JPH0629131U - Rotary substrate processing equipment - Google Patents

Abstract

(57) [Abstract] [Purpose] To easily respond to changes in the shape and size of the substrate without adjusting the optical axes of the projector and the receiver individually and without lowering the accuracy. [Structure] Supporting pins 70 having the same height and provided with positioning pins 6 are attached to the turntables 50 and 5a so that their mounting positions correspond to the size of the substrate 8 to form a substrate support, and The bottom surface 130 of the fitting tubular portions 13b and 13a
Prepare a plurality of wafers 80 having different distances A, B from the b, 130a to the substrate supporting position depending on the size and shape of the wafers 8, 80, and replace them with predetermined substrate supports according to the size of the wafer to be processed. Irrespective of changes in the shape and size of the wafer, the projector 11 is provided inside the outer edge of the wafer supported by the support pins 70, which is closest to the rotation center P.
The support height changing mechanism is configured such that the optical axes L connecting the optical receiver 12 and the optical receiver 12 intersect.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention supports a substrate such as a semiconductor wafer, a glass substrate for a liquid crystal display device, a glass substrate for a photomask, a substrate for an optical disk, etc. on a substrate support member in an appropriate posture to rotate the photoresist on the substrate. A rotary type that supplies the coating solution to form a coating film, drops the developing solution on the substrate for development, and supplies a cleaning solution such as pure water to clean the substrate. The present invention relates to a substrate processing apparatus, and more particularly, to a rotary substrate processing apparatus capable of detecting the substrate support posture of a substrate support.

[0002]

[Prior art]

 In spin coaters, spin developers, spin scrubbers, and other rotary substrate processing equipment, when a substrate is not supported by the substrate support in the correct posture and is tilted or eccentric, the substrate falls off from the substrate support due to rotation. There is a risk of damage.

Therefore, it has been necessary to determine whether or not the mounting posture is proper immediately after the substrate is supported by the substrate support prior to the rotation for processing the substrate.

Therefore, conventionally, for example, as disclosed in Japanese Patent Application Laid-Open No. 2-86144, a light source for projecting a light beam is provided on one side above and below a substrate and a light beam from the light source is provided on the other side. A light receiver that receives the light and outputs a light reception signal is provided, and it is arranged so that the optical axis of the light source and the light receiver is always blocked by the substrate when the substrate is supported by the substrate support in a normal posture. It is known that the substrate is rotated once at a low speed, and whether the mounting posture of the substrate on the substrate support is proper or not is determined by whether or not the light receiving signal is output during the one rotation. There is.

That is, if the posture is normal, the light beam is blocked by the substrate for one rotation, so that no light reception signal is output. Conversely, if the posture is not normal, The light beam from the light source is received by the light receiver at at least one position of one rotation of the board, and the light reception signal is output from the light receiver. Depending on whether or not the light reception signal is output, the mounting posture of the board is appropriate. It is possible to determine whether or not.

In order to detect the quality of the supporting posture of the substrate more reliably and accurately with such an apparatus, the optical axes of the light source and the photodetector should be adjusted so that the optical axes of the light source and the light receiver are supported by the substrate supporting member in a normal posture. It is necessary to accurately arrange them so that they intersect with the substrate at a position near the innermost portion of the outer edge that is closest to the rotation center.

However, the substrate processed by the rotary substrate processing apparatus is not always uniform in shape or size. In this way, when the size of the board that is the target of posture change changes, the size of the orientation flat changes, or the shape changes from a circular board to a rectangular board, Since it is necessary to adjust the positions of the optical axes that intersect with each other, in the above-mentioned conventional example, the mounting positions of the light source and the light receiver are adjusted in accordance with changes in the shape and size of the board, and the mounting posture is adjusted. Also make adjustments so that when the substrate is supported in a normal posture, the optical axes that connect the light source and the light receiver intersect inside the outer edge of the substrate that is closest to the center of rotation. Was there.

[0008]

[Problems to be solved by the device]

 However, as described above, when adjusting the optical axis, not only the mounting positions of the light source and the light receiver must be changed, but also the mounting postures thereof must be adjusted. It had to be performed accurately in a narrow space inside the casing, and there was a drawback in that adjustments to cope with changes in the shape and size of the substrate were extremely troublesome.

The present invention has been made in view of such circumstances, and once the initial setting of the optical axis is performed, the light source and the light receiver are moved one by one with respect to changes in the shape and size of the substrate. It is therefore an object of the present invention to provide a rotary substrate processing apparatus that can easily cope with the need for individually adjusting its optical axis and without lowering the accuracy of substrate posture detection.

[0010]

[Means for Solving the Problems]

 In order to achieve the above-mentioned object, the rotary substrate processing apparatus of the present invention includes a substrate support that supports a substrate, a drive source that rotates the substrate support by mounting it on a shaft, and a substrate support. A positioning member that regulates the position of the supported substrate, a projector that is provided on one side of the substrate supported by the substrate support and sandwiches the plate-shaped surface, and projects light obliquely onto the substrate, and the substrate plate In a rotary substrate processing apparatus that consists of a light-emitter that is provided on the opposite side of the light-emitter across the surface and receives light from the light-emitter, supports the substrate support in response to changes in the size or shape of the substrate. Equipped with a support height changing mechanism that changes the support height of the base plate so that the optical axes connecting the transmitter and the receiver intersect inside the outer edge of the printed circuit board closest to the center of rotation. Configure.

The following various configurations can be adopted as the support height changing mechanism. (1) When a support pin and a positioning member are attached to the turntable to form a substrate support, support pins with different heights and a substrate support with a positioning member according to the size and shape of the substrate are attached to the turntable. Prepare multiple bodies in advance and replace them according to the size and shape of the substrate to be processed.

(2) A positioning member according to the size and shape of the board is attached to the turntable, and a plurality of board supports having different fitting depths for the drive shaft of the drive source are prepared in advance, and the size and shape of the board are prepared. Replace according to.

(3) When the support pin and the positioning member are attached to the turntable to form the substrate support, the turntable is provided with the positioning member at a position corresponding to the change in the shape and size of the substrate. Support pin mounting holes are formed in advance to support pins that correspond to the shape and size of the board (for example, if the board size changes, the larger the board, the higher the support pin is used). Replace. At this time, for example, if there are three types of board sizes, the support pins with the heights corresponding to the three types of boards are previously attached to the turntable to support the smallest size board. When changing to the state of supporting a larger base plate, the corresponding action is to remove the unnecessary support pin on the smaller side, and vice versa. It is also possible to attach a support pin corresponding to the first substrate to support it.

(4) In the case of (3) above, a spacer may be provided at a fitting portion between the drive shaft of the drive source and the rotary table so that the mounting height of the rotary table can be changed. According to this, there is an advantage that the support pins having the same height can be used.

(5) An elongated hole is formed in the rotating table so as to extend in a direction approaching and retracting from the center of rotation, and the mounting shaft portion of the support pin provided with the positioning member is inserted through the elongated hole. The height is made different in multiple stages, and it is configured so that the support height according to the size of the substrate can be obtained as the mounting and fixing position is changed.

[0016]

[Action]

 According to the configuration of the rotary substrate processing apparatus of the present invention, the entire substrate support is replaced, or the members constituting the substrate support are replaced according to the shape and size of the substrate to be processed, or By changing the support height of the substrate supported by the substrate support by changing the mounting and fixing position of the members that make up the substrate support, the projector can be projected diagonally from the projector. The position where the light that crosses the substrate changes. Then, by this, the optical axis connecting the light emitter and the light receiver is adjusted so as to intersect with the substrate at a position inside the outer edge of the substrate supported by the substrate support closest to the position closest to the rotation center. .

[0017]

【Example】

 Next, an embodiment of the present invention will be described in detail with reference to the drawings.

<First Embodiment> FIG. 1 is an overall schematic side view showing a first embodiment of a rotary substrate processing apparatus according to the present invention, and FIG. 2 is an overall schematic plan view. In the figure, 1 is an electric motor 1 as a drive source, and 2 is a drive shaft of the electric motor 1. A screw 4 is screwed into the side of the drive shaft 2. Reference numeral 5 denotes a turntable which is a stage necessary to support and rotate the substrate. The turntable 5 has a lower surface on which a bottomed hollow tubular fitting tube portion 13 is integrally formed. A notch 3 is formed at the lower end of the fitting tubular portion 13. By aligning the notch 3 with the position of the screw 4 and fitting the fitting cylindrical portion 13 into the drive shaft 2 until the bottom surface 130 thereof contacts the upper end of the drive shaft 2, the rotary table 5 is attached to and detached from the drive shaft 2. Can be mounted as possible. Further, on the rotary table 5, there are provided support pins 7 ... Protrudingly provided with positioning pins 6 as positioning members on the upper end thereof at predetermined intervals along the circumference around the rotation center P of the drive shaft 2. A book is provided. Among the positioning pins 6, those corresponding to the position of the orientation flat of the substrate, which will be described later, are provided slightly inside the circumference around the rotation center P.

