JP2019161234A - Plasma processing apparatus and plasma processing method - Google Patents

Abstract

To enhance yield of processing by precisely detecting remaining thickness of a membrane to be processed during the processing.SOLUTION: A plasma processing method for processing a membrane structure formed previously on an upper surface of a wafer placed in a processing chamber inside a vacuum container, the membrane structure including a membrane to be processed and a mask layer placed thereunder, by using plasma formed in the processing chamber includes a step of calculating an etching amount of a membrane to be processed at the time during processing an arbitrary wafer, by using comparison results of data of an actual pattern and data of a detection pattern synthesizing the actual pattern of intensity having as a parameter wavelength of interference light obtained during processing of the membrane structure on an arbitrary wafer, and two intensity patterns having as a parameter the wavelength of the interference light obtained by processing in advance the membrane structure having the membrane to be processed and three or more mask layers having different thickness before processing the arbitrary wafer.SELECTED DRAWING: Figure 1

Description

The present invention relates to a plasma processing apparatus or a plasma processing method for detecting an etching end point when a substrate-like sample is etched in the manufacture of a semiconductor integrated circuit or the like, and in particular, a semiconductor wafer disposed in a processing chamber in a vacuum vessel. The present invention relates to a plasma processing apparatus and a plasma processing method for performing etching processing while detecting a processing state using plasma in which a film structure including a processing target film provided in advance on a top surface of a substrate-like sample is formed in a processing chamber .

In the process of manufacturing a semiconductor device from a substrate-like sample such as a semiconductor wafer, film layers of various materials formed on the surface of the wafer, particularly removal of a dielectric material film layer or pattern formation on the film. For the formation, a dry etching technique using plasma formed in a processing chamber in a vacuum vessel is widely used. In such an etching processing apparatus using plasma, an electric field or a magnetic field is applied to a processing gas introduced into a processing chamber which is a processing space in a vacuum vessel to form plasma, and charged particles such as ions in the obtained plasma. In general, a film to be processed is etched by reacting a highly active particle (radical) with a film structure including a film layer to be processed which is arranged in advance on the wafer surface.

During such a wafer etching process, it is known that the intensity of a specific wavelength in the emission of the formed plasma changes with the progress of etching of the film to be processed. Therefore, a change in the emission intensity of a specific wavelength from the plasma during such processing is detected during the processing, and based on the detected result, the film is removed by etching, or the etching end point that has reached the desired depth Conventionally, a technique for detecting the above has been known.

In particular, in order to achieve higher integration of semiconductor devices and miniaturization of processing, it is important to end the processing with a predetermined value for the remaining thickness of the film to be processed in the etching process. As a technique for terminating the etching process by setting the thickness of the film to be processed to a predetermined value, as the remaining thickness of the film to be processed decreases with the progress of etching, from the wafer surface including the film to be processed. There has been known a technique for detecting the remaining film thickness by using the change in intensity of the interfered light (interference light) by utilizing the formation of an interfering waveform.

Further, after applying a mask material on the wafer, for example, there is a step of etching a silicon substrate to form a groove in the silicon for electrically separating elements on the wafer. In this case, it is important to finish the process by etching the silicon substrate by a predetermined depth.

For example, Patent Document 1 discloses a technique in which at least two types of wavelengths of interference light are detected, and the remaining thickness of the film to be processed is detected using the intensity values of the interference light of the plurality of wavelengths. . Patent Document 2 discloses a pattern of data relating to the intensity of interference light obtained by detecting interference light of a plurality of wavelengths and using a plurality of wavelengths determined in advance as parameters, and the intensity of interference light actually obtained. A technique for detecting the remaining thickness of the film to be processed by comparing the data with respect to the above is disclosed.

In Patent Document 3, a method is known in which known light from the outside is incident, the wavelengths of the three lights reflected from the wafer are observed, frequency analysis is performed, and the etching depth is calculated. In Patent Document 4, a method is known in which plasma light is reflected by a material to be processed, interference light is observed, a mask component and a step component are separated from each other according to a wavelength band of the interference waveform, and an etching depth is calculated.

JP 2001-085388 A JP 2003-083720 A JP 2010-034582 A JP 2003-83720 A

The above prior art has a problem because the following points are insufficiently considered.

For example, it is known that an oxide film formed by LPCVD (Low Pressure Chemical Vapor Deposition) has low reproducibility of the thickness of the film, and it is said that the reproducibility is about 10%. On the other hand, in the etching process, even if the thickness of the film to be processed has such a variation, the techniques disclosed in Patent Document 1 and Patent Document 2 can generate interference light according to the absolute value of the remaining film thickness. By detecting the change in intensity, the remaining thickness of the film to be processed can be detected with high accuracy.

However, if the underlying film, which is the lower layer of the film to be processed, is made of a material that transmits light and its thickness varies greatly from sample to sample, the interference light obtained on each wafer Since the strength of the film becomes different even if the remaining thickness of the film to be processed is the same, there is a problem that the remaining thickness of the film to be processed cannot be accurately detected. Such a problem has not been taken into consideration in the above-described conventional technology.

SUMMARY OF THE INVENTION A first object of the present invention is to provide a plasma processing apparatus and a plasma processing method for accurately detecting the remaining thickness of a film to be processed during an etching process using plasma and improving the processing yield. .

In addition, in order to separate the elements formed on the wafer, it is important to etch the depth of the groove formed in the silicon by a predetermined depth and finish the process.

However, Patent Document 3 has problems with respect to the following points. Only the interference between the surface layer of the film to be etched (silicon) and the bottom of the etching is considered in light reflected from the wafer. Actually, since the light is reflected also from, for example, the surface layer of the resist mask formed on the silicon, it is necessary to consider the remaining film amount of the resist mask. Therefore, with this method, the depth of the film to be etched (silicon) cannot be detected accurately.

Moreover, in patent document 4, the problem has arisen about the following points. For example, when the interference waveform of the mask component and the interference waveform of the step component overlap at all wavelengths, the mask component and the step component cannot be separated by the wavelength band. For this reason, in this method, the depth of the etching target film (silicon) may not be detected accurately.

It is a second object of the present invention to provide a plasma processing apparatus or a plasma processing method for reducing the influence from a mask material formed on a substrate and detecting the etching amount with high accuracy to improve the processing yield. is there.

