JP2010089180A - Slurry feeder for polishing substrate chemical machine, and polishing system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To consistently and constantly feed polishing slurry not including any bubble, and to stably operate a centrifugal pump by separating bubbles from the polishing slurry even if bubbles are mixed in the polishing slurry, in a polishing slurry feeder for feeding the polishing slurry for polishing a substrate by a CMP (Chemical Mechanical Polishing) method to a substrate polishing apparatus by using the centrifugal pump. <P>SOLUTION: A polishing slurry feeder comprises a storage tank for storing polishing slurry, a centrifugal pump for feeding the polishing slurry to a substrate polishing apparatus, a feed pipe for connecting the storage tank to a suction side of the centrifugal pump to form a flow passage of the polishing slurry, and a discharge pipe connected to the discharge side of the centrifugal pump to form a flow passage of the polishing slurry. Furthermore, a gas separating pipe having an open end is connected to the feed pipe so that the open end is located above the level of the polishing slurry stored in the storage tank. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a substrate chemical mechanical polishing slurry supply apparatus and a polishing system.

  As a surface polishing technology for semiconductor substrates such as silicon wafers, liquid crystal panel substrates, plasma panel substrates such as silicon wafers that require a high level of flatness, dispersion and suspension stability of abrasives such as silica particles and alumina particles in aqueous media A chemical mechanical polishing method (CMP method) using a liquefied slurry is widely used. In such a CMP method, a polishing system including a polishing slurry supply device and a substrate polishing device is used (Patent Document 1).

  Such a polishing slurry supply device includes a storage tank for storing the polishing slurry, a liquid feed pump for transferring the polishing slurry in the storage tank to the substrate polishing device, a storage tank, and a suction side of the liquid supply pump. It includes a supply pipe to be connected and a discharge pipe connected to the discharge side of the liquid feed pump. In addition, as a liquid feed pump, a centrifugal pump has come to be used because the flow rate of the fluid is easy to control from the reciprocating pump, there is no pulsation, and there is no poor liquid feed due to wear in the sealing part. ing.

JP 2007-319948 A

  By the way, the CMP slurry for polishing a substrate such as a semiconductor wafer includes bubbles generated by decomposition of added hydrogen peroxide and various additives, bubbles generated by local heating of the CMP slurry, and the like. There is a case. The presence of bubbles may impair the stable supply of the CMP slurry to the substrate polishing apparatus, possibly causing an air lock inside the centrifugal pump and stopping the CMP slurry feeding. In addition, there is a problem that the centrifugal pump itself must be stopped in order to remove the bubbles once taken into the centrifugal pump and stopped in the centrifugal pump. As a result, the substrate to be polished is defective, and the productivity is greatly reduced.

  An object of the present invention is to solve the above-described problems of the prior art, and supply a polishing slurry for polishing a substrate to a substrate polishing apparatus using a centrifugal pump for polishing the substrate by CMP. Even if air bubbles are mixed in the polishing slurry, the device separates the air bubbles from the polishing slurry, and supplies the polishing slurry that does not contain air bubbles to the centrifugal pump stably and constantly. It is an object to provide a polishing slurry supply apparatus that can be operated in the same manner.

  The present inventor connects a storage tank for storing a polishing slurry for chemical mechanical polishing of a semiconductor substrate and a centrifugal pump, and mixes the polishing slurry into a supply pipe serving as a flow path for the polishing slurry. By connecting a gas separation pipe having an open end as a means for separating bubbles so that the open end is positioned above the liquid level of the polishing slurry stored in the storage tank, the above-mentioned purpose is achieved. We have found that this has been accomplished and completed the present invention.

That is, the present invention includes a storage tank for storing a polishing slurry for chemically mechanically polishing a substrate, a centrifugal pump for supplying the polishing slurry to a substrate polishing apparatus, a storage tank, and a suction side of the centrifugal pump. In a polishing slurry supply apparatus having a supply pipe that is connected between and a supply pipe that is a flow path for polishing slurry, and a discharge pipe that is connected to the discharge side of the centrifugal pump and is a flow path for polishing slurry,
As means for separating bubbles in the polishing slurry from the polishing slurry, a gas separation pipe having an open end is positioned above the liquid level of the polishing slurry stored in the storage tank. Thus, a polishing slurry supply apparatus is provided which is connected to the supply pipe.