Then, a semiconductor wafer (hereinafter referred to as a 5-inch wafer) 8 having a diameter of 5 inches on which an orientation flat is formed is supported on a support pin 7 ... And a vertical position is regulated by a positioning pin 6. While rotating around the axis P, a cleaning liquid and a surface treatment liquid are supplied from the nozzle 9 onto the 5-inch wafer 8 to perform various surface treatments.

The rotating table 5 is driven by an elevating means (not shown) so as to be able to move up and down between an ascending position which surrounds the outer periphery of the rotating table 5 to prevent the processing liquid from scattering and a descending position which is not enclosed. A cup 10 is provided, and on the outer side of the cup 10, one side of the plate-shaped surface of the 5-inch wafer 8 supported by the support pins 7 is sandwiched, that is, above the plate-shaped surface of the 5-inch wafer 8. A projector 11 for projecting light obliquely downward is provided so as to intersect the 5-inch wafer 8. Then, on the side opposite to the projector 11 sandwiching the plate-shaped surface of the 5-inch wafer 8, that is, on the lower side of the plate-shaped surface of the 5-inch wafer 8, a light-receiving signal that receives light from the projector 11 and outputs a light-receiving signal is received. A device 12 is provided, and the optical axis L connecting the light projector 11 and the light receiver 12 is configured to intersect inside the outer edge of the 5-inch wafer 8 closest to the rotation center P. The optical axis referred to in the present invention refers to the path of the light flux of the substrate detecting light beam projected by the light projector 11 and received by the light receiver 12.

In this embodiment, the rotary table 5 to which the positioning pins 6 ... And the support pins 7 ... Are attached is used by being replaced according to the size of the wafer to be processed. FIGS. 1 and 3 (a) show a state in which a support pin 7 having a positioning pin 6 protruding from the upper end is attached to a turntable 5 for a 5-inch wafer 8 to support the 5-inch wafer 8. In FIG. 3B, a supporting pin 7z having a positioning pin 6 protruding from the upper end is attached to a rotary table 5z for a semiconductor wafer (hereinafter referred to as "6 inch wafer") 80 having a diameter of 6 inches, and 6 The state of supporting the inch wafer 80 is shown.

The support pin 7z for the 6-inch wafer 80 attached to the turntable 5z has a height from the surface of the turntable to a position (upper end of the support pin 7z) for supporting the 6-inch wafer 80, which is the 5-inch wafer 8. It is configured to be higher than the support pin 7 for the. Therefore, the distance Y from the bottom surface 130z of the fitting cylinder portion 13z of the rotary table 5z for the 6-inch wafer 80 to the position supporting the wafer is the bottom surface of the fitting cylinder portion 13 of the rotary table 5 for the 5-inch wafer 8. It is configured to be longer than the distance X from 130 to the position supporting the wafer.

Although the outer diameter of the turntable 5z for the 6-inch wafer 80 is the same as that of the turntable 5 for the 5-inch wafer 8, it is necessary to attach support pins corresponding to the wafer size. The position of the hole for attaching the support pin 7z is located on the outer radial side of the position of the hole formed in the rotary table 5. As a result, the support pin 7z is attached so as to be located on the outer radial direction side of the attachment position of the support pin 7 attached to the rotary table 5 for the 5-inch wafer 8. As described above, the rotary table 5z for the 6-inch wafer 80 and the rotary table 5 for the 5-inch wafer 8 have the same configuration except the positions of the holes to which the support pins are attached.

A state in which a 5-inch wafer and a 6-inch wafer are processed under such a configuration will be described with reference to FIG. In the figure, the solid line portion shows the state where the 5-inch wafer 8 is processed. When the 5-inch wafer 8 is supported by the support pins 7 attached to the rotary table 5 and is in the position shown in FIG. 2, the 5-inch wafer 8 is located inside the center of the orientation flat closest to the rotation center P of the outer edge of the wafer. It intersects with the optical axis L at R. When the 6-inch wafer 80 is continuously processed, the rotary table 5 is removed from the drive shaft 2, and the rotary table 5z for the 6-inch wafer 80 to which the support pins 7z are attached is fitted on the drive shaft 2. Therefore, when the 6-inch wafer 80 is placed on the support pin 7z, it is supported at a position slightly higher than that of the 5-inch wafer 8. When the 6-inch wafer 80 is located at the position indicated by the chain double-dashed line in FIG. 2, the 6-inch wafer 80 intersects the optical axis L at the inner position S near the center of the orientation flat closest to the rotation center P among the outer edges of the wafer. It is like this.

In the first embodiment described above, the case of processing a 5-inch wafer and a 6-inch wafer has been described. However, in addition to the support pin 7 and the support pin 7z, the diameter of the wafer used and the size of the orientation flat are used. Depending on the shape and size of the notch, etc., prepare a turntable that has support pins with different heights from the turntable surface to the position to support the wafer, and change it according to the wafer to be used. Therefore, this embodiment can be applied to various wafers.

With these configurations, even if the size of the substrate to be processed changes, the substrate is supported by the support pins 7, ..., 7z ... A support height changing mechanism for changing the support height of the substrate is configured so that the optical axis L connecting the light projector 11 and the light receiver 12 intersects at the inner side of the outer edge of the outermost part of the outer edge of the substrate which is closest to the rotation center P. Has been done.

According to this configuration, when processing a 5-inch wafer 8, for example, the rotary table 5 corresponding thereto is simply attached to the drive shaft 2, and the projector 11 and the optical receiver 12 are individually mounted. Even if the adjustment is not performed, the optical axis L connecting the light projector 11 and the light receiver 12 is located at the position closest to the rotation center P of the outer edge of the 5-inch wafer 8 supported by the support pins 7 attached to the turntable 5. Since it intersects with the 5-inch wafer 8 at a near inner position, if the supporting posture of the 5-inch wafer 8 is deviated, the projector 11 is provided at least at one position while the 5-inch wafer 8 is rotated once. The light emitted by is detected by the light receiver 12. Therefore, in the initial stage of loading and supporting the 5-inch wafer 8, the 5-inch wafer 8 is rotated once at a low speed in a state where the cup 10 is lowered to a position that does not cover the outer peripheral side of the turntable 5, and one rotation is performed. Whether or not the supporting posture of the 5-inch wafer 8 is good can be reliably detected based on whether or not the light receiving signal is output from the light receiver 12 therein. Further, if the light reception signal is output, it is determined that the 5-inch wafer 8 is displaced from the predetermined posture, the supporting posture is corrected, and the 5-inch wafer 8 may be dropped and damaged due to the rotation accompanying the processing. It can be prevented.

According to the first embodiment described above, there is an advantage that it is only necessary to replace the substrate support with respect to the change in the size or shape of the substrate to be processed, and the labor can be saved. Further, if holes for mounting the support pins 7, 7z ... Are formed in the rotary table 5 at positions corresponding to all sizes of substrates to be used, the rotary table 5 having exactly the same shape is common. Can be used.

The innermost position of the outer edge of the substrate closest to the rotation center P is the innermost position of the outer edge Q of the circular substrate [see (a) of FIG. 9], Oriente In the case of a circular substrate with an orientation flat, the inside of the orientation flat near the center Q [see (b) of FIG. 9], and in the case of a circular substrate with an orientation notch, the tip of the orientation notch Q It refers to the inner side near [see (c) of FIG. 9], and in the case of a rectangular substrate, the inner side near the center Q of the long side [see (d) of FIG. 9]. It should be noted that the one including the rotary table 5 and the support pin 7 and the one including the rotary table 5z and the support pin 7z in the first embodiment described above are included in the "substrate support" described in the claims of the utility model. Corresponds to the body. The positioning pin 6 in the first embodiment corresponds to the "positioning member" described in the scope of claims for utility model registration.

