JPH0569311A - Device for pressure-grinding wafer board - Google Patents

Abstract

PURPOSE:To provide a pressure-grinding device, which can measure pressurized pressure and surface temperature of a board at the time of pressure-grinding a wafer substrate. CONSTITUTION:A pressure sensor 11 and/or a temperature sensor 12 are/is arranged near the adhesion surface of a wafer substrate 3 of a rotary top ring 2, and a light transmitter 13 for converting electric signals from these sensors 11, 12 to light is fitted to the rotary top ring 2, and on the other hand, a light receiver 15 is arranged in a holder 16, which is fitted to a holding member 4, at a position opposite to the light transmitter 13 to receive the optical signal from the light transmitter 13 and convert it to an electric signal. Pressurized pressure and surface temperature of the wafer substrate 3 during the rotary grinding by a grinding level plate 1 can be thereby measured intermittently.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure polishing apparatus for wafer substrates.

[0002]

2. Description of the Related Art A wafer substrate such as a silicon wafer used for manufacturing a VLSI is required to have a flatness which is substantially equal to a manufacturing design rule (design minimum line width). For example, the current design rule for silicon wafers for 4 Mbit DRAM manufacturing is 0.8 μm, so a flatness of ± 0.8 μm is required, and the design rule for silicon wafers for 16 Mbit DRAM manufacturing is 0.6 μm. It is expected that the flatness will be required to be about ± 0.6 μm. As described above, with the progress of the miniaturization technology of LSI, higher accuracy is required for the flatness of the silicon wafer, and the sophistication of the pressure polishing technology for realizing it is desired.

Here, a conventional pressure polishing apparatus for a silicon wafer substrate will be described with reference to FIG. 3 as a typical example. In FIG. 3, 1 is a polishing surface plate (platen) which is supported by a rotating shaft 1a and is rotatable, and 2 is a lower surface which is supported by a rotating shaft 2a parallel to the rotating shaft 1a of the polishing surface plate 1. It is a rotating top ring that allows a plurality of wafer substrates 3 to be bonded to each other. Reference numeral 4 is a disk-shaped holding member that radially holds a plurality of, for example, four rotating top rings 2, and 5 is a pressurizing / pressurizing device such as a cylinder that raises and lowers the holding member 4, one end of which is fixed to a fixed portion 6. Has been done. Then, as shown in FIG. 4, for example, six wafer substrates 3 are radially adhered to the back surface of the rotary top ring 2, and then the rotary top ring 2 is rotated by a pressurizing / pressurizing device 5 as shown in FIG. By rotating the platen 1 while pressing it against the polishing surface, uniform polishing can be performed.

[0004]

By the way, the surface of the wafer substrate is flattened by the above-mentioned polishing operation with the pressure polishing apparatus to obtain a product. There is a problem that the pressure applied to the wafer substrate during pressure polishing and the substrate surface temperature at that time have a great influence on the flatness after polishing, and it is often the case that the above-mentioned required accuracy of flatness cannot be satisfied. ..

Therefore, the pressure applied to the wafer substrate during pressure polishing and the substrate surface temperature may be measured online, and the pressure applied to the rotary top ring and the rotational speed may be controlled based on the data. However, it has been extremely difficult to measure the pressurizing pressure and temperature online in the past. That is, usually, as a means for realizing measurement on a rotating body, for example, a method using FM radio wave communication, a method using a slip ring, and a method using an optical slip ring (optical rotary joint) (see, for example, US Pat. No. 4027945). However, they cannot be applied to a pressure polishing apparatus for polishing a wafer substrate due to the following problems.

First, in the method using FM radio wave communication, there are restrictions on the radio wave frequency band and a large number of measurement points cannot be obtained (for example, a commercially available Meisei Electric Co., Ltd. temperature telemeter has a maximum of 13 points). There are drawbacks such as the time required for transmission processing such as demodulation (for example, 0.4 seconds / point), and measurement problems due to noise problems (a problem common to radio communication).

Next, in the method using the slip ring,
It is difficult to maintain due to the abrasion of electrical contacts, and in addition, since the contamination of dust in a wafer processing process generally gives a fatal impact to the product, it is not possible to use mechanical contact parts such as slip rings in process equipment. It becomes a source of generation and is not preferable. Further, in the case of the method using an optical slip ring, as shown in FIG. 6, a rotating body 7 having a plurality of optical fiber bundles 6 and a non-rotating body 8 are arranged so as to face each other, and a plurality of optical transmitters 9 are provided.
a, 9b, 9c, the optical signals transmitted from a plurality of optical receivers
The optical communication system is configured to receive by 10a, 10b and 10c respectively. However, even in such a method, it is technically difficult to apply the optical fiber bundle 6 to the axis of the rotating body 7 and its surroundings, as it is, as it is to the pressure polishing apparatus.

The present invention has been made in order to solve the above problems of the prior art, and measures the pressurizing pressure and / or the surface temperature of the wafer substrate to be polished and outputs the measurement signal. It is an object of the present invention to provide a pressure polishing device capable of easily performing remote transmission of the.

[0009]

According to the present invention, there is provided a polishing platen which is supported by a rotating shaft and is rotatable, and a plurality of polishing plates which are supported by a rotating shaft parallel to the rotating shaft of the polishing platen and which are provided on the lower surface thereof. In a pressure polishing apparatus for a wafer substrate, which comprises a rotary top ring that allows wafer substrates to be bonded freely and a holding member that radially holds a plurality of these rotary top rings, the rotary top ring is disposed near the wafer substrate bonding surface of the rotary top ring. A pressure sensor and / or a surface temperature sensor, an optical transmitter fixed to the rotating top ring to convert an electric signal from the sensor into light, and a holder mounted on the holding member or outside the machine. An optical receiver disposed at a position facing the optical transmitter and receiving an optical signal from the optical transmitter and converting the optical signal into an electric signal. It is a polishing apparatus.

[0010]

[Operation] According to the present invention, an optical transmitter for optically converting and transmitting a signal measured by a sensor is attached to a rotating top ring, while an optical receiver is fixed and attached at a position facing the optical transmitter. As a result, even if the rotary top ring rotates, the measurement signal from the optical transmitter can be intermittently received by the optical receiver.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a side view showing a partial cross-section of the structure of the pressure polishing device of the present invention. In the figure, 11 is a pressure sensor such as a strain gauge, and 12 is a temperature sensor such as a thermocouple, which are mounted near the bonding surface of the wafer substrate 3 of the rotary top ring 2 in correspondence with the position of the wafer substrate 3. .. 13 is each sensor
It is an optical transmitter that inputs electric signals from 11 and 12 through a signal line 14 and converts it into light, and is attached to the upper surface of each rotary top ring 2 by, for example, one each (here, four in total). 15
Is an optical receiver that receives an optical signal from the optical transmitter 13 and converts it into an electric signal, and faces a holder 16 protruding from the lower surface of the center of the holding member 4 at the height position of the optical transmitter 13. Thus, for example, the same number as the number of the optical transmitters 13 (here, four) is provided. An arithmetic controller 17 has a function of inputting an electric signal from the optical receiver 15 via a signal line 18 and performing arithmetic processing such as averaging and comparison with a set value. Reference numeral 19 denotes a pressurizing pressure controller, which controls the pressurizing pressure of the pressurizing / pressurizing device 5 in accordance with a control signal from the arithmetic controller 17, and controls the pressurizing pressure of the wafer substrate 3 to the polishing surface of the polishing platen 1. Adjust.

In this way, the pressure transmitter and the light transmitter are combined with each other.
Wafer substrate 3 by attaching 13 and optical receiver 15
Since the pressure applied to all the wafer substrates 3 and the temperature of the surface thereof can be intermittently measured and remotely transmitted during polishing, the measurement signals are averaged by the arithmetic controller 17 and previously measured. By comparing the applied pressurization pressure set value P _S and the surface temperature set value T _S respectively, if there is a difference between the two, a control signal is output to the pressurization pressure adjuster 19 accordingly. The amount of pressure reduction of the pressure reduction device 5 is adjusted. Although not shown here, it is also possible to adjust the rotation speed of the rotary top ring 2.

In the above embodiment, the optical transmitter
13 has been described as being attached to each rotating top ring 2 one by one, but the present invention is not limited to this, and it is possible to increase the number according to the number of wafer substrates 3 bonded to the rotating top ring 2. is there. Further, the optical receiver 15 is attached to the holder 16, but if the rotation of the rotating top ring 2 is used, it can be attached to the holder 16A outside the device as shown in FIG. 2 (a). is there.

Further, in the above-mentioned embodiment, the optical receivers 15 have been described as being arranged one by one corresponding to the rotating top ring 2, but as shown in FIG.
13 are arranged by the number of wafer substrates 3, for example, while L
The optical receiver 15 is connected to the optical transmitter 13 by using the character-shaped holder 16B.
It is also possible to arrange them so as to face each other, which enables an almost continuous measurement. Furthermore, at the same time, the pressure sensor 11 and the temperature sensor 12 measure the pressurizing pressure and the surface temperature.
However, the present invention is not limited to this, and either one may be measured.

[0015]

As described above, according to the present invention, the optical transmitter for optically converting the signal measured by the sensor and transmitting it is attached to the rotary top ring, while the optical receiver is opposed to the optical transmitter. Since it is fixed in position and attached, even if the rotating top ring rotates, the measurement signal from the optical transmitter can be easily received by the optical receiver, which enables proper polishing control. Therefore, it is possible to obtain the flatness of the wafer substrate according to the design rule, and therefore, it greatly contributes to the improvement of product quality and yield.

[Brief description of drawings]

FIG. 1 is a side view showing a partial cross-section of an embodiment of a pressure polishing device of the present invention.

2A and 2B are partial side views showing another embodiment.

FIG. 3 is a schematic view showing a conventional example of a pressure polishing device.

FIG. 4 is a perspective view of a conventional rotating top ring.

FIG. 5 is a perspective view illustrating the operation of a conventional pressure polishing device.

FIG. 6 is a sectional view schematically showing an example of a conventional optical slip ring.

[Explanation of symbols]

 1 Polishing surface plate 2 Rotating top ring 3 Wafer substrate 4 Holding member 5 Pressurizing and lowering device 11 Pressure sensor 12 Temperature sensor 13 Optical transmitter 15 Optical receiver 16 Holder 17 Arithmetic controller 19 Pressurizing pressure controller

Claims (1)

[Claims] 1. A polishing platen which is supported by a rotation shaft and is rotatable, and a rotation which is supported by a rotation shaft parallel to the rotation shaft of the polishing platen so that a plurality of wafer substrates can be bonded to its lower surface. In a pressure polishing apparatus for a wafer substrate, which comprises a top ring and a holding member that radially holds a plurality of the rotating top rings, a pressure applying pressure and / or surface is provided near a wafer substrate bonding surface of the rotating top ring. A sensor that measures temperature, an optical transmitter that is fixed to the rotating top ring and that converts an electric signal from the sensor into light, and a position that faces the optical transmitter in the holding member or a holder attached outside the machine. And a light receiver for receiving an optical signal from the optical transmitter and converting the optical signal into an electric signal, the pressure polishing apparatus for a wafer substrate.