  The present invention also provides a rotatable substrate polishing stage, a substrate holding unit that holds the substrate and presses the substrate while rotating the substrate polishing stage, and polishing that applies polishing slurry to the substrate polishing stage. The polishing slurry is supplied to the polishing slurry applying section of the substrate polishing apparatus from the discharge pipe of the polishing slurry supply apparatus. A polishing system is provided.

  In the polishing slurry supply apparatus of the present invention, as a means for separating bubbles in the polishing slurry from the polishing slurry, a gas separation pipe having an open end is polished in which the open end is stored in the storage tank. It is connected to supply piping so that it may be located above the liquid level of the slurry for use. Therefore, it is possible to reliably suppress bubbles from accumulating in the supply pipe connecting the storage tank and the centrifugal pump, and stably supply the polishing slurry to the substrate polishing apparatus without generating an air lock in the centrifugal pump. Can do.

  The present invention will be described below with reference to the drawings. In each figure, the same figure number represents the same or equivalent component.

  FIG. 1 shows a polishing slurry supply apparatus of the present invention. The polishing slurry supply apparatus includes a storage tank 1 for storing a polishing slurry SL for chemical mechanical polishing a substrate such as a silicon wafer, and a centrifugal pump for supplying the polishing slurry SL to the substrate polishing apparatus (100). 2, the storage tank 1 and the suction side 2 a of the centrifugal pump 2, connected to the supply pipe 3 serving as a flow path for the polishing slurry SL, and the discharge side 2 b of the centrifugal pump 2, and the polishing slurry SL And a discharge pipe 4 serving as a flow path. In addition, the supply pipe 3 may branch the drainage pipe 5, and in that case, it is preferable to include a valve v. Alternatively, the supply pipe 3 and the drain pipe 5 may be separately connected to the storage tank 1 (not shown). In that case, it is preferable to connect the supply pipe 3 to the storage tank 1 at a position higher than the drainage pipe 5.

  The polishing slurry supply apparatus of the present invention has a gas separation pipe connected upward from the supply pipe 3 as means for separating bubbles in the polishing slurry SL from the polishing slurry SL. The gas separation pipe 6 is disposed so that the open end 6 a is positioned above the liquid level of the polishing slurry SL stored in the storage tank 1. Therefore, the liquid surface of the polishing slurry SL in the storage tank 1 and the liquid surface of the polishing slurry SL in the gas separation pipe 6 are substantially equal in height.

  In order to facilitate separation of bubbles in the polishing slurry SL, it is desirable that the pipe diameter of the gas separation pipe 6 is equal to or larger than the pipe diameter of the supply pipe 3. Here, the equivalent diameter means that the former diameter is preferably 0.9 to 1.1 times, particularly 1.0 times the latter diameter, and the larger diameter means the former diameter. Is preferably 1.1 times (not including 1.1 times) to 3 times, particularly 1.5 times to 2.5 times the latter diameter.

  In the polishing slurry supply apparatus of FIG. 1, even when bubbles are mixed in the polishing slurry SL, the bubbles that have flowed to the gas separation pipe 6 together with the polishing slurry SL are lifted above the gas separation pipe 6 by their buoyancy. Ascended and released into the atmosphere from the open end 6a. Therefore, since air bubbles do not flow into the centrifugal pump 2, no air lock occurs in the centrifugal pump 2. Therefore, the polishing slurry supply apparatus can supply the polishing slurry SL to the substrate polishing apparatus (100) stably and permanently. Moreover, since the liquid level of the polishing slurry SL in the gas separation pipe 6 does not change, management devices such as a liquid level gauge and a valve are not required.

  Moreover, you may arrange | position the open end 6a of the gas separation piping 6 in the upper part of the storage tank 1, ie, above the liquid level of the slurry for polishing, as shown in FIG. In the unlikely event that the polishing slurry flows backward, there is a concern that the polishing slurry SL from the gas separation pipe 6 may leak, but the configuration shown in FIG. Can be recovered in the storage tank 1.

