Massachusetts Institute of Technology

Euclid E Moon

Henry Ignatius Smith

Patrick N Everett

Alberto M Modiano

An interferometric-spatial-phase imaging (ISPI) system includes a substrate wafer. An alignment configuration is permanently embedded in the substrate wafer. The alignment configuration uses a global coordinate reference system by providing a plurality of global reference marks that encompass up to the entire substrate wafer. A plurality of alignment markings is provided on a surface in close proximity to the alignment configuration for obtaining continuous six-axis control of a scanning probe tip with respect to the global coordinate reference system.

Infrared interferometric-spatial-phase imaging using backside wafer marks

An interferometric-spatial-phase imaging (ISPI) system includes a substrate wafer. An alignment configuration is permanently embedded in the substrate wafer. The alignment configuration uses a global coordinate reference system by providing a plurality of global reference marks that encompass up to the entire substrate wafer. A plurality of alignment markings is provided on a surface in close proximity to the alignment configuration for obtaining continuous six-axis control to provide positional information of a scanning probe tip or an electron beam with respect to said global coordinate reference system.

Nanometer-level mix-and-match scanning tip and electron beam lithography using global backside position reference marks

An interferometric-spatial-phase imaging (ISPI) system includes an alignment mechanism for obtaining continuous six-axis control of a scanning probe tip with respect to a coordinate system attached to a substrate. A gap detection mechanism measures tip height above a substrate and controls tip approach toward the substrate of one or more tips, as well as measures tip deflection during surface contact of the one or more tips. A plurality of complementary marks is provided for attachment to the one or more tips. A plurality of grating marks is provided to backdiffract a reflected beam from a flexible cantilever to detect high-frequency tip deflection in a compact configuration of a light source and a light detector.

Nanometer-precision tip-to-substrate control and pattern registration for scanning-probe lithography

An apparatus and method measures the gap between one substantially planar object, such as a mask, and a second planar object, such as a substrate. A gapping mark is used for measuring a gap between the first and second plates. The gapping mark includes a first grating on a first surface of a first plate, the first grating having a first uniform period in a first direction. A second grating is located on the first surface of the first plate, the second grating being adjacent to the first grating in the first direction, the second grating having a second uniform period in the first direction. The gapping mark also includes a third grating on the first surface of the first plate, the third grating being adjacent to the first grating in a second direction, the second direction being substantially orthogonal to the first direction, the third grating having the second uniform period in the first direction. A fourth grating is located on the first surface of the first plate, the fourth grating being adjacent to the third grating in the first direction.

Long-range gap detection with interferometric sensitivity using spatial phase of interference patterns

An apparatus and method of measuring the gap between one substantially planar object, such as a mask, and a second planar object, such as a substrate. The invention achieves a high degree of sensitivity, accuracy, capture range, and reliability, through a novel design of a mark located only on the mask-plate. The light is inclined to the surfaces so associated optical components do not interrupt the exposing beam used in lithography. The same optics are used as for aligning overlay. Each gapping mark on the mask-plate includes one or more two-dimensional gratings, each with period constant in the incident plane, but varying in the transverse plane. When illuminated, two images are formed of each of the two-dimensional gratings, with fringes resulting from interference between paths having traveled different distances through the gap and the mask-plate as a result of successive diffractions and reflections. Phase and geometric measurements from these images yield accurate measurement of the gap between the plates. Direct calibration, referenced to the light-wavelength, is obtained from a diffractive Michelson technique that uses a linear grating also included within the gapping mark.

Optical gap measuring apparatus and method having two-dimensional grating mark with chirp in one direction

Alignment marks on first and second plates include a plurality of periodic gratings. A grating on a first plate has a period or pitch p.sub.1 paired up with a grating on the second plate that has a slightly different period p.sub.2. A grating on the first plate having a period p.sub.3 is paired up with a grating on the second plate having a slightly different period p.sub.4. Illuminating the gratings produces a first interference pattern characterized by a first interference phase where beams diffracted from the first and second gratings overlap and a second interference pattern characterized by a second interference phase where beams diffracted from the third and fourth gratings overlap. The plates are moved until the difference between the first and second interference phases correspond to a predetermined interference phase difference. Further invention uses an interrupted-grating pattern on the second plate with certain advantages. Further advantages are obtained using a checkerboard pattern on the second plate. In addition two inventions are made for measuring gap. One method uses the same marks on the second plate as used in aligning, and the second uses no marks on the second plate, which is an advantage in some cases.

Optical interference alignment and gapping apparatus

Optical alignment apparatus having multiple parallel alignment marks

There are first and second relatively movable plates. On a face of each of the first and second plates, there are first and second alignment marks, each being a linear grating of parallel lines of uniform spatial period, the spatial periods being different from each other. There is a light source for illuminating the linear grating on the second plate through the linear grating on the first plate to produce an interference pattern. Indicia on the first or second plates indicate a periodic reference pattern having a phase. A detector is configured to detect when the spatial phase of the interference pattern and the spatial phase of said reference pattern differ by a predetermined value. A position adjustor is for adjusting the relative position of the first and second plates until the detector detects said phase difference.

Growing community of inventors

Boston, MA, United States of America

Euclid E Moon