Closed container to be used in a clean room

Abstract: Disclosure is a closed container used in a clean room in a semiconductor manufacturing system which eliminates the difficulty that it is necessary to convey a container to an inert gas purge station to supplement it with the inert gas. In the closed container which accommodates wafers in an inert gas atmosphere, and is conveyed from one processing device to another in a semiconductor manufacturing system; in which, a gas passageway is formed in the container in such a manner that one end thereof is open inside the container and the other end is open outside the container, and a portable inert gas bomb is detachably connected to the other end of the gas passageway, to supplement the container with the inert gas.

Description: This invention relates to a closed container. Such a container is, for example, used in a semiconductor manufacturing system in a clean room for manufacturing semiconductor wafers, liquid crystal display boards, reticles, disks, etc. A closed container to be used in a clean room is already known from European Patent Application 509 256, whose priority date is before that of the present application but whose publishing date is after the priority date of the present application. Such a closed container comprises a gas supply passage and an inert gas cylinder detachably connected to the gas passageway to supply the container with inert gas. The gas flow through the passage into the closed container is regulated by means of a supply valve (which is separate from the gas cylinder) by an electronic controller in order to allow a very specific procedural timing schedule. One example of a semiconductor manufacturing system of this type is as shown in FIG. 3. In FIG. 3, reference numeral 1 designates a surface treatment device incorporating a surface treatment furnace for giving surface treatment to semiconductor wafers, the device 1 having two ports (described later) arranged in parallel; 2, a wafer inspecting equipment; 3, a self-running type positioning robot; 4, a wafer storehouse; 4A, the apron of the wafer storehouse 4; 5, a wafer washing device; and 6, a linear motor conveyor. FIG. 4 is a sectional view showing a part of the aforementioned surface treatment device 1. In FIG. 4, reference numeral 10 designates a closed container with an opening 11 which is sealingly closed through a seal 12 with a lid 13. The lid incorporates an automatic locking mechanism (not shown) with a rod 14. The rod 14 is moved back and forth, so that its end is engaged with the opening 11 of the container 10. Further in FIG. 4, reference numeral 15 designates a wafer cassette, in which a plurality of semiconductor wafers W (for instance twenty-five semiconductor wafers W) are set one above another. The wafer cassette 15 is set in the container 10 when conveyed. FIG. 4 shows the container 10 including the wafer cassette 15 which container is placed on a plate 16 of the surface treatment device 1. The plate 16 forms the above-described port (or cassette taking-in-and-out port) 16A. The container 10 is locked onto the plate 16 with lever-type locking mechanisms 17, and thereupon the self-locking mechanism of the lid 13 is released. The wafer cassette 15 together with the lid 13 is placed on the stand 18A of a lift 18 and moved downwardly, and then onlv the wafer cassette 15 is conveved to the surface treatment furnace (not shown) by the conveyor (not shown). After the surface treatment of the semiconductor wafers has been accomplished, the wafer cassette 15 is moved back to the lid 13 set on the lift stand 18A. Thereafter, the lift stand 18A is moved upwardly, so that the wafer cassette 15 is brought into the container 10. Under this condition, the lid 13 is locked; that is, the container 10 is closed with the lid 13 thus locked. The container 10 thus closed is moved into the wafer storehouse 4 through the apron 4A by the robot 3. In the wafer storehouse 4, a stacking crane 7 is operated to set the container 10 at a predetermined position on a shelf specified by a central control device (not shown). Semiconductor wafers or the like should be free from dust. Therefore, a semiconductor manufacturing process is carried out in a clean room having a clean atmosphere, and heretofore the wafer cassette 15 is not covered when conveyed from one processing device to another. However, as the integration of semiconductor circuits is improved, the wafer cassette 15 is handled as follows: That is, the wafer cassette 15 is set in the closed container 10 before moved between processing devices. In addition, the closed container 10 is filled with inert gas, to suppress the formation of natural oxide films on the semiconductor wafers. The container is held closed. However, if it is left for a long time after filled with an inert gas such as N 2 gas, the gas leaks gradually, so that the density of N 2 gas in the container is decreased. Therefore, in the case where it is required for the container to have a high purity N 2 gas atmosphere, or the container is held in the storehouse for a long time, it is necessary to supplement the container with the gas. For this purpose, the container is conveyed to the N 2 gas purge station every predetermined period of time, and gas-purged. This makes the system intricate in operation. Accordingly, an object of this invention is to eliminate the above-described difficulty accompanying a conventional closed container. More specifically, an object of the invention is to provide a closed container used in a clean room which has a gas supply source detachably connected to it, and is therefore free from the difficulty that it is necessary to convey the container to the N 2 gas purge station to supplement it with N 2 gas. This object is met by features of claim 1. When the leakage of gas from the container advances; that is, when the internal pressure of the container is decreased to a predetermined value, the N 2 gas bomb automatically supplements the container with the N 2 gas. FIG. 1 is a sectional view showing one embodiment of this invention; FIG. 2 is an enlarged sectional view showing essential components of the embodiment; FIG. 3 is a perspective view showing the arrangement of one example of a semiconductor manufacturing system; and FIG. 4 is a sectional view of showing a part of a surface treatment device in the semiconductor manufacturing system. One embodiment of this invention will be described with reference to the accompanying drawings. In FIG. 1, reference numeral 20 designates a gas supply source, namely, a portable small N 2 gas bomb. A container 10 has a flange 10A, in which a small gas passageway 31 is formed in such a manner that its one end 31A is opened in the upper surface of the flange 10A, and the other 31B is opened in the inner surface of the container 10. A filter 32 is provided at the other end 31B of the gas passageway 31. The N 2 gas bomb 2C has a nozzle 21 with a pressure reducing valve 22, from which a gas supply pipe 23 is extended. The gas supply pipe 23, as shown in FIG. 2, is threadably engaged with the gas passageway 31 at the one end 31A. In FIG. 2, reference numeral 33 designates a control valve urged by a spring 34. At an N 2 gas purge station or the like, the closed container 10 thus constructed is gas-purged and filled with N 2 gas to a pressure slightly higher than the atmospheric pressure. In the case where the container 10 is left set on the shelf in the wafer storehouse in FIG. 3, the leakage of gas advances with time, and the internal pressure in the container is therefore decreased. If the pressure in the container 10 is decreased, for instance, to the atmospheric pressure, the valve 33 is moved downwardly against the elastic force of the spring 34; that is, it is moved away from the opening 23A of the gas supply pipe 23. As a result, the N 2 gas is jetted from the N 2 gas bomb 20 into the gas passageway 31 while its pressure being reduced to a value higher than the atmospheric pressure by the pressure reducing valve 22. The N 2 gas thus jetted runs into the container 10 through the other end 31B of the gas passageway 31, thus increasing the density of N 2 gas in the container 10. As was described above, when the leakage of gas from the container 10 advances; that is, when the internal pressure of the latter 10 is decreased to a predetermined value, the N 2 gas bomb 20 automatically supplements the container 10 with the gas. This eliminates the troublesome work that the container 10 is conveyed to the N 2 gas purge station periodically, and it is supplemented with N 2 gas. As was described above, the inert gas bomb is held connected to the container to supplement the latter with the inert gas. Hence, the purity of inert gas in the container is automatically maintained high at all times. Therefore, it is unnecessary to convey the container to the gas purge station to supplement it with the gas, which will decrease the load of the semiconductor manufacturing system as much.

