TW201524674A - Polishing end point detection method and polishing end point detection apparatus - Google Patents

Abstract

There is provided a polishing end point detection method of improving the accuracy of detecting a polishing end point. The polishing end point detection method emits light toward a polishing object including a hybrid film made of a nanocarbon material and a light-transmissive material while polishing the polishing object (Step S102). Then, the polishing end point detection method receives light reflected from the polishing object (Step S103). Then, the polishing end point detection method subjects the received reflected light to signal processing (Step S104). Then, the polishing end point detection method determines the polishing end point of the polishing object based on the result of the signal processing (Step S105), and detects the polishing end point (Step S106).

Description

Grinding end point detecting method and grinding end point detecting device

The present invention relates to a polishing end point detecting method and a polishing end point detecting device.

In the past, copper or tungsten was used as a wiring material for a semiconductor circuit or the like. The resistance of these wiring materials increases as the size of the semiconductor circuit or the like is reduced. As a result, the reliability is lowered due to a decrease in current capacitance. Therefore, a nanocarbon material which is expected to have low resistance and high reliability even if the line width is narrow is attracting attention as a next-generation wiring material.

The nanocarbon material includes, for example, MLG (Multi-Layer Graphene) of stacked graphene sheets, and carbon nanotubes (CNT: Carbon nanotube). The MLG is used, for example, as a lateral wiring in a semiconductor circuit. The carbon nanotubes are used, for example, as longitudinal wiring (Via) in a semiconductor circuit.

In addition, a substrate such as a semiconductor wafer including a wiring of a nanocarbon material is polished by a polishing apparatus such as a CMP (Chemical Mechanical Polishing apparatus). When the substrate is polished by a polishing apparatus, polishing is performed. The end point is judged.

In this regard, the past technology was determined by the operator to visually determine the end point of the grinding. That is, the worker stops polishing after starting the polishing for a predetermined period of time to visually confirm the surface of the substrate (for example, the color of the surface of the substrate, etc.). When the operator judged that the polishing was insufficient by the visual result, the polishing was started again, and after a predetermined period of time, the polishing was stopped, and the surface of the substrate was visually confirmed. In the past, the optimum polishing end point was determined by repeating polishing and visual determination.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. Hei 10-202523

Past technology has not considered improving the detection accuracy of the polishing end point.

That is, since the past technique determines the polishing end point by visual observation by the operator, the polishing end point is deviated. Further, since the worker uses the visual judgment to perform the grinding and the visual judgment repeatedly, the man-hours increase. Further, in the past, in order to confirm the polishing state, the substrate thickness may be observed by a fracture observation such as a cross-sectional SEM. However, since this method is accompanied by destruction of the substrate, it cannot be used in the process of actually manufacturing the product.

Therefore, the object of one aspect of the present invention is to improve the detection accuracy of the polishing end point.

In one aspect of the method for detecting a polishing end point of the present invention, in view of the above-described problems, a polishing object including a mixed film of a nanocarbon material and a light-transmitting material is polished, and light is irradiated onto the object to be polished. The light reflected by the object to be polished detects the polishing end point of the object to be polished.

In one aspect of the polishing end point detecting method of the present invention, the step of detecting the polishing end point of the object to be polished may be a spectroscopic interference method for measuring the film thickness of the object to be polished based on the phase difference of the light reflected from the object to be polished. To detect the aforementioned object to be polished Grinding the end point.

In one aspect of the polishing end point detecting method of the present invention, the step of detecting the polishing end point of the polishing target object may be based on a change in the combined wave intensity of the light reflected from the plurality of reflecting surfaces of the polishing target object, and the polishing target The polishing rate of the object is used to detect the polishing end point of the object to be polished.

In one aspect of the polishing end point detecting method of the present invention, in the step of detecting the polishing end point, the polishing end point of the polishing target object can be detected based on a spectral change of light reflected from the polishing object.

