Abstract: Generating test signals for a device under test (DUT) involves generating a master reference signal, using a vernier technique to generate test pattern signals based on the master reference signal, generating a test clock signal that is phase-matched with and frequency similar to the test pattern signals by providing the master reference signal as input to a phase-locked loop (PLL) and controlling one or more programmable dividers in the PLL to adjust the test clock signal to be a multiple or sub-multiple of a frequency of the test pattern signals, applying the test clock signal to the clock input pin of the DUT, and applying the test pattern signals to data pins of the DUT. When the frequency of the test pattern signals is changed, the test clock signal frequency may be adjusted to calibrate to the changed frequency of the test pattern signals by re-programming the programmable dividers.

Abstract: A coupling in a metrology system for placement between a floating inspection chamber and a fixed transfer chamber. The coupling prevents transfer of vibrations between the chambers and seals a passage between the chambers. The coupling includes a first flange attached to the inspection chamber, a second flange not in contact with the first flange and attached to the transfer chamber, and a looped diaphragm having an outer peripheral edge region secured to the first flange and an inner peripheral edge region secured to the second flange to thereby couple the flanges together and close a space between the flanges. Clamps are provided for securing the outer and inner peripheral edge regions of the diaphragm to the first and second flanges, respectively.

Abstract: A system and method for identifying an optimal landing energy of a probe current in a scanning electron microscope system. A probe current having a known landing energy is directed at a sample for producing a signal electron beam. The current of the signal electron beam is measured by directing the beam to a current detector for calculating a current yield, which is the ratio of the signal current to the probe current. The landing energy can then be changed for subsequent measurements of the signal current to identify the landing energy which produces a desired current yield. Once identified, the landing energy value can be used to produce a signal electron beam directed towards an imaging detector to generate topographic images of samples.

Abstract: Method and apparatus for optically testing (e.g., using a laser beam) an operating integrated circuit (device under test—DUT) that actively control the operating temperature of the DUT. This is chiefly useful with flip-chip packaged ICs. The temperature of the DUT varies with its operating power consumption, and this fluctuation in temperature adversely affects the results obtained during optical probing or other optical testing. Furthermore, the DUT may be damaged if its temperature exceeds design limits. The temperature of the DUT is controlled by thermally contacting the exposed backside surface of the DUT die to a diamond film heat conductor, an associated heat sink structure, and at least one thermoelectric device. The thermoelectric device is controlled by a temperature sensor proximal to the DUT. By controlling the amount and direction of the electrical current supplied to the thermoelectric device in response to the sensed temperature, the temperature of the DUT is maintained.

Abstract: An apparatus for imaging the surface of a sample, such as a scanning electron microscope. The apparatus generates a beam of charged particles directed at the surface, and includes an objective lens and an electrostatic lens for controlling the particle beam. The objective lens and the electrostatic lens constitute a compound lens that has an axis. The beam is controlled so that it travels along the axis of the compound lens in order to avoid adverse consequences induced by, for example, mechanical misalignments and as manifested when the focus of one of the objective and electrostatic lenses is changed during operation of the apparatus.

Abstract: In order to improve the resolution of an electron beam in a scanning electron microscope or the like in which a Wien filter is employed for particle detection purposes, the beam is caused to have an envelope with a crossover point within, and preferably centrally located with respect to, the Wien filter.

Abstract: In instruments such as Wien filters, electrostatic and/or magnetic pole pieces must be mounted on and secured to a supporting structure with a very high degree of dimensional precision, usually by brazing. To that end, a fixture is provided for holding the parts to be assembled in precise relationship and to press the pole pieces into engagement with the supporting structure while the securing operation is being carried out. The pressing is accomplished by a gravity-produced force which is, therefore, independent of positional accuracies caused by very high temperatures, such as are encountered during brazing.

Abstract: A packet generator that increases the output speed of column and row addresses and data provided by a semiconductor device test system. The packet generator receives column and row addresses and data from a conventional algorithmic pattern generator (APG) and generates column and row addresses and data in packet form, thereby allowing communications with a packet-based device under test, such as a memory. The packet generator further provides variable time spacing between column and row addresses and data packets. Thereby, the packet generator advantageously allows testing of memory devices that require signal inputs at a higher rate than a conventional APG can provide.

Abstract: A method and associated apparatus for testing devices outputting source synchronous signals using automated test equipment (“ATE”). An output data signal and an output clock signal from such a source synchronous device under test are delayed using a delay network. The delay provides the time required to deskew path errors and to buffer and distribute the output clock signal. The output data signal appears relatively stable to the ATE by reading the output data signal using the output clock signal.

Abstract: A fixture and method is provided for aligning optical elements in a microscope. The fixture attaches to an objective lens plane of the microscope and supports an alignment optical element. During optical component alignment, an alignment beam is directed along the illumination and imaging paths of the microscope through the objective lens port and into the fixture for reflection by the alignment optical element. The fixture allows an alignment optical element positioned in a single location to be used for aligning the microscope components and for adjusting the microscope objective lens.

