JP2005029233A - Method for packaging substrate exposing surface of material and package - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for packaging an substrate for efficiently packaging an etched wafer or the like with the surface of a material being exposed at low costs and effectively suppressing oxidation of the surface during storage, and to provide a package. <P>SOLUTION: In a method for packaging the substrate W with the surface of the material being exposed, a laminated bag P containing the substrate W is placed in a chamber 2, the inside of the chamber 2 is evacuated, while nitrogen gas is supplied into the chamber 2 by supplying the nitrogen gas through a nitrogen gas nozzle 10 inserted in the opening of the laminated bag P, the opening of the laminated bag P is sealed to package the substrate W. Further, after the inside of the chamber 2 is evacuated and the nitrogen gas is supplied, the inside of the chamber 2 is evacuated again to supply nitrogen gas. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method and a packaging body for packaging a substrate whose surface is exposed, such as a substrate after etching.

  For example, a semiconductor wafer (hereinafter referred to as “wafer”) such as GaAs (gallium arsenide) may be stored for a while after being subjected to a surface treatment such as etching, and a process such as epitaxial growth may be performed after several days. During storage, it is necessary to keep the wafer surface clean and suppress surface oxidation. Conventionally, as a method for storing wafers after etching, a method of storing wafers one by one in a dedicated airtight container has been proposed (see, for example, Patent Document 1). In this method, the oxidation of the wafer surface is suppressed by making the inside of the hermetic container a nitrogen gas atmosphere to have a low oxygen concentration.

JP-A-2-204400

  In the conventional method, a dedicated airtight container for storing the wafer is required, which increases the cost. Furthermore, it is difficult to securely seal the main body and lid of the hermetic container, and oxygen may enter during storage and oxidation may proceed. Also, it took a long time to reduce the oxygen concentration in the airtight container, and a large amount of nitrogen gas was required.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method and a packaging method for a substrate that can efficiently wrap wafers exposed on the surface of a material such as etched wafers at low cost and effectively suppress oxidation of the surface during storage. To provide a body.

  In order to solve the above-mentioned problems, according to the present invention, there is provided a method for packaging a substrate with the surface of a material exposed, wherein a laminate bag containing a substrate is placed in a chamber, the inside of the chamber is decompressed, and the laminate A substrate packaging method is provided, wherein nitrogen gas is supplied from a nitrogen gas nozzle inserted into an opening of a bag, the opening of the laminate bag is sealed, and the substrate is packaged. Here, the substrate from which the surface of the material is exposed is, for example, a wafer after etching. According to such a substrate packaging method, the etched wafer can be packaged by using a laminate bag and a chamber type packaging machine that are used in a normal packaging form such as a wafer. Therefore, the wafer can be packaged at a low cost. In addition, the opening of the laminate bag can be easily and reliably sealed by thermocompression bonding.

  In this packaging method, it is preferable to decompress the inside of the chamber, introduce nitrogen gas into the chamber, decompress the inside of the chamber again, and then supply nitrogen gas from the nitrogen gas nozzle. Then, the oxygen concentration inside the laminate bag can be further reduced.

  In addition, according to the present invention, there is provided a substrate packaging body characterized in that the inside of the laminate bag in which the substrate with the surface of the material exposed is packaged has an oxygen concentration of 2% or less. In this package, even if oxygen is generated from a tray placed in a laminate bag, the oxygen concentration does not increase excessively, and a good antioxidant effect is obtained.

  According to the present invention, a substrate can be airtightly packaged using a laminate bag and a chamber-type packaging machine that are used in a normal packaging form of the substrate. Therefore, it is not necessary to prepare a dedicated airtight container or the like, and the substrate can be airtightly packaged at a low cost. In addition, the opening of the laminate bag can be sealed easily and reliably. The inside of the laminate bag can be efficiently reduced in oxygen concentration in a short time. The substrate can be effectively prevented from being oxidized while the substrate is being stored.

  Hereinafter, preferred embodiments of the present invention will be described. As shown in FIG. 1, the aluminum laminate pack P (hereinafter referred to as “laminate pack P”) is formed in a bag shape, and the opening of the laminate pack P can be sealed by thermocompression bonding. The laminate pack P is used for a normal packaging form of wafers. Inside the laminate pack P, a GaAs substantially disk-shaped wafer W and a tray T are accommodated. In the present embodiment, the wafer W is after etching. The tray T is made of, for example, polypropylene. The wafer W is placed in the tray T with the front surface (surface on which semiconductor devices are formed) being the bottom surface.

