TWI413178B - A plasma processing method and a plasma processing apparatus - Google Patents

Abstract

A plasma processing method and apparatus are provided to detect accurately an end point of plasma process by determining automatically a type of a substrate and selecting an end point detection set according to the determined type of the substrate. A correlation between wafer assortment data and optical data is previously calculated according to plural kinds of wafers. The correlation is utilized when the wafer is subjected to plasma, and wafer assortment data is calculated from the optical data obtained when the plasma is started(S221,S222). A kind of the wafer is determined on the basis of the calculated wafer assortment data(S223). End point detection set data corresponding to the determined type of the wafer is selected from each end point detection set data stored in a data memory unit(S224).

Description

Plasma processing method and plasma processing device

The present invention relates to a plasma processing method and a plasma processing apparatus which perform plasma processing on a substrate such as a semiconductor wafer or a liquid crystal substrate.

The processing using a plasma substrate (for example, etching treatment, film formation treatment, etc.) has been widely applied to a semiconductor manufacturing step or an LCD substrate manufacturing step. The plasma processing apparatus used for such a plasma treatment includes, for example, an upper electrode and a lower electrode which are disposed in parallel with each other in the processing chamber, and a substrate such as a semiconductor wafer (hereinafter also referred to as a wafer) In addition, high-frequency power is applied between the upper electrode and the lower electrode, and plasma of the processing gas is generated. For example, the patterned film is used to etch the film to be etched.

In such a plasma etching process, the end point of the process is detected based on the optical data acquired by performing the process. For example, it is known that an illuminating spectrum of a gas generated by etching is detected as optical data, and a time point at which a specific wavelength change is detected is known as an end point of etching. In addition, when the substrate is irradiated with light of a specific wavelength, interference light (interference wave) of reflected light reflected from the interface between the film to be etched and the surface of the reticle is detected as optical data. The amount of etching or the film thickness is calculated from the interference light, and the time at which the desired etching amount or film thickness is formed is detected as the end point of the etching (see, for example, Patent Documents 1 and 2). Patent Document 2 describes that two types of light having different wavelengths are irradiated to a wafer by a light source in consideration of the light transmittance of the mask, whereby the amount of etching can be calculated even in a mask having a high light transmittance.

[Patent Document 1] JP-A-2001-217227 (Patent Document 2) Japanese Patent Publication No. 2004-363367

In recent years, with the increase in the number of semiconductor devices, there has been an increase in plasma processing of wafers having different types (opening ratios) such as mask patterns in the same processing chamber.

However, when plasma processing is performed on such a wafer, the end point detection of the plasma processing is conventionally performed regardless of the type of the mask pattern. Therefore, even if the material type of the mask is the same, it may occur depending on the type of the mask pattern. The end point deviation was not able to accurately detect the end point, which was clearly confirmed by experiments by the inventors. That is, once the types of the mask patterns are different, the characteristics of the optical data obtained by the plasma processing may be different. Therefore, it is known that if the end point of the plasma processing is detected based on such optical data, it will be light. The end point deviation occurs in the type of the cover pattern, and the end point may not be accurately detected.

In this case, it is conceivable that the operator can perform the processing depending on the type of the mask pattern, that is, the method of detecting the end point of the plasma processing apparatus depending on the type of the wafer, but the processing is performed every time the wafer is processed. The type of wafer, each time the endpoint detection method is changed, not only takes time, but also the production capacity is reduced. This is not limited to the case where the types of the mask patterns are different, for example, the type of the material of the mask or the type of the film to be etched is different.

Accordingly, the present invention has been made in view of such a problem, and an object thereof is to provide an end point detection setting that automatically determines a type of a substrate and automatically selects a substrate type to be determined, thereby eliminating the need for a substrate. The plasma processing method for correct end point detection, etc.

In order to solve the above problems, a plasma processing method according to an aspect of the present invention applies high-frequency electric power to an electrode provided in a processing chamber, and generates a plasma of a processing gas, and the plasma is applied to the substrate by a specific method. A plasma processing method for processing, comprising: an analyzing step of determining a substrate type data set corresponding to a plurality of substrate types by multivariate analysis and an optical data detecting means when plasma processing the substrate a correlation relationship between the detected optical data; a determination step of calculating the optical data detected by the optical data detecting means at the time of starting the plasma processing of the substrate by using the correlation obtained by the analyzing step The substrate type data determines the type of the substrate based on the calculated substrate type data; and the selecting step is performed by the end point of the plasma processing detected in advance by the data memory means in association with each of the substrate types Setting data to select setting data corresponding to the substrate type determined in the above determining step; end point detection Step, which is performed based on the setting information based on said selecting step for detecting the end point of the selected plasma processing; and the end of the step, which is based on the above-described end-point detection step detects the end of the end plasma treatment.

Further, in order to solve the above problems, a plasma processing apparatus according to an aspect of the present invention applies high-frequency electric power to an electrode provided in a processing chamber, and generates plasma of a processing gas, and applies the plasma to the substrate. A plasma processing apparatus for specific processing is characterized by: an optical data detecting means for detecting optical data when the plasma is processed by the substrate; and a data memory means for memorizing: indicating a substrate type corresponding to the plurality of substrates And the correlation data between the set substrate type data and the optical data detected by the optical data detecting means, and the respective settings for detecting the end points of the plasma processing respectively associated with the respective substrate types The control unit is configured to calculate the substrate from the optical data detected by the optical data detecting means when the plasma processing is started by using the correlation data stored in the data memory means when the plasma processing substrate is processed in the processing chamber. The seed data is determined based on the calculated substrate type data, and is recorded in the data record Endpoint detection means for each set of data selected corresponding to the determined kind of the substrate to the other endpoint detection configuration data, the configuration data selected according to the end-point detection to detect the end point of the above-described plasma treatment.

According to the method or apparatus of the present invention, the type of the substrate is automatically determined when the plasma processing of the substrate is started, and the end point detection setting corresponding to the determined substrate type can be automatically selected. Thereby, the correct end point detection can be performed regardless of the type of the substrate.

Further, the optical data detecting means includes, for example, a light source that emits light on the substrate, and a light detecting means that detects spectral data of reflected light obtained by reflecting the light from the light source from the substrate.

When the types of the substrates are different, the characteristics of the spectral data of the reflected light obtained by the reflection from the substrate are all different. Therefore, for example, by using such spectral data, the type of the substrate can be determined.

Further, it is preferable that the optical data for determining the substrate type is spectral data detected by the optical data detecting means at a specific time point immediately after the plasma processing of the substrate. Thereby, the type of the substrate can be determined at an early stage after the start of the plasma treatment.

Further, the substrate type is distinguished by the type of the mask (for example, the type of the material of the mask or the type of the mask pattern) formed on the film to be processed to be subjected to the plasma treatment, and the end point detecting step in this case is, for example, processing. The substrate detects the film thickness of the film to be processed on the substrate by the spectral data detected by the optical data detecting means at a specific timing, and forms a specific film thickness with the detected film thickness. The point is the end point of the plasma treatment.

When the film thickness of the film to be processed on the substrate changes, the characteristics of the spectral data also change, so that the film thickness can be detected based on the spectral data. Thereby, according to the spectral data, not only the type of the substrate but also the film thickness of the film to be processed can be detected.

Further, each of the above-described setting materials is, for example, an end point detecting method or an end point detecting recipe (Recipe) suitable for each of the above-described types of substrates. Further, in the above analysis step, a part of least squares is used as the multivariate analysis described above.

Moreover, in order to solve the above-described problems, a plasma processing method according to another aspect of the present invention applies high-frequency electric power to an electrode provided in a processing chamber, and generates a plasma of a processing gas, and applies the plasma to the substrate. A plasma processing method according to a specific process, comprising: an analyzing step of determining, by multivariate analysis, a type corresponding to a type of a mask pattern formed on a processed film on the substrate; The correlation between the substrate type data set by the plurality of substrate types and the optical data detected by the optical data detecting means when the substrate is processed by the plasma; and the determining step is performed by using the correlation relationship obtained in the analyzing step. When starting the plasma processing of a substrate, the substrate type data is calculated from the optical data detected by the optical data detecting means, and the type of the substrate is determined based on the calculated substrate type data; and the selecting step is associated with each other Each of the above-mentioned types of substrates is stored in advance in the setting data of the end point of the plasma processing for detecting the end point of the plasma processing Selecting a setting data corresponding to the substrate type determined in the determining step; an end point detecting step of performing end point detection of the plasma processing based on the prescription setting data selected in the selecting step; and ending the step The plasma treatment is terminated at the end point detected by the above-described end point detecting step.

Further, the optical data detecting means includes, for example, a light source that emits light on the substrate, and a light detecting means that detects spectral data of reflected light obtained by reflecting the light from the light source from the substrate.

