JPH0929637A - Slurry supplying device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent solidification and decomposition of slurry inside a pipeline by providing a slurry discharging part and a slurry switching means in a slurry supplying line of a slurry supplying device for supplying the slurry to be used as the polishing material. SOLUTION: When polishing is started, slurry inside of a mixing tank 9 is supplied onto a surface plate 19 from a slurry discharging part 18 through a first gate valve 17 by a roller pump 14. At this stage, in a returning pipeline 20, since a second gate valve 21 is provided near the pipe end of the connection side with a slurry supplying pipeline 16, residual quantity of the slurry inside of a pipe of the returning pipeline 20 in the upstream side of the second gate valve 21 is reduced as small as possible. After concluding the polishing, when a rinse process for washing the surface plate 19 with the pure water is started, the first gate valve 17 is closed, and while the second gate valve 21 is opened. With this switching of valves, the slurry fed from the mixing tank 9 through the supplying pipeline 16 is returned to the mixing tank 9 through the returning pipeline 20.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a slurry supply device for supplying a slurry used as an abrasive in a wafer polishing process in the field of semiconductor device processing, and more particularly, to prevent solidification of the slurry at a discharge portion. The present invention relates to a slurry supply device.

[0002]

2. Description of the Related Art In recent years, chemical mechanical polishing, which is being considered for use in the manufacturing process of semiconductor devices, involves a relative rotational movement between a wafer and a polishing cloth while pressing the wafer against the polishing cloth with a constant pressure. Is a process of polishing while supplying a polishing agent.

Conventionally, a polishing apparatus used for this type of chemical mechanical polishing process has a surface plate having a polishing cloth fixed to the surface thereof with an adhesive such as a double-sided tape, and a semiconductor wafer to be polished. And a polishing head that holds the
It comprises a slurry supply device for supplying a slurry to be used as an abrasive on a polishing cloth, and a loader device for temporarily mounting the wafer and attaching / detaching the wafer to / from the polishing head.

The polishing head presses against the surface of the polishing cloth on the surface plate while rotating the held wafer, and moves in the radial direction of the surface plate. At this time, the slurry is supplied from the slurry supply device and the wafer is polished.

Conventionally, in a polishing apparatus used for chemical mechanical polishing, a system has been adopted in which slurry and pure water are supplied onto a surface plate by separate systems. Generally, in the case of this method, since there is no flushing mechanism, the slurry solids gradually solidify in the slurry discharge part, and the slurry solids adhering around the discharge part during polishing are polished on the surface plate. There was a problem in that it fell on the wafer in the middle of the process and damaged the surface of the wafer.

Therefore, in the conventional slurry supply device, a method of supplying pure water from the middle of the slurry pipe is adopted in order to prevent the solidification of the slurry around the slurry discharge part.

This method is an application of the technology originally used for mirror processing of silicon wafers to chemical mechanical polishing processing. If a little slurry solidifies, its effect is small, Even if it is flushing with pure water, no major problem occurs.

[0008]

However, some of the slurries used for processing semiconductor devices may solidify or precipitate in the slurry pipe when the processing is continuously stopped. However, in order to start it again, there is a problem that the slurry accumulated in the slurry pipe must be discarded once and a new slurry must be supplied.

Therefore, an object of the present invention is to solve the above problems of the prior art, prevent solidification and decomposition of the slurry in the slurry pipe, and prevent the slurry from adhering to the slurry discharge part. An object of the present invention is to provide a slurry supply device capable of preventing the above.

[0010]

In order to achieve the above object, the present invention provides a slurry supply device for supplying a slurry used as an abrasive on a surface plate for polishing a wafer, in which a slurry in a slurry tank is fixed. A slurry supply line for delivering to a slurry discharge part provided so as to face the board, and a slurry drawn from the upstream of the vicinity of the slurry discharge part of the slurry supply line and sent through the slurry supply line to the slurry tank. A slurry return line to recirculate to, and a pure water supply line extending from a pure water supply source and connected to the immediate upstream side of the slurry discharge section on the downstream side of the slurry return line,
The present invention is characterized by comprising line switching means for selectively connecting the slurry supply line to the slurry discharge unit and the slurry return line, and the pure water supply line to the slurry supply line.

