CN116810618A - Optical measuring device for CMP and chemical mechanical polishing equipment - Google Patents

Abstract

The application discloses an optical measuring device and chemical mechanical polishing equipment for CMP, wherein the optical measuring device comprises: an in-line optical measurement assembly including a first optical sensor and a first window for measuring a nonmetallic film thickness of a wafer, and a reference optical measurement assembly including a second optical sensor for obtaining a calibration light intensity, a second window, a calibration sheet, and a shutter assembly.

Description

Optical measuring device for CMP and chemical mechanical polishing equipment

Technical Field

The application relates to the technical field of chemical mechanical polishing, in particular to an optical measuring device for CMP and chemical mechanical polishing equipment.

Background

Wafer fabrication is a key element in restricting the development of the ultra/very large scale integrated circuit (i.e., chip, IC, integrated Circuit) industry. As moore's law continues, integrated circuit feature sizes continue to shrink to approach theoretical limits, and wafer surface quality requirements become more stringent, so that wafer fabrication process control over defect size and number becomes more stringent. Chemical mechanical polishing (Chemical Mechanical Planarization, CMP) is a global surface planarization technique used in semiconductor manufacturing to reduce the effects of wafer thickness variations and surface topography. CMP has become one of the most widely used surface planarization techniques in semiconductor manufacturing processes because it can precisely and uniformly planarize wafers to the desired thickness and flatness.

The chemical mechanical polishing process is to press a wafer against the surface of a polishing pad with a carrier head, and to polish the surface of the wafer by means of relative motion between the wafer and the polishing pad and by means of abrasive particles in a polishing liquid. For nonmetallic polishing process control, an off-line measuring device is generally used for measuring the film thickness of the nonmetallic layer, parameters such as film thickness change before and after wafer polishing in the past are obtained to build a model, and then the value before the wafer film thickness is measured to perform feedback control on polishing pressure, polishing duration and the like.

The control of the polishing endpoint during chemical mechanical polishing is important to determine whether the film has been planarized to a desired flatness or thickness, or to determine when a desired amount of material has been removed. On the one hand, overpolishing (removing too much) can result in increased circuit resistance. On the other hand, insufficient polishing (removal of too little) can result in electrical shorting. Variations in the initial thickness of the film, variations in the slurry composition, variations in the state of the polishing pad, variations in the relative speed between the polishing pad and the wafer, and variations in the polishing pressure can result in variations in the material removal rate. These variations result in variations in the time required to reach the polishing endpoint. Therefore, in the prior art, the offline measurement mode is difficult to accurately acquire the film thickness of the wafer in real time, the polishing pressure and the polishing time are difficult to adjust in real time, the polishing endpoint cannot be accurately controlled, and the over-polishing or under-polishing condition is caused.

Disclosure of Invention

The embodiment of the application provides an optical measuring device for CMP and chemical mechanical polishing equipment, which aim to at least solve one of the technical problems in the prior art.

A first aspect of an embodiment of the present application provides an optical measurement device for CMP, including: an in-line optical measurement assembly including a first optical sensor and a first window for measuring a nonmetallic film thickness of a wafer, and a reference optical measurement assembly including a second optical sensor for obtaining a calibration light intensity, a second window, a calibration sheet, and a shutter assembly.

In some implementations, the in-line optical measurement assembly rotates with the polishing platen to perform in-line non-metallic film thickness measurement while polishing, the first optical sensor is disposed inside the polishing platen, the first window is embedded in the polishing pad surface at a corresponding position above the first optical sensor, and an optical path of the first optical sensor irradiates the wafer through the first window.

In some implementations, the reference optical measurement assembly is mounted inside the polishing disk to obtain the calibration light intensity, the second optical sensor and the second window are disposed opposite to each other, the calibration sheet is attached to a side of the second window away from the second optical sensor, and the shielding assembly is used for shielding between the second optical sensor and the second window.

In some implementations, the first window and the second window are identical.

In some implementations, the first optical sensor is positioned at a linear distance from the first window that coincides with a linear distance from the second optical sensor to the second window.

