JP2002343754A - Polishing apparatus and method and semiconductor device manufacturing method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polishing apparatus that can precisely detect the polishing end point in a wafer that is being polished and machined. SOLUTION: This polishing apparatus 1 has a wafer holder 12 that sucks and retains a wafer W on an upper surface, a head member 22 that is positioned at the upper portion of the wafer holder and has a polishing pad 21 on a lower surface, and an optical measurement section 30 that measures the surface state of the wafer W. The wafer W is retained by the wafer holder 12 for rotating and driving, and is flatly polished and machined by the CMP operation of slurry at a portion to the polishing pad 21 that is crimped to the surface to be polished of the wafer for relative movement. Probe light from the optical measurement section 30 is irradiated to the rotary center (specific position) of the wafer W, and variation in the intensity of reflection signal light during polishing and machining is measured. In this configuration, a measurement position is constantly the same even if the wafer W is rotated, thus precisely judging a polishing end point in the wafer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing apparatus and a polishing method for polishing an object to be polished, such as a semiconductor wafer, a quartz substrate, and a glass substrate, and more particularly to a polishing method for precisely and flatly polishing a surface to be polished of a semiconductor wafer. The present invention relates to a polishing apparatus, a polishing method, and a semiconductor device manufacturing method using the polishing apparatus.

[0002]

2. Description of the Related Art A CMP apparatus is a polishing apparatus suitable for polishing an object to be polished as described above. Conventionally, a CMP apparatus has been used for mirror polishing, which is the final step of the silicon polishing wafer manufacturing process, and the wafer surface is subjected to chemical mechanical polishing (CM).
P) It is used as a polishing device for flat mirror polishing by processing. On the other hand, in the semiconductor device manufacturing process, as the integration degree of the integrated circuit becomes higher, the circuit pattern becomes finer and multilayered, and the device surface becomes less flat. Further, in order to increase the degree of integration by reducing the line width of an integrated circuit, the wavelength of a light source used for optical lithography has been shortened, and the depth of focus of a semiconductor exposure apparatus has been substantially reduced. For this reason, in recent years, in the process of forming a three-dimensional multilayer circuit pattern, the CMP (Chemical Mechanical Planarization) process for polishing and flattening the surface of a semiconductor wafer has been improved in integration degree. Therefore, there is a demand for a CMP apparatus suitable for such a polishing process.

As shown in FIG. 8, the basic structure of a conventionally used CMP apparatus is a polishing platen 122 having a polishing pad 121 mounted on an upper surface, and a wafer holding device for suction-holding a wafer on a lower surface. And a member 112. The polishing table 122 is supported by a table driving shaft 123 that extends vertically downward, and is driven to rotate in a horizontal plane by a driving mechanism (not shown). The wafer holding member 112 is held by a wafer rotation shaft 113 extending vertically upward, and is driven to rotate in a horizontal plane by a rotation mechanism (not shown). The wafer holding member 112 is swung in the radial direction of the polishing platen 122 by an unillustrated swing mechanism.

In the CMP apparatus 101 configured as described above, the polishing of the wafer W is performed by rotating the polishing platen 122 and the wafer holding member 112 in the same direction or the opposite direction, and supplying the slurry to the pad surface of the polishing pad 121. By lowering the wafer holding member 112 while pressing the wafer W against the pad surface, the wafer holding member 112 is further reciprocatedly oscillated in the radial direction of the polishing platen 122. As a result, the surface to be polished of the wafer W relatively moved while being in contact with the pad surface is polished flat by the mechanical and chemical polishing action of the slurry interposed between the wafer W and the pad surface (CMP process).
Is done.

During polishing, the polishing state is changed in-situ.
End point detection for measuring and detecting the polishing end point is performed. As a conventional end point detection method, there is a torque detection method. This is because the change in the coefficient of friction between the wafer W and the polishing pad 121 is indirectly detected by detecting the change in the torque current value of the motor that rotationally drives the polishing platen 122 or the motor that rotationally drives the wafer holding member 112. Is to be detected.

However, the torque detection method effectively functions only in a CMP process in which the frictional resistance greatly changes near the polishing end point, such as metal CMP, and in a CMP process, such as an interlayer insulating film CMP, which does not use a stopper. Cannot be applied. Further, since the information indirectly detected by this method is the averaged frictional resistance of the entire polished surface, when the variation in polishing is large, a signal change does not clearly appear, and the polishing end point may not be detected. There was a problem.

Therefore, in recent years, a polishing apparatus for directly measuring the surface state of the wafer W optically and detecting the end point has been devised. This polishing apparatus 102 is schematically shown in FIG.
A hole is provided in a part of the polishing platen 122, and a light-transmitting portion 125 is provided in the polishing pad 121. Irradiation, reflected light is detected, and end point detection is performed from the intensity change and spectrum distribution.

According to such a polishing apparatus, the metal CM
The end point can be detected not only for P and STI-CMP but also for a CMP process that does not use a stopper, such as an interlayer insulating film CMP. In addition, since the information detected by this method is not the averaged information of the entire surface to be polished but the information of the spot area irradiated by the probe light, it has been considered that the polishing end point can be reliably detected.

[0009]

However, when repeatedly polishing various kinds of wafers with the above-described polishing apparatus 102, it has been found that the polishing end point is slightly different for each wafer. . That is,
Over-polishing and under-polishing wafers are found with respect to the ideal polishing end state. This means that the determination of the end point detection is varied with respect to the ideal polishing end point, and suppressing this variation to improve the determination accuracy requires efficient management of the CMP process and the CMP apparatus. This has been an important technical issue in improving throughput.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a polishing method and a polishing apparatus capable of determining a polishing end point with high accuracy during polishing.

