JP2012047556A - Apparatus and method for measuring active species being present in plasma - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus and a method capable of easily measuring the quantity of active species such as ions or radicals generated by plasma being present in a vacuum device.SOLUTION: The quantity of active species generated by plasma or the like is measured by comparing a physical property depending output that is a result measured by a physical property depending output measuring apparatus, in which no obstacle is mounted, enabling all components including active species in plasma to reach the physical property depending output measuring apparatus, the physical property depending output that is a result measured by the physical property depending output measuring apparatus, in which any obstacle is mounted, capable of perfectly blocking only active species in plasma, and a fixed output value obtained in measurements by the physical property depending output measuring apparatus with obstacles in which a representative length of any other space than with or without obstacles is changed.

Description

  The present invention relates to an apparatus and method for measuring the amount of active species such as ions and radicals other than molecules present in a vacuum apparatus, and more particularly to an apparatus and method for determining the amount of activity present in a gas phase such as plasma. .

  Conventionally, various types of processing using plasma have been performed in the field of semiconductor manufacturing equipment and the like. In such plasma-based devices, measuring the amount of active species other than molecules such as radicals and ions is necessary to maintain the plasma in a state suitable for processing and to maintain the accuracy and efficiency of the processing. It is a thing.

  In view of this, plasma measuring methods such as a plasma monitoring method, a plasma processing method, a semiconductor device manufacturing method, and a plasma processing apparatus have been proposed (see Patent Document 1).

  By using the fact that the quartz vibrator sensor output depends on the molecular weight and viscosity of the gas to be measured, the concentration (partial pressure) of each gas in the mixed gas composed of two kinds of gases can be obtained. Such a concentration measuring method in a binary gas mixture is already known (see Patent Document 2).

  A method of detecting the end point of cleaning by measuring the radical emission intensity of a CVD processing container is known (see Patent Document 3).

  For measurement of active species such as ions and radicals, a method using light is generally used. Specifically, for ions and radicals that themselves emit light in plasma, the type of active species that emits light of that wavelength is analyzed by measuring the wavelength of the light using a spectrometer. Measurement is the simplest method.

  Since the wavelength of emitted light is fixed depending on the type of active species, the amount of active species emitted can be measured by the intensity analysis of the plasma emission. These methods using plasma emission are particularly effective for measuring active species and ions in an excited state in a high energy state.

  In addition to these, for measurement of active species in the ground state, which is a steady state of energy, it is necessary to separately introduce measurement light into the plasma. As a light source, there is a method of irradiating a plasma with a high-intensity and high-intensity laser to measure absorption by active species in the ground state, or detecting light such as fluorescence or phosphorescence emitted by the active species after absorption. is there.

  Wavelength of the light and light emitting active species are absorbed can be determined the type and amount of the original activity nest by analyzing whether the wavelength of which light for are determined by the active species type. The above is described in detail in Non-Patent Document 1. Further, Patent Document 4 has been filed in which a cleaning end point is detected by plasma treatment using a change in the amount of active species measured by such a method.

  However, in the above method, it is difficult to detect the most abundant gas molecules in the plasma, and in addition, the other lasers used as the light source are expensive and the analysis of the measurement results is complicated. Furthermore, it cannot be used when light adversely affects the plasma processing.

  Patent Document 4 is a method and apparatus for measuring active species in plasma by performing both quartz crystal sensor measurement and gas analysis using a mass analyzer and comparing the results. In this method and apparatus, mass spectrometry is performed. A vessel is essential. In the existing mass spectrometer used for such gas analysis, it is difficult to perform measurement by installing the measurement unit inside the plasma apparatus due to the size limitation of the measurement unit. Since the measurement part affects the plasma, accurate measurement is difficult. In addition, when the pressure in the vacuum apparatus in which the plasma to be measured exists is as high as 1 kPa or more, the pressure in the analysis part of the mass analyzer also increases, which significantly reduces the measurement accuracy. It cannot be used at this pressure.

Japanese Patent No. 3873394 Japanese Patent No. 3336384 JP 2006-086325 A JP 2010-038867 A

Mitsuharu Onuma, “Basics of Plasma and Film Formation”, Nikkan Kogyo Shimbun, Chapter 4 Absolute concentration and loss kinetics of hydrogen atom in methane and hydrogen plasmas, Journal of applied Physics, 90 (11), 5497-5503 (2010)

  In view of the situation as described above, an apparatus that performs plasma processing is generated by plasma existing in a vacuum apparatus without introducing gas or light unnecessary for manufacturing other than gas necessary for plasma processing. Provided are an apparatus and a method capable of measuring the amount of active species such as ions and radicals.

  Specifically, using a physical property-dependent output measuring device such as a quartz vibrator sensor that can output a substance-dependent output that is dependent on the physical property values such as the viscosity and molecular weight of the gas present in the device, Direct mounting and measurement in plasma to determine physical property dependent output.

  At this time, in the state where there is no obstacle such as a filter with respect to the quartz crystal sensor, all gas phase components in the plasma such as gas molecules, atoms, radicals, and ions arrive. Provides information on all gas phase components. That is, the output at this time includes information on active species in the plasma such as atoms, radicals, and ions.

  On the other hand, when an obstruction with respect to the gas phase component in the plasma is installed in the crystal resonator sensor, the obstruction prevents the plasma gas phase component from reaching the crystal resonator sensor. The degree of inhibition of the gas phase component by the obstacle varies depending on the type of the gas phase component. For example, in hydrogen plasma, particularly hydrogen gas, which is a stable gas molecule, has almost no loss due to collision with a stainless steel obstacle that is a material of a normal vacuum apparatus. On the other hand, the probability of loss of hydrogen radicals (atoms) generated in hydrogen plasma in stainless steel is estimated to be about 15% according to Non-Patent Document 2 above. The reaction probability with a certain solid, that is, the probability of loss at an obstacle is greatly different.

