Scanning tunneling microscope and surface topographic observation method

Claim 2

A surface topographic observation method using a scanning tunnelling microscope, comprising the steps of: applying a voltage between a probe and a sample to be observed; positioning a tip of the probe close to the surface of the sample; detecting a tunnel current flowing across the probe and the sample when a distance between the tip of the probe and the surface of the sample is within a tunnelling effect region; moving the probe away from the surface of the sample when the detected tunnel current reaches a set point value; moving the probe in a direction substantially parallel with the surface of the sample for scanning the probe from one measurement point to another measurement point when the distance between the tip of the probe and the surface of the same is outside of the tunnelling effect region; and obtaining information of the surface of the sample from the spatial position of the tip of the probe when the tunnel current reaches the set point value at respective measurement points; wherein the steps of detecting a tunnel current and moving the probe away from the surface of the sample when the detected tunnel current reaches a set point value includes detecting when the tunnel current reaches the set point value and immediately moving the probe away from the surface of the sample when the detected tunnel current reaches the set point value, the detection of the tunnel current and obtaining of information of the surface of the sample at respective measurement points being effected without servo control of the positioning of the tip of the probe close to the surface of the sample.

Claim 3

A surface topographic observation method according to claim 1, wherein the set point value is the value at which tunnel current begins to flow across the probe and the sample.

Claim 4

A surface topographic observation method according to claim 1, wherein the step of positioning a tip of the probe close to the surface of the sample includes applying a signal to a piezoelectric member of the probe so as to effect elongation thereof, and the step of moving the probe away from the surface of the sample when the detected tunnel current reaches a set point value includes stopping the application of the signal for elongating the piezoelectric member so that the piezoelectric member immediately contracts upon detection of reaching of the set point value.

Claim 5

A surface topographic observation method according to claim 3, wherein the step of applying an elongation signal includes applying a digital signal for providing a stepped elongation of the piezoelectric member in accordance therewith, and the step of obtaining information of the surface of a sample from the spatial position of the tip of the probe when the tunnel current reaches the set point value at respective measurement points includes counting a digital signal indicative of the elongation signal representative of the spatial position of the tip of the probe.

Claim 6

A scanning tunnelling microscope comprising: a probe having a tip facing a surface of a sample to be observed; means for applying a voltage between a probe and a sample; means for positioning a tip of the probe close to the surface of the sample so that the distance between the tip of the probe and the surface of the sample is within a tunnelling effect region; means for measuring a tunnel current flowing across the probe and the sample when the distance is within the tunnelling effect region; means for moving the probe away from the surface of the sample when the detected tunnel current reaches a set point value; scanning means for discretely moving the probe in a direction substantially parallel with the surface of the sample from one measurement point to another measurement point when the probe has been moved away from the surface of the sample and the distance is outside of the tunnelling effect region; and means for obtaining information of the surface of the sample from the spatial position of the tip of the probe when the tunnel current reaches the set point value at respective measurement points; wherein the means for measuring a tunnel current includes means for detecting when the tunnel current reaches the set point value and the means for moving the probe away from the surface of the sample effects immediate movement of the probe away from the surface of the sample after the detected tunnel current reaches the set point value, the means for measuring the tunnel current and the means for obtaining information on the surface of the sample operating without the means for stopping the application of the signal for elongating the piezoelectric member so that the piezoelectric member immediately contracts upon detection of reaching of the set point value.

Claim 7

A scanning tunnelling microscope comprising: a probe having a tip facing a surface of a sample to be observed; means for applying a voltage between a probe and a sample; means for positioning a tip of the probe close to the surface of the sample so that the distance between the tip of the probe and the surface of the sample is within a tunnelling effect region; means for measuring a tunnel current flowing across the probe and the sample when the distance is within the tunnelling effect region; means for moving the probe away from the surface of the sample when the detected tunnel current reaches a set point value; scanning means for discretely moving the probe in a direction substantially parallel with the surface of the sample from one measurement point to another measurement point when the probe has been moved away from the surface of the sample and the distance is outside of the tunnelling effect region; and means for obtaining information of the surface of the sample from the spatial position of the tip of the probe when the tunnel current reaches the set point value at respective measurement points; wherein the means for measuring a tunnel current includes means for detecting when the tunnel current reaches the set point value and the means for moving the probe away from the surface of the sample effects immediate movement of the probe away from the surface of the sample after the detected tunnel current reaches the set point value, the means for measuring the tunnel current and the means for obtaining information on the surface of the sample operating without the means for stopping the application of the signal for elongating the piezoelectric member so that the piezoelectric member immediately contracts upon detection of reaching of the set point value.