  As shown in FIG. 2, the chamber type packaging machine 1 that seals the laminate pack P includes a chamber 2 that forms a sealed space therein. The chamber 2 includes a chamber body 3 and a lid 4 that covers the upper surface of the chamber body 3.

A mounting table 7 on which the laminate pack P is mounted is provided inside the chamber 2. On the upper surface of the mounting table 7, six laminate packs P can be placed side by side. Six nitrogen gas nozzles 10 that are inserted into the openings of the laminate pack P and discharge nitrogen (N ₂ ) gas are provided on the side of the mounting table 7. The nitrogen gas nozzles 10 are arranged horizontally along the long side of the upper surface of the mounting table 5, and are provided so as to protrude from the nitrogen gas supply pipe 11 toward the mounting table 7 in the horizontal direction. The size of the inner surface side of the nitrogen gas nozzle 10 is, for example, a length from the base end to the nozzle opening of about 2 cm, a width of about 5 mm, and a height at the nozzle opening of about 1 mm.

  Further, a sealer 15 for heating and thermocompression-bonding the opening of the laminate pack P is provided inside the chamber 2. As shown in FIG. 3, the sealer 15 includes a lower sealer 16 that contacts the opening of the laminate pack P from below, and an upper sealer 17 that contacts the opening of the laminate pack P from above. The lower sealer 16 is disposed on the peripheral edge of the upper surface of the mounting table 7 and is positioned below the opening of the laminate pack P. The upper sealer 17 can be moved up and down between a standby position above the laminate pack P and a contact position in contact with the upper surface of the opening of the laminate pack P. The upper sealer 17 is lowered, and the opening is sandwiched between the lower sealer 16 and the upper sealer 17 and heated to bond the inner surface of the opening.

  Further, a nitrogen gas introduction path 20 for introducing nitrogen gas into the chamber 2 is provided. Further, a chamber exhaust path 21 for exhausting the inside of the chamber 2 is provided. The chamber exhaust passage 21 is connected to a vacuum pump (not shown) through a valve (not shown).

  Next, a method for packaging the wafer W using the chamber type packaging machine 1 configured as described above will be described. First, before packaging the wafer W, the wafer W is subjected to a surface smoothing process and then subjected to a surface treatment by etching. As a result, a part of the surface of GaAs which is the material of the wafer W is exposed. Then, after inspecting the etched wafer W, the packaging process is started. The wafer W is placed in the tray T with the front side facing down, and is inserted into the inside of the laminate pack P together with the tray T.

  The laminate pack P storing the wafer W and the tray T is transported to the chamber type packaging machine 1 and stored inside the chamber 2. In the chamber 2, the laminate pack P is placed on the upper surface of the placing table 7 with the nitrogen gas nozzle 10 inserted into the opening. Further, the wafer W is placed so that the surface thereof faces downward. The upper sealer 17 is kept waiting above the laminate pack P. In this way, six laminate packs P are arranged on the upper surface of the mounting table 7.

  When the laminate pack P is arranged on the mounting table 7, the lid 4 is closed and the chamber 2 is sealed. First, a vacuum pump (not shown) is operated, the inside of the chamber 2 is exhausted by the chamber exhaust passage 21, and the inside of the chamber 2 is decompressed. When the inside of the chamber 2 reaches the target degree of vacuum (pressure), the valve (not shown) is closed to stop the exhaust.

  Next, nitrogen gas is supplied from the nitrogen gas nozzle 10 and the nitrogen gas introduction path 20. Thus, by introducing nitrogen gas after depressurizing the inside of the chamber 2, the atmosphere in the chamber 2 is replaced with nitrogen gas, and the inside of the chamber 2 is brought to a low oxygen concentration. Further, by supplying nitrogen gas from the nitrogen gas nozzle 10, oxygen is efficiently pushed out from the inside of the laminate pack P by the nitrogen gas, and the inside of the laminate pack P can be quickly reduced to a low oxygen concentration. Moreover, oxygen is uniformly pushed out from the six laminate packs P in the chamber 2, and the variation in the oxygen concentration in each laminate pack P can be reduced. When the pressure in the chamber 2 reaches the target pressure, the supply of nitrogen gas from the nitrogen gas nozzle 10 and the nitrogen gas introduction path 20 is stopped.

