JP2000233372A - Slurry feed system and polishing system using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve stabilization of slurry concentration and improvement in work efficiency in simple constitution by controlling passage switching means to circulate slurry in one selected tank in a plurality of tanks. SOLUTION: A slurry mixing unit 16 includes a mixing tank 30 for mixing crude slurry solution fed from a slurry feeding unit 14 with a dilution liquid 1. The crude slurry solution feeding unit 14 includes crude solution tanks 42, 44, 46 for storing crude slurry solution. A feed pipe 50 for feeding crude slurry solution to the mixing tank 30, a take-out piping 62 used in circulating crude slurry solution and a return piping 64 are connected to the crude solution tank 42. A feed pipe 52 for the crude slurry solution, a taking-out piping 66 used in circulating crude slurry solution and a return piping 68 are connected to the crude solution tank 44. A feeding piping 54, a taking-out piping 70 and a return piping 72 are connected to the crude solution tank 46.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a slurry supply system used in a polishing apparatus for flattening a surface of a semiconductor wafer or the like.

[0002]

2. Description of the Related Art As a polishing apparatus for flattening the surface of a semiconductor wafer or the like, a CMP apparatus (chemical mechanical polishing apparatus) is widely used at present. In a CMP apparatus, a polishing slurry is supplied between a rotating polishing pad and a semiconductor wafer. Such a polishing slurry is stored in a predetermined tank and then sent out to the CMP apparatus main body side. When refilling the tank with new slurry or cleaning the inside of the tank, the use of the tank must be temporarily stopped. Therefore, it is conceivable to use a plurality of tanks alternately.

In a polishing system, it is important to use a slurry having a stable concentration. For this reason, a method of circulating and stirring the slurry in a tank has been proposed for the purpose of preventing a change in concentration due to precipitation of the slurry.

[0004]

However, when a plurality of slurry tanks are used, there is a problem in circulating the slurry stored in the tanks. That is,
To constantly circulate the slurry in all tanks,
Requires multiple or large pumps. For this reason, there is a problem that the configuration is complicated and large, the cost of the entire system is increased, and maintenance is troublesome.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a slurry supply system and a polishing system capable of stabilizing a slurry concentration and improving operation efficiency with a simple configuration. Aim.

[0006]

In order to solve the above problems, a slurry supply system according to a first aspect of the present invention includes a plurality of tanks for storing slurry; and a plurality of tanks connected to each of the plurality of tanks. A circulation piping system used to circulate the slurry in the tank; a single circulation pump connected to all of the circulation piping systems; and between a plurality of circulation piping systems and the circulation pump. A flow switching means connected thereto; and a control means for controlling the flow switching means so as to circulate the slurry in a selected one of the plurality of tanks.

[0007] A polishing system according to a second aspect of the present invention includes a polishing apparatus for polishing a workpiece using a slurry;
A plurality of tanks for storing a stock slurry having a higher concentration than the slurry actually used; a slurry mixing unit for mixing the stock slurry supplied from the tank with a predetermined diluent to produce a slurry having an appropriate concentration; A circulating piping system connected to each of the tanks and used to circulate the slurry in the tank; a single circulating pump connected to all of the circulating piping systems; Flow path switching means connected between the piping system and the circulation pump; and control means for controlling the flow path switching means so as to circulate the slurry in a selected one of the plurality of tanks.

As described above, in the present invention, a plurality of tanks for storing the slurry are provided, and these tanks are selectively used. Polishing work can be performed efficiently. In addition, since a single pump is used for a plurality of tanks, and the slurry is circulated only for the tank in use by switching the flow path, a pump may be provided for each tank or a large capacity pump may be provided. No need to use.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to examples. In the embodiments described below, the technical idea of the present invention is applied to a CMP system for polishing the surface of a semiconductor wafer. It goes without saying that the present invention can be applied not only to polishing of semiconductor wafers but also to polishing of various workpieces such as magnetic disks and glass substrates.

[0010]

FIG. 1 shows the overall configuration of a CMP system according to an embodiment of the present invention. The CMP system 10 includes a CMP apparatus main body 12, a configuration (14 to 18 and the like) for supplying a polishing slurry to the apparatus 12, a configuration (20 and others) for contributing to regeneration of used slurry, and a disposal unit 24. ing. The CMP apparatus main body 12 polishes the surface of the semiconductor wafer using a polishing pad. During the polishing operation, a polishing slurry is supplied between the polishing pad and the semiconductor wafer.

Reference numeral 16 denotes a slurry mixing unit,
A slurry stock solution having a higher concentration than the polishing slurry used in the CMP apparatus supplied from the slurry stock solution supply unit 14 is mixed with a diluent such as pure water or an additive at a predetermined ratio to obtain a desired concentration. The new polishing slurry supplied from the slurry mixing unit 16 is sent to the slurry supply unit 18.

On the other hand, the used slurry discharged from the CMP apparatus main body 12 is supplied to a disposal unit 24 and a return unit (regeneration unit) 20. The slurry supplied to the disposal unit 24 is a slurry that does not have an appropriate concentration, such as a discharged slurry immediately after the CMP apparatus main body 12 is washed with pure water, and is discarded without being recycled. On the other hand, the slurry supplied to the return unit 20 is a slurry having an appropriate concentration, and is returned to the slurry supply unit 18 after the filter unit performs a filtration regeneration process.

The slurry supply unit 18 includes a storage tank, a pump, and a temperature control mechanism. The new slurry supplied from the slurry mixing unit 16 and the regenerated slurry supplied from the return unit 20 are mixed and stored. Then, the temperature is adjusted and supplied to the filter unit 22. Filter unit 22
Filters the polishing slurry immediately before being supplied to the CMP apparatus main body 12 to remove secondary growth abrasive grains and abnormal growth abrasive grains of the slurry.

A valve 26 is provided between the main body 12 of the CMP apparatus and the filter unit 22 so that the polishing slurry supplied from the filter unit 22 is removed by the CMP.
The guide is directed to only one of the apparatus main body 12 and the return unit 20. That is, the configuration is such that the flow path of the polishing slurry can be arbitrarily switched between the CMP apparatus main body 12 side and the return unit 20 side. C
Further, pure water for cleaning is supplied to the MP apparatus main body 12 via a valve 27.

On the other hand, a valve 28a is provided between the CMP apparatus main body 12 and the return unit 20, and a waste unit 2 is provided.
4, valves 28b are provided respectively. By selectively opening and closing these two valves 28a and 28b, the flow path of the liquid (slurry, pure water) discharged from the CMP apparatus main body 12 is switched between the return unit 20 side and the waste unit 24 side. It is designed to switch. The slurry supplied to the return unit 20 is
Cycle through the system for recycling. Further, the slurry and pure water supplied to the disposal unit 24 are disposed at a predetermined timing.

Next, the overall operation of the CMP system 10 configured as described above will be briefly described. From the slurry stock solution supply unit 14 to the slurry mixing unit 1
The slurry stock solution supplied to 6 is mixed with a diluting solution (pure water) at a predetermined ratio and then sent to the slurry supply unit 18. During the polishing operation, the valve 27
Is closed, and the valve 26 is open to the CMP apparatus main body 12.

The used slurry discharged from the CMP apparatus main body 12 during the polishing operation and supplied to the return unit 20 is filtered and regenerated in the return unit 20, and supplied to the slurry supply unit 18 as regenerated slurry. You.

The new slurry supplied from the slurry mixing unit 16 and the regenerated slurry supplied from the return unit 20 are mixed in the slurry supply unit 18 and sent to the filter unit 22.
Then, the slurry filtered again by the filter unit 22 is supplied to the CMP apparatus main body 12.

When the polishing operation in the CMP apparatus main body 12 is completed, the valve 2 is used for cleaning the polished wafer and the apparatus.
6 is opened to the return unit 20, the valve 27 is opened, and pure water is supplied to the CMP apparatus main body 12.
Supply within. During the cleaning of the CMP apparatus main body 12, the valve 28a is closed and the valve 28b is opened, and the discharged liquid of the CMP apparatus main body 12 (mixed liquid such as pure water, residual slurry and polishing waste) is discarded through the discarding unit 24. I do.

FIG. 2 shows the detailed structure of the slurry stock solution supply unit 14 and the slurry mixing unit 16 described above. The slurry mixing unit 16 includes a slurry stock solution supplied from the slurry stock solution supply unit 14 and a diluent (pure water).
And a load cell 40 for measuring the weight of the slurry in the mixing tank 30. In the mixing tank 30, driven by a motor 32,
A stirring fin 34 for stirring the slurry in the tank 30 is provided. The slurry stored in the mixing tank 30 is sent to the slurry supply unit 18 by a pump 38.

The undiluted slurry supply unit 14 includes three undiluted tanks 42, 44, 46 for storing undiluted slurry.
And load cells 88, 90, which measure the weight of the slurry stock solution stored in the stock solution tanks 42, 44, 46.
92. The capacities of the stock solution tanks 42, 44, 46 are set sufficiently larger than the capacity of the mixing tank 30. For example, the capacity of the mixing tank 30 can be about 10 liters, and the capacity of the stock solution tank can be 200 liters. With such a volume setting, the slurry stock solution can be supplied to the mixing tank 30 with a margin. The slurry stock solution supply unit 14 and the mixing unit 1
The space required around the CMP apparatus body 12 can be reduced by installing the apparatus 6 away from the CMP apparatus body 12, the return unit 20, the slurry supply unit 18 and the filter unit 22.

The stock solution tank 42 includes a supply pipe 50 for supplying the stored slurry stock solution to the mixing tank 30, and a take-out pipe 62 and a return pipe 64 used for circulation of the slurry stock solution. Are linked. A circulation piping system is constituted by the removal piping 62 and the return piping 64. A supply pump 48 is connected to the supply pipe 50, and the action of the pump 48 supplies the stock slurry in the stock tank 42 to the mixing tank 30 side. On the other hand, the extraction pipe 62 and the return pipe 64
Is connected to a circulation pump 86, and the operation of the pump 86 circulates and agitates the slurry stock solution in the stock solution tank 42. The supply pipe 50, the extraction pipe 62, and the return pipe 64 have valves 56, 74,
76 are connected, and these valves 56, 74, 7
By controlling the opening and closing of 6, the operation timing of the supply and circulation of the slurry stock solution is adjusted.

In the stock solution tank 44, a supply pipe 52 for supplying the stored stock slurry to the mixing tank 30, and a take-out pipe 66 and a return pipe 68 used for circulation of the stock slurry are provided. Are linked. A circulation piping system is constituted by the removal piping 66 and the return piping 68. A supply pump 48 is connected to the supply pipe 52, and the action of the pump 48 supplies the stock slurry in the stock solution tank 44 to the mixing tank 30 side. On the other hand, the extraction pipe 66 and the return pipe 68
Is connected to a circulation pump 86, and the operation of the pump 86 circulates and agitates the slurry stock solution in the stock solution tank 44. The supply pipe 52, the extraction pipe 66, and the return pipe 68 have valves 58, 78,
80 are connected and these valves 58, 78, 8
The opening and closing control of 0 adjusts the operation timing of the supply and circulation of the slurry stock solution.

The stock solution tank 46 has a supply pipe 54 for supplying the stored stock slurry to the mixing tank 30, a take-out pipe 70 used for circulating the stock slurry in the tank, and a return pipe 70. The pipe 72 is connected. A circulation piping system is constituted by the extraction pipe 70 and the return pipe 72. A supply pump 48 is connected to the supply pipe 54, and the action of the pump 48 supplies the slurry stock solution in the stock solution tank 46 to the mixing tank 30 side. On the other hand, a circulation pump 86 is connected to the take-out pipe 70 and the return pipe 72, and the operation of the pump 86 circulates the stock slurry in the stock tank 46. The supply pipe 54, the take-out pipe 70, and the return pipe 72 have valves 60, 8 respectively.
2, 84 are connected and these valves 60, 8
The operation timing of supply and circulation of the undiluted slurry is adjusted by the opening and closing control of 2,84.

FIG. 3 shows the configuration of a control system for the slurry stock solution supply unit 14 and the mixing unit 16 shown in FIG. In the present embodiment, the control unit 100 performs overall control. That is, the remaining amount of slurry in the mixing tank 30
A load cell 40 for measuring (weight), a stock solution tank 42,
Based on the output signals of the load cells 88, 90 and 92 for measuring the remaining amount (weight) of the slurry stock solution 44 and 46, the operation control of the circulation pump 86 and the supply pump 48 and the operation of the valves 56 and
Open / close control of 58, 60, 74, 76, 78, 80, 82, 84 is performed.

FIG. 4 shows the operation timing in the slurry stock solution supply unit 14 shown in FIG. In this embodiment, the stock solution tanks are used in the order of 42, 44, 46. Thus, by providing the plurality of stock solution tanks 42, 44, and 46 and using these tanks alternately, the polishing operation can be performed efficiently without stopping the operation for cleaning the tank or replenishing the slurry. be able to. While supplying the slurry stock solution using the stock solution tank 42,
The control unit 100 opens the valves 56, 74, 76 and closes the other valves 58, 60, 78, 80, 82, 84. The control unit 100 drives the supply pump 48 when it is determined from the signal (measurement result) from the load cell 40 that the remaining amount of the slurry in the mixing tank 30 is equal to or smaller than the predetermined reference value A (in the figure). A point).

Thus, the selected stock solution tank 4
From 2, a high concentration slurry stock solution is supplied to the mixing tank 30. When it is determined from the signal from the load cell 40 that the weight of the slurry in the mixing tank 30 has increased to the desired value B, that is, when the desired amount of the slurry stock solution is supplied into the mixing tank 30, The operation pump 48 is stopped (point B in the figure). Thereafter, the valve 36 is opened to supply pure water into the mixing tank 30. Control unit 100
When the signal from the load cell 40 indicates that the slurry weight in the mixing tank has increased to a desired value,
That is, when a desired amount of pure water is supplied into the mixing tank 30, the valve 36 is closed and the supply of pure water is stopped.

The control unit 100 also includes a circulation pump 86
Is intermittently driven to circulate and agitate the undiluted slurry stored in the undiluted solution tank 42 via the take-out pipe 62 and the return pipe 64. Thereby, the stock solution tank 42
The sedimentation of the slurry stock solution stored in the slurry can be prevented. The drive of the circulation pump 86 is intermittent operation such as ON for 5 minutes and OFF for 5 minutes in order to extend the life of the pump, but it can be always ON. Further, the interval of the intermittent operation can be changed according to the easiness of sedimentation of the used slurry stock solution.

When the remaining amount of the undiluted slurry in the undiluted solution tank 42 becomes equal to or less than a predetermined lower limit and the operation of supplying the undiluted slurry to the mixing tank 30 at that time is completed, the next undiluted solution tank 44 Is selected. That is,
When the measured value of the load cell 88 becomes equal to or less than the lower limit value C (point C in the figure), the control unit 100 moves from the stock solution tank 42 by the supply pump 48 at that time to the mixing tank 30.
After the supply of the undiluted slurry to the tank is completed, the valves 56, 74, and 76 which have been open are closed and the valves 58, 78, and 80 are opened. The valves 60, 8
2, 84 remain closed. Thereafter, circulation and supply of the slurry stock solution are performed using the stock solution tank 44 as in the case of the stock solution tank 42.

Thus, the stock solution tank 44 to be used next
The switching to is not performed immediately when the measured value of the load cell 88 becomes equal to or less than the lower limit, but the operation of supplying the undiluted slurry from the undiluted solution tank 42 to the mixing tank 30 at that time is performed as usual. Since the switching is performed after the end, a sufficient amount of slurry is stored in the mixing tank 30 at the time when the switching is performed. Accordingly, a sufficient interval can be provided until the next supply of the slurry stock solution to the mixing tank 30 (until the remaining amount of the slurry in the mixing tank 30 becomes equal to or less than the predetermined reference amount A). During this interval, the slurry stock solution in the stock solution tank 44 to be used next can be circulated by the circulation pump 86.
Therefore, the slurry stock solution having an inappropriate concentration due to sedimentation of the abrasive grains and the like is not supplied from the stock solution tank 44 to the mixing tank 30.

Also, just in case, after the switching of the undiluted solution tank, the control system is designed so that the operation of the supply pump 48 is not started until the circulation operation by the circulation pump 86 for a predetermined time (one time) is completed. 100 may be provided. The work of replenishing the used stock solution tank 42 with the new stock solution and the washing operation of the tank may be performed while another stock solution tank is selected, so that there is no need to interrupt the polishing work.

The lower limit of the stock solution tank can be set as follows. FIG. 5 is an explanatory diagram for explaining the concept of setting the lower limit. In the figure, reference numeral 242 denotes a stock solution tank, and 230 denotes a mixing tank. It is assumed that the remaining amount of the slurry stock solution in the stock solution tank at the time when the lower limit value is reached is x. Further, the supply amount of the slurry stock solution supplied from the stock solution tank to the mixing tank at one time is represented by y. This y is determined by the capacity of the mixing tank and the dilution ratio of the slurry stock solution. (For example, when the mixing tank capacity is 10 liters (capacity up to the reference value A of the mixing tank described above) and the mixing ratio between the slurry stock solution and the diluent is 1: 1 by volume, y is 5 liters. At this time, the lower limit value of the stock solution tank is set so that x is equal to or more than y (x is set to be equal to y as described below or as close to y as possible). desirable). By setting the lower limit in this way, it is possible to prevent the slurry stock solution in the stock solution tank from running out before the operation of supplying the stock slurry solution from the stock solution tank to the mixing tank is completed.

Incidentally, in order to reduce the number of replenishment operations of a new slurry stock solution, the capacity z of the stock solution tank is preferably large. On the other hand, the amount of the undiluted slurry remaining without being used in the undiluted solution tank is x at the maximum, but the smaller the amount of the undiluted slurry is, the higher the efficiency is, so x (≧ y) is small. Better. Therefore, it is better that z is sufficiently larger than x, that is, it is better that the stock tank capacity is sufficiently larger than the mixing tank capacity.

In the example shown in FIG. 4, in order to simplify the explanation, the volume z of the stock solution tank is about three times the supply amount y per one time of the stock solution of the slurry (the supply operation of the stock solution tank by the pump 48 is performed three times). In practice, it is desirable to set the volume of the stock solution tank to 10 times or more the supply amount per operation, and more preferably to 20 times or more.

When the remaining amount of the undiluted slurry in the undiluted solution tank 44 becomes equal to or less than the lower limit and the operation of supplying the undiluted slurry to the mixing tank 30 at that time is completed, the next undiluted solution tank 46 is selected. Supply and circulation of the slurry stock solution are performed by the same operation as described above. The used stock tank is replenished with a new stock slurry, for example, after internal cleaning. The undiluted slurry supplied to the mixing tank 30 is mixed with pure water (diluent) in the tank 30 to be converted into a slurry having a predetermined concentration and sent out to the CMP apparatus main body 12 side. The capacities of the plurality of stock solution tanks may all be the same, or may be different capacities. In the case of different capacities, the above-described conditions may be satisfied in each of the stock tanks.

As described above, in this embodiment, a single circulation pump 86 is used for a plurality of stock solution tanks 42, 44, and 46, and the slurry is controlled only for the tank being used by controlling the opening and closing of valves. Because of the circulation of
There is no need to provide a pump for each tank or use a large capacity pump.

FIG. 6 shows a CMP according to another embodiment of the present invention.
2 shows a configuration of a stock slurry supply unit 94 used in the system. In this embodiment, the same or corresponding components as those in the embodiment shown in FIG. 2 are denoted by the same reference numerals, and redundant description will be omitted. In the embodiment shown in FIG. 6, a pump 98 having both functions is used in place of the circulation pump 86 and the supply pump 48 of the above-described embodiment. A valve 96 is provided between the pump 98 and the mixing tank 30, and the supply and circulation of the undiluted slurry are switched by opening and closing the valve 96.

The stock solution tank 42 supplies the stock slurry solution stored therein to the mixing tank 30 and takes out the stock solution slurry for circulation, and a pipe 102 for returning the stock slurry solution to the tank during circulation. The pipe 104 is connected. A valve 106 is connected between the pipe 102 and the pump 98, and a valve 108 is connected between the pipe 104 and the pump 98. The valve 106 is open both during supply and during circulation. on the other hand,
The valve 108 is opened only when the slurry is circulated, that is, when the valve 96 is closed.

The stock solution tank 44 supplies the stored stock slurry to the mixing tank 30 and removes the stock slurry for circulation, and a pipe 110 for returning the stock slurry to the tank during circulation. The pipe 112 is connected. A valve 114 is connected between the pipe 110 and the pump 98, and a valve 116 is connected between the pipe 112 and the pump 98. The valve 114 is open both during supply and during circulation. on the other hand,
The valve 116 is opened only when the slurry is circulated, that is, when the valve 96 is closed.

The stock solution tank 46 supplies the stock slurry solution stored therein to the mixing tank 30 and takes out the stock solution slurry for circulation, and a pipe 118 for returning the stock slurry solution to the tank during circulation. The pipe 120 is connected. A valve 122 is connected between the pipe 118 and the pump 98, and a valve 124 is connected between the pipe 120 and the pump 98. The valve 122 is open both during supply and during circulation. on the other hand,
The valve 124 is opened only when the stock slurry is circulated, that is, when the valve 96 is closed.

FIG. 7 shows the configuration of a control system of the slurry stock solution supply unit 14 shown in FIG. Also in the present embodiment, the control unit 100 performs overall control similarly to the above-described embodiment. That is, the load cell 40 for measuring the remaining amount of the slurry in the mixing tank 30 and the stock solution tanks 42 and 4
Load cell 8 for measuring remaining amount of 4,46 slurry stock solution
Based on the output signals of 8, 90 and 92, the operation of the pump 98 is controlled and the valves 96, 106, 108, 114 and 11 are controlled.
6, 122 and 124 are controlled.

FIG. 8 shows the operation timing in the slurry stock solution supply unit 94 shown in FIG. Also in this embodiment, the stock solution tanks are used in the order of 42, 44, 46. While supplying the stock slurry using the stock tank 42, the valve 106 is opened and the valves 114 and 114 are opened.
122 is closed. When the remaining amount of the slurry in the mixing tank 30 becomes equal to or less than the predetermined reference value A, a supply command is issued from the mixing unit 16 (point A in the figure). The controller 100 opens the valve 96 and simultaneously closes the valve 108 while the supply command is issued (until the weight of the slurry in the mixing tank 30 reaches the desired value B as in the above-described embodiment). I do. That is, regardless of the state of the circulation operation, if there is a supply command from the mixing unit 16, the supply of the stock slurry to the mixing tank 30 is preferentially performed.

An intermittent command is supplied to the control unit 100 periodically (at regular intervals) for circulation of the slurry stock solution. The control unit 100 drives the pump 98 when at least one of the supply command and the intermittent command is ON. When the valve 96 is closed and the pump 98 is operating, the circulation and stirring of the slurry stock in the stock tank 42 are performed.

The remaining amount of the stock slurry in the stock tank 42 becomes equal to or less than a predetermined lower limit (a value set based on the same concept as in the above-described embodiment), and the supply of the stock slurry at that time is performed. Is completed, the next stock solution tank 44 is selected. That is, when the measured value of the load cell 88 becomes equal to or lower than the lower limit value C (point C in the figure), the control unit 100 controls the supply of the stock slurry from the stock tank 42 to the mixing tank 30 by the pump 98 at that time. After the termination, the valve 106 which has been open is closed and the valve 114 is opened. Note that the valve 122 is kept closed. Thereafter, the supply and circulation of the slurry stock solution are performed using the stock solution tank 44 as in the case of the stock solution tank 42.

As described above, the stock solution tank 44 to be used next
The switching to is not performed immediately when the measured value of the load cell 88 becomes equal to or less than the lower limit, but the operation of supplying the undiluted slurry from the undiluted solution tank 42 to the mixing tank 30 at that time is performed as usual. Since the switching is performed after the end, a sufficient amount of slurry is stored in the mixing tank 30 at the time when the switching is performed. Therefore, a sufficient interval can be provided until the next supply of the slurry stock solution to the mixing tank 30 (until the remaining amount of slurry in the mixing tank 30 becomes equal to or less than the predetermined reference value A). During this interval, the pump 98 can circulate the slurry stock solution in the stock solution tank 44 to be used next. Therefore, the slurry stock solution having an inappropriate concentration due to sedimentation of the abrasive grains and the like is not supplied from the stock solution tank 44 to the mixing tank 30.

Incidentally, a control system that does not open the valve 96 until the circulation operation of the pump 98 for a predetermined time (one time) is completed after the switching of the stock solution tank may be provided in the control unit 100, just in case. Good.

When the remaining amount of the undiluted slurry in the undiluted solution tank 44 becomes equal to or less than the lower limit and the supply of undiluted undiluted solution at that time is completed, the next undiluted solution tank 46 is selected, and the same operation as described above is performed. Supply and circulation of the slurry stock solution are performed.

[0048]

As described above, according to the present invention,
Since a plurality of tanks for storing the slurry are provided and these tanks are used alternately, the polishing operation can be efficiently performed without stopping the operation for cleaning the tank or replenishing the slurry. In addition, since a single pump is used for a plurality of tanks, and the slurry is circulated only for the tank in use by switching the flow path, a pump may be provided for each tank or a large capacity pump may be provided. No need to use.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an overall configuration of a CMP system according to the present invention.

FIG. 2 is a schematic diagram showing a configuration of a slurry stock solution supply unit and a mixing unit according to an embodiment of the present invention.

FIG. 3 is a block diagram showing a configuration of a control system of the embodiment shown in FIG. 2;

FIG. 4 is a timing chart showing an operation of the embodiment shown in FIG. 2;

FIG. 5 is an explanatory diagram for explaining the concept of setting the lower limit value of the stock solution tank of the embodiment shown in FIG. 2;

FIG. 6 is a schematic view showing a configuration of a slurry stock solution supply unit and a mixing unit according to another embodiment of the present invention.

FIG. 7 is a block diagram showing a configuration of a control system of the embodiment shown in FIG. 6;

FIG. 8 is a timing chart showing the operation of the embodiment shown in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 CMP system 12 CMP apparatus main body 14 Slurry stock solution supply unit 16 Slurry mixing unit 48 Supply pump 86 Circulation pump 50,52,54 Supply piping 56,58,60,74,76,78,80,82,8
4 Valves 62, 66, 70 Removal pipe 64, 68, 72 Return pipe 100 Control unit

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Keiji Soejima 1-8 Fuso-cho, Amagasaki-shi, Hyogo Sumitomo Metal Industries, Ltd. Semiconductor Equipment Division F-term (reference) 3C047 FF08 GG13 GG15 3C058 AA07 AC04 CB03 DA17

Claims (7)

[Claims] 1. A slurry supply system for supplying a polishing slurry to a predetermined location, comprising: a plurality of tanks for storing the slurry; a plurality of tanks connected to each of the plurality of tanks, and the slurry circulated in the tanks. A single circulation pump connected to all of the circulation piping systems; a flow switching means connected to the plurality of circulation piping systems; Control means for controlling the flow path switching means so as to circulate the slurry in a selected one of the tanks. 2. The slurry supply system according to claim 1, wherein said tank is a slurry stock solution tank for storing a slurry stock solution. 3. The control means selects one of the plurality of tanks for slurry supply, and after circulating the slurry stored in the selected tank for a predetermined period of time, 3. The slurry supply system according to claim 1, wherein the flow path switching unit is controlled so as to start a slurry supply operation from a tank. 4. A supply pipe for taking out stored slurry is connected to each of the plurality of tanks, a supply pump is provided on the supply pipe, and the control means controls the slurry supply. 4. The slurry according to claim 3, wherein the supply operation by the supply pump is started after the circulation operation for a predetermined time by the operation of the circulation pump is completed in the tank newly selected for operation. 5. Feeding system. 5. The slurry supply system according to claim 4, wherein said circulation pump doubles as said supply pump. 6. A valve is provided between the circulation pump and the predetermined supply location, and the control means terminates the circulation operation for a predetermined time in a tank newly selected for slurry supply. The slurry supply system according to claim 5, wherein the opening and closing states of the pump and the valve are controlled so that a slurry supply operation is performed later. 7. A polishing apparatus for polishing a workpiece using a slurry; a plurality of tanks for storing a slurry stock solution having a higher concentration than the slurry actually used; A slurry mixing unit that mixes with a diluent to produce a slurry having an appropriate concentration; a circulation piping system connected to each of the plurality of tanks and used to circulate the slurry stock solution in the tanks; A single circulation pump connected to all of the circulation piping systems; flow switching means connected between the plurality of circulation piping systems and the circulation pump; selection of the plurality of tanks And a control means for controlling the flow path switching means so as to circulate the slurry in one of the polishing systems.