Mask unit, film deposition apparatus, film deposition method, and method for manufacturing electronic device
The mask unit with a mask stand and positioning sections addresses the warping issue of the mask frame, enhancing pattern position accuracy and adhesion in film deposition processes for organic EL display devices.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- CANON TOKKI CORP
- Filing Date
- 2025-11-06
- Publication Date
- 2026-07-02
Smart Images
Figure JP2025038974_02072026_PF_FP_ABST
Abstract
Description
Mask unit, film forming apparatus, film forming method, and method of manufacturing an electronic device
[0001] The present invention relates to a mask unit, a film forming apparatus including the mask unit, a film forming method, and a method of manufacturing an electronic device.
[0002] Organic EL display devices (organic EL displays) are used in various application fields such as smartphones, televisions, automotive displays, VR HMDs (Virtual Reality Head Mount Displays), and the like. In particular, displays used in VR HMDs are required to form pixel patterns with high precision in order to reduce user dizziness, and further higher resolution is required.
[0003] In the manufacture of an organic EL display device, film formation on an organic light emitting element (organic EL element; OLED) constituting the organic EL display device is performed in a vacuum chamber. In film formation of an organic light emitting element, an organic material layer and a metal layer are formed on a substrate by depositing a film forming material (evaporation material) emitted from a film forming source of a film forming apparatus on the substrate through a mask on which a pixel pattern is formed. At this time, in order to deposit the film forming material emitted from the evaporation source installed on the lower surface of the vacuum chamber on the substrate through the mask, if the substrate and the mask are not accurately approximated, the degree of adhesion between the substrate and the mask may decrease, leading to product defects.
[0004] Patent Document 1 discloses a method of stretching and fixing a mask to a mask frame by welding in a mask unit (evaporation mask) including a mask and a mask frame that supports the mask so that the mask does not bend.
[0005] Japanese Unexamined Patent Application Publication No. 2022-141899
[0006] However, when the mask is stretched and fixed to the mask frame, the mask frame is deformed such as warping. The warping of the mask frame may cause a decrease in the installation accuracy of the mask frame, and thus a decrease in the pattern position accuracy in the film forming operation.
[0007] An object of the present invention is to improve the pattern position accuracy in a film forming operation.
[0008] To achieve the above objective, the present invention provides a mask unit for use in a film deposition apparatus that deposits a film-forming material onto a substrate, comprising a mask stand provided with a positioning section, wherein the mask unit placed on the mask stand comprises: a mask having a plurality of openings; a first frame to which the mask is fixed; and a second frame joined to the first frame, wherein the second frame is provided with a positioning section that engages with the positioning section of the mask stand and defines the position of the mask unit relative to the mask stand. Furthermore, to achieve the above objective, the present invention provides a film deposition apparatus for depositing a film-forming material onto a substrate, comprising: a mask stand having a reference surface and a plurality of positioning sections provided on the reference surface; and a mask unit placed on the mask stand, comprising: a mask having an opening; a first frame to which the mask is fixed; a second frame fixed to the first frame; and a mask frame having a plurality of positioning sections provided on the second frame, the plurality of positioning sections that engage with the positioning section.
[0009] According to the present invention, the pattern position accuracy in the film deposition process can be improved.
[0010] This is a schematic diagram of the film deposition apparatus according to the first embodiment. This is an enlarged view of the magnetic levitation stage according to the first embodiment. This is a top view of the magnetic levitation stage according to the first embodiment. This is a diagram of the mask unit according to the first embodiment. This is a diagram of the mask stand according to the first embodiment. This is an explanatory diagram of the engagement state of the kinematic coupling according to the first embodiment. This is an exploded view of the mask unit according to the first embodiment. This is a diagram of the deformation of the first mask frame according to the first embodiment. This is a diagram of the deformation of the second mask frame according to the first embodiment. This is an explanatory diagram of the kinematic coupling according to the first embodiment. This is an exploded view of the mask unit according to the second embodiment. This is an explanatory diagram of the organic EL display device.
[0011] The embodiments for carrying out this invention will be described in detail below with reference to the drawings, based on examples. However, the dimensions, materials, shapes, and relative arrangements of the components described in these embodiments should be appropriately modified depending on the configuration of the device to which the invention is applied and various conditions. In other words, the scope of this invention is not intended to be limited to the following embodiments.
[0012] (First Embodiment) Referring to Figures 1 to 3, a film deposition apparatus, a film deposition method, and a method for manufacturing an electronic device according to the first embodiment of the present invention will be described. Figures 1 to 3 show the XYZ axes. The Z axis is an axis parallel to the vertical direction, and the XY axes are axes parallel to the horizontal direction and perpendicular to each other.
[0013] <Film Deposition Apparatus> The film deposition apparatus 1 according to this embodiment will be described with reference to Figure 1. Figure 1 is a schematic configuration diagram of the film deposition apparatus 1 according to the first embodiment, and schematically shows the configuration of the film deposition apparatus 1 as viewed from the front in the Y direction.
[0014] The film deposition apparatus 1 comprises a vacuum chamber, a magnetic levitation stage 2 positioned inside the vacuum chamber, and a stage support 6 that fixes the magnetic levitation stage 2 to the vacuum chamber. In Figure 1, the magnetic levitation stage 2 is shown enclosed by a dotted line. The magnetic levitation stage 2 is fixed to the upper corner or upper side of the interior of the vacuum chamber by the stage support 6.
[0015] The vacuum chamber is a chamber composed of a vacuum chamber side surface 3, a vacuum chamber bottom surface 32, and a top surface which is the surface of the vacuum chamber top plate 11. While the vacuum chamber generally has a hexahedral configuration, it is not limited to this configuration. A thin film is formed on the substrate 27 via a mask 16 by the film-forming material released from an evaporation source 5, which is installed on the vacuum chamber bottom surface 32, as a film-forming source.
[0016] The mask 16 is a mask foil that is magnetic and configured to be attracted by the attraction magnet 18. The attraction magnet 18 is a magnet that can move up and down relative to the magnetic levitation stage 2. The attraction magnet 18 is configured to be able to move up and down, i.e., move in the Z direction, by a lifting mechanism 18X (see Figure 2). Various known technologies such as a ball screw mechanism or a rack and pinion mechanism can be used for the lifting mechanism 18X.