An object of the present invention is to provide a film structure formed in advance on the upper surface of a wafer placed in a processing chamber inside a vacuum vessel and including a film to be processed and a mask layer disposed above the film structure. A plasma processing method for processing using a formed plasma, wherein an actual pattern having an intensity using a wavelength of interference light obtained from the film to be processed as a parameter during processing of the film structure on an arbitrary wafer A plurality of intensities using the data and the wavelength of the interference light with respect to the film thickness of the film to be processed of the film structure having the film to be processed and the mask layer in advance before the processing of the arbitrary wafer as a parameter And the detection pattern data obtained by synthesizing two of the three or more patterns having different mask layer thicknesses. By providing and determining the arrival to the processing of the target membrane of the processing target using the steps and the etching amount for calculating the amount of etching of the serial processing target membranes is achieved.

The remaining film thickness value of the material to be processed can be accurately detected in consideration of the influence of the base film formed under the material to be processed. Further, the depth value of the material to be processed can be accurately detected in consideration of the influence of the mask material formed on the material to be processed. Furthermore, it is possible to manage the thickness of the underlying film and the initial film thickness of the mask and feed back to the previous CVD process.

It is a figure which shows typically the outline of a structure of the plasma processing apparatus which concerns on 1st Example of this invention. It is a figure which shows typically the film | membrane structure on the wafer which the plasma processing apparatus shown in FIG. 1 makes the object of an etching process. It is a graph which shows the relationship between the intensity value of the interference light based on the film | membrane structure shown in FIG. 2, and the thickness of a base film. It is a flowchart which shows the flow of the operation | movement which detects the etching amount of the plasma processing apparatus which concerns on 1st Example shown in FIG. It is a graph which shows the implementation result of the wafer etched in the 1st Example shown in FIG. It is a figure which shows typically the outline of a structure of the plasma processing apparatus which concerns on 2nd Example of this invention. It is a longitudinal cross-sectional view which shows typically the structure of the film | membrane structure which the plasma processing apparatus concerning 2nd Example shown in FIG. 6 processes. It is a flowchart which shows the flow of the process which the plasma processing apparatus based on 2nd Example shown in FIG. 6 performs. It is a graph which shows the differential waveform pattern obtained when the wafer which has the film | membrane structure shown in FIG. 7 is etched using the plasma processing apparatus which concerns on the modification shown in FIG. By calculating the theoretical differential waveform pattern of the interference light from the mask film layer and subtracting the corresponding data of the theoretical differential waveform pattern from each data of the actual differential waveform pattern of the interference light from the film structure, It is a flowchart which shows the flow of the operation | movement which calculates a waveform pattern.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

A first embodiment of the present invention will be described below with reference to FIGS.

A plasma processing apparatus 1 according to a first embodiment of the present invention is shown in FIG. FIG. 1 is a diagram schematically showing a schematic configuration of a plasma processing apparatus according to an embodiment of the present invention.

The plasma processing apparatus 1 includes a vacuum processing chamber 2 disposed inside a vacuum vessel. The lower part of the vacuum vessel is connected to an exhaust device having a vacuum pump such as a turbo molecular pump although not shown. Also, above and around the cylindrical vacuum vessel, there are a coaxial cable to which high-frequency power (not shown) is supplied, an electric field generating means such as an antenna or a waveguide that propagates microwaves, or a solenoid coil. A magnetic field generating means is arranged so that an electric field or a magnetic field can be supplied into the vacuum processing chamber 2.

The outer side wall of the vacuum vessel of the plasma processing apparatus 1 of the present embodiment is connected to a vacuum transfer vessel which is another vacuum vessel (not shown), and between the transfer chamber which is a decompressed internal space in the vacuum transfer vessel. The wafer 4 to be processed is transferred and exchanged. In addition, a sample stage 5 on which the wafer 4 has a cylindrical shape and is placed on the upper surface is disposed in the central portion of the lower portion of the vacuum processing chamber 2. Further, the vacuum container is connected to a supply pipe for gas supply (not shown), and the gas supply pipe communicates with a plurality of gas introduction holes arranged on the top or the ceiling surface of the vacuum processing chamber 2.

In such a plasma processing apparatus 1, the wafer 4 as a sample placed on the tip of the arm of a transfer robot disposed in a vacuum transfer container is transferred in the transfer chamber, and the arm extends to expand the vacuum. It enters into the vacuum processing chamber 2 through a gate which is an opening disposed on the side wall of the container, and is transferred to the sample table 5 disposed in the vacuum processing chamber 2. Thereafter, the robot arm contracts to exit from the vacuum processing chamber 2 and the gate is hermetically closed from the outside of the vacuum processing chamber 2 by a gate valve (not shown) to seal the inside of the vacuum processing chamber 2.

Further, the wafer 4 is attracted and held by static electricity on the upper surface made of a dielectric of the sample table 5 which is the mounting surface. A heat transfer gas such as He is supplied between the back surface of the wafer 4 and the mounting surface of the sample table 5 to promote heat conduction between the wafer 4 and the sample table 5.

A processing gas supplied from a gas introduction hole through a gas supply pipe connected to a gas source is introduced into the vacuum processing chamber 2, and the inside of the vacuum processing chamber 2 is exhausted by the operation of the exhaust device, so that a vacuum is generated. The inside of the processing chamber 2 is depressurized to a pressure of a degree of vacuum suitable for processing a substrate-like sample such as a semiconductor wafer by the balance between the gas supply rate and the exhaust rate. In this state, an electric field or a magnetic field is supplied from the means for generating an electric field or a magnetic field to the inside of the vacuum processing chamber 2, and particles of the processing gas are excited to form plasma 3. A film structure in which a plurality of films formed in advance on the upper surface of the wafer 4 on the sample stage 5 is laminated is etched by charged particles or highly reactive particles (active particles) contained in the plasma 3.

Since the excited particles contained in the plasma 3 emit the increased energy as light, the plasma 3 emits light. A light receiver 8 having a translucent member such as a light receiver for receiving and detecting the light emission of the plasma is disposed on the ceiling surface above the vacuum processing chamber 2 and on the upper part of the vacuum vessel. The light emitted from the plasma 3 is reflected directly or on the upper surface of the wafer, then received by the light receiver 8 and transmitted as a signal to the etching amount detector 9 electrically or optically connected or connected thereto.

A typical example of the film structure to be etched in this embodiment will be described with reference to FIG. FIG. 2 is a diagram schematically showing a film structure on a wafer to be subjected to an etching process by the plasma processing apparatus shown in FIG.

As shown in FIG. 2A, the film structure to be processed in this embodiment is a polysilicon film 201 that is a film to be processed and an oxide film that is a film layer disposed in contact with the polysilicon film 201 below. A base film 202 and a silicon substrate 203 are included. Light from the plasma incident on the film structure having such a configuration is reflected at the boundary or interface between the films to generate reflected light. The reflected light includes reflected light 221 reflected at the surface of the polysilicon film 201, reflected light 222 reflected at the boundary between the polysilicon film 201 and the base film 202, and reflected light 223 reflected at the boundary between the base film 202 and the silicon substrate 203. Exists.