In some implementations, the first optical sensor and the second optical sensor are connected to the same light source and the same detection unit, respectively, through optical paths having equal optical paths.

In some implementations, the first optical sensor and the second optical sensor are connected to the same light source and the same detection unit, respectively, through an X-type optical fiber; the input end of one side of the X-shaped optical fiber is connected with the light source, the output end of one side of the X-shaped optical fiber is connected with the detection unit, one of the input and output ends of the other side of the X-shaped optical fiber is connected with the first optical sensor, and the other input and output end of the other side of the X-shaped optical fiber is connected with the second optical sensor.

In some implementations, the shutter assembly includes a light blocking member and a drive module coupled to the light blocking member and capable of driving the light blocking member between the second optical sensor and the second window.

In some implementations, the light blocking member moves between the second optical sensor and the second window upon polishing; the light blocker is moved away to clear the second optical sensor from the second window during maintenance.

A second aspect of an embodiment of the present application provides a chemical mechanical polishing apparatus including a carrier head, a polishing platen, a dresser, a liquid supply portion, and the optical measurement device described above.

The beneficial effects of the embodiment of the application include:

a. the light intensity can be conveniently calibrated, and the deviation of a measurement result caused by the light intensity drift of the light source is avoided;

b. the first optical sensor and the second optical sensor are respectively connected with the same light source and the same detection unit through light paths with equal light paths, so that other interference factors are avoided, and the light intensity obtained by the second optical sensor can be used as a calibration light intensity;

c. the reference light intensity signal can be obtained at any time by arranging the light intensity calibration unit in the polishing unit, so that the state of the white light measurement module integrated in the polishing unit is conveniently monitored, the PM period is reduced, and a certain effect is generated on yield improvement.

Drawings

The advantages of the present application will become more apparent and more readily appreciated from the detailed description given in conjunction with the following drawings, which are meant to be illustrative only and not limiting of the scope of the application, wherein:

FIG. 1 illustrates a chemical mechanical polishing apparatus provided in accordance with one embodiment of the present application;

FIG. 2 illustrates a chemical mechanical polishing apparatus provided in accordance with one embodiment of the present application;

FIG. 3 shows a master control module according to an embodiment of the present application;

FIG. 4 shows the relationship between the reflection spectrum and the film thickness;

fig. 5 shows the steps of a method for measuring a film thickness of a wafer according to an embodiment of the application.

Detailed Description

The following describes the technical scheme of the present application in detail with reference to specific embodiments and drawings thereof. The examples described herein are specific embodiments of the present application for illustrating the concept of the present application; the description is intended to be illustrative and exemplary in nature and should not be construed as limiting the scope of the application in its aspects. It should be noted that, without conflict, the embodiments of the present application and features of the embodiments may be combined with each other. In addition to the embodiments described herein, those skilled in the art can adopt other obvious solutions based on the disclosure of the claims and the specification thereof, including those adopting any obvious substitutions and modifications to the embodiments described herein. It should be understood that the following description of the embodiments of the present application, unless specifically stated otherwise, is established in the natural state of the relevant devices, apparatuses, components, etc. in which no external control signal or driving force is given, in order to facilitate understanding.

In addition, it is noted that terms used herein such as front, back, upper, lower, left, right, top, bottom, front, back, horizontal, vertical, etc. are merely for convenience of description and are not intended to limit any device or structure orientation to aid in understanding the relative position or orientation.

In order to describe the technical solution according to the application, reference will be made to the accompanying drawings and examples.

In the present application, chemical mechanical polishing (Chemical Mechanical Polishing) is also called chemical mechanical planarization (Chemical Mechanical Planarization), and wafer is also called wafer, silicon wafer, substrate, or substrate (substrate), etc., and its meaning and actual effect are equivalent.

The application provides a scheme capable of realizing online measurement of the nonmetallic film thickness of the wafer surface in the chemical mechanical polishing process, which is suitable for realizing polishing endpoint monitoring by using an optical detection mode; the optical detection mode tracks the process progress by detecting the change of the reflection spectrum of the surface of the wafer, so as to judge the end point of the polishing process. The optical detection mode is used as a non-contact measurement method, and can measure the film material change in the polishing process without damaging the film on the surface of the wafer.

