Abstract: A scanning probe microscope equipped with a mechanism for exchanging a probe balance beam from the scan head, wherein the probe balance beam is of the type which is magnetically constrained on the scan head. A magnet having a magnetic field strength greater than that of the scan head magnet is utilized to overcome the attractive force exerted on the balance beam by the scan head magnet and transfer the balance beam from the scan head to a plate in a holding station on the sample table of the microscope. Completely automatic operation is achieved without operator handling of the balance beam.

Abstract: A circuit for driving light emitting diodes with a precise amount of current in response to an input pulse is disclosed. The input pulse drives a transistor into saturation, and the collector current of this transistor is increased in value through the use of two cascaded multiplying current mirrors. The second current mirror directly drives the light emitting diodes.

Abstract: X-ray masks are typically made by depositing and patterning a layer of heavy metal on a thin supporting membrane. The metal layer must have a relatively low and uniform stress to prevent stress-induced deformation of the pattern. Tungsten films having excellent stress characteristics are produced by employing a continuously operating capacitance-based measurement technique to allow adjustment of the deposition conditions in rapid response to changes in stress of the film being deposited. The stress gradients in the film are further reduced by transferring heat from the membrane as the metal is deposited thereon.

Abstract: A circuit that prevents optical screening systems from being pinned in an inoperative state under certain light conditions. The invention accomplishes this by using a circuit comprising a photodetector for converting scattered light from a visual code (e.g., universal product code) into current and a current limiting circuit coupled to the photodetector for limiting the current capable of passing through the photodetector.

Abstract: A photodetector circuit is disclosed which can extract a carrier frequency signal from an optical beam. A photodiode is back-biased by a voltage supply, and the capacitance of the photodiode is dependent on the value of its back-bias potential. The photodiode is connected in parallel resonance with an inductor, and the parallel resonant combination is connected to the input of an inverting amplifier having a feedback capacitor. This feedback capacitor causes a capacitive component to appear in the input impedance of the amplifier which combines with the photodiode capacitance and the inductor to provide a parallel resonant tank circuit. The amplifier has a change in gain versus change in power supply characteristic. By selecting the value of the feedback capacitor, changes in the capacitive component of the input impedance are equal and opposite to changes in the capacitance of the photodiode, and the resonant frequency of the tank circuit is thereby essentially unaffected by changes in the supply voltage.

Abstract: X-ray masks are typically made by depositing and patterning a layer of heavy metal on a thin supporting membrane. The metal layer must have a relatively low stress to prevent stress-induced deformation of the pattern. Tungsten films having excellent stress characteristics are produced by employing a continuously operating capacitance-based measurement technique to allow adjustment of the deposition conditions in rapid response to changes in stress of the film being deposited.

Abstract: A battery feed circuit for supplying DC power to a telephone loop and for coupling signals to and from said loop is disclosed. A differential amplifier having its inputs connected by way of a twisted resistive bridge to the telephone loop provides a voltage at its output which includes the signal from said telephone loop and has a DC component which is proportional to the DC current flowing in the loop. Signals are coupled to the telephone loop by a low-inductance three-winding transformer which has two of its windings connected in series with an external power supply and the twisted bridge in order to supply current to the telephone loop. A second differential amplifier is connected in different ways in several embodiments between the output of the first differential amplifier and the third winding of the transformer to provide an automatic flux-cancelling action in order to avoid saturation of the transformer core.

Abstract: X-ray masks are typically made by depositing and patterning a layer of heavy metal on a thin supporting membrane. The metal layer must have a relatively low stress to prevent stress-induced deformation of the pattern. Tungsten films having excellent stress characteristics are produced by employing a continuously operating capacitance-based measurement technique to allow adjustment of the deposition conditions in rapid response to changes in stress of the film being deposited.

Abstract: Capacitive proximity sensors are disclosed that can be fabricated in different shapes, sizes and materials used in a wide variety of applications. Each such sensor includes a sensing electrode and a guard electrode. The sensor electrode and guard electrode can be parallel conductors separated by an insulating layer, such as a double-sided circuit board shaped to suit the application. One such sensor is transparent for use in conjunction with an optical bar-code scanner. Another sensor is annular in shape for use in conjunction with a telephone transmitter. The sensing electrode and the guard electrode are driven in unison by an RF signal. The proximity of an object to the sensor is observed by detecting changes in the RF current flowing through the sensing electrode caused by the proximity of an object to the sensing electrode.

Abstract: In accordance with the present invention, a silicon device fabricated on a (100) silicon substrate is provided with a (111) slant surface and an electrical contact comprising epitaxial low Schottky barrier silicide is formed on the (111) surface. For example, low resistance rare earth silicide contacts on V-groove surfaces are provided for the source and drain contacts of a field effect transistor. The resulting high quality contact permits downward scaling of the source and drain junction depths. As another example, rare earth silicide Schottky contacts are epitaxially grown on V-groove surfaces to provide low voltage rectifiers having both low power dissipation under forward bias and low reverse-bias leakage current.

Abstract: A force-sensing system suitable, for example, for atomic force microscopy. This system includes a rocking beam, a base, and means for supporting the beam adjacent a surface of the base such that the beam can pivot about at least one axis parallel to the base surface. In contrast to rocking-beam systems of the prior art, the support means comprise at least one pivot element that can be held against the base surface by a magnetic field.

