JPH10329014A - Wafer polishing device attached with heat insulating mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wafer polishing device attached with a heat insulating mechanism capable of measuring wafer polishing quantity without an error. SOLUTION: A porous plate 54 is fitted to a table composing a wafer retaining head 14 and a wafer 52 is fitted to the table through the porous plate 54. By providing a pump 42 for supplying cooling air to the porous plate 54 and supplying cooling air to the porous plate 54 from the pump 42, wafer working heat is prevented from being transmitted to the table from the wafer 52. Thus thermal expansion of the table can be prevented therefore wafer 52 polishing quantity can be accurately measured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wafer polishing apparatus, and more particularly to a wafer polishing apparatus with a heat insulating mechanism capable of measuring a polishing amount of a wafer during polishing of the wafer.

[0002]

2. Description of the Related Art With the recent increase in the density and the number of layers of semiconductor devices, it has been required to flatten wafers with high precision in the manufacturing process. As a method of flattening a wafer, there is a method in which a wafer is pressed against a rotating polishing platen, a slurry is supplied to a contact surface thereof, and polishing is performed while measuring a polishing amount in real time.

The measurement of the polishing amount is performed by providing a sensor on the wafer holding head. That is, a wafer holding head, a table to which a wafer is attached,
The table includes a casing that supports the urging member, and the sensor is provided between the table and the casing, and a polishing amount of the wafer is measured based on information indicating a table variation from the sensor. .

On the other hand, a conventional polishing apparatus employs a wafer polishing apparatus in which a retainer ring surrounding the periphery of a wafer is provided on a casing, and the retainer ring and the wafer are pressed against a rotating polishing platen to polish the wafer. Have been. According to this polishing apparatus, stress concentration from the polishing platen to the wafer edge can be prevented, so that the entire polishing surface of the wafer can be uniformly polished.

[0005]

However, in the conventional wafer polishing apparatus, since the processing heat generated during the polishing of the wafer is transmitted from the wafer to the table and the table thermally expands, the accurate fluctuation amount of the table is reduced. Cannot be detected, resulting in a measurement error in the wafer polishing amount.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a wafer polishing apparatus with a heat insulating mechanism that can measure a wafer polishing amount without error.

[0007]

In order to achieve the above object, according to the present invention, a table on which a wafer is mounted is supported on a casing via an urging means, and the wafer is supported by the urging force of the urging means. Is pressed against a polishing platen to polish, and during the polishing, a wafer polishing apparatus that obtains a polishing amount of a wafer based on information indicating a table fluctuation amount from a sensor provided between a table and a casing. By attaching the wafer to the table via a porous member and providing a fluid supply unit for supplying a cooling fluid to the porous member, and supplying a cooling fluid to the porous member from the fluid supply unit. In addition, the present invention is characterized in that the heat of wafer polishing is prevented from conducting from the wafer to the table.

According to the first aspect of the present invention, when the cooling fluid is supplied to the porous member from the fluid supply means, the heat of the wafer polishing process is insulated before the heat is transferred from the wafer to the table. Can be prevented. Therefore, according to the present invention, the wafer polishing amount can be measured without error. The invention according to claim 2 is directed to a wafer polishing apparatus with a retainer ring, in which a porous member is provided between the retainer ring and a casing, and a cooling fluid is supplied to the porous member from fluid supply means. This prevents heat from the ring from being conducted to the casing, thereby preventing thermal expansion of the casing. Therefore, the present invention can provide a wafer polishing apparatus with a retainer ring that can measure the wafer polishing amount without error.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a wafer polishing apparatus with a heat insulating mechanism according to the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is an overall configuration diagram of a wafer polishing apparatus to which a wafer polishing apparatus with a heat insulating mechanism of the present invention is applied. As shown in FIG.
Numeral 0 includes a polishing platen 12 and a wafer holding head 14. The polishing platen 12 is formed in a disk shape, and a polishing cloth 16 is attached to an upper surface thereof. In addition, a spindle 18 is connected to a lower portion of the polishing table 12, and the spindle 18 is connected to an output shaft (not shown) of a motor 20. When the motor 20 is driven, the polishing platen 12 rotates in the direction of arrow A, and a slurry 24 is supplied from a nozzle 22 shown in FIG. 2 onto the polishing cloth 16 of the rotating polishing platen 12.