As shown in fig. 1, the chemical mechanical polishing apparatus includes a carrier head 10 for holding and rotating a wafer w, a polishing disk 20 covered with a polishing pad 21, a dresser 30 for dressing the polishing pad 21, and a liquid supply portion 40 for supplying a polishing liquid.

In the chemical mechanical polishing process, the carrier head 10 presses the wafer w against the polishing pad 21 covered by the surface of the polishing platen 20, and the carrier head 10 makes a rotational motion and reciprocates in the radial direction of the polishing platen 20 so that the surface of the wafer w in contact with the polishing pad 21 is gradually polished while the polishing platen 20 rotates, and the liquid supply part 40 sprays the polishing liquid to the surface of the polishing pad 21. The wafer w is rubbed against the polishing pad 21 by the relative motion of the carrier head 10 and the polishing platen 20 under the chemical action of the polishing liquid to perform polishing. The conditioner 30 is used to condition and activate the surface topography of the polishing pad 21 during polishing. The use of the dresser 30 can remove impurity particles remaining on the surface of the polishing pad 21, such as abrasive particles in the polishing liquid, and waste material detached from the surface of the wafer w, and can planarize the surface deformation of the polishing pad 21 due to the polishing.

As shown in fig. 2, the chemical mechanical polishing apparatus further includes an optical measuring device 50, and the optical measuring device 50 is disposed below the disk surface of the polishing disk 20 and rotates following the polishing disk 20 to perform online measurement while polishing. The polishing pad 21 is provided with a light transmissive aperture that extends through the polishing pad 21 to provide an optical pathway through the polishing pad 21. The light emitted from the optical measuring device 50 is irradiated to the surface of the wafer w on the polishing pad 21 through the opening and receives the reflected light of the wafer w through the window to determine the nonmetallic film thickness of the wafer w from the spectrum of the reflected light.

During polishing of the wafer w, the carrier head 10 presses the wafer w against the polishing pad 21 and the carrier head 10 reciprocates in the radial direction of the polishing platen 20, and the optical measurement device 50 rotates following the polishing platen 20, so that the positions of sampling points measured on the wafer w by the optical measurement device 50 are constantly changed, and thus optical measurement signals of different radial positions of the wafer w can be acquired.

As shown in fig. 2, in one embodiment of the present application, an optical measurement device 50 is used to measure the nonmetallic film thickness of a wafer during chemical mechanical polishing, comprising: an in-line optical measurement assembly including a first optical sensor 51 and a first window 52 for measuring a nonmetallic film thickness of a wafer, and a reference optical measurement assembly; the reference optical measurement assembly comprises a second optical sensor 53 for obtaining a calibration light intensity, a second window 54, a calibration sheet 55 and a shielding assembly.

The in-line optical measuring assembly rotates along with the polishing platen 20, thereby realizing in-line non-metal film thickness measurement while polishing, the first optical sensor 51 is disposed inside the polishing platen 20, the first window 52 is embedded inside the polishing pad 21 at a corresponding position above the first optical sensor 51, and the optical path of the first optical sensor 51 is irradiated to the wafer w through the first window 52.

In one embodiment, the first optical sensor 51 is disposed inside the polishing disk 20, a receiving groove is disposed on the surface of the polishing disk 20, the first optical sensor 51 is disposed in the receiving groove, and the first optical sensor 51 is connected to the main control module 60 through a first optical fiber. The first window 52 is embedded inside the polishing pad 21, and the first window 52 is disposed directly above the first optical sensor 51. Specifically, the polishing pad 21 is provided with a through-hole at a position corresponding to a position directly above the first optical sensor 51, and the first window 52 is inserted into the through-hole.

The light emitted from the first optical sensor 51 is irradiated to the surface of the wafer w on the polishing pad 21 through the first window 52 and receives the reflected light of the wafer w via the first window 52 to determine the nonmetallic film thickness of the surface of the wafer w from the spectrum of the reflected light.