  Therefore, when such an obstacle is placed on the quartz resonator sensor, the arrival of the active species quartz resonator sensor is far more than that of molecules as the typical length or transmittance of the space decreases. It is greatly inhibited. Here, the “representative length of space” is an amount indicating the degree to which the components in the plasma reach the physical property dependent output measuring device. However, the size and shape of the space that it has are usually different, and in the present invention, the size and shape of such a space are important for the arrival of the components in the plasma, so it has a broader meaning. Define as Actually, as an example of “representative length of space”, in addition to transmittance, “nominal element pore size (Swedge Rock company filter catalog)” and “passing grain sphere reference value (Kuraba company HP)” Are used as an expression of filter roughness. When the representative length or transmittance of the space as described above decreases, eventually, a state may occur in which all active species cannot reach the crystal resonator sensor.

  At this time, no active species reach the crystal resonator sensor, and therefore information on the active species is excluded from the crystal resonator sensor output. On the other hand, the gas molecules in the plasma are less reactive with the obstacle than the active species, so even if all the active species cannot reach the quartz crystal sensor, all the gas molecules pass through the obstacle and pass through the crystal. It is possible to reach the transducer sensor. In such a situation, the crystal sensor output provides information only on gas molecules in the plasma.

  Since the gas phase component is composed only of gas molecules and active species, this crystal oscillation can be obtained by removing the crystal oscillator sensor output that provides information on stable gas molecules from the crystal sensor output that provides information on all gas phase components. By the child sensor measurement, it is possible to obtain information on only active species that are difficult to measure by the conventional method.

  The information on the active species obtained here is mainly a relative amount, not an absolute value. However, if this measurement is performed while changing the plasma conditions, the plasma condition dependence of the relative amount of active species can be obtained, which is useful for process management.

  In the measurement with the representative length of the obstacle space changed, if the measurement results in the representative length or transmittance of a range of obstacles other than those with or without the obstacle are almost equal, Since it is assumed that a certain amount of appearance is due to the fact that only a specific active species in the plasma is blocked from reaching the measuring device by the obstacle, this result is used to distinguish the active species in the plasma. It can be measured separately.

  Such a constant value of measurement arises because of the difference in loss due to obstacles even within the same active species. The constant value of the measurement result indicates that the loss caused by the obstacle is larger as the representative length of the obstacle space or the transmittance is larger, that is, the result is a highly reactive active species.

  In the above measurement, it is necessary to change the representative length or transmittance of the obstacle space with respect to the quartz crystal sensor, but such measurement changes the representative length or transmittance of the space such as the filter. This is a simple measurement method compared with the conventional method for measuring active species in plasma because it can be easily realized simply by mounting an obstacle around the quartz resonator sensor.

  Here, the obstacle is a substance that can adjust the representative length or transmittance of the space to the quartz resonator sensor, and specifically, a substance having a filter or mesh structure.

  When this measurement is performed in plasma, the influence of the obstacle on the plasma and the influence of the plasma on the obstacle are taken into consideration, and metals and ceramics are suitable as the obstacle material.

  In this measurement, it is necessary to use an obstacle capable of controlling the representative length or transmittance of the space, but this can be easily adjusted by controlling the transmittance, space length, and space area of the thin film mesh. In this respect, in the thin film mesh, parameters such as transmittance, space length, and space area are uniquely determined in advance, so that these controls are easy.

  By this measurement, it is possible to measure the total amount of active species in the plasma, which is difficult to measure. In addition, when the difference in reactivity of active species can be used, it is possible to measure the type of active species separately. It is necessary to measure all active species by other methods in order to obtain the individual absolute amount of active species and the components and density of all active species, but it is effective for easily grasping the amount of active species. .

  One of the specific physical property dependent outputs can be obtained by the above-described crystal resonator sensor. The output of the crystal resonator sensor changes with these changes because the impedance of the electric circuit including the crystal resonator in the sensor depends on the molecular weight and viscosity of the gas to be measured. Therefore, a physical property-dependent output that depends on the molecular weight and viscosity of the gas can be obtained by using a quartz oscillator sensor.

  By utilizing the fact that the crystal resonator sensor output depends on the molecular weight and viscosity of the gas to be measured, the concentration (partial pressure) of each gas in the mixed gas composed of two kinds of gases can be obtained.

  Such a concentration measuring method in a binary gas mixture has already been patented (see Patent Document 2). However, even when only one type of gas is used as the supply gas, various types of molecules, ions, and radicals are generated and exist in the plasma gas phase due to collision between the supply gas and electrons. Therefore, the concentration of all substances existing in the plasma gas phase cannot be measured only by the above-mentioned Patent Document 2.

  However, if a value that correlates with the amount of active species can be obtained from the physical property-dependent output measured as described above, it will affect the costly and complicated manufacturing apparatus or manufacturing process using conventional light emission and light. The amount of active species can be measured without using a measurement method that gives Further, different types of active species can be separately measured by fractionation by reactivity.

  In the present invention, the measurement with the crystal resonator sensor can be performed by a simple method similar to measuring the pressure, and can be easily applied to a practical manufacturing apparatus. An object of the present invention is to realize an apparatus and method for measuring active species present in plasma that can be performed.

  Furthermore, since the present invention is a measurement method that does not irradiate heat or light when using a piezoelectric element including a crystal resonator, it can safely measure even a highly reactive gas mixture that causes an explosion due to stimulation by heat or light. It is an object of the present invention to provide an apparatus and method for measuring active species present in plasma that does not require an ultraviolet lamp having a specific wavelength for measurement and is easy to maintain.

