Abstract: A flat workpiece is placed in contact with a flat platen in a vacuum chamber, and is held by a uniformly-distributed force while a small mass flow of gas is introduced along a contour to form a uniform pressure region between the flat workpiece and the platen. Separation of the two surfaces due to aplanarity or surface roughness is less than the gas mean free path, and high rates of heat transfer are obtained uniformly over the area of the workpiece. A scavenging port, located outwardly of the gas introduction contour is differentially pumped to reduce the rate of gas leakage into the chamber. Preferably, pressure is provided by an electrostatic clamp (for non-insulating substrates) or other clamping arrangement which does not occlude the front surface of the workpiece. In the electrostatic clamp, the voltage activation sequence prevents workpiece vibration, while a clamping current sensor immediately detects degree of contact, e.g., due to debris on the platen, and initiates a suitable warning or control.

Abstract: An apparatus and method for precisely calibrating the transfer arm of a multiple station wafer processing system without breaking vacuum and with a minimum of system downtime is provided. A system of determining and properly aligning the crystallographic orientation of the wafers before processing as well as monitoring the orientation of individual wafers during wafer transfer between processing stations is also provided.

Abstract: The temperature and radiant energy emissivity of a semiconductor substrate or wafer undergoing processing are monitored by combining indications derived from an interferometer and the intensity of radiant energy emitted from the substrate. The radiant energy intensity is detected at adjacent maxima or minima in the intensity of the interference pattern.

Abstract: A method and apparatus makes rapid frequency measurements by measuring time intervals for a series of blocks of event counts with the number of events in each block held constant. This makes the numerator of the events/time relationship constant so it does not have to be measured, processed or stored. The frequency of the signal is determined by measuring the time interval, then taking the inverse of the measured value and multiplying by the appropriate constant. A fast inverse circuit uses a Taylor series expansion technique implemented in digital circuit, with the slope resolution adjusted for regions of small slope to improve accuracy.

Abstract: A method for examining an input signal and setting a modulation domain measuring instrument to a state which will produce a measurement and a stable, centered, properly scaled display of the signal, automatically. After finding the 50 percent voltage threshold of the input signal, an iterative process determines the minimum and maximum input frequency, then checks the ratio of these two frequencies against instruments limits, and adjusts the display values, if necessary to show only the higher frequencies. The method then varies the measurement parameters to seek the best frequency resolution while maintaining the measurement and display of frequency modulation. The display frequency scale is set to display the signal in the center half of the display, using values with no more than two significant digits for the center and span. The time scale is set to display a selected number of modulation cycles.

Abstract: A linear-and-angular measuring plane mirror interferometer measures two degrees of freedom, both linear translation and rotation angle, using a single interferometer optical assembly. In alternate orientations it can be used to measure either the pitch, roll or yaw angle. The linear-and-angular measuring interferometer splits the measurement beam at the interferometer optic, using a single integrated optical assembly to make measurements at two locations on a measuring mirror on a stage. In a first embodiment, the input beam is split, and two separate measurements, X and X', are made at two locations separated by a distance d. A second embodiment optically produces a direct measurement of X--X' at a detector. The input beam makes one interferometer measurement for X, then the polarization of part of the resulting output beam is rotated and the rotated part of the beam is returned for a second pass to make an interferometer measurement at a location offset by a distance d from the first pass measurement.

Abstract: A test head comprising an electrically conductive cylindrical member for coupling to a device under test, a first path for connecting a first type of signal with the device under test, the first path being located outside the cylindrical member, and a second path for connecting a second type of signal with the device under test, the second path being located inside the cylindrical member, thereby preventing interference between signals of the first and second types. The first type of signal may be a digital signal and the second type of signal may be an analog signal.

Abstract: A method of digitally controlling the gate for a timing counter, to open and close the gate based on the occurrence of signal events, rather than on the envelope of the pulse. In a particular embodiment, a digital divider controls the gate, so that, when a pulse burst of RF is encountered, the gate opens on the second signal event. The divider can be programmed to close the gate any number of signal events later. Measurements are taken for an integral number of signal events, while counting time events from a precision clock. A series of measurements can be taken with various integral numbers of signal events for frequency profiling. By incrementing the digital divider from n to n+1 signal events for successive measurements, and subtracting the results, very narrow gates are effectively generated which move through the pulse cycle by cycle for frequency profiling.

Abstract: A real-time database provides the predictable, high speed data access required for on-line applications, while providing flexible searching capabilities. The data retrieval routines include the option to "read-through-lock" to access data in locked data tables, the capability to directly access to data using tuple identifiers, and the capability to directly access unformatted data from input areas which contain blocks of unformatted data. The data updating routines include an option to omit index updating when updating data and an option to update data in a locked data table. Multiple indexes can be defined for a data table. Thus, high speed searches can be performed based on a variety of data fields. The data storage and retrieval mechanisms are independent and there are hash index tables that connect the multiple index keys to the data tables. The data table structure includes a column defined for storing tuple identifier strings.

Abstract: A hermetic package for microelectronic circuits comprises a ceramic base with conductive, hermetically sealed vias that connect the metal ground plane on the bottom of the base to the circuit on the top, a ceramic frame sealed to the top of the base, leads sealed between the frame and the base, and a lid sealed to the top of the frame. The vias are cofired with the ceramic base and provide good power dissipation because of their thermal conductivity and good RF grounds to isolate different stages in the circuit. Because the vias are hermetically sealed, no separate bottom component and no brazing operation is required to hermetically seal the package. The leads have a tapered section so the leads are wider outside the package reducing inductance and narrower going through the ceramic frame to reduce capacitance, thus tuning the leads to close to 50 ohm impedance. A layer of conducting silver loaded solder glass underneath the lead electrically connects the lead to the circuit and seals the lead to the base.

