JP4530776B2 - Multilayer film forming sputtering apparatus and film thickness control method thereof - Google Patents

Description

  The present invention relates to an optical multilayer film forming apparatus using a sputtering method, and more particularly to a method for simultaneously forming both surfaces and controlling a film thickness.

  For the production of optical multilayer films such as various filters and antireflection films, vacuum deposition is the mainstream, but in order to increase the packing density of the film, improvements such as ion assist are being implemented. Compared with the conventional vacuum deposition method, there are problems such as throughput, installation area, substrate temperature, running cost, equipment cost, etc., but these problems are being solved little by little due to recent advances in sputtering technology.

  The greatest advantage of the sputtering technique is the high reproducibility due to the stable generation of plasma. For this reason, film thickness reproducibility of several percent is obtained by controlling the discharge time without particularly installing a film thickness monitor. More specifically, the number of atoms sputtered by the incidence of one ion (sputtering yields) varies depending on the ion energy, the material of the target, and the angle of incidence of the ions on the target surface, but the actual sputter deposition Then, the sputtering yield is generally determined by determining the degree of vacuum during sputtering, the output of the sputtering power source, and the target. Therefore, the deposition rate by sputtering is extremely stable compared to vacuum deposition, and the deposited film thickness is controlled by time management without using a crystal film thickness meter or optical film thickness meter. Is common.

As an example of realizing the sputtering method, a carousel type (drum type) sputtering apparatus capable of mounting a large amount of substrates as shown in FIG. 9 has been proposed (for example, Patent Documents 1 and 2). In FIG. 9, while rotating a circular or polyhedral drum 25 to which a substrate is attached, a sputtering gas 19 and a reaction gas 20 are simultaneously introduced to alternately discharge the metal target material 8 and another metal target material 9. The method of forming a multilayer dielectric thin film by reactive sputtering has been taken. The film thickness distribution in the vertical direction of the rotary drum 25 can be adjusted by the film thickness correction plate 18.
Japanese Patent Publication No. 8-19518 Japanese Patent No. 3064301

  However, in the carousel type sputtering apparatus, when the flat substrate is attached to the drum 25, the space in the drum 25 is not used, so this portion becomes useless space and increases the installation area of the equipment. When the carousel type is a load lock type or in-line type, the installation area is further increased.

  In terms of film thickness distribution, the longitudinal direction of the drum 25 can be made uniform by geometric adjustment of the film thickness correction plate 18, but the elongated target erosion part is used as the evaporation source in the rotation direction of the drum 25. Since the film is formed on the rotating substrate, the uniformity is limited.

  Further, as a general problem of the sputtering apparatus, the film forming speed is reduced even when the film is formed under the same sputtering conditions as the target is eroded. That is, the target surface is eroded with the elapse of the sputtering time, the distance between the target and the substrate is increased, the deposited film thickness per unit time is gradually reduced, and as a result, the desired characteristics cannot be obtained. There's a problem. In the case of a single target material, it is also possible to control by fitting to a monotonously decreasing function by, for example, performing main film formation after obtaining data on the deposited film thickness with respect to the sputtering time after preliminary film formation. However, in the case of a multilayer structure, the degree of erosion of the target surface varies between the initial layer and the final layer, and as a result, the deposited film thickness per unit time differs between the initial layer and the final layer, making it difficult to control the film thickness with high precision. It becomes. That is, it is difficult to obtain reproducibility of about 1% in the case of forming a multilayer film over several hours.

  In the case of forming a dielectric thin film, a charge-up phenomenon occurs in the vicinity of the cathode and anode electrodes such as an earth shield, and often causes abnormal film discharge and problems of film thickness reproducibility and film quality degradation.

  From the viewpoint of film quality, film formation by sputtering generally has a higher film packing density due to higher particle energy during deposition than vacuum evaporation. However, since the internal stress of the film also increases at the same time, warping often occurs on a thin glass substrate having a thickness of 1.5 mm or less.

  Furthermore, the film thickness adjustment in the vertical direction of the substrate is performed by the film thickness correction plate 18, but when fine adjustment of the film thickness distribution is performed, it is necessary to open the vacuum chamber to atmospheric pressure and take out the correction plate 18 for adjustment. After the correction plate 18 is attached, there is a problem that time loss is caused by discharging only the target not intended for film formation on the substrate to reduce the emission gas in order to make the vacuum state in the vacuum chamber constant. there were.

