JP2000133622A - End point detecting device for substrate polishing equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To exactly detect the end point of polishing even when the processing conditions of substrates are different. SOLUTION: This end point detecting device is provided at a substrate polishing device for polishing the surface of a substrate W held by a substrate holder 1 by allowing a polishing mechanism 9 to autorotate and act for detecting the end of polishing accompanied by the progress of the processing. This device is provided with a light projecting part 15 for irradiating the substrate W held by the substrate holder 1 with lights, light receiving part 17 for detecting lights transmitted through the substrate W and displaced according to the level of polishing, moving mechanism 7 for moving the polishing mechanism 9 so that the lights can be normally detected, and control part 19 for judging the end point of polishing based on light intensity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an end point detecting apparatus provided in a substrate polishing apparatus for polishing a substrate surface, for detecting an end point of the processing accompanying the progress of the polishing processing. (Chemical Mechanical Polishin
g) relates to an end point detection device for a substrate polishing apparatus used in the above.

[0002]

2. Description of the Related Art In the field of semiconductor manufacturing, finer circuit patterns have been developed in integrated circuit manufacturing processes, and a CMP process for flattening a substrate surface in order to improve the resolution in an exposure process is often used. It has become In particular,
In recent years, Al has been used for the purpose of improving conductivity.
Due to the introduction of technology using Cu as a wiring material instead of Cu, after the entire surface of the insulating layer on which the required pattern is formed is coated with Cu, a CMP process is performed, and C
The damascene process of leaving u has begun to be used.

[0003] In the CMP step in this damascene process, for example, an apparatus configured to measure a polishing rate using a substrate in advance and perform polishing for a predetermined time determined in accordance with the result is used. .

[0004]

However, the prior art having such a structure has the following problems. That is, in the apparatus having the above-described configuration, there is a problem that a slight difference in the pressing of the polishing brush, the processing temperature, the film quality of the metal layer, and the like causes non-uniform processing results. Also,
A substrate having different processing conditions for each substrate, such as an ASIC, could not be processed at all.

[0005] Therefore, there is an apparatus configured to perform friction of the polishing surface, which changes with the progress of polishing, by detecting a torque signal of a motor that rotates the polishing brush. There is a problem that it is still impossible to accurately detect the end point of polishing because the change in friction is subtle and the change differs depending on the processing conditions. If the end point cannot be accurately detected in this way, dishing or erosion in which the polishing surface is depressed due to excessive polishing occurs, and the thickness of the lower layer of the metal layer becomes uneven, and a phenomenon that normal control cannot be performed occurs. .

The present invention has been made in view of such circumstances, and determines the polishing state based on the light intensity so that the end point of polishing can be accurately detected even if there is a difference in the processing conditions of the substrate. It is an object of the present invention to provide an end point detection device for a substrate polishing apparatus capable of performing the above.

[0007]

The present invention has the following configuration in order to achieve the above object. That is, the invention according to claim 1 is provided in a substrate polishing apparatus for performing a polishing process by rotating the polishing device on the surface of the substrate held by the substrate holding device and performing the polishing process, and the polishing end point as the process proceeds. In an end point detection apparatus for a substrate polishing apparatus for detecting the light, irradiation means for irradiating light to the substrate held by the substrate holding means, and is irradiated from the irradiation means, transmitted through the substrate or reflected by the substrate Detecting means for detecting light displaced in accordance with the degree of polishing, and an optical path for setting the light path formed by the irradiation means and the detecting means in a non-blocking state so that the detecting means can normally detect light. And an end point determining means for determining an end point of polishing based on the light intensity output from the detecting means.

[0008] The invention described in claim 2 is the first invention.
In the end point detection apparatus for a substrate polishing apparatus according to the above, the polishing means, the diameter of which is smaller than the substrate diameter, characterized in that it is configured to polish the entire surface of the substrate while moving. is there.

[0009]

The operation of the present invention described in claim 1 is as follows. Light is emitted from the irradiating means to the substrate held by the substrate holding means, and light which is displaced in accordance with the degree of polishing is detected by the detecting means. Irradiation light from the irradiation means because the polishing means acts on the polished surface of the substrate while rotating, transmitted light transmitted through the polished surface or reflected light reflected on the polished surface may be blocked by the polishing means, The detection means can detect transmitted light and reflected light so that the light path securing means does not block the light path. In the state in which the metal layer is applied to the entire surface of the substrate and the state in which the metal layer is almost polished and removed and the underlying insulating layer is exposed, the transmitted light intensity and the reflected light intensity are larger than at the start of polishing. Because of the displacement, the end point determining means can determine the polishing end point based on the light intensity output from the detecting means.