  Subsequently, the valve (not shown) is opened again, the inside of the chamber 2 is exhausted by the chamber exhaust passage 21, and the inside of the chamber 2 is decompressed. When the inside of the chamber 2 reaches the target degree of vacuum (pressure), the valve (not shown) is closed to stop the exhaust.

  Thereafter, nitrogen gas is again supplied from the nitrogen gas nozzle 10 and the nitrogen gas introduction path 20. By performing the second nitrogen gas replacement in the chamber 2, the inside of the chamber 2 can be further reduced in oxygen concentration. When the pressure in the chamber 2 reaches the target pressure, the supply of nitrogen gas from the nitrogen gas nozzle 10 and the nitrogen gas introduction path 20 is stopped.

  After the chamber 2 and the laminate pack P are thus brought to a low oxygen concentration, the upper sealer 17 is then lowered, the opening of the laminate pack P is sandwiched between the lower sealer 16 and the upper sealer 17, and the lower sealer 16 The upper sealer 17 is heated to heat the opening, and the inner surface of the opening is bonded. Thereby, the opening part of the laminate pack P is reliably sealed. Thus, a package body in which the wafer W and the tray T are air-tightly wrapped with the laminate pack P is completed.

  Thereafter, the lid 4 is opened and the package is carried out of the chamber 2. As described above, the packaging process of the wafer W by the chamber type packaging machine 1 is completed. The package is shipped to a factory that performs processes such as epitaxial growth. While the package is being transported and stored, the airtight state of the laminate pack P of the package is reliably maintained, and oxygen does not enter the laminate pack P from outside air. Therefore, the inside of the laminate pack P is maintained at a low oxygen concentration, and the oxidation of the surface of the wafer W is suppressed.

  In each factory, the stored laminate pack P of the package is opened, the wafer W is taken out, and an epitaxial growth process is performed. At this time, it is not necessary to perform the surface oxide film removal process of the wafer W before the epitaxial growth process, and even if the epitaxial growth is performed immediately, there is no fear that the growth surface becomes non-uniform. Therefore, it is possible to efficiently manufacture a semiconductor device having good characteristics.

  Depending on the material of the tray T, oxygen may be generated from the tray T, and the oxygen concentration inside the laminate pack P may increase by, for example, about 0.35% after packaging. By sufficiently reducing the oxygen concentration in the laminate pack P at the time of sealing, the oxygen concentration inside the laminate pack P can be kept low, and oxidation of the wafer surface can be effectively suppressed. The oxygen concentration in the laminate pack P when the opening of the laminate pack P is sealed is preferably about 2% or less, for example. In this case, even if oxygen is generated from the tray T, the oxygen concentration in the laminate pack P does not increase excessively, and a good antioxidant effect is obtained. More preferably, the oxygen concentration in the laminate pack P at the time of sealing is set to a value such that the oxygen concentration is maintained at about 1% or less even when the oxygen concentration increases due to the generation of oxygen from the tray T. In particular, when the oxygen concentration at the time of sealing is about 0.1% or less, even if oxygen is generated from the tray T, the oxygen concentration can be suppressed to about 0.5% or less, and a very good antioxidant effect is obtained. be able to. Further, the oxygen concentration at the time of sealing may be about 0.5%. Also in this case, even if oxygen is generated from the tray T, the oxygen concentration can be suppressed to about 1% or less, and a satisfactory antioxidant effect can be obtained. Moreover, the pressure can be reduced in a shorter time than when the oxygen concentration at the time of sealing is about 0.1% or less, and the efficiency is high.