Abstract: A mounting nest for the sapphire ball at the tip of a bar code reader wand has a hemispherical recess that contacts the surface of the sapphire ball to hold the ball securely. The mounting nest is molded from a material having a relatively high index of refraction so the optical effect of the surface of the ball in contact with the recess component can be effectively neutralized. The mounting nest eliminates leakage paths around the sapphire ball for dust, ESD or other contaminants to the sensor and circuitry inside the wand.

Abstract: Method and apparatus for isolating optical feedback in a laser interferometer having a laser light source from which a linear polarized outgoing laser beam of certain polarization orientation is derived. The interferometer also redirects the outgoing laser beam to form a return laser beam directed to a receiver. The outgoing laser beam and the return laser beam are physically close and are substantially parallel. The linearly polarized outgoing laser beam is converted to circular polarization. A portion of the circularly polarized return laser beam directed toward the laser light source is converted back to linear polarization with polarization orientation orthogonal to the polarization orientation of the outgoing laser beam. A portion of the circularly polarized return laser beam directed toward the receiver is converted back to linear polarization with polarization orientation being substantially the same as the polarization orientation of the outgoing laser beam.

Abstract: A bar code reader configuration and control system uses an interpreter routine in the operating system of the bar code reader and a menu with bar code tags encoded to invoke instructions which directly access and manipulate the system's memory. The instructions encoded in the bar code labels on the menu can access any memory address in the operating system to load any value at a given bit or byte location. By changing the values at the accessed memory locations, the menu tags perform two kinds of functions, configuring the operating characteristics of the bar code reader and controlling the operation of the reader.

Abstract: A vector analyzer incorporates a set of five types of markers for the display, which facilitate the visual analysis of the magnitude, phase and time relationships of the I and Q components of the modulation states displayed. The five markers are: an I marker, a Q marker, a magnitude marker, a phase marker and a time marker. The I and Q markers indicate amplitude in the I and Q coordinates displayed on the X-Y displays. The magnitude marker indicates amplitude on the radial coordinate of the X-Y displays. The phase marker indicates relative phase on the angular coordinate of the X-Y displays. The time marker indicates the time coordinate on the displays, and controls the time instant displayed. The analyzer also incorporates a circuit for performing linear transforms on the I, Q, and time data which allows real time adjustment of the sampled signals and enables the signals to be displayed in a three dimensional projection mode.

Abstract: A tracking YIG tuned filter-mixer circuit is provided. In the preferred embodiment, four YIG-tuned resonators are combined to provide a tracking filter-mixer with a switched input. Field coils produce a magnetic tuning field that is uniform over the four YIG resonators. The first YIG resonator acts as the first stage of the filter, and in combination with a PIN diode circuit switches the RF input signal either to an output port or into the succeeding stages of the filter mixer. The second YIG resonator acts as the second stage of the filter. The third YIG resonator acts as the third stage of the filter, and as a fundamental mixer for combining the input RF signal with a swept LO signal to produce the IF output signal. The fourth YIG resonator acts as a discrimintor, comparing the LO frequency to the filter tuning frequency to generate an error signal for the field coil drive circuit.

Abstract: A trackball for controlling the motion of a video-screen cursor comprises a control ball, said control ball being held on at least two rotatable rolling bodies, said rolling bodies each touching the control ball at at least two contact points. These rolling bodies may, for example, have the shape of a double cone or of two spheres mounted on a shaft. The result is that, once imparted rotary momentum in an initial direction, the control ball retains momentum in that direction, i.e., the video-screen cursor moves in a precisely vertical or precisely horizontal direction across the video screen once it is started in such a direction. Furthermore, in a preferred embodiment, the axial bearing arrangement of the rolling bodies is dispensed with.

Abstract: A remote receiver for laser interferometer systems is split into two parts connected by a fiber optic link. The front-end of the receiver, located near the remote interferometer optics, houses only the optical components for focusing and mixing the laser beam, and transmits the beam through an optical fiber cable. The back-end of the receiver, located remotely, houses the electronic components for detecting and measuring the frequency difference to produce the signal for the measurement electronics.

Abstract: An optical system for an interferometer compensates for changes in temperature by incorporating optics in which the reference and measurement beams follow different but optically equivalent paths through optical elements that are in thermal equilibrium. The optical elements of the interferometer are so arranged that the reference beam and the measurement beam follow equivalent optical path lengths through the interferometer, whose elements are in thermal equilibrium. That is, the path lengths through the high refractive index media of the optics are the same length and refractive index, but do not follow the same path. Because the beams are not constrained to follow the same path, fewer optical elements are needed and shorter OPLs can be used resulting in less complexity, better optical efficiency, easier alignment and lower cost.

Abstract: A combination FIFO buffer and programmable shift register having asynchronous input and output capabilities comprises a three stage system which synchronizes the incoming data stream with the memory input clock, buffers the incoming data stream and provides a variable delay for the data. The digital data stream from an input device is received by an input synchronizer having its input clocked at the clock rate of the input device clock and its output clocked at a higher internal clock rate. The data is written into two FIFO buffers, a master and a slave. The master buffer controls the read and write addresses of both buffers, so that the write address of the buffers advances only when valid data is written into the buffers, and the read address advances only when data is read out of the buffers. The slave buffer can be programmed with an offset in its read address, so it operates as a delay buffer.

Abstract: A feeder assembly comprising a feeder tube having metal rails mounted therein along which IC's can slide on the parts of their leads next to their body and at one end an adapter for guiding the IC's from a transport tube onto the rails. An opening in the feeder tube is provided for permitting pulses of gas to flow through the tube toward the end of the tube remote from the adapter so as to move the IC's to a pick-up pad at said remote end one at a time.