JP2001284298A - Monitoring method for polishing state, polishing device and manufacturing method of semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a monitoring method for polishing state which enables measurement at a short time interval, and a polishing device wherein it is used. SOLUTION: Three observation windows 5a to 5c are provided on a turn table 3 and a polishing pad 4. Light cast from an optical characteristic measurement device 6 is projected to the surface of a wafer 1 through the observation windows 5a to 5c. Reflection light from the wafer 1 is subjected to spectrum treatment with an optical system provided inside the optical characteristic measurement device 6 and data processing with a personal computer 7, and a polishing amount or a polishing end point is detected. Three observation windows 5a to 5c are provided and disposed with an equal interval on a concentric circle to a rotation center of a polishing plate without making them proximate. As a result, a measurement interval is reduced and highly precise control is possible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for optically measuring the progress of a polishing step when a wafer is polished by a polishing apparatus in, for example, a semiconductor manufacturing process, a polishing apparatus having the same, and The present invention relates to a method for manufacturing a semiconductor device using them.

[0002]

2. Description of the Related Art High density semiconductor devices have continued to evolve without showing any limitations.
Methods are being developed. One of them is a multilayer wiring, and the technical problems associated with this include flattening a global (relatively large area) device surface and wiring between upper and lower layers. In view of the reduction in the depth of focus during exposure due to the shortening of the wavelength of lithography, there is a great demand for the accuracy of flattening the interlayer at least in the range of the exposure area.

In addition, the demand for so-called inlays (plugs, damascenes) for embedding metal electrode layers is great for realizing a multilayer wiring. In this case, it is necessary to remove and flatten an extra metal layer after lamination.

A polishing process called CMP is drawing attention as an efficient planarization technique for these large areas. CMP (Chemical Mechanical Polish)
ing or Planarization) is a combination of physical polishing and chemical action (abrasives, melting with a solution)
The process of removing the surface layer of the wafer is a leading candidate for global planarization and electrode forming technology. Specifically, using an abrasive called a slurry in which abrasive grains (typically silica, alumina, cerium oxide, etc.) are dispersed in a soluble solvent of the abrasive, such as an acid and an alkali,
Polishing is advanced by pressing the wafer surface with a suitable polishing cloth and rubbing by relative motion. By making the pressure and the relative movement speed uniform over the entire surface of the wafer, uniform polishing within the surface becomes possible.

[0005] Although this process still has many problems in terms of matching with the conventional semiconductor process, etc., one of the general requirements is to detect the end point of the polishing process. In particular, the detection of the polishing end point (in-situ) while performing the polishing step is greatly demanded for improving the process efficiency.

As one of the detection methods, a method has been used in which a change in friction when polishing is performed on a layer different from the target polishing layer is detected by a change in motor torque for wafer rotation or pad rotation. This method may be effective at the time of metal polishing for detecting the start of polishing of a different layer, but it is pointed out that it is not effective for a certain kind of electrode metal (such as Cu having a barrier metal layer). Insufficient accuracy. (It has also been reported that detection with the aging of the polishing pad makes detection difficult.)

In order to cope with such a problem, the present inventors have determined, as reference characteristics, reflected light and transmitted light when irradiating the wafer with light, and applied a light spot to the wafer during polishing. Then, a method of performing a fitting calculation between the measured values of the spectral characteristics of the reflected light and transmitted light from the wafer and the above-mentioned reference characteristics, and inventing a method of setting the film thickness that gives the best match as the measured value was invented. It is disclosed in JP-A-11-33901.

According to the present invention, the thickness of a portion having a fine structure can be accurately measured by using a light spot larger than that of the fine structure. The method enables non-destructive measurement in the in-situ state.

