JPH07171759A - Method for controlling temperature of polishing level block - Google Patents

Abstract

PURPOSE:To stably realize the continuous polishing with high precision with the curvature of the upper surface of a turntable being constant by keeping the temperature of a water-cooled jacket at a constant value. CONSTITUTION:In the method for controlling the temperature of a polishing level block, the temperature of a water-cooled jacket 13 fixed to a turntable 12 of the polishing level block 11 is measured by a thermometer 16, and the temperature of the cooling water to the water-cooled jacket 13 is controlled by this measured temperature through a controller 18 and a solenoid valve 17 to keep the surface temperature of the turntable 12 constant.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of controlling a temperature of a polishing surface plate of a polishing apparatus for a semiconductor substrate, and more particularly to improving the processing accuracy by keeping the temperature of the polishing surface plate constant. .

[0002]

2. Description of the Related Art A conventional method for controlling the temperature of a polishing surface plate will be described with reference to FIGS. The polishing surface plate 11 is composed of a turntable 12 and a turntable 12. The polishing surface plate 11 includes a water cooling jacket 13 for rotating the turntable 12 and cooling the turntable 12, and a polishing cloth 14 attached to the upper surface of the turntable 12. There is. Further, a groove 15 for circulating cooling water is provided in the water cooling jacket 13 in contact with the lower surface of the turntable 12.

On the other hand, as a temperature control member of the polishing surface plate 11, a radiation thermometer 16 for measuring the surface temperature of the polishing cloth 14
An electromagnetic opening / closing valve 17 for controlling cooling water from the measured temperature to the water cooling jacket 13 and a controller 18 for opening / closing the electromagnetic valve 17 are provided. In the polishing process in this configuration, a semiconductor substrate is set on a plate (not shown) on the upper surface of the polishing surface plate 11, that is, the upper surface of the polishing cloth 14, and polishing is performed by rotating the semiconductor cloth while pressing it against the polishing cloth 14 with a pressing head. Instead of the pressing head, the semiconductor substrate set on the carrier is pressed against the polishing cloth 14 by the upper surface plate to perform polishing while applying rotation to the polishing cloth 14.

All of these polishing processes are carried out while supplying a polishing liquid, but the temperature of the polishing surface plate 11 is controlled in order to improve the processing accuracy, that is, to keep the surface curvature of the turntable 12 constant.

The conventional temperature control method is the turntable 12
The radiation thermometer 16 measures the temperature of the polishing cloth 14 attached to the upper surface of the plate during the processing, and the controller 18 opens and closes the electromagnetic opening / closing valve 17 so that this temperature (usually around 40 ° C.) is cooled. The temperature is controlled by supplying or shutting off water to the water cooling jacket 13.

[0006]

The conventional method for controlling the temperature of the polishing surface plate 11 is a method of measuring the surface temperature of the polishing cloth 14 and controlling the cooling water from this temperature to the water cooling jacket 13 as described above. However, the processing heat of the surface of the polishing cloth 14 passes through the polishing cloth 14 and the turntable 12
Since the polishing cloth 14 is normally made of a plastic material and has low thermal conductivity, the surface temperature of the polishing cloth 14 and the surface temperature of the turntable 12 at the time of processing are usually several numbers. There is a temperature difference of degrees.

Moreover, in recent years, low thermal expansion materials have been used as turntable materials in order to prevent thermal deformation due to temperature. These materials generally have poor thermal conductivity, and the control of the cooling water of the water cooling jacket 13 cannot be promptly controlled due to the large volume of the water cooling jacket 13 due to the change in the surface temperature of the polishing cloth 14, so that there is a delay. Is large and it is difficult to keep the surface temperature of the polishing pad 14 constant.

For this reason, in some cases, the surface temperature of the polishing pad 14 is kept constant by adjusting the flow rate of the polishing material at the polishing site. However, the method of adjusting the flow rate of the polishing agent is not a good method because it causes a change in the chemical action of the polishing agent.

Further, when the flow rate of the polishing agent is not adjusted, the quality of the product has been empirically determined by observing how many hours after the start of operation it becomes stable.

Therefore, according to the present invention, it is judged that the change of the surface shape of the turntable 12 is largely due to the heat change of the water cooling jacket 13 having a large volume. Therefore, the temperature of the water cooling jacket 13 is measured, and the water cooling is performed from this temperature. By controlling the cooling water to the jacket 13 to make the surface curvature of the turntable 12 to which the polishing cloth 14 is adhered constant, a highly accurate polishing process can be stably performed and the polishing cloth 14 can be used without changing the flow rate of the polishing agent. It is intended to stabilize the chemical action of the polishing agent by keeping the surface temperature of the above.

