and even more preferably Ry≦0.5 μm, and even more preferably Ry≦0.25 μm. Note that the Ry value is the highest specified in JIS B0601-1994.
A ninth mode of the invention provides a method of manufacturing a grooved polishing pad according to the seventh or eighth mode, wherein the cutting of the plurality of grooves is performed by using the multi-edged tool wherein a surface processing is performed on a blade edge side region of the curve on the front clearance face so that the surface roughness of the blade edge side region will be less than that of a base part side region, on an other side of the curve.
The method for manufacturing a grooved polishing pad according to the present form of embodiment is able to avoid effectively new problems with the dangers that arise due to the use of the specific structure in the 2-stage structure in the front clearance angle, in the same manner as in the aforementioned eighth form of embodiment, and can form grooves with small radii of curvature, with excellent machining precision through suppressing the tool interferences that occur during the cutting process, the same as in the aforementioned seventh and eighth forms of embodiment. Note that in the present mode, the surface treatment may be performed both on the region on the blade edge side of the curve, and also on the region on the base part side of the curve.
A tenth mode of the invention provides a method of manufacturing a grooved polishing pad according to any one of the seventh through ninth modes, wherein the cutting of the plurality of grooves is performed by using the multi-edged tool wherein a front clearance angle α of the blade edge side of the curve in the pad groove machining cutting part is in a range of 3�≦α≦60�.
In the method for manufacturing a grooved polishing pad according to the present form of embodiment, having the front clearance angle α of the blade edge side of the curve be in the specific range makes it possible to avoid tooling interferences when performing the machining, and to reduce more effectively the adherence of shavings and the production of heat in the blade edge part. That is, when the front clearance angle α is too large, the blade edge part that contacts the pad will stand up, which is essentially the same as using a cutting tool with a small wedge angle, which can cause chipping of the blade edge part, and insufficient durability. On the other hand, if the front clearance angle α is too small, then the amount of contact between the blade edge part and the pad substrate will be large, which may prevent the desired effect of reducing the heating or charging of the blade edge part.
Note that the front clearance angle α of the blade edge side of the curve in the present form of embodiment is in the range described above, and is determined by a combination of the cutting face of the pad groove machining cutting part and the cutting angle, which is 0� or more, that is formed by the surface that is perpendicular relative to the polishing pad substrate. Note that, preferably, the front clearance angle α is such that 10�≦α≦60�, more preferably 20�≦α≦50�.
An eleventh mode of the invention provides a method of manufacturing a grooved polishing pad according to any one of the seventh through tenth modes, wherein the cutting of the plurality of grooves is performed by using the multi-edged tool wherein the performance of a surface treatment by lapping, using diamond particles of 10 μm or less, on the blade edge side region of the curve on the front clearance face.
In the method for manufacturing a grooved polishing pad according to the present mode, the surface roughness of the region on the blade edge side of the curve can be reduced effectively. Doing so can reduce effectively the wear of the surface in the region on the blade edge side of the curve. This can also delay the start and advancement of the initial wear, enabling the effective maintenance of the machining precision over an extended period. Note that, more preferably, a surface treatment using lapping with diamond particles of less than 5 μm is more preferable, where a well-known lapping process may be performed in a form that uses a slurry with an appropriate solvent, or the like.
A twelfth mode of the invention provides a method of manufacturing a grooved polishing pad according to any one of the seventh through eleventh modes, wherein the cutting of the plurality of grooves is performed by using the multi-edged tool wherein a position where a height is 2.0 mm, in a direction of a depth of each groove, from a blade edge on the front clearance face is at a distance of separation of no more than 2.5 mm from the blade edge in a direction of cutting.
In this type of method for manufacturing a grooved polishing pad according to the present mode, the width dimension in the front-back direction, in the direction of cutting by the pad groove machining cutting part enables the roughness of the machined surface to be effectively eliminated or decreased through decreasing the interferences between the side surfaces of the blades and the side surfaces of the tools even when cutting grooves with small radii of curvature. More preferably, the design should be such that the position that is 2.0 mm high, in the direction of depth of the groove, from the blade edge has a distance of separation of no more than 2.0 mm from the blade edge in the direction of cutting.
A thirteenth mode of the invention provides a method of manufacturing a grooved polishing pad according to any one of the seventh through eleventh modes, wherein the cutting of the plurality of grooves is performed by using the multi-edged tool wherein a nose radius R of the blade edge in each of the pad groove machining cutting parts is such that R≦0.05 mm.
Typically, nearly all polishing pad substrates are formed out of a synthetic resin material, and when performing machining on this type of synthetic polymer material, it is desirable for the blade edge of the pad groove machining cutting part to have a sharp shape. However, conventionally the blade edge has been formed into a rounded surface, not withstanding the reduction in machining precision, due to the need to insure the strength of the blade edge, in response to this problem, the pad groove machining cutting part used in the method for manufacturing a grooved polishing pad according to the present form of embodiment, the strength of the blade edge part can be increased through the use of a blade edge part having a specific structure, enabling the nose radius R of the blade edge part to be made smaller. Reducing the nose radius R of the blade edge part enables the cutting of the polishing head substrate, which is typically made of a synthetic resin material, to be performed with greater machining precision. Note that, as is obvious from the above, it is desirable for the nose radius R of the blade edge to be as small as possible, and, in practice, the blade edge part can also be made sharp, with a nose radius R of 0.
A fourteenth mode of the invention provides a method of manufacturing a grooved polishing pad according to any one of the seventh through thirteenth modes, wherein the cutting of the plurality of grooves is performed by using the multi-edged tool wherein side clearance angles being provided on both end faces, in a width direction of the cutting part, in the pad groove machining cutting parts.
In this type of method for manufacturing, a grooved polishing pad manufactured according to the present mode, interferences with the side surfaces of the grooves by the width-direction edge faces of the blades of the pad groove machining cutting parts can be avoided effectively. In the case where the polishing pad substrate is formed of a synthetic resin material having an elasticity, or upon machining grooves having a relatively large radius of curvature, the present arrangement is effective to avoid undesirable interferences with the side surfaces of the grooves by the width-direction edge faces of the blades of the pad groove machining cutting parts during machining or moving upward the cutting parts, thereby enabling the orthogonality of the groove edges to be maintained. In consideration of the strength and durability of the cutting tools, ease of machining, and so forth, the side clearance angles (εs) are preferably set to no more than 5�, and more preferably set in a range of 0�≦εs≦3�, and even more preferably set in the range of 0.1�≦εs≦10.
A fifteenth thirteenth mode of the invention provides a method of manufacturing a grooved polishing pad according to any one of the seventh through fourteenth modes, wherein the cutting of the plurality of grooves is performed by using the multi-edged tool wherein the pad groove machining cutting parts are fabricated from an ultrahard alloy or a high-speed steel.
In this type of method for manufacturing a grooved polishing pad according to the present form of embodiment, the use of an ultrahard alloy with superior hardness, wear-resistance, and toughness makes it possible to provide a pad groove machining cutting part that has superior machining precision. Moreover, because fabricating the blade edge part so as to have a large wedge angle enables increased strength in the blade edge part, the present form of embodiment makes it possible to avoid or reduce the occurrence of small chips, etc., in the blade, even in pad groove machining cutting parts made from sintered materials such as ultrahard alloys. In view of wear-resistant of the multi-edged tool, preferably employed is a multi-edged tool having a plurality of cutting parts made of an ultrahard alloy. In view of a finish of the grooves, preferably employed is a multi-edged tool with the cutting parts made of a high-speed steel.
