JP2009049145A - Coating processor, and coating processing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coating processor capable of forming a coating film excelling in film thickness uniformity on the whole surface of a substrate with a simple structure and a small quantity of coating liquid. <P>SOLUTION: The coating processor is a device which forms a coating film by expanding a coating liquid on a substrate over the whole surface of the substrate by rotating the substrate, and includes: a first coating liquid discharge means of discharging, to a rotational center position of the substrate, a low-viscosity coating liquid being a solution having the same chemical constituent as that of a solution forming the coating film, and high in wettability to a surface of the substrate; a second coating liquid discharge means of discharging, to the rotational center position, a high-viscosity coating liquid being a solution for forming the coating film, and having viscosity higher than that of the low-viscosity coating liquid after the low-viscosity coating liquid is discharged by the first coating liquid discharge means; and a substrate rotating means of fixing the substrate at the rotating center position to rotate the substrate at a predetermined rotating speed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a coating processing apparatus and a coating processing method, and in particular, a resin layer is coated on the surface of a semiconductor wafer with a uniform film thickness (for example, a resin layer for surface protection is formed on a semiconductor circuit pattern forming surface of the wafer). The present invention relates to a technique suitably applied to the above.

  Conventionally, various methods are used as a method for forming a coating film in a semiconductor device manufacturing process, and one of them is a spin coating method. In this spin coating method, a coating solution is dropped at the rotation center position of a semiconductor wafer that is stopped or rotated, and then the semiconductor wafer is rotated at a predetermined rotational speed, and the coating solution is spread over the entire wafer by centrifugal force to form a thin coating film. It is a method of forming. Usually, in the formation of a coating film by spin coating, by controlling the viscosity of the coating solution to be dropped, the amount of dropping, and the number of rotations of the wafer, it is managed so as not to cause coating defects such as missing coating and uneven film thickness. .

  Also, as a method for improving the wettability with respect to the substrate and reducing the amount of the coating solution used, a method of performing a prewetting process in which a solvent having high wettability such as thinner is applied to the surface of the semiconductor wafer prior to the application of the coating solution. It has been known. This pre-wetting process is to spread the solvent over the entire semiconductor wafer by discharging a solvent such as thinner to the rotation center position of the semiconductor wafer before applying the coating liquid, and to improve the wettability of the coating liquid to the substrate. Thus, the coating liquid can be easily spread over the entire semiconductor wafer.

  For example, Patent Document 1 discloses a resist coating method in which variations in the thickness of a resist film are reduced without causing concentric coating spots or the like even when the resist discharged on the wafer surface is spin-coated in a resist solvent atmosphere. Is disclosed. In the resist coating method, the wafer is rotated in a resist solvent atmosphere and the resist is spread on the wafer surface by centrifugal force. The resist solvent atmosphere is gradually replaced with a resist dry atmosphere as the rotation time elapses. The resist can be gradually dried.

  Also, for example, in Patent Document 2, the organic material film is formed on the surface of the substrate by the spin coating method of the organic material, and an organic material film having a uniform thickness is formed on the surface of any size substrate. A spin coating method aimed at improving productivity is disclosed. The spin coating method is a spin coating method of an organic material in which an organic material liquefied with a solvent is dropped onto a rotating substrate to form an organic film having a required thickness on the substrate. After the liquefied organic material is dropped, cooled air or air containing a mist-like solvent is blown onto the rotating substrate surface, so that the flow region of the liquefied organic material can be expanded.

Further, for example, Patent Document 3 discloses a coating processing method capable of forming a coating film having excellent film thickness uniformity over the entire surface of the substrate. The coating treatment method uses the above-described pre-wetting treatment for the spin coating method. After performing the pre-wetting treatment by discharging thinner to the outer peripheral portion of the wafer, the coating solution is discharged to substantially the center of the surface of the rotating wafer. In addition, by spreading this coating solution over the entire surface of the wafer, it is possible to form a coating film with good film thickness uniformity.
JP-A-4-361524 JP-A-5-166710 JP 2003-136010 A

  In the conventional coating method using spin coating, it is difficult to spread a high-viscosity solvent to the outer peripheral portion of the semiconductor wafer. This tendency has become more prominent with the recent increase in the diameter of semiconductor wafers. Although it is conceivable to increase the discharge amount of the solvent in order to improve the coating property, simply increasing the discharge amount of the solvent simply returns the running cost and is not a good solution. On the other hand, in order to reduce the solvent discharge amount, a method using a prewetting process as in Patent Document 3 is conceivable. However, for example, a high-viscosity solvent of 50 cp (centi-poise) or more (a photoresist, a buffer coating material such as polyimide and polybenzoxazole, an interlayer insulating film, etc.) is applied to a semiconductor wafer by a spin coating method to a coating thickness of 2 μm or more. In the case of formation, it has been found that if the amount of solvent discharged is further reduced by using prewetting treatment, a stable coating film cannot be obtained only by modifying the substrate surface to improve wettability.

  This will be described with reference to FIG. FIG. 5A is a top view of the semiconductor wafer as viewed from a direction perpendicular to the wafer surface, and FIGS. 5B and 5C are side views of a cross section of the semiconductor wafer as viewed from a direction parallel to the wafer surface. In the application by spin coating, when the coating liquid 12 discharged to the center of the semiconductor wafer 3 spreads around the substrate by the centrifugal force by rotating the substrate, it is applied in a number of branches like an amoeba tentacle. It extends from the lump of liquid 12 to the periphery. Eventually, the adjacent coating liquids that have branched off will merge, but when they merge, the surface of each of the branched coating liquids has been dried and the viscosity has increased, so the familiarity between the coating liquids has decreased. However, there is a problem that air is entrained when the coating liquids are merged, resulting in bubbles in the film. This bubble becomes a pinhole that is taken into the film or does not adhere to the coating solution at all, and therefore, the portion does not have the required original film thickness, and the quality is deteriorated.

  On the other hand, the resist coating method of Patent Document 1 and the spin coating method of Patent Document 2 are used for spin coating in a resist solution atmosphere or for spraying cooling air or air containing a mist solvent during spin coating. Although it is possible to prevent the coating liquid surface from being dried and to maintain the fluidity of the coating liquid, a configuration such as a steam generator or an air generator is newly required, and the cost of the coating apparatus itself is increased.

  Therefore, in view of the above-described circumstances, the present invention provides a coating processing apparatus and a coating processing method that can form a coating film with excellent film thickness uniformity over the entire surface of a substrate with a simple configuration and a small amount of coating liquid. The purpose is to provide.

  To achieve this object, the present invention provides a coating processing apparatus for forming a coating film by spreading a coating solution on a substrate over the entire surface of the substrate by rotating the substrate, and a solution for forming the coating film, A first coating liquid discharge means for discharging a low viscosity coating liquid having a high chemical composition wettability to the substrate surface to the rotation center position of the substrate, and a low viscosity coating liquid discharged by the first coating liquid discharge means After that, a second coating solution discharge means for discharging a high-viscosity coating solution having a viscosity higher than that of the low-viscosity coating solution to the rotation center position and a substrate fixed at the rotation center position. And a substrate rotating unit that rotates the substrate at a predetermined rotation speed.

  Further, according to the present invention, in the above-described coating processing apparatus, the second coating liquid discharge unit discharges the high viscosity coating liquid before the low viscosity coating liquid discharged by the first coating liquid discharge unit spreads over the entire surface of the substrate. It may be characterized by.

  In the coating processing apparatus according to the present invention, the substrate rotating unit may be faster than discharging the high-viscosity coating liquid after the high-viscosity coating liquid discharged by the second coating liquid discharging unit spreads over the entire surface of the substrate. The rotational speed may be changed so as to be rotated.

  In another aspect, the present invention provides a coating processing method for forming a coating film by spreading a coating solution on a substrate over the entire surface of the substrate by rotating the substrate, and the same chemistry as the solution for forming the coating film. A first coating liquid discharge step for discharging a low-viscosity coating liquid having high wettability to the substrate surface to the rotation center position of the substrate, and a substrate on which the low-viscosity coating liquid is discharged by the first coating liquid discharge step A solution for forming a coating film after the low-viscosity coating liquid is discharged by the first substrate rotation step and the first coating liquid discharge step, which are higher in viscosity than the low-viscosity coating liquid. A second coating liquid discharging step for discharging the high viscosity coating liquid to the rotation center position, and a second substrate rotating step for rotating the substrate on which the high viscosity coating liquid is discharged by the second coating liquid discharging step at a predetermined rotation speed. A coating treatment method characterized in that it comprises a.

