JPH09306842A - In-process film forming monitor device and vacuum monitor device and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable forming film monitoring by a single calibration curve by a method wherein a film forming monitor value is processed to be standardized by using the quotient or function thereof produced by dividing a sputtering gas pressure by a voltage applied to the sputtering step so as to detect the film forming rate by the particles splashing in a film forming device according to the standardized monitor value. SOLUTION: The particles splashed from a film forming particle source adhere to a substrate while expending the photoenergy in the case of passing through a detecting light flux 14 so as to decrease the intensity of light flux after passing through a particle splashing region 13 than that before incoming to said region 13. Next, the intensity ratio after passing through the splashing region 13 and before starting the film formation step is processed to compute the relative value for time integrating the value to compute the thick film value. At this time, if the difference in the distance between a target and a substrate is notable, the splashing rate of the particles can be computed by the inverse number of the quotient dividing a sputtering pressure by a sputtering voltage thereby enabling a monitor to be applied using the same calibration curve even for the film forming steps meeting the variable sputtering requirements by correcting the sputtering requirements using said splashing rate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an in-process film forming monitoring apparatus, a vacuum monitoring apparatus and a monitoring method capable of in-process online control in a film forming apparatus.

[0002]

2. Description of the Related Art In recent years, film formation using a film forming apparatus is an indispensable element in the semiconductor industry, and in particular, the need to accurately control the film formation has increased. As a film thickness control in a conventional film forming apparatus, a method has been mainly used in which the film thickness is measured by off-line measurement and the time is controlled based on the relationship with an operating parameter at the time of film formation. As the in-process film thickness monitor, there is also a case where a crystal oscillator monitoring method or a film deposition rate control using an atomic absorption method is performed.

A film forming rate control device by the atomic absorption method in the conventional film forming device will be described below. FIG.
Shows the structure of a conventional atomic absorption film formation rate control device. In FIG. 4, a photodetector 3 including a light source 1 and an optical filter 2 that transmits only the characteristic wavelength light of scattered particles
Is insulated and fixed to a vacuum chamber 6 having a film-forming particle source 4 and a substrate 5 for forming a film therein. A signal is sent from the output of the photodetector 3 to a comparator 7 which judges the magnitude relation with a preset voltage value. The judgment result of the comparator 7 is connected so that it can be fed back to the input power source 8 of the vacuum vapor deposition device.

The operation of the film-forming rate control device by the atomic absorption method in the film-forming device constructed as described above will be described. First, energy is introduced from the input power source 8 to the film forming particle source 4 in the vacuum chamber 6, the substance of the film forming particle source 4 is evaporated, and the scattered particles adhere to the substrate 5 to form a film. . In this state, when the light beam 9 from the light source 1 including the characteristic wavelength of the substance of the film forming particle source 4 passes through the particle scattering region in the vacuum container 6, the light beam intensity is attenuated in correlation with the number of particles existing in the light beam 9. To do. The rate of this attenuation has a strong correlation with the film forming rate, and the attenuation rate when the film forming rate was used was investigated in advance, and the luminous flux intensity after passing through the optical filter 2 was measured using the photodetector 3. Assuming that the ratio of the light intensity immediately before the start of vapor deposition and the light intensity during vapor deposition is the attenuation rate, the magnitude relationship between the attenuation rate at the film formation rate examined in advance is compared by the comparator 7, and if the attenuation rate is large, The power of the input power source 8 is decreased, and when the power is small, the power of the input power source 8 is increased.

In this way, a film having a predetermined film thickness can be formed by controlling the input power source and controlling the film forming time so that the film forming rate falls within a certain range. Here, there is a case where the power source of the light source 1 is driven by the following method in order to remove a noise component generated due to the inclusion of external light or the like in the light beam received by the photodetector 2. First, the TTL having a constant frequency in the light source power source 10
A rectangular wave of a level is formed, and this is amplified and used as the lighting voltage of the lamp to drive the lamp. Further, the signal obtained by the photodetector 3 is input to the phase detector 11, and the TTL
There is also a case where noise is removed from the signal at the time when the lamp is turned on and the signal at the time when the lamp is not turned on by performing phase comparison using the level rectangular wave as a reference signal.

