JPH0227721A - Polishing device for semiconductor wafer - Google Patents

Abstract

PURPOSE:To measure flatness during the actual polishing work of a polishing surface plate, and to improve the dimensional accuracy of a semiconductor wafer by providing a monitor means monitoring the surface state of the polishing surface of the polishing surface plate during the polishing work in a noncontact manner. CONSTITUTION:A sensor 7 for measuring flatness is arranged in the radial direction of a surface plate 1 just above the polishing surface 2 of a polishing surface plate 1. The sensor 7 is connected to a flatness monitor device 8, and both the sensor 7 and the flatness monitor device 8 constitute a monitor means. A controller 9 conducts required arithmetic processing on the basis of the result of the measurement of flatness with time from the sensor 7 and the device 8, and secularly sets the optimum conditions of polishing of the polishing surface 2. Accordingly, dimensional accuracy including the flatness of the surface to be polished of a wafer is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a polishing technique, and particularly to a technique that is effective when applied to polishing semiconductor wafers.

[Conventional technology]

In the semiconductor wafer polishing process, the semiconductor wafer is held on a polishing plate, and the polishing surface of the wafer is brought into contact with the polishing cloth on the polishing plate, and the polishing plate is rotated and the polishing plate is polished. Semiconductor wafers are polished by rotating and revolving around a surface plate.

In this wafer polishing, if the polishing surface of the polishing surface plate on which the wafer is to be polished is not flat, the flatness of the polished surface of the wafer, which is the object to be polished, will not be ensured. This may cause defects in the semiconductor integrated circuit devices manufactured using the wafer, as it may cause defects in the wafer and may also cause resolution defects in the photoresist process using the wafer. It becomes the cause.

Therefore, in the past, in order to ensure the flatness of the polishing surface plate, the polishing surface plate was stopped as necessary or at regular intervals during the polishing process, and three-point or multi-point straight gauges were manually polished. The flatness of the polished surface is measured by applying it to the polishing surface of a surface plate and checking the presence or absence of a gap between the two.

Incidentally, polishing of semiconductor wafers is described in "Electronic Materials 1982 Special Volume" published by Kogyo Kenkyukai on November 15, 1982, pages 61 to 66.

[Problem to be solved by the invention]

However, the present inventor found that the above-mentioned conventional technology has the following problems.

That is, in the above-mentioned conventional technology, the flatness is measured manually and visually by the operator, so that variations and errors occur in the accuracy. Moreover, there are limits to performing multi-point measurements on the entire surface of the polished surface both in terms of efficiency and technology.

In addition, in the case of the above conventional technology, since the flatness is measured while the polishing surface plate is stopped, the actual amount of dynamic deformation of the polishing surface plate,
Furthermore, it is extremely difficult to accurately know the fluctuations in the amount of deformation due to temperature changes on the polished surface.

Therefore, it is even more difficult to accurately judge the state of wafer flatness due to deformation of the polishing surface, etc., based on the measurement of the flatness of the polishing surface plate, which has many uncertainties, and there are inherent limitations. .

As a result, the flatness of the wafer is lowered, resulting in defects in the wafer, which in turn leads to product defects in semiconductor integrated circuit devices using the wafer.

An object of the present invention is to be able to measure the surface condition including the flatness of the polishing surface of a polishing surface plate during polishing without having to stop the polishing surface plate or relying on manual work, and based on the measurement. An object of the present invention is to provide a semiconductor wafer polishing technique that can improve the flatness of a semiconductor wafer.

The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[Means to solve the problem]

A brief overview of typical inventions disclosed in this application is as follows.

That is, the semiconductor wafer polishing apparatus of the present invention is equipped with a monitoring means for monitoring the surface condition of the polishing surface of the polishing surface plate in a non-contact manner during the actual polishing process.

As this monitoring means, a sensor using an eddy current or an electrostatic window 1 can be used, which is arranged in the radial direction directly above the polishing surface of the polishing surface plate without coming into contact with the polishing surface.

Further, the monitoring means can be connected to a control device that sets polishing conditions for the polishing surface plate and polishing plate.

[Effect]

According to the above-mentioned means, the flatness of the polishing surface of the polishing surface plate during the actual polishing process is measured by the monitor means, so it is more efficient and accurate than manual and visual inspection. Flatness measurements can be made.

As a result, the polishing conditions for the semiconductor wafer can be easily and accurately set based on the measurements by the monitor means, thereby making it possible to significantly improve the flatness of the semiconductor wafer being polished.