In one aspect of the polishing end point detecting method of the present invention, the step of detecting the polishing end point compares a predetermined spectral waveform with a spectral waveform of light reflected from the polishing object, and detects the polishing object based on the comparison result. Grinding the end point.

In one aspect of the polishing end point detecting method of the present invention, the nanocarbon material may include a graphene sheet or a carbon nanotube.

An aspect of the polishing end point detecting device according to the present invention is characterized in that the illuminating unit is configured to emit light on an object to be polished including a mixed film of a nanocarbon material and a light transmitting material, and the light receiving unit receives the polishing from the polishing unit. The light reflected by the object; and the detecting unit detects the polishing end point of the object to be polished based on the light received by the light receiving unit.

In one aspect of the polishing end point detecting device of the present invention, the detecting unit may detect the polishing of the object to be polished by using a spectroscopic interference method for measuring a film thickness of the object to be polished in accordance with a phase difference of light reflected from the object to be polished. end.

In one aspect of the polishing end point detecting device of the present invention, the detecting unit may change the intensity of a composite wave of light reflected from a plurality of reflecting surfaces of the object to be polished. The polishing end of the object to be polished is detected by the polishing rate of the object to be polished.

In one aspect of the polishing end point detecting device of the present invention, the detecting unit may detect a polishing end point of the polishing target based on a spectral change of light reflected from the polishing target.

In one aspect of the polishing end point detecting device of the present invention, the detecting unit may compare a predetermined spectral waveform with a spectral waveform of light reflected from the polishing target, and detect a polishing end point of the polishing target based on the comparison result.

In one aspect of the polishing end point detecting device of the present invention, the nanocarbon material may include a graphene sheet or a carbon nanotube.

When the aspect of the invention of the present invention is adopted, the detection accuracy of the polishing end point can be improved.

100‧‧‧ grinding device

102‧‧‧Substrate

108‧‧‧ polishing pad

110‧‧‧ polishing table

112‧‧‧First electric motor

116‧‧‧Top ring carousel

118‧‧‧Second electric motor

120‧‧‧Slurry pipeline

140‧‧‧Machine Control Department

160‧‧‧Rotary joint connector

171‧‧‧Rotary joint connector

200‧‧‧ Grinding endpoint detection device

210‧‧‧Optical sensor

220‧‧‧ Endpoint detection device body

230‧‧‧ Spectroscope

240‧‧‧Signal Processing Department

250‧‧‧ Grinding End Detection Department

310‧‧‧矽 substrate

320‧‧‧Abrasive film

410‧‧‧Horizontal wiring

420‧‧‧Vertical wiring (Vis)

510‧‧‧Metal film

520‧‧‧ nitride film

530‧‧‧Oxide film

540‧‧‧ basement membrane

550‧‧‧ catalyst layer

560‧‧・nano carbon tube

570‧‧‧ mixed layer

580‧‧‧SOG layer

590‧‧‧Light-transmitting materials

610‧‧‧矽 substrate

620‧‧‧TEOS layer

630‧‧‧ basal layer

640‧‧‧ mixed layer

650‧‧‧SOG layer

660‧‧‧ catalyst layer

710‧‧‧ minimum

720‧‧‧maximum

R1, R2‧‧‧ reflected light

N0‧‧‧ incident light

‧‧‧‧Specified time

The first figure schematically shows the overall configuration of the polishing apparatus and the polishing end point detecting apparatus.

The second A diagram is an explanatory diagram of the measurement principle of the spectral interference method.

The second B diagram is an explanatory diagram of the measurement principle of the spectral interference method.

The third figure is an explanatory diagram of the measurement principle of the spectral interference method.

The fourth A diagram shows a schematic diagram of the processing of the signal processing unit.

The fourth B diagram shows a schematic diagram of the processing of the signal processing unit.

The fourth C diagram shows a schematic diagram of the processing of the signal processing unit.

The fifth figure shows an outline of wiring using MLG and carbon nanotubes.

Fig. 6A is a view schematically showing an example of a circuit using a carbon nanotube.