Further, the substrate type can be distinguished, for example, by an aperture ratio in a specific region of the photomask on the substrate.

In this case, the setting data of each of the above-mentioned places is a plurality of film thickness data indicating a correspondence relationship between the optical data and the film thickness, and the selecting step may select a film thickness data corresponding to the substrate type determined in the determining step, the end point The detecting step can detect the processed film on the substrate by using the film thickness data selected in the selecting step from the spectral data detected by the optical data detecting means at a specific timing while processing the substrate. The film thickness is the time point at which the film thickness is formed to a specific film thickness as the end point of the plasma treatment.

Once the type of the mask pattern on such a substrate (for example, the aperture ratio in a specific region) is different, the characteristics of the spectral data reflected from the substrate are also changed. Therefore, when the end point detection is performed using such spectral data, the end point detection corresponding to the type of the mask pattern is performed, whereby the end point detection can be accurately performed regardless of the type of the mask pattern.

In order to solve the above problems, a plasma processing method according to another aspect of the present invention applies high-frequency electric power to an electrode provided in a processing chamber, generates plasma of a processing gas, and applies a specificity to the substrate by the plasma. A plasma processing method for processing, comprising: an analyzing step of determining, by multivariate analysis, a plurality of numbers corresponding to material types of masks formed on a film to be processed on the substrate The relationship between the substrate type data set by the substrate type and the optical data detected by the optical data detecting means when the plasma is processed by the plasma; and the determining step of using the correlation obtained in the analyzing step to start a certain In the plasma processing of the substrate, the substrate type data is calculated from the optical data detected by the optical data detecting means, and the type of the substrate is determined based on the calculated substrate type data; and the selecting step is associated with each of the above The detection method setting data of the end point of the plasma processing for detecting the substrate type and pre-memorizing the data memory means Selecting a data corresponding to the substrate type determined in the determining step; an end point detecting step of performing the end point detection of the plasma processing based on each of the detecting method setting data selected in the selecting step; and ending the step The plasma treatment is terminated at the end point detected by the above-mentioned end point detecting step.

Further, the optical data detecting means includes, for example, a light source that emits light on the substrate, and a light detecting means that detects spectral data of reflected light obtained by reflecting the light from the light source from the substrate.

Further, the substrate type may be distinguished by, for example, a hard mask or a photoresist mask in accordance with the mask on the substrate.

In this case, the detection method setting method for the substrate on which the hard mask is formed is: the substrate from the substrate obtained by irradiating the substrate with a single illumination light having a wavelength reflected from the light source reflected on the hard mask. The spectral data of the reflected light is used to detect the film thickness of the film to be processed, and the setting data of the detection method for detecting the end point based on the detected film thickness is performed, and the method for detecting the substrate on which the photoresist mask is formed is determined. The setting data is configured to detect the processed data based on spectral data of the reflected light from the substrate obtained by irradiating the substrate with the irradiation light of the wavelength of the light-receiving mask and the reflected light. The film thickness of the film is set as the setting data of the detection method for detecting the end point based on the detected film thickness.

Once the material type of the mask on the substrate (for example, the transmittance of the mask) is different, the characteristics of the spectral data reflected from the substrate also change. Therefore, when the end point detection is performed using such spectral data, the end point detection can be performed accurately by performing the end point detection of the material type corresponding to the mask, regardless of the type of the material of the mask.

As described above, according to the present invention, the type of the substrate is automatically determined, and the end point detection setting corresponding to the determined substrate type can be automatically selected. Thereby, end point detection corresponding to the substrate type can be performed.

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

In the present specification and the drawings, constituent elements that have substantially the same functional configuration are denoted by the same reference numerals and the description thereof will not be repeated.

(First embodiment)

First, the schematic configuration of the plasma processing apparatus according to the first embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a cross-sectional view showing a configuration example of a plasma processing apparatus of the embodiment. Here, an example of the plasma processing apparatus will be described with a parallel plate type plasma etching apparatus.

The plasma processing apparatus 100 is provided with a processing chamber 102 having a processing container which is, for example, a cylindrical shape in which aluminum is anodized (aluminum-treated). This processing chamber 102 is grounded. A substantially cylindrical base support table 104 on which the wafer W is placed is placed on the bottom of the processing chamber 102 via an insulating plate 103 made of ceramic or the like. A susceptor 105 constituting a lower electrode is provided on the susceptor support base 104. A high pass filter (HPF) 106 is connected to this susceptor 105.

A temperature adjustment medium chamber 107 is provided inside the susceptor support 104. Then, the temperature adjustment medium is introduced through the introduction pipe 108, circulated through the temperature adjustment medium chamber 107, and discharged from the discharge pipe 109. The susceptor 105 can be controlled to a desired temperature by such a temperature-regulating cycle of the medium.

The susceptor 105 has a disk shape in which a central portion of the upper side is formed in a convex shape, and an electrostatic chuck 111 having a shape substantially the same as that of the wafer W is provided thereon. The electrostatic chuck 111 is formed between the insulating material and interposed between the electrodes 112. The electrostatic chuck 111 is, for example, applied with a DC power source 113 connected to the electrode 112, for example, to apply a DC voltage of 1.5 kV. Thereby, the wafer W is electrostatically attracted to the electrostatic chuck 111.

Further, in the insulating plate 103, the susceptor support 104, the susceptor 105, and the electrostatic chuck 111 form a gas passage for supplying a heat transfer medium (for example, a back gas such as He gas) to the back surface of the wafer W of the object to be processed. 114. The heat transfer between the susceptor 105 and the wafer W is performed by the heat transfer medium to maintain the wafer W at a specific temperature.

An annular focus ring 115 is disposed on the peripheral edge portion of the upper end of the susceptor 105 so as to be able to surround the wafer W placed on the electrostatic chuck 111. The focus ring 115 is made of an insulating material such as ceramic or quartz or a conductive material. By the configuration of the focus ring 115, the uniformity of etching can be improved.

Further, an upper electrode 121 is provided in parallel with the susceptor 105 above the susceptor 105. The upper electrode 121 is supported inside the processing chamber 102 via an insulating material 122. The upper electrode 121 is composed of an electrode plate 124 that has a plurality of discharge holes 123 that face the surface of the susceptor 105, and an electrode support 125 that supports the electrode plate 124. The electrode plate 124 is made of, for example, quartz, and the electrode support 125 is made of, for example, a conductive material such as aluminum whose surface is treated with alumite. In addition, the interval between the susceptor 105 and the upper electrode 121 can be adjusted.

A gas introduction port 126 is provided at the center of the electrode support 125 of the upper electrode 121. The gas supply port 126 is connected to the gas supply port 126. Further, the gas supply pipe 127 is connected to the process gas supply source 130 via the valve 128 and the mass flow controller 129.

The gas supply source 130 can be processed thereby to supply an etching gas for plasma etching. Further, in FIG. 1, only one processing gas supply system including the gas supply pipe 127, the valve 128, the mass flow controller 129, and the processing gas supply source 130 is shown, but the actual plasma processing device 100 is There are a plurality of processing gas supply systems. For example, etching gases such as CF ₄ , O ₂ , N ₂ , CHF ₃ and the like are separately controlled by independent flow rates and supplied to the processing chamber 102.

An exhaust pipe 131 is connected to the bottom of the processing chamber 102, and the exhaust pipe 131 is connected to the exhaust device 135. The exhaust device 135 includes a vacuum pump such as a turbo molecular pump, and adjusts the inside of the processing chamber 102 to a specific reduced pressure environment (for example, 0.67 Pa or less). Further, a gate valve 132 is provided on the side wall of the processing chamber 102. By opening the gate valve 132, the loading of the wafer W into the processing chamber 102 and the removal of the wafer W from the processing chamber 102 can be performed. Further, the transfer of the wafer W is, for example, using a wafer cassette.

The first high-frequency power source 140 is connected to the upper electrode 121, and the first integrator 141 is interposed in the power supply line. Further, a low pass filter (LPF) 142 is connected to the upper electrode 121. The first high frequency power supply 140 can output electric power having a frequency in the range of 50 to 150 MHz. By applying such a high frequency of electric power to the upper electrode 121, a plasma having a better dissociation state and a high density can be formed in the processing chamber 102, and plasma treatment under a low pressure condition can be formed in comparison with the prior art. The frequency of the output power of the first high-frequency power source 140 is preferably 50 to 80 MHz, and is typically adjusted to a frequency of 60 MHz or the vicinity thereof as shown.

The second high-frequency power source 150 is connected to the susceptor 105 as the lower electrode, and the second integrator 151 is interposed in the power supply line. The second high frequency power supply 150 can output power having a frequency in the range of several hundred kHz to ten tens of MHz. By applying power of such a range of frequencies to the susceptor 105, it is possible to impart an appropriate ion action to the wafer W of the object to be processed without causing damage. The frequency of the output power of the second high-frequency power source 150 is typically adjusted to 2 MHz or 13.56 MHz as shown.