As is clear from the description above, in the method for manufacturing a grooved polishing pad according to the present invention, the use of a multi-edged tool wherein the blade edge spacing is an integer multiple (2 or more) of the desired groove spacing enables a large number of grooves to be fabricated with high precision with the desired groove spacing being narrow. Furthermore, in machining of grooves, the present invention can prevent effectively the concentrated occurrence of heating and static electricity between the large number of grooves produced, thereby enabling an improvement in machining precision.
BRIEF DESCRIPTION OF THE DRAWINGS The foregoing and/or other objects features and advantages of the invention will become more apparent from the following description of preferred embodiments with reference to the accompanying drawings, in which like numerals are used to represent like elements and wherein:
FIG. 4A is a plane view of a platen of the grooving machine of FIG. 1, and FIG. 4B is a cross sectional view of the platen of FIG. 4A taken along line B-B of FIG. 4A;
FIG. 5A is a plane view of a suction plate of the grooving machine of FIG. 1, FIG. 5B is an axial cross sectional view of the suction plate, FIG. 5C is a fragmentally enlarged view of the suction plate, FIG. 5D is an enlarged view of a X portion of FIG. 5C, and FIG. 5E is an enlarged cross sectional view taken along line E-E of FIG. 5D;
FIGS. 18A, 18B and 18C show enlarged front elevational view of one example of a tool tip;
FIG. 24A is a side view of one example of a cutting device usable in the grooving machine of FIG. 1, FIG. 24B is a front elevational view of the cutting device, and FIG. 24C is a cross sectional view of the cutting device, taken along line C-C of FIG. 24B;
FIG. 26A is a plane view of one example of a drill attached to a drill unit of FIG. 11, and FIG. 26B is an exploded view of a major cutting part of the drill of FIG. 26A;
FIG. 38 is a graph showing a distribution of an abutting pressure of the polishing pad on a surface of the wafer of the static model of FIG. 37;
FIG. 39 is a graph showing a relationship between a peak pressure applied on the surface of the wafer and a rate of variation or error of a groove width;
FIGS. 40A, 40B and 40C show respective steps of a method of producing the polishing pad according to the present invention;
FIG. 41A, is a front elevational view of an ion blowing device used in the grooving machine of FIG. 1 for neutralizing charged components of the grooving machine, and FIGS. 41B and 41C are a side and a bottom elevational view of the ion blowing device, respectively;
FIG. 42 shows one step of the method of producing the polishing pad according to the present invention;
FIG. 43 shows another step of the method of producing the polishing pad according to the present invention;
FIG. 44 shows yet another step of the method of producing the polishing pad according to the present invention;
FIG. 45 shows still another step of the method of producing the polishing pad according to the present invention;
FIG. 46 shows the further step of the method of producing the polishing pad according to the present invention;
FIG. 47 is an enlarged fragmentary view showing a pad groove machining cutting tool of construction according to the invention and a polishing pad substrate;
FIG. 48A is a side elevational view of the cutting tool shown in FIG. 47, FIG. 48B is a front elevational view thereof, and FIG. 48C is a perspective view in a diagonally backward direction;
FIG. 49 is an enlarged cross sectional view of a blade edge portion of the cutting tool of FIG. 47;
FIG. 50 is a front elevational view of a grooving machine by which executed the method of producing the polishing pad of the invention;
FIG. 51 is a side elevational view of the grooving machine of FIG. 50;
FIG. 52A, is a front elevational view of a tool holder equipped with the cutting tools according to the invention, and FIGS. 52B and 52C are a side and a bottom elevational view of the tool holder, respectively;
FIG. 53 is a part plane view of a grooved polishing pad formed according to the method of the present invention;
FIG. 54 is a fragmental enlarged cross sectional view of the grooved pad of FIG. 53; and
FIGS. 55A and 55B are explanatory views for obtaining an amount of interference of the pad groove machining cutting tool of the invention, where FIG. 55A shows specific set values in the cutting tool and FIG. 55B shows the amount of interference with the side wall faces of the groove with the cutting tool when forming a groove with a radius dimension r.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Referring first to FIGS. 1A-1C, there is shown a schematic construction of a grooving machine according to one preferred embodiment of the present invention. The grooving machine is equipped with a turning tool for cutting grooves, which is constructed according to one preferred embodiment of the invention. The grooving machine is used for producing a polishing pad according to one preferred embodiment of the invention in accordance with a method according to one preferred embodiment of the invention.
FIG. 4A shows a plane view of the circular platen 1, while the FIG. 4B shows a cross sectional view of the circular platen 1 taken along line B-B of FIG. 4A. A material for producing the circular platen 1 may be preferably selected from light metals including aluminum alloy, titanium and the like, thereby lowing a moment of inertia of the circular platen 1, thus permitting a prompt startup or stop of the rotation of the circular platen. In particular, the material of the circular platen 1 is desired to be less likely to cause the secular change of the circular platen 1, like strain, to exhibit a heat resistance, and to have sufficient stiffness and strength. While the communication holes 1 a is formed through the central portion of the circular platen 1 for introducing the suction force applied from the suction blower 25 into the upper surface of the circular platen 1 through, the circular platen 1 is also formed with a plurality of leading grooves 1 c, 1 d for leading the suction force into the outer circumferential portion of the circular platen 1. The circular platen 1 is further provided with a plurality of generally concentric grooves 1 e, through which the plurality of leading grooves 1 c, 1 d extending in the radial directions are held in communication with each other. A plurality of circumferential walls If defined between adjacent ones of the annular grooves 1 e serve as supports on which the suction plate 16 is placed.
Referring next to FIGS. 5A, 5B, 5C, there are shown a plane view, an axial cross sectional view, and a fragmentally enlarged view of the suction plate 16. In addition, FIG. 5D shows an enlarged view of an X part of FIG. 5C, and FIG. 5E shows a cross sectional view taken along line E-E of FIG. 5D. As shown in FIG. 5E, the suction plate 16 functions to support the foamed urethane pad 15 to be placed thereon. The suction plate 16 is provided with the multiplicity of tiny air holes 16 a evenly dispersed over the entire surface of the suction plate 16, so that the foamed urethane pad 15 is fixed onto the surface of the suction plate 16 by the suction force evenly applied to the back surface thereof through the air holes 16 a. Like the circular platen 1, the suction plate 16 is made of a material preferably selected from light metals including hard aluminum alloy, titanium, and the like, and ceramic materials.
It should be appreciated that the operation of the grooving machine may be controllable by utilizing a sequential control device 110, instead of the NC device 102 as described above. The use of the sequential control device 110 instead of the numerical control device 102 enables to simplify the entire control system and reduce the cost of the device, although accuracy of control in positioning, feeding, and cutting are somewhat limited in comparison with that in the numerical control device 102. Therefore, one of the numerical control device 102 and the sequential control device 110 may be optionally selected depending upon the use or processability of the foamed urethane pad 15.
