Airtight storage container

Abstract

To provide an airtight housing container that does not deteriorate the particle level on a surface of a wafer on the uppermost stage.SOLUTION: An airtight housing container includes a container main body for housing a wafer, and a lid that opens and closes an opening of the container main body. Inside the container main body, groove parts in each of which the wafer is placed and housed are provided in multiple stages in a vertical direction. Between the groove part on the uppermost stage among the groove parts in the multiple stages and an upper wall of the container main body, a dust adhesion prevention plate is disposed apart from the upper wall. The dust adhesion prevention plate includes a cut part. The cut part is disposed to exist on a depth wall side of the container main body.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a sealed container. [Background technology]

[0002] The positional relationships of load boats in Equipment Front End Modules (EFEMs), which are devices used in the process of manufacturing semiconductor wafers such as silicon (hereinafter simply referred to as wafers), and Front Opening Unified Pods (FOUPs), which are sealed containers (hereinafter simply referred to as containers) that store semiconductor wafers, are regulated by SEMI (Semiconductor Equipment and Material International) standards.

[0003] When the FOUP lid is opened by the load port, the inside of the FOUP can become contaminated by the inflow of outside air containing dust generated from the load port and other equipment, the FOUP packing, etc. This dust can cause defects in the semiconductor wafers stored in the FOUP, so dust inflow (dust generation) evaluations are conducted when installing equipment such as equipment or during regular FOUP storage quality evaluations to evaluate how much dust will flow into the FOUP when the FOUP lid is opened, to adjust the speed of the lid opening and closing operation and the pressure conditions so as not to cause a sudden change in the pressure of the storage container when the lid is opened and to evaluate the deterioration state of the FOUP sealing packing.

[0004] The dust inflow evaluation results showed that contamination of the wafers occurred due to the above-mentioned dust. For example, Patent Documents 1-5 take measures to prevent such dust from adhering to the wafers, but these measures are insufficient. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2017-112132 A [Patent Document 2] Special Publication No. 2014-513442 [Patent Document 3] JP 2001-015582 A [Patent Document 4] JP 2010-056296 A [Patent Document 5] JP 2019-029596 A Summary of the Invention [Problem to be solved by the invention]

[0006] As mentioned above, when a sealed storage container such as a FOUP is filled with wafers, especially from top to bottom, there is a problem in that the surface of the topmost wafer (generally, a maximum of 25 wafers, for example, can be stored. Here, the topmost wafer refers to the 25th wafer counting from the bottom) is contaminated by the adhesion of dust (also called particles) due to the air (outside air) that flows in when the lid of the sealed storage container is opened, and the particle level on the surface of the 25th wafer deteriorates.

[0007] The present invention has been made in view of the above problems, and has as its object to provide a sealed storage container which does not worsen the particle level on the surface of the uppermost wafer. [Means for solving the problem]

[0008] In order to achieve the above object, the present invention provides a sealed storage container having a container body for storing wafers and a lid for opening and closing an opening of the container body, Inside the container body, The groove portion in which the wafer is placed and stored is provided in a plurality of stages in the vertical direction, a dust adhesion prevention plate is disposed between an uppermost groove portion of the plurality of groove portions and an upper wall of the container body and spaced apart from the upper wall; The dust adhesion prevention plate has a notch, and the notch is disposed so as to be positioned on the inner wall side of the container body.

[0009] In such a sealed storage container of the present invention, dust contained in the air flowing in when the lid of the sealed storage container is opened flows over a dust adhesion prevention plate with a cutout disposed above the wafer (e.g., the 25th wafer) placed in the groove of the topmost stage, thereby preventing the airflow from coming into contact with the top surface (surface) of the 25th wafer, and thus significantly preventing dust from adhering to the top surface of the 25th wafer. This makes it possible to prevent the particle level on the surface of the topmost wafer from deteriorating.

[0010] The dust adhesion prevention plate may be a disk-shaped plate having the cutout portion.

