Dual cantilever scanning probe microscope

• US 6,028,305 A
• Filed: 03/25/1998
• Issued: 02/22/2000
• Est. Priority Date: 03/25/1998
• Status: Expired due to Fees

• Current Assignee: Board of Trustees of the Leland Stanford Junior University (Stanford University)
• Original Assignee: Board of Trustees of the Leland Stanford Junior University (Stanford University)
• Inventors: Quate, Calvin F., Minne, Stephen C.
• Primary Examiner(s): LE, QUE TAN
• Application Number:
  US09/047,239
• Time in Patent Office: 699 Days
• Field of Search: 250/234, 250/559.22, 250/306, 250/201.3, 356/376, 356/377
• US Class Current: 250/234
• CPC Class Codes: B82Y 35/00 Methods or apparatus for measurement or analysis of nanostructures
• CPC Class Codes: G01Q 60/363 Contact-mode AFM
• CPC Class Codes: G01Q 70/06 Probe tip arrays
• CPC Class Codes: Y10S 977/874 Probe tip array

Abstract

This microscope apparatus comprises two probes. The first probe is configured to interact with and measure characteristics of surfaces within an effective measurement distance of the first probe. This probe could be contact type, non-contact type, constant force mode, or constant height mode. A combination of actuation devices positions the first probe over a surface of a sample. The surface is scanned at high speeds in search of a target area. When a target area is found, a scanner moves the sample so that a second contact type probe with a sharp tip is positioned over the target area. The second probe is activated and the target area is scanned at low speeds and high resolution. The first and second probes are part of the same probe assembly. The probe assembly of the present invention does not require probe replacement as frequently as current assemblies because the sharp tip is used only at low speeds and high resolution configurations. Thus, the sharp tip wears slower than it would if the sharp tip was used to find the target feature as well.

Claims

1. A scanning probe microscope comprising:

a first probe configured to interact with and measure characteristics of surfaces within an effective measurement distance of said first probe;

a first mechanism configured to position said first probe over a first point of a surface of a sample within said effective measurement distance;

a second probe;

a second mechanism configured to contact and remove said second probe to and from said surface of said sample at a second point, wherein said second point is separated from said first point by a predetermined distance in a predetermined direction; and

a third mechanism configured to move said second probe said predetermined distance in said predetermined direction.

2. The scanning probe microscope of claim 1, wherein said third mechanism comprises:

a scanner configured to receive, interpret, and respond to data representing movement instructions, said movement instructions instructing said scanner to move said sample said predetermined distance in said first direction; and

a controller configured to send said data to said scanner.

3. The scanning probe microscope of claim 2, wherein said scanner comprises piezoelectric tubes.

4. The scanning probe microscope of claim 1, wherein said first probe is a contact type probe which is configured to interact with and measure said characteristics of said surfaces by contacting said surface, whereby said effective measurement distance is zero.

5. The scanning probe microscope of claim 4, further comprising a microscope body, wherein said first mechanism is a first actuator having a first and second end, said first actuator coupled to said microscope body at said first end of said first actuator and coupled to said first probe at said second end of said first actuator.

6. The scanning probe microscope of claim 5, wherein said first probe comprises a first contact type probe, said contact type probe comprising a first tip, said effective measurement distance being zero in that said first contact type probe cannot measure characteristics of said surface of said sample without actually contacting said surface of said sample.

7. The scanning probe microscope of claim 5, wherein said second mechanism is a second actuator having a first and second end, said second actuator coupled to said microscope body at said first end of said second actuator and coupled to said second probe at said second end of said second actuator.

8. The scanning probe microscope of claim 7, wherein said second probe comprises a second contact type probe, said second contact type probe comprising a second tip.

9. The scanning probe microscope of claim 8, wherein said second tip is sharper than said first tip.

10. The scanning probe microscope of claim 1, further comprising a microscope body, wherein said second mechanism is an actuator having a first and second end, said actuator coupled to said microscope body at said first end and coupled to said second probe at said second end.

