JP2001287160A - Polishing end point detecting apparatus and CMP apparatus having the same - Google Patents

Abstract

[PROBLEMS] To provide a polishing end point detection device capable of improving the throughput of a polishing step by more accurately detecting the polishing end point of the same film type of a substrate to be polished, and a CMP apparatus having the same. SOLUTION: The polishing end point detecting device according to the present invention comprises a CM
When the P polishing is performed, the polishing end point is detected. The polishing end point detecting device is disposed next to the turntable 11 on which the polishing cloth 13 is placed, and supports a wafer 15 during polishing, an optical window 23 provided on the support 21, A light emitting element 20 disposed below the optical window 23 for irradiating the polished surface of the wafer 15 with light for detecting an end point.
A light-receiving element disposed below the optical window 23 for receiving reflected light of the light illuminated on the polished surface by the light-emitting element 20, and a detecting means for detecting a change in light received by the light-receiving element And

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing end point detecting device and a CMP device provided with the same. In particular, the present invention relates to a polishing end point detecting device capable of improving the throughput of a polishing process and a CMP device provided with the same.

[0002]

2. Description of the Related Art FIG. 2A is a plan view schematically showing a conventional CMP (Chemical Mechanical Polishing) apparatus provided with a conventional polishing end point detecting apparatus, and FIG.
It is sectional drawing along the 2b-2b line shown to (a). CM
The P device has a disk-shaped turntable 111, and a rotary motor (not shown) is arranged on the lower surface of the turntable 111 via a rotary shaft (not shown). A light emitting element 123 and a light receiving element (not shown) are arranged below the turntable 111. The turntable 111 is provided with an optical window (hole) 120. When the turntable 111 is rotated as shown by the arrow and the optical window 120 is positioned above the light emitting element 123, the light emitted by the light emitting element 123 is transmitted to above the turntable 111 through the optical window 120. Has become. The light emitting element 123, the light receiving element, the optical window 120, and the like constitute a polishing end point detecting device.

[0003] A polishing cloth 113 is mounted on the upper surface of the turntable 111. Above the turntable 111, a wafer suction head 11 as a wafer holding unit is provided.
A rotation motor (not shown) is disposed above the wafer suction head 117 via a rotation shaft 118. During polishing, the wafer suction head 117 is positioned above the light emitting element 123. A nozzle (not shown) for discharging a slurry (not shown) is disposed above the turntable 111.

When a wafer as a substrate to be polished is polished by the above-mentioned CMP apparatus, first, wafer holding means 117 is polished.
The lower surface of the wafer 115 is vacuum-sucked to the lower part of the wafer. And
FIG. 2A shows the turntable 111 being rotated by a rotating motor.
, The slurry is discharged from the nozzle, and the slurry is dropped near the center of the polishing cloth 113. Next, the wafer holding means 11 is rotated by a rotation motor.
7 is rotated in the direction of the arrow, and the surface (polished surface) of the wafer 115 is pressed against the polishing cloth 113. The light emitted by the light emitting element 123 while polishing the wafer 115 is irradiated onto the polished surface of the wafer 115 through the optical window 120, and the light reflected by the polished surface is reflected on the optical window 1.
The light is received by the light receiving element through 20. The change in the received light is detected, and the polishing end point of the wafer 115 is detected.
The polishing of the wafer is terminated at the end point of the polishing.

[0005]

In the above-mentioned conventional polishing end point detecting device, the turntable 111 is provided with an optical window 120, and the optical window 120 is rotated by one turn of the turntable 111. 115), the polishing end point is detected by observing the polished surface of the wafer by the method described above at that time.
For this reason, the light for performing the end point detection is applied to the polished surface of the wafer only when the optical window 120 is positioned below the wafer. Therefore, since the time for observing the polished surface of the wafer is very short, it has been difficult to accurately detect the polishing end point of the wafer.

In the above conventional polishing end point detecting device,
It is relatively easy to detect the end point of a heterogeneous interface that terminates polishing when two or more types of films are exposed. In other words, starting from polishing one type of film, and then finishing polishing when another type of film is exposed as the polishing proceeds, it is determined whether or not another type of film is exposed as described above. It is relatively easy to detect by the method. However, it is difficult to detect the end point of the same film type interface (especially an interlayer insulating film) that terminates polishing when only one type of film is planarized. Therefore, as a method for detecting the end point of the same film type interface, there is no particularly effective means other than the method based on the polishing time derived from the polishing rate. For this reason, when polishing the interlayer insulating film by CMP, it was necessary to polish in two steps, and the throughput was poor. That is, the interlayer insulating film is polished to a certain thickness in one step, and then the thickness of the interlayer insulating film is measured to detect the remaining polishing thickness of the interlayer insulating film. Since the polishing had to be performed in steps, the throughput was poor.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above circumstances, and has as its object to improve the throughput of the polishing process by more accurately detecting the polishing end point of the same film type on the substrate to be polished. An object of the present invention is to provide a polishing end point detecting device and a CMP device having the same.

