KR100881162B1 - Method for manufacturing a conditioning disc for polishing pad - Google Patents

Abstract

A manufacturing method of the conditioning disk for the polishing pad is provided to fundamentally prevent the particle dropout by the abrasion occurring with the conditioning work of the polishing pad or the chemical etching. A manufacturing method of the conditioning disk for the polishing pad performs follow steps: a feed stock formation step which forms the feed stock in which the ceramic powder and thermoplastic resin binder are uniformly dispersed by pulverizing after mixing the ceramic powder and thermoplastic resin binder(S1); an extrusion step which solidifies after injecting within the cavity of the injection mold while heat-softening the feed Stock and molds the injection molded article(S2); a degreasing step removing the thermoplastic resin binder in the injection molded article(S3); and the sintering step sintering the fat removed injection molded article (S4).

Description

Manufacturing method of conditioning disc for polishing pad {METHOD FOR MANUFACTURING A CONDITIONING DISC FOR POLISHING PAD}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conditioning disk for a polishing pad, and more particularly, to a manufacturing method of a conditioning disk capable of processing a plurality of projections more precisely.

In the late 1980s, IBM in the United States developed a new polishing process called Chemical Mechanical Polishing (CMP), which combines mechanical removal and chemical removal in one process.

Such CMP, together with Plasma Enhanced Chemical Vapor Deposition (PECVD) and Reactive Ion Etching (RIE), is an essential step in the manufacture of chips on submicron scale. Among these CMPs, interlayer dielectric (ILD) CMP and metal CMP should be continuously applied to all surfaces of the device layer. In order to obtain a three-dimensional shape, it is necessary to planarize each layer globally to obtain a three-dimensional shape. It is the main role. This CMP is a polishing process in which mechanical and chemical actions simultaneously interact with each other.

In the CMP process, the wafer is polished by the polishing pad and the slurry, and the polishing table to which the polishing pad is attached performs simple rotational movement, and the head portion is pressed at a constant pressure while simultaneously performing the rotational movement and the swinging movement.

The wafer is mounted on the head portion by surface tension or vacuum, and the surface of the wafer and the polishing pad are brought into contact with the head portion's own load and a pressing force applied thereto. The slurry, which is the processing liquid, flows between the minute gaps between the contact surfaces and / or the pore portion of the polishing pad, and mechanical removal action is performed by the abrasive particles in the slurry and the surface protrusions of the polishing pad. Chemical removal is achieved.

In the CMP process, contact is made from the top of the device protrusion by the pressing force between the polishing pad and the wafer, and the pressure is concentrated in this portion, thereby having a relatively high surface removal rate. As the processing proceeds, the protrusion is gradually reduced and uniformly removed over the entire surface.

According to the conventional mechanical polishing method, the damaged layer can be easily formed, and the damaged layer becomes a defect of the semiconductor chip. In addition, chemical polishing does not produce a deteriorated layer, but a flattened shape, i.e., a shape precision, cannot be obtained, and thus there is a limit in that only a simple smooth surface can be obtained. On the other hand, CMP has an advantage of obtaining high shape precision without forming a processing altered layer.

On the other hand, the polishing pad used for such chemical mechanical polishing reduces the surface roughness in the process of polishing the surface of the object such as a wafer. If the surface roughness of the polishing pad is not restored to its original state, it will adversely affect the removal rate and uniformity in the subsequent polishing process.

Accordingly, a conditioning process for supplying a new slurry as well as recovering the surface roughness of the polishing pad is indispensable. In this conditioning process, a conditioning disk is used and a new slurry on the polishing pad side. Condition the conditioning disc by pressing the conditioning disc at a constant pressure on the surface side of the pad while supplying.

By this conditioning process, the polishing pad can maintain its porosity constant, recover its surface roughness, suppress uneven deformation and maintain flatness, and smoothly deposit slurry in the pores of the polishing pad. Can supply

Conventional conditioning disks are generally diamond disks produced using a metal binder of diamond particles having a size of about 100 ~ 250㎛, such diamond disks can be easily removed by wear or corrosion of the adhesive site by the slurry. There was a downside. The dropped diamond particles adhere to the surface of the polishing pad to cause severe scratches on the surface of the wafer, and also act as a major cause of contamination of metal ions, which causes a short circuit on the wafer surface.

