JP2005079289A - End point detection method and film quality evaluation method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely detect the end point of processing such as etching or the like of a film to be treated by using an interference light that is measured after a light is emitted to the film to be treated. <P>SOLUTION: When dry etching of a low selection ratio is applied for a polysilicon film 103 as the film to be treated, a light is emitted to the polysilicon film 103, and an interference light is measured as lights reflecting respectively from a boundary between the polysilicon film 103 and a gate oxide film 102 as its base and from the surface of the polysilicon film 103. The end point of the dry etching of a low selection ratio is detected on a basis of the disturbance of a waveform of the measured interference light. Then, the etching mode is changed from a low selection-ratio mode to a high selection-ratio mode, and a remaining polysilicon film 103A is dry-etched to form a gate electrode 103B. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an end point detection method and film quality evaluation method using interference light measured by irradiating light on a film to be processed.

  As the semiconductor device is miniaturized, the gate oxide film is thinned. As a result, in the dry etching of the polysilicon film that becomes the gate electrode, it is necessary to detect the end point of the etching before the gate oxide film is exposed. ing. For this reason, the end point of etching is detected before the gate oxide film is exposed by an end point detection method using interference light as disclosed in Patent Document 1, for example.

  First, an etching apparatus to which a conventional end point detection method is applied will be described with reference to FIG.

  The etching apparatus shown in FIG. 15 is installed at a predetermined interval above the processing chamber 10, a lower electrode 12 disposed on the bottom surface of the processing chamber 10 and serving as a sample stage on which the semiconductor substrate 11 is installed. The upper top plate 13 is provided. A coil 14 is installed on the upper top plate 13. The processing chamber 10 is provided with a gas supply unit (not shown) and a gas discharge unit 15 to which a vacuum exhaust device (not shown) is connected. A high-frequency power source 16 is connected to the lower electrode 12 and the coil 14 via a matching box (not shown), and power is applied from the high-frequency power source 16 to the lower electrode 12 and the coil 14. Etching is performed.

  As shown in FIG. 15, a window member 17 is attached to the upper top plate 13, and light from the light source 18 is irradiated on the semiconductor substrate 11 above the window member 17 and on the semiconductor substrate 11. A light receiving and emitting device 19 is installed to collect the reflected light reflected at. The light source 18 and the light receiving / emitting device 19 are connected via an optical fiber 20, and the light receiving / emitting device 19 and the spectroscope 21, and the spectroscope 21 and the end point detecting device 22 are connected via the optical fiber 20. Yes. Furthermore, the end point detection device 22 is connected to the control unit 23 of the etching apparatus. When the end point detection signal 24 is transmitted from the end point detection device 22 to the control unit 23, the control unit 23 transmits a signal 25 for stopping the application of power to the high frequency power source 16 in order to end the etching.

  Next, a conventional end point detection method will be described with reference to FIGS. 15 and 16A and 16B.

  As shown in FIGS. 15 and 16A, light from the light source (light source 18) is irradiated perpendicularly to the surface of the Si substrate (semiconductor substrate 11). However, a polysilicon film is formed on the Si substrate via a gate oxide film. A part of the irradiation light from the light source is reflected on the polysilicon film, while the other part of the irradiation light passes through the polysilicon film and is reflected at the interface between the gate oxide film and the polysilicon film. These reflected lights interfere with each other to form interference light, and the interference light is collected by the end point detection device 22 via the window member 17, the device 19, the optical fiber 20, and the spectrometer 21 in the upper top plate 13. Is done. Here, the waveform of the interference light (time change in the intensity of the interference light) changes depending on the remaining film thickness of the polysilicon film. Therefore, by monitoring the waveform of the interference light, the remaining film thickness of the polysilicon film is desired. When the value is reached, that is, the end point of etching can be detected.

  In FIG. 16A, the path of the irradiation light from the light source and the path of the reflected light from the polysilicon film and the like are shown tilted for convenience.

  Next, with reference to FIGS. 16A and 16B, the relationship between the remaining film thickness d of the polysilicon film being etched and the interference light will be described.

  As shown in FIG. 16A, since there is a path difference (2d) between the reflected light from the polysilicon film and the reflected light from the gate oxide film / polysilicon film interface, the light from the light source is When the light is irradiated perpendicularly to the substrate, the path difference 2d becomes the phase difference between the two reflected lights as they are, and interference light is generated. Therefore, as shown in FIG. 16B, when this phase difference is an integral multiple of the wavelength of the reflected light in the polysilicon film, the intensity of the interference light is the weakest. Further, when this phase difference is shifted by a half wavelength from an integral multiple of the wavelength of the reflected light in the polysilicon film, the intensity of the interference light becomes the strongest. That is, as the etching amount increases (etching time increases), the intensity of the interference light changes periodically, and its waveform is basically a sine wave.

  By the way, the relationship between the remaining film thickness d of the polysilicon film and the interference light is expressed by the following equations (1) to (3).

Interference light intensity = A ² + B ² + 2AB × cos (ab) (1)
Phase difference (ab) = 2πn × (2d / λ) (2)
Residual film thickness d = d ₀ −Rt (3)
Here, A and B are the amplitudes of the reflected lights, a and b are the initial phases of the reflected lights, n is an integer, d is the remaining film thickness of the polysilicon film, d ₀ is the initial film thickness of the polysilicon film, R Is the etching rate of the polysilicon film, t is the etching time, and λ is the wavelength of light.

  Hereinafter, a conventional method for manufacturing a semiconductor device, specifically, a conventional method for forming a gate electrode will be described with reference to the process cross-sectional views of FIGS.

  First, as shown in FIG. 17A, a gate oxide film 32 is formed by thermal oxidation or the like on a semiconductor substrate 30 on which an element isolation 31 is formed, and then a film forming method such as a CVD (chemical vapor deposition) method. Then, a polysilicon film 33 is formed, and then a resist pattern 35 having a desired gate pattern is formed by using a photolithography technique.

  Next, as shown in FIG. 17B, dry etching is performed on the polysilicon film 33 using the resist pattern 35 as a mask using a dry etching technique. Here, the dry etching conditions are adjusted so that the selection ratio of the polysilicon film 33 to the gate oxide film 32 (underlayer) is lowered. Thereby, a favorable etching shape is obtained. FIG. 17B shows a state immediately after the etching end point is detected by the conventional end point detection method, and the polysilicon film 33A is a polysilicon film remaining when the end point is detected.

  Next, as shown in FIG. 17C, dry etching is performed on the remaining polysilicon film 33A using the resist pattern 35 as a mask to form a gate electrode 33B. Here, the dry etching conditions are adjusted so that the selection ratio of the polysilicon film 33A to the gate oxide film 32 (underlayer) is increased. Thereby, the gate oxide film 32 functions as an etching stopper. FIG. 17C shows a state immediately after the two-stage etching for the polysilicon film 33 is completed.