Referring next to FIGS. 15A, 15B, there is shown the ion-blowing device 114 adapted to generate and blow positive ions formed by corona discharge. The ion-blowing device 114 includes a compressed air generator (not shown) and a blower nozzle 76, so that the generated positive ions are discharged through the blower nozzle 76 together with the compressed air. Alternatively, the positive ions are discharged through holes 71(a), 72(a) which will be described later. This ion-blowing device 114 is disposed in a portion of the grooving machine such that a protruded open-end portion of the blower nozzle 76 is located in the vicinity of the attached cutting tool, e.g., the fixed tool 69 or the rotative tool 57 (the multi-edged tool 74 is attached in FIGS. 15A-15C by way of example). When the foamed urethane pad 15 is subjected to the grooving process, cut fragments or chips of the foamed urethane pad 15 are likely to be electrically charged due to friction between the cutting tools and the urethane pad 15, and stick to the surface of the urethane pad 15 and the cutting tools, resulting in difficulty in removing the charged chips from the surfaces of the cutting tool and the urethane pad. To cope with this problem, the ion blowing device 114 is operated to blow the positive ions on the chips stuck to the cutting tool and the foamed urethane pad 15, while the grooving process is executed for the foamed urethane pad 15, whereby the chips are effectively neutralized and removed from the cutting tool and the urethane pad 15. When the multi-edged tool 74 of the fixed tool is used for forming simultaneously a plurality of grooves on the foamed urethane pad 15, in which a plurality of cutting edges are juxtaposed to each other, it is required to evenly blow the positive ions on the respective cutting edges so that the positive ions forcedly come into collision with the charged chips. To meet this requirement, the protruded open-end portion of the nozzle 76 may be suitably arranged.
FIGS. 15A-15C show a front, a side and a bottom elevational view of the ion-blowing device 114 that is fixed to a tool holder 71. The tool holder 71 has a rectangular block shape and detachably fixed to the side face of the tool rest 18 (19) by means of suitable fastening means such as a bolt. The tool holder 71 has the above mentioned through hole 71 a formed therethrough in the vertical direction as seen in FIG. 15A through which positive ions are discharged. To the bottom face of the tool holder 71, a rectangular block shaped tool cartridge is fixed such that the tool cartridge 72 is supported by tapered bush 73 so as to be positioned in the vertical direction as seen in FIG. 15A. The tool cartridge 72 has the above-indicated plurality of straight holes 72 a extending therethrough in the vertical direction as seen in FIG. 15A. These straight holes 72 a are held in communication with the through hole 71 a of the tool holder 71, so that the lower end of the through holes 71 a is exposed to the atmosphere through the straight holes 72 a. As shown in FIG. 15A, the multi edged tool 74 is fixed to the tool holder 71 by way of example. The multi edged tool 74 may be a tool detachably installable on the tool holder 71 with high accuracy. For instance, the multi-edged tool 74 is fixed to the tool cartridge 72. The cartridge 72 is positioned relative to the tool holder 71 by means of tapered bushes 73, 73. The cartridge 72 is guided by the side walls of the tool holder 71, and is firmly fitted to the tool holder 71 by means of a pressing plate 75 that is bolted to the tool holder 71. The positive ions can be discharged from the side of the attached tool through the nozzle 76. In the case where the multi edged tool 74 is attached to the tool holder 71 as described above with the compressed air, the ion blowing device 114 may be arranged to blow the positive ion through the through hole 71 a formed through the tool holder 71 and the straight holes 72 a formed through the cartridge 72 instead of or in addition to the nozzle 76. In the ion-blowing device 114, the compressed air generator may be disposed within the nozzle 76, or the straight holes 72 a, for example. Alternatively, the compressed air generator may be constituted by utilizing an external compressed air source that is held in fluid communication with the nozzle 76 or the like via an air conduit. It should be appreciated that the compressed air generator is interpreted to mean the overall structure thereof including the air conduit connecting between the external compressed air source and the nozzle 76 or the like.
The single edged tool 58 has a cutting part 58 a that is arranged as follows so that the single edged tool 58 is suitable for cutting a working piece made of a resin material, e.g., a foamed urethane pad. Namely, the cutting part 58 a of the single edged tool 58 has a tooth width: W1 within a range of 0.005-11.0 mm, a side clearance angle: θ1 within a range of 0-3 degrees, as shown in FIG. 16A. Further, the cutting tooth of the single edged tool 58 has a wedge angle: θ2 within a range of 15-35 degrees, a rake angle: θ3 within a range of 10-20, and a front clearance angle θ4 within a range of 45-65 degrees, as shown in FIG. 16B. These angles of respective parts of the cutting part 58 a of the single edged part 58 a are determined taking into account a problem of interface between the cutting part 58 a and walls of the foamed grooves and a required strength of the cutting part 58 a. Preferably, the single edged part 58 a is made of a rigid material, such as hard metal, high speed steel, carbon steel, ceramics, cermet, and diamonds.
Referring next to FIGS. 24A-24C, there are respectively shown a side elevational view, a front elevational view and a cross sectional view taken along line C-C of FIG. 24B of the cutting device 77 which is adapted to be mounted on the tool rest 18 (19) disposed on the saddle 8A (8B) of the cutting machine constructed according to the present embodiment. The cutting device 77 is operable to cut primary peripheral portion of the foamed urethane pad 15 to shape the external form of the foamed urethane pad 15 desirably. More specifically described, the cutting device 77 includes: a base 78; a fourth guide rails 63A, 63B disposed on the base 78 so as to extend parallel to each other in the Z-axis direction; a tool rest 64 disposed on the base 78 via the pair of fourth guide rails 63A. 63B so as to be movable in the Z-axis direction; a cutting tool holder 66 mounted on the tool rest 64; and a power source 62 disposed on the base 78 so as to generate a drive power by which the tool rest 64 is moved in the Z-axis direction. A cutting tool 61 is fixed to the cutting tool holder 66 such that a base portion of the cutting tool 61 is fitted into a cutting tool base 83 formed in the cutting tool holder 66, while being supported by the a pair of tool supports 65 with its protruding end portion supported by a stopper pin 80. An output member of the power source 62 is connected to a support member 67 disposed on the tool rest 64 via a connecting metal member 68, thus transmitting output power of the power source 62 to the tool rest 64. Thus, the cutting tool 61 is driven in the Z-axis direction. It should be understood that the power source 62 may comprises a piston-cylinder mechanism of pneumatics type or hydraulic type, or a solenoid-type actuator. It should be further understood that the cutting tool 61 may otherwise be constituted by a suitable turning tool for assuring further improved cutting ability of the cutting device 77.
Referring next to FIGS. 27A, 27B, there is shown a polishing pad fabricated according to one preferred embodiment of the invention by way of example. The polishing pad is formed by cutting a multiplicity of generally concentric grooves into the surface of the foamed urethane pad 15 having a thickness: T1 within a range of 1.0 mm-2.0 mm. The generally concentric grooves have a width: W1 within a range of 0.005-11.0 mm, a depth: D1 within a range of 0.2-2.0 mm, and a pitch: L2 within a range of 0.2-2.0 mm. For producing the polishing pad of the present invention, initially, the single-edged cutting tool 58 or the multi-edged cutting tool 74 is fixed to the tool rest 18 (19), while a base for desired polishing pad, e.g., the foamed urethane pad 15 is placed on the suction plate 16 of the circular platen 1. Preferably, the foamed urethane pad 15 is shaped to have a circular-disk shape identical in size with the circular platen 1 in advance, by cutting. The cutting of the foamed urethane pad 15 may be executed by means of cutting device 77 fixed to the tool rest 18 (19). In the case where the foamed urethane pad 15 has a diameter smaller than the suction plate 16, an annular covering member may be placed on the outer peripheral portion of the suction plate 16 located radially outward of the foamed urethane pad 16, so that the air holes 16 a open in the outer peripheral portion of the suction plate 16 is effectively closed by the annular covering member. The suction plate-16 may be modified so that only a portion of the suction plate 16 serving for suctioning the urethane pad 15 is provided with the air holes 16 a. Alternatively, the communication grooves 16 b formed in the suction plate 16 may be partially closed so that distribution of the suction force on the suction plate 16 is divided into local sections.