(Configuration example of optical data detecting means)

The plasma processing apparatus 100 of the present embodiment is an optical measuring instrument including an optical data detecting means for detecting optical data. 2 is a block diagram showing a configuration example of an optical measuring instrument. The optical measuring device 200 here is an optical material such as spectral data such as reflected light that is reflected from the wafer when the light is irradiated on the wafer.

Specifically, as shown in FIG. 2, the optical measuring device 200 includes a collecting lens 202, an optical fiber 204, a light source 206, and a polychromator (light detecting unit) 208. The light source 206 is composed of, for example, a xenon lamp, a tungsten lamp, various types of electric radiation, or a combination thereof, and can emit light of a specific wavelength or a plurality of lights having different wavelengths.

A cylindrical observation portion 160 is provided in the upper electrode 121. A window portion 162 made of, for example, quartz glass is provided at the upper end of the observation portion 160. The observation unit 160 is optically connected to the light source 206 and the polychromator 208 by the collecting lens 202 and the optical fiber 204 provided to the window portion 162.

The light emitted from the light source 206 is irradiated to the wafer W via the optical fiber 204 and the observation unit 160, respectively. If the light from the light source 206 is reflected at a plurality of heights of the wafer W, the plurality of reflected lights interfere with each other, and the reflected light (interference light) is incident on the polychromator 208 via the optical fiber 204 to be detected. Out.

For example, as shown in FIG. 3, an etched film E as a film to be processed and a mask M having a specific opening for forming holes in the film E to be etched are formed on the wafer W. In this case, once the wafer W is etched, only the exposed portion of the etching film E (the portion of the opening of the mask M) is gradually etched to form the holes H. At this time, once the light La from the light source 206 is irradiated onto the wafer W, it is reflected on the interface between the mask M and the film E to be etched, and is reflected on the exposed surface of the film E to be etched (the bottom surface of the hole H). The reflected lights La1, La2 interfere with each other, and the reflected light (interference light) can be detected by the polychromator 208.

As described above, the reflected light (interference light) detected by the polychromator 208 is input to the control unit 300 as optical data (for example, spectral data). The control unit 300 uses the optical data for the determination of the wafer type, detects the film thickness of the film to be formed or the like formed on the wafer, and detects the end point of the etching. The specific processing of the control unit 300 will be described in detail later.

In addition, the optical data may also be spectral data obtained from the plasma when the plasma is processed by the plasma. Thereby, the film thickness of the film to be etched can be detected by the spectral data of the plasma light emission. In this case, the optical meter's spectral data on plasma luminescence can also be detected.

(Configuration example of control unit)

Here, a configuration example of the above-described control unit will be described with reference to the drawings. 4 is a block diagram showing a configuration example of a control unit of the plasma processing apparatus.

As shown in FIG. 4, the control unit 300 includes a program memory means 310 for storing a program for performing various processes, and an arithmetic means 320 for controlling each unit based on a program stored in the program memory means 310 to perform processing; The data storage means 330 stores the result data obtained by the processing of the setting data or the program set when the various processes are executed, and the input/output means 340 for inputting the optical data from the optical measuring device 200, etc. The input and output of various materials; and various controllers 350 for controlling the various parts of the plasma processing apparatus 100.

The arithmetic means 320 can be constituted by, for example, a microprocessor or the like. The program memory means 310 and the data memory means 320 can each be constituted by a memory medium such as a memory or a hard disk.

The program memory means 310, in addition to the multivariate analysis program for obtaining the correlation between the wafer type data and the optical data by multivariate analysis such as the partial least square method, is also stored for use in the wafer. A program for plasma processing such as etching is used to execute various processing programs such as end point detection processing for detecting the end point of plasma processing in accordance with the wafer type.

The data memory means 330 is a correlation data 334 for storing the correlation information for obtaining the correlation between the wafer type data and the optical data, and the correlation data 334 for analyzing the result of the multivariate analysis using the analysis data 332 for the wafer type. The end point detection selection data 336 and the like of the end point detection setting data are selected.

The analysis material 332 is, for example, a wafer for analysis (for example, W1 to W6), a wafer type (for example, A, B), and a wafer type data set for each wafer type as shown in FIG. 5 (for example, 0, 1), and the optical data (such as spectral data) obtained when processing the wafer. Further, the configuration of the analysis material 332 is not limited to that shown in FIG. 5.

Here, the type of the wafer is distinguished by, for example, the type of the mask (for example, the type of the material of the mask and the type of the mask pattern) formed on the film to be etched. Further, the types of wafers may be classified according to the type of film of the film to be etched or the like, or may be distinguished according to two or more combinations of the types.

In the case where the wafer type is distinguished by the type of the mask pattern, for example, a mask pattern having a different aperture ratio in a specific region of the mask can be used. Further, the type of the wafer is distinguished by the type of the film to be etched, and for example, an oxide film, a polysilicon film, or the like can be used.

Further, in the case of distinguishing the types of wafers by the type of the material of the mask, for example, a hard mask and a photoresist mask may be used. The hard mask is made of, for example, SiO ₂ , Si ₃ N ₄ or the like, and the photoresist mask is made of, for example, a photosensitive material such as Krf, Arf, i-line, etc., and thus can be subdivided according to the materials of the masks. .

In such a wafer in which the type of the mask or the film to be etched is different, since the spectral characteristics reflected from the wafers are different, if such a spectrum is used as the end point detection as it is, there is The end point detected at the time will be biased. Therefore, in the present invention, the wafer type is determined as will be described later, and appropriate end point detection is performed depending on the wafer type. For example, in the case shown in FIG. 5, the wafer type is two types, and the respective wafer types are A and B.

The wafers W1 to W6 for analysis are wafers of known wafer types, and different values are assigned for each wafer type (for example, A, B). This value can be freely assigned, but here it is, for example, a positive integer assigned sequentially from 0. It can also be assigned from 1 onwards. The data of the values assigned according to the wafer type is referred to as wafer type data. For example, the wafer type shown in FIG. 5 is two types (species A and B), so the wafer type data corresponding to each wafer type is 0, 1.

The optical data referred to here is, for example, data (spectral data) of the spectral intensity of a specific wavelength region (wavelength band) of the reflected light from the wafer obtained by irradiating light on the wafer. Specifically, the spectral intensity of a wavelength of 1 to K per specific interval in a specific wavelength region is used. For example, the spectral intensity of 153 wavelengths at 5 nm intervals in the range of 195 to 955 nm. The spectral intensity of each wavelength is, for example, when etching one wafer, using the latter from the etching for a few seconds (for example, 3 seconds).

The end point detection selection data 336 is composed of, for example, a wafer type (for example, A, B) and end point detection setting data (for example, Da, Db) associated with each wafer type as shown in FIG. The endpoint detection setting data is the setting data necessary for the endpoint detection. As the end point detection setting data, for example, an end point detecting method, an end point detecting prescription, and a combination of the methods and the prescription may be mentioned.

In this way, the optimum end point detection setting data is determined in accordance with the wafer type, and is stored as the end point detection selection data 336 in advance, and the end point detection setting data corresponding to the wafer type is selected when discriminating the wafer type as described later. Optimal end point detection corresponding to each wafer type is performed.

The end point detecting method includes, for example, a method of detecting an end point based on a film thickness detected by spectral data of reflected light reflected from a wafer when the wafer is irradiated with light, and spectral data according to plasma luminescence. Change to detect the end point, etc. The end point detection prescription includes, for example, a wavelength region (wavelength band) of spectral data used for end point detection, and a type of light source that is irradiated onto the wafer.

Further, it is also possible to perform end point detection based on the film thickness detected from the spectral data obtained when the wafer is processed, using film thickness data indicating the relationship between the film thickness of the complex number and the spectral data to be reflected from the wafer at that time. At the time, the film thickness data is memorized according to the wafer type as the end point detection prescription, and the film thickness data is selected according to the wafer type.

In the control unit 300, the correlation data (model) of the wafer type data and the optical data used for determining the wafer type is prepared in advance by the analysis processing using the multivariate analysis. Specifically, a multivariate analysis program is used to obtain an optical data as a explanatory variable (describe variable), and a wafer type data is used as a relational expression (1-1) under the explanatory variable (destination variable, purpose variable) ( Predictive equations such as regression, mode). In the following regression equation (1-1), X is intended to indicate the rank of the variable, and Y is the rank of the variable to be explained. and. B is a regression matrix composed of coefficients (quantities) of explanatory variables, and E is a residual matrix.

