JP2005079454A - Plasma treatment device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plasma treatment device wherein such a state of its inside as the end point of an etching reaction can be detected accurately. <P>SOLUTION: The plasma treatment device has a treatment chamber 1 for generating a plasma therein and subjecting a sample disposed therein to a plasma treatment, an auxiliary-light chopping mechanism 502 for so interrupting an auxiliary light emitted from an auxiliary-light source 501 as to feed it to the inside of the processing chamber 1, a spectral detecting means 503 for detecting respectively a plasma light emission and the sum of the auxiliary light and the plasma light emission which pass the inside of the treatment chamber, and an operational processing portion 504 for detecting a plasma-light-emission spectrum based on the detected output of the spectral detecting means and detecting an absorption spectrum relative to the auxiliary light based on the interrupting signal emitted from the auxiliary-light chopping mechanism. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a plasma processing apparatus, and more particularly to a plasma processing apparatus that can accurately detect a state in a plasma processing apparatus.

  FIG. 5 is a diagram for explaining a conventional plasma etching apparatus. In FIG. 5, the plasma etching apparatus includes a processing chamber (processing vessel) 1, a gas supply means 14 for supplying a processing gas into the processing chamber, an exhaust outlet path 8, exhausting the processing gas and setting the pressure in the processing chamber to a set value. A gas exhaust means 9 is provided for control. Further, the processing chamber 1 includes a sample stage 2 that supports a sample 5 to be processed and a plasma generation means 6 for generating plasma in the processing chamber.

  The plasma generating unit 6 includes a magnetron that generates an electromagnetic wave, an electromagnetic wave supplying unit that supplies the generated electromagnetic wave into the processing chamber 1, an antenna that generates an electric field in the processing chamber 1, and an electromagnetic coil that generates a magnetic field. Further, a high frequency voltage from a high frequency power source 7 is applied to the sample stage 2 to attract reaction products such as ions generated by the plasma to the sample side.

  Further, the plasma etching apparatus includes apparatus state detection means 15. The means 15 includes an analyzer for detecting light emission from the plasma generated in the processing chamber 1 by the plasma generating means 6 and performing spectroscopic analysis to generate analysis data. By using this analyzer, for example, the end point of etching can be determined (see Patent Document 1).

  FIG. 6 is a diagram for explaining a conventional plasma ashing apparatus. The plasma ashing apparatus includes a processing chamber 1, a perforated conductive plate 13 for partitioning plasma in the processing chamber 1, and an electromagnetic wave supply means 10 for supplying microwaves and the like for generating plasma in the processing chamber 1. In addition, the processing chamber 1 includes a sample stage 2 that supports the sample 5. The radicals generated in the plasma processing apparatus are transported through the processing chamber 1 to the upper surface of the sample 5 through the perforated conductive plate 13 and cause an ashing reaction on the upper surface of the sample 5.

11 is a spectroscope disposed above the processing chamber, and 12 is a photomultiplier. The state of the plasma can be observed by dispersing light emitted from the plasma with the spectroscope 11 or the like and observing the spectral output using the photomultiplier 12.
Japanese Patent Application No. 2002-64783

  For example, when the etching end point is determined by the plasma etching apparatus, it is difficult to determine the etching end point when the sample to be etched is a non-volatile material such as heavy metal. That is, when a non-volatile material is etched, the amount of luminescence of the reaction product to be generated is very small. Therefore, it is difficult to determine the end point of etching.

  In addition, when trying to estimate the etching shape, completed dimensions, etc. from the light emission amount, it is necessary to accurately measure the amount of ions, radicals, etchants, reaction products, etc. present in the processing chamber. Become. However, light emission from ions, radicals, etchants, reaction products, and the like is slight, so that the light emission is buried in the plasma light emission, and it is difficult to accurately measure these amounts.

  In addition, the plasma ashing apparatus generates radicals by plasma as described above, and performs ashing by transporting the generated radicals to the sample surface. That is, the ashing reaction proceeds mainly with radicals transported in the vicinity of the upper surface of the sample. For this reason, observation cannot be performed using the spectroscope 11 and the photomultiplier 12 disposed above the processing chamber. That is, the plasma that can be observed by the spectroscope 11 and the photomultiplier 12 is separated from the reaction part in the vicinity of the upper surface of the sample. For this reason, it is difficult to detect the end point of the ashing reaction using the spectroscope 11 and the photomultiplier 12.

  The present invention has been made in view of these problems, and provides a plasma processing apparatus capable of accurately detecting the state in the apparatus such as the end point of the etching reaction.