While the grid patterned grooves are formed on the surface of the base for the polishing pad by using a milling cutter 81 in the grooving machine of the illustrated embodiment, the grid patterned grooves may be formed more efficiently by utilizing a single edged tool or a multi edged tool that is fixed to the tool rest 18 (19) that is reciprocally movable in the Y-axis direction at a relatively high speed, e.g., 50-180 m per minute. More specifically described, the grooving machine is modified such that the saddles 8A, 8B are reciprocally moved in the Y-axis direction by means of linear motors disposed so as to extend along the guide rails 9A, 9B, in stead of the ball-screw shafts 10, 14. The use of the linear motors enables the above-indicated high-speed reciprocal motion of the saddles 8A, 8B and the_tool rest 18, 19 in the Y-axis direction, in comparison with the ball-screw shafts 10, 14 which permits the reciprocal movement of the saddles 8A, 8B at 10 m per minute at most. Thus, the modified grooving machine, which has the linear motors as a drive power source of the saddles 8A, 8B in the Y-axis direction, is capable of cutting the grid patterned grooves into the base for the polishing pad with significantly improved efficiency. In addition, the modified grooving machine utilizes the single or multi edged tool rather than the milling cutter 81. This arrangement is effective to prevent undesirable melt of the base of the polishing pad due to heat caused by frictional contact of the milling cutter 81 with the base for the polishing pad, depending upon kinds of materials of the base for the polishing pad.
It should be appreciated that as shown in FIG. 18A, the pad groove machining cutting parts 58 a in the present form of embodiment are arrayed linearly with a blade spacing that is twice the spacing of the grooves to be formed in the polishing pad 15. Here a polishing pad 15 wherein grooves have been fabricated at the desired spacing in the polishing pad 15 can be provided through repetitively performing cutting fabrication of grooves while moving the multi-edged tool 74 in the direction of the array of the plurality of blade edge parts 58 a. More specifically, in the multi-edged tool 74, as shown in FIG. 18A, a plurality of cutting parts 58 a are arrayed linearly with essentially equal spacing. The spacing p in this plurality of cutting parts 58 a is twice the desired groove spacing d of the grooves to be formed in the polishing pad 15. Furthermore, as shown in FIG. 40A, after grooves have been fabricated with the spacing p using the multi-edged tool 74 in a first process, then, as shown in FIG. 40B, the multi-edged tool 74 is moved by an amount equal to the desired groove spacing d in the direction of the array of the cutting parts 58 a (in one direction or the other along the radial direction of the polishing pad 15) as a second process, following which, as a third process, grooves are again formed with a spacing of p as shown in FIG. 40C. At this point, the spacing p of the cutting parts 58 a is twice the groove spacing d desired for the grooves, and thus the grooves formed in the third process with the spacing p will be positioned essentially centered between the grooves formed with the spacing of p in the first process. This causes grooves to be formed with the spacing d, which is � of the spacing p of the cutting parts 58 a, enabling the fabrication of grooves with a specific groove spacing d on the front surface and/or back surface of the polishing pad 15. Note that in the present form of embodiment the desired grooves are formed on the front surface and/or the back surface of the polishing pad 15 through moving the multi-edged tool 74 towards the outer radial direction from the inner position in the radial direction of the polishing pad 15.
In the method for manufacturing described above, the use of a multi-edged tool that has a blade edge spacing p that is an integer multiple of the groove spacing d enables the fabrication of grooves with the specific groove spacing d. Consequently, when fabricating, in a polishing pad 15, grooves that have a small groove spacing d in order to achieve a required high precision polishing, it is possible to provide a large blade edge spacing in the multi-edged tool 74, making it possible to manufacture the cutting parts 58 a of the multi-edged tool 74, which has tended to be difficult because of the spacing p being narrow, with relative ease and with high precision. Moreover, providing a relatively large spacing p for the cutting parts 58 a of the multi-edged tool 74 enables the positions between adjacent cutting parts 58 a in the multi-edged tool 74 to be wide, enabling the heat due to friction between the cutting parts 58 a and the polishing pad 15 to be dispersed in this wide area, thereby making it possible to reduce or eliminate effectively the pad deformation and reduction in polishing performance caused by the effects of concentrated frictional heating. Furthermore, because the spacing p of the cutting parts 58 a of the multi-edged tool 74 can be made relatively large, the amount of airflow between the cutting parts 58 a can be increased, which can produce beneficial cooling of the cutting parts 58 a through the flow of air, making it possible to effectively reduce or avoid reductions in polishing precision due to the generation of heat in the polishing pad 15. In particular, in the present form of embodiment, an �ion blow� is performed wherein air that includes negative ions (in the present embodiment the air is ionized to include positive ions and negative ions) is blown onto the cutting parts 58 a to not only achieve more effective cooling of the cutting parts 58 a, but to also make it possible to control the occurrence of static electricity at the cutting location, enabling the effective prevention of reductions in cutting precision due to, for example, the adherence of shavings within the grooves.
Note that this type of �ion blow,� as shown in FIG. 15, may be performed by blowing from the side of the multi-edged tool 74. However, preferably the ionic air should be blown from behind the blade edges of the multi-edged tool 74, in the direction of cutting, as shown, for example, in FIGS. 41A, B, and C. That is, blowing the air stream from behind can prevent shavings from getting between the cutting parts 58 a and melting and adhering due to frictional heating. In particular, as is shown by the double dotted lines in FIGS. 41B and C, it is preferable to position the opening of a vacuum tube negative pressure suction opening 300 in front of the blade edges of the multi-edged tool, in the direction of cutting, so that the shavings will be vacuumed away and removed from the cutting work area as quickly as possible by this negative pressure suction aperture 300.
Furthermore, it is not absolutely necessary that the fluid used for cooling the cutting parts 58 a and the polishing pad 15 be an ionic air, but rather the fluid may be normal air that is blown by, for example, a blower. It is also not imperative to have, for example, a device that blows the cooling fluid, but rather the cutting parts 58 a and the position of cutting in the polishing pad 15 may be cooled through the air flow that occurs naturally due to the turning.
It should be appreciated that while in the present form of embodiment the use of a multi-edged tool 74 having a spacing p for the cutting parts 58 a that is twice the groove spacing d of the grooves was shown as an example, as shown in FIG. 18A, any spacing of the cutting parts 58 a is acceptable insofar as it is an integer multiple of the groove spacing d, and, as shown in FIG. 18B, the spacing p of the cutting parts 58 a may be three times the groove spacing d of the grooves, or, as shown in 18C, the spacing of the cutting parts 58 a may be four times the groove spacing d of the grooves. Of course, the spacing p of the cutting parts 58 a may be an integer multiple of five times or more the groove spacing d.
More specifically, the plurality of grooves may be formed more effectively in accordance with the following machining processes.
Referring first to FIG. 42, the grooves are formed onto the surface of the polishing pad substrate 15, by means of the plurality of cutting parts 58 a of the multi-edged tool 74, with the spacing p corresponding to the spacing p of the cutting parts 58 a, by the number corresponding to that of the cutting parts 58 a of the multi-edged tool 74.
Subsequently, as shown in FIG. 43, the multi-edged tool 74 is relocated with respect to the polishing pad substrate 15 in the widthwise direction thereof (i.e., in a direction along which the plurality of cutting parts 58 a are arranged), by a distance corresponding to a sum (B+p) of a distance B between the outermost end cutting parts 58 a of the multi-edged tool 74 and a spacing p between the adjacent cutting parts 58 a. At this location, the groove forming process previously executed is repeated, thereby forming the plurality of grooves onto the substrate by the same number and with the same pitch.
Referring next to FIG. 44, these subsequent processes of grooving and dislocation are repeated by the suitable number of times, until a desired area of the surface of the polishing pad substrate is formed with the plurality of grooves.