Another object of the present invention is to provide a method for manufacturing a semiconductor device using such a polishing apparatus.

[0012]

Means for Solving the Problems In order to solve the above-mentioned problems, the inventor first examined the reason why the judgment of the end point detection varies from an ideal polishing end point, and found the following factors. The first factor is that the film formation state and the polishing rate differ depending on the position of the die region (chip region) on the wafer and the pattern position in the die region. That is, various patterns having different writing densities and finenesses exist in the die area (chip area) formed on the wafer, and the polishing rate differs according to the density of the pattern. In addition, even when the pattern has a relatively uniform pattern, the film thickness and the polishing rate may differ depending on the position of the die region on the wafer.

The "die area (chip area)" in this specification refers to an area where a device pattern is formed on a wafer and divided into streets, and forms one die (chip) after dicing. Refers to the area.

The second factor is that it is not clear which position the surface state measured by the optical measuring device 130 is. That is, it is conventionally unknown which die area on the wafer surface the measurement position is and which pattern position in the die area.

For this reason, in the conventional polishing apparatus, when the optical measuring device 130 measures a position where the polishing rate is high (die area or pattern position), the polishing end point is advanced, and as a result, insufficient polishing occurs as a whole, When the position where the polishing rate was slower was measured, the polishing end point was delayed and excessive polishing occurred as a whole. From the above examination results, the inventor has invented the following means to achieve the above object.

According to the present invention, an object holder (for example, the wafer holder 12 in the embodiment) for holding a polishing object (for example, the wafer W in the embodiment) and a polishing member (for example, a polishing pad in the embodiment) for polishing the object to be polished. A configuration in which the polishing member and the polishing target are relatively moved while the polishing member is in contact with the polishing target held by the target holding portion to perform a polishing process on the polished surface of the polishing target. In the polishing apparatus has an optical measurement unit for optically measuring the surface state of the surface to be polished, the optical measurement unit measures the surface state of a specific position on the surface to be polished during the polishing process of the surface to be polished. A polishing apparatus is configured.

The polishing apparatus having the above configuration is provided with an optical measuring section for optically measuring the surface condition of the surface to be polished,
The optical measuring unit measures the surface condition of a specific position on the surface to be polished during polishing. Here, the "specific position of the surface to be polished" refers to a predetermined position specified on the surface to be polished, for example, in the example of the semiconductor wafer described above, a specific (specific address) die area on the wafer surface Or a specific pattern position in a specific die area, or a specific reference area provided outside the die area. According to this configuration, since the optical measurement unit always measures the surface state at a specific position on the surface to be polished, it is possible to accurately capture the change in the surface state of the surface to be polished, and therefore, high precision during polishing. Thus, a polishing apparatus capable of determining the polishing end point can be obtained.

The object holding section is configured to be able to rotate the object to be polished around a rotation axis (for example, the rotation axis A in the embodiment) orthogonal to the surface to be polished at the center of rotation. A illuminating unit that irradiates the surface to be polished with light and a light detecting unit that detects signal light reflected or transmitted from the surface to be polished, and detects signal light obtained by irradiating probe light to the rotation center position of the surface to be polished. By doing so, the polishing apparatus may be configured to measure the surface condition at a specific position.

In a polishing apparatus in which an object to be polished is held and held by an object holder, each position on a rotating circumference is rotated with the rotation of the object to be polished. However, only the rotation center position does not change due to the rotation drive. In this configuration, the rotation center position that does not change in movement is defined as a specific position, and the optical measurement unit irradiates the specific position with probe light to measure the surface state. Therefore, according to the above configuration, a change in the surface state of the surface to be polished can be accurately detected with a very simple configuration.

The object holding portion is configured to be capable of rotating the object to be polished around a rotation axis intersecting with the surface to be polished, and at least one of a rotation angle position of the object to be polished and a rotation angle position of the object holding portion. An optical measuring unit includes an illuminating unit that irradiates the surface to be polished with probe light and a light detecting unit that detects signal light reflected or transmitted from the surface to be polished. The polishing apparatus may be configured to measure a surface state at a specific position by detecting a signal light obtained by irradiating a position specified based on a detection signal from the detection unit with probe light.

In the polishing apparatus having the above structure, the angular position detecting section detects at least one of the rotation angle position of the object to be polished and the rotation angle position of the object holding section, and the optical measuring section detects the rotation angle position from the angle position detecting section. The surface condition at a specific position specified based on the detection signal is measured. Therefore, according to the polishing apparatus having the above-described configuration, it is possible to always specify a fixed position by specifying the rotation angle position on the same circumference on which the probe light is irradiated, and to specify the specified position thus specified. The change in the surface state of the object can be accurately grasped.

The angular position detecting section optically detects a specific index formed on the object to be polished to detect the rotational angle position of the object to be polished, and the optical measuring section is detected by the angle position detecting section. The polishing apparatus can be configured to measure the surface condition of a specific position on the surface to be polished based on the detection signal of the specific index.

Here, the “specific index formed on the object to be polished” is, for example, an orientation flat or notch (Notc) on a semiconductor wafer.
h), refers to an index such as an alignment mark, and may be an index for position detection newly provided outside the die area (for example, an optical reflection area or the like). According to the polishing apparatus having such a configuration, since the specific index formed on the object to be polished is directly used as the reference of the angular position, the position on the surface to be polished can be easily specified, and the positional accuracy of the specific position is improved. Can be improved. Further, since there is no need to provide another detected portion for detecting the angular position, the polishing apparatus can be simplified.