〔Example〕

FIG. 1 is a schematic plan view of a semiconductor wafer polishing apparatus according to an embodiment of the present invention, and FIG. 2 is a schematic side view of the polishing apparatus.

In this embodiment, a polishing cloth (not shown) is laid on the upper surface of the polishing surface 2 of the polishing surface plate 1, and the polishing surface plate 1 is rotated in the direction of the arrow by a motor 3, which is its rotational driving means. be done.

The semiconductor wafer 4 polished by the polishing surface plate I is held by the lower surface of the polishing plate 5 by vacuum suction means (not shown). The polishing plate 5 is rotated in the same direction as the polishing surface plate 1 by a motor 6 serving as a rotational drive means, and also revolves around the polishing surface plate 1, so that the semiconductor wafer 4 is moved against the polishing surface 2 of the polishing surface plate 1. It is designed to polish by contacting and pressing it.

Directly above the polishing surface 2 of the polishing surface plate 1 of this embodiment, a sensor 7 (monitoring means) for flatness measurement is arranged in the radial direction of the polishing surface plate 1. That is, this sensor 7 measures the flatness, which represents one of the surface conditions, approximately in the entire radial direction without contacting the polished surface 2 or in a non-contact manner.

This sensor 7 uses, for example, eddy current to
By measuring the amount of deformation during the polishing process, the flatness of the polished surface 2 can be measured in substantially the entire radial direction.

The sensor 7 can also be configured to measure the amount of deformation of the polishing surface 2 during polishing using capacitance.

The sensor 7 is connected to a flatness monitor device 8 (monitor means), and both constitute the monitor means. The flatness monitor device 8 indicates the flatness of the polishing surface 2 measured by the sensor 7, for example, a contour line 8as of the polishing surface 2, a vertical cross-sectional shape 8b of the polishing surface 2, and a deviation amount of the polishing surface 2 from a reference plane. It is configured so that it can be monitored in the form of a measured value of 8C.

The flatness monitor device 8 is connected to a control device 9. The control device 9 performs necessary arithmetic processing based on the flatness measurement results over time from the sensor 7 and the flatness monitor device 8, and can set the optimal polishing conditions for the polishing surface 2 over time. .

Further, this control device 9 is connected to the motors 3 and 6, and can control the motors 3 and 6 according to the optimum polishing conditions described above.

Next, the operation of this embodiment will be explained.

First, a semiconductor wafer 4 such as silicon (Si), which has been sliced from a single-crystal pulled ingot and surface-treated by ramping and etching, is placed on a polishing plate 5.
Hold by vacuum suction.

Then, the attitude of the polishing plate 5 is controlled so that the surface to be polished of the semiconductor wafer 4 faces the polishing surface 2 of the polishing surface plate 1,
The polishing plate 5 is lowered while being rotationally driven by the motor 6, and the surface to be polished of the semiconductor wafer 4 is brought into contact with and pressed onto the polishing cloth (pad) on the polishing surface 2 of the polishing surface plate 1 which is also rotating.

Then, by rotating the polishing plate 1 and the polishing plate 5 at a predetermined rotational speed and revolving the polishing plate 5 with respect to the polishing plate l, the semiconductor wafer 4 is
The surface to be polished is polished by the polishing surface 2 of the polishing surface plate 1.

In this polishing process, the flatness of the polishing surface 2 of the polishing surface plate 1 changes over time for some reason, and the amount of deformation changes depending on the position of the surface, so that it is no longer a flat surface.

Such poor flatness of the polishing surface 2 causes poor flatness of the polished surface of the semiconductor wafer 4, and is one of the causes of product defects in semiconductor integrated circuit devices.

Therefore, in this embodiment, the sensor 7, which is arranged in a non-contact radial direction directly above the polishing surface 2 of the polishing surface plate 1, uses eddy current or capacitance to control the polishing surface 2 during polishing. Flatness is measured over time in substantially the entire radial direction.

The flatness measurement result is sent to the flatness monitor rI from the sensor 7.
Contour line 8as vertical cross-sectional shape 3b of polishing surface 2
, and a measured value 8C representing the amount of deviation from the reference plane.

Further, the flatness monitor device 8 sends the flatness measurement results to the control device 9. The control device 9 executes processing such as necessary calculation processing based on the flatness measurement results over time from the sensor 7 and the flatness monitor device 8, and determines the optimum polishing conditions for the polishing surface 2 of the polishing surface plate l. set over time.