FIG. 4 is a diagram showing an example of such a film thickness measuring device. In FIG. 4, a wafer 21 to be polished is held by a wafer carrier 22. A polishing pad 24 is provided on the surface of the polishing platen 23.
Is rotating around its central axis. The wafer carrier 22 rotates while reciprocating while pressing the wafer 21 onto the polishing pad 24, and polishes the wafer 21 with the polishing pad 24. The polishing platen 23 and the polishing pad 24 are provided with a quartz light transmitting window 25. Light emitted from the irradiation light source 26 is projected onto the surface of the wafer 21 through the quartz light transmitting window 25. The reflected light from the wafer 21 is spectrally processed by an optical system as shown in FIG.
Data is processed by the personal computer 27 in FIG. 4 to detect the polishing amount or the polishing end point.

FIG. 5 is a diagram showing details of an example of an optical system used in the film thickness measuring device shown in FIG. In FIG. 5, light from a xenon lamp 28 as an irradiation light source is converted into a parallel light beam by a lens
After passing through the beam splitter 32,
Is collected. The light that has passed through the beam splitter 32 is
The beam is again converted into a parallel light beam by the lens 33 and is projected on the surface of the wafer 21 through the quartz light transmitting window 25 in FIG.

The reflected light is again condensed on the beam splitter 32 through the quartz light transmitting window 25 and the lens 33. In the beam splitter 32, the reflected light is changed in direction by 90 ° and is converted into a parallel light by the lens 34. And
The light is reflected by the reflecting mirror 35 and is focused on the pinhole 37 by the lens 36. Then, noise components such as scattered light and diffracted light are removed, and the light is projected on a diffraction grating 39 via a lens 38 to be separated. The split light enters the linear sensor 40, and the spectral intensity is measured.

The personal computer 27 shown in FIG. 4 detects a change in the distribution of the spectral intensity and, based on a predetermined algorithm, determines the thickness of the layer to be polished (the uppermost layer),
The polishing end point is detected. The polishing amount is determined from the initial thickness of the wafer and the thickness of the layer being polished (the uppermost layer).

That is, the spectral reflectance of the wafer exhibits characteristics as shown in FIG. 6A at the beginning of polishing, but at the end of polishing, characteristics as shown in FIG. 6B. Therefore, the measured spectral reflectance and b in FIG.
Is calculated by the least squares method or the cross-correlation method, and polishing is terminated when a predetermined degree of matching is obtained. According to this method, it is possible to measure the polishing amount or the polishing end point in both the polishing of the interlayer insulating film and the polishing of the metal electrode film without changing the apparatus.

[0014]

However, in the method as shown in FIG. 4, the measurement can be performed only when the quartz light transmitting window 25 comes above the irradiation light source 26 due to the rotation of the polishing platen 23. The time during which data can be acquired must be intermittent. An increase in the signal acquisition interval is disadvantageous when high-precision control is performed by optical measurement. This is because a desirable process change point may not coincide with the signal acquisition timing (it may be too early if stopped at the previous signal judgment, or too late if stopped at the next signal judgment). In addition, it is usual to increase the certainty by evaluating the process change point based on the measurement results of a plurality of times, but if the measurement interval becomes longer than a certain level, polishing proceeds during that time. In some cases, a desired process change point may be passed.

The present invention has been made in view of such circumstances, and has as its main objects to provide a polishing state monitoring method capable of performing measurement at short time intervals and a polishing apparatus using the same. Another object of the present invention is to provide a method for manufacturing a semiconductor device using the same.

[0016]

According to a first aspect of the present invention, there is provided a method for monitoring a polishing state of an object to be polished in a polishing apparatus during polishing. By providing a plurality of places where light passes through the board, irradiating the object to be polished with light through the places where the light passes, and measuring the optical characteristics of the reflected light or transmitted light, thereby obtaining one or more objects to be polished. The present invention provides a method for monitoring a polishing state (claim 1), wherein the polishing state is monitored.

In the present invention, unlike the conventional method, a plurality of measurements can be performed during one rotation of the polishing pad, so that the measurement interval can be shortened, and the process change point and the polishing end point can be reduced. Can be determined accurately. In the present specification, the “optical characteristic” refers to an amount indicating a state of light, such as a spectral reflectance and a spectral transmittance.

A second means for solving the above-mentioned problem is as follows.
In the first means, a plurality of optical measurement optical systems,
The present invention is characterized in that reflected light or transmitted light is measured (claim 2).