  In order to solve the above-mentioned problem, the active species amount measuring apparatus of the present invention measures a physical property-dependent output of a gas in a reactor in which plasma is generated, which depends on physical property values other than pressure and temperature. In the active species amount measurement device that measures the amount of chemical species other than molecules, including ions and radicals generated by plasma, that is, the amount of active species, physical property dependent output with an obstacle attached to and detached from the reactor In the case where there is no obstacle in which the obstacle is not mounted on the physical property dependent output measuring device, all the components including active species in the plasma reach the physical property dependent output measuring device, In the case of an obstacle with an object attached, only the active species in the plasma is completely blocked, and the object is the result of measurement by a physical property-dependent output measuring device without an obstacle at the time of plasma generation Characterized by measuring the amount of active species generated by plasma by comparing the measurement result in a physical property dependent output due to the physical properties dependent output measuring device with dependent output and the obstacle.

  Furthermore, in the active species measuring device that can measure the length or transmittance of the obstacle space installed in the physical property dependent output measuring device, measurement within the range of the representative length of the space other than with or without the obstacle. When the result in (2) is constant, this value is compared with the result with or without an obstacle to measure the type of active species.

  In addition, the active species amount measuring apparatus of the present invention measures the physical property-dependent output of the gas in the reactor in which the plasma is generated, depending on the physical property values other than pressure and temperature, so that the chemical species other than molecules can be used. In the active species amount measuring apparatus for measuring the amount of chemical species including ions and radicals generated by plasma or the like, that is, the amount of active species, a physical property-dependent output measuring apparatus without an obstacle in the reaction apparatus. And an obstacle-equipped physical property-dependent output measuring device with an obstacle, and the obstacle is an active species in the plasma when there is no obstacle that does not attach the obstacle to the physical property-dependent output measuring device. In the case where all the components included reach the physical property dependent output measuring device and the obstacle with the obstacle is attached, only active species in the plasma are completely blocked, and the obstacle at the time of plasma generation The amount of active species generated by the plasma is measured by comparing the physical property dependent output, which is a measurement result of the physical property dependent output measuring device without, and the physical property dependent output, which is the measurement result of the physical property dependent output measuring device with an obstacle. It is characterized by doing.

  Furthermore, the active species amount measuring device of the present invention performs measurement with the representative length or transmittance of the obstacle changed with respect to the physical property dependent output measuring device without changing the obstacle. A range of typical lengths of a certain space other than with or without obstacles in the active species measurement device with multiple physical property dependent output measurement devices attached with multiple obstacles with different representative lengths or transmittances In the case where the result in the measurement at is constant, this value is compared with the result at the time of presence or absence of an obstacle, and this is a device that performs measurement by classifying the type of active species.

  Furthermore, in the active species amount measuring apparatus, the present invention can reduce the representative length of the obstacle space or the transmittance to the physical property dependent output measuring apparatus as a measurement result of the physical property dependent output measuring apparatus with an obstacle. By using a value obtained by saturating the measurement result of the physical property dependent output that decreases with the result, only the active species in the plasma are completely shut off, and the result is obtained.

  Furthermore, in the active species amount measuring apparatus, the present invention can increase the representative length of the obstacle space or the transmittance to the physical property-dependent output measuring device as a measurement result of the physical property-dependent output measuring device without an obstacle. A value obtained by saturating the measurement result of the physical property-dependent output that increases with the result is used to obtain a result when all components including active species in the plasma reach the physical property-dependent output measurement device.

  Furthermore, the present invention provides the active species amount measuring apparatus, wherein the physical property dependent output depends on the viscosity and the molecular weight, and the crystal resonator sensor or the spinning rotor is used as the physical property dependent output measuring device for measuring the physical property dependent output. It is characterized by using a gauge.

  Furthermore, the present invention is the above-mentioned active species amount measuring apparatus, wherein the obstacle is a filter made of a metal or an insulator as a material which is not affected by plasma and does not affect the plasma. It has a blocking performance that can block all active species by the quartz crystal sensor.

  In addition, the method for measuring the amount of active species according to the present invention is a chemical species other than molecules, which is generated by plasma, by measuring a physical property-dependent output that depends on a physical property value of a gas in a reactor in which plasma is generated. In the method of measuring the amount of active species that measures the amount of chemical species including ions and radicals, a physical property dependent output measuring device with an obstacle attached and detached is provided in the reactor, and the obstacle is not attached to the obstacle. The physical property dependent output measurement device measures the physical property dependent output when all the components including active species in the plasma reach the physical property dependent output measurement device capable of measuring the physical property dependent output other than pressure and temperature. This is a physical property dependent output measuring device with an obstacle attached to the object, and the physical property dependent output when only the active species in the plasma is completely blocked by the obstacle is measured. The amount of active species generated by the plasma is measured by comparing the physical property dependent output measured by the physical property dependent output measuring device and the physical property dependent output measured by the physical property dependent output measuring device with an obstacle. .

  Furthermore, the method for measuring the amount of active species according to the present invention provides a measurement method in which the representative length or transmittance of an obstacle with respect to a physical property dependent output measuring device is changed, within a range of the representative length of a certain space other than with or without an obstacle. When the result in the measurement of is constant, this value is compared with the result with or without an obstacle, and the measurement is performed by classifying the active species.