[0011]

In order to solve the above problems, a method of controlling the temperature of a polishing surface plate according to the present invention is a method of controlling the temperature of a polishing surface plate of a semiconductor substrate polishing apparatus including a turntable and a water cooling jacket. In the above, the temperature of the water cooling jacket is measured with a thermometer, and the cooling water to the water cooling jacket is controlled so that this temperature becomes a predetermined temperature, the temperature of the turntable surface is kept constant, and The curvature is kept constant.

[0012]

According to the above construction, the temperature of the water-cooling jacket is measured, and the cooling water to the water-cooling jacket is controlled so that this temperature becomes a predetermined temperature to keep the surface temperature of the turntable constant. Keep the surface curvature constant.

[0013]

EXAMPLE A method of controlling the temperature of a polishing surface plate of the present invention is to measure the temperature of a water cooling jacket 13 and control the cooling water to the water cooling jacket by this temperature.

An embodiment of the present invention will be described below with reference to FIG. This drawing shows a polishing apparatus for a semiconductor substrate, and a radiation thermometer 16 for measuring the surface temperature of the water cooling jacket 13 is provided on the side of the water cooling jacket 13.

Further, an electromagnetic opening / closing valve 17 for circulating or blocking the cooling water from the measurement temperature measured by the radiation thermometer 16 to the water cooling jacket 13, and a controller 18 for controlling opening / closing of the electromagnetic opening / closing valve 17 are provided. There is.

With the above construction, during polishing, the surface temperature of the water cooling jacket 13 is measured by the radiation thermometer 16, and the controller 18 turns the electromagnetic on-off valve 17 ON and OFF from the measured temperature to perform water cooling. The cooling water is circulated or cut off to the jacket 13 so that the surface temperature of the water cooling jacket 13 is always kept constant and a stable shape is maintained.

FIG. 4 is a graph showing the relationship (test result) between the temperature of the water cooling jacket 13 and the change in processing accuracy of the semiconductor substrate. As shown in FIG. 4, at the start of processing, the entire surface plate is cooled to room temperature and the processing accuracy is poor. As the polishing processing is repeated, the temperature of the entire polishing surface plate is increased by the processing heat and the processing accuracy is also improved.

In this test, cooling water was controlled so that the surface temperature of the polishing cloth was 38 ° C. at room temperature of about 22 ° C., and polishing was performed as a result. As a result, the temperature of the water cooling jacket 13 was changed from 1 to 6 batches. It was found that as the temperature rises, the processing accuracy improves, and after 6 batches, the processing accuracy stabilizes at 4.02 μm at the temperature of the water cooling jacket 13 of 25.2 to 25.5 ° C.

That is, the processing accuracy is stable in the processing after 6 batches. As a result, as a result of polishing the semiconductor substrate when the temperature of the water cooling jacket reached this temperature, highly accurate processing could be continuously obtained.

Normally, the surface shape of the turntable 12 is finished in a convex shape, a concave shape, or another shape in consideration of the difference in material, size, etc. so as to be an ideal shape in this stable state. .

In the present embodiment, the control of the cooling water to the water cooling jacket has been described with the example of the electromagnetic switching valve, but it is also possible to use a flow rate adjusting valve.

[0022]

According to the present invention, with the above construction, the temperature of the water cooling jacket is measured, and the cooling water to the water cooling jacket is controlled by this temperature to keep the surface temperature of the water cooling jacket constant and turn the water cooling jacket. The curvature of the surface of the table can be stably maintained in a constant shape. Therefore, high-precision polishing can be performed continuously and stably.
Further, in order to make the surface shape of the turntable ideal in a short time, it was possible to initially flow hot water instead of cooling water and then adjust the temperature to a predetermined temperature.

[Brief description of drawings]

FIG. 1 is a perspective view showing a method for controlling a temperature of a polishing surface plate of the present invention.

FIG. 2 is a perspective view showing a conventional temperature control method for a polishing surface plate.

FIG. 3 is a partial cross-sectional view of a polishing platen.

FIG. 4 is a diagram showing changes in temperature and processing accuracy of a water cooling jacket.

[Explanation of symbols]

 11 Polishing surface plate 12 Turntable 13 Water cooling jacket 14 Polishing cloth 16 Radiation thermometer 17 Electromagnetic on-off valve 18 Controller

Claims (1)

[Claims] 1. A method of controlling a temperature of a polishing surface plate of a polishing apparatus for a semiconductor substrate, comprising a turntable and a water cooling jacket, the temperature of the water cooling jacket is measured, and the water cooling jacket is kept at a predetermined temperature. A method of controlling the temperature of a polishing surface plate, wherein the temperature of the surface of the turntable is controlled to be constant by controlling the cooling water to the surface of the turntable.