[0008]

SUMMARY OF THE INVENTION A polishing end point detecting device according to the present invention is a polishing end point detecting device for detecting a polishing end point during CMP polishing, and is arranged next to a rotary table on which a polishing cloth is placed. A support for supporting a substrate to be polished at the time of polishing, an optical window provided on the support, and an optical window disposed below the optical window for irradiating the polishing surface of the substrate with light for end point detection. A light-emitting element, a light-receiving element disposed below the optical window, for receiving reflected light of the light emitted to the polished surface by the light-emitting element, and a detecting means for detecting a change in light received by the light-receiving element And characterized in that:

According to the above-mentioned polishing end point detecting device, a support table is arranged next to the rotary table, an optical window is provided on the support table, and a light emitting element is arranged below the optical window. Thus, since the light can always be applied to the polished surface of the substrate to be polished by the light emitting element, the optical polishing end point of the polished surface can be detected in real time. In other words, light emitted by the light emitting element while polishing the substrate to be polished is applied to the polished surface of the substrate to be polished through the optical window, and light reflected by the polished surface is received by the light receiving element through the optical window. . The change in the received light is detected by the detection means, and the polishing end point of the substrate to be polished is detected. Thus, the optical polishing end point of the polished surface can be detected in real time. Accordingly, the polishing end point at the same film type interface can be detected more accurately. Therefore, the throughput of the polishing step can be improved.

[0010] A CMP apparatus according to the present invention is a CMP apparatus provided with a polishing end point detecting device for detecting a polishing end point of a substrate to be polished. The CMP apparatus is arranged next to a rotary table on which a polishing cloth is placed. A support for supporting the polishing substrate, an optical window provided on the support, and a light emitting element disposed below the optical window and irradiating the polishing surface of the substrate to be polished with light for detecting an end point, A light receiving element disposed below the optical window and receiving reflected light of the light illuminated on the polished surface by the light emitting element; and detecting means for detecting a change in light received by the light receiving element. It is characterized by doing.

[0011] A CMP apparatus according to the present invention includes a rotatable turntable on which a polishing cloth is mounted on an upper surface, a support table disposed next to the turntable and supporting a substrate to be polished during polishing, And rotatable holding means for holding the substrate to be polished, disposed above the turntable, pressing means for pressing the holding means against the turntable and the support table, and slurry disposed above the turntable. Discharge means for discharging the polishing cloth, an optical window provided on the support, and a light emitting element disposed below the optical window and irradiating the polishing surface of the substrate to be polished with light for detecting an end point. A light receiving element disposed below the optical window and receiving reflected light of the light illuminated on the polished surface by the light emitting element; and a detecting means for detecting a change in light received by the light receiving element. Characterized by comprising the, the.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1A is a plan view schematically showing a CMP apparatus provided with a polishing end point detecting device according to an embodiment of the present invention, and FIG. 1B is a plan view of FIG.
FIG. 2 is a cross-sectional view taken along line 1b-1b shown in FIG.

The CMP apparatus has a disk-shaped turntable 11, and a rotation motor (not shown) is provided on a lower surface of the turntable 11 via a rotation shaft (not shown).
Is arranged. A polishing cloth 13 is placed on the upper surface of the turntable 11. Above the turntable 11, a wafer suction head 17 as a wafer holding means is provided.
A rotary motor (not shown) is disposed above the wafer suction head 17 via a rotary shaft 18. The wafer suction head 17 is configured to be movable in a direction of an arrow 19 by a moving means (not shown). A nozzle (not shown) for discharging a slurry (not shown) is disposed above the turntable 11.

A fixed disk-shaped support 21 is arranged next to the turntable 11. The surface of the support 21 is preferably made of a material similar to or close to that of the polishing cloth 13. The surface of the support 21 is located on substantially the same plane as the surface of the polishing cloth 13. This support 21 is used when the entire polished surface of the wafer 15 is not on the polishing cloth 13 of the turntable 11 at the time of polishing,
In the case where a part of the polishing surface of the wafer 5 is on the turntable 11, the remaining portion of the wafer 15 is supported by the support 21 so that the polishing surface of the wafer 15 is
To make parallel contact with the surface.