[0017] Inside the vacuum chamber, a laser displacement meter 17 is installed on a mask stand 33. The magnetic levitation stage 2 is configured so that its position can be controlled based on the measurement results from the laser displacement meter 17.
[0018] Furthermore, the film deposition apparatus 1 has a control unit 35. The control unit 35 has functions for controlling various mechanisms, the evaporation source 5, and the film deposition process. The control unit 35 can be configured by a computer having, for example, a processor, memory, storage, I / O, etc. In this case, the functions of the control unit 35 are realized by the processor executing a program stored in the memory or storage. A general-purpose personal computer may be used as the computer, or an embedded computer or PLC (programmable logic controller) may be used. Alternatively, some or all of the functions of the control unit 35 may be configured by circuits such as ASICs or FPGAs. Note that a control unit 35 may be provided for each film deposition apparatus 1, or one control unit 35 may control multiple film deposition apparatuses 1.
[0019] Next, the configuration of the vibration isolation table support section outside the vacuum chamber, i.e., on the atmospheric side, will be described. The vibration isolation table support section consists of a support frame 8, vibration isolation tables 9a and 9b, vibration isolation table bases 10a and 10b, etc. Vibration isolation table 9a is placed on the vacuum chamber top plate 11 via the vibration isolation table base 10a, and vibration isolation table 9b is placed on the vacuum chamber top plate 11 via the vibration isolation table base 10b. The support frame 8 is supported by vibration isolation tables 9a and 9b, thereby suppressing vibrations transmitted from the vacuum chamber. Vibration isolation table 9a and vibration isolation table base 10a are placed at one end of the vacuum chamber top plate 11 in the X direction, and vibration isolation table 9b and vibration isolation table base 10b are placed at the other end of the vacuum chamber top plate 11 in the X direction.
[0020] Mask guide mechanisms 12a and 12b are provided on the support frame 8. The mask guide mechanisms 12a and 12b are mechanisms that guide the vertical movement of the mask support columns 13a and 13b, which extend vertically from the outside to the inside of the vacuum chamber, and raise and lower them. The mask support column 13a is configured to be movable in the vertical direction by the mask guide mechanism 12a, and the mask support column 13b is configured to be movable in the vertical direction by the mask guide mechanism 12b.
[0021] A mask stand 33 for supporting the mask 16 is connected to the lower ends of the mask support columns 13a and 13b. In other words, the mask stand 33 is supported by the mask support columns 13a and 13b within the vacuum chamber and moves up and down together with the mask support columns 13a and 13b. The mask frame 15, which serves as a mask holding member for holding the mask 16, is brought into the vacuum chamber, i.e., the interior of the film deposition apparatus 1 (hereinafter also simply referred to as the interior of the apparatus), by a robot hand (not shown) and placed on the mask stand 33.
[0022] When the robot hand moves in and out of the device to load the mask frame 15 and substrate 27 into the device, the mask guide mechanisms 12a and 12b lower the mask stand 33 to a position that does not obstruct the movement of the robot hand. Between the vacuum chamber top plate 11 and the support frame 8, bellows 14a are provided to surround the mask support column 13a, and bellows 14b are provided to surround the mask support column 13b. When the mask guide mechanisms 12a and 12b raise and lower the mask stand 33, the bellows 14a and 14b expand and contract. These bellows 14a and 14b maintain the vacuum state inside the vacuum chamber.
[0023] Furthermore, the mask stand 33 may be configured to move not only vertically but also rotationally and translationally. By providing a rotational and translational mechanism that rotates and moves the mask stand 33 on the XY plane, it becomes easier to bring the mask and the like into the camera's field of view, and the positioning accuracy by the robot hand and positional deviations when placing the mask and the like can be reduced.
[0024] Furthermore, the film deposition apparatus 1 is equipped with alignment cameras 7a and 7b supported by a support frame 8. This suppresses vibrations transmitted from the vacuum chamber to the alignment cameras 7a and 7b, enabling high-precision measurements. A viewport for alignment measurement is installed on the top plate 11 of the vacuum chamber, and alignment measurements can be taken using the alignment cameras 7a and 7b located on the atmospheric side. Lighting fixtures 24a and 24b are installed on the underside of the mask stand 33. By utilizing the transmitted light from the lighting fixtures 24a and 24b, alignment marks 102a, 102b, 102c, and 102d (see Figure 4(b)) on the mask 16 are captured by the alignment cameras 7a and 7b. Four alignment cameras and four lighting fixtures (including those not shown) are installed, and they are configured to detect the positions of alignment marks formed on the mask 16, etc.
[0025] <Magnetic Levitation Stage> The magnetic levitation stage 2 will be explained using Figures 2 and 3. Figure 2 is an enlarged view of the magnetic levitation stage 2 shown in Figure 1. Figure 3 is a top view of the magnetic levitation stage 2 as seen from above in the Z direction. In Figure 3, the stator and the attraction magnet 18 provided on the stage support 6 are also shown in order to clarify the positional relationship between the movable element and the stator, etc.
[0026] The magnetic levitation stage 2 comprises a stage frame 31, self-weight compensating magnet movable elements 22a, 22b, 22c, 22d, and linear motor movable elements 20a, 20b, 20c, 20d. The self-weight compensating magnet movable elements 22a, 22b, 22c, 22d and the linear motor movable elements 20a, 20b, 20c, 20d are each fixed to the stage frame 31.
[0027] The self-weight compensating magnet movable elements 22a, 22b, 22c, and 22d play the role of supporting the magnetic levitation stage 2 in a non-contact manner with respect to the stage support 6 in order to cancel out the self-weight of the magnetic levitation stage 2. The linear motor movable elements 20a, 20b, 20c, and 20d play the role of generating thrust to move the magnetic levitation stage 2 in a non-contact manner with respect to the stage support 6.
[0028] Furthermore, an electrostatic chuck 25, which serves as a substrate holding member, is fixed to the lower surface of the magnetic levitation stage 2. This electrostatic chuck 25 allows the substrate 27, which is to be deposited on, to be held in place with the deposition surface facing downwards, i.e., in a face-down state.
