JPH09155722A - Semiconductor wafer polishing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily, accurately detect the polishing amount of semiconductor wafer with a CMP device and increase throughput. SOLUTION: A CMP device 10 is constituted so that a semiconductor wafer 16 is sucked with a suction table 14 for holding, the semiconductor wafer 16 is pressed against a polishing cloth 12, and the polishing cloth 12 and the suction table 14 are rotated to polish the semiconductor wafer 16. The polishing cloth 12 is formed with a high rigidity material such as ceramic or a high molecular resin to prevent sinking down of the semiconductor wafer 16 into the polishing cloth 12 during polishing. A sensor 30 is set in the upper part of the suction table 14, the displacement amount (t) in the pressing direction of the suction table 14 during polishing is measured with the sensor 30, and displacement data corresponding to the displacement amount (t) is outputted to a control part 32. The control part 32 calculates the thickness of the semiconductor wafer 16 based on the displacement data to directly measure the polishing amount. When the semiconductor wafer 16 is polished to the polishing amount target value, polishing is finished.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor wafer polishing apparatus, and more particularly to a CMP (Chemical-Mechano-Polishing) apparatus for chemically polishing the surface of a semiconductor wafer.

[0002]

2. Description of the Related Art A CMP apparatus used as a polishing apparatus for semiconductor wafers uses particles softer than the semiconductor wafer as polishing particles and causes a solid phase reaction between the particles and the semiconductor wafer to cause a contact interface between them. This is an apparatus that produces a heterogeneous substance by the reaction of, and polishes while removing that portion, and has the advantage of high specularity and little process deterioration.

Such a CMP apparatus is provided with a polishing cloth and a suction table for sucking and holding a semiconductor wafer. The semiconductor table is pressed against the polishing cloth by the suction table and the polishing cloth and the suction table are relatively rotated. The surface of the semiconductor wafer. Further, in the CMP apparatus, the detection of the polishing amount (end detection) is as important as the flattening polishing technique, and the accuracy of the end detection affects the yield of products. Since the polishing amount requires processing accuracy on the order of nm, conventionally, end detection is performed by processing time, change in current of a polishing cloth rotating motor, optical measurement, spectroscopic measurement, or the like.

[0004]

However, in the end detection by the conventional CMP apparatus, for example, the detection by the processing time is inaccurate because the polishing amount changes depending on the state of the polishing cloth or the slurry, and it is also difficult to rotate the polishing cloth. The detection based on the current change of the motor can detect the polishing amount of the underlying pattern of the semiconductor wafer and the exposed portion of the wiring, but has a disadvantage that the current change does not correspond to the polishing amount during polishing of the insulating film, and thus cannot be detected.

On the other hand, the detection by optical measurement can obtain processing accuracy on the order of nm. However, in order to detect the polishing amount from the polishing cloth side, if the polishing cloth is made of a soft material (foamed polyurethane, artificial leather, etc.), the semiconductor wafer will sink into the polishing cloth during polishing, so the polishing amount will be accurate. Cannot be detected. In addition, detection by spectroscopic measurement is performed in
Although processing accuracy of the order can be obtained, there is a disadvantage that detection cannot be performed if wiring is formed on a film or a base that does not transmit light on the semiconductor wafer.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a semiconductor wafer polishing apparatus capable of easily and accurately detecting the polishing amount of a semiconductor wafer.

[0007]

In order to achieve the above object, the present invention presses a semiconductor wafer on a suction table while holding it on a polishing cloth, and relatively rotates the suction table and the polishing cloth. In a semiconductor wafer polishing apparatus for polishing a semiconductor wafer by using a high-rigidity material, the polishing cloth is prevented from sinking into the polishing cloth at the time of polishing, and the suction table is pressed in the pressing direction. It is characterized in that the polishing amount of the semiconductor wafer is measured by measuring the amount of displacement of the semiconductor wafer with a sensor.

According to the present invention, the polishing cloth is made of a highly rigid material to prevent the semiconductor wafer from sinking into the polishing cloth during polishing. Then, the amount of displacement of the suction table in the pressing direction during polishing is measured by a sensor to measure the amount of polishing of the semiconductor wafer. Therefore, according to the present invention, since the polishing amount of the semiconductor wafer can be directly measured, the polishing amount of the semiconductor wafer can be detected easily and accurately, and the drawbacks of the conventional detection device can be eliminated.

According to a second aspect of the present invention, the polishing cloth is formed of a highly rigid material such as ceramics or polymer resin.
This can surely prevent the semiconductor wafer from sinking into the polishing cloth during polishing.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a semiconductor wafer polishing apparatus according to the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a structural diagram of a main part of a CMP apparatus to which a semiconductor wafer polishing apparatus according to an embodiment of the present invention is applied. The CMP apparatus 10 shown in FIG.
The semiconductor wafer 16 is suction-held on the lower surface of the suction table 14 with the polishing surface facing downward.

The polishing cloth 12 has a motor 18 at the center of the lower part.
The rotary shaft 20 is fixed, and is rotated at a predetermined speed in the direction indicated by the arrow in the figure by the rotational force of the motor 18. Further, the suction table 14 has a rotary shaft 24 of a motor 22 fixed to a central portion of an upper portion thereof, and is rotated at a predetermined speed in a direction indicated by an arrow in the figure by a rotational force of the motor 22. The motor 22
The rod 28 of the air cylinder 26 is fixed to the upper part of the motor 22 by the expansion and contraction of the rod 28.
And the suction table 14 is moved up and down.