  In order to solve the above problems, the present invention employs the following means.

  A processing chamber for generating plasma in the processing chamber and performing plasma processing on a sample disposed in the chamber; and an auxiliary light chopping mechanism for intermittently supplying auxiliary light from the auxiliary light source into the processing chamber; Spectral detection means for detecting the plasma light emission of plasma and the sum of the auxiliary light and plasma light emission that have passed through the processing chamber, and the plasma emission spectrum and the light emission spectrum based on the detection output of the spectral detection means and the intermittent signal by the chopping mechanism An arithmetic processing unit for detecting an absorption spectrum for the auxiliary light is provided.

  Since this invention is provided with the above structure, it can provide the plasma processing apparatus which can detect the state in an apparatus accurately.

  Hereinafter, the best embodiment will be described with reference to the accompanying drawings. FIG. 1 is a diagram illustrating a plasma processing apparatus (etching apparatus) according to this embodiment.

  As shown in FIG. 1, a quartz cover 16 formed of a light-transmitting member such as quartz is provided inside the processing chamber 1. The quartz cover 16 is disposed so as to surround the side or upper side of the sample table 2. By arranging in this way, plasma is generated in the space inside the quartz cover 16, and even if various reaction products are generated by the plasma, the products adhere to the inner wall surface of the processing chamber 1, Alternatively, it is possible to prevent the inner wall surface of the processing chamber 1 from being scraped by the plasma or a product of the reaction.

  A view for irradiating intermittent light of auxiliary light to the inside of the processing chamber 1 on the side wall of the processing chamber 1 to receive light (reflected light of the auxiliary light or plasma light) from the inside of the processing chamber 1. Port 3 is provided.

  The viewport 3 is provided with auxiliary light irradiation means and light receiving means (not shown). Further, the intermittent light of the auxiliary light generated in the apparatus state detection unit 50 is transmitted to the view port 3 through the illumination fiber 505, and the light received by the view port is transmitted to the spectral detection unit 503 through the light receiving fiber 506. To do.

  Here, the intermittent light of the auxiliary light can be generated by intermittently turning on / off the irradiation light of the auxiliary light source 501 by the auxiliary light chopping mechanism 502. The intermittent light generated by the chopping mechanism 502 is transmitted to the viewport 3 through the irradiation fiber 505.

  Further, a reflection means 4 is provided on the inner wall surface of the processing chamber for reflecting the intermittent auxiliary light and directing it to the light receiving means. The reflection means 4 is provided outside the quartz cover 16 in order to prevent the plasma or the reaction product generated thereby from adhering or the surface from being scraped by the plasma. It can be provided inside the quartz cover 16 or inside the processing chamber 1.

  The light received by the light receiving unit attached to the view port is supplied to the spectroscopic detection means 503 via the light receiving fiber 506.

  The spectroscopic detection means 503 receives auxiliary light and plasma emission when the auxiliary light is conducted by the chopping mechanism 502, and receives plasma emission when the auxiliary light is not conducted. In addition, the arithmetic processing unit 504, based on the spectral output from the spectral detection unit 503 and the chopping signal indicating the intermittent timing of the chopping mechanism 502, respectively, calculates the plasma emission spectrum and the absorption spectrum due to the reaction product, as will be described later. Analyze and detect conditions in the processing chamber.

  FIG. 2 is a diagram illustrating a process for detecting the state in the plasma processing apparatus based on the reflected light of the auxiliary light. In this example, auxiliary light is irradiated and the reflected light is measured before the etching process (without plasma discharge). The light detected by the spectroscopic detection means 503 is auxiliary light transmitted through the quartz cover 16 and the viewport 3 (measurement value 1).

  The quartz cover 16 and the viewport 3 are attached with products or the surfaces thereof are scraped with plasma processing. Along with this, the amount of attenuation of light also changes under the influence. When the reaction product or the like adheres to the inner wall surface of the quartz cover 16 or to the viewport, the amount and intensity of light passing through the quartz cover 16 are greatly attenuated due to the attached matter. If it is performed, it may be determined that the light emission in the processing chamber has decreased, and based on this, it may be determined that the reaction has been stopped or terminated.