In this means, a plurality of places where light passes through the rotating polishing pad and the polishing platen are provided, and a plurality of measuring instruments are provided. Some polishing apparatuses simultaneously polish a plurality of objects to be polished. In such a case, even if a plurality of places where light passes through the polishing pad and the polishing platen are provided, one polishing object can be obtained. In some cases, only the polishing state of the body can be measured. In this case, even in such a case, the polishing state of each object to be polished can be independently monitored.

A third means for solving the above-mentioned problem is as follows.
A polishing apparatus for pressing an object to be polished held by a polishing head against a polishing pad attached to a polishing surface plate, supplying an abrasive, and performing polishing while rotating at least the polishing surface plate, comprising a polishing pad and a polishing surface. A board is provided with a plurality of places through which light passes, and an apparatus for irradiating the object to be polished with probe light through a place through which light passes, and an apparatus for measuring light reflected or transmitted from the object to be polished, A polishing apparatus for monitoring the polishing state of the object to be polished based on the optical characteristics of the reflected light or transmitted light.

In this means, the light provided on the polishing pad and the polishing platen passes through the apparatus for irradiating the probe light each time the light passes therethrough. Alternatively, transmitted light can be measured. Therefore, the polishing state of the object to be polished can be measured at shorter intervals as compared with the conventional polishing apparatus, so that the polishing end point and the process change point can be accurately measured. It is needless to say that a polishing operation in which the distance between the object to be polished and the center of the polishing platen is changed is added to the polishing operation, and an operation involving rotation of the object to be polished falls within the scope of the present invention.

The "apparatus for measuring the reflected light or transmitted light from the object to be polished" is an apparatus which receives reflected light or transmitted light and converts them into spectral characteristics and other "optical characteristics". Say. The “device for monitoring the polishing state” is a device that measures the thickness of a polished film or determines whether a change in the polishing operation has been reached based on these optical characteristics.

A fourth means for solving the above-mentioned problem is:
The third means is characterized in that a plurality of devices for measuring reflected light or transmitted light from the object to be polished are provided (claim 4).

As described above, some polishing apparatuses simultaneously polish a plurality of objects to be polished. In such a case, a plurality of places where light passes through the polishing pad and the polishing platen are provided. Even if it is provided, there is a case where the polishing state of only one polishing object can be measured. In this case, even in such a case, the polishing state of each object to be polished can be independently monitored.

A fifth means for solving the above problem is as follows.
The fourth means, wherein at least two devices for measuring the plurality of reflected light or transmitted light share a part of the configuration between at least two devices (claim 5). is there.

In this means, for example, a separate light receiving section for directly receiving light is provided, and an expensive portion (for example, a spectroscope) for obtaining optical characteristics from an optical signal received by the light receiving section is used in common. Can be made cheaper.

A sixth means for solving the above-mentioned problem is:
The fifth means, wherein the partial configuration is shared.
The apparatus for measuring a plurality of reflected light or transmitted light includes a switching device for switching received signal light and transmitting the signal light to a shared portion connected thereafter (Claim 6). .

In this means, the received signal light is switched by the switching device and sent to a shared portion connected thereafter. For example, the received light is switched by a light switching device and sent to a common part such as an expensive spectroscope. Therefore, expensive parts can be shared,
The whole can be inexpensive.

[0029] A seventh means for solving the above problem is as follows.
The fifth means or the sixth means, wherein the device for measuring a plurality of reflected light or transmitted light includes a main body for detecting optical characteristics of light, and a light receiving unit for receiving light and guiding the light to the main body. Wherein the main body is shared and an optical fiber is used for the light receiving portion.
It is.

This means is divided into a main body for detecting the optical characteristics of the light from the received light, and a light receiving section for receiving the light and guiding the light to the main body, and a portion for directly receiving the light is composed of an optical fiber. Or an optical system, and in each case, the received light is guided to the main body using an optical fiber.

