JPH08139060A - Method of manufacturing semiconductor device and chemical machine polisher - Google Patents

Abstract

PURPOSE: To bury a metal in a connecting hole for flattening the surface of an insulating film using a chemomechanical polishing step comprising a series of processes. CONSTITUTION: An interlayer insulating film 3 is formed on a metallic wiring 2 formed on a semiconductor substrate 1 and after the formation of a connecting hole in the interlayer insulating film 3, a metallic film 6 is formed on the interlayer insulating film 3. This metallic film 6 is polished using an acid polishing solution in a chemomechanical polishing process. In this chemomechanical polishing process, the surface exposed time point of the surface of the interlayer insulating film 3 to the polished surface is detected by the change of revolving torque of a carrier head or the conductivity in the wafer thickness direction to continue the polishing of the metallic film as it is assuming the detection time as the terminal time. Later, the feeding of the polishing solution is stopped to be substituted for pure water for linsing step and then substituting for alkalic polishing solution for insulating film for polishing the interlayer insulating film 3 for flattening the surface. In the polishing step, the metal 6 buried in the connecting hole 4 is used as the polishing stopper of the interlayer insulating film 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device and a chemical mechanical polishing apparatus used for the same, and more particularly to a connection hole (including both a contact hole and a via hole) in a step of forming a multilayer wiring in a wafer process. The present invention relates to a manufacturing method characterized by the process of burying a metal in a metal and flattening the surface of the insulating film in which the connection hole is formed, and an apparatus used therefor.

[0002]

2. Description of the Related Art Recently, with the progress of miniaturization and integration of semiconductor devices, multilayer wiring has become an indispensable technique. However, with the extension of the conventional technology, the absolute step becomes stricter, the margin of photolithography cannot be secured, and the problem that the coverage of the interlayer insulating film and the metal film for wiring cannot be sufficiently secured occurs, and the metal wiring is formed. There is a strong demand for flattening the surface of the insulating film. Therefore, as one method for solving these problems, an approach from the film forming process side of the insulating film is also performed, but although this method can realize partial planarization,
Complete flattening is an extremely difficult situation.

Recently, a chemical mechanical polishing (CMP) technique has been actively studied. In this chemical mechanical polishing, in addition to the conventional simple mechanical polishing technique, when the object to be polished is an insulating material such as a silicon oxide film, a polishing liquid (slurry) prepared to be alkaline is used, and the object to be polished is In the case of a metal film, an acidic polishing liquid is used. As described above, in the chemical mechanical polishing, the polishing liquid is selected according to the object to be polished, so that the chemical polishing is simultaneously performed and the selectivity of the polishing rate between the insulator and the metal is utilized.

As a concrete method utilizing chemical mechanical polishing, a technique of embedding a metal in a connection hole has been proposed.
Here, after forming a metal film to be embedded in a connection hole provided in an insulating film, the metal film is chemically mechanically polished with a polishing liquid that has a polishing rate of the metal film higher than that of the insulating film to form the insulating film. Embedding a metal film in the connection hole as a stopper has been introduced ("Nikkei Microdevice", 1992).
June issue, pp. 66-67). It is also introduced therein that a metal film pattern is formed, an insulating film that covers the metal film pattern is formed, and then the insulating film is polished with a polishing liquid for polishing the insulating film using the metal film as a stopper.

[0005]

In the chemical mechanical polishing as introduced in the above documents, chemical mechanical polishing for the insulating film is performed after the insulating film is formed, or the chemical mechanical polishing for the metal film is performed after the metal film is formed. A chemical mechanical polishing process is performed, such as a chemical mechanical polishing. Therefore, for example, in the method of polishing a metal film and embedding a metal in the connection hole, the flatness of the insulating film surface after polishing largely depends on the initial flatness of the insulating film, and the flatness of the insulating film surface before forming the metal film is large. The unevenness remains even after the chemical mechanical polishing of the metal film. If the contact hole is filled with metal and the insulating film surface is also to be flattened, the insulating film is first planarized by chemical mechanical polishing before forming the metal film, then the connecting hole is formed, and then the metal film is formed. As a result, it is necessary to perform chemical mechanical polishing twice, such as performing chemical mechanical polishing for the metal film again, which increases the number of steps, complicates the process, and raises the manufacturing cost. There is.

