Abstract:
Light scattered from illuminated spot on a patterned wafer is first passed through a di-electric filter and then by an optical fiber bundle to a detector. The di-electric filter controls the aperture of the light that is passed to a desired azimuth angle and the optical fiber further limits the aperture.
Abstract:
The invention relates to the assessment of the presence or absence of contaminating materials It relates to a method in which the locations (39) to be studied are successively illuminated at the surface of an electrically conducting material (33), this illumination stimulating the photoelectric emission of material below each location. An electron collector device (41) measures the photoelectric current, and another electron collector (49), placed at a distance, makes it possible to compensate for the capacitive effects existing between the surface of the conducting material (33) and the first collector device (41). Application to the analysis of the surfaces of semiconductor wafers during the manufacture of integrated circuits.
Abstract:
Methods for determining the presence or absence of, and the thickness or other spacial extent of, a contaminant layer at each of a plurality of two or more sites on the surface of an electrically conductive material such as a semiconductor, a metal or a metal silicide. The invention uses a change in photoemission current from an illuminated spot on the surface to determine the presence and extent of a contaminant layer at the illuminated site. Compensation is provided for the effects of capacitive current and photovoltaic current. The invention provides a pattern of illumination sites on the conductor surface that can, if desired, cover all points on the surface.
Abstract:
Light scattered from an illuminated spot (54) on a patterned wafer (56) is first passed through a dielectric filter (74) and then through an optical fiber bundle (76) to a detector (72). The filter (74) controls the aperture of the light that is passed to a desired azimuth angle and the optical fiber bundle (76) further limits the aperture.
Abstract:
A method of locating particle and defect features on a periodically patterned surface (16) uses multiple threshold intensity levels to identify features in the data stream produced by scanning the surface with a light beam (12) and detecting the light scattered (22) from the surface. High thresholds are assigned to regions of the surface with high background scatter, while low thresholds are assigned to regions of the surface with low background scatter. The scattered light (22) is detected with a wide dynamic range detector producing high resolution 12-bit pixel data capable of resolving the smallest particles and defects of interest in low scatter regions, while avoiding saturation in high scatter regions. Periodic pattern features (56) are removed from the data by mapping features from a plurality of periodically repeating die on the surface to a single die map and looking for overlapping features.
Abstract:
A stylus profilometer having a counterbalanced stylus with a motion transducer using a vane (41) moving between parallel, spaced-apart, conductive plates (35 and 37) which damp the motion of the vane by means of trapped air. The vane forms an electrode with the plates so that the combination is a pair of capacitors in a balanced bridge arrangement. Motion of the stylus causes an unbalance of the bridge indicative of the extent of stylus motion. A lever arm (59) associated with the stylus has a tip (57) influenced by a magnetic field which biases the stylus or controls force on a surface to be measured. The entire assembly has a very low moment of inertia to reduce the effects of vibration on the stylus and thereby increase resolution of the device and reduce damage to the substrate.
Abstract:
In an optical scanning system (200) for detecting particles and pattern defects on a sample surface (240), a light beam (238) is focused to an illuminated spot on the surface and the spot is scanned across a scan line. A detector (11b) is positioned adjacent to the surface to collect scattered light from the spot where the detector includes a one- or two-dimensional array of sensors. Light scattered from the illuminated spot at each of a plurality of positions along the scan line is focused onto a corresponding sensor in the array. A plurality of detectors symmetrically placed with respect to the illuminating beam detect laterally and forward scattered light from the spot.
Abstract:
A high sensitivity and high throughput surface inspection system directs a focused beam of light (38) at a grazing angle towards the surface to be inspected (40). Relative motion is caused between the beam (38) and the surface (40) so that the beam (38) scans a scan path covering substantially the entire surface and light scattered along the path is collected for detecting anomalies. The scan path comprises a plurality of arrays of straight scan path segments. The focused beam of light (38) illuminates an area of the surface between 5-15 microns in width and this system is capable of inspecting in excess of about 40 wafers per hour for 150 millimeter diameter wafers (6-inch wafers), in excess of about 20 wafers per hour for 200 millimeter diameter wafers (8-inch wafers) and in excess of about 10 wafers per hour for 300 millimeter diameter wafers (12-inch wafers).
Abstract:
A test device for calibrating an optical scanner wherein microscopic patterns (21) of light scattering elements (13, 15) simulate the scattering of light from particles or flaws of different sizes. Simulation of different particles sizes is achieved by means of clusters (25, 29, 33, 37) or arrays of these light scattering elements having different areawise densities. Patterns of such clusters or arrays are disposed on a surface with intervening spaces (17) where a random assortment of foreign particles may be expected. In this manner, the foreign particles may be directly compared to a test pattern. The test surface may be a semiconductor wafer (41) having a thin, inert coating with openings (45) therein forming the light scattering elements. The openings may be made by photolithographic techniques, i.e., masking and etching, so that various patterns on a surface may be all created simultaneously by the same process.