JP2000077371A - Detecting method, detector and polishing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for easily and highly accurately detecting the film thickness and the process end point in any device pattern at through the process end point and the thickness of a removed film could not be detected in the past with sufficient accuracy with a device pattern present on the wafer surface, when optically detecting the thickness of a thin film to be removed from a semiconductor wafer. SOLUTION: The difference between the maximum/relative maximum reflective rate and the minimum/relative minimum reflective rate of spectral waveforms of a reflected light and a transmitted light obtained by irradiating a probe light on a semiconductor wafer, or the ratio of the minimum/relative minimum value and the maximum/relative maximum value, is used to specify or search the measurement position of a semiconductor wafer surface. An accurate film thickness or process end point can be detected by monitoring at a specific position.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a detection apparatus, and more particularly to a detection method and an inspection apparatus used in an end point detection apparatus for a CMP process for removing an insulating layer or an electrode layer on a semiconductor element surface in a semiconductor device manufacturing process. .

[0002]

2. Description of the Related Art The density of semiconductor devices has continued to increase without showing a limit. As the density has increased, the technology of multilayer wiring and the accompanying formation of interlayer insulating films and electrodes such as plugs and damascenes has been increasing. The importance has increased significantly. Obviously, monitoring the thickness and shape (such as whether or not embedded correctly) of such an interlayer insulating film or metal film is a major issue. Needless to say, the monitoring of the film thickness is also required in processes such as thin film formation and etching, but what has been particularly viewed as a problem recently is the detection of the process end point in the planarization process.

In consideration of the reduction in the depth of focus during exposure accompanying the shortening of the wavelength in lithography, there is a great demand for the accuracy of flattening the interlayer at least in the range of the exposure area. In the so-called inlay (plug, damascene) in which a metal electrode layer is embedded, it is required to remove and flatten an excessive metal layer after lamination. Many methods for locally smoothing an interlayer layer by improving a film forming method or the like have been proposed and executed, but a polishing process called CMP is an effective flattening technique for a larger area. CMP (Chemic
al Mechanical Polishing or Planarization)
It is a promising candidate for global planarization technology, in which physical polishing is used in combination with a chemical action (dissolution with an abrasive solution) to remove the surface irregularities of the wafer. Specifically, using an abrasive called a slurry in which abrasive particles (typically silica, alumina, cerium oxide, etc.) are dispersed in a solvent for the member to be polished such as an acid or an alkali, and using an appropriate polishing cloth. The polishing is advanced by pressurizing the wafer surface and rubbing by relative motion. By making the pressure and the relative movement speed uniform over the entire surface of the wafer, uniform polishing within the surface is possible.

In such a CMP process, the stability and reproducibility of the process are harder to obtain than the conventional film formation and etching. Therefore, it is necessary to constantly detect the film thickness of the interlayer layer or metal layer as quickly as possible so that the process efficiency can be improved. It has also been requested. For these evaluations, a general film thickness measuring device is often used for inspection of the process. A minute blank portion (a place where there is no two-dimensional distribution of film thickness) of the wafer cleaned after the process is selected as a measurement place, and measurement is performed by various methods.

[0005] In the polishing flattening step, as a monitoring method that provides quicker feedback, a fluctuation in friction when polishing proceeds to a layer different from the target polishing layer is detected by a change in motor torque of wafer rotation or pad rotation. There is a way. In addition, a method has been proposed in which an optical path is provided on a polishing pad, or the thickness of a thin film being polished is measured by optical interference using light transmitted through the wafer (infrared light) from the back surface of the wafer. I have.

[0006]

A technique for quickly and simply monitoring the thickness of an interlayer film, a metal layer, or the like in the above-mentioned CMP process or the like, or for accurately monitoring the end point of the process, despite the increasing demand. And there is no definitive method. Although the measurement with the above-mentioned film thickness measuring apparatus can obtain sufficient accuracy and reliable data at present, it has the following problems.