As described above, in the dry etching (low selection ratio) of the polysilicon film 33 shown in FIG. 17B, the etching end point is detected by the conventional end point detection method using the above-described interference light. That is, the etching end point is set to be detected in the required remaining film thickness of the polysilicon film 33. The etching end point can be detected at any location of the interference light waveform, and the wavelength of light used for end point detection can be set to an arbitrary value (see equations (1) to (3)).
JP 2001-85388 A

  However, the following problems occur in the formation of the gate electrode using the conventional end point detection method. That is, if the conventional end point detection method is used when the void 34 (see FIG. 17A) is generated in the polysilicon film 33 in the above-described conventional example, the remaining film thickness of the polysilicon film 33 is a predetermined value. When the dry etching (low selection ratio) is finished at the point of time, the underlying gate oxide film 32 is exposed at the location where the void 34 is generated (see FIG. 17B). At this time, since the selection ratio of the polysilicon film 33 to the gate oxide film 32 is low, damage such as a penetration 36 occurs in the gate oxide film 32 (see FIG. 17C).

  In view of the above, an object of the present invention is to reliably detect an end point of processing such as etching on a film to be processed using interference light measured by irradiating the film to be processed with light. .

  In order to achieve the above object, the inventor of the present application has developed a new end point using interference light in place of the conventional end point detection method in which the time point when the film thickness of the film to be processed reaches a desired value is detected as the processing end point. As a result of examining the detection method, the following idea was obtained.

  The void that caused the film to be processed in the gate electrode formation using the conventional endpoint detection method is a hole or void generated in the crystal grain boundary, and is present not only in the polysilicon film but also in all kinds of deposited films. Yes. By the way, as a film forming method, a method is generally known in which a specific gas is allowed to flow, and then a raw material gas for depositing a desired film is allowed to flow. In this case, an initial film having a thickness of about several tens of nm is first formed on the underlayer. In addition, there are many cases where minute voids are present in the initial film, which causes a decrease in film density.

  Interference light generated by irradiating the film to be processed is not affected by the low-density initial film when the film thickness of the deposited film (film to be processed) is large. Change in the intensity of the interference light with respect to the processing time), that is, the waveform of the interference light is a sine wave. On the other hand, when the film thickness of the film to be processed becomes smaller than a certain film thickness, a slight disturbance occurs in the sine wave that is the waveform of the interference light due to the influence of the initial film.

  The inventor of the present application paid attention to this waveform disturbance (hereinafter referred to as noise). That is, for example, in dry etching of a film to be processed, if the time when noise generated in a sine wave that is a waveform of interference light is detected as an etching end point, before reaching the initial film in the film to be processed, in other words, The dry etching can be terminated before reaching the void generation location in the film to be processed. Thereby, damage to the underlayer can be prevented.

  Further, the inventor of the present application quantifies the relationship between the noise and the density of the film to be processed, for example, by using the above-described interference light during the dry etching of the film to be processed in the film thickness direction of the film to be processed. It was found that the density change can be evaluated.

  Furthermore, the present inventor, when the film to be processed is doped with impurities, for example, the etching rate of the film to be processed changes at the impurity doping site, so the sine wave that is the waveform of the interference light is distorted and the frequency is increased. Focused on changing. That is, by quantifying the relationship between the distortion of the sine wave and the impurity concentration, for example, by using the above-described interference light during dry etching of the film to be processed, the concentration change of the impurity in the film thickness direction of the film to be processed can be changed. It was found that it can be evaluated. The inventor of the present application has also found that the same technique can be applied to a case where the film to be processed is composed of multiple elements. That is, by quantifying the relationship between the distortion of the sinusoidal wave that is the waveform of the interference light and the impurity concentration of a certain element, for example, using the above-described interference light during dry etching of the film to be processed, It was found that the change in element concentration in the film thickness direction can be evaluated.

  The present invention has been made on the basis of the above knowledge. Specifically, the end point detection method according to the present invention is an end point detection method used when processing a film to be processed. The step of measuring the interference light formed by the reflected light from each of the interface between the film to be processed and its underlayer and the surface of the film to be processed by irradiating light, and the waveform of the measured interference light And a step of detecting an end point of processing on the film to be processed based on the disturbance.

  According to the end point detection method of the present invention, the processing end point for the film to be processed is detected based on the disturbance of the waveform of the interference light measured by irradiating the film to be processed. For this reason, for example, when dry etching is performed on a film to be processed using a condition in which the selectivity of the film to be processed is low, in other words, before the etching reaches the initial film in the film to be processed, The dry etching can be terminated before the etching reaches the place where the void is generated in the film to be processed. Therefore, since damage to the underlying layer can be reliably prevented, damage to the gate insulating film can be eliminated by using the end point detection method of the present invention in, for example, dry etching of a polysilicon film serving as a gate electrode. .

  In the end point detection method of the present invention, the measured interference light waveform is, for example, a sine wave, and the disturbance of the interference light waveform is, for example, noise generated in the sine wave. In this case, the noise is generated due to, for example, voids existing in the film to be processed.

  The processing method according to the present invention is based on a processing method for processing a film to be processed, and detects the processing end point for the film to be processed using the end point detection method of the present invention.

  That is, according to the processing method of the present invention, when processing a film to be processed, since the end point detection method of the present invention is used, the processing end point of the film to be processed can be detected while reliably protecting the underlayer. it can. In the processing method of the present invention, the processing end point for the film to be processed may be detected during the processing of the film to be processed. Further, in the processing of the film to be processed, for example, plasma etching or chemical mechanical polishing may be used.

  The etching method according to the present invention is premised on a method of etching a film to be processed formed on a base layer. Specifically, a first step of performing etching on the film to be processed and detecting the end point of etching by using the end point detection method of the present invention, and below the film to be processed after the first step A second step of continuously etching the film to be processed by switching to a condition in which the selection ratio to the formation is higher than that of the first step.

  According to the etching method of the present invention, the end point of etching is detected using the end point detection method of the present invention when dry etching is performed on the film to be processed under the condition that the selective ratio of the film to be processed is low. To do. For this reason, before the etching reaches the initial film in the film to be processed, in other words, the dry etching with a low selectivity can be terminated before the etching reaches the void generation site in the film to be processed. Therefore, a good etching shape can be obtained by dry etching with a low selectivity while reliably preventing damage to the underlayer. In addition, after detecting the end point of dry etching with a low selectivity, the remaining portion of the film to be processed including the initial film or void is subjected to high etching with a high selectivity, thus preventing damage to the underlying layer. However, the remaining portion of the film to be processed can be etched.