Further, the irradiation position of the probe light on the surface to be polished can be relatively moved in the radial direction of the surface to be polished,
It is also preferable that the polishing apparatus is configured to measure a surface state of a specific position in which a rotation angle position and a radial position of the surface to be polished are specified by allowing a reflected or transmitted signal light by irradiation to be received in a movement path. .

According to the above configuration, the surface to be polished is rotated around the rotation axis so that the surface condition at a specific position on the same circumference can be measured, and the measurement position can be relatively moved in the radial direction of the polished surface. Then, the surface state of the specific position in which the rotational angle position and the radial position of the polished surface are specified is measured. For this reason, not only a constant rotation circumference but also an arbitrary position on the surface to be polished can be specified, and a change in the surface state at the specific position can be accurately grasped.

The polishing member is attached to the polishing apparatus via a moving mechanism that supports the polishing member so as to be movable in the radial direction of the object to be polished, and the illumination unit and the light detection unit are supported by the moving mechanism to perform polishing. The polishing apparatus can be configured to be movable in the radial direction of the object. According to such a configuration, it is possible to configure the polishing apparatus capable of specifying and measuring an arbitrary position on the surface to be polished without separately providing a moving mechanism for moving the illumination unit and the light detection unit. .

It is preferable that the polishing apparatus be configured so that the light detecting section selectively extracts only the zero-order light component from the reflected light reflected by the surface to be polished and measures the surface condition of the surface to be polished. .

In the polishing method according to the present invention, the object holding portion and the polishing member are relatively moved while the object held by the object holding portion is in contact with the polishing member, and the object to be polished is polished. In a polishing method for polishing a polished surface, a change in the surface state at a specific position on the polished surface is measured during the polishing of the polished surface using an optical measurement unit that optically measures the surface state of the polished surface. Then, the polishing process is controlled based on the measurement result of the surface state at the specific position to be measured.

An object to be polished by the polishing apparatus constructed as described above is a semiconductor wafer, and the method for manufacturing a semiconductor device according to the present invention uses the polishing apparatus having the above-mentioned structure to flatten the surface of the semiconductor wafer. It is comprised including the process of changing.

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. In the description, first, a case will be described in which a metal film embedded in a damascene process is flattened by metal CMP to form an electrode wiring. C according to the first embodiment of the present invention
As shown in FIG. 1, the MP apparatus 1 has a schematic configuration as shown in FIG. 1, a wafer table 10 for adsorbing and holding a wafer W on an upper surface, a polishing head 20 on which a polishing pad 21 is mounted on a lower surface, and This is a CMP apparatus that includes an optical measurement unit 30 that measures a surface state, and that performs a polishing process by measuring the surface state at the center position of the wafer W.

The wafer table 10 includes a wafer holder 12
And a holder drive shaft 13 that extends vertically downward from the wafer holder 12 and supports the wafer holder 12. The holder drive shaft 13 is rotated by a rotation drive mechanism (not shown).
Is rotated around the rotation axis A. Wafer holder 12
Is provided with a holding mechanism for sucking and holding the wafer W from the back side, and a retainer ring for aligning the center of the wafer W with the rotation axis A of the wafer holder 12 (both are not shown). As a result, the wafer W is suction-held so that its center position coincides with the rotation axis A, and is horizontally rotated at a predetermined rotation speed by the rotation drive mechanism.

The polishing head 20 has a polishing pad 21 on the lower surface.
A head member 22 to which the head member 2 is attached
And a spindle shaft 23 that extends vertically upward and supports the spindle 2. The spindle shaft 23 is driven to rotate around a rotation axis B by a rotation drive mechanism (not shown), and the polishing pad 21 attached to the lower end is rotated. Rotate in a horizontal plane at a predetermined rotation speed.

In the polishing of the wafer W, the wafer holder 12 and the head member 22 are rotated in the same direction or opposite directions,
The polishing head 20 is lowered while supplying the slurry from the center of the polishing pad 21 to press the polishing pad 21 against the surface to be polished of the wafer W, and further, the polishing head 20 is moved radially between the central portion and the outer peripheral portion of the wafer W. It is performed by swinging back and forth in the direction. Thereby, the polished surface of the wafer W is polished flat by the mechanical and chemical polishing action of the slurry interposed between the wafer W and the pad surface.

In the CMP apparatus 1, the diameter of the polishing pad 21 is smaller than the diameter of the wafer W as shown in the figure. Therefore, according to the CMP apparatus having such a configuration, the entire apparatus can be configured to be smaller in size than the conventional CMP apparatus described above. Further, in such a CMP apparatus, the polished surface of the wafer W is exposed except for a region where the polishing pad 21 is performing polishing. For this reason, without providing a hole in the head member 22 (polishing platen 122 in the prior art) or providing a light-transmitting portion in the polishing pad,
The surface condition of the polished surface can be measured.

In the CMP apparatus 1 according to the first embodiment, the surface state of the rotation center position of the wafer W is measured by the optical measurement unit 30 as means for measuring a specific position on the wafer.

The optical measuring unit 30 includes a light source 31, a beam splitter 32, a reflected light detector 33, a lens optical system (not shown), and the like, and converts the probe light emitted from the light source 31 to the center of the wafer W along the rotation axis A. And irradiate the surface with a predetermined spot diameter (for example, φ100 μm to several hundred μ)
m) is formed. Wafer W
Is reflected by the beam splitter 32,
The light is received by the reflected light detector 33. The optical measuring unit 30 calculates the ratio of the light intensity of the reflected signal light to the probe light based on the light intensity of the reflected signal light detected by the reflected light detector 33 and the signal intensity of the probe light detected by the probe light detector (not shown);
That is, the reflectance of the polished surface is measured.