First, the device itself becomes large-scale. Second, the wafer that has been cleaned after the CMP process is transferred to a measurement position (such as holding a stage) that is sufficiently stably placed and measured, so that it takes a long time until a measured value is obtained, and feedback to the process is required. Slows down. Third, a major problem is the position setting of wafer measurement. In a device wafer having a pattern, the film thickness must be measured by searching for a portion having no pattern. Generally, a portion having no pattern is very small in area, and
The position is not constant depending on the device wafer.

If the area of the pattern-free portion is small, the measurement range must be reduced, but this is not easy in terms of equipment. Further, it is not easy to quickly search a small measurement range and measure at high speed. For this purpose, it is necessary to have a complicated mechanism for capturing, recognizing, and processing the pattern image, which requires a large load and a high cost for both hardware (image pickup device, precision alignment mechanism, etc.) and software (image processing software). Because it will be something. Even if it can be realized, the time for image processing, position search and positioning will greatly increase the measurement time.

Although the method of detecting the end point of the CMP process by the motor torque is simple and fast, it is effective only when the start of polishing of a distinct layer is detected at present, and is insufficient in accuracy. It is. An optical method is known as a highly accurate method for detecting a film thickness or a process end point. In this method, a process end point is determined by irradiating a wafer or the like with a laser or the like and tracking a temporal change in monitor light intensity obtained by reflection or the like. According to this method, a certain degree of accuracy can be obtained in the measurement of a blank film having no device pattern. However, when a device pattern (base pattern) exists on the wafer surface, it cannot be detected with sufficient accuracy. This problem was more serious in a logic element or a mixed element of logic and memory than in a memory element such as a D-RAM.

[0010] Furthermore, during polishing, the wafer moves and cannot separate signals at specific locations of the pattern from signals at other locations in the pattern, as well as signals at non-patterned portions. Therefore, the end point of the process could not be detected by in-situ measurement while polishing.
An object of the present invention is to solve the above problems and provide a simple method for detecting a film thickness or a process end point with high detection accuracy, a detection device, and a polishing device with high productivity.

[0011]

[Means for Solving the Problems] The inventor has found that
Ends process with optical measurement when vise pattern exists
The cause that the point cannot be detected with sufficient accuracy was investigated. The result
The result is obtained by irradiating the wafer surface with probe light.
Monitor signal has a pattern interference component overlapping the film thickness interference component.
The size of the pattern interference component is
Will change if the device pattern changes. In other words, many
Pattern interference generation for a variety of device patterns
Since the size of the minute changes, the monitor signal
There is uncertainty depending on the pattern,
You. For example, a memory device such as a D-RAM or a logic
Between devices, logic and memory mixed devices,
In addition, the pattern of the same type
There is uncertainty because the interference components differ greatly.

Also, there is an uncertainty that the size of the pattern interference component differs depending on the location to be measured even for the same type of device with the same degree of integration. This uncertainty is small in uncertainty because the memory element such as a D-RAM can be regarded as a continuation of the periodic structure and the pattern can be regarded as substantially uniform. However, in the case of a logic element or a mixed element of logic and memory, Since the pattern is not uniform and the problem due to the measurement position becomes significant, the uncertainty increases. It has been found that these uncertainties are the major error sources of detection.

As a result of earnest research, the inventor has eliminated these error sources by specifying the location where the device pattern is measured based on appropriate parameters obtained from the monitor signal (signal waveform). . Therefore, in the present invention, first, in the step of removing the thin film on the surface of the substrate, the removing step is performed by a signal waveform of reflected light or transmitted light obtained by irradiating a part or the entire surface of the substrate with probe light. A method for detecting one or both of a film thickness and a process end point in the method, comprising a step of specifying a measurement position on the substrate surface using a parameter obtained from the signal waveform. Detection method (Claim 1) "is provided.

[0014] Secondly, there is provided a "detection method according to claim 1, wherein the parameter is a difference between a maximum local minimum value and a minimum local minimum value of the signal waveform. I do. Thirdly, the present invention provides "the detection method according to claim 1, wherein the parameter is a minimum value of the signal waveform."

Fourthly, there is provided a "detection method according to claim 1 wherein the parameter is a ratio between a minimum minimum value and a maximum maximum value of the signal waveform. I do. Fifth, the present invention provides "the detection method according to claim 1, wherein the parameter is an average value of the signal waveform."