  A first film quality evaluation method according to the present invention is a film quality evaluation method for evaluating a film quality of a film to be processed, and includes a step of forming a film to be processed on an underlayer, etching the film to be processed Irradiating the film to be treated with light, measuring the interference light formed by the reflected light from the interface between the film to be treated and the underlayer and the surface of the film to be treated, and the measured interference And a step of evaluating a density change in the film thickness direction of the film to be processed based on the disturbance of the light waveform.

  According to the first film quality evaluation method, in the film thickness direction of the film to be processed, based on the disturbance of the waveform of interference light measured by irradiating the film to be processed with light when etching the film to be processed. Evaluate density change. That is, by quantifying the relationship between the disturbance of the waveform of the interference light and the density of the film to be processed, the density change in the film thickness direction of the film to be processed can be performed using the above-described interference light when etching the film to be processed. evaluate. For this reason, compared with the conventional film quality evaluation using refractive index measurement, stress measurement, electrical characteristic measurement, or the like, for example, density measurement in the film thickness direction of a polysilicon film serving as a gate electrode can be performed easily and at low cost. .

  In the first film quality evaluation method, the measured interference light waveform is, for example, a sine wave, and the disturbance of the interference light waveform is, for example, noise generated in the sine wave. In this case, the noise is generated due to, for example, voids existing in the film to be processed.

  A second film quality evaluation method according to the present invention is a film quality evaluation method for evaluating the film quality of a film to be processed into which an impurity has been introduced. The film quality evaluation method includes: a step of forming a film to be processed on an underlayer; Etching, and irradiating light to the film to be processed to measure interference light formed by reflected light from the interface between the film to be processed and the underlayer and the surface of the film to be processed; And a step of evaluating a change in impurity concentration in the film thickness direction of the film to be processed based on the measured distortion of the waveform of the interference light.

  According to the second film quality evaluation method, in the film thickness direction of the film to be processed based on the waveform distortion of the interference light measured by irradiating the film to be processed with light when etching the film to be processed. The change in impurity concentration is evaluated. That is, by quantifying the relationship between the distortion of the interference light waveform and the impurity concentration, the above-described interference light is used to evaluate the change in impurity concentration in the film thickness direction of the film to be processed during etching of the film to be processed. To do. For this reason, compared with the conventional film quality evaluation using CIMS or the like, it is possible to easily and inexpensively measure the impurity concentration (for example, phosphorus concentration) in the film thickness direction of the polysilicon film serving as the gate electrode.

  In the second film quality evaluation method, the waveform of the measured interference light is, for example, a sine wave, and the distortion of the waveform of the interference light is, for example, a shift generated in the sine wave. In this case, the deviation occurs due to, for example, impurities present in the film to be processed.

  A third film quality evaluation method according to the present invention is a film quality evaluation method for evaluating the film quality of a film to be processed comprising a plurality of elements including at least one element, the method comprising: forming a film to be processed on an underlayer; In addition to etching the film to be processed and irradiating the film to be processed with light, interference formed by reflected light from each of the interface between the film to be processed and the underlayer and the surface of the film to be processed A step of measuring light, and a step of evaluating the concentration change of one element in the film thickness direction of the film to be processed based on the measured distortion of the waveform of the interference light.

  According to the third film quality evaluation method, in the film thickness direction of the film to be processed based on the distortion of the waveform of interference light measured by irradiating the film to be processed with light when etching the film to be processed. Evaluate the concentration change of one element. That is, by quantifying the relationship between the distortion of the waveform of interference light and the concentration of one element, one element in the film thickness direction of the film to be processed can be obtained by using the above-mentioned interference light during etching of the film to be processed. Evaluate changes in concentration. For this reason, compared with the film quality evaluation using the conventional SIMS analysis etc., the germanium density | concentration measurement in the film thickness direction of a silicon germanium film | membrane can be performed easily and at low cost, for example.

  In the third film quality evaluation method, the measured interference light waveform is, for example, a sine wave, and the distortion of the interference light waveform is a shift generated in the sine wave. In this case, the deviation occurs due to, for example, the concentration of one element in the film to be processed.

  According to the present invention, the processing end point for the film to be processed is detected by using the disturbance of the waveform of the interference light measured by irradiating the film to be processed with light. For this reason, even when voids are generated in the film to be processed, it is compared with the conventional end point detection method, that is, the method of detecting when the film thickness of the film to be processed reaches a desired value as the processing end point. Thus, the end point of the processing can be detected while reliably protecting the underlayer.

  In addition, according to the present invention, when the film to be processed is etched, the above-described interference light is used to perform film quality evaluation such as density change, impurity concentration change or element concentration change in the film thickness direction. Therefore, various film quality evaluations can be performed easily and at low cost.

(First embodiment)
Hereinafter, a method for manufacturing an electronic device according to the first embodiment, specifically a method for forming a gate electrode, using the end point detection method of the present invention will be described with reference to the drawings.

  FIG. 1A to FIG. 1C are cross-sectional views showing respective steps of the electronic device manufacturing method according to the first embodiment.

  First, as shown in FIG. 1A, a gate oxide film 102 is formed on a semiconductor substrate 100 on which an element isolation 101 has been formed using a film forming method such as thermal oxidation, and then the gate oxide film 102 is formed. On top of this, a polysilicon film 103 is formed using a film forming method such as a CVD method. At this time, a void 104 is formed in the polysilicon film 103, particularly in the initial film which is a portion immediately above the gate oxide film 102. Thereafter, a resist pattern 105 having a desired gate pattern is formed on the polysilicon film 103 by using a photolithography technique.

Next, as shown in FIG. 1B, dry etching is performed on the polysilicon film 103 using the resist pattern 105 as a mask, using a dry etching technique. Specifically, for example, using an inductively coupled plasma (ICP) type etching apparatus, the applied power for generating plasma is 350 W, the sample stage applied power is 100 W, the pressure is 0.4 Pa, the Cl ₂ flow rate is 20 ml / min, Dry etching is performed using conditions such as an HBr flow rate of 25 ml / min, a CF ₄ flow rate of 25 ml / min, and an O ₂ flow rate of 3 ml / min (conditions in which the selectivity of the polysilicon film 103 to the gate oxide film 102 is low). .

  In the present embodiment, in dry etching with a low selection ratio with respect to the polysilicon film 103, the polysilicon film 103 is irradiated with light, whereby the interface between the polysilicon film 103 and the gate oxide film 102, and the surface of the polysilicon film 103. The intensity of interference light (for example, wavelength 600 nm) formed by the reflected light from each of the above is measured. FIG. 2 shows the change of the measured value with respect to the etching time (that is, the remaining film thickness of the polysilicon film 103 to be processed), that is, the waveform of interference light. Here, the waveform shown in FIG. 2 is basically a sine wave, but with the progress of etching, in other words, as the remaining film thickness of the polysilicon film 103 decreases, the waveform is affected by the void 104 in the initial film. Is disturbed and noise appears. In the present embodiment, the etching end point is detected when the noise intensity change reaches 5% of the intensity predicted as a sine wave.

