CN110871407A

CN110871407A - Polishing pad dresser and method for chemical mechanical planarization

Info

Publication number: CN110871407A
Application number: CN201811025287.8A
Authority: CN
Inventors: 宋健民
Original assignee: Individual
Current assignee: Individual
Priority date: 2018-09-04
Filing date: 2018-09-04
Publication date: 2020-03-10

Abstract

The invention relates to a polishing pad dresser and a chemical mechanical planarization method. All CMP pad dressers use diamonds as cutting edges, however the height difference of the diamond cutting edges from the most protruding apex is more than 60 microns, so that the working particle count of the cut pad is less than 500. Although some trimmers are made by coating carved ceramic (such as SiC) with a diamond film, the diamond film is easy to peel off and scratch the finished product. The invention takes non-diamond superhard material PcBN as a grinding material, directly carves customized independent small pieces, and then assembles the CMP polishing pad trimmer. PcBN has much higher corrosion resistance than diamond and is sintered at ultra high pressure. The invention can independently customize the size, shape and height of the cutting edge, so the number of the cutting edges and the cutting depth of the polishing pad can be controlled, the service life of CMP consumables can be prolonged, the cost (CoO) is reduced, the CMP efficiency can be accelerated, the productivity is increased, and the invention is a tool for producing the current semiconductor products.

Description

Polishing pad dresser and method for chemical mechanical planarization

Technical Field

The present invention relates to a polishing pad dresser and a chemical mechanical planarization method, and more particularly, to a PcBN polishing pad dresser, a chemical mechanical planarization method using the PcBN polishing pad dresser, and a process for manufacturing an integrated circuit.

Background

Chemical Mechanical Planarization (CMP) is a process that must be used many times to manufacture Integrated Circuits (ICs), and as the line width of the circuits according to Moore's Law is smaller, the CMP requirements are more stringent and the times are more frequent. Taking the largest wafer foundry in the world, taiwan integrated circuit (TSMC) as an example, the 7nm process requires CMP of an IC wafer with a diameter of 300mm (12 inches) for tens of times, the polishing rate of each CMP is fast and flat, and there is no scratch on the IC wafer, so that a chip with a small nail size can be cut out from the complete IC wafer, which contains tens of layers of copper wires with a total length of over ten kilometers, and is connected with billions of Transistors (Transistors) on the surface of a silicon substrate, so that the chip can be operated by 0 or 1 to become a hardware calculator such as CPU/GPU/NPU for mobile phones, computers, robots, internet, etc. CMP is used not only for manufacturing the logic operation body of an IC, but also for manufacturing the memory of an IC (such as DRAM, Flash memory (Flash), etc.), even a silicon wafer itself, and even a memory (such as a hard disk), and in short, CMP is a necessary process for manufacturing a highly planarized plane of a large area (such as a sapphire wafer).

Specifically, CMP is a polishing method in which a rotating IC wafer is pressed against a rotating polishing pad (usually PU) on which a Slurry (Slurry) containing nano-abrasive particles (e.g., SiO) is coated₂And Al₂O₃) And chemical reactants (e.g., acids, bases, hydrogen peroxide); the polishing pad usually contains micro-pores for adjusting the compression ratio and storing the slurry. Since the contact area and distribution of the wafer and pad must be controlled during polishing, the pad must be dressed with a diamond disk to produce a moderately sized and uniformly distributed nap (asperties) on the pad surface. If the contact area between the wafer and the polishing pad is too large, the polishing rate is low and the CMP efficiency is insufficient; on the contrary, the local polishing is too much, which causes the problems of wafer unevenness (WIWNU), Dishing (Erosion), and scratching. In addition, the diamond disk is responsible for cutting off the hard debris (Glaze) on the polishing pad, so the distribution of the diamond vertex height on the diamond disk controls the depth distribution of diamond penetrating into the polishing pad, affects various performances of CMP, and is a key consumable for controlling the CMP performance.

Diamond disks are typically made of stainless steel, with abrasive particles (Grind grit) of diamond grit, such as 150 microns, fixed and aligned in a metallic material (e.g., nickel or alloys thereof) by plating, brazing or sintering. Because the diamond abrasive particles are different in size and have large peak height difference, and the diamond abrasive particles are irregular in shape and often contain fracture surfaces, the sharpness of the cutting polishing pad is difficult to control, so that the sizes and the distribution of fluff on the polishing pad are uneven, and the CMP efficiency and the yield are influenced.