In a sixth aspect, the method further comprises the step of: further comprising the step of calculating a film thickness and determining a process end point using a reference value corresponding to the specified measurement position. And a detection method according to claim (claim 6). Seventhly, the method further comprises the step of, after specifying the measurement position, moving a measurement point to a desired measurement position. Item 7) is provided.

Eighth, the method further comprises the step of: "calculating a film thickness and determining a process end point using a reference value corresponding to a desired measurement position at which the measurement point has been moved." Described method (claim 8). " Also,
Ninth, `` selecting and acquiring a signal from a desired measurement position, further comprising a step of determining a film thickness and a process end point using a reference value corresponding to the selected measurement position, To provide a detection method according to any one of claims 1 to 5 (claim 9).

A tenth aspect of the present invention is that the substrate surface is a semiconductor element surface in a semiconductor device manufacturing process, and the thin film is an insulating layer or an electrode layer. (Claim 10). " Eleventh, there is provided a "detection apparatus characterized by using any one of the detection methods described in claims 1 to 10 (claim 11)".

In a twelfth aspect, the invention provides a detecting device, a polishing pad, and a polishing head for holding a member to be polished, wherein a relative motion is provided between the polishing pad and the member to be polished. Thus, a polishing apparatus (claim 12) for polishing the member to be polished is provided.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below.
However, the present invention is not limited to this example. Figure
FIG. 3 is an overall view for explaining the embodiment of the present invention.
Or show a polishing machine with a device to detect the end of the process
You. 1 is a polishing head, 2 is a wafer as a substrate, and 3 is a polishing head.
Polishing pad, 4 is a polishing plate, 5 is a translucent window, 6 is light irradiation
, 7 is irradiation light and reflected light, 17 is a signal processing unit, 18 is
It is a display unit.

The polishing apparatus operates as follows. The wafer 2 is held by a polishing head 1, the polishing pad 3 is held by a polishing platen 4, and the wafer 2 is pressed against the surface of the polishing pad 3 by pressing 20.
Have been. While the abrasive 105 is supplied between the polishing pad 3 and the wafer 2 from the abrasive supply mechanism 104, the relative movement between the wafer 2 and the polishing pad 3 is caused by the rotational movement 30 of the wafer 2 and the rotational movement 40 of the polishing pad 3. , The wafer 2 is polished. The irradiation light and the reflected light 7 are passed through a light-transmitting window to detect the film thickness or the process end point while performing the polishing, and the reflected light is received by the light irradiation light-receiving unit 6 and then processed by the signal processing unit 17. The film thickness information is monitored.

In the present invention, for the purpose of optical monitoring, as irradiation light (probe light), multi-component wavelength light having a plurality of continuous wavelength components, specifically, white light (or a component obtained by spectrally separating the same) is used. ) Is applied to the surface of the wafer 2 and the signal of the spectral waveform of the reflected light is signal-processed to detect the film thickness or the end point of the process. Of course, a method of irradiating from the back surface of the wafer (in this case, transmitted light may be detected) may be used, but in this case, a multi-component wavelength light source in the infrared region is required.

[0023] The spot diameter of the irradiating light depends on the device pattern.
Larger than the minimum unit of the
I was fired. Here is the measurement position of the device pattern
The principle of specifying the position will be described in detail. Device pattern
Is a two-dimensionally distributed multilayer thin film pattern
And the reflected light is reflected in each of the patterns as schematically shown in FIG.
The turn is a superposition of light waves from each layer of the laminated thin film.
And the spectral waveform can be complex interference effects.
Therefore, even if the thickness of the top layer is the same,
It will be very different. From such a spectral waveform,
Calculating the film thickness value you want to measure directly is generally
Is not easy. However, beforehand,
Calculate the spectral reflectance from the device pattern
Is compared with the measured reflectance value to calculate the film thickness.
Or that the measured reflectance value matches the calculated reflectance value
Can be used as the end point of the process.

