KR20030077802A - Chemical mechanical polishing apparatus having a polishing head - Google Patents

Abstract

PURPOSE: A CMP(Chemical Mechanical Polishing) equipment having a polishing head is provided to be capable of uniformly pressing a semiconductor wafer when carrying out a CMP process. CONSTITUTION: CMP equipment is provided with a turn table and a polishing head for holding a wafer and pressing the wafer on the turn table. The polishing head includes an upper plate(310) of the head, a carrier(320) located at the back side of the upper plate of the head, a center clamp(330) located at lower portion of the carrier, the first and second inner tube located between the carrier and the center clamp for being connected through the first and second inner tube pressure pipe, respectively, a porous plate(335) having a plurality of holes(336), located at the lower portion of the center clamp, a membrane(340) located at the lower portion of the porous plate for contacting the wafer, and a retainer ring(350) located at the lower edge portion of the carrier.

Description

Chemical mechanical polishing apparatus having a polishing head

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to equipment for manufacturing semiconductor wafers, and more particularly, to equipment for chemical mechanical polishing of surfaces of semiconductor wafers.

In recent years, as semiconductor devices have been highly integrated, wiring structures have been multilayered to increase the surface level between unit cells stacked on a semiconductor substrate, or between cell array regions and peripheral circuit regions. Various wafer planarization methods have been proposed to reduce the surface steps. Chemical Mechanical Polishing apparatus (CMP apparatus) is a planarization equipment of the wafer process surface which is currently widely used. Typically, in the process of planarizing a wafer process surface using a CMP apparatus, the wafer is mounted on a polishing head with its process surface facing the turntable, and the process surface of the wafer is placed on a turntable provided with a polishing pad. . The polishing head provides controllable pressure on the wafer to press the wafer against the polishing pad of the turntable. The polishing head may also rotate to provide additional motion between the wafer and the turntable.

An effective chemical mechanical polishing process is to process substrates of uniform flatness at high polishing rates. Properties such as the uniformity, flatness, and polishing rate of the wafer surface are greatly influenced by the relative speed between the wafer and the polishing pad, and the pressing force of the wafer against the polishing pad. In particular, the polishing rate is higher as the pressing force of the wafer against the polishing pad increases. Thus, when a non-uniform pressing force is applied from the polishing head to the wafer, certain areas of the wafer that are subjected to relatively high pressure will be polished faster than other areas that are subjected to relatively small pressure.

1 is a schematic view showing a polishing head of a conventional chemical mechanical polishing equipment, and FIG. 2 is a cross-sectional view taken along the line II ′ of FIG. 1.

Referring to FIGS. 1 and 2, the conventional polishing head 5 includes a head top plate 10 on which pressure tubes are disposed, a carrier 20 that adsorbs or pressurizes the wafer, and a retainer ring that provides space for supporting the wafer. (30). The pressure tubes disposed inside the head top plate 10 include a main pressure tube 11 for absorbing a wafer or applying pressure to the wafer, a retainer pressure tube 12 for transferring pressure to the retainer ring 30, and an inner tube pressure tube 13. There is this. The central clamp 40 is disposed on the carrier lower surface. The central clamp 40 has a convex portion penetrating the central portion of the carrier 20, the convex portion is connected to the head top plate 10, it is installed so that the vertical movement.

During the polishing of the wafer, gas pressure is applied to the pressure tubes 11, 12, 13. The path of the pressure of the gas applied through the pressure tubes will be briefly described.

First, the pressure of the gas applied through the retainer pressure tube 12 separates the internal clamp 21 interposed between the head upper plate 10 and the carrier 20 from the head upper plate. Then, the pressure of the gas through the retainer pressure tube 12 is a rolling diaphram disposed at the edge of the inner clamp 21 through a space created by the separation of the inner clamp 21 and the head top plate 10. 23). The pressure applied to the rolling diaphragm 23 is transmitted to the retainer ring 30 below the rolling diaphragm 23. The rolling diaphragm 23 is fixed to the head top plate 10 by an external clamp 22. In this way, the retainer ring 30 prevents the wafer from leaving the polishing head 5 during the process.

Next, the pressure of the gas applied through the inner tube pressure tube 13 is an inner tube disposed below the carrier 20 through an extension of the inner tube pressure tube 13 disposed inside the carrier 20. 24) Inflate One side of the inner tube pressure tube 13 is in contact with the inner tube 24 to communicate. The inner tube 24 has a ring shape, and applies pressure to the edge of the wafer during the polishing process to prevent the wafer from being separated during the process.