  FIG. 1B shows a state immediately after the etching end point is detected by the end point detection method of the present invention, and the polysilicon film 103A is a polysilicon film remaining when the end point is detected.

Next, as shown in FIG. 1C, the etching mode is switched from the low selection ratio mode to the high selection ratio mode, and the resist pattern 105 is used as a mask to dry the slightly remaining polysilicon film 103A. Etching is performed to form the gate electrode 103B. Here, the polysilicon film 103A other than the gate electrode formation region is removed. Specifically, for example, an inductively coupled plasma etching apparatus is used, the applied power for generating plasma is 250 W, the applied power of the sample stage is 50 W, the pressure is 10 Pa, the HBr flow rate is 50 ml / min, and the O ₂ flow rate is 1 ml / Dry etching is performed using conditions such as min and He flow rates of 50 ml / min (conditions in which the selectivity of the polysilicon film 103 to the gate oxide film 102 is increased). At this time, the gate oxide film 102 which is the base layer is exposed at the portion where the void 104 is generated in the polysilicon film 103 as compared with the portion where the void 104 is not present. However, since the etching rate of the gate oxide film 102 is extremely low, the gate electrode 103B can be formed with almost no damage to the gate oxide film 102.

  As described above, according to the first embodiment, the low-selection for the polysilicon film 103 is based on the disturbance of the interference light waveform measured by irradiating the polysilicon film 103, which is the film to be processed, with light. The end point of the ratio dry etching is detected. Specifically, the etching end point is detected when the intensity change of the noise generated in the sine wave that is the waveform of the interference light becomes 5%. For this reason, before the etching reaches the initial film in the polysilicon film 103, in other words, before the etching reaches the generation point of the void 104 in the polysilicon film 103, the dry etching with a low selectivity is terminated. Can do. Therefore, a good etching shape can be obtained by dry etching with a low selection ratio while reliably preventing damage to the gate oxide film 102 which is the base layer. Further, after the end point of the dry etching with a low selectivity is detected, the remaining polysilicon film 103A including the initial film or the void is subjected to the high etching with the high selectivity so that the gate oxide film 102 is reliably prevented from being damaged. However, the remaining polysilicon film 103A can be etched.

  In the first embodiment, the wavelength of the interference light used for detecting the etching end point is not particularly limited, and can be set to an arbitrary value.

  In the first embodiment, the etching end point is detected when the change in the intensity of the noise generated in the sine wave that is the waveform of the interference light reaches 5%. However, the present invention is not limited to this. The end point of etching may be detected when a change in the intensity of noise reaches an arbitrary value in accordance with the density of the voids 104 existing in FIG.

  Further, in the first embodiment, the dry etching of the polysilicon film in the gate electrode forming step is targeted. However, the present invention is not limited to this, and the same effect can be obtained for all dry etching that must protect the underlying layer of the film to be processed. Can be expected. Further, the present invention is not limited to dry etching, and the same effect can be obtained when other processing such as chemical mechanical polishing is performed on the film to be processed.

(Second Embodiment)
Hereinafter, a film quality evaluation method according to a second embodiment of the present invention will be described with reference to the drawings.

  FIGS. 3A and 3B are cross-sectional views showing respective steps of the film quality evaluation method according to the second embodiment.

  First, as shown in FIG. 3A, after a silicon oxide film 201 is formed on a semiconductor substrate 200 by using a film forming method such as thermal oxidation, for example, a CVD method or the like is formed on the silicon oxide film 201. The polysilicon film 202 is formed using the film forming method. At this time, a void 203 is formed in the polysilicon film 202, particularly in the initial film which is a portion immediately above the silicon oxide film 201.

Next, as shown in FIG. 3B, dry etching is performed on the polysilicon film 202 using a dry etching technique. Specifically, for example, an inductively coupled plasma etching apparatus is used, the applied power for generating plasma is 350 W, the applied power of the sample stage is 100 W, the pressure is 0.4 Pa, the Cl ₂ flow rate is 20 ml / min, and the HBr flow rate is Dry etching is performed using conditions such as 25 ml / min, CF ₄ flow rate of 25 ml / min, and O ₂ flow rate of 3 ml / min.

  In the present embodiment, in the dry etching for the polysilicon film 202, the polysilicon film 202 is irradiated with light so that the interface between the polysilicon film 202 and the silicon oxide film 201 and the surface of the polysilicon film 202 are respectively irradiated. The intensity of interference light (for example, wavelength 600 nm) formed by the reflected light is measured. FIG. 4A shows the change of the measured value with respect to the etching time (that is, the remaining film thickness of the polysilicon film 202 to be processed), that is, the waveform of interference light. Here, the waveform shown in FIG. 4A is basically a sine wave, but as the etching progresses, in other words, as the remaining film thickness of the polysilicon film 202 decreases, the crystallinity of the polysilicon film 202 is shown. The waveform is disturbed due to the influence of the variation (specifically, the void 203 in the initial film), and noise appears.

  In the present embodiment, by quantifying the relationship between the disturbance of the interference light waveform, that is, the sine wave noise and the density of the polysilicon film in advance, the measurement result shown in FIG. The density change in the film thickness direction of the polysilicon film 202 that is the film to be processed can be evaluated. FIG. 4B shows the evaluation result.

  As described above, according to the second embodiment, the waveform of the interference light measured by irradiating the polysilicon film 202 with light when the polysilicon film 202 that is the film to be processed is etched. Based on this disturbance, the density change in the thickness direction of the polysilicon film 202 is evaluated. That is, by quantifying the relationship between the disturbance of the interference light waveform and the density of the polysilicon film, the density change in the film thickness direction of the polysilicon film can be achieved by using the above-mentioned interference light during the etching of the polysilicon film. evaluate. On the other hand, according to the conventional film quality evaluation method using refractive index measurement, stress measurement, electrical property measurement, etc., the change in the film thickness direction of each measured value is very small. Assessment of changes is very difficult. That is, according to the present embodiment, compared with the conventional film quality evaluation method, for example, density measurement in the film thickness direction of a polysilicon film serving as a gate electrode can be performed easily and at low cost.

  In the second embodiment, the wavelength of interference light used for film quality evaluation is not particularly limited, and can be set to an arbitrary value.

  In the second embodiment, the film quality evaluation of the polysilicon film is targeted. However, the present invention is not limited to this, and the same effect can be expected when film quality evaluation of various types of films is targeted. The same effect can be obtained when the film quality is evaluated using interference light while performing chemical mechanical polishing on the film to be processed instead of dry etching.

