JP2008235461A - Thin-film-removal sensing apparatus and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thin-film-removal sensing apparatus and method wherein whether a thin-film-removal has been completed or not can be decided by a simpler constitution, in a simpler manner, and at a lower cost than conventional ones. <P>SOLUTION: When removing a thin film present on a silicon wafer 10 the thin film removal sensing apparatus senses whether the thin-film-removal has been completed or not. A light is so irradiated on the silicon wafer 10 from a light source 20 as to transmit via an interference transmission filter 22 only the light having a specific wavelength of lights reflected via the wafer 10, and the light transmitted from the interference transmission filter 22 is so received by a light receiving sensor 24 as to measure the light intensity of the transmission light, and further, based on whether the intensity of the reflecting or absorbing light having the specific wavelength is a predetermined intensity itself or a predetermined rate of the predetermined intensity or not, whether the thin film present on the silicon wafer 10 has been removed or not is decided by a processing portion 36 of an information processing device 30. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a thin film removal detection apparatus and a thin film removal detection method for detecting whether or not a thin film has been removed when removing the thin film on a base material, and in particular, the thin film can be removed more easily with a simpler configuration. The present invention relates to a low-cost thin film removal detection apparatus and a thin film removal detection method that can determine whether or not they have been made.

  In a semiconductor manufacturing process, there is a process of removing a thin film on a semiconductor wafer by etching or the like. In such a removal process, in order to reliably remove a predetermined thin film, the film thickness of the thin film is accurately determined during the removal process. Need to be measured. Here, as a nondestructive film thickness measurement method, a method of optically measuring the film thickness using an interference method, ellipsometry, or the like is common.

  FIG. 6A is a schematic configuration diagram of a conventional thin film removal detection apparatus, and FIG. 6B is an explanatory diagram illustrating a spectrum analysis result in the conventional thin film removal detection method. In FIG. 6A, 10 is a silicon wafer, 20 is a light source that irradiates the silicon wafer 10 with light, 52 is a light receiving sensor that receives reflected light from the silicon wafer 10 and measures the light intensity, and 50 is reflected light. This is a spectrum analyzer for performing spectrum analysis.

  When light is irradiated onto the silicon wafer 10 from the light source 20 and the spectrum of the reflected light is analyzed by a spectrum analyzer, a spectrum analysis result as shown in FIG. 6B, for example, is obtained. The spectrum analysis result is the correlation between the frequency and the reflected or absorbed light intensity, that is, the distribution of the reflected or absorbed light intensity with respect to the frequency in a certain region, and depending on which frequency has the peak of the reflected or absorbed light intensity from the spectrum analysis result. The film thickness of the thin film on the silicon wafer 10 is detected.

Further, as a technique for further increasing the resolution of film thickness measurement, for example, there is “a film thickness management apparatus and a film thickness detection method” disclosed in JP-A-9-113229.
JP-A-9-113229

  However, in the conventional technology described above, it is necessary to always provide an expensive spectrum analyzer, and since it is necessary to measure all the frequencies in a certain region, it takes time for analysis processing, and processing time is reduced. In order to shorten it, it is necessary to prepare a more expensive spectrum analyzer.

  In addition, the above-described conventional thin film removal detection apparatus and thin film removal detection method described above are effective in applications that require strict management of process conditions such as the need to continuously change the process conditions through repeated processes. For example, in the use only as a determination means for determining whether or not the thin film can be removed without managing the film thickness, there is a circumstance that it is over spec and is not cost effective.

  The present invention has been made in view of the above-described conventional circumstances, and can determine whether or not a thin film can be more easily removed with a simpler configuration, and a low-cost thin film removal detection apparatus and It aims at providing the thin film removal detection method.

  In order to achieve the above object, the thin film removal detection apparatus according to claim 1 is a thin film removal detection apparatus that detects whether or not the thin film has been removed when removing the thin film on the base material. A light source for irradiating a base material with light; a filter that transmits only light of a specific wavelength out of reflected light from the base material; and a sensor that receives the transmitted light from the filter and measures the light intensity of the transmitted light; Determining means for determining whether or not the thin film on the base material has been removed based on whether the reflected or absorbed light intensity of the specific wavelength light has reached a predetermined intensity or a predetermined ratio of the predetermined intensity. It is characterized by that.