Y=BX+E.........(1-1)

For example, if X is expressed using the spectral data shown in FIG. 5, the general formula (1-2) will be formed. If Y is used to represent Y, the following formula will be formed. (1-3) is generally shown. Further, in the following formula (1-2), for example, λ _a11 to λ _a1K are spectral data obtained when processing a wafer of wafer type Ya, and correspond to values of spectral intensities of respective wavelengths of 1 to K.

In the present embodiment, when the above (1-1) is obtained, for example, the PLS (Partial Least Squares) method described in "JOURNALOF CHEMOMETRICS, VOL. 2 (PP211-228) (1998)" is used. In this PLS method, even if there are a plurality of explanatory variables and explanatory variables in the ranks X and Y, respectively, as long as there are a few measured values, the relationship between X and Y can be obtained. Even if the relationship is obtained with a small measured value, it is still stable and reliable, and this is also a feature of the PLS method.

In the program memory means 310, a multivariate analysis program, for example, a program for the PLS method, is stored, and the wafer type data and the optical data are processed by the calculation means 320 in accordance with the program of the program, and the regression equation (1-1) is obtained. The result is stored in the data memory means 330 as the correlation data. Therefore, it is only required to take the above regression equation (1-1), and then the optical data can be applied to the rank X as an explanatory variable, thereby calculating the wafer type data. And the calculated wafer type data is highly reliable.

For example, for the X ^T Y row and column, the i-th principal component corresponding to the i-th eigenvalue is represented by t _i . If the rank X is the point t _i and the vector p _i using the i-th principal component, it is expressed by the following formula (1-4), and if the rank Y is the point t _i and the vector c using the i-th principal component _i is represented by the following formula (1-5). Further, in the following formula (1-4), in the formula (1-5), X _i+1 , Y _i+1 are the residual rows of X and Y, and X ^T is the transposed row of the row X. Hereinafter, the index T means the transposed rank.

X=t ₁ p ₁ +t ₂ p ₂ +t ₃ p ₃ +. . +t _i p _i +X _i+1 .........(1-4)

Y=t ₁ c ₁ +t ₂ c ₂ +t ₃ c ₃ +. . +t _i c _i +Y _i+1 .........(1-5)

Further, the PLS method according to the first embodiment calculates a plurality of eigenvalues and respective eigenvectors when the equations (1-4) and (1-5) are correlated with a small amount of calculation.

The PLS method is implemented by the following procedure. First, in the first stage, the centering and scaling operations of the rows and columns X and Y are performed. Moreover, i=1, X ₁ =X, and Y ₁ =Y are set. Further, the first column of the rank Y ₁ is set as u ₁ . Here, centering is an operation of subtracting the average value of each row from each value of each row, and the so-called scaling is an operation (processing) of dividing the standard deviation of each row by each value of each row.

In the second stage, after obtaining w _i =X _i ^T u _i /(u _i ^T u _i ), the determinant of w _i is normalized, and t _i =X _i w _{i is obtained} . Moreover, the row Y is also processed by the same, and after c _i =Y _i ^T t _i /(t _i ^T t _i ) is obtained, the determinant of c _i is normalized, and u _i =Y _i c is obtained. _i /(c _i ^T c _i ).

In the third stage, the X load amount p _i =X _i ^T t _i /(t _i ^T t _i ), and the Y load amount q _i =Y _i ^T u _i /(u _i ^T u _i ) are obtained. Then, b _i = u _i ^T t _i / (t _i ^T t _i ) which returns u to t is obtained. Next, the residual rank X _i =X _i -t _i p _i ^T and the residual rank Y _i =Y _i -b _i t _i c _i ^{T are obtained} . Then, increment i, set i=i+1, and repeat the process from the second stage. The series of processes are repeated until the specific stop condition is met according to the PLS method, or the residual rank X _{i+1 is} concatenated to zero, and the maximum eigenvalue of the residual rank and its eigenvector are obtained.

The PLS method is a stop condition of the residual rank X _i+1 or a fast convergence to zero, and only repeats the calculation 10 times, and the residual rank will be converged to the stop condition or zero. Generally, the calculation is repeated 4 to 5 times, and the residual rank will be converged to the stop condition or zero. The first principal component of the X ^T Y row and column can be obtained by using the maximum eigenvalue obtained by the calculation process and its eigenvector, and the maximum correlation between the X row column and the Y row column can be known.

(Operation of plasma processing device)

Next, the operation of the plasma processing apparatus 100 will be described. In the present embodiment, first, the wafer for plasma etching analysis (test wafer) is used to obtain the analysis material 332, and the analysis data 332 is used for multivariate analysis to obtain the wafer type. Correlation between data and optical data (regression (1-1)). Then, wafer processing (for example, processing of a wafer for a product) accompanying wafer type determination is performed. At this stage, optical data at a specific time point after the start of wafer processing is detected, and the optical data is applied to the regression equation (1-1), and the wafer type data is calculated and determined from the calculated wafer type data. Wafer type.

Here, a specific example of the plasma etching process of the analysis wafer or the other wafer (for example, the product wafer) performed by the plasma processing apparatus 100 will be described. Here, the plasma etching treatment in the case where the film to be etched E shown in FIG. 3, that is, the polysilicon film and the mask M are formed on the wafer.

First, an etching process (breakthrough etching step) of removing a natural oxide film on the exposed surface of the etching film E is performed on the wafer on the susceptor 105 by using a mixed gas containing at least CF ₄ and O ₂ .

For the conditions at the time of the etching, for example, the pressure in the processing chamber 102 is 10 mTorr, the interval between the upper electrode 121 and the susceptor 105 is 140 mm, and the gas flow ratio of CF ₄ /O _{2 (} the gas flow rate of CF ₄ / O _{2 )} The gas flow rate is 134 sccm / 26 sccm. Further, in order to adsorb the wafer, the voltage applied to the electrostatic chuck 110 was 2.5 kV, and the back surface cooling gas pressure of the wafer W was 3 mTorr at the center and the edge. Further, the set temperature in the processing chamber 102 was 75 ° C for the lower electrode, 80 ° C for the upper electrode, and 60 ° C for the side wall portion.

In the breakthrough etching step, high-frequency high-frequency power is applied to the susceptor 105 and the upper electrode 121, respectively. For example, the high frequency power applied to the upper electrode 121 is 650 W, and the high frequency power applied to the susceptor 105 is 220 W. Thereby, the natural oxide film on the exposed surface of the film E to be etched is removed.

Next, a main etching step of etching the film E to be processed in the depth direction is performed in the opening of the mask M. In this main etching step, a mixed gas containing at least HBr and O ₂ is used as a processing gas, and the film E to be etched is removed in the depth direction at the opening of the mask M. The film E to be etched is, for example, etched to a depth of 85% of the original film thickness.

For the conditions at the time of main etching, for example, the pressure in the processing chamber 102 is 20 mTorr, the interval between the upper electrode 121 and the susceptor 105 is 140 mm, and the gas flow ratio of HBr/O ₂ (gas flow rate of HBr / gas of O ₂ ) The flow rate is 400 sccm / 1 sccm. Further, in order to adsorb the wafer, the voltage applied to the electrostatic chuck 110 was 2.5 kV, and the back surface cooling gas pressure of the wafer W was 3 mTorr at the center and the edge. Further, the set temperature in the processing chamber 102 was 75 ° C for the lower electrode, 80 ° C for the upper electrode, and 60 ° C for the side wall portion.

In the main etching step, high-frequency power is applied to the susceptor 105 and the upper electrode 121, respectively. For example, the high frequency power applied to the upper electrode 121 is 200 W, and the high frequency power applied to the susceptor 105 is 100 W. Thereby, the film to be etched E exposed to the opening of the mask M is selectively etched away, and the hole H is formed in the film E to be etched.

In the plasma etching process, the optical meter 200 detects reflected light obtained by reflection from the wafer when irradiated with light from the light source as optical data (for example, spectral data).

For example, the analysis wafer is prepared by preparing the wafer for analysis of all wafer types that can be processed in the processing chamber 102, and the plasma etching process is performed to obtain each optical material, and the wafer type data is set for each wafer type. The wafer type data and the optical data are used as the analysis data 332 to be stored in the data memory means 330. Preferably, the analytical data is a plurality of pieces of data depending on the type of wafer. The more the amount of data for analysis, the more the reliability of the mode can be improved.

(Specific example of analysis processing)

Next, a specific example of the analysis processing for obtaining the correlation between the wafer type data and the optical data by using the analysis material 332 will be described. FIG. 7 is a flowchart showing a specific example of analysis processing. The wafer type data and the optical data used for the analysis processing are acquired in step S110. Specifically, for example, the wafer type data and the optical data are acquired by the analysis material 332 stored in the data memory means 330.

