KR20040040740A - Apparatus for supplying a slurry - Google Patents

Abstract

PURPOSE: A slurry supply apparatus is provided to be capable of preventing generation of a pulsation phenomenon in supplying slurry and uniformly supplying the slurry. CONSTITUTION: A slurry supply apparatus(100) is provided with a circulation pipe(110) for circulating slurry, a cylinder(120) connected with the circulation pipe for storing the slurry, and the first piston(124) for dividing the inner portion of the cylinder into the first region connected with the circulation pipe and the second region connected with a supply pipe. At this time, the first piston includes the first through hole for connecting the first region with the second region. The slurry supply apparatus further includes the second piston(126) connected with one side of the first piston for switching the first through hole and a driving part(150) connected with the first and second piston for controlling the first and second piston. Preferably, the first and second piston have the same shape with each other.

Description

Apparatus for supplying a slurry}

The present invention relates to an apparatus for feeding a slurry. More specifically, the present invention relates to an apparatus for supplying a slurry used in a chemical mechanical polishing process of a semiconductor substrate at a constant flow rate.

Recently, the manufacturing technology of semiconductor devices has been developed to improve the degree of integration, reliability, response speed, etc. in order to meet various needs of consumers. In general, semiconductor devices are manufactured by performing unit processes such as film formation, photolithography, etching, ion implantation and polishing processes. Among the unit processes, the polishing process has emerged as an important process technology for improving the integration degree of a semiconductor device and improving the structural and electrical reliability of the semiconductor device. Recently, a chemical mechanical polishing process for flattening a semiconductor substrate by chemical reaction of a slurry and a film formed on the semiconductor substrate and a mechanical friction force between the polishing pad and the film formed on the semiconductor substrate is mainly used.

The apparatus for performing the chemical mechanical polishing process generally includes a polishing pad attached to a rotating table, a polishing head for holding and rotating a semiconductor substrate, a slurry supply portion for supplying a slurry between the polishing pad and the semiconductor substrate, and a surface of the polishing pad. And a polishing pad conditioner or the like for improving the condition. A polishing end point detection device is also provided for determining the polishing end point of the chemical mechanical polishing process.

The slurry may be referred to as a medium for transferring abrasive particles and chemicals to or from the surface of the semiconductor substrate as a workpiece. In a chemical mechanical polishing process using the slurry, the polishing rate is an important variable, and the polishing rate depends on the slurry used. The hardness of the abrasive grains contained in the slurry has a hardness similar to that of the semiconductor substrate and performs mechanical polishing. One example of an apparatus for feeding the slurry is disclosed in US Pat. Nos. 6,319,099 (issued to Tanoue, et al.) And 6,402,599 (issued to Crevasse, et al.).

Typically, the abrasive particles contained in the slurry consist of primary particles having a particle diameter of approximately 130 to 170 nm. However, in the slurry in suspension, the abrasive particles tend to agglomerate with each other, thereby forming clumps of secondary particles having a relatively large particle size. The tendency of the abrasive particles to agglomerate in the slurry is more pronounced when the slurry is not flowing and stagnant, and the agglomerates formed by agglomeration of the abrasive particles vary in size from about 0.1 to 30 μm depending on the primary particle size of the abrasive particles. Has

Thus, the slurry is continuously circulated from the storage vessel through the circulation piping to prevent agglomeration of the abrasive particles. At this time, most of the diaphragm pump (diaphragm pump) or using a method of pressurizing the nitrogen (N ₂ ) gas to the vessel connected to the circulation pipe, and a tube peristaltic pump (peristaltic pump) is used to control the final supply. The problem of the slurry supply method as described above causes a pulsation of the slurry depending on the stroke of the diaphragm pump or the rotational speed of the tube-linked pump, and in particular, the upper limit of the set slurry supply amount when a small amount of slurry is supplied. Above or below the limit or the lower limit (lower limit) occurs, it becomes difficult to supply a fixed amount of slurry. Such a non-uniform slurry supply lowers the polishing uniformity, especially in the case of a slurry or a small supply of slurry having a small content of abrasive particles, the retainer ring is broken, the polishing uniformity of the semiconductor substrate is reduced, and the wafer surface is damaged. The same process failure occurs. In order to solve the above problems, a damper or pumpless method has been introduced, but it does not completely eliminate pulsation.