Claims: A closed container (10) which accommodates wafers (W) in an inert gas atmosphere and is conveyed from one processing equipment to another in a semiconductor manufacturing system, having a gas communicating unit (31,31A,31B) formed in the container (10) in such a manner that a first end (31A) thereof is open inside the container and a second end (31B) is open outside the container, a portable inert gas bomb (20) detachably connected to the second end (31B) of the gas communicating unit to supplement the container (10) with the inert gas, and said portable inert gas bomb (20) having a control valve (33) urged to move against an elastic force of a spring (34) thereby allowing a gas flow from the portable inert gas bomb (20) into the gas communicating unit (31,31A,31B), if the pressure in the container (10) is decreased to a predetermined value. A closed container as claimed in claim 1, wherein said gas communicating unit (31,31A,31B) includes a filter (32) provided at the first end of said gas communicating unit.

Inventors: HAYASHI MITSUHIRO, KAWANO HITOSHI, MORITA TERUYA, MURATA MASANAO, OKUNO ATSUSHI, TANAKA TSUYOSHI, TSUDA MASANORI, YAMASHITA TEPPEI, HAYASHI, MITSUHIRO, KAWANO, HITOSHI, MORITA, TERUYA, MURATA, MASANAO, OKUNO, ATSUSHI, TANAKA, TSUYOSHI, TSUDA, MASANORI, YAMASHITA, TEPPEI, Hayashi, Mitsuhiro, c/o Ise Works of, Kawano, Hitoshi, c/o Ise Works of, Morita, Teruya, c/o Ise Works of, Murata, Masanao, c/o Ise Works of, Okuno, Atsushi, c/o Ise Works of, Tanaka, Tsuyoshi, c/o Ise Works of, Tsuda, Masanori, c/o Ise Works of, Yamashita, Teppei, c/o Ise Works of
Applicants: SHINKO ELECTRIC CO LTD, SHINKO ELECTRIC CO. LTD.
Application year: 1993
Main classification: H01L21
IPC codes: B65D81, B65D85, H01L21, B65G49, B65D88, F24F7