Nikon Corporation

Nikon Research Corporation of America

Other

Nikon Precision Incorporated

Verity Instruments, Inc.

Applejack 199 L.p.

Arun Ananth Aiyer

Henry K Chau

Kyoichi Suwa

Mark Anthony Meloni

Paul Derek Coon

John H McCoy

Andrew Weeks Kueny

Kenneth C Harvey

Bernard Fay

Henry Kwok Pang Chau

A sensor device which is adapted for detecting target molecules in-vitro and in-vivo, comprises a MIR source emitting in 2 um to 10 um range for exciting the target species and a probe beam with orthogonal polarizations and split frequencies in the KHz. to MHz range. The probe beam measures the effects of specie concentration change and of its excitation. The evanescent fields of the orthogonally polarized beams in the probe beam undergo differential phase shifts when target species concentration changes in epidermis or when its refractive index changes due to photo-thermal excitation by the MIR beam. The phase shift is directly proportional to concentration change and refractive index change and are measured using a heterodyne interferometer operating at the same frequency as the split frequency. The measured phase shift can be related to specie concentration change in target volume.

Optical device for non-invasive continuous monitoring of blood glucose level and HbA1c concentration

A sensor device which is adapted for detecting target molecules in-vitro and in-vivo, comprises a MIR source for exciting the target species and a probe beam with split frequency to measure the effect of excitation. The latter uses a heterodyne interferometer operating at a beat frequency &#x2dc; KHz. to MHz. The photo-thermal excitation of target species leads to refractive index change. The RI change produces probe beam displacement and is measured using a 1) grating heterodyne interferometer, 2) grating deflection amplifier and 3) evanescent field heterodyne interferometer. The measured RI change can be related to specie concentration change in target volume. Furthermore, a sensing method for detecting HbA1c concentration and its change with thermal excitation is described in terms of phase shift of the OCT spectrum obtained with spectral domain optical coherence tomography (SD-OCT).

A sensor device which is adapted for detecting target molecules having a target nucleic acid sequence located in nano/micro channels, comprises a THz source for exciting the target molecules and a heterodyne interferometer, having a detection frequency MHz, for probing the excited molecules. The nano-channel array in the sample holder is functionalized with electric field to linearize the target alleles and genes. The linearized molecules are exposed to THz field whereby the different vibrational modes of base pairs are resonantly excited. The excitation of base-breathing mode and base-shifting mode leads to differential induced dipole moments along and perpendicular to the double helix axis. This induced asymmetry in polarizability leads to optical anisotropy. The dipole-dipole interaction between adjacent bases affects polarizability along the helix axis and hence the intrinsic molecular anisotropy is a function of number of base pairs in the strand. The resulting birefringence can be measured using the heterodyne interferometer as a function of changes in the number of base pairs in the strand. Furthermore, a sensing method for detecting birefringence in terms of phase shift of the MHz signal, as a function of target molecule size, is described.

Sensor device and method for label-free detection of double strand nucleotides

A system and method of measuring feature depth using a common path auto-correlation low coherence interferometer including a light source having an output directed toward a first beam splitter, the first beam splitter directing at least a portion of a light beam from the light source toward a sample having two reflective interfaces including a top surface reflective interface and a feature bottom reflective interface. The first beam splitter can also pass toward a second beam splitter each of a reference light beam reflected from the top surface interface and a measurement light beam reflected from the feature bottom reflective interface. The second beam splitter directs the reference light beam to a first mirror and the measurement light beam to a second mirror and combines a reflected measurement light beam from the second mirror and a reflected reference light beam from the first mirror to form an interference pattern.

Method and system for measuring patterned substrates

A self referencing heterodyne reflectometer is disclosed which rapidly alternates between a heterodyne reflectometry (HR) mode, in which an HR beam comprised of s- and p-polarized beam components at split angular frequencies of &#x3c9; and &#x3c9;+&#x394;&#x3c9; is employed, and a self referencing (SR) mode, in which an SR beam comprised of p-polarized beam components at split angular frequencies of &#x3c9; and &#x3c9;+&#x394;&#x3c9; is employed. Alternatively, in SR operating mode the SR beam is replaced by a p-polarized amplitude modulated (AM) beam, operating at two modulated amplitudes of &#x3b1; and &#x3b1;+&#x394;&#x3b1; at a single frequency, &#x3c9;'. When the two measurements are made in rapid succession, using an optical chopper switcher, temperature induced noise in the detector is be assumed to be equivalent. Film phase shift information is derived from the measured phase shift &#x3b4;, generated from the HR beam, and the reference phase shift &#x3b4;, generated from the SR/AM beam, which are used for calculating film thickness.