  According to the present invention, in the coating treatment method described above, the second coating liquid discharge step discharges the high viscosity coating liquid before the low viscosity coating liquid discharged by the first coating liquid discharge step spreads over the entire surface of the substrate. It may be characterized by.

  In the coating processing method according to the present invention, the second substrate rotation step may be performed when the high-viscosity coating liquid is discharged after the high-viscosity coating liquid discharged by the second coating liquid discharge step spreads over the entire surface of the substrate. Also, the rotation speed may be changed so as to achieve high speed rotation.

  ADVANTAGE OF THE INVENTION According to this invention, the coating processing apparatus and the coating processing method which can form the coating film excellent in film thickness uniformity on the whole substrate surface with a simple structure and a small amount of coating liquid are provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  First, the structure of the coating processing apparatus which is embodiment of this invention is demonstrated. FIG. 1 is a diagram showing a schematic configuration of a coating treatment apparatus of the present embodiment. The coating processing apparatus of this embodiment includes a coating liquid discharge nozzle A1, a coating liquid discharge nozzle B2, a spin chuck 4, a scan arm 5, a coater cup 6, a drive motor 8, a coating liquid discharge pump A9, a coating liquid discharge pump B10, and a low It has a container for the viscosity coating solution 11 and the high viscosity coating solution 12. The coating liquid discharge nozzle A1 corresponds to the first coating liquid discharge means of claim 1, the coating liquid discharge nozzle B2 corresponds to the second coating liquid discharge means of claim 1, and the spin chuck 4 and the drive motor 8 are provided. This corresponds to the substrate rotating means of claim 1.

  The coater cup 6 is for preventing the coating liquid from splashing when the semiconductor wafer 3 is rotated and coating it, and discharging the unnecessary coating liquid. The coater cup 6 accommodates the semiconductor wafer 3 held by the spin chuck 4. It has a hollow shape with enough space. The bottom surface is circular and has a diameter larger than the length of the maximum portion of the semiconductor wafer 3 (diameter if the wafer shape is a circle, diagonal if it is a rectangle), and a hole through which the spin chuck 4 passes is provided in the center portion. Yes. In addition, a drain 7 is provided at a predetermined position on the outer periphery of the bottom portion, so that unnecessary coating liquid is discharged from the drain 7. Further, the side surface portion is provided higher than the position where the semiconductor wafer 3 is held, and in the vicinity of the holding position of the wafer, the side surface portion is inclined so as to approach the inside of the space in order to further prevent scattering to the outside ( Up to the position where the slope starts, it is vertical from the bottom).

  The coater cup 6 can move up and down, and is fixed in a state where the uppermost portion of the side surface is lower than the wafer holding position of the spin chuck 4 before spin coating. When the semiconductor wafer 3 is held by the spin chuck 4 and spin coated, Move to a higher position than the holding position and fix. In the present embodiment, the coater cup 6 is configured to be movable up and down, but the coater cup 6 may be fixed and the spin chuck 4 and the drive motor 8 may be configured to be movable up and down. The shape of the coater cup 6 may be a square, a rectangle, or other polygons instead of a circle.

  The spin chuck 4 includes a pedestal portion in which a contact surface between the rod-shaped rotation shaft portion and the semiconductor wafer 3 is larger than the rotation shaft portion, and the semiconductor wafer 3 is fixed and held by vacuum suction at the pedestal portion. The semiconductor wafer 3 is rotated by a drive motor 8 and the held semiconductor wafer 3 is thereby rotated. The drive motor 8 can change the rotation speed by a control device (not shown), and changes the rotation speed in conjunction with the change of the discharge position of the coating liquid discharge nozzle A1 and the coating liquid discharge nozzle B2, which will be described later.

