JP2012219280A - Support structure of tray, plasma cvd apparatus, and vacuum treatment apparatus for solar cell production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve flatness of a tray supported by a lifting and lowering device when performing treatment on a substrate placed on the tray for mounting a workpiece.SOLUTION: A plurality of trays T on a substrate cart K are supported by conveying rollers R on a substrate conveying device 70 at the lower surfaces of a pair of side edges. A plurality of lifting and lowering devices 50 are arranged beneath the substrate cart K, and the lower surface of the tray T is supported by a holding part 52 on the tip side of each lifting and lowering device 50 via a support plate 53. A thin film is formed on the substrate W mounted on the tray T while the supporting surface of the lower surface of the tray T supported by the holding part 52 of each lifting and lowering devices 50 and the supporting surface of the lower surface of the tray T supported by the plurality of conveying rollers R are set to such a position that the lower surface of the tray T has the same height.

Description

  The present invention relates to, for example, a tray support structure on which a substrate to be processed is mounted in a vacuum processing apparatus, a plasma CVD apparatus, and a vacuum processing apparatus for manufacturing a solar cell.

When a thin film is formed on a substrate (work) by a CVD apparatus, a sputtering apparatus, or a vapor deposition apparatus, the substrate is mounted on a tray on which the work is mounted, and is transported into a vacuum or high-temperature vacuum processing chamber to form a film.
For example, in a plasma CVD apparatus, a tray on which a work is mounted is carried into a preheating chamber of the plasma CVD apparatus from an external station by a transfer device. And after preheating in a preheating chamber, it is conveyed from a preheating chamber to a vacuum processing chamber by another conveyance apparatus, and processes, such as film-forming, are performed in a vacuum processing chamber.
In this case, in ion beam sputtering film formation and the like, a film formation apparatus for raising a tray transported from a load lock chamber to a film formation chamber by a horizontal transport apparatus by a lifting device and forming a film on a workpiece in that state is known. (For example, refer to FIG. 5 of Patent Document 1).

JP-A-7-316813

  As described in Patent Document 1, when a film is formed in a state in which a workpiece is pushed up by a lifting device, the tray is deformed due to its own weight or film stress during film formation, and the flatness becomes rough. For this reason, the dispersion | variation in the film thickness of the thin film formed in the workpiece | work on a tray becomes large, and the characteristic of a workpiece | work falls.

The tray support structure according to the present invention includes a plurality of transport rollers for supporting a workpiece mounting tray on the lower surfaces of a pair of side edges facing each other, and a holding portion for supporting the lower surface of the tray at a position different from the rollers. At least one lifting device, a supporting surface of the lower surface of the tray by the holding unit of the lifting device, and a supporting surface of the lower surface of the tray by a plurality of conveying rollers at a height position where the lower surface of the tray is flush with each other And a control means for processing the work mounted on the tray in the set state.
A plasma CVD apparatus according to the present invention includes the above support structure.
The vacuum processing apparatus for manufacturing a solar cell according to the present invention includes the above support structure.

  According to this invention, since the lower surface of the tray is supported by the lifting device and the conveying roller, and the height position of the lower surface of the supported tray is the same, the flatness of the tray can be improved.

Sectional drawing of the plasma CVD apparatus as one Embodiment which has the support structure of the tray of this invention. The perspective view of the support structure of the tray of this invention illustrated in FIG. FIG. 3 is an enlarged plan view of the substrate cart illustrated in FIG. 2. Sectional drawing which follows the IV-IV line | wire of FIG. 2 in a film-forming state. Sectional drawing which follows the VV line | wire of FIG. 2 in a film-forming state. The figure which shows a test result.

(overall structure)
Hereinafter, the tray support structure of the present invention will be described with reference to the drawings.
FIG. 1 is an overall configuration diagram schematically showing a configuration of a plasma CVD apparatus as an embodiment having a tray support structure of the present invention.
The plasma CVD apparatus 100 in this embodiment includes a vacuum preheating chamber 10 that also serves as a load / unload chamber and a vacuum processing chamber 20. The external station 30 is arranged separately from the plasma CVD apparatus 100. In the vacuum preheating chamber 10, substrate transfer devices 11 and 13 are arranged in two upper and lower stages, and a lamp heater 15 is installed above the substrate transfer devices 11 and 13. The lamp heater 15 is driven by a heater driving unit (not shown).