The reference optical measurement assembly is used to calibrate the light intensity. As shown in fig. 2, in one embodiment, a reference optical measurement assembly is mounted inside the polishing platen 20, the reference optical measurement assembly including a second optical sensor 53, a second window 54, a calibration sheet 55, and a shutter assembly. The second optical sensor 53, the second window 54, the calibration sheet 55, and the shutter assembly are all located inside the polishing pad 20. The second optical sensor 53 is used to obtain a calibrated light intensity. Specifically, the calibration sheet 55 is a standard silicon wafer for calibrating the light intensity.

Further, the second optical sensor 53 and the second window 54 are disposed opposite to each other, and the calibration sheet 55 is attached to a side of the second window 54 away from the second optical sensor 53. In other words, the calibration sheet 55 is closely attached to the second window 54 and is located on a side of the second window 54 away from the second optical sensor 53. Specifically, as shown in fig. 2, as a specific example, the detection end of the second optical sensor 53 faces downward, the second window 54 is located below the second optical sensor 53, the upper surface of the second window 54 is opposite to the detection end of the second optical sensor 53, the lower surface of the second window 54 is closely attached to the calibration piece 55, there is no gap between the calibration piece 55 and the lower surface of the second window 54, and the optical path of the second optical sensor 53 emits downward and reaches the calibration piece 55 through the second window 54, and is reflected by the calibration piece 55 to obtain the calibration light intensity.

Of course, as another implementation manner, the detection end of the second optical sensor 53 may be upward, the second window 54 is located above the second optical sensor 53, so that the lower surface of the second window 54 is opposite to the detection end of the second optical sensor 53, the upper surface of the second window 54 is closely attached to the calibration piece 55, and there is no gap between the calibration piece 55 and the upper surface of the second window 54, in this case, the light path of the second optical sensor 53 emits upward, passes through the second window 54, reaches the calibration piece 55, and is reflected by the calibration piece 55. Alternatively, the detection end of the second optical sensor 53 may also face in a forward, backward, leftward, backward or even downward direction, as long as one surface of the second window 54 faces the detection end of the second optical sensor 53, and the other surface of the second window 54 is closely attached to the calibration sheet 55, so long as the optical paths for obtaining the calibration light intensity are within the scope of the present application, and the relative positions among the second optical sensor 53, the second window 54 and the calibration sheet 55 are not limited to the above list.

In addition, the first window 52 and the second window 54 are identical, i.e., the first window 52 and the second window 54 are identical in size, thickness, material, shape, etc. The linear distance of the first optical sensor 51 from the first window 52 is equal to the linear distance of the second optical sensor 53 from the second window 54. During chemical mechanical polishing, the wafer w is pressed against the polishing pad 21 by the carrier head 10, and the wafer passes through the first window 52 and is brought into close contact with the upper surface of the first window 52.

Therefore, the optical path of the light emitted from the first optical sensor 51 reaching the surface of the wafer through the first window 52 is the same as the optical path of the light emitted from the second optical sensor 53 reaching the surface of the calibration sheet 55 through the second window 54 when the first optical sensor 51 measures the wafer, and the optical paths of the two optical paths are the same, and only the measured object is different, so as to exclude the interference of other factors, thereby obtaining the calibration light intensity by using the signal measured by the second optical sensor 53 as a reference.

As shown in fig. 2, the shielding assembly is used to provide shielding between the second optical sensor 53 and the second window 54. In one embodiment, the shutter assembly includes a light blocking member 56 and a drive module 57, the drive module 57 being coupled to the light blocking member 56 and being capable of driving the light blocking member 56 between the second optical sensor 53 and the second window 54. The light blocking member 56 is movable between the second optical sensor 53 and the second window 54 to block the optical path between the second optical sensor 53 and the second window 54; the light blocking member 56 can also be moved out between the second optical sensor 53 and the second window 54 to clear the optical path between the second optical sensor 53 and the second window 54. The light blocking member 56 may be made of light absorbing material, and the surface is not reflective. The driving module 57 is connected to the main control module 60 so that the movement of the light blocking member 56 can be manipulated under the control of a program. Specifically, the driving module 57 can control the light blocking member 56 to swing, moving in and out between the second optical sensor 53 and the second window 54.