[0006]

However, the above-mentioned conventional structure has the following problems. The relationship between the attenuation rate of the light from the light source and the film forming rate is as shown in FIG. 5 when the characteristic parameters of the film forming apparatus and the arrangement of the monitoring system are determined. Here, originally, the atomic absorption method is to measure the density of atoms in a light flux by absorbing light having a characteristic wavelength of the particles in a particle group, and originally, the film formation rate is obtained by multiplying the density by the particle velocity. If this method is applied to a sputtering apparatus, the particle velocity may change extremely depending on the sputtering pressure, the applied voltage, etc. even if the apparatus configuration is the same. For this reason, a calibration curve was required for each sputtering parameter such as sputtering pressure even with the same device configuration. In addition, even if the same sputtering parameters are used, a slight change in the degree of vacuum may affect high-precision measurement.

In view of the above problems, the present invention enables film formation monitoring with a single calibration curve, and an in-process film formation monitor and a vacuum monitor capable of measuring a local vacuum degree by an atomic absorption method. It aims at providing those monitoring methods.

[0008]

In order to achieve the above object, an in-process film forming monitor of the present invention is a sputtering film forming apparatus for scattering particles, and a film forming monitor applying an atomic absorption method, and a film forming monitor. A vacuum gauge that can measure the sputtering gas pressure in the atmosphere and output it.
A voltage measuring device capable of measuring a voltage applied to a sputtering target, and an arithmetic means capable of standardizing a film formation monitor value by a quotient obtained by dividing a sputtering gas pressure by a sputtering voltage or a function thereof, and the film formation based on the standard value. This is a configuration for detecting the rate at which a film is formed by particles scattered in the apparatus.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The first structure of the in-process film formation monitoring apparatus of the present invention is a sputtering film forming apparatus for scattering particles, and a film forming monitor to which an atomic absorption method is applied and a film forming atmosphere A vacuum gauge capable of measuring the sputtering gas pressure and outputting the measured sputtering gas pressure, a voltage measuring device capable of measuring the voltage applied to the sputtering target, and a quotient obtained by dividing the sputtering gas pressure by the voltage applied to the sputtering or It is characterized in that it is provided with an arithmetic means capable of standardizing the film formation monitor value by the function, and detects the rate of film formation by particles scattered in the film formation apparatus based on the standard value.

The second structure of the in-process film formation monitoring apparatus of the present invention is a sputtering film formation apparatus for scattering particles, and a film formation monitor applying an atomic absorption method and particles emitted from a light source in the film formation monitor. The intensity component of the optical signal of the characteristic wavelength of the flying particles absorbed in the flying region and the intensity component of each wavelength including the light of the characteristic wavelength of the flying particles generated in the flying region of the sputtered particle can be measured separately. An optical measurement system and a calculation means capable of deriving the number of particles in the ground state and the number of particles in the excited state and the plasma parameters of the sputtering gas flying based on these measured values, the physical quantity in the film forming atmosphere, and The number of flying particles in the ground and excited states, and
It is characterized in that the film forming rate and the film forming thickness are detected.

The first monitoring method of the present invention is a sputtering film forming apparatus for scattering particles to obtain a film forming monitor value by a film forming monitor to which an atomic absorption method is applied.
The sputtering gas pressure in the film forming atmosphere is measured, the voltage applied to the sputtering target is measured, the quotient of the sputtering gas pressure at each time divided by the sputtering voltage is obtained, and the film forming monitor value at each time is obtained. The sputtering gas pressure is divided by the quotient divided by the sputtering voltage or its function is standardized, and by multiplying this by a constant determined for each device, the film is formed by particles scattered in the film forming device based on the specified value. It is characterized by detecting the rate.

Further, the second monitoring method of the present invention is a sputtering film forming apparatus for scattering particles, wherein flying particles emitted from a light source in a film forming monitor to which an atomic absorption method is applied and absorbed in a particle flying region are absorbed. The intensity component of the optical signal of the characteristic wavelength and the intensity component of each wavelength including the light of the characteristic wavelength of the flying particles generated in the flying region of the sputtered particle are measured separately, and the flight is performed based on these measured values. The number of particles in the ground state and the number of particles in the excited state, and the plasma parameters of the sputtering gas are derived, and the physical quantity in the film forming atmosphere and the number of flying particles in the ground state and the excited state, the film forming rate, and the film forming It is characterized by detecting the thickness.

Further, the vacuum monitor device of the present invention is a vacuum device in which a light flux emitted from a light source including at least one of characteristic wavelengths of molecules or atoms of one or more gas existing in a particle flight region. And an optical system configured to pass through a vacuum region, and separate only the intensity component of the characteristic wavelength light of the molecule or atom of the gas after passing through the particle flying region, and further generate inside the flying particle region or externally. A light intensity measuring system capable of separating and measuring light intensity components of the same wavelength of the noise light of the above, and before entering into a film forming atmosphere in which only characteristic wavelengths of the molecules or atoms of the sputtering gas are separated After passing through the atmosphere, there is provided an arithmetic means capable of taking the ratio of the respective light intensities and the logarithm of the ratio of the light intensities, and the gas pressure and the gas partial pressure in the vacuum device are calculated by the logarithmic value. Characterized in that it out.

Another monitoring method of the present invention emits a light source including at least one of characteristic wavelengths of molecules or atoms of one or more gas existing in a particle flight region in a vacuum apparatus. An optical system configured so that the light flux can pass through a vacuum region and only the intensity component of the characteristic wavelength light of the molecule or atom of the gas after passing through the particle flight region are separated and further generated inside the flight particle region. A light intensity measurement system capable of separating and measuring light intensity components of the same wavelength of external noise light is installed, and before entering into a film forming atmosphere in which only characteristic wavelengths of the molecules or atoms of the sputtering gas are separated. After passing through the film forming atmosphere, the ratio of the respective light intensities and the logarithm of the ratio of the light intensities are taken, and the respective gas pressure and gas partial pressure in the vacuum device are detected by the logarithmic value.

As described above, the in-process film formation monitoring apparatus of the present invention enables the film formation monitoring with a single calibration curve by accurately measuring the sputtering pressure, the sputtering voltage and the like and correcting the absorbance. To do. The speed of the film-forming particles in sputtering is considered to be a function of the quotient of the sputtering pressure divided by the sputtering voltage, so correction is performed to improve the accuracy by eliminating the unstable factor of particle speed. Therefore, it becomes possible to greatly improve the practical convenience of using one calibration curve. Further, at this time, it was very difficult to measure the gas pressure in the sputtering region with high accuracy, but focusing on the light absorption by the gas, introducing the characteristic wavelength light of the gas atoms or molecules into the vacuum region, It is possible to measure the local gas pressure with high accuracy by the absorbance here.

(Embodiment 1) A case where the in-process film formation monitoring apparatus of the first embodiment of the present invention is applied to a magnetron sputtering apparatus will be described below with reference to the drawings. FIG. 1 shows the outline of the configuration in the case where the in-process film formation monitoring apparatus in the first embodiment of the present invention is applied to a magnetron sputtering apparatus.

In FIG. 1, a monitoring device 12 has a light source 1 capable of emitting a light beam containing a characteristic wavelength of scattered particles, and a light beam 9 emitted from the light source 1 passes through a particle scattering area 13 and is detected by a photodetector 3. The exploration light intensity 23 is measured.
Further, the degree of vacuum obtained by the vacuum gauge 51 attached to the vacuum container 6 is output as an electric signal 52, the potential difference 53 between the sputter target 4 and the vacuum container 6 is output from the voltage measuring device 52, and these signals are output. An online connection is made to a computing device 24 for computing. When the particles scattered from the film-forming particle source 4 in the vacuum container 6 adhere to a substrate (not shown) to form a thin film, the scattered particles pass through the exploration light beam 14 and the ratio of absorption of light energy is Measurement is performed, the film forming rate is estimated, and the degree of vacuum and the sputtering voltage are corrected.

The operation of the in-process film thickness control device configured as described above will be described. First, the particles scattered from the film-forming particle source 4 in the vacuum container 6 adhere to the substrate and are obtained as a film. When passing through the exploration light beam 14, the light energy in the exploration light beam 14 is taken away and Scattered area 13
The intensity after passing through is less than that before incidence. By taking the ratio of the intensity of the exploration light 14 after passing through the particle scattering region 13 and the intensity before the start of film formation, it is possible to obtain a value that correlates with the absorption ratio, and by integrating this over time from the start of film formation It is possible to obtain the film thickness. Here, in the case where the distance between the target and the substrate is very large as in the present example, the experimental result in which the flying speed of particles can be described by the reciprocal of the quotient obtained by dividing the sputtering pressure by the sputtering voltage was obtained. By making corrections by the number, the monitor can be used with the same calibration curve even for film formation with different sputtering conditions.

Depending on the apparatus configuration such as the distance between the sputtering target and the substrate, it may not be the reciprocal of the quotient obtained by dividing the sputtering pressure by the sputtering voltage, but may be another function of the quotient obtained by dividing the sputtering pressure by the sputtering voltage. . Although the simplest atomic absorption monitor is used here, it is also possible to use atomic absorption monitors having various configurations for higher accuracy. Further, as the vacuum gauge, one attached inside the vacuum container is used here, but a monitor device capable of locally measuring the degree of vacuum in the vicinity of the film forming region may be used.

In this embodiment, the use as an in-process monitor has been described. However, if the monitor value is larger than the specified value set in advance using the monitor result, the power supply for the film-forming power supply is turned on. When the monitor value is smaller than the specified value, the film forming power supply is equipped with a feedback means that can increase the power input to the film forming power supply. May be managed.

(Second Embodiment) Next, a second embodiment of the present invention will be described. FIG. 2 shows the outline of the configuration in the case where the in-process film formation monitoring apparatus according to the second embodiment of the present invention is applied to a vacuum apparatus.

In FIG. 2, the exploration light beam 14 emitted from the light source 1 containing the characteristic wavelength of the gas existing in the vacuum device is introduced into the film forming region of the vacuum container, and after passing through the inside region of the vacuum device, the outside of the vacuum container again. It is configured by an optical measurement system 19 and a data processing system 20 which are installed at a position where they can be detected.

The operation of the in-process film formation monitoring apparatus constructed as above will be described. First, the exploration light beam 14 emitted from the light source 1 is modulated and introduced into the vacuum container, and after passing through the vacuum container, the optical wavelength measuring system 19 determines the characteristic wavelength light intensity of the gas present in the vacuum device of the exploration light beam 14. In the vacuum device at the time when the inside of the vacuum container was in a high vacuum state, the light component generated in the vacuum container was removed based on the modulation applied to the search light beam 14 emitted from the light source 1 by the phase detection method. Based on the characteristic wavelength light intensity of the gas present in, the ratio of the light intensity at each time when the gas is present in the vacuum device is taken, and the absorbance is obtained by taking the logarithm of this, based on the calibration curve It is possible to know the partial pressure of the gas present in the vacuum device.

As described above, according to this embodiment, the light intensities of the gas molecules or atoms of the gas at the time of sputtering, etc. before being incident into a film forming atmosphere in which only characteristic wavelengths are separated and after passing through the film forming atmosphere are obtained. And the ratio of the light intensities are logarithmic, and the partial pressure of the gas in the vacuum device can be detected by this logarithmic value.

In the present embodiment, the type of gas existing in the vacuum apparatus is described, but in the case of a plurality of gases, the same detection may be performed for each characteristic wavelength. Although the light source and light detection system are outside the vacuum container, if the gas is present in the atmosphere to the extent that it interferes with detection, put the optical system in vacuum or use a different gas. Alternatively, the method of purging may be adopted. Further, an optical fiber and a bundle, a vacuum jig, or the like may be used so that the distance that light having a characteristic wavelength passes through the gas is adjusted to an optimum distance depending on the pressure of the gas. Further, although the method in which the light emission in the vacuum container is taken into consideration is adopted here, if there is no light emission in the vacuum container, the phase detection may not be performed.

(Embodiment 3) Next, a third embodiment of the present invention will be described. FIG. 3 shows the outline of the configuration when the in-process film thickness monitoring device according to the third embodiment of the present invention is applied to a magnetron sputtering device.

In FIG. 3, the light source luminous flux 9 emitted from the light source 1 which emits light including the characteristic wavelength light of the film-forming particles is modulated and introduced as an exploration light beam 14 into the film-forming particle flying area, and the film-forming particle flying area is obtained. Optical measurement system 19 for detecting the characteristic wavelength light component of the film-forming particles having the intensity of the exploration light beam 14 after passing
And a data processing system 20.