Abstract: Apparatus and method for exposing a selected feature of an integrated circuit device such as a selected portion of the metallization layer, from the backside of the integrated circuit substrate without disturbing adjacent features of the device such as the active semiconductor regions. This is performed using an FIB (focused ion beam) etching process in conjunction with observation by an optical microscope to form a trench through the substrate. The process includes a precise optical endpointing technique to monitor the remaining thickness of the semiconductor substrate at the floor of the trench. It is important to terminate etching of the trench so that the trench floor extends as close to the active semiconductor structures as desired and yet is not detrimental to device operation. This is done without introducing a need for any additional tool.

Abstract: An apparatus for imaging the surface of a sample, such as a scanning electron microscope. The apparatus generates a beam of charged particles directed at the surface, and includes an objective lens and an electrostatic lens for controlling the particle beam. The objective lens and the electrostatic lens constitute a compound lens that has an axis. The beam is controlled so that it travels along the axis of the compound lens in order to avoid adverse consequences induced by, for example, mechanical misalignments and as manifested when the focus of one of the objective and electrostatic lenses is changed during operation of the apparatus.

Abstract: A magnetic lens focuses a charged particle beam generated by an instrument to a very small spot for deriving characteristics of a sample. The magnetic flux pattern is created by splitting the winding coil into a primary coil and a secondary coil. This enables faster adjustment of the magnetic flux, and with improved resolution.

Abstract: An improved target and a technique for using it to measure registration relative to each other of more than two layers of a semiconductor wafer. At least first, second and third layers are formed to overlay each other. A first pattern is provided in a designated location of the first layer. A second pattern is provided in a designated location of the second layer, such second pattern having a given shape and a given size, and having at least one discontinuity formed therein at a predetermined location. A third pattern is provided in a designated location of the third layer, such third pattern having the given shape and the given size of the second pattern, and having at least one discontinuity formed therein at a predetermined location, wherein a portion of each one of the second and third patterns fits within the at least one discontinuity in the other when the second and third layers are in registration with each other.

Abstract: A charged particle filter such as a Wien filter in which components used as the pole pieces and electrodes are precisely and reliably secured to a supporting structure through which they extend and to which they are brazed. Electrical insulating gaps in the magnetic circuit are located very remotely from the pole faces of the pole pieces so as to minimize any adverse effect of the gaps on the produced magnetic field.

Abstract: Semiconductor wafers are held in position within a transfer chamber as it is subjected to pressurization and depressurization during transfer of the wafers between ambient atmosphere and an inspection chamber which is maintained at vacuum pressure. The transfer chamber is interposed between the ambient atmosphere and the inspection chamber. A paddle is arranged in the transfer chamber and has a wafer-receiving surface with openings formed therein adapted to be covered by a wafer. A vacuum actuated system draws the wafer to the wafer-receiving surface of the paddle by providing suction at the openings. Since the wafer is thus drawn to the paddle, the wafer is securely retained on the paddle during depressurization and repressurization of the transfer chamber. To further inhibit motion during repressurization, gas is backfilled into the transfer chamber through a diffuser as a laminar flow.

Abstract: Tester edge placement accuracy (EPA) is important for testing of semiconductor component devices. The value of that accuracy is quantified to the device manufacturer in terms of yield loss and bad parts sold as good parts (escapes in DPM). A simulation is presented that models the tester accuracy, the device edge distribution and their interaction for a example device having an operating speed of 800 Mbps. The same model can be applied for microprocessors or other parts that operate near the limits of ATE performance. In an example given, the estimated losses due to lack of appropriate tester accuracy are considerable: with the estimated yields and selling prices for the example device, the model shows a value of over $1 M for every 1 ps of enhanced tester edge placement accuracy.

Abstract: Noise in digitized image data is reduced by providing an array of pixels for each of which a gray level has been determined. For each column of the array, a distribution of gray levels is derived, and a range of acceptable gray levels is set based on the distribution. For pixels with a gray level outside the range, the gray level is changed to reduce the influence of noise in the imaged data.

Abstract: A process for manufacturing an electrostatic element for steering a charged particle beam. A cylindrical, non-conductive body having a bore therethrough is assembled with a cylindrical, conductive core also having a bore therethrough and sized to fit within the bore of the body. The core is secured within the bore of the body, and then longitudinally extending slots are cut completely through the core to create pole pieces that are electrically isolated from each other.

Abstract: Methods are provided for exposing a selected feature of an IC device, such as a selected conductor, from the back side of the substrate without disturbing adjacent features of the device, such as active regions. One such method comprises: (a) determining a region of the IC device in which the selected feature is located; (b) acquiring from the back side of the substrate an IR optical microscope image of the region; (c) aligning the IR optical microscope image with a coordinate system of a milling system; and (d) using structures visible in the IR optical microscope image as a guide, operating the milling system to expose the selected feature from the back side of the IC device without disturbing adjacent features.