  According to such a packaging method, a laminate pack P used in a normal packaging form such as a wafer W, and a chamber type packaging machine 1 in which a nitrogen gas nozzle 10 is attached to a chamber type packaging machine used in a normal packaging form such as a wafer W. The wafer W after etching can be packaged in an airtight manner. Therefore, it is not necessary to prepare a dedicated airtight container or the like for storing the etched wafer W, and the wafer W can be packaged at low cost. Further, the opening of the laminate pack P can be easily and reliably sealed by thermocompression bonding. Therefore, it is possible to reliably prevent oxygen from entering from the outside air, effectively suppress the oxidation of the surface of the wafer W, and keep the surface clean. Further, by supplying nitrogen gas with the nitrogen gas nozzle 10 inserted into the laminate pack P, the inside of the laminate pack P can be efficiently reduced to a low oxygen concentration in a short time. Furthermore, the supply amount of nitrogen gas can be reduced. The oxygen concentration can be sufficiently lowered by the nitrogen gas replacement twice. And the wafer W packaged by such a packaging method is effectively suppressed from oxidizing the surface even during storage for several days.

  Although an example of a preferred embodiment of the present invention has been described above, the present invention is not limited to the embodiment described here. For example, in the present embodiment, the substrate is a GaAs semiconductor wafer, but is not limited to this, and can be applied to various substrates. In the present embodiment, the process for exposing the surface of the wafer W is etching. However, the present invention is not limited to this, and may be, for example, a process for removing an oxide film or the like using an amine-based chemical solution. .

(Example 1)
The laminate pack P containing the wafer W and the tray T was stored inside the chamber 2, and the inside of the chamber 2 was depressurized by the chamber exhaust path 21. The ultimate pressure in the chamber 2 was set to about 3 × 10 ⁴ Pa (about 0.3 atm). The time required for the pressure in the chamber 2 to reach about 3 × 10 ⁴ Pa was about 5 seconds. Next, nitrogen gas was supplied from the nitrogen gas nozzle 10 and the nitrogen gas introduction path 20. The ultimate pressure in the chamber 2 was about 9 × 10 ⁴ Pa (about 0.9 atm). Subsequently, the pressure inside the chamber 2 was reduced again by the chamber exhaust passage 21. The ultimate pressure in the chamber 2 was about 3 × 10 ⁴ Pa. The time required for the pressure in the chamber 2 to reach about 3 × 10 ⁴ Pa was about 5 seconds. Thereafter, nitrogen gas was supplied from the nitrogen gas nozzle 10 and the nitrogen gas introduction path 20. The ultimate pressure in the chamber 2 was about 9 × 10 ⁴ Pa. Thus, the oxygen concentration inside the laminate pack P could be reduced to about 2%.

(Example 2)
The laminate pack P containing the wafer W and the tray T was stored inside the chamber 2, and the inside of the chamber 2 was depressurized by the chamber exhaust path 21. The ultimate pressure in the chamber 2 was about 2 × 10 ⁴ Pa (about 0.2 atm). The time required for the pressure in the chamber 2 to reach about 2 × 10 ⁴ Pa was about 5.5 seconds. Next, nitrogen gas was supplied from the nitrogen gas nozzle 10 and the nitrogen gas introduction path 20. The ultimate pressure in the chamber 2 was about 9 × 10 ⁴ Pa. Subsequently, the pressure inside the chamber 2 was reduced again by the chamber exhaust passage 21. The ultimate pressure in the chamber 2 was about 2 × 10 ⁴ Pa. The time required for the pressure in the chamber 2 to reach about 2 × 10 ⁴ Pa was about 5.5 seconds. Thereafter, nitrogen gas was supplied from the nitrogen gas nozzle 10 and the nitrogen gas introduction path 20. The ultimate pressure in the chamber 2 was about 9 × 10 ⁴ Pa. Thus, the oxygen concentration inside the laminate pack P could be reduced to about 1%.

(Example 3)
The laminate pack P containing the wafer W and the tray T was stored inside the chamber 2, and the inside of the chamber 2 was depressurized by the chamber exhaust path 21. The ultimate pressure in the chamber 2 was about 1 × 10 ³ Pa. The time required for the pressure in the chamber 2 to reach about 1 × 10 ³ Pa was about 18 seconds. Next, nitrogen gas was supplied from the nitrogen gas nozzle 10 and the nitrogen gas introduction path 20. The ultimate pressure in the chamber 2 was about 9 × 10 ⁴ Pa. The time required for the pressure in the chamber 2 to reach about 9 × 10 ⁴ Pa was about 21 seconds. Subsequently, the pressure inside the chamber 2 was reduced again by the chamber exhaust passage 21. The ultimate pressure in the chamber 2 was about 1 × 10 ³ Pa. The time required for the pressure in the chamber 2 to reach about 1 × 10 ³ Pa was about 18 seconds. Thereafter, nitrogen gas was supplied from the nitrogen gas nozzle 10 and the nitrogen gas introduction path 20. The ultimate pressure in the chamber 2 was about 9 × 10 ⁴ Pa. The time required for the pressure in the chamber 2 to reach about 9 × 10 ⁴ Pa was about 21 seconds. Thus, the oxygen concentration inside the laminate pack P could be reduced to about 0.5%.

