US5706094A — Ultrafast optical technique for the characterizat…

Claim 1

Independent Claim 163 words

Apparatus for examining a semiconductor sample having at least one localized region underlying a surface into which a chemical species may have been introduced, comprising: optical means for generating optical pump pulses having a wavelength selected for generating a population of charge carriers in said sample, said charge carriers diffusing within and recombining in said sample and said localized region and inducing at least one transient time-varying change in optical constants of the sample at a location at or near to the surface of the sample, said optical means further being operable for generating an optical probe beam; means for measuring a response of the sample to said optical probe beam at least during a time that the optical constants are varying; and means for associating the measured response with at least one of chemical species concentration, chemical species type, implant energy, a presence or absence of an introduced chemical species region at the location, and a presence or absence of implant-related damage.

Claim 2

Dependent Claim 163 words

Apparatus for examining a semiconductor sample having at least one localized region underlying a surface into which a chemical species may have been introduced, comprising: optical means for generating optical pump pulses having a wavelength selected for generating a population of charge carriers in said sample, said charge carriers diffusing within and recombining in said sample and said localized region and inducing at least one transient time-varying change in optical constants of the sample at a location at or near to the surface of the sample, said optical means further being operable for generating an optical probe beam; means for measuring a response of the sample to said optical probe beam at least during a time that the optical constants are varying; and means for associating the measured response with at least one of chemical species concentration, chemical species type, implant energy, a presence or absence of an introduced chemical species region at the location, and a presence or absence of implant-related damage.

Claim 3

Dependent Claim 20 words

Apparatus as set forth in claim 1, wherein said optical means is comprised of means for generating probe beam pulses.

Claim 4

Dependent Claim 22 words

Apparatus as set forth in claim 1, wherein said optical means is comprised of means for generating a continuous wave probe beam.

Claim 5

Dependent Claim 51 words

Apparatus as set forth in claim 1, wherein said pump beam pulses each have a duration in a range of approximately 0.01 picosecond to approximately 100 picoseconds, an energy of approximately 0,001 nJ to approximately 100 nJ per pulse, and a wavelength that is equal to approximately 200 nm or greater.

Claim 6

Dependent Claim 52 words

Apparatus as set forth in claim 1, wherein said measuring means is comprised of a detector that is positioned for receiving said optical probe beam after it impinges on the sample, and wherein said measuring means is further comprised of means for measuring a change in reflected intensity of the probe beam.

Claim 7

Dependent Claim 51 words

Apparatus as set forth in claim 1, wherein said measuring means is comprised of a detector that is positioned for receiving the probe beam after it impinges on the sample, and wherein said measuring means is further comprised of means for measuring a change in transmitted intensity of the probe beam.

Claim 8

Dependent Claim 52 words

Apparatus as set forth in claim 1, wherein said measuring means is comprised of a detector that is positioned for receiving the probe beam after it impinges on the sample, and wherein said measuring means is further comprised of means for measuring a change in a polarization state of the probe beam.

Claim 9

Dependent Claim 51 words

Apparatus as set forth in claim 1, wherein said measuring means is comprised of a detector that is positioned for receiving the probe beam after it impinges on the sample, and wherein said measuring means is further comprised of means for measuring a change in optical phase of the probe beam.

Claim 10

Dependent Claim 50 words

Apparatus as set forth in claim 1, wherein said measuring means is comprised of a detector that is positioned for receiving the probe beam after it impinges on the sample, and wherein said measuring means is further comprised of means for measuring a change in direction of the probe beam.

Claim 11

Dependent Claim 54 words

Apparatus as set forth in claim 1, wherein said measuring means is comprised of a detector that is positioned for receiving the probe beam after it impinges on the sample, and wherein said measuring means is further comprised of means for measuring a change in optical path length between the surface and the detector.

Claim 12

Dependent Claim 79 words

Apparatus as set forth in claim 1, wherein said optical means applies a plurality of pairs of optical pulses to the sample, each of the pairs of pulses comprising an optical pump pulse and an optical probe pulse, said probe pulse being delayed in time from said pump pulse by a delay time t D , wherein for at least some of the pairs of pulses t D is less than a charge carrier recombination time within the sample.

Claim 13

Dependent Claim 20 words

Apparatus as set forth in claim 11, and further comprising mechanical means for generating the time delay t D .

Claim 14

Dependent Claim 28 words

Apparatus as set forth in claim 12, wherein the mechanical means is comprised of a piezoelectric transducer that is coupled to a mirror that reflects said probe pulses.