FIG. 2 is a longitudinal sectional view of the wafer holding head 14. The wafer holding head 14 shown in FIG. 1 includes a casing 26, a table 28, and the like. The casing 26 is formed in a cup shape with an open lower part, and a rotating shaft 30 for rotating the casing 26 in the direction of arrow B is fixed to the upper surface thereof. Also, casing 2
6, air supply paths 32 and 34 are formed, and these air supply paths 32 and 34 are communicated with air supply paths 36 and 38 formed on the rotating shaft 30. A valve 40 and a pump 42 for supplying compressed air are connected to the air supply paths 36 and 38.

The table 28 is housed in the casing 26 and has springs (biasing means) 44,44.
And is supported by the casing 26 through the casing so as to be vertically movable. The upper edge of the table 28 is supported in contact with elastic members 46, 46 fixed to the casing 26, so that the upward movable position with respect to the casing 26 is regulated. The table 28 is provided with the elastic member 4.
The rotational force from the casing 26 is transmitted via the casings 6 and 46.

By the way, the casing 26 and the table 28
Between them, a differential transformer type electric micrometer (sensor) 51 is provided. This electric micrometer 51
Is composed of a core 48 and a bobbin 50. The core 48 is fixed downward on the casing 26 side, and the bobbin 50 is fixed upward on the table 28 side. The electric micrometer 51 detects a vertical fluctuation amount of the table 28 with respect to the casing 26, and measures a polishing amount of the wafer 52 based on the detection result.

On the lower surface of the table 28, a porous plate 5 is provided.
4 is fixed. The porous plate 54 has a number of air passages inside, and for example, a porous plate made of a sintered body of a ceramic material is used. The porous plate 54
Is connected to the air supply passage 32 on the casing 26 side via an air supply passage 56 formed in the table 28. Therefore, after the compressed air from the pump 42 is supplied to the porous plate 54 through the air supply passages 36, 32, and 56, the compressed air is blown downward from the lower surface of the porous plate 54. Thereby, the porous plate 54 is air-cooled,
Wafer processing heat conducted from the wafer 52 to the table 28 is insulated by the porous plate 54. Further, the wafer 52 is floatingly supported by the air blown out from the lower surface of the porous plate 54 and pressed against the polishing pad 16 via the pressure fluid layer L. Therefore, the wafer processing heat is insulated by the pressure fluid layer L in addition to the porous plate 54.

On the other hand, a plurality of sensors 58 are embedded in the porous plate 54. The sensor 58 includes:
It is a non-contact sensor such as an eddy current sensor, and its detection surface 58
A is arranged flush with the lower surface of the porous plate 54. The sensor 58 detects the amount of change in the thickness of the pressure fluid layer L by measuring the distance from the upper surface of the semiconductor wafer 52.

CPU for measuring the amount of polishing of wafer 52
(Not shown) is the polishing amount of the wafer 52 by adding the fluctuation amount of the pressure fluid layer L detected by the sensor 58 to the fluctuation amount of the table 28 detected by the electric micrometer 51 described above. Is calculated. That is, if the variation detected by the electric micrometer 51 is T1 and the variation detected by the sensor 58 is T2, the CPU calculates the polishing amount of the wafer 52 at that time by T1 + T2. The variation from the electric micrometer 51 is T1, and the sensor 5
If the amount of change from 8 is O, the polishing amount of the wafer 52 at that time is calculated as T1. Further, the electric micrometer 5
The variation from T1 is T1, and the variation from sensor 58 is-
If it is T2, the polishing amount of the wafer 52 at that time is T1-
It is calculated by T2.

On the lower surface of the casing 26, a ring-shaped retainer ring 60 is fixed via a porous plate 62 also formed in a ring shape. The retainer ring 60 surrounds the periphery of the wafer 52 and is pressed against the polishing pad 16 together with the wafer 52. In the present embodiment, ceramic having a smaller coefficient of thermal expansion than metal is used. The contact surface 60A of the retainer ring 60 with the polishing pad 16 is coated with diamond to improve durability.

