Abstract:
A method for operating a monolithic, integrated, micromachined structure that includes a reference member and one or more dynamic members. Each dynamic member is supported from the reference member, either directly or indirectly, by torsion hinges. Supported in this way, each dynamic member exhibits a plurality of vibrational modes. Preferably, the structure is micromachined to establishes specified relationships between various pairs of vibrational modes. The method also includes applying force to each dynamic member that urges the member to rotate out of a rest position to a fixed particular angle.
Abstract:
A document transport for a scanner (100) has a flexible, elongated finger (226) disposed adjacent to a document (134), and a force applied to the finger (226) urges teeth (233) on the finger (226) into contact with the document (134) which urges the document (134) along a path through the scanner (100). A piezoelectric plate (222), which applies the force to the finger (226), requires only a small amount of electrical power. To traverse the scanner (100), a document (134) may also be manually fed along a guide (272). First and second speed-sensing detectors (276a and 276b), disposed along the path traversed by the document (134), permit the scanner (100) to determine a speed at which the manually fed document (134) traverses the scanner (100). To conserve electrical energy, the scanner (100) also includes a document-presence detector (274) for activating the scanner (100) when a document (134) to be scanned is present.
Abstract:
Two torsion bars project from a reference member to support at least one plate or frame-shaped first dynamic member for rotation about an axis of the torsion bars. In one embodiment, a frame-shaped first dynamic member and a second pair of torsion bars, oriented non-parallel to the first torsion bars, support a second dynamic member for rotation about an axis that is collinear with the second pair of torsion bars. The vibrational frequency of the principal torsional vibrational mode of the dynamic members are respectively lower by at least 20% than the vibrational frequency of any other vibrational mode thereof. Either an electrostatic or electromagnetic drive means imparts rotary motion to the dynamic members about the collinear torsion bar axis(es). The reference member, the torsion bars and the dynamic member(s) are all monolithically fabricated from a stress-free semiconductor layer of a silicon substrate.
Abstract:
The forming of superhard, durable and inert mechanical microstructures, such as tips for atomic force microscopy and field emission, membranes, hinges, actuators, and sensors requires micromachining of silicon or polysilicon. The microstructures are then reacted with a hydrocarbon or ammonia gas, at a temperature in the range of 700.degree. C. to 1100.degree. C. and in partial vacuum conditions for several minutes. Gases such as methane, ethane, or acetylene will convert the surface layers to SiC, which is useful for its conductive properties, while ammonia gas will convert the surface layers to Si.sub.3 N.sub.4, which is useful for its insulative properties. Thus, the converted material will have improved physical, mechanical, chemical and electrical properties.
Abstract:
A monolithic single crystal Si rate-gyro consisting of in the preferred embodiment, an outer torsional frame, self resonating with a substantial amplitude, as controlled by a four-terminal piezo torsion sensor, connected to an inner frame by torsional hinges. The inner frame itself is connected to a fixed inner post, by a set of torsion hinges, defining an axis of rotation perpendicular to the first axis. Rotation of the axis of oscillation of the outer body causes the moving mass and the inner frame to tilt and oscillate at the outer frequency due to Coriolis forces, thereby periodically deforming the inner hinges in torsion. These inner hinges are likewise equipped with a four-terminal piezo voltage torsion sensor, giving an indication of the rate of rotation of the sensor. The design allows for good sensitivity, due to the substantial swing of the outer oscillator, its high moment of inertia, excellent Si spring characteristics, and excellent sensitivity of the torsional sensors. Because of the integration of all of parts in silicon and its inherent simplicity, it can be made very inexpensively.
Abstract:
A conduit defined by an oxygen ion permeable wall formed of zirconia or other materials and having gas permeable electrodes disposed on an inner and outer surface of the wall. The electrodes are configured to form two oxygen pumps that share an electrode on the inner surface in order to minimize interference with gas flowing through the conduit, yet allow a number of operations to be performed on the gas as it flows. The conduit can be used as a getter for removal of oxygen from even reactive gases. The conduit can also be used as a pump for injecting a known quantity of oxygen to the gas, the oxygen supplied from air outside the conduit. The upstream pump can be used as a getter and the downstream pump for oxygen injection, thereby providing a known concentration of oxygen gas or oxidants, such as water vapor, in the gas exiting the conduit. The conduit can contain a pair of sensor electrodes on the inner and outer surface downstream of the other electrodes. The sensor electrodes can determine when the oxygen removed from the gas is equal to the known quantity of oxygen injected, providing a means for measuring the concentration of oxidants in the gas.
Abstract:
A surface inspection apparatus having multiple inspection stations to inspect a wafer for a number of characteristics. The wafer is placed on a chuck connected to a rack-and-pinion or equivalent system so that the wafer simultaneously rotates and translates under the fixed position of the inspection stations. A single light source may be used by all stations in turn. One station may be a particle detector with collection optics receiving a small select portion of the light scattered from the wafer surface. A second station may be a roughness detector with a collection system to direct a large portion of scattered light to a detector. A position sensitive detector may be used to determine the slope of the wafer surface at an inspection point when the wafer is not clamped to the chuck, giving a measure of surface deformation. These or other stations are positioned about either of two inspection points at which the beam from the light source may be directed. The inspection points are spaced one wafer radius apart to minimize the required wafer motion for a complete surface scan.
Abstract:
A method and apparatus for predicting the number of contaminant particles in circuit area of a patterned semiconductor wafer having a number of reflective circuit areas. The method includes forming on a wafer in specified areas, a grating test pattern, such as a line grating. The grating patterns are formed at the same time and in the same manner that repetitive circuit patterns are formed on the wafer. The wafer is then scanned by a light beam. Since the diffraction pattern caused by the grating test patterns is known, it is possible to detect when the light beam is scanning one of the known grating patterns. The diffraction pattern may be inspected for fabrication derived variations. In response to detecting a known grating pattern, a detection mechanism is activated. Since the diffraction pattern is known it may be spatially separated. In this way only light scattered by particles or defects in the pattern are collected and detected. From the scattered light that is collected and detected, a particle count may be determined for the grating pattern area. From this particle count an accurate prediction of the number of particles in the circuit patterns may be made. The apparatus may also inspect bare areas. In this manner real time inspection may be performed on patterned wafers.
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:
Method and apparatus for determining the amount, if any, of residue remaining at the bottom of an aperture in a layer of dielectric or insulator material. A layer of electrically conducting material is positioned adjacent to the aperture bottom, an electron collector is positioned adjacent to the mouth of the aperture, and a voltage difference (optional) is impressed between the conducting material and the electron collector. The aperture bottom is illuminated with a light beam with photon energy greater than the electron work function of the conducting material, and a portion of the photons that comprise the light beam reach the conducting material and produce photoelectrons by photoemissive action. A photoelectron current is sensed by the electron collector, and the cleanliness of the aperture bottom is determined from the value of the current.