Electron beam specimen analysis

Claim 1

A method of analysing a specimen comprising the steps of: scanning the specimen by an electron beam to produce a first electrical signal of the type normally requiring integration over many fields before reliable information is obtained for analysis, detecting specimen current or voltage variations produced as the electron beam scans across regions in the specimen which have differing electrical properties, converting detected specimen current or voltage variations into a second electrical signal the amplitude of which varies as different regions of said specimen are scanned, and which represents regions of said specimen having differing electrical properties; comparing the amplitude excursions of the second signal with a reference signal and detecting any amplitude excursions which exceed the reference signal, generating signal pulses from the detected excursions, said signal pulses representing borders of said regions of said specimen having differing electrical properties; gating said first signal by said signal pulses or pulses derived therefrom inhibit the passing of said first signal for analysis excePt when the amplitude of said second signal is sufficient to exceed said reference signal, so that said first signal is gated for analysis only in regions of said specimen having said differing electrical properties, whereby the need for integrating said first signal over many fields is eliminated; wherein the first signal is obtained from an X-ray detector probe set to detect any X-ray emission from the specimen due to electron bombardment thereof and said second signal is derived from the variation of the specimen current during scanning, comparing the instantaneous amplitude of the second signal with a reference voltage, generating a signal pulse each time the amplitude exceeds the reference voltage, comparing the instantaneous amplitude of the second signal with a second reference voltage, inhibiting the generation of a signal pulse if the amplitude exceeds said second reference voltage, tuning the X-ray probe to preferentially select X-ray radiation of a given wavelength, counting the pulses from the X-ray probe, producing an electrical signal equivalent to the total number of pulses, accumulating the signal pulses, deriving from the total accumulated signal a measure of the total area of the region or regions of the specimen which produce amplitude excursions of the specimen current signal which exceed the reference voltage; and dividing the X-ray pulse count signal by the area signal.

Claim 2

A method of analysing a specimen comprising the steps of: scanning the specimen by an electron beam to produce a first electrical signal of the type normally requiring integration over many fields before reliable information is obtained for analysis, detecting specimen current or voltage variations produced as the electron beam scans across regions in the specimen which have differing electrical properties, converting detected specimen current or voltage variations into a second electrical signal the amplitude of which varies as different regions of said specimen are scanned, and which represents regions of said specimen having differing electrical properties; comparing the amplitude excursions of the second signal with a reference signal and detecting any amplitude excursions which exceed the reference signal, generating signal pulses from the detected excursions, said signal pulses representing borders of said regions of said specimen having differing electrical properties; gating said first signal by said signal pulses or pulses derived therefrom inhibit the passing of said first signal for analysis excePt when the amplitude of said second signal is sufficient to exceed said reference signal, so that said first signal is gated for analysis only in regions of said specimen having said differing electrical properties, whereby the need for integrating said first signal over many fields is eliminated; wherein the first signal is obtained from an X-ray detector probe set to detect any X-ray emission from the specimen due to electron bombardment thereof and said second signal is derived from the variation of the specimen current during scanning, comparing the instantaneous amplitude of the second signal with a reference voltage, generating a signal pulse each time the amplitude exceeds the reference voltage, comparing the instantaneous amplitude of the second signal with a second reference voltage, inhibiting the generation of a signal pulse if the amplitude exceeds said second reference voltage, tuning the X-ray probe to preferentially select X-ray radiation of a given wavelength, counting the pulses from the X-ray probe, producing an electrical signal equivalent to the total number of pulses, accumulating the signal pulses, deriving from the total accumulated signal a measure of the total area of the region or regions of the specimen which produce amplitude excursions of the specimen current signal which exceed the reference voltage; and dividing the X-ray pulse count signal by the area signal.