The porous plate 62, like the porous plate 54 provided on the table 28, has a large number of ventilation paths inside, and is made of, for example, a sintered body of a ceramic material. The casing 2 is provided on the porous plate 62.
The air supply path 34 formed in 6 is connected. Therefore, the compressed air from the pump 42 is supplied to the air supply path 3
After being supplied to the porous plate 62 via 8, 34, it is blown out from the peripheral surface of the porous plate 62 to the outside. As a result, the porous plate 62 is air-cooled by the compressed air, so that the retainer ring 6 generated during polishing of the wafer 52 is formed.
The processing heat of No. 2 is insulated by the porous plate 62 and does not conduct to the casing 26 side.

Next, the operation of the wafer holding head 14 of the wafer polishing apparatus 10 configured as described above will be described. First, in FIG. 2, the wafer holding head 14 is rotated by the rotational force of the rotating shaft 30, the valve 40 is opened to drive the pump 42, and the compressed air from the pump 42 is supplied to the porous plates 54 and 62. . The compressed air supplied to the porous plate 54 cools the porous plate 54 while passing through the porous plate 54, and is blown downward from the lower surface of the porous plate 54. Then, the wafer 52 is placed on the porous plate 54.
Is pressed against the polishing pad 16 via the pressurized fluid layer L by the air blown out from the polishing pad and polished.

As a result, the wafer processing heat is insulated by the pressure fluid layer L and the porous plate 54, so that the table 28 can be prevented from being thermally expanded by the wafer processing heat. Therefore, in the present embodiment, it is possible to accurately measure the wafer polishing amount by the electric micrometer 51 and the sensors 58, 58,. On the other hand, since the compressed air from the pump 42 is also supplied to the porous plate 62 on the retainer ring 60 side, heat from the retainer ring 60 is not conducted to the casing 26. Therefore,
In this embodiment, since the casing 26 can be prevented from thermally expanding due to the heat from the retainer ring, the measurement of the amount of polished wafer by the electric micrometer 51 and the sensors 58, 58,. Can be.

In the present embodiment, the wafer holding head 14 with the retainer ring 60 has been described. However, the present invention is not limited to this. For a wafer holding head without the retainer ring 60 and for adsorbing and fixing the wafer 52 to a table. Can also be applied. In this type, since there is no retainer ring 60, the retainer ring 6
The porous plate 62 for air-cooling 0 is unnecessary.

[0021]

As described above, according to the wafer polishing apparatus with the heat insulating mechanism according to the present invention, the wafer is mounted on the table via the porous member, and the cooling fluid is supplied to the porous member from the fluid supply means. By doing so, thermal expansion of the table due to processing heat is prevented, so that the wafer polishing amount can be measured without error.

Further, according to the present invention, a porous member is provided between the retainer ring and the casing, and a cooling fluid is supplied from the fluid supply means to the porous member. Since the expansion is prevented, it is possible to provide a wafer polishing apparatus with a retainer ring capable of measuring a wafer polishing amount without error.

[Brief description of the drawings]

FIG. 1 is an overall structural diagram of a wafer polishing apparatus with a heat insulating mechanism according to the present embodiment.

FIG. 2 is a longitudinal sectional view of a wafer holding head of the wafer polishing apparatus shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Wafer polishing apparatus 12 ... Polishing surface plate 14 ... Wafer holding head 16 ... Polishing cloth 26 ... Casing 28 ... Table 51 ... Electric micrometer 52 ... Wafer 54, 62 ... Porous plate 58 ... Eddy current sensor 60 ... Retaining ring

Claims (2)

[Claims] A table on which a wafer is mounted is supported by a casing via an urging means, and the wafer is pressed against a polishing platen by the urging force of the urging means to polish the table. And a wafer polishing apparatus that obtains a polishing amount of a wafer based on information indicating a table fluctuation amount from a sensor provided between the casing and the wafer, attaching the wafer to the table via a porous member, Fluid supply means for supplying a cooling fluid to the porous member is provided, and by supplying a cooling fluid to the porous member from the fluid supply means, wafer polishing heat is prevented from being conducted from the wafer to the table. A wafer polishing apparatus provided with a heat insulating mechanism. 2. A casing, wherein a retainer ring surrounding the periphery of the wafer is provided through a porous member, and fluid supply means for supplying a cooling fluid to the porous member is provided. 2. The wafer polishing apparatus with a heat insulating mechanism according to claim 1, wherein heat from the retainer ring is prevented from being conducted to the casing by supplying a cooling fluid from the supply means to the porous member.