Abstract: Provided are an electric resistance measuring apparatus for circuit boards, and an electric resistance measuring method using the same. An electric resistance measuring apparatus includes a one-side inspection circuit board having a plurality of connecting electrodes, and layer connector members provided on the inspection circuit board and formed of a conductive elastomer. Each of the layer connector members is brought into simultaneous contact with a plurality of connecting electrodes at one side thereof to be electrically connected thereto, and at the other side thereof, brought into simultaneous contact with a plurality of electrodes to be inspected to be electrically connected thereto. In this measurable state, two connecting electrodes are used for current supply and for voltage measurement, thereby performing measurement of electric resistance on a specified electrode to be inspected.

Abstract: A test interconnect, a test method, a test carrier, and a test system for testing semiconductor components are provided. The interconnect includes a substrate, and a pattern of interconnect contacts on the substrate for electrically engaging terminal contacts on a component under test. At least one pair of interconnect contacts comprise resistivity contacts configured for electrically engaging interconnected terminal contacts, such as Vss or Vcc contacts, on the component. The resistivity contacts include test pads arranged as a four terminal Kelvin structure. A resistivity measuring circuit can be electrically connected to the test pads for evaluating a total resistance Rx between the resistivity contacts. Using the total resistance Rx, and a standard based on prior resistance measurements, the contact resistances between the resistivity contacts, and the interconnected terminal contacts on the component can be quantified.

Abstract: There is provided a method and system for evaluating a condition of a surface of a combustion vessel exposed to deposition thereon of a material released during a combustion of a fuel in the combustion vessel during a combustion process. The method preferably comprises the steps of imposing a current on an electrical network arranged relative to the combustion vessel and having at least one electrode and thereafter detecting at least one characteristic of the electrical network during the step of imposing a current on the electrical network. The method further includes the step of evaluating a condition of the deposition exposed surface based upon the at least one detected characteristic of the electrical network.

Abstract: The invention allows for measurement at the same density as an actual device pattern and measures the level of registration of actual patterns with precision. In the measurement of the invention, a first exposure process is performed on a first-level pattern and a second exposure process is then performed on a second-level pattern. After that, the patterns are developed and etched, thereby forming two patterns of different shapes. Next, the resistance between terminals of a pattern which are obtained by means of etching is measured through a four-point measurement. An amount of misregistration of the first-level pattern and the second-level pattern is calculated from the measured resistance.

Abstract: A substrate, preferably constructed of a ductile material and a tool having the desired shape of the resulting device for contacting contact pads on a test device is brought into contact with the substrate. The tool is preferably constructed of a material that is harder than the substrate so that a depression can be readily made therein. A dielectric (insulative) layer, that is preferably patterned, is supported by the substrate. A conductive material is located within the depressions and then preferably lapped to remove excess from the top surface of the dielectric layer and to provide a flat overall surface. A trace is patterned on the dielectric layer and the conductive material. A polyimide layer is then preferably patterned over the entire surface. The substrate is then removed by any suitable process.

Abstract: A method and apparatus for measuring impedance of grounding system wherein a transient electric current is injected at the ground system under test while measuring the a transient ground potential difference, as well as the injected electric current. The ground potential difference is measured with respect to several points on the earth's surface at small distances from the test system. These measurements are processed by computer software which filters noise, corrects voltage and current transducer errors, and estimates the test system ground potential rise with respect to remote earth. Correction algorithms are used to remove irregularities in the frequency response of the voltage and current transducers and analog filters. The filtered and corrected measurements are used to estimate the ground impedance as a function of frequency. For this purpose, a parameter estimation procedure is used which takes into consideration the geometric arrangement of the voltage and current probes.

Abstract: An innovative multi-dimensional, low frequency, impedance measurement probe array, measurement system, and method are disclosed for detecting flaws in conductive articles. The device and method provide for contacting a conductive article with an multi-probe array of current and voltage probes, injecting current sequentially through a plurality of current probe pairs and measuring absolute or relative voltages with a plurality of voltage probes and voltage probe pairs across the surface of an article for each current flow condition. The device and method further provide for constructing a voltage profile across the surface of an article where disruptions in the voltage profile enable detection of the presence, location and orientation of flaws for flaw sizes as low as 20 um.