Then, as shown in FIG. 45, the multi-edged tool 74 is moved back to the initial position as shown in FIG. 42. Subsequently, the multi-edged tool 74 is shifted outward in the widthwise direction by a desired pitch of the grooves formed onto the polishing pad substrate 15 (e.g., an interval between adjacent grooves) At this location, the groove forming process previously executed is repeated, thereby forming the plurality of grooves onto the substrate by the number of cutting parts 58 a and with the spacing p corresponding to the spacing p of the cutting parts 58 a. Subsequently, as shown in FIG. 46, the multi-edged tool 74 is relocated with respect to the polishing pad substrate 15 in the widthwise direction thereof (i.e., in a direction along which the plurality of cutting parts 58 a are arranged), by the distance corresponding to the aforementioned sum (B+p), and at this location, the groove forming process previously executed is repeated, thereby forming the plurality of grooves onto the substrate by the same number and with the same pitch. These subsequent processes of grooving and dislocation are repeated by the suitable number of times, until a desired area of the surface of the polishing pad substrate is formed with the plurality of grooves.
As needed, a series of the processes discussed above is repeated until a multiplicity of grooves are formed at a desired pitch, thereby completing the processes of machining the desired multiplicity of grooves onto the polishing pad substrate 15.
The aforementioned groove forming method is able to avoid machining grooves onto the area adjacent to the grooves just formed in the last machining process. Accordingly, if the area where the grooves have just been formed undergoes experiences a temperature increase, the next grooving process to the same area can be performed after the area undergoes cooling for a given period of time, while assuring that the groove machining process can be continued with no break. This results in an improved process efficiency overall, while avoiding heating of the polishing pad substrate itself.
As disclosed in FIGS. 42-46, the desired grooves can be produced by shifting the multi-edged tool 74 by the distance corresponding to the sum of B+p, while repeating the groove machining, and then going back to the initial point, as described above. Alternatively, for example, the processes shown in FIGS. 42 and 43 are performed, and then the process shown in FIG. 45 are performed by positioning the multi-edged tool 74 at the illustrated position, before executing the process shown in FIG. 44. The specific sequence of the location of the multi-edged tool 74 can be suitably desired without limited to those in the illustrated embodiment.
For adopting the aforementioned groove processing method, a radius dimension of an area where the grooves to be formed should be twice or more the distance B between the most end cutting parts 58 a of the multi-edged tool 74, more preferably, an integer multiple of the distance B.
There will be described another embodiment of the present invention. First, FIG. 47 shows the leading edge part in a cutting tool 310, as a cutting tool for machining a pad groove, and a pad substrate 310, as a pad substrate for polishing, in another embodiment according to the present invention. The cutting tool 310 forms grooves 313 by cutting the pad substrate 312 through advancing from the right side towards the left side in FIG. 47. Note that in the explanation below the forward and backwards directions for the cutting direction are, as a rule, referring to the left and right directions in FIG. 47, where in FIG. 47 the left side is the forward direction. Furthermore, in each the various appended drawings, the shapes and dimensions are exaggerated to facilitate understanding of the shapes of the cutting tool 310 and the pad substrate 312, which will be explained below.
The pad substrate 312 has a thin disk shape that has a uniform thickness dimension overall, and may be formed from an appropriate material of any of a variety of types, such as a hard foam, a solid synthetic resin, or a hard rubber material.
On the other hand, in the cutting tool 310, as can be seen in FIG. 48 as well, a rake face 314, which is a front face, forms a specific cutting angle of α towards the back from the perpendicular direction relative to the pad substrate 312. Conversely, a curve 318 that extends facing in direction of the width of the blade of the cutting tool 310 is formed on the front clearance face 316, which is the back surface, where the region on the blade edge side of the curve 318 on the front clearance face 316 is defined as the blade edge-side front clearance face 320, and the region on the base-side of the curve 318 is defined as the base-side front clearance face 322.
Moreover, the wedge angle θ1 at the blade edge-side front clearance face 320 is different from the wedge angle θ2 at the base-side front clearance face 322, where the wedge angle θ2 at the base-side front clearance face 322 is smaller than the wedge angle θ1 at the blade edge-side front clearance face 320. The result is that the front clearance angle εe2 at the base-side front clearance face 322 will be larger than the front clearance angle εe1 at the blade edge-side front clearance face 320, so that the base-side front clearance face 322 will be the one that will have the larger rise relative to the pad substrate 312.
Here the wedge angle θ1 at the blade edge-side front clearance face 320 is preferably set in a range of 25�≦θ1≦87�, preferably 25�≦θ1≦70�, more preferably, 30�≦θ1≦70�. In the present form of embodiment is set to 30�. In accordance therewith, the wedge angle θ2 of the base-side front clearance face 322 uses a value that is smaller than that of θ1, and in the present form of embodiment, is set to 20�.
The front clearance angle εe1 at the blade edge-side front clearance face 320 is preferably set in a range of 3�≦εe1≦60�, preferably 10�≦εe1≦60�, more preferably 20�≦εe1≦50�. These front clearance angles εe1 and εe2 are set by the cutting angle α and the wedge angle θ1 and θ2, and in the present form of embodiment the cutting angle α is set to 10�, so the clearance angle εe1 at the blade edge-side front clearance face 320 is set to 50�, and the front clearance angle εe2 at the base-side front clearance face 322 is set to 60�.
Note that the curve 318 is preferably formed at a position with a height between 0.05 mm and 1.0 mm from the blade edge of the cutting tool 310 in the direction of depth of the groove 313 in the pad substrate 312, and, more preferably, is set to be smaller than the dimension of the depth of the groove 313 that is formed in the pad substrate 312. Were the position of the curve 318 set to a position that is higher than the groove 313, the small blade edge-side front clearance face 320 of the front clearance angle would have an interference with the edge of the groove 313, which would tend to cause tooling interferences. In the present form of embodiment, in particular, the curve 318 is formed at a position with a height of 0.3 mm from the blade edge of the cutting tool 310, in consideration of the depth dimension of the groove 313, formed in the pad substrate 312, being set to 1.0 mm.
In order to reduce the tooling interferences, preferably the distance of separation, in the direction of the cutting, from the blade edge part in the front clearance face 316, or in other words, the front-back width of the cutting tool 310 in the direction of cutting, is small, and, specifically, preferably the position at a height of 2.0 mm from the blade edge in the front clearance face 316, in the direction of the depth of the groove 313, has a distance of separation of no more than 2.5 mm from the blade edge in the cutting direction, and, more preferably, this distance of separation is no more than 2.0 mm, and, even more preferably, this distance of separation is no more than 1.5 mm. In the present form of embodiment, given the cutting angle and the wedge angle as described above, the position at a height of 2.0 mm from the blade edge in the front clearance face 316 has a distance of separation of 1.23 mm from the blade edge (in the horizontal direction), and at a height of 1.0 mm, has a distance of separation of 0.66 mm from the blade edge.
Furthermore, a surface treatment is performed on the blade edge-side front clearance face 320, where the surface roughness thereof is less than that of the base-side front clearance face 322. In particular, in the present form of embodiment, a surface treatment is performed through lapping using a diamond abrasive grain with a size of no more than 10 μm so that the surface roughness will have an Ry value of no more than 3 μm, and preferably Ry≦1 μm. Note that a variety of treatment methods can be used for the surface treatment, where, for example, polishing, buff finishing, ultrasonic treatments, etc., can be used instead of lapping, or plating can be performed on the blade edge-side front clearance face 320 to reduce the surface roughness, etc.