According to the present invention, the number of steps is reduced by embedding a metal in the connection hole by using chemical mechanical polishing, flattening the surface of the insulating film, and further enabling the chemical mechanical polishing by a series of processes. It is an object of the present invention to provide a method for suppressing an increase in manufacturing cost and flattening with high stability and reproducibility. The present invention also aims to provide a chemical mechanical polishing apparatus suitable for carrying out such a method.

[0007]

According to the present invention, an insulating film is formed on a semiconductor substrate wafer, a connection hole is formed at a predetermined position of the insulating film, and then a metal film is formed on the insulating film. The back side of the wafer is held by a carrier head, and the front side of the wafer is rotated while being pressed against a polishing pad to perform polishing. The polishing is performed in the following steps (A) to (C).
Is a series of chemical mechanical polishing including. (A) A metal film polishing liquid containing a polishing agent and prepared to increase the polishing rate for metal is supplied between the wafer surface and the polishing pad to expose the insulating film, and to the portion other than the connection hole. A step of polishing the metal film until no metal film remains, (B) a step of rinsing the polishing surface by switching the supply between the wafer surface and the polishing pad from the metal film polishing liquid to water, (C) After that, the supply between the wafer surface and the polishing pad is switched from water to a polishing liquid for an insulating film which contains a polishing agent and is prepared to increase the polishing rate for an insulator, and is embedded in a connection hole. The step of polishing the insulating film by using the metal film as a stopper to flatten the surface of the insulating film. The metal film polishing liquid is an acidic polishing liquid prepared to be acidic or a polishing liquid to which a promoter for promoting metal polishing is added. The insulating film polishing liquid is an alkaline polishing liquid prepared to be alkaline or a polishing liquid to which a promoter for promoting polishing of an insulating material is added.

In a preferred mode, in the step (A) of polishing the metal film, the end point of the metal film polishing is detected from the rotation torque of the carrier head. In the end point detection, a time point when the rotational torque increases to a predetermined magnitude or more, or a time point when the rate of change thereof satisfies a predetermined condition is detected as an end point, and a predetermined amount of polishing is continued after the end point is detected. In another preferred embodiment, in the step (A) of polishing the metal film, the end point of the metal film polishing is detected from the conductivity in the thickness direction of the wafer between the front surface side and the back surface side of the wafer. In the end point detection, the time point when the conductivity falls below a predetermined magnitude, or the time point when the change rate satisfies a predetermined condition is detected as the end point, and a predetermined amount of polishing is continued after the end point is detected. As a preferable example of the metal film, a tungsten film, an aluminum film or an aluminum alloy film, or a copper film can be used.

In the polishing apparatus of the present invention, an upper surface is a horizontal surface, a polishing pad is provided on the horizontal surface, a polishing surface plate that rotates in the horizontal surface and a back surface of a wafer substrate are held, and the front surface of the wafer substrate is polished. A head mechanism that presses against the pad and rotates it in a horizontal plane by applying a load, a measurement system that detects the end point of a certain polishing process, and a polishing liquid for the metal film, a polishing liquid for the insulating film, and pure water are switched onto the polishing pad. And a polishing liquid supply unit that can supply the polishing liquid. The measurement system that detects the end point of a certain polishing process detects the rotational torque of the head mechanism, and when the detected rotational torque reaches a preset reference level, or when the rotational torque change rate reaches a predetermined condition. The rotational torque measurement system that detects the time point when the condition is satisfied and determines the end point, or the conductivity in the thickness direction of the wafer substrate is detected, and the time when the detected conductivity falls below a preset reference level, or further conductivity is detected. This is a conductivity measuring system that detects the time point when the rate of change of the rate satisfies a predetermined condition and sets it as the end point of the polishing step.

An example of the chemical mechanical polishing process of the present invention will be described with reference to FIG. (A) The interlayer insulating film 3 is formed on the metal wiring 2 formed on the semiconductor substrate 1. (B) The connection hole 4 is formed by the photography process and the etching process. (C) A metal film 6 is formed on the interlayer insulating film 3. At this time, if necessary, the adhesion layer 5 is formed prior to the formation of the metal film. All the steps up to this point are known steps.