An object of the present invention for solving the above problems is to provide a slurry supply device that prevents the pulsation phenomenon of the slurry supply in the chemical mechanical polishing process of the semiconductor substrate, it is possible to supply the quantitative supply of the slurry.

1 is a schematic diagram illustrating a slurry supply apparatus according to an embodiment of the present invention.

FIG. 2 is a block diagram for explaining an overall configuration of a slurry supply unit including the slurry supply device shown in FIG. 1.

3 is an exploded perspective cross-sectional view for explaining the piston and the drive shaft shown in FIG.

4 is a schematic diagram illustrating an example of a driving unit illustrated in FIG. 1.

5 is a schematic diagram illustrating another example of the driving unit illustrated in FIG. 1.

6A and 6B are views for explaining a method for supplying a slurry contained in a cylinder to a polishing pad.

Explanation of symbols on the main parts of the drawings

10 polishing pad 20 polishing head

30: rotation plate 40: rotation axis

100: slurry supply device 110: circulation pipe

112 storage container 114 pump

116: filter 118: circulation valve

120: cylinder 120a: first region

120b: second region 124: first piston

126: second piston 128: first drive shaft

130: second drive shaft 140: supply piping

142: supply valve 150: drive unit

W: semiconductor substrate

The present invention for achieving the above object, the circulation pipe for circulating the slurry, the cylinder connected to the circulation pipe and accommodates the slurry, the first region connected to the circulation pipe and the polishing of the semiconductor substrate A first piston having a first through hole for dividing an inner space of the cylinder into a second region connected to a supply pipe for supplying the slurry onto a polishing pad for communicating with the slurry, and for communicating the first region with the second region; And a second through hole that is in close contact with one side of the first piston, and has a second through hole corresponding to the first through hole, the second piston for opening and closing the first through hole by rotation, and the first piston and the first hole. It is connected to the second piston, the second piston is rotated to open and close the first through hole, while the first through hole is opened to move the first piston and the second piston in the direction of the first region. Moving the slurry contained in the first region to the second region, and moving the first piston and the second piston in the direction of the second region while the first through hole is closed, thereby moving the slurry onto the polishing pad. It provides a slurry supply device comprising a drive for supplying.

The slurry contained in the second region is constantly supplied onto the polishing pad as the first piston and the second piston move. Therefore, the pulsation phenomenon of the slurry supplied onto the polishing pad is prevented, and the quantitative supply of the slurry is possible.

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

1 is a schematic diagram illustrating a slurry supply apparatus according to an embodiment of the present invention.

1, the slurry supply apparatus 100 according to an embodiment of the present invention is connected to the circulation pipe 110 for circulating the slurry, the cylinder 120 for temporarily storing the slurry connected to the circulation pipe 110 And a piston (122) installed inside the cylinder (120) for supplying the slurry to the supply pipe (140) for supplying the slurry on the polishing pad (10) for polishing the semiconductor substrate (W); And, the driving unit 150 for providing a driving force to the piston (122).

The circulation pipe 110 includes a cylinder 120, a slurry storage container 112 for storing the slurry, and a pump 114 for applying pressure to circulate the slurry stored in the storage container 112 along the circulation pipe 110. ), A filter 116 for filtering abrasive particles having a predetermined size or more among abrasive particles included in the slurry circulating through the circulation pipe 110, and a circulation valve 118 for opening and closing the circulation pipe 110. . At this time, a diaphragm pump or a tube-linked pump may be used as the pump 114.

The supply pipe 140 is provided with a supply valve 142 for adjusting the supply cycle and time of the slurry, the nozzle 144 for supplying the slurry onto the polishing pad 10 at the end of the supply pipe 140. Is connected.

The semiconductor substrate W is held and rotated by the polishing head 20, and the polishing head 20 holds the semiconductor substrate W by using a vacuum pressure, and is installed to surround a peripheral portion of the semiconductor substrate W. A retainer ring (not shown) is provided to prevent the semiconductor substrate W from being separated and to uniformly adhere the semiconductor substrate W to the polishing pad 10. The polishing pad 10 is attached on the rotary surface plate 30, and the rotary surface plate 30 is rotated by the rotational force transmitted through the lower rotation shaft 40.

