JP2009228062A - Sputtering film deposition apparatus and sputtering film deposition method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the following problem in film deposition using a rotary drum such as a carrousel, that an extremely fine eccentricity between a rotary shaft of the carrousel and a bearing of an apparatus body exerts an influence on a variation in the characteristics of a product. <P>SOLUTION: In a carrousel type sputtering film deposition apparatus, a cylindrical or polygonal drum is rotatably provided inside a chamber 3 being a chamber, each substrate holder 9 for housing each substrate 10 is attached on the outer circumferential surface of the drum, and a film is deposited on each substrate 10 while rotating the drum around a vertical rotary shaft. The apparatus is provided with: targets 7, 8 provided on the inner wall of the chamber 3 being the chamber and depositing a film on each substrate 10; and an eccentricity measuring device 13 for measuring the eccentricity quantity of the rotary drum by measuring the distance between each target and each substrate 10 at the position at which each substrate holder 9 is confronted with the targets 7, 8 in front, and the apparatus corrects the target electric power according to each substrate target by the output from the eccentricity measuring device 13. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an optical multilayer film forming apparatus and a sputtering film forming method by a sputtering method when an optical multilayer film used for a liquid crystal projector or the like is formed by a sputtering method, and in particular, carousel type sputtering film forming. The present invention relates to improvement in the stability of optical characteristics of an optical multilayer film formed in a rotary sputter film forming apparatus such as an apparatus.

  The optical multilayer film is composed of an alternating laminated film of two kinds of films having a high refractive index and a low refractive index or a laminated film of three or more kinds of films on a substrate. The film thickness of each of these layers is the most important factor for determining the optical characteristics, and it is an important matter in the film forming apparatus to control the film thickness more accurately. At present, the optical multilayer film is required to have a thickness error of several percent or less to 1% or less for strict specifications. Therefore, if the stability of the film formation rate is not ensured, required optical characteristics such as transmittance and half-value wavelength of the transmission band cannot be obtained. Furthermore, in order to perform continuous film formation with a mass production machine, reproducibility between lots cannot be obtained unless the above-described stability is ensured.

Conventionally, it has been common to use a vacuum deposition method for forming an optical multilayer film. However, since the kinetic energy of attached particles is very low, in recent years it has a dense microstructure and no wavelength shift. In order to form a thin film, Passive that energizes attached particles by plasma assist of ions, such as substrate heating, ion-assisted vapor deposition, or ion plating.
An energy process, a sputtering method, and the like have been proposed. In addition, the film formation technique based on the sputtering method provides high reproducibility due to the generation of stable plasma. In particular, it is possible to form a predetermined film thickness according to a predetermined film formation rate without installing a film thickness monitor. By calculating and controlling the required time, the film thickness control accuracy of each layer during film formation is getting better and better. Therefore, the film formation rate in the sputtering method is extremely stable compared to the vacuum evaporation method, and the film thickness can be controlled without using a crystal film thickness meter or an optical film thickness meter. There is an advantage that it is possible.

In particular, a film forming technique and a film forming apparatus based on a carousel-type rotary sputtering method capable of forming a large area among sputtering methods have been proposed (for example, see Patent Documents 1 to 3). In a sputter deposition apparatus equipped with a rotating drum called a carousel, a metal target material and another metal target material are alternately discharged while rotating the carousel, and an optical multilayer is formed by a reactive sputtering or oxidation assist process. A method of forming a film has been taken.
Japanese Patent Laid-Open No. 8-176721 JP 2003-27226 A JP-A-62-284076

  The carousel-type rotary sputtering method can form a film on a large-area substrate or a large number of substrates, but it is very difficult to control the in-plane variation of the gold optical characteristics due to the variation of the film thickness distribution. There is a problem. Factors of the variation include substrate vertical direction, substrate horizontal direction, substrate holder-to-lot, and lot-to-lot variation.

When adjusting the film thickness in the vertical direction of the substrate, by providing a film thickness correction plate between the substrate and the target, it is possible to block some of the particles sputtered from the target and scattered in the substrate direction. By adjusting the thickness, it is possible to uniformly correct the film thickness distribution and to obtain a desired non-uniform film that changes the film thickness depending on the location. Also, the film thickness variation in the lateral direction of the substrate is caused by the difference in the probability of sputtered atom deposition due to the difference in plasma density around the center of the substrate and at both ends of the substrate. It is possible to make the adhesion probability uniform by adjusting the speed. Stabilization is achieved by adjusting the carousel between the substrate holders and by adjusting the film thickness between lots by feeding back the film formation results.
However, at present, the optical multilayer film requires increasingly strict optical specifications, and it is very difficult to realize the current in-plane variation characteristics only with the above-mentioned efforts, and in particular, the efforts between the substrate holders. There is a limit to the mechanical dimension adjustment. In fact, a problem has arisen that the extremely small eccentricity of the rotation axis of the carousel and the bearing of the apparatus main body affects the variation in optical characteristics. The present invention solves the above-described conventional problems, and an object of the present invention is to provide a sputter deposition apparatus and a sputter deposition method that can make the optical characteristics between the substrate holders uniform.