  The thin film removal detection apparatus according to claim 2, wherein each of the filters includes several filters that transmit only specific wavelength light among the reflected light from the base material. For all of the transmitted light from the individual filters, it is determined that the thin film on the base material has been removed when the reflected or absorbed light intensity of each specific wavelength reaches a predetermined intensity or a predetermined ratio of the predetermined intensity. It is characterized by.

  The thin film removal detection apparatus according to claim 3 is characterized in that a specific wavelength of the filter is determined according to a material of the base material and the thin film.

  The thin film removal detection apparatus according to claim 4, wherein the specific wavelength of the filter is a reflection or absorption spectrum of the reflected light when the base material before and after the thin film removal is irradiated with light in advance. Based on the result of the analysis, the wavelength at which the difference between the reflected or absorbed light intensities of the two becomes the maximum is determined, and the predetermined intensity used for the determination by the determining means or the predetermined ratio of the predetermined intensity is the reflection or absorption spectrum analysis of the reflected light. It is determined from the result.

  Further, in the thin film removal detection apparatus according to claim 5, the specific wavelength of each of the several filters is the reflected light when the base material before and after the thin film removal is irradiated with light in advance. From the result of the reflection or absorption spectrum analysis, it is determined by selecting several points from the larger one for the wavelength at which the difference between the reflected or absorbed light intensities becomes large. The predetermined ratio of the intensity is determined from the result of reflection or absorption spectrum analysis of the reflected light.

  The thin film removal detection apparatus according to claim 6 terminates the operation of removing the thin film on the base material after a predetermined time has elapsed after the determination unit determines that the thin film on the base material has been removed. It is characterized by.

  The thin film removal detection method according to claim 7 is a thin film removal detection method for detecting whether or not the thin film has been removed when removing the thin film on the base material. A measuring step of transmitting only a specific wavelength light of the reflected light from the base material through a filter and measuring the light intensity of the transmitted light, and the reflected or absorbed light intensity of the specific wavelength light is predetermined. And determining whether or not the thin film on the base material has been removed based on whether the strength or a predetermined ratio of the predetermined strength has been reached.

  Further, in the thin film removal detection method according to claim 8, each of the filters is several filters that transmit only a specific wavelength light among the reflected light from the base material, and the determination step includes the several filters. Determining that the thin film on the base material has been removed when the reflected or absorbed light intensity of each specific wavelength light reaches a predetermined intensity or a predetermined ratio of the predetermined intensity for all of the transmitted light from the filter Features.

  The thin film removal detection method according to claim 9 is characterized in that a specific wavelength of the filter is determined according to a material of the base material and the thin film.

  The thin film removal detection method according to claim 10, wherein the specific wavelength of the filter is a reflection or absorption spectrum of the reflected light when the base material before and after the thin film removal is irradiated with light in advance. Based on the analysis results, the wavelength at which the difference between the reflected or absorbed light intensities is the maximum is determined, and the predetermined intensity used for the determination in the determining step or the predetermined ratio of the predetermined intensity is the reflection or absorption spectrum analysis of the reflected light. It is determined from the result.

  Further, in the thin film removal detection method according to claim 11, the specific wavelength of each of the several filters is the reflected light when the base material before and after the thin film removal is irradiated with light in advance. From the result of the reflection or absorption spectrum analysis, a plurality of points having a larger difference between the reflected or absorbed light intensities are selected from the larger one, and the predetermined intensity used for the determination in the determination step or the predetermined The predetermined ratio of the intensity is determined from the result of reflection or absorption spectrum analysis of the reflected light.

  Furthermore, the thin film removal detection method according to claim 12 terminates the operation of removing the thin film on the base material after a predetermined time has elapsed since it was determined that the thin film on the base material was removed in the determination step. It is characterized by.

  According to the thin film removal detection apparatus and thin film removal detection method of the present invention having the above characteristics, a simple structure including an inexpensive light source, a filter of a specific wavelength, a sensor, and a determination means (for example, PC), and a base material and a thin film in advance. It is easy to determine whether or not the thin film on the base material has been removed based on whether the reflected or absorbed light intensity of the specific wavelength set according to the material reaches a predetermined intensity or a predetermined ratio of the predetermined intensity. The thin film removal detection can be performed with a simple procedure, and a lower cost thin film removal detection apparatus and thin film removal detection method can be realized.

  Hereinafter, embodiments of the thin film removal detection apparatus and the thin film removal detection method of the present invention will be described in detail with reference to the drawings. In this example, the thin film removal detection apparatus and thin film removal detection method of the present invention is completed when the thin film (nitride film, etc.) on the base material (semiconductor wafer) is removed and the base material is exposed. This is applied to a thin film removal processing apparatus.

〔Example〕
FIG. 1 is a configuration diagram of a thin film removal detecting apparatus according to an embodiment of the present invention. In the figure, the thin film removal detection apparatus of this embodiment determines whether or not the thin film has been removed when removing the thin film (for example, a nitride film) on the silicon wafer (base material in the claims) 10. A thin film removal detection device for detecting, from a light source 20 that irradiates light onto a silicon wafer 10, a transmission interference filter 22 that transmits only light of a specific wavelength among reflected light from the silicon wafer 10, and a transmission interference filter 22 A light receiving sensor 24 that receives the transmitted light and measures the light intensity of the transmitted light, and whether the reflected or absorbed light intensity of the specific wavelength light has reached a predetermined intensity or a predetermined ratio of the predetermined intensity. And an information processing device (determining means in the claims) 30 for determining whether or not the thin film on the substrate 10 has been removed.

  The silicon wafer 10, the light source 20, the transmission interference filter 22 and the light receiving sensor 24 are in an apparatus such as a thin film removal processing apparatus, and the silicon wafer 10 is centered on the axis during thin film removal work on the silicon wafer 10. It is assumed that the measuring instrument of the light source 20, the transmission interference filter 22 and the light receiving sensor 24 is scanned in the radial direction of the silicon wafer 10 by a movable mechanism (not shown) and performs measurement at any time.

  Further, the information processing device 30 inputs at least a light intensity signal from the light receiving sensor 24, outputs a scanning instruction to the movable mechanism of the measuring instrument of the light source 20, the transmission interference filter 22, and the light receiving sensor 24, and removes the thin film. An input / output unit 32 that outputs an instruction to start / end the thin film removal operation to the processing apparatus, and a storage unit 34 that stores predetermined light intensity at a specific wavelength of the transmission interference filter 22 for determining whether or not the thin film is removed. And a processing unit 36 that performs the above-described determination processing based on a user's operation instruction and a light intensity signal input from the light receiving sensor 24, and performs a control instruction to the movable mechanism of the measuring instrument and the thin film removal processing apparatus. For example, it is realized by a PC (personal computer) (for FA) having a display output and a sound output function.

  The specific wavelength of the transmission interference filter 22 is determined according to the base material and the material of the thin film (silicon wafer 10 and nitride film). That is, the specific wavelength of the transmission interference filter 22 is obtained by analyzing the reflection or absorption spectrum of the reflected light when the silicon wafer 10 is irradiated with light before and after removing the thin film by a spectrum analyzer separately prepared in advance. And from the spectrum analysis result, it is determined as the wavelength at which the difference between the reflected or absorbed light intensities is the maximum.

  When the absorption spectrum of near-infrared light before and after film removal of the silicon wafer 10 with nitride film was measured, the results shown in FIG. 5 were obtained. According to FIG. 5, the wavelength at which the difference between the two absorbed light intensities is maximum is 1034 [nm]. Therefore, in this embodiment, the specific wavelength of the transmission interference filter 22 is 1034 [nm] and the transmission wavelength width 1034 is set. A transmission interference filter of ± 1 [nm] was used.

  Further, in the processing unit 36 of the information processing apparatus 30, the predetermined light intensity at a specific wavelength of the transmission interference filter 22 for determining whether or not the thin film is removed is determined from the reflection or reflection spectrum analysis result of the reflected light. Here, although specific numerical values are not illustrated, in the absorption spectrum distribution of FIG. 5, the value of the absorbed light intensity after film removal at a wavelength of 1034 [nm], or a value of about 80 to 90 [%] of the value is a thin film. The threshold value for determining whether or not to remove is set in the storage unit 34. Here, the specific wavelength of the transmission interference filter 22 and the determination threshold are set based on the absorption spectrum distribution, but it goes without saying that the specific wavelength is determined by the reflection spectrum distribution.

  Further, in the processing unit 36 of the information processing apparatus 30, it is determined that the nitride film on the silicon wafer 10 has been removed when the signal value of the absorbed light intensity from the light receiving sensor 24 reaches the threshold value set in the storage unit 34. However, the processing unit 36 terminates the operation of removing the nitride film on the silicon wafer 10 after a predetermined time has elapsed since the threshold value was reached.

  For example, in the case of the silicon wafer 10 having a diameter of 300 [mm], it takes 7 [minutes] from the start of the removal process to the time when the threshold is reached. In this case, the predetermined time is set to 3 [minutes] and the threshold is set. The film removal operation was terminated after 3 [minutes] from the time of reaching.

  It should be noted that the threshold for determining whether or not the thin film is removed is what percentage of the absorbed light intensity after the film removal, and how long after the threshold is reached, the film removal operation is finished. It is desirable to set it empirically. In other words, the flexible setting of these combinations can provide a margin for the removal amount of the thin film, and can flexibly cope with changes in process conditions and lot variations.

  Next, the thin film removal detection method of this embodiment for determining whether or not the thin film (nitride film) on the silicon wafer 10 has been removed using the thin film removal detection apparatus having the above-described configuration will be described with reference to FIGS. This will be described with reference to the flowchart. Here, FIG. 2 is a flowchart for explaining a reflection (absorption) spectrum measurement process performed in advance before entering the thin film removal work, and FIG. 3 explains a judgment process for judging whether or not the thin film is removed during the thin film removal work. It is a flowchart.

  With reference to FIG. 2, the reflection (absorption) spectrum measurement process performed in advance before starting the thin film removal operation will be described. First, a silicon wafer 10 with a nitride film is prepared before and after the film removal process, and each of the silicon wafers 10 is irradiated with light from the light source 20, and the reflection or absorption spectrum of the reflected light is measured. Analysis is performed by a spectrum analyzer (step S101).

  Next, from the reflection or absorption spectrum distribution of the reflected light, the wavelength at which the difference between the reflected (absorbed) light intensities before and after the film removal process is maximized is set as the specific wavelength of the transmission interference filter 22 to remove the film. With respect to the processed wafer, the reflected (absorbed) light intensity value of the specific wavelength is stored in the storage unit 34 as a threshold value for determining later whether or not the thin film is removed in the processing unit 36 of the information processing apparatus 30 (step). S102).

  Specifically, when the absorption spectrum of near-infrared light before and after film removal of the silicon wafer 10 with nitride film was measured, the result shown in FIG. 5 was obtained. The specific wavelength of the filter 22 is set to 1034 [nm], and the thin film removal detection apparatus is configured using a transmission interference filter having a transmission wavelength width of 1034 ± 1 [nm]. Further, in the absorption spectrum distribution of FIG. 5, it is determined whether or not the value of the absorbed light intensity after film removal at a wavelength of 1034 [nm] or a value of about 80 to 90 [%] of the value is to remove the thin film. The threshold value is set in the storage unit 34. Here, the specific wavelength of the transmission interference filter 22 and the determination threshold are set based on the absorption spectrum distribution, but it goes without saying that the specific wavelength is determined by the reflection spectrum distribution.

  Next, a determination process for determining whether or not thin film removal is completed by the thin film removal detection apparatus of this embodiment during the thin film removal operation by the thin film removal processing apparatus will be described with reference to FIG. First, light is emitted from the light source 20 onto the silicon wafer 10, and only light having a specific wavelength out of the reflected light from the silicon wafer 10 is transmitted through the transmission interference filter 22. The light receiving sensor 24 reflects or reflects the transmitted light. The absorbed light intensity is measured (measurement step in the claims: step S201).

  Next, the information processing device 30 receives the light intensity signal from the light receiving sensor 24, and the processing unit 36 reflects or absorbs the specific wavelength light transmitted through the transmission interference filter 22 with a predetermined intensity or a predetermined intensity. It is determined whether or not a predetermined ratio (the threshold set in the storage unit 34 in step S102) has been reached (step S202). If the reflected or absorbed light intensity has reached the threshold value, the process proceeds to step S203, and if the reflected or absorbed light intensity has not reached the threshold value, the measurement in step S201 is continued.

  Further, it is determined whether or not a predetermined time has elapsed since the reflected or absorbed light intensity reached the threshold set in the storage unit 34 (step S203). That is, in the processing unit 36 of the information processing apparatus 30, it is temporarily determined that the nitride film on the silicon wafer 10 has been removed when the reflected or absorbed light intensity reaches the threshold value set in the storage unit 34. After a predetermined time has elapsed from the point of arrival, the operation is terminated assuming that the removal of the nitride film on the silicon wafer 10 is completed.

  At this time, the light intensity signal from the light receiving sensor 24 follows the process as shown in FIG. 4 along with the process time. When the value α of the absorbed light intensity after film removal at the wavelength 1034 [nm] is set as a threshold value for determining whether or not the thin film is removed, the light intensity signal from the light receiving sensor 24 is a threshold value at time X. The film removal operation is terminated after a predetermined time has elapsed from time X when α is reached. In addition, the process of the said step S202 and step S203 corresponds to the judgment step said to a claim.

  As described above, the thin film removal detection apparatus according to the present embodiment is a thin film removal detection apparatus that detects whether or not the thin film has been removed when the thin film on the silicon wafer 10 is removed. By irradiating the wafer 10 with light, only light having a specific wavelength out of the reflected light from the silicon wafer 10 is transmitted through the interference transmission filter 22, and the transmitted light from the interference transmission filter 22 is received by the light receiving sensor 24. The light intensity of the transmitted light is measured, and the processing unit 36 (determination means) of the information processing device 30 determines whether the reflected or absorbed light intensity of the specific wavelength light has reached a predetermined intensity or a predetermined ratio of the predetermined intensity. It is determined whether or not the thin film on the silicon wafer 10 has been removed.

  The thin film removal detection method of the present embodiment is a thin film removal detection method for detecting whether or not the thin film has been removed when the thin film on the silicon wafer 10 is removed. Light is emitted from the light source, and only the specific wavelength light of the reflected light from the silicon wafer 10 is transmitted through the interference transmission filter 22, and the light intensity of the transmitted light is measured. Whether or not the thin film of the silicon wafer 10 has been removed is determined based on whether or not the reflected or absorbed light intensity reaches a predetermined intensity or a predetermined ratio of the predetermined intensity.

  The specific wavelength of the interference transmission filter 22 is determined according to the material of the silicon wafer 10 and the thin film, and the reflection or absorption of the reflected light when the silicon wafer 10 before and after the thin film removal is irradiated with light in advance. From the result of spectrum analysis, the wavelength at which the difference between the reflected or absorbed light intensities is the maximum is determined, and the predetermined intensity or the predetermined ratio of the predetermined intensity used in the determination in the determination means or determination step is the reflection or absorption of the reflected light. It is desirable to be determined from the result of spectrum analysis.

  In this way, a simple configuration including an inexpensive light source 20, an interference transmission filter 22 having a specific wavelength, a light receiving sensor 24, and an information processing device (PC, etc.) 30, and a specific setting previously set according to the material of the base material and the thin film Thin film removal detection is performed by a simple procedure of judging whether or not the thin film on the base material has been removed based on whether the reflected or absorbed light intensity of the wavelength light has reached a predetermined intensity or a predetermined ratio of the predetermined intensity. Thus, a lower-cost thin film removal detection apparatus and thin film removal detection method can be realized.

  Note that unlike the prior art, it is not necessary to control a specific frequency on the light source 20 side, and there is no need to analyze the light intensity for all wavelengths in a certain region on the light receiving side. Further, in order to set a specific wavelength of the interference transmission filter 22 and a predetermined intensity or a predetermined ratio of the predetermined intensity used for determination in the determination means or determination step, it is necessary to prepare a spectrum analyzer separately. It is sufficient that at least one unit is provided at the location, and it is not necessary to always keep it in an individual apparatus such as a thin film removing apparatus.