Claim 8

A scanning tunneling microscope according to claim 5, wherein the detecting means detects the value at which tunnel current begins to flow across the probe and the sample as the set point value.

Claim 9

A scanning tunneling microscope according to claim 5, wherein the means for positioning a tip of the probe close to the surface of the sample includes means for applying a signal to a piezoelectric member of the probe so as to effect elongation thereof and the means for moving the probe away from the surface of the sample when the detected tunnel current reaches a set point value includes means for stopping the application of the signal for elongating the piezoelectric member so that the piezoelectric member immediately contracts upon detection of reaching of the set point value.

Claim 10

A scanning tunnelling microscope according to claim 7, wherein the means for applying an elongation signal includes digital means for applying a digital signal for providing a stepped elongation of the piezoelectric member in accordance therewith, and the means for obtaining information of the surface of a sample from the spatial position of the tip of the probe when the tunnel current reaches the set point value at respective measurement points includes means for counting a digital signal indicative of the elongation signal representative of the spatial position of the tip of the probe.

Claim 11

A surface topographic observation method comprising the steps of: moving a probe so that a tip of the probe approaches a surface of the sample; measuring a physical quantity when a distance between the tip of the probe and the surface of the sample is within a predetermined region; detecting a moment when the physical quantity reaches a set point value; moving the probe away from the surface of the sample immediately upon detection of the moment when the physical quantity reaches the set point value and from one measurement point to another measurement point relative to the surface of the sample so that at least during a part of the movement of the probe the distance between the tip of the probe and the surface of the sample is outside of the predetermined region; and obtaining information of the surface of the sample from spatial positions of the tip of the probe at the moment when the physical quantity reaches the set point value at respective measurement points; wherein the detection of the physical quantity and obtaining of information of the surface of the sample at respective measurement points is effected without servo control of the moving of the tip of the probe to approach the surface of the sample.

Claim 12

A surface topographic observation method comprising the steps of: moving a probe so that a tip of the probe approaches a surface of the sample; measuring a physical quantity when a distance between the tip of the probe and the surface of the sample is within a predetermined region; detecting a moment when the physical quantity reaches a set point value; moving the probe away from the surface of the sample immediately upon detection of the moment when the physical quantity reaches the set point value and from one measurement point to another measurement point relative to the surface of the sample so that at least during a part of the movement of the probe the distance between the tip of the probe and the surface of the sample is outside of the predetermined region; and obtaining information of the surface of the sample from spatial positions of the tip of the probe at the moment when the physical quantity reaches the set point value at respective measurement points; wherein the detection of the physical quantity and obtaining of information of the surface of the sample at respective measurement points is effected without servo control of the moving of the tip of the probe to approach the surface of the sample.

Claim 13

A surface topographic observation method according to claim 9, wherein the set point value is the value at which the physical quantity is initially able to be detected.

Claim 14

A surface topographic observation method according to claim 9, wherein the step of moving the tip of the probe to approach the surface of the sample includes applying a signal to a piezoelectric member of the probe so as to effect elongation thereof and the step of moving the probe away from the surface of the sample when the detected physical quantity reaches a set point value includes stopping the application of the signal for elongating the piezoelectric member so that the piezoelectric member immediately contracts upon detection of reaching of the set point value.

Claim 15

A surface topographic observation method according to claim 11, wherein the step of applying an elongation signal includes applying a digital signal for providing a stepped elongation of the piezoelectric member in accordance therewith, and the step of obtaining information of the surface of a sample from the spatial position of the tip of the probe when the physical quantity reaches the set point value at respective measurement points includes counting a digital signal indicative of the elongation signal representative of the spatial position of the tip of the probe.