The wafer W is positioned by the action of the retainer so that the center position of the wafer W coincides with the rotation axis A, and is held by the wafer holder 12 by suction. For this reason, the probe light emitted from the light source 31 is always irradiated to the center position of the wafer W even when the wafer W is attached and detached, and the probe light is irradiated on the rotation axis A. Even if the measurement is performed, the measurement spot position on the wafer surface does not change. Therefore, it is possible to specify the center position of the wafer W and measure the change in the surface state by such means.

FIG. 5 shows a change in the reflectance R detected by the optical measurement unit 30 similar to the above when a wafer having a fixed wiring pattern is continuously polished by metal CMP in the damascene process. . The original wafer surface that initiated the polishing is entirely the metal layer is formed, the reflectance detected by the optical measuring unit 30 hardly changes in the state of high value R _M. On the other hand, as the polishing of the metal layer progresses to a certain extent, the barrier layer (stopper layer) as an underlayer gradually increases.
Is exposed, and the detected reflectance gradually decreases as the polishing process progresses. And if the extra metal layer is removed, the area of the metal electrode will not change,
The reflectance of the reflective signal light is also not change at low R _B. Therefore, by detecting the reflectance R detected in this way and measuring the change, when the reflectance reaches a predetermined reflectance (for example, R _B in the figure), the end point of the polishing process, that is, the polishing is finished. An end point can be determined.

In the CMP apparatus 1 according to the present embodiment, the optical measuring unit 30 is configured such that the center position of the wafer is the polishing head 2
The surface state at the same position (the die area at the wafer center position, the pattern position in the specific die area) is continuously measured except during the time when the polishing pad 21 is covered by the swing of 0. Accordingly, the change characteristic of the reflectance detected by the optical measurement unit 30 is similar to the characteristic shown in FIG. 5 except that the center position of the wafer is covered with the polishing pad 21.

Further, the pattern on the surface to be polished to the optical measuring unit 30 is measured, because it is specified as a pattern of the wafer center position, the value R _B of the reflectance corresponding to the polishing end point in the pattern also known is there. Therefore, by setting the value R _B of the reflectance as a criterion value in advance in the optical measurement chamber 30, it is possible to determine the polishing endpoint accurately and highly accurately be detachably replace the wafer W.

The polishing end point determined in this way is C
It is output to an operation control device 80 that controls the operation of the MP device 1, and the operation control device 80 ends the polishing based on this determination signal. Therefore, the wafer polished by such a CMP apparatus has no variation in the polishing end state, and the CMP process can be efficiently managed to improve the throughput of the CMP apparatus.

Next, the CMP according to the second embodiment of the present invention
The apparatus will be described with reference to FIG. The CMP apparatus 2 includes a wafer table 1 for holding a wafer W by suction on an upper surface thereof.
0, a polishing head 20 on which a polishing pad 21 is mounted on the lower surface, an optical measuring unit 30 for measuring the surface state of the wafer W, and an angular position detecting unit 40 for detecting the rotational angle position of the wafer W This is a CMP apparatus configured to measure the surface state of a specific position on a certain radius from the center of the wafer W and perform polishing.

Since the configuration of the wafer table 10 and the polishing head 20 and the internal configuration of the optical measuring section 30 in the present embodiment are the same as those in the first embodiment, the same portions are assigned the same numbers and duplicated. Description is omitted.

[0044] In the CMP apparatus 2, the probe light irradiation position of the optical measuring unit 30 is not on the rotational axis A of the wafer holder 12 is set to away from the rotation axis A by a predetermined radial distance r ₁ position. Therefore, the probe light emitted from the optical measurement unit 30 traces the die region and the pattern located on the same circumference with the radius r ₁ from the center position of the wafer W when the wafer holder 12 is rotationally driven.

For this reason, the detected reflectance changes with the rotation of the wafer W (change of the measurement position), and the period of the reflectance changes with a period of one rotation of the wafer W (micro-change signal). )become. On the other hand, during the polishing, the reflectance at each position on the surface to be polished changes as shown in FIG. 5 (macro change signal) as the polishing progresses. Since this change similarly occurs on the entire surface to be polished of the wafer W, when continuous measurement is performed during the polishing process, the reflection is such that the micro change signal is added to the macro reflectivity change characteristic shown in FIG. It becomes a rate change signal.

The change signal of the reflectance detected in this manner is an aggregate of the above-described macro change characteristics.
By specifying a position (die region or pattern position) on the rotation circumference of the radius r ₁ and extracting only a signal at the specified position, the reflectance change characteristic at the specified position (FIG. 5)
A similar macro reflectance change characteristic) can be obtained.
The angular position detecting unit 40 is a device for specifying the position on the wafer surface by r ₁ and θ by specifying the rotation angle θ of the wafer W.

The angular position detector 40 includes a light source 41 and a detector 42 for detecting light from the light source 41. The light emitted from the light source 41 is irradiated so as to be incident on the outer peripheral edge of the wafer surface at a predetermined incident angle, and when the wafer W is located at the irradiation position, the reflected light reflected on the wafer surface is incident on the detector 42. The alignment is performed so that the light from the light source 41 does not enter the detector 42 when the wafer W is not located at the irradiation position (or the detection intensity decreases).

Therefore, when the wafer W is held by the wafer holder 12 and driven to rotate, the reflected light is detected by the detector 42 while the wafer W passes through the irradiation position, and the irradiation position is formed on the wafer W. The reflected light is not detected while the notch or the orientation flat passes. Therefore, by measuring the light intensity detected by the detector 42, the moment when the notch or the like of the wafer W passes can be detected, and the angular position of the wafer W can be specified by the detection signal. The signal detected by the angular position detection unit 40 is output to the optical measurement unit 30.