  The vacuum preheating chamber 10 is connected to an exhaust system 10a and a gas introduction system 10b, and is configured to be switchable between air release and vacuum sealing, and heats a substrate (workpiece) W such as a silicon substrate. . Each of the substrate transport apparatuses 11 and 13 has a structure in which a plurality of rollers R are rotatably supported on a frame, and the substrate cart K on which the substrates W are mounted is transported by rotating the rollers R. The substrate transfer devices 11 and 13 are configured to be able to swing clockwise and counterclockwise, respectively.

  In the vacuum processing chamber 20, a substrate transfer device 70, an RF electrode 22, and a sheathed heater 23 are installed. The RF electrode 22 is connected to a plasma discharge control unit (not shown). An exhaust system 20a and a gas introduction system 20b are connected to the vacuum processing chamber 20 by pipes, and processing under a predetermined gas pressure, for example, vacuum processing such as film formation and etching is performed. The substrate transport device 70 has a structure in which a pair of transport mechanisms in which a plurality of rollers R are rotatably supported on a frame are arranged on the left and right in the width direction, and the substrate W is mounted by rotating the rollers R. The board cart K is transported. The substrate transfer device 70 is configured to be able to swing clockwise and counterclockwise. The sheathed heater 23 is disposed inside the pair of transport mechanisms in the width direction.

  A plurality of lifting devices 50 are disposed outside the vacuum processing chamber 20. Each lifting device 50 includes a rod 51 that extends from an opening provided in the wall of the vacuum processing chamber 20 into the vacuum processing chamber. Although not shown in the drawings, a sealing material for sealing the inside is provided at each rod 51 and the opening of the wall portion of the vacuum processing chamber 20. As will be described in detail later, the tips of the rods 51 come into contact with the lower surfaces of the plurality of trays T constituting the substrate cart K, and the rods 51 are moved up and down to raise or lower the substrate cart K. Each lifting device 50 is controlled to move up and down by a lifting device driving unit (not shown).

  The vacuum preheating chamber 10 is provided with a gate G1 facing the external station 30 side, and a gate G2 is provided at the boundary between the vacuum preheating chamber 10 and the vacuum processing chamber 20. The gate G1 is opened when the substrate W is carried in and out of the plasma CVD apparatus 100 together with the transfer tray, and is closed at times other than carrying in and out to seal the vacuum preheating chamber 10. The gate G2 is opened when the substrate W is moved in and out between the vacuum preheating chamber 10 and the vacuum processing chamber 20 together with the transfer tray, and is closed at other times.

  A substrate transfer device 18 is provided in the external station 30, holds the unprocessed substrate W and supplies it to the plasma CVD apparatus 100, and receives the processed substrate W from the plasma CVD apparatus 100 and is shown in the figure. Do not store in stocker. The substrate transfer device 18 is configured to be movable between an upper position indicated by a solid line and a lower position indicated by a dotted line.

  The plasma CVD apparatus 100 has a control unit having a microcomputer, and controls driving of the heater driving unit, the plasma discharging unit, the substrate transport device driving unit, and the lifting device driving unit by a program incorporated in the microcomputer. . In addition, the flow control valves provided in the introduction systems of the exhaust system 10a, the gas introduction system 10b, the exhaust system 20a, and the gas introduction system 20b connected to the vacuum preheating chamber 10 are opened and closed. Control and adjust the gas flow into and out of the chamber. Further, the temperature of the lamp heater 15 and the sheathed heater 23 is controlled to monitor the film forming temperature of the substrate W.

(Substrate transport)
The conveyance of the substrate W will be described.
First, the substrate transfer device 18 is arranged on the upper stage side of the external station 30 with the substrate cart K placed thereon.
In this state, the substrate W before processing is mounted on the substrate cart K by a transporter (not shown) such as a vacuum suction transporter.