In the embodiment shown in fig. 2, the first optical sensor 51 and the second optical sensor 53 are connected to the main control module 60 through optical fibers, respectively. The main control module 60 is located inside the polishing pad 20 and rotates with the polishing pad 20. The main control module 60 is connected to other devices located outside the polishing pad 20 through a rotary joint. The connection wires of the main control module 60 lead out the electrical signals through the rotary joint, thereby avoiding the damage caused by the torsion of the wires.

As shown in fig. 3, the main control module 60 includes a light source 61, a detection unit 62, a data acquisition and communication unit 63, a central processing unit 64, and an external interface 65.

In one embodiment, the first optical sensor 51 and the second optical sensor 53 are respectively connected to the same light source 61 and the same detection unit 62 through optical paths with equal optical paths, so as to avoid introducing other interference factors, and ensure that the light intensity obtained by the second optical sensor 53 can be used as the calibration light intensity.

Specifically, as shown in fig. 3, the first optical sensor 51 and the second optical sensor 53 are connected to the light source 61 and the detection unit 62 through an X-type optical fiber, respectively. Wherein, the input end of one side of the X-shaped optical fiber is connected with the light source 61, the output end of one side of the X-shaped optical fiber is connected with the detection unit 62, one of the input and output ends of the other side of the X-shaped optical fiber is connected with the first optical sensor 51, and the other input and output end of the other side of the X-shaped optical fiber is connected with the second optical sensor 53. Thereby realizing that the light source 61 signal provided by the light source 61 is divided into two identical optical input signals to reach the first optical sensor 51 and the second optical sensor 53 through two optical paths which are completely symmetrical and have equal optical paths. Specifically, the light source 61 signal output by the light source 61 is divided into two identical signals, namely a first optical input signal and a second optical input signal, through a symmetrical light path; the first optical sensor 51 receives a first optical input signal and the second optical sensor 53 receives a second optical input signal, the first optical input signal received by the first optical sensor 51 being identical to the second optical input signal received by the second optical sensor 53.

Further, the first optical sensor 51 outputs a first optical output signal to be sent to the detection unit 62, the second optical sensor 53 outputs a second optical output signal to be sent to the detection unit 62, and transmission routes of the first optical output signal and the second optical output signal are symmetrical and have equal optical paths, so that other interference is avoided.

As shown in fig. 3, the light source 61 and the detection unit 62 are respectively connected to the data acquisition and communication unit 63, the data acquisition and communication unit 63 is respectively connected to the central processing unit 64 and the external interface 65, and the central processing unit 64 is also connected to the external interface 65.

During chemical mechanical polishing, the program sets the light blocking member 56 to move between the second optical sensor 53 and the second window 54, the light emitted by the second optical sensor 53 is absorbed by the light blocking member 56 and cannot return, that is, no reflected light is generated, the second optical sensor 53 does not feed back a signal, no interference occurs to the optical signal collected by the first optical sensor 51, the light emitted by the first optical sensor 51 is reflected by the wafer through the first window 52 and received by the first optical sensor 51, and at this time, the detection unit 62 receives only the first optical output signal collected by the second optical sensor 53, thereby obtaining the film thickness of the wafer.

During maintenance of the apparatus, after the polishing pad is replaced, a light absorbing sheet is placed over the first window 52, light emitted from the first optical sensor 51 is absorbed by the light absorbing sheet and no reflected light is generated, the first optical sensor 51 does not feed back a signal, in addition, the light blocking member 56 is programmed to be removed so that no shielding exists between the second optical sensor 53 and the second window 54, light emitted from the second optical sensor 53 is reflected by the calibration sheet 55 through the second window 54 and received by the second optical sensor 53, and at this time, only the second optical output signal collected by the second optical sensor 53 is received by the detection unit 62, thereby obtaining the calibration light intensity.

Aiming at the problem of light intensity drift of the light source 61, the light intensity needs to be calibrated before measurement, the application provides a built-in optical light intensity signal calibration device based on X-type optical fibers, which is used for calibrating the light intensity of the light source 61.

