KR100223953B1 - Pad Conditioner in Chemical Mechanical Polishing Device - Google Patents

Abstract

The present invention relates to a pad conditioner of a CMP apparatus for removing clogging of a polishing pad generated during wafer processing using a CMP apparatus.

The pad conditioner of the present invention includes a swing arm installed so that its outer end moves repeatedly to the top of the polishing pad around the rotational shaft located on one side of the upper side of the CMP apparatus and vibrates repeatedly on the surface of the pad, and the end of the swing arm. The rotating oscillator and the outer circumferential surface of the swing arm are fixed to the end of the swing arm, which are coupled to the rotating device and the oscillation device for horizontal rotation and vertical vibration of the conditioning tool. It consists of.

The pad conditioner of the present invention has an advantage of extending the life of the pad and improving the processing efficiency of the wafer by finely removing the fine particles of the slurry clogged on the surface of the pad by high frequency vibration.

Description

Pad Conditioner for Chemical Mechanical Polishing (CMP) Devices

1 is a longitudinal cross-sectional view schematically showing a polishing process of a wafer using a CMP apparatus.

2 is a plan view of a CMP apparatus having a pad conditioner according to one embodiment of the present invention.

3 is a front view of the FIG. 2 device.

Figure 4 is a longitudinal sectional view of the rotary vibrator and the shanghai conveying apparatus of the present invention.

5 is a scanning electron micrograph of a pad surface conditioned using the pad conditioner of the present invention.

(a) is the new pad surface,

(b) is the blinded pad surface before conditioning,

(c) is the pad surface after conditioning.

* Explanation of symbols for main parts of the drawings

10: CMP apparatus 11: pad

14 wafer carrier 16 swing arm

17: Shanghai transport mechanism 18: rotating vibrator

21: end effector cleaning section 25: pneumatic cylinder

29: vibration generating device 35: tool mounting opening

36: Conditioning Tool

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wafer polishing technique using a chemical mechanical polishing (CMP) apparatus as a method of processing a semiconductor wafer, and more particularly, to a slurry form supplied during a wafer polishing process using a CMP apparatus. This invention relates to a pad conditioner of a CMP apparatus which improves the polishing efficiency by removing the fine particles of the slurry stuck to the air gap on the pad surface and fixed to the pad surface by the rotational motion and the high frequency vibration of the pad conditioner.

As a next-generation semiconductor wafer processing method that has been recently developed and gained attention, CMP allows mechanical removal and mechanical removal through a slurry between a wafer to be processed and a polishing pad. The structure of the CMP device and the wafer processing process will be described with reference to the schematic diagram of the general CMP device of FIG.

As shown in the drawing, the CMP apparatus has a polishing pad 2 attached to an upper surface of a rotary table 1 having a generally flat upper surface, and on the upper side of the pad 2, a wafer 3 to be processed is placed. The wafer carrier 4 to be mounted is provided, and during processing of the wafer 3 using the CMP apparatus having such a structure, the wafer 3 is continuously supplied to the center portion of the upper surface of the pad 2. The carrier 4 to which the is mounted is pressed (P) with respect to the upper surface of the pad 2, and the carrier 4 and the turntable 1 are rotated so that the wafer 2 can be polished.

At this time, in order to smoothly supply the slurry 5 between the wafer 3 and the pad 2, the carrier 4 is moved in the horizontal direction in parallel with the simple rotation of the rotary table 1 and the carrier 4. Oscillation is being added.

On the other hand, the slurry 5 supplied between the processing target surface of the wafer 3 and the upper surface of the pad 2 has, for example, a fumed silica having a particle size of several tens to hundreds of mm in diameter and excellent in corrosiveness to the wafer 3. It is a composition suspended in an alkaline aqueous solution such as KOH and made into colloidal silica in a gel state by pressurization of the wafer 3, and then the surface of the wafer 3 is removed by SiO ₂ adhesion and peeling action by horizontal relative motion. It is chemically removed micromechanically.

In addition, the polishing pad 2 is made of, for example, a urethane pad impregnated with a foamed urethane in a flexible nonwoven fabric, and a plurality of micropores are present on the surface of the pad, so that slurry is incorporated into the pores, so that the chemicals of the wafer, Induce mechanical polishing.