(Modification of the second embodiment)
Hereinafter, a film quality evaluation method according to a modification of the second embodiment of the present invention will be described with reference to the drawings.

  The difference between this modification and the second embodiment is as follows. That is, in the second embodiment, when etching a film to be processed after film formation, the film quality of the film to be processed is evaluated using interference light generated by irradiating the film with light. It was. On the other hand, in this modification, when the film to be processed is formed, the film quality of the film to be processed is evaluated using interference light generated by irradiating the film with light.

  FIGS. 5A and 5B are cross-sectional views showing respective steps of a film quality evaluation method according to a modification of the second embodiment.

  First, as shown in FIG. 5A, a silicon oxide film 201 is formed on a semiconductor substrate 200 by using a film forming method such as thermal oxidation.

  Next, as shown in FIG. 5B, a polysilicon film 202 is formed on the silicon oxide film 201 by using a film forming method such as a CVD method. At this time, a void 203 is formed in the polysilicon film 202, particularly in the initial film which is a portion immediately above the silicon oxide film 201.

  In this modification, by irradiating the polysilicon film 202 with light while forming the polysilicon film 202, the interface between the polysilicon film 202 and the silicon oxide film 201 and the surface of the polysilicon film 202 are each applied. The intensity of interference light (for example, wavelength 600 nm) formed by the reflected light is measured. FIG. 6A shows the change of the measured value with respect to the deposition time (that is, the deposited film thickness of the polysilicon film 202 to be processed), that is, the waveform of interference light. Here, the waveform shown in FIG. 6A is basically a sine wave, but at the initial stage of deposition, in other words, when the initial film is formed, the crystallinity variation (specifically, the initial stage) of the polysilicon film 202 is changed. The waveform is disturbed by the influence of voids 203) in the film, and noise appears.

  In this modification, the relationship between the disturbance of the interference light waveform, that is, the sine wave noise, and the density of the polysilicon film is quantified in advance, and the measurement result shown in FIG. It is possible to evaluate the density change in the film thickness direction of the polysilicon film 202 which is a treatment film. FIG. 6B shows the evaluation result.

  As described above, according to the modification of the second embodiment, the waveform of the interference light measured by irradiating the polysilicon film 202 with light when depositing the polysilicon film 202 to be processed is disturbed. Based on the above, the density change in the thickness direction of the polysilicon film 202 is evaluated. That is, by quantifying the relationship between the disturbance of the interference light waveform and the density of the polysilicon film, the density change in the film thickness direction of the polysilicon film can be determined using the above-described interference light during the deposition of the polysilicon film. evaluate. On the other hand, according to the conventional film quality evaluation method using refractive index measurement, stress measurement, electrical property measurement, etc., the change in the film thickness direction of each measured value is very small. Assessment of changes is very difficult. That is, according to this modification, it is possible to easily and inexpensively measure the density in the film thickness direction of a polysilicon film that becomes a gate electrode, for example, as compared with the conventional film quality evaluation method.

  In the modification of the second embodiment, the wavelength of the interference light used for the film quality evaluation is not particularly limited and can be set to an arbitrary value.

  In the modification of the second embodiment, the film quality evaluation of the polysilicon film is targeted. However, the present invention is not limited to this, and the same effect can be expected when the film quality evaluation of various types of films is targeted. .

(Third embodiment)
Hereinafter, a film quality evaluation method according to a third embodiment of the present invention will be described with reference to the drawings.

  FIGS. 7A and 7B are cross-sectional views showing respective steps of the film quality evaluation method according to the third embodiment.

  First, as shown in FIG. 7A, after a silicon oxide film 301 is formed on a semiconductor substrate 300 by using a film forming method such as thermal oxidation, for example, a CVD method or the like is formed on the silicon oxide film 301. The polysilicon film 302 is formed using the film forming method. Thereafter, for example, phosphorus 303 is doped into the polysilicon film 302 using, for example, ion implantation.

Next, as shown in FIG. 7B, dry etching is performed on the polysilicon film 302 by using a dry etching technique. Specifically, for example, an inductively coupled plasma etching apparatus is used, the applied power for generating plasma is 200 W, the applied power of the sample stage is 50 W, the pressure is 1.5 Pa, the Cl ₂ flow rate is 20 ml / min, and the HBr flow rate is Dry etching is performed using conditions such as 180 ml / min and O ₂ flow rate of 1 ml / min.

  In the present embodiment, in the dry etching for the polysilicon film 302, the polysilicon film 302 is irradiated with light so that the interface between the polysilicon film 302 and the silicon oxide film 301 and the surface of the polysilicon film 302 are respectively removed. The intensity of interference light (for example, wavelength 600 nm) formed by the reflected light is measured. FIG. 8A shows the change of the measured value with respect to the etching time (that is, the remaining film thickness of the polysilicon film 302 to be processed), that is, the waveform of interference light. Here, when phosphorus is not injected into the polysilicon film 302, the waveform of the interference light is basically a sine wave, but in practice, due to the influence of the phosphorus 303 injected into the polysilicon film 302, The measured interference light waveform deviates from the sine wave. Specifically, as shown in FIG. 8A, the interference light waveform of the phosphorus-doped polysilicon film 302 (solid line in FIG. 8A) is the interference light waveform of the non-doped polysilicon film (FIG. It becomes a distorted waveform shifted from the middle of the broken line a). This occurs for the following reasons. That is, as the concentration of phosphorus in the polysilicon film increases, an etchant having a positive charge is likely to be drawn into the polysilicon film having a negative charge by phosphorus, so that the etching rate of the phosphorus-doped polysilicon film increases. Therefore, the frequency of the interference light waveform of the phosphorus-doped polysilicon film is higher than the frequency of the interference light waveform of the non-doped polysilicon film.

  In the present embodiment, the relationship between the waveform distortion of the interference light, that is, the deviation generated in the sine wave and the phosphorus concentration is quantified in advance, and the measurement result shown in FIG. Changes in the concentration of phosphorus 303 in the film thickness direction of the polysilicon film 302 that is a treatment film can be evaluated. FIG. 8B shows the evaluation result.

  As described above, according to the third embodiment, the waveform of the interference light measured by irradiating the polysilicon film 302 with light when the polysilicon film 302 that is the film to be processed is etched. Based on this distortion, the change in impurity concentration in the thickness direction of the polysilicon film 302 is evaluated. That is, by quantifying the relationship between the waveform distortion of the interference light and the impurity concentration, the change in the impurity concentration in the thickness direction of the polysilicon film is evaluated by using the above-described interference light during the etching of the polysilicon film. To do. On the other hand, according to the conventional film quality evaluation method using CIMS (chemical ionization mass spectrometry) or the like, there is a problem that it is expensive and requires a lot of time for analysis. That is, according to the present embodiment, the impurity concentration (for example, phosphorus concentration) measurement in the film thickness direction of the polysilicon film that becomes the gate electrode, for example, can be performed easily and at a lower cost than the conventional film quality evaluation method.