The operation of the in-process film thickness control device configured as described above will be described. First, by using the exploration light intensity 23 obtained by the optical measurement system 19 and the modulation signal applied to the light source light, the component in which the light source light is detected by the phase detector 11 and the component generated in the film forming region are respectively detected. .

Regarding the light source component, the absorbance is derived by taking the ratio with the signal before the start of film formation, and taking the logarithm thereof to determine the density or number of particles in the ground state among the flying particles. It is possible to obtain the density of the particles in the excited state or the number of the particles in the components generated in the film forming region. As a result, the information in the film formation area during sputtering can be obtained accurately,
Higher accuracy of film formation rate monitoring can be realized.

As described above, according to the present embodiment, the intensity component of the optical signal of the characteristic wavelength of the flying particles emitted from the light source in the film formation monitor to which the atomic absorption method is applied and absorbed in the particle flying region, and the sputtering. The number of excited ground particles and the number of ground particles that are flying are measured based on the measured values of the intensity components of each wavelength including light of the characteristic wavelength of the flying particles generated in the particle flight region. By deriving the number of particles and the plasma parameters of the sputtering gas, it is possible to detect the physical quantity in the film forming atmosphere, the number of flying particles in each of the ground state and excited state, the film forming rate, and the film thickness with high accuracy. it can.

In the present embodiment, the method of simply distinguishing the light from the light source and the light emission in the film-forming region is adopted, but a device for improving the accuracy other than this may also be carried out.
Further, although only the wavelength component generated in the film forming region is detected, other wavelengths may be detected and the spectroscopic analysis may be performed.

[0032]

As described above, in the present invention, by accurately monitoring the sputtering gas pressure and the sputtering voltage in the vacuum container, the atomic absorption film formation monitor is corrected by detecting the velocity component of the scattered particles, It is possible to promote the improvement of productivity by realizing higher precision and performing the film thickness control which has been conventionally performed by the time control with high precision in the process.

Further, in addition to the use as an in-process film thickness monitor, a feedback means is provided which can change the input power of the film-forming power source and the like so as to keep the rate constant by using the monitor result. As a result, the film thickness control can be performed in-process with high precision only by the conventional time management, the productivity can be improved, and the industrial value is extremely high.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram in the case where an in-process film thickness control device according to a first embodiment of the present invention is applied to a magnetron sputtering device.

FIG. 2 is a schematic configuration diagram of a vacuum container according to a second embodiment of the present invention.

FIG. 3 is a schematic configuration diagram when the in-process film thickness control device according to the third embodiment of the present invention is applied to a magnetron sputtering device.

FIG. 4 is a schematic configuration diagram when a conventional film formation rate control device is applied to a vapor deposition device.

FIG. 5 is a diagram showing the relationship between film formation rate and absorbance when a conventional film formation rate control device is applied to a vapor deposition device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 light source 3 photodetector 4 evaporation source 6 vacuum chamber 9 light flux 10 power source for light source 11 phase detector 12 film thickness monitoring device 13 particle scattering region 14 exploration light flux 19 optical measurement system 20 data processing system 22 reference output 23 exploration output 24 calculation Device 51 Vacuum gauge 52 Voltage measuring device

Claims (10)