[0029] On the lower surface of the stage support 6, the weight-compensating magnet stators 23a, 23b, 23c, and 23d are fixed so as to face the weight-compensating magnet movable elements 22a, 22b, 22c, and 22d, respectively. A magnetic force equivalent to the weight of the magnetic levitation stage 2 is generated between the movable and stator elements of the weight-compensating magnet, and the magnetic levitation stage 2 is supported by the stage support 6 in a non-contact state.
[0030] Furthermore, linear motor stators 21a, 21b, 21c, and 21d are fixed to the lower surface of the stage support 6, facing the linear motor movable elements 20a, 20b, 20c, and 20d, respectively. The thrust that moves the magnetic levitation stage 2 is generated by the change in the current value flowing through the coils built into these linear motor stators 21a, 21b, 21c, and 21d. In the vertical direction, the self-weight of the magnetic levitation stage 2 is canceled out by the self-weight compensating magnets, so the thrust generated by the linear motors is minimal. Therefore, the amount of current required is small, and the amount of heat generated by the current is minimal, preventing deformation or damage to the components due to heat. However, if necessary, the coils may be covered with a water-cooling jacket and actively cooled by circulating a coolant.
[0031] The stage frame 31 is rectangular when viewed vertically. The linear motor movable elements 20a, 20b, 20c, and 20d are positioned at four corners on the upper surface of the stage frame 31. This allows for translational drive of the magnetic levitation stage 2 in the X and Y directions and rotational drive around the Z axis. In addition, by arranging at least three linear motors (not shown) that generate thrust in the Z axis direction, it is possible to move the magnetic levitation stage 2 with six degrees of freedom. In this embodiment, the magnetic levitation stage 2 is configured to move with six degrees of freedom using linear motors arranged in a total of seven locations. Furthermore, the self-weight compensating magnet movable elements 22a, 22b, 22c, and 22d are arranged symmetrically at four locations around the center of gravity of the magnetic levitation stage 2. This allows for the application of moment force, enabling stable levitation of the magnetic levitation stage 2.
[0032] <Alignment Mechanism> The alignment mechanism (positioning mechanism) between the substrate 27 and the mask 16 will be explained. The relative position of the magnetic levitation stage 2 with respect to the mask base 33 is measured by the laser displacement meter 17. In the film deposition apparatus 1, the laser displacement meter 17 is located in a total of six places: two in the X direction, one in the Y direction, three in the Z direction, etc. Based on the information from the six laser displacement meter 17s, a geometric coordinate transformation is performed and converted into the position of the magnetic levitation stage 2 in six degrees of freedom around its center of gravity. Based on the position information of the six degrees of freedom, a control calculation is performed and a thrust command for the six degrees of freedom is determined. Based on the thrust command for the six degrees of freedom, current is passed through the coils of the seven linear motors, and the magnetic levitation stage 2 is moved, making it possible to position the magnetic levitation stage 2 with high precision relative to the mask base 33.
[0033] Furthermore, the laser displacement meter 17 is fixed near the mask 16 on the mask stand 33. This allows for direct positioning of the mask 16 and the substrate 27 in a vacuum environment without being affected by Abbe errors or other factors. In addition, the laser displacement meter 17 on the mask stand 33 is less susceptible to vibrations from the vacuum chamber due to the vibration isolation tables 9a and 9b on which the support frame 8 is mounted, enabling stable measurement. The magnetic levitation stage 2 is also supported by a non-contact, low-magnetic spring-resistance self-weight compensating magnet, and similarly, vibrations from the vacuum chamber are suppressed. With this configuration, the relative position of the magnetic levitation stage 2 and the mask stand 33 can be positioned with high precision, resulting in high-precision alignment of the substrate 27 and the mask 16.
[0034] <Mask and Substrate> The mask 16 and substrate 27 will be described in more detail. The mask 16 has multiple through-holes, which are openings corresponding to the pixel pattern, provided at equal intervals, and is configured so that the film-forming material passing through the through-holes is formed on the surface of the substrate 27. The material of the mask 16 is made of, for example, a metal foil that is resistant to thermal expansion such as Invar, or a membrane film made by processing a Si wafer into a thin film.
[0035] The mask 16 is fixed to the mask frame 15, which serves as a mask holding member. In the following description, the mask 16 and the mask frame 15, when fixed and integrated, will be referred to as the mask unit 19 (see Figure 4(a) below). It is transported by a robot hand and placed on the mask stand 33. Various known techniques can be used to fix the mask 16 and the mask frame 15, such as fixing by spot welding while the mask 16 is stretched, using mechanical clamps, or fixing by adhesive. When fixing, it is desirable to fix the mask 16 to the mask frame 15 in a way that prevents distortion of the mask 16.
[0036] Inside the vacuum chamber, the substrate 27 is held by an electrostatic chuck 25, which serves as a substrate holding member. The suction magnet 18 is configured to approach the surface of the electrostatic chuck 25 opposite to the suction surface within a non-contact range, and is configured to generate the magnetic flux necessary for attracting the mask 16. The electrostatic chuck 25 and the substrate 27 are non-magnetic materials, and the magnetic flux of the suction magnet 18 can generate an attractive force that pulls the mask 16 vertically upward. This attractive force allows the mask 16 to adhere tightly to the substrate 27. This adhesion prevents the film deposition material from wrapping around (shadowing) during film formation.
[0037] <Positioning the mask relative to the mask base> The positioning of the mask 16 relative to the mask base 33 will be explained with reference to Figures 4(a) to (c), 5(a) to (b), 6(a) to (b), 7, and 8(a) to (c). Figures 4(a) to (c) show the mask unit 19 (mask 16 and mask frame 15) according to this embodiment. Figure 4(a) is a side view of the mask unit 19, Figure 4(b) is a top view of the mask unit 19, and Figure 4(c) is a bottom view of the mask unit 19.
[0038] The mask frame 15 is a rectangular frame. The mask frame 15 has openings formed at positions corresponding to the through holes of the mask 16 when the mask 16 is fixed in place. In other words, the mask frame 15 is joined to the outer circumference of the mask 16, and during film formation, the film-forming material passes through the through holes via the openings. In this embodiment, the cross-sectional shape of the openings is rectangular.