There will be the respective side clearance angles εs on both edges 321 and 321 in the direction of the width of the blade in the blade edge part of the cutting tool 310. These side clearance angles εs preferably are set to between 0� and 5�, more preferably 0� and 3�, and more preferably 0.1� and 1�, and in the present form of embodiment, εs is set to approximately 2�.
Moreover, the blade width of the cutting tool 310 is set according to the groove width dimension to be formed in order to produce the desired polishing performance in the polishing pad, where typically, for a polishing pad for CMP (chemical mechanical polishing), this dimension should be set to between 0.1 mm and 1.0 mm, and in the present form of embodiment is set to about 0.5 mm.
As is shown in FIG. 49, the blade edge strength is increased through the formation of a curve that has a specific nose radius R at the blade edge part of the cutting tool 310. Note that, from the perspective of machining precision, it is desirable to form a sharp shape for the blade edge part of the cutting tool 310 that will cut the pad substrate 312, which is typically formed from a synthetic resin material. In consideration of both the durability and the machining precision in the cutting tool 310, it is desirable for this nose radius R to be as small as possible. Consequently, it is desirable for this nose radius R to be, specifically, no more that 0.05 mm, and, actually, the nose radius R may be 0, with the edge part of the cutting tool 310 forming a sharp angle. In particular, in the present form of embodiment, the nose radius R of the edge part of the cutting tool 310 is set to 0.01 mm. That is, in accordance with the present invention, it is possible to provide a cutting tool that has a blade edge that has this type of small R or that forms a sharp angle.
It should be appreciated that the cutting tool 310 can be made from a variety of different materials, for example, diamond, sintered diamond, sintered cBN, ceramic, ceramic metal, an ultrahard alloy, high-speed steel, or the like. In particular, the use of an ultra hard alloy or high speed-steel is preferred. In the present form of embodiment, the cutting tool 310 is made from an ultra hard alloy.
The cutting tool 310 with this type of structure can be used in a cutting device such as, for example, is explained below, to fabricate, with superior machining precision and machining efficiency, multiple parallel grooves in a pad substrate for polishing.
Specifically, the machining device 330, as shown in FIG. 50 and FIG. 51, is well suited for use. Note that the machining device 330 that is described below is described in JP-A-2002-11630, and so only a summary description will be provided herein.
The machining device 330 comprises a circular table 334 equipped with a flat support surface 332 for fixedly supporting a pad substrate 312; a pair of blade holders 336A and 336B that can move relative to the circular table 334 in the three orthogonal directions of the X axis, the Y axis, and the Z axis; cutting units 338 equipped in these blade holders 336A and 336B; driving means for driving the blade holders 336A and 336B and the circular table 334; and a control device 340 as control means for controlling the operations thereof. Note that the direction of the X axis is the left-right direction shown in FIG. 51, the direction of the Y axis is the left-right direction shown in FIG. 50, and the direction of the Z axis is the up-down direction shown in FIG. 50. Moreover, the blade holders 336A and 336B in FIG. 50 are shown in a state wherein the cutting units 338 have been removed.
The circular table 334 is not only rotationally driven around a central axis that extends in the vertical direction (the direction of the Z axis) by C axis control, but is also equipped with holding means, such as an electromagnetic break, not shown, that holds the circular table 334 releasably so as to prevent rotation. Moreover, the support surface 332 of the circular table 334 not only is able to hold the pad substrate 312 using a vacuum suction, but is also formed with an indentation, such as a clearance groove or a clearance hole, for when a cutting tool is used, at that location.
Moreover, a pair of first guides 344A and 344B are disposed so as to extend in the X-axial direction, with the circular table 334 interposed there between, on a bed 342 in the machining device 330, and a gantry-shaped column 346, which can move in the X-axial direction, is guided by these first guides 344A and 344B.
Furthermore, the gantry-shaped column 346 is equipped with a pair of saddles 350A and 350B that can be moved in the Y-axial direction by a pair of second guides 348A and 348B, which extend in the Y-axial direction, equipped on the gantry-shaped column 346.
Furthermore, each of these saddles 350A and 350B is equipped with a blade holder 336A and 336B. These blade holders 336A and 336B can be moved in the Z-axial direction by the respective motors 352A and 352B. Moreover, attachment holes 354A and 354B, for equipping tools, are provided as appropriate in the respective blade holders 336A and 336B, enabling the attachment of tools.
As described above, the blade holders 336A and 336B can move in three orthogonal directions relative to the circular table 334 through movement in the X direction due to the first guides 344A and 344B of the gantry-shaped column 346, the second guides 348A and 348B of the saddles 350A and 350B, and free movement in the Z axial direction.
Moreover, the operational control and positional control of the circular table 334 and blade holders 336A and 336B are performed by the control device 340. Note that the operational control of the various members by this control device 340 is performed, for example, through a well-known means such as the back control of a servo motor, or the like, as driving means for driving each of the operating members, using a detector signal from position sensors for detecting the positions of each member.
Moreover, cutting tools and turning tools are attached as appropriate to the blade holders 336A and 336B that are controlled positionally in the three orthogonal directions as described above. Note that while the present form of embodiment shows a form wherein a cutting tool is provided, a bore or a drill may be attached instead.
FIG. 51 shows one form wherein a cutting tool is mounted on the machining device 330. A cutting unit 338, as the cutting tool, is attached to an attachment hole 354B in the blade holder 336B shown in FIG. 51. This cutting unit 338 is equipped with a tool holder 358 to which a tool tip 356 is attached as a multi-edged tool.
The tool tip 356, as shown in FIG. 52, is used appropriately as a multi-edged tool tip wherein cutting tools 310, structured according to the present invention, are provided, at the area around the tip, with an appropriate pitch P (which is the spacing between adjacent blades in the direction of the blade width, and, in the present form of embodiment, is approximately 3.0 mm). This type of tool tip 356 is positioned with high accuracy through positioning pins 360 and 360, for example, being firmly secured to the tool holder 358, held by a retaining plate 362, and secured to the tool holder 358 by a bolt 364. Note that in the present form of embodiment, the tool tip 356 may be formed with a plurality of blades for a single tool, but it is also possible to form a multi-edged tool in the same manner by securing, through layering in the blade-width direction with spacers interposed therebetween, as appropriate, a plurality of cutting tools, each having a single independent blade. Moreover, in the present form of embodiment, tunnel-shaped holes 363 are formed, extending in the vertical direction, within the tool tip 356, where the bottom edge parts of these holes 363 are split into a plurality of blow openings 365, after which there are openings formed in a plurality of positions behind the tool tip 356. Moreover, ions are blown from the through holes 363 through the blow openings 365 when the tool tip 356 is installed in the tool holder 358. That is, when cutting using the tool tip 356, ions are blown through blowing a stream of ionic air towards the blade edge of the tool tip 356, reducing insofar as is possible, the static electricity that is generated by the lapping. Furthermore, while not shown in the figure, in front of the tool tip 356 there is a suction opening from a vacuum tube, where shavings are vacuumed away through the suction opening, to be eliminated as quickly as possible from the cutting work area.
The use of a cutting unit 338 equipped with a tool holder 358, structured in this way, to perform a machining process by having the cutting tool 310 protrude into the pad substrate 312, which is held in place against the support surface 332 of the circular table 334 by suction, and to perform a turning process by repetitively cutting so as to trace the same cutting positions can effectively cut and form a groove 313 that has the desired shape through the performance of multiple repetitions in a discontinuous form through reciprocating motion, or the like, if the groove is a groove that is linear or that has ends, such as a spiral groove, or in a continuous form if the groove is a closed loop.