Claim 15

Dependent Claim 28 words

Apparatus as set forth in claim 12, wherein the mechanical means is comprised of a shaker table that is coupled to a mirror that reflects said probe pulses.

Claim 16

Dependent Claim 62 words

Apparatus as set forth in claim 1, wherein said associating means is comprised of a digital data processor, wherein said digital data processor generates a curve that is a function of a change in the optical constants over time, and wherein said digital data processor compares the generated curve to at least one reference curve obtained from at least one reference sample.

Claim 17

Dependent Claim 63 words

Apparatus as set forth in claim 1, wherein said associating means is comprised of a digital data processor, wherein said digital data processor generates a curve that is indicative of a change in the optical constants over time, and wherein said digital data processor compares the generated curve to at least one reference curve that is calculated from a model of the sample.

Claim 18

Dependent Claim 46 words

Apparatus as set forth in claim 1, wherein said optical means generates a sequence of pump pulses at a frequency of f 1 , the sequence of pump pulses being intensity modulated at a frequency of f 2 , and wherein f 2 <f 1 .

Claim 19

Dependent Claim 43 words

Apparatus as set forth in claim 1, wherein said optical means generates a sequence of pump pulses at a frequency of f 1 and a sequence of probe pulses at a frequency of f 2 , and wherein f 2 ≢f 1 .

Claim 20

Dependent Claim 30 words

Apparatus as set forth in claim 1, wherein said optical means applies at least one of a pump pulse and a probe pulse to the surface through an optical fiber.

Claim 21

Dependent Claim 24 words

Apparatus as set forth in claim 1, wherein said measuring means includes an optical fiber for directing a reflected probe pulse to a photodetector.

Claim 22

Dependent Claim 55 words

Apparatus as set forth in claim 1, wherein said optical means is comprised of means for focussing a pump pulse and a probe pulse onto the surface, and wherein said focussing means is comprised of an optical fiber having a terminal end portion that is reduced in diameter over other portions of the optical fiber.

Claim 23

Dependent Claim 39 words

Apparatus as set forth in claim 1, wherein said optical means is comprised of a laser for generating optical pulses at a rate within a range of approximately 100 pulses per second to approximately 5×10 9 pulses per second.

Claim 24

Dependent Claim 28 words

Apparatus as set forth in claim 1, wherein said optical means is comprised of a single laser for generating an optical pump pulse and an optical probe pulse.

Claim 25

Dependent Claim 33 words

Apparatus as set forth in claim 1, wherein said optical means is comprised of a first laser for generating an optical pump pulse and a second laser for generating an optical probe pulse.

Claim 26

Dependent Claim 23 words

Apparatus as set forth in claim 1, wherein said optical means generates, for each optical pump pulse, a plurality of optical probe pulses.

Claim 27

Dependent Claim 24 words

Apparatus as set forth in claim 1, wherein said measurement means obtains measurements as a function of an amplitude of said optical pump pulses.

Claim 28

Dependent Claim 35 words

Apparatus as set forth in claim 1, wherein said optical means generates optical probe pulses, and wherein said optical pump pulses and said optical probe pulses are applied at an angle normal to said surface.

Claim 29

Dependent Claim 37 words

Apparatus as set forth in claim 1, wherein said optical means generates optical probe pulses, and wherein said optical pump pulses and said optical probe pulses are applied at an angle other than normal to said surface.

Claim 30

Dependent Claim 35 words

Apparatus as set forth in claim 1, wherein said optical means generates optical probe pulses, and wherein said optical pump pulses and said optical probe pulses are applied along a same axis to said surface.

Claim 31

Dependent Claim 35 words

Apparatus as set forth in claim 1, wherein said optical means generates optical probe pulses, and wherein said optical pump pulses and said optical probe pulses are applied along two different axes to said surface.

Claim 32

Dependent Claim 35 words

Apparatus as set forth in claim 1, wherein said optical means generates optical probe pulses, and wherein said optical pump pulses and said optical probe pulses are applied to a same location on said surface.

Claim 33

Dependent Claim 35 words

Apparatus as set forth in claim 1, wherein said optical means generates optical probe pulses, and wherein said optical pump pulses and said optical probe pulses are applied to two different locations on said surface.

Claim 34

Dependent Claim 41 words

Apparatus as set forth in claim 1, wherein said optical means generates optical probe pulses having a predetermined polarization state, and wherein said measuring means includes means for detecting ellipsometric parameters upon a reflection or transmission of said optical probe pulses.

