Abstract: An ellipsometric apparatus provides two impinging focused probe beams directed to reflect off the sample along two mutually distinct and preferably substantially perpendicular directions. A rotating stage rotates sections of the wafer into the travel area defined by two linear axes of two perpendicularly oriented linear stages. As a result, an entire wafer is accessed for measurement with the linear stages having a travel range of only half the wafer diameter. The reduced linear travel results in a small travel envelope occupied by the wafer and consequently in a small footprint of the apparatus. The use of two perpendicularly directed probe beams permits measurement of periodic structures along a preferred direction while permitting the use of a reduced motion stage.

Abstract: The subject invention relates to a wafer stage, such as may be used in optical wafer metrology instruments. The stage contains a wafer-chuck that can be connected to translation stages for the purpose of clamping and translating the wafer so that a plurality of sites on the wafer surface may be measured. The chuck includes a holder for mounting a reference sample. The holder is movable between a retracted position where the reference sample is held below the chuck surface and an extended position, such as where the surface of the reference sample is co-planar with the wafer surface. Therefore the holder may be installed within the area of the chuck that is utilized for wafer clamping. By this arrangement, the size of the wafer translation system can be reduced minimizing the stage travel and enabling increased spatial resolution, increased wafer throughput and reduced capital equipment and operating costs.

Abstract: An ellipsometer includes a light source for generating a probe beam of polychromatic light for interacting with a sample. The probe beam is passed through a first polarizer that imparts a known polarization state to the probe beam. The polarized probe beam is then directed to reflect from the sample. A second illumination source is switched on and off at a predetermined frequency to create an intensity modulated pump beam (the beam may also be chopped). The pump beam is directed normally against the subject producing a small illumination spot within the area illuminated by the probe beam. The pump induces localized changes in the dielectric properties of the subject. The pump-beam induced oscillations are picked up by the portion of the probe beam that is reflected from within the illumination spot of the pump beam.

Abstract: An ellipsometric apparatus provides two impinging focused probe beams directed to reflect off the sample along two mutually distinct and preferably substantially perpendicular directions. A rotating stage rotates sections of the wafer into the travel area defined by two linear axes of two perpendicularly oriented linear stages. As a result, an entire wafer is accessed for measurement with the linear stages having a travel range of only half the wafer diameter. The reduced linear travel results in a small travel envelope occupied by the wafer and consequently in a small footprint of the apparatus. The use of two perpendicularly directed probe beams permits measurement of periodic structures along a preferred direction while permitting the use of a reduced motion stage.

Abstract: The subject invention relates to a translating wafer stage for use in optical wafer metrology instruments. The stage contains a wafer-chuck connected to translation stages for the purpose of clamping and translating the wafer so that a plurality of sites on the wafer surface may be measured. The chuck includes a holder for mounting a reference sample. The holder is movable between a retracted position where the reference sample is held below the chuck surface and an extended position where the surface of the reference sample is co-planar with the wafer surface. Therefore the holder may be installed within the area of the chuck that is utilized for wafer clamping. By this arrangement, the size of the wafer translation system can be reduced minimizing the stage travel and enabling increased spatial resolution, increased wafer throughput and reduced capital equipment and operating costs.

Abstract: An optical inspection system and method which uses a procedure for determining an offset between a field of view and a center or rotation of an R-theta stage, or polar coordinate stage. Determining this offset allows the precise location of a site being inspected on a wafer to be determined. The system and method take advantage of the fact that in a R-theta system there can be only two positions for the R-theta stage that will position a particular site under the lens of the imaging system of the optical inspection system. By moving the stage from a first position where a particular site is positioned in the field of view, to the second position where the particular site is positioned in the field of view, the offset can be determined.

Abstract: A fast wafer positioning method for optical metrology includes three main steps. In the first step, an initial measurement recipe is constructed for the host system and target wafer. In the next step, the host system performs a test run using the initial measurement and the target wafer. In this step, the initial measurement recipe is refined to eliminate positioning errors produced by the host system. In the final step, the refined measurement recipe is used by the host system to process production wafers (e.g., as part of a production environment). This is performed using the information included in the refined measurement recipe without reference to optical images of the wafers being processed.

Abstract: An autofocus system for maintaining a sample in the focal plane of a primary lens is disclosed. A light source generates a monitor beam which is focused onto the sample through the primary lens. The reflected beam passes back through the primary lens and is directed to a secondary lens. The beam is then split by a reflective wedge into two portions with different path lengths such that the beam waists of the two portions are spatially separated. An aperture is located between the two beam waists. A bi-cell photodetector measures the intensity of the two beam portions transmitted by the aperture. The measured intensity levels vary with respect to the position of the sample. By comparing the measured intensity levels, an indication of the position of the sample can be obtained.

Abstract: A system for communication between the software components of an optical metrology system is provided. For this system, an optical metrology tool is configured to have a graphical user interface (GUI) process and a control software process. The GUI process is responsible for user interaction. The control software controls the operation of the optical metrology tool (e.g., data acquisition, robotic wafer handling, etc.). The GUI and control software processes communicate using two named pipes. The first, or inbound pipe is used by the GUI process to send commands to the control software process. The second, or outbound pipe is used by the control software process to send result messages to the GUI process. This decouples the GUI and control software processes. This facilitates the use of GUI development environments and allows the GUI process and control software process to be hosted on separate computer systems in networked environments.

Abstract: A positioning subsystem for an optical metrology tool includes a beam splitter that receives light reflected by an area of interest within a subject. The beam splitter divides the reflected light and directs the result along separate high and low magnification paths. The high and low magnification paths each include one or more lenses. The lenses on the low magnification path create a low magnification image of the area of interest that is used to perform rough positioning of the subject. The lenses on the high magnification path create a high magnification image of the area of interest that is used to refine the rough positioning of the subject.

Abstract: A metrology system which includes an imaging system and provides a number of software interface tools. These software interface tools allow a user to intuitively and efficiently move a sample being imaged and measured to different locations relative to the imaging system. The software interface allows a user to use a pointer to select areas on an image of the wafer, and the processor system will detect the user inputs selecting the desired area on the wafer, and in response to the input, move the selected area on the wafer to a position such that it appears closer to a center region displayed on the user interface. The software interface also provides a geometric shape where the user can select areas on the geometric shape and in response to the selection of areas on the geometric shape the processor system will move a corresponding area on the wafer being imaged to a location relative to the imaging system such that the corresponding area will appear closer to a center area on a displayed image of the wafer.

Abstract: An autofocus system for maintaining a sample in the focal plane of a primary lens is disclosed. A light source generates a monitor beam which is focused onto the sample through the primary lens. The reflected beam passes back through the primary lens and is directed to a secondary lens. The beam is then split by a reflective wedge into two portions with different path lengths such that the beam waists of the two portions are spatially separated. An aperture is located between the two beam waists. A bi-cell photodetector measures the intensity of the two beam portions transmitted by the aperture. The measured intensity levels vary with respect to the position of the sample. By comparing the measured intensity levels, an indication of the position of the sample can be obtained.

Abstract: An ellipsometric apparatus provides two impinging focused probe beams directed to reflect off the sample along two mutually distinct and preferably substantially perpendicular directions. A rotating stage rotates sections of the wafer into the travel area defined by two linear axes of two perpendicularly oriented linear stages. As a result, an entire wafer is accessed for measurement with the linear stages having a travel range of only half the wafer diameter. The reduced linear travel results in a small travel envelope occupied by the wafer and consequently in a small footprint of the apparatus. The use of two perpendicularly directed probe beams permits measurement of periodic structures along a preferred direction while permitting the use of a reduced motion stage.

Abstract: An optical inspection system and method which uses a procedure for determining an offset between a field of view and a center or rotation of an R-theta stage, or polar coordinate stage. Determining this offset allows the precise location of a site being inspected on a wafer to be determined. The system and method take advantage of the fact that in a R-theta system there can be only two positions for the R-theta stage that will position a particular site under the lens of the imaging system of the optical inspection system. By moving the stage from a first position where a particular site is positioned in the field of view, to the second position where the particular site is positioned in the field of view, the offset can be determined.

Abstract: The subject invention relates to a translating wafer stage for use in optical wafer metrology instruments. The stage contains a wafer-chuck connected to translation stages for the purpose of clamping and translating the wafer so that a plurality of sites on the wafer surface may be measured. The chuck includes a holder for mounting a reference sample. The holder is movable between a retracted position where the reference sample is held below the chuck surface and an extended position where the surface of the reference sample is co-planar with the wafer surface. Therefore the holder may be installed within the area of the chuck that is utilized for wafer clamping. By this arrangement, the size of the wafer translation system can be reduced minimizing the stage travel and enabling increased spatial resolution, increased wafer throughput and reduced capital equipment and operating costs.

Abstract: A spectroscopy system having enhanced noise reduction that comprises (i) an arc lamp light source of emitted light, which emitted light is projected as an image of the light source; (ii) a slit aperture through which the emitted light is projected; and (iii) a detector operably associated with the slit aperture for detecting the emitted light. The slit aperture, the arc lamp, and the image of the arc lamp each have a major axis. The major axis of the slit aperture is oriented essentially orthogonally to the major axis of the image of the arc lamp, so that the signal-to-noise ratio of the spectroscopy system is improved as compared to the signal-to-noise ratio of the spectroscopy system when the major axis of the slit aperture is oriented essentially parallel to the major axis of the image of the arc lamp.