On the other hand, CMP is an interface polishing method, and the pressure distribution of the interface is determined by the size and distribution of the nap of the polishing pad, and the difference in the heights of the apexes of the diamond particles of the diamond disk is so large that practically less than 500 diamond particles can penetrate into the polishing pad to form the nap. Furthermore, the problem of up to ten diamond particles penetrating too deeply (e.g., greater than 60 microns) results in a polishing pad that is more expensive than a diamond disk being consumed twice. Therefore, the peak height difference of the diamond abrasive particles is too large, so that the service lives of the diamond disk and the polishing pad are shortened, the IC wafer is not flat, even the problem of scratching is caused, the yield of chips is reduced, in addition, the downtime for replacing the diamond disk and the polishing pad is more frequent, and the shipment volume of a single machine is reduced.

Although the use of smaller diamond grit reduces the peak height difference, it causes a reduction in the protrusion of the diamond grit, which causes friction between the metal holding the diamond grit and the slurry, which contaminates the IC wafer and also reduces the chip yield. The use of diamond particles of regular crystal form can reduce the peak height difference, but there is a problem that the diamond particles are not sharp enough, which causes the hard debris to remain on the surface of the polishing pad, thereby increasing the number of micro-scratches of the IC wafer. Therefore, the diamond disk with fixed diamond grains has difficulties that it is difficult to overcome, including the difference in the height of the apex and the sharpness, so that the cost (CoO) and the efficiency (Throughput) of CMP cannot be increased.

In view of the above, the present inventors have used a whole sintered piece of Polycrystalline diamond (PCD) as a polishing structure of a diamond disk, and matched the diamond disk manufactured by electrical discharge machining, which has a uniform vertex height and a uniform pyramid shape, to become a diamond disk selected by the american application Materials Co (Applied Materials Co) for the development of electro-chemical cmp (electrokinetic cmp) of copper oxide wire (ecmp).

However, the PCD contains cobalt as a sintering agent, and is evaporated into pores after electrical discharge machining, so that the PCD is easily adhered to abrasive dust and is not suitable for a CMP process.

Disclosure of Invention

CMP needs the surface of a polishing pad to be capillary and rich in fluff, the fine fluff can avoid wafer scratching, the fine fluff can accelerate wafer polishing, more diamond tops need to be penetrated into the fine fluff, namely the highest peaks of diamonds need to be uniform, when the number of working particles of the diamonds is large, the penetration is not deep, so that the angles of the diamond tops are sharp, and the inherent tops of the diamonds have the problems of non-uniformity and non-sharp tops.

It is a primary object of the present invention to address the above-mentioned problems and disadvantages of known pad dressers using diamond material, and it is another object of the present invention to extend the rate of chemical reaction of tips soaking in CMP slurry, thereby providing a pad dresser that is superior to diamond disks.

The invention provides a polishing pad dresser for a CMP process, which comprises a plurality of PcBN grinding sheets, wherein a plurality of grinding tips are formed on each PcBN grinding sheet, and the grinding tips have a protruding height which is enough to penetrate into a polishing pad to remove abrasive dust.

In one embodiment, the average penetration depth of the abrasive tip is greater than the average size of the pores of the polishing pad.

In one embodiment, the average size of the pores is between 30 microns and 60 microns.

The invention also provides a polishing pad dresser, which comprises a plurality of PcBN grinding sheets, wherein a plurality of grinding tips are formed on each PcBN grinding sheet, and the number of the grinding tips with the height difference of the highest distance among all the grinding tips within the range of 60 micrometers is between 300 and 5000.

In one embodiment, the PcBN abrasive sheet is secured to a ceramic substrate.

In one embodiment, the PcBN abrasive sheet is bonded to a base by a thickness compensating plastomer that adjusts the protrusion height of the abrasive tip on the PcBN abrasive sheet, respectively.

In one embodiment, the thickness-compensating plastomer is an organic material.

In one embodiment, the PcBN abrasive sheet has a cBN volume percentage of at least 90%.

In one embodiment, the number of the polishing tips having the height difference of the polishing tips at the highest distance in the range of 40 μm is between 300 and 1000.

In one embodiment, the number of the abrasive tips having a height difference of 40 μm from the abrasive tip having the highest distance among the abrasive tips on a single PcBN abrasive sheet is between 50 and 500.