[0039] On the lower surface 15a of the mask frame 15, there are several spherical seats 100 (three in this embodiment) which are hemispherical parts that constitute a kinematic coupling for positioning the mask frame 15 (mask unit 19) relative to the mask base 33. The spherical seats 100 are protrusions that project from the lower surface 15a. The three spherical seats 100 will be described separately as spherical seats 100a, 100b, and 100c, respectively. It is desirable that these spherical seats 100a, 100b, and 100c be installed at 120° intervals or equivalent positions with respect to the center of gravity of the mask 16. In this embodiment, the center of gravity of the mask 16 coincides with the center of the mask 16 and the center of the mask frame 15 (central center in the plan view) when the mask unit 19 is viewed from above.
[0040] In the following description, the direction along one side that constitutes the outer circumference of the mask unit 19 is referred to as the first direction D1, and the direction perpendicular to the first direction D1 along another side that constitutes the outer circumference of the mask unit 19 is referred to as the second direction D2. The ends of the mask unit 19 in the first direction D1 are referred to as the first end 19a and the second end 19b, and the ends of the mask unit 19 in the second direction D2 are referred to as the third end 19c and the fourth end 19d. When the mask unit 19 is placed on the mask stand 33, it is positioned such that the first direction D1 is parallel to the X direction and the second direction D2 is parallel to the Y direction.
[0041] The spherical seat 100a is positioned on the side of the first end 19a in the first direction D1 and on the side of the fourth end 19d in the second direction D2. The spherical seat 100b is positioned midway between the first end 19a and the second end 19b in the first direction D1 and on the side of the third end 19c in the second direction D2. The spherical seat 100c is positioned on the side of the second end 19b in the first direction D1 and on the side of the fourth end 19d in the second direction D2. In other words, the spherical seat 100b is positioned in the center of one side of the outer circumference of the mask unit 19, while the spherical seats 100a and 100c are positioned close to one end of one side of the outer circumference of the mask unit 19.
[0042] Alignment marks 102a, 102b, 102c, and 102d are provided on the upper surface 16a of the mask 16 (the surface opposite to the surface that adheres to the mask frame 15). These alignment marks 102a, 102b, 102c, and 102d are photographed by alignment cameras 7a, 7b, etc., during alignment.
[0043] Figures 5(a) and 5(b) show a mask base 33 according to this embodiment. Figure 5(a) is a side view of the mask base 33, and Figure 5(b) is a top view of the mask base 33. The reference surface 33a, which is the top surface of the mask base 33, is provided with several grooves (specifically three) that constitute a kinematic coupling. These grooves are made up of V-grooves 110 having a pair of sides that become closer to each other as they approach the bottom of the groove. The V-grooves 110 are bases on which the mask unit 19 is placed via a spherical seat 100. The three V-grooves 110 will be described separately as V-grooves 110a, 110b, and 110c, respectively.
[0044] The V-grooves 110a, 110b, and 110c are positioned to correspond to the spherical seats 100a, 100b, and 100c, respectively. The V-groove 110a corresponds to and engages with the spherical seat 100a, the V-groove 110b corresponds to and engages with the spherical seat 100b, and the V-groove 110c corresponds to and engages with the spherical seat 100c. When viewed in a direction perpendicular to the reference plane 33a, the V-grooves 110a, 110b, and 110c are positioned such that the extension direction of the V-grooves points toward the center of the mask base 33, that is, toward the center of gravity of the mask 16 when the mask unit 19 is placed on the mask base 33.
[0045] As described above, in the present embodiment, the kinematic coupling is composed of a spherical seat 100 as a positioning target portion and a V-groove portion 110 as a positioning portion. A plurality of spherical seats 100 are provided on the lower surface 15a of the mask frame 15, and a plurality of V-groove portions 110 are provided on the reference surface 33a of the mask stage 33. When the mask 16 is placed on the mask stage 33, each spherical seat 100 is fitted into the corresponding V-groove portion 110, so that a kinematic coupling is formed in which the relative positioning of six degrees of freedom between the mask frame 15 and the mask stage 33 is performed, and the positioning is accurately performed. By this kinematic coupling, the mask frame 15 and the mask stage 33 are mutually constrained in six degrees of freedom, and their relative positional relationships are fixed.
[0046] In the present embodiment, as the kinematic coupling, a configuration in which the spherical seats 100 are provided on the mask frame 15 and the groove portions are provided on the mask stage 33 is shown, but the configuration is not limited to this. For example, a configuration in which the spherical seats constituting the kinematic coupling are provided on the mask stage 33 and the groove portions constituting the kinematic coupling are provided on the mask frame 15 can also be adopted. Further, in the present embodiment, an example of the configuration of the V-groove portion and the spherical seat as the positioning portion and the positioning target portion constituting the kinematic coupling is shown, but the kinematic coupling is not limited to these configurations, and other known techniques can also be adopted. For example, the positioning portion may be constituted by a convex portion having no spherical surface, and the positioning target portion may be constituted by a concave portion having no V-groove.
[0047] In the present embodiment, illuminations 24a, 24b, 24c, and 24d are embedded in the mask stage 33. In the case of the present embodiment, the illuminations of 24a, 24b , 24c, and 24d irradiate the alignment marks 102a, 102b, 102c, and 102d, and the transmitted light is photographed to perform alignment.
[0048] By repeatedly depositing a film on the substrate 27, the film-forming material is deposited on the mask 16. Therefore, it is necessary to replace the mask 16 every time a film is deposited on the substrate 27 a predetermined number of times. By lowering the mask stage 33 together with the mask support columns 13a and 13b by the mask guide mechanisms 12a and 12b, the gap between the electrostatic chuck 25 holding the substrate 27 and the mask stage 33 is widened. In this state, a robot hand (not shown) enters the apparatus, the mask unit 19 is carried out from the mask stage 33, and a new mask unit 19 is placed on the mask stage 33.