The above-described optical path securing means includes, for example,
When the polishing means is larger than the substrate, it is an optical path formed in the polishing means by a material transparent to light from the irradiation means, or the polishing means is moved laterally from above the substrate so as not to block the optical path. Transportation means.

According to the second aspect of the present invention, there is provided an apparatus in which the diameter of the polishing means is smaller than the diameter of the substrate, and the polishing means is moved to polish the entire surface of the substrate. Since a part of the substrate surface is exposed, the polishing state can be easily detected by the irradiation unit and the detection unit.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. <First Embodiment> FIG. 1 is a schematic configuration diagram showing a substrate polishing apparatus provided with an end point detecting device according to the present embodiment.

The substrate W is placed on the upper surface of the substrate holder 1 formed slightly larger than its diameter in a horizontal posture with the polished surface facing upward, and an annular holding member provided on the peripheral edge of the substrate holder 1. 3 allows the positioning in the horizontal direction to be performed and held. An optical path member 5 (for example, a glass cylinder) made of a material that is transparent to light, which will be described later, is embedded in one portion of the substrate holder 1. Note that the substrate holder 1 and the holding member 3 correspond to a substrate holding unit of the present invention.

A polishing mechanism 9 is provided above the substrate holder 1 so as to be horizontally movable by a moving mechanism 7. The polishing mechanism 9 includes a rotation motor (not shown), and is attached to a lower portion of the brush attaching portion 11.
Polishing brush 13 formed smaller than the diameter of substrate W
Each is configured to rotate. Further moving mechanism 7
Thus, the entire surface of the substrate W can be polished by moving two-dimensionally. Although not shown, a nozzle for supplying polishing and a liquid to the polishing surface is provided.

A light projecting section 15 for irradiating infrared light as a spot beam B is provided above the optical path member 5, and on the opposite side of the light projecting section 15 across the optical path member 5,
A light receiving unit 17 for detecting infrared light emitted from the light projecting unit 15 and transmitted through the substrate W is provided. In addition,
The light projecting unit 15 corresponds to the irradiating unit of the present invention, and the light receiving unit 17 corresponds to the detecting unit.

The substrate W to be polished has, for example, a structure as shown in FIG. That is, it has a laminated structure in which a metal layer such as a wiring, an insulating layer such as an oxide film, and a metal layer (Cu layer) for planarization are provided on the uppermost portion of the silicon substrate. Then, only the uppermost metal layer is polished by a CMP process, but the polishing end point is flat on the uppermost surface while leaving the metal of the uppermost metal layer only in the concave portion of the insulating layer as shown in FIG. It is at the time of conversion.

At the start of polishing shown in FIG. 2A, the spot beam B emitted from the light projecting unit 15 is detected by the light receiving unit 17 because the uppermost metal layer is thick and has low transmittance. The light intensity is extremely low. However, as the polishing starts and approaches the end point of the polishing as shown in FIG. 2B, the metal layer becomes thinner and the transmittance gradually increases,
The light intensity sharply increases from immediately before the end point to the end point.

The control unit 19 monitors the light intensity of the spot beam B displaced in accordance with the degree of polishing as described above.
It is. The control unit 19 corresponding to the end point determining means of the present invention
Is the time at which the light intensity is monitored from the start of polishing, and the point at which the signal stops rising after a sharp rise in the signal is determined to be the end point of polishing. Based on this, the time when the polishing mechanism 9 polishes the entire surface of the substrate W The polishing mechanism 9 is controlled by controlling the moving mechanism 7 with the substrate W.
Is retracted to the side, and the processing is completed.

The control section 19 takes in the light intensity signal from the light receiving section 17 only when the polishing mechanism 9 which is moved two-dimensionally in the horizontal direction by the moving mechanism 7 does not block the optical path. ing. That is, the optical path member 5 of this embodiment and the moving mechanism 7 correspond to the optical path securing means of the present invention.

The operation at the time of the polishing process by the substrate polishing apparatus configured as described above will be described below.

The substrate W before polishing is placed in the substrate holder 1 in advance.
The level of the output signal is adjusted to around "0" V by adjusting the amplifier of the light receiving unit 17 in the state where the substrate W is mounted, and the level of the output signal is set to "10" in the state where the polished substrate W is mounted. It is preferable to keep it near V in order to increase the detection accuracy.