In particular, in the present form of embodiment, this type of groove 313 can be formed with improved machining precision and machining efficiency through the use of a cutting tool 310 having a particular structure.
That is, the cutting tool 310 according to the present form of embodiment not only maintains a large front clearance angle εe2 for the base-side front clearance face 322 at the blade part, but also side clearance angles are formed so that, when forming a groove 313 with a small diameter dimension positioned in the center part of a pad substrate 312, tool interference can be avoided effectively, and disruption of the edge shape of the groove 313 can be avoided or reduced.
Moreover, given the present form of embodiment, the wedge angle θ1 at the blade edge-side front clearance face 320 is greater than the wedge angle θ2 at the base-side front clearance face 322, so that in the cutting tool 310, the blade edge part can be fabricated with an appropriate thickness. Consequently, the strength of the blade edge part can be increased, enabling an increase in the useful life of the cutting tool 310. Moreover, increasing the strength of the blade edge part makes it possible to form the front edge part of the cutting tool 310 with a sharper shape, making it possible to perform the machining with greater precision.
In addition, in the present form of embodiment the adherence of shavings to the machining surface when performing the cutting process can be reduced through reducing the surface roughness of the blade edge-side front clearance face 320. Doing so reduces the roughness of the machining surface, which is caused by the presence of the shavings, thereby enabling greater machining precision. Furthermore, because the amount of heat that is produced in the blade edge part of the cutting tool 310 that is thought to be caused by frictional heating is suppressed, not only is it possible to increase the speed of machining, but it is also possible to suppress changes in quality due to heating within the groove 313. In addition, suppressing the generation of heat can further improve the useful life of the cutting tool 310. In particular, in investigations by the present inventors, improvements in the machining precision of the bottom parts of grooves were found to be the result of not just reductions in the heating alone. That is, when machining pad substrates made from synthetic resin materials there is a tendency for there to be plastic deformation, where the pad substrate expands in the direction behind the blade when the cutting tool is pressed downwards, which is thought to increase the likelihood of contact with the front clearance face of the blade edge of the cutting tool. Because the size of this contact surface is relatively large when compared to the case when machining metal, there is also the tendency to have the aforementioned problem with generating heat, while, in addition, because the electrical conductivity of the pad substrate is low, there is a tendency for the shavings to be electrostatically charged, and thus a tendency for the effects of the static electricity to cause the shavings to adhere to the inside surfaces of the grooves being machined in the pad substrate. Because the cutting by the cutting tool is performed by repetitively cutting a large number of cycles, with a slight depth each, in order to form a groove of the desired depth, shavings that adhere to the inner walls of the groove get caught between the pad substrate and the cutting tool during the repeated cutting cycles, which is thought to cause roughness in the cut surfaces. In the present form of embodiment, the cutting tool front clearance face has low friction at the blade edge part, which is most likely to come into contact with the polishing pad, and the occurrence of static electricity is suppressed, thereby enabling even greater groove machining precision. Note that in order to prevent more effectively the adhesion of shavings onto the pad substrate due to static electricity, preferably devices should be used such as, for example, blowing ions onto the cutting positions, or vacuuming shavings away from the cutting positions.
Next FIG. 53 and FIG. 54 show a polishing pad 370 as one example of a polishing pad manufactured according to a manufacturing process as described above. FIG. 53 is a partial plan view of the polishing pad 370, and FIG. 54 is an expanded view of the key part of the polishing pad 370. The grooves 313 in the polishing pad 370 are a large number of ring-shaped grooves that extend in concentric circular shapes around the central axis of the polishing pad 370, formed with, for example, a groove width of B=0.5 mm, a grove depth of D=1.0 mm and a groove pitch of P=1.5 mm. This type of polishing pad 370 is fabricated through mounting a pad substrate 312 onto a circular table 334 of the aforementioned machining device 330, and rotating the circular table 334 and inserting, a plurality of times, the cutting tool 310, manufactured as described above, with continuous tracks. Note that as described above, the tool tip 356 has a gap between cutting tools 310 of P=3.0 mm, and thus when performing a turning process for the grooves 313, the cutting unit 338, or in other words, the tool tip 356 is moved by 1.5 mm each time in the radial direction of the pad substrate 312 to form the ring-shaped grooves with a groove pitch P=1.5 mm.
Given this, the diameter D of the ring-shaped groove 313 at the position that is nearest the center of the polishing pad 370 in the present form of embodiment is 20 mm. Because of this, a wide area of the surface of the polishing pad 370 can be used effectively as the polishing surface. Moreover, because the ring-shaped grooves 313 are provided even in the center part of the pad, where the polishing fluid is less likely to accumulate, these grooves can be anticipated to hold the polishing fluid effectively. Note that, as described above, the use of the cutting tool 310 with a structure according to the present invention reduces interferences with the inner surfaces of the side walls of the ring-shaped grooves 313 by the cutting tool 310 and enables turning fabrication and machining with ease for even ring-shaped grooves with a diameter of less than 60 mm, while appropriately adjusting the front clearance angle and the wedge angle to enable excellent turning fabrication of ring-shaped grooves at D<20 mm and even D≦10 mm.
Furthermore, by using the cutting tool 310, with the particular structure as described above, to fabricate the ring-shaped groove 313 that is located closest to the center, the groove can be fabricated with superior machining precision, even for a ring-shaped groove of such a small radial dimension. This makes it possible to obtain better polishing fluid flow operations for the polishing pad 370.
Note that the structure of the cutting tool 310 in the present form of embodiment is preferred for use as the cutting part 58 a of the multi-edged tool 74 used in the method for manufacturing a grooved polishing pad shown in the first form of embodiment described above. The use of a cutting tool 310 structured in this way, as the cutting part 58 a not only has the effect, for example, of enabling high precision fabrication of grooves with the narrow groove spacing shown in the first form of embodiment, but is also able to suppress the production of heat and static electricity due to friction, shown in the second form of embodiment, and able to exhibit the benefit of other effects such as being able to achieve high precision cutting fabrication of grooves.
EXAMPLES Next, a comparative investigation will be performed regarding the amount of tool interference when fabricating ring-shaped grooves using cutting fabrication for a cutting tool with a conventional structure vs. a cutting tool with the structure according to the present invention. Note that for the sake of brevity, the comparative investigation will focus on the distance of separation from the blade edge part in the direction of cutting at the front clearance face, or in other words, will focus on the front-back width of the cutting tool in the direction of cutting, rather than considering the blade width.
First, FIG. 55A shows the various set values for the aforementioned front clearance angle, etc., in the cutting tool structured according to the present invention. That which is the subject is the cutting tool 310 in the form as described above, where the blade edge front clearance face 320 has a front clearance angle εe1=50�, and the base-side front clearance face 322 has a front clearance angle of εe2=60�. Note that the height dimension of the curve 318 in the direction of depth is 0.3 mm.
Note that the ring-shaped grooves 313 fabricated through cutting using this cutting tool 310 have a height dimension of D=1.0 mm, and a curvature radius dimension, when the pad substrate is viewed from the top, of r=10 mm.
Here the distance of separation W of the front clearance face 316 (which, in the present form of embodiment, is the base-side front clearance face 322) from the blade edge at the top edge face of the groove 313, or in other words, the front-back width, in the direction of cutting of the cutting tool 310, at the top edge face of the groove 313 is the sum of the front-back width w1 from the blade edge to the curve 318 and the front-back width w2 from the curve 318 to the position on the top edge face of the groove 313 of the base-side front clearance face 322.