Fig. 6B is a view schematically showing an example of a circuit using a carbon nanotube.

The sixth C diagram schematically shows an example of a circuit using a carbon nanotube.

The seventh figure is a simplified model diagram of an example of a circuit using a carbon nanotube.

The eighth figure shows a flow chart of the detection process of the polishing end point.

Fig. 9A is a graph showing a change in the spectrum of the reflected light in the seventh polishing when the patterned substrate of the seventh figure is repeatedly polished by the rubbing treatment for 240 seconds.

Fig. IXB is a graph showing a change in the spectrum of the reflected light in the seventh polishing when the patterned substrate of the seventh figure is repeatedly polished by the rubbing treatment for 240 seconds.

The ninth C diagram shows a change pattern of the spectrum of the reflected light in the seventh polishing when the patterned substrate of the seventh figure is repeatedly polished by the rubbing treatment for 240 seconds.

The tenth figure shows an example of the detection of the polishing end point using the spectral index waveform.

Hereinafter, a polishing end point detecting method and a polishing end point detecting device according to an embodiment of the present invention will be described with reference to the drawings.

The first figure schematically shows the overall configuration of the polishing apparatus and the polishing end point detecting apparatus. First, a polishing apparatus will be described.

As shown in the first figure, the polishing apparatus 100 includes a polishing table 110 on which a polishing pad 108 for polishing a substrate 102 such as a semiconductor wafer can be mounted. Further, the polishing apparatus 100 includes a first electric motor 112 that rotationally drives the polishing table 110. Further, the polishing apparatus 100 is provided with an annular turntable 116 that can hold the upper surface of the substrate 102. Further, the polishing apparatus 100 includes a second electric motor 118 that rotationally drives the upper annular turntable 116.

Further, the polishing apparatus 100 includes a slurry line 120 that supplies a polishing liquid containing an abrasive to the polishing pad 108. Further, the polishing apparatus 100 includes a polishing apparatus control unit 140 that outputs various control signals to the polishing apparatus 100.

When the polishing apparatus 100 polishes the substrate 102, the polishing slurry containing the abrasive grains is supplied from the slurry line 120 to the polishing pad 108, and the polishing table 110 is rotationally driven by the first electric motor 112. Then, the polishing apparatus 100 presses the substrate 102 held by the upper ring-shaped turntable 116 against the polishing pad 108 while rotating the upper ring-shaped turntable 116 around the rotating shaft eccentric with the rotating shaft of the polishing table 110. Thereby, the substrate 102 is planarized by polishing the polishing pad 108 holding the polishing slurry.

Next, the polishing end point detecting device will be described. As shown in the first figure, the polishing end point detecting device 200 is provided with an optical sensor 210. Further, the polishing end point detecting device 200 includes an end point detecting device body 220 that is connected to the optical sensor 210 via the rotary joint connectors 160 and 170.

In the present embodiment, a spectroscopic interference method is used in order to measure the film thickness of the substrate 102 and the polishing end point of the substrate 102. Briefly, the measurement principle of the spectroscopic interference method is as follows.

The second A diagram, the second B diagram, and the third diagram are used to illustrate the measurement principle diagram of the spectroscopic interference method. Here, the polishing film 320 to be polished is stacked on the ruthenium substrate 310 as an example. First, as shown in FIG. 2A, when the incident light (n0) is irradiated from the optical sensor 210, the reflected light R1 reflected on the surface of the polished film 320 and the interface through the polished film 320 from the substrate 310 are transmitted. The reflected reflected light R2 is combined. Here, the reflected light R1 is in phase with the reflected light R2.

Further, as shown in FIG. 2B, even when the film thickness of the polishing film 320 is changed, the reflected light R1 reflected by the surface of the polishing film 320 and the reflection reflected from the interface with the ruthenium substrate 310 through the polishing film 320 are reflected. Light R2 is synthesized. Here, the reflected light R1 and the reflected light R2 are in opposite phases. As shown in FIG. 2A and FIG. 2B, when the film thickness of the polishing film 320 is changed by polishing, the reflected light R1 and The reflected light R2 produces a phase deviation.

