JP2020196907A - Sputtering device and sputtering film deposition method - Google Patents

Abstract

To provide a film deposition apparatus capable of controlling a film thickness highly accurately by correcting film pressure change caused by relative position change between a target and a substrate.SOLUTION: A sputtering film deposition apparatus includes a substrate holding part for holding a substrate inside a chamber, a target arranged inside the chamber, and measurement means for a position and inclination of the substrate. The sputtering film deposition apparatus further has a control part for estimating a film deposition rate based on the measured position and inclination of the substrate, and depositing a film up to a target film thickness based on the estimated film deposition rate.SELECTED DRAWING: Figure 5

Description

The present invention relates to a sputtering film forming apparatus and a sputtering film forming method that can be used for forming an optical thin film or the like provided on an optical lens.

Generally, an optical thin film formed on an optical component such as a lens is formed by a vacuum vapor deposition apparatus or a sputtering apparatus. The film thickness and film thickness distribution of the optical thin film play an important role in the optical characteristics of the lens.

In a sputtering apparatus, it is generally known that the film formation rate and the film thickness distribution change when the TS distance indicating the distance between the target and the substrate changes. It is also known that as the erosion of the target progresses, the TS distance and the release angle of the material change, and the film formation rate and the film thickness distribution change. Therefore, there is a demand for a sputtering apparatus capable of obtaining a desired film thickness and film thickness distribution by reflecting these changes.

Patent Document 1 discloses a sputtering device in which a substrate is mounted on an outer peripheral surface of a rotating drum and a film is formed on the substrate while rotating the drum, and a sputtering device capable of measuring the amount of eccentricity of the rotating drum is disclosed. The sputtering apparatus described in Patent Document 1 can suppress the influence of minute eccentricity of the rotary bearing on the variation in film thickness characteristics by modifying the target power based on the measured eccentricity amount.

Further, Patent Document 2 discloses a sputtering apparatus provided with a mechanism for measuring the shape of an erosion portion (erosion) of a target by sputtering. The sputtering apparatus described in Patent Document 2 can obtain a desired film thickness and a uniform film thickness distribution by setting the optimum distance between the substrate and the target according to the wear state of the target.

Japanese Unexamined Patent Publication No. 2009-228062 Japanese Unexamined Patent Publication No. 2000-64037

However, the optical thin film of a lens used for a camera, a video, or the like is required to have high film thickness accuracy, and the optical characteristics change due to a change in the relative position between the target and the substrate during film formation. In the sputtering apparatus described in Patent Document 1 and Patent Document 2, the film thickness cannot be controlled with high accuracy when the relative position between the target and the substrate other than the TS distance changes.

The sputter film forming apparatus of the present invention is a sputter film forming apparatus provided with a substrate holding portion for holding a substrate inside a chamber, a target arranged inside the chamber, and means for measuring the position and inclination of the substrate. It is characterized by having a control unit that estimates a film forming rate based on the measured position and inclination of the substrate and forms a film to a target film thickness based on the estimated film forming rate.

The sputter film forming method of the present invention comprises a substrate holding portion for holding a substrate inside a chamber, a target arranged inside the chamber, and a measuring means for measuring the position and inclination of the substrate. The film method is characterized in that a film forming rate is estimated based on the measured position and inclination of the substrate, and the film is formed to a target film thickness based on the estimated film forming rate.

According to the sputter film forming apparatus of the present invention, the film thickness can be controlled with high accuracy by correcting the film thickness change caused by the relative position between the target and the substrate.

It is a figure which shows the outline of the sputtering film formation apparatus of 1st Embodiment. It is a figure explaining the relationship between a substrate holding part and a rotating shaft. It is a figure explaining the position and direction of a substrate. It is the schematic which shows the release distribution of the film-forming material. It is a figure which shows the flow of the sputtering film formation method of 1st Embodiment. It is a figure explaining that the inclination of a substrate affects the film formation rate. It is a figure which shows the outline of the sputtering film formation apparatus of 2nd Embodiment.