Abstract: The use of Electrical Impedance Tomography (EIT) to map subsurface hydraulic conductivity. EIT can be used to map hydraulic conductivity in the subsurface where measurements of both amplitude and phase are made. Hydraulic conductivity depends on at least two parameters: porosity and a length scale parameter. Electrical Resistance Tomography (ERT) measures and maps electrical conductivity (which can be related to porosity) in three dimensions. By introducing phase measurements along with amplitude, the desired additional measurement of a pertinent length scale can be achieved. Hydraulic conductivity controls the ability to flush unwanted fluid contaminants from the surface. Thus inexpensive maps of hydraulic conductivity would improve planning strategies for subsequent remediation efforts. Fluid permeability is also of importance for oil field exploitation and thus detailed knowledge of fluid permeability distribution in three-dimension (3-D) would be a great boon to petroleum reservoir analysts.

Abstract: Measuring an electrical potential in a semiconductor element by applying one or more voltages over the semiconductor element, placing at least one conductor in contact with the semi-conductor element using a scanning proximity microscope while injecting a substantially zero current in the semiconductor element with the conductor, measuring an electrical potential in the conductor while injecting a substantially zero current in the semiconductor element with the conductor, changing the position of the conductor, and repeating the measuring and changing steps.

Abstract: A thin-film depositing apparatus of the present invention deposits a sputtered film on a substrate in a sputtering chamber, and removes the substrate having the sputtered film deposited thereon from the sputtering chamber via a load-lock chamber by a robot arm. As a system for controlling the sheet resistance of the sputtered film deposited on the substrate, a measuring device using an eddy current method is mounted in the proximity of a substrate outlet of the load-lock chamber and measures the sheet resistance of the sputtered film of the substrate removed from the substrate outlet. With this structure, it is possible to provide a thin-film depositing apparatus which stably measures the sheet resistance of a thin film deposited on a substrate and performs feedback of the measurement result to control the film deposition conditions so that a thin film to be deposited on a subsequent substrate has a desired thickness.

Abstract: An instrument for measuring the resistance of liquid paints and the surface resistance of articles to be coated electrostatically, includes a voltage multiplier circuit that multiplies a periodic low voltage signal to generate a resistance measuring voltage applied to first and second electrodes for resistance measurements. The electrodes are coupled to differential inputs of an A/D converter having an oscillator output for supplying the periodic low voltage signal to the multiplier circuit. Resistance, voltage and current measuring circuits are alternately switchable between the electrodes and the differential inputs of the A/D converter for measuring resistance, voltage and current, the results of which are displayed visually.

Abstract: A system for automatic spreading resistance profiling of wafer specimens. The system comprises a positioning stage for positioning the specimens for contact by probe tips and alternately a probe conditioning fixture or a sample calibration fixture. The system further comprises a programmed computer for controlling the positioning stage to effect automatic specimen profiling, probe tip conditioning, and calibration.

Abstract: Conditions in a fluidized bed are measured with a probe and a circuit. The bed can be a polymerization reactor's reaction chamber, and the conditions can result in "sheeting" which is the build up of polymer on the chamber walls. The probe protrudes into the bed and detects a current which generally is a function of at least the impact and charge of particulates in the bed. The current detected by the probe is related to the conditions in the bed. The circuit measures the detected current. The probe has an inner probe piece of metallic material within an insulator of polymeric material. A portion of the insulator protrudes a first distance into the bed, and a portion of the inner probe piece protrudes a second distance into the bed. The first distance is less than or equal to the second distance. The insulator typically does not extend as far into the bed as the inner probe piece.

Abstract: A contact resistance check circuit and method for verifying that a sufficient electrical connection is established between a source and a sense lead of a Kelvin connection. The circuit includes a microprocessor for driving a transformer that is connected to the source/sense probe (i.e., contact resistance) with an input pulse. The input pulse is altered in relation to the magnitude of the contact resistance to produce a check pulse. A comparator is used to compare the check pulse with a threshold voltage and for generating a fault indication signal. A flip flop then stores the fault indication signal so that the fault indication signal may be monitored by the microprocessor.

Abstract: An NO.sub.x sensor is produced by sintering a plurality of columnar crystals of .beta.-type Nb.sub.2 O.sub.5. The average value M of aspect ratios b/a (wherein a represents a width and b represents a length) in the columnar crystals is set in a range of 2.11<M.ltoreq.5. The NO.sub.x sensor has a high sensitivity to NO.sub.x via an enhancement attained by control of crystal type and structure.

