JPH11238787A - Wafer stocker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wafer stocker which has few turbulences of air current in a clean room and is capable of effectively preventing the chemical contamination of the inside and improving the device characteristics of a product. SOLUTION: This wafer stocker is constituted of an air blasting means 1a, an air circulating channel 1 which is substantially airtightly closed or has part of the air replaced with outside air, a wafer storing section 3 which is interposed in the way of the air circulating channel 1 and has doors 2 which is openable. A fine particle removing section 4 which is interposed on the way of the air circulating channel 1 and eliminates fine particles in the circulated air, a chemical contaminant eliminating section 5 which is located on the way of the air circulating channel 1 and eliminates chemical contaminants in the circulated air, and a temperature maintaining mechanism 6 for suppressing the increase in temperature of the circulated air.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wafer stocker used for temporarily storing wafers in the semiconductor industry where a high degree of fine particle removal and a high degree of chemical pollutant removal are required.

[0002]

2. Description of the Related Art Conventionally, a wafer stocker for temporarily storing a wafer has been a very important facility in performing a fine processing step of a wafer in the semiconductor industry. However, in the prior art, a shelf is simply provided in a relatively high-clarity zone in a clean room, or an ULPA filter is provided on an upper portion having a clean bench structure, and only a countermeasure against particulates is performed. . There is also a case type in which a blower is built in, but this was also handled only by the above-mentioned ULPA filter.

[0003]

In the prior art as described above, an open one-pass system was basically used. Therefore, when a wafer stocker for storing a wafer carrier or a wafer carrier box is installed in a clean room, there is a drawback that the air flow emitted from the clean room disturbs the down-flow air flow. In addition, such turbulence of the airflow may cause fine particle contamination and chemical contamination.

In the prior art, even if, for example, a wafer stocker is placed in a relatively high-clarity zone in a clean room, the clean room receives various chemical contaminations. Effects of chemical pollutants, and painted surfaces as cleanroom components,
At present, gas generation from various materials other than metals such as sealing materials and HEPA filters cannot be avoided. Further, various chemicals are used in the wafer micromachining process, and although these are evacuated, a slight leak from the apparatus cannot be avoided. The chemical contaminants generated in such a clean room are enriched 10 times or more in consideration of the circulation amount and the exhaust amount of the clean room. In a wafer stocker that requires more fining space, HEPA, ULPA The most important issue was not only the removal of fine particles by the filter but also the removal of chemical pollutants. Since such chemical contaminants increase in the amount attached to the wafer stored in the wafer stocker with the passage of time, the storage time becomes short and not only hinders the work process, but also causes an It is said that the attachment of inorganic chemical contaminants to wafers degrades device characteristics of products such as ICs.

[0005] However, as described above, in the prior art, the wafer stocker is an open system and only measures against particulates by an ULPA filter. For example, a facility that employs a chemical filter for a circulation system and an introduction system in a clean room. However, at present, the various problems described above have not been solved.

[0006] Accordingly, an object of the present invention is to reduce the turbulence of the air flow in a clean room, and
An object of the present invention is to provide a wafer stocker capable of effectively preventing internal chemical contamination and improving device characteristics of a product.

[0007]

According to the present invention, there is provided a wafer stocker having an air blowing means.
A circulating air passage that is substantially sealed or partially replaced with outside air, a wafer storage unit having an openable / closable door interposed in the circulating air passage, and a circulating air passage interposed in the circulating air passage; A particulate removal unit that removes particulates in the gas, a chemical contaminant removal unit that is interposed in the circulation air passage and removes chemical pollutants in the circulation gas, and a temperature maintaining mechanism that suppresses a temperature rise of the circulation gas. It is characterized by having.

In the above structure, the circulating air passage has an inlet for outside air and an outlet for circulating gas, and replaces a part of the circulating gas with the outside air. It is preferable from the viewpoint of the effects described later that the temperature rise of the circulating gas is suppressed by the substitution with

The circulating air passage is provided at the door of the storage section so that the inside of the door is maintained at a positive pressure when the door is closed. It is preferable from the viewpoint of the effects described below.

At this time, a plurality of doors of the storage section are provided, a divided storage section corresponding to the door is provided, and a shutter capable of adjusting an opening area is provided in each door as an exhaust port. It is preferable from the point of effect.

The circulating air passage is substantially closed, and the temperature maintaining mechanism suppresses a temperature rise of the circulating gas by a cooling device interposed in the circulating air passage. Is preferable from the viewpoint of the operation and effect described below.