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

(First Embodiment)
The sputtering film forming apparatus of the present embodiment is a magnetron sputtering film forming apparatus (hereinafter referred to as "sputter film forming apparatus") in which a permanent magnet is arranged on the back surface of the target to generate a magnetic field to improve the film forming speed. Can be used. FIG. 1 is a diagram showing an outline of the sputtering film forming apparatus of the first embodiment.

In FIG. 1, the sputtering film forming apparatus 100 includes a target 3 for discharging a film forming material, a substrate holding portion 13 for holding a substrate 12 such as a lens, and a camera 16 for photographing the substrate 12 inside the vacuum chamber 1. I have. A shutter 9 is provided between the target 3 and the substrate 12, and the substrate 12 can be covered during pre-sputtering.

The vacuum chamber 1 is provided with an exhaust device 22, and the inside of the vacuum chamber 1 can be evacuated to a vacuum. The vacuum chamber 1 can be supplied with the sputter gas (argon gas) compressed in the sputter gas cylinder 9 and the reactive gas (oxygen gas) compressed in the reactive gas cylinder 6. The flow rate of the sputter gas is adjusted by the sputter gas valve 10, and the sputter gas is supplied into the vacuum chamber 1 through the gas pipe 11. The reactive gas (oxygen gas) is supplied into the vacuum chamber 1 through the gas pipe 8 whose gas flow rate is controlled by the mass flow controller 7. When it is not necessary to supply the sputter gas (argon gas) and the reactive gas (oxygen gas), the gas supply can be cut off by an electromagnetic valve (not shown).

By exhausting the sputter gas and the reactive gas filled in the vacuum chamber 1 from the exhaust device 22 connected to the vacuum chamber 1, the inside of the vacuum chamber 1 can be adjusted to a predetermined pressure. Further, the pressure in the vacuum chamber 1 can be adjusted even when the sputtering gas and the reactive gas are being supplied.

A plasma power supply 21 is connected to the target 3, and plasma is generated by supplying a predetermined electric power in a vacuum state. Silicon, nickel, aluminum, or the like can be used for the target 3, and the target 3 can be automatically switched depending on the film type to be formed. The target 3 is held by the target holding unit 4, and the target holding unit 4 is connected to a cooler 5 for supplying cooling water. The cooler 5 cools the target 3 to prevent the target 3 and its surroundings from being deformed by the heat of the plasma. A permanent magnet 2 is provided on the back surface of the target 3, and a magnetic field is formed on the material emission surface. Further, a plasma emission monitor 5 is provided in the vicinity of the target 3 so that plasma emission can be monitored.

The substrate holding unit 13 that holds the substrate 12 can be rotated and the TS distance can be adjusted by the substrate driving unit 14. The substrate driving unit 14 rotates the substrate 12 held by the substrate holding unit 13 at a predetermined rotation speed so that a film can be formed at a predetermined TS distance. Further, the rotation speed and the TS distance can be arbitrarily adjusted even during the film formation. The rotation axis of the substrate holding portion 13 can be set at an arbitrary angle, and the film can be formed in a state where the rotation is stopped.

The shutter 9 is provided between the target 3 and the substrate 12, and can be penetrated and retracted between the target 3 and the substrate 12 by the shutter driving unit 15. The shutter 9 is retracted during film formation, and when a predetermined film thickness is reached, the shutter 9 is allowed to penetrate between the target 3 and the substrate 12, so that the film formation can be stopped. Further, the shutter driving unit 15 can control the shutter 9 to be intermediately stopped at an arbitrary position, and can also be used as a mask for controlling the film thickness distribution.

The camera 16 is arranged in the atmosphere chamber 17, and the substrate 12 can be imaged through the glass viewport 18. A flat plate illumination 19 is provided on the back side of the substrate 12 as viewed from the camera 16, and the position of the substrate 12 can be measured by imaging the substrate 12 and processing the captured image. Further, the camera 16 captures not only the substrate 12 but also the substrate holding portion 13, and the captured image is image-processed so that the relative positions of the target 3 and the substrate 12 can be obtained with high accuracy.

