Patent Number: 051704188
Section: summary

FIELD OF THE INVENTION AND RELATED ART This invention relates to an X-ray exposure apparatus and, more particularly, to an X-ray exposure apparatus for executing exposure by using synchrotron orbital radiation light (hereinafter "SOR light"). In another aspect, the invention is concerned with a semiconductor processing method which uses such an X-ray exposure apparatus. An X-ray exposure apparatus for executing exposure by using SOR light includes a synchrotron radiation device for producing the SOR light. The synchrotron radiation device is maintained in an ultra high vacuum, and an exposure chamber for accommodating a mask or a wafer is coupled to the synchrotron radiation device by means of a beam line. In an X-ray exposure apparatus of such a structure, there is a possibility that if leakage occurs in the beam line or the exposure chamber an atmospheric gas enters the synchrotron radiation device. In an attempt to avoid this, an arrangement such as shown in FIG. 5 has been proposed (Japanese Laid-Open Patent Application No. Sho 64-61700). SOR light 501 produced by a synchrotron radiation device (not shown) goes along a beam line 503 and through a window material 507, provided on the beam line 503, and irradiates a mask 512 and a wafer 511 placed in an exposure chamber 503. The beam line is equipped with a shock wave delay tube 502, for retarding advancement of shock waves resulting from vacuum leakage, and a mirror chamber 505 for expanding the SOR light 501, disposed in this order. Provided between the mirror chamber 505 and the window material 507 is a pressure sensor 506, and provided between the synchrotron radiation device and the delay tube 504 is an emergency cutoff valve 502 which is operable in response to the detection by the pressure sensor 506. The mask 515 and the wafer 511 accommodated in the exposure chamber 513 can be replaced by any one of masks 515 accommodated in a mask pre-chamber 516 and any one of wafers 511 accommodated in a wafer pre-chamber 509, respectively, with the cooperation of gate valves 514 and 510, respectively. If the window material 507 is broken as a result of leakage in the beam line 503 or in the exposure chamber 513, in response the pressure detected by the pressure sensor 512 increases and the emergency cutoff valve 502 closes to block entry of atmospheric gas into the synchrotron radiation source device. SUMMARY OF THE INVENTION In the X-ray exposure apparatus of the type described above, the pressure sensor for detecting abnormal pressure is provided at a side (upstream side) of the window material closer to the synchrotron radiation device. If, therefore, the leakage occurs in the exposure chamber, the sensor does not directly detects the leakage but it detects the same after the window material breaks. If the window material breaks, the fractions thereof scatter into the exposure chamber and the beam line. This necessitates complicated operations for recovery as well as a long time until the exposure operation starts again. It is accordingly an object of the present invention to provide an X-ray exposure apparatus by which, in an occasion where leakage occurs in an exposure chamber, protection of a synchrotron radiation device can be done without breakage of a window material. In accordance with an aspect of the present invention, there is provided an X-ray exposure apparatus, comprising: an exposure chamber to be coupled with a synchrotron radiation device through a beam line for receiving synchrotron radiation applied through a window material provided on the beam line to execute an exposure process in said exposure chamber; pressure detecting means for detecting pressure in said exposure chamber; a cutoff valve provided in a portion of the beam line between the window material and the synchrotron radiation device; a bypass having a communication valve for communicating a portion of the beam line between the window material and said cutoff valve with a portion between the window material and said exposure chamber; vacuum evacuating means for vacuum evacuating a portion of the beam line between the window material and said cutoff valve; a pump valve provided in a conduit for coupling the beam line with said vacuum evacuating means; and a controller responsive to a pressure detected by said pressure detecting means, wherein, when in the exposure operation the detected pressure represents a steady state lower than a predetermined pressure, said controller operates to open said cutoff valve and said pump valve and to close said communication valve, and wherein, when in the exposure operation the detected pressure is higher than the predetermined pressure, said controller operates to close said cutoff valve and said pump valve and thereafter to open said communication valve. A second cutoff valve may be provided in a portion of the beam line between the window material and the exposure chamber, the opening and closing being controlled in a similar way as the cutoff valve provided in a portion of the beam line between the window material and the synchrotron radiation device. The structure may be modified so that it includes only a cutoff valve in a portion of the beam line between the window material and the exposure chamber as well as the controller. If leakage occurs in the exposure chamber during the exposure operation and the detected pressure increases beyond the predetermined pressure, the cutoff valve and the pump valves are closed and, thereafter, the communication valve is opened. Since the cutoff valve is closed before the communication valve is opened, there is no possibility of entry of a gas in the exposure chamber into the synchrotron radiation device. The opening of the communication valve is effective to avoid application of a pressure to the window material and, as a result, the window material is not damaged. A vacuum pump is provided to vacuum evacuate a predetermined portion of the beam line. When the exposure operation is to be re-started, the communication valve is closed and, thereafter, the pump valve is opened so as to vacuum evacuate any gas in the exposure chamber having been entered into between the window material and the cutoff valve. After this, the cutoff valve is opened. Thus, similarly to the moment as the cutoff valve is closed, it is possible to prevent entry of the gas in the exposure chamber into the synchrotron radiation device. These and other objects, features and advantages of the present invention will become more apparent upon a consideration of the following description of the preferred embodiments of the present invention taken in conjunction with the accompanying drawings.