(D) The back side of the wafer of the semiconductor substrate 1 is held by a carrier head of a polishing apparatus, the front side of the wafer is rotated while being pressed against a polishing pad, and a metal film 6 (adhesion film) is formed by a chemical mechanical polishing process. 5 is formed, the adhesion film 5 is also polished at the same time as the metal film 6. The same applies to the following). As the polishing liquid for this chemical mechanical polishing, a polishing liquid prepared to be acidic for the metal film is used.

The time when the surface of the interlayer insulating film 3 is exposed on the polished surface is detected from the change of the rotation torque of the carrier head and the change of the conductivity in the thickness direction of the wafer, and the time is taken as the end point. At the end point, as shown in the drawing, a part 7 of the metal film still remains in the portion where the surface of the interlayer insulating film 3 is depressed between the metal wirings 2.

(E) Even after the surface of the interlayer insulating film is exposed on the polished surface, the polishing of the metal film is continued for a certain amount to completely remove the part 7 of the metal film remaining in the step (D). . However, at this point, the flatness of the surface of the interlayer insulating film 3 has not been realized so much. While continuing the rotation of the carrier head, at this point the supply of the polishing liquid for the metal film is stopped, and instead pure water is supplied to the polishing surface for rinsing to perform the polishing liquid for the metal film on the polishing surface. Is replaced with pure water.

(F) Thereafter, the supply of pure water is switched and supplied to a polishing liquid for an insulating film which is adjusted to be alkaline, and the interlayer insulating film is polished to flatten the surface of the interlayer insulating film 3.
At this time, it is not necessary to detect the polishing end point, and the metal 6 embedded in the connection hole 4 serves as a stopper for polishing the interlayer insulating film 3. Therefore, the stability and reproducibility of this polishing process can be easily obtained.

The chemical mechanical polishing of the present invention is a series of chemical mechanical polishing including switching of a polishing liquid. The features can be organized as follows. The metal film is polished using a polishing liquid for a metal film, the end point of the metal film polishing is detected, and a predetermined amount of metal polishing is continued even after the end point of the metal film polishing is detected. After the rinsing step, the polishing liquid is switched to the polishing liquid for the insulating film, and the insulating film is polished using the metal as a stopper.

The detection of the end point of polishing the metal film will be described.
Generally, in the chemical mechanical polishing process, the end point is detected when the polishing surface, which is the end point, appears in the area of the object to be polished, but the positional relationship between the carrier head and the polishing surface plate and the capacity For example, when trying to detect based on the amount that changes continuously, there is a problem in detection accuracy and reproducibility. However, when the end point of polishing is found at the interface between different materials, such as when the end point of polishing is found at the interface between the metal film and the insulating film as in the present invention, such a problem does not occur, and polishing is relatively easy. You can find the end point of. In particular, regarding the detection of the interface between the metal film and the insulating film, the amount of change in the rotation torque of the carrier head and the amount of change in the conductivity of the semiconductor substrate wafer are effective information. In the present invention, by obtaining the polishing end point based on these pieces of information, it becomes possible to perform control with excellent process stability and good reproducibility.

The reason why a certain amount of polishing is continued after the end point of the polishing of the metal film is continued is as follows. Generally, the step coverage shape of the interlayer insulating film reflects the underlying metal wiring pattern,
The surface of the interlayer insulating film between the wiring patterns has a depressed shape. By modifying the film forming process of the interlayer insulating film, the depressed shape can be somewhat eliminated. This is so-called partial flattening, but complete flattening is impossible. Therefore,
If a metal film is formed on the interlayer insulating film in this state and the metal film is polished by chemical mechanical polishing, and polishing is stopped when a part of the interlayer insulating film is exposed, the depressed area of the interlayer insulating film surface A part of the metal film formed above remains even at the end of polishing. If the manufacturing process of the semiconductor device is continued in this state, the remaining part of the metal film causes a short circuit between the wirings, leading to a decrease in reliability and yield. Therefore, in the present invention, by polishing a predetermined amount even after the end point of the metal film is detected, a part of the metal film remaining in the depressed region on the surface of the interlayer insulating film is removed. As a result, the present invention does not require a complicated partial planarization process for intentionally flattening the surface of the interlayer insulating film, and contributes to widening the degree of freedom in the step of forming the interlayer insulating film.