11. The scanning probe microscope of claim 10, wherein said second probe comprises a contact type probe, said second contact type probe comprising a tip, said effective measurement distance being zero in that said second contact type probe cannot measure characteristics of said surface of said sample without actually contacting said surface of said sample.

12. An scanning probe microscope comprising:

a microscope body;

a first probe configured to interact with and measure characteristics of surfaces within an effective measurement distance of said first probe, wherein said first probe is a contact type probe which is configured to interact with and measure said characteristics of said surfaces by contacting said surface;

a first mechanism configured to position said first probe over a first point of a surface of a sample within said effective measurement distance, wherein said first mechanism is a first actuator having a first and second end, said first actuator coupled to said microscope body at said first end of said first actuator and coupled to said first probe at said second end of said first actuator;

a second probe, wherein said second probe comprises a second contact type probe, said second contact type probe comprising a second tip, said effective measurement distance being zero in that said second contact type probe cannot measure characteristics of said surface of said sample without actually contacting said surface of said sample;

a second mechanism configured to contact and remove said second probe to and from said surface of said sample at a second point, wherein said second point is separated from said first point by a predetermined distance in a predetermined direction, wherein said second mechanism is a second actuator having a first and second end, said second actuator coupled to said microscope body at said first end of said second actuator and coupled to said second probe at said second end of said second actuator, wherein said second tip is sharper than said first tip; and

a third mechanism configured to move said second probe said predetermined distance in said predetermined direction, said third mechanism comprising;

a scanner configured to receive, interpret, and respond to data representing movement instructions to move said scanner said predetermined distance in said first direction, said scanner comprising piezoelectric tubes; and

a controller configured to send said data to said scanner.

13. A method for probing a surface of a sample comprising:

contacting a first probe comprising a first contact end to a surface of said sample at said first contact end;

after contacting a first probe, moving said first probe along said surface until said first contact end contacts a target point on said surface; and

after moving said first probe, contacting a second probe comprising a second contact end to said target point at said second contact end, said second probe being a fixed distance from said first probe in a first direction.

14. The method of claim 13, wherein said step of contacting a second probe further comprises the substep of moving said second probe said fixed distance in said first direction.

15. The method of claim 14, wherein said substep of moving said second probe comprises the substep of moving said second probe said fixed distance before contacting said second probe to said target point at said second contact end.

16. The method of claim 13 further comprising the step of, after contacting a second probe, moving said second probe along said surface.

17. The method of claim 13 wherein said step of contacting a second probe comprises the step of contacting said second probe comprising said second contact end smaller than said first contact end to said surface of said sample at said second contact end, said second probe being said fixed distance from said first probe in said first direction.

18. The method of claim 13 wherein said step of contacting a second probe comprises the step of contacting said second probe comprising said second contact end smaller than said first contact end by a factor of ten to a surface of said sample at said second contact end, said second probe being said fixed distance from said first probe in said first direction.

19. A scanning probe microscope comprising:

a first cantilever coupled to a first actuator, said first actuator being for driving said first cantilever between a raised position and a lowered position, a tip of said first cantilever being closest to a surface of a sample when said first cantilever is in said lowered position;

a second cantilever coupled to a second actuator, said second actuator being for driving said second cantilever between a raised position and a lowered position, a tip of said second cantilever being closest to said surface of said sample when said second cantilever is in said lowered position; and

a control unit for controlling said first and second actuators such that said first cantilever is in said lowered position when said second cantilever is in said raised position.

20. A method of analyzing a sample comprising the steps of:

providing a scanning probe microscope, said scanning probe microscope having first and second cantilevers with first and second tips, respectively, separated by a fixed predetermined distance;

positioning said cantilevers such that said first tip is within an effective measurement distance of said sample and said second tip is spaced apart from said sample;

causing relative motion between said cantilevers and said sample such that said first tip arrives over a first location on said sample;

positioning said cantilevers such that said first tip is spaced apart from said sample and said second tip is adjacent said sample;

scanning said sample with said second tip so as to generate a representation of a property of said sample.