Next, in step S120, the correlation between the wafer type data and the optical data is obtained. That is, the multivariate analysis of the PLS method is performed based on the wafer type data and the optical data, and the correlation (for example, regression equation (1-1)) is obtained, and the correlation data 334 is memorized in the data memory. Means 330.

(Specific example of wafer processing by analysis result)

Next, a specific example of the wafer processing performed by the result of the analysis processing will be described with reference to the drawing. Fig. 8 is a flow chart showing a specific example of wafer processing in the embodiment. Here, for example, plasma etching treatment is performed on a wafer other than the analysis wafer (product wafer or the like). In this wafer processing, after the start of etching, the correlation type data 334 is used to determine the wafer type, and the end point detection setting data corresponding to the wafer type is selected, and the end point detection of the etching is performed based on the end point detection setting data.

Specifically, as shown in FIG. 8, first, plasma etching processing for the wafer is started in step S210, and end point detection setting data selection processing is performed in step S220. The plasma etching treatment in this case is the same as the above.

The end point detection setting data selection processing of step S220 is executed as shown in, for example, FIG. That is, first, when the etching is started in step S221, the optical data after the etching starts for several seconds (for example, three seconds) is obtained by the optical measuring device 200.

Next, in step S222, the wafer type data is calculated from the acquired optical data using the correlation data 334 from the data memory means 330. Specifically, the optical data is applied to the regression equation (1-1) of the correlation data 334, and the wafer type data is calculated.

For example, when the wafers W11 to W16 are etched, the optical data, that is, the spectral data after 3 seconds from the start of etching, is as shown in FIG. 11 is a graph in which the horizontal axis represents the wavelength and the vertical axis represents the light intensity at each wavelength in terms of reflectance. The spectral data of the wavelength region shown in FIG. 11 is roughly divided into two types of curve groups, that is, a curve group of the wafers W11 to W13 and a curve group of the wafers W14 to W16.

Next, in step S223, the wafer type (A, B) is determined from the calculated wafer type data. When the calculated wafer type data is close to, for example, the wafer type data 0 preset in the analysis data 332 shown in FIG. 5, the wafer type is determined as A, and when the wafer type data 1 is close to The wafer type is determined to be B.

FIG. 12 is a wafer type data map calculated by applying, for example, the spectral data of the wafers W11 to W16 to the regression equation (1-1). According to FIG. 12, the wafer type data is also roughly divided into two types of data groups corresponding to the curve group of the spectral data, that is, the data groups of the wafers W11 to W13 and the data groups of the wafers W14 to W16. The data group of the wafers W11 to W13 is a value close to 1, and the data group of the wafers W14 to W16 is a value close to zero. Therefore, the calculated wafer type data, for example, the intermediate value of 0 and 1 is 0.5, and the wafer type is determined to be A when the threshold value is below the threshold value. When the threshold value is exceeded, the wafer type is determined to be B.

Next, in step S224, the end point detection setting data corresponding to the determined wafer type is selected. Specifically, the end point detection selection data 336 of the data memory means 330 selects the end point detection setting data corresponding to the determined wafer type. For example, if the end point detection selection material 336 shown in FIG. 6 is used, the end point detection setting data Da is selected when the wafer type is A, and the end point detection setting data Db is selected when the wafer type is B.

Next, the process proceeds to step S230 shown in FIG. In step S230, an end point detection process based on the selected end point detection setting data (for example, an end point detection prescription) is executed. FIG. 10 shows a specific example of the end point detection processing. In this example, the end point is detected based on the film thickness of the film to be etched obtained in accordance with the spectral data. In this case, the end point detection setting data Da, Db shown in Fig. 6 is, for example, a method or a prescription for detecting the film thickness from the spectral data.

The end point detection processing is, for example, a period in which wafer processing is performed as shown in FIG. 10, in step S231, spectral data is acquired by the optical measuring instrument 200, and in step S232, the film thickness of the film to be etched is detected. In this case, for example, when the wafer type is A, the film thickness is detected by the spectral data using the end point detection setting data Da, and when the wafer type is B, the film thickness is detected by the spectral data using the end point detection setting data Db. Thereby, the film thickness can be accurately detected regardless of the wafer type.

Next, in step S233, it is judged whether or not the film thickness to be detected is the film thickness of the etching end point (predetermined target film thickness). When it is determined in step S233 that the film thickness of the non-etching end point is determined, it is determined in step S234 whether or not a specific sampling time has elapsed. If it is determined that the sampling time has elapsed, the process returns to step S231 to acquire optical data. In this manner, the optical data is taken for a specific sampling time, and the film thickness of the film to be etched is detected, and it is determined whether or not the film thickness to be formed forms the film thickness of the etching end point. Then, when it is judged in step S233 that the detected film thickness is the film thickness of the formation target, the process returns to the process shown in FIG. 8, and etching is terminated in step S240.

Next, the experimental results regarding the plasma etching treatment of the wafers of the species A and B will be described with reference to the drawings. FIG. 13 is a case where the end point detection is performed based on the same end point detection setting data (here, the wavelength region (wavelength band) of the spectral data used for the end point detection), and FIG. 14 is selected based on the determination of the wafer type. The end point detection setting data is used to perform the end point detection. Here, the plasma etching process is performed on 9 wafers of the seed A and 6 wafers of the seed B, and then the end point detection is performed, and the etching time at the end point of the detected end point detection is detected. The wafer types A and B are those in which the aperture ratios of the mask patterns on the respective wafers are different. Further, the wafer types A and B are the same as the material of the film to be etched formed on the wafer and the material of the mask.

According to the results of such an experiment, when the same end point detection setting data (wavelength region) is used regardless of the wafer type (Fig. 13), a difference occurs between the etching time data group of the wafer type A and the etching time data group of the wafer type B. deviation. In contrast, when the end point detection setting data (wavelength region) selected corresponding to the wafer type is used (FIG. 14), there is almost no between the etching time data group of the wafer type A and the etching time data group of the wafer type B. There will be deviations. Thereby, it can be seen that the deviation of the etching time can be eliminated by using the end point detection setting data selected in accordance with the wafer type. As described above, in the present embodiment, since the end point detection setting data can be selected in accordance with the wafer type, the end point detection corresponding to the wafer type can be performed, so that accurate end point detection can be performed regardless of the wafer type.

(Second embodiment)

Next, a second embodiment of the present invention will be described with reference to the drawings. In the plasma processing apparatus 100 used in the second embodiment, the configuration of the optical measuring device 200 is the same as that shown in FIG. 1 and FIG. 2, and thus detailed description thereof will be omitted. In the second embodiment, when the wafer type is distinguished by the type of the mask pattern formed on the film to be etched, it is exemplified that the optimum end point detection recipe (for example, film thickness data) is used depending on the type of the mask pattern. Be explained.

(wafer type and endpoint detection setting data)

Since the correct etching end point cannot be detected according to the type of the mask pattern, the present embodiment determines the type of the wafer having a different type of the mask pattern, and selects the end point detecting method corresponding to the type of the mask pattern as the end point. By detecting the setting data, it is possible to detect the correct etching end point regardless of the type of the mask pattern.

The end point detection selection data 336 in this case is formed as shown in Fig. 15. The wafer type here is distinguished by, for example, an aperture ratio of a specific region of the mask pattern, and when two types of mask patterns (for example, a first mask pattern and a second mask pattern) are used, the first mask pattern is used. The wafer type is set to A, and the wafer type of the second mask pattern is set to B. Further, the end point detection setting data corresponding to the wafer type A is the end point detection prescription Ra, and the end point detection setting data corresponding to the wafer type B is the end point detection prescription Rb.

On the wafer of such a type A, B, for example, as shown in FIG. 3, an etched film E and a mask M having a specific opening for forming holes in the etched film E are formed. The film E to be etched of the wafer of the species A is, for example, a polycrystalline germanium film, and the type of the mask M is, for example, a hard mask such as oxidized bismuth material (SiO ₂ ). The hard mask M is not limited thereto, and the mask M may be a hard mask such as a tantalum nitride (Si ₃ N ₄ ) or a light made of a photoresist (photosensitive material). Blocker. Further, the mask M of the wafer of the species A is patterned by the first mask pattern. On the other hand, the mask M of the wafer of the type B is patterned by the second mask pattern different from the aperture ratio of the first mask pattern.

(end point detection method)

Next, an end point detecting method for etching according to the present embodiment will be described. Here, the wafers of the types A and B all implement the same endpoint detection method. Specifically, as shown in FIG. 3, the single light La is irradiated toward the wafer W by the light source 206. As a result, the irradiation light La is reflected on the interface between the mask M and the film E to be etched, or is reflected on the exposed surface of the film E to be etched (the bottom surface of the hole H). The reflected light interferes with each other, and the interference light can be detected by the polychromator 208. The interference light detected by the polychromator 208 is input to the control unit 300 as optical data (spectral data).