First, with the polishing mechanism 9 retracted to the side by the moving mechanism 7, the substrate W is placed on the substrate holder 1 with the uppermost metal layer facing upward, and the annular holding member 3
By this, the substrate W is fixed to the substrate holder 1.

Next, when the operator instructs the start of the processing from an operation panel (not shown), the control unit 19 moves the polishing mechanism 9 to the upper portion of the substrate W via the moving mechanism 7 and moves the polishing brush 13 over the entire surface of the substrate W. The polishing process is repeatedly performed by acting while moving.

At the start of the polishing, the output signal of the light receiving section 17 is V _S which is substantially “0” V as shown in FIG. 3, but as the polishing progresses, the output signal starts at a certain time _TE0. Start to grow. Then, Figure 2 in T _E point
Assuming that the degree of polishing has progressed to the state shown in (b), the output signal sharply increases from immediately before that and V _E (=
3.5 V) and almost no change thereafter. Control unit 19 always monitors the amount of displacement per time, it determines T _E time as a polishing end point. Then, at this point, the processing is finished when the polishing mechanism 9 has once polished the entire surface of the substrate W.

As described above, in the state where the metal layer is applied to the entire surface of the substrate and the state where the metal layer is almost polished and removed and the underlying insulating layer is exposed, the transmitted light intensity at the start of polishing is reduced. Displacement is large compared to. Therefore, the light receiving section 17
The control unit 19 determines the end point of polishing based on the light intensity output from the substrate, so that even if the processing conditions of the substrate are different and the thickness of the metal layer is different for each substrate, the polishing is accurately performed. An end point can be detected.

<Second Embodiment> Next, referring to FIG.
Although a substrate polishing apparatus according to an embodiment will be described, the same components as those in the above embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

In this apparatus, a light projecting unit 15 for irradiating visible light as a spot beam B is provided above the optical path member 5.
Is arranged in an inclined posture, while the light emitting unit 1 is
5 is different from the above-described embodiment in that a light receiving unit 17 for detecting visible light reflected from the polished surface of the substrate W emitted from the substrate 5 is provided.

The light emitted from the light projecting section 15 is preferably visible light or ultraviolet light which transmits through the substrate W and is not reflected on the back surface thereof, but is infrared light similarly to the above-described embodiment. You may.

In an apparatus having such a configuration, for example, FIG.
The output signal is displaced as shown in the graph of FIG.

That is, at the start of polishing (FIG. 2A), the visible light spot beam B
Is almost reflected, so that the output signal V _S becomes large. On the other hand, the output signal decreases as the uppermost metal layer is polished and becomes thinner gradually, and sharply from the point of time _TE0 immediately before the end of polishing. The output signal starts to drop. At the polishing end time T _E (FIG. 2B), the output signal V _E is considerably lower than the output signal V _S at the start time.
After that, the output signal becomes almost constant,
It is adapted to determine a polishing end point T _E point based on the displacement amount per hour.

In the second embodiment, since the spot beam B from the light projecting section 15 is reflected by the substrate W and detected by the light receiving section 17, the light path member 5 is connected to the substrate holder 1 There is an advantage that it is not necessary to bury the device in the device and the configuration can be further simplified as compared with the device of the first embodiment.

<Third Embodiment> Next, referring to FIG.
A substrate polishing apparatus according to an embodiment will be described. The same components as those in the above-described embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

This apparatus has a configuration very similar to that of the first embodiment described above, but in this apparatus, the polishing brush 13 of the polishing mechanism 9 is formed slightly larger than the diameter of the substrate W. In addition, the polishing mechanism 9 which rotates on its own is moved to the moving mechanism 7.
When the light path member 5 is moved in the horizontal direction at regular intervals, the light path member 5 is largely moved to a position where the optical path member 5 is exposed as shown by a two-dot chain line in the figure. And the control unit 19
Is designed to determine the polishing end point based on the light intensity when the optical path member 5 is exposed.

<Fourth Embodiment> FIG. 7 shows a substrate polishing apparatus provided with an end point detecting device according to a fourth embodiment.

In this apparatus, the polishing brush 13 is formed slightly larger than the diameter of the substrate W as in the third embodiment.
Although the optical path member 5A is embedded in the substrate holder 1, the same optical path member 5B is embedded in the brush mounting portion 11 and the polishing brush 13 of the polishing mechanism 9.