In one embodiment, the polishing tip has a peak with an included angle between 40 degrees and 120 degrees.

In one embodiment, the angle of the peak is between 60 degrees and 100 degrees.

In one embodiment, wherein the peak is in the shape of a cone or a ridge.

In one embodiment, the cone is a polygonal cone with between 3 and 6 sides.

In one embodiment, the PcBN abrasive sheet is square or circular in shape.

In one embodiment, the abrasive tip comprises a blunt top surface having a width between 2 microns and 20 microns.

In one embodiment, the number of PcBN abrasive sheets is between 4 and 50.

In one embodiment, the abrasive tips on each PcBN abrasive sheet are arranged to form an array.

The invention further provides a chemical mechanical planarization method, which comprises the following steps:

providing a polishing pad;

arranging a workpiece on the surface of the polishing pad, and enabling the workpiece and the polishing pad to be mutually ground; and

the dresser is arranged on the surface of the polishing pad to remove the abraded debris of the workpiece.

In one embodiment, the workpiece is a semiconductor element comprising one or more layers of a copper film, a tungsten film, an oxide film, a barrier layer, or a combination thereof.

Therefore, the PcBN of the present invention is used as a polishing pad of a dresser to replace the conventional diamond disk, and the conventional dresser usually only considers the mechanical properties, but neglects that the IC wafer and the pad dresser involve chemical erosion and mechanical polishing at the same time when performing CMP, while the PcBN has not only high chemical inertness, is suitable for resisting the chemical erosion in CMP, but also has excellent mechanical properties compared to most materials, has better processability than diamond materials, and is suitable for processing the polishing tips into specific shapes and arrangements, so as to meet the requirement of high customization.

Drawings

FIG. 1 is a schematic view of one embodiment of a pad dresser of the present invention.

FIG. 2 is an enlarged schematic view of the first PcBN abrasive sheet of FIG. 1.

FIG. 3 is an enlarged schematic view of the second PcBN abrasive sheet of FIG. 1.

Fig. 4 is a schematic sectional view taken along the line a-a in fig. 1.

FIG. 5 is a schematic view of another embodiment of a pad dresser of the present invention.

FIG. 6 is a schematic view of another embodiment of a pad dresser of the present invention.

FIG. 7 is a flowchart illustrating a method of chemical mechanical planarization according to an embodiment of the present invention.

[ description of the drawings ]

10. 10a, 10 b: polishing pad dresser

20: PcBN abrasive sheet

20 a: first PcBN abrasive sheet

20 b: second PcBN abrasive sheet

21 a: a first grinding tip

21 b: second grinding tip

22 a: a first top surface

22 b: second top surface

23 b: depressions

24: edge

25: corner

30: ceramic matrix

40: thickness compensated plastomer

50: base seat

51: depressions

60: hard layer

70: flow path

71: step (ii) of

72: step (ii) of

73: step (ii) of

W: width of

Detailed Description

The detailed description and technical contents of the present invention will now be described with reference to the drawings as follows:

the present invention provides a polishing pad dresser for a CMP process, comprising a plurality of PcBN abrasive sheets, each of which is formed with a plurality of abrasive tips having a protrusion height sufficient to penetrate into a polishing pad to remove abrasive dust, the PcBN (Polycrystalline cubic silicon nitride) being obtained by Ultra high pressure sintering (Ultra high pressure sintered) of cBN micropowder. In one embodiment, the average penetration depth of the abrasive tips is greater than the average size of the pores of the polishing pad, the average size of the pores may be between 30 microns and 60 microns, and the working number of the abrasive tips may be greater than 500.

In another aspect, the present invention provides a Pad conditioner made of PcBN, the Pad conditioner comprising a plurality of PcBN abrasive sheets, each of which has a plurality of abrasive tips formed thereon, wherein the number of the abrasive tips having a height difference of 60 μm from the highest abrasive tip among all the abrasive tips is in a range of 300 to 5000. In one embodiment, the PcBN abrasive sheets are fixed on a ceramic substrate and the PcBN abrasive sheets are bonded to a base by a thickness compensating plastomer that adjusts the protrusion height of the abrasive tips on the PcBN abrasive sheets, respectively. In one embodiment, the thickness-compensating plastomer is an organic material. In one embodiment, the PcBN abrasive sheet has a cBN volume percentage of at least 90%.