Since the spectral data is composed of the light intensity of each wavelength as described above, when the film E is etched and the film thickness is changed, the light intensity of each wavelength changes, and the characteristics of the spectral data also change. Therefore, if the film thickness data showing the correspondence between the film thickness and the spectral data is prepared in advance, the film thickness can be used to etch the wafer, and the spectral data detected by the polychromator 208 can be used at a specific sampling timing. The film thickness of the film E to be etched is obtained in real time.

When the film thickness of the film E to be etched is obtained, for example, the spectral data detected by the polychromator 208 and the spectral data of the film thickness data are subjected to fitting, and the film thickness data corresponding to the optimum adjustment is obtained. The film thickness of the spectral data is the film thickness of the film E to be etched. The film thickness of the film E to be etched is monitored in this manner, and etching is completed at a time when a specific film thickness is formed.

Further, since the light intensity of each wavelength of the spectral data differs depending on the type (opening ratio) of the mask pattern, the characteristics of the spectral data are also different. Therefore, in the present embodiment, two types of film thickness data corresponding to the wafer types A and B are used as the end point detection recipes Ra and Rb, respectively, and the wafer type A can be obtained by using the film thickness data of the end point detection prescription Ra. The film thickness can be obtained by using the film thickness data of the end point detection prescription Rb for the wafer type B.

Specifically, a wafer having the same wafer as that of the species A and B of the present embodiment is prepared, and the wafer is subjected to plasma etching treatment, and the film thickness of the film E to be processed is measured while acquiring spectral data (for example, the exposed portion) According to the film thickness, two types of film thickness data showing the relationship between the film thickness and the spectral data were prepared. Then, the two types of film thickness data are used as the end point detection prescriptions Ra, Rb, and the end point detection selection data 336 corresponding to the wafer types A and B is stored in the data memory means 330.

16(A) and (B) show specific examples of the film thickness data of the end point detection prescriptions Ra and Rb, respectively. The film thickness data is, for example, the film thickness (T1, T2, T3, ...) used for a specific interval of film thickness detection as shown in Fig. 16 (A) and (B), and the spectral data to be obtained when the film thickness is obtained. . The spectral data in this case is the luminous intensity of each wavelength of a specific wavelength region (wavelength band). The wavelength region of this spectral data can vary depending on the type of wafer. The wavelength region having the most different characteristics, such as a wavelength region having a large change in the light-emission intensity, is set in accordance with the wafer type, whereby the end point detection can be performed more accurately. In addition, the wavelength region of such spectral data can also be used as the endpoint detection prescription Ra, Rb.

(Example of operation of the plasma processing apparatus)

Next, an operation example of the plasma processing apparatus 100 according to the second embodiment will be described. In the plasma processing apparatus 100 according to the second embodiment, the correlation between the wafer type data and the optical data is first obtained in the same manner as in the first embodiment. Specifically, for example, the analysis material 332 shown in FIG. 5 is acquired, and the analysis data 332 is used to perform multivariate analysis using the analysis data 332. Thereby, the correlation between the wafer type data and the optical data (regression formula (1-1)) is obtained, and the correlation data 334 obtained by the analysis result is stored in the data memory means 330.

Next, wafer processing (for example, processing of a product wafer) accompanying the determination of the wafer type is performed. This wafer processing is as shown in FIG. 8. After the start of the etching, the correlation data 334 is used to determine the wafer type, and the end point detection setting data corresponding to the wafer type is selected, and the end point of the etching is performed based on the end point detection setting data. Detection. In the present embodiment, when it is determined that the wafer type is A, the end point detection prescription Ra is selected as the end point detection setting data, and the end point detection is performed while detecting the film thickness of the film to be etched based on the film thickness data of the end point detection prescription Ra. When it is determined that the wafer type is B, the end point detection prescription Rb is selected as the end point detection setting data, and the end point detection is performed while detecting the film thickness of the film to be etched based on the film thickness data of the end point detection prescription Rb. Then, once the end point detection of the etch is detected, the etch is finished.

Thereby, it is possible to automatically determine the type of the wafer to be distinguished by the type of the mask pattern, and automatically select the end point detection prescription corresponding to the determined wafer type, thereby performing accurate end point detection regardless of the type of the mask pattern. .

(Third embodiment)

Next, a third embodiment of the present invention will be described with reference to the drawings. In the plasma processing apparatus 100 used in the third embodiment, the configuration of the optical measuring device 200 is the same as that shown in FIG. 1 and FIG. 2, and thus detailed description thereof will be omitted. In the third embodiment, when the wafer type is distinguished by the type of the material of the mask formed on the film to be etched, an optimum end point detecting method for the type of the mask is used as an example.

(wafer type and endpoint detection setting data)

Since the correct etching end point cannot be detected according to the type of the mask material (for example, the hard mask and the photoresist mask), this embodiment determines the wafer type of the material of the mask, and the selection corresponds to The end point detection method of the material type of the mask is used as the end point detection setting data, whereby the correct etching end point can be detected regardless of the type of the mask pattern.

The end point detection selection data 336 in this case is formed as shown in Fig. 17. The types of wafers here are distinguished by the transmittance of light. For example, it is distinguished by a hard mask and a photoresist mask. The wafer type in which the hard mask is formed is A, and the wafer type in which the photoresist mask is formed is B. Further, the end point detection setting data corresponding to the wafer type A is the method Qa, and the end point detection setting data corresponding to the wafer type B is the method Qb.

On the wafer of such a type A, B, for example, as shown in FIG. 18(A), an etched film E is formed, and a hard mask Ma having a specific opening for forming holes in the etched film E is formed. . The film E to be etched of the wafer of the species A is, for example, a polycrystalline germanium film, and the hard mask Ma is made of, for example, a cerium oxide material (SiO ₂ ). The hard mask Ma is not limited thereto, and the hard mask Ma may be formed of, for example, a tantalum nitride material (Si ₃ N ₄ ).

On the other hand, on the wafer of the seed B, for example, as shown in FIG. 19(A), the film E to be etched and the hard mask Ma having a specific opening for forming holes in the film E to be etched are formed. . The film E to be etched of the wafer of the type B is formed, for example, by a polysilicon film of the same type as that of the wafer of the seed A, and the photoresist mask Mb is made of, for example, a photoresist (photosensitive material) such as an i-line. The mask E to be etched and the mask Mb are not limited thereto, and the mask Mb may be formed of, for example, a photosensitive material such as Krf or Arf.

(end point detection method)

Next, the end point detecting methods Qa and Qb for etching in the third embodiment will be described.

First, the terminal detection method Qa will be described. The wafer in which the type A of the hard mask Ma is formed is further etched, for example, by the state shown in FIG. 18(A), and as shown in FIG. 18(B), only the exposed portion of the film E to be etched is formed ( The portion of the opening of the mask Ma is slowly etched to form the holes H. The etching in this case is, for example, a mixed gas of HBr gas and O ₂ gas as a processing gas.

In this case, the single light La is irradiated toward the wafer W by the light source 206. As a result, the irradiation light La is reflected by the hard mask Ma and is reflected by the interface between the hard mask Ma and the film E to be etched, and is reflected on the exposed surface of the film E to be etched (the bottom surface of the hole H). The reflected lights La11, La12 interfere with each other, and the interference light can be detected by the polychromator 208. The interference light Lai detected by the polychromator 208 is input to the control unit 30 as optical data (spectral data).

The light intensity (light intensity of each wavelength of the spectral data) of the interference light Lai detected by the polychromator 208 is, for example, the state shown in FIG. 18(A) to the state shown in FIG. 18(B). As the hole H becomes deeper, it is periodically reduced. Then, the control unit 300 can take in, for example, the light intensity of the interference light Lai detected by the polychromator 208 at a specific sampling timing, and obtain the film E to be etched based on the change in the light intensity of the interference light Lai. The etching amount (for example, the depth h12 of the hole H) is used to calculate the film thickness (the amount of etching residual film) of the film E to be etched. Then, etching is terminated at a point in time when the film E to be etched forms a specific film thickness.

Further, in the end point detecting method Qa, since the irradiation light La from the light source 206 passes through the hard mask Ma, even if the surface of the hard mask h11 is cut by etching, the film thickness of the film E to be etched is not obtained. Calculate the impact.

Next, the description of the endpoint detection method Qb will be described. Similarly, in the wafer of the species B in which the photoresist mask Mb is formed, for example, further etched by the state shown in FIG. 19(A), only the film E to be etched is as shown in FIG. 19(B). The exposed portion (the portion of the opening of the mask Mb) is slowly etched to form the hole H. The etching in this case is also the same as the case of using the wafer of the species A, for example, a mixed gas of HBr gas and O ₂ gas is used as the processing gas.