Abstract: The fluid conductivity sensor disclosed herein is adapted for the non-contacting measurement of fluid conductivity and utilizes first and second insulating tubes, each of which is provided with both the driving transformer and the sensing transformer. The sensor is immersed in the fluid to be tested so that the tubes fill with the fluid. The driving transformer's are oppositely poled so that the current induced in one tube tends to return through the other tube. Shrouds are provided which link the corresponding ends of the tubes and operate to obstruct in-fluid current flow not linking both of the tubes. Accordingly the influence of objects nearby in the fluid is substantially eliminated.

Abstract: A film deposition control system and method in which a deposition rate monitor and an ellipsometer are used to control the thickness of a thin film being deposited on a wafer. The ellipsometer is also used to detect the refractive index of the thin film being deposited, and the detected refractive index value is used to control the ratio of the reactive gases being injected into the processing chamber.

Abstract: An electronic module tester measures the difference between the voltage provided by the tester during testing and the voltage actually delivered to an electronic device. The difference corresponds to a voltage drop associated with the contamination contact resistance. This resistance builds up on contact surfaces of the tester as many modules are inserted and extracted. One power line and one ground line from the electronic module are isolated and connected to a voltmeter for a direct measurement of voltage on the device. A comparison is made with the power supply voltage provided by the tester to the device under test. A voltage difference exceeding a predetermined value initiates further action prior to continued testing, such as contact cleaning.

Abstract: A method and apparatus for measuring sheet resistance and thickness of thin films and substrates. A four-point probe assembly engages the surface of a film on a substrate, and the thickness of the substrate is determined from the point of contact between the probes and film. A measuring apparatus then outputs a voltage waveform which applies a voltage to probes of the probe assembly. An inverter inverts the voltage and provides the inverted voltage on another probe of the probe assembly, thus inducing a current in these probes of the four point probe and through the surface of the film. Two other probes measure a voltage in the film created by the current. The voltages on the current probes provide a voltage close to zero at the other probes, thus allowing these other probes to measure voltages with greater precision. The current created by the voltage waveform and the voltage created across the inner probes are measured for each voltage level of the waveform.

Abstract: An improved area monitor for detecting gas concentration is provided that requires a very infrequent calibration, and works reliably in detecting a particular target gas using only two semiconductor sensors. One of these sensors will exhibit a drift that is constantly monitored and automatically compensated for, while the other sensor exhibits a stable, repeatable response over very long periods of time. Once the "stable" has been initially calibrated, the concentration of the target gas can be discerned directly from the resistance of this sensor, although more that one particular chemical gas may cause the stable sensor to change resistance. The second sensor is then used to discern whether or not the change in resistance of the stable sensor was due to the actual target chemical, or due to some other similar chemical. The second sensor is selected to be of a type that responds in one direction (i.e.

Abstract: A sensing device and a method for sensing the presence and absence of an object in a machine using the sensing device. The sensing device generally including a sensing mechanism, a resistive element, and a control mechanism communicatively coupled to the sensing mechanism and resistive element. The sensing mechanism being coupled to the resistive element. The method comprising actuating the sensing mechanism so that it senses the location of the object. Recording the voltage across the resistive element in the control mechanism when the sensing mechanism senses the location of the object. Reactuating the sensing mechanism at least one more time to sense the location of the object. Measuring a subsequent voltage across the resistive element when the sensing mechanism is reactuated and comparing the subsequent voltage with the recorded voltage across the resistive element when the resistive element sensed the location of the object.

Abstract: A circuit for measuring alternating current (a.c.) and direct current (d.c.) in a conductor without breaking the conductor is provided. A modulated current source is coupled in parallel with a segment of the conductor to inject a test current. A synchronous demodulator is also coupled in parallel across the segment to separate the test voltage drop induced by the test current from the voltage drop due to the current in the conductor. The test voltage drop and the voltage drop are measured by a voltmeter and the resistance of the segment and the current flowing through the segment can then be calculated.

Abstract: An apparatus for rotary signal coupling in in-situ monitoring of a chemical-mechanical polishing process by a polisher is provided with a sensor fixed to a rotatable wafer carrier for creating a signal responsive to the chemical mechanical polishing process, a conductor coupled to the sensor for receiving the signal, the conductor fixed to the rotatable wafer carrier, a contact coupled to the conductor, the contact fixed to a stationary drive arm, and signal transfer means coupled to the contact for transferring the signal to a monitoring means.

Abstract: A probe for electrical contact with a metal layer of an integrated circuit wherein the probe features a polycrystalline diamond layer coating a fine conductive wire. The diamond coating has exposed pyramidal facets having a density of at least 2000 per square millimeter. The substrate has a radius exceeding one micrometer.