In the present embodiment, the image captured by the camera is image-processed to measure the position and direction of the substrate 12, but the substrate 12 is measured by using, for example, a laser displacement system or a contact-type displacement system other than the camera. The position of may be measured.

The control unit 23 estimates the film formation rate and controls the film formation rate based on the position information of the substrate 12 or the position information of the substrate 12 and the substrate holding unit 13.

Next, a method of estimating the film formation rate of the sputtering film deposition apparatus of the present embodiment will be described with reference to FIG. In order to control the film thickness with high accuracy, the film formation rate is estimated by the product of the release rate of the film-forming material discharged from the target 3 and the film-forming ratio at which the released film-forming material adheres to the substrate 12. To do. The value obtained by integrating the estimated film formation speed over time is used as the film thickness estimation value, and when a predetermined film thickness is reached, the shutter 9 is closed to stop the film formation.

First, the estimation of the release rate of the film-forming material will be described. The power applied to the target 3 and / or the gas flow rate of the reactive gas (oxygen gas) are controlled so that the spectral characteristics of the plasma emission acquired from the plasma emission monitor 5 are in a predetermined state. Then, based on (1) the spectral characteristics of the plasma emission during film formation, (2) the voltage applied to the target 3, and (3) the gas flow rate of the reactive gas (oxygen gas), the film formation emitted from the target 3 is performed. Estimate the release rate of the material. Simulation or advance of the relationship between (1) spectral characteristics of plasma emission, (2) voltage applied to target 3, (3) gas flow rate of reactive gas (oxygen gas), and (3) release rate of film-forming material. By registering the measurement results in the database, the release rate of the film-forming material can be estimated. As examples of this embodiment, (1) spectral characteristics of plasma emission, (2) voltage applied to the target 3, (3) gas flow rate of reactive gas (oxygen gas), and release of film-forming material. The results of measuring the speed relationship were tabulated and registered in a database (not shown) for use.

Next, the estimation of the film formation ratio at which the released film-forming material adheres to the substrate 12 will be described. The film formation ratio is estimated based on (5) the position and inclination of the substrate and (6) the release distribution of the film-forming material. (5) For the substrate position, the displacement amount of the substrate 12 and the displacement angle of the substrate 12 are used. Further, (5) the substrate position can be more accurately estimated by using the amount of rotation axis deviation of the substrate holding portion 13.

FIG. 2 describes the relationship between the substrate holding portion 13 and the rotating shaft. As shown in FIG. 2A, the substrate holding portion 13 usually rotates on the rotation axis _RH . In contrast, as shown in FIG. 2 (b), when the rotation axis of the substrate holder 13 is displaced obtains the rotation axis deviation amount [Delta] X _R. Further, as shown in FIG. 2C, when the angle of the rotation axis of the substrate holding portion 13 is deviated from the usual angle, the rotation axis deviation angle θ _H of the substrate holding portion 13 is obtained.

Next, the position and direction of the substrate 12 will be described with reference to FIG. As shown in FIG. 3A, the rotation axis _RH of the substrate holding portion 13 and the central axis _RS of the substrate 12 coincide with each other. In contrast, as shown in FIG. 3 (b), when the center axis R _S of the rotation axis R _H and the substrate 12 of the substrate holder 13 is displaced in obtaining the shift amount [Delta] X _S of the substrate 12. As shown in FIG. 3C, when the angles of the rotation axis _RH of the substrate holding portion 13 and the central axis _RS of the substrate are deviated, the deviation angle θ _S of the substrate 12 is obtained. By registering in the database the results of simulation or pre-measurement of the relationship between (5) the position and inclination of the substrate 12, (6) the release distribution of the film-forming material, and the film-forming ratio, the film-forming material can be obtained. The rate of film formation on the substrate 12 is estimated. Here, as shown in FIG. 4, the release distribution D of the film-forming material indicates the distribution of the amount of the film-forming material released from the target 3 toward the substrate in a unit time, and is the TS distance and the film-forming. When the material, the consumption state of the target, and the like change, the film thickness distribution formed on the substrate 12 also changes. In the embodiment of the present embodiment, the results of measuring the relationship between the position and inclination of the substrate, the release distribution of the film-forming material, and the film-forming ratio were tabulated in advance and registered in a database for use.