[0011] Such a disk-shaped plate can be formed in the same shape as a disk-shaped wafer, and can more reliably cover the topmost wafer, and can more effectively prevent the air current from coming into contact with the topmost wafer, thereby more effectively preventing adhesion of dust to the wafer. Effect of the Invention

[0012] With the sealed storage container of the present invention, when the container is fully filled with wafers, it is possible to prevent dust particles contained in the air that flows in when the lid of the sealed storage container is opened from adhering to the top surface of the wafer located in the topmost row. [Brief description of the drawings]

[0013] [Figure 1] FIG. 2 is a side view showing an example of a sealed storage container of the present invention (without storing wafers). [Diagram 2] FIG. 2 is a side view showing an example of the sealed storage container (with wafers stored therein) of the present invention. [Diagram 3]FIG. 2 is a top view showing an example of the sealed storage container (with wafers stored therein) of the present invention. [Figure 4] 1 is a graph showing evaluation results of the number of particles on the upper surface of the uppermost wafer in an example and a comparative example. [Diagram 5] FIG. 1 is an explanatory diagram showing an example of a wafer transfer device in which a general airtight storage container is arranged. [Figure 6] FIG. 1 is an explanatory diagram showing an example of a general sealed storage container. [Figure 7] FIG. 1 is a side view showing an example of a general sealed storage container (without storing wafers). [Figure 8] FIG. 1 is a side view showing an example of a general sealed storage container (with wafers stored therein). [Figure 9] FIG. 1 is a top view showing an example of a general sealed storage container (with wafers stored therein). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] The present invention will be described in more detail below, but the present invention is not limited thereto. First, the circumstances under which the present inventors came to discover the present invention will be described. The inventors investigated the flow of outside air that enters a FOUP when the lid of the sealed storage container is opened. Note that although the explanation here takes a FOUP as an example, the same applies to other sealed storage containers such as a FOSB (Front Opening Shipping Box). As a result, when the FOUP lid is opened by the load port door of the load port with all the wafers loaded inside, outside air flows in through the gap between the container body and the lid. However, because the wafers are loaded horizontally and evenly from bottom to top, it was confirmed that outside air is introduced from the lid side toward the back wall (innermost side wall) through the space between the top wall (top plate) of the FOUP and the uppermost wafer. At the same time, it was confirmed that outside air is introduced toward the back wall through the space between the bottom wall (bottom surface) of the FOUP and the lowermost wafer.

[0015] Dust can be generated from various places, such as the FOUP lid opening and closing mechanism, the transfer robot in the transfer chamber, and the load port door and opening and closing mechanism, and when the FOUP lid is opened, the outside air flowing into the container body often contains dust, and when dust is contained in the upper or lower outside air flow, dust may adhere to the top surface of the top wafer or the underside of the bottom wafer. In light of these, it was found that the cause of dust adhering to the top surface of the top wafer or the underside of the bottom wafer is the outside air (containing dust) flowing in the space between the wafer and the wall of the sealed storage container. They also discovered that there is a slightly larger space between the top wafer of the FOUP and the top wall of the container body than between the bottom wafer and the bottom wall.

[0016] From these findings, the inventors came up with the idea of ​​providing a dust adhesion prevention plate having a cutout in the space between the wafers stored in the sealed storage container and the wall of the sealed storage container in order to prevent dust from adhering to the wafers. More specifically, the inventors came up with the idea of ​​a sealed storage container in which a dust adhesion prevention plate is disposed between the topmost groove on which the wafers are placed and stored and the top wall of the container body, at a distance from the top wall, and the dust adhesion prevention plate has a cutout, and the cutout is disposed so as to be located on the inner wall side of the container body. In this case, it was found that, whereas in the past, the outside air flowing in when the lid is opened flows through the space between the topmost wafer and the top wall of the container body, by disposing the dust adhesion prevention plate, dust is less likely to adhere to the topmost wafer. The inventors found these and completed the present invention.

[0017] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In describing the sealed storage container of the present invention, first, the relationship between a general sealed storage container and a wafer transfer device will be described. 5 shows an example of a wafer transfer device 10 in which a general sealed storage container is arranged. The general sealed storage container 101 and processing device 20 are shown together. Here, a FOUP type will be described as an example of the sealed storage container 101, but the type is not particularly limited. The wafers to be transported (transferred) by the wafer transfer device 10 are not particularly limited, and examples thereof include various semiconductor wafers such as semiconductor silicon wafers and compound semiconductor wafers, and in particular, polished silicon wafers and silicon wafers formed by epitaxial growth. This device can also transfer and transport wafer-like objects such as glass substrates.