  Therefore, for example, every time processing of a wafer as a sample is started or lot processing is started, auxiliary light from the light source 801 of auxiliary light is continuously (or intermittently) input into the processing chamber 1 by the chopping mechanism 502. To). The irradiated auxiliary light passes through the quartz cover 16, passes through the space in the quartz cover 16, is reflected by the reflecting means 4, and is received by the light receiving means. The received light is transmitted to the spectral detection means 503 via the light receiving fiber 506, where it is dispersed for each wavelength, and the difference from the irradiation light for each wavelength preset by the arithmetic processing means 504, that is, the amount of spectrum Calculate the attenuation. Thereby, the degree of contamination of the quartz cover 16 and the viewport 3 can be detected. This attenuation amount can be used as a correction value for the measured value in the following processing. Further, by storing each time the amount of attenuation of the spectrum amount is calculated, it is possible to know a change with time.

  FIG. 3 is a diagram for explaining a process for detecting the state in the plasma processing apparatus based on the reflected light of the auxiliary light or the plasma emission, and FIG. 3A is a diagram when the auxiliary light is turned off during the etching process (with plasma discharge). FIG. 3B is a diagram illustrating photometry when auxiliary light is on (during irradiation) during the etching process (with plasma discharge).

  As described above, the light received through the light receiving means is split by the spectral detection means 803 through the light receiving fiber 506. The spectrum of the separated light represents various reactions or the generation of substances depending on the wavelength (frequency). Therefore, by evaluating the intensity of this spectrum, it is possible to detect the corresponding reaction and the state of product formation, or the amount and speed of the reaction.

  For example, when the intensity or size of a spectrum at a certain wavelength is large, it can be considered that the amount of reaction or product corresponding to that wavelength is large. Conversely, if the amount of this spectrum is reduced, the corresponding reaction becomes smaller, or it can be determined that the reaction has ended or stopped.

  Further, when a substance such as a reaction product is present in the processing chamber 1, the auxiliary light absorbs light having a wavelength specific to the substance. Therefore, by evaluating the intensity of the absorption spectrum, it is possible to detect the reaction corresponding to the absorption spectrum, the state of production of the product, the amount and speed of the reaction, and the like. That is, it is possible to detect the plasma state or the reaction state by measuring the absorption of light or auxiliary light generated by the plasma emission or reaction inside the processing chamber 1.

  First, the light reception data obtained in the case of FIG. 3A, that is, the light detected by the spectral detection means 503 during the etching process (with plasma discharge) and when the auxiliary light is on (at the time of irradiation) is the quartz cover 16. And the plasma emission transmitted through the viewport 3 (measurement value 2).

  As described above, light generated in the processing chamber 1 when processing a sample, that is, plasma light emission, includes light emission accompanying various chemical reactions or product generation reactions that occur in the plasma. For this reason, it is possible to detect the apparatus state of the plasma processing apparatus by analyzing the spectrum intensity by spectrally diffusing the plasma emission for each wavelength by the spectral detection means 503.

  For example, by using the change in the time-series data for the light spectrum of a specific wavelength, information such as the start of reaction or the end of reaction corresponding to the wavelength can be detected. Further, by using the attenuation amount (measured value 1) calculated in FIG. 2, the influence of the attenuation amount of light when passing through the quartz cover or the viewport is suppressed and the reaction detection accuracy is improved. Can be improved.

  The light reception data obtained in the case of FIG. 3B, that is, the light detected by the spectroscopic detection means 503 during the etching process (with plasma discharge) and when the auxiliary light is on (at the time of irradiation) is the quartz cover 16. And auxiliary light transmitted through the viewport 3 and plasma emission transmitted through the quartz cover 16 and the viewport 3 (measurement value 3).

  When the auxiliary light passes through the processing chamber, light specific to the material is absorbed by the material (such as a reaction product) existing in the processing chamber. Therefore, by obtaining the change with time of the absorption spectrum, it is possible to know the change with time of the reaction product existing in the processing chamber. Further, for example, the end point of etching can be determined using this change with time.

  Here, as the absorption spectrum for the auxiliary light, the light reception data in FIG. 3A and the light reception data in FIG. 3B are alternately obtained, and the spectrum data (measured value) corresponding to the light reception data in FIG. It can be obtained by subtracting spectral data (measured value 2) corresponding to the received light data in FIG.

  Note that the received light data (measured value 2) in FIG. 3A and the received light data (measured value 3) in FIG. 3B are obtained by intermittently supplying auxiliary light from the auxiliary light source 501 by the chopping mechanism as described above. And the plasma emission and the reflected light of the auxiliary light can be alternately obtained by detecting with the spectral detection means. The auxiliary light is preferably white light.

  FIG. 4 is a diagram for explaining an example in which the apparatus state detecting means 50 is applied to a plasma processing apparatus (ashing apparatus). In the figure, the same parts as those shown in FIGS. 1 and 6 are denoted by the same reference numerals, and the description thereof is omitted.