Claim 35

Dependent Claim 80 words

Apparatus as set forth in claim 1, wherein said optical means generates sets of pump/probe pulses each comprising at least one optical pump pulse and at least one optical probe pulse, and wherein said measuring means includes means for detecting, from an oscillation in a change in at least one of intensity, polarization state, and optical phase of light reflected from or transmitted through said sample, at least an indication of an amount of lattice defects present in the sample.

Claim 36

Independent Claim 148 words

A method for examining a semiconductor sample having at least one localized region underlying a surface into which a chemical species may have been introduced, comprising the steps of: generating optical pump pulses having a wavelength selected for generating a population of charge carriers in the sample, the charge carriers diffusing within and recombining in the sample and the localized region and inducing at least one transient time-varying change in optical constants of the sample at a location at or near to a surface of the sample; measuring a response of the sample to an optical probe beam at least during a time that the optical constants are varying; and associating the measured response with at least one of chemical species concentration, chemical species type, implant energy, a presence or absence of an introduced chemical species region at the location, and a presence or absence of implant-related damage.

Claim 37

Independent Claim 148 words

A method for examining a semiconductor sample having at least one localized region underlying a surface into which a chemical species may have been introduced, comprising the steps of: generating optical pump pulses having a wavelength selected for generating a population of charge carriers in the sample, the charge carriers diffusing within and recombining in the sample and the localized region and inducing at least one transient time-varying change in optical constants of the sample at a location at or near to a surface of the sample; measuring a response of the sample to an optical probe beam at least during a time that the optical constants are varying; and associating the measured response with at least one of chemical species concentration, chemical species type, implant energy, a presence or absence of an introduced chemical species region at the location, and a presence or absence of implant-related damage.

Claim 38

Dependent Claim 32 words

A method as set forth in claim 35, wherein the step of measuring includes a step of generating at least one of a continuous wave probe beam and a pulsed probe beam.

Claim 39

Dependent Claim 59 words

A method as set forth in claim 35, wherein the step of generating includes a step of generating pump beam pulses having a duration in a range of approximately 0.01 picosecond to approximately 100 picoseconds, an energy of approximately 0.001 nJ to approximately 100 nJ per pulse, and a wavelength that is equal to approximately 200 nm or greater.

Claim 40

Dependent Claim 47 words

A method as set forth in claim 35, wherein the step of measuring employs a detector that is positioned for receiving the optical probe beam after it impinges on the sample, and further comprising a step of measuring a change in reflected intensity of the probe beam.

Claim 41

Dependent Claim 47 words

A method as set forth in claim 35, wherein the step of measuring employs a detector that is positioned for receiving the optical probe beam after it impinges on the sample, and further comprising a step of measuring a change in transmitted intensity of the probe beam.

Claim 42

Dependent Claim 48 words

A method as set forth in claim 35, wherein the step of measuring employs a detector that is positioned for receiving the optical probe beam after it impinges on the sample, and further comprising a step of measuring a change in a polarization state of the probe beam.

Claim 43

Dependent Claim 47 words

A method as set forth in claim 35, wherein the step of measuring employs a detector that is positioned for receiving the optical probe beam after it impinges on the sample, and further comprising a step of measuring a change in optical phase of the probe beam.

Claim 44

Dependent Claim 46 words

A method as set forth in claim 35, wherein the step of measuring employs a detector that is positioned for receiving the optical probe beam after it impinges on the sample, and further comprising a step of measuring a change in direction of the probe beam.

Claim 45

Dependent Claim 50 words

A method as set forth in claim 35, wherein the step of measuring employs a detector that is positioned for receiving the optical probe beam after it impinges on the sample, and further comprising a step of measuring a change in optical path length between the surface and the detector.

Claim 46

Dependent Claim 86 words

A method as set forth in claim 35, wherein the steps of generating and measuring include a step of applying a plurality of pairs of optical pulses to the sample, each of the pairs of pulses comprising an optical pump pulse an optical probe pulse, the probe pulse being delayed in time from the pump pulse by a delay time t D , wherein for at least some of the pairs of pulses t D is less than a charge carrier recombination time within the sample.

Claim 47

Dependent Claim 60 words

A method as set forth in claim 35, wherein the step of measuring includes a step of generating a curve that is a function of a change in the optical constants over time, and wherein the step of associating includes a step of comparing the generated curve to at least one reference curve obtained from at least one reference sample.

Claim 48

Dependent Claim 61 words

A method as set forth in claim 35, wherein the step of measuring includes a step of generating a curve that is indicative of a change in the optical constants over time, and wherein the step of associating includes a step of comparing the generated curve to at least one reference curve that is calculated from a model of the sample.