  In the third embodiment, phosphorus 303 is implanted into the polysilicon film 302 after deposition of the polysilicon film 302 that is a film to be processed. Instead, the polysilicon film 302 is deposited while depositing the polysilicon film 302. Alternatively, phosphorus 303 may be doped. Further, the impurity implanted into the polysilicon film 302 is not particularly limited. Specifically, p-type boron may be implanted instead of the n-type phosphorus 303. In this case, as the boron concentration in the polysilicon film increases, the etchant having a positive charge is less likely to be drawn into the polysilicon film having a positive charge by the boron, so that the etching rate of the boron-doped polysilicon film is reduced. Therefore, the frequency of the interference light waveform of the boron-doped polysilicon film is lower than the frequency of the interference light waveform of the non-doped polysilicon film.

  In the third embodiment, the wavelength of interference light used for film quality evaluation is not particularly limited, and can be set to an arbitrary value.

  In the third embodiment, the film quality evaluation of the polysilicon film is targeted. However, the present invention is not limited to this, and the same effect can be expected when film quality evaluation of various types of films is targeted. The same effect can be obtained when the film quality is evaluated using interference light while performing chemical mechanical polishing on the film to be processed instead of dry etching.

(Modification of the third embodiment)
Hereinafter, a film quality evaluation method according to a modification of the third embodiment of the present invention will be described with reference to the drawings.

  The point that this modification is different from the third embodiment is as follows. That is, in the third embodiment, when etching a film to be processed after film formation, the film quality of the film to be processed is evaluated using interference light generated by irradiating the film to be processed with light. It was. On the other hand, in this modification, when the film to be processed is formed, the film quality of the film to be processed is evaluated using interference light generated by irradiating the film with light.

  FIGS. 9A and 9B are cross-sectional views showing respective steps of a film quality evaluation method according to a modification of the third embodiment.

  First, as shown in FIG. 9A, a silicon oxide film 301 is formed on a semiconductor substrate 300 by using a film forming method such as thermal oxidation.

  Next, as shown in FIG. 9B, a polysilicon film 302 is formed on the silicon oxide film 301 by using a film forming method such as a CVD method.

  At this time, for example, phosphorus 303 is doped in the polysilicon film 302 while forming the polysilicon film 302.

  Furthermore, in this modification, by irradiating the polysilicon film 302 with light while forming the polysilicon film 302, the interface between the polysilicon film 302 and the silicon oxide film 301 and the surface of the polysilicon film 302 are exposed. The intensity of interference light (for example, wavelength 600 nm) formed by the reflected light from each is measured. FIG. 10A shows the change of the measured value with respect to the deposition time (that is, the deposited film thickness of the polysilicon film 302 as the film to be processed), that is, the waveform of interference light. Here, when phosphorus is not injected into the polysilicon film 302, the waveform of the interference light is basically a sine wave, but in practice, due to the influence of the phosphorus 303 injected into the polysilicon film 302, The measured interference light waveform deviates from the sine wave. Specifically, as shown in FIG. 10A, the interference light waveform of the phosphorus-doped polysilicon film 302 (solid line in FIG. 10A) is the interference light waveform of the non-doped polysilicon film (FIG. 10A). It becomes a distorted waveform shifted from the middle of the broken line a).

  In this modification, the relationship between the distortion of the waveform of the interference light, that is, the deviation generated in the sine wave and the phosphorus concentration is quantified in advance, and the measurement result shown in FIG. Changes in the concentration of phosphorus 303 in the film thickness direction of the polysilicon film 302 that is a treatment film can be evaluated. FIG. 10B shows the evaluation result.

  As described above, according to the modification of the third embodiment, the waveform distortion of the interference light measured by irradiating the polysilicon film 302 with light when depositing the polysilicon film 302 as the film to be processed. Based on the above, the change in impurity concentration in the thickness direction of the polysilicon film 302 is evaluated. That is, by quantifying the relationship between the waveform distortion of the interference light and the impurity concentration, the change in the impurity concentration in the thickness direction of the polysilicon film is evaluated by using the above-described interference light during the etching of the polysilicon film. To do. On the other hand, according to the conventional film quality evaluation method using CIMS or the like, there is a problem that it is expensive and requires a lot of time for analysis. That is, according to this modification, it is possible to easily and inexpensively measure the impurity concentration (for example, phosphorus concentration) in the film thickness direction of the polysilicon film serving as the gate electrode, for example, as compared with the conventional film quality evaluation method.

  In the modification of the third embodiment, the impurity implanted into the polysilicon film 302 is not particularly limited. Specifically, p-type boron may be implanted instead of the n-type phosphorus 303.

  In the modification of the third embodiment, the wavelength of the interference light used for the film quality evaluation is not particularly limited and can be set to any value.

  In the modification of the third embodiment, the film quality evaluation of the polysilicon film is targeted. However, the present invention is not limited to this, and the same effect can be expected when the film quality evaluation of various types of films is targeted. .

(Fourth embodiment)
Hereinafter, a film quality evaluation method according to a fourth embodiment of the present invention will be described with reference to the drawings.

  FIGS. 11A and 11B are cross-sectional views showing respective steps of the film quality evaluation method according to the fourth embodiment.

  First, as shown in FIG. 11A, a silicon oxide film 401 is formed on a semiconductor substrate 400 by using a film forming method such as thermal oxidation, and then, for example, a CVD method or the like is formed on the silicon oxide film 401. The silicon germanium film 402 is formed using the film forming method.

Next, as shown in FIG. 11B, dry etching is performed on the silicon germanium film 402 using a dry etching technique. Specifically, for example, an inductively coupled plasma etching apparatus is used, the applied power for generating plasma is 200 W, the applied power of the sample stage is 50 W, the pressure is 1.5 Pa, the Cl ₂ flow rate is 20 ml / min, and the HBr flow rate is Dry etching is performed using conditions such as 180 ml / min and O ₂ flow rate of 1 ml / min.

  In the present embodiment, in the dry etching for the silicon germanium film 402, the silicon germanium film 402 is irradiated with light, so that the interface between the silicon germanium film 402 and the silicon oxide film 401 and the surface of the silicon germanium film 402 are respectively emitted. The intensity of interference light (for example, wavelength 600 nm) formed by the reflected light is measured. FIG. 12A shows the change of the measured value with respect to the etching time (that is, the remaining film thickness of the silicon germanium film 402 as the film to be processed), that is, the waveform of interference light. Here, the waveform of the interference light is basically a sine wave, but the waveform of the interference light is distorted by the germanium concentration in the silicon germanium film. Specifically, as shown in FIG. 12A, the interference light waveform of the silicon germanium film 402 to be evaluated (solid line in FIG. 12A) is the interference light waveform of the silicon germanium film having a known germanium concentration ( It becomes a distorted waveform shifted from the middle of the broken line in FIG. This occurs for the following reasons. That is, since the etching rate of the silicon germanium film changes depending on the germanium concentration, the frequency of the interference light waveform of the silicon germanium film 402 to be evaluated is equal to the frequency of the interference light waveform of the silicon germanium film having a known germanium concentration. Compared to change.

