Scanning electron microscope operating in area scan and angle scan modes

Claim 2

A scanning electron microscope having a beam source and means for focusing the beam to a probe impinging on a specimen, wherein the improvement is in a combination of: area scan means comprising means for selecting an angle of incidence of the beam probe on the specimen from a defined range of angles and means for scanning the specimen with the beam probe while maintaining said selected angle of incidence, thereby operating the microscope in an area scan mode; angle scan means comprising means for selecting a point of incidence of the beam probe on the specimen and means for automatically scanning the angle of incidence of the beam probe on the specimen in a scanning pattern while maintaining the beam probe at the selected point of incidence on the specimen, thereby operating the microscope in an angle scan mode; switch means for causing the microscope to operate the area scan means and the angle scan means in a selected sequence; and first means for displaying area dependent information about the specimen obtained in the course of said area scan mode of operating the scanning electron microscope and second means for displaying angle dependent information about the same specimen obtained in the course of said angle scan mode of operating the scanning electron microscope.

Claim 3

A scanning electron microscope as in claim 1 including a deflection coil set disposed in the path of the beam to act thereon, wherein the area scan means includes means for driving the deflection coil set with a positioning signal to define said selected angle of incidence and with a scanning signal to scan the specimen with the beam while maintaining said selected angle of incidence.

Claim 4

A scanning electron microscope as in claim 2 wherein the area scan means includes means for driving the deflection coil set with a DC positioning signal to define the selected angle of incidence and means for driving the deflection coil set with an AC scanning signal to carry out said scanning of the specimen with the beam probe while maintaining the selected angle of incidence of the beam probe.

Claim 5

A scanning electron microscope as in claim 1 including a deflection coil set disposed in the path of the beam to act thereon, wherein the area scan means includes means for driving the deflection coil set to carry out area scan of the specimen and the angle scan means includes means for driviNg the deflection coil set to carry out angle scan of the specimen.

Claim 6

A scanning electron microscope as in claim 4 wherein the area scan means includes means for driving the deflection coil set with a DC signal to define said selected angle of incidence of the beam probe and for driving the deflection coil set with an AC signal to carry out scanning of an area of the specimen, and wherein the angle scan means includes means for driving the deflection coil set with a DC signal to define said selected point of incidence of the beam probe and for driving the deflection coil set with an AC signal to carry out angle scanning of the specimen.

Claim 7

A scanning electron microscope as in claim 5 including an objective lens wherein said deflection coils are disposed between the objective lens and the specimen.

Claim 8

A scanning electron microscope as in claim 6 including a specimen holder disposed below the objective lens and including means for supporting a specimen and means for supporting said deflection coils.

Claim 9

A scanning electron microscope as in claim 7 wherein said deflection coil set includes a lower deflection coil and an upper deflection coil.

Claim 10

A scanning electron microscope as in claim 5 including an objective lens having an aperture through which the beam passes wherein said deflection coil set is disposed at least partly within said objective lens aperture.

Claim 11

A scanning electron microscope as in claim 5 including an objective lens wherein said deflection coils are disposed between the objective lens and the beam source.

Claim 12

A scanning electron microscope as in claim 10 including a movable aperture plate disposed between the deflection coils and the objective lens.

Claim 13

A scanning electron microscope having a beam source and means for focusing the beam to a probe impinging on a specimen, comprising: area scan means comprising means for selecting an angle of incidence of the beam probe on the specimen and means for scanning in a defined pattern a selected area of the specimen with the beam probe while maintaining said selected angle of incidence to thereby operate the microscope in an area scan mode; angle scan means comprising means for selecting a point of incidence of the beam probe on the specimen and means for automatically scanning the angle of incidence of the beam probe on the specimen in a defined scanning pattern while maintaining the beam probe at the selected point of incidence on the specimen to thereby operate the microscope in an area scan mode; switch means for causing the scanning electron microscope to operate the area scan means and the angle scan means in a selected sequence so as to obtain both area dependent and angle dependent information about the same specimen; and first means for displaying said area dependent information about the specimen obtained in the course of said area scan mode and second means for displaying angle dependent information about the same specimen obtained in the course of said angle scan mode of operating the scanning electron microscope.