When polishing a wafer using such a conventional CMP apparatus, as the polishing progresses, sharp points on the surface of the pad are worn down due to pressure and rocking motion applied from the wafer toward the pad, and the wear component of the workpiece is collapsed. The so-called glazing occurs when the mixture of and the slurry blocks the voids on the pad surface.

As such, when the sharp point of the pad surface is worn out or clogged, the pad can no longer hold the slurry, thereby deteriorating the polishing efficiency of the wafer and the uniformity of the processed surface.

Therefore, in the conventional CMP apparatus, after the processing of several to several dozen wafers, the surface of the pad is ground using an electrodeposited diamond disk to remove the clogging and the like, thereby creating a new pad surface by removing the pad surface layer. The wafer is processed continuously on the pad.

However, in the conventional conditioning of the pad using the electrodeposited diamond disk, diamond particles are dropped from the disk to cause scratches on the surface of the wafer to be processed, or the disk itself or the adhesive material between the disk and the diamond (sus or Ni, etc.). Metal particles are separated from the wafer and contaminate the wafer and the pad. In some cases, the entire pad must be replaced as a result of pad contamination.

In addition, when the pad is polished using the diamond disk, the pad life is shortened due to the abrasion of the pad to be removed, and overall, the pad conditioning requires a long time, which adversely affects the yield. The disadvantages are also pointed out.

Accordingly, the present invention is to solve the above-mentioned problems which are pointed out in the conditioning of the pad required for the processing of the wafer using a conventional CPM apparatus, and a rotary oscillator that performs vertical high-frequency vibration in parallel with the rotational movement. It is an object of the present invention to provide a pad conditioner of the CPM device that can effectively eliminate the clogging of the pad through.

The object of the present invention is a swing arm that is rotatably installed on one side of the upper surface of the CPM apparatus, a swing arm drive motor installed on the pivot center axis of the swing arm to transmit driving force to the swing arm, and fixed to the free end of the swing arm. It is achieved by a structure consisting of a rotary vibrator.

At this time, the rotary oscillator is casing is fixed to the end of the outer peripheral surface one side of the swing arm, the drive motor is installed on the upper outer side of the casing and the motor shaft is penetrated into the casing, the motor shaft of the drive motor is coupled to the casing Vibration generating device is installed so as to be rotated from the inside and the lower portion of the casing, and the tool mounting and coupled to the vibration generating device is composed of a shanghai conveying mechanism for driving up and down the rotary vibrator.

Therefore, the conditioning tool mounted on the lower end of the rotary oscillator of the present invention is to perform both the rotational motion and the oscillation motion by the vertical vibration generated from the vibration generating device together with the rotation in the horizontal direction by the drive of the drive motor. Consists of.

Objects, technical configurations and effects of the present invention will be clearly understood by the following detailed description with reference to the drawings showing preferred embodiments of the present invention.

First, FIG. 2 is a plan view of a CPM apparatus equipped with an embodiment pad conditioner of the present invention, and FIG. 3 is a front view of the apparatus of FIG.

As shown in the figure, the CPM apparatus 10 of the present invention has a polishing pad 11 rotatably installed at a substantially central portion of an upper surface thereof, and is guided to a horizontal transfer mechanism 12 at the top of the pad 11 so as to be horizontal. In the CPM apparatus, the carrier driver 13 is installed to be transportable, and the wafer carrier 14 is provided on one side of the carrier driver 13 to receive the power from the carrier driver 13 to move up and down. A swing arm 16 driven by the driving motor 15 is rotatably installed on one side of the CPM device 10, and a shanghai transport mechanism 17 is mounted on the free end of the swing arm 16. Rotating oscillator 18 is coupled to the structure.

In the figure, reference numeral 19 is a driving motor for transmitting a driving force to the horizontal transfer mechanism 12, 20 is a weight (weight) for balancing is installed on the upper rotation shaft of the swing arm 16, 21 is the end End effector clean station.