The third graph shows a graph of the signal intensity variation of the composite wave of the reflected light R1 and the reflected light R2. In the third diagram, the horizontal axis shows the film thickness of the polishing film 320, and the vertical axis shows the signal intensity of the composite wave of the reflected light R1 and the reflected light R2. When the film thickness of the polishing film 320 is changed by polishing, a phase deviation occurs between the reflected light R1 and the reflected light R2 depending on the film thickness. As a result, as shown in the third figure, the reflected intensity of the synthesized wave periodically generates strength. In the third figure, (1) as shown in FIG. 2A, the portion in which the reflected light R1 and the reflected light R2 are in phase, and (2) as shown in the second B, the portion in which the reflected light R1 and the reflected light R2 are in opposite phases.

The polishing end point detecting device 200 measures the film thickness of the polishing film 320 based on the fluctuation of the synthesized wave signal intensity and detects the polishing end point of the polishing film 320. For example, when the relationship between the polishing rate of the polishing film 320 and the fluctuation period of the composite wave signal intensity is known, the polishing end point detecting device 200 can measure the polishing amount of the polishing film 320 and detect the polishing end point of the polishing film 320.

Returning to the first figure, the polishing end point detecting device 200 will be specifically described. The optical sensor 210 includes an irradiation unit that irradiates light onto the substrate 102 and a light receiving unit that receives light reflected from the substrate 102. Here, holes for inserting the optical sensor 210 from the back side of the polishing table 110 are formed in the polishing table 110 and the polishing pad 108. The optical sensor 210 is inserted into a hole formed in the polishing table 110 and the polishing pad 108. The optical sensor 210 illuminates the substrate 102 and receives light reflected from the substrate 102.

The end point detecting device main body 220 includes a spectroscope 230, a signal processing unit 240, and a polishing end point detecting unit 250. The beam splitter 230 takes the reflected light received by the optical sensor 210. The spectroscope 230 splits the reflected light at each wavelength (for example, 400 nm to 800 nm).

The signal processing unit 240 calculates a spectral index (Spectral Index) indicating the intensity of the reflected light at predetermined intervals along the polishing time (for example, the polishing table 110 is rotated once). also, The signal processing unit 240 calculates a spectral index waveform in which the calculated spectral index is marked along the time series.

Here, the processing of the signal processing unit 240 will be described. The fourth A diagram, the fourth B diagram, and the fourth C diagram show schematic diagrams of the processing of the signal processing unit 240. As shown in FIG. 4A, the signal processing unit 240 obtains the signal intensity of the reflected light of each wavelength at predetermined intervals along the polishing time (for example, the polishing table 110 rotates once). Continuing, as shown in FIG. 4B, the signal processing unit 240 calculates the spectral index at each predetermined interval based on the signal intensity of the reflected light of each wavelength at each predetermined interval. Continuing, as shown in the fourth C diagram, the signal processing unit 240 calculates the spectral index waveform by time-series the spectral indices of the specified intervals.

Returning to the description of the first figure, the polishing end point detecting unit 250 detects the polishing end point of the substrate 102 in accordance with the light received by the optical sensor 210 (light receiving unit). Specifically, the polishing end point detecting unit 250 detects the polishing end point of the substrate 102 by using the spectroscopic interference method of measuring the film thickness of the substrate 102 based on the phase difference of the light reflected from the substrate 102. For example, the polishing end point detecting unit 250 can detect the polishing of the object to be polished by changing the intensity of the combined wave of the light reflected from the plurality of reflecting surfaces of the object to be polished and the polishing rate of the object to be polished, as described in the third drawing. end.

Further, the polishing end point detecting unit 250 can detect the polishing end point of the substrate 102 in accordance with the spectral change of the light reflected from the substrate 102. For example, the polishing end point detecting portion 250 compares the predetermined spectral waveform with the spectral waveform of the light reflected from the polishing object. The polishing end point detecting unit 250 can detect the polishing end point of the polishing target object based on the comparison result. This will be described later.