Claim 14

A scanning electron microscope having a beam source and means for focusing the beam to a probe impinging on a specimen, comprising: area scan means comprising means for selecting an angle of incidence of the beam probe on the specimen and means for scanning in a defined pattern a selected area of the specimen with the beam probe while maintaining said selected angle of incidence to thereby operate the microscope in an area scan mode; angle scan means comprising means for selecting a point of incidence of the beam probe on the specimen and means for automatically scanning the angle of incidence of the beam probe on the specimen in a defined scanning pattern while maintaining the beam probe at the selected point of incidence on the specimen to thereby operate the microscope in an area scan mode; switch means for causing the scanning electron microscope to operate the area scan means and the angle scan means in a selected sequence so as to obtain both area dependent and angle dependent information about the same specimen; and first means for displaying said area dependent information about the specimen obtained in the course of said area scan mode and second means for displaying angle dependent information about the same specimen obtained in the course of said angle scan mode of operating the scanning electron microscope.

Claim 15

A scanning electron microscope as in claim 12 including means for generating a positioning signal and means for generating a scanning signal, said positioning signal defining the selected angle of incidence of the beam probe on the specimen when the microscope is operating in the area scan mode and defining the selected point of incidence of the beam on the specimen when the microscope is operating in the angle scan mode, and said scanning signal defining the scanning pattern in either mode.

Claim 16

A scanning electron microscope as in claim 13 wherein said positioning signal is a DC electrical signal and said scanning signal is an AC electrical signal.

Claim 17

A scanning electron microscope as in claim 14 including a deflection coil and means for applying said positioning and scanning signal to the deflection coil.

Claim 18

A scanning electron microscope as in claim 15 wherein the deflection coil comprises a first coil for seleCtively deflecting the beam in a first direction along the specimen and a second coil for selectively deflecting the beam in a second direction along the specimen, said first and second direction intersecting each other, and wherein each of the first and second coil comprises an upper and a lower coil, means for applying said positioning and scanning signals to each of the upper and lower coils in ratios defining the scanning mode, the angle of incidence and the scanned area in the area scan mode, and the point of incidence and the scanning pattern in the angle scan mode.

Claim 19

A scanning electron microscope as in claim 16 wherein the first display means provides an area scan display of an electron microscope image of the scanned area of the specimen and the second display means provides an angle scan display of an electron microscope image of the scanned point of the specimen, and including means for displaying on the second display means the angle of incidence of the beam while the microscope is operating in the area scan mode, and for displaying on the first display means the point of incidence of the beam on the specimen while the microscope is operating in the angle scan mode.

Claim 20

A scanning electron microscope as in claim 12 including deflection coil means for selectively deflecting the beam with respect to the specimen, wherein the area scan means includes means for driving the deflection coil means with a positioning signal defining the angle of incidence of the beam probe on the specimen and with a superimposed scanning signal defining the scanning pattern of the beam probe over a selected area of the specimen, and wherein the angle scan means includes means for driving the deflection coil means with a positioning signal defining the point of incidence of the beam probe on the specimen and with a superimposed scanning signal defining the pattern of scanning a selected range of angles of incidence of the beam probe on the specimen.

Claim 21

A scanning electron microscope as in claim 18 wherein the deflection coil means includes electromagnetic coils and wherein said positioning signal is a DC signal and said scanning signal is an AC signal.

Claim 22

A scanning electron microscope as in claim 19 including means interposed between the area scan and the angle scan means on the one hand and the deflection coil means on the other hand for selectively varying the power of the DC signal to thereby select an angle of scanning in the area scan mode and a point of incidence in the angle scan mode, and for selectively varying the power of the AC signal to thereby select the size of the scanned area in the area scan mode and the range of scanned angles in the angle scan mode.

Claim 25

A method as in claim 21 including the steps Of: displaying an area scan image of the specimen and an angle scan image of the specimen, said angle scan image of the specimen representing the angle of incidence of the beam probe on the specimen during area scan and said area scan image of the specimen representing the point of incidence of the beam on the specimen during angle scan.

Claim 26

A method as in claim 21 wherein the specimen is scanned first in an angle scan mode and is then scanned in an area scan mode, with the angle of incidence of the beam probe on the specimen during said area scan mode selected on the basis of the angle dependent information obtained in the course of the preceding angle scan mode scanning of the specimen.

Claim 27

A method as in claim 21 wherein the specimen is scanned first in an area scan mode and is then scanned in an angle scan mode, with the point of incidence of the beam during said angle scan mode being selected on the basis of area dependent information obtained in the course of said preceding area scan mode scanning of the specimen.