[Claims] 1. A sputtering film forming apparatus for scattering particles, a film forming monitor applying an atomic absorption method, and a vacuum gauge capable of measuring the sputtering gas pressure in a film forming atmosphere and outputting the measured sputtering gas pressure. And a voltage measuring device capable of measuring a voltage applied to a sputtering target, and an arithmetic means capable of normalizing a film formation monitor value by a quotient obtained by dividing the sputtering gas pressure by a voltage applied to the sputtering or a function thereof, the standard An in-process film formation monitoring device, which detects a film formation rate of particles scattered in the film formation device based on the value. 2. A sputtering film-forming apparatus for scattering particles, a film-forming monitor applying an atomic absorption method, a vacuum gauge capable of measuring a sputtering gas pressure in a film-forming atmosphere and outputting the same, and a sputtering target. Equipped with a voltage measuring device capable of measuring the applied voltage, the quotient obtained by dividing the sputtering gas pressure at each time by the sputtering voltage, the film-forming monitor value the quotient obtained by dividing the sputtering gas pressure at each time by the sputtering voltage or the A monitoring method characterized by normalizing with a function, and multiplying this by a constant determined for each apparatus, to detect the rate at which a film is scattered by particles scattered in the film forming apparatus based on the standard value. 3. A vacuum apparatus, wherein a light beam emitted from a light source containing at least one characteristic wavelength of one or more gas molecules or atoms present in a particle flight region can pass through the vacuum region. The optical system and the characteristic wavelength of the molecules or atoms of the gas after passing through the particle flight region are separated, and only the intensity component of the light is separated, and the same wavelength of the noise light generated inside the flight particle region or outside A light intensity measurement system capable of separating and measuring the light intensity component of, and each light intensity before entering the film forming atmosphere in which only the characteristic wavelength of the molecule or atom of the sputtering gas is separated and after passing through the film forming atmosphere And a logarithm of the ratio of the light intensities, and the gas monitor and the gas partial pressure in the vacuum device are detected by the logarithmic value. Location. 4. A vacuum apparatus, wherein a light beam emitted from a light source containing at least one characteristic wavelength of one or more gas molecules or atoms present in a particle flight region can pass through the vacuum region. The optical system and the characteristic wavelength of the molecules or atoms of the gas after passing through the particle flight region are separated, and only the intensity component of the light is separated, and the same wavelength of the noise light generated inside the flight particle region or outside A light intensity measurement system capable of separating and measuring the light intensity component of is set, before entering the film forming atmosphere in which only the characteristic wavelength of the molecule or atom of the sputtering gas is separated and after passing through the film forming atmosphere. A method for monitoring, wherein a ratio of light intensities and a logarithm of the ratio of light intensities are taken, and the gas pressure and gas partial pressure in the vacuum device are detected by the logarithmic value. 5. A vacuum device having a structure for actively changing the distance that a light beam emitted from a light source passes through a vacuum region by using an optical fiber or a bundle or by the shape of a port for introducing a light source light into a vacuum. The vacuum monitor device according to claim 3, further comprising: 6. In a vacuum device, an optical fiber or a bundle is used, or the distance that a light beam emitted from a light source passes through a vacuum region is actively changed depending on the shape of a port for introducing a light source light into a vacuum. The monitoring method according to claim 4, wherein 7. An in-process film formation monitoring apparatus, wherein in a sputtering film formation apparatus for scattering particles, the sputtering gas pressure according to claim 1 is measured using the vacuum monitoring apparatus according to claim 3 or 5. 8. A sputtering film forming apparatus for scattering particles, wherein the sputtering gas pressure according to claim 2 is measured by the monitoring method according to claim 4 or 6. 9. A sputtering film forming apparatus that scatters particles, and a film forming monitor to which an atomic absorption method is applied, and light having a characteristic wavelength of flying particles emitted from a light source in the film forming monitor and absorbed in a particle flying region. The strength component of the signal,
An optical measurement system that can measure separately each intensity component for each wavelength including light of the characteristic wavelength of the flying particles generated in the flying region of the sputtered particles, and the ground state of the flying state based on these measured values Equipped with an arithmetic means that can derive the number of particles, the number of particles in the excited state, and the plasma parameter of the sputtering gas, the physical quantity in the film forming atmosphere, the number of flying particles in each of the ground state and excited state, the film forming rate, and the film forming thickness. An in-process film formation monitoring device characterized by detecting. 10. In a sputtering film forming apparatus for scattering particles, an intensity component of an optical signal of a characteristic wavelength of flying particles emitted from a light source in a film forming monitor to which an atomic absorption method is applied and absorbed in a particle flying region, Sputtering particles Measured separately for each intensity component of each wavelength including light of the characteristic wavelength of flying particles generated in the flight region, and based on these measured values, the number of ground-state particles flying and the excitation The number of particles in the state and the plasma parameters of the sputtering gas are derived, and the physical quantity in the film forming atmosphere and
A monitoring method characterized by detecting the number of flying particles in each of the ground state and the excited state, and a film forming rate and a film forming thickness.