[0049] FIGS. 6(a) and 6(b) are diagrams showing an example of the engagement state between the spherical seat 100 and the V-groove portion 110 of the kinematic coupling. FIG. 6(a) shows a state in which the V-groove portion 110 and the spherical seat 100 are in contact at two points, contact points 120a and 120b. The contact point 120a is the contact point between one side surface of the V-groove portion 110 and the spherical seat 100, and the contact point 120b is the contact point between the other side surface of the V-groove portion 110 and the spherical seat 100. By achieving such an engagement state (contact state), six-degree-of-freedom positioning is performed, and the mask unit 19 can be accurately positioned with respect to the mask stage 33.
[0050] FIG. 6(b) shows a state in which the V-groove portion 110 and the spherical seat 100 are in contact at one point, contact point 12**c**. At this time, the spherical seat 100 contacts only one side surface of the V-groove portion 110. When placing the mask frame 15 with the robot hand, depending on the positioning accuracy of the transfer robot, the V-groove portion 110 and the spherical seat 100 may be in a state of contacting at one point, contact point 120c, as shown in FIG. 6(b). In order to securely and accurately fix the mask unit 19 to the mask stage 33, it is desirable that the mask unit 19 slides by its own weight from the one-point contact state shown in FIG. 6(b) to the two-point contact state shown in FIG. 6(a). Therefore, it is suitable to select the materials of the V-groove portion 110 and the spherical seat 100 or apply a coating to reduce the friction coefficient on one or both surfaces so that the mask unit 19 slides by its own weight to a two-point contact state.
[0051] However, even with a coating, wear of the coating can sometimes result in a single-point contact state as shown in Figure 6(b). Therefore, in this embodiment, a method is employed to ensure that the kinematic coupling is properly fitted (the ball seat 100 and the V-groove 110 are properly fitted) even when the mask frame 15 does not slip due to its own weight and does not reach the state shown in Figure 6(a).
[0052] <Mask Unit> The mask unit 19 will be described in more detail. Figure 7 is an exploded cross-sectional view of the mask unit 19 according to this embodiment. The mask frame 15 of the mask unit 19 consists of a first frame 200 to which the mask 16 is fixed, and a second frame 201 on which a plurality of spherical seats 100 (100a, 100b, 100c) are provided. In other words, the mask unit 19 consists of the mask 16, the first frame 200, and the second frame 201. The mask unit 19 is an essential unit for performing the film deposition operation and can be considered as one of the components of the film deposition apparatus 1.
[0053] The first frame 200 and the second frame 201 are rectangular frames with an opening formed in the center, and their outer periphery and opening shapes are identical. Figure 7 is a cross-sectional view of the through-hole of the mask 16 and the openings of the first frame 200 and the second frame 201. The second frame 201 has a first surface 201a that contacts the first frame 200 and a second surface 201b opposite to the first surface 201a. The second surface 201b is the surface on which a plurality of spherical seats 100 are provided and is the same surface as the lower surface 15a of the mask frame 15. The first frame 200 has a third surface 200a to which the mask 16 is fixed and a fourth surface 200b that contacts the first surface 201a of the second frame 201.
[0054] The first frame 200 and the second frame 201 are joined together by fastening their four corners with bolts 202, so that the first surface 201a and the fourth surface 200b are in contact. In this example, bolt holes are formed in the second frame 201 through which the bolts 202 are inserted, and the seating surface of the bolts 202 is in contact with the second frame 201. The first frame 200 also has screw holes for which the threaded portion of the bolts 202 is fixed. With this configuration, the second frame 201 is detachably attached (joined) to the first frame 200.
[0055] Note that the fixing location and number of bolts 202 are not limited to the above configuration. Also, the joining member (joining means) for joining the first frame 200 and the second frame 201 is not limited to bolts 202. However, it is preferable that the second frame 201 and the first frame 200 are configured to be detachable from each other. As the film deposition on the substrate 27 is repeated, the film deposition material is repeatedly deposited on the mask 16, so the mask 16 needs to be cleaned. According to the configuration of this embodiment, when cleaning the film deposition material deposited on the mask 16, the first frame 200 and the second frame 201 are separated, and only the mask 16 and the first frame 200 are cleaned. This eliminates the need to readjust the individual positions of the highly adjusted spherical seats 100 (100a, 100b, 100c).
[0056] Figures 8(a) to 8(c) show the deformation of the first frame 200 caused by the tensioning of the mask 16. Figure 8(a) is a cross-sectional view of the mask 16 and mask frame 15 seen from the side, Figure 8(b) is a bottom view of the mask 16 and first frame 200, and Figure 8(c) is a perspective view of the mask frame 15. In Figures 8(a) to 8(c), the spherical seat 100 and alignment marks 102a to 102d are not shown, and in Figure 8(c), the mask 16 is not shown.
[0057] The first frame 200 is made of metal. The mask 16 is joined to the four sides of the outer circumference of the metal first frame 200 by welding. However, the means of joining the mask 16 and the first frame 200 are not limited to welding, and other means may be used.
[0058] The mask 16 is tensioned and fixed to the first frame 200. In other words, a force is applied to the first frame 200 in the direction that causes the mask 16 to contract. Consequently, the first frame 200 to which the mask 16 is welded undergoes deformation 203 (203a, 203b, 203c, 203d) such that the corners lift up, as shown in Figure 8(c). In this embodiment, the lifting of the corners means that the corners deform in the direction from the fourth surface 200b toward the third surface 200a. In other words, each side constituting the outer periphery of the first frame 200 bends in a roughly arc shape.
[0059] Figures 9(a) and 9(b) show the deformation of the second frame 201 before and after joining the first frame 200 and the second frame 201. Figure 9(a) shows the state before joining the first frame 200 and the second frame 201, and Figure 9(b) shows the state after joining the first frame 200 and the second frame 201.
[0060] Because the first frame 200 to which the mask 16 is fixed is deformed, when the first frame 200 and the second frame 201 are joined, the second frame 201 also deforms in the same way as the first frame 200. In other words, the second frame 201 joined to the first frame 200 undergoes deformation 204 (204a, 204b, 204c, 204d) in the same direction as the first frame 200. Consequently, the corners of the second frame 201 also deform so that they lift up relative to the center of each side. At this time, the amount of deformation 204 (displacement) of the second frame 201 is smaller than the amount of deformation 203 (displacement) of the first frame 200 before the second frame 201 was joined. This is because the deformation of the first frame 200 is corrected by the second frame 201. The deformation of the entire mask unit 19 is also similar to deformation 204.