Finally, the pressure of the gas delivered through the main pressure pipe 11 is a porous plate disposed below the central clamp 40 through an extension of the main pressure pipe 11 disposed in the convex portion of the central clamp 40. It is transmitted to the space interposed between the perforated plate 41 and the central clamp 40. The perforated plate 41 has perforated plate holes 42, which are means for transmitting suction or pressure. The pressure of the gas applied to the main pressure pipe 11 expands the membrane 45 made of a flexible material on the lower surface of the porous plate 41 through the porous plate hole 42. The membrane 45 is fixed by a membrane clamp 46 disposed on the upper surface of the edge of the porous plate 41. One end is interposed between the retainer ring 30 and the carrier 20, and the other end is interposed between the upper surface of the membrane clamp 46 and the flexure clamp 48 by a flexure 47. The pressures of the pressure tubes 11, 12 and 13 are prevented from leaking to the outside.

As the membrane 45 is expanded, pressure is applied to the wafer to polish the process surface of the wafer. However, the pressure applied through the main pressure pipe 11 is intensively applied to the central portion of the membrane 45 during the polishing process, so that the pressure may be weakened toward the edge from the central portion of the wafer. For this reason, the uniformity of a wafer falls in the grinding | polishing process. The pressure by the retaining pressure tube 12 does not directly affect the wafer. In addition, the pressure by the inner tube pressure tube 13 affects only the edge of the wafer, making it difficult to control the pressure for the overall uniformity of the wafer.

An object of the present invention is to provide a chemical mechanical polishing equipment that can apply a uniform pressure to the front surface of a semiconductor wafer during the polishing process.

1 is a schematic view showing a polishing head of a conventional chemical mechanical polishing equipment.

FIG. 2 is a cross-sectional view taken along the line II ′ of FIG. 1.

Figure 3 is a schematic diagram showing a chemical mechanical polishing equipment according to an embodiment of the present invention.

4 is a schematic diagram illustrating a polishing head of a chemical mechanical polishing apparatus according to an embodiment of the present invention.

FIG. 5 is a cross-sectional view taken along II-II 'of FIG. 4.

Figure 6 is a schematic diagram for explaining a polishing process by the chemical mechanical polishing equipment according to an embodiment of the present invention.

To provide a chemical mechanical polishing equipment for solving the above technical problem. The chemical mechanical polishing equipment according to the present invention includes a turn table having a polishing pad mounted on an upper surface thereof, and a polishing head for holding the wafer and pressing the wafer onto the turn table. The polishing head is characterized in that it has means for applying pressure to the part of the wafer during the polishing process.

Specifically, the polishing head includes a head top plate having a main pressure tube, at least one auxiliary pressure tube, a first inner tube pressure tube and a second inner tube pressure tube therein. On the bottom surface of the head upper plate, a carrier having internal portions of the auxiliary pressure tubes and respective extensions of the first and second inner tube pressure tubes is disposed. A central clamp is disposed below the carrier, and the central clamp has a convex portion. An extension of the main pressure pipe is disposed inside the convex portion of the central clamp, and is connected to the central portion of the head upper plate by vertical movement through the central portion of the carrier. First and second inner tubes are interposed between the carrier and the central clamp to communicate with the first and second inner tube pressure tubes, respectively. One side of the auxiliary pressure tubes communicates with a space between the first inner tube and the second inner tube. A perforated plate having perforated plate holes is disposed under the central clamp. A membrane in surface contact with the wafer is disposed on the bottom of the porous plate. A ring-shaped retainer ring is located on the bottom edge of the carrier edge.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced herein are provided to ensure that the disclosed subject matter is thorough and complete, and that the spirit of the invention will be fully conveyed to those skilled in the art. Portions denoted by like reference numerals denote like elements throughout the specification.

Figure 3 is a schematic diagram showing a chemical mechanical polishing equipment according to an embodiment of the present invention.

Referring to FIG. 3, the chemical mechanical polishing equipment 200 according to the present invention has a polishing station 220 and a polishing head assembly 230 installed with a rotatable turntable 210 to which a polishing pad 211 is attached.

The turn table 210 is connected to a means (not shown) for rotating the turn table and rotates during the polishing process. The polishing pad 211 may be a composite material having a rough polishing surface. The polishing station 220 may include conventional pad conditioning means 212 and reaction reagents (e.g., deionized water for oxidative polishing), friction particles (e.g., silicon dioxide for oxidative polishing), and chemical reaction catalysts (e.g., hydroxide for oxidizing polishing). Slurry supply means 213 for supplying a slurry containing potassium) to the surface of the polishing pad.