When an actual measured value of the spectral reflectance of a desired sample can be obtained from a dummy wafer or the like used in various processes, the actual measured waveform is used as a reference (target value) and an end point is set. Monitoring is more practical and convenient. When measuring a wafer on which a pattern is formed, the pattern is a one-dimensional or two-dimensional periodic pattern, the irradiation area is sufficiently larger than the area for one cycle of the pattern, and the pattern is uniformly formed over the entire surface of the wafer. In the case of distribution (a pattern of a D-RAM or the like corresponds to this), it has been confirmed that a stable and reproducible signal can be obtained regardless of location as average information. In this case, the so-called in-line measurement in which the wafer is measured after the process is also performed in the in-situ measurement performed during the process.
Also in measurement, it is possible to calculate the film thickness or know the end point of the process from the spectral waveform without having to pay attention to the measurement position (irradiation position). However, as described above, in the case of a CPU, an ASIC, or the like having a non-uniform pattern distribution, the spectral waveform greatly varies depending on the irradiation position, and the reproducibility cannot be obtained depending on the irradiation position.

Devices such as CPUs and ASICs can often be divided into several functionally separated blocks, albeit with non-uniform patterns.
In fact, the inventor has confirmed that in various devices, signal reproducibility in each block is good, and that spectral waveforms are significantly different between blocks. It is considered that such signal fluctuation occurs due to the following circumstances. That is, in a certain block, the device wiring pattern therein is usually regular, and even if it is not necessarily regular, the definition (average pitch) of the pattern is almost the same. This is appropriate from the viewpoint of the efficiency of the device manufacturing process.

The inventor has analyzed signal waveforms (spectral reflectance or spectral waveform) from the pattern and has noticed that the shape of these waveforms greatly depends on the definition of the device pattern. Conversely, if the definition is about the same,
That is, they have almost the same spectral waveform. In the measurement by vertical light incidence, the film thickness and the pattern density naturally also affect the waveform. Here, the pattern density is the ratio of the area of the protrusions in the layer to the total area. The projection is generally a dielectric film (transparent film) on the metal layer. However, the film thickness is almost the same on the entire surface of the wafer in the process, and the pattern density is within a certain range (30 to 50%) in a normal device. The inventors have observed that the effect is not so great. As an effect on the entire waveform, the fact that the definition is higher than the pattern density means that in a certain device pattern, a fine portion such as a memory cell portion (FIG. 1A) and a portion having a coarse pattern pitch such as a wiring portion (FIG. 1A). In -b), a clear waveform difference was recognized even though the film thickness and the pattern density were almost the same. It is presumed that the reason why the shape of the waveform largely depends on the definition of the device pattern is due to the difference in the interference phenomenon of the reflected light.
As exemplarily shown in FIG. 6, in the reflected light from the laminated thin film pattern, which is a device pattern, interference between patterns (interference of wavefront division) is added together with an interference phenomenon due to film thickness (interference of amplitude division). Since the interference by the pattern is a phenomenon between the patterns only within the (spatial) coherence length of the irradiation optical system, it does not occur when the pattern width is larger than the coherence length. In the case of a large pattern width, that is, a coarse pattern, the spectral waveform is determined by simply adding the light intensities from the respective portions. This estimation is based on simulation calculation results by modeling the interference of amplitude division and the interference of wavefront division and coherence length,
The validity was confirmed by comparing the above measured data and the like.

In the present invention, it is an object of the present invention to utilize such a phenomenon to know an irradiation position by a spectral waveform obtained from a wafer having a device pattern, and to obtain measurement reproducibility. That is, whether or not the irradiation light is irradiated on the device pattern by the spectral waveform, and if it is irradiated, the irradiation position is determined by which part on the device pattern (for example, A, B, C, D, E in FIG. 2). , F), the irradiation position is specified, and the method of calculating the film thickness (model calculation) is changed according to the irradiation position. The target waveform at the process end point is also selected according to the irradiation position. In this manner, the process can be controlled by detecting the film thickness and the process end point regardless of the position where the irradiation light irradiates during polishing.