  In addition, the method for measuring the amount of active species according to the present invention is a chemical species other than molecules, which is generated by plasma, by measuring a physical property-dependent output that depends on a physical property value of a gas in a reactor in which plasma is generated. In the method for measuring the amount of active species to measure the amount of chemical species including ions and radicals, an obstacle-free physical property-dependent output measuring device without an obstacle in the reactor and an obstacle with an obstacle A physical property-dependent output measuring device that is equipped with a physical property-dependent output measuring device and that is not equipped with the obstacle, and that measures all the components including active species in the plasma other than pressure and temperature. Measure the physical property dependent output when reaching the physical property dependent output measuring device, and with the obstacle equipped physical property dependent output measuring device equipped with the obstacle, only the active species in the plasma can be completely removed by the obstacle Measure the physical property dependent output in case of interruption, and compare the physical property dependent output measured by the physical property dependent output measuring device without obstacles at the time of plasma generation with the physical property dependent output measured by the physical property dependent output measuring device with obstacles Thus, the amount of active species generated by the plasma is measured.

  Furthermore, the method for measuring the amount of active species according to the present invention performs measurement by changing the representative length of the space or the transmittance of the obstacle with respect to the physical property dependent output measuring device without attaching or removing the obstacle. A range of typical lengths of a space other than with or without obstacles in the measurement of active species is provided with multiple physical property-dependent output measurement devices with multiple obstacles with different typical lengths or transmittances. In the case where the result in the measurement at is constant, it is characterized in that this value is compared with the result with or without an obstacle to measure the type of active species.

  Furthermore, the present invention provides a method for measuring the amount of active species, wherein the measurement result of the physical property dependent output measuring device with an obstacle is a reduction in the representative length of the obstacle space or the transmittance to the physical property dependent output measuring device. By using a value obtained by saturating the measurement result of the physical property dependent output that decreases with the result, only the active species in the plasma are completely shut off, and the result is obtained.

  Furthermore, the present invention provides a method for measuring the amount of active species in the above-described method for measuring the representative length of the obstacle or the transmittance to the physical property-dependent output measuring device as a measurement result of the physical property-dependent output measuring device without an obstacle. A value obtained by saturating the measurement result of the physical property-dependent output that increases with the result is used to obtain a result when all components including active species in the plasma reach the physical property-dependent output measurement device.

  Furthermore, the present invention is characterized in that, in the above active species amount measuring method, the physical property dependent output depends on viscosity and molecular weight, and the physical property dependent output device for measuring the physical property dependent output is a crystal vibration. A child sensor or a spinning rotor gauge is used.

  Furthermore, the present invention provides the active species amount measuring method, wherein the obstacle is not affected by the plasma, and is made of a filter made of a metal or an insulator as a material that does not affect the plasma. It is characterized by having a shut-off performance capable of shutting off all the seeds from the quartz crystal sensor.

The apparatus and method for measuring active species present in plasma of the present invention have the following excellent effects.
(1) In plasma using gas as a medium, the active species in the plasma using only a quartz crystal sensor and an absolute pressure gauge in which an obstacle such as a thin film mesh or a filter is attached to the tip of the inside of the container where the plasma exists. The amount can be determined. In this measurement, high-speed measurement is possible without consuming the gas measured at the time of measurement, and it can always be measured even when the pressure of the mixed gas is other than atmospheric pressure or even when the pressure changes.

(2) Furthermore, when using a piezoelectric element including a quartz resonator, it is a measurement method that does not irradiate heat or light, so it can safely measure even highly reactive gas mixtures that cause an explosion due to stimulation by heat or light. be able to. The measurement does not require an ultraviolet lamp having a specific wavelength, is easy to maintain, and can immediately measure its composition in response to changes in gas composition.

It is a figure explaining the Example of the decomposition rate measuring apparatus and measuring method which concern on this invention. It is a figure which shows the change of the physical property dependence output at the time of changing a pressure about the kind of substance, (a) shows the change of a crystal oscillator sensor output, (b) is the change of the display pressure of a crystal oscillator pressure gauge. (C) is a figure which shows the change of the instruction | indication pressure of a spinning rotor gauge. It is a figure which shows the temperature dependence of a crystal oscillator sensor output. It is a figure which shows a time-dependent change of the quartz-crystal vibrator sensor calibration value at the time of generating / stopping hydrogen plasma ((circle): No filter,-A filter exists). It is an example of the filter with which the crystal oscillator sensor was mounted | worn. It is a figure which shows the filter space representative length dependence of the quartz oscillator sensor calibration value variation | change_quantity by plasma.

  DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS With reference to the drawings, the best mode of a measurement apparatus and method for active species present in plasma will be described in detail based on examples.

  The apparatus and method for measuring active species present in plasma according to the present invention provides a method and apparatus for measuring the amount of active species by plasma with a simpler method and apparatus than conventional plasma diagnostic methods using light. To do.

  Specifically, the physical property dependent output that depends on the physical properties of the plasma in the plasma device is measured, and the vacuum is determined from the difference between the result measured in the state without the obstacle and the result measured in the state with the obstacle. The amount of active species present in the apparatus is determined.

  The state without an obstacle is a state in which the amount of change in the property-dependent output due to the plasma is maximized, and the change in the property-dependent output due to the plasma at this time is a change due to the stable gas and active species present in the plasma.

  The state with an obstacle is a state in which the amount of change in the property-dependent output due to the plasma is minimized, and the change in the property-dependent output due to the plasma at this time is a change due to the stable gas existing in the plasma.

  The physical property values are viscosity and molecular weight, and the crystal oscillator sensor that can measure the amount depending on the viscosity and the measurement by the absolute pressure gauge and thermometer, and the output of the crystal oscillator sensor when plasma is generated, the pressure And the physical property dependent output in the plasma is measured by performing temperature calibration.