Interference light is formed because an optical path difference occurs between these reflected lights. Further, as the etching progresses, the thickness of the polysilicon film 201 which is the film to be processed decreases, so that the optical path difference of each reflected light changes, and the period of change in intensity differs for each wavelength of the light. Interference phenomenon occurs.

The interference light whose intensity changes in this way is transmitted to the spectroscope 10 of the etching amount detection device 9 through the light receiver 8 facing the plasma 3 in the upper part of the vacuum processing chamber 2 in FIG. The etching amount detection device 9 detects the intensity value of the interference light and the amount of change thereof from the signal related to the transmitted interference light, and based on the result, the etching depth and the remaining amount of the polysilicon film 201 that is the film to be processed The etching amount such as the film thickness and the arrival at the end point of the process are determined.

As shown in FIG. 1, the etching amount detection device 9 of this embodiment includes a spectroscope 10, a first digital filter 12, a differentiator 13, a second digital filter 14, a differential waveform comparator 15, and different base film thicknesses. Three or more differential waveform pattern databases 16, a residual calculator 17 for obtaining a residual σ using these differential waveform comparators, and a database selector for extracting two pattern databases DBj and DBk having a small residual σ calculated by the calculator 17 18, a synthesis database generator 19 that synthesizes a synthesis database from the selected database, a pattern matching comparator 20 that performs pattern matching with a synthesis database using α as a parameter, and a synthesis coefficient for obtaining a synthesis coefficient α with the smallest residual Based on the output from the calculator 21 and the calculator 21 and the pattern matching comparator 20. The residual film thickness time series data recorder 22 for calculating the instantaneous residual film thickness of the film to be processed and recording this in time series, and the residual film thickness recorded by the residual film thickness time series data recorder 22 A regression analyzer 23 that calculates the current value of the remaining film thickness using the time series data, an end point determination unit 24 that determines the end of etching from the current value of the remaining film thickness, and an end point determination unit 24 A display 25 for displaying the determination result is provided.

In the etching amount detection apparatus 9 of this embodiment, except for the display unit 26, detection units including semiconductor devices such as microprocessors each having a plurality of functions are connected by a wired or wireless communication line. It may be a thing, and may be comprised with one semiconductor device which can show | play these several functions. A detection unit including a semiconductor device includes a computing unit such as a microprocessor, a communication interface for communicating signals with the outside, a RAM, a ROM for storing signals, data and software, a hard disk drive, a CD- A storage device such as a ROM drive is provided and these are communicably connected.

The light emitted from the plasma 3 formed in the vacuum processing chamber 2 is reflected by the upper surface of the wafer 4 and transmitted to the spectroscopic device 10 through the light receiver 8. In the spectroscopic device 10 that has received the signal from the light receiver 8, the interference light signal is split into a predetermined frequency, and the intensity of each wavelength is converted into a digital signal and output.

Signals of a plurality of specific wavelengths output as sampling signals at arbitrary times during processing of the wafer 4 by the spectroscope 10 are stored in a storage device such as a RAM (not shown) as time series data yij. The time series data yij is transmitted to the first digital filter 12, smoothed, and stored as smoothed time series data Yij in a storage device such as a RAM.

Next, the smoothed time series data Yij is transmitted to the differentiator 13, and time series data dij of the time differential (derivative) value (primary differential value or secondary differential value) is calculated and stored in a storage device such as a RAM. Remembered. The time series data dij of the derivative values is smoothed by the second digital filter 14 and stored in a storage device such as a RAM as smoothed derivative coefficient time series data Dij. Then, from this smoothed differential coefficient time series data Dij, a differential waveform pattern (actual pattern) indicating the wavelength dependence of the differential value of the intensity of the interference light (with wavelength as a parameter) is obtained.

Here, calculation of the smoothed differential coefficient time series data Di will be described. In the present embodiment, for example, a secondary Butterworth low-pass filter is used as the digital filter circuit 12. Smoothed time-series data Yi that is smoothed by a secondary Butterworth low-pass filter is obtained by equation (1).

Yi = b1 ・ yi + b2 ・ yi-1 + b3 ・ yi-2-[a2 ・ Yi-1 + a3 ・ Yi-2] (1)

Here, the coefficients b and a have different numerical values depending on the sampling frequency and the cutoff frequency. For example, a2 = -1.143, a3 = 0.4128, b1 = 0.067455, b2 = -0.013491, b3 = 0.067455 (sampling frequency 10 Hz, cut-off frequency 1 Hz) are used as digital filter coefficient values in this embodiment. The time-series data di of the second derivative value is calculated by the differentiator 13 from the equation (2) using the polynomial-adapted smoothing differentiation method of the five-point time-series data Yi as follows.

j = 2
di = Σwj · Yi + j (2)
j = -2

Here, w−2 = 2, w−1 = −1, w0 = −2, w1 = −1, h, w2 = 2 with respect to the weight coefficient w. Using the time-series data di of the derivative values, the smoothed derivative coefficient time-series data Di is calculated as follows from the equation (3) by a second-order Butterworth low-pass filter as the digital filter circuit 14, for example.

Di = b1 ・ di + b2 ・ di-1 + b3 ・ di-2-[a2 ・ Di-1 + a3 ・ Di-2] (3)

In the differential waveform pattern database 16, the remaining film thickness during the etching process of polysilicon, which is the film to be processed, which is an object of the etching amount measurement disposed above the underlying oxide film having a predetermined film thickness. A data value DBi of a pattern using a waveform of a differential value indicating a change in the intensity of interference light corresponding to the amount (the amount of remaining film) as a parameter is stored in advance prior to processing of the wafer 4. In the differential waveform comparator 15, an actual pattern value and a differential waveform pattern database 16, which are patterns using the waveform of the differential value of the intensity relating to the interference light actually obtained during the processing of the wafer 4 as a parameter, are stored. The differential waveform pattern data value DBi is compared to calculate a residual value σ between the two patterns.

For example, the waveform of the change due to the change in the value of the remaining film thickness of the differential value of the interference light intensity at the same wavelength (which can be considered to correspond to the time or time after the start of processing) is expressed as DBi. A difference is determined for each remaining film thickness value from the pattern, and this is determined for the entire band of a predetermined wavelength or for a specific plurality of wavelengths. These can be detected as a pattern of residual values of both.