FIG. 2 shows the pre-operational state of the swing arm 16. At this time, the end effctor of the rotary oscillator 18 is located in the end effector cleaning unit 21 filled with the cleaning liquid. The swing arm is rotated counterclockwise from the state of FIG. 2 by the operation of FIG. 15 to indicate the state in which the rotary oscillator 18 is moved to the upper portion of the pad 11. Thus, the rotary oscillator 18 swings. The rotation of the arm 16 is configured to reciprocate between the end effector cleaning portion 21 and the pad 11 surface.

The structure of the rotary vibrator 18 of the present invention will be described in detail based on the longitudinal sectional view of the rotary vibrator shown in FIG.

As shown, the rotary oscillator 18 of the present invention is coupled to the shank conveying device 17 for conveying it up and down, this shank conveying device 17 is a piston in the cylinder chamber 22 as a closed space (23) and the piston rod 24 is composed of a pneumatic cylinder (25) formed to reciprocate and a rotary oscillator casing (26) which is connected to the piston rod (24) to move up and down, and the rotary oscillator casing (26) The vibration generator 29 is inserted therein, and the upper end thereof is coupled to the end of the piston rod 24 so that the rotary oscillator casing 26 is moved up and down by the operation of the pneumatic cylinder 25.

That is, the pneumatic cylinder (25) is horizontally fixed at all times as the outer peripheral surface of the swing arm 16 is coupled to the outer peripheral surface of the cylinder 27 is formed integrally formed integrally with the outer peripheral surface of the cylinder 27 As the position is maintained, the rotary oscillator casing 26 coupled with the piston rod 24 of the pneumatic cylinder 25 is moved up and down in accordance with the operation of the pneumatic cylinder 25.

At this time, the drive motor 28 is mounted on the outer surface of the upper surface of the rotary oscillator casing 26 so that the motor shaft 28a penetrates into the rotary oscillator casing 26, and the vibration generating device 29 therein. Is rotatably provided by a bearing 30 interposed between the inner wall of the rotary oscillator casing 26.

On the other hand, the vibration generator 29 is driven from the drive motor 28 by a coupling rod 31 formed at the center of the upper surface and a coupling 32 for coupling the connecting rod 31 and the motor shaft 28a. As the rotational driving force is transmitted, the inside of the rotary oscillator casing 26 is driven by the driving motor 28.

The vibration generating device 29 is composed of a vibration generating element 33 for generating a high frequency vibration or ultrasonic vibration and a booster 33a for amplifying the vibration generated from the vibration generating element 33 and these connection rods 31 It is driven by the power supplied through the brush 34 in contact with the). At this time, a specific example of the vibration generating element 33 may be a piezoelectric transducer (transducer), it is preferable to use a carbon brush as the brush 34.

In addition, the vibration generating device 29 is designed to maintain its exposed state outside the bottom of the cylinder 27 at its end, that is, the lower portion of the booster 34 even when the vibration generator 29 is at the maximumly raised position with respect to the cylinder 27. At the lower end of the booster 33a, a horn-shaped tool mounting hole 35 is integrally formed, and the lower end of the booster 33a is equipped with a conditioning tool 36 such as a disc or cup.

On the other hand, a cooling tube 37 through which coolant is circulated therein is installed around the tool mounting hole 35 so as to prevent the tool mounting hole 35 from being overheated during the conditioning operation.

The conditioning tool 36 used in the rotary vibrator 18 of the present invention includes a knife blade type, a diamond bite type, a grooved ceramic type, a needle type, and the like, including general tools used in a conventional CMP apparatus. The basic form of these tools is disc and cup.

Looking at the process of pad conditioning using the pad conditioner of the present invention having such a structure as follows.

First, driving the shank conveying apparatus 17 from the state shown in FIG. 2 lifts the rotary vibrator 18 from the end effector cleaning unit 21, and then drives the swing arm driving motor 15 to swing arm ( By rotating in the counterclockwise direction of 16), as shown in FIG. 3, the rotary vibrator 18 is positioned above the pad 11.