  In the present embodiment, the relationship between the distortion of the waveform of the interference light, that is, the deviation generated in the sine wave and the germanium concentration is quantified in advance, and the measurement result shown in FIG. A change in germanium concentration in the film thickness direction of the silicon germanium film 402 as a treatment film can be evaluated. FIG. 12B shows the evaluation result.

  As described above, according to the fourth embodiment, the waveform of the interference light measured by irradiating the silicon germanium film 402 with light when the silicon germanium film 402 as the film to be processed is etched. Based on the distortion, the change in the germanium concentration in the film thickness direction of the silicon germanium film 402 is evaluated. That is, by quantifying the relationship between the distortion of the waveform of the interference light and the germanium concentration, the change in germanium concentration in the film thickness direction of the silicon germanium film is evaluated using the above-described interference light during the etching of the silicon germanium film. To do. On the other hand, according to the conventional film quality evaluation method using SIMS (secondary ion mass spectrometry) or the like, there is a problem that the cost is high and the analysis requires a lot of time. That is, according to this embodiment, the germanium concentration measurement in the film thickness direction of the silicon germanium film can be performed easily and at a lower cost than the conventional film quality evaluation method.

  In the fourth embodiment, the germanium concentration in the silicon germanium film 402 is set as the evaluation target. However, it goes without saying that the silicon concentration can be set as the evaluation target instead.

  In the fourth embodiment, the wavelength of interference light used for film quality evaluation is not particularly limited, and can be set to any value.

  In the fourth embodiment, the film quality evaluation of the silicon germanium film is targeted. However, the present invention is not limited to this, and the film quality evaluation of other types of films made of a plurality of elements (specifically, measurement of element concentration) is performed. The same effect can be expected when the target is used. The same effect can be obtained when the film quality is evaluated using interference light while performing chemical mechanical polishing on the film to be processed instead of dry etching.

(Modification of the fourth embodiment)
Hereinafter, a film quality evaluation method according to a modification of the fourth embodiment of the present invention will be described with reference to the drawings. Note that this modification is different from the fourth embodiment as follows. That is, in the fourth embodiment, when etching a film to be processed after film formation, the film quality of the film to be processed is evaluated using interference light generated by irradiating the film with light. It was. On the other hand, in this modification, when the film to be processed is formed, the film quality of the film to be processed is evaluated using interference light generated by irradiating the film with light.

  FIGS. 13A and 13B are cross-sectional views showing respective steps of a film quality evaluation method according to a modification of the fourth embodiment.

  First, as shown in FIG. 13A, a silicon oxide film 401 is formed on a semiconductor substrate 400 by using a film forming method such as thermal oxidation.

  Next, as shown in FIG. 13B, a silicon germanium film 402 is formed on the silicon oxide film 401 by using a film forming method such as a CVD method.

  In this modification, the silicon germanium film 402 is irradiated with light while the silicon germanium film 402 is formed, so that each of the interface between the silicon germanium film 402 and the silicon oxide film 401 and the surface of the silicon germanium film 402 is formed. The intensity of interference light (for example, wavelength 600 nm) formed by the reflected light is measured. FIG. 14A shows the change of the measured value with respect to the deposition time (that is, the deposited film thickness of the silicon germanium film 402 as the film to be processed), that is, the waveform of interference light. Here, the waveform of the interference light is basically a sine wave, but the waveform of the interference light is distorted by the germanium concentration in the silicon germanium film. Specifically, as shown in FIG. 14A, the interference light waveform of the silicon germanium film 402 to be evaluated (solid line in FIG. 14A) is the interference light waveform of the silicon germanium film having a known germanium concentration ( It becomes a distorted waveform shifted from the middle of the broken line in FIG. This occurs for the following reasons. That is, since the etching rate of the silicon germanium film changes depending on the germanium concentration, the frequency of the interference light waveform of the silicon germanium film 402 to be evaluated is equal to the frequency of the interference light waveform of the silicon germanium film having a known germanium concentration. Compared to change.

  In this modification, the relationship between the distortion of the waveform of the interference light, that is, the deviation generated in the sine wave and the germanium concentration is quantified in advance, and the measurement result shown in FIG. A change in germanium concentration in the film thickness direction of the silicon germanium film 402 as a treatment film can be evaluated. FIG. 14B shows the evaluation result.

  As described above, according to the modification of the fourth embodiment, the distortion of the waveform of the interference light measured by irradiating the silicon germanium film 402 with light during the deposition of the silicon germanium film 402 as the film to be processed. Based on the above, the change in the germanium concentration in the film thickness direction of the silicon germanium film 402 is evaluated. That is, by quantifying the relationship between the distortion of the waveform of the interference light and the germanium concentration, the change in the germanium concentration in the film thickness direction of the silicon germanium film is evaluated using the above-described interference light during the deposition of the silicon germanium film. To do. On the other hand, according to the conventional film quality evaluation method using SIMS or the like, there is a problem that it is expensive and requires a lot of time for analysis. That is, according to this modification, the germanium concentration measurement in the film thickness direction of the silicon germanium film can be performed easily and at a lower cost than the conventional film quality evaluation method.

  In the modification of the fourth embodiment, the germanium concentration in the silicon germanium film 402 is an object to be evaluated, but it goes without saying that the silicon concentration can be an object to be evaluated instead.

  In the modification of the fourth embodiment, the wavelength of the interference light used for the film quality evaluation is not particularly limited and can be set to any value.

  In the modification of the fourth embodiment, the film quality evaluation of the silicon germanium film is targeted. However, the present invention is not limited to this, and the film quality evaluation of other types of films composed of a plurality of elements (specifically, the element concentration The same effect can be expected when measuring).

  As described above, the present invention relates to a technique using interference light that is measured by irradiating light on a film to be processed. This is particularly useful when applied to the evaluation of film quality.