Which part is the light receiving part and which part is the main body part depends on the design. However, when the optical signal is switched by an optical signal switch and received by a common optical sensor, the parts after the optical signal switch are used. Can be considered a department. In this means, since the optical fiber is used for transmitting the light in the light receiving section, the degree of freedom of mechanical design around the light receiver in the polishing apparatus can be increased.

Eighth means for solving the above-mentioned problem is:
In any one of the third means to the seventh means, a part of a device for measuring reflected light or transmitted light from the object to be polished rotates with a polishing platen, and receives the received light. The rotary joint has a function of guiding to a fixed portion (claim 8).

In this means, a part of the device for measuring the light reflected or transmitted from the object to be polished rotates together with the polishing platen. At that time, the irradiation light from these measuring devices
It goes without saying that a part of these measuring devices is provided at a position such that the light always passes through the place provided on the rotating polishing pad and the polishing platen. Thus, the time during which the object to be polished is irradiated with the light from the measuring device can be lengthened, and accurate measurement can be performed.

A ninth means for solving the above-mentioned problem is:
A semiconductor device, comprising the step of polishing at least one of the first means, the second means, or the third means to the eighth means when polishing a wafer. (Claim 9).

In this means, since the change point of the polishing step and the polishing end point can be accurately grasped, the wafer can be accurately polished, and the semiconductor device can be manufactured with a high yield.

[0036]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the embodiment described below, a polishing end point is determined and a polishing amount is measured. The principle method is the same as that shown in FIGS.

That is, spectrometry using light of multiple component wavelengths is applied as a method capable of appropriately and more accurately performing optical measurement of a wafer having a pattern. Specifically, white light (or a component obtained by dividing the light) is applied. Of course, irradiation from the back surface of the wafer may be performed, but in that case, a multi-component wavelength light source in the infrared region is required. In each case, the state of polishing is to be known by looking at the wavelength dependence of reflected light (or transmitted light in the case of infrared light), that is, spectral characteristics.

In the detection system of this embodiment, light is emitted with a spot diameter larger than the minimum unit of the pattern. In such a case, the reflected light (or transmitted light) from the pattern structure portion which is not a blank depends on the wavelength from the superposition of the light beam from the boundary of each layer of the laminated thin film constituting the device and the reflected light wave from each pattern portion. (Spectral characteristics). By monitoring this waveform while polishing is in progress, it is possible to know the polishing amount or determine the polishing end point. For example, in the polishing of a metal layer in a damascene process, a large change in waveform appears due to the exposure of the underlying pattern near the polishing end point, so that highly accurate detection can be performed.

In such an optical method, during polishing,
In order to perform so-called in-situ measurement, a pad and a surface plate are provided with a light-transmitting window. The translucent window may use a transparent pad member or a method in which a hollow portion is filled with a transparent fluid (air or water).

When both the number of rotations of the wafer and the number of rotations of the polishing platen are measured at about 60 rpm, the signal acquisition interval is approximately one second. Under the conditions of Cu polishing, the polishing progress in one second may be about 10 nm, which is a value that cannot be ignored for the precision to be controlled. Therefore, it is difficult to monitor with one data number per rotation in view of safety (considering that data acquisition may not be performed properly due to noise).

On the other hand, in the present invention, as an embodiment, for example, a polishing apparatus having a configuration as shown in FIG. 1 is used. In FIG. 1, 1 is a wafer, 2 is a polishing head,
3 is a polishing table, 4 is a polishing pad, 5a to 5c are observation windows,
Reference numeral 6 denotes an optical characteristic measuring device and 7 a personal computer. Note that the optical property measuring device 6 is a device for measuring reflected light or transmitted light from the object to be polished in the claims.
And a personal computer 7 for monitoring the polishing state of the object to be polished.
Corresponding to

The wafer 1 to be polished is held by a polishing head 2. A polishing pad 4 is provided on the surface of the polishing platen 3, and the polishing platen 3 is rotated around its central axis. The polishing head 2 rotates and reciprocates while pressing the wafer 1 on the polishing pad 4, and polishes the wafer 1 with the polishing pad 4. The polishing platen 3 and the polishing pad 4 are provided with three observation windows 5a to 5c. Light emitted from the optical property measuring device 6 is projected on the surface of the wafer 1 through the observation windows 5a to 5c. The reflected light from the wafer 1 is spectrally processed by an optical system as shown in FIG.
The data is processed by the personal computer 7 to detect the polishing amount or the polishing end point.