The differential waveform pattern stored in the differential waveform pattern database 16 and registered as used for detecting the thickness of the remaining film amount is an upper limit and a lower limit of the film thickness of the oxide film 202 which is a base film that varies in an arbitrary range. In order to mass-produce semiconductor devices, an oxide film 202 having a thickness of a value close to these values or a film structure of polysilicon, which is a process-symmetric film for measuring an etching amount disposed thereon, is used. To the value of the remaining film thickness (remaining film amount) of the film to be processed when the film structure including the mask layer on the actual wafer is subjected to the same processing conditions as the etching process. Three or more differential value patterns using the wavelength of the intensity of the interference light as a parameter are used. That is, the differential pattern of the intensity used as a parameter for the wavelength of the interference light used for detecting the remaining film thickness is at least three patterns with different base films RAM and ROM constituting the differential waveform pattern database 16 Alternatively, the data value DBi is pre-registered and recorded in a storage device such as a hard disk or a storage device such as a DVD-ROM before starting the processing. Is calculated in

On the other hand, FIG. 2B shows a cross section of a wafer in which the thicknesses of the base films 211 and 212 which are oxide films are different. An oxide film formed by LPCVD (Low Pressure Chemical Vapor Deposition) is known to have low film thickness reproducibility, and the reproducibility is said to be about 10%.

As described above, a problem occurs when the thicknesses of the oxide films 211 and 212 as the underlying films are different. Even when the remaining film amount of the polysilicon film to be processed is the same, if the film thicknesses of the base films 211 and 212 that are oxide films are different, as shown in FIG. The optical path difference between the light 223 reflected at the boundary and the other reflected lights 221 and 222 is different. In interference, since the maximum and minimum of the intensity of interference light is determined by this optical path difference, the value of the intensity of interference light differs even with the same polysilicon film 201 thickness, and the film thickness is determined based on the intensity of interference light. It becomes difficult to detect with high accuracy.

In FIG. 3, in each case where the thickness of the base film is 40 nm and 80 nm, the differential value of the intensity with the wavelength of the interference light from the polysilicon film as a parameter with respect to the change in the remaining film thickness of the polysilicon film. A pattern (differential waveform pattern) in which the change is represented by the magnitude of the value is shown. FIG. 3A shows a change in the intensity value of interference light at a wavelength of 400 nm and a differential waveform pattern in a wavelength range of 250 nm to 850 nm when the base film thickness is 40 nm. FIG. 3B shows a change in the intensity value of interference light at a wavelength of 400 nm and a differential waveform pattern in the wavelength range of 250 nm to 850 nm when the base film thickness is 80 nm.

In each figure of the differential waveform pattern, the wavelength [nm] is plotted on the vertical axis and the remaining film thickness [nm] is plotted on the horizontal axis (which can be considered to correspond to the time or time after the start of processing). These figures are graphs showing the relationship between the value of the intensity of the interference light and the thickness of the underlying film in the film structure shown in FIG.

As shown in FIG. 3, when the thickness value of the base oxide film is different, the change in the intensity of the interference light is different. The minimum value of the intensity of the interference light is different in the remaining thickness of the polysilicon film in wafers having different thickness values of the base oxide film. This means that the determination accuracy deteriorates depending on the film thickness value of the base film oxide film for the apparatus that performs the remaining film thickness determination using optical interference.

In this embodiment, the thickness of the underlying oxide film 202 is set under the same conditions as those for etching a film structure including a mask layer on an actual wafer subjected to a processing step for mass production of semiconductor devices. In the case where a plurality of film structures having different values and similar to other structures are approximated to be equivalent or similar are etched using a polysilicon film layer disposed above the oxide film 202 and measuring the etching amount as a symmetric process. A differential waveform database including a differential pattern of intensity with the wavelength of interference light obtained from the polysilicon film as a parameter is stored and held in the differential waveform pattern database 16. Then, when processing the actual film structure on the wafer for mass production, the data stored in these databases is combined as a basic database to create new pattern data or its database, and the pattern data is Even when the thickness of the underlying oxide film 202 varies, the thickness of the polysilicon film 201 to be processed above the thickness of the underlying oxide film 202 can be detected by detecting the thickness of the film layer to be processed in the film structure. Alternatively, the end point can be accurately determined.

Hereinafter, in this embodiment, a configuration for calculating a differential waveform for thickness detection by combining pattern data stored in a differential waveform database corresponding to each of oxide films 211 and 212 having different thicknesses as basic data. Will be explained. In the differential waveform comparator 15, intensity differentiation using the wavelength of interference light from the film to be processed as a parameter for a plurality of film structures having different thicknesses of three or more base oxide films stored in the differential waveform database 16. The waveform data pattern DBi data value is compared with the actual pattern of the differential waveform data obtained during processing of the wafer 4 for a product for manufacturing a semiconductor device, and the minimum residual σi and the minimum data are obtained. A differential waveform pattern DBi is obtained.

In this embodiment, the residual uses the square error magnitude of each time series data value as shown below. The selector 18 selects two patterns in order from the smallest residual among the residuals σi.

The database creator 19 creates a composite pattern database DB with a composite coefficient α according to the following equation (4). Here, (alpha) can take the numerical value of 0-1.

BD = α (t) × DBj + (1−α) × DBk (4)

Next, the pattern matching comparator 20 compares the synthesized pattern database with the actual pattern. The calculator 21 selects a synthesis coefficient α that minimizes the residual σ by changing the value of the synthesis coefficient α in the range of 0 to 1 so that the residual σ becomes smaller.

Using the composite pattern database that minimizes the residual σ obtained when selecting this composite coefficient, the remaining film thickness of the polysilicon film at the present time (any time) during processing is calculated as the instantaneous film thickness, Data of this value is stored in the remaining film thickness time series data recorder 22. In the regression analyzer 23, the remaining film thickness (instantaneous film thickness) at the present time and a plurality of past times recorded in the remaining film thickness time series data recorder 22 is used, and the present remaining film thickness is obtained by regression calculation. Is calculated as the calculated film thickness.

The remaining film thickness as a result calculated by this regression calculation is transmitted to the end point determination unit 24, and the end point determination unit 24 compares the preset target remaining thickness value with the current remaining film thickness (calculation) to obtain the target It is determined whether the remaining film thickness value is equal to or less than the current remaining film thickness (calculation). If it is determined that it is below the target, it is determined that the etching amount of the film to be processed has reached a predetermined value, and a command to end the etching process is transmitted to the plasma processing apparatus 1. Further, the result of the determination is transmitted to the display unit 25, and the result is displayed on the display unit 25 having a liquid crystal or a CRT and notified to the user. The display 26 is also notified of information on the operation of the plasma processing apparatus 1, abnormalities during operation, and operational errors.