In the wafer of the seed B, the film thickness of the film E to be etched may not be detected by the single irradiation light La from the light source 206 as in the above-described end point detecting method Qa. For example, when the photo-resist mask Mb having a large absorption coefficient among the wavelengths of the irradiation light La from the light source 206 is different from the hard mask Ma, since the irradiation light La does not pass through the photo-mask Mb, the light cannot be obtained. The reflected light of the interface between the mask Mb and the film E to be etched. Therefore, even if a single irradiation light La is irradiated from the light source 206, the film thickness of the film E to be etched cannot be detected. Thus, the wafer of the species B is an end point detecting method Qb for performing a plurality of lights (for example, irradiation light La, Lb) having different wavelengths by the light source 206 to the wafer.

Specifically, the light source 206 irradiates two lights (the first irradiation light La and the second irradiation light Lb) having different wavelengths to the wafer W. For example, the wavelength of the irradiation light La is 261 nm, and the wavelength of the irradiation light Lb is 387 nm. Since the wavelength 261 nm of the irradiation light La is the light absorption band of the photoresist mask M, the irradiation light La cannot pass through the photoresist mask Mb, is reflected on the upper surface of the photoresist mask Mb, and is reflected on the film E to be etched. The exposed surface (the bottom surface of the hole H). The reflected lights La21 and La22 interfere with each other, and the first interference light Lai can be detected by the polychromator 208. The first interference light Lai detected by the polychromator 208 is input to the control unit 300 as the first optical data (first spectral data).

On the other hand, since the irradiation light Lb is longer than the wavelength 261 nm of the irradiation light La by 387 nm, it passes through the photoresist mask Mb and is reflected at the interface between the photoresist mask Mb and the film E to be etched, and is reflected. On the top of the photoresist mask Mb. The reflected lights Lb21, Lb22 interfere with each other, and the second interference light Lbi can be detected by the polychromator 208. The second interference light Lbi detected by the polychromator 208 is output to the control unit 300 as the second optical data (second spectral data).

The light intensity (light intensity of each wavelength of the spectral data) of the interference light Lai, Lbi detected by the polychromator 208 is, for example, the state shown in FIG. 19(A) to FIG. 19(B). The state is periodically reduced as the hole H becomes deeper. Therefore, the control unit 300 can take in the light intensity of the interference light Lai, Lbi detected by the polychromator 208, for example, according to a specific sampling timing, and instantly calculate the etched light based on the change in the light intensity of the interference light Lai, Lbi. The film thickness of the film E (for example, the depth of the holes H).

Specifically, the bottom surface position of the hole H (the height difference between the upper surface of the photomask Mb and the bottom surface of the hole H) obtained by the change in the light intensity of the first interference light Lai can be added to the second interference. The amount of etching (cut amount h21) of the mask Mb obtained by the change in the light intensity of the light Lbi is calculated based on the amount of etching of the film E to be processed (the absolute depth of the hole H, h22). The film thickness (the amount of residual etching film) of the film E to be etched. Then, etching is terminated at a point in time when the film E to be etched forms a specific film thickness.

Further, in the end point detecting method Qb, since the irradiation light La and Lb from the light source 206 are light reflected on the top surface of the photoresist mask Mb, the film of the film E to be etched can be detected by the reflected light. Therefore, even if the surface of the photomask Mb is cut by etching, the position of the surface is shifted, and the film thickness calculation of the film E to be etched is not affected.

(Example of operation of the plasma processing apparatus)

Next, an operation example of the plasma processing apparatus 100 according to the third embodiment will be described. Similarly to the case of the first embodiment, the plasma processing apparatus 100 of the third embodiment obtains the correlation between the wafer type data and the optical data in advance. Specifically, for example, the analysis material 332 as shown in FIG. 5 is acquired, and the analysis data 332 is used to perform multivariate analysis by the analysis processing shown in FIG. 7 . Thereby, the correlation between the wafer type data and the optical data (regression equation (1-1)) is obtained, and the correlation data 334 obtained by the analysis result is stored in the data memory means 330.

Next, wafer processing (for example, processing of a product wafer) accompanying the determination of the wafer type is performed. This wafer processing is as shown in FIG. 8. After the start of etching, the correlation data 334 is used to determine the wafer type, and the end point detection setting data corresponding to the wafer type is selected, and the end point detection setting data is used for etching. End point detection. In the present embodiment, when it is determined that the wafer type is A, the end point detecting method Qa is selected as the end point detecting setting data, and the end point detecting method Qa is used to perform the end point detecting. Further, when it is determined that the wafer type is B, the end point detection method Qb is selected as the end point detection setting data, and the end point detection method Qb is used to perform the end point detection. Then, once the end point detection of the etch is detected, the etch is finished.

Thereby, it is possible to automatically determine the type of the wafer to be distinguished by the type of the mask material, and automatically select the end point detecting method corresponding to the determined wafer type, thereby performing accurate end point detection regardless of the type of the mask.

The preferred embodiments of the present invention have been described above with reference to the drawings, but are not limited to the examples of the present invention. As long as it is the person in charge, various modifications and corrections can be made within the scope of the patent application. Of course, these are also within the technical scope of the present invention.

For example, in the above-described embodiment, the plasma treatment is described as an example of etching the wafer. However, the present invention is not limited thereto, and the present invention can also be applied to other plasma treatment such as film formation.

[Industry use possibility]

The invention is applicable to a plasma processing method and a plasma processing apparatus.

100. . . Plasma processing device

102. . . Processing room

103. . . Insulation board

104. . . Pedestal support

105. . . Pedestal

107. . . Temperature regulation media room

108. . . Inlet tube

109. . . Drain pipe

110. . . Electrostatic chuck

111. . . Electrostatic chuck

112. . . electrode

113. . . DC power supply

114. . . Gas passage

115. . . Focus ring

121. . . Upper electrode

122. . . Insulating material

123. . . Spit hole

124. . . Electrode plate

125. . . Electrode support

126. . . Gas inlet

127. . . Gas supply pipe

128. . . valve

129. . . Mass flow controller

130. . . Process gas supply

131. . . exhaust pipe

132. . . gate

135. . . Exhaust

140. . . High frequency power supply

141. . . Integrator

150. . . High frequency power supply

151. . . Integrator

160. . . Observation department

162. . . Window

200. . . Optical measuring instrument

202. . . Collecting lens

204. . . optical fiber

206. . . light source

208. . . Multicolor meter

300. . . Control department

310. . . Program memory means

320. . . Arithmetic means

330. . . Data memory means

332. . . Analytical data

334. . . Related information

336. . . End point detection selection data

340. . . Output means

350. . . Various controllers

1 is a cross-sectional view showing a schematic configuration of a plasma processing apparatus according to a first embodiment of the present invention.

Fig. 2 is a block diagram showing a schematic configuration example of an optical measuring instrument of the same embodiment.

Figure 3 is a diagram for explaining reflected light from a wafer.

Fig. 4 is a block diagram showing a schematic configuration example of a control unit of the same embodiment.

Fig. 5 is a view showing a specific example of the analysis material of the same embodiment.

Fig. 6 is a view showing a specific example of the selection data for the end point detection in the same embodiment.

Fig. 7 is a flow chart showing a specific example of the analysis processing of the same embodiment.

Fig. 8 is a flow chart showing a specific example of wafer processing in the same embodiment.

FIG. 9 is a flowchart showing a specific example of the end point detection setting data selection processing shown in FIG. 8.

FIG. 10 is a flowchart showing a specific example of the end point detection processing shown in FIG. 8.

FIG. 11 is a view showing a specific example of spectral data when plasma processing is started for two types of wafers.

Fig. 12 is a wafer type data calculated from each spectral data shown in Fig. 11 .

Fig. 13 is an etching time when the end point detection is performed based on the same end point detection setting data regardless of the wafer type.

FIG. 14 is an etching time when the end point detection is performed based on the end point detection setting data selected for determining the wafer type.

Fig. 15 is a view showing a specific example of the selection data for the end point detection according to the second embodiment of the present invention.

Fig. 16 is a view showing a specific example of each of the portions shown in Fig. 15. Fig. 16 is a specific example of the film thickness data of the prescription Ra, and Fig. 16(B) is a specific example of the film thickness data of the prescription Rb.

Fig. 17 is a view showing a specific example of the selection data for the end point detection according to the third embodiment of the present invention.

FIG. 18 is an explanatory view for explaining the operation of the end point detecting method Qa of the wafer A of the type A in which the hard mask is formed.

Fig. 19 is an explanatory view for explaining the operation of the end point detecting method Qb of the wafer of the type B in which the photoresist mask is formed.