Accordingly, in order to minimize the dropping of the diamond particles, a method of coating a corrosion resistant material such as chromium or palladium on the surface of the metal binder to which the diamond particles are bound is proposed, but nevertheless, the problem of dropping the diamond particles is solved. I couldn't.

Accordingly, in recent years, various studies have been attempted without using a metal binder. Instead of using diamond particles, a method of forming a plurality of protrusions by mechanical processing on the surface of a ceramic material (Domestic Patent Registration No. 10-0387954) Or "prior art 1") or a method of thermal spraying a surface of a ceramic material (Domestic Patent Registration No. 10-0678303, hereinafter referred to as "prior art 2"), and the like.

Prior art 1 makes a ceramic body by sintering a ceramic plate molded into a predetermined shape to make a sintered body, and performing primary roughing, secondary middle grinding, tertiary finishing grinding, and the like on both sides of the sintered body. Then, a method of processing a plurality of projections on one side of the ceramic body through a mechanical processing using a diamond tool.

However, the prior art 1 has a disadvantage in that the processing time is very long and mass production is not easy. In addition, due to the grinding impact due to mechanical processing, there is a disadvantage that the inner crack that can not be verified irregularly, thereby easily the protrusion of the latent inner crack.

Prior art 2 proposes a method of integrally forming a plurality of protrusions on the surface of a ceramic body by a thermal spraying method.

However, in the prior art 2, the height of the projections formed by the thermal spraying is not constant, and irregular pores are formed inside the ceramic body. Accordingly, since the ceramic body does not have a constant adhesive strength over the entire surface of the ceramic body, the ceramic body is partially lowered below the intrinsic strength of the ceramic and has a disadvantage in that a plurality of protrusions are dropped to a macro size.

In addition, the conditioning disk should have a uniform height throughout the plurality of projections provided on its surface. This facilitates uniform conditioning of the polishing pad.

In addition, the height uniformity (deviation) of the projections must be maintained at least within 30㎛, thereby not only can maintain the grinding force of 2.5 ~ 3.5㎛ per minute, which is the current optimal condition, but also precise control of the grinding force, adjustment of the number of protrusions, etc. Can be made easier.

However, the conventional conditioning disk has a disadvantage in that the height uniformity of the projections cannot be precisely maintained due to the different shrinkage rate (10-30%) or twisting of the ceramic body after sintering than before the sintering.

Accordingly, the present invention has been made in view of the above, and an object of the present invention is to provide a conditioning pad for a polishing pad which can fundamentally prevent particle falling off due to wear and chemical corrosion occurring during the conditioning operation of the polishing pad. There is this.

In addition, an object of the present invention is to provide a conditioning disk for a polishing pad which can maintain the height uniformity of the projections more precisely by greatly improving the processing precision.

The present invention for achieving the above object is a method for manufacturing a conditioning disk in which a plurality of protrusions are integrally formed,

A feedstock forming step of forming a feed stock in which the ceramic powder and the thermoplastic resin binder are uniformly dispersed by mixing and pulverizing the ceramic powder and the thermoplastic resin binder; And

An injection molding step of molding the injection molded body by injecting the feedstock into the cavity of the injection mold while solidifying the feedstock;

A degreasing step of removing the thermoplastic resin binder in the injection molded body; And

It includes a sintering step of sintering the degreasing injection molding.

The ceramic powder and the thermoplastic resin binder of the feedstock have a volume ratio of 1: 0.3 to 0.7.

Accordingly, the present invention can fundamentally prevent the protrusions of the conditioning disk from falling off due to physical wear or chemical corrosion by using a thermoplastic resin instead of a metal material as a binder for fixing the ceramic powder.

The feedstock forming step is characterized in that the feedstock is formed by pulverizing the ceramic powder and the thermoplastic binder after three-dimensional mixing.