In this embodiment, three observation windows 5a to 5c are set.
The measurement intervals are shortened and high-precision control is possible by disposing them at equal intervals on the concentric circle with respect to the center of rotation of the polishing table without providing them close to each other. That is,
The measurement interval becomes 1/3 as compared with the case where the number of observation windows is one, and control with the polishing amount of 1/3 becomes possible. If you increase the number of observation windows,
As a result, the measurement interval becomes shorter, and a small change in the polishing amount can be detected.

FIG. 2 shows an example of a polishing apparatus according to another embodiment of the present invention. 2, the same components as those shown in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. In FIG. 2, reference numerals 1a and 1b denote wafers, 2a and 2a,
b is a polishing head, 8a and 8b are light receiving ends, 9a and 9b are optical fibers, 10 is a fiber switching device, and 11 is an optical fiber. In the present embodiment, what corresponds to the “device for measuring reflected light or transmitted light from the object to be polished” referred to in the claims is not only the optical property measuring device 6 but also the light receiving end. 8a, 8b, optical fibers 9a, 9
b, a fiber switching device 10 and an optical fiber 11 are included.

In this embodiment, the polishing head is 2
a and 2b are provided, and two wafers 1a and 1b are respectively held and two wafers can be polished simultaneously. In such a polishing apparatus, even if a plurality of observation windows are provided, the measurement interval can be shortened, but only the polishing state of one wafer can be detected. Therefore, in the present embodiment, two “devices for measuring reflected light or transmitted light” described in the claims are provided. Two detectors are provided according to the number of wafers. However, an expensive main part having a spectroscope or the like is shared, and only two parts corresponding to the light receiving end are provided (corresponding to claim 5).

That is, the light receiving ends 8a and 8b are provided in accordance with the positions of the wafers 1a and 1b. Light receiving end 8
Reference numerals a and 8b denote, for example, those in which a condenser lens is attached to the tip of an optical fiber, and condense reflected light from the wafers 1a and 1b. The light received at the light receiving ends 8a and 8b is guided to the fiber switching mechanism 10 through the optical fibers 9a and 9b, respectively. Since an optical fiber is used to guide the light, flexibility can be given to the light passage path, and the degree of freedom in the arrangement of mechanical parts around the lower part of the polishing platen 3 can be increased.

The fiber switching mechanism 10 includes an optical fiber 9
Since the light from a and 9b is selected and transmitted to the optical fiber 11, it is a well-known one and the description thereof is omitted. By periodically switching the light from the optical fibers 9a and 9b by the fiber switching mechanism 10 and sending the light to the optical characteristic measuring device 6 via the optical fiber 11, both wafers 1a,
The polishing state 1b can be observed (corresponding to claim 6).

A rotary joint is installed in front of the fiber switching mechanism 10 so that the light receiving ends 8a, 8b and the optical fibers 9a, 9b rotate together with the polishing platen 3 so that the optical fibers 9a, 9b The signal light may be guided to the non-rotating fiber switching mechanism 10 via the rotary joint. In this case, the irradiation light and the reflected light always pass through the observation windows 5a and 5b.
The time during which the wafers 1a and 1b are irradiated with the irradiation light is lengthened, so that the measurement time can be shortened.
The lower structure can be made compact.

FIG. 3 is a flowchart showing a semiconductor device manufacturing process. When the semiconductor device manufacturing process is started, first, in step S200, an appropriate processing step is selected from the following steps S201 to S204. According to the selection, the process proceeds to any of steps S201 to S204.

Step S201 is an oxidation step for oxidizing the surface of the silicon wafer. Step S202 is a CVD step of forming an insulating film on the surface of the silicon wafer by CVD or the like. Step S203 is an electrode forming step of forming electrodes on the silicon wafer by steps such as vapor deposition. Step S204 is an ion implantation step of implanting ions into the silicon wafer.