  The first aspect of the present invention is a sputtering chamber comprising a vacuum chamber, a moving member that holds and moves the substrate in the sputtering chamber, and a plurality of plasmas for generating a plurality of target materials for forming an optical thin film on the substrate. Sputtering apparatus for forming an optical multilayer film having a sputter cathode consisting of a pair of each of the above, wherein each pair of sputter cathodes is disposed at a position facing each other across the movement path of the substrate, and the substrate is arranged for each pair of sputter cathodes The sputtering apparatus includes means for operating the moving member so as to pass through the vicinity a plurality of times. Further, the movement path of the substrate is a straight line, and the operating means is configured to reciprocate the moving member.

  According to a second aspect of the present invention, there is provided a sputtering chamber comprising a vacuum chamber, a moving member that holds and moves the substrate in the sputtering chamber, and a plasma of a target material made of a semi-metal or a metal to form a dielectric on the substrate. The sputtering apparatus includes a sputtering cathode that generates plasma, and includes a plasma monitoring unit that monitors a plasma state and a control unit that performs sputtering control based on an output of the plasma monitoring unit.

  According to a third aspect of the present invention, there is provided a sputtering chamber comprising a vacuum chamber, a moving member that holds and moves the substrate in the sputtering chamber, and a plasma of a target material made of a semimetal or a metal to form a dielectric on the substrate. A sputtering apparatus having a sputtering cathode for generating a substrate, wherein a substrate monitoring means for monitoring the substrate and a control means for performing sputtering control based on the output of the substrate monitoring means are provided, and the substrate is not opposed to the target material by the moving member It is a sputtering apparatus that moves to a predetermined measurement position and performs monitoring by the substrate monitoring means at the measurement position.

  According to a fourth aspect of the present invention, there is provided a sputtering chamber comprising a vacuum chamber, a moving member that holds and moves the substrate in the sputtering chamber, and a plasma of a target material made of a semi-metal or a metal to form a dielectric on the substrate. A sputtering apparatus having a sputtering cathode for generating a substrate, a substrate monitoring means for monitoring the substrate, a deposition rate of a film thickness formed on the substrate is calculated from an output of the substrate monitoring means, and the calculated deposition rate and a predetermined The sputtering apparatus is provided with a control unit that compares the theoretical values with each other to calculate the erosion amount of the target material and performs sputtering control based on the calculated erosion amount.

In the second to fourth aspects, the sputtering control includes control of the moving speed or moving direction of the moving member, or control of electric power applied to the sputtering cathode. Furthermore, an indicator for notifying the necessity of maintenance is provided to the control means, and the sputter control includes a control of the operation / non-operation of the indicator.
The plasma monitoring means is composed of a plasma sensor and an optical monitor that spectrally measures the output of the plasma sensor, and the optical monitor is composed of a multi-wavelength optical film thickness meter. on the other hand,
The substrate monitor means comprises a substrate sensor and an optical monitor that spectroscopically measures the output of the substrate sensor, and the optical monitor comprises a multi-wavelength optical film thickness meter.

Here, at least one pair of sputter cathodes for generating plasma from a plurality of target materials, and at least one pair of plasma sensors are provided, and the movement path of the substrate is configured to be a straight line. Each pair of sensors for use is arranged opposite to and parallel to the substrate across the movement path of the substrate, and an optical film is formed on both surfaces of the substrate. In addition, the apparatus includes a plurality of sputtering cathodes for generating plasma from a plurality of target materials for forming an optical multilayer film formation on the substrate, and at least one or more plasma sensors, so that the movement path of the substrate is linear. In addition, at least some of the plurality of sputter cathodes are arranged in parallel with the substrate along the movement path of the substrate, and each plasma sensor is arranged approximately in the middle of the adjacent sputter cathodes.
Further, in the adjacent set of sputter cathodes, when sputtering power is applied to one sputter cathode pair, the power applied to the other sputter cathode pair is reduced or cut off, and the other sputter cathode pair is connected. When power for sputtering is applied to the pair, the power applied to the pair of one sputtering cathode is reduced or cut off.

  According to a fifth aspect of the present invention, there is provided a sputtering chamber composed of a vacuum chamber, a moving member that holds and moves the substrate in the sputtering chamber, and a plasma of a target material composed of a semi-metal or a metal to form a dielectric on the substrate. Sputtering device equipped with a sputter cathode that generates heat, and is installed outside the sputtering chamber to adjust the film thickness distribution in the substrate and the preparation chamber for carrying the substrate into the sputtering chamber while maintaining the vacuum in the sputtering chamber A correction plate attached in front of the target material, and a correction plate attachment / detachment mechanism for operating the attachment / detachment of the correction plate from the outside of the sputtering chamber. The correction plate is carried together with the moving member, and the correction plate attachment / detachment mechanism is used. And a sputtering apparatus configured to be set at a predetermined position.