  In order to solve the above-mentioned conventional problems, a sputtering film forming apparatus of the present invention includes a cylindrical or polygonal drum in a chamber, a substrate holder in which a substrate is stored on the outer peripheral surface of the drum, A sputter sputtering apparatus having a target provided on an inner wall and forming a film on the substrate, wherein the substrate holder measures the distance between the target and the substrate at a position facing the target in front, and the rotating drum An eccentricity measuring device that measures the amount of eccentricity of the target, and corrects the target power for each substrate holder based on the amount of eccentricity.

  The sputter deposition apparatus of the present invention is characterized in that, in the eccentricity measuring apparatus, a distance between the target and each substrate is measured using a non-contact sensor.

  In the sputter deposition method of the present invention, a cylindrical or polygonal drum is rotatably provided in a chamber, a substrate holder for storing a substrate is attached on the outer peripheral surface of the drum, and the drum is vertical. In the sputtering film forming method for forming a film on the substrate while rotating around a rotation axis, a step of measuring an eccentric amount of the rotary drum by measuring a distance from a target to be formed on the substrate, and the eccentricity And a step of controlling the target power for each base holder based on the quantity.

  The sputter film forming method of the present invention also includes a step of measuring the eccentric amount of the rotating drum by measuring a distance from the target to be formed on the substrate, and the substrate holders based on the eccentric amount. The step of controlling the target power is performed during evacuation of the chamber.

  According to the sputter film forming apparatus and the sputter film forming method of the present invention, by controlling the target power according to the distance between the target and the substrate stored in the substrate holder, the rotation axis of the carousel and the bearing of the apparatus main body are offset. Variations in optical characteristics due to the core can be suppressed.

  Embodiments of a sputter film forming apparatus and a sputter film forming method of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a cross-sectional view schematically showing a configuration of a sputter film forming apparatus according to the present invention, and is a cross-sectional view seen from above. FIG. 2 is a perspective view showing the configuration of the carousel 1 and the substrate holder 9 used in the sputter deposition apparatus according to the present invention.

  The sputter film forming apparatus shown in FIG. 1 is a sputter film forming apparatus including a vacuum chamber 2 for taking in and out a drum 1 called a curl cell and a chamber 3 for performing a sputter film forming process. The vacuum chamber 2 and the chamber 3 are connected, and the vacuum chamber 2 is provided with a door 4 for carrying in and out the carousel 1. Further, a gate valve 5 is provided between the vacuum chamber 2 and the chamber 3 which is a chamber in order to evacuate each room independently. The carousel 1 is transported from the vacuum chamber 2 to the chamber 3 which is a chamber, or from the chamber 3 to the vacuum chamber 2 by a transport mechanism. The drum 1 can be rotated by a rotation mechanism 6 installed in the chamber 3, and the carousel 1 is formed in the chamber 3 by two targets 7 and 8 provided facing the side surface of the chamber. Sputter film formation can be performed on the substrate 10 provided in the plurality of substrate holders 9 above.

For film formation, for example, argon is used as a sputtering gas and oxygen is used as a reaction gas, for example, so as to flow at a constant pressure, and power is externally applied to the sputtering cathode 11 holding the A target 7 (Si in this case). When the drum 1 is rotated by the rotating mechanism 6 in the reactive sputtering state, a SiO ₂ film is formed on the substrate 10 on the drum 1 by the reactive sputtering method. Similarly, an Nb ₂ O ₅ film is formed on the substrate 10 on the drum 1 by the reactive sputtering method by applying power to the sputtering cathode 12 holding the other B target 8 (Nb in this case). . By repeating such a process, a multilayer film of SiO ₂ and Nb ₂ O ₅ is formed on the substrate 10. Although the reactive sputtering method is used for the sputtering method, an oxide sputtering method such as a plasma assist method may be used. The target 7 is made of Si and the target 8 is made of Nb. However, various materials such as Ti, Ta, Zr, oxides, nitrides, and carbides thereof can be used for the target. . The number of targets may be one or three or more. In addition, the sputtering apparatus is provided with an eccentricity measuring mechanism 13 and a target power adjusting mechanism 14.