In the above structure, the line switching means is on the slurry supply line and is provided between the slurry return line and the pure water supply line. It comprises a second sluice valve provided at the pipe end on the side connected to the supply line, and a third sluice valve provided on the pipe end on the side connected to the slurry supply line on the pure water supply line.

In the present invention, the slurry in the slurry tank is supplied to the slurry discharge part through the slurry supply line during the polishing process and discharged from the slurry discharge part onto the surface plate. When not, the line is switched, flows from the slurry supply line to the slurry return line, returns to the slurry tank, and the slurry circulates. Therefore, the slurry does not stay in the pipe, and it is possible to prevent the slurry from decomposing or solidifying in the pipe.

Further, during the rinsing step of cleaning the surface plate with pure water, since pure water is supplied from the pure water supply line to the surface plate through the slurry discharge part, the slurry is washed away and near the discharge part. Almost no slurry remains,
It becomes possible to prevent the slurry from adhering to the slurry discharge portion.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION A slurry supply apparatus embodying the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows an embodiment of a slurry supply apparatus according to the present invention. The slurry supply apparatus in this embodiment is a slurry in which two different types of stock solutions of slurry and pure water are quantitatively mixed. Is maintained at a constant temperature and supplied onto the surface plate. Depending on the type of slurry used, a slurry obtained by mixing one kind of stock solution with pure water may be used. In the figure, reference numerals 1 and 2 denote tanks containing one of the two undiluted stock solutions to be mixed, each of which has the same non-precipitating stock solution. Are provided respectively. Each of these scales 1a, 2a is for detecting that one tank 1 or 2 is empty, and when one tank 1 or 2 is empty, the valve 1c or 2c is switched to supply a fixed amount. The suction of the metering pump 8a of the device 8 is automatically switched to the full tank 2 or 1 side. Further, the operator is notified on the spot that one of the tanks 1 and 2 has become empty by an alarm buzzer or the like (not shown).

On the other hand, tanks 3 and 4 contain stock solutions having a sedimentation property, and these tanks 3 and 4 are provided with agitation pumps 5 and 6 for preventing sedimentation of solids. Each of them is installed and the weighing device 3
a and 4a are provided respectively. Similar to the case of the tank 1, each of the weighing devices 3a and 4a is for detecting that one of the tanks 3 or 4 is empty, and the other of the weighing devices 3a and 4a is automatically operated by the operation of the valves 3c and 4c. The suction of the metering pump 8b is switched to the side of the tank 4 or 5 which is full, and the operator is informed by the alarm buzzer or the like that one of the tanks 4 or 5 has become empty on the spot. It is like this.

Reference numeral 7 denotes a pure water tank, which receives pure water supplied from a pure water supply source 22 and stores a predetermined pure water by a liquid level sensor 7A. An open / close valve 7B for occasional complete replacement of pure water is attached to the bottom of the pure water tank 7.

The undiluted solution from one of the tanks 1 and 2, the undiluted solution from one of the tanks 3 and 4 and the deionized water from the deionized water tank 7 are supplied to the metering pumps 8a of the metering device 8.
8c to 8c are mixed at a constant ratio and supplied to a mixing tank 9 as a slurry tank made of, for example, a Teflon container. In addition, 9A is a liquid level sensor.

As the constant quantity supply device 8, a diaphragm type constant quantity pump 8a to 8c in which the flow rate can be individually adjusted is interlocked with each other, but it is not an interlocking type and a constant quantity supply device such as a pump is provided individually. You may do it.