  As shown in FIG. 1, the plasma processing apparatus includes a reaction apparatus 3 of the plasma apparatus, a plasma electrode 5 projecting from the reaction apparatus 3 of the plasma apparatus that supplies a high frequency voltage from a high frequency power supply 10, and a plurality of types of supply gases. A plurality of introduction pipes having a plurality of gas flow rate control devices (mass flow controllers: MFC) 7, a quartz vibrator sensor 1 having a size of 1 cm or less, a diaphragm pressure gauge 2, and a work support as a product A table 15 and a pressure control valve 9 are provided.

  As an example applied to the plasma apparatus in such a plasma processing apparatus, an embodiment of a measuring apparatus and method for active species present in plasma of the present invention will be described.

  The active species measuring apparatus of this embodiment is one of the physical property dependent outputs from the plasma apparatus, and pressure correction means for obtaining a “quartz crystal sensor calibration value” which is an amount depending on a gas component in the gas phase. 4 and temperature correction means 6 are provided. Specifically, the pressure correction unit 4 and the temperature correction unit 6 use a computer 17 having an input unit, an output unit, a CPU, a storage device, and the like (not shown).

  This pressure correction and temperature correction are mainly performed on the result of using the physical property dependent output measuring apparatus with an obstacle. The pressure correction means and the temperature correction means shown below are respectively described in Patent Document 4 above. The same.

  In addition, since the influence of the pressure and temperature with respect to the result in the physical property dependence output measuring apparatus without an obstacle is small, correction by these is usually unnecessary.

  The quartz vibrator sensor 1 and the diaphragm pressure gauge 2 are connected to the input unit of the computer 17 via a data line. The calibration value of the quartz crystal sensor 1 is obtained by directly using the data obtained by the pressure correction unit 4 or, if necessary, by using the data obtained by processing the data by the temperature correction unit 6. It is done.

  The pressure correction means 4 inputs measurement data from the quartz oscillator sensor 1 and the diaphragm pressure gauge 2 and corrects the influence of absolute pressure from the output of the quartz oscillator sensor 1. If the temperature change during measurement is large, the pressure-corrected value (pressure correction value) is output to the temperature correction means 6, and if not, this value is used as it is as a calibration value for the crystal oscillator sensor. .

  The temperature correction means 6 inputs the pressure correction value and information on the resonance frequency of the crystal resonator having a large correlation with the temperature generated from the crystal resonator sensor 1 or the ambient temperature obtained by actual measurement. The calibration value of the crystal resonator sensor is obtained by performing correction.

  FIG. 2A is a graph showing the absolute pressure dependence of the quartz vibrator sensor output in each gas, and FIG. 2B is a graph showing the absolute pressure dependence of the display pressure of the quartz vibrator pressure gauge. FIG. 2C is a graph showing the absolute pressure dependence of the indicated pressure of the spinning rotor gauge.

  As shown in FIG. 2A, the output of the crystal resonator sensor 1 (not a crystal resonator sensor but a crystal friction vacuum gauge or a spinning rotor gauge) at the same absolute pressure differs depending on the type of gas. By utilizing it, the amount of active species in the plasma can be measured.

  Note that the output is not limited to the pressures in the ranges of FIGS. 2A to 2C, and the output is different depending on the type of gas at the same absolute pressure for all pressures. Even in the pressure range, it is possible to measure the component change in the plasma.

  Here, the quartz frictional pressure gauge uses a built-in quartz oscillator sensor that is oscillated by electricity, and that the resistance that occurs when gas molecules collide with this sensor depends on the pressure and viscosity of the gas. It is a pressure gauge that performs measurement by taking it out as a voltage of an electric circuit including the sensor.

  The spinning rotor gauge uses the fact that the power is stopped after a steel ball or the like is rotated at a high speed in the gas, and the rate of decrease in the rotational speed after the power is stopped is also dependent on the pressure and viscosity of the gas. It is a pressure gauge.

  The component measurement in the present invention utilizes the fact that the output of the quartz vibrator sensor (or quartz friction vacuum gauge or spinning rotor gauge) is different when the absolute pressure is the same depending on the type of gas. In order to obtain a measurement result by the obtained physical property dependent measuring apparatus with an obstacle, it is necessary to measure with both the quartz vibrator sensor 1 and the diaphragm pressure gauge 2. When there is no substantial change in absolute pressure as under atmospheric pressure, measurement can be performed by measuring only the crystal resonator sensor 1.

  By removing the influence of the absolute pressure from the output of the crystal resonator sensor 1, the crystal resonator sensor calibration value is obtained. Specifically, first, the absolute pressure dependence of the crystal resonator sensor output as shown in FIG. 2A is examined, and a pressure coefficient which is a change rate with respect to the pressure of the output is obtained. This pressure coefficient can be used to correct the change in the output due to the absolute pressure change.

  If the measurement device output, measurement pressure, and pressure coefficient are V, P, and C, respectively, the pressure correction value Vp is Vp = V−C × (P−) with respect to the absolute pressure P0 at an arbitrary point. P0). This pressure-corrected value Vp is an amount that correlates with the molecular weight and viscosity of the gas, and the change in the gas component can be measured using this value.

  In order to correct the influence of the temperature, the ambient temperature at the measurement location of the crystal resonator sensor 1 is simultaneously measured by the thermometer 18, or from the information on the resonance frequency having a large correlation with the temperature obtained from the crystal resonator sensor 1, The temperature coefficient of the crystal oscillator sensor output as shown in FIG. 3 is obtained and temperature correction is performed. FIG. 3 is a graph showing the measured ambient temperature dependence of the crystal resonator output under a constant pressure condition.

  Since the correlation between the quartz crystal sensor output and temperature is constant, the quartz crystal sensor output value is calculated using the previously calculated quartz crystal sensor output-the slope of the temperature line, that is, the temperature coefficient of the quartz crystal sensor output. By calibrating, it is possible to eliminate the influence of temperature change and obtain the quartz crystal sensor calibration value.