The inside of the cylinder 120 has a first region 120a connected to the circulation pipe 110 and a second region 120b connected to the supply pipe 140 by the first piston 124 and the second piston 126. ). The first piston 124 is adjacent to the second region 120b and the second piston 126 is adjacent to the first region 120a. The first piston 124 and the second piston 126 are in close contact with each other, the first piston 124 is connected to the first drive shaft 128, the second piston 126 and the second drive shaft 130 It is connected.

The first piston 124 has a disk shape, and a first through hole 124a for passing the slurry is formed. The second piston 126 has the same shape as the first piston 124, and a second through hole 126a corresponding to the first through hole 124a is formed.

The first drive shaft 128 connected to the central portion of the first piston 124 penetrates the central portion of the second piston 126 and passes through the first region 120a of the cylinder 120. It extends outside. The second driving shaft 130 connected to the central portion of the second piston 126 is a hollow shaft, and the first driving shaft 128 extends through the inside of the second driving shaft 130. The first driving shaft 128 and the second driving shaft 130 extend outside the cylinder 120 and are connected to the driving unit 150.

Although not shown in detail, the driving unit 150 rotates the second piston 126 to open and close the first through hole 124a, and opens the first piston 124 and the second piston 126 of the cylinder 120. Reciprocate in the long axis direction.

When the second piston 126 is rotated to coincide with the first through hole 124a of the first piston 124 and the second through hole 126a of the second piston 126, the first region of the cylinder 120 120a and the second region 120b communicate with each other, and the slurry contained in the first region 120a is moved to the second region 120b through the circulation pipe 110. While the first through hole 124a is opened by the second through hole 126b, the driving unit 150 moves the first piston 124 and the second piston 126 in the direction of the first region 120a. The slurry is sufficiently accommodated in the two regions 120b.

On the contrary, when the first piston 126a is closed by rotating the second piston 126, the first region 120a and the second region 120b are completely blocked. Therefore, the pulsation phenomenon of the slurry generated by the operation of the pump 114 in the circulation pipe 110 does not affect the slurry contained in the second region 120b. The driving unit 150 moves the first piston 124 and the second piston 126 at a constant speed in the direction of the second region 120b to transfer the slurry contained in the second region 120b through the supply pipe 140. The substrate W is supplied onto a polishing pad 10 for polishing.

In this case, the internal volume of the cylinder 120 may be changed depending on the number of semiconductor substrates W to be polished and the type of film formed on the semiconductor substrate W. FIG. In addition, when the chemical mechanical polishing process of the semiconductor substrate W is completed by a predetermined amount, the first piston 124 and the second piston 126 are moved in the direction of the first region 120a to form the second region 120b. The slurry can be accommodated again. In contrast, the movement distance of the first piston 124 and the second piston 126 may be preset, and thus the movement of the first piston 124 and the second piston 126 may be controlled.

FIG. 2 is a block diagram for explaining an overall configuration of a slurry supply unit including the slurry supply device shown in FIG. 1.

Referring to FIG. 2, the illustrated slurry supply unit 60 is a central control unit for controlling the fluid storage device 70, the slurry mixing device 80, the slurry supply device 100, and the slurry supply unit 60 as a whole. 90, and serves to quantitatively supply slurry at a constant flow rate on the polishing pad 10 (see FIG. 1) for polishing the semiconductor substrate W. FIG.

The fluid storage device 60 includes a slurry stock solution storage tank 72 for storing slurry stock solution, a pure water storage tank 74 for storing pure water, a pH control liquid storage tank 76 for storing a pH adjusting liquid, and a surface active agent. It consists of a surface active agent storage tank (78) for storing, and serves to store and supply various materials that make up the slurry.

The slurry mixing device 80 receives various slurry composition materials stored in the fluid storage device 70 and mixes the slurry appropriately with each semiconductor substrate W to be polished, and supplies the slurry to the slurry supply device 100. Do it.