The rinsing step of switching from the polishing liquid for polishing the metal film to the pure water, when the acidic polishing liquid is used as the polishing liquid for the metal film, is suddenly changed to the alkaline polishing liquid as the polishing liquid for the insulating film. The main purpose is to prevent the generation of heat and products generated by switching, and it is also useful for clarifying the polishing end point and improving reproducibility. When polishing an interlayer insulating film using a polishing liquid for an insulating film, the end point detection is generally a big problem, but in the present invention, since the metal already embedded in the connection hole can be polished as a stopper, Improves process stability and reproducibility.

[0019]

EXAMPLE FIG. 2A shows a first example of a chemical mechanical polishing apparatus for carrying out the present invention. Reference numeral 21 is a polishing platen, the upper surface of which is a horizontal plane, and is rotated in the horizontal plane by a rotating shaft 22. A polishing pad 23 is attached to the upper surface of the horizontal surface. The back side of the semiconductor wafer 24, which is the object to be polished, is adsorbed and held by the carrier head 25. A load is applied to the carrier head 25 so as to press the surface of the wafer 24 against the polishing pad 23, and the head 25 is rotated by a motor 26 to polish the surface of the wafer 24.

A rotary torque measuring system that detects the rotary torque of the carrier head 25 on the rotary shaft of the carrier head 25 and detects when the detected rotary torque reaches a preset reference level as the end point of the polishing process. 27 are provided. The rotation torque measuring system 27 inputs a rotation monitor 35 which is provided on the rotation shaft of the carrier head 25 and detects the number of rotations of the carrier head 25 by an encoder or the like, and a detection signal of the rotation monitor 35, and communicates from the power supply 37 to the motor 26. Negative feedback control of the current to control the carrier head 25
Drive control unit 36 that keeps the rotation speed constant, and a torque signal S ₁ that corresponds to the current flowing to the motor 26 to keep the rotation speed of the carrier head 25 constant is detected as a voltage value, for example, and the end point of the metal film polishing is detected. And a comparison unit 38a for switching the type of polishing liquid via the valve drive unit 39 in comparison with the reference signal level L ₁ of the rotation torque corresponding to the above.

In order to supply the polishing liquid onto the polishing pad 23, the metal film polishing liquid supply device 28 for supplying the metal film polishing liquid, and the rinse liquid supply device 2 for supplying the pure water for rinsing.
9, and an insulating-film polishing liquid supply device 30 for supplying the insulating-film polishing liquid.
29 and 30 are valves 31 provided at respective outlets,
32 and 33 are selected and supplied. Opening and closing of the valves 31, 32, 33 are controlled by a valve driving unit 39 according to the output of the comparing unit 38a.

An embodiment for carrying out the process shown in FIG. 1 using the apparatus shown in FIG. 2A will be described. For the sample in which the via hole is opened in the interlayer insulating film by the known technique, a TiN film having a thickness of about 500 Å is formed as an adhesion layer by the reactive sputtering method, and then a metal for filling the via hole. As a result, a tungsten film was formed to a thickness of about 8000Å by the CVD method using WF ₆ gas. This sample was set on the carrier head 25 of the chemical mechanical polishing apparatus shown in FIG.

The valve 31 was opened and the metal film polishing liquid was supplied from the metal film polishing liquid supply device 28 onto the polishing pad 23 to polish the tungsten film. The conditions at this time are shown below. Polishing liquid flow rate: 250 ml / min Surface plate rotation speed: 18 rpm Carrier head rotation speed: 700 rpm Carrier head pressure: 5 psi

In a preliminary experiment conducted in advance while monitoring the rotational torque of the carrier head 25 with the rotational torque measuring system 27, a rotational torque change curve as shown in FIG. 2B was obtained. Rotation torque S as indicated by the arrow
_The time when ₁ increases to the reference signal level L ₁ is the time when the area of the interlayer insulating film that appears on the polished surface becomes constant, and that point is taken as the end point of the metal film polishing, and polishing is continued for another 3 minutes from that point. Continuing, the process up to this point was the polishing process for the metal film. Again, as a result of the preliminary experiment under the same conditions, it was confirmed by microscopic observation of the sample surface at this point that no tungsten film remained in the depressed region of the interlayer insulating film.