In the optical measuring section 30, the angular position detecting section 40
Is used as a trigger to specify the angular position θ on the rotation circle having the radius r ₁ . For example, when the measurement position of the optical measurement unit 30 and the detection position of the angle position detection unit 40 are on the same straight line including the rotation axis A, and the angle position detection unit 40 detects a notch (for example, The angle position of the wafer W at the time of falling or rising) is θ = 0.
When the notch is detected, the optical measurement unit 30
Is the reflectance of the pattern at the position of the radius r ₁ and the angular position θ = 0 degrees (the specific position specified by r ₁ and θ ₀ ).

The optical measuring unit 30 extracts only the reflectance signal at the specific position (r ₁ , θ ₀ ) specified from the reflectance change signal detected by the reflected light detector 31 and performs the identification. Measure the change in reflectivity at the location. In this case, the obtained measurement data of the specific position is discrete reflectance change data because sampling is performed once per wafer rotation, but the time width of the area where the reflectance changes (FIG. 5)
Reflectance is short enough sampling interval relative to the time width) that varies from R _M to R _B, it is possible to obtain substantially the same reflectance change characteristics Figure 5 in.

The reflectivity measured after a predetermined delay time t (delay) within one rotation cycle from the notch detection signal is calculated from the angular position of θ = 0 on the radius r _{1 of the} wafer W. Is the reflectance of the pattern at the angular position θ _t rotated by the rotation angle corresponding to Accordingly, by extracting only the reflectance signal at the specific position (r ₁ , θ _t ) from the reflectance change signal detected by the reflected light detector 31, an arbitrary position on the radius r ₁ of the wafer W is specified. Thus, the change in reflectance at the specific position can be measured.

The optical measuring section 30 determines the polishing end point from the reflectance change characteristics of the specific position thus obtained in the same manner as in the above embodiment. Therefore, according to the CMP apparatus 2 configured as described above, one or more arbitrary positions (die regions or pattern positions) located on a predetermined radius can be specified to accurately determine the polishing end point. .

Further, in the CMP apparatus 2, it is not necessary to monitor the center position of the wafer W by the optical measuring unit 30. Therefore, by measuring an appropriate radial position other than the swing range of the polishing head 20, the measurement spot of the optical measurement unit 30 is not covered with the polishing pad 21, and the reflectance measurement is not interrupted. For this reason, the change in film thickness during the polishing process can be more finely measured in real time, and highly accurate end point detection can be performed. As a result, it is possible to produce a wafer having a uniform polishing end state,
Throughput can be improved by efficiently managing the P process.

In the embodiment described above, the wafer W
The angle position detecting unit 40 is used as a means for detecting the angular position of
Although the embodiment in which the notch or the orientation flat of the wafer W is detected is disclosed, the angular position detecting means only needs to be able to specify the angular position θ of the wafer W, and the angle of the wafer is indirectly obtained from the rotational angle position of the wafer holder 12. The position may be specified.

For example, a small mirror is mounted on the upper surface position, the lower surface position, the outer peripheral surface, and the like of the wafer holder 12 having a fixed relationship with the notch position of the wafer W, and the rotation position of the mirror is monitored by the angular position detector 40. With such a configuration, the intensity of the reflected light increases when the mirror passes through the irradiation position of the light source 41 due to the rotation of the wafer holder 12, so that the configuration is similar to that of the above-described embodiment by using this reflected signal as a trigger. be able to. Further, the angular position detecting means may be configured using a proximity sensor, a magnetic sensor, or the like, or may be configured to detect the rotation angle of the wafer holder 12 with a rotary encoder or the like.

Next, the CMP according to the third embodiment of the present invention will be described.
The apparatus will be described with reference to FIG. The CMP apparatus 3 includes a wafer table 10, a polishing head 20, an optical measuring unit 30, and a wafer angular position detecting unit 40.
The optical measurement unit 30 is attached to the polishing head 20 so as to be movable in the radial direction of the wafer W with respect to the apparatus 2,
This is a CMP apparatus that measures the surface state of a specific position on this movement path and performs polishing.

That is, in the CMP apparatus 3, the optical measurement unit 3
0 is attached to the polishing head 20 via the connecting member 26, and the wafer W
Is configured to be able to reciprocate (swing) in the radial direction.
The swing operation range of the polishing head 20 is set so that the measurement spot of the optical measurement unit 30 reciprocates between the center (radius r = 0) of the wafer W and the outer peripheral edge (r = r _E ). .
The swinging mechanism of the polishing head 20 is provided with a swinging position detecting unit for detecting the swinging position of the head, and a swinging position detection signal detected by this detecting unit is input to the optical measuring unit 30.

The optical measuring section 30 obtains the radial position r of the measurement spot with respect to the wafer W from the swing position detection signal input from the swing position detecting section, and detects the notch of the notch input from the angular position detecting section 40. The angle position θ of the measurement spot is determined based on the detection signal. From the above two detection signals r and θ, for example, (r ₀ ,
θ) and (r ₁ , θ _t ), and the reflected light detector 3
By extracting the reflectance signal of the specific position specified in this manner from the reflectance change signal detected in step 1, an arbitrary position on the wafer W is specified, and the change in the reflectance of the specific position is measured. can do.

In the CMP apparatus 3, the optical measuring section 30 swings together with the polishing head 20, and its movement paths r _{0 to} r _E.
The reflectivity of the pattern passing above is measured. Therefore, by making the rotation speed of the wafer holder 12 sufficiently higher than the swing movement speed of the head member 22 or controlling them synchronously, the same position (die region or pattern position) on an arbitrary radius is specified and reflected. The rate change can be measured. A plurality of specific positions specified in this manner can be provided in the movement range of the optical measurement unit 30, and the change characteristic of the reflectance can be measured at a plurality of radial positions on the wafer.