[0061] The positions where the spherical seats 100a and 100c are placed are closer to the corners of the second frame 201 compared to the spherical seat 100b. Therefore, when deformation 204 occurs, the relative positions of the spherical seats 100a and 100c with respect to the spherical seat 100b change. In particular, the relative positions in the vertical direction change significantly, and the spherical seats 100a and 100c tend to move to a higher position relative to the spherical seat 100b (away from the mask base 33). Therefore, if the amount of protrusion (height) of the spherical seats 100a to 100c from the second surface 201b is the same, and the height of the V-groove portions 110a to 110c from the reference surface 33a is the same, the second frame 201 will be positioned at an angle to the mask base 33. This, in turn, leads to a deterioration in the parallelism between the mask 16 of the mask unit 19 and the substrate 27, i.e., a deterioration in adhesion.
[0062] Therefore, in this embodiment, the amount of protrusion of the ball seats 100a and 100c from the second surface 201b is adjusted to be greater than the amount of protrusion of the ball seat 100b from the second surface 201b. Figures 10(a) and (b) are explanatory diagrams of the kinematic coupling. Figure 10(a) is a schematic cross-sectional view showing the relationship of the protrusion amounts of each ball seat 100. Figure 10(b) is a schematic diagram showing the engagement position of the ball seat 100 and the V-groove 110.
[0063] In the first embodiment, if the amount of protrusion of the spherical seat 100b (first protrusion) from the second surface 201b is defined as the first protrusion amount P1, then the amount of protrusion of the spherical seats 100a and 100c (second and third protrusions) from the second surface 201b is set to a second protrusion amount P2, which is greater than the first protrusion amount P1. More specifically, when the deformed mask unit 19 is placed on the mask stand 33, the protrusion amounts of each spherical seat 100a to 100c are adjusted so that the mask 16 and the substrate 27 become closer to parallel. With this configuration, the degree of adhesion between the mask 16 and the substrate 27 can be improved, and the pattern position accuracy in the film deposition operation can be improved.
[0064] In the first embodiment, the radii of the spherical surfaces of each spherical seat 100a to 100c are the same, and only the amount of protrusion differs. Therefore, the height H1 from the reference surface 33a at the contact point C1 between the spherical seat 100b and the V-groove 110b, and the height H2 from the reference surface 33a at the contact point C2 between the spherical seat 100a and the V-groove 110a are the same.
[0065] Furthermore, as a method for adjusting the protrusion amount of the spherical seat 100, the protrusion amount of spherical seats 100 of the same radius may be changed, or the diameter (outer shape) of the spherical seat 100 may be changed. Alternatively, the protrusion amount of the spherical seat 100 may be adjusted by inserting a shim between the spherical seat 100 and the second frame 201. Alternatively, the parallelism between the substrate 27 and the mask 16 may be improved by inserting a shim between the first frame 200 and the second frame 201. In addition, instead of the spherical seat 100, the height of the V-groove 110 or the angle of the V-groove may be adjusted. For example, if the height of the V-groove 110b (first base) from the reference surface 33a is set as the first height, and the height of the V-groove 110a, 110c (second base, third base) from the reference surface 33a is set as a second height that is higher than the first height, the same effect as in the first embodiment can be obtained. Here, the height of the V-groove portion 110 from the reference surface 33a is the height of the opposing surface forming the V-groove from the reference surface 33a, and corresponds to the height of the contact point with the ball seat 100 from the reference surface 33a (for example, heights H1, H2). Alternatively, the configuration may be such that both the amount of protrusion of the ball seat 100 and the height of the V-groove portion 110 are adjusted.
[0066] The amount of protrusion of the spherical seat 100 may be determined experimentally or determined in advance by calculation using numerical analysis, etc. For example, a prototype mask unit 19 in which the protrusion amounts of all spherical seats 100 are the same may be manufactured, the inclination angle of the surface of the mask unit 19 (for example, the upper surface 16a) with respect to the reference surface 33a may be obtained, and the protrusion amounts of each spherical seat 100 may be adjusted and set so that the inclination angle becomes zero.
[0067] Furthermore, even when the spherical seat 100 and the V-groove portion 110 are in a single-point contact state as shown in Figure 6(b), the degree of adhesion between the mask 16 and the substrate 27 can be increased by adjusting the amount of protrusion of each spherical seat 100 while taking that contact state into account.
[0068] Furthermore, various known methods can be used to provide the convex portion, such as the spherical seat 100, on the second frame 201. For example, a spherical or hemispherical member may be prepared, a groove for arranging the member may be provided in the second frame 201, and the member may be fixed to the second frame 201 by adhesive or welding. Alternatively, a hemispherical member having a flat surface may be prepared and fixed to the second surface 201b of the second frame 201. Alternatively, the second frame 201 and the convex portion may be integrally formed by additive manufacturing or the like.
[0069] Furthermore, in this embodiment, the second frame 201 is formed with a greater thickness than the first frame 200. The second frame 201 is made of ceramic. In other words, the ceramic second frame 201 has a higher Young's modulus and higher rigidity compared to the metal first frame 200, and therefore has a more highly accurate flat surface with superior flatness. Accordingly, by joining the first frame 200 to the second frame 201, the shape of the first frame 200 is corrected to improve deformation 203. With this configuration, a highly accurate flat surface of the mask 16 can be created with respect to the mask base 33. As a result, the adhesion of the mask 16 to the substrate 27 is improved, and shadows due to wrapping around the substrate can be suppressed.
[0070] In this embodiment, by making the first frame 200 out of metal, welding becomes easier when the mask 16 is made of metal mask foil, and the jointability can be improved. Furthermore, by forming the second frame 201, to which the mask 16 is not joined, out of a material with higher rigidity than the first frame 200, the amount of deformation of the mask frame 15 caused by the joining of the mask 16 can be reduced. In other words, it is preferable to make the second frame 201 more rigid than the first frame 200, or to form it out of a highly rigid material, while taking into consideration the jointability of the mask 16. Here, high rigidity means that it has high resistance to deformation (small amount of deformation) in particular to the tensile force caused by the mask 16.
[0071] (Second Embodiment) Next, a second embodiment of the present invention will be described. The configuration of the mask unit in the second embodiment differs from that of the first embodiment. Hereinafter, only the differences between the configuration of the second embodiment and that of the first embodiment will be described. Components in the second embodiment that are the same as those in the first embodiment will be denoted by the same reference numerals and their descriptions will be omitted.
[0072] <Mask Unit> The mask unit 219 according to the second embodiment will now be described. Figure 11 is an exploded cross-sectional view of the mask unit 219 according to the second embodiment. The mask unit 219 consists of a first frame 200, a second frame 201, a first mask 220 fixed to the first frame 200, a second mask 221 fixed to the second frame 201, and a third mask 222.
[0073] The configuration of the first frame 200 according to the second embodiment differs from that of the first embodiment in that a groove having a fixing surface 201c for fixing the second mask 221 is formed on the first surface 201a. However, the amount of protrusion of the spherical seat 100 is adjusted to improve the parallelism between the substrate 27 and the mask 16, which is the same as in the first embodiment.
[0074] The first mask 220 of the second embodiment has the same configuration as the mask 16 of the first embodiment and is fixed to the third surface 200a of the first frame 200. The second mask 221 is fixed to a fixed surface 201c that faces the same direction as the first surface 201a. The fixed surface 201c is the bottom surface of a groove formed in the first surface 201a and is located closer to the second surface 201b than to the first surface 201a. The third mask 222 is fixed to the second surface 201b by bolts 202. The second mask 221 may also be fixed to the fixed surface 201c by bolts 202, or it may be joined by other methods such as welding.
[0075] The configuration of the openings in the second mask 221 and the third mask 222, that is, the shape and position of the through holes, is the same as the configuration of the openings in the first mask 220. With this configuration, compared to a configuration in which only one mask is provided in the mask unit 19, the vapor deposition material passing through the openings of each mask is limited to components with higher straight-line propagation. The vapor deposition operation is performed with the first mask 220 attracted to the substrate 27 by the attraction magnet 18. At this time, if there is a gap between the mask 16 and the substrate 27, the vapor deposition material may wrap around the gap and cause shadows. However, with the configuration of the second embodiment, the vapor deposition material passing through the mask unit 19 can be carefully selected to have components with higher straight-line propagation, so that the wrapping of the vapor deposition material can be suppressed, and consequently, the occurrence of shadows can be suppressed.
[0076] The first mask 220 is a Fine Metal Mask (FMM) having openings with multiple fine through-holes. The thickness of the second mask 221 and the third mask 222 is greater than that of the first mask 220. Unlike the first mask 220, the second mask 221 and the third mask 222 do not need to be attracted by the suction magnet 18, making it easier to increase their thickness compared to the first mask 220. Increasing the thickness of the masks makes it possible to process the openings (through-holes) with higher precision.
[0077] Furthermore, the second mask 221 and the third mask 222 are fixed to the second frame 201 in a detachable manner. Therefore, similar to the first frame 200, the second mask 221 and the third mask 222 can also be removed from the second frame 201 for cleaning and regeneration, thus providing high cleaning efficiency. In addition, because the second mask 221 and the third mask 222 are provided on the second frame 201, film-forming material is less likely to directly deposit on the second frame 201 itself. Therefore, the number of times the second frame 201 needs to be cleaned can be reduced, and the second frame 201 can be maintained with high rigidity and high precision in its flatness.
[0078] In this embodiment, two masks were fixed to the second frame 201, but the configuration is not limited to this. For example, only one of the second mask 221 and the third mask 222 may be fixed to the second frame 201, or three or more masks may be fixed to the second frame 201.
[0079] <Method for Manufacturing Electronic Devices> An example of a method for manufacturing electronic devices using the film deposition apparatus 1 according to each of the above embodiments will be described. Below, the configuration and manufacturing method of an organic EL display device will be illustrated as an example of an electronic device. First, the organic EL display device to be manufactured will be described. Figure 12(a) is an overall view of the organic EL display device 560, and Figure 12(b) shows the cross-sectional structure of one pixel.
[0080] As shown in Figure 12(a), the display area 561 of the organic EL display device 560 has multiple pixels 562, each having multiple light-emitting elements, arranged in a matrix. As will be explained in detail later, each light-emitting element has a structure comprising an organic layer sandwiched between a pair of electrodes. Here, a pixel refers to the smallest unit that enables the display of a desired color in the display area 561. In the organic EL display device according to this embodiment, the pixels 562 are composed of a combination of a first light-emitting element 562R, a second light-emitting element 562G, and a third light-emitting element 562B, which emit different light from each other. The pixels 562 are often composed of a combination of a red light-emitting element, a green light-emitting element, and a blue light-emitting element, but they may also be a combination of a yellow light-emitting element, a cyan light-emitting element, and a white light-emitting element, and are not particularly limited as long as there is at least one color.
[0081] Figure 12(b) is a schematic partial cross-sectional view along line A-A in Figure 12(a). Pixel 562 has an organic EL element on a substrate 563, comprising a first electrode (anode) 564, a hole transport layer 565, one of the light-emitting layers 566R, 566G, or 566B, an electron transport layer 567, and a second electrode (cathode) 568. Of these, the hole transport layer 565, the light-emitting layers 566R, 566G, 566B, and the electron transport layer 567 are organic layers. In this embodiment, the light-emitting layer 566R is a red-emitting organic EL layer, the light-emitting layer 566G is a green-emitting organic EL layer, and the light-emitting layer 566B is a blue-emitting organic EL layer. The light-emitting layers 566R, 566G, and 566B are formed in patterns corresponding to light-emitting elements (sometimes described as organic EL elements) that emit red, green, and blue light, respectively. Furthermore, the first electrode 564 is formed separately for each light-emitting element. The hole transport layer 565, the electron transport layer 567, and the second electrode 568 may be formed in common for multiple light-emitting elements 562R, 562G, and 562B, or they may be formed for each light-emitting element. In addition, an insulating layer 569 is provided between the first electrode 564 and the second electrode 568 to prevent short circuits caused by foreign matter. Furthermore, since the organic EL layer deteriorates due to moisture and oxygen, a protective layer 570 is provided to protect the organic EL element from moisture and oxygen.
[0082] In Figure 12(b), the hole transport layer 565 and the electron transport layer 567 are shown as a single layer, but depending on the structure of the organic EL display element, they may be formed as multiple layers including a hole blocking layer and an electron blocking layer. Furthermore, a hole injection layer having an energy band structure that allows for smooth injection of holes from the first electrode 564 to the hole transport layer 565 can be formed between the first electrode 564 and the hole transport layer 565. Similarly, an electron injection layer can be formed between the second electrode 568 and the electron transport layer 567.
[0083] Next, an example of a method for manufacturing an organic EL display device will be described in detail. First, a circuit (not shown) for driving the organic EL display device and a substrate 563 on which the first electrode 564 is formed are prepared.
[0084] An acrylic resin is formed on a substrate 563 on which the first electrode 564 is formed by spin coating. The acrylic resin is then patterned by lithography to form an insulating layer 569 in the area where the first electrode 564 is formed. This opening corresponds to the light-emitting region where the light-emitting element actually emits light.
[0085] A substrate 563 patterned with an insulating layer 569 is brought into the first film deposition apparatus, the substrate is held by a substrate support unit, and a hole transport layer 565 is deposited as a common layer on the first electrode 564 of the display area. The hole transport layer 565 is deposited by vacuum deposition. In practice, the hole transport layer 565 is formed to a size larger than the display area 561, so a high-resolution mask is not required.
[0086] Next, the substrate 563, on which the hole transport layer 565 has been formed, is loaded into a second film deposition apparatus and held by a substrate support unit. Alignment of the substrate and the mask (first alignment and second alignment) is performed, the substrate is placed on the mask, and a red light-emitting layer 566R is formed on the portion of the substrate 563 where the red light-emitting elements are to be placed.
[0087] Similar to the deposition of the light-emitting layer 566R, a light-emitting layer 566G that emits green light is deposited using a third deposition apparatus, and then a light-emitting layer 566B that emits blue light is deposited using a fourth deposition apparatus. After the deposition of the light-emitting layers 566R, 566G, and 566B is completed, an electron transport layer 567 is deposited over the entire display area 561 using a fifth deposition apparatus. The electron transport layer 567 is formed as a common layer for the three colored light-emitting layers 566R, 566G, and 566B.
[0088] The substrate, with the electron transport layer 567 formed on it, is moved to a sputtering apparatus to deposit the second electrode 568, and then moved to a plasma CVD apparatus to deposit the protective layer 570, thereby completing the organic EL display device 560.
[0089] From the time the substrate 563 with the insulating layer 569 patterned is loaded into the film deposition apparatus until the deposition of the protective layer 570 is completed, exposure to an atmosphere containing moisture or oxygen may cause the light-emitting layer made of organic EL material to deteriorate due to moisture or oxygen. Therefore, in this example, the loading and unloading of substrates between film deposition apparatuses is performed under a vacuum atmosphere or an inert gas atmosphere.
[0090] 16...Mask foil, 19...Mask unit, 27...Substrate, 33...Mask stand, 100a, 100b, 100c...Spherical base (positioning part), 110a, 110b, 110c...V-groove part (positioning part), 200...First frame, 201...Second frame
Claims
1. A mask unit used in a film deposition apparatus for depositing a film deposition material on a substrate, comprising a mask stand equipped with a positioning section, wherein the mask unit placed on the mask stand comprises: a mask having a plurality of openings; a first frame to which the mask is fixed; and a second frame joined to the first frame, wherein the second frame is provided with a positioning section that engages with the positioning section of the mask stand and defines the position of the mask unit relative to the mask stand.
2. The mask unit according to claim 1, wherein the positioning portion is a protrusion that protrudes from the second surface of the second frame opposite to the first surface that contacts the first frame, and the second frame is provided with a first protrusion, the amount of which it protrudes from the second surface is a first protrusion, and a second protrusion, the amount of which it protrudes from the second surface is a second protrusion, which is higher than the first protrusion.
3. The mask unit according to claim 1, characterized in that the positioning portion is a V-groove portion having a pair of opposing surfaces forming a V-shaped cross-section, and the positioning portion is a spherical seat having a spherical surface that contacts the opposing surfaces.
4. The mask unit according to claim 1, characterized in that the first frame and the second frame are rectangular frames, and the second frame has a plurality of bolts that fix the four corners of the second frame to the four corners of the first frame.
5. The mask unit according to claim 1, characterized in that the second frame has higher rigidity than the first frame.
6. The mask unit according to claim 1, further comprising a second mask having a plurality of openings and being detachably fixed to the second frame, when the mask is designated as the first mask.
7. The mask unit according to claim 6, characterized in that the thickness of the second mask is greater than the thickness of the first mask.
8. A film deposition apparatus comprising: a mask unit according to any one of claims 1 to 7 having a plurality of positioning parts; and a mask base having a plurality of positioning parts and a reference surface on which the plurality of positioning parts are provided, wherein the plurality of positioning parts include a first base having a height from the reference surface that is a first height and a second base having a height from the reference surface that is a second height higher than the first height, and the plurality of positioning parts include a plurality of convex members protruding from the second surface of the second frame opposite to the first surface of the second frame that is in contact with the first frame.
9. A film deposition apparatus for depositing a film-forming material onto a substrate, comprising: a mask stand having a reference surface and a plurality of positioning parts provided on the reference surface; and a mask frame having a mask unit placed on the mask stand, the mask having an opening; a first frame to which the mask is fixed; a second frame fixed to the first frame; and a plurality of positioning parts provided on the second frame, the plurality of positioning parts engaging with the positioning parts.
10. A method for forming a film, characterized in that the mask unit according to any one of claims 1 to 7 is placed on the mask stand of the film forming apparatus such that the positioning portion engages with the positioning portion.
11. A method for forming a film, characterized in that a film is formed using the film forming apparatus described in claim 9, with the mask unit placed on the mask stand of the film forming apparatus such that the positioning portion engages with the positioning portion.
12. A method for manufacturing an electronic device, characterized by manufacturing an electronic device using the film formation method described in claim 10.
13. A method for manufacturing an electronic device, characterized by manufacturing an electronic device using the film formation method described in claim 11.