The support table 21 is provided with an optical window (hole) 23 having a horizontally long plane shape. A light emitting element 20 and a light receiving element (not shown) are arranged below the optical window 23, and a detecting means (not shown) for detecting reflected light is connected to the light receiving element. Each of the optical window 23 and the light emitting element 20 has a shape elongated in the direction of the diameter of the wafer during polishing. Various light-emitting elements can be used as the light-emitting element 20, and various light-receiving elements can be used as long as they can receive light reflected from the polished surface of the wafer and observe the wavelength and intensity of the light. It can be used. For example, as the light emitting element 20 and the light receiving element, it is preferable to use an optical film thickness detection array,
Other elements may be used, and it is also possible to use an optical detector in which a plurality of diodes are arranged.

The specific structure of the optical film thickness detection array includes a white light source (a single wavelength is also possible) arranged in the diameter direction of the wafer and a CCD array arranged in the same manner. And irradiates the light to the C
It is configured to detect with a CD array. In addition, the specific configuration of the optical detector composed of a diode has a light emitting diode arranged in the diameter direction of the wafer and a phototransistor that detects reflected light arranged in the same manner, and transmits light from the light source to the wafer surface. Irradiate and reflect light reflected from it
It is configured to detect with a D array.

During polishing, the wafer suction head 17 is mainly
The polishing is performed in a state where the wafer 15 is always located on the optical window 23 at a position as shown in FIG. The light emitted by the light emitting element 20 is sent above the support base 21 through the optical window 23, the light is reflected on the polished surface of the wafer, and the reflected light is sent to the light receiving element through the optical window 23. ing. The light emitting element 20, the light receiving element, the detecting means, the optical window 23, and the like constitute a polishing end point detecting device.

When polishing a wafer as a substrate to be polished in the above-mentioned CMP apparatus, first, a wafer suction head 17 is polished.
The lower surface of the wafer 15 is vacuum-sucked to the lower part of the wafer. Then, the turntable 11 is rotated in the direction of the arrow shown in FIG. 1A by the rotation motor, and the slurry is discharged from the nozzle, and the slurry is dropped near the center of the polishing cloth 13.

Next, light for detecting the end point is emitted from the light emitting element 20 to the upper side of the support 21 through the optical window 23. Then, the wafer suction head 17 is rotated by the rotation motor.
Is rotated in the direction of the arrow, and the surface (polished surface) of the wafer 15 is rotated.
Is pressed against the polishing cloth 13 and the wafer suction head 1 is further pressed.
7 presses the wafer from the back side with air. At this time, the center of the polishing surface of the wafer 15 is positioned near the outer periphery of the polishing cloth 13 and near the outer periphery of the support 21. Thus, during polishing, a part (nearly half) of the polished surface of the wafer is pressed against the polishing cloth, and the other part of the polished surface of the wafer is pressed against the support 21. As a result, the wafer polishing surface is polished by the polishing cloth 13 and the support table 2 is polished.
The optical polishing end point of the wafer polished surface is always detected by the end point detecting light emitted through the one optical window 23.
That is, while the wafer 15 is being polished, the light emitted from the light emitting element 20 is applied to the polished surface of the wafer 15 through the optical window 23, and the light reflected by the polished surface is transmitted to the optical window 2.
The light is received by the light receiving element 3. The change in the received light is detected by the detecting means, and the polishing end point of the wafer 15 is detected. The polishing of the wafer is terminated at the end point of the polishing.

It is preferable to polish the wafer while moving the wafer suction head 17 as indicated by an arrow 19 when polishing the wafer. Further, by moving in this way, the center of the wafer polishing surface can be positioned above the optical window 23, and the center of the polishing surface can be irradiated with light for detecting the end point. As a result, it is possible to detect the end point of the central portion of the wafer polishing surface.

According to the above embodiment, the support table 21 is provided next to the turntable 11, and the optical window 23 is formed in the support table 21. For this reason, it is possible to detect the polishing end point of the wafer 15 more accurately than the conventional polishing end point detecting device. In other words, in the conventional polishing end point detecting device, the light for performing the end point detection is applied to the polished surface of the wafer only when the optical window is located below the wafer,
In the present embodiment, since the time for observing the wafer polished surface is extremely short, the light can always be applied to the wafer polished surface as described above. Can be. Therefore, the polishing end point of the substrate to be polished such as a wafer can be detected more accurately and easily.