Preferably, the chemical contaminant removing section is a filter composed of activated carbon, an ion exchanger, an activated carbon impregnated with a chemical, or a combination thereof, from the viewpoint of the operation and effect described below.

According to the present invention, the circulating air passage is substantially sealed or partially replaced with the outside air while having the blowing means, and the circulation of the gas to the outside is performed. Since the discharge amount is small, when placed in a clean room, the air flow inside the clean room is hardly disturbed and the outside is hardly affected. In addition, since a wafer storage section is provided in a circulation air path in which a fine particle removing section for removing fine particles in the circulating gas and a chemical contaminant removing section for removing chemical contaminants in the circulating gas are provided. And chemical pollutants can be removed, and since the circulation air passage is a small volume independent space, the contact time can be increased by reducing the amount of circulation air, and the removal effect is extremely large. It will be. For example, if the circulating wind speed is
0.5m / sec which is standard for PA and ULPA filters
0.2 m / sec or less, the contact time of the gas with the filter for the above-mentioned chemical contaminants can be doubled or more. Further, since a temperature maintaining mechanism for suppressing a rise in the temperature of the circulating gas is provided, the ability to adsorb organic substances to the activated carbon filter is stabilized. As a result, the adsorbing / removing ability does not decrease. As a result, the turbulence of the air flow in the clean room is small, and
It was possible to provide a wafer stocker capable of effectively preventing internal chemical contamination and improving the device characteristics of a product.

The circulating air path has an inlet for outside air and an outlet for circulating gas, and replaces a part of the circulating gas with outside air. In the case where the temperature rise of the circulating gas is suppressed, the temperature rise of the circulating gas can be suppressed by a simple mechanism without providing a cooling device.

At this time, an exhaust port for the circulating gas is provided in the door of the storage section, and the circulating air passage is configured so that the inside of the door is maintained at a positive pressure when the door is closed. In this case, the circulating gas is exhausted from the exhaust port due to the positive pressure inside the door, so the relatively contaminated gas immediately after storing the wafer is immediately exhausted from the exhaust port, and the particulate removal unit and the chemical contamination are removed. The load on the substance removing section can be reduced. Also,
When the door is opened, the amount of exhaust from the storage section increases, as if the area of the exhaust port becomes larger, and when wafers are stored, contaminated gas near the wafer is removed by clean exhaust from the storage section. can do.

In the case where a plurality of doors of the storage section are provided, a divided storage section corresponding to the door is provided, and a shutter capable of adjusting an opening area is provided in each door as an exhaust port, the door of the storage section may be provided. Is provided, by opening and closing only necessary doors, it is possible to minimize contamination from outside air when opening the doors. In addition, since a shutter capable of adjusting the opening area is provided as an exhaust port on each door, the total exhaust amount can be adjusted, and the exhaust amount of each door can be adjusted according to the use condition of the divided storage section, thereby achieving exhaust. The above-described effects can be individually enhanced.

Further, the circulating air passage is substantially closed, and the temperature maintaining mechanism suppresses a temperature rise of the circulating gas by a cooling device interposed in the circulating air passage. Since the exhaust of the circulating gas is not substantially performed, when placed in a clean room, the air flow inside the clean room is not disturbed, and there is no adverse effect on the outside. Further, since there is no need to introduce outside air, it is possible to reduce the load on the fine particle removal section and the chemical pollutant removal section, and it is not necessary to provide a filter or the like at the outside air introduction port.

When the chemical contaminant removing section is a filter composed of activated carbon, an ion exchanger, or a chemical impregnated activated carbon, or a combination thereof, the chemical contaminants can be efficiently removed with a simple apparatus configuration. . In other words, the built-in chemical filter, that is, an activated carbon filter for removing trace volatile organic substances, and a filter composed of a positive and anion exchanger for removing trace volatile inorganic substances, can remove corresponding chemical pollutants, The same effect can be obtained for an activated carbon filter impregnated with an acid instead of an ion exchanger.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 1, the wafer stocker according to the present embodiment has an air blowing means 1a, an outside air inlet 1b and a circulating gas exhaust port 1c, and circulates a part of the circulating gas with the outside air. An air passage 1 is provided.
A temperature maintaining mechanism 6 that suppresses a rise in the temperature of the circulating gas by introducing relatively low-temperature outside air by replacement with the outside air is configured. Note that a pre-filter is provided at the outside air inlet 1b.