The slurry supply device 100 continuously circulates the slurry to prevent agglomeration of the slurry, and uniformly supplies the slurry onto the polishing pad 10 by using the cylinder 120 (see FIG. 1) and the driving unit 150. .

3 is an exploded perspective cross-sectional view for explaining the piston and the drive shaft shown in FIG.

Referring to FIG. 3, a first driving shaft 128 connected to the driving unit 150 (see FIG. 1) is connected to one central portion of the first piston 124. The second driving shaft 130 connected to the driving unit 150 is connected to one central portion of the second piston 126. The second driving shaft 130 is a hollow shaft, and the first driving shaft 128 is connected to the driving unit 150 by passing through the central portion of the second piston 126 and the second driving shaft 130.

The first piston 124 has a disk shape, and the second piston 126 has the same shape as the first piston 124. A first through hole 124a is formed in the first piston 124, and a second through hole 126a is formed in the second piston 126. It is preferable that the shape and size of the first through hole 124a and the second through hole 126a are the same. As shown, although the first through hole 124a and the second through hole 126a are formed in an elliptic shape, there is no limitation on the shape of the first through hole 124a and the second through hole 126a. It can be formed in various ways.

A seal for preventing the slurry from leaking between the inner wall of the cylinder 120 (see FIG. 1) and the first piston 124 and the second piston 126 at the peripheral portion of the first piston 124 and the second piston 126. First annular grooves 124b and second annular grooves 126b for mounting members (not shown) are formed, respectively.

The first piston 124 and the second piston 126 are in close contact with each other inside the cylinder 120, in order to prevent the leakage of the close contact with the surface of the first piston 124 and the second piston 126 It must be very high. Therefore, the surfaces of the first piston 124 and the second piston 126 must be processed very precisely.

4 is a schematic diagram illustrating an example of a driving unit illustrated in FIG. 1.

Referring to FIG. 4, the driving unit 150a rotates the first driving force and the second piston 126 to linearly reciprocate the first piston 124 (see FIG. 1) and the second piston 126 (see FIG. 1). It must provide all the second driving force to make it work. As shown, the driving unit 150a includes a hydraulic cylinder 152 for providing a first driving force and a motor 154 for providing a second driving force. Here, the hydraulic cylinder 152 providing the first driving force may be replaced with a pneumatic cylinder.

A bracket 158 for supporting the motor 154 is connected to an end of the piston rod 156 of the hydraulic cylinder 152, and the first drive shaft 128 penetrates through the rotation shaft of the motor 154. 158, and the second drive shaft 130 is connected to the rotation shaft of the motor 154 by the coupling 160. At this time, the rotation axis of the motor 154 is a hollow shaft.

As shown, although the driving unit 150a is schematically configured using the hydraulic cylinder 152 and the motor 154, the reciprocating motion is performed by the hydraulic cylinder 152 and the reducer for reducing the rotational speed of the motor 154. A guide for guiding the bracket 158 may be further installed.

At this time, since the supply flow rate of the slurry is determined by the moving speed of the first piston 124 and the second piston 126, precise control of the moving speed of the first piston 124 and the second piston 126 should be performed. do. The moving speed of the first piston 124 and the second piston 126 as described above is performed by the central control unit 90 (see FIG. 2).

5 is a schematic diagram illustrating another example of the driving unit illustrated in FIG. 1.

Referring to FIG. 5, the driving unit 150b may include a first motor 170 that provides a first driving force for linearly reciprocating a first piston 124 (see FIG. 1) and a second piston 126 (see FIG. 2). And a second motor 172 that provides a second driving force for rotating the second piston 126. The rotating shaft of the first motor 172 is connected to a ball screw (not shown), and the ball screw is embedded in the ball guide 174. The ball block 176 is coupled to the ball guide 174, and a bracket 178 for installing the second motor 172 is installed in the ball block 176. Since the ball screw, the ball guide 174 and the ball block 176 are variously known, a detailed description thereof will be omitted.

4 and 5 illustrate two examples for providing the first driving force and the second driving force, but the present invention is not limited to the configuration of the driving units 150a and 150b as described above. That is, since the configuration of the driving unit 150 that can provide the first driving force and the second driving force is variously known, various modifications are possible.

6A and 6B are views for explaining a method for supplying a slurry contained in a cylinder to a polishing pad.