In the above embodiment, the polishing end point at the same film type interface on the substrate to be polished can be detected more accurately. That is, unlike the conventional polishing process, it is not necessary to perform polishing in two steps, and even in the polishing process of the same film type interface, polishing can be performed in one step. Thereby, the throughput of the polishing step can be improved.

That is, when the flatness increases at the same film type interface, the reflected light from the polished surface observed by the light receiving element also changes as compared with the case where it is not flat. Therefore, the end point of polishing at the same film type interface can be detected by detecting the change in the light with high sensitivity. On the other hand, in the conventional polishing end point detecting device, the light for performing the end point detection is applied to the wafer polished surface only when the optical window is located below the wafer, and the wafer polished surface is observed. Since the time is very short, a change in light cannot be detected with sufficient sensitivity. In the present embodiment, it is also possible to detect the polishing end point at the interface between different kinds of films on the substrate to be polished.

Further, in the above-described embodiment, since a method is employed in which almost half of the polished surface of the wafer 15 which is the substrate to be polished is pressed against the polishing cloth 13, the entire polished surface of the wafer is pressed against the polishing cloth. Conventional CM for polishing
The use area of the polishing cloth 13 can be reduced as compared with the P device. Therefore, the turntable 11 can be made smaller than the conventional one, and accordingly, the polishing cloth 1
3 can also be of small area. Thereby, the cost of the polishing cloth can be reduced.

The present invention is not limited to the above embodiment, but can be implemented with various modifications.

[0026]

As described above, according to the present invention, a polishing end point detecting device which can more accurately detect the polishing end point of the same film type of the substrate to be polished, thereby improving the throughput of the polishing step, and A CMP apparatus having the same can be provided.

[Brief description of the drawings]

FIG. 1A is a plan view schematically showing a CMP apparatus provided with a polishing end point detecting device according to an embodiment of the present invention, and FIG. 1B is a view along line 1b-1b shown in FIG. FIG.

FIG. 2A is a diagram showing a C having a conventional polishing end point detecting device.
It is a top view which shows the outline of an MP apparatus, (b) is (a)
FIG. 2 is a cross-sectional view taken along line 2b-2b shown in FIG.

[Explanation of symbols]

 Reference Signs List 11 turntable 13 polishing cloth 15 wafer 17 wafer suction head 18 rotation axis 19 arrow 20 light emitting element 21 support base 23 optical window 111 turntable 113 polishing cloth 115 wafer 117 wafer suction head 118 rotation axis 120 optical window 123 light emitting element

Claims (3)

[Claims] 1. A polishing end point detecting device for detecting a polishing end point when performing CMP polishing, comprising: a support table which is disposed next to a rotary table on which a polishing cloth is mounted, and which supports a substrate to be polished during polishing; An optical window provided on the support base, a light emitting element disposed below the optical window and irradiating the polishing surface of the substrate to be polished with light for detecting an end point, and disposed below the optical window; A polishing end point detecting device, comprising: a light receiving element for receiving reflected light of light illuminated on the polishing surface by the light emitting element; and a detecting means for detecting a change in light received by the light receiving element. . 2. A CMP apparatus provided with a polishing end point detecting device for detecting a polishing end point of a substrate to be polished, wherein the CMP apparatus is arranged next to a rotary table on which a polishing cloth is placed, and supports the substrate to be polished during polishing. A base, an optical window provided on the support base, a light emitting element disposed below the optical window, and irradiating the polished surface of the substrate to be polished with light for detecting an end point, below the optical window. A light-receiving element that receives reflected light of the light illuminated on the polished surface by the light-emitting element; and a detecting unit that detects a change in light received by the light-receiving element. A CMP device equipped with a polishing end point detection device. 3. A rotatable turntable on which a polishing cloth is mounted on an upper surface, a support table disposed adjacent to the turntable and supporting a substrate to be polished at the time of polishing, and above the support table and the turntable. A rotatable holding unit for holding the substrate to be polished, a pressing unit for pressing the holding unit against a turntable and a support table, and a slurry disposed above the turntable, for discharging a slurry to the polishing cloth. A discharge unit, an optical window provided on the support table, a light emitting element disposed below the optical window, and irradiating the polishing surface of the substrate to be polished with light for detecting an end point; A light receiving element disposed below and receiving reflected light of the light illuminated on the polished surface by the light emitting element; and detecting means for detecting a change in light received by the light receiving element. A CMP apparatus provided with a polishing end point detecting device, characterized by the following.