The valve 31 is closed to stop the supply of the polishing liquid for the metal film, the polishing of the metal film is completed, and the valve 3
2 is opened and 300 ml of pure water is supplied from the rinse liquid supply device 29.
The rinse step was performed for 2 minutes by flowing at a flow rate of / minute. The carrier head 25 is also rotated in the rinse step.

Next, the valve 32 was closed to complete the rinse step, and the valve 33 was opened to supply the insulating film polishing liquid from the insulating film polishing liquid supply device 30 to polish the insulating film. The conditions for polishing the insulating film are as follows. Polishing liquid flow rate: 200 ml / min Surface plate rotation speed: 12 rpm Carrier head rotation speed: 500 rpm Carrier head pressure: 8 psi

The interlayer insulating film was polished by changing the polishing time to 4 minutes, 5 minutes, and 6 minutes, and the surface and cross section thereof were observed. The surface of tungsten is almost the same,
It was flattened sufficiently. If you polish for 6 minutes,
There was some so-called dishing, in which the surface of the tungsten dropped slightly, but the amount was acceptable.
Further, the thickness of the interlayer insulating film was hardly changed by polishing for 4 minutes, 5 minutes, or 6 minutes. From this,
It is understood that under the above insulating film polishing conditions, tungsten effectively acts as a stopper for polishing the interlayer insulating film. After polishing the insulating film for a predetermined time, the valve 33 is closed to stop the supply of the insulating film polishing liquid, the insulating film polishing is completed, and the valve 32 is opened to rinse the liquid supply device 2.
Rinsing is performed by flowing pure water from No. 9 at a flow rate of 300 ml / min to remove the polishing liquid from the polishing surface.

(Embodiment 2) FIG. 3A shows another example of the chemical mechanical polishing apparatus. As compared with the apparatus shown in FIG. 2A, as a measurement system for detecting the end point of metal film polishing, instead of the rotation torque measurement system 27, the conductivity in the thickness direction of the wafer 24 is detected and detected. The main difference is that a conductivity measuring system 40 is provided to detect when the conductivity falls below a preset reference level as the end point of the polishing process. The motor 26 is controlled by the power supply unit 37a so as to rotate at a constant speed.

The conductivity measuring system 40 includes a carrier head 25.
From the semiconductor wafer 24, the polishing platen 21, and the power supply unit 41 for flowing a current to the ground, and the signal S ₂ corresponding to the conductivity of the semiconductor wafer 24 is detected as a voltage value from the current or the applied voltage supplied from the power supply unit 41. It also includes a comparison unit 38b for switching the type of polishing liquid via the valve drive unit 39 in comparison with the reference signal level L ₂ of the conductivity corresponding to the end point of the metal film polishing. The mechanism for supplying the polishing liquid is the same as that shown in FIG.

An embodiment for carrying out the process shown in FIG. 1 using the apparatus shown in FIG. 3A will be described. Using a known technique, a Ti film with a thickness of about 500 Å was formed as an adhesion layer using a collimated sputtering method on a sample in which a via hole was opened in the interlayer insulating film, and then a pure metal was used as a metal to be embedded in the via hole. Approximately 900 aluminum film was formed by sputtering method using aluminum as a target.
A film was formed to a thickness of 0 Å, and then heated in vacuum to about 450 ° C. for reflow to embed aluminum in the via hole.

With respect to this sample, aluminum was polished and flattened under the same conditions as in Example 1. However,
As a means for detecting the end point of the aluminum film polishing at this time, as shown in FIG. 3A, a change in the conductivity of the sample wafer 24 in the thickness direction is measured by the conductivity measuring system 40, and the end point is determined from the change. I asked.