A chemical contaminant removing section 5 for removing chemical contaminants in the circulating gas and a particulate removing section 4 for removing fine particles in the circulating gas are provided downstream of the blowing means 1a in the circulating air path 1. , And a wafer storage unit 3 having a door 2 that can be opened and closed are sequentially interposed. An air blowing means 1a is provided below the wafer storage unit 3, and a chemical contaminant removing unit 5 and a particulate removal unit 4 are provided on the back surface of the wafer storage unit 3.

Activated carbon,
It is preferable that the filter is made of an ion exchanger, a chemically impregnated activated carbon, or a combination thereof. In particular, a combination of activated carbon and an ion exchanger is suitably used.

As the fine particle removing section 4, an ULPA filter, a HEPA filter, or the like is preferable, but an ULPA filter is suitably employed from the viewpoint of removing fine particles.

The wafer storage unit 3 is provided with a plurality of doors 2,
The divided storage section 3a corresponding to the door 2 is constituted by a partition and a shelf 3b. There is a gap between the edge of the shelf 3b on the door 2 side and the door 2, and the circulating gas that has passed through the chemical contaminant removal unit 5 and the particulate removal unit 4 passes through the divided storage unit 3a, It flows downward from the gap. The divided storage section 3a stores a wafer carrier or a wafer carrier box in which a plurality of wafers can be set.

As shown in FIG. 2, each door 2 is provided with a shutter capable of adjusting the opening area as an exhaust port 1c.
Is closed and the inside thereof is maintained at a positive pressure, so that a part of the circulating gas that has passed through the divided storage portion 3a is exhausted from the exhaust port 1c. In order to maintain the inside of the door 2 at a positive pressure, a pressure loss portion 1d such as a pre-filter is provided between the upstream portion of the blowing means 1a of the circulation air passage 1 and the wafer storage portion 3 (see FIG. 1). ). Specifically, the pressure loss portion 1d and the exhaust port 1c are adjusted so that the discharge amount is about 5% or less while maintaining the inside at a positive pressure. The shutter is a rotary type, and the door 2 is provided with a glass window 2a and a handle 2b.
Is a double door and is attached to the main body by a hinge 2c.

The members constituting the apparatus are mainly made of metal such as SUS which does not easily generate fine particles and chemical pollutants. In addition, an operation panel 7 is provided on the front surface, so that the wind force of the blowing means 1a can be adjusted and the pressure of each part can be displayed. Such a wafer stocker is usually installed in a clean room.

[Another Embodiment] Another embodiment will be described below.

(1) In the above embodiment, the circulating air passage has an inlet for outside air and an outlet for circulating gas, and replaces a part of the circulating gas with outside air. Although the mechanism has shown an example in which the temperature of the circulating gas is suppressed by replacement with the outside air, the circulating air passage is substantially sealed, and the temperature maintaining mechanism is The cooling device interposed in the circulating air passage may suppress the temperature rise of the circulating gas, and in this case, the above-described operation and effect can be obtained. In this case, for example, a cooling coil may be provided in the circulation air passage, and an intake unit is provided so that a very small amount of outside air can be introduced upstream of the blowing means in order to slightly maintain a positive pressure inside the wafer stocker. I just need.

(2) In the above embodiment, the example in which the pressure loss portion 1d is provided to maintain the inside of the door 2 at a positive pressure has been described, but instead of the pressure loss portion 1d, the pressure loss portion 1d is closed when the door 2 is opened and closed. A shutter that opens may be provided. In this case, when the door 2 is opened, the amount of gas discharged from the shutter when the door 2 is opened may be increased as a shutter that is completely or partially closed automatically. Thus, when storing the wafer, the contaminated gas near the wafer can be more efficiently removed by clean exhaust from the storage unit.

(3) In the above embodiment, as shown in FIGS. 1 and 2, the blowing means 1a, the circulation air passage 1, the chemical pollutant removing section 5,
Although the example in which the fine particle removing unit 4 and the storage unit 3 are arranged has been described, the order and arrangement thereof are not limited to those in FIGS. 1 and 2 and can be changed as appropriate according to the purpose of the present invention.

(4) In the above embodiment, an example is shown in which the outside air inlet 1b is provided below the apparatus body as shown in FIGS. 1 and 2, but the outside air inlet 1b may be provided on the ceiling. . Normal,
In the clean room, a gas with a high degree of cleanliness is supplied from above, so that with the above configuration, a gas with a higher degree of cleanliness can be introduced, and the load on the fine particle removal section and the chemical pollutant removal section can be reduced. . In addition, turbulence of the airflow from above can be reduced.