In a rotary polishing apparatus that performs polishing by rotating the wafer W, the variation in the thickness of the polished film on the surface to be polished is as follows.
In addition to the above-described variation due to the difference in the wiring pattern, there is generally a concentric variation related to the radial position of the wafer.

The CMP apparatus 3 can measure the reflectance at a plurality of specific positions at different radial distances, so that it is possible to measure even the concentric film thickness variation. Therefore, it is possible to accurately determine the polishing end point in consideration of the variation in the film thickness of the entire surface to be polished, and it is possible to produce a wafer with high polishing quality. Thereby, the throughput can be improved by efficiently managing the CMP process.

Next, the CMP according to the fourth embodiment of the present invention will be described.
The apparatus will be described with reference to FIG. This CMP apparatus 4 is different from the above-described CMP apparatus 3 of the third embodiment,
The optical measuring unit 30 is provided so as to be movable in the radial direction of the wafer W by an independent swinging mechanism, and measures the surface condition of a specific position on the moving path to perform polishing. The internal configuration of the wafer table 10, the polishing head 20, the optical measuring unit 30, and the wafer angular position detecting unit 40
And the like are the same as in the above-described embodiments.

In the CMP apparatus 4, the optical measuring unit 30 is configured to be able to reciprocate (oscillate) in the radial direction of the wafer W by a swing mechanism (not shown), and the measurement spot of the optical measuring unit 30 is set at the center of the wafer W. It is arranged so as to be able to reciprocate between (radius r = 0) and the outer peripheral edge (r = r _E ) under appropriate moving conditions. The swing mechanism is provided with a movement position detection unit that detects the movement position of the optical measurement unit 30, and a detection signal is input to the optical measurement unit 30.

The optical measuring section 30 determines the radial position r of the measurement spot on the wafer W from the detection signal input from the moving position detecting section, and uses the notch detection signal input from the wafer angular position detecting section as a reference. Is determined as the angular position θ of the measurement spot. As described above, all the die regions on the wafer W and the pattern positions in the die regions are specified as (r, θ) from the two detection signals r and θ, and are detected by the reflected light detector 31. By extracting the reflectance signal at the specific position specified in this manner from the reflectance change signal, an arbitrary position on the wafer can be specified and the change in the reflectance at the specific position can be measured.

In the CMP apparatus 4, since the optical measuring section 30 has its own moving mechanism, its moving speed and stop position can be set arbitrarily. Therefore, independent measurement conditions can be set without being influenced by the relationship (polishing conditions) between the rotation speed of the wafer holder 12 and the swing speed of the polishing head 20. For example, the optical measurement unit 3
The movement measurement is performed by synchronizing the movement of 0 with the rotation speed of the wafer holder, or the optical measurement unit 30 is intermittently moved to perform multi-point measurement on the same radius or sampling a plurality of times at the same specific position. For example, it is possible to perform weighted measurement on the radius range.

Therefore, a CMP having an independent drive system
According to the apparatus 4, since the reflectance of an arbitrary position on the wafer can be measured separately and independently in parallel with the polishing, the CM
As in the case of the P apparatus 3, the concentric circle thickness variation can be measured by measuring the reflectance of the entire surface of the wafer, and the polishing process is intensively performed while monitoring the reflectance for the portion having a large remaining film thickness. For example, more detailed processing control can be performed. Therefore, it is possible to configure a polishing apparatus capable of accurately determining the polishing end point while correcting the variation in the film thickness of the entire polished surface, and it is possible to produce a wafer with high polishing quality. In addition, a high-throughput CMP apparatus can be provided by efficiently managing the CMP process.

In each of the above embodiments, a semiconductor wafer is exemplified as the object to be polished, and the case where the wafer is polished flat is described. However, the object to be polished is another substrate such as a quartz substrate or a glass substrate. The shape of the surface to be polished may be a curved surface (for example, a curved surface having a convex cross section or a concave cross section) as long as it is rotationally symmetric.

The head member 22 is used as a CMP apparatus.
Is smaller than the diameter of the wafer holder 22, and the polishing apparatus in which the surface to be polished of the wafer is open upward is illustrated. However, the present invention is not limited to such a polishing apparatus. The arrangement and size of the upper and lower portions may be reversed, and the present invention is also applicable to a conventional polishing apparatus as shown in FIG.

In each of the above embodiments, the metal CMP
In the above polishing process, an example in which the optical measuring unit 30 detects the polishing end point by measuring the reflectance of the surface to be polished has been described. However, the polishing apparatus of the present invention is not limited to such a polishing process. Insulation film and element isolation (Shallow
The present invention is also applicable to a polishing process of an insulating film CMP for planarizing an insulating film of Trench Isolation (STI).

FIG. 6 shows an example of the configuration of an optical measuring unit 50 suitable for detecting the polishing end point by measuring the thickness of the insulating film on the surface to be polished in the polishing process of the insulating film CMP.
The optical measuring unit 30 of the CMP apparatuses 1 to 4 described so far.
Instead of or in addition to the optical measurement unit 30, a CMP apparatus capable of accurately detecting the end point of the insulating film CMP is configured.

The overall configuration and operating state of the CMP apparatus when the optical measuring section is replaced are the same as those of the above-described CMP apparatuses 1 to 4, and therefore, duplicate explanations are omitted. Will be described.