Abstract: Two electrical wires are connected to the surface of an electrically conductive solid body at two measurement points located on either side of a crack in the surface of the body. The two wires form a thermoelectric couple. A constant DC current is applied to the body. The two wires are connected to a device for measuring the extent of the crack and another device for measuring the temperature of the crack. By measuring the potential difference during application and interruption of the DC electric current to the body, it is possible to simultaneously obtain a measurement of the extent of the crack and a measurement of the temperature of the crack.

Abstract: A method of testing series passive components in electronic assemblies. Only one test pin per passive component is required, thereby reducing the cost and complexity of test fixtures and the electronic assemblies. A passive component is connected between the output of a driving circuit and (optionally) an input of a receiving circuit. The output of the driving circuit is placed in a low impedance state. The receiving end of the passive component is stimulated and the response is measured. For reactive components, the stimulus and response are AC. For resistors, multiple DC measurements may be made. A optional DC bias may be provided to limit DC current and to further reduce the small signal output impedance of the driving circuit.

Abstract: A micromechanical sensor in which the impedance of a gap in a conductor, under tunnelling current conditions, is sensed to provide an indication of deflection in the conductor. This provides a new way to sense acceleration, strain, and other parameters which can be translated into a deflection.

Abstract: A method of manufacturing a nitrogen oxide sensor for detecting a nitrogen oxide to be used in the field of e.g. reducing or decomposing nitrogen oxides, as well as such sensor and material suitable for manufacturing the sensor are disclosed. For manufacturing the sensor material, a precursor containing components for constituting the sensor material in a predetermined equivalent ratio of stoichiometry between chemical elements is prepared. First, the precurser is subjected to sintered to a preliminary sintering step. Then, the resultant sintered material is subjected to at least two cycles of main sintering step at 815.degree. to 848.degree. C. (T1) with an intermediate grinding step of the sintered material therebetween, thus obtaining the gas detecting portion comprised mainly of oxide compound having a composition represented by:Bi.sub.2 Sr.sub.2 YCu.sub.2 O.sub.8+y(0.ltoreq.y.ltoreq.1)and having the 2212 phase of crystal structure.

Abstract: The change in thickness of a film on an underlying body such as a semiconductor substrate is monitored in situ by inducing a current in the film, and as the thickness of the film changes (either increase or decrease), the changes in the current are detected. With a conductive film, eddy currents are induced in the film by a generating an alternating electromagnetic field with a sensor which includes a capacitor and an inductor.

Abstract: Measuring an electrical potential in a semiconductor element by applying one or more voltages over the semiconductor element, placing one or more conductors in contact with the semi-conductor element using a scanning proximity microscope, calibrating the contact force between the conductors and the semiconductor element and measuring an electrical potential in the semi-conductor element with at least one of the conductors while injecting a substantially zero current in the semiconductor element. To measure the electrical potential distribution within the semiconductor, the position of at least one of the conductors is changed and the electric potential re-measured.

Abstract: Apparatus and methods for measuring the sheet resistance of an electrically conductive film on a semiconductor substrate while maintaining the substrate within the vacuum environment of the semiconductor process apparatus. In one aspect of the invention, the conductive film is deposited on the substrate within a vacuum chamber, and the resistance probe is located within the same chamber. The probe retracts out of the way during deposition of the film, and then moves to the substrate to measure the resistance of the film after deposition is paused or completed. In a second aspect of the invention, the probe is located in a chamber other than the chamber which deposits the conductive film.

Abstract: Imaging instruments for inspecting products, such as semiconductor chips, e calibrated by providing a reference test structure having features which can be located by electrical measurements not subject to tool-induced shift and wafer-induced shift experienced by the imaging instrument, and by the imaging instrument. The reference test structure is first qualified using electrical measurements, and is then used to calibrate the imaging instrument. The electrical measurements are made by forcing a current between a plurality of spaced reference features and a pair of underlying conductors. Conductive connectors formed in vias in an insulating layer overlying the pair of conductors and individually connected to a respective conductive element formed on the insulating layer are each spaced at progressively greater distances relative to the centerline of the space between the pair of conductors, such that a null-overlay element may be identified.