[0031]

The present invention will now be described by way of examples showing specific structures and effects of the present invention, but the present invention is not limited to these examples.

In the apparatus shown in FIGS. 1 and 2, a clean wafer stocker in which a fiber activated carbon filter and an ion exchange fiber filter are laminated on the upstream side of the ULPA filter, which is a clean air blowing surface, in the circulation system, specifically, UL.
From the upstream side of the PA filter, a wafer stocker equipped with a fiber activated carbon nonwoven fabric filter material, and a three-ply pleated filter of a strongly acidic cation exchange fiber nonwoven fabric filter material and a strongly basic anion exchange fiber nonwoven fabric filter material was prepared. The performance is shown in Table 1. Table 1 shows the effect of removing volatile inorganic substances.

[0033]

[Table 1]

Although the difference from the blank value corresponds to the concentration of each substance, as shown in the results of Table 1, the concentration of the storage shelf is considerably lower than the concentration at the inlet of the circulating blower (in the clean room). I understand.

Table 2 shows that each sampled analysis sample (sampled in a concentrating tube filled with Tenax-GR) was set in a thermal desorption apparatus and analyzed using GC-MS. The analytical value showed the amount of organic substances in terms of toluene.

[0036]

[Table 2]

As shown in the results of Table 2, it can be seen that the concentration of organic matter in the storage shelf is considerably lower than that in the circulation blower inlet (in the clean room).

As a result, the air in the clean wafer stocker becomes clear air having a removal rate of 95% or more with respect to the concentration in the clean room, which is the supply air source for both organic and inorganic substances. As a result, when a standing test was performed in a conventional wafer carrier installation shelf and in the clean wafer stocker of the present invention, the amount of organic substances attached to the wafer surface showed a reduction rate of 98% or more in the case of the wafer stocker. The reason why the reduction rate of the organic substance on the wafer surface is higher than the reduction rate of the organic substance in the wafer stocker is that the removal rate of the organic substance having a large molecular weight that easily adheres to the wafer is higher than the average removal rate.

[Brief description of the drawings]

FIG. 1 is a vertical side view showing an example of a wafer stocker.

FIG. 2 is a front view showing an example of a wafer stocker.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Circulation airway 1a Blowing means 2 Door 3 Storage part 4 Particulate removal part 5 Chemical pollutant removal part 6 Temperature maintenance mechanism

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor, Yoshiyoshi Yoshioka 2-9-1 Harashi, Otsu City, Shiga Prefecture Inside Kansai Nippon Electric Co., Ltd. (72) Inventor Hiroshi Tokunaga 2-9-1, Hararashi, Otsu City, Shiga Prefecture Within Kansai Nippon Electric Co., Ltd. Inside Takuma Co., Ltd. (72) Inventor Takumi Sakagami 2-33, Kinrakuji-cho, Amagasaki City, Hyogo Prefecture Inside Takuma Co., Ltd.

Claims (6)

[Claims] 1. A circulating air passage which is substantially sealed or partially replaced with the outside air while having an air blowing means, and a wafer accommodating in the circulating air passage and having a door which can be opened and closed. And a particulate removal unit interposed in the circulation air passage and removing particulates in the circulating gas; a chemical pollutant removal unit and a circulation gas interposed in the circulation air passage and removing a chemical pollutant in the circulation gas Wafer stocker having a temperature maintaining mechanism for suppressing a temperature rise of the wafer. 2. The circulating air path has an inlet for outside air and an outlet for circulating gas, and replaces a part of the circulating gas with outside air. 2. The wafer stocker according to claim 1, wherein the replacement suppresses a temperature rise of the circulating gas. 3. A circulating air passage is provided on a door of the storage section so that the inside of the door is maintained at a positive pressure when the door is closed. 3. The wafer stocker according to claim 2, wherein 4. A plurality of doors for the storage section, a divided storage section corresponding to the door is provided, and each door is provided with a shutter capable of adjusting an opening area as an exhaust port.
The described wafer stocker. 5. The circulating air passage is substantially sealed, and the temperature maintaining mechanism suppresses a temperature rise of circulating gas by a cooling device interposed in the circulating air passage. Item 2. The wafer stocker according to Item 1. 6. The filter according to claim 1, wherein the chemical contaminant removing section is a filter composed of activated carbon, an ion exchanger, activated carbon impregnated with a chemical, or a combination thereof.
The wafer stocker according to any of the above.