After the CVD step or the electrode forming step, the process proceeds to step S205. In step S205, it is determined whether or not to perform the CMP process, and if so, the process proceeds to the CMP process in S206. If the CMP step is not performed, S206 is bypassed. In the CMP step, the polishing apparatus according to the present invention performs planarization of an interlayer insulating film, formation of a damascene by polishing a metal film on the surface of a semiconductor device, and the like.

After the CMP step or the oxidation step, step S
Proceed to 207. Step S207 is a photolithography step. In the photolithography process, a resist is applied to a silicon wafer, a circuit pattern is printed on the silicon wafer by exposure using an exposure apparatus, and the exposed silicon wafer is developed. Further, the next step S208 is an etching step of removing portions other than the developed resist image by etching, and thereafter stripping the resist to remove unnecessary resist after etching.

Next, in step S209, it is determined whether or not all necessary steps have been completed. If not, the process returns to step S200, and the previous steps are repeated to form a circuit pattern on the silicon wafer. If it is determined in step S209 that all steps have been completed, the process ends.

[0054]

EXAMPLE 1 In the polishing apparatus shown in FIG. 1, Cu which is a metal electrode film on a 6-inch wafer (TaN as a barrier metal having a lower layer of about 40 nm) was actually polished, and the end point of the polishing was detected. Was. Polishing was performed by rotating and rocking a polishing head holding a wafer with a backing film on a foaming polishing pad having a diameter of 600 mm. The abrasive (slurry) was prepared by dispersing silica particles in an alkaline solvent, and the polishing was performed at a polishing pressure of about 200 g / cm ² and a rotation speed of 60 rpm.

In this example, three circular cuts having a diameter of about 20 mm are provided on the pad surface (each disposed at an angle of 120 °), and a transparent resin is disposed slightly below the polishing pad surface to thereby provide a polishing monitor. A light-transmitting window was formed. By irradiating probe light from the measurement unit for detection (fixed) to the wafer surface through the light-transmitting window, and detecting the spectral characteristics of the reflected light with an optical system as shown in FIG. did.

Since three windows are provided, the data acquisition interval is 1/3 rotation (approximately 333 msec), and it is possible to detect minute changes during that period. As a result, a thickness change immediately before the Cu film disappears can be controlled to 10 nm or less.

[0057]

Embodiment 2 Cu polishing was performed using a polishing apparatus as shown in FIG. 2 in the same manner as in Embodiment 1, and the end points of each of the two wafers were determined. Specifically, two observation windows having the same configuration as in Example 1 and having a diameter of 20 mm were provided so that the time when each window passed the position of the light receiving ends 8a and 8b was slightly shifted. By doing so, the signal of the optical system 1 from the wafer 1 and the signal of the optical system 2 from the wafer 2 can be obtained alternately using the fiber switching device 10. The fiber switching timing was synchronized with the rotation of the polishing table 3.

With this mechanism, in-situ monitoring of a plurality of wafers can be realized by one main optical system and signal processing system (optical characteristic measuring device 6, personal computer 7), and accurate process management of a plurality of wafers can be achieved. It is now possible.

[0059]

As described above, according to the first aspect of the present invention, since the measurement can be performed a plurality of times during one rotation of the polishing pad, the measurement interval can be shortened. Thus, the process change point and the polishing end point can be accurately determined.

In the invention according to the second aspect, even when a plurality of polished objects are polished simultaneously, the polishing state of each polished object can be monitored independently. In the invention according to the third aspect, the polishing state of the object to be polished can be measured at shorter intervals than in the conventional polishing apparatus, so that the polishing end point and the process change point can be accurately measured.

In the invention according to the fourth aspect, even when a plurality of polished objects are polished simultaneously, the polishing state of each polished object can be monitored independently. In the invention according to claim 5, it is possible to reduce the price of the apparatus by, for example, separately providing a light receiving unit for directly receiving light and sharing an expensive portion for obtaining a spectral characteristic from a detected signal. it can.