  In this example, the measurement light path composed of the view port 3 and the reflection means 4 is set in the vicinity of the sample 5 installed on the sample stage 2. For this reason, the apparatus state detection means 50 can detect the apparatus state in the vicinity of the sample without being disturbed by plasma.

  As described above, according to the present embodiment, for example, when the end point is determined, the absorption spectrum of the reaction product or the like with respect to the auxiliary light and the spectrum of plasma emission are used, so that the end point can be determined with high accuracy. In addition, since the absorption spectrum data is absorption spectrum data for auxiliary light having a substantially constant output (because it is not absorption spectrum data for plasma emission with a large fluctuation amount), the change with time can be accurately measured. Therefore, a more accurate machining shape can be obtained.

  When applied to an ashing apparatus, the measurement light path composed of the view port 3 and the reflection means 4 is set in the vicinity of the sample 5 installed on the sample stage 2. For this reason, the apparatus state detection means 50 can detect the apparatus state in the vicinity of the sample without being disturbed by plasma.

Incidentally, by using the auxiliary light including the infrared light component as the auxiliary light, it is possible to detect the absorption spectrum of the C0 _2, it is possible to determine the end point of the ashing using the same.

Also, other processes can be evaluated in the ashing process. For example, an in-line ashing device for an aluminum wiring etching device can perform an ashing process to perform a touch-proof process in addition to resist removal. That is, the aluminum wiring before the ashing treatment is bonded to chlorine as an etchant, but it is possible to perform the anti-corrosion treatment by substituting this with fluorine (Al—Cl + F * (fluorine radical) → Al—F + Cl _2. ). In such a case, the anti-corrosion treatment process can be monitored by detecting the absorption spectrum of Cl or F, and the anti-corrosion performance of the apparatus can be evaluated.

It is a figure explaining the plasma processing apparatus of this embodiment. It is a figure explaining the process which detects the state in a plasma processing apparatus based on the reflected light of auxiliary light. It is a figure explaining the process which detects the state in a plasma processing apparatus based on the reflected light or plasma light emission of auxiliary light. It is a figure explaining the example which applied the apparatus state detection means 50 to the ashing apparatus. It is a figure explaining the conventional plasma etching apparatus. It is a figure explaining the conventional plasma ashing apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Processing chamber 2 Sample stand 3 Viewport 4 Reflection means 5 Sample 6 Plasma generation means 7 High frequency power supply 8 Exhaust outlet path 9 Exhaust means 10 Electromagnetic wave supply means 11 Spectrometer 12 Photomultiplexer 13 Perforated conductive plate 14 Gas supply means 15 Device state Detection means 16 Quartz cover 50 Device state detection means 501 Auxiliary light source 502 Auxiliary light chopping mechanism 503 Spectral detection means 504 Arithmetic processing means 505 Illuminating optical fiber 506 Receiving optical fiber

Claims (8)

A processing chamber for generating plasma in the processing chamber and performing plasma processing on a sample disposed in the chamber;
Auxiliary light chopping mechanism for intermittently supplying auxiliary light from the auxiliary light source and supplying it into the processing chamber;
Spectral detection means for detecting the plasma emission of the plasma and the sum of the auxiliary light and plasma emission that have passed through the processing chamber,
A plasma processing apparatus comprising an arithmetic processing unit for detecting a plasma emission spectrum and an absorption spectrum for auxiliary light based on a detection output of a spectral detection means and an intermittent signal by the chopping mechanism.   2. The plasma processing apparatus according to claim 1, wherein an end point of the plasma processing is detected based on the detected plasma emission spectrum and absorption spectrum for the auxiliary light.   The plasma processing apparatus according to claim 1, further comprising a reflecting mirror that reflects auxiliary light that has passed through the vacuum processing chamber, wherein the spectroscopic detection unit detects light reflected by the reflecting mirror.   2. The plasma processing apparatus according to claim 1, wherein the intensity of the auxiliary light is greater than the intensity of the plasma emission.   2. The plasma processing apparatus according to claim 1, wherein a state change in the processing chamber is detected based on a plasma emission spectrum detected for each sample to be subjected to plasma processing and an absorption spectrum for auxiliary light. .   2. The plasma processing apparatus according to claim 1, wherein the auxiliary light is introduced into the vacuum processing chamber in a state where no plasma is emitted, and contamination of the introduction part and the outlet part of the auxiliary light is detected.   2. The plasma processing apparatus according to claim 1, wherein the auxiliary light is white light. 8. The plasma processing apparatus according to claim 1, wherein the auxiliary light is white light including an infrared component.

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