<Second Embodiment> FIG. 4 shows a second embodiment of the rotary substrate processing apparatus according to the present invention. The second embodiment is different from the first embodiment in the structure of the rotary table and the support pins for changing the support height of the substrate.

In the present embodiment, when processing the 5-inch wafer 8, the rotary table 50 and the support pins 70 shown in FIG. 4A are used, and when processing the 6-inch wafer 80, FIG. 4B is used. The rotary table 5a and the support pin 70 shown in are used respectively. Here, the positioning pins 60 ... And the support pins 70 ... are exactly the same. The rotary table 50 for the 5-inch wafer 8 and the rotary table 5a for the 6-inch wafer 80 have the same diameter, but the mounting positions of the positioning pins 60 ... And the support pins 70 ... It depends on the substrate diameter. In addition, the distance B from the bottom surface 130a of the fitting cylinder portion 13a of the rotary table 5a for the 6-inch wafer 80 to the substrate supporting position (upper end of the support pins 70 ...) is equal to that of the rotary table 50 for the 5-inch wafer 8. The fitting cylinders 13a and 13b have different configurations so that the distance is longer than the distance A from the bottom surface 130b of the coupling cylinder 13b to the substrate supporting position.

Also in this second embodiment, the wafer is replaced with a predetermined turntable corresponding to the size of the wafer to be used, and the portion of the outer edge of the wafer supported by the support pins 70 ... A support height changing mechanism that changes the support height of the wafer is configured so that the optical axes L connecting the light projector 11 and the light receiver 12 cross each other on the inside.

According to the second embodiment described above, it suffices to replace the rotary table with respect to the change in the size or shape of the wafer to be processed, and the labor is small, and the same positioning pins 60 ,. The pins 70 ... Can be commonly used.

As a modified example of the second embodiment, a flange (not shown) is formed on the drive shaft 2 for abutting and supporting the lower end surfaces of the fitting cylinders 13a and 13b, and the flange is fitted with the flange. If the wafer support height is changed by interposing a spacer (not shown) between the lower end surfaces of the coupling cylinder portions 13a and 13b, the rotary table can be shared. . It should be noted that the one including the rotary table 50 and the support pin 70 and the one including the rotary table 5a and the support pin 70 in the above-described second embodiment are respectively described in the "patent support" in the claims of the utility model. Corresponds to the body. The positioning pin 6 in the second embodiment corresponds to the "positioning member" described in the scope of utility model registration.

<Third Embodiment> FIG. 5 is an overall schematic plan view showing a third embodiment of the rotary substrate processing apparatus according to the present invention. The rotary table 5c constituting the substrate support is provided with a predetermined circumferential direction. Mounting holes 14a ..., 14b ..., 14c ... for mounting the support pins 7a, 7b, 7c by screwing are formed so as to be spaced apart and along the circles of three kinds of diameters.

As shown in the overall schematic side view of FIG. 6, in each of the mounting holes 14a ..., 14b ..., 14c. Pins 7a, 7b, 7c are attached, and the light emitter 11 and the light receiver are provided on the inner side of the outer edge of the 5-inch wafer 8 supported by the support pins 7a, ..., 7b. A support height changing mechanism for changing the support height of the 5-inch wafer 8 is configured so that the optical axis L connecting with 12 intersects. In the third embodiment, screws are not formed in the mounting holes 14a, 14b, 14c, and the support pins 7a, 7b, 7c are mounted on the rotary table 5 by nuts. Is also good.

According to the third embodiment described above, the rotary table 5c can be commonly used regardless of changes in the size or shape of the wafer to be processed, which is economical. In the third embodiment, the rotary table 5c and the support pin 7a, the rotary table 5c and the support pin 7b, and the rotary table 5c and the support pin 7c are respectively used. It corresponds to the “substrate support” described in the claims for new model registration. Further, the positioning pin 6 in the above-mentioned third embodiment corresponds to the "positioning member" described in the scope of claims for utility model registration.

<Fourth Embodiment> FIG. 7 is a perspective view of a main portion showing a fourth embodiment of the rotary substrate processing apparatus according to the present invention, and FIG. 8 is a cross-sectional view of the main portion. An elongated hole 16 through which a screw shaft 15 projecting downward is inserted from a support pin 7d having a positioning pin 6 projecting at the upper end while being circumferentially separated by a predetermined distance and extending in the radial direction of the rotary table 5d. Is formed, and a support portion 17 that supports the support pin 7d at a high position is formed on the radially outer side of the rotary table 5d of the elongated hole 16, and a nut 18 is attached to the screw shaft 15. ing.