Next, a procedure for obtaining the etching amount of the film to be processed when the etching amount detection device 9 of FIG. 1 performs the etching process will be described with reference to the flowchart of FIG. FIG. 4 is a flowchart showing a flow of an operation for detecting the etching amount of the plasma processing apparatus according to the embodiment shown in FIG. The flow of the operation of the etching amount detection device 9 is mainly shown.

In the present embodiment, prior to the processing of the wafer 4, the target remaining film thickness value of the polysilicon film 201 which is the film to be processed and the pattern data stored in the differential waveform pattern database 16 used for the detection or determination thereof. Setting is performed (step 300). As the pattern data selected in the three or more differential waveform pattern databases, three or more patterns having different thicknesses of the underlying oxide film 202 are selected and set. Further, the target film thickness of the polysilicon film 210 to be processed is set and stored in the storage device in the etching amount detection device 9.

Next, processing of the wafer 4 is started in the vacuum processing chamber 2, and sampling of interference light from the surface of the wafer 4 obtained during processing (for example, every 0.1 to 0.5 seconds) is started (step 301). ). At this time, a sampling start command is issued with the start of the etching process. The intensity of multi-wavelength interference light from the film layer to be processed, which changes according to the etching of the film structure on the wafer that progresses with the change in time after the start, is the amount of etching at each time after the process starts. The light is transmitted to the spectroscope 10 of the detection device 9 and is detected and output as a light detection signal having a voltage corresponding to the intensity of light for each predetermined frequency.

For example, the light detection signal of the processing spectrometer 10 that has detected the interference light from inside the vacuum processing chamber 2 at an arbitrary time t after the start of processing is converted into a digital signal and used as a data signal associated with the arbitrary time t. A sampling signal yij is obtained. Next, the multi-wavelength output signal yij from the spectroscope 10 is smoothed by the first-stage digital filter circuit 12, and time-series data Yij at an arbitrary time is calculated (step 302).

Next, the time series data Yij is transmitted to the differentiator 13, and the time series differential coefficient dij is calculated by the SG method (Savitzky-Golay method) (step 303). That is, the coefficient (primary or secondary) di of the signal waveform is detected by differential processing (SG method).

The derivative coefficient dij is transmitted to the second-stage digital filter circuit 14 to calculate smoothing derivative coefficient time series data Dij (P) (step 304). The obtained smoothed differential coefficient time series data Dij (P) is transmitted to the differential waveform comparator 15.

In the differential waveform comparator 15, three or more differential waveform pattern data stored in advance in the differential waveform pattern database 16 and the smoothed differential coefficient time series data Dij (P ) And a residual σi = √ (Σ (P−DBi) 2 / j) value is calculated and transmitted to the residual calculator 17. In the residual calculator 17, the two differential waveform pattern data DBj and DBk are selected in order from the one having the smallest residual σ value, and these are transmitted to the composite database creator 19. (Step 306).

In the synthesis database creator 19 of this embodiment, the received two differential waveform pattern data DBj and DBk are synthesized using a synthesis coefficient α (t) having a plurality of values between 0 and 1, and a synthesis database DB is created. (Step 307). Pattern matching between this synthesized database DB and actual pattern data, which is a differential waveform pattern obtained from the smoothed differential coefficient time series data P created in step 304, is performed using α (t) as a parameter.

Here, the synthesis coefficient α (t) having the smallest residual is obtained by the synthesis coefficient calculator 21 (step 308). The remaining film thickness corresponding to this composite pattern database is calculated as instantaneous film thickness data Zi at the arbitrary time (current time) t (step 309), and the remaining film thickness time system data string recorder 22 is calculated. Send and memorize.

Further, the regression analyzer 23 uses the instantaneous film thickness time series data Zi recorded in the remaining film thickness time series data recorder 22 and the instantaneous film thickness time series data Zi at a plurality of past times during processing. Thus, the current calculated film thickness value is calculated and stored in a storage means such as a RAM or ROM in the calculated film thickness time series data recorder in the etching amount detector 9 (not shown) (step 310). That is, the linear regression line Y = Xa · t + Xb (Y: amount of remaining film, t: etching time, Xa: absolute value of Xa is etching rate, Xb: initial film thickness) is obtained by calculation of the regression analyzer 23. The etching amount (or remaining film amount) at the current time is calculated from this regression line and stored in the storage device.

In step 309, if the result of the comparison shows that the residual between the actual pattern and the synthesized differential waveform pattern data is equal to or greater than a threshold value that divides a predetermined allowable range, the film thickness is determined. As an inappropriate data, the film thickness corresponding to the synthetic differential waveform pattern data which is the minimum residual is stored in the remaining film thickness time-series data recorder 22 as the instantaneous film thickness data Zi at the current time. You can keep it without memorizing. In step 310, the instantaneous film thickness data Zi at a time in the past processing from an arbitrary time t (for example, the sampling time immediately before the current time) or the above-mentioned regression calculation is used instead of the instantaneous film thickness Zi at the current time. You may perform the calculation in the analyzer 23. FIG.

Next, the calculated calculated film thickness value as the remaining film amount of the film to be processed is compared with a preset target remaining film thickness value (set in step 300) (step 311). In this step, if it is determined that the calculated film thickness value calculated in step 310 is equal to or less than the target remaining film thickness value, it is determined that the target has been reached, and the process proceeds to step 312 to complete the etching process. A signal to be transmitted is transmitted to the plasma processing apparatus 1 (step 312). Finally, the end of sampling is set.

If it is determined that it has not been reached, the process returns to step 302. When it is determined in step 311 that the target has been reached, a command may be transmitted to the plasma processing apparatus 1 so as to perform the etching process of the next step as well as the control to end the etching process. For example, when the overetching process with a reduced processing speed or the film to be etched is composed of a plurality of film layers, the operating conditions of the plasma processing apparatus 1 are changed to those suitable for the lower film layer. The processing may be performed.

FIG. 5 shows the effect of this embodiment. FIG. 5 is a graph showing the effect of the wafer etched in the embodiment shown in FIG.

This figure shows the results when a wafer having a base oxide film thickness of 45 nm to 77 nm (4 types, 4 each) is etched. The horizontal axis in FIG. 5 is the set target remaining film, and the vertical axis indicates the determined remaining film with respect to the target remaining film. Each of the base oxide films has a determination accuracy within ± 1 nm, indicating that a high-accuracy determination has been performed.

Further, as described above, since sufficient determination accuracy is satisfied and information on the thickness of the base oxide film of the etched wafer can be obtained, it can also be used for production control of the base oxide film thickness.

FIG. 6 is a longitudinal sectional view showing an outline of a configuration of a plasma processing apparatus according to a modification of the embodiment of the present invention. The plasma processing apparatus 61 of this example includes the vacuum vessel 2 and the depth monitor apparatus 9 as in the above embodiment.