Claims (21)

A plasma processing method is a plasma processing method in which a high-frequency power is applied to an electrode disposed in a processing chamber to generate a plasma of a processing gas, and a plasma is applied to the substrate by a specific treatment. And an analysis step of determining a correlation between the substrate type data set corresponding to the plurality of substrate types and the optical data detected by the optical data detecting means when the substrate is processed by the multi-variable analysis; a step of calculating a substrate type data from the optical data detected by the optical data detecting means when the plasma processing of a substrate is started by using the correlation relationship obtained in the analyzing step, and calculating the substrate type data according to the calculated substrate type data Determining the type of the substrate; and selecting a step corresponding to each of the setting data of the end point of the plasma processing detected in advance by the data memory means in association with each of the substrate types The setting data of the substrate type determined by the step; the end point detecting step is based on the selection step Optional end point detection setting data to perform the plasma processing; and the end of the step, which is based on the above-described end-point detection step detects the end of the end plasma treatment. The plasma processing method of claim 1, wherein the optical data detecting means comprises: a light source that emits light on the substrate; and a light detecting means that detects spectral data of the reflected light obtained by reflecting the light from the light source from the substrate. The plasma processing method of claim 2, wherein the optical data for determining the substrate type is: detected by the optical data detecting means at a specific time point immediately after the plasma processing of the substrate is started. Spectral data. The plasma processing method according to the third aspect of the invention, wherein the substrate type is distinguished according to a type of a mask formed on a film to be processed by a plasma treatment, and the end point detecting step is performed while processing the substrate. The film thickness of the film to be processed on the substrate is detected by the spectral data detected by the optical data detecting means at a specific timing, and the time at which the film thickness is formed to form a specific film thickness is used as a plasma. The end of the treatment. The plasma processing method according to claim 1, wherein each of the setting data is an end point detecting method or an end point detecting prescription suitable for each of the substrate types, and the end point detecting method is based on reflecting from the substrate according to the irradiation of the substrate. a method of detecting an end point by a film thickness detected by spectral data of the reflected light, or a method of detecting an end point according to a change in spectral data of the plasma light emission, wherein the end point detection prescription is a film thickness data of each substrate type or The wavelength region of the spectral data, the type of light source that is illuminated to the wafer. For example, the plasma processing method of claim 1 of the patent scope, wherein In the above analysis step, a partial least squares method is used as the above multivariate analysis. A plasma processing method is a plasma processing method in which a high-frequency power is applied to an electrode disposed in a processing chamber to generate a plasma of a processing gas, and a plasma is applied to the substrate by a specific treatment. And an analysis step of obtaining a substrate type data and a plasma set corresponding to a plurality of substrate types classified according to a type of a mask pattern formed on a processed film on the substrate by multivariate analysis a correlation relationship between the optical data detected by the optical data detecting means when the substrate is processed; and a determining step of utilizing the correlation obtained in the analyzing step, when the plasma processing of a substrate is started from the optical data The optical data detected by the detecting means calculates the substrate type data, and determines the type of the substrate based on the calculated substrate type data; and the selecting step is performed by using the data memory means in advance in association with each of the substrate types Selecting data corresponding to each of the detected end points of the plasma processing to select the one corresponding to the determination step The substrate setting information is set; the end point detecting step is performed to perform the end point detection of the plasma processing according to the prescription setting data selected in the selecting step; and the final step is the end point detected in the end point detecting step At the end of the plasma treatment. The plasma processing method of claim 7, wherein the optical data detecting means comprises: a light source that emits light on the substrate; and a light detecting means that detects spectral data of the reflected light obtained by reflecting the light from the light source from the substrate. The plasma processing method according to the eighth aspect of the invention, wherein the substrate type is distinguished by an aperture ratio of an opening of a photomask formed on the substrate. The plasma processing method according to claim 9, wherein the setting data of the plurality of places is a plurality of film thickness data indicating a correspondence relationship between the optical data and the film thickness, and the selecting step is selected corresponding to the determining step. The film thickness data of the determined substrate type, wherein the end point detecting step uses the film thickness selected by the optical data detecting means at a specific timing while processing the substrate, and uses the film thickness selected in the selecting step. The data was used to detect the film thickness of the film to be processed on the substrate, and the time at which the film thickness was formed to form a specific film thickness was used as the end point of the plasma treatment. A plasma processing method is a plasma processing method in which a high-frequency power is applied to an electrode disposed in a processing chamber to generate a plasma of a processing gas, and a plasma is applied to the substrate by a specific treatment. And an analysis step of obtaining a substrate type data and a plasma set corresponding to a plurality of substrate types classified according to a material type of a photomask formed on the film to be processed on the substrate by multivariate analysis Correlation of optical data detected by optical data detecting means when processing the above substrate; a determination step of calculating a substrate type data from the optical data detected by the optical data detecting means when the plasma processing of a substrate is started by using the correlation obtained by the analyzing step, and calculating the substrate type according to the calculated substrate type The data is used to determine the type of the substrate; and the selecting step is performed by selecting each of the detection method setting data associated with each of the substrate types and previously stored in the data memory means for detecting the end point of the plasma processing. Setting data in the substrate type determined in the determining step; an end point detecting step of performing end point detection of the plasma processing based on each of the detection method setting data selected in the selecting step; and ending the step The plasma treatment is terminated at the end point detected by the above-described end point detecting step. The plasma processing method according to claim 11, wherein the optical data detecting means includes: a light source that emits light on the substrate; and a light detecting means that detects the light from the light source from the above Spectral data of reflected light obtained by reflection on the substrate. The plasma processing method according to claim 12, wherein the substrate type is distinguished by a hard mask or a photoresist mask on the substrate. The plasma processing method of claim 13, wherein the setting method for the detection method of the substrate on which the hard mask is formed is: for reflecting the substrate from the light source The spectral data of the reflected light from the substrate obtained by the single irradiation light of the wavelength of the hard mask is used to detect the film thickness of the film to be processed, and the detection method for detecting the end point based on the detected film thickness is performed. The data setting method for the type of the substrate on which the photoresist mask is formed is used to irradiate the substrate with the irradiation light of the wavelength of the light source and the reflected wavelength of the light source. The obtained spectral data of the reflected light from the substrate is used to detect the film thickness of the film to be processed, and the setting data of the detection method for detecting the end point based on the detected film thickness is performed. A plasma processing apparatus is a plasma processing apparatus that applies high-frequency power to electrodes disposed in a processing chamber to generate plasma of a processing gas, and applies a specific treatment to the substrate by the plasma. The invention provides an optical data detecting means for detecting optical data when the plasma is processed by the substrate, and a data memory means for memorizing: indicating the substrate type data corresponding to the plurality of substrate types and the optical data by using the optical data a correlation data of the correlation of the optical data detected by the detecting means, and setting data for detecting an end point of the plasma processing respectively associated with each of the substrate types; and a control unit, which is connected to the processing room When the substrate is processed by the slurry, the substrate type data is calculated from the optical data detected by the optical data detecting means by the correlation data stored in the data memory means, and the substrate type data is determined based on the calculated substrate type data. Substrate type, and the end point detection setting resources memorized by the above data memory means The end point detection setting data corresponding to the determined substrate type is selected, and the end point detection of the plasma processing is performed based on the selected end point detection setting data. The plasma processing apparatus according to claim 15, wherein the optical data detecting means includes: a light source that emits light on the substrate; and a light detecting means that detects the light from the light source from the above Spectral data of reflected light obtained by reflection on the substrate. The plasma processing apparatus of claim 16, wherein the optical data for determining the substrate type is detected by the optical data detecting means at a specific time point immediately after the plasma processing of the substrate is started. Spectral data. The plasma processing apparatus according to claim 17, wherein the substrate type is distinguished according to a type of a mask formed on a film to be processed by a plasma treatment, and an end point detection of plasma processing of the substrate is performed. When the substrate is processed, the film thickness of the film to be processed on the substrate is detected based on the spectral data detected by the optical data detecting means at a specific timing, and the film thickness is determined by the detected film thickness. The time point of the film thickness is used as the end point of the plasma treatment. The plasma processing apparatus of claim 15, wherein each of the setting data is an end point detecting method or an end point detecting prescription suitable for each of the substrate types, and the end point detecting method is based on the substrate when the light is irradiated to the substrate. The method of detecting the end point of the film thickness detected by the spectral data of the reflected light obtained by the reflection, or the method of detecting the end point based on the change of the spectral data of the plasma luminescence, wherein the end point detection prescription is the film thickness data of each substrate type Or the wavelength region of the spectral data, the type of light source that is illuminated to the wafer. The plasma processing apparatus according to claim 15, wherein the correlation data between the substrate type data and the optical data is obtained by multivariate analysis of the substrate type data and the optical data. A plasma processing apparatus according to claim 20, wherein a partial least square method is used in the multivariate analysis system.