The substrate cart K is made of carbon and has a much larger area than the substrate W. The gate G1 is opened, by rotating the roller R of the substrate transfer apparatus 11 in the roller R and the vacuum preheating chamber 10, the substrate transfer device 18, the substrate cart K is moved in the direction of arrow X ₁ together with the substrate W The substrate is transferred onto the substrate transfer device 11 in the vacuum preheating chamber 10. Made preheating of the substrate W in a vacuum preheating chamber 10, the preheating is finished, opens the gate G2, inclined parallel to the substrate transfer apparatus 70 of the substrate transfer apparatus 11 and the vacuum processing chamber 20 and the X ₂ direction Let By rotating the roller R of the substrate transfer apparatus 70 of the substrate transfer apparatus 11 of the roller R and the vacuum processing chamber 20, the substrate cart K substrate transfer in the vacuum processing chamber 20 by moving the substrate W together direction of arrow X ₂ It is conveyed on the device 70.

The substrate transfer device 70 is leveled, and the substrate W is processed in this state. At this time, as will be described later, the rod 51 of each lifting device 50 is extended, and the lower surfaces of the plurality of trays T constituting the substrate cart K are supported by the rod 51. The height position of the lower surface of the tray T supported by the rod 51 is the same as the height position of the lower surface of each tray supported by the upper surface of each roller R of the substrate transport apparatus 70. In this state, the substrate W mounted on the substrate cart K is subjected to processing such as thin film deposition by plasma CVD. After predetermined processing is completed, opening the gate G2, to the substrate transfer apparatus 13 of the substrate transfer apparatus 70 and the vacuum preheating chamber 10 is inclined parallel to the X ₃ direction. By rotating the roller R of the substrate transport apparatus 13 in the roller R and the vacuum preheating chamber 10 of the substrate transfer apparatus 70, the vacuum preheating chamber substrate cart K the processed substrate W together moves in the arrow X ₃ direction 10 is transferred onto the substrate transfer device 13 in the apparatus 10.

In the external station 30, the substrate transfer device 18 moves the substrate cart K together with the substrate W before processing to the substrate transfer device 11, and then moves to the lower side as indicated by the dotted line.
The substrate transfer device 13 is leveled and the gate G1 is opened. By rotating the roller R of the substrate transport device 13 and the roller R of the substrate transport device 18, the substrate cart K moves in the direction of the arrow X ₄ together with the processed substrate W and is transported onto the substrate transport device 18.

  Then, the substrate transfer device 18 is moved to the upper side, and the processed substrate W on the substrate cart K is stored in a stocker (not shown) by a transfer device (not shown) such as a vacuum suction transfer machine. Thereafter, the unprocessed substrate W is mounted on the substrate cart K on the substrate transfer device 18, and the same transfer is repeated thereafter.

  In the above, the transfer of the substrate cart K and the substrate W described above is not serial control in which the processed substrate W is unloaded from the external station 30 and then the unprocessed substrate W is loaded into the external station 30. In the vacuum processing chamber 20, while processing the substrate W, the processed substrate W is unloaded, the next substrate W is loaded, and the vacuum preheating chamber 10 is loaded in parallel. Control is performed.

(Substrate transfer device)
Next, a method for forming a thin film on the substrate W while supporting the substrate cart K will be described in detail.
FIG. 2 is a perspective view showing an embodiment of a substrate transfer device and a lifting device mounted in the vacuum processing chamber 20. However, in FIG. 2, the substrate transfer device is shown in only one stage, and the swing mechanism that tilts the substrate transfer device is omitted.
The substrate transfer device 70 is mounted as a pair of transfer mechanisms 70 </ b> A that are mounted in line symmetry with respect to the center plane along the opposing wall surfaces in the vacuum processing chamber 20.
Since each conveyance mechanism 70A has the same structure, only one side will be described. In FIG. 2, four rollers R are illustrated, but this is an example, and an appropriate number can be used. Each roller R has a rotation shaft 77 rotatably supported on a frame (not shown). A motor 62 is disposed outside the frame, and a bevel gear 64 is attached to a rotating shaft 63 of the motor 62. The bevel gear 64 meshes with a bevel gear 72 fixed to the drive shaft 71 at the shaft center. The shaft angle between the bevel gear 64 and the bevel gear 72 is 90 degrees.

  The drive shaft 71 is provided with four bevel gears 73. Each bevel gear 73 is disposed in a region corresponding to the rotation shaft 77 of the roller R, and a bevel gear 74 that meshes with each bevel gear 73 is provided on the rotation shaft 77 of each roller R. The shaft angle of the bevel gear 73 and the bevel gear 74 is 90 degrees.