  If the measurement device output, measurement temperature, and temperature coefficient are V, T, and K, respectively, the temperature correction value Vt is Vt = V−K × (T−T0) with respect to the absolute temperature T0 at an arbitrary point. ).

  Since the vibration frequency of the crystal resonator has temperature dependency, the temperature coefficient of the crystal resonator sensor output can be obtained from the temperature dependency of the vibration frequency.

  A method for determining the amount of active species present in the plasma apparatus using the “crystal resonator sensor calibration value”, which is a physical property dependent output, obtained by the above method is as follows.

  For the output from the physical property-dependent output measuring device without an obstacle, the values as they are may be used without performing the above pressure and temperature correction.

  In the case where hydrogen is actually used, the result when no obstacle is attached to the crystal resonator sensor is indicated by a circle in FIG. FIG. 4 is a plot of quartz resonator sensor calibration values against time on the horizontal axis. As can be seen from FIG. 4, the “quartz crystal sensor calibration value” changes as the plasma is generated. This amount of change of the “quartz crystal sensor calibration value” due to the plasma is hereinafter referred to as “quartz crystal sensor calibration value change amount”.

  “Quartz crystal sensor calibration value change amount” at this time is measured in a state where all the components in the plasma reach the physical property-dependent output measuring device without obstacles. It is. Therefore, this is hereinafter referred to as “maximum crystal resonator sensor calibration value change amount”. This value is information due to changes in all gas phase components in the plasma.

  Next, a filter as shown in FIG. 5 is attached to the quartz resonator sensor as an obstacle, and measurement is performed in the same manner. The result is simultaneously indicated by a mark ● in FIG. 4. Although the “crystal oscillator sensor calibration value change amount” is decreased due to the increase in transmittance, the change with time is similar to the case without an obstacle.

  Subsequently, the measurement with the obstacle attached is performed until the transmittance is gradually lowered and the “crystal oscillator sensor calibration value change amount” by the plasma becomes constant.

  FIG. 6 is a plot of “quartz crystal sensor calibration value change amount” versus the filter space representative length in the above measurement. In FIG. 6, the smallest “quartz crystal sensor calibration value variation” is the “minimum quartz crystal sensor calibration value variation”.

  The “maximum crystal resonator sensor calibration value change amount” obtained above is information on changes in all gas phase components in the plasma. On the other hand, the “minimum crystal resonator sensor calibration value change amount” is due to a change in the stable gas present in the plasma. Therefore, the difference between these two “variations” is due to changes in all active species other than stable gas molecules in the plasma. Of course, since there are no active species before plasma generation, the amount of all active species in the plasma is determined from this.

  In addition, in the range of 100 to 400 microns in the horizontal axis in FIG. 6, the “quartz crystal sensor calibration value change amount” is almost constant, but this is only the active species having high reactivity as described in paragraph 0022. This is because it reacts with the obstacle and disappears, and other active species reach the quartz crystal sensor without reacting. Here, when the constant value of the “quartz crystal sensor calibration value change amount” in the range of 100 to 400 microns is defined as the “specific crystal vibrator sensor calibration value change amount”, the “specific crystal vibration” is described in more detail than paragraph 0087. The amount of highly reactive active species from the comparison of the change amount of the calibration value of the child sensor and the change amount of the calibration value of the maximum quartz crystal sensor. The amount of the low-reactive active species can be determined separately from the comparison with the “sensor calibration value change amount”. Although these amounts are relative amounts, it is beneficial to increase the amount of information if the same active species is measured by being classified into several types.

  Here, the transmittance at which the “crystal oscillator sensor calibration value change amount” is minimum is a state in which all active species other than the stable gas in the plasma are inhibited and disappeared by obstacles and do not reach the crystal sensor. However, it is not self-evident in advance what kind of transmittance and shape the obstacle is achieved when the obstacle is mounted. However, since the typical length of the space is expected to be shorter than the mean free path of the gas determined by the pressure, the representative length or transmittance of the obstacle space is reduced within this mean free path. As a result, the “minimum crystal resonator sensor calibration value change amount” is obtained.

  The physical property quantities that depend on the physical property-dependent output required by the crystal oscillator sensor are viscosity and molecular weight. For example, the viscosity is measured by a crystal oscillator pressure gauge and a spinning rotor gauge in addition to the crystal oscillator sensor. It is calculated by removing the influence of absolute pressure measured with an absolute pressure gauge such as a diaphragm vacuum gauge.

  Since the above-mentioned quartz oscillator sensor is small and can be moved in the apparatus, it can be moved and measured with respect to the fixed plasma electrode in the apparatus. When determining the amount of active species, for example, for discharges occurring between parallel plate electrodes, it is optimal to measure between the electrodes, but if this is not possible under some conditions, it should be as close as possible to the plasma electrode. It is desirable to measure with.

  In this case, if the distance to the electrodes of the quartz crystal sensor is smaller than the distance between the parallel plates, the direct influence of the plasma on the quartz crystal sensor becomes large and the measurement becomes inaccurate. It is preferable to measure at a position separated by the distance between the plate electrodes.

  At this time, the effect of temperature becomes prominent in the measurement near the plasma electrode, but in order to correct this effect, another temperature measurement is performed, or the resonance frequency obtained from the quartz vibrator sensor and highly correlated with the temperature is measured. As described above, the physical property value output is calibrated by correcting the temperature to obtain the quartz resonator sensor calibration value.

  Effective information can be obtained from the information on the relative amount of the active species obtained as described above, because it can contribute to high performance of the plasma treatment.