The emission distribution of the film-forming material stores the integrated value of the amount of power applied to the target 3 by the plasma power supply 21, and estimates the consumption state (position of the erosion track and the amount of consumption) of the target 3 based on the integrated power amount. be able to. The integrated value of the amount of electric power applied to the target 3 by the plasma power supply 21 is reset every time the target 3 is replaced with a new one. The emission distribution of the film-forming material emitted from the target 3 is estimated by registering the relationship between the emission distribution of the film-forming material and the integrated value of the applied power to the target 3 in the database as a result of simulation or measurement in advance. To do. In the embodiment of the present embodiment, the results of measuring the relationship between the emission distribution of the film-forming material and the integrated power applied to the target 3 in advance are tabulated and registered in a database (not shown) for use.

In the first embodiment, since the target 3 is sufficiently cooled, the relationship between the emission distribution of the film-forming material and the integrated power applied to the target 3 is reproducible. If reproducibility cannot be obtained, a mechanism for measuring the position of the target 3 and the shape of the eroded portion (erosion) of the target 3 by sputtering may be provided. At this time, the relationship between the shape measurement result of the target 3 and the release distribution of the film-forming material was tabulated and registered in the database for use.

Next, the estimation of the film thickness distribution will be described. The position and direction of the substrate 12 are obtained by image processing the image taken by the camera 16, and the film thickness distribution of the material formed on the substrate is estimated based on the emission distribution of the film-forming material. By registering the relationship between the position and direction of the substrate 12 and the release distribution of the film-forming material and the film thickness distribution in the database, the film-forming material is deposited on the substrate 12. Calculate the film thickness distribution. The control unit 23 commands the substrate drive unit 14 to adjust the TS distance so that the film thickness distribution estimated by calculation becomes uniform. In the examples of this embodiment, the results of measuring the relationship between the position and inclination of the substrate, the release distribution of the film-forming material, and the film thickness distribution were tabulated and registered in a database for use.

Imaging is performed a plurality of times while the substrate 12 makes one rotation in order to determine the position and direction of the substrate 12. In order to accurately determine the position and direction of the substrate 12, it is preferable to obtain the position and direction of the substrate 12 by imaging at least eight times during one rotation of the substrate 12. In the embodiment of the present embodiment, the film was formed at a rotation speed of the substrate 12 at 60 rpm, the camera 16 imaged at 60 fps, and 60 images were taken while the substrate 12 rotated once. The position and direction of the substrate 12 were obtained from the images of the 60 substrates 12. In order to accurately measure the position and direction of the substrate 12, images were continuously taken while the substrate 12 was rotated a plurality of times, and the position and direction of the substrate 12 were determined based on the image.

FIG. 5 shows a control flow of the sputtering film forming apparatus according to the embodiment of the present invention. Steps S101 to S109 show the preparatory flow until the start of film formation, steps S201 to S204 show the flow during film formation, and steps S301 to S302 show the post-treatment flow after film formation. Cooling water is always supplied from the cooler 5 to the target holding portion 4, so that the target 3 and its surroundings are not easily deformed by the heat of plasma.

In step S101 of FIG. 5, the substrate 12 is charged into the vacuum chamber 1 by a transfer robot device (not shown). The substrate 12 is held by the substrate holding portion 13, and the vacuum chamber 1 is evacuated by the exhaust device 22.

In step S102, the substrate holding unit 13 that holds the substrate 12 is driven by the substrate driving unit 14 so that the TS distance and the rotation speed are set in advance based on the film formation design conditions. In the embodiment of this embodiment, the film was formed at a rotation speed of the substrate 12 at 60 rpm.

In step S103, the camera 16 and the flat plate illumination 19 are controlled, and the positions and directions of the substrate 12 and / or the substrate holding portion 13 are detected from each of the images of the 60 substrates 12 continuously imaged at 60 fps. Position and direction of the substrate 12 calculates the shift amount [Delta] X _S of the substrate 12, the deviation angle theta _S of the substrate 12. For the position and direction of the substrate holding portion 13, the rotation axis deviation amount ΔX _R and the rotation axis deviation angle θ _H of the substrate holding portion 13 are calculated.

In step S104, the emission distribution is acquired from the database 23 based on the integrated power value applied from the plasma power source 21 to the target 3 until the previous film formation.

In step S105, the shift amount [Delta] X _S of the substrate 12 obtained in step S103, based on the emission distribution obtained in step S104, acquires the thickness distribution to be deposited on the substrate 12 from the database 24. The TS distance at which the film thickness distribution becomes uniform is obtained using the database 24, and the TS distance is corrected by the substrate driving unit 14.

In step S106, the film formation ratio is acquired from the database 22 based on the position of the substrate 12 obtained in step S103 and the release distribution of the film-forming material obtained in step S104.

In step S107, a sputter gas (argon gas) and a reactive gas (oxygen gas) are supplied to the vacuum chamber 1, and a preset power is supplied from the plasma power source 21 to the target 3 to discharge the gas.

In step S108, the gas flow rate of the reactive gas (oxygen gas) is feedback-controlled by the mass flow controller 7 so that the spectral characteristics of the plasma emission acquired from the plasma emission monitor 5 are in a predetermined state, until the film formation is completed. Continue control.

In step S201 of FIG. 5, the shutter driving unit 15 opens the shutter 9 and starts film formation.

In step S202, the spectral characteristics of the plasma emission acquired from the plasma emission monitor 5, the amount of power applied from the plasma power source 21 to the target 3, and the gas flow rate of the reactive gas (oxygen gas) controlled by the mass flow controller 7 are acquired. To do. Then, based on these values, the release rate of the film-forming material is acquired from the database 25.

In step S203, the film thickness is estimated by integrating the film formation rate, which is the product of the film formation ratio obtained in step S106 and the release rate obtained in step S202, over time.

In step S204, the film thickness estimated value obtained in step S203 is compared with the preset target film thickness value, and if the film thickness estimated value does not reach the target film thickness value, the process returns to step S202 to return the film. Repeat until the estimated thickness reaches the target film thickness value. In the embodiment of the present embodiment, high-precision film thickness reproducibility is realized by looping from step S202 to step S204 in a cycle of 50 msec.

In step S205, the shutter 9 is closed by the shutter driving unit 15, the film-forming material released from the target 3 is blocked from adhering to the substrate 12, and the power supplied from the plasma power source 21 to the target 3 is stopped.

In step S301 of FIG. 5, the solenoid valves of the sputter gas (argon gas) and the reactive gas (oxygen gas) supplied to the vacuum chamber 1 are closed to shut off the gas supply.

In step S205, the exhaust device 22 is stopped, the vacuum chamber 1 is released to the atmosphere, and the substrate 12 is discharged from the vacuum chamber 1 by a transfer robot device (not shown).

FIG. 6 shows the effect of the deviation angle θ _S of the substrate 12 of FIG. 3 on the film thickness accuracy. FIG. 6A shows a case where the substrate 12 has a desired position and inclination with respect to the target, and FIG. 6B shows a case where the substrate 12 is tilted with respect to the target at a deviation angle θ _S. .. The arrow indicates the film-forming material released from the target. As shown in FIG. 6, when the substrate 12 is tilted with respect to the target, the amount of the film-forming material reaching the substrate 12 is reduced, so that even if the rate at which the material is discharged from the target is constant, the substrate The rate of filming on the material is reduced. Therefore, when there is a relative position change between the target and the substrate 12 as well as the TS distance due to the heat of the plasma, the film thickness of the substrate 12 is actually thinner than the desired film thickness. In order to prevent such a change in the film formation ratio, it is necessary to control the deviation angle θ _S and the like. According to the first embodiment, the change in the film formation ratio can be estimated by measuring the change in the relative position and direction of the target and the substrate 12, and the film thickness is increased by correcting the film formation time. It can be controlled with precision.