The polishing head assembly 230 includes a polishing head 300, a drive shaft 231, and a motor 232. The polishing head 300 holds the wafer against the polishing pad 211 and evenly distributes the downward pressure to the backside of the wafer. The polishing head 300 may be rotated by a drive shaft 231 connected to the motor 232.

The polishing head 300 may be connected to at least one fluid supply channel capable of applying gas pressure or vacuum pressure. Pumps are respectively connected to these fluid supply channels.

4 is a schematic view showing a polishing head of a chemical mechanical polishing apparatus according to an embodiment of the present invention, and FIG. 5 is a cross-sectional view taken along II-II 'of FIG.

4 and 5, the polishing head 300 according to the embodiment of the present invention includes a head upper plate 310, a carrier 320, a central clamp 330, a porous plate 335, and a membrane 340. Include.

The main pressure pipe 311, the auxiliary pressure pipes 312, the retainer pressure pipe 313, the first inner tube pressure pipe 314, and the second inner tube pressure pipe 315 are disposed in the head upper plate 310. The main pressure pipe 311, the auxiliary pressure pipes 312, and the first and second inner tube pressure pipes 314 and 315 may be made of a flexible material to contract or extend in the longitudinal direction. For example, it is preferable that it consists of rubber | gum. At least one auxiliary pressure tube 312 is disposed, and in the case of the plurality of auxiliary pressure tubes 312, all of the auxiliary pressure tubes 312 are disposed at the same radius in the center of the head upper plate 310. In this example, four auxiliary pressure tubes 312 are shown.

An external clamp 322, a rolling diaphragm 323, and an internal clamp 321 are horizontally interposed between the head upper plate 310 and the carrier 320. The outer clamp 322 is disposed in contact with the lower surface of the edge of the head upper plate 310, the inner clamp 321 is disposed closer to the center of the head upper plate 310 than the outer clamp 322. In contact with the lower surface of the head upper plate 310, it is not fixed. One end of the rolling diaphragm 323 is in contact with and fixed to one side of the outer clamp 322, and the other end of the rolling diaphragm 323 is in contact with and fixed to one side of the inner clamp 321. The rolling diaphragm 323 is made of a flexible material and is elastic, and prevents the pressure or vacuum pressure of the gas applied to the inside of the polishing head 300 from leaking. The rolling diaphragm 323 is preferably formed of, for example, rubber.

The internal clamp 321 is always in contact with the top surface of the carrier 320 is fixed. The upper surface of the inner clamp 321 may be contacted or spaced apart from the lower surface of the head upper plate 310. That is, when the wafer is adsorbed to the polishing head 300, the lower surface of the head upper plate 310 and the upper surface of the internal clamp 321 are in contact with each other, on the contrary, adsorbed to the polishing head 300. When the wafer is brought into close contact with the polishing pad 211 and pressed against the polishing pad, an upper surface of the inner clamp 321 and a lower surface of the head upper plate 310 are spaced apart from each other.

The external clamp 322 is always in contact with and fixed to the head top plate 310. Alternatively, the carrier 320 may be contacted or spaced apart from the carrier 320. That is, when the wafer is bonded to the polishing head 300, the wafer is in contact with the upper surface of the carrier 320, and conversely, the wafer adsorbed to the polishing head 300 is brought into close contact with the polishing pad 211. When pressure is applied against the polishing pad, the lower surface of the outer clamp 322 and the upper surface of the carrier 320 are spaced apart.

In the carrier 320, first and second inner tube pressure tubes 314 and 315 disposed inside the head upper plate 310 and extensions of the auxiliary pressure tubes 312 are disposed.

The center clamp 330 is disposed below the carrier 320. A convex portion is disposed in the center of the central clamp 330. The convex portion penetrates through the central portion of the carrier 320 and is connected to the central portion of the head upper plate 310. At this time, the central clamp 330 is connected to allow the vertical movement. An extension of the main pressure pipe 311 disposed in the center of the head upper plate 310 is disposed inside the convex portion of the central clamp 330.

