Abstract: A method for detecting an anomaly on a first surface of a transparent substrate starts with providing a transparent substrate that has a reflective second surface. The method then comprises directing a radiation beam at the first surface of the substrate so that at least a portion of the radiation penetrates the substrate and strikes the reflective second surface. This radiation is reflected back as a reflected radiation beam through the first surface of the substrate. The method then comprises detecting radiation from the reflected radiation beam. This method can further comprise causing relative motion between the radiation beam and the first surface of the substrate. This method can also further comprise documenting the presence of an anomaly if the detected radiation shows that the reflected radiation beam was scattered upon traversing the first surface.

Abstract: A mark comprising at least one set of calibration periodic structures and at least two sets of test periodic structures, both types of which are positioned along an axis. The mark is used to measure the relative position between two layers of a device. Each set of test periodic structures has its periodic structures formed within first and second sections. The periodic structures of the first and second sections are each formed on one of the two layers of the device, respectively. The first and second sections of each test set is positioned proximate to the second and first sections of the next test set, respectively. This mark allows two beams which scan the mark to travel over both a test section formed on one layer of the device and a test section formed on the other of the two layers. Scanning multiple test sets provides multiple registration error values which are then averaged to obtain an average registration error value.

Abstract: The present invention is a method and apparatus that uses a microscopic height variation positioned relative to a semiconductor device to scan a target on the device to produce an electrical signal representative of height variations of first and second periodic structures of the target in a selected path across the device, and a computing and control system to provide translation between the microscopic height variation detector and the target on the device in a selected path, and to calculate any offset between the first periodic structure and the second periodic structure of the target from the electrical signals from the microscopic height variation detector. The first periodic structure of the target is on a first layer of the device, and the second periodic structure, that complements the first periodic structure, is on a second layer of the device at a location that is adjacent the first periodic structure.

Abstract: The present invention is a new target, and associated apparatus and methods, for determining offset between adjacent layers of a semiconductor device. The target disclosed here includes a first periodic structure to be placed on a first layer of the device and a second periodic structure, that complements the first periodic structure, placed on a second layer of the device at a location that is adjacent the first periodic structure when the second layer is placed on the first layer. Any offset that may occur is detected by the present invention either optically, micro-mechanically or with electron beams using any of various methods and system embodiments.

Abstract: An angle-dependent reflectometer or transmissometer includes an optical imaging array in the incident and reflected or transmitted light path that breaks up an incident light beam into mutually spatially incoherent light bundles. The individual light bundles are then focused to a common spot by a high numerical aperture objective lens so as to provide a range of incidence angles on a sample surface. In a reflectometer, reflected light returns through the objective lens and imaging array and is imaged onto a detector array where different incidence and reflection angles are received by different groups of detection elements. In the angle-dependent transmissometer, the imaging array and high numerical aperture focusing objective lens are used for illuminating a spot on the sample, with a second high numerical aperture collection objective lens and detector array used for receiving transmitted light over a wide range of collection angles.

Abstract: A plurality of sample beam wavefronts derived from selected portions of a wide-aperture outgoing optical beam wavefront enter an entrance pupil (11) located adjacent a focal surface (12) on which the sample beams are individually focussed. A relay lens system (13) transmits the sample beams to a beam splitter (14), which divides each of the sample beams into an undeviated component and a diviated component. The undeviated components of the various sample beams image the entrance pupil (11) on a first scanning mirror (15), and the deviated components image the entrance pupil (11) on a second scanning mirror (16). The focal surface (12) is reimaged by the relay lens system (13) onto focal planes (17 and 18), respectively, so that the foci of the individual sample beams appear as spots on the focal planes (17 and 18).

Abstract: A scan-shear interferometer comprises a beamsplitter (11) for dividing an optical beam into a transmitted component I and a reflected component II, which are propagated in opposite directions along a triangular portion of an optical path defined by mirrors (12) and (13) back to the beamsplitter (11), from which the beam component I is transmitted and the beam component II is reflected to a mirror (14), which reflects the beam components I and II coincidentally to form pupils on an interference plane at a photodetector device (15). A rotating prism (16) is positioned so that each of the beam components I and II makes a double pass through the prism (16) before reaching the interference plane. Rotation of the prism (16) causes the pupil formed by the beam component II to remain stationary, and causes the pupil formed by the beam component I to move across the stationary pupil along a scan axis on the interference plane.

Abstract: An apparatus is described for measuring spatial phase difference between a signal beam and a reference beam in substantially real time, where the signal and reference beams are coherent beams of optical radiation superimposed upon each other and having orthogonal polarization states with respect to each other.

Abstract: An interferometer for measuring optical surfaces which is capable of very high sensitivity. A HeNe laser light is converted into a circular polarized beam, spatially filtered and collimated. The light beam is passed through a photoelastic modulator for modulating the relative phase of the two polarization states of the optical field of the beam. The beam is then passed through a ROCHON prism which splits the beam into two orthogonally polarized components. One beam is reflected off the optical surface that is being measured and is recombined with the undeviated beam. The resulting irradiance distribution oscillates in the modulation frequency and the phase of the oscillation is dependent upon the optical path difference between the two beams. The detected interference signal is processed to extract the phase information.