(Example 4)
The laminate pack P containing the wafer W and the tray T was stored inside the chamber 2, and the inside of the chamber 2 was depressurized by the chamber exhaust path 21. The ultimate pressure in the chamber 2 was about 17 Pa. The time required for the pressure in the chamber 2 to reach about 17 Pa was about 4 hours. Next, nitrogen gas was supplied from the nitrogen gas nozzle 10 and the nitrogen gas introduction path 20. The ultimate pressure in the chamber 2 was about 9 × 10 ⁴ Pa. The time required for the pressure in the chamber 2 to reach about 9 × 10 ⁴ Pa was about 21 seconds. Subsequently, the pressure inside the chamber 2 was reduced again by the chamber exhaust passage 21. The ultimate pressure in the chamber 2 was about 17 Pa. The time required for the pressure in the chamber 2 to reach about 17 Pa was about 4 hours. Thereafter, nitrogen gas was supplied from the nitrogen gas nozzle 10 and the nitrogen gas introduction path 20. The ultimate pressure in the chamber 2 was about 9 × 10 ⁴ Pa. The time required for the pressure in the chamber 2 to reach about 9 × 10 ⁴ Pa was about 21 seconds. Thus, the oxygen concentration inside the laminate pack P could be reduced to about 0.1%.

(Test 1)
The present inventors conducted a test to confirm the antioxidant effect of the packaging method according to the present invention. By the packaging method shown in Example 1, 2, 3 or 4 above, the oxygen concentration inside the laminate pack P should be about 0.1%, about 0.5%, about 1%, or about 2%. A plurality of package bodies (0.1% product, 0.5% product, 1% product, 2% product) packaged to the target were prepared for each target oxygen concentration. Also, a plurality of packaged bodies (10% products) were manufactured which were packaged with the goal of setting the oxygen concentration inside the laminate pack P to about 10%. The wafer W was manufactured by the VGF (Vertical Gradient Freeze) method, and the surface was etched with an ammonia-hydrogen peroxide chemical solution and packaged immediately after the etching. The tray T was made of polypropylene. These are stored at room temperature, and periodically measured for the oxygen (O ₂ ) concentration in the laminate pack P and the X-ray spectroscopic measurement (ESCA measurement) of the surface of the wafer W for each package with a target oxygen concentration. Went. The measurement was performed immediately after completion of the package, and after 7 days, 14 days, and 30 days after the package was stored. In X-ray spectroscopic measurement, a sample for measurement is selected from the package of each target oxygen concentration for each measurement, the laminate pack P is opened, the wafer W is taken out, and an X-ray spectroscope (JPS-manufactured by JEOL Ltd.) 9000 MC). Then, from the spectrum observed by X-ray spectroscopic measurement, the ratio of the peak total area of the As oxide component to the peak total area of As (arsenic) (peak intensity ratio) (As _ox / As _total ) and Ga (gallium) The ratio of the peak total area of the Ga oxide component to the total peak area (peak intensity ratio) (Ga _ox / Ga _total ) was calculated, and the oxidation progress of the wafer W was evaluated. Further, the X-ray spectroscopic measurement was performed on the central portion and the edge portion of the wafer W. 4, 5 and 6 show the measurement results of the above test. From the measurement results, 0.1% products, 0.5% products, 1% products, and 2% products have good anti-oxidation effects on the wafer W, and the packaging shown in Examples 1, 2, 3, or 4 It was found that the method can satisfactorily suppress the oxidation of the wafer W. In particular, the 0.1% product, the 0.5% product, and the 1% product had a very good anti-oxidation effect on the wafer W. On the other hand, the 10% product has a significantly increased surface oxide ratio compared to the 0.1% product, 0.5% product, 1% product and 2% product. I couldn't.