The polishing end point detecting unit 250 is connected to the polishing device control unit 140 that performs various controls on the polishing apparatus 100. After the polishing end point detecting unit 250 detects the polishing end point of the substrate 102, the polishing end point detecting unit 250 outputs a signal indicating the purpose thereof to the polishing apparatus control unit 140. The polishing apparatus control unit 140 receives the signal indicating the polishing end point from the polishing end point detecting unit 250, and then finishes the polishing of the polishing apparatus 100.

Next, the substrate 102 to be polished in the present embodiment will be described. In the present embodiment, the substrate 102 is composed of a mixed film of a nanocarbon material and a light transmitting material.

Here, the nanocarbon material contains a graphene sheet or a carbon nanotube. The graphene sheet is combined with carbon atoms to form a sheet-like substance such as a hexagonal lattice structure of a honeycomb. For example, MLG (Multi-Layer Graphene) of stacked graphene sheets is used for the lateral wiring in a semiconductor circuit.

Further, the carbon nanotube-based graphene sheets form a single layer or a plurality of layers of coaxial tubular materials. The carbon nanotubes are used, for example, as longitudinal wiring (Via) in a semiconductor circuit.

The fifth figure shows an outline of wiring using MLG and carbon nanotubes. As shown in FIG. 5, the wiring in the semiconductor circuit includes a lateral wiring 410 including MLG and a vertical wiring (Vis) 420 formed by including a carbon nanotube.

Next, a specific circuit configuration will be described. The sixth A diagram, the sixth B diagram, and the sixth C diagram schematically show an example of a circuit using a carbon nanotube. The sixth A diagram, the sixth B diagram, and the sixth C diagram schematically show an example of a circuit including a carbon nanotube.

As shown in FIG. A, the circuit is formed by stacking a nitride film 520 on a metal film 510 of copper or tungsten (Cu, W) or the like, and forming an oxide film 530 on the nitride film 520. A hole (Via) for longitudinal wiring is formed in one portion of the oxide film 530. A base film 540 (for example, titanium or titanium nitride (Ti or TiN)) is formed on the oxide film 530 and a portion where the oxide film 530 is formed with a hole. A catalyst layer 550 (for example, nickel or cobalt (Ni or Co) or the like) for growing a carbon nanotube is formed on the base film 540. The carbon nanotubes 560 are grown in the longitudinal direction and formed on the catalyst layer 550. Further, a mixed layer 570 in which the light-transmitting material 590 (SOG (Spin On Glass) or the like) is immersed in the carbon nanotube 560 is formed on the catalyst layer 550. Further, on the mixed layer 570 The light transmissive material 590 is formed as a separate layer of the SOG layer 580. An example of the SOG film-based light-transmitting material 590 of the mixed layer 570 and the SOG layer 580. In the present embodiment, an example in which the SOG film is used for the mixed layer 570 and the SOG layer 580 is shown. However, the present invention is not limited thereto, and any material that can be permeable to light and immersed in the carbon nanotube 560 can be used. In addition, the following is a description of the polishing end point detection of the substrate including the carbon nanotube and the light-transmitting material. However, it is not limited thereto, and is also applicable to the detection of the polishing end point of a substrate including other nano carbon materials (for example, MLG, etc.) and a light-transmitting material.

Here, the polishing is performed in the order of the sixth A diagram, the sixth B diagram, and the sixth C diagram, and the state of the sixth C diagram is used as the polishing end point. The seventh figure is a simplified model diagram of an example of a circuit using a carbon nanotube.