  The coating liquid discharge nozzle A1 is a nozzle that discharges the low-viscosity coating liquid 11 having high wettability to the wafer surface onto the semiconductor wafer 3, and includes a nozzle section that discharges the coating liquid onto the wafer surface and a tube connection section. Is connected to the tube from the coating liquid discharge pump A9. The coating liquid discharge nozzle B2 is a nozzle that discharges the high-viscosity coating liquid 12 having a higher viscosity than the low-viscosity coating liquid 11 onto the semiconductor wafer 3, and includes a nozzle section that discharges the coating liquid onto the wafer surface and a tube connection section. The connecting portion is connected to the tube from the coating liquid discharge pump B10.

  The coating liquid discharge nozzle A1 and the coating liquid discharge nozzle B2 are attached to a support part that can move horizontally up and down at the tip of the scan arm 5, and the semiconductor wafer is driven by driving the scan arm 5 according to control of a control device (not shown). The nozzles quickly move to the rotation center position 3, and the nozzles are properly used. Further, the control device controls the driving of the coating liquid discharge pump A9 and the coating liquid discharge pump B10, and drives the discharge pump connected to the nozzle at the rotation center position of the semiconductor wafer 3.

  In the present embodiment, the two nozzles are collectively attached to the tip of the scan arm 5, but may be attached to separate scan arms, for example, when each nozzle can be used quickly. Also, it is possible to connect the two types of coating liquid tubes to one tube connecting section by configuring the nozzle connecting section to have an injection switching function for switching the coating liquid to be injected into the nozzle. Good. When one nozzle is used, the control device controls injection switching of two types of coating liquids at the tube connection portion, and controls to drive a discharge pump that sends out the coating liquid selected as the injection liquid by the injection switching. It will be.

  The coating liquid discharge pump A9 is a pump that sends the low-viscosity coating liquid 11 to the coating liquid discharge nozzle A1, and a tube connected to the coating liquid discharge nozzle A1 and a tube connected to the container of the low-viscosity discharge liquid 11 are connected. Has been. The coating liquid discharge pump B10 is a pump that feeds the high-viscosity coating liquid 12 to the coating liquid discharge nozzle B2, and a tube connected to the coating liquid discharge nozzle B2 and a tube connected to the container of the high-viscosity discharge liquid 12 are connected. Has been.

  Next, the spin coating control performed by the coating processing apparatus of this embodiment will be described. FIG. 2 is a flowchart showing the flow of spin coating control in the present embodiment. FIG. 3 illustrates a coating process according to the spin coating control in the present embodiment.

  First, a low-viscosity coating liquid is discharged to the rotation center position of the substrate (step S1). Specifically, as shown in FIG. 3A, the coating liquid discharge nozzle A1 is moved to the rotation center position of the semiconductor wafer 3 vacuum-sucked by the spin chuck 4, and the semiconductor wafer 3 is applied in a stationary state. The low-viscosity coating liquid 11 is discharged from the liquid discharge nozzle A1. When the low-viscosity coating liquid 11 is discharged from the coating liquid discharge nozzle A1, the semiconductor wafer 3 may be rotated at a low speed. In the following description, the case where the low-viscosity coating liquid 11 is discharged while the wafer is stationary will be described.

  After the low-viscosity coating liquid is discharged onto the substrate, the substrate is rotated at a low speed (step S2) until a predetermined time has elapsed (step S3 / NO). Specifically, as shown in FIG. 3B, the coating liquid discharge nozzle B2 is moved to the rotation center position of the semiconductor wafer 3 so as to be replaced with the coating liquid discharge nozzle A1, and the drive motor 8 moves the spin chuck 4 to the spin chuck 4. The held semiconductor wafer 3 is rotated at a low speed to spread the low viscosity coating solution 11 on the wafer surface. At this time, the high-viscosity coating liquid 12 is not discharged from the coating liquid discharge nozzle B2.

  Next, after the substrate is rotated at a low speed and a predetermined time has passed (step S3 / YES), the rotation of the substrate is temporarily stopped (step S4), and the high-viscosity coating liquid is discharged to the rotation center position of the substrate (step S5). Then, the substrate is rotated again at a low speed (step S6) until the high-viscosity coating liquid spreads over the entire substrate (step S7 / NO). Specifically, as shown in FIG. 3C, the high-viscosity coating liquid 12 is discharged from the coating liquid discharge nozzle B2 while being familiar with the low-viscosity coating liquid 11, and the low-viscosity coating liquid 11 and the high-viscosity are obtained by low-speed rotation. The coating liquid 12 is gradually spread on the wafer surface. First, the low-viscosity coating liquid 11 reaches the outer peripheral portion of the semiconductor wafer 3 and then spreads so that the high-viscosity coating liquid 12 follows. The high-viscosity coating liquid 11 necessary for forming a desired film thickness is continuously fed while the low-viscosity coating liquid 11 having high wettability serving as the priming water covers the wafer surface in advance, so that the high-viscosity is applied to the outer periphery of the wafer. It becomes possible to spread the coating liquid 12 stably.