Claim 16

A surface topographic observation method according to claim 9, wherein the physical quantity is a tunnel current.

Claim 17

A surface topographic observation method according to claim 9, wherein the physical quantity is an atomic force.

Claim 18

A surface topographic observation method according to claim 9, wherein the physical quantity is a temperature.

Claim 19

A surface topographic observation method according to claim 9, wherein the physical quantity is a light.

Claim 20

A surface topographic observation method according to claim 9, wherein the physical quantity is an electrostatic capacity.

Claim 21

A surface topographic observation method according to claim 9, wherein the physical quantity is an electric resistance.

Claim 22

Apparatus for surface topographic observation comprising: a probe having a tip facing a surface of a sample to be observed; means for moving the probe so that the tip of the probe approaches the surface of the sample and a distance between the tip of the probe and the surface of the sample comes within a predetermined region; means for measuring a physical quantity when the distance between the tip of the probe and the surface of the sample is within the predetermined region; means for detecting a moment when the physical current reaches a set point value; means for immediately moving the probe away from the surface of the sample upon detection of the physical current reaching the set point value and from one measurement point to another measurement point relative to the surface of the sample so that at least during a part of the movement of the probe the distance between the tip of the probe and the surface of the sample is outside of the predetermined region; and means for obtaining information on the surface of the sample from the spatial positions of the tip of the probe at the moment when the detected physical quantity reaches the set point value at respective measurement points; wherein the detection of the physical quantity and obtaining of information of the surface of the sample at respective measurement points is effected without servo control of the moving of the tip of the probe to approach the surface of the sample.

Claim 23

Apparatus for surface topographic observation comprising: a probe having a tip facing a surface of a sample to be observed; means for moving the probe so that the tip of the probe approaches the surface of the sample and a distance between the tip of the probe and the surface of the sample comes within a predetermined region; means for measuring a physical quantity when the distance between the tip of the probe and the surface of the sample is within the predetermined region; means for detecting a moment when the physical current reaches a set point value; means for immediately moving the probe away from the surface of the sample upon detection of the physical current reaching the set point value and from one measurement point to another measurement point relative to the surface of the sample so that at least during a part of the movement of the probe the distance between the tip of the probe and the surface of the sample is outside of the predetermined region; and means for obtaining information on the surface of the sample from the spatial positions of the tip of the probe at the moment when the detected physical quantity reaches the set point value at respective measurement points; wherein the detection of the physical quantity and obtaining of information of the surface of the sample at respective measurement points is effected without servo control of the moving of the tip of the probe to approach the surface of the sample.

Claim 24

An apparatus according to claim 19, wherein the detecting means detects the set point value as the value at which the physical quantity is initially able to be detected.

Claim 25

An apparatus according to claim 19, wherein the means for moving a tip of the probe to approach the surface of the sample includes means for applying a signal to a piezoelectric member of the probe so as to effect elongation thereof, and the means for moving the probe away from the surface of the sample when the detected physical quantity reaches a set point value includes means for stopping the application of the signal for elongating the piezoelectric member so that the piezoelectric member immediately contracts upon detection of reaching of the set point value.

Claim 26

An apparatus according to claim 21, wherein the means for applying an elongation signal includes digital means for applying a digital signal for providing a stepped elongation of the piezoelectric member in accordance therewith, and the means for obtaining information of the surface of a sample from the spatial position of the tip of the probe when the physical quantity reaches the set point value at respective measurement points includes means for counting a digital signal indicative of the elongation signal representative of the spatial position of the tip of the probe.

Claim 27

An apparatus according to claim 19, wherein the physical quantity is a tunnel current and the apparatus is a scanning tunnelling microscope.

Claim 28

An apparatus according to claim 19, wherein the physical quantity is an atomic force.

Claim 29

An apparatus according to claim 19, wherein the physical quantity is a temperature.

Claim 30

An apparatus according to claim 19, wherein the physical quantity is a light.