As a result of a preliminary experiment for measuring the change in conductivity,
The results shown in FIG. 3 (B) were obtained. As shown by the arrow in FIG. 3B, the time when the conductivity decreases to the reference signal level L ₂ is the time when the area of the interlayer insulating film appearing on the polished surface becomes constant, and the time is when the metal film The polishing end point was set, and polishing was continued for another 2 minutes from that point, and the steps up to this point were used as the polishing step for the metal film. Again, as a result of a preliminary experiment under the same conditions, it was confirmed by microscopic observation of the sample surface at this point that no aluminum film remained in the depressed region of the interlayer insulating film.

After that, a rinsing step and an interlayer insulating film polishing were carried out in the same steps as in Example 1 to realize sufficient buried flattening. The cutting liquid switching operation in the embodiment shown in FIGS. 2 and 3 is collectively shown in the time chart of FIG.
This operation can be automatically executed according to the program stored in the valve drive unit 39. In this embodiment, a pure aluminum film is used to fill the via hole, but AlSiCu (Si 1%, Cu 0.5%) is used.
The same effect can be obtained by using an aluminum alloy such as the above.

In Examples 1 and 2 described above, the metal polishing is continued for 2 to 3 minutes after the end point of the metal polishing is detected. However, when the end point of the metal polishing is detected, the metal polishing is performed on the surface of the interlayer insulating film. Needless to say, the polishing of the metal film is not necessary after the end point of the metal polishing is detected when the process of forming the interlayer insulating film is used so as to obtain the flatness to the extent that no metal remains.

(Embodiment 3) Another embodiment using the apparatus of FIG. 3A will be described. Similar to the second embodiment, for a sample in which a via hole is opened in an interlayer insulating film by a known technique, a tungsten film is first formed as a base metal film by a sputtering method to a thickness of about 500 Å, and then the via hole is buried. A Cu film was formed as a metal film by a sputtering method to a thickness of about 8000Å, and then annealed at about 450 ° C. in vacuum for 20 minutes,
Cu was embedded in the via hole. For this sample, Cu was polished and flattened under the same conditions as in Example 2.

The polishing conditions for Cu are as follows. Polishing liquid flow rate: 300 ml / min Surface plate rotation speed: 10 rpm Carrier head rotation speed: 600 rpm Carrier head pressure: 5 psi

The detection of the end point of the copper film polishing was carried out by the change in the conductivity of the wafer 24 in the thickness direction by the conductivity measuring system 40 as in the second embodiment. In this example as well, as in Example 2, the polishing was continued for another 2 minutes from the end point, and the process up to this point was taken as the metal polishing step. Again, as a result of a preliminary experiment under the same conditions, it was confirmed by microscopic observation of the sample surface at this point that no copper film remained in the depressed region of the interlayer insulating film.

The subsequent steps have the same contents and conditions as in Example 1, and as a result, sufficient buried flattening was realized.
In this embodiment, the sputtering method is used as the copper film forming method, but if the filling into the connection hole is sufficiently performed, another method such as the ECR-CVD method may be used to obtain the same result. Is obtained.

[0039]

According to the manufacturing method of the present invention, the metal film polishing step,
Since the rinsing step and the interlayer insulating film polishing step can be performed by a series of chemical mechanical polishing steps, the buried planarization can be realized without increasing the number of steps. And
In the step of polishing the metal film, by continuing the polishing of the metal film by a predetermined amount after the end point of the metal film polishing is detected, the metal can be prevented from remaining in the depressed region of the surface of the interlayer insulating film, and the upper metal wiring can be formed. It is possible to obtain a highly reliable semiconductor device in which a short circuit between them does not occur. When tungsten is used as the burying metal, tungsten has excellent step coverage and can reliably fill fine grooves and connection holes, resulting in high reliability. Further, if aluminum or an aluminum alloy is used as the burying metal, the cost of the multi-layer wiring portion is reduced. If copper is used as the burying metal, copper is a low resistance material and a semiconductor device suitable for high speed operation can be obtained. The stability and reproducibility of the end point detection can be improved by using the change of the rotation torque of the carrier head and the change of the conductivity in the thickness direction of the semiconductor substrate wafer to determine the end point of the metal film polishing.

[Brief description of drawings]

FIG. 1 is a process sectional view showing a manufacturing method of the present invention.