  According to a sixth aspect of the present invention, there is provided a sputtering chamber composed of a vacuum chamber, a moving member that holds and moves the substrate in the sputtering chamber, and a plasma of a target material composed of a semi-metal or a metal to form a dielectric on the substrate. A sputtering apparatus equipped with a sputtering cathode for generating a substrate is provided outside the sputtering chamber, and a charging chamber is provided for carrying the substrate into the sputtering chamber while maintaining a vacuum in the sputtering chamber. To the sputter chamber and recovery from the sputter chamber.

  Furthermore, in the second to fifth aspects, the target material is a material for forming at least an optical thin film. In the first to fifth aspects, the optical thin film is composed of an IR cut filter or an AR (antireflection) film.

  A sixth aspect of the present invention includes a sputtering chamber including a vacuum chamber, a moving member that holds and moves the substrate in the sputtering chamber, and a sputtering cathode including a plurality of pairs that generate plasma of a plurality of target materials. A method for forming an optical multilayer film in a sputtering apparatus, in which power is applied to a sputtering cathode to generate plasma of a target material, and the substrate is passed through a space sandwiched between each pair of sputtering cathodes to simultaneously perform sputtering on both surfaces of the substrate. This is an optical multilayer film forming method in which the operation of performing and passing is repeated a plurality of times. Here, as a result of the double-sided simultaneous sputtering, the internal stress of the film formed on both sides of the substrate was offset.

  The seventh aspect of the present invention is a sputtering chamber comprising a vacuum chamber, a moving member that holds and moves the substrate in the sputtering chamber, and generates a plasma of the target material to form a dielectric film on the substrate in the sputtering chamber. A sputtering method in a sputtering apparatus comprising a sputtering cathode to be plasma and a plasma monitoring means for monitoring a plasma state, the step of monitoring the plasma state using the plasma monitoring means, and the sputtering based on the output of the plasma monitoring means It is a sputtering method which consists of a step which performs control.

  The eighth aspect of the present invention is a sputtering chamber comprising a vacuum chamber, a moving member that holds and moves the substrate in the sputtering chamber, and generates plasma of the target material to form a dielectric film on the substrate in the sputtering chamber. A sputtering method in a sputtering apparatus comprising a sputtering cathode to be monitored and a substrate monitoring means for monitoring the substrate, wherein the step of moving the substrate to a predetermined measurement position not facing the target material by the moving member is deposited on the substrate by the substrate monitoring means. The sputtering method comprises the steps of measuring the spectral characteristics of the deposited film and performing the sputtering control based on the measured spectral characteristics.

  A ninth aspect of the present invention is a sputtering chamber comprising a vacuum chamber, a moving member that holds and moves the substrate in the sputtering chamber, and generates plasma of a target material to form a dielectric film on the substrate in the sputtering chamber. A sputtering method in a sputtering apparatus comprising a sputtering cathode to be provided and a substrate monitoring means for monitoring the substrate, the step of measuring the spectral characteristics of the film deposited on the substrate by the substrate monitoring means, the thickness of the film from the measured spectral characteristics Sputtering method comprising steps of calculating a deposition rate, calculating a erosion amount of the target material by comparing the calculated deposition rate with a predetermined theoretical value, and performing a sputtering control based on the calculated erosion amount It is.

  The present invention reduces the equipment area, improves film thickness control performance that could not be improved only by conventional time control, improves control accuracy by using an optical monitor, and cancels internal stress of thin film by simultaneous film formation on a glass substrate. In particular, in the field of optical thin film laminated parts production, such as the management of equipment maintenance cycles by monitoring abnormal discharge monitoring and the film thickness correction plate mechanism that can be replaced without breaking the vacuum in the sputtering chamber, the industrial value can be significantly improved. It's a big cry.

  In addition, by measuring the deposited film thickness after each layer is formed using the spectral characteristic measurement method, it is possible to correct the deposited film thickness per unit time associated with erosion of the target surface, resulting in extremely high-accuracy film thickness control. It has become possible.

  In order to remove the ineffective space of the carousel type sputtering apparatus, if the drum is developed on a flat surface and the length is adjusted to be a tray on which the substrate is mounted, the film forming type sputtering apparatus is obtained. At this time, in order to double the production amount, film formation on both sides of the tray may be performed by using a counter target as in the sputtering chamber (vacuum chamber) 1 shown in FIG. The length of the device is determined by the tray length and target size. The carousel type requires a large amount of board, but requires a larger installation area. On the other hand, in the passing film formation type, the installation area is reduced, but it seems that there are advantages and disadvantages that the amount of substrate mounting is reduced. However, if the target size is estimated to be the same size, for example, 5 inches wide and 40 inches long, the installation area is 9: 1 and the substrate mounting amount is 2: 1 (both are carousel type: double-sided film forming type). Therefore, it can be said that the double-sided passing method is advantageous in terms of the amount of board mounted relative to the installation area.