[Equation ]
w1=0.3/tan 50� w2=(1−0.3)/tan 60� W=w1+w2=0.656 [Equation 1]
Consequently, the front-back width, at the top edge surface of the groove 313, of the cutting tool 310 is set to W=0.656. Here, as shown in FIG. 55B, the amount of interference x1 with the side wall faces of the groove 313 with the cutting tool 310 when forming a groove 313 with the radius dimension r, as described above, is calculated using the following equation:
x ⁢ ⁢ 1 = w 2 + 10 2 - 10 = 0.021 [ Equation ⁢ ⁢ 2 ] Accordingly, using the cutting tool 310 according to the present invention causes the amount of interference x1 with the inner wall surface, when forming the ring-shaped groove 313, as described above, through cutting, to be 0.021 mm. On the other hand, when the same calculation is performed for a cutting tool according to the conventional structure, which is formed with a constant wedge angle of θ=20�, without having the curve 318, the amount of interference x2=0.017. As is clear from these calculations, the structure according to the present invention has many effects, as described above, through maintaining the cutting angle θ1 of the blade edge part even while keeping the effect on the tool interference low.
Next, Table 1 shows the results of comparisons of groove machining precision, durability, etc., after having performed repetitive groove machining on identical synthetic resin chemical mechanical polishing pad substrates for three test samples (all made from the same materials) those comprising a cutting tool of the comparative example that has a blade edge shape according to a conventional structure, formed having a constant wedge angle, without having the curve. A cutting tool of an example A that has a two-stage structure, with the curve, for the front clearance face, according to the present invention where no surface treatment has been performed on the front clearance face on the blade edge side of the curve; and a cutting tool of example B according to the present invention where, on the front clearance face in example A, a surface treatment has been performed on the region from the curve to the blade edge to reduce the surface roughness of this region.
Note that in the tests of the groove machining, a high speed multi-edged tool with a blade pitch of 3.0 mm with 11 blades, as described above, and shown in FIG. 52, was used to form through cutting ring-shaped concentric grooves with a grove width of 0.5 mm, a groove pitch of 1.5 mm, and a groove depth of 1.0 mm, in a foam urethane pad with a diameter of 750 mm, using the machining conditions of a turning pad speed of rotation of between 200 and 400 rpm. Note that in the cutting tool of the comparative example, the wedge angle θ=20�, and in examples A and B, θ1=30� and θ2=20�.
side walls and
Good for only
pads processed
2-stage wedge
angle (no
lapping finish
The present invention was confirmed to be able to use an ultrahard alloy, which has been difficult to use conventionally.
While the use of an ultrahard alloy slightly increases the defect rate, when compared to the use of high-speed steel in similar experiments, in the structure according to example B it was confirmed that the defect rate, up to the end of the useful life, can be held to 2%.
Incidentally, when an ultrahard alloy is used, the defect rate, up to the end of useful life, was 5% in the structure according to the example A, described above, and manufacturing was extremely difficult using the structure according to the conventional example, described above.
Firstly, when the machining precision of the groove is observed, no major difference can be seen in terms of the machining precision of the side walls of the groove, but when it comes to the machining precision of the bottom surface of the groove, better machining precision could be obtained using the cutting tool structured according to the present invention than in the conventional example. This confirms the ability to increase the machining precision of the groove through the effect of providing a 2-stage cutting angle in the front clearance phase, and, preferably, the effects of providing a surface treatment in the region of the blade edge part.
Moreover, observing the durability of the cutting tool, durability was clearly better for example A than for the comparative example, and better still for the example B. Moreover, when it comes to defects in the blade edge part, in the comparative example not only did the occurrence of defects occur in an early stage, but the quantity of the defects was large, where an improvement was seen in example B, and even in example A the onset of the defects was delayed, and the quantity of defects was low. That is, it was possible to verify the effect of both the fabrication of the large wedge angle in the blade edge part of the cutting tool, and of the performance of the surface treatment on the blade edge side region of the front clearance face as both increasing the durability, and in the cutting tool structured according to the present invention (in particular, in the example B), these two effects appeared synergistically, so as to be able to produce superior durability.
The specific values in, for example, the forms of embodiment described above, such as the values for the wedge angles θ1 and θ2 and for the front clearance angles εe1 and εe2, are no more than examples of suitable set values, and, of course, there are no limitations whatsoever to the set values such as described above. Note that when the blade edge part wedge angle θ1 is made larger, the front-back width in the cutting direction of the cutting tool is increased, and the amount of tool interference is increased, and thus when θ1 is made larger it is desirable to reduce the height position of the curve accordingly. Specifically, if, for example, θ1≦60�, then the height of the curve from the blade edge should be no more than 0.8 mm.
Furthermore, in the method for manufacturing a polishing pad with grooves as described above, a groove machining method was presented as an illustration wherein a single tool tip 56 was used as a multi-edged tool; however, the groove machining may be performed through providing a plurality of these tool tips 56 lined up in parallel. This type of situation enables the groove machining to be performed more efficiently.
Furthermore, in the forms of embodiment described above, an example was given of a method for manufacturing a polishing pad with a plurality of ring-shaped grooves, extending in concentric circular shapes, through the use of a multi-edged tool structured according to the present invention, presented as an example of a manufacturing method for a grooved polishing pad; however, this method for performing machining using a multi-edged tool is not limited in any way. For example, instead of machining grooves through a cutting process or a turning process wherein the polishing pad substrate is rotated, as described above, and the cutting tool is inserted into the surface thereof, the cutting tool structured according to the present invention may instead be applied to groove machining wherein a cutting process is performed through moving the cutting tool linearly or along an appropriate curve on the surface of an abrasive pad substrate while holding the abrasive pad substrate in a stationary position, or to groove machining wherein the cutting effect is produced through moving both the pad substrate and the cutting tool simultaneously. Given these groove machining processes, grooved polishing pads with multiple grid-like grooves can be manufactured with excellent machining precision and machining efficiency.
The application of the grooved polishing pad substrate manufactured according to the method for manufacturing according to the present invention is also not a limitation. For example, although the present invention is applied to polishing of silicon wafers and polishing of semiconductor wafers, and in particular is used in CMP (chemical-mechanical polishing), the present invention may also be applied to resin pads for other types of polishing instead. Furthermore, the groove machining of the polishing pads can be performed on either surface of the pad, the front or the back. Also, the polishing pad to which the present invention is applied is not limited in its material or its application, and, for example, as a polishing pad for CMP, a pad substrate made from a conventionally known synthetic resin material, a pad substrate with a multilayer structure, a pad substrate made from a hardened resin, a pad substrate made from a composite material wherein water-soluble particles are dispersed into a water insoluble matrix of cross-linked polymers, etc., can be used.
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(Partial Translation).Referenced byCiting PatentFiling datePublication dateApplicantTitleUS8496512 *Oct 10, 2012Jul 30, 2013Iv Technologies Co., Ltd.Polishing pad, polishing method and method of forming polishing pad* Cited by examinerClassifications U.S. Classification29/558, 409/293, 82/1.11, 409/304, 409/345International ClassificationB23P15/00Cooperative ClassificationB24B37/26, B24D18/00European ClassificationB24B37/26, B24D18/00Legal EventsDateCodeEventDescriptionOct 1, 2012FPAYFee paymentYear of fee payment: 4Mar 21, 2006ASAssignmentOwner name: TOHO ENGINEERING KABUSHIKI KAISHA, JAPANFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:SUZUKI, TATSUTOSHI;REEL/FRAME:017695/0367Effective date: 20051228RotateOriginal ImageGoogle Home - Sitemap - USPTO Bulk Downloads - Privacy Policy - Terms of Service - About Google Patents - Send FeedbackData provided by IFI CLAIMS Patent Services©2012 Google