In the above method, the position to be irradiated is specified from the spectral waveform, and detection is performed by preparing a plurality of calculation methods and target waveforms corresponding to each position on the device pattern. In the case of a device having a mechanism that can change the irradiation position, it is also possible to perform light irradiation on a desired position by analyzing the acquired spectral waveform in a time series.

The measurement is performed while performing the polishing step.
In the case of in-situ measurement, in this method, the irradiation position cannot be controlled, and data from various positions is continuously obtained. Even in this case, the irradiation position is determined and specified based on the spectral waveform, and the data can be processed according to the irradiation position, thereby enabling the process control. Always in the same position (for example,
Only data from any one of A, B, C, D, E, and F in FIG. 2 is selected and processed, or various data (for example, FIG.
, A, B, C, D, E, and F) are distributed to each position and processed at each position.

Specific parameters that are preferable for judging and specifying the irradiation position from the spectral waveform are specifically described below. 1. 1. Difference between the maximum maximum value and the minimum minimum value 2. Ratio of minimum local maximum to maximum local maximum The value for any parameter obtained by signal processing from the spectral waveform can be obtained by simulation calculation or measurement for different pattern positions using at least one selected from the minimum minimum value or more parameters. The irradiation position is determined and identified by comparing it with a value stored in advance.

Although the present invention has been described with reference to a dielectric film (interlayer insulating film), the present invention is also applicable to determination of a measurement position of a metal film. That is, in general, when the metal laminated on the entire surface is removed by etching or polishing when forming the electrode layer embedding (inlay), a portion with and without a metal layer appears at the end of the process. The spectral waveform of the reflected light is usually smooth in a metal film. When the metal film disappears and a pattern appears, the spectral waveform greatly changes under the influence of the underlying dielectric layer. By observing this variation, it is effective to determine the measurement position with respect to the metal film of each pattern.

If the irradiation position can be determined and specified from the spectral waveform, then appropriate parameters are obtained from the spectral waveform by signal processing and used to monitor the process end point. It is preferable to use one or more selected ones. 1. 1. One or more selected from a local maximum value, a local minimum value, or (local maximum value-local minimum value), or (local minimum value / local maximum value) Maximum maximum value, minimum minimum value, or (maximum minimum value-minimum minimum value), or (maximum minimum value / maximum maximum value)
2. One or more selected from Dispersion 4. 4. Components of the appropriate Fourier transform Cross-correlation function between spectral waveform and spectral waveform obtained by simulation calculation stored in advance The parameter used for detecting the polishing end point may be the same as or different from the parameter used for determining and determining the measurement position.

In this embodiment, the apparatus used in the removing step is the polishing apparatus shown in FIG. 3. However, it goes without saying that the present invention can be used in other removing steps such as ion etching. All of the above judgments are general,
The method can be performed at a much higher speed than the position determination method by performing image processing on an image captured by capturing a pattern, and the mechanism is much simpler.

[0034]

EXAMPLES [Example 1] In fact the imaging device on a 6-inch wafer interlayer insulating film SiO ₂ is polished by polishing device shown in FIG. 3, we tried the polishing endpoint detection. The polished image sensor has a block structure as shown in FIG.
The positions B and C are high-definition portions such as elements and capacitors, and the positions D, E and F are low-definition portions such as wiring. As shown in FIG. 3, the light irradiation was performed by forming a polishing pad 3 (epoxy polishing cloth) on the lower surface and a circular hole of about 2 cmΦ in the polishing platen 4 and providing quartz on the same surface as the polishing pad 3 surface. It is determined that the light transmission window 5 is provided. As shown in FIG. 4, the light irradiating and receiving unit makes a xenon lamp vertically incident on the surface of the wafer 2, passes the reflected light through a pinhole 15 (removing scattered light and diffracted light), and wavelength-resolves the light by a diffraction grating 13. Then, the light is detected by the photodiode type linear sensor (512 elements) 14 so that light of different wavelengths is directed in different directions. Measurement wavelength range is about 40
0 nm to 800 nm, the irradiation spot system is about 2 mmΦ. The output from the sensor is sent to the signal processing unit 17 for processing. The signal processing unit 17 previously stores reference information obtained from a spectral waveform measured for the pattern of the image pickup device, and is used as a reference value for signal processing.