Conventionally, when the sputtering film forming apparatus is continuously operated, the film thickness is deviated when the film is formed due to the deformation of the vacuum chamber due to the pressure difference between the vacuum and the atmosphere, the thermal deformation due to the plasma, the substrate holding position error, and the like. The relative position between the target and the substrate was about 0.8 mm in the TS distance, about 0.5 mm in the horizontal method, and about 0.5 degrees in the angle. Since the film thickness changes due to the change in the relative position between the target and the substrate, the film thickness had an error of 2.43% from the set value, but by using the film thickness estimation of the first embodiment, The film thickness error was improved to 1.17%.

(Second Embodiment)
The second embodiment is a suitable embodiment for using a substrate larger than the first embodiment. FIG. 7 shows a sputtering film forming apparatus according to the second embodiment.

The second embodiment is a film forming apparatus for a large glass substrate 112. The large glass substrate 112 is held by the substrate holding portion 113, and the large glass substrate 112 is scanned and formed into a film by the substrate conveying portion 114. A laser position measurement sensor 116 for measuring the shape from below the large glass substrate 112 is provided. Immediately before the scan film formation of the large glass substrate 112, the scan shape of the large glass substrate 112 is scanned and measured, and the relative position of the film-forming portion of the target 103 and the large glass substrate 112 is measured. When the size of the substrate is increased, the substrate is bent by its own weight, and the relative position of the film-forming portion of the target 103 and the large glass substrate 112 changes, so that the film-forming ratio may change. In the case of this embodiment, a desired film thickness distribution can be obtained by correcting the scanning speed of the large glass substrate 112 according to the change in the film formation ratio. Alternatively, the power supplied to the target 103 may be corrected according to the change in the film formation ratio.

Claims (8)

A board holding part that holds the board inside the chamber,
With the target placed inside the chamber,
In a sputtering film forming apparatus provided with means for measuring the position and inclination of the substrate,
A sputter film forming apparatus including a control unit that estimates a film forming rate based on the measured position and inclination of the substrate and forms a film to a target film thickness based on the estimated film forming rate. The measuring means measures the amount of displacement of the substrate with respect to the rotation axis of the substrate and the displacement angle of the substrate.
The sputter film forming apparatus according to claim 1, wherein the control unit estimates the film forming rate based on the measured position of the substrate and the displacement angle of the substrate. The measuring means measures the amount of displacement of the substrate with respect to the rotation axis of the substrate, the deviation angle of the substrate, and the amount of deviation of the rotation axis of the substrate holding portion.
The spatter film formation according to claim 1, wherein the control unit estimates the film formation rate based on the measured position of the substrate, the deviation angle of the substrate, and the amount of rotation axis deviation of the substrate holding unit. apparatus. The measuring means is a camera.
Any one of claims 1 to 3, wherein the control unit estimates the film formation rate based on the position and inclination of the substrate, and forms a film to the target film thickness based on the estimated film thickness. The sputter film forming apparatus according to the section. A sputter film formation method comprising a substrate holding portion for holding a substrate inside a chamber, a target arranged inside the chamber, and a measuring means for measuring the position and inclination of the substrate.
A sputtering film formation method characterized in that a film formation rate is estimated based on the measured position and inclination of the substrate, and a film is formed to a target film thickness based on the estimated film formation rate. The measuring means measures the amount of displacement of the substrate with respect to the rotation axis of the substrate and the displacement angle of the substrate.
The sputter film forming method according to claim 5, wherein the film forming rate is estimated based on the measured position of the substrate and the displacement angle of the substrate. The measuring means measures the amount of displacement of the substrate with respect to the rotation axis of the substrate, the deviation angle of the substrate, and the amount of deviation of the rotation axis of the substrate holding portion.
The spatter film forming method according to claim 5, wherein the film forming speed is estimated based on the measured position of the substrate, the displacement angle of the substrate, and the amount of rotation axis deviation of the substrate holding portion. The measuring means is a camera.
The measured position of the substrate and the deviation angle of the substrate are according to any one of claims 5 to 7, wherein the position and inclination of the substrate are calculated by image processing the image measured by the camera. The spatter film forming apparatus according to the above.

Images