In the invention according to claim 6, an expensive signal processing section can be shared, and the whole can be made inexpensive. In the invention according to claim 7, since the optical fiber is used for transmitting light in the light receiving unit,
The degree of freedom of mechanical design around the optical receiver in the polishing apparatus can be increased.

In the invention according to claim 8, the time during which the object to be polished is irradiated with the light from the measuring device can be lengthened, and accurate measurement can be performed. According to the ninth aspect of the present invention, since the change point of the polishing process and the polishing end point can be accurately grasped, the wafer can be accurately polished, and the semiconductor device can be manufactured with high yield. .

[0064]

[Brief description of the drawings]

FIG. 1 is a diagram showing an outline of a polishing apparatus as an example of an embodiment of the present invention.

FIG. 2 is a diagram showing an outline of a polishing apparatus as another example of the embodiment of the present invention.

FIG. 3 is a diagram illustrating an outline of a method for manufacturing a semiconductor device as an example of an embodiment of the present invention;

FIG. 4 is a schematic view showing an example of a conventional polishing apparatus.

FIG. 5 is a schematic diagram illustrating an example of a spectroscopic device.

FIG. 6 is a diagram showing an example of the spectral reflectance of a wafer at the start of polishing and at the end of polishing.

[Explanation of symbols]

 1, 1a, 1b: Wafer 2, 2a, 2b: Polishing head 3: Polishing platen 4: Polishing pad 5a-5c: Observation window 6: Optical property measuring device 7: Personal computer 8a, 8b: Light receiving end 9a, 9b ... Optical fiber 10 ... Fiber switching device 11 ... Optical fiber

Claims (9)

[Claims] 1. A method for monitoring a polishing state of an object to be polished in a polishing apparatus during polishing, wherein a plurality of places where light passes through a rotating polishing pad and a polishing platen are provided, and the light passes therethrough. Monitoring a polishing state of one or more polishing objects by irradiating the polishing object with light through a place and measuring an optical property of reflected light or transmitted light thereof; . 2. The method for monitoring a polishing state according to claim 1, wherein a plurality of optical measurement optical systems measure reflected light or transmitted light. 3. A polishing apparatus for pressing an object to be polished held by a polishing head against a polishing pad attached to a polishing platen, supplying an abrasive, and polishing at least while rotating the polishing platen, A plurality of places where light passes through the polishing pad and the polishing platen are provided, and an apparatus for irradiating the object to be polished with probe light through the place where the light passes,
It has a device for measuring a reflected light or a transmitted light from an object to be polished, and a device for monitoring a polishing state of the object to be polished based on the measured optical characteristics of the reflected or transmitted light. Polishing equipment. 4. The polishing apparatus according to claim 3, wherein a plurality of devices for measuring reflected light or transmitted light from the object to be polished are provided. 5. The polishing apparatus according to claim 4, wherein said plurality of devices for measuring reflected light or transmitted light share at least two devices in common. Polishing equipment. 6. The polishing apparatus according to claim 5, wherein the apparatus for measuring the plurality of reflected lights or transmitted lights, which shares the partial configuration, switches the received signal light, and thereafter, A polishing apparatus, comprising: a switching device that sends a signal to a common part connected to the polishing apparatus. 7. The polishing apparatus according to claim 5, wherein the apparatus for measuring a plurality of reflected lights or transmitted lights includes:
It is divided into a main unit that detects the optical characteristics of light and a light receiving unit that receives light and guides it to the main unit.The main unit is shared, and an optical fiber is used for the light receiving unit. Polishing equipment. 8. One of claims 3 to 7
The polishing apparatus according to the above, wherein a part of the apparatus for measuring the reflected light or transmitted light from the object to be polished rotates with the polishing platen, the received light using a rotary joint, fixed A polishing apparatus characterized in that it has a function of leading to a part. 9. A polishing method for monitoring a polishing state according to claim 1 or 2, or polishing using a polishing apparatus according to claim 3 when polishing a wafer. A method for manufacturing a semiconductor device, comprising the step of: