US20070149094A1

US20070149094A1 - Monitoring Device of Chemical Mechanical Polishing Apparatus

Info

Publication number: US20070149094A1
Application number: US11/615,089
Authority: US
Inventors: Jae Choi
Original assignee: Dongbu Electronics Co Ltd
Current assignee: DB HiTek Co Ltd
Priority date: 2005-12-28
Filing date: 2006-12-22
Publication date: 2007-06-28

Abstract

A monitoring device and method of a chemical mechanical polishing apparatus are provided. Embodiments may form a uniform surface of a polishing pad and monitor a CMP process by incorporating piezoelectric sensors capable of monitoring a pressure applied to a pad on a rear surface of a polishing pad. The monitoring device can include: a polishing pad; a plurality of piezoelectric sensors formed at a rear surface of the polishing pad for detecting a pressure applied to the polishing pad; a communication section connected to the piezoelectric sensors for transmitting data detected by the piezoelectric sensors; and a display section for displaying the data transmitted from the communication section.

Description

RELATED APPLICATION

This application claims the benefit under 35 U.S.C. § 119(e), of Korean Patent Application 10-2005-0132649 filed Dec. 28, 2005, which is incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to a monitoring device of a chemical mechanical polishing apparatus.

BACKGROUND OF THE INVENTION

In a process for manufacturing a semiconductor device, in order to remove a metal thin film and an oxide layer, a chemical mechanical polishing process is performed. In the chemical mechanical polishing process, after a wafer has been mounted on an upper portion of a polishing pad, the wafer is ground to a predetermined thickness. Then, it is passed to a next stage.
The chemical mechanical polishing process is used as the means for a planarization process of an insulating layer and a damascene process of a metal layer.
A chemical mechanical polishing process is one of the necessary semiconductor processes used to meet a planarization demand according to the reduced size and increased integration of semiconductor devices.
Such a chemical mechanical polishing process is divided into a polishing step for polishing a wafer and a washing step. In the polishing step, after a wafer is mounted on a polishing table and is ground to a predetermined thickness, it is passed to the washing step. The washing step washes the wafer polished in the polishing step.
The following is a description of a chemical mechanical polishing apparatus according to the related art with reference to the accompanying drawings.
FIG. 1 is a perspective view showing a chemical mechanical polishing apparatus according to the related art.
As shown in FIG. 1, the chemical mechanical polishing apparatus includes a table 10, a polishing pad 20, a backing 50, a retaining ring 40, a head 60, a slurry supply portion 80, and a conditioner 70. The table 10 can rotate. The polishing pad 20 is formed on the table 10. A wafer 30 is positioned at one side of the polishing pad 20. The backing 50 and the retaining ring 40 protect the wafer 30 from a pressure applied to an upper portion thereof and support the wafer 30. The head 60 applies a force to an upper portion of the backing 50 and rotates the backing 50. The slurry supply portion 80 supplies a slurry to the polishing pad 20. The conditioner 70 removes refuse discharged from the polishing step and adjusts a surface of the polishing pad 20.
The polishing pad 20 of the chemical mechanical polishing apparatus is composed of a polymer pad, which is often made of polyurethane.
The chemical mechanical polishing apparatus moves the wafer 30 and dispenses a chemical solution and particles in the slurry supply portion 80 to process a surface of the wafer 30. Accordingly, properties of the slurry supply portion 80 and the polishing pad 20 exert a significant influence upon the chemical mechanical polishing process.
The polishing pad 20 directly contacts with the wafer 30. A surface state of the polishing pad 30 has a significant influence upon the polishing rate, uniformity, and defects.
Recent polishing pads have various constructions and materials according to their purpose However, the most commonly used polishing pad is manufactured by putting a heat curing agent in a polymer with a microcapsule, and heating the resulting object using an oven.
Grooves of various shapes for a floating of slurry are formed at a surface of the manufactured polishing pad using a cutter.
However, the polishing pad 20 of the chemical mechanical polishing apparatus according to the related art has a non-uniform surface. Since the polishing pad manufactured through the aforementioned method has a non-uniform surface in a groove formation step, it is not ground to a desired size

BRIEF SUMMARY

Accordingly, the present invention is directed to a monitoring device and method of a chemical mechanical polishing (CMP) apparatus that can address or substantially obviate one or more problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide a monitoring device and method of a chemical mechanical polishing apparatus, which may form a uniform surface of a polishing pad. Embodiments of the present invention can monitor a CMP process by including piezoelectric sensors capable of monitoring a pressure applied to a pad at a lower portion of the pad.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these objects and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, there is provided a monitoring device of a chemical mechanical polishing apparatus comprising: a polishing pad; a plurality of piezoelectric sensors formed at a rear surface of the polishing pad for detecting a pressure applied to the polishing pad; a communication section connected to the piezoelectric sensors for transmitting data detected by the piezoelectric sensors; and a display section for displaying the data transmitted from the communication section.
In another aspect of the present invention, there is provided a method for monitoring a chemical mechanical polishing apparatus comprising: providing a plurality of piezoelectric sensors at a rear surface of a polishing pad; detecting a pressure applied to the polishing pad by the piezoelectric sensors; and transmitting data detected by the piezoelectric sensors to a display section so that the display section displays the data.
It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principle of the invention.
FIG. 1 is a perspective view showing a chemical mechanical polishing (CMP) apparatus according to the related art.
FIG. 2 is a cross-sectional view for describing a method for forming a polishing pad of a CMP apparatus according to an embodiment the present invention.
FIG. 3 is a photograph showing a surface of a polishing pad according to the embodiment of FIG. 2.
FIG. 4 is a plan view showing a polymer sensor formed at a rear surface of the polishing pad of a chemical mechanical polishing apparatus according an embodiment of to the present invention.
FIG. 5 is a photograph showing a surface of a polishing pad according to the embodiment of FIG. 4.
FIG. 6 is a view showing a construction of the monitoring device of the CMP apparatus according to an embodiment of the present invention.
FIG. 7 is a block diagram showing a communication section in the monitoring device of the CMP apparatus according to an embodiment of the present invention.
FIG. 8 is a flow chart illustrating a monitoring method of a CMP apparatus according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.
Hereinafter, a monitoring device and method of a chemical mechanical polishing (CMP) apparatus according to an embodiment of the present invention will be described with reference to the accompanying drawings.
FIG. 2 is a cross-sectional view for showing a method for forming a polishing pad of a CMP apparatus according to an embodiment of the present invention.
With reference to FIG. 2, a master mold 112 can be mounted on a first stage 100 a. The master mold 112 can have a pattern with a phase inverse to that of desired pad grooves.
In a specific embodiment, the master mold 112 can be formed with grooves having the inverse phase pattern by performing an etching process, and can be made of a metal SUS material.
A polymer film 111 can be mounted at an upper portion of a second stage 100 b to face the master mold 112.
The polymer film 111 is then placed in contact with the master mold 112. When heat and pressure are applied to the polymer film 111, grooves having an inverse phase from that of the master mold 112 are formed in the polymer film.
Further, by cooling the polymer film 111 in which the grooves are formed, a polishing pad is formed.
The polymer film 11 can be a material layer of the polishing pad. Through the aforementioned process, a more uniform pressure can be applied to the entire surface of the polymer film 111. Therefore, grooves can be formed having a uniform surface as compared to the pads formed by the cutter of the related art.
After the uniform grooves have been formed on the polymer film 111, the second stage 100 b can be separated from the polymer film 11.
In a further embodiment the first and second stages 100 a and 100 b can be composed of a hot plate to which heat is applied. In addition, the polishing pad can be formed in a vacuum state.
FIG. 3 is a photograph showing a surface of a polishing pad formed by the embodiment of FIG. 2.
As shown in FIG. 3, the polishing pad of the CMP apparatus of the present invention formed by the method of FIG. 2 includes grooves 113 having a surface of a uniform arrangement.
FIG. 4 is a plan view showing a polymer sensor formed at a rear surface of the polishing pad of a chemical mechanical polishing apparatus according to an embodiment of the present invention. FIG. 5 is a view showing a polymer film 111 incorporating the embodiment of FIG. 4 and the polymer sensor 120 formed at a rear surface of the polymer film 111.
Referring to FIG. 4, a plurality of polymer sensors 120 can have a uniform arrangement and can be formed at a rear surface of the polymer film 111.
The polymer sensor 120 can be made of a polyurethane component device having a piezoelectric function. Because the main component of the polymer sensor 120 is a polymer, it is not damaged by an external pressurization and can be freely bent. Accordingly, the polymer sensor 120 can be attached to a desired position of the polymer film 111.
When an external voltage is applied to the polymer sensor 120, a displacement occurs in the polishing pad, and when the displacement occurs in the polymer sensor 120, the polishing pad generates a voltage.
Accordingly, it is understood that a pressure distribution by regions in a surface of a wafer is provided during the CMP process. By analyzing the pressure distribution, it is possible to obtain an exact estimation during a set-up of the CMP process or slurry development.
Referring to FIG. 5, the polishing pad can include a polymer film 111 and piezoelectric polymer sensors 120. The polymer film 111 includes grooves, which are uniformly formed at a surface thereof. The polymer sensors 120 can be regularly arranged at a rear surface of the polymer film 111.
In a specific embodiment, each of the polymer sensors 120 is a piezoelectric sensor. The polymer sensors 120 can be regularly arranged at a lower, or rear, side of the polymer film 111.
Because the polymer sensors 120 do not make contact with the wafer, the wafer is not damaged by the polymer sensors.
Each of the polymer sensors 120 functions to detect a pressure state applied to the wafer according to an electric signal from regions of the wafer.
The following is an explanation of piezoelectricity and a formation method of the polymer sensors 120.
In general, piezoelectricity is a property of a noncentral symmetry crystal material, and occurs by a dipole moment due to a noncentral symmetry of a lattice. The piezoelectricity may convert electric energy into dynamic energy, and perform an inverse conversion.
Examples of piezoelectric material include lead xirconate (PZT), barium titanate (BaTiO3), and zinc oxide (ZnO). In addition, polymer materials having piezoelectricity include a copolymer of poly vinylidene fluoride (PVDF or PVF2: β-phase) and vinylidene fluoride, and poly(vinylidene Fluoride-Co-Trifluoro Ethylene): P(VDF-TrFE) copolymer.
Electrostriction is a phenomenon where strain or stress occurs under a strong electric field. Although the principle of the occurrence of the electrostriction is not known, it is a general view that the strain occurs due to an electrostatic force generated by a charge applied between flexible electrodes.
Such an electrostriction can convert an electric energy into a dynamic energy but cannot perform a reverse conversion. The strain occurs in proportion to a square of an intensity of an applied electric field.
It has been reported that examples of electrostriction materials are polyurethane (PU), silicon rubber, fluoro-silicon, ethylene propylene, and polybutadiamine.
However, polyurethane has been used in clothing, shoes, bags, and miscellaneous goods. In addition, polyurethane is used for water-proofing, fire prevention, vibration isolation products, waterproof cloth for industrial materials, and moisture transpiration waterproof cloth for clothes. Here, a surface of synthetic leather is coated with the polyurethane. Nonetheless, it has not been reported that these products use the electrostriction and piezoelectricity properties of polyurethane.
Polyurethane is a hemicrystalline polyer simultaneously having a crystalline and an amorphous structure. In general, polyurethane is composed of polyol, a chain extender, and isocyanate.
Polyurethane is divided into a hard segment and a soft segment according to a shape thereof. The polyol constitutes the soft segment, and the chain extender and isocyanate are combined with each other to form the hard segment.
The crystalline structure in the hard segment and the soft segment is a main factor influencing piezoelectricity. The soft segment is the main factor influencing the electrostriction of the polyurethane. The polyurethane has both electrostriction and piezoelectricity. In order to increase the piezoelectricity, the crystalline degree of structural elements is reduced. Further, the polyurethane having a maximized crystalline degree increases a directional property of crystallines through an applied electric field process.
Moreover, so as to improve the electrostriction, polyol having no crystallines is synthesized by a solution polymerization method, which is a first process for manufacturing the polyurethane in order to increase the piezoelectricity. Further, components for increasing an elastic force are added thereto.
The solution polymerization method is a polymerization method that suitably melts a monomer in an inert solvent and adds a soluble catalyst to polymerize the solution.
The polymer sensor 120 formed at a rear surface of the polishing pad in the CMP apparatus according to an embodiment the present invention can be made of polyurethane having a piezoelectricity. The polyurethane having the piezoelectricity may be obtained by synthesizing the polyurethane using polytetramethelen ether grycol (PTMG) and by adding trimethylol propane (TMP) to increase an elastic property. Here, the PTMG is a polyol having no crystallines.
FIG. 6 is a schematic view showing a construction of the monitoring device of the CMP apparatus according to an embodiment the present invention.
As shown in FIG. 6, the monitoring device can include a table 210, a polishing pad 220, a plurality of piezoelectric sensors, a support member 230, a blue tooth module 240, and a display section 250. The table 210 can rotate. The polishing pad 220 can be formed having a uniform surface on the table 210. The plurality of piezoelectric sensors can be uniformly arranged at a rear surface of the polishing pad 220 and spaced apart from each other to detect a pressure applied to the polishing pad 220. The support member 230 supports the table 210. The blue tooth module 240 can be installed at one side of the support member 230 to be connected to the piezoelectric sensors, and transfers the pressure data detected by the piezoelectric sensors. The display section 250 can display the data transferred through the blue tooth module 240.
FIG. 7 is a block diagram showing a communication section in the monitoring device of the CMP apparatus according to an embodiment of the present invention.
As shown in FIG. 7, the communication section can be a blue tooth module. The blue tooth module 240 can include a signal pass filter 241, an analog/digital (A/D) converter 242, and a blue tooth communication section 243. The signal pass filter 241 receives the pressure data detected by the piezoelectric sensors and removes unnecessary noise included in the data. The A/D converter 242 converts the analog signal outputted from the signal pass filter 241 into a digital signal. The blue tooth communication section 243 transfers the digital signal from the A/D converter 242 to an external computer.
The following is a description of the monitoring method of the CMP apparatus according to an embodiment of the present invention.
FIG. 8 is a flow chart illustrating a monitoring method of a CMP apparatus according to an embodiment of the present invention.
As shown in FIG. 8, first, a polishing pad having a uniform surface can be formed (S100). The polishing pad can be formed using the method described with respect to FIG. 2.
Next, a plurality of piezoelectric sensors can be arranged at a rear surface of the polishing pad and spaced apart from each other by a predetermined distance (S200).
The piezoelectric sensors detect a pressure applied to the polishing pad (S300).
Next, the data detected by the piezoelectric sensors can be transmitted to a display section of an external computer to be monitored (S400).
Here, a procedure of transmitting the data to the display section will now be explained in detail with reference to FIG. 7.
That is, the signal pass filter 241 receives the data obtained by the piezoelectric sensors and removes unnecessary noise included in the data. The A/D converter 242 converts the analog signal being an output signal of the signal pass filter 241 into a digital signal, which may be calculated by a computer.
Next, the blue tooth communication section 243 transmits the digital signal from the A/D converter 242 to the display section 250 so that the display section 250 displays the digital signal. The blue tooth communication section 243 is a device capable of transmitting and receiving a signal in a wireless manner.
Since the CMP apparatus is a rotating piece of equipment, a ring type jig (slip rig) is required to transmit the data to an exterior when not using a wireless communication in order to not be influenced by a rotation. However, the ring type jig can have an influence upon the rotation of the CMP apparatus. Therefore, when a wireless communication device is used, it can easily transmit the data to an external computer.
As described above, the transmitted data is transmitted to a computer through a receiver of a blue booth device. Accordingly, the receiver calculates and displays a required pressure distribution of an entire surface of a wafer.
However, it should be noted that while the blue tooth device is explained as an example of a wireless communication device, used in embodiments of the subject invention, the present invention is not limited thereto. For example, any wireless communication method can be used, including zigbee, infrared ray communication, and ultra wide band.
As is seen from the forgoing description, the monitoring device and method of a chemical mechanical polishing apparatus according to embodiments of the present invention can have following effects.
That is, the present invention may prevent an original signal from being distorted due to a touch-signal transmission manner such as a slip ring by using a wireless communication device. Further, embodiments of the present invention can provide exact detection of a pressure distribution of a pad surface according to a CMP process condition and a process condition at a set-up. In addition, the present invention may remove a random effect occurring due to a non-uniformity of the pad surface during an estimation of a slurry in order to exactly estimate the slurry.
It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention. Thus, it is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Claims

1. A monitoring device of a chemical mechanical polishing apparatus, comprising:

a polishing pad;

a plurality of piezoelectric sensors formed at a rear surface of the polishing pad for detecting a pressure applied to the polishing pad;

a communication section connected to the piezoelectric sensors for transmitting data detected by the piezoelectric sensors; and

a display section for displaying the data transmitted from the communication section.

2. The monitoring device according to claim 1, wherein each of the plurality of piezoelectric sensors is a polymer sensor.

3. The monitoring device according to claim 1, wherein the plurality of piezoelectric sensors are capable of detecting pressure applied to the polishing pad according to a position of the polishing pad.

4. The monitoring device according to claim 1, wherein the communication section comprises a blue tooth, zigbee, infrared ray communication, or ultra wide band transmission.

5. The monitoring device according to claim 1, wherein the communication section comprises:

a signal pass filter for receiving and filtering data detected by the plurality of piezoelectric sensors;

an analog/digital converter for converting an analog signal outputted from the signal pass filter into a digital signal; and

a blue tooth communication section for transmitting the digital signal from the analog/digital converter to the display section.

6. The monitoring device according to claim 1, wherein the polishing pad is a polymer film.

7. The monitoring device according to claim 1, wherein the polishing pad comprises regularly formed grooves.

8. A method for monitoring a chemical mechanical polishing apparatus, comprising:

providing a plurality of piezoelectric sensors at a rear surface of a polishing pad;

detecting a pressure applied to the polishing pad by the plurality of piezoelectric sensors; and

transmitting data corresponding to pressure detected by the plurality of piezoelectric sensors to a display section for displaying the data.

9. The method according to claim 8, wherein transmitting the data comprises using a wireless communication.

10. The method according to claim 9, wherein the wireless communication uses a bluetooth module.

11. The method according to claim 8, wherein the polishing pad is formed by a process comprising:

preparing a master mold in which negative-phase grooves are formed through an etching process;

mounting a polymer film to face the master mold;

applying heat and pressure to the master mold and the polymer film to form grooves in the polymer film having a phase inverse to the negative phase grooves of the master mold; and

cooling the polymer film.