Claim 31

An apparatus according to claim 19, wherein the physical quantity is an electrostatic capacity.

Claim 32

An apparatus according to claim 19, wherein the physical quantity is an electric resistance.

Claim 33

A surface topographic observation method using a scanning tunnelling microscope, comprising the steps of: applying a voltage between a probe and a sample to be observed; positioning a tip of the probe close to the surface of the sample; detecting a tunnel current flowing across the probe and the sample when a distance between the tip of the probe and the surface of the sample is within a tunnelling effect region; moving the probe away from the surface of the sample when the detected tunnel current reaches a set point value; moving the probe in a direction substantially parallel with the surface of the sample for scanning the probe from one measurement point to another measurement point when the distance between the tip of the probe and the surface of the sample is outside of the tunnelling effect region; and obtaining information of the surface of the sample from the spatial position of the tip of the probe when the tunnel current reaches the set point value at respective measurement points; wherein the step of moving the probe away from the surface of the sample when the detected tunnel current reaches the set point value is effected immediately when the detected tunnel current first arrives at the set point value independently of the tunnel current becoming a constant value of the set point value.

Claim 34

A surface topographic observation method using a scanning tunnelling microscope, comprising the steps of: applying a voltage between a probe and a sample to be observed; positioning a tip of the probe close to the surface of the sample; detecting a tunnel current flowing across the probe and the sample when a distance between the tip of the probe and the surface of the sample is within a tunnelling effect region; moving the probe away from the surface of the sample when the detected tunnel current reaches a set point value; moving the probe in a direction substantially parallel with the surface of the sample for scanning the probe from one measurement point to another measurement point when the distance between the tip of the probe and the surface of the sample is outside of the tunnelling effect region; and obtaining information of the surface of the sample from the spatial position of the tip of the probe when the tunnel current reaches the set point value at respective measurement points; wherein the step of moving the probe away from the surface of the sample when the detected tunnel current reaches the set point value is effected immediately when the detected tunnel current first arrives at the set point value independently of the tunnel current becoming a constant value of the set point value.

Claim 35

A scanning tunnelling microscope comprising: a probe having a tip facing a surface of a sample to be observed; means for applying a voltage between a probe and a sample; means for positioning a tip of the probe close to the surface of the sample so that the distance between the tip of the probe and the surface of the sample is within a tunnelling effect region; means for measuring a tunnel current flowing across the probe and the sample when the distance is within the tunnelling effect region; means for moving the probe away from the surface of the sample when the detected tunnel current reaches a set point value; scanning means for discretely moving the probe in a direction substantially parallel with the surface of the sample from one measurement point to another measurement point when the probe has been moved away from the surface of the sample and the distance is outside of the tunnelling effect region; and means for obtaining information of the surface of the sample from the spatial position of the tip of the probe when the tunnel current reaches the set point value at respective measurement points; wherein the means for moving the probe away from the surface of the sample when the detected tunnel current reaches the set point value immediately effects movement of the probe when the detected tunnel current first arrives at the set point value independently of the tunnel current becoming a constant value of the set point value.

Claim 36

A scanning tunnelling microscope comprising: a probe having a tip facing a surface of a sample to be observed; means for applying a voltage between a probe and a sample; means for positioning a tip of the probe close to the surface of the sample so that the distance between the tip of the probe and the surface of the sample is within a tunnelling effect region; means for measuring a tunnel current flowing across the probe and the sample when the distance is within the tunnelling effect region; means for moving the probe away from the surface of the sample when the detected tunnel current reaches a set point value; scanning means for discretely moving the probe in a direction substantially parallel with the surface of the sample from one measurement point to another measurement point when the probe has been moved away from the surface of the sample and the distance is outside of the tunnelling effect region; and means for obtaining information of the surface of the sample from the spatial position of the tip of the probe when the tunnel current reaches the set point value at respective measurement points; wherein the means for moving the probe away from the surface of the sample when the detected tunnel current reaches the set point value immediately effects movement of the probe when the detected tunnel current first arrives at the set point value independently of the tunnel current becoming a constant value of the set point value.