  As shown in FIGS. 1 and 2, as one embodiment, 24 substrate holders 9 are attached to the drum 1 to form a regular 24-hedron, and each substrate holder 9 stores three substrates. Yes.

  As shown in FIG. 2, the carousel 1 is formed in a cylindrical shape, and a substrate holder 9 is attached to the outer periphery of the drum 1. A substrate 10 is arranged on each side surface of the outer periphery of the substrate holder 9 provided on the outer periphery of the drum 1. The center axis 15 of the drum 1 and the rotation axis 16 in the chamber 3 are rotatably provided so as to coincide with the center line in the chamber 3 extending in the vertical direction. The substrate holder 9 is formed in a polygonal cylinder shape such as a regular 24 square cylinder. By rotating the drum 1 in the chamber 3, the substrate holder 9 and the substrate 10 rotate around the rotation axis 16, and the chamber 3. It sequentially passes in front of the targets 7 and 8. The substrate holder 9 is not limited to a regular 24-hedron, and may be another polyhedron depending on the shape and size of the substrate 10. There is no problem in any shape and size as long as the substrate is stored in the substrate holder.

The eccentricity measuring device 13 performs a rotating operation in a state where the carousel 1 is attached to the rotating shaft 16 by the optical microsensor 18 attached in the chamber 3, and each substrate holder 9 is positioned in front of the target 7. The distance to the substrate 10 (hereinafter referred to as T / S distance 17) is measured. The optical microsensor 18 is attached in a direction perpendicular to the central axis 15 of the substrate holder 9 and is installed in a region not affected by sputtered electrons. That is, in FIG. 1, it arrange | positions at the side where the targets 7 and 8 are not arrange | positioned. Note that the sensing region 19 on the substrate holder 9 of the optical microsensor 18 is more preferably subjected to high flattening processing, mirror surface processing, or the like in order to perform highly accurate measurement. In addition, although the optical microsensor 18 is used for the measurement of the T / S distance 17, a non-contact type distance measuring device such as another magnetic sensor,
In addition, a contact-type distance measuring device such as a touch probe may be used.

  Next, inconveniences associated with eccentricity will be described. Eccentricity is a blurring of the carousel 1 during rotation that occurs due to the dimensional tolerance between the rotary shaft 16 and the central shaft 15 of the drum 1 and the mounting tolerance in the drum 1 attached to the rotary shaft 16. If this occurs, the T / S distance 17 will differ for each substrate holder 9 and the film thickness of the material deposited on the substrate 10 will need to be controlled. Here, it demonstrates further in detail using FIG. FIG. 3 is a diagram for explaining a part of the configuration of the sputter deposition apparatus according to the present invention, and FIG. 3A is a cross-sectional view schematically showing the state in which the substrate holder A is sputter deposited. FIG. 3B is a cross-sectional view schematically showing that the substrate holder B is formed by sputtering. In FIG. 3, when eccentricity has occurred, the rotating shaft 16 of the drum 1 and the central shaft 15 of the drum do not coincide. Therefore, the relationship between the distance T1 between the target 7 and the substrate holder A and the distance T2 between the target 7 and the substrate holder B becomes T1> T2 or T1 <T2. In FIG. 3, T1 <T2. Similarly, in the other substrate holders 9, the T / S distance 17 changes according to the rotation of the carousel 1. The difference between the T / S distance 17 of each substrate holder 9 and the T / S distance when the amount of eccentricity is zero is the amount of eccentricity of each substrate holder 9. When the T / S distance 17 is shortened, the probability of sputtered electron deposition increases and the film thickness on the substrate 10 also increases. As a result, the optical characteristics of the optical thin film are also shifted to the longer wavelength side, and the optical characteristics of the substrate holders 9 are also different.

  Next, the target power adjustment mechanism 14 will be described. The target power adjustment mechanism 14 is a mechanism that corrects the target power program according to the eccentricity amount of each substrate holder 9 after measuring the eccentricity amount by the eccentricity measuring device 13, and according to the eccentricity amount, This is a function of assigning target power to each substrate holder using the relationship between the amount of eccentricity and the target power stored in the memory 21 in the control PC 20 in advance.

Here, a method for deriving the relationship between the eccentricity and the target power will be described. First, the relationship between the target power of the material used for film formation and the amount of film formation rate fluctuation is examined. The fluctuation rate of the film formation rate is the fluctuation amount of the film formation rate formed in one second. Here, the target power is 6 kW and Nb ₂ O _{5 in} SiO ₂ which is the basic film formation condition in this embodiment. Then, it is standardized by the film formation rate at a target power of 4.5 kW. Actually, FIG. 4 shows the relationship between the target power and the film formation rate fluctuation amount for SiO ₂ and Nb ₂ O ₅ . As shown in FIG. 4, the target power and the film formation rate fluctuation amount are linearly proportional to each other, and the film formation rate fluctuation amount, that is, the film thickness that can be formed in the same time by reducing the target power. It can be seen that it is possible to reduce. Then, the relationship between the film thickness fluctuation amount and the eccentricity amount is examined. The film thickness fluctuation amount is the fluctuation amount of the film thickness of the formed product, and is normalized by the total film thickness of the product determined by the specification. FIG. 5 shows the relationship between the film thickness fluctuation amount and the eccentricity amount. It can be seen that the film thickness fluctuation amount and the eccentricity amount have a linear proportional relationship, and the film thickness fluctuation amount changes as the eccentricity amount changes. Further, this film thickness fluctuation amount is relative to the total film thickness of the product, and the film thickness fluctuation quantity in which the eccentricity amount contributes to the SiO ₂ film is the total film thickness fluctuation quantity × SiO ₂ film thickness / total film thickness. Nb ₂ O ₅ film contributes thickness variation in can total thickness variation × _Nb 2 _{O 5} film thickness / total film represented in thickness. From the relationship between the target power and the film formation rate variation obtained as described above, and the relationship between the film thickness variation and the eccentric amount of each target, the target power for the eccentric amount of each substrate holder is determined. This relational expression is stored in the memory 21 in advance. These relational expressions are stored for each target and each product.

Next, FIG. 6 is a flowchart relating to the sputtering film forming method of the present invention. First, the substrate holder 9 and the substrate 10 are set on the carousel 1. Next, the carousel 1 is carried into the vacuum chamber 2 and the door is closed to perform evacuation. After the vacuum chamber 2 is evacuated to a predetermined degree of vacuum, the gate valve 5 is opened, and the carousel 1 is carried into the chamber 3 by the transport mechanism. Then, the gate valve 5 is closed, and the chamber 3 is evacuated to a predetermined vacuum level. The drum 1 is rotated during the evacuation, and the eccentricity measurement device 13 performs the eccentricity measurement. In accordance with the eccentricity measurement result, the target power corresponding to each substrate holder is corrected through the target power adjustment mechanism 14. Thereafter, when the chamber 3 is evacuated to a predetermined degree of vacuum, sputtering film formation is started, and an optical multilayer film is formed.

  Here, the drum is φ960 mm, the substrate holder is a regular 24-polygonal polygonal cylinder, the size is W: 250 mm × H: 550 mm, and the substrate is W: 100 mm × H: 100 mm in which 3 sheets are stored in the vertical direction. Was used. The rotation speed of the drum during eccentricity measurement was 7 rpm, and the rotation speed during sputtering film formation was 100 rpm. FIG. 7 shows the change in half-value wavelength as the substrate holder eccentricity measured by the optical microsensor 18 when the eccentricity control is not performed and the optical characteristics of each substrate after film formation. Here, the case where the T / S distance 17 is the original distance is set to zero, and the direction in which the T / S distance 17 becomes shorter is set to be positive. Further, the amount of light transmitted through the substrate 10 after film formation is measured, and the wavelength at which the amount of transmitted light decreases by half is defined as the half-value wavelength. FIG. 7A shows the 24 substrate holders 10 sequentially numbered from arbitrary holders, and the deviation from the original T / S distance is measured as the amount of eccentricity. FIG. The measurement example of the half-value wavelength of the substrate after film formation is shown. As optical characteristics, only one measurement result located in the middle of the three substrates stored in each substrate holder is shown. As can be seen from the figure, a characteristic such as a SIN curve is shown in the rotation direction, and an eccentricity amount of about 4000 μm is observed at peak-to-peak, and a half-wavelength characteristic variation of about 8 nm is observed at peak-to-peak. Thus, it can be seen from the fact that a tendency like a SIN curve is shown in the rotation direction, there is a variation in the half-value wavelength due to the eccentricity due to the axis deviation of the rotation. FIG. 8 shows the relationship between the amount of eccentricity and the half-value wavelength. There is a linear proportional relationship between the amount of eccentricity and the half-value wavelength, and it can be seen that variation in the half-value wavelength can be reduced by reducing the amount of eccentricity. FIG. 9 shows the measurement result of the eccentricity of the fifth substrate holder when the rotation speed of the carousel is changed. The measurement is a result of measuring only one substrate holder while changing the rotation speed. As can be seen from FIG. 9, it can be seen that the eccentricity does not change even if the rotational speed is changed. That is, the rotational speed at the time of eccentricity measurement may be any rotational speed within the allowable rotational speed in the apparatus.

FIG. 10 shows a configuration diagram of a long wave pass filter film (hereinafter abbreviated as LWPF film) formed in this example. Table 1 shows the film thickness of each layer of the LWPF film formed in this example. On the glass substrate 22, Nb ₂ O ₅ layers 23 and SiO ₂ 24 layers were alternately laminated at a film pressure shown in Table 1 in 15 layers (30 layers in total).

FIG. 11 shows the target power corresponding to each derived substrate holder in the total film thickness of LWPF used in this example: 2007 nm (breakdown is SiO ₂ film thickness: 1246 nm, Nb ₂ O ₅ film thickness: 761 nm). Show. Thus, it can be seen that the target power is changed for each substrate holder according to the amount of eccentricity.

  FIG. 12 shows the half-value wavelength of the LWPF in which the film is formed by correcting with the conventional case and the eccentricity measuring mechanism 13 and the target power adjusting mechanism 14 of the present invention. The half-value wavelength is peak-to-peak, which was 8 nm in the conventional case, but is improved to 1 nm or less in the present invention. By changing the target power as in the present embodiment, variations in optical characteristics could be reduced.

  In this way, the optical characteristic distribution on the substrate can be made uniform by measuring the T / S distance for each substrate holder before sputtering film formation and controlling the target power accordingly. The embodiment of the present invention is an exemplification, and a suitable target power is set according to the substrate size and the target material.

  In this embodiment, a cylindrical drum is used as shown in FIG. 2, but the shape of this drum may be any shape that can measure the distance between the target 7 and the substrate 10. A square or conical drum may be used.

  The sputter film forming apparatus and the sputter film forming method according to the present invention suppress in-plane variation in optical characteristics due to eccentricity by adjusting the target power in accordance with the distance between the target and the substrate, and such uniformity. It is useful as a film forming apparatus and a film forming method for an optical filter such as a video apparatus having excellent optical characteristics.

The top view which shows typically the structure of the sputtering film-forming apparatus in the Example of this invention The perspective view which shows the structure of the drum and board | substrate holder in the Example of this invention. The figure explaining a part of structure of the sputtering film-forming apparatus concerning this invention The figure which shows the relationship between the target electric power and film-forming rate fluctuation | variation in a present Example The figure which shows the relationship between the film thickness fluctuation | variation and eccentricity amount in a present Example The flowchart which shows the sputtering film-forming method in the Example of this invention The figure which shows the change of a half value wavelength as each substrate holder eccentricity amount and the optical characteristic of each substrate The figure which shows the rotational speed and eccentricity of the drum in a present Example The figure which shows the relationship between the amount of eccentricity and a half value wavelength in a present Example Configuration diagram of LWPF film formed in Example The figure which shows the relationship of the target electric power corresponding to each board | substrate holder in a present Example. The figure which shows the optical characteristic in the past and this example

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Carousel 2 Vacuum chamber 3 Chamber 4 Door 5 Gate valve 6 Rotation mechanism 7, 8 Target 9 Substrate holder 10 Substrate 11, 12 Sputter cathode 13 Eccentricity measurement mechanism 14 Target power adjustment mechanism 15 Center axis 16 Rotation axis 17 T / S Distance 18 Optical microsensor 19 Sensing area 20 Control PC
21 memory

Claims (4)

A drum provided in the chamber;
A substrate holder in which a substrate is stored on the outer peripheral surface of the drum;
A target provided on the inner wall of the chamber to form a film on the substrate;
In a sputter deposition apparatus having
The substrate holder has an eccentricity measuring device that measures a distance between the target and the substrate at a position facing the target in front of the target,
A sputtering film forming apparatus, wherein a target power for each substrate holder is corrected based on the distance. The sputter deposition apparatus according to claim 1, wherein the eccentricity measuring apparatus measures a distance between the target and each substrate using a non-contact sensor. A drum is rotatably provided in the chamber,
A substrate holder for storing the substrate on the outer peripheral surface of the drum;
A target for forming a film on the base is provided on the inner wall of the chamber,
In the sputter deposition method in which the drum is deposited on the substrate while rotating around a vertical rotation axis,
Measuring the eccentricity of the rotating drum by measuring the distance between the substrate and the target;
Controlling the target power for each base holder based on the amount of eccentricity;
A sputter film forming method comprising: Measuring the eccentricity of the rotating drum by measuring the distance between the substrate and the target;
Controlling the target power for each base holder based on the amount of eccentricity;
The sputter deposition method according to claim 3, wherein the sputtering is performed during evacuation of the chamber.

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