(A)-(c) is sectional drawing which shows each process of the manufacturing method of the electronic device which concerns on the 1st Embodiment of this invention. It is a figure which shows the waveform of the interference light measured at the time of the etching of the polysilicon film in the manufacturing method of the electronic device which concerns on the 1st Embodiment of this invention. (A) And (b) is sectional drawing which shows each process of the film quality evaluation method which concerns on the 2nd Embodiment of this invention. (A) is a figure which shows the waveform of the interference light measured at the time of the etching of the polysilicon film in the film quality evaluation method which concerns on the 2nd Embodiment of this invention, (b) uses the measurement result shown to (a). It is a figure which shows the result of having evaluated the density change in the film thickness direction of a polysilicon film. (A) And (b) is sectional drawing which shows each process of the film quality evaluation method which concerns on the modification of the 2nd Embodiment of this invention. (A) is a figure which shows the waveform of the interference light measured at the time of film-forming of the polysilicon film in the film quality evaluation method which concerns on the modification of the 2nd Embodiment of this invention, (b) is shown to (a). It is a figure which shows the result of having evaluated the density change in the film thickness direction of a polysilicon film using a measurement result. (A) And (b) is sectional drawing which shows each process of the film quality evaluation method which concerns on the 3rd Embodiment of this invention. (A) is a figure which shows the waveform of the interference light measured at the time of the etching of the polysilicon film in the film quality evaluation method which concerns on the 3rd Embodiment of this invention, (b) uses the measurement result shown to (a). It is a figure which shows the result of having evaluated the change of the impurity concentration in the film thickness direction of a polysilicon film. (A) And (b) is sectional drawing which shows each process of the film quality evaluation method which concerns on the modification of the 3rd Embodiment of this invention. (A) is a figure which shows the waveform of the interference light measured at the time of film-forming of the polysilicon film in the film quality evaluation method which concerns on the modification of the 3rd Embodiment of this invention, (b) is shown to (a). It is a figure which shows the result of having evaluated the change of the impurity concentration in the film thickness direction of a polysilicon film using a measurement result. (A) And (b) is sectional drawing which shows each process of the film quality evaluation method which concerns on the 4th Embodiment of this invention. (A) is a figure which shows the waveform of the interference light measured at the time of the etching of the silicon germanium film | membrane in the film quality evaluation method which concerns on the 4th Embodiment of this invention, (b) uses the measurement result shown to (a). It is a figure which shows the result of having evaluated the change of the germanium density | concentration in the film thickness direction of a silicon germanium film | membrane. (A) And (b) is sectional drawing which shows each process of the film quality evaluation method which concerns on the modification of the 4th Embodiment of this invention. (A) is a figure which shows the waveform of the interference light measured at the time of film-forming of the silicon germanium film | membrane in the film quality evaluation method which concerns on the modification of the 4th Embodiment of this invention, (b) is shown to (a). It is a figure which shows the result of having evaluated the change of the germanium concentration in the film thickness direction of a silicon germanium film | membrane using a measurement result. It is a figure which shows the structure of the etching apparatus to which the conventional end point detection method was applied. (A) And (b) is a figure which shows the relationship between the residual film thickness of the polysilicon film in the etching using the conventional end point detection method, and interference light. (A)-(c) is sectional drawing which shows each process of the manufacturing method of the semiconductor device using the conventional end point detection method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Semiconductor substrate 101 Element isolation 102 Gate oxide film 103 Polysilicon film 103A Polysilicon film 103B gate electrode 104 Void 105 Resist pattern 200 Resist pattern 200 Semiconductor substrate 201 Silicon oxide film 202 Polysilicon film 203 Void 300 Semiconductor substrate 301 Silicon oxide Film 302 Polysilicon film 303 Phosphorus 400 Semiconductor substrate 401 Silicon oxide film 402 Silicon germanium film

Claims (17)

An end point detection method used when processing a film to be processed,
Irradiating the film to be processed with light, measuring the interference light formed by the reflected light from the interface between the film to be processed and its underlayer and the surface of the film to be processed;
And a step of detecting an end point of processing on the film to be processed based on the measured disturbance of the interference light waveform. The waveform of the measured interference light is a sine wave,
The end point detection method according to claim 1, wherein the disturbance is noise generated in the sine wave.   The end point detection method according to claim 2, wherein the noise is generated due to a void existing in the film to be processed. A processing method for processing a film to be processed,
A processing method for detecting an end point of processing for the film to be processed using the end point detecting method according to claim 1.   The processing method according to claim 4, wherein an end point of processing for the processing target film is detected during processing of the processing target film.   6. The processing method according to claim 4, wherein plasma etching is used for processing the film to be processed.   6. The processing method according to claim 4, wherein chemical mechanical polishing is used in processing the film to be processed. An etching method for etching a film to be processed formed on an underlayer,
A first step of performing etching on the film to be processed and detecting an end point of the etching using the end point detection method according to any one of claims 1 to 3.
After the first step, a second condition in which the selective ratio of the film to be processed to the base layer is switched to a condition that is higher than that in the first step, and the etching is continuously performed on the film to be processed. An etching method comprising: a step. A film quality evaluation method for evaluating a film quality of a film to be processed,
Forming the film to be processed on the underlayer;
Etching is performed on the film to be processed, and light is applied to the film to be processed, so that reflected light from each of the interface between the film to be processed and the base layer and the surface of the film to be processed Measuring the formed interference light; and
And a step of evaluating a density change in the film thickness direction of the film to be processed based on the measured disturbance of the interference light waveform. The waveform of the measured interference light is a sine wave,
The film quality evaluation method according to claim 9, wherein the disturbance is noise generated in the sine wave.   The film quality evaluation method according to claim 10, wherein the noise is generated due to a void existing in the film to be processed. A film quality evaluation method for evaluating the film quality of a film to be treated into which impurities are introduced,
Forming the film to be processed on the underlayer;
Etching is performed on the film to be processed, and light is applied to the film to be processed, so that reflected light from each of the interface between the film to be processed and the base layer and the surface of the film to be processed Measuring the formed interference light; and
And a step of evaluating a change in the concentration of the impurity in the film thickness direction of the film to be processed based on the measured waveform distortion of the interference light. The waveform of the measured interference light is a sine wave,
The film quality evaluation method according to claim 12, wherein the distortion is a shift generated in the sine wave.   The film quality evaluation method according to claim 13, wherein the deviation occurs due to the impurities present in the film to be processed. A film quality evaluation method for evaluating the film quality of a film to be processed comprising a plurality of elements including at least one element,
Forming the film to be processed on the underlayer;
Etching is performed on the film to be processed, and light is applied to the film to be processed, so that reflected light from each of the interface between the film to be processed and the base layer and the surface of the film to be processed Measuring the formed interference light; and
And a step of evaluating a concentration change of the one element in the film thickness direction of the film to be processed based on the measured waveform distortion of the interference light. The waveform of the measured interference light is a sine wave,
The film quality evaluation method according to claim 15, wherein the distortion is a shift generated in the sine wave.   The film quality evaluation method according to claim 16, wherein the deviation occurs due to a concentration of the one element in the film to be processed.

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