A first inner tube 331 and a second inner tube 332 are interposed between the carrier 320 and the central clamp 330. The first and second inner tubes 331 and 332 form a ring around the convex portion of the central clamp 330. The radius of the second inner tube 332 is smaller than the radius of the first inner tube 331. The first inner tube 331 is preferably disposed on the upper surface of the edge of the central clamp 330. The first and second inner tubes 331 and 332 are made of a flexible material. For example, it is preferable to form with rubber. The first and second inner tubes 331, 332 communicate with the first and second inner tube pressure tubes 314, 315, respectively. Each of the first and second inner tubes 331 and 332 may be disposed inside and fixed to a guide groove k formed in the lower surface of the carrier. One side of the auxiliary pressure pipes 312 formed inside the carrier 320 is disposed on a lower surface of the carrier 320 between the first and second inner tubes 331 and 332. Accordingly, the auxiliary pressure tube 312 and the empty space formed of the first and second inner tubes 331 and 332, the lower surface of the carrier 320, and the upper surface of the central clamp 330 communicate with each other. Alternatively, the positions of the second inner tube 332 and the second main pressure tube 312 may be changed. (Not shown) In this case, the second pressure tube may include the second inner tube 332 and the lower portion of the carrier. Surface, the lower surface of the central clamp 330 and the empty space consisting of the convex portion of the central clamp 330.

A retainer ring 350 is disposed on an edge lower surface of the carrier 320. The retainer ring 350 provides a space for supporting the wafer.

The porous plate 335 is disposed below the central clamp 330. The perforated plate is provided with perforated plate holes 336 through which the pressure or vacuum pressure of the gas flowing from the first main pressure pipe can pass. The lower surface of the porous plate 335 is disposed a membrane 340 in direct surface contact with the back of the wafer. The membrane 340 is made of a flexible material. For example, it is preferable that it consists of rubber | gum.

An end of the membrane 340 and a membrane clamp 341 are sequentially interposed between the edge of the central clamp 330 and the edge of the porous plate 335. That is, the end of the membrane 340 is fixed by being interposed at the edge of the membrane clamp 341 and the porous plate 335. An end of the membrane clamp 341 and the membrane 340 is a chamber A, which is an empty space, between the central clamp 330 and the porous plate 335. The gas applied through the main pressure pipe 311 through the chamber A may be delivered to the front surface of the membrane 340 through the porous plate holes 336 formed in the porous plate 335 to apply pressure. have.

One end of the flexure 342 made of a flexible material is interposed between edges of the membrane clamp 341 and the central clamp 330, and the other end of the flexure 342 is formed of the carrier 320 and the carrier. Interposed between the retainer ring 350 is fixed. The flexure 342 serves to seal the pressure or vacuum pressure of the gas applied to the inside of the polishing head 300 so as not to leak. The flexure 342 is preferably formed of a flexible material, such as rubber.

Figure 6 is a schematic diagram for explaining a polishing process by the chemical mechanical polishing equipment according to an embodiment of the present invention.

Referring to FIG. 6, the back surface of the wafer 100 having a process surface is adsorbed to the membrane 340 provided in the polishing head 300 and moved to the turntable 210 having the polishing pad 211. At this time, the vacuum pressure adsorbing the wafer 100 is transmitted only through the main pressure pipe 311 disposed in the polishing head 300.

The wafer 100 moved to the turntable 210 is disposed so that a process surface is in contact with the polishing pad 211, and then applies a force facing the polishing pad 211 to the inside of the polishing head 300. To introduce gas. In this case, it is preferable to use nitrogen (N 2) as the gas to be introduced.

The force applied to each part of the wafer 100 due to the inflow of the gas will be described.

First, the gas introduced into the retainer pressure tube 313 spaces the internal clamp 321 disposed on the upper surface of the carrier 320 from the head upper plate 310. Thus, the gas introduced into the retainer pressure tube 313 is delivered to the rolling diaphragm 323 through a space formed between the head top plate 310 and the internal clamp 321, the rolling diaphragm 323 Pressure is applied to the retainer ring 350 on the lower side. As a result, the retainer ring 350 prevents the wafer 100 from escaping out of the polishing head 300. The pressure of the gas flowing into the retainer pressure pipe 313 is applied to other pressure pipes, that is, the main pressure pipe 311, the auxiliary pressure pipes 312, the first inner tube pressure pipe 314, and the second inner tube pressure pipe 315. The highest.

Secondly, the gas flowing into the main pressure tube 311 flows into the chamber A, and the gas flowing into the chamber A forms the porous plate holes 336 disposed in the porous plate 335. The membrane 340 is expanded through. The front surface of the wafer 100 is pressed by the expanded membrane 340. However, the gas flowing through the main pressure tube 311 has a high pressure applied to the central portion of the membrane 340, thereby allowing centralized control of the gas, that is, the K region of the wafer 100.

Third, the gas flowing into the second inner tube pressure tube 315 flows into the second inner tube 332 to expand the second inner tube 332. The expanded second inner tube 332 may control the pressure applied above the L region of the wafer 100 by applying a force to a portion of the central clamp 330 in contact with the bottom surface thereof. The L region has a ring shape adjacent to the K region.

