A new x-ray metrology for determining cross-sectional profile of semiconductor device pattern

We have developed a new x-ray metrology for measuring surface periodic grating of semiconductor device pattern. X-rays irradiate surface of the device area with a shallow glancing angle, which is close to the critical angle of total external reflection of the surface material. The measured x-ray diffraction pattern is reflected to the average cross-sectional profile of the grating. The pattern made from SiO 2 on Si with100 nm-pitch is analyzed by the present x-ray metrology. The obtained profile, for example, line width, height of the grating and so on are well agreed with that observed by cross-sectional transmission electron microscopy. The wavelength of x-ray that we use is 0.154093 nm and it is enough shorter than the critical length of the grating structure, even when the line width becomes 10 nm or less. Therefore, the resolution of the x-ray metrology will be maintained good enough for the analysis that will be required in the future. In addition, x-ray metrology can be measure the cross-sectional profile with nondestructively due to hightransmissivity of x-rays for the materials. Furthermore, the optical parameter of the materials for x-ray is well established, therefore, x-ray metrology is applicable for any materials of device patterns without uncertain empirical parameters.