Self referencing heterodyne reflectometer and method for implementing

The present invention is directed to a self referencing heterodyne reflectometer system and method for obtaining highly accurate phase shift information from heterodyned optical signals, without the availability of a reference wafer for calibrations. The self referencing heterodyne reflectometer rapidly alternates between a heterodyne reflectometry (HR) mode, in which an HR beam comprised of s- and p-polarized beam components at split angular frequencies of &#x3c9; and &#x3c9;+&#x394;&#x3c9; is employed, and a self referencing (SR) mode, in which an SR beam comprised of p-polarized beam components at split angular frequencies of &#x3c9; and &#x3c9;+&#x394;&#x3c9; is employed. When the two measurements are made in rapid succession, temperature induced noise in the detector is be assumed to be the same as for both measurements. A measured phase shift &#x3b4;is generated from the HR beam and a reference phase shift &#x3b4;is generated from the SR beam. The measured phase shift &#x3b4;generated from the beat signals of the HR beam is used for film thickness measurements. The SR beam is p-polarized and no significant reflection will result from a film surface and will not carry any phase information pertaining to the film. The reference phase shift &#x3b4;generated from the beat signals of the SR beam is equivalent to that obtained using a reference sample. Film phase shift information is then derived from the measured phase shift &#x3b4;and the reference phase shift &#x3b4;which is independent of phase drift due to temperature. Film thickness is calculated from the film phase shift information.

Non-imaging measurement is made of misalignment of lithographic exposures by illuminating periodic features of a mark formed by two lithographic exposures with broadband light and detecting an interference pattern at different wavelengths using a specular spectroscopic scatterometer including a wavelength dispersive detector. Misalignment can be discriminated by inspection of a spectral response curve and by comparison with stored spectral response curves that may be empirical data or derived by simulation. Determination of best fit to a stored spectral curve, preferably using an optimization technique can be used to quantify the detected misalignment. Such a measurement may be made on-line or in-line in a short time while avoiding tool induced shift, contact with the mark or use of a tool requiring high vacuum.

Automated overlay metrology system

The present invention is directed to a heterodyne reflectometer system and method for obtaining highly accurate phase shift information from heterodyned optical signals, from which extremely accurate film depths can be calculated. A linearly polarized light comprised of two linearly polarized components that are orthogonal to each other, with split optical frequencies, is directed toward a film causing one of the optical polarization components to lag behind the other due to an increase in the optical path in the film for that component. A pair of detectors receives the beam reflected from the film layer and produces a measurement signal, and the beam prior to incidence on the film layer and generates a reference signal, respectively. The measurement signal and reference signal are analyzed by a phase detector for phase shift. The detected phase shift is then fed into a thickness calculator for film thickness results. A grating interferometer may be included with the heterodyne reflectometer system with a grating, which diffracts the reflected beam into zeroth- and first-order bands, which are then detected by separate detectors. A detector receives the zeroth-order beam and generates another measurement signal. Another detector receives the first-order beam and generates a grating signal. The measurement signal from the grating and reference signal may be analyzed by a phase detector for phase shift, which is related to the thickness of the film. Conversely, either measurement signal may be analyzed with the grating signal by a phase detector for detecting a grating phase shift. The refractive index for the film may be calculated from grating phase shift and the heterodyne phase shift. The updated refractive index is then used for calculating thickness.

Heterodyne reflectometer for film thickness monitoring and method for implementing

An optical profilometer apparatushaving a stage with a support surfaceon which a wafer substrate may rest. The wafer stage is capable of moving the wafer in (x, y) or (r, &#x3b8;) mode to achieve complete wafer scan. Polarized light from a monochromatic sourceis directed towards the wafer surface. Surface profiling is achieved by sensing beam shift on a segmented sensor caused by level/height change at the wafer surface. In preferred embodiment of the profilometer, a single light beam is engineered to propagate in two orthogonal planes of incidence so that it becomes sensitive to height/level change on the wafer while being insensitive to local slope or wafer tilt. In another embodiment, slope of surface feature is measured. By integrating slope over the measurement spot, local feature height is obtained. This is particularly useful when the beam shift due to feature height change is below detection sensitivity. Since the beam propagates in two orthogonal planes of incidence, the slope measurement sensitivity and hence height sensitivity is doubled. The entire wafer surface can be profiled using (x, y) or (r, &#x3b8;) scan of the wafer surface.