  The amount of active species can be obtained in real time at any point in time when plasma is generated by using a measuring device equipped with a physical property dependent output measuring device with and without an obstacle, and monitoring using this becomes possible. If necessary, it can be produced while adjusting the various conditions while maintaining the desired decomposition rate.

  In addition, when this real-time property is used, it is possible to control conditions in the plasma. Since the amount of active species in the plasma is one of the important conditions in the production conditions, if this is known, the product can be sophisticated by modulating the amount in real time. In addition, the product can be made uniform and uniform. When an abnormal discharge of plasma occurs, the amount of active species in the plasma changes greatly. By monitoring this abnormal change, it is possible to detect abnormal operation and stop of plasma at an early stage.

  Of these conditions, all except the temperature-related conditions can be quickly controlled by an electrical signal. On the other hand, since the measurement output by this measuring apparatus can also be output as an electrical signal, quick result output and quick control by this are possible.

  If the measurement method of the present invention is used to constantly measure changes in gas components during plasma operation, even if the amount of active species initially assumed changes due to some abnormality, the change can be detected by this measurement method. When a significant difference appears in the gas component change, the amount of active species can be maintained at a desired value by applying feedback to the flow rate of the supply gas.

  By using an active species amount measuring apparatus capable of rapid measurement, a simple, small and low-priced film thickness / deposition rate / film structure automatic control apparatus can be provided. In particular, in the silane-hydrogen binary system used in the thin film silicon manufacturing process, the amount of active species affects important physical properties such as the structure of the film to be manufactured (amorphous or microcrystalline) and light stability. If the correlation between the physical properties and the decomposition rate of the supply gas is obtained, the characteristics of the product can be kept constant by measuring the amount of active species by this method during the actual process.

  Similarly, if the correlation between various physical properties such as film thickness, electrical properties, etching ratio, etc. of the obtained product and the amount of active species is obtained, these correlations are used during actual process to control process conditions. be able to.

  In etching plasmas using fluorocarbon and fluorosulfide gases, correlations between various physical properties such as etching ratio and the amount of active species are obtained, and process conditions are controlled using these correlations during actual processes. Thus, the etching process can be improved.

  The present invention can also be used for gas plasma using any kind of gas such as hydrocarbon plasma such as methane, germane gas plasma, and mixed gas plasma thereof for producing diamond thin film, carbon nanotube, hard material and the like. .

In addition to plasma, the present invention can measure the amount of active species generated by light, heat, electrons, radiation and the like.

  The best mode for carrying out the measurement apparatus and method for active species present in plasma according to the present invention has been described above based on the embodiments. However, the present invention is not limited to such embodiments. Needless to say, there are various embodiments within the scope of the technical matters described in the claims.

  Since the apparatus and method for measuring active species present in plasma according to the present invention has the above-described configuration, it can be applied to various manufacturing apparatuses that perform processing, machining, and manufacturing using the plasma apparatus.

DESCRIPTION OF SYMBOLS 1 Crystal oscillator sensor 2 Diaphragm pressure gauge 3 Reaction apparatus of plasma apparatus 4 Pressure correction means 5 Plasma electrode 6 Temperature correction means 7 Gas flow control apparatus (mass flow controller: MFC)
8 Heater 9 Pressure control valve 10 High frequency power source 12 Work 15 Work support base 17 Computer 18 Thermometer

Claims (16)