The difference from the embodiment shown in FIG. 1 is that the differential waveform pattern database has three or more differential waveform databases 116 having different mask film thicknesses, and the depth of the remaining film thickness is changed to the time series data recorder 22. The time series data recorder 122 is provided. The other configuration is the same as that shown in FIG. 1 and has the same function.

FIG. 7 is a vertical cross-sectional view schematically showing the configuration of a film structure formed and arranged in advance on a wafer on which the modification shown in FIG. 6 performs processing. FIG. 7A schematically shows a film structure including a mask layer 1201 and a silicon layer 1202 immediately after the start of the etching process. FIG. 7B schematically shows a film structure including a mask layer 1207 and a silicon layer 1208 after the plasma processing in the plasma processing apparatus 1 of FIG.

When plasma emission 1203 is incident on the wafer FIG. 7A immediately after the start of the etching process, reflected light 1204 by the surface of the mask layer 1201, reflected light 1205 by the boundary between the mask layer 1201 and the silicon layer 1202, and the silicon layer Reflected light 1206 from the surface 1202 is generated.

Further, plasma emission 1203 is incident on the wafer in FIG. 7B during the etching process, reflected light 1210 by the surface of the mask layer 1207, reflected light 1211 by the boundary between the mask layer 1207 and the silicon layer 1208, and the silicon layer 1208. Reflected light 1212 is generated by the surface. In FIG. 7B, the step value 1213 is VS, the mask thickness 1214 is VM, and the depth value 1215 is VD.

Next, a procedure for obtaining the etching amount of the film to be processed when the etching amount detecting device 9 of FIG. 6 performs the etching process will be described with reference to the flowchart of FIG. FIG. 8 is a flowchart showing an operation flow for detecting the etching amount of the plasma processing apparatus according to the modification shown in FIG. This flowchart is symmetrical with respect to the processing when the wafer 4 having the mask structure 1201 shown in FIG. 7 and the silicon layer 1202 disposed below the mask layer 120 is formed on the surface in advance and is etched using plasma. The procedure for determining the depth of a groove or hole formed in the polysilicon layer 1202 which is a film layer using the mask layer 1201 as a mask, mainly shows the flow of the operation of the etching amount detection device 9. .

In this embodiment, prior to the processing of the wafer 4, when a film structure having a polysilicon layer 1202 that is a film layer symmetrical to the process and three or more mask layers having different film thicknesses is etched, the film is processed. The differential waveform pattern database 116 is set with each of the data of the differential value pattern (differential waveform pattern) of the intensity using the wavelength of the interference light obtained from the structure as a parameter (step 1301). Further, the value of the target depth of the polysilicon layer is stored and held in the storage device in the etching amount detection device 9.

Next, processing of the wafer 4 is started in the vacuum processing chamber 2, and sampling of interference light from the surface of the wafer 4 obtained during processing (for example, every 0.1 to 0.5 seconds) is started (step 1301). ). At this time, a sampling start command is issued with the start of the etching process. The intensity of multi-wavelength interference light from the film layer to be processed, which changes according to the etching of the film structure on the wafer that progresses with the change in time after the start, is the amount of etching at each time after the process starts. The light is transmitted to the spectroscope 10 of the detection device 9 and is detected and output as a light detection signal having a voltage corresponding to the intensity of light for each predetermined frequency.

For example, the light detection signal of the processing spectrometer 10 that has detected the interference light from inside the vacuum processing chamber 2 at an arbitrary time t after the start of processing is converted into a digital signal and used as a data signal associated with the arbitrary time t. A sampling signal yij is obtained. Next, the multi-wavelength output signal yij from the spectroscope 10 is smoothed by the first stage digital filter circuit 12, and time-series data Yij at an arbitrary time is calculated (step 1302).

Next, the time series data Yij is transmitted to the differentiator 13, and the time series differential coefficient dij is calculated by the SG method (Savitzky-Golay method) (step 1303). That is, the coefficient (primary or secondary) di of the signal waveform is detected by differential processing (SG method).

The differential coefficient dij is transmitted to the second-stage digital filter circuit 14 to calculate smoothing differential coefficient time series data Dij (P) (step 1304). The obtained smoothed differential coefficient time series data Dij (P) is transmitted to the differential waveform comparator 15.

In the differential waveform comparator 15, three or more differential waveform pattern data stored in advance in the differential waveform pattern database 16 and the smoothed differential coefficient time series data Dij (P ) And a residual σi = √ (Σ (P−DBi) 2 / j) value is calculated and transmitted to the residual calculator 17. In the residual calculator 17, the two differential waveform pattern data DBj and DBk are selected in order from the one having the smallest residual σ value, and these are transmitted to the composite database creator 19. (Step 1306).

In the synthesis database creator 19 of this embodiment, the received two differential waveform pattern data DBj and DBk are synthesized using a synthesis coefficient α (t) having a plurality of values between 0 and 1, and a synthesis database DB is created. (Step 1307). Pattern matching between this synthesized database DB and actual pattern data, which is a differential waveform pattern obtained from the smoothed differential coefficient time series data P created in step 304, is performed using α (t) as a parameter.

Here, the synthesis coefficient α (t) with the smallest residual is obtained by the synthesis coefficient calculator 21 (step 1308). The value of the etching depth of the polysilicon layer 1202 corresponding to this synthetic pattern database is calculated as the instantaneous depth data Zi at the arbitrary time (current time) t (step 1309), and the depth time series data recorder It transmits in 122 and memorizes it.

Further, using the instantaneous depth time series data Zi recorded in the depth time series data recorder 122 and the instantaneous depth time series data Zi at a plurality of past times being processed, the regression analyzer 23 uses the current time series data Zi. The calculated depth value is calculated and stored in a storage means such as a RAM or ROM in the calculated depth time series data recorder in the etching amount detector 9 (not shown) (step 1310). That is, the linear regression line Y = Xa · t + Xb (Y: amount of remaining film, t: etching time, Xa: absolute value of Xa is etching rate, Xb: initial film thickness) is obtained by calculation of the regression analyzer 23. The etching amount (or depth amount) at the current time is calculated from this regression line, and data indicating this is stored in the storage device.

In step 1309, if the result of the comparison shows that the residual between the actual pattern and the synthesized differential waveform pattern data is equal to or greater than a threshold value that divides a predetermined allowable range, data for determining the depth For example, the depth corresponding to the combined differential waveform pattern data that is the minimum residual is not stored in the depth time series data recorder 22 as the instantaneous depth data Zi at the current time. You can also leave In addition, in step 1310, the instantaneous depth data Zi at a time in the past from an arbitrary time t (for example, the sampling time immediately before the current time) or the above-mentioned regression calculation is used instead of the instantaneous depth data Zi at the current time. You may perform the calculation in the analyzer 23. FIG.