Subsequently, the drive motor 28 and the vibration generator 29 of the rotary vibrator 18 are driven to allow the tool mounting hole 35 and the conditioning tool 36 mounted thereon to perform vertical vibration together with the horizontal rotational movement. Next, the shank transport device 17 is driven to move the rotary oscillator 18 downward so that the conditioning tool 36 contacts the upper surface of the pad 11, and then the swing arm 16 swings on the pad surface. By vibrating and rotating while exercising, conditioning of the pad 11 is achieved.

Such a conditioning operation by the rotary vibrator 18 of the present invention can be performed in-process with the processing of the wafer.

According to the present invention, the slurry is clogged in the air gap of the pad 11 in the process of performing high frequency vibration with the horizontal rotation while the conditioning tool 36 is in contact with the upper surface of the pad 11 by the rotary vibrator 18. Particle components are released from the voids, thereby removing clogging in a short time without abrasion of the pad 11.

When the blockage of the pad is removed as a result of the above conditioning operation or the conditioning time has elapsed for a predetermined time or more, the rotary oscillator 18 is transferred to the end effector cleaning unit 21 to remain in the lower portion of the rotary oscillator 18. Allow removal of the slurry.

(A) to (c) of FIG. 5 are scanning electron micrographs of the pads, (a) for the new pads, and (b) for the preconditioning state of the pads clogged by processing of the wafer. The white circle in the picture shows the clogging.

On the other hand, the photograph of (c) of FIG. 5 is for the pad surface conditioned using the pad conditioner of the present invention with respect to the pad in the state of (b), and (c) is for the pad 5 minutes after the start of conditioning. will be.

As can be seen in FIG. 5, when conditioning through the pad conditioner of the present invention, a surface similar to the new pad can be obtained even after a short time of operation, and of course, clogging when a longer on-conditioning time has elapsed. Removal is almost complete.

As described above, the pad conditioner of the present invention is a new state-of-the-art clogging during wafer processing by rotating and vibrating the rotor 18 in the process and in-process during the conditioning and finely removing the clogging of the pad. Since the pad surface can be secured, the reduction of the processing efficiency of the wafer can be effectively prevented and the excellent uniformity can be achieved over the entire surface of the wafer.

In the present invention, unlike the conventional method of removing the surface layer of the pad by using the electrodeposited diamond disk, the diamond particles or the metal are removed by removing the clogging by contact with the pad by the high frequency vibration of the conditioning tool. There is no risk of scratching or contamination of the wafer due to the dropping of the component particles. In addition, the present invention has a form in which the wear of the pad is extremely small as the wear of the pad is extremely semi-permanent as it takes the form of microscopic removal with a very small amount of wear during conditioning. There is an advantage.

Claims (5)

A swing arm installed so that its outer end moves repeatedly to the top of the polishing pad around the rotational shaft located on one side of the upper part of the CPM apparatus, and then swings repeatedly; Rotating vibrator including a rotating device and a vibration generating device coupled to the end of the swing arm for horizontal rotation and vertical vibration of the conditioning tool and The pad conditioner of the CPM device, characterized in that the outer peripheral surface of the one side is fixed to the end of the swing arm consisting of a shank conveying device for moving the rotating vibrator in the vertical direction. 2. The swing arm of claim 1, wherein the swing arm is reciprocated between the upper end of the pad and the end effector cleaning part located outside the pad mounting surface by a drive motor provided on the rotational shaft, and swings on the pad surface when driving the vibration part. Pad conditioner of a CPM device, characterized in that the conditioning. The rotating device of claim 1, wherein the rotating device of the rotary vibrator includes a driving motor and a connecting rod whose upper end is connected to a motor shaft of the driving motor while the lower end is connected to a vibration generating device. Pad conditioner of the CPM device, characterized in that consisting of a booster coupled to the tool fittings on the lower end. 4. The pad conditioner of claim 3, wherein the vibration generating element is a piezoelectric element type transducer. According to claim 1, wherein the shanghai conveying device is composed of a pneumatic cylinder and a cylinder extending downward of the pneumatic cylinder so that the upper end of the rotary oscillator casing inside the cylinder is fixed to the lower end of the piston rod of the pneumatic cylinder, characterized in that it moves up and down Pad conditioner for CPM units.

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