Claim 49

Dependent Claim 29 words

A method as set forth in claim 35, wherein the step of measuring includes a step of generating, for each optical pump pulse, a plurality of optical probe pulses.

Claim 50

Dependent Claim 26 words

A method as set forth in claim 35, wherein the step of measuring obtains measurements as a function of an amplitude of the optical pump pulses.

Claim 51

Dependent Claim 50 words

A method as set forth in claim 35, wherein the step of measuring includes a step of generating optical probe pulses having a predetermined polarization state, and wherein the step of measuring means includes a step of detecting ellipsometric parameters upon a reflection or transmission of the optical probe pulses.

Claim 52

Dependent Claim 58 words

A method as set forth in claim 35, wherein the step of measuring includes a step of detecting, from an oscillation in a change in at least one of intensity, polarization state, and optical phase of light reflected from or transmitted through said sample, at least an indication of an amount of lattice defects present in the sample.

Claim 53

Dependent Claim 25 words

A method as set forth in claim 35, wherein the surface underlies at least one layer comprised of a semiconductor material or a dielectric material.

Claim 54

Dependent Claim 52 words

A method as set forth in claim 35, wherein the step of generating includes a step of generating a sequence of pump pulses at a frequency of f 1 , the sequence of pump pulses being intensity modulated at a frequency of f 2 , and wherein f 2 <f 1 .

Claim 55

Dependent Claim 59 words

A method as set forth in claim 35, wherein the step of generating includes a step of generating a sequence of pump pulses at a frequency of f 1 , wherein the step of measuring includes a step of generating a sequence of probe pulses at a frequency of f 2 , and wherein f 2 ≢f 1 .

Claim 56

Dependent Claim 34 words

A method as set forth in claim 35, wherein at least one of the steps of generating and measuring includes a step of applying an optical beam to the surface through an optical fiber.

Claim 57

Dependent Claim 29 words

A method as set forth in claim 35, wherein the step of measuring includes a step of applying a reflected probe pulse to a photodetector through an optical fiber.

Claim 58

Dependent Claim 58 words

A method as set forth in claim 35, wherein at least one of the steps of generating and measuring includes a step of applying a focussed optical beam to the surface, wherein the optical beam is focussed with an optical fiber having a terminal end portion that is reduced in diameter over other portions of the optical fiber.

Claim 59

Dependent Claim 49 words

A method as set forth in claim 35, wherein at least one of the steps of generating and measuring includes a step of operating a laser for generating optical pulses at a rate within a range of approximately 100 pulses per second to approximately 5×10 9 pulses per second.

Claim 60

Dependent Claim 38 words

A method as set forth in claim 35, wherein the step of measuring includes a step of generating optical probe pulses, and wherein the optical pump pulses and the optical probe pulses are generated with a single laser.

Claim 61

Dependent Claim 43 words

A method as set forth in claim 35, wherein the step of generating generates the optical pump pulses with a first laser, and wherein the step of measuring includes a step of generating at least one optical probe beam with a second laser.

Claim 62

Dependent Claim 30 words

A method as set forth in claim 35, wherein the optical pump pulses and the optical probe beam are applied to the surface at an angle normal to the surface.

Claim 63

Dependent Claim 34 words

A method as set forth in claim 35, wherein the optical pump pulses and the optical probe beam are applied to the surface at an angle that is other than normal to the surface.

Claim 64

Dependent Claim 27 words

A method as set forth in claim 35, wherein the optical pump pulses and the optical probe beam are applied to the surface along the same axis.

Claim 65

Dependent Claim 27 words

A method as set forth in claim 35, wherein the optical pump pulses and the optical probe beam are applied to the surface along two different axes.

Claim 66

Dependent Claim 27 words

A method as set forth in claim 35, wherein the optical pump pulses and the optical probe beam are applied to a same location on the surface.

Claim 67

Dependent Claim 27 words

A method as set forth in claim 35, wherein the optical pump pulses and the optical probe beam are applied to two different locations on the surface.

Claim 68

Dependent Claim 39 words

A method as set forth in claim 35, wherein the measuring includes a step of generating the optical probe beam, and further comprising a step of varying a wavelength of the optical pump pulses and the optical probe beam.

Claim 69

Dependent Claim 55 words

A method as set forth in claim 35, wherein the step of generating includes a step of simultaneously generating a plurality of optical pump pulses each having an energy sufficient to generate charge carriers within the sample, and wherein the step of measuring includes a step of simultaneously generating a plurality of optical probe beams.