In one embodiment, the number of the polishing tips with the height difference of 40 microns from the highest polishing tip among all the polishing tips is between 300 and 1000, and in another embodiment, the number of the polishing tips with the height difference of 40 microns from the highest polishing tip among the polishing tips on a single PcBN polishing sheet is between 50 and 500.

In one embodiment, the polishing tip has a peak with an included angle between 40 degrees and 120 degrees, and in another embodiment, the included angle of the peak is between 60 degrees and 100 degrees. In one embodiment, the peak is in the shape of a cone or ridge, the cone is a polygonal cone with between 3 and 6 sides, and in one embodiment, the grinding tip comprises a blunt top surface with a width of between 2 and 20 microns.

In one embodiment, the PcBN abrasive sheets have a square or circular shape, the number of the PcBN abrasive sheets is between 4 and 50, and the abrasive tips on each PcBN abrasive sheet are arranged to form an array.

For purposes of clarity, the following description should be read with reference to the drawings, in which many features are not necessarily drawn to scale, and in fact, the number or size of the various features may be increased or decreased to make the description more clear.

Referring to fig. 1, 2 and 3, there are shown a schematic diagram of an embodiment of a pad conditioner of the present invention, an enlarged schematic diagram of the first PcBN abrasive sheet of fig. 1, and an enlarged schematic diagram of the second PcBN abrasive sheet of fig. 1, respectively. The polishing pad dresser 10 of the present embodiment includes a plurality of PcBN polishing pieces 20, each PcBN polishing piece 20 having a plurality of polishing tips formed thereon, wherein the number of height differences of tip height points of all the polishing tips in the range of 60 μm is 300 to 5000. In the present embodiment, the PcBN polishing sheet 20 has a square shape, the sides 24 of the PcBN polishing sheet 20 face outward, the PcBN polishing sheet 20 includes a first PcBN polishing sheet 20a and a second PcBN polishing sheet 20b, the first PcBN polishing sheet 20a and the second PcBN polishing sheet 20b are alternately arranged, the first PcBN polishing sheet 20a includes a plurality of first polishing tips 21a, the first polishing tips 21a have a polygonal cone shape, the number of sides of the polygonal cone shape is 4, the first polishing tips 21a include first top surfaces 22a, the first top surfaces 22a are flat surfaces to be polished, the second PcBN polishing sheet 20b includes a plurality of second polishing tips 21b, the second polishing tips 21b have a rectangular line shape, the second polishing tips 21b include a plurality of second top surfaces 22b and a plurality of recesses 23b alternately arranged with the second top surfaces 22b, and in other embodiments, the second polishing tips 21b may include only the second top surfaces 22b, without the recess 23 b. The width W of the top surface is between 2 microns and 20 microns.

Referring to fig. 4, which is a schematic sectional view taken along the direction a-a of fig. 1, in the present embodiment, the PcBN polishing pad 20 is fixed on a ceramic substrate 30, the ceramic substrate 30 is, for example, cobalt-cemented tungsten carbide, the ceramic substrate 30 is further fixed in a recess 51 of a base 50 by a thickness-compensating plastic body 40, the base 50 may be made of metal, for example, stainless steel, the thickness-compensating plastic body 40 may be an organic material, for example, thermosetting resin or thermoplastic resin, which has elasticity before hardening, and before hardening, the thickness of the organic material may be adjusted by a flat top plate, for example, a hard layer 60 shown in fig. 4, so as to adjust the protruding height of the polishing tip 21a on the PcBN polishing pad 20a relative to the horizontal plane, thereby further improving the flatness. In one embodiment, the thickness-compensating plastic body 40 may be an epoxy resin having a thickness that supports the PcBN abrasive sheet 20 such that the tips are accessible to the planar top plate, such that the height of the tips on all of the PcBN abrasive sheets 20 on the polishing pad conditioner 10 can be controlled.