Abstract: Slurry in a slurry polisher is ultrasonically agitated during polishing to dislodge embedded debris and grit from the polishing pad and thereby improve the uniformity of material removal, lengthen the life of the pad and avoid scratches and defects on the surface being polished. The method is particularly useful for applications in which slurry polishing is used for planarizing deposited layers on semiconductor wafers where non-uniformities caused by such embedded material can affect process yields. Apparatus is disclosed for applying ultrasonic energy to the slurry so that such energy is focussed on the pad.

Abstract: A force balancing method and apparatus detects small changes in force or pressure. An LC tuned circuit having a capacitor with at least one movable plate senses force or pressure changes. Deviations in the phase of the response of the tuned circuit are compared to the phase of a driving reference oscillator to generate an error signal. The error signal is used to control the oscillator to increase or decrease its output amplitude for driving the tuned circuit. As a result the electrostatic force across the capacitor plates tends to change in such a way as to precisely balance the effect of external force or pressure changes. The system therefore operates in a force-balance mode and in such a way as to provide a high sensitivity together with a precisely controlled stiffness. This system is particularly applicable to high sensitivity microphones, micro-topography, and atomic force microscopy.

Abstract: This invention provides an in situ monitoring technique and apparatus for chemical/mechanical planarization end point detection in the process of fabricating semiconductor or optical devices. Fabrication of semiconductor or optical devices often requires smooth planar surfaces, either on the surface of a wafer being processed or at some intermediate stage e.g. a surface of an interleaved layer. The detection in the present invention is accomplished by means of capacitively measuring the thickness of a dielectric layer on a conductive substrate. The measurement involves the dielectric layer, a flat electrode structure and a liquid interfacing the article and the electrode structure. Polishing slurry acts as the interfacing liquid. The electrode structure includes a measuring electrode, an insulator surrounding the measuring electrode, a guard electrode and another insulator surrounding the guard electrode.

Abstract: Position indicating apparatus that allows position detection with windings provided on only one of two members and an output signal in which the position of one of the members relative to the other member is directly encoded in the phase of the output signal. A first member has a plurality of spaced ferromagnetic protuberances. A second member, movable with respect to the first member, contains at least first, second and third poles located in proximity to the protuberances and spans 360 spatial degrees. Each pole contains a winding with one terminal of each winding connected to a common point. The windings are driven at a fundamental carrier frequency with individual signals of equal amplitude but different temporal phases that span 360 temporal degrees. Circuit means detect the phase of the resulting carrier signal at the common point, which phase is linearly representative of position.

Abstract: There are disclosed both one and two-dimensional, high resolution, brushless DC servomotors that are linear, rotary, planar and cylindrical in nature. All of these employ a capacitive method for deriving the required position and motor commutation information. In suitable circumstances, particularly two-dimensional planar motors on air bearings, the method allows the use of the motor ferromagnetic cores themselves as the capacitive position sensing elements. This leads to a particularly simple and compact type of sevomotor design. In addition, since such motors can move at high speed, there are also disclosed two transformer coupled methods for handling the current drive to the motor windings. Both methods are simple, energy efficient, applicable to motors of any number of phases, and in addition, handle motor direction reversals automatically.

Abstract: A capacitance based, high resolution, incrementally encoding, position measuring system employs an array of identical replicated electrodes that are driven in unison from an RF source and mounted in proximity to a patterned monolithic reference ground plane of arbitrary size. Motion of such position-sensing arrays is monitored by measuring both the sums and the differences of the electrode displacement currents in such a way as to provide incrementally encoding position signals in both one and two dimensions together with a continuous measurement of the height of the sensor array above the patterned ground plane. In various modifications, the system and methods are applied both to one dimensional linear, as well as to two dimensional planar and two dimensional cylindrical motion measurement and control. Various techniques for eliminating the effects of spurious capacitances are also disclosed.

Abstract: There is disclosed an optical ranging system adapted for use with widely varying return signal levels. Automatic signal level control is achieved in two parts, a passive optical part and an active electronic AGC part. The optical part is based on the coaxial arrangement of transmitting and receiving elements in which the shielded transmitting element is mounted in front of the receiving element, which includes Fresnel lens which comprises a plastic casting. The electronic AGC portion of the system includes means for providing a voltage drive (with low internal impedance) for the final AGC transistor when it would tend to be slow, so little phase shift in the control results from changes in the signal levels. Thereby, the determination of distance (the ranging) by phase shift measurement is kept reliable as signal level changes.

Abstract: An acoustic transducer is connected to an electronically controllable time-dependent conductance so that energy may be rapidly applied to and extracted from the transducer and associated circuitry.

Abstract: Disclosed is a capacitive, preferably noncontacting, photovoltaic method for conductivity type determination of a semiconductor sample, including of a thin epitaxial layer on a substrate, and a related method that can advantageously be used for surface state spectroscopy of semiconductors. The type-determination method comprises comparing the phase of a signal, obtained capacitively by maintaining an electrode in close proximity with an appropriately illuminated semiconductor surface region, with the phase of a reference signal at the illumination modulation frequency. The phase relationship between signal and reference signal indicates the conductivity type of the semiconductor. A preferred embodiment of the method, comprising an operational amplifier integrator, can be advantageously used for surface state spectroscopy, since, inter alia, the observed signal is substantially independent of the sample/electrode spacing.