  Each conveying mechanism 70A is configured as described above. As shown in FIG. 2, when the rotating shaft 63 of the motor 62 rotates in the clockwise direction as shown by the → mark, the bevel gear 64-the bevel gear 72-the drive shaft. The rotating shaft 77 of the roller R is rotated counterclockwise via the 71-bevel gear 73-bevel gear 74, and the substrate cart K placed on the roller R is conveyed in the left direction. When the rotation shaft 63 of the motor 62 is rotated counterclockwise, the rotation shaft 77 of the roller R is rotated clockwise through the same transmission path, and the substrate cart K mounted on the roller R is conveyed to the right. To do.

(lift device)
The lifting device 50 is arranged between the pair of transport mechanisms 70A in a matrix of 3 rows in the transport direction of the substrate transport device 70 and 3 rows in the direction orthogonal to the transport direction, that is, 3 × 3. .
Each lifting device 50 is a cylinder that expands and contracts by hydraulic pressure, a motor, or pneumatic pressure. In this embodiment, the stroke of the cylinder is detected by a stroke sensor (not shown) provided in the cylinder. However, when the cylinder is expanded and contracted by a motor, the stroke can be detected from the rotation signal of the motor. In this case, the stroke sensor is unnecessary. A holding part 52 having a diameter larger than that of the rod 51 for supporting the substrate cart K is provided at the tip of the rod 51 of the lifting device 50. In the case of the present embodiment, each of the three lifting devices 50 arranged in the transport direction of the substrate transport device 70 is connected by a receiving plate 53. That is, three receiving plates 53 are arranged in parallel to the transport direction in a direction orthogonal to the transport direction of the substrate transport device 70, and each receiving plate 53 is disposed on the holding portion 52 of the three lifting devices 50. Each holding portion 52 is fixed to a receiving plate 53. Here, the receiving plate 53 is indicated by a dotted line for convenience of illustration. In the present embodiment, each holding portion 52 is fixed to the receiving plate 53, but may not be fixed to the receiving plate 53.

(Substrate cart)
FIG. 3 is an enlarged plan view of the substrate cart K. FIG.
The substrate cart K includes a plurality of trays T and a connecting plate 31 that connects these trays T. The substrate cart K includes a fastening member 32 and a pin 33 made of ceramic. Although four trays T are shown in FIG. 3, the number of trays T may be more or less than this. The number of the trays T may be one, and in that case, the connecting plate 31 is unnecessary.
Each tray T is formed of carbon, has a long shape, and in a state in which the adjacent tray T and the side surface on the long side are in close contact with each other at a pair of side edges facing each other on the side orthogonal to the long side. These are fixed and integrated by the connecting plate 31.

The connection plate 31 has, for example, a thin plate shape with high strength such as stainless steel, and connects the four trays T with adjacent ones of the trays T in close contact with each other in the longitudinal direction. . The length of the connecting plate 31 is substantially the same as the total dimension of the widths of the four trays T (the length in the direction perpendicular to the longitudinal direction).
The four trays T are formed with through holes for fastening together with the connecting plate 31, and are integrated by fastening the tray T together with the connecting plate 31 by the fastening member 32. Thereby, the substrate cart K has a structure in which the connecting plate 31 protrudes from the lower surface of the tray T (see FIG. 2).

Each tray T is formed with a substrate (work) mounting portion 41 on which a large number of substrates W are mounted.
The pin 33 has a function for positioning the substrate W. Even if the substrate W mounted on the substrate mounting portion 41 rotates as indicated by a dotted line, for example, the rotation is restricted by the pins 33 and positioning is performed.

4 is a cross-sectional view taken along the line IV-IV in FIG. 2 in the film formation state, and FIG. 5 is a cross-sectional view taken along the line VV in FIG. 2 in the film formation state.
As shown in FIGS. 4 and 5, the upper surface of each roller R of the substrate transport apparatus 70 is in contact with the lower surface of the connecting plate 31 of the substrate cart K in the film formation state. That is, the upper surface of each roller R is a hindrance for supporting the lower surfaces of a pair of side edges of each tray T constituting the substrate cart K.
On the other hand, the upper surface of the receiving plate 53 is in contact with the lower surface of each tray T constituting the substrate cart K, and the holding portion 52 provided at the tip of the rod 51 of each lifting device 50 is on the lower surface of the receiving plate 53. The substrate cart K is supported by contact. That is, the upper surface of the holding portion 52 of each lifting device 50 is a hindrance that interferes with the lower surface of each tray T constituting the substrate cart K.