With continued reference to fig. 5 and 6, a schematic diagram of another embodiment and a schematic diagram of yet another embodiment of a pad conditioner of the present invention are shown, respectively. In the embodiment of FIG. 4, the edges 24 of the first PcBN abrasive sheet 20a are directed outward, while the corners 25 of the second PcBN abrasive sheet 20b are directed outward; whereas in the embodiment of FIG. 5, the PcBN abrasive sheet 20 includes only the first PcBN abrasive sheet 20a, the side 24 of the first PcBN abrasive sheet 20a is oriented outwardly. The above is merely an illustration of the configuration of the PcBN polishing sheets 20, and in other embodiments, the number, orientation, and distribution of the tips of the PcBN polishing sheets 20 may be adjusted as desired. Furthermore, in other embodiments of the pad dresser of the present invention, the PcBN polishing pad 20 may be configured with other types of polishing units disposed on the base 50, such as polishing units made of conventional diamond grit.

The present invention further provides a method for chemical mechanical planarization, referring to fig. 7, which is a schematic flow chart of steps of an embodiment of the method for chemical mechanical planarization of the present invention, and the flow chart 70 of the embodiment includes the following steps. Step 71: providing a polishing pad; step 72: arranging a workpiece on the surface of the polishing pad, and enabling the workpiece and the polishing pad to be mutually rotated and ground; and a step 73: the polishing pad dresser is arranged on the surface of the polishing pad to remove the chips of the workpiece after being ground. In one embodiment, the workpiece is a semiconductor device comprising one or more layers of a copper film, a tungsten film, an oxide film, a barrier layer (e.g., TaN), or combinations thereof.

In the classification of abrasives, alumina (Al) is generally included₂O₃) Cubic boron nitride (cBN), silicon carbide (SiC) and Diamond (Diamond), also commonly known as A (Al)₂O₃) B (cBN), C (SiC), D (diamond). Wherein, AB is temperature resistant and corrosion resistant, and CD is not temperature resistant and corrosion resistant; low AC hardness (<2500Kg/mm²) Being a traditional abrasive, the BD hardness was high, Knoop hardness of the diamond (Knoop hardness)>7000Kg/mm²Hardness of cBN is about 5000Kg/mm²BD is commonly known as superabrasive and is synthesized at ultra high pressure. In the case of CMP, both the corrosion resistance and the Mechanical property of the abrasive should be considered, but the prior art only considers the Mechanical property (Mechanical) and neglects the Chemical property (Chemical), so that the CMP cannot be optimized by using diamond as the abrasive. cBN and diamond are both superhard materials, but have far less oxidation and corrosion resistance than diamond, and although diamond is hard, the CMP refining has high corrosivity and oxidizability. The lifetime of a diamond disk used in oxide film planarization is about three times that of a diamond disk used in tungsten film planarization because of the use in the planarization of tungsten films or other metal layersThe abrasive slurry needs to contain a strongly oxidizing or corrosive substance, such as hydrogen peroxide or a strong acid, which can accelerate the wear rate of the diamond tip; conversely, PcBN is chemically inert, e.g., diamond oxidizes at about 600 ℃ in air, whereas PcBN oxidizes at 1400 ℃. Also in the above-mentioned CMP process, the process temperature applied for the planarization of the tungsten film is high (about 80 ℃), and diamond oxidation is generated at the corner of the edge and at a higher temperature. Further, the oxide film planarization and the pad dressing are performed simultaneously (in-situ), while the tungsten planarization and the pad dressing are performed alternately (ex-situ), so that the diamond disk rarely reacts with the slurry during the tungsten planarization process, even though the diamond cutting edge is rapidly oxidized.

According to the above, when CMP is performed, the IC wafer and the pad dresser are simultaneously chemically etched and mechanically ground, the diamond on the conventional diamond disk has high hardness which is resistant to mechanical grinding but far inferior to PcBN in corrosion resistance, but the latter is slightly lower than the hardness of diamond abrasive particles to provide better processing convenience for diamond grinding wheels and wire saws, so that the PcBN can be diamond-engraved with special patterns, such as special-shaped cones and intervals between the cones, and the problem that the peak height and the diamond sharpness are difficult to be compatible is solved.

Conventionally, there is a pad dresser formed by coating a diamond film on a carved ceramic material (e.g., silicon carbide or tungsten carbide), but the diamond film is coated by vapor chemical deposition (CVD) in a vacuum environment, not only is there no sintered bond between diamond particles, but also the coated interface is easily peeled off, so that it is necessary to coat a blunt-tipped pyramid with a thin (e.g., 10 μm) diamond film. The rough plastic pulling of such diamond-disk dressed pads is excessive, increasing the contact interface, limiting the polishing rate of IC wafers, while the thin diamond film also shortens the life of the diamond disk, both of which reduce the throughput of the CMP stand-alone.