(Test 2)
In addition, the present inventors conducted a test to confirm the effect of supplying nitrogen gas by the nitrogen gas nozzle 10 and the effect of supplying and depressurizing nitrogen gas twice. The chamber-type packaging machine 1 (hereinafter referred to as “packaging machine with nozzle”) shown in the present embodiment and the chamber-type packaging machine 1 in which the nitrogen gas nozzle 10 is removed from the chamber-type packaging machine 1 (hereinafter referred to as “packaging without nozzle”). The wafer W was packaged by a method of performing nitrogen gas replacement once and a method of performing twice. That is, (1) in a packaging machine with a nozzle, the inside of the chamber 2 is depressurized, and a packaging body is packaged by supplying nitrogen gas from the nitrogen gas nozzle 10 and the nitrogen gas introduction path 20 and sealing it; , The inside of the chamber 2 is depressurized, the nitrogen gas is supplied from the nitrogen gas introduction path 20 and the package is packed by the sealing method. (3) In the packaging machine with a nozzle, the inside of the chamber 2 is depressurized, A package packaged by supplying nitrogen gas from the nitrogen gas introduction path 20, depressurizing the inside of the chamber 2 again, and supplying nitrogen gas from the nitrogen gas nozzle 10 and the nitrogen gas introduction path 20, (4) In a nozzleless packaging machine The pressure in the chamber 2 is reduced, nitrogen gas is supplied from the nitrogen gas introduction path 20, the pressure in the chamber 2 is reduced again, and the nitrogen gas introduction path 20 is again supplied. Package was wrapped by a method for supplying hydrogen gas to produce a. As shown in FIG. 7, the reduced pressure is about 2 × 10 ⁴ Pa (decompression degree of about −80), about 1 × 10 ⁴ Pa (decompression degree of about −90), or about 0 Pa (decompression degree of about −100). Each of these three different degrees of vacuum was packaged. The first and second decompressions in (3) and (4) were performed at the same degree of decompression. The introduction of the nitrogen gas through the nitrogen gas introduction path 20 and the supply of the nitrogen gas through the nitrogen gas nozzle 10 were performed so that the inside of the chamber 2 was at normal pressure (about 1 × 10 ⁵ Pa). And about the package of (1)-(4), the oxygen concentration in the laminate pack P was each measured immediately after completion of each package. Moreover, the calculated value of the oxygen concentration in the laminate pack P was calculated about each package of (1)-(4), respectively. 7 and 8 show measurement results and calculation results. From the measurement results, the package with the lowest oxygen concentration was the package (3). Therefore, it was found that the method shown in this embodiment can efficiently reduce the oxygen concentration.

It is a perspective view of a laminate pack. It is a schematic perspective view of a chamber type packaging machine. It is sectional drawing of a chamber. 6 is a table showing the results of oxygen concentration measurement and X-ray spectroscopic measurement in Test 1. 4 is a graph showing measurement results of peak intensity ratios of As in Test 1. 6 is a graph showing measurement results of Ga peak intensity ratios in Test 1. FIG. 6 is a table showing measurement results of oxygen concentration in Test 2. 6 is a graph showing the measurement results of oxygen concentration in Test 2.

Explanation of symbols

P Laminate pack T Tray W Wafer 1 Chamber type packaging machine 2 Chamber 10 Nitrogen gas nozzle 15 Sealer 20 Nitrogen gas introduction path 21 Chamber exhaust path

Claims (3)

A method of packaging a substrate with an exposed surface of a material,
Put the laminate bag with the substrate in the chamber,
Depressurizing the chamber;
Supplying nitrogen gas into the chamber while supplying nitrogen gas from a nitrogen gas nozzle inserted into the opening of the laminate bag;
A substrate packaging method, wherein an opening of the laminate bag is sealed and the substrate is packaged. 2. The substrate packaging method according to claim 1, wherein the chamber is decompressed and nitrogen gas is supplied, and then the chamber is decompressed again and nitrogen gas is supplied. A substrate packaging body, characterized in that the inside of the laminate bag in which the substrate with the exposed surface of the material is wrapped has an oxygen concentration of 2% or less.

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