[0018] A typical FOUP 101 will now be described with reference to FIG. FOUP 101 is a sealed storage container for storing wafers. FOUP 101 comprises a container body 102 and a lid 103. Container body 102 is formed so as to be able to store multiple wafers, and has an opening (wafer loading / unloading entrance) on the front. Wafers are loaded and unloaded through this opening. In FIG. 6, the front of container body 102 is the right side. Lid 103 is for opening and closing the opening on the front of container body 102. When lid 103 is closed, the inside of container body 102 is sealed. When wafers W are stored and transported inside the FOUP 101, the wafers W are usually fully loaded.

[0019] As shown in the side view of FIG. 7 in which no wafers are stored, inside the container body 102 of the FOUP 101, multiple grooves 104 are provided in the vertical direction, and wafers can be placed and stored one by one in each groove 104. A typical FOUP is provided with 25 grooves 104, and can store 25 wafers when fully loaded. For simplicity, only seven grooves 104 are shown in the drawing. The bottom row will be called the first row, and the top row will be called the 25th row (the seventh row in the drawing).

[0020] Next, the wafer transfer device 10 will be described with reference to FIG. First, the wafer transfer device 10 has an EFEM 11. This EFEM 11 transfers the wafer W stored in the FOUP 101 from the FOUP 101 to the processing device 20 in a mini-environment system. The EFEM 11 includes a transfer robot 12, a transfer chamber 13, and a load port . The transfer robot 12 takes out the wafer W stored in the FOUP 101 and transfers it. The transfer chamber 13 houses the transfer robot 12. The wafer W taken out of the FOUP 101 by the transfer robot 12 is transferred to the processing device 20 via the transfer chamber 13.

[0021] The load port 14 is an interface for transferring wafers W between the FOUP 101 and the EFEM 11. The load port 14 includes a load port stand (stand) 15 and a load port door (door) 16. The stand 15 is where the FOUP 101 is placed. The door 16 is for opening and closing an opening which serves as a wafer entrance / exit (substrate loading / unloading entrance), and has a built-in latch key mechanism. When the door 16 of the FOUP 101 is closed, the inside of the transfer chamber 13 is sealed.

[0022] When the wafers W are transported from the FOUP 101 to the processing device 20, the FOUP 101 is first placed at a predetermined position on the stand 15 so that the lid 103 of the FOUP 101 faces the door 16 of the load port 14. At this time, the lid 103 of the FOUP 101 and the door 16 of the load port 14 are engaged with each other, and the lid 103 is opened after the latch key is rotated. Then, the wafers W stored in the FOUP 101 are transported to the processing device 20 by the transport robot 12. In this way, the wafers W are transported in a mini-environment manner.

[0023] As described above, since the FOUP 101 is sealed by the lid 103, for example, when the lid 103 is opened, the inside becomes negative pressure. When the inside of the FOUP 101 becomes negative pressure, outside air flows in and dust in the air enters the container body 102. Thus, when the lid 103 is opened or closed in association with the loading or unloading of the wafer W, pressure fluctuations and the inflow of dust into the container body 102 may occur.

[0024] Each component of the sealed storage container of the present invention will be described below. Fig. 1 shows a side view of the sealed storage container of the present invention (when no wafers are stored). Fig. 2 and Fig. 3 show a side view and a top view of the sealed storage container of the present invention (when wafers are stored). Fig. 2 and Fig. 3 also show the flow of outside air that flows in when the lid is opened. Here, the sealed storage container of the present invention will be described taking a FOUP type as an example, but the type is not particularly limited. It may also be a FOSB type. The airtight storage container (also called FOUP) 1 comprises a container body 2 and a lid 3. The container body is formed to be able to store multiple wafers, and has an entrance (wafer loading / unloading entrance) on the front. Wafers W can be loaded and unloaded through this opening. The lid 3 fits into the door of the load port, just like a typical FOUP, and the lid 3 can be opened and closed by a latch key mechanism.

[0025] Inside the container body 2, multiple grooves 4 are provided in the vertical direction (here, an example of 25 typical stages will be explained. Note that only seven stages are shown in the drawing for simplicity, as mentioned above), and each groove 4 can hold one wafer. Each groove is provided at equal intervals.