According to the optical measuring device provided by the embodiment of the application, the reference light intensity signal can be obtained at any time by arranging the light intensity calibration unit in the optical measuring device, so that the state of the white light measuring module integrated in the polishing unit can be monitored conveniently, the PM period is reduced, and a certain effect is generated on yield improvement.

On the other hand, based on the above chemical mechanical polishing apparatus, an embodiment of the present application further provides a method for measuring a film thickness of a wafer, including:

collecting a reflection spectrum in the initial polishing stage, and obtaining the number n of spectrum peaks or troughs of the reflection spectrum;

and selecting and using an FFT algorithm or a spectrum fitting algorithm Jie Suan wafer film thickness according to the number of the spectrum peaks or the spectrum troughs.

In one embodiment, if the number N of spectral peaks or troughs is greater than a preset threshold N, i.e., N > N, then selecting an FFT algorithm to resolve the reflectance spectrum;

if the number N of the spectral peaks or the troughs is not greater than a preset threshold N, namely N is less than or equal to N, a spectral fitting algorithm is selected to calculate the reflection spectrum.

Wherein, through experience such as test data, confirm to predetermine threshold value N and be a certain constant.

When white light is used to measure the thickness of the nonmetallic film layer on the surface of the wafer, as shown in fig. 4, the characteristic value in the reflection spectrum obtained by the optical measurement device is related to the thickness of the film layer on the surface of the wafer, and as shown in fig. 4, 1 extreme point (namely, spectrum peak or trough) is present in the characteristic value of the reflection spectrum with the thickness of 270 nm; the characteristic value of the reflection spectrum with the film thickness of 500nm has 3 extreme points; in the characteristic value of the reflection spectrum with the film thickness of 1040nm, 5 extreme points exist; the corresponding spectrum analysis algorithm can be selected according to the number of extreme points (namely the number of spectrum peaks or troughs), so that the reliability of the measurement result is improved.

As shown in fig. 5, the specific steps of the wafer film thickness measurement method include:

step S01, polishing is started;

s02, collecting a reflection spectrum;

step S03, performing signal processing to obtain the number N of spectral peaks or troughs of the reflection spectrum, judging the size relation between the number N and a preset threshold N, and judging whether N > N is satisfied;

step S04, if N > N is satisfied, selecting an FFT algorithm to calculate a reflection spectrum to obtain the thickness of the wafer;

s05, if N > N is not satisfied, calculating a reflection spectrum by using a spectrum fitting algorithm to obtain the thickness of the wafer;

step S06, judging whether the polishing end point is reached according to the obtained film thickness of the wafer, and ending polishing if the polishing end point is reached;

and step S07, if the end point is not reached, continuing polishing and returning to step S02 to execute the wafer film thickness measuring method again.

Further, the spectral fitting algorithm includes:

in the polishing process, a measurement spectrum is generated according to the collected reflection spectrum;

selecting a spectral set of reference spectra closest to the measured spectrum;

the film thickness corresponding to the spectral group of the closest reference spectrum is estimated as the film thickness of the wafer.

In addition, before the spectrum fitting algorithm is adopted, it is necessary to prepare a spectrum group of a plurality of reference spectrums corresponding to different film thicknesses in advance.

In this embodiment, the reference spectrum is:

wherein n is the refractive index; lambda is the wavelength; a. b and c are constants which are related to the material, thickness, etc. of the measured sample.

In this embodiment, the maximum value is selected by using the following formula, so as to select the spectrum group of the reference spectrum closest to the measured spectrum:

wherein x is _i For the fitted theoretical spectral abscissa values, typically wavelengths, i=1, 2, …, n; y is _i To measure the spectrum at wavelength x _i Relative reflectance values at, y (x _i ) For fitting theoretical spectra at wavelength x _i Relative reflectance values at.

In one embodiment, the FFT algorithm comprises:

performing fast Fourier transform on the reflection spectrum, performing time domain-frequency domain transform, and extracting the relation between the frequency component and the frequency spectrum intensity;

and converting the relation between the frequency component and the spectrum intensity by using the thickness function to generate the relation between the thickness and the spectrum intensity.