With this configuration, the nut 18 is loosened to move the supporting pin 7d along the elongated hole 16 in response to the change in the size and shape of the wafer, and the nut 18 is attached to either one of both ends of the elongated hole 16. The wafer is clamped and fixed by means of the wafer, and the wafer is supported so that the optical axes L connecting the light emitter 11 and the light receiver 12 may intersect inside the outer edge of the outer edge of the wafer supported by the support pins 7d. A support height changing mechanism is configured to change the support height of the.

According to the fourth embodiment, the rotary table 5d and the support pins 7d can be shared and the support pins 7d can be used regardless of the size and shape of the wafer to be processed. It has the advantage that it can be easily adjusted without having to remove it.

In each of the above-described embodiments, the supporting pin 7d provided with the positioning pin 6 is shown. However, in the present invention, the positioning pin formed separately from the supporting pin is used, and the lower surface of the wafer is supported by the supporting pin. May be configured to support.

It should be noted that the one composed of the turntable 5d and the support pin 7d in the fourth embodiment corresponds to the "substrate support" described in the scope of claims for utility model registration. The positioning pin 6 in the fourth embodiment corresponds to the "positioning member" described in the scope of utility model registration.

Further, in the above-mentioned first to fourth embodiments, the case where the substrate to be processed is a semiconductor wafer has been described, but the present invention is not limited to this, and the present invention is not limited to this. Needless to say, it can be applied to various substrates such as glass substrates for liquid crystal display devices, glass substrates for photomasks, and substrates for optical discs.

[0044]

[Effect of device]

 According to the rotary substrate processing apparatus of the present invention, the shape and size of the substrate can be controlled by the entire substrate support or by the support height changing mechanism such as replacement of the members constituting the substrate support or change of the mounting and fixing position. Since it can respond to changes in the optical axis, compared to the conventional case where the optical axis is adjusted by adjusting the mounting position and mounting posture of each of the projector and the receiver in a narrow space inside the device casing, It is now possible to easily perform the adjustment work to cope with changes in the shape and size of the car without degrading the accuracy.

[Brief description of drawings]

FIG. 1 is an overall schematic side view showing a first embodiment of a rotary substrate processing apparatus according to the present invention.

FIG. 2 is an overall schematic plan view of the first embodiment.

FIG. 3 is a partially cutaway side view of a substrate support.

FIG. 4 is a partially cutaway side view of a second embodiment of the rotary substrate processing apparatus according to the present invention.

FIG. 5 is an overall schematic plan view showing a third embodiment of the rotary substrate processing apparatus according to the present invention.

FIG. 6 is a side view of a main part of the third embodiment.

FIG. 7 is a perspective view of essential parts showing a fourth embodiment of the rotary substrate processing apparatus according to the present invention.

FIG. 8 is a sectional view of an essential part of the fourth embodiment.

FIG. 9 is a plan view illustrating the shapes of various substrates.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Electric motor as a drive source 2 ... Drive shafts 5, 5z, 50, 5a, 5c, 5d ... Rotating table 6 ... Positioning pins 7, 7z, 70, 7a, 7c, 7d ... Support pins 8 ... Wafers with a diameter of 5 inches 11 ... Projector 12 ... Photoreceiver 80 ... 6 inch diameter wafer L ... Optical axis

Claims (1)

[Scope of utility model registration request] 1. A substrate support for supporting a substrate, a drive source for mounting the substrate support on an axis for rotational driving, and a positioning member for regulating the position of the substrate supported by the substrate support, A projector provided on one side of the plate-shaped surface of the substrate supported by the substrate support and projecting light in an oblique direction to the substrate, and an opposite side of the projector that sandwiches the plate-shaped surface of the substrate. A light receiving device which is provided in the light receiving device and receives light from the light projecting device, and an outer edge of the substrate supported by the substrate support body in response to a change in size or shape of the substrate. A support height changing mechanism for changing the support height of the substrate so that the optical axes connecting the light projector and the light receiver intersect each other on the inner side of a portion closest to the rotation center And a rotary substrate processing apparatus.