Claim 3

A method of analysing a specimen comprising the steps of: scanning the specimen by an electron beam to produce a first electrical signal of the type normally requiring integration over many fields before reliable information is obtained for analysis, detecting specimen current or voltage variations produced as the electron beam scans across regions in the specimen which have differing electrical properties, converting detected specimen current or voltage variations into a second electrical signal the amplitude of which varies as different regions of said specimen are scanned, and which represents regions of said specimen having differing electrical properties; comparing the amplitude excursions of the second signal with a reference signal and detecting any amplitude excursions which exceed the reference signal, generating signal pulses from the detected excursions, said signal pulses representing borders of said regions of said specimen having differing electrical properties; gating said first signal by said signal pulses or pulses derived therefrom to thereby inhibit the passing of said first signal for analysis except when the amplitude of said second signal is sufficient to exceed said reference signal, so that said first signal is gated for analysis only in regions of said specimen having said differing electrical properties, whereby the need for integrating said first signal over many fields is eliminated; wherein the first signal is obtained from an X-ray detector probe set to detect any X-ray emission from the specimen due to electron bombardment thereof and said second signal is derived from the variation of the specimen current during scanning, comparing the instantaneous amplitude of the second signal with a reference voltage, generating a signal pulse each time the amplitude exceeds the reference voltage, comparing the instantaneous amplitude of the second signal with a second reference voltage, inhibiting the generation of a signal pulse if the amplitude exceeds said second reference voltage, tuning the X-ray probe to preferentially select X-ray radiation of a given wavelenght, counting the pulses from the X-ray probe, producing an electrical signal equivalent to the total number of pulses, accumulating the signal pulses, deriving from the total accumulated signal a measure of the total area of the region or regions of the specimen which produce amplitude excursions of the specimen current signal which exceed the reFerence voltage, wherein the signal pulses arising from scanning each distinct region of a specimen surface are accumulated separately and a separate area signal is generated for each region, the pulses from the X-ray probe are likewise accumulated separately for each distinct region of the specimen surface, as determined by the separate area signals, and a separate X-ray pulse count is generated for each distinct area, and wherein the area signal and X-ray pulse count signal for each region are released simultaneously and the latter is divided by the area signal.

Claim 4

A method of analysing a specimen comprising the steps of: scanning the specimen by an electron beam to produce a first electrical signal of the type normally requiring integration over many fields before reliable information is obtained for analysis, detecting specimen current or voltage variations produced as the electron beam scans across regions in the specimen which have differing electrical properties, converting detected specimen current or voltage variations into a second electrical signal the amplitude of which varies as different regions of said specimen are scanned, and which represents regions of said specimen having differing electrical properties; comparing the amplitude excursions of the second signal with a reference signal and detecting any amplitude excursions which exceed the reference signal, generating signal pulses from the detected excursions, said signal pulses representing borders of said regions of said specimen having differing electrical properties; gating said first signal by said signal pulses or pulses derived therefrom to thereby inhibit the passing of said first signal for analysis except when the amplitude of said second signal is sufficient to exceed said reference signal, so that said first signal is gated for analysis only in regions of said specimen having said differing electrical properties, whereby the need for integrating said first signal over many fields is eliminated; wherein the first signal is obtained from an X-ray detector probe set to detect any X-ray emission from the specimen due to electron bombardment thereof and said second signal is derived from the variation of the specimen current during scanning, comparing the instantaneous amplitude of the second signal with a reference voltage, generating a signal pulse each time the amplitude exceeds the reference voltage, comparing the instantaneous amplitude of the second signal with a second reference voltage, inhibiting the generation of a signal pulse if the amplitude exceeds said second reference voltage, tuning the X-ray probe to preferentially select X-ray radiation of a given wavelenght, counting the pulses from the X-ray probe, producing an electrical signal equivalent to the total number of pulses, accumulating the signal pulses, deriving from the total accumulated signal a measure of the total area of the region or regions of the specimen which produce amplitude excursions of the specimen current signal which exceed the reFerence voltage, wherein the signal pulses arising from scanning each distinct region of a specimen surface are accumulated separately and a separate area signal is generated for each region, the pulses from the X-ray probe are likewise accumulated separately for each distinct region of the specimen surface, as determined by the separate area signals, and a separate X-ray pulse count is generated for each distinct area, and wherein the area signal and X-ray pulse count signal for each region are released simultaneously and the latter is divided by the area signal.