Therefore, the semiconductor wafer 16 is pressed against the surface 12A of the polishing cloth 12 by the downward movement of the suction table 14 due to the extension operation of the rod 28, and the polishing cloth 12 and the suction table 14 are rotated as described above. Is polished to the target value of the polishing amount. Further, during polishing, a slurry (not shown) is supplied between the polishing cloth 12 and the semiconductor wafer 16.

By the way, the polishing cloth 12 is made of ceramic or polymer resin (vinyl chloride, vinyl chloride, vinyl chloride, vinyl chloride, etc.) in order to prevent the semiconductor wafer 16 from sinking into the polishing cloth 12 during polishing.
It is made of a highly rigid material such as polycarbonate.
The suction table 14 is also made of a highly rigid material that does not elastically deform when the semiconductor wafer 16 is pressed against the polishing cloth 12.

On the other hand, a sensor 30 is installed above the suction table 14. This sensor 30 is pressed by the suction table 14 during polishing (vertical direction in the figure).
This sensor 30 measures the displacement amount t of the sensor without contact.
Displacement amount data corresponding to the displacement amount t measured in (3) is output to the control unit 32. As the sensor 30, nm
It is preferable to use an optical sensor (laser, triangulation), a capacitance sensor, an eddy current sensor, or the like that can measure the order.

When the displacement amount data is output from the sensor 30, the controller 32 determines the displacement amount t and the thickness dimension of the suction table 14 from the height dimension H of the sensor 30 with respect to the surface 12A of the polishing cloth 12. Subtract A and. The dimensions H and A are previously stored in the control unit 32, that is, the control unit 32 controls the semiconductor wafer 16 being polished by the subtraction.
Calculate the thickness of. Then, the controller 32 stops the motor 22 and the air cylinder 26 when the thickness of the semiconductor wafer 16 reaches the polished amount target value, that is, when the end is detected, and finishes the polishing process.

Next, the operation of the semiconductor wafer polishing apparatus configured as described above will be described. First, the suction table 14 is moved upward by a predetermined amount to move the semiconductor wafer 16
Is suction-held on the suction table 14. Next, the suction table 14 is moved down to remove the semiconductor wafer 16 from the polishing cloth 1.
The polishing pad 12 and the suction table 14 are rotated while being pressed against the second surface 12A, and polishing of the semiconductor wafer 16 is started.

The semiconductor wafer 16 being polished is the polishing cloth 1
Since 2 is made of a high-rigidity material, it is polished without sinking into the polishing cloth 12 even if it is pressed against the polishing cloth 12. The thickness of the semiconductor wafer 16 being polished is determined by the suction table 1 output from the sensor 30 as described above.
It is calculated by the controller 32 based on the displacement amount t of 4. Then, the control unit 32 stops the motor 22 and the air cylinder 26 when the thickness of the semiconductor wafer 16 reaches the polished amount target value, and ends the polishing process.

As described above, in the present embodiment, the polishing cloth 1
2 is formed of a high-rigidity material to prevent the semiconductor wafer 16 from sinking into the polishing cloth 12 during polishing, and the sensor 30 measures the displacement amount t of the suction table 14 during polishing.
The polishing amount of the semiconductor wafer 16 is measured by measuring with. Therefore, in the present embodiment, since the polishing amount of the semiconductor wafer 16 can be directly measured, the polishing amount of the semiconductor wafer 16 can be easily and accurately detected. Further, this can improve the yield and throughput of the semiconductor wafer 16.

[0019]

As described above, according to the semiconductor wafer polishing apparatus of the present invention, the polishing cloth is made of a highly rigid material to prevent the semiconductor wafer from sinking into the polishing cloth during polishing, and Since the polishing amount of the semiconductor wafer is directly measured by measuring the amount of displacement of the suction table in the pressing direction by the sensor, the polishing amount of the semiconductor wafer can be easily and accurately detected.

[Brief description of the drawings]

FIG. 1 is a structural diagram of a main part of a CMP apparatus to which a semiconductor wafer polishing apparatus of the present invention is applied.

[Explanation of symbols]

 10 ... CMP apparatus 12 ... Polishing cloth 14 ... Suction table 16 ... Semiconductor wafer 30 ... Sensor 32 ... Control unit

Claims (2)

[Claims] 1. A semiconductor wafer polishing apparatus for polishing a semiconductor wafer by pressing the semiconductor wafer onto a polishing cloth while holding the semiconductor wafer on the suction table and rotating the suction table and the polishing cloth relative to each other. By forming the polishing cloth with a high-rigidity material to prevent the semiconductor wafer from sinking into the polishing cloth during polishing, the amount of polishing of the semiconductor wafer can be increased by measuring the displacement of the suction table in the pressing direction with a sensor. A semiconductor wafer polishing apparatus characterized by being measured. 2. The semiconductor wafer polishing apparatus according to claim 1, wherein the polishing cloth is made of a highly rigid material such as ceramic or polymer resin.