  Furthermore, in the polishing slurry supply apparatus of the present invention, a polishing slurry supply pipe (not shown) is connected to the storage tank 1 to replenish the polishing slurry SL to the storage tank 1 as necessary. May be. Further, as shown in FIG. 3, a stirring device 7 may be installed in order to maintain the dispersion state of the polishing slurry SL. Further, in order to prevent the solid matter (abrasive) from precipitating due to the drying of the slurry SL for polishing, the storage tank 1 is covered with a lid 8 and humidified gas introduction pipe for introducing humidified nitrogen or humidified air into the storage tank 1. 9 is preferably provided. Preparation of humidified nitrogen or humidified air can be performed by providing a known gas bubbling device (not shown) in the humidified gas introduction pipe 9. The storage tank 1 can be provided with a liquid level meter, a thermometer, a humidity measuring device (not shown), and the like.

  A gas separation pipe 6 can be connected to the lid 8 of the storage tank 1 in FIG. 3, and drying of the polishing slurry SL in the gas separation pipe 6 can be prevented. In this case, as a result, the open end 6a of the gas separation pipe 6 is opened to the atmosphere through the gap 7a between the stirring device 7 and the lid 8 or through the exhaust port 10 provided separately. .

  FIG. 4 shows another embodiment of the polishing slurry supply apparatus of the present invention. In this aspect, two storage tanks 1 are provided and are configured to be switchable so that the operation of the polishing slurry supply device does not stop due to cleaning of the storage tank or the like. That is, the supply pipe 3 opposite to the centrifugal pump 2 is branched into two, and the storage tank 1 is connected to each of the branched supply pipes 3.

  In addition, although the connection part of the supply piping 3 and gas separation piping 6 in the polishing slurry supply apparatus of this invention may use a general T-type connector, in order to improve the separation efficiency of a bubble, FIG. It is preferable to use a connector 50 having an internal region IR that increases the diameter of the supply pipe 3 such as a substantially conical connector or a substantially trapezoidal connector having a cross section as shown in FIG.

  Next, the polishing system of the present invention will be described.

  As shown in FIG. 1, the polishing system holds a rotatable substrate polishing stage 101 and a substrate 102 in the polishing slurry supply apparatus of the present invention, and presses the substrate 102 while rotating the substrate 102 to the substrate polishing stage 101. A substrate polishing apparatus having a substrate holding unit 103 that performs polishing and a polishing slurry applying unit 104 that applies polishing slurry SL to the substrate polishing stage 101 is combined. According to this polishing system, the polishing slurry SL is stably and continuously supplied to the substrate polishing stage 101. Therefore, the semiconductor substrate can be polished with high accuracy and high throughput.

  In the following, the results of measuring and evaluating the change in the discharge pressure of the centrifugal pump when the gas separation pipe is provided in the polishing slurry supply pipe and when the gas separation pipe is not provided will be described in relation to the embodiment of FIG.

(Discharge pressure change measurement (see Fig. 2))
Pure water was stored in the storage tank 1. One end of a supply pipe 3 having an outer diameter of 1 inch was connected to the bottom surface of the liquid storage tank 1, and the other end was connected to the suction side of a centrifugal pump 2 (LEV300, Levitronics). A discharge pipe 4 having an outer diameter of 1/2 inch was connected to the discharge side of the centrifugal pump 2. When the gas separation pipe 6 was provided, a pipe having an outer diameter of 1 inch was connected upward to the supply pipe 3 on the primary side of the centrifugal pump 2.

  Next, in order to experimentally mix bubbles in the pure water that is the slurry for pseudo polishing, a nitrogen input pipe (not shown) is connected immediately downstream of the valve v of the supply pipe 3 to operate the centrifugal pump 2. Nitrogen was continuously flowed in 1 minute after the start. Moreover, in order to measure the discharge pressure of the centrifugal pump 2, a pressure gauge (CS-P-15, surpass industry) was installed in the discharge pipe 4. The flow rate of each fluid at the start of the experiment is 5 liters of pure water per minute and 50 milliliters of nitrogen per minute.