Abstract: A method and apparatus for measuring sheet resistance and thickness of thin films and substrates. A four-point probe assembly engages the surface of a film on a substrate, and the thickness of the substrate is determined from the point of contact between the probes and film. A measuring apparatus then outputs a voltage waveform which applies a voltage to probes of the probe assembly. An inverter inverts the voltage and provides the inverted voltage on another probe of the probe assembly, thus inducing a current in these probes of the four point probe and through the surface of the film. Two other probes measure a voltage in the film created by the current. The voltages on the current probes provide a voltage close to zero at the other probes, thus allowing these other probes to measure voltages with greater precision. The current created by the voltage waveform and the voltage created across the inner probes are measured for each voltage level of the waveform.

Abstract: A sensing device and a method for sensing the presence and absence of an object in a machine using the sensing device. The sensing device generally including a sensing mechanism, a resistive element, and a control mechanism communicatively coupled to the sensing mechanism and resistive element. The sensing mechanism being coupled to the resistive element. The method comprising actuating the sensing mechanism so that it senses the location of the object. Recording the voltage across the resistive element in the control mechanism when the sensing mechanism senses the location of the object. Reactuating the sensing mechanism at least one more time to sense the location of the object. Measuring a subsequent voltage across the resistive element when the sensing mechanism is reactuated and comparing the subsequent voltage with the recorded voltage across the resistive element when the resistive element sensed the location of the object.

Abstract: A system to sense changes in the state of an ion exchange resin bed which includes first and second current electrodes spaced from each other, a first electrical circuit electrically connecting the current electrodes and designed to be connected to a source of alternating current, and also including first and second voltage probes spaced from each other and located approximately between said first and second current electrodes with a wire connecting voltage probes. A second electrical circuit consists of the first and second voltage probes, the wire and the portion of the resin bed lying between said voltage probes so that when the first electrical circuit is energized by the source of alternating current a voltage is induced in the second electrical circuit which corresponds to the state of the resin bed located between the first and second voltage probes.

Abstract: A hydrogen sensitive metal alloy contains palladium and titanium to provide a larger change in electrical resistance when exposed to the presence of hydrogen. The alloy is deposited on a substrate and a thin film and connected across electrical circuitry to provide a sensor device that can be used for improved sensitivity and accuracy of hydrogen detection.

Abstract: Rotary signal coupling in in-situ monitoring of a chemical-mechanical polishing process. A sensor fixed to a rotatable wafer carrier for creating a signal responsive to the chemical mechanical polishing process is coupled to a bottom half of a rotary transformer fixed to a rotating portion of the polisher. A top half of the rotary transformer, coupled to the bottom half of the rotary transformer, is fixed to a stationary portion of the polisher. The signal from the sensor is thus coupled through the rotary transformer to a process monitor.

Abstract: The change in thickness of a film on an underlying body such as a semiconductor substrate is monitored in situ by inducing a current in the film, and as the thickness of the film changes (either increase or decrease), the changes in the current are detected. With a conductive film, eddy currents are induced in the film by a generating an alternating electromagnetic field with a sensor which includes a capacitor and an inductor.

Abstract: A method and apparatus are provided for determining the endpoint for chemical mechanical polishing a film on a wafer. First, a reference point polishing time indicating when a breakthrough of the film has occurred is determined, then an overpolishing time indicating an interval between the reference point polishing time and when the film has been completely polished is determined. To get the total polishing time to the endpoint, the reference point polishing time and the overpolishing time are added.

Abstract: Apparatus for measuring the surface resistance and electrical resistivity of a homogeneous, resistive material sample includes a measuring cell having a sample location able to receive the sample and several electrodes in the form of knives placed on the same side of the sample and guided in an insulating block whose ends are positioned on the sample, the pressure necessary for establishing good electrical contacts between the electrodes and the sample being ensured by a shim which urges the electrodes toward the sample. A first pair of the electrodes make it possible to inject a current into a sample to be tested and a second pair of the electrodes make it possible to collect a voltage from the sample.

Abstract: A method and apparatus for endpoint detection in removal of a film from a semiconductor wafer is provided, with a sensor for creating a signal responsive to the film removal process, a positive feedback amplifier coupled to the sensor, the positive feedback amplifier having a mode selector, and an analyzer coupled to the positive feedback amplifier.

Abstract: A method and apparatus for measuring the electrical resistance of a circuit energized with AC power. The invention imposes a known DC current in the circuit under test and senses a resulting DC voltage drop that corresponds to the resistance of the circuit. The invention senses AC overvoltage conditions in the circuit under test and electrically isolates the measuring circuit from the circuit under test.