However, the PcBN pad dresser of the invention has no fragile plating film, so that more sharp cones can be used, the service life of the pad dresser is prolonged, more fluff can be generated on a polishing pad during dressing, and the speed of CMP polishing of IC wafers is accelerated.

Taking the example of applying a diamond disk to a tungsten CMP process, the diamond disk penetrates the deepest (about 60 microns) cutting edge of the polishing pad, the lifetime is only tens of kilometers, while the same diamond disk CMP oxide film can support up to two hundred kilometers, and the fact that the diamond edge micro-oxidation is not obvious is indeed observed. This problem can be solved with a PcBN trimmer.

Another non-obvious fact is that the number of peaks penetrating into the polishing pad is inversely proportional to the deepest depth of cut, and the large comparison of diamond disks used in large semiconductor factories shows that the number of peaks of diamond disks used in normal CMP is about 300 to 500, which is about 5% of the number of tens of thousands of diamonds on a general diamond disk, and it is seen that most diamonds do not contact the polishing pad, and even if they contact, because the peaks of diamonds are smooth and obtuse angles, there is no actual penetration, but rather the pad is depressed or plastically deformed. In addition, polishing pads usually contain micro-pores for adjusting compressibility and storing slurry, while the micro-pores inside the polishing pad are closed, but the micro-pores on the surface of the polishing pad have openings, and thus, in the planarization process, since abrasive dust is deposited in the open pores on the surface of the polishing pad, the de-scaling (Deglazing) of CMP requires that the diamond peaks penetrate into the polishing pad to a depth exceeding the average pore size of the polishing pad to effectively remove the abrasive dust.

The problems can be solved by using PcBN, and the PcBN can be processed by using laser or diamond grinding wheels, can carve specific cutting edge shapes and angles and can also form specific tip height difference distribution, so that different dresser specifications can be customized according to the CMP application, CMP can be optimized, the service lives of a dresser and a polishing pad are prolonged, grinding pulp is reduced or diluted, and the CMP cost (CoO) is reduced; when the number of tips that work effectively on the dresser is increased, the fuzz of the polishing pad is increased, and thus the polishing speed of CMP can be increased, resulting in an increase in productivity of a single machine.

In addition, there is a non-obvious advantage in that in metal (e.g., copper or tungsten) processing, the wafer can be simultaneously (in-situ) CMP and pad dressed in the presence of a strong acid and an oxidizing agent, such timely dressing can also increase the rate of polishing the wafer, and the dressing and pad life can be extended without excessively penetrating into the pad, thereby reducing the number of times spent down to replace consumables, and such additive effect can further reduce the CMP cost and increase the yield of IC wafers.

Another feature of making polishing pad dressers with engraved PcBN is that the used PcBN can be reground for reuse. And polishing the worn tip to form the tip, so that the trimmer can be reused, and the manufacturing cost is reduced. At present, no matter the dresser of diamond abrasive particles or diamond coating can not be processed and used again.

The puzzling of a diamond disk is related to the angle of the vertex of the diamond, if the diamond is complete in crystal form, the vertex is mostly obtuse, generally an acute angle is formed by a fracture surface to penetrate into a polishing pad, but the vertex with an irregular shape is easy to form a killer diamond, so that the polishing pad is excessively consumed, the diamond is easy to fracture, and the wafer is scratched. Many diamond dish makers have spent on selecting diamonds, increasing costs. What is more, the diamond point is upward, so that the diamond point is not quickly worn, and the diamond point is not as fast as the diamond point with the upward ridge line, but the included angle of the ridge line of the diamond is an obtuse angle. The included angle between the cube faces is a right angle, but such edges are rare, with the included angle between the octahedral faces being about 109 degrees and the included angle between the cube and the octahedron being about 140 degrees. The PcBN can be carved to customize the angle of the ridge line and prolong the service life of the dresser and the polishing pad.

Example 1

Sintering under ultrahigh pressure (>5GPa) to obtain a plurality of PcBN grinding sheets, wherein the PcBN grinding sheets contain cBN with the volume ratio of 90 percent, and the bonding agent is a ceramic material. After sintering, the material was cut into 10mmx10mm squares by laser machining. Then, 100 (arranged in a 10 × 10 matrix) four-sided pyramids were ground on each PcBN grinding plate by a diamond grinding wheel, with a pitch of 1mm between the pyramids. The apex face angle of each pointed cone is a right angle, the height of the cone top is 150 microns, and the width of the cone bottom is 300 microns. The diamond grinding wheel is made by sintering diamond abrasive particles with a metal, ceramic or resin bond, in this example, a ceramic bond is illustrated.