The controller 19 controls the position of the optical path member 5B due to the horizontal movement and rotation of the polishing mechanism 9 by the moving mechanism 7 for preventing unevenness, and the position of the optical path member 5A of the substrate holder 1 only when the position matches. An output signal from the light receiving section 17 is taken in. Therefore, the end point of polishing can be accurately detected based on the light intensity of the spot beam B displaced according to the degree of polishing, as in the above-described embodiments.

In the first to fourth embodiments described above, the substrate holder 1 is described as not rotating. However, the substrate holder 1 may be rotatable so as to enhance polishing uniformity. Further, instead of forming only a part of the substrate holder 1 with a light transmitting member as in the above embodiment, the entire substrate holder 1 may be formed of a light transmitting material.

In the case where a barrier metal layer for preventing Cu diffusion is formed under the uppermost layer in FIG.
Depending on the material and thickness of the barrier metal, it may not be possible to detect the end point by transmission measurement. In such a case, the end point may be detected by the reflection measurement as in the second embodiment, but by utilizing the fact that the reflectance of the Cu layer rapidly decreases in the visible light region, particularly, from green to blue. It is preferable to use a green or blue spot beam for the light projecting unit 15 in order to increase the accuracy of end point detection.

[0039]

As is apparent from the above description, according to the first aspect of the present invention, the state in which the metal layer is adhered to the entire surface of the substrate and the state in which the metal layer is almost polished and removed and the lower insulating layer is formed. In the state where the layer is exposed, the intensity of the transmitted light and the intensity of the reflected light are largely displaced as compared with the polishing start time. Therefore, the end point determining means determines the polishing end point based on the light intensity output from the detecting means, so that the polishing end point can be accurately detected even if there is a difference in the processing conditions of the substrate.

According to the second aspect of the present invention, when the diameter of the polishing means is smaller than the diameter of the substrate, a part of the substrate surface is exposed, so that the polishing state can be easily detected. it can. Therefore, the end point of polishing can be detected with a relatively simple configuration.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of a substrate polishing apparatus provided with an end point detection device according to a first embodiment.

FIG. 2 is a cross-sectional view for explaining polishing.

FIG. 3 is a graph showing a signal change during a polishing process.

FIG. 4 is a view showing a schematic configuration of a substrate polishing apparatus provided with an end point detection device according to a second embodiment.

FIG. 5 is a graph showing a signal change during a polishing process.

FIG. 6 is a diagram illustrating a schematic configuration of a substrate polishing apparatus provided with an end point detection device according to a third embodiment.

FIG. 7 is a view showing a schematic configuration of a substrate polishing apparatus provided with an end point detection device according to a fourth embodiment.

[Explanation of symbols]

 W ... substrate 3 ... holding member 5 ... optical path member 7 ... moving mechanism 9 ... polishing mechanism 11 ... brush mounting part 13 ... polishing brush 15 ... light emitting part 17 ... light receiving part 19 ... control part B ... spot beam

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Noriyuki Kondo 4-chome Tenjin Kitamachi 1-chome, Horikawa-dori-Terauchi, Kamigyo-ku, Kyoto F-term (reference) 3C034 AA13 AA17 BB93 CA22 CA30 CB03 DD10 DD20 3C058 AA06 AA07 AC02 BA09 BC02 CB01 DA12 DA17 5F004 AA11 CB09 CB16 DB08 EB02

Claims (2)

[Claims] 1. A substrate polishing apparatus for performing a polishing process by rotating a polishing means on a surface of a substrate held by the substrate holding means while rotating the substrate to detect a polishing end point as the processing proceeds. In an end point detection device for a polishing device, an irradiation unit that irradiates light to the substrate held by the substrate holding unit, and is irradiated from the irradiation unit, and the substrate is transmitted or reflected by the substrate according to the degree of polishing. Detecting means for detecting the displaced light; optical path securing means for setting the light path formed by the irradiating means and the detecting means in a non-blocking state so that the detecting means can detect light normally; And an end point judging means for judging an end point of polishing based on the light intensity output from the means. 2. The end point detecting device for a substrate polishing apparatus according to claim 1, wherein the polishing means has a diameter smaller than the substrate diameter, and is configured to polish the entire surface of the substrate while moving. An end point detection apparatus for a substrate polishing apparatus, comprising: