Kla Tencor Corporation

Phase Shift Technology, Inc.

Kla-tencor Technologies Corporation

Shouhong Tang

Klaus Reinhard Freischlad

Yi Zhang

Jaydeep K Sinha

Haiguang Chen

Sergey Kamensky

Chunhai Wang

Andrew An Zeng

Andrew Zeng

Chunsheng J Huang

Frederick Arnold Goodman

George J Kren

Daniel Ivanov Kavaldjiev

Brian L Haas

Dieter Mueller

Steve Yifeng Cui

Romain Sappey

Jie-Fei Zheng

Enrique Chavez

An Andrew Zeng

Kibyung Seong

John Hager

Chris L Koliopoulos

Mark Plemmons

Brian Haas

Klaus Freischlad

Systems and methods for processing phase maps acquired using interferometer wafer geometry tools are disclosed. More specifically, instead of performing phase unwrapping first and then analyze the unwrapped data in a height domain, systems and methods in accordance with the present disclosure operate in a curvature domain without having to perform any phase unwrapping.

Systems and methods for wafer structure uniformity monitoring using interferometry wafer geometry tool

A semiconductor measuring tool has a folding mirror configuration that directs a light beam to pass the same space multiple times to reduce the size and footprint. Furthermore, the folding mirrors may reflect the light beam at less than forty-five degrees; thereby allowing for smaller folding mirrors as compared to the prior art.

Method and apparatus to fold optics in tools for measuring shape and/or thickness of a large and thin substrate

Interferometer systems and methods for providing improved defect detection and quantification are disclosed. The systems and methods in accordance with the present disclosure may detect surface defects on patterned or bare wafer surfaces and subsequently quantify them. In certain embodiments in accordance with the present disclosure, amplitude maps of the wafer surfaces are obtained and are utilized in addition/alternative to phase maps for wafer surface feature detection. Furthermore, local one-dimensional and/or two-dimensional unwrapping techniques are also disclosed and are utilized in certain embodiments in accordance with the present disclosure to provide height and depth information of the detected defects, further improving the detection capabilities of the measurement systems.

Systems and methods for wafer surface feature detection and quantification

A calibration wafer and a method for calibrating an interferometer system are disclosed. The calibration method includes: determining locations of the holes defined in the calibration wafer based on two opposite intensity frame; comparing the locations of the holes against the locations measured utilizing an external measurement device; adjusting a first optical magnification or a second optical magnification at least partially based on the comparison result; defining a distortion map for each of the first and second intensity frames based on the comparison of the locations of the holes; generating an extended distortion map for each of the first and second intensity frames by map fitting the distortion map; and utilizing the extended distortion map for each of the first and second intensity frames to reduce at least one of: a registration error or an optical distortion in a subsequent measurement process.

Reducing registration error of front and back wafer surfaces utilizing a see-through calibration wafer

Methods and systems for reducing wafer shape and thickness measurement errors resulted from cavity shape changes are disclosed. Cavity calibration process is performed immediately before the wafer measurement. Calibrating the cavity characteristics every time the method is executed reduces wafer shape and thickness measurement errors resulted from cavity shape changes. Additionally or alternatively, a polynomial fitting process utilizing a polynomial of at least a second order is utilized for cavity tilt estimation. High order cavity shape information generated using high order polynomials takes into consideration cavity shape changes due to temperature variations, stress or the like, effectively increases accuracy of the wafer shape and thickness information computed.

Method for reducing wafer shape and thickness measurement errors resulted from cavity shape changes

The present disclosure is directed to a system for measuring a thickness variation and a shape of a wafer. The system includes a first reference flat and a second reference flat. The first reference flat and the second reference flat are spaced apart to form a cavity. The cavity is configured to receive the wafer. The system also includes a plate. The plate may be inserted into the cavity with the wafer. The system also includes a first interferometer located on a first side of the cavity and a second interferometer located on a second side of the cavity. The system also includes a processor which may be in communication with the first interferometer and the second interferometer. The processor is configured to determine the thickness variation and the shape of the wafer based on at least the readings of the first interferometer and the second interferometer.

Measurement of thickness variation and shape of wafers

The invention provides a new dual-sided Moir&#xe9; wafer analysis system that integrates wafer flatness measurement capability with wafer surface defect detection capability. The invention may be, but is not necessarily, embodied in methods and systems for simultaneously applying phase shifting reflective Moir&#xe9; wafer analysis to the front and back sides of a silicon wafer and comparing or combining the front and back side height maps. This allows wafer surface height for each side of the wafer, thickness variation map, surface nanotopography, shape, flatness, and edge map to be determined with a dual-sided fringe acquisition process. The invention also improves the dynamic range of wafer analysis to measure wafers with large bows and extends the measurement area closer to the wafer edge.

Method and apparatus for measuring shape and thickness variation of a wafer

Disclosed herein is a method and apparatus for reducing measurement error resulting from temperature variations across a wafer, without measuring the wafer temperature, the temperature gradient in the surrounding air, or the distribution of the index of refraction of the air.

Method for compensating for wafer shape measurement variation due to variation of environment temperature

A method for enabling more accurate measurements of localized features on wafers is disclosed. The method includes: a) performing high order surface fitting to more effectively remove the low frequency shape components and also to reduce possible signal attenuations commonly observed from SEMI standard high pass, such as Gaussian and Double Gaussian filtering; b) constructing and applying a proper two dimensional LFM window to the residual image from the surface fitting processing stage to effectively reduce the residual artifacts at the region boundaries; c) calculating the metrics of the region using the artifact-reduced image to obtain more accurate and reliable measurements; and d) using site-based metrics obtained from front and back surface data to quantify the features of interest. Additional steps may also include: filtering data from measurements of localized features on wafers and adjusting the filtering behavior according to the statistics of extreme data samples.

Methods and systems for improved localized feature quantification in surface metrology tools

Disclosed herein is a method and system for providing environmental control for a vibration sensitive system such as an interferometric measurement system, while minimizing acoustic noise during data acquisition.

Method and apparatus for improving the temperature stability and minimizing the noise of the environment that encloses an interferometric measuring system

A method and system is disclosed for utilizing two single-shot phase shift interferometers to simultaneously measure wafer shape and thickness variation of two sides of a wafer. This system is able to extract the front height, the back height, and the thickness variation of a wafer in a single data acquisition. This system, when utilized with a fast shutter speed, decreases the insensitivity to vibration. Algorithms are introduced that extract the true thickness variation of a wafer even when the wafer is vibrating. The effects of air turbulence can be reduced by a phase averaging technique.

Method and apparatus for measuring the shape and thickness variation of a wafer by two single-shot phase-shifting interferometers

An interferometer system and method may be used to measure substrate thickness or shape. The system may include two spaced apart reference flats having that form an optical cavity between two parallel reference surfaces. A substrate holder may be configured to place the substrate in the cavity with first and second substrate surfaces substantially parallel with corresponding first and second reference surfaces such that a space between the first or second substrate surface is three millimeters or less from a corresponding one of the reference surfaces or a damping surface. Interferometer devices may be located on diametrically opposite sides of the cavity and optically coupled thereto. The interferometers can map variations in spacing between the substrate surfaces and the reference surfaces, respectively, through interference of light optically coupled to and from to the cavity via the interferometer devices.

Method and apparatus for measuring shape or thickness information of a substrate

A system with two unequal path interferometers, with a first flat, a second flat, and a cavity between the first and second flats, a holder to receive an object in the cavity such that an optical path remains open between the first and second flats, and a motor coupled to the holder such that the object may be tilted in the cavity to allow for measurements of, and a radiation assembly to direct collimated radiation to the interferometer assembly, a collecting assembly to collect radiation received from the interferometer assembly, and a controller comprising logic to; vary a wavelength of the radiation, record interferograms, extract phases of the interferograms to produce phase maps, determine from each map areas with high slopes, tilt the holder to allow measurement of the high slope areas, and process measurement that covers the entire surface of the object.

Measuring the shape and thickness variation of a wafer with high slopes

In one embodiment, an interferometer system comprises an unequal path interferometer assemble comprising; a first reference flat having a first length Lin a first dimension, a second reference flat having a second length Lin the first dimension, a cavity Ddefined by a distance between the first reference flat and the second reference flat, and a receptacle to receive an object in the cavity such that an optical path remains open between the first reference flat and the second reference flat, and a radiation targeting assembly to direct a collimated radiation beam to the interferometer assembly, a radiation collecting assembly to collect radiation received from the interferometer assembly, and a controller comprising logic to; vary a wavelength of the collimated radiation beam, record interferograms formed by a plurality of surfaces, extract phases of each of the interferograms for each of the plurality of surfaces to produce multiple phase maps, and determine each phase map from its corresponding interferogram, using a weighted least-square algorithm.

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Santa Clara, CA, United States of America

Shouhong Tang