Then, the control device 9 can control the motors 3, 6, etc. according to the set optimal polishing conditions, and automatically continue polishing the semiconductor wafer 4 under the optimal polishing conditions.

As a result, the dimensional accuracy including the flatness of the surface to be polished of the semiconductor wafer 4 is improved, and the polishing surface 2 of the polishing surface plate 1 and the surface to be polished of the semiconductor wafer 4 are better aligned, so that the polishing speed is increased. This improves polishing efficiency.

Dimensional accuracy (including flatness) of semiconductor wafers according to the present invention
As is clear from Table 1, the results of the inventor's comparative experiment on the flatness of a stopped semiconductor wafer (comparative example) are as follows: In the case of the present invention, the dimensional accuracy (including flatness) and polishing efficiency of the semiconductor wafer were significantly improved compared to the comparative example.

Although the invention made by the present inventor has been specifically explained above based on Examples, it goes without saying that the present invention is not limited to the Examples and can be modified in various ways without departing from the gist thereof. Nor.

For example, the sensor 7 may measure the surface condition of the polishing surface 2 of the polishing surface plate 1 without contact using something other than eddy current or capacitance.

Furthermore, the configurations and functions, controlled objects, control methods, etc. of the flatness monitor device 8 and the control device 9 may also be other than those in the embodiments.

In the above explanation, the invention made by the present inventor was mainly applied to the field of application, which is the polishing of silicon semiconductor wafers, but the invention is not limited to this. s
) can also be applied to wafers made of semiconductor materials other than silicon.

〔Effect of the invention〕

A brief explanation of the effects obtained by typical inventions disclosed in this application is as follows.

[1) A device that holds a semiconductor wafer on a polishing plate and polishes it by rotating it on a rotatable polishing surface plate, which monitors the surface condition of the polishing surface of the polishing surface plate during polishing without contact. By being equipped with a monitoring means, it is possible to measure the flatness of the polishing surface plate during the actual polishing process without having to stop the polishing surface plate or relying on manual work or visual judgment by the operator. The dimensional accuracy of semiconductor wafers can be significantly improved.

(2)6 Semiconductor integrated circuit 11iI manufactured using the semiconductor wafer according to (1) above! It is possible to prevent the occurrence of product defects.

(3) Due to (1) above, the polishing surface of the polishing surface plate and the surface to be polished of the semiconductor wafer are better aligned, and there is no need to stop the polishing surface plate for flatness measurement.
Polishing efficiency can be significantly improved.

(4) Since the flatness measurement is performed without contacting the polishing surface of the polishing surface plate, the flatness of the polishing surface is not impaired by the measurement.

(5) The monitoring means is connected to a control device that sets polishing conditions for the polishing surface plate, polishing plate, etc., so that the polishing surface plate, polishing plate, etc. can be automatically adjusted based on the measurement results by the monitoring means. It is possible to automatically perform optimal polishing by controlling the optimal polishing conditions.

[Brief explanation of the drawing]

FIG. 2 is a schematic plan view of a semiconductor wafer polishing apparatus according to an embodiment of the present invention, and FIG. 2 is a schematic side view of the polishing apparatus. 1... Polishing surface plate, 2... Polishing surface, 3... Motor,
4... Semiconductor wafer, 5... Polishing plate, 6...
- Motor, 7... Sensor (monitoring means), 8... Flatness monitoring device (monitoring means), 8a... Contour line, 8
b... Vertical cross-sectional shape, 8C... Measured value, 9... Control device. Agent Patent Attorney Daiwa Tsutsui Diagram

Claims (1)

[Scope of Claims] 1. An apparatus for polishing a semiconductor wafer by holding it on a polishing plate and rotating it on a rotatable polishing surface plate, which is capable of controlling the surface condition of the polishing surface of the polishing surface plate during the polishing process. A semiconductor wafer polishing apparatus characterized by being equipped with a monitoring means for contactless monitoring. 2. A claim characterized in that the monitoring means includes a sensor that is disposed in the radial direction directly above the polishing surface of the polishing surface plate and measures the flatness of the polishing surface using eddy current. Item 1. The semiconductor wafer polishing apparatus according to item 1. 3. The above-mentioned monitoring means is characterized in that it has a sensor arranged in the radial direction directly above the polished surface of the semiconductor wafer and measures the flatness of the polished surface using electrostatic capacitance. 1. The semiconductor wafer polishing apparatus according to 1. 4. The semiconductor wafer polishing according to claim 1, wherein the monitoring means is connected to a control device that sets polishing conditions for the polishing surface plate and the polishing plate. Device.