By measuring the physical property dependent output of the gas in the reactor where the plasma is generated, which depends on the physical property values other than pressure and temperature, chemical species other than molecules, ions and radicals generated by the plasma can be detected. In the active species amount measuring device for measuring the amount of the chemical species including the active species,
A physical property-dependent output measuring device with an obstacle attached and detached in the reaction device,
When there is no obstacle that does not attach the obstacle to the physical property dependent output measuring device, all the components including active species in the plasma reach the physical property dependent output measuring device and the obstacle is attached to the obstacle. In the case of things, only active species in the plasma are completely blocked,
Active species generated by plasma by comparing the physical property-dependent output, which is the measurement result of the physical property-dependent output measurement device without obstacles, and the physical property-dependent output, which is the measurement result of the physical property-dependent output measurement device with obstacles, at the time of plasma generation A device for measuring the amount of active species, characterized in that the amount of the active species is measured.   The active species amount measuring apparatus according to claim 1, wherein the measurement is performed by changing the representative length or transmittance of the obstacle space with respect to the physical property dependent output measuring apparatus, and the representative length of a certain space other than with or without the obstacle. When the result in the measurement within a certain range is constant, the active species measuring apparatus is characterized in that this value is compared with the result when there is an obstacle or not, and the type of the active species is measured separately. . Ions and radicals that are chemical species other than molecules and are generated by plasma, etc. by measuring the physical property-dependent output of the gas in the reactor where the plasma is generated, which depends on the physical property values other than pressure and temperature. In an active species amount measuring device for measuring the amount of a chemical species containing, that is, an active species,
There is an obstacle-free physical property-dependent output measurement device that does not mount obstacles in the reactor and a physical property-dependent output measurement device with obstacles that is equipped with obstacles,
When there is no obstacle that does not attach the obstacle to the physical property dependent output measuring device, all the components including active species in the plasma reach the physical property dependent output measuring device and the obstacle is attached to the obstacle. In the case of things, only active species in the plasma are completely blocked,
Generated by plasma by comparing the physical property dependent output, which is a measurement result by a physical property dependent output measuring device without an obstacle, at the time of plasma generation and the physical property dependent output, which is a measurement result by a physical property dependent output measuring device with an obstacle. An active species amount measuring apparatus for measuring the amount of active species.   The active species amount measuring apparatus according to claim 3, wherein the measurement is performed without changing the representative length or transmittance of the obstacle space with respect to the physical property dependent output measuring apparatus without attaching or removing the obstacle. In addition, a plurality of physical property-dependent output measuring devices with multiple obstacles with different representative lengths or transmittances are attached, and measurement within a range of representative lengths other than with or without obstacles A device for measuring the amount of active species, characterized in that, when the result is constant, this value is compared with the result when an obstacle is present or not, so that the type of active species is measured separately.   As the measurement result of the physical property dependent output measuring device with an obstacle, a value obtained by saturating the representative length of the obstacle or the measurement result of the physical property dependent output that decreases with a decrease in the transmittance to the physical property dependent output measuring device is used. The active species amount measuring device according to any one of claims 1 to 4, wherein only the active species in the plasma are completely blocked.   As a measurement result of the physical property-dependent output measuring device without the obstacle, a value obtained by saturating the measurement result of the physical property-dependent output that increases as the representative length of the obstacle or the transmittance to the physical property-dependent output measurement device increases is used. The active species amount measuring apparatus according to any one of claims 1 to 4, wherein all the components including active species in the plasma reach a physical property dependent output measuring apparatus.   5. The physical property dependent output depends on viscosity and molecular weight, and a crystal resonator sensor or a spinning rotor gauge is used as a physical property dependent output measuring device for measuring the physical property dependent output. The active species amount measuring apparatus according to any one of the above.   The obstacle is a filter made of a metal or an insulator as a material which is not affected by plasma and does not affect the plasma, and blocks all active species caused by plasma from the quartz crystal sensor. The active species amount measuring apparatus according to claim 1, wherein the active species amount measuring apparatus according to claim 1 has a blocking performance. By measuring the physical property dependent output that depends on the physical property value of the gas in the reactor where the plasma is generated, the amount of chemical species other than molecules, including ions and radicals generated by the plasma, can be determined. In the method for measuring the amount of active species to be measured,
A physical property-dependent output measuring device with an obstacle attached and detached in the reaction device,
In the physical property-dependent output measurement device without obstacles, in which all components including active species in plasma reach the physical property-dependent output measurement device capable of measuring physical property-dependent outputs other than pressure and temperature. Measure the physical property dependent output of, and measure the physical property dependent output when only the active species in the plasma is completely blocked by the obstacle in the obstacle-dependent physical property dependent output measuring device equipped with the obstacle,
The amount of active species generated by the plasma is compared by comparing the physical property dependent output measured by the physical property dependent output measuring device without obstacles at the time of plasma generation with the physical property dependent output measured by the physical property dependent output measuring device with obstacles. A method for measuring the amount of active species, characterized by measuring.   The active species amount measuring method according to claim 9, wherein the measurement is performed by changing the representative length or transmittance of the obstacle space with respect to the physical property dependent output measuring device, and the representative length of a certain space other than with or without the obstacle. A method for measuring the amount of active species, characterized in that when the result in the measurement in the range of is constant, this value is compared with the result with or without an obstacle, and the type of active species is measured separately . By measuring the physical property dependent output that depends on the physical property value of the gas in the reactor where the plasma is generated, the amount of chemical species other than molecules, including ions and radicals generated by the plasma, can be determined. In the method for measuring the amount of active species to be measured,
There is an obstacle-free physical property-dependent output measurement device that does not mount obstacles in the reactor and a physical property-dependent output measurement device with obstacles that is equipped with obstacles,
In the physical property-dependent output measurement device without obstacles, in which all components including active species in plasma reach the physical property-dependent output measurement device capable of measuring physical property-dependent outputs other than pressure and temperature. Measure the physical property dependent output of, and measure the physical property dependent output when only the active species in the plasma is completely blocked by the obstacle in the obstacle-dependent physical property dependent output measuring device equipped with the obstacle,
The amount of active species generated by the plasma is compared by comparing the physical property dependent output measured by the physical property dependent output measuring device without obstacles at the time of plasma generation with the physical property dependent output measured by the physical property dependent output measuring device with obstacles. A method for measuring the amount of active species, characterized by measuring.   The active species amount measuring method according to claim 11, wherein the measurement is performed without changing the representative length or transmittance of the obstacle with respect to the physical property dependent output measuring device without attaching or detaching the obstacle. In addition, a plurality of physical property-dependent output measuring devices with multiple obstacles with different representative lengths or transmittances are attached, and measurement within a range of representative lengths other than with or without obstacles A method for measuring the amount of active species, characterized in that when the result is constant, this value is compared with the result with or without an obstacle, and the type of active species is measured separately.   As the measurement result of the physical property dependent output measuring device with an obstacle, a value obtained by saturating the representative result of the obstacle or the measurement result of the physical property dependent output that decreases as the transmittance to the physical property dependent output measuring device decreases is plasma. The method for measuring the amount of active species according to any one of claims 9 to 12, wherein only the active species therein are completely blocked.   As a measurement result of the physical property-dependent output measuring device without the obstacle, a value obtained by saturating the measurement result of the physical property-dependent output that increases as the representative length of the obstacle or the transmittance to the physical property-dependent output measurement device increases is plasma. The method for measuring the amount of active species according to any one of claims 9 to 12, wherein all the components including active species therein are obtained as a result when they reach the physical property dependent output measuring device.   The physical property dependent output is dependent on viscosity and molecular weight, and the physical property dependent output device for measuring the physical property dependent output uses a quartz resonator sensor or a spinning rotor gauge. The method for measuring the amount of active species according to any one of claims 9 to 12.   The obstruction is not affected by plasma, and is a filter made of metal or an insulator as a material that does not affect the plasma, so that all active species due to plasma can be blocked from the quartz crystal sensor. The method for measuring the amount of active species according to any one of claims 9 to 12, characterized by having a blocking performance that can be achieved.