As shown in the seventh figure, the modeled circuit stacks a TEOS (Insulating Film) layer 620 on the germanium substrate 610, and a base layer 630 formed of titanium nitride and titanium is stacked on the TEOS layer 620. Further, a catalyst layer 660 formed of nickel is stacked on the base layer 630. A mixed layer 640 of mixed carbon nanotubes and SOG is stacked on the catalyst layer 660, and an SOG layer 650 is stacked on the mixed layer 640. Further, the catalyst layer 660 is a very thin layer (for example, 2 to 3 nm), and becomes a fine particle at the time of growth of the carbon nanotube. Therefore, the catalyst layer 660 hardly affects the polishing end point detection in the present embodiment.

Next, the polishing end point detection processing in the modeled circuit will be described. The eighth figure shows a flow chart of the detection process of the polishing end point. First, the polishing apparatus control unit 140 starts polishing the substrate 102 (step S101). Continuing, the optical sensor 210 emits light from the irradiation unit (step S102). Continuing, the optical sensor 210 receives the reflected light from the substrate 102 by the light receiving portion (step S103).

Continuing, the signal processing unit 240 signals the reflected light (step S104). Specifically, as shown in FIG. 4A, the signal processing unit 240 obtains the signal intensity of the reflected light of each wavelength at each predetermined interval along the polishing time (for example, the rotation of the polishing table 110 once). Further, as shown in FIG. 4B and FIG. 4C, the signal processing unit 240 reflects the signal intensity of each wavelength according to each wavelength of each specified interval. Degree, the spectral index is calculated at each specified interval. The signal processing unit 240 calculates the spectral index waveform by time-series the spectral indices of the specified intervals.

Continuing, the polishing end point detecting unit 250 determines the polishing end point based on the signal processing result of step S104 (step S105). For example, the polishing end point detecting unit 250 can determine the polishing end point of the substrate 102 in accordance with the spectral change of the reflected light.

Explain this point. The ninth A diagram, the ninth B diagram, and the ninth C diagram show changes in the spectrum of the reflected light in the seventh polishing when the 240 second polishing process is performed once and the modeled substrate of the seventh figure is repeatedly polished. Figure. The horizontal axis of the ninth A, ninth, and ninth C shows the wavelength of light, and the vertical axis shows the signal intensity of the reflected light. Further, in the present embodiment, after the number of polishing times is completed, the film thickness of the TEOS layer 620 at the center of the substrate is confirmed by the film thickness measuring device. As a result, the TEOS layer 620 at the central portion of the substrate was hardly ground at the end of the sixth polishing, and was sharply ground at the end of the seventh polishing. Therefore, in the seventh polishing, the mixed layer 640, the catalyst layer 660, the underlayer 630, and the TEOS layer 620 of the CNT-SOG in the central portion of the substrate are ground.

The waveform of Fig. 9A shows the spectrum from the tenth rotation to the one hundred and ninety rotations in the seventh polishing every 10 rotations. In the waveform of Figure 9A, the waveform of the spectrum is amplituded up and down with a relatively small period.

In addition, the waveform of the ninth B graph shows the spectrum from the second hundred rotations to the twenty-fifth rotations in the seventh polishing every 10 rotations. In the waveform of the ninth diagram, the waveform of the spectrum becomes smaller in the vertical period and the amplitude in the large period.

Furthermore, the waveform of the ninth C-picture shows the spectrum from the 260th rotation to the 712th rotation in the seventh polishing every 10 rotations. In the waveform of the ninth C-picture, the waveform of the spectrum hardly has an amplitude up and down in a small period, and the amplitude is up and down in a large period.

From the change of such a spectral waveform, it is roughly shown that the waveform of FIG. 9A appears when the mixed layer 640 of CNT-SOG is polished. Further, a waveform as shown in FIG. BB appears when the catalyst layer 660 or the base layer 630 is polished. Also, a waveform as shown in FIG. CC appears when the TEOS layer 620 is polished.