That is, the present invention has the advantage that the height uniformity of the projections can be precisely maintained by mixing the ceramic powder and the thermoplastic resin binder so as to be uniformly dispersed through the three-dimensional mixing process.

The feedstock forming step,

A first mixing step of three-dimensional mixing of the mixture of the ceramic powder and the thermoplastic resin binder for a predetermined time at room temperature under a vacuum atmosphere;

A second mixing step of raising the temperature to a first predetermined value capable of imparting fluidity to the thermoplastic resin binder while three-dimensional mixing;

A third mixing step of three-dimensional mixing and solidifying while maintaining the first set value for a predetermined time and then slowly cooling to a second set value; And

A pulverizing step of pulverizing the solidified mixture,

The second set value is characterized in that the temperature lower than the first set value.

In the injection molding step, the injection pressure of the feedstock is uniformly distributed.

The injection mold has a cavity therein, and includes a first mold having a plurality of injection holes and a second mold formed with an intaglio pattern, wherein the cavity dimension of the injection mold is larger than the size of the conditioning disk. do.

The ceramic powder is characterized in that the zirconia powder.

More preferably, the ceramic powder is characterized in that the partially stabilized zirconia powder.

The thermoplastic resin binder includes a binder, a swelling agent, and a plasticizer.

In the feedstock forming step, the flow aid is further added.

The flow aid is characterized in that the urethane.

Each of the ceramic powder and the thermoplastic binder is composed of particles of different sizes. Thereby, the space | gap of the part which contacts each other at the time of the mixing can be minimized.

The present invention as described above can fundamentally prevent particles from falling off due to wear and chemical corrosion occurring during the conditioning operation of the polishing pad, thereby preventing contamination of metal ions due to particle dropping or defective circuit shortage of the wafer. There is an effect that can be prevented.

In addition, the present invention can freely form the shape and number of the projections by greatly improving the processing precision, thereby having the effect of greatly improving the removal rate (removal rate).

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 to 3 illustrate a method of manufacturing a conditioning disk according to an embodiment of the present invention.

The present invention is for producing a conditioning disk 100 having a plurality of projections 110 formed on one side, one embodiment of the conditioning disk 100 is illustrated in FIG. Of course, the conditioning disk 100 manufactured by the present invention may be formed in various other forms without being limited to the form illustrated in FIG.

The conditioning disk 100 may be mounted on the body 200 side. Body portion 200 may be made of a material such as Teflon or stainless steel, which is excellent in corrosion resistance and chemical resistance, and easy to shape processing. In addition, the main body 200 is not necessarily required in terms of its function. The main function is to simply connect the motor shaft of the conditioning equipment.

First, a feedstock for injection molding is formed (S1). Feedstock is formed by pulverizing after cooling after mixing ceramic powder, thermoplastic binder, other additives and the like.

Since ceramic powders, thermoplastic resins, and additives are different from each other in specific gravity, they cannot be uniformly dispersed and mixed in a space where gravity exists, and also because of different pore or air content ratios inside the conditioning disk ( It is difficult to precisely control the height uniformity of the protrusions 110 of 100.

In order to solve this problem, the present invention may select one embodiment to uniformly disperse and mix the ceramic powder, thermoplastic resin binder, etc. through a three-dimensional mixing (rotational torsion mixing) process in a vacuum atmosphere.

However, the present invention is not limited to the three-dimensional mixing process of mixing the ceramic powder and the thermoplastic resin binder, and the two-dimensional mixing process over a long time of 12 hours or more if the ceramic powder and the thermoplastic resin binder can be uniformly dispersed and mixed. Alternatively, various other mixing processes may be applied.

A more specific embodiment of the feedstock forming step S1 is shown in FIG. 2.

First, a mixture of ceramic powder, thermoplastic binder, additives and the like is injected into the container, and the inner space of the container is made into a vacuum atmosphere, and then the container is mounted in a three-dimensional mixer (S1-1). Here, the inner space of the container is made in a vacuum atmosphere to improve the dispersion efficiency of the mixture by not containing bubbles or air during mixing of the mixture.