[Modification]
In the thin film removal detection apparatus and the thin film removal detection method of the embodiment described above, the reflection of the reflected light or the absorption spectrum analysis result when the silicon wafer 10 is irradiated with light before and after the thin film removal is reflected from both. Alternatively, the wavelength that maximizes the difference in absorbed light intensity is set as the specific wavelength of the filter, and the single transmission interference filter 22 is used. However, several transmission interference filters having different specific wavelengths may be used.

  In this case, the determining means (the processing unit 36 of the information processing device 30) reflects or reflects each specific wavelength light for all the transmitted light from the several transmission interference filters in the determining step (step S202 in FIG. 3). When the absorbed light intensity reaches a predetermined intensity or a predetermined ratio of the predetermined intensity, it is determined that the thin film on the base material has been removed.

  The specific wavelengths of several transmission interference filters are determined according to the base material and the material of the thin film (silicon wafer 10 and nitride film), respectively, as in the embodiment. That is, the specific wavelength of each of the several transmission interference filters is obtained by spectral analysis of the reflected light when the silicon wafer 10 is irradiated with light before and after removing the thin film by a separately prepared spectrum analyzer. From the result of the spectrum analysis, several points are selected from the larger one for the wavelength at which the difference between the reflected or absorbed light intensities is large.

  In addition, a threshold (a predetermined light intensity at each specific wavelength of several transmission interference filters or a predetermined ratio of the predetermined intensity) for determining whether or not to remove a thin film in the determination means (the processing unit 36 of the information processing device 30). ) Is determined from the reflection or absorption spectrum analysis result of the reflected light as in the embodiment. As for the intensity ratio, the threshold is set to a uniform intensity ratio (80 to 100 [%]) for several specific wavelengths, or the intensity ratio of the wavelength that maximizes the difference in reflected or absorbed light intensity. Is set higher than the intensity ratio of the other selected wavelengths, and the wavelength with the largest difference is set to be relatively difficult to make a judgment, and the weight of the wavelength with the largest difference is further increased. Various settings such as a technique to be performed are conceivable.

  According to the thin film removal detection device and the thin film removal detection method of the present modification, the cost for several transmission interference filters is increased as compared with the embodiment, and the processing in the determination step is slightly increased. Compared with the conventional thin film removal detection apparatus and thin film removal detection method, the increment is slight, and a low-cost thin film removal detection apparatus and thin film removal detection method can be realized. Further, in the thin film removal detection apparatus and thin film removal detection method of this modification, detection accuracy and certainty are improved as compared with the embodiment, and therefore detection accuracy and certainty are given priority even if there is a slight increase in cost. Desirably applied to the device.

  In the embodiment and the modification described above, the thin film removal detection apparatus and the thin film removal detection method of the present invention are used. Although the thin film (nitride film) on the base material (semiconductor wafer) is removed and described as a form applied to the thin film removal processing apparatus that completes processing when the base material is exposed, it is not limited to this, For example, the present invention can be applied to various other uses such as determining whether or not a thin film such as paint has been removed.

It is a block diagram of the thin film removal detection apparatus which concerns on one Example of this invention. FIG. 2 is a flowchart for explaining the reflection (absorption) spectrum measurement process. FIG. 3 is a flowchart for explaining determination processing for determining whether or not thin film removal is performed during thin film removal work. It is explanatory drawing which illustrates the time passage of the light intensity signal from the light receiving sensor. It is explanatory drawing which illustrates the absorption spectrum analysis result of the near-infrared light before a film removal and after a film removal. FIG. 6A is a schematic configuration diagram of a conventional thin film removal detection apparatus, and FIG. 6B is an explanatory view illustrating a spectrum analysis result in a conventional thin film removal detection method.

Explanation of symbols

10 Silicon wafer (base material)
20 Light source 22 Transmission interference filter (filter)
24,52 Light receiving sensor (sensor)
30 Information processing device (judgment means)
32 Input / output unit 34 Storage unit 36 Processing unit 50 Spectrum analyzer

Claims (12)

A thin film removal detecting device for detecting whether or not the thin film is removed when removing the thin film on the base material,
A light source for irradiating the base material with light;
A filter that transmits only a specific wavelength of the reflected light from the base material;
A sensor that receives the transmitted light from the filter and measures the light intensity of the transmitted light;
Determining means for determining whether the thin film on the base material has been removed based on whether the reflected or absorbed light intensity of the specific wavelength light has reached a predetermined intensity or a predetermined ratio of the predetermined intensity;
A thin film removal detecting device comprising: Each of the filters has several filters that transmit only specific wavelength light among the reflected light from the base material,
The determination means includes a thin film on the base material when the reflected or absorbed light intensity of each specific wavelength light reaches a predetermined intensity or a predetermined ratio of the predetermined intensity for all of the transmitted light from the several filters. The thin film removal detection apparatus according to claim 1, wherein the film removal is determined to be removed.   3. The thin film removal detection apparatus according to claim 1, wherein a specific wavelength of the filter is determined according to a material of the base material and the thin film. The specific wavelength of the filter is determined in advance from the result of reflection or absorption spectrum analysis of the reflected light when the base material before and after removal of the thin film is irradiated with light. Is defined as the maximum wavelength,
The predetermined intensity used for determination by the determination means or the predetermined ratio of the predetermined intensity is determined from the result of reflection or absorption spectrum analysis of reflected light. Thin film removal detector. The specific wavelength of each of the several filters is determined based on the reflection or absorption spectrum analysis of the reflected light when the base material before and after the thin film removal is irradiated with light. For the wavelength where the difference in absorbed light intensity is large, several points are selected from the larger one, and are determined.
5. Each predetermined intensity used for determination by the determination means or a predetermined ratio of the predetermined intensity is determined from the result of reflected light reflection or absorption spectrum analysis. The thin film removal detection apparatus according to 1.   6. The operation of removing the thin film on the base material is terminated after a lapse of a predetermined time after the judgment means judges that the thin film on the base material has been removed. The thin film removal detection apparatus according to item 1. A thin film removal detection method for detecting whether or not the thin film has been removed when removing the thin film on the base material,
A measurement step of irradiating the base material with light from a light source, allowing only a specific wavelength light of the reflected light from the base material to pass through a filter, and measuring the light intensity of the transmitted light;
A determination step of determining whether the thin film on the base material has been removed based on whether the reflected or absorbed light intensity of the specific wavelength light has reached a predetermined intensity or a predetermined ratio of the predetermined intensity;
A thin film removal detection method characterized by comprising: Each of the filters is several filters that transmit only specific wavelength light among the reflected light from the base material,
In the determination step, for all of the transmitted light from the several filters, when the reflected or absorbed light intensity of each specific wavelength reaches a predetermined intensity or a predetermined ratio of the predetermined intensity, the thin film on the base material The thin film removal detection method according to claim 7, wherein it is determined that the film has been removed.   9. The thin film removal detection method according to claim 7, wherein a specific wavelength of the filter is determined according to a material of the base material and the thin film. The specific wavelength of the filter is determined in advance from the result of reflection or absorption spectrum analysis of the reflected light when the base material before and after removal of the thin film is irradiated with light. Is defined as the maximum wavelength,
10. The predetermined intensity used for the determination in the determination step or the predetermined ratio of the predetermined intensity is determined from the result of reflection of reflected light or an absorption spectrum analysis. Thin film removal detection method. The specific wavelength of each of the several filters is determined based on the reflection or absorption spectrum analysis of the reflected light when the base material before and after the thin film removal is irradiated with light. For the wavelength where the difference in absorbed light intensity is large, several points are selected from the larger one, and are determined.
11. The method according to claim 7, wherein each predetermined intensity or a predetermined ratio of the predetermined intensity used for the determination in the determination step is determined from a result of reflected light reflection or absorption spectrum analysis. The thin film removal detection method according to 1.   The operation of removing the thin film on the base material is terminated after a predetermined time has elapsed since it was determined that the thin film on the base material was removed in the determination step. 2. The thin film removal detection method according to item 1.

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