Therefore, the polishing end point detecting unit 250 determines that the TEOS layer 620 is started to be polished after detecting the spectral waveform as shown in FIG. When the polishing end point detecting unit 250 determines that the TEOS layer 620 is to be polished, it is determined that the polishing end point (detection polishing end point) is determined by a predetermined predetermined time. For example, the polishing end point detecting unit 250 presets the spectral waveform as shown in FIG. 9C and compares it with the spectral waveform obtained by the signal processing unit 240. When the degree of matching between the predetermined spectral waveform and the spectral waveform obtained by the signal processing unit 240 exceeds the preset threshold value, the polishing end point detecting unit 250 determines that the polishing of the TEOS layer 620 has started.

Further, the polishing end point detecting unit 250 may also detect the polishing end point based on the spectral index waveform. The tenth figure shows an example of the detection of the polishing end point using the spectral index waveform.

In the tenth graph, the horizontal axis shows the grinding time, and the vertical axis shows the reflection intensity. The polishing end point detecting unit 250 presets, for example, the frequency of the spectral index waveform when the TEOS layer 620 is polished. When the spectral index waveform of the set frequency appears, the polishing end point can be determined after detecting the minimum value 710 of the waveform. Further, the polishing end point detecting unit 250 is not limited to the minimum value 710, and may be determined as the polishing end point after detecting the maximum value 720. Further, the polishing end point detecting unit 250 may determine the polishing end point after detecting the minimum value 710 or the maximum value 720 at a plurality of times. Further, the polishing end point detecting unit 250 may determine the polishing end point after a predetermined time (for example, when the specified time α has elapsed after the maximum value 720 has elapsed) after the minimum value 710 or the maximum value 720 is detected.

The polishing end point detecting unit 250 repeats the process of step S105 until the polishing end point is detected (NO in step S106), and after detecting the polishing end point (YES in step S106), the detection is performed. The purpose of the polishing end point is transmitted to the polishing apparatus control unit 140 (step S107).

The polishing apparatus control unit 140 receives the detection of the polishing end point from the polishing end point detecting unit 250, and then finishes polishing of the substrate (step S108).

As described above, according to the present embodiment, the detection accuracy of the polishing end point can be improved. That is, the end point detection of the substrate polishing such as the semiconductor wafer including the wiring of the nanocarbon material has been performed by the visual observation of the worker, and a deviation occurs in the detection of the polishing end point.

In the present embodiment, the object to be polished containing the mixed film of the nanocarbon material and the light-transmitting material is polished, and the object to be polished is irradiated with light, and the polishing end point of the object to be polished is detected based on the light reflected from the object to be polished. Therefore, according to the present embodiment, even if the operator does not rely on the visual observation, the detection accuracy of the polishing end point can be improved. Moreover, since it is not necessary to repeatedly perform polishing and visual determination, it is also possible to reduce man-hours.

In particular, the nanocarbon material is usually black, and is hardly absorbed by light reflection, and it is difficult to measure the film thickness by using a spectroscopic interference method for the nanocarbon material alone. In the present embodiment, a spectroscopic interference method is used for an object to be polished containing a mixed film of a nanocarbon material and a light-transmitting material. Therefore, according to the present embodiment, light can be partially reflected on the surface of the light-transmitting material, and as a result, film thickness measurement by the spectroscopic interference method can be performed.

Further, for the method of detecting the polishing end point, for example, the rotational torque of the polishing table 110 is also used. That is, the rotational torque of the polishing table 110 is related to the current flowing into the first electric motor 112 that rotationally drives the polishing table 110. For example, consider the case of grinding the first and second layers of the abrasive object having a large difference in the polishing rate. At this time, when the polishing target changes from the first layer to the second layer, the current flowing into the first electric motor 112 also largely changes. Therefore, it is possible to detect that the second layer has been started to be ground by detecting the change in the current.

In this regard, the polishing rate of the substrate-based SOG layer 650 to be polished used in the present embodiment is 180 to 200 nm/min, the polishing rate of the CNT-SOG mixed layer 640 is 150 to 180 nm/min, and the polishing rate of the underlying layer 630: 90~110nm/min, polishing rate of TEOS layer 620: 90~110nm/min.