Then, the three-dimensional mixer is driven to three-dimensional mixing the mixture for a predetermined time at room temperature (S1-2).

Thereafter, three-dimensional mixing is performed while raising the temperature in the container to the first set value (S1-3). The first set value is a temperature such that fluidity can be imparted to the thermoplastic resin binder at about 150 ° C.

When the temperature reaches the first set point, the temperature is maintained for a predetermined time of about 10 to 30 minutes, and then gradually cooled and slowly solidified to the second set point with three-dimensional mixing and solidification (S1-4). The second set point is a temperature such that the fluidity of the thermoplastic resin binder can be reduced to a temperature of about 50 ° C. or less.

As a result, a coagulation mixture in which the ceramic powder and the thermoplastic resin binder are uniformly dispersed is produced, and the coagulation mixture is pulverized to form a feedstock (S1-5).

In addition, each of the ceramic powder and the thermoplastic binder may be made of particles of the same size, or alternatively, may be made of particles of different sizes (eg, zirconia particles having a size of 0.5 μm and zirconia particles having a size of 3.0 μm, etc.). In particular, when particles of different sizes are mixed, there is an advantage of minimizing the voids in contact with each other.

After heat softening the feedstock formed as described above, the heat softened feedstock is injected into the cavity 10a of the injection mold 10 as shown in FIGS. 3 (a) and 3 (b) and cooled. The injection molded body 20 is molded by solidification by, for example (S2).

The injection mold 10 includes a first mold 11 having a plurality of injection holes 11a and a second mold 12 having a plurality of grooves 12a engraved therein.

In the first mold 11, the plurality of injection holes 11a are spaced apart at regular intervals, whereby the injection pressure of the feedstock is equally distributed, so that the density of the molten feedstock injected into the cavity 10a is equalized.

A plurality of grooves 12a are formed in the inner surface of the second mold 12, and the plurality of grooves 12a are formed in a structure corresponding to the shape of the protrusion 110 of the conditioning disk 100.

On the other hand, the cavity 10a of the injection mold 10 may be made of a size larger than the size of the designed conditioning disk 100. This is to consider the shrinkage (20 ~ 35%) during the sintering of the injection molded body (20).

The injection molding step (S2) may be carried out through an automatic injection molding press, and when using the automatic injection molding press, by adjusting the pressing force appropriately according to the size of the conditioning disk, the shrinkage rate of the injection molded body 20 is sintered. Not only can it be minimized, but it can also stabilize strain due to density. In addition, the conditioning disk 100 in which the plurality of protrusions 110 are finally formed does not need to be post-processed.

Then, the thermoplastic resin binder in the injection molded body 20 is removed through a degreasing process (S3), and the injection molded body 20 from which the thermoplastic resin binder is removed is sintered through a sintering process as shown in FIG. Conditioning disk 100 is formed (S4).

In particular, the present invention uses the feedstock in which the thermoplastic resin binder is uniformly dispersed through the three-dimensional mixing process, the shrinkage (20 ~ 35%) of the injection molded body 20 during the sintering of the injection molded body 20 You can evenly spread across the surface. As a result, the plurality of protrusions 110 may maintain a precision of about 20 to 30 μm or less in height uniformity, and therefore, additional post-processing is required for planarizing the surface of the conditioning disk 100 or the protrusion 110 after sintering. It doesn't work. Accordingly, the present invention has the advantage that can be very easy to mass production with a minimum number of facilities and personnel.

In addition, the present invention manufactures the conditioning disk 100 by using a thermoplastic binder instead of the metal binder, the prepared conditioning disk 100 minimizes the dropping of the projection 110 or particles due to wear or corrosion, etc. can do.

Meanwhile, zirconia powder having good corrosion resistance, acid resistance, heat resistance, etc. may be used in the ceramic powder of the present embodiment. Particularly, a partial stabilizer such as Y ₂ O ₃ may be added to the zirconia powder to facilitate molding.