Non-contact optical profilometer with orthogonal beams

An alignment simulation method simulates the signal waveform for an alignment mark using various alignment methods as well as the signal strength for an alignment mark, which is useful in optimizing the thickness of one or more layers as well as the geometry of the mark. The simulation of signal strength is also useful in optimizing the thickness of a layer for artifact wafers. The alignment simulation method includes accurately modeling the alignment mark, including one or more layers of various thicknesses and materials. The accurate modeling of the alignment mark includes such things as smoothing regions of the alignment mark and generating lateral shifts of the layers. The model of the alignment mark is a series of small pixels, each including the thickness of the layers and the layers indices of refraction. Using scalar diffraction, a complex reflectivity is generated for each pixel and a fast fourier transform is performed on the series of pixels. The results of the fast fourier transform are used to simulate the diffraction intensities for the alignment mark alignment systems, such as LIA or LSA as well as the signal waveforms. The LSA signal waveform, however, requires additional modeling of the alignment mark. An FIA image is generated by removing appropriate orders from the fast fourier transform result and performing an inverse fast fourier transform and repeating the process at different light wavelengths and illumination angles. The signal strength is the maximum value of the image minus the minimum.

Alignment simulation

A wafer inspection apparatus having a stage with a support surface on which a wafer substrate may rest. The wafer stage is capable of moving the wafer in (x, y) or (r, &thgr;) mode to achieve complete wafer scan. Polarized light from a monochromatic source is directed towards the wafer surface . The state of polarization of the beam entering PBS is either s- or p- or circular depending on the exemplary embodiment of the invention. Alternatively, both s- and p-polarization components are simultaneously present with the optical frequency of one of them shifted by &Dgr;f with respect to the other. The reflected light is sensed by detector(s) or and . A processor in communication with the detector(s) can generate image of the wafer surface based on reflectance data from a plurality of points generated via wafer (r, &thgr;) scan. The polarizing beam splitters (PBS) and along with the turning mirrors through are configured such that every ray from the source that is directed toward PBS is propagated in two orthogonal planes of incidence. In another exemplary embodiments, two images of the wafer surface taken simultaneously with two counter propagating beams and processed to enhance defect signal while suppressing geometry generated background noise. Current invention also provides for normal illumination of the wafer surface along with off-axis illumination. Dark field inspection can also be implemented in anyone of the described exemplary embodiments by locating off-axis detectors . Other embodiments describe phase-image inspection of wafer surface for detecting those defects that are insensitive to dark field or bright field inspection using two phase images that are 180&deg; apart in phase.

Wafer inspection apparatus with unique illumination methodology and method of operation

An apparatus and method for conditioning a pad used for chemical-mechanical planarization (CMP) are provided, that allow the conditioning to be performed in situ without stopping the polishing. A retractable pad-conditioning structure, e.g., conditioning tips, is positioned along the bottom perimeter of a wafer carrier. While polishing a surface of a wafer held in the middle of the wafer carrier, whenever the removal rate drops below a permissible value, the pad-conditioning structure, which rotates in unison with the wafer carrier, is lowered to contact the pad to condition the pad's surface. Since an area of the pad used for polishing the wafer is always surrounded by already conditioned pad areas and the area for polishing moves as the wafer carrier moves around on the pad surface, a substantially uniform removal rate is maintained. When the pad is sufficiently conditioned, the conditioning structure is retracted until the pad needs to be conditioned again.

In-situ pad conditioning apparatus for CMP polisher

In-situ pad conditioning for CMP polisher

A CMP heterodyne in-situ sensor (C-HIS) system utilizes optical heterodyne interferometry. A wafer undergoing CMP is illuminated through the wafer thickness using an infrared laser beam at a wavelength of 1.1 &mgr;m or greater. The beam is transmitted through the wafer and is reflected from the front wafer surface. As the wafer is polished, the optical beam path through the wafer is shortened, causing the reflected optical frequency to undergo a Doppler shift. By measuring this shift, the change in wafer thickness is determined. The frequency shift generates a signal, which enables dynamic process control. In embodiments where the wafer includes a planarization film, the frequency shift provides a measurement of changing film thickness. Embodiments of the invention utilize phase detection independent of intensity, and hence do not suffer from intensity fluctuations. Some embodiments detect thickness changes less than 2.5 nm. C-HIS sensors operate in both polished-to-thickness and polished-to-stop scenarios.

Heterdoyne Thickness Monitoring System

In a CMP method and apparatus an essentially circular polishing pad is mounted on a rotating platen. A region of the polishing pad is thinned to provide enhanced optical transparency. A portion of the platen underlying the thinned pad region is also transparent. The thinned pad and the transparent platen portion provide optical access to the surface of a wafer for in-situ process monitoring. Input signals from optical monitoring instruments enable dynamic process control.

Growing community of inventors

Fremont, CA, United States of America

Arun Ananth Aiyer