As described above, in the substrate to be polished used in the present embodiment, the difference in the polishing rate of each layer is not large, and therefore the change in the current flowing into the first electric motor 112 is not remarkable. Therefore, it is difficult to apply the polishing end point detecting method using the rotational torque of the polishing table 110 to the substrate to be polished used in the present embodiment.

In addition, the polishing rate of the CNT-SOG mixed layer 640 varies depending on the density of the carbon nanotubes. When the density of the carbon nanotubes is high, the polishing rate is lowered. At this time, since the difference in the polishing rate from the underlying layer becomes large, the electric motor torque may vary during the underlayer polishing, and the torque variation may easily occur due to the following reasons.

In general, since the carbon material has a low coefficient of friction, it is used as a lubricant. Therefore, the carbon residue generated during the polishing remains on the surface of the polishing pad to form a slippery state. Thus, it is possible that the overall torque value becomes small, and the change is not easily seen even when the base layer exposes the abrasive surface.

On the other hand, in the present embodiment, since the detection method of the polishing end point using the spectroscopic interference method is employed, as shown in the ninth figure, the waveform of the spectrum changes significantly as the layer to be polished is switched. As a result, the polishing end point can be more accurately detected by the present embodiment.

S101~S108‧‧‧Steps

Claims (12)

A polishing end point detecting method for polishing an object to be polished and irradiating light onto the object to be polished, wherein the object to be polished comprises a mixed film of a nano-carbon material and a light-transmitting material; and reflecting from the object to be polished Light, detecting the polishing end point of the object to be polished. The method of detecting a polishing end point according to the first aspect of the invention, wherein the step of detecting a polishing end point of the object to be polished is to measure a film thickness of the object to be polished using a phase difference of light reflected from the object to be polished. The interference method is used to detect the polishing end point of the object to be polished. The method for detecting a polishing end point according to the first or second aspect of the patent application, wherein the step of detecting the polishing end point of the object to be polished is based on synthesizing the combined wave intensity of light reflected from a plurality of reflecting surfaces of the object to be polished The polishing end point of the object to be polished is detected by changing the polishing rate of the object to be polished. The polishing end point detecting method according to the first or second aspect of the invention, wherein the step of detecting the polishing end point is to detect a polishing end point of the polishing object based on a spectral change of light reflected from the polishing object. The method for detecting a polishing end point according to claim 4, wherein the step of detecting the polishing end point is to compare a predetermined spectral waveform with a spectral waveform of light reflected from the polishing object, and detect the polishing object according to the comparison result. The grinding end point of the object. The method for detecting a grinding end point according to claim 1 or 2, wherein the nano carbon material comprises a graphene sheet or a carbon nanotube. A polishing end point detecting device comprising: an illuminating unit that emits light on an object to be polished, wherein the object to be polished includes a mixed film of a nanocarbon material and a light transmitting material; and the light receiving unit receives the light from the foregoing The light reflected by the object to be polished; and a detecting unit that detects the polishing end point of the object to be polished based on the light received by the light receiving unit. The polishing end point detecting device according to the seventh aspect of the invention, wherein the detecting unit detects the polishing object by using a spectroscopic interference method for measuring a film thickness of the object to be polished based on a phase difference of light reflected from the object to be polished. The grinding end point. The polishing end point detecting device according to the seventh or eighth aspect of the invention, wherein the detecting unit changes the intensity of the combined wave of the light reflected from the plurality of reflecting surfaces of the object to be polished, and the object to be polished The polishing rate is used to detect the polishing end point of the object to be polished. The polishing end point detecting device according to the seventh or eighth aspect of the invention, wherein the detecting unit detects the polishing end point of the object to be polished based on a spectral change of light reflected from the object to be polished. The polishing end point detecting device according to claim 10, wherein the detecting unit compares a predetermined spectral waveform with a spectral waveform of light reflected from the polishing object, and detects a polishing end point of the polishing object based on the comparison result. . The polishing end point detecting device according to claim 7 or 8, wherein the nano carbon material comprises a graphene sheet or a carbon nanotube.