An example of such a partially stabilized zirconia is as follows.

ZrO ₂ + Y ₂ O ₃ + HfO ₂ + Al ₂ O ₃ wt%:> 99.7

Y ₂ O ₃ wt%: <5.15

Al ₂ O ₃ wt%: <0.25

SiO ₂ wt%: <0.02

This partially stabilized zirconia changes its crystal structure with temperature, but has a monoclinic crystal structure at room temperature. This monoclinic crystal structure changes into a tetragonal structure at about 1,200 ° C. or more, and this phase transformation is known as martensite. In addition, in order to obtain a dense zirconia sintered body, various oxides such as CaO, MgO, CeO ₂ , Y ₂ O _3, etc. may be added as stabilizers. It becomes a tetragonal or cubic structure so that transformation does not occur during cooling to avoid deformation and cracking. Accordingly, the ceramic powder of the present embodiment may be partially stabilized zirconia (PSZ, Partially Stabilized Zircornia). In addition, the molding density can be increased by finely controlling the amount of the partial stabilizer such as Y ₂ O ₃ .

The binder of this embodiment has sufficient fluidity during injection molding, should have good releasability from the mold, and is made of a material having good degreasing property. Since it is difficult to exhibit such a property simultaneously with a single thermoplastic resin, it is good to use combining various types of resin. The binder consists of a binder, a swelling agent, a plasticizer and the like.

As the binder, polyethylene, polypropylene, ethylene vinyl acetate copolymer, ethylene acrylic copolymer, polystyrene and the like having good fluidity upon heating may be used, and polystyrene, atactic polypropylene, metalacrylic resin, polyaceta having good degreasing properties Etc. can be used.

As the swelling agent, paraffin wax, microcrystalline wax, stearic acid, adumi wax and the like are used.

Butyric acid ester can be used as a plasticizer.

Since the fluidity is secured through the binder in the injection molding step (S2), the composition and the amount of the binder may be combined in consideration of fluidity, mold release property, and degreasing property. On the other hand, when the amount of the binder is added, the fluidity is good, but the degreasing property is difficult, or the shrinkage during sintering becomes large, so that the precision of the sintered body is deteriorated.

In addition, the present invention may further add a resin (RESIN) component such as PP, PE or the like as a flow aid to facilitate the flow. These flow aids can control the molding density according to the amount, and the more flow aids of these resin components, the better the fluidity, so that the injection molding can be performed more smoothly. This can happen. Here, by adjusting the content of the resin to 3 to 25 wt% according to the size of the product it is possible to minimize the degree of shrinkage bending.

Urethane is preferred as the fluidity aid in the present embodiment, and as the urethane is added, it is possible to secure greater fluidity than any material with a small amount, and excellent shape retention ability to more easily overcome the difference in molding density. there was.

The following shows an example of the composition of a feedstock which is the molding material of the present invention.

Partially stabilized zirconia (ZrO ₂ + Y ₂ O ₃ + HfO ₂ + Al ₂ O ₃ ) ----- 84.10 wt%

            Urethane ------------------------------------- 5.17 wt%

            Polystyrene --------------------------------- 3.20 wt%

            Atactic Polypropylene ------------------------ 2.93 wt%

            Stearic Acid --------------------------------- 0.42 wt%

            Nonionic Surfactant ------------------------ 4.18 wt%

Here, the content of Y ₂ O ₃ can be variously changed depending on the size of the conditioning disk 100 in about 2-6%.

Experimental Example 1

Through a physical method, the experiment was conducted to compare the dropping condition of the conditioning disk produced by the present invention and the conventional example.

Using a waterjet with a 0.3 mm diameter orifice, spaced approximately 30 mm from the target product (invention and prior art), the water pressure is 40,000 psi (2.812 kgf / cm 2), and the orifice head is 1,000 mm / min. Transfer at a feed rate of 800mm / min, 500mm / min, or 300mm / min.

The result is shown in [Table 1] below.