The abrasive (slurry) used was a dispersion of silica particles in an alkaline solvent, and was polished at a polishing pressure of about 100 g / cm ² . The effect on the light quantity (mainly scattering loss) due to the presence of the slurry was 1% or less. First, preliminary measurement was performed on a wafer sample having the same shape as a product wafer (imaging device) using the above apparatus. About 1 on the outermost surface
Polishing the insulating film SiO ₂ formed by CVD of 000 nm,
Polishing was performed to finish polishing at a thickness of about 500 nm, and the obtained spectral waveform was observed. When the respective portions A, B, and C were irradiated, the shape was as shown in FIG.
The signal from each of the parts E and F has a shape as shown in FIG. 5B, and reflects the definition of each position (block). From the similarity of the waveforms, block A, B and C
The portions D, E, and F are separated from the block 2, and the wafer sample is polished from a polishing film thickness of zero to a predetermined polishing film thickness for each predetermined polishing film thickness, and then measured. , The difference between the maximum maximum value and the minimum minimum value is obtained for the block 1 and the block 2.
Although there was a large difference between the values for block 1 and block 2, there was no significant difference for each of the polished film thicknesses. Determined and stored as reference information. In addition to this, the film thickness or polishing end point determination information obtained from the difference between the maximum maximum value and the minimum minimum value for the block 1 is also stored as reference information.

As the product wafer, an image sensor having the same shape as that used in the preliminary measurement was selected, and about 10
The insulating film SiO ₂ formed by CVD with a thickness of 00 nm was polished.
The difference between the maximum maximum value and the minimum minimum value of the spectral waveform during polishing was determined. If the difference was equal to or more than a certain value stored as reference information, block 1 was determined.

[0037] Maximum pole as parameter for polishing end point detection
Using the difference between the maximum and the minimum minimum, the monitor will block
Perform only for 1 but not for block 2
Was. During the course of polishing, the difference between the maximum and the minimum is
This value is compared with the film thickness or polishing end point judgment information.
The end of polishing was determined by comparison, and polishing was terminated.

[0038] Actually several wafers of polished products
Upon observation, the surface was flattened and the target
Polishing is performed with an error of about 3% of the thickness.
It could be confirmed. [Example 2] As parameters for monitoring the polishing end point
Instead of the difference between the maximum maximum and the minimum minimum,
The measurement was performed using the same apparatus and method as in Example 1 except that
Was.

[0039] For this reason, the film thickness or polishing end point judgment information
Refer to the spectral waveform of block 1 for the polishing end point
And stored as reference information. Judgment of block 1 and block 2
Another specification was performed in the same manner as in Example 1. Monitor polishing end point
Is performed only on the block 1 as in the first embodiment,
This was not done for block 2. During the polishing process,
Measured spectral waveform values and polishing stored as reference information
Calculate the cross-correlation coefficient between the end point and the spectral waveform.
The polishing was terminated at the time when the correlation coefficient rapidly increased.

[0040] Actually several wafers of polished products
Upon observation, the surface was flattened and the target
Polishing is performed with an error of about 3% of the thickness.
It could be confirmed. [Embodiment 3] The minimum value of the spectral waveform is used as a parameter for determining the measurement position.
Meter, and block if it falls below a certain value
1, except that the case of more than 1 is determined as block 2.
The measurement was performed by the same device and method as in Example 1.

During the progress of the polishing, the maximum maximum and the minimum minimum
The difference from this value changes, and this value is used to determine the film thickness or polishing end point.
The end of polishing is determined by comparing the
Done. Actual observation of several polished product wafers
Then, the surface is flattened and the target polishing thickness is about 500 nm.
Confirmed that polishing was performed with an error of about 3%
did it. [Embodiment 4] The same mechanism and position detection as in the measurement of Embodiment 1
Knowledge method (judgment based on the difference between the maximum and minimum values)
The metal layer (aluminum layer) by CMP
The process of polishing and plug formation was monitored. Polishing
Initially, the entire surface to be polished is covered with a metal layer.
When observing light, a substantially flat spectral waveform is obtained. Polishing
Progresses and as the insulating layer is exposed,
Maximum and minimum values appear in the spectral waveform. The maximum of this maximum
The difference between the largest one and the smallest one is
C to compare with a fixed value stored as reference information
To block 1 or block 2
Was determined.