The optical measuring unit 50 transmits the probe light emitted from the light source 51 through the light source 51, the lenses 52, 53, and 54 of the illumination system for guiding the probe light emitted from the light source onto the wafer W. A beam splitter 55 for reflecting the reflected signal light, a lens of a measuring system for guiding the reflected signal light returned by the beam splitter, and mirrors 61 and 62;
63, 65, a slit 64, a diffraction grating 66, a linear sensor 67 for detecting the intensity distribution of the reflected signal light, and an arithmetic processing device 68 for receiving and processing the detection signal from the linear sensor 67.

The light source 51 is a white light source having a multi-wavelength component, and a lamp such as a xenon lamp or a halogen lamp, a white LED, or the like can be used. The probe light emitted from the light source 51 is collimated by a lens 52,
3 and the beam 5 after passing through the beam splitter 55.
In 4, the beam is collimated into substantially parallel light, is perpendicularly incident on the wafer W, and forms a beam spot having a predetermined spot diameter (for example, about 200 μm to several mm) on the wafer surface.

Of the signal light reflected from the wafer W, specularly reflected light (0th-order light) passes through the lens 54, is reflected by the beam splitter 55, and is collimated by the lens 61.
The light is converted into substantially parallel light, passes through a slit 64 through a mirror 62 and a lens 63, is collimated again by a lens 65, and then enters a diffraction grating 66. In the diffraction grating 66, the light is diffracted at a diffraction angle corresponding to the wavelength and enters the linear sensor 67.

Considering the reflected signal light from the wafer on which the device pattern is formed, the reflected signal light has many diffraction spots other than the specularly reflected light that cannot be ignored in terms of light quantity. The diffraction spot has a pattern pitch (fine structure period) d, a light wavelength λ, and a diffraction order n (n = 0,
1, 2,...) In the diffraction angle θ direction represented by the following equation.

[0076]

## EQU1 ## dsinθ = nλ

In the optical measuring section 50, the diffracted light is reflected from the wafer W at an angle θ different from the specularly reflected light (zero-order light). Is refracted in a different direction. The slit 64 is provided at the focal position of the lens 63 to which the specularly reflected light is connected.
Is shielded from light. For this reason, the diffracted light cannot reach the diffraction grating 66, and only the regular reflection light enters the diffraction grating 66 and is diffracted at a diffraction angle corresponding to the wavelength.

The specularly reflected light incident on the linear sensor 67 in this manner is diffracted according to the wavelength by the diffraction grating 66 and is separated, so that the light intensity for each wavelength component, that is, the spectral intensity distribution is detected and calculated. The data is input to the processing device 68. Diffracted light has been removed from this spectral intensity distribution,
Since it is not necessary to consider the influence of the pattern pitch, the arithmetic processing is simplified.

The arithmetic processing unit 68 obtains the film thickness from the input spectral intensity distribution. For example, when the surface of the wafer W is SiO ₂
In the case where the interlayer insulating film is formed, the reflectance of white light reflected by the interlayer insulating film has dispersion characteristics according to the film thickness, and the characteristics of the spectral intensity distribution for each film thickness are known. is there. The arithmetic processing unit 68 stores the characteristic data of the spectral intensity distribution with respect to the film thickness set in advance and the linear sensor 6.
Calculation processing for fitting is performed by comparing the spectral intensity distribution input from FIG. 7 and the thickness of the interlayer insulating film is obtained.
At this time, dispersion intensity information of the light source 51 measured in advance is taken into consideration.

Therefore, by monitoring the change in the film thickness of the wafer W thus determined, it can be determined whether or not the wafer has been polished by a predetermined amount and has reached the processing end point.
Thus, the planarization of the interlayer insulating film, that is, the insulating film CMP can be performed in the same manner as the above-described metal CMP.

Next, an embodiment of a method for manufacturing a semiconductor device according to the present invention will be described. FIG. 7 is a flowchart showing a semiconductor device manufacturing process. When the semiconductor manufacturing process is started, first, in step S200, an appropriate processing step is selected from the following steps S201 to S204, and the process proceeds to any one of the steps.

Here, step S201 is an oxidation step for oxidizing the surface of the wafer. Step S202 is CV
C to form insulating film and dielectric film on wafer surface by D
This is a VD process. Step S203 is an electrode forming step of forming electrodes on the wafer by vapor deposition or the like. Step S2
Reference numeral 04 denotes an ion implantation step of implanting ions into the wafer.

After the CVD step (S202) or the electrode forming step (S203), the process proceeds to step S206, where the CMP
Determine whether to perform the process. If not, the process proceeds to step S207; otherwise, the process proceeds to step S205. Step S205 is a CMP process. In the CMP step, the polishing apparatus (CMP 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.

The CMP step (S205) or the oxidation step
After (S201), the process proceeds to step S207. Step S
Reference numeral 207 denotes a photolithography process. In this step, a resist is applied to the wafer, a circuit pattern is printed on the wafer by exposure using an exposure device, and the exposed wafer is developed. Further, in the next step S208, portions other than the developed resist image are removed by etching,
Thereafter, the resist is removed, and this is an etching step of removing unnecessary resist after etching.

Next, it is determined in step S209 whether all necessary processes have been completed, and if not, step S2
Returning to step 00, the previous steps are repeated to form a circuit pattern on the wafer. If it is determined in step S209 that all steps have been completed, the process ends.

In the method of manufacturing a semiconductor device according to the present invention, since the polishing apparatus according to the present invention is used in the CMP process, the throughput of the CMP process is improved. As a result, there is an effect that a semiconductor device can be manufactured at a lower cost than a conventional semiconductor device manufacturing method. Note that the polishing apparatus according to the present invention may be used in a CMP step of a semiconductor device manufacturing process other than the semiconductor device manufacturing process. Further, the semiconductor device manufactured by the semiconductor device manufacturing method according to the present invention is manufactured at a high throughput, so that it is a low-cost semiconductor device.