[0026] Up to this point, the configuration is similar to that of a typical airtight storage container (FOUP) 101, but in the airtight storage container (FOUP) 1 of the present invention, a dust adhesion prevention plate 5 having a cutout portion 6 is further arranged inside the container body 2. The dust adhesion prevention plate 5 is disposed between the uppermost (25th) groove portion 4T of the multiple groove portions 4 and the upper wall 7 of the container body 2. The dust adhesion prevention plate 5 is disposed away from the upper wall 7, leaving a space between the upper wall 7 and the plate 5. Moreover, the dust adhesion prevention plate 5 is disposed so that the cutout portion 6 is located on the side of the back wall 8 of the container body 2. That is, the cutout portion 6 and the back wall 8 are disposed so as to face each other. Even if the dust adhesion prevention plate 5 is disposed so that a part of the dust adhesion prevention plate 5 and the back wall 8 are in contact with each other, the presence of the cutout portion 6 necessarily provides a gap between them, so that the outside air flowing into the container body 2 when the lid 3 is opened is not prevented from flowing between the dust adhesion prevention plate 5 and the upper wall 7 (or the back wall 8). Also, if they are originally disposed apart without contacting each other, the cutout portion 6 allows the outside air to flow more smoothly. The cutout portion, which is a partial hole, allows the outside air flowing in to simply and effectively flow over the dust adhesion prevention plate 5, not over the uppermost wafer WT placed in the uppermost groove portion 4T. As a result, it is possible to prevent air containing dust from flowing over the top wafer WT as in the conventional case, and to prevent the dust from adhering to the top surface of the wafer WT, thereby making it possible to significantly reduce the particle level on the top surface of the wafer WT compared to the conventional case.

[0027] The method of placing or fixing the dust adhesion prevention plate 5 at the above-mentioned installation position is not particularly limited. For example, a dedicated groove for the dust adhesion prevention plate 5 may be newly provided above the 25th groove 4T on the topmost stage for placing the wafer W, and at a location spaced apart from the grooves 4 by the same distance as the distance between the grooves 4, and the dust adhesion prevention plate 5 may be placed in the dedicated groove to fix the position. Alternatively, the dust adhesion prevention plate 5 may be fixed to the inner wall of the container body 2 by adhesion or the like.

[0028] Furthermore, the shape and size of the dust adhesion prevention plate 5 are not particularly limited. For example, when the wafers W to be stored are disk-shaped wafers, the dust adhesion prevention plate 5 may be a disk-shaped plate of the same size with the notch 6 formed therein. Alternatively, the dust adhesion prevention plate 5 may be a plate having a shape that conforms to the inner wall surface of the container body 2 in a plan view with the notch formed therein. There is also no particular limitation on the shape or size of the cutout portion 6. For example, as shown in Fig. 3, the cutout portion may be a substantially rectangular cutout portion having a predetermined width along the outer periphery of the disk-shaped dust adhesion prevention plate 5. These can be appropriately determined depending on the shape and size of the container body 2 and the wafers W to be stored.

[0029] Next, in order to further illustrate the effectiveness of the FOUP 1 of the present invention, the flow of outside air (air) that flows in when wafers are stored in the FOUP 1 and the lid is opened at the load port will be described with reference to FIGS. For example, when the FOUP 1 is fully loaded with wafers W (or nearly so), the wafers W are basically placed horizontally and at equal intervals, so the outside air flows in as a horizontal flow along the wafers W. This can be broadly divided into two flows. These flows are as shown in Figure 2 when viewed from the side, and as shown in Figure 3 when viewed from above. The first flow is outside air flowing in through the gap between the upper wall (top plate) 7 of the FOUP 1 and the dust adhesion prevention plate 5 (here, a disk-shaped plate with a notch 6) disposed above the wafer WT located at the topmost stage. This first flow then flows to the back through the gap between the upper wall 7 of the FOUP 1 and the disk-shaped plate of the dust adhesion prevention plate 5, and then flows downward along the back wall 8. The second flow flows to the back through the space between the bottom wall 9 of the FOUP 1 and the wafer WB located at the bottommost stage, and then flows upward along the back wall 8.

[0030] In this manner, the dust adhesion prevention plate 5 is disposed between the uppermost groove 4T (uppermost wafer WT) and the upper wall 7, where there is a relatively large space, with the cutout 6 facing the rear wall 8, so that the incoming outside air can pass extremely smoothly over the dust adhesion prevention plate 5. This makes it possible to reduce adhesion of dust caused by the inflow and contact of outside air on the upper surface of the uppermost wafer WT, which occurred in the past. Even if some plate-like member is disposed in a similar position instead of the dust adhesion prevention plate 5, if there is no notch 6 as described above, there is a risk that it will be difficult for outside air to flow to the rear wall 8 in the gap between the upper wall 7 and the plate-like member and further downward along the rear wall 8. In this case, outside air will also easily flow into the gap below, i.e., the gap between the plate-like member and the uppermost wafer WT, and dust will easily adhere to the top surface of the wafer WT. On the other hand, in the present invention, since the cutout portion 6 is provided as described above, it is possible to prevent such problems from occurring.