6A and 6B, initially, the slurry flowing through the circulation pipe 110 is temporarily accommodated in the first region 120a of the cylinder 120. The slurry accommodated in the first region 120a forms the first through hole 124a and the second through hole 126a by moving in the direction of the first region 120a of the first piston 124 and the second piston 126. It is accommodated in the second area 120b. At this time, the first through-hole 124a and the second through-hole 126a are in a matched state by the driving unit 150 (see FIG. 1), and the supply valve 142 of the slurry supply pipe 140 is closed. It is a state.

Subsequently, when the second piston 126 rotates to close the first through hole 124a, the supply valve 142 of the slurry supply pipe 140 is opened to open the first piston 124 and the second piston 126. The slurry is supplied to the polishing pad 10 for polishing the semiconductor substrate W by moving in the direction of the second region 120b. At this time, the pulsation phenomenon of the slurry by the pumping operation of the slurry circulation pipe 110 is not transmitted to the slurry passing through the slurry supply pipe 140. This is because the first region 120a and the second region 120b of the cylinder 120 are completely blocked by the first piston 124 and the second piston 126.

When the chemical mechanical polishing process for the predetermined quantity of semiconductor substrates W is finished, the supply valve 142 is blocked, and the driving unit 150 rotates the second piston 126 to make the first piston 124 of the first piston 124. 1 Open the through hole 124a. Subsequently, the first piston 124 and the second piston 126 are moved in the direction of the first region 120a to accommodate the slurry in the second region 120b.

In this case, the movement period of the first piston 124 and the second piston 126 may be determined according to the processing quantity of the semiconductor substrate W, and may be determined by the movement distance of the first piston 124 and the second piston 126. It may be determined accordingly. That is, since the amount of processing of the semiconductor substrate W and the supply amount of the slurry have an organic relationship with each other, the volume of the cylinder 120, the first piston 124, and the second piston 126 are considered in consideration of the efficiency of the chemical mechanical polishing process. It is possible to determine the moving period and the moving speed of.

According to the present invention as described above, the slurry for chemical mechanical polishing is supplied onto the polishing pad from the second region of the cylinder completely blocked by the piston from the first region of the cylinder connected with the slurry circulation pipe.

Therefore, the pulsation phenomenon of the slurry due to the pump operation for circulation of the slurry is not transmitted to the slurry supplied onto the polishing pad. This improves the polishing uniformity of the semiconductor substrate and reduces the occurrence of defects such as surface scratches of the semiconductor substrate. In addition, the life of the retainer ring of the polishing head is increased.

Although described above with reference to a preferred embodiment of the present invention, those skilled in the art will be variously modified and changed within the scope of the invention without departing from the spirit and scope of the invention described in the claims below I can understand that you can.

Claims (4)

Circulation piping for circulating the slurry; A cylinder connected to the circulation pipe to receive the slurry; The internal space of the cylinder is divided into a first region connected to the circulation pipe and a second region connected to a supply pipe for supplying the slurry onto a polishing pad for polishing a semiconductor substrate. A first piston having a first through hole communicating with the second region; A second piston in close contact with one side of the first piston and having a second through hole corresponding to the first through hole, the second piston for opening and closing the first through hole by rotation; And It is connected to the first piston and the second piston, the second piston is rotated to open and close the first through hole, while the first through hole is opened, the first piston and the second piston in the direction of the first region Moving the slurry contained in the first region to the second region, and moving the first piston and the second piston in the direction of the second region while the first through hole is closed, thereby moving the slurry onto the semiconductor substrate. Slurry supply apparatus comprising a drive for supplying. The slurry supply apparatus of claim 1, wherein the first piston and the second piston have the same shape. According to claim 1, Storage container connected to the slurry circulation pipe, for storing the slurry; A pump installed in the circulation pipe to apply pressure to circulate the slurry; A filter installed in the circulation pipe to filter abrasive particles having a predetermined size or more among abrasive particles contained in the slurry; And Slurry supply apparatus further comprises a circulation valve for opening and closing the circulation pipe. The slurry supply apparatus of claim 1, further comprising a supply valve installed in the supply pipe and configured to open and close the supply pipe.