Fourth, the gas flowing into the auxiliary pressure tubes 312 may be a lower surface of the carrier 320, an upper surface of the central clamp 330, the second inner tube 332 and the first inner tube 331. The pressure applied to the M region of the wafer 100 can be controlled by applying a force to a portion of the central clamp 330 which flows into the space formed by the bottom surface of the central clamp 330. The M region has a larger radius than the L region in a ring shape adjacent to the L region.

Fifth, the gas flowing into the first inner tube pressure tube 314 flows into the first inner tube 331 and expands it. The expanded first inner tube 331 may control a pressure applied to an N region, which is an edge of the wafer 100, by applying a force to a portion of the central clamp 330 disposed below the expanded first inner tube 331. . The N region is adjacent to the M region and forms a ring. The radius of the M area is the largest for the other areas.

As a result, in the polishing process, the pressure applied to the wafer 100 against the polishing pad 211 is applied to the main pressure tube 311, the auxiliary pressure tube 312, the first inner tube 331, and the second inner portion. The tube 332 can be subdivided. For this reason, the process surface of the wafer 100 can be polished more uniformly.

Thereafter, the polishing process is performed by rotating the polishing head 300 and the turntable 210.

As described above, in the embodiment of the present invention, the pressure applied to the polishing head 300 is applied to the main pressure pipe 311, the auxiliary pressure pipes 312, the second inner tube 332, and the first inner tube 331. Broken down into. However, the present invention is not limited thereto, and the wafer may be installed by installing another auxiliary pressure tubes having a different radius from the auxiliary pressure tubes 312 or another inner tube having a different radius from the first and second inner tubes 331 and 332. The pressure exerted on 100 can be further subdivided (not shown).

As described above, the present invention provides a chemical mechanical polishing apparatus for increasing the uniformity of the polishing process surface of the wafer by subdividing the pressure applied to the wafer when the wafer having the process surface is subjected to the chemical mechanical polishing process.

Claims (10)

In equipment for polishing wafers. A turn table having a polishing pad mounted on an upper surface thereof; And a polishing head for holding a wafer and forcing the wafer onto a turntable, wherein the polishing head has means for applying a partial pressure to the wafer during the polishing process. The method of claim 1, The polishing head is. A head top plate having a main pressure pipe, at least one auxiliary pressure pipe, a first inner tube pressure pipe, and a second inner tube pressure pipe therein; A carrier having a bottom portion of the head upper plate, each extending portion of the auxiliary pressure tubes and the first and second inner tube pressure tubes therein; A central clamp disposed on the lower surface of the carrier and having a convex portion, the convex portion having an extension portion of the main pressure tube disposed therein and connected to a central portion of the head upper plate through a central portion of the carrier to vertically move; First and second inner tubes interposed between the carrier and the central clamp and communicating with the first and second inner tube pressure tubes, respectively; A perforated plate disposed under the central clamp and provided with perforated plate holes; A membrane disposed on the bottom surface of the porous plate and in surface contact with the wafer; And And a ring-shaped retainer ring disposed on the carrier edge lower surface, wherein one side of the auxiliary pressure tubes communicates with a space between the first inner tube and the second inner tube. The method of claim 2, And the main pressure tube, the auxiliary pressure tubes, the first inner tube pressure tube, the second inner tube pressure tube, the first inner tube, the second inner tube and the membrane are made of rubber. The method of claim 2, And a retainer pressure tube inside the head top plate. The method of claim 2, Further comprising an inner clamp, an outer clamp and a rolling diaphragm interposed between the head top plate and the carrier, wherein the inner clamp, the outer clamp and the rolling diaphragm are interposed horizontally with respect to the head top plate, and The lower surface of the inner clamp is fixed in contact, the lower surface of the head upper edge and the upper surface of the outer clamp is fixed in contact, one end of the rolling diaphragm is fixed in contact with one side of the inner clamp and the rolling And the other end of the diaphragm is fixed in contact with one side of the external clamp. The method of claim 5, And the rolling diaphragm is made of rubber. The method of claim 2, And the first and second inner tubes are disposed inside a guide groove disposed on the carrier lower surface. The method of claim 2, And a membrane clamp interposed between an edge of the central clamp and an edge of the porous plate, wherein an end of the membrane is interposed between the membrane clamp and the edge of the porous plate. The method of claim 8, And a flexure made of a flexible material, wherein one end of the flexure is interposed between the edge of the central clamp and the membrane clamp, and the other end of the flexure is between the edge of the carrier and the retaining ring. Chemical mechanical polishing equipment, characterized in that interposed. The method of claim 9, And said flexure is made of rubber.