The array sheet is fixed on the periphery of a base by using stainless steel (SS316) with the diameter of 108mm as the base and pressing eight square matrixes on thermosetting resin or thermoplastic resin by using silica gel covering cloth, and the square matrixes can be outwards arranged on the periphery or outwards arranged at sharp angles or alternately arranged. When hot pressing is carried out, the thickness of the thermosetting adhesive or the thermoplastic can compensate the thickness of the PcBN, so that the top height of the PcBN is consistent.

Example 2

As in the previous example, but PcBN was ground with a diamond wheel to 10 square ridges. The diamond wire saw was used to cut an arc perpendicular to the ridge line so that the ridge line was interrupted and each had a length of about 50 microns.

Example 3

The same as example 1 or example 2, but the number of apexes in the range of 40 μm of the highest apex exceeds half the number of all apexes.

Example 4

To reduce tip height differences and remove surface cracks, the assembled diamond disk can be over-pressed to trim the pad so that its tip is slightly blunter.

Claims

1. A pad dresser for a CMP process, comprising a plurality of PcBN abrasive sheets, each PcBN abrasive sheet having a plurality of abrasive tips formed thereon, the abrasive tips having a protrusion height sufficient to penetrate a polishing pad to remove abrasive debris.

2. The pad conditioner of claim 1 wherein the average penetration depth of the abrasive tips is greater than the average size of the pores of the pad.

3. The pad conditioner of claim 2 wherein said pores have an average size of between 30 microns and 60 microns.

4. A polishing pad dresser comprising a plurality of PcBN abrasive sheets, each of the PcBN abrasive sheets having a plurality of abrasive tips formed thereon, wherein among all the abrasive tips, the number of the abrasive tips having a height difference of 60 μm from the highest one is in a range of 300 to 5000.

5. The pad conditioner of claim 4 wherein the PcBN abrasive sheet is secured to a ceramic substrate.

6. The dresser of claim 4, wherein the PcBN abrasive sheets are bonded to a base by thickness-compensating plastomers respectively adjusting the protrusion heights of the abrasive tips on the PcBN abrasive sheets.

7. The pad conditioner of claim 6 wherein the thickness compensating plastomer is an organic material.

8. The pad conditioner of claim 4, wherein the PcBN abrasive sheet has a cBN percentage of at least 90% by volume.

9. The dresser of claim 4, wherein the number of grinding tips having the height difference from the highest grinding tip in the range of 40 μm is between 300 and 1000.

10. The dresser of claim 4, wherein the number of the abrasive tips having the height difference of the highest abrasive tip among the abrasive tips on a single PcBN abrasive sheet within 40 μm is between 50 and 500.

11. The dresser of claim 4, wherein the abrasive tip has a peak, and the peak is angled between 40 degrees and 120 degrees.

12. The pad conditioner of claim 11 wherein said peak has an included angle of between 60 degrees and 100 degrees.

13. The pad conditioner of claim 12 wherein said peak is in the shape of a cone or a ridge.

14. The pad conditioner of claim 13 wherein said taper is a polygonal taper, said polygonal taper having between 3 and 6 sides.

15. The pad conditioner of claim 4 wherein the PcBN abrasive sheet is square or circular in shape.

16. The pad conditioner of claim 4 wherein said abrasive tip includes a blunt top surface having a width of between 2 microns and 20 microns.

17. The pad conditioner of claim 4 wherein the number of PcBN abrasive sheets is between 4 and 50.

18. The pad conditioner of claim 17 wherein the abrasive tips on each PcBN abrasive sheet are arranged to form an array.

19. A method of chemical mechanical planarization, comprising the steps of:

providing a polishing pad;

arranging a workpiece on the surface of the polishing pad, and grinding the workpiece and the polishing pad mutually; and

using the dresser according to any one of claims 1 to 18, provided on the surface of the polishing pad, debris after the workpiece is abraded is removed.

20. The method of claim 19, wherein the workpiece is a semiconductor device comprising one or more layers of copper film, tungsten film, oxide film, barrier layer, or combinations thereof.