Patent Number: 047019409
Section: summary

BACKGROUND OF THE INVENTION The present invention relates to a patterning process using an X-ray i.e., a process of X-ray lithography. In a patterning process using an X-ray, the influence of emission of a photoelectron or a Auger electron caused by absorption of the X-ray on irradiation objects must be taken into consideration. For example, when an X-ray is radiated to an electron beam resist to form a pattern, the resist is exposed to secondary electrons emitted from irradiation objects, so the pattern formed becomes bad in quality. According to Yasunao Saitoh et al, "J. Vac. Sci. Technol. B," Vol. 2, No. 1, Jan.-Mar., 1984, p. 63-p. 67, the influence of secondary electrons from a substrate is prevented by using a multi-layer resist. However, although this method is effective against the emission of secondary electrons from a substrate, it is not effective against the influence of secondary electrons emitted from a resist or mask. Besides, the multi-layer resist method is disadvantageous in that a more complicated process is required. SUMMARY OF THE INVENTION It is the object of the present invention to provide a patterning process capable of forming replicate fine patterns in high resolution. According to the patterning process of the present invention, by the using a linearly polarized X-ray, the emitting direction of secondary electrons from a substrate, resist and/or mask during radiation of the X-ray is fixed, consequently the influence of such secondary electrons is diminished. FIG. 7 shows characteristic of a photoelectron emission of K-shell electrons in the radiation of a linearly polarized X-ray. A linearly polarized incident X-ray 1 is assumed to be one in which its electric vector has a linear polarization in the direction indicated at 3. At point 4 the X-ray 1 is absorbed and a photoelectron e.sup.- is emitted. If the angle between the emitting direction 2 of the photoelectron e.sup.- and an advancing direction of the linearly polarized incident X-ray 1 is .theta. and the angle between the photoelectron emitting direction 2 as projected on a plane perpendicular to the linearly polarizd incident X-ray and the electric vector direction 3 is .phi., the probability of photoelectrons being emitted in each direction is expressed approximately as I(.theta., .phi.) .alpha. sin.sup.2 .theta. cos.sup.2 .phi.. Thus, the largest number of photoelectrons are emitted in the electric vector direction 3. In forming a pattern, therefore, a good pattern can be formed by fixing the electric vector direction 3 to a direction perpendicular to a direction in which a high accuracy is required. In other words, the patterning process of the present invention is characterized by using a linearly polarized X-ray.