In each lifting device 50, the height position of the lower surface of each tray T supported by the holding portion 52 provided at the tip of the rod 51 is set to the height of the lower surface of each tray T supported by the roller R by the control means. It is controlled to be at the same height position as the position. In this case, the lifting of each lifting device 50 is controlled while detecting the rising position by a stroke sensor provided in each lifting device 50 (not shown). Thereby, the lower surfaces of the four trays T constituting the substrate cart K are supported at a position flush with the eight rollers R and the holding portions 52 of the nine lifting devices 50.
In this way, the support surface of the lower surface of the tray T by the holding portion 52 of the lifting device 50 and the support surface of the lower surface of the tray T by the plurality of transport rollers R are such that the lower surface of the tray T is flush. In the state set at this position, a process of forming a thin film on the substrate W mounted on the tray T is performed under the control of the control means.
Therefore, as compared with the case where the tray T constituting the substrate cart K is supported only by the holding unit 52 of the lifting device 50, the plane of the tray T is supported by the side edges of the lower surface of each tray T supported by the plurality of rollers R. The degree becomes higher. Thereby, when a thin film is formed on the substrate W placed on the substrate cart K, the variation in the thickness of the thin film can be reduced, and the characteristics of the substrate W can be improved.

(Confirmation of effect)
The lower surfaces of a pair of side edges facing each other of the 1.5 m × 2.0 m substrate cart K were supported by a total of twelve rollers R using a transport mechanism 70A having six rollers R. At the same time, three rows in the direction of transport of the substrate cart K and three rows in the direction orthogonal to the direction of transport of the substrate cart K, a total of nine lifting devices 50 are arranged in a matrix, and the five carbons constituting the substrate cart K The lower surface of the central portion of the tray T made of the steel was supported by the holding portion 52 of each lifting device 50 via the receiving plate 53.
In this state (Embodiment 1), the flatness of the substrate cart K was measured. Further, in this state, a silicon insulating film (thin film) was formed on the substrate W placed on the substrate cart K by plasma CVD, and the film thickness variation was measured after the film formation.
As a comparative example, only the holding portions 52 of the nine lifting devices 50 arranged in a matrix form support the five trays T constituting the substrate cart K, and the flatness of the substrate cart K in this state, The variation in the thickness of the thin film after film formation on the substrate W was measured.
The test results are shown in FIG.

As shown in FIG. 6, in the case of the first embodiment, the flatness (maximum height difference) of the substrate cart K is 1.81 mm, and the variation in the thickness of the thin film formed on the substrate W is 8.0. %Met.
In contrast, in the comparative example, the flatness (maximum height difference) of the substrate cart K was 3.00 mm, and the variation in the thickness of the thin film formed on the substrate W was 10.7%.
Thereby, it was confirmed that the variation in the film thickness of the thin film formed on the substrate W in the first embodiment is smaller than that in the case where the film is not supported by the roller R.

The test for the first embodiment uses a comparative plasma CVD apparatus adjusted as a method for lifting the tray T by the elevating device 50 so that the lower surface of the tray T is positioned above the upper surface of the roller R. I went. In this case, the distance between the electrodes of the plasma CVD apparatus is 37 mm.
However, in this Embodiment 1, it carried out in the state which hold | maintained the holding part 52 of the raising / lowering apparatus 50 in the height position where the upper surface of the roller R contacts the lower surface of the tray T. For this reason, in the case of this Embodiment 1, the distance between electrodes was 45 mm.
In the case of the comparative example, it has been confirmed that the distance between the electrodes is almost optimal, but in the case of the first embodiment, it is not confirmed whether the distance between the electrodes is optimal. The test results shown in FIG. 6 are in such a state, but in the case of the first embodiment, the comparative example in which the interelectrode distance is confirmed to be optimal Better results were obtained.

  As described above, in the present embodiment, the flatness of the tray is improved by supporting the lower surface of the work mounting tray by the lifting device and the conveying roller and making the height of the lower surface of the supported tray the same. Thus, there is an effect that the characteristics of the workpiece placed on the tray can be improved.