[Table 1]

Feed speed The present invention Conventional example 1,000mm / min No particle dropout Fine grain dropout 800mm / min No particle dropout Severe particle dropouts 500mm / min No particle dropout Severe particle dropouts 300mm / min Particle dropout Severe particle dropouts

From this, it can be seen that the conditioning discs produced by the present invention do not easily drop their particles due to physical external forces.

Experimental Example 2

After immersing the conditioning disk and the conventional example according to the present invention in HCl stock solution, the protrusions or particles were dropped after a certain period of time.

First, it was observed that as soon as the conventional example was put into the HCl stock solution, bubbles or air started to be generated and corrosion started. And after 4 hours, the phenomenon that the whole diamond particle fell by reaction with an acid was observed.

On the other hand, it can be seen that the conditioning disk according to the present invention is chemically stable because it is made of a ceramic material and thus does not react with acid in the HCl stock solution at all.

1 is a process chart showing a manufacturing method of a conditioning disk according to an embodiment of the present invention.

Figure 2 is a process diagram showing in detail the feedstock forming step according to the present invention.

3 is a view showing an injection molding step according to the present invention.

4 shows an exemplary embodiment of a conditioning disk made in accordance with the present invention.

Brief description of symbols for the main parts of the drawings

10: injection mold 10a: cavity

11: first mold 12: second mold

20: injection molding 100: conditioning disk

110: turning

Claims (12)

In the method of manufacturing a conditioning disk in which a plurality of projections are formed integrally, A feedstock forming step of forming a feed stock in which the ceramic powder and the thermoplastic resin binder are uniformly dispersed by mixing and pulverizing the ceramic powder and the thermoplastic resin binder; An injection molding step of molding the injection molded body by injecting the feedstock into the cavity of the injection mold while solidifying the feedstock; A degreasing step of removing the thermoplastic resin binder in the injection molded body; And And a sintering step of sintering the degreased injection molded body. The method of claim 1, The ceramic powder and the thermoplastic resin binder of the feedstock has a volume ratio of 1: 0.3 to 0.7 characterized in that the manufacturing method of the conditioning disk for the polishing pad. The method of claim 1, Wherein the feedstock forming step, the ceramic powder and the thermoplastic binder is a grinding pad manufacturing method for producing a conditioning disk, characterized in that the feedstock is formed by grinding after the three-dimensional mixing of the mixing of the rotational twist method. The method of claim 3, The feedstock forming step, A first mixing step of three-dimensional mixing of the mixture of the ceramic powder and the thermoplastic resin binder for a predetermined time at room temperature under a vacuum atmosphere; A second mixing step of raising the temperature to a first predetermined value capable of imparting fluidity to the thermoplastic resin binder while three-dimensional mixing; A third mixing step of three-dimensional mixing and solidifying while maintaining the first set value for a predetermined time and then slowly cooling to a second set value; And A pulverizing step of pulverizing the solidified mixture, And said second set point is at a lower temperature than said first set point. The method of claim 1, Method of manufacturing a conditioning disk for a polishing pad, characterized in that uniformly distribute the injection pressure of the feedstock in the process of injecting the feedstock into the cavity of the injection mold during the injection molding step. The method of claim 1, The injection mold has a cavity therein, and includes a first mold having a plurality of injection holes and a second mold having an intaglio pattern, and the cavity dimension of the injection mold is larger than the size of the conditioning disk. A manufacturing method of a conditioning disk for a polishing pad. The method of claim 1, Said ceramic powder is a zirconia powder. The method of claim 7, wherein And said ceramic powder is a partially stabilized zirconia powder. The method of claim 1, The thermoplastic resin binder is a manufacturing method of the polishing disk conditioning disk, characterized in that it comprises a binder, a swelling agent, a plasticizer. The method of claim 1, In the feedstock forming step, the manufacturing method of the conditioning disk for polishing pad, characterized in that further adding a flow aid. The method of claim 10, The flow aid is a manufacturing method of the conditioning disk for polishing pad, characterized in that the urethane. The method of claim 1, And the size of the particles of the thermoplastic resin binder and the size of the particles of the thermoplastic resin binder are different from each other.

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