FIG. 2A is a schematic configuration diagram showing an embodiment of a chemical mechanical polishing apparatus, and FIG. 2B shows a change in rotational torque when polishing a metal film using the chemical mechanical polishing apparatus. FIG.

FIG. 3A is a schematic configuration diagram showing another embodiment of a chemical mechanical polishing apparatus, and FIG. 3B is a change in conductivity when polishing a metal film using the chemical mechanical polishing apparatus. FIG.

FIG. 4 is a time chart diagram collectively showing the operation of the embodiment.

[Explanation of symbols]

 1 Semiconductor Substrate 2 Metal Wiring 3 Interlayer Insulation Film 4 Connection Hole 5 Metal Film 21 Surface Plate 23 Polishing Pad 24 Wafer 25 Carrier Head 27 Rotational Torque Measuring System 28 Metal Film Polishing Liquid Supply Device 29 Rinsing Liquid Supply Device 30 Insulating Film Polishing Liquid supply device 31, 32, 33 Valve 40 Conductivity measurement system

Claims (8)

[Claims] 1. An insulating film is formed on a semiconductor substrate wafer,
After forming a connection hole at a predetermined position of the insulating film, a metal film is formed on the insulating film, the back side of the wafer is held by a carrier head, and the front side of the wafer is pressed against a polishing pad to rotate. Then, the method for manufacturing a semiconductor device is characterized in that the metal film is embedded in the connection hole by a series of chemical mechanical polishing including the following steps (A) to (C). (A) A metal film polishing liquid containing a polishing agent and prepared to increase the polishing rate for metal is supplied between the wafer surface and the polishing pad to expose the insulating film, and to the portion other than the connection hole. A step of polishing the metal film until no metal film remains, (B) a step of rinsing the polishing surface by switching the supply between the wafer surface and the polishing pad from the metal film polishing liquid to water, (C) After that, the supply between the wafer surface and the polishing pad is switched from water to a polishing liquid for an insulating film which contains a polishing agent and is prepared to increase the polishing rate for an insulator, and is embedded in a connection hole. The step of polishing the insulating film by using the metal film as a stopper to flatten the surface of the insulating film. 2. In the step (A) of polishing a metal film,
2. The method of manufacturing a semiconductor device according to claim 1, wherein the end point of the metal film polishing is detected from the change in the rotation torque of the carrier head, and after the end point is detected, a predetermined amount of polishing is continued. 3. In the step (A) of polishing a metal film,
Detecting the end point of the metal film polishing from the change in conductivity in the thickness direction of the wafer between the front surface side and the back surface side of the wafer,
The method of manufacturing a semiconductor device according to claim 1, wherein a predetermined amount of polishing is continued after the end point is detected. 4. The method of manufacturing a semiconductor device according to claim 1, wherein the metal film is a tungsten film. 5. The method of manufacturing a semiconductor device according to claim 1, wherein the metal film is an aluminum film or an aluminum alloy film. 6. The method of manufacturing a semiconductor device according to claim 1, wherein the metal film is a copper film. 7. An upper surface is a horizontal surface, a polishing pad is provided on the horizontal surface, a polishing surface plate that rotates in the horizontal surface, and a back surface of a wafer substrate are held, and the front surface of the wafer substrate is pressed against the polishing pad, A head mechanism that applies a load to rotate in a horizontal plane, a rotation torque measurement system that detects the rotation torque of the head mechanism and detects the end point of the polishing process from the detected rotation torque, and polishing of a metal film on a polishing pad A polishing apparatus comprising: a polishing liquid supply unit that can selectively supply a liquid, a polishing liquid for an insulating film, and pure water. 8. An upper surface is a horizontal surface, a polishing pad is provided on the horizontal surface, a polishing surface plate that rotates in the horizontal surface, and a back surface of a wafer substrate are held, and the front surface of the wafer substrate is pressed against the polishing pad, A head mechanism that applies a load to rotate in the horizontal plane, a conductivity measuring system that detects the conductivity in the thickness direction of the wafer substrate, and detects the end point of the polishing process from the detected conductivity, and a polishing pad A polishing apparatus comprising: a polishing solution supply unit capable of selectively supplying a polishing solution for a metal film, a polishing solution for an insulating film, and pure water.