Next, the calculated depth value as the current depth of the film to be processed is compared with a preset target depth value (set in step 1300) (step 1311). In this step, if it is determined that the calculated film thickness value calculated in step 310 is equal to or less than the target remaining film thickness value, it is determined that the target has been reached, and the process proceeds to step 1312 to end the etching process. A signal to be transmitted is transmitted to the plasma processing apparatus 61 (step 1312). Finally, the end of sampling is set.

If it is determined that it has not reached, the process returns to step 1302. When it is determined in step 1311 that the target has been reached, a command may be transmitted to the plasma processing apparatus 1 so as to perform the etching process of the next step as well as the control to end the etching process. For example, over-etching processing with reduced processing speed, or when the film to be etched is composed of a plurality of film layers, the operating conditions of the plasma processing apparatus 61 are changed to those suitable for the amount of remaining film of the mask. Then, the processing may be performed.

FIG. 9 is a graph showing a differential waveform pattern obtained when the wafer having the film structure shown in FIG. 7 is etched using the plasma processing apparatus according to the modification shown in FIG. Each pattern of the three graphs in this figure is a differential waveform pattern in which the magnitude of the differential value of the intensity with the wavelength of the interference light obtained from the surface of the film structure as a parameter during processing of the film structure is represented by shading. It is a representation. In this figure, the vertical axis indicates the wavelength, and the horizontal axis indicates the time after the start of processing (this is the same value as the value of the remaining film thickness during processing or a value approximated to this).

FIG. 9A is a diagram showing a differential waveform pattern (theoretical differential waveform pattern) of intensity using the wavelength of interference light from the mask film calculated theoretically as a parameter. FIG. 9B shows an intensity differential waveform pattern (actual differential waveform pattern) using as a parameter the wavelength of interference light from the surface obtained when the wafer having the film structure shown in FIG. 7 is actually etched. Is shown.

In FIG. 9B, 1507 and 1508 indicate the waveform components related to the interference light from the step generated by the etching of silicon in the actual differential waveform pattern, and 1509 and 1510 indicate the actual differential waveform pattern. The component of the change in the intensity of the interference light generated when the remaining film of the mask film decreases with the progress of the etching process is shown. FIG. 9C shows data obtained by subtracting the data of the pattern of FIG. 9A from the data corresponding to the time and wavelength pairs of the pattern of FIG. 9B at a ratio corresponding to the aperture ratio of the wafer. The horizontal axis represents time and the vertical axis represents wavelength, and the remaining film thickness changes as the etching process proceeds (that is, the depth of the step changes). The pattern of the intensity differential waveform (actual step differential waveform pattern) using the wavelength of light as a parameter is shown.

The figure will be described taking the actual step interference waveform in FIG. 9C as an example. First, the definition formula of the optical path difference is expressed by the following formula (14).

2dn / cos θ = mλ (14)

(M = 0, 1, 2,..., That is, the maximum value is obtained when m is an integer. Refractive index n, incident angle θ, and film thickness d are assumed.)

Before the etching process, the optical path difference due to the step is the thickness of the mask film. As the etching process proceeds, the thickness of the film to be processed decreases, so that the optical path difference increases.

At this time, as can be seen from the equation (14), it can be seen that the optical path difference 2d having the maximum value depends on the wavelength (for simplicity, θ = 0), that is, the long wavelength compared with the wavelength period on the short wavelength side. Since the wavelength period on the side becomes longer, the positive differential value 1514, the differential value 1515 near zero, and the negative differential value 1516 as the wavelength increases as shown in FIG. You can see that it is going down.

In FIG. 9A showing the theoretical differential waveform pattern of the mask film, the mask thickness decreases as the etching process proceeds, contrary to the actual step differential waveform pattern 9 (c) of the film to be processed. That is, the optical path difference decreases. Therefore, as the wavelength becomes longer as shown in FIG. 9A of the theoretical differential waveform pattern of the mask film layer, the positive differential value 1504, the differential value 1505 near zero, and the negative differential value 1506 become higher right. It goes up.

The actual differential waveform pattern in FIG. 9B is a waveform obtained when the wafer having the film structure shown in FIG. 7 is actually etched, and the theoretical differential waveform pattern of the mask film layer shown in FIG. The actual step differential waveform pattern shown in FIG. Therefore, each data of the actual step differential waveform pattern of the film to be processed is obtained by subtracting or removing the data of the theoretical differential waveform pattern of the mask film layer from each data of the actual differential waveform pattern obtained from the entire film structure. Can be detected. Below, the structure which calculates | requires the theoretical differential waveform pattern of a mask film layer is demonstrated.

FIG. 10 shows the calculation of the theoretical differential waveform pattern of the interference light from the mask film layer, and subtraction of the corresponding data of the theoretical differential waveform pattern from the data of the actual differential waveform pattern of the interference light from the film structure. It is a flowchart which shows the flow of operation | movement which calculates an actual level | step difference differential waveform pattern.

After the start of the operation (step 1601), first, a test wafer having a film structure having the same configuration as that of the product wafer to be processed is etched, and an actual differential waveform pattern of interference light from the film structure is obtained ( Step 1602). Further, an initial mask film thickness, a final mask film thickness (at the end point of the process), and an etching process time t of a test wafer actually etched are obtained, and an etching rate is obtained from these data values. Rm is calculated (step 1604). Here, the etching rate Rm can be calculated by Rm = (initial mask film thickness−final mask film thickness) / t.

That is, the initial film thickness of the mask obtained before processing the wafer, the interference waveform data obtained during the etching process, and the final film thickness of the wafer obtained by measuring the processed wafer with an SEM are used. Thus, the etching rate (etching rate) can be obtained from the amount of etching of the mask when the etching process is performed and the etching process time t.

Next, a document describing physical property values of the layer to be treated, such as “Handbook of Optical Constants of Solids” (Edward D. Palic (Naval Research Laboratory Washington, DC), Academic Inc. 5) The value of the refractive index ni corresponding to the wavelength λi of the mask material is acquired. From the obtained λi and ni, Rm obtained in step 1604, and the initial mask film thickness, a theoretical interference waveform Im of the mask film layer of the test wafer is calculated (step 1604). Such a theoretical interference waveform Im can be obtained by using a conventionally known technique (for example, a method using an amplitude reflection coefficient of Fresnel). Step 1604 may be performed prior to step 1602.