Abstract: An impedance meter enables a real value of a component's impedance value to be forced to be negative when contact between measurement terminals and the component is poor. The value of the real part of the measured value is compared with a standard value for judging whether the contact is good or bad. The contact is judged poor when the real part of the measured value is more negative than the standard value. The standard value for judging whether the contact is good or bad is made more negative than the magnitude of the dispersion of the real part of the measured values, and thus erroneous judgments due to dispersion of measured values are eliminated. The circuit that forces the real part of the measured value to become negative is formed as follows: the input of an inverse gain amplifier is connected to the output terminal of a signal generator, the output of the inverse gain amplifier is connected to a high-voltage voltage terminal through a resistance.

Abstract: A metal-insulator-semiconductor diode sensor having a Pt/Ir alloy and/or a Pt/Sn alloy electrode is sensitive to and can detect ethylene. An array of metal-insulator-semiconductor diode sensors having varying sensitivity responses can indicate a fault in an electrical transformer by the detection of at least one of the key fault gases CO, H.sub.2, C.sub.2 H.sub.2 and C.sub.2 H.sub.4.

Abstract: A novel substrate for growth of material by chemical phase deposition includes a temperature monitoring zone formed by applying a coating of growth preventing material (e.g., SiO.sub.x or SiN.sub.x) to a portion of the substrate. The temperature of the substrate can be monitored during growth of a desired material using an optical pyrometer having its field of view directed at the temperature monitoring zone.

Abstract: A method for measuring the resistance or conductivity between two or more conductors which are placed against a semiconductor element, the conductors are placed either in contact with the top surface or one conductor is placed in contact with the top surface and the other conductor is in the form of a large ohmic contact applied to the bottom surface of the semiconductor element. In order to bring the contact resistance between the top conductor(s) and the element to, and hold it at, a predetermined value during measuring, the conductor(s) are held at a constant distance and/or under constant pressure relative to the semiconductor element by use of a scanning proximity microscope. The top conductor may have a boron implanted diamond tip. The carrier profile of the semiconductor element is determined from previously derived calibration curves.

Abstract: An apparatus is disclosed for determining the concentration of a fluid. In one aspect of the invention an apparatus for detecting the ionic concentration of a fluid is provided. The ionic concentration detecting apparatus may include a resonance coil or other suitable receiver that arranged to be influence by the fluid being monitored. The resonance coil is driven by a high frequency signal having a frequency in the range of 10-100 MHz. A detector is provided to measure the losses experienced by the resonance coil. In another aspect of the invention, an ultrasonic based density detecting apparatus for detecting the density of the fluid is provided. The ionic concentration detecting device may be used in conjunction with the density determining device to provide concentration detecting capabilities for solutions having multiple constituents.

Abstract: A sensor for measuring moisture changes in soil and having an electrically insulating cylindrical body along which bare electrical conductors are placed. A transmitter produces constant alternating current which is supplied to the sensor. The voltage which this current creates in the soil is detected by the electrical conductors on the sensor and is fed to a receiver. The receiver consists of electronic circuitry for determining the necessity for allowing irrigation to occur, and if so, switches on a solenoid controlling the water supply. When the sensor indicates sufficient irrigation has occurred, the electronic controls switch the irrigation off. A tube sensor comprising rigid metal tubes of equal length and secured by end members such that no two tubes touch is also provided, for example to measure moisture content changes of any granular material.

Abstract: A system for lapping a magnetoresistive (MR) sensor on a slider to a proper height is disclosed. The system comprises simultaneously lapping the MR lap monitor and the MR sensor positioned on the slider until a resistance of a variable resistor located within the MR lap monitor is approximately equal to a resistance of a target resistor located within the MR lap monitor. During the lapping process, a reference resistor located within the lap monitor is compared to both the variable and target resistors to prevent a lapping failure. In one preferred embodiment, the reference, target, and variable resistors are formed from a ferromagnetic metal alloy. The MR lap monitor and the MR sensor are lapped until a height of the ferromagnetic metal alloy forming the variable resistor is approximately equal to a height of the ferromagnetic metal alloy forming the target resistor.

Abstract: The change in thickness of a film on an underlying body such as a semiconductor substrate is monitored in situ by inducing a current in the film, and as the thickness of the film changes (either increase or decrease), the changes in the current are detected. With a conductive film, eddy currents are induced in the film by a generating an alternating electromagnetic field with a sensor which includes a capacitor and an inductor.