  In the first embodiment, the number of rollers R that support the substrate cart K is 12 (six on one side) and the number of lifting devices 50 is nine. However, the number of rollers R and lifting devices 50 may be appropriate depending on the size or thickness of the substrate cart K. In particular, the number of lifting devices 50 may be one.

  In the above embodiment, the case where the lower surfaces of the plurality of trays T constituting the substrate cart K are supported has been described. However, the present invention can also be applied to one tray T.

  In the above-described embodiment, the case where the substrate cart K is supported by interposing the receiving plate 53 between the holding portion 52 of the lifting device 50 and the tray T has been described. However, the holding portion 52 of the lifting device 50 may be directly abutted against and supported by the lower surface of the tray T without using the receiving plate 53.

In the above embodiment, the case of the plasma CVD apparatus has been described. In particular, it is very useful to apply to a vacuum processing apparatus for manufacturing a solar cell in which an antireflection film is formed on a solar cell substrate by plasma CVD among plasma CVD devices. Recently, a large number of solar cell substrates are often placed on the roofs and outer walls of general residences and apartment buildings, and along with physical characteristics such as conversion efficiency, appearance characteristics, more specifically There is a demand for uniformity in the color of the solar cell substrate. And since the color of the solar cell substrate changes depending on the film thickness of the antireflection film formed on the surface, the plasma CVD apparatus of the above embodiment is applied to the vacuum processing apparatus for manufacturing the solar cell. It is possible to manufacture a solar cell substrate having a small variation in film thickness, that is, a uniform hue.
In the above embodiment, the case of a plasma CVD apparatus has been described. However, the present invention can also be applied to a sputtering apparatus or another CVD apparatus. Further, the present invention is not limited to the case where a thin film is formed, and can be applied to other vacuum processing such as etching.

  In addition, the tray support structure of the present invention can be variously modified within the scope of the gist of the invention. In short, the tray support structure of the present invention is opposite to the work mounting tray. A plurality of conveying rollers supported on the lower surfaces of the pair of side edges, at least one lifting device having a holding portion for supporting the lower surface of the tray at a position different from the rollers, and a lower surface of the tray by the holding portion of the lifting device. Control means for processing the work mounted on the tray in a state where the support surface and the support surface on the lower surface of the tray by the plurality of conveying rollers are set at a height position where the lower surface of the tray is flush with the surface; What is necessary is just to have.

DESCRIPTION OF SYMBOLS 10 Vacuum preheating chamber 11, 13, 18, 70 Substrate conveyance apparatus 20 Vacuum processing chamber 50 Lifting apparatus 52 Holding part 53 Base plate
100 Plasma CVD apparatus K Substrate cart R Roller T Tray W Substrate (work)

Claims (9)

A plurality of conveying rollers for supporting a work mounting tray on the lower surfaces of a pair of opposing side edges;
At least one lifting device having a holding portion for supporting the lower surface of the tray at a position different from the roller;
A state in which the support surface of the lower surface of the tray by the holding portion of the lifting device and the support surface of the lower surface of the tray by the plurality of transfer rollers are set to a height position where the lower surface of the tray is flush with each other. And a control means for processing the workpiece mounted on the tray.   2. The tray support structure according to claim 1, comprising a plurality of the lifting devices, a support surface of the lower surface of the tray by the holding portion of each lifting device, and a lower surface of the tray by the plurality of transport rollers. A support structure for a tray, wherein the support surface is set at a height position where the lower surface of the tray is flush with the support surface.   3. The tray support structure according to claim 2, wherein a plurality of the lifting devices are arranged in each of a transport direction of the tray by the transport rollers and a direction orthogonal to the transport direction. Support structure.   4. The tray support structure according to claim 1, wherein a plurality of the trays are connected to form one substrate cart. 5.   5. The tray support structure according to claim 1, wherein the tray is made of carbon. 6.   The tray support structure according to any one of claims 1 to 5, further comprising a receiving plate that supports a lower surface of the tray interposed between a front end surface of the elevating unit of the elevating device and the tray. A tray support structure comprising:   The tray support structure according to any one of claims 1 to 6, wherein the receiving plate extends across the plurality of lifting devices.   A plasma CVD apparatus comprising the tray support structure according to claim 1. A vacuum processing apparatus for manufacturing a solar cell, comprising the tray support structure according to claim 1.

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