  In addition, there are the following advantages in simultaneous film formation on both sides. (1) Since both sides of the film are formed simultaneously, the film formed on both sides of the substrate can relieve the internal stress of the film compared to the film formed on only one side. (2) In simultaneous film formation on both sides, by setting different film formation parameters for each of the substrates, for example, an IR cut filter can be formed simultaneously on the surface of the substrate and an antireflection film can be formed on the back surface. (3) A mechanism that allows the substrate to be moved by the transfer tray (moving member) and the substrate formed by the substrate sensor 13 to be observed.

  When abnormal discharge due to charge-up or the like occurs, some abnormality occurs in the discharge state during sputtering, and can be detected by the sensor 14 for plasma measurement. In this case, for example, an abnormal discharge can be detected by observing a sudden change in the emission intensity of, for example, a wavelength of 425.9 nm in the emission spectrum of Ar (argon) plasma. Since the photometric wavelength range of the optical monitor is, for example, 380 nm to 1000 nm, there is no problem as a measurement region. The optical monitor can be observed by the sensor 13 at the substrate measurement position at the time of substrate measurement, but can be observed by the sensor 14 at the zone position where plasma light can be observed at the time of sputtering. The optical monitor 16 is of a multicolor type capable of observing a spectrum having a wavelength of 380 nm to 1000 nm.

  The film thickness correction plate 18 provided in front of the target erosion unit is intended to control the film thickness distribution of the film deposited on the substrate side by cutting a part of the sputtered particles flying from the target. Maintenance is required to remove the film deposited on the correction plate. Normally, maintenance of the correction plate 18 is performed in accordance with the replacement timing of the target. However, when controlling the film thickness distribution of about 1%, it is often necessary to perform maintenance frequently. In this case, when the work such as cleaning or replacement of the correction plate 18 is performed, the sputtering chamber is once opened to atmospheric pressure, but after maintenance, an empty discharge that is not intended for vacuum chamber baking or substrate film formation is performed. It is necessary to go and bring the vacuum device to a steady state. In the present invention, a method of replacing the correction plate 18 without opening the vacuum chamber to the atmosphere is presented.

Hereinafter, specific examples of the present invention will be shown based on examples.
(1) First Example The sputtering apparatus shown in FIG. 1 is a load-lock type sputtering apparatus including a preparation chamber (vacuum chamber) 2 for taking in and out a tray 5 and a sputtering chamber 1 for performing a sputtering film forming process. The tray 5 loaded with the substrate 7 is sent from the atmospheric pressure side through the gate valve 3 to the preparation chamber 2 through the gate valve 3 by the transfer mechanism 6, and the sputter chamber 1 is exhausted by a vacuum pump through the main valve 4 although not shown. In response to this, the substrate is heated by the heater 21 and then the tray 5 is sent to the sputter chamber 1 which has been evacuated through the gate valve 3, and a constant pressure is applied by the sputter gas 19 (Ar) and the reaction gas 20 (O ₂ ). Electric power is applied from the DC power source 11 to the sputtering cathode 81 that holds the target material 8 (for example, Si), and the tray 5 is transported at a constant speed by the transport mechanism 6 in the reactive sputtering state. Thus, SiO2 films are formed on both surfaces of the substrate 7 on the tray 5 by the reactive sputtering method using the target material 8 (silicon Si).

  Next, the tray 5 passes through the sputtering zone of the target material 8 and moves to the sputtering zone of the target material 9 (for example, niobium Nb) held by the sputtering cathode 91. When there are only two types of target materials, it is more efficient that the tray 5 is once pulled out of the zone of the target material 9 at a high speed and transported in the opposite direction to perform the sputter film formation with the target material 8. This is because the target material 8 and the target material 9 can be as close as possible to shorten the tray conveyance distance. In this way, the tray can reciprocate between the target material 8 and the target material 9 to stack a desired dielectric thin film. As for the laminated state, when the substrate 7 comes to the position of the sensor unit 13 of the optical monitor 16, the laminated state of the thin film can be known by light transmission or reflection. Since the photometric time is about 100 msec, it does not interfere with the substrate transport. When the intermediate film formation state is shifted from the expected value by this photometry, the film thickness is adjusted by determining with a personal computer or a sequencer and controlling the transport mechanism 6 or the DC power source 11 with the control device 17. be able to.

The substrate may be formed by sputtering on both sides, or two divided sheets may be formed side by side. In the latter case, the purpose is to double the production. As an example, Table 1 shows sputtering conditions when 20 layers of silicon oxide SiO ₂ film (refractive index 1.48) and niobium oxide Nb ₂ O ₅ film (refractive index 2.31) are alternately stacked on BK7 glass (refractive index 1.52). The obtained spectral transmittance is shown in FIG.

In this embodiment, the target size is 5 inches wide and 7 inches long, but if the size is extended in the vertical direction, it can be made as long as the apparatus size allows. Since it is possible to design the apparatus according to the size in the vertical direction according to the amount of the substrate mounted, the size of the apparatus main body does not depend on the amount of the substrate mounted in terms of installation area. However, since the target size increases when the substrate mounting amount is large, the DC power source 11 and the like increase.

In the embodiment, the target materials 8 and 9 are 5 inches wide and 7 inches long. The power input to the target shown in Table 1 is the power applied to one of the targets.
In the film configuration of Table 1, the symbol L means a film (low refractive index material) with the target 8, H means the target 9 (high refractive index material), and the optical film thickness at the wavelength λ = 600 nm is λ / 4. To do.

  FIG. 4 shows the spectral transmittance from a wavelength of 350 nm to 1000 nm when 20 layers are laminated on the substrate 7. The measurement was performed using a spectroscope after removing the substrate from the apparatus after film formation. In this case, since the substrate is divided and mounted on the tray, the film is formed on one side. Since the two divided substrates have the same film configuration and the obtained spectral transmittance is almost the same, FIG. 4 shows only one of them. When the substrate is divided into both sides, as shown in FIG. 3, by inserting a metal reflector 34 between the substrates, information on the spectral reflectance of only one substrate is obtained from the sensor 13 connected to the optical monitor 16. Can be confirmed. FIG. 5 shows the spectral reflectance of the optical monitor 16 corresponding to FIG. Since the spectral spectrum of the laminated film can be confirmed during the film formation, it is a feature of this apparatus that the film thickness can be adjusted by slightly changing the sputtering conditions until the final lamination.

  Next, a case where an optical multilayer film is formed by performing sputtering film formation on both surfaces of one substrate will be described. FIG. 2 shows a schematic diagram in which a low refractive index material 32 and a high refractive index material 33 are stacked on a substrate 31. FIG. 6 shows the spectral transmittance of the IR cut filter obtained by this method. The number of layers is 39 layers on one side × both sides, which is designed on a BK7 substrate with a center wavelength of 825 nm based on a refractive index of silicon oxide of 1.44 and a refractive index of niobium oxide of 2.23. The greatest advantage of this method is that a film having the same structure is laminated on both sides, so that the internal stress of a large film can be offset on each side.

  In addition, it has been described so far that two substrates with an optical multilayer film are manufactured simultaneously by mounting on a tray with both substrates or two substrates bonded together. It is another feature of the present invention that the multilayer film can be laminated. That is, an IR cut filter can be formed on one side and an antireflection film (AR film) can be formed on one side. For this purpose, a desired laminated film can be easily obtained by separately controlling the discharge power applied to the left and right target materials. When the number of stacked layers is smaller on the left and right, the smaller target applied power may be stopped there.

  Next, features related to device maintenance will be described. The optical monitor sensors 13 for measuring the laminated state of the substrates are paired. When the transmittance of the substrate 7 is measured, one is a projector and the other is a light receiver. In the case of measuring the reflectance of the substrate 7, both serve as light projection and light reception. The light projection is provided inside the optical monitor 16 with a light source lamp and can be guided to a measurement location using the optical fiber 15. In this case, the sensor 13 is used for a substrate, but by using the sensor 14 by switching the optical monitor 16 internally, the light emission state of plasma can be diagnosed by using only the light receiving unit. Although the sensors 14 are paired, they need only be positioned at an intermediate position between the target material 8 and the target material 9 and only need to be able to observe the plasma state in the vicinity of each target. The target material 8 and the target material 9 do not discharge at the same time, and during the film formation, the opposing discharge of the target material 8 or the target material 9 is divided by the tray 5, so discharge information from almost one target can be obtained. Obtainable.

  The discharge state of the plasma can be monitored by observing the emission spectrum of the sputtering gas 19 or the reaction gas 20. For example, the sputtering gas Ar has emission peaks at 425.9 nm, 750.4 nm, 763.5 nm, etc. Can be monitored. These wavelengths are within the measurement region 380 nm to 1000 nm of the optical monitor. When abnormal discharge occurs, the emission intensity fluctuates. Therefore, setting a reference value can be used as an index for apparatus maintenance. Abnormal discharge is likely to occur due to the charge-up phenomenon of electric charge due to the dielectric thin film deposited around the cathode such as the earth shield, and therefore, abnormal discharge is more likely to occur as the amount of deposition increases. In addition, since the sensors 13 and 14 are easily formed into a film, it is possible to keep the dirt for a period of time when the target material is replaced by attaching a cylindrical deposition preventive plate.

In addition, the target material is usually made with a thickness of about 6 mm to 8 mm, but the sputtering voltage decreases due to the consumption of the target material, that is, the progress of erosion. As for the relationship between the maximum erosion depth of the target material and the film formation rate, the film formation rate is reduced by about 5% with erosion of about 5 mm under the same sputtering conditions. When a film thickness control of about 1% is required, it is necessary to control the film formation speed by erosion. When the same target material is exchanged and used, the relationship between the erosion depth and the film formation rate may be controlled in accordance with a second-order regression equation for the target usage time once obtained. As another method, there is a method utilizing the fact that the emission spectrum intensity at the time of sputtering changes due to a change in plasma impedance due to a decrease in discharge voltage. Also in this case, since a correlation with the maximum erosion depth is obtained by a change in the specific emission spectrum intensity corresponding to the usage time of the target material, it is possible to predict and control the decrease in the target life and the film formation rate.
Further, for example, an indicator that informs the control device 17 of whether maintenance is necessary may be provided, and in the case of the target life, the indicator may be operated to prompt the user to perform maintenance. The indicator here includes one that emits light or sound, or one that displays that fact on a screen provided on an operation panel or a personal computer.

  As the number of trays formed in the multilayer film formation increases, the film thickness of the deposited film increases around the cathode, and it is often necessary to replace or adjust the film thickness correction plate 18 before replacing the target material. In this case, in the load lock type apparatus, the sputtering chamber 1 is opened to the atmospheric pressure, but a loss time occurs due to adjustment of the released gas until the film can be formed. In order to improve this, the present invention shows a method of replacing the film thickness correction plate without breaking the vacuum in the sputtering chamber.

As shown in FIG. 7, the substrate 7 is mounted on the tray 5 in pairs for each type of target material for replacement or adjustment, and the substrate 7 is transported from the preparation chamber 2 to the sputtering chamber 1. The tray is stopped at the previous stop position, and the correction plate attaching / detaching mechanism 22 capable of rotating and extending is inserted and rotated into the hook hole 40, and the correction plate mounted on the tray is simultaneously pulled to the left and right to the position shown in FIG. Wear a correction plate. When removing the correction plate, the reverse operation may be performed without mounting the correction plate on the tray.
In this embodiment, since the tray 5 is moved in both directions and the single loading chamber 2 is used to carry in / out the substrate, the entire apparatus is small.

(2) Second Example This example uses a spectral characteristic measuring device to measure the film thickness of the substrate on the tray after the film formation of each layer, instead of the film thickness control method conventionally performed only by time management. In the case where there is a deviation from the target value, the objective is to perform film thickness control with high accuracy by correcting the film thickness in subsequent layers.

で表される。Ｎは複素屈折率、ｄは薄膜の厚さ、θは薄膜への光の入射角を表す。また、多層膜は各層に対する四端子行列の積として表されるから、

となり、多層膜の振幅透過率：τ及びエネルギー透過率：Ｔは四端子行列の要素と媒
質の屈折率：Ｎ_０及び基板の屈折率Ｎ_Ｓから、

と表され、波長に対する透過率をプロットすると分光特性が得られる。 The theoretical value of the spectral characteristic of the optical thin film by the dielectric multilayer film can be obtained from the product of the four-terminal matrix.

It is represented by N represents the complex refractive index, d represents the thickness of the thin film, and θ represents the incident angle of light on the thin film. In addition, since the multilayer film is represented as a product of four-terminal matrices for each layer,

Next, the amplitude transmittance of the multilayer film: tau and energy transmission: T is the refractive index of the element and the medium of four-terminal matrix: N ₀ and the refractive index N _S of the substrate,

When the transmittance with respect to wavelength is plotted, spectral characteristics are obtained.

  In the present invention, when the spectral characteristic measuring apparatus is mounted on a continuous sputtering apparatus, the spectral characteristic is measured after film formation of each layer, the obtained measurement data is compared with the simulation result, and the film thickness is shifted. The correction is performed on and after the next layer.

  FIG. 8 shows a main part of a continuous sputtering apparatus equipped with a spectral characteristic measuring apparatus. FIG. 8 shows details of the sensor 13, the optical fiber 15 and the optical monitor 16 of FIG. Light emitted from the light source 161 for spectroscopic measurement enters the sputtering chamber 1 through the optical fiber 15 and the focus lens 131. The light transmitted through the sputter chamber 1 enters the spectroscope 162 for spectroscopic measurement via the condenser lens 132 and the optical fiber 15. After each layer is formed, when the substrate 7 mounted on the moving tray 5 passes on the optical axis composed of the focus lens 131 and the condenser lens 132, the conveyance of the tray 5 is temporarily stopped and the spectral characteristic device To measure the spectral characteristics of the substrate 7.

Next, the operation will be described.
The tray 5 on which the substrate 7 is mounted is transferred from the preparation chamber 2 to the sputtering chamber 1, and sputtering film formation on the target 9 is started. When the tray 5 finishes passing through the front surface of the target 9, the tray 5 stops once when the substrate 7 moves on the optical axis constituted by the focus lens 131 and the condenser lens 132. The optical monitor 16 includes a spectral characteristic measuring device including a light source 161 and a spectroscope 162. The spectroscope 162 measures the spectral characteristics of the substrate 7, and the control device 17 calculates the deposited film thickness or deposition rate based on the measurement result. Then, the data calculated by the control device 17 is compared with the data simulated in advance. If the deposited film thickness or deposition speed is different from the simulation result from the comparison result, the tray transport mechanism 6 in FIG. To adjust the deposited film thickness or deposition rate. In addition, the film design of the subsequent layers is also changed so that the spectral characteristics of the subsequent layers coincide with the simulation values. When there are a plurality of targets, film thickness measurement, deposition film thickness correction, and film design change can be similarly performed for film formation of other targets.

  By measuring the spectral characteristics of the substrate 7 after forming each layer as described above, it becomes possible to grasp the change in the deposited film thickness per unit time due to erosion of the target surface, and the film thickness correction in the subsequent layers can be performed. It becomes possible. Furthermore, since the substrate 7 can be moved by the tray 5 and the measurement position can be set to a desired position, it is possible to perform film thickness measurement with higher accuracy.

Although the most preferred example of the present invention has been described above, for example, the following modifications can be made without departing from the scope of the present invention.
(1) In Example 1, an example using two pairs of sputter cathodes was shown, but the number of pairs can be increased or decreased.
(2) In the first embodiment, a plurality of sputter cathodes are paired, but it is also possible to arrange for a single-sided multilayer by arranging them in a single row in parallel with the movement path of the substrate 7.
(3) In the present embodiment, the tray 5 and the substrate 7 are moved only linearly. However, the film formation may be controlled by providing a structure that reverses the front and back.
(4) In the first embodiment, the switching device 12 is used to switch the application of electric power to each sputtering cathode, but each sputtering cathode may be individually controlled using a separate power source. In this embodiment, the power supply to the sputtering cathode of the target that is not subject to the plasma state monitoring is cut off, but the power supply may be reduced.
(5) In the present embodiment, the film forming control is performed by controlling the moving speed of the tray 5 or the voltage applied from the DC power source 11 to the sputtering cathode. However, the main valve 4, the sputtering gas 19, The reaction gas 20 or the heater 21 may be controlled.

Diagram of the load lock type sputtering apparatus of the present invention Diagram showing structure of double-sided optical laminated film The figure which shows the structure of the double-sided optical laminated film when the reflector is sandwiched Diagram showing spectral transmittance of 20-layer laminated film Diagram showing spectral reflectance of 20-layer laminated film Diagram showing spectral transmittance of IR cut filter by double-sided film formation Diagram showing automatic film thickness correction plate attachment / detachment mechanism The figure explaining the sputtering device of the present invention Diagram showing a conventional carousel type sputtering system

Explanation of symbols

1. Sputtering chamber (vacuum chamber)
2. Preparation chamber (vacuum tank)
3. 3. Gate valve Main valve 5. Tray 6. 6. Tray transport mechanism Substrate 8. Target material9. Target material 10. Magnet 11. DC power supply (including pulse part)
12 Switch 13. Sensor (for board)
14 Sensor (for plasma)
15. Optical fiber 16. Optical monitor 17. Control device 18. Film thickness correction plate 19. Sputter gas 20. Reaction gas 21. Heater 31. Glass substrate 32. Refractive index A film 33. Refractive index B film 34. Reflector 40. Hook hole 81. Sputter cathode 91. Sputter cathode 131. Focus lens 132. Condensing lens 161. Light source 162. Spectrometer

Claims (16)

A sputtering chamber comprising a vacuum chamber, a moving member that holds and moves the substrate in the sputtering chamber, and a sputtering cathode comprising a plurality of pairs that generate plasma of a plurality of target materials for forming an optical thin film on the substrate. A sputtering apparatus for forming an optical multilayer film comprising:
Each pair of the sputter cathodes is disposed at a position facing each other across the movement path of the substrate,
Substrate is viewed contains a means for operating the moving member so as to pass a plurality of times in the vicinity of each pair of the sputtering cathode,
The sputtering apparatus characterized in that a movement path of the substrate is a straight line, and the means for operating reciprocates the moving member .
The sputtering apparatus according to claim 1 , further comprising:
A sputtering apparatus comprising plasma monitoring means for monitoring the state of the plasma, and control means for performing sputtering control based on the output of the plasma monitoring means.
The sputtering apparatus according to claim 1 , further comprising:
Substrate monitoring means for monitoring the substrate, and control means for performing sputtering controlled based on an output of the substrate monitoring means comprises,
A sputtering apparatus, wherein the moving member moves the substrate to a predetermined measurement position that does not face the target material, and monitoring is performed by the substrate monitoring means at the measurement position.
The sputtering apparatus according to claim 1 , further comprising:
Substrate monitoring means for monitoring the substrate;
The deposition rate of the film thickness formed on the substrate is calculated from the output of the substrate monitoring means, and the erosion amount of the target material is calculated by comparing the calculated deposition rate with a predetermined theoretical value. sputtering apparatus provided with a control means for sputtering control based on該浸diet amount.
A sputtering apparatus as claimed in any one the preceding claims 2, the sputtering apparatus wherein sputter control, characterized in that it comprises a control of the moving speed or moving direction of the moving member.
A sputtering apparatus as claimed in any one the preceding claims 2, wherein the sputter control sputtering apparatus which comprises a control of the power applied to the sputtering cathode.
The sputtering apparatus according to any one of claims 2 to 4 , further comprising:
Provided with an indicator that informs the control means whether maintenance is necessary,
The sputtering apparatus includes control of operation / non-operation of the indicator.
The sputtering apparatus according to claim 2 ,
The sputtering apparatus, wherein the plasma monitoring means comprises a plasma sensor and an optical monitor for spectroscopically measuring the output of the plasma sensor, and the optical monitor comprises a multi-wavelength optical film thickness meter.
The sputtering apparatus according to claim 3 or 4 , wherein
The sputtering apparatus, wherein the substrate monitor means comprises a substrate sensor and an optical monitor for spectroscopically measuring the output of the substrate sensor, and the optical monitor comprises a multi-wavelength optical film thickness meter.
The sputtering apparatus according to claim 8 , wherein
Comprising at least one pair of sputter cathodes for generating plasma from a plurality of the target materials, and at least one pair of sensors for the plasma;
The substrate movement path is configured to be a straight line, and each pair of the sputtering cathodes and each pair of the plasma sensors are arranged in parallel and opposite to the substrate across the substrate movement path. An optical film is formed on the sputtering apparatus.
The sputtering apparatus according to claim 8 , wherein
A plurality of sputter cathodes for generating plasma from the plurality of target materials for forming an optical multilayer film formation on the substrate, and at least one plasma sensor;
The movement path of the substrate is configured to be a straight line, and at least a part of the plurality of sputter cathodes are arranged in parallel to the substrate along the movement path of the substrate, and the plasma sensors are adjacent to each other. A sputtering apparatus, which is disposed substantially in the middle of the sputtering cathode.
The sputtering apparatus according to claim 9 , wherein
When a sputtering power is applied to one of the sputter cathode pairs in an adjacent set of the sputter cathodes, the power applied to the other sputter cathode pair is reduced or cut off, and the other sputter cathode pair is applied. When sputtering power is applied to a cathode pair, the sputtering apparatus is characterized in that the power applied to one of the sputtering cathode pairs is reduced or cut off.
The sputtering apparatus according to claim 1 , further comprising:
A charging chamber that is attached to the outside of the sputtering chamber and carries the substrate into the sputtering chamber while maintaining a vacuum in the sputtering chamber;
A detachable correction plate attached to the front of the target material for adjusting the film thickness distribution in the substrate, and a correction plate attachment / detachment mechanism for operating the attachment / detachment of the correction plate from the outside of the sputtering chamber;
A sputtering apparatus, wherein the correction plate is carried in together with the moving member and set at a predetermined position using the correction plate attaching / detaching mechanism.
The sputtering apparatus according to claim 1 , further comprising:
Attached to said sputtering chamber outside the substrate while maintaining the vacuum of the sputtering chamber provided with a load chamber for loading inside the sputtering chamber,
The sputtering apparatus, wherein the substrate is carried out to the sputtering chamber and recovered from the sputtering chamber in the same preparation chamber.
2. The sputtering apparatus according to claim 1, wherein the optical thin film comprises an IR cut filter or an AR (antireflection) film.
Optical multilayer in a sputtering apparatus comprising a sputtering chamber comprising a vacuum chamber, a moving member that moves in a straight line while holding the substrate in the sputtering chamber, and a plurality of pairs of sputtering cathodes that generate plasma of a plurality of target materials A film forming method comprising:
Applying power to the sputter cathode to generate plasma of the target material;
Sputtering is performed simultaneously on both sides of the substrate by passing the substrate through a space sandwiched between each pair of the sputtering cathodes,
The method of forming an optical multilayer film, wherein the passing operation is repeated a plurality of times by reciprocating the moving member .

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