Next, each data corresponding to the theoretical differential waveform pattern of the mask film layer of the film structure of the test wafer obtained in Step 1604 is subtracted from each data of the actual differential waveform pattern of the test wafer obtained in Step 1602. Thus, the data of the actual step differential waveform pattern is calculated (step 1605). When subtracting the theoretical differential waveform pattern of the mask film layer from the actual differential waveform pattern of the film structure, for example, using the aperture ratio of the test wafer from which the data of the real differential waveform pattern was acquired, the data of the theoretical differential waveform pattern to be subtracted Determine the percentage.

Furthermore, using λi, ni, and Rm obtained in step 1604, the wavelength of the intensity of interference light from a plurality of (three or more in this embodiment) mask film layers having different initial thickness values is used as a parameter. The differential waveform pattern (theoretical differential waveform pattern) of the intensity to be calculated is calculated (step 1606). Further, a differential waveform pattern DBi is calculated by superimposing each data of the actual step differential waveform pattern obtained in step 1605 and corresponding data of each theoretical differential waveform pattern from the mask film layers having a plurality of film thicknesses obtained in step 1606. Then, each data is stored and stored in the differential waveform pattern database 116 (step 1608). At this time, the data of each pattern DBi is stored in a storage device such as a ROM or a RAM, an external storage device such as a DVD-ROM or a hard disk, etc., arranged in the etching amount detection device 9.

In the configuration as described above, even if the base film thickness or the initial thickness of the mask film layer varies, it is possible to accurately determine the remaining film thickness and the depth, thereby improving the process yield. . Furthermore, since information on the thickness of the base film and the thickness of the mask film layer can be obtained with high accuracy, it can be used for production management of the base film thickness and the mask film thickness.

DESCRIPTION OF SYMBOLS 1 ... Plasma processing apparatus 2 ... Vacuum processing chamber 3 ... Plasma 4 ... Wafer 5 ... Sample stand 8 ... Photoreceiver 9 ... Etching amount detection apparatus 10 ... Spectrometer 12 ... First digital filter 13 ... Differentiator 14 ... Second digital filter 15 ... Differential waveform comparator 16 ... Differential waveform pattern database 17 ... Residual calculator 18 ... Database selector 19 ... Synthetic database creator 20 ... Pattern matching comparator 21 ... Synthetic coefficient calculator 22 ... Residual film thickness time series data Recorder 23 ... Regression analyzer 24 ... End point determination device 25 ... Display device 201 ... Polysilicon film 202 ... Base film 203 ... Substrate 211 ... Base film 212 ... Base film 116 ... Differential waveform pattern database 122 ... Depth time series data recording vessel.

Claims (8)

A plasma having a film structure formed in advance on the upper surface of a wafer placed in a processing chamber inside a vacuum vessel and including a film to be processed and a mask layer disposed above the plasma. A plasma processing method using and processing,
Data of an actual pattern having an intensity of a wavelength of interference light obtained from the film to be processed as a parameter during processing of the film structure on the arbitrary wafer, and the processing before the processing of the arbitrary wafer A plurality of patterns having an intensity with the wavelength of the interference light as a parameter with respect to the film thickness of the film to be processed of the film structure having the target film and the mask layer, each having a different thickness of the mask layer 3 Calculating an etching amount of the film to be processed at a time during processing of the arbitrary wafer using a result of comparing data of a detection pattern obtained by combining two of two or more patterns; and the etching And determining whether the film to be processed reaches the target of the process using an amount. The plasma processing method according to claim 1,
During the processing of the film structure of the arbitrary wafer, the detection pattern data generated using two of the three or more basic patterns in the order of the smallest difference from the actual pattern and the actual pattern A plasma processing method comprising a step of calculating the etching amount using a result of comparison with data. The plasma processing method according to claim 1 or 2,
An actual pattern composed of time-series data of differential values of intensity using the wavelength of interference light obtained from the film to be processed as a parameter during processing of the film structure on the arbitrary wafer; and the arbitrary wafer Before the process of the above, it is composed of time-series data of the differential value of the intensity with the wavelength of the interference light with respect to the film thickness of the film to be processed of the film structure having the film to be processed and the mask layer as a parameter The processing of the arbitrary wafer is performed using a result of comparing data of detection patterns obtained by synthesizing two of three or more patterns, each of which is a plurality of patterns having different mask layer thicknesses. Calculating the etching amount of the film to be processed at the time of the step. The plasma processing method according to claim 1 or 2,
The etching amount at the arbitrary time is calculated by using the calculated etching amount value at the arbitrary time and the etching amount value at the time before the arbitrary time during the processing stored in advance. A plasma processing method for calculating again and determining reaching the target of the processing using the etching amount detected again. A processing chamber disposed inside the vacuum chamber; and a sample stage disposed in the processing chamber on which the wafer is placed on an upper surface thereof, and a processing target included in a film structure formed in advance on the upper surface of the wafer. A plasma processing apparatus for processing a film using plasma formed in the processing chamber,
An actual pattern having an intensity with the wavelength of interference light obtained from the film to be processed as a parameter during the processing of the film structure on the arbitrary wafer, and the processing target in advance before the processing of the arbitrary wafer Three or more patterns of intensity having the wavelength of the interference light as a parameter with respect to the film thickness of the film to be processed of the film structure having the film and the mask layer, each having a different thickness of the mask layer A calculation configured to calculate the etching amount of the film to be processed at the time during the processing of the arbitrary wafer using the result of comparing the data of the detection pattern obtained by combining two of the patterns of And a determination device configured to determine the arrival of the processing target using the etching amount. The plasma processing apparatus according to claim 5,
The calculator calculates data of the detection pattern created using two of the three or more basic patterns in order of smallest difference from the actual pattern during the processing of the film structure of the arbitrary wafer. And a plasma processing apparatus configured to calculate the etching amount using a result of comparing the actual pattern data. The plasma processing method according to claim 5 or 6,
The calculator includes an actual pattern composed of time-series data of differential values of intensity having a parameter of a wavelength of interference light obtained from the film to be processed during processing of the film structure on an arbitrary wafer. The differential value of the intensity using the wavelength of the interference light as a parameter with respect to the film thickness of the film to be processed of the film structure having the film to be processed and the mask layer in advance before the processing of the arbitrary wafer. The detection pattern data composed of two or more of three or more patterns composed of time-series data, each of which has a different thickness of the mask layer, and the result of comparison with the above, A plasma processing apparatus configured to calculate an etching amount at a time during processing of an arbitrary wafer. The plasma processing method according to claim 5 or 6,
The calculator uses the calculated value of the etching amount related to the arbitrary time and the value of the etching amount related to the time before the arbitrary time during the processing stored in advance. A plasma processing apparatus configured to recalculate an etching amount at a time, and wherein the determination unit is configured to determine arrival of the processing target using the etching amount detected again.

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