Ryoichi Hirano

Bio: Ryoichi Hirano is an academic researcher from Toshiba. The author has contributed to research in topics: Mask inspection & Extreme ultraviolet lithography. The author has an hindex of 15, co-authored 110 publications receiving 847 citations. Previous affiliations of Ryoichi Hirano include Topcon Corporation.

Method and an apparatus for measuring a displacement between two objects and a method and an apparatus for measuring a gap distance between two objects

Abstract: A method and an apparatus for measuring a displacement between two objects. Corresponding pairs of regions of the two objects each have at least one diffraction grating which generate two-dimensionally distributed diffracted light beams. These light beams are diffracted and caused to interfere with each other in the paired regions, whereby two-dimensionally distributed diffracted interference light beams are emitted. A light beam of a specific order is detected from each of these diffracted interference light beams, and is converted into a beat signal. The displacement is obtained in accordance with the phase difference between these beat signals.

Sample transferring method and sample transfer supporting apparatus

Abstract: A method of transferring a sample to and from a treating chamber kept in a vacuum atmosphere through a pressure regulatively preparatory chamber. The sample is contained in the sample transfer container, which is kept air-permeable by a dust filtering filter, in a cleaned atmosphere before the sample is transferred to the treating chamber. The sample transfer container is transferred into the preparatory chamber, and the inside of the preparatory chamber is evacuated to a vacuum atmosphere. The sample is then extracted from the sample transfer container in the vacuum atmosphere and is transferred into the treating chamber. Also disclosed is an apparatus for supporting the sample transferring method.

Study of EUV mask inspection technique using DUV light source for hp22nm and beyond

Abstract: EUV lithography is expected to be not only for hp 2Xnm node device production method but also for hp 1X nm node. We have already developed the mask inspection system using 199nm wavelength with simultaneous transmitted and reflected illumination optics, which utilize p-polarized and s-polarized illumination for high defect detection sensitivity, and we developed a new image contrast enhancement method which changes the digitizing rate of imaging sensor depending on the signal level. Also, we evaluate the mask structure which improve the image contrast and defect detection sensitivity. EUVL-mask has different configuration from transmitted type optical-mask. A captured image simulator has been developed to study the polarized illumination performance theoretically of our inspection system. Preferable mask structure for defect detection and possibility of miss defect detection are considered.

A mask‐to‐wafer alignment and gap setting method for x‐ray lithography using gratings

Abstract: A new optical‐heterodyne interferometry alignment and gap setting method for x‐ray lithography is developed, where the phases of beat signals are used for detection. The fact that the lateral displacement and the gap between mask and wafer can be detected independently is shown, based on the results of analysis and experiments. Two pairs of gratings are arranged as detection marks. One pair forms a window on the mask and a checkerboard grating on the wafer, while another pair forms two linear gratings at right angles to each other. Two He‐Ne laser beams with slightly different frequencies illuminate the gratings from the ±1st‐order diffraction light directions. The lateral displacement is detected by measuring the beat signal phase difference between the two (0,1)th‐order diffraction lights from two pairs of gratings. To detect the gap, the signal phase difference between the (0,1)th‐ and (1,1)th‐order diffraction lights from the pair of linear gratings is used. Better than 0.02 μm (3σ) alignment repeatability and 0.1 μm gap setting accuracy have been achieved.

Method and apparatus for aligning two objects, and method and apparatus for providing a desired gap between two objects

Abstract: A first diffraction grating is formed on a mask, and a second diffraction grating is formed on a wafer. Two light beams having slightly different frequencies interfere with each other and are diffracted as they travel through the first diffraction grating, are reflected by the second diffraction grating, and again pass through the first diffraction grating. As a result, they change into thrice diffracted light beams. The diffracted light beams are combined into a detection light beam which has a phase shift φA representing the displacement between the wafer and the mask, or a phase shift φG representing the gap between the wafer and the mask. The detection light beam is converted into a detection signal. The phase difference between the detection signal and a reference signal having no phase shifts are calculated, thus determining phase shift φA or φG. The displacement or the gap is determined from the phase shift. In accordance with the displacement or the gap, the wafer and the mask are aligned to each other, or the gap between them is adjusted to a desired value. Since the detection signal is generated from diffracted light beams, its S/N ratio is sufficiently great. Therefore, the displacement or the gap is determined with high precision. In addition, it is possible with the invention to perform the aligning of the wafer and the mask and the adjusting of the gap therebetween, simultaneously. Further, the incident light may be either circularly polarized light or non-polarized light.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

Lithographic apparatus, and device manufacturing method

Abstract: A lithographic apparatus configured to project a patterned beam of radiation onto a target portion of a substrate is disclosed. The apparatus includes a first radiation dose detector and a second radiation dose detector, each detector comprising a secondary electron emission surface configured to receive a radiation flux and to emit secondary electrons due to the receipt of the radiation flux, the first radiation dose detector located upstream with respect to the second radiation dose detector viewed with respect to a direction of radiation transmission, and a meter, connected to each detector, to detect a current or voltage resulting from the secondary electron emission from the respective electron emission surface.

Method and apparatus for angular-resolved spectroscopic lithography characterization

Abstract: An apparatus and method to determine a property of a substrate by measuring, in the pupil plane of a high numerical aperture lens, an angle-resolved spectrum as a result of radiation being reflected off the substrate. The property may be angle and wavelength dependent and may include the intensity of TM- and TE-polarized radiation and their relative phase difference.

Step and repeat imprint lithography processes

Abstract: The present invention is directed to methods for patterning a substrate by imprint lithography. Imprint lithography is a process in which a liquid is dispensed onto a substrate. A template is brought into contact with the liquid and the liquid is cured. The cured liquid includes an imprint of any patterns formed in the template. In one embodiment, the imprint process is designed to imprint only a portion of the substrate. The remainder of the substrate is imprinted by moving the template to a different portion of the template and repeating the imprint lithography process.

Optical translation measurement

Abstract: A method for determining the relative motion of a surface with respect to a measurement device comprising: illuminating the surface with incident illumination; detecting illumination reflected from the surface to form at least one detected signal; and determining the amount of relative motion parallel to the surface from said at least one detected signal, characterized in that said determining includes correcting for the effects of relative motion perpendicular to the surface.