  FIG. 6 shows a comparison of changes in discharge pressure when the gas separation pipe 6 is provided and not provided. The broken line shows the case where the gas separation pipe 6 is provided, and the solid line shows the case where it is not provided. As can be seen from FIG. 6, when the gas separation pipe 6 was provided, the pressure of 43 kilopascals at the beginning of the measurement was stably maintained without change, but on the other hand, the gas separation pipe 6 was not provided. In this case, the pressure suddenly decreased, an air lock was generated after about 2 minutes, and the pressure, which was 43 kilopascals at the beginning of the measurement, became 0.6 kilopascals after 5 minutes. Therefore, from this measurement result, it was found that the gas separation pipe 6 is effective for separating bubbles.

  According to the polishing slurry supply apparatus and the polishing system of the present invention, as a means for separating bubbles in the polishing slurry from the polishing slurry, a gas separation pipe having an open end is stored in the storage tank. Since it is connected to the supply pipe so that it is located above the liquid level of the polishing slurry, the accumulation of bubbles in the supply pipe connecting the storage tank and the centrifugal pump is reliably suppressed, and The polishing slurry can be stably and continuously supplied to the substrate polishing apparatus without generating an air lock in the pump. Therefore, the polishing slurry supply apparatus and polishing system of the present invention are useful for polishing semiconductor wafers, liquid crystal panel substrates, and plasma panel substrates.

1 is a schematic diagram of a polishing slurry supply apparatus and a polishing system according to the present invention. It is a schematic diagram of the polishing slurry supply apparatus of another aspect of the present invention. It is a schematic diagram of a storage tank applicable to the present invention. It is a schematic diagram of the polishing slurry supply apparatus of another aspect of the present invention. It is the schematic of the connector used by this invention. It is a measurement_result figure of the discharge piping pressure in the slurry supply apparatus for grinding | polishing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Storage tank 2 Centrifugal pump 2a Centrifugal pump suction side 2b Centrifugal pump discharge side 3 Supply piping 4 Discharge piping 5 Drainage piping 6 Gas separation piping 6a Open end 7 Stirring device 7a Gap between stirring device and lid body 8 Lid 9 Humidifying gas introduction pipe 10 Exhaust port 50 Connector 100 Substrate polishing apparatus 101 Substrate polishing stage 102 Substrate 103 Substrate holding part 104 Polishing slurry applying part SL Polishing slurry v Valve IR Internal region

Claims (6)

A storage tank for storing a polishing slurry for chemical mechanical polishing of a substrate, a centrifugal pump for supplying the polishing slurry to a substrate polishing apparatus, and a connection between the storage tank and the suction side of the centrifugal pump for polishing In a polishing slurry supply apparatus having a supply pipe serving as a slurry flow path and a discharge pipe connected to the discharge side of the centrifugal pump and serving as a polishing slurry flow path,
As a means for separating bubbles in the polishing slurry from the polishing slurry, a gas separation pipe having an open end is positioned above the liquid level of the polishing slurry stored in the storage tank. As described above, the polishing slurry supply apparatus is connected to the supply pipe.   The polishing slurry supply apparatus according to claim 1, wherein the diameter of the gas separation pipe is equal to or larger than the diameter of the supply pipe.   The slurry supply apparatus for polishing a chemical substrate of a substrate according to claim 1 or 2, wherein an open end of the gas separation pipe is disposed at an upper portion of the storage tank.   The storage tank is covered with a lid body having an exhaust hole, and a humidified gas introduction pipe for flowing humidified nitrogen or humidified air into the space between the lid body and the liquid surface of the polishing slurry is provided on the lid body. The polishing slurry supply apparatus according to any one of claims 1 to 3.   The slurry supply apparatus for polishing according to any one of claims 1 to 4, wherein the supply pipe opposite to the centrifugal pump is branched into two, and a storage tank is connected to each of the branched supply pipes. .   A rotatable substrate polishing stage, a substrate holding unit that holds the substrate and presses the substrate while rotating the substrate polishing stage, and a polishing slurry applying unit that applies polishing slurry to the substrate polishing stage. A polishing slurry is supplied from a discharge pipe of the polishing slurry supply device to the polishing slurry applying portion of the substrate polishing device. Polishing system.

Images