A mixing tank 9 as a slurry tank is provided with a stirring pump 10, a heater 11 having a thermometer 12, and a cooling device 13 composed of a cooling chiller. The supplied slurry mixed stock solution and pure water are mixed and stirred by the stirring pump 10, and the heater 11 and the cooling device 1 are also used.
By 3, the temperature is adjusted so as to maintain a predetermined temperature.

Further, to the mixing tank 9, for example, a suction side end of a supply pipe 16 constituting a slurry supply line in which a roller pump 14 and a flow meter 15 are incorporated is connected. The end portion of the supply pipe 16 is connected to the slurry discharge portion 18 via a first sluice valve 17 that constitutes a part of the line switching means. Then, the slurry in the mixing tank 9 is sent out through the supply pipe 16 by starting the roller pump 14 at the same time when polishing is started, and the slurry discharge unit 1 through the first sluice valve 17.
8 is supplied to the surface plate 19 on which the polishing of the wafer is performed from the slurry discharge part 18 arranged so as to face the surface plate 19.

A return pipe 20 constituting a slurry return line is provided in the supply pipe 16 immediately upstream of the first sluice valve 17.
Of the second sluice valve 2 forming a part of the line switching means at a position close to the pipe end on the side of connection with the supply pipe 16 while the end thereof is connected to the mixing tank 9.
1 is provided. The second sluice valve 21 is a valve that is always closed during the polishing process and is opened when the polishing process is not performed. The slurry sent from the supply pipe 16 flows through the return pipe 20. Is returned to the mixing tank 9 via the supply pipe 16 and the return pipe 2
0 forms a closed line for circulating the slurry.

On the other hand, the first sluice valve 1 of the slurry discharge section 18
A pure water supply pipe 23 that forms a line for supplying pure water from the pure water supply source 22 is connected to a position immediately downstream of 7. In this case, a third sluice valve 24 that constitutes a line switching means together with the first and second sluice valves 17 and 21 is provided at a position near the pipe end of the pure water supply pipe 23 that is connected to the slurry discharge portion 18. A hand shower nozzle 25 is provided upstream of the third sluice valve 24. Then, when the polishing process is completed and the rinse step with pure water is started, the third sluice valve 24 is opened, and pure water from the pure water supply source 22 is sent to the slurry discharge part 18 through the pure water supply pipe 23. From the slurry discharge part 18 to the surface plate 1
9 to be supplied.

The slurry supply device is constructed as described above, and its operation will be described below.

The slurry stored in the mixing tank 9 is agitated by the agitation pump 10 so that the solid content is settled,
When the temperature is fluctuated, the heater 11 and the cooling device 13 are operated to keep the temperature of the slurry constant, so that the slurry in the mixing tank 9 is constantly subjected to polishing processing. It is placed under optimal conditions for.

When the polishing process is started, the slurry in the mixing tank 9 is sucked into the roller pump 14,
It is delivered through the supply pipe 16 and is supplied onto the surface plate 19 from the slurry discharge section 18 through the first sluice valve 17.

At this time, since the second sluice valve 21 is provided in the return pipe 20 as close as possible to the pipe end on the connection side with the slurry supply pipe 16, the second sluice valve 21 is returned on the upstream side. It is possible to minimize the amount of slurry remaining in the pipe of the pipe 20.

When the polishing process is completed and a rinsing process of cleaning the surface plate 19 with pure water is started, the first sluice valve 1
7 is closed and the second sluice valve 21 is opened. By this valve switching, the slurry sent from the mixing tank 9 through the supply pipe 16 is returned to the mixing tank 9 through the return pipe 20. As described above, the supply pipe 16 and the return pipe 20 form a closed flow path for circulating the slurry, and the slurry circulates without staying in the pipe. At this time, since the return pipe 20 is connected to the supply pipe 16 in a position immediately adjacent to the first sluice valve 17, the residual slurry on the upstream side of the first sluice valve 17 can be minimized.