The difference between the maximum local minimum value and the minimum local minimum value is used as a parameter for detecting the polishing end point, and the monitoring is performed only for the block 1, and this parameter is stored as the maximum local minimum value and the minimum local minimum value of the stored target waveform. By comparing with the difference from the above, the process end point could be detected efficiently.

[0043]

As described above, according to the present invention, when measuring the film thickness of a device wafer, the measurement position can be easily and quickly specified, so that the reproducibility of the measurement can be realized, and the polishing film thickness and the process end point can be realized. Can be detected with high accuracy and high speed, and process control can be performed quickly and efficiently.

[Brief description of the drawings]

FIG. 1 is a comparison of spectral waveforms for the same device pattern but due to differences in position (block). a is a spectral waveform of a portion having a fine definition, and b is a spectral waveform of a portion having a low definition.

FIG. 2 is a schematic diagram of a device pattern in an embodiment.

FIG. 3 is an overall view for explaining an embodiment and an example of the present invention, and shows a polishing apparatus provided with a device for detecting a film thickness or an end point of a process.

FIG. 4 is a schematic diagram of a measurement optical system in an embodiment.

FIG. 5 shows spectral waveforms at respective positions of the device in the example. 5-a shows the spectral waveform of the group of block 1 and 5-b shows the spectral waveform of the group of block 2.

FIG. 6 is a schematic diagram of superposition of light waves from each part of the laminated thin film pattern.

[Explanation of symbols]

1 Polishing head 2 Wafer 3 Abrasive pad 4 Polishing surface plate 5 Translucent window 6 Light irradiation light receiving part 7 Irradiation light and reflected light 8 Personal computer for detection processing 9 Irradiation light source (xenon lamp) 10 Slit (specify irradiation area) 11 Lens 12 Beam splitter 13 Diffraction grating 14 Linear sensor 15 Pinhole 16 Mirror 17 Signal processing unit 18 Display unit

Claims (12)

[Claims] In the step of removing a thin film from the surface of a substrate, a film thickness or an end of the step in the removing step is obtained by a signal waveform of reflected light or transmitted light obtained by irradiating a part or all of the substrate surface with probe light. A method for detecting one or both of the points, comprising a step of specifying a measurement position on the substrate surface using a parameter obtained from the signal waveform. 2. The method according to claim 1, wherein the parameter is a difference between a maximum value and a minimum value of the signal waveform. 3. The method according to claim 1, wherein the parameter is a minimum value of the signal waveform. 4. The detection method according to claim 1, wherein the parameter is a ratio between a minimum value and a maximum value of the signal waveform. 5. The method according to claim 1, wherein the parameter is an average value of the signal waveform. 6. The detection method according to claim 1, further comprising a step of calculating a film thickness and determining a process end point using a reference value corresponding to the specified measurement position. . 7. The detection method according to claim 1, further comprising, after specifying the measurement position, moving a measurement point to a desired measurement position. 8. The detection method according to claim 7, further comprising a step of calculating a film thickness and determining a process end point using a reference value corresponding to a desired measurement position at which the measurement point movement has been performed. 9. The method according to claim 1, further comprising the step of selecting and acquiring a signal from a desired measurement position, and calculating a film thickness and determining a process end point using a reference value corresponding to the selected measurement position. The detection method according to claim 1. 10. The detection method according to claim 1, wherein said substrate surface is a semiconductor element surface in a semiconductor device manufacturing process, and said thin film is an insulating layer or an electrode layer. . 11. A detection device using any one of the detection methods according to claim 1. 12. A member to be polished comprising a detecting device according to claim 11, a polishing pad, and a polishing head for holding the member to be polished, wherein said member to be polished is provided with relative movement between said polishing pad and said member to be polished. Polishing equipment.