[0087]

As described above, according to the polishing apparatus of the present invention, there is provided an optical measuring section for optically measuring the surface condition of the surface to be polished, and this optical measuring section is used during polishing. To measure the surface condition at a specific position specified on the polished surface,
The change in the surface state of the polished surface can be accurately grasped. Therefore, it is possible to obtain a polishing apparatus capable of determining the polishing end point with high accuracy during the polishing process, thereby providing a polishing apparatus having a high throughput by efficiently managing the CMP process.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a polishing apparatus according to a first embodiment of the present invention.

FIG. 2 is a schematic configuration diagram illustrating a polishing apparatus according to a second embodiment of the present invention.

FIG. 3 is a schematic configuration diagram illustrating a polishing apparatus according to a third embodiment of the present invention.

FIG. 4 is a schematic configuration diagram illustrating a polishing apparatus according to a fourth embodiment of the present invention.

FIG. 5 is an explanatory diagram showing a reflectance change characteristic of a polished surface detected during polishing in a metal CMP process.

FIG. 6 is a configuration diagram showing another embodiment of the optical measurement unit in each of the polishing apparatuses.

FIG. 7 is a flowchart showing a semiconductor manufacturing process according to the present invention.

FIG. 8 is a schematic configuration diagram showing a conventional polishing apparatus.

FIG. 9 is a schematic configuration diagram showing another configuration example of a conventional polishing apparatus.

[Explanation of symbols]

 W Wafer (object to be polished) 1, 2, 3, 4 CMP apparatus (polishing apparatus) 10 Wafer table 12 Wafer holder (object holding part) 20 Polishing head 21 Polishing pad (polishing member) 30 Optical measuring part 31 Light source (Lighting part) 33) Reflected light detector (light detector) 40 Angular position detector 50 Optical measuring unit 51 Light source (illuminator) 67 Linear sensor (light detector)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) // G01B 11/30 102 G01B 11/30 102Z F term (reference) 2F065 AA50 BB03 CC19 FF44 HH04 3C034 AA08 AA13 BB93 CA05 3C058 AA07 AC02 BA01 BA07 CA01 CA06 CB01 CB03 DA17

Claims (9)

[Claims] An object holding section for holding an object to be polished, and a polishing member for polishing the object to be polished, wherein the polishing member is brought into contact with the object to be polished held by the object holding section. A polishing apparatus configured to relatively move the polishing member and the object to be polished to perform a polishing process on the surface to be polished of the object to be polished, wherein the surface state of the surface to be polished is optically measured. A polishing apparatus, comprising: an optical measuring unit, wherein the optical measuring unit measures a surface state of a specific position on the polished surface during polishing of the polished surface. 2. The object holding section is configured to be able to rotate the object to be polished around a rotation axis orthogonal to the surface to be polished at a center of rotation, and the optical measuring section is configured to transmit probe light to the surface to be polished. And an optical detector for detecting signal light reflected or transmitted from the surface to be polished, and detecting the signal light obtained by irradiating the rotation center position of the surface to be polished with probe light. The polishing apparatus according to claim 1, wherein a surface state of the specific position is measured. 3. The object holding section is configured to be able to rotate the object to be polished around a rotation axis intersecting with the surface to be polished, and the rotation angle position of the object to be polished and the rotation angle of the object holding section An optical position measurement unit configured to irradiate probe light to the surface to be polished, and a light to detect a reflected or transmitted signal light from the surface to be polished; A detecting unit, and measuring the surface state of the specific position by detecting the signal light obtained by irradiating a position specified based on a detection signal from the angular position detecting unit with probe light. The polishing apparatus according to claim 1, wherein: 4. The angular position detecting section optically detects a specific index formed on the object to be polished to detect a rotational angle position of the object to be polished, and the optical measuring section detects the angular position. The polishing apparatus according to claim 3, wherein a surface state of a specific position on the polished surface is measured based on a detection signal of the specific index detected by a unit. 5. An irradiation position of the probe light on the surface to be polished can be relatively moved in a radial direction of the surface to be polished, and the reflected or transmitted signal light by the irradiation can be received on a movement path. The surface state at a specific position where the rotational angle position and the radial position of the surface to be polished are specified is measured.
Alternatively, the polishing apparatus according to claim 4. 6. The polishing member is attached to the polishing apparatus via a moving mechanism that supports the polishing member movably in a radial direction of the object to be polished, wherein the illumination unit and the light detection unit are connected to each other. The polishing apparatus according to claim 5, wherein the polishing apparatus is supported by the moving mechanism and is movable in a radial direction of the polishing target. 7. The apparatus according to claim 1, wherein the light detector selectively extracts only the zero-order light component from the light reflected on the surface to be polished and measures the surface condition of the surface to be polished. The polishing apparatus according to any one of claims 2 to 6. 8. A polishing process for a surface to be polished of the object to be polished by moving the object holding part and the polishing member relatively while bringing the object to be polished held by the object holding part into contact with a polishing member. In the polishing method, measuring the change in the surface state of the specific position in the polished surface during the polishing process of the polished surface using an optical measurement unit that optically measures the surface state of the polished surface, A polishing method, comprising: controlling a polishing process based on a measurement result of a surface state at a specific position to be measured. 9. An object to be polished is a semiconductor wafer, comprising a step of flattening the surface of the semiconductor wafer by using the polishing apparatus according to claim 1. Description: Semiconductor device manufacturing method.