In the rinsing step, the third sluice valve 24 of the pure water supply pipe 23 is provided at the same time as or before or after the circulation of the slurry.
Is opened, and pure water from the pure water supply source 22 is supplied from the slurry discharge unit 18 onto the surface plate 19 through the pure water supply pipe 23. At this time, since the pure water supply pipe 23 is connected to the slurry discharge section 18 in the immediate vicinity of the first sluice valve 17, the downstream side of the first sluice valve 17 will be washed with pure water. It is possible to reduce the amount of slurry remaining in the pipe on the downstream side of the gate valve 17 and prevent the slurry from adhering to the slurry discharge unit 18.

As described above, when the polishing process is not continued, the slurry is constantly circulated by using the supply pipe 16 and the return pipe 20, so that the slurry stays in the pipe. Therefore, solidification or precipitation in the slurry pipe can be prevented.

In addition, since pure water flows through the slurry discharge section 18 every rinse step, when the polishing process is performed next time, the slurry is cleaned in each rinse step and the slurry is in good condition. Can be supplied to the surface plate.

In the above-described embodiment, the supply pipe 16 forming the slurry supply line is selectively connected to the slurry discharge section 18 and the return pipe 20 forming the slurry return line, and the pure water supply line is formed. The example in which the first to third sluice valves 17, 21, and 24 are used as the line switching means for selectively connecting the pure water supply pipe 23 to the slurry discharge part 18 has been described. , A three-way switching valve corresponding to the second sluice valves 17 and 21, and a three-way switching valve corresponding to the second and third sluice valves 21 and 24.
It may be one three-way switching valve or a multi-way switching valve that switches three lines at the same time.

Further, in the above-mentioned embodiment, an example in which a predetermined amount of pure water is supplied from the pure water tank 7 to the mixing tank 9 by the metering pump 8c is shown, but the pure water tank 7 is provided above the mixing tank 9. A predetermined amount of pure water determined by the liquid level sensor 7A may be supplied by opening the open / close valve 7B. This eliminates the need for the metering pump 8c and at the same time prevents problems such as generation of bacteria due to residual pure water.

[0034]

As described above, according to the present invention, the slurry supply line, the return line, and the pure water supply line are provided, and the slurry is circulated through the slurry supply line and the slurry return line except for polishing. Therefore, it is possible to prevent the slurry from decomposing and deteriorating or solidifying in the pipe.

Further, during the rinsing process of cleaning with pure water, pure water is supplied from the slurry discharge part onto the surface plate, so that the slurry is prevented from remaining or adhering around the slurry discharge part. You can

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a slurry supply device embodying the present invention.

[Explanation of symbols]

 8 Quantitative Supply Device 9 Mixing Tank 10 Stirring Pump 12 Thermometer 13 Cooling Device 14 Roller Pump 16 Supply Pipe 17 First Gate Valve 18 Slurry Discharge Section 19 Plate 20 Return Pipe 21 Second Gate Valve 22 Pure Water Supply Source 23 Pure Water supply pipe 24 Third sluice valve

Claims (2)

[Claims] 1. A slurry supply device for supplying a slurry used as an abrasive to a surface plate for polishing a wafer, wherein the slurry in a slurry tank is delivered to a slurry discharge section provided so as to face the surface plate. For supplying a slurry, a slurry return line for returning the slurry, which has been drawn from the upstream of the slurry discharge portion of the slurry supply line and sent through the slurry supply line to the slurry tank, and a pure water supply source. Out, and a pure water supply line connected immediately upstream of the slurry discharge unit on the downstream side of the slurry return line, the slurry supply line to the slurry discharge unit, and a pure water supply line to the slurry return line. And line switching means selectively connected to the slurry supply line. Characteristic slurry supply device. 2. The line switching means is on a slurry supply line, a first gate valve provided between a connection portion between the slurry return line and the pure water supply line, and a slurry supply line on the return line. And a third sluice valve provided at the pipe end on the side of connection with the slurry supply line on the pure water supply line. The slurry supply device according to claim 1.