  The predetermined time until the discharge of the high-viscosity coating liquid 12 is started is the time it takes for the permeation portion of the low-viscosity coating liquid previously discharged to become the target region, and the viscosity, the dripping amount of the low-viscosity coating liquid, A time is set in advance based on the number of rotations of the wafer and stored in a memory in the control device. As described above, in this flow, the method of measuring the timing of discharging the high-viscosity coating solution with time (step S3) is used, but the time point when the low-viscosity coating solution penetrates to a predetermined area on the wafer surface is grasped. Therefore, a method may be used in which an area where the low-viscosity coating liquid has permeated is detected by an optical sensor or the like to determine whether the predetermined area has been reached, or the permeated area is imaged by a CCD (Charge Coupled Device) or the like. A method may be used in which the determination is made by comparing the data with image data in a predetermined area.

  When the high-viscosity coating solution spreads over the entire substrate due to the low-speed rotation of the substrate (step S7 / YES), the rotation of the substrate is changed from the low-speed to the high-speed until the predetermined time elapses (NO in step S9). (Step S6). Specifically, as shown in FIG. 3D, after the high-viscosity coating liquid 12 is spread over the entire surface of the semiconductor wafer 3, the rotation speed of the wafer is gradually changed from a low speed to a high speed. Is adjusted so as to obtain a desired film thickness.

  As a method for determining whether or not the high-viscosity coating liquid 12 has spread over the entire surface of the semiconductor wafer 3 (step S7), a method of measuring time as in the case of the discharge start timing of the high-viscosity coating liquid 12 may be used. The application status may be detected by a sensor, or the application status may be verified by image data. In addition, as a method for determining whether or not the high-viscosity coating liquid 12 has a desired film thickness, a method of measuring time (step S9) as in the present flow, a method of detecting a coating state with a sensor, Alternatively, a method of verifying the application status with image data may be used.

  Step S1 (discharge of low-viscosity coating liquid) in the flowchart of FIG. 2 is stage (1), steps S2 to 3 (low-speed rotation after discharging low-viscosity coating liquid) are stage (2), and steps S4 to 6 (high viscosity) FIG. 4 shows a sequence when step (3) is set for discharging the coating liquid and low speed rotation after discharging) and step (4) is set for steps S7 to 9 (high speed rotation after applying the high viscosity coating liquid). It is.

  In step (1), the low-viscosity coating solution 11 is discharged while the semiconductor wear 3 is stationary. In step (2), the semiconductor wafer 3 is rotated at a low speed in order to spread the discharged low-viscosity coating solution 11 on the wafer surface. In step (3), the rotation is temporarily stopped and the high-viscosity coating liquid 12 is discharged. After the discharge, the low-speed rotation of the wafer is resumed to spread the high-viscosity coating liquid 12 over the entire surface of the semiconductor wafer 3. In (4), the rotation speed of the wafer is gradually changed from a low speed to a high speed so that the high viscosity coating liquid 12 spread over the entire wafer surface has a desired film thickness.

  In the present embodiment, this is performed with the semiconductor wafer 3 being stationary when the low-viscosity coating liquid 11 or the high-viscosity coating liquid 12 is ejected. However, the coating liquid may be ejected while rotating at a low speed. The wafer may be rotated at a low speed while discharging the coating liquid is started while the semiconductor wafer 3 is stationary.

  The above-described embodiment is a preferred embodiment of the present invention, and the scope of the present invention is not limited to the above-described embodiment alone, and various modifications are made without departing from the gist of the present invention. Implementation is possible.