In summary, according to the wafer film thickness measuring method provided by the application, the reflection spectrum information is collected at the polishing starting stage, the specifically used algorithm model is judged according to the characteristics of the reflection spectrum, and the measuring error caused by unmatched measured actual film thickness and algorithm is avoided by adopting a priori algorithm switching mode. Aiming at the problem of resolving accuracy of the spectrum fitting algorithm and the FFT algorithm on wafer film thicknesses in different thickness ranges, the application provides an priori algorithm mode recognition model. The corresponding spectrum information processing algorithm model can be automatically identified and switched according to the collected spectrum information in the polishing process. And establishing a priori model judgment feedback flow, realizing self-adaptive adjustment of a polishing process calculation algorithm model based on a priori value, selecting the most suitable thickness calculation algorithm according to the analysis data and the logical judgment of the priori value, reducing measurement errors caused by overlarge polishing process range, and realizing accurate thickness identification and end point judgment in a large range.

The drawings in the present specification are schematic views, which assist in explaining the concept of the present application, and schematically show the shapes of the respective parts and their interrelationships. It should be understood that for the purpose of clearly showing the structure of various parts of embodiments of the present application, the drawings are not drawn to the same scale and like reference numerals are used to designate like parts in the drawings.

In the description of the present specification, reference to the terms "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the application. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiments or examples. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

While embodiments of the present application have been shown and described, it will be understood by those of ordinary skill in the art that: many changes, modifications, substitutions and variations may be made to the embodiments without departing from the spirit and principles of the application, the scope of which is defined by the claims and their equivalents.

Claims (10)

1. An optical measurement device for CMP, comprising: an in-line optical measurement assembly including a first optical sensor and a first window for measuring a nonmetallic film thickness of a wafer, and a reference optical measurement assembly including a second optical sensor for obtaining a calibration light intensity, a second window, a calibration sheet, and a shutter assembly.

2. The optical measuring device according to claim 1, wherein the in-line optical measuring unit rotates along with the polishing platen to perform in-line non-metal film thickness measurement while polishing, the first optical sensor is disposed inside the polishing platen, the first window is embedded in the surface of the polishing pad at a corresponding position above the first optical sensor, and an optical path of the first optical sensor is irradiated to the wafer through the first window.

3. The optical measurement device of claim 1 wherein the reference optical measurement assembly is mounted within the polishing platen to obtain a calibrated light intensity, the second optical sensor and the second window are positioned opposite, the calibration sheet is affixed to a side of the second window remote from the second optical sensor, and the shielding assembly is configured to provide shielding between the second optical sensor and the second window.

4. The optical measurement device of claim 1 wherein the first window and the second window are identical.

5. The optical measurement device of claim 4 wherein the first optical sensor is a linear distance from the first window that coincides with the linear distance of the second optical sensor from the second window.

6. The optical measurement device of claim 5 wherein the first optical sensor and the second optical sensor are connected to the same light source and the same detection unit respectively through optical paths having equal optical paths.

7. The optical measurement device of claim 6, wherein the first optical sensor and the second optical sensor are connected to the same light source and the same detection unit, respectively, through an X-type optical fiber; the input end of one side of the X-shaped optical fiber is connected with the light source, the output end of one side of the X-shaped optical fiber is connected with the detection unit, one of the input and output ends of the other side of the X-shaped optical fiber is connected with the first optical sensor, and the other input and output end of the other side of the X-shaped optical fiber is connected with the second optical sensor.

8. The optical measurement device of claim 1 wherein the shutter assembly includes a light blocking member and a drive module coupled to the light blocking member and capable of driving the light blocking member between the second optical sensor and the second window.

9. The optical measurement device of claim 8 wherein the light blocking member moves between the second optical sensor and the second window during polishing; the light blocker is moved away to clear the second optical sensor from the second window during maintenance.

10. A chemical mechanical polishing apparatus comprising a carrier head, a polishing platen, a conditioner, a liquid supply, and an optical measurement device according to any one of claims 1 to 9.