Claim 70

Dependent Claim 57 words

A method as set forth in claim 35, wherein the step of measuring includes a step of generating a plurality of optical probe beams, and wherein individual ones of the plurality of pump pulses and probe beams are generated to have at least one of different angles of incidence, different wavelengths, different delay times, and different polarizations.

Claim 71

Independent Claim 151 words

A method for examining a semiconductor sample having at least one localized region underlying a surface into which a chemical species has been implanted, comprising the steps of: thermally annealing the sample to reduce or eliminate implant-related damage; generating optical pump pulses having a wavelength selected for generating a population of charge carriers in the sample, the charge carriers diffusing in the sample and localized region and recombining at different rates in the sample and the localized region, the charge carriers inducing at least one transient time-varying change in optical constants of the sample at a location at or near to a surface of the sample; measuring a response of the sample to an optical probe beam at least during a time that the optical constants are varying; and determining, in accordance with the measured response, whether the sample has been sufficiently thermally annealed to reduce or eliminate the implant-related damage.

Claim 72

Independent Claim 151 words

A method for examining a semiconductor sample having at least one localized region underlying a surface into which a chemical species has been implanted, comprising the steps of: thermally annealing the sample to reduce or eliminate implant-related damage; generating optical pump pulses having a wavelength selected for generating a population of charge carriers in the sample, the charge carriers diffusing in the sample and localized region and recombining at different rates in the sample and the localized region, the charge carriers inducing at least one transient time-varying change in optical constants of the sample at a location at or near to a surface of the sample; measuring a response of the sample to an optical probe beam at least during a time that the optical constants are varying; and determining, in accordance with the measured response, whether the sample has been sufficiently thermally annealed to reduce or eliminate the implant-related damage.

Claim 73

Independent Claim 135 words

A method for examining a semiconductor sample having at least one localized region underlying a surface into which a chemical species has been implanted, comprising the steps of: generating optical pump pulses having a wavelength selected for generating a population of charge carriers in the sample, the charge carriers diffusing in the sample and localized region and recombining at different rates in the sample and the localized region, the charge carriers inducing at least one transient time-varying change in optical constants of the sample at a location at or near to a surface of the sample; measuring a response of the sample to an optical probe beam at least during a time that the optical constants are varying; and determining, in accordance with the measured response, an energy at which the chemical species was implanted.

Claim 74

Independent Claim 135 words

A method for examining a semiconductor sample having at least one localized region underlying a surface into which a chemical species has been implanted, comprising the steps of: generating optical pump pulses having a wavelength selected for generating a population of charge carriers in the sample, the charge carriers diffusing in the sample and localized region and recombining at different rates in the sample and the localized region, the charge carriers inducing at least one transient time-varying change in optical constants of the sample at a location at or near to a surface of the sample; measuring a response of the sample to an optical probe beam at least during a time that the optical constants are varying; and determining, in accordance with the measured response, an energy at which the chemical species was implanted.

Claim 75

Independent Claim 163 words

A method for examining a semiconductor sample having at least one region underlying a surface into which a chemical species has been implanted, comprising the steps of: generating optical pump pulses having a wavelength selected for generating a population of charge carriers in the sample, the charge carriers diffusing in the sample and localized region and recombining at different rates in the sample and the localized region, the charge carriers inducing at least one transient time-varying change in optical constants of the sample at a location at or near to a surface of the sample, individual ones of the optical pump pulses also launching a propagating mechanical wave in the sample; measuring a response of the sample to an optical probe beam at least during a time that the optical constants are varying, the measured response including an oscillatory component due to the propagating mechanical wave; and determining, in accordance with the measured response, at least one characteristic associated with the implanted region.

Claim 76

Independent Claim 163 words

A method for examining a semiconductor sample having at least one region underlying a surface into which a chemical species has been implanted, comprising the steps of: generating optical pump pulses having a wavelength selected for generating a population of charge carriers in the sample, the charge carriers diffusing in the sample and localized region and recombining at different rates in the sample and the localized region, the charge carriers inducing at least one transient time-varying change in optical constants of the sample at a location at or near to a surface of the sample, individual ones of the optical pump pulses also launching a propagating mechanical wave in the sample; measuring a response of the sample to an optical probe beam at least during a time that the optical constants are varying, the measured response including an oscillatory component due to the propagating mechanical wave; and determining, in accordance with the measured response, at least one characteristic associated with the implanted region.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	2001-01-05	2001-07-07	2002-01-06	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2005-01-05	2005-07-07	2006-01-06	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2009-01-05	2009-07-07	2010-01-06	$7700.00	Window Closed / Lapsed

Ultrafast optical technique for the characterization of altered materials

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