[0031] It should be noted that the above describes the effect of opening the lid 3 when removing the wafer W from the FOUP 1, but this is not limited thereto. Conversely, dust adhesion can be similarly prevented when removing the wafer W from the FOUP 1 or when the lid 3 is closed. EXAMPLES

[0032] The present invention will be described in more detail below with reference to examples and comparative examples of the present invention, but the present invention is not limited to these. Various FOUPs in the examples and comparative examples described below were fully loaded with wafers (25 wafers stored), and the FOUP lid was opened using the load port of a wafer transfer device as shown in FIG. 5, and the top surface of the topmost wafer (the 25th wafer) was evaluated for dust adhesion. (Example) A FOUP of the present invention similar to that shown in Fig. 1 was prepared. This has a disk-shaped dust adhesion prevention plate (with the cutout facing the back wall of the container body) above the wafer (groove) located at the top of the container body. Wafers are placed in all the grooves from top to bottom.

[0033] (Comparative Example) A conventional FOUP similar to that shown in FIG. 7 was prepared. In other words, above the wafers located at the top of the container body, no disk-shaped plate like the dust adhesion prevention plate of the present invention was provided. Other than that, it was the same FOUP as in the embodiment. Wafers were placed in all the grooves from top to bottom.

[0034] (result) To evaluate dust when opening and closing the lid of the sealed storage container FOUP of the Example and Comparative Example, 25 polished wafers with a diameter of 300 mm were stored in each container, and the lid was opened and closed 100 times, and the number of particles of 46 nm or more in size was measured for the topmost wafer (the 25th wafer) using a KLA particle counter SP2. The particle counts were then normalized and compared between the Example and Comparative Example. As shown in Fig. 4, the particle level on the top surface of the topmost wafer (the 25th wafer) in the Example was about 0.5, whereas in the Comparative Example it was nearly double that, at about 1. Since the Example was significantly lower than the Comparative Example, it was found that the disk-shaped plate (with a notch) of the dust adhesion prevention plate arranged on the upper side, like the sealed storage container of the present invention, has a significant effect of suppressing the adhesion of dust.

[0035] In the case of the embodiment, as shown in FIGS. 2 and 3, it is believed that the influence of dust on the uppermost wafer due to the first flow could be prevented. On the other hand, in the comparative example, as in the state in which wafers are stored in Figures 8 and 9, the first flow comes into contact with the top surface of the wafer located at the top of the container body, which is thought to be the cause of the influence of dust.

[0036] The present invention is not limited to the above-described embodiment. The above-described embodiment is merely an example, and any configuration that is substantially the same as the technical idea described in the claims of the present invention and that provides similar effects is included in the technical scope of the present invention. [Explanation of symbols]

[0037] 1... airtight storage container (FOUP) of the present invention, 2... container body, 3...Cover; 4...Groove; 4T...Topmost groove; 5...Dust adhesion prevention plate; 6...cutout portion; 7...upper wall; 8...rear wall; 9...lower wall; 10...wafer transfer device, 11...EFEM, 12...transport robot, 13...transport room, 14...load port, 15...load port stand, 16...load port door, 20...processing device, 101...General airtight storage container (FOUP), 102...Container body, 103...Lid, 104...Groove, W...wafer, WT...top wafer, WB...bottom wafer.

Claims

1. A sealed storage container having a container body for storing wafers and a lid for opening and closing an opening of the container body, Inside the container body, The groove portion in which the wafer is placed and stored is provided in a plurality of stages in the vertical direction, a dust adhesion prevention plate (excluding a plate having a slot in its surface) is placed in a dedicated groove between the topmost groove of the plurality of grooves and the upper wall of the container body, and is fixed in position by being spaced apart from the upper wall; The dust adhesion prevention plate has a cutout portion, and is placed so that the cutout portion is located on the inner wall side of the container body.

2. 2. The sealed storage container according to claim 1, wherein the dust adhesion prevention plate is a disk-shaped plate having the cutout portion.

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