  For example, when applying a low-viscosity coating liquid, pre-wetting treatment using a thinner may be performed in advance. Further, the coating processing apparatus to which the present invention is applied can be used as a resist coating processing apparatus such as a photoresist used in a photolithography process for forming an electrode pattern on a wafer. It is possible to reduce the amount of resist required for production and to reduce the production cost. The substrate to be processed is not limited to a semiconductor wafer, and may be another substrate such as an LCD (Liquid Crystal Display) substrate.

  According to the above-described embodiment, the high-viscosity solvent can be smoothly spread from the center portion to the outer peripheral portion of the substrate, so that it is possible to obtain a coating film with excellent film quality by reducing entrainment of bubbles in the coating film. It becomes.

  Further, according to the above-described embodiment, it is possible to reduce the amount of the coating liquid to be used.

  Further, according to the above-described embodiment, it is possible to eliminate the generation of bubbles in the film and form a coating film with excellent film quality without newly providing a device for suppressing the drying of the coating liquid surface. Become.

It is the figure which showed schematic structure of the coating processing apparatus which concerns on embodiment of this invention. It is the flowchart which showed the flow of the spin coating control in embodiment of this invention. The coating process according to the rotation coating control in the embodiment of the present invention is illustrated. It is a sequence diagram showing the spin coating control in the embodiment of the present invention. It is a figure for demonstrating the application state to the board | substrate of the coating liquid by a spin coat method.

Explanation of symbols

1 Coating liquid discharge head A
2 Coating liquid discharge head B
3 Semiconductor wafer 4 Spin chuck 5 Scan arm 6 Coater cup 7 Drain 8 Drive motor 9 Coating liquid discharge pump A
10 Coating liquid discharge pump B
11 Low viscosity coating solution 12 High viscosity coating solution

Claims (6)

A coating processing apparatus for forming a coating film by spreading the coating liquid on the substrate over the entire surface of the substrate by rotating the substrate,
A first coating liquid discharge means for discharging a low-viscosity coating liquid having high wettability to the substrate surface with a solution having the same chemical component as the solution for forming the coating film to the rotation center position of the substrate;
After the low-viscosity coating liquid is ejected by the first coating liquid ejection means, a high-viscosity coating liquid having a viscosity higher than that of the low-viscosity coating liquid is ejected to the rotation center position with a solution for forming the coating film. A second coating liquid discharging means,
Substrate rotating means for fixing the substrate at the rotation center position and rotating the substrate at a predetermined rotation speed;
The coating processing apparatus characterized by having.   The said 2nd coating liquid discharge means discharges the said high-viscosity coating liquid before the said low-viscosity coating liquid discharged by the said 1st coating liquid discharge means spreads over the said board | substrate whole surface. The coating processing apparatus as described.   The substrate rotation means has a rotation speed so that the high-viscosity coating liquid discharged by the second coating liquid discharge means is rotated at a higher speed than when the high-viscosity coating liquid is discharged after spreading over the entire surface of the substrate. The coating processing apparatus according to claim 1, wherein the coating processing apparatus is changed. A coating processing method for forming a coating film by spreading the coating liquid on the substrate over the entire surface of the substrate by rotating the substrate,
A first coating liquid discharge step of discharging a low-viscosity coating liquid having high wettability to the substrate surface with a solution having the same chemical component as the solution for forming the coating film to the rotation center position of the substrate;
A first substrate rotating step of rotating the substrate on which the low-viscosity coating solution has been discharged in the first coating solution discharging step at a predetermined rotation speed;
After the low-viscosity coating liquid is discharged in the first coating liquid discharging step, a high-viscosity coating liquid having a viscosity higher than that of the low-viscosity coating liquid is discharged to the rotation center position with a solution for forming the coating film. A second coating liquid discharging step,
A second substrate rotating step of rotating the substrate on which the high-viscosity coating solution has been discharged in the second coating solution discharging step at a predetermined rotation speed;
A coating treatment method characterized by comprising:   The said 2nd coating liquid discharge step discharges the said high-viscosity coating liquid before the said low-viscosity coating liquid discharged by the said 1st coating liquid discharge step spreads over the said board | substrate whole surface. The coating process method of description.   The second substrate rotating step is rotated so that the high-viscosity coating liquid discharged in the second coating liquid discharging step spreads over the entire surface of the substrate and then rotates at a higher speed than when the high-viscosity coating liquid is discharged. 6. The coating treatment method according to claim 4, wherein the speed is changed.

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