Method for rapid seeks to the measurement surface for a scanning probe microscope

1. A method for operating a scanning probe microscope to measure a property of a measurement surface, said microscope having a probe tip and an actuator mechanically coupled to said probe tip and coupled to a position sensor, said method comprising:

making an initial determination of a settle height, said initial determination comprising:

bringing said probe tip towards said measurement surface at a first point on said measurement surface and at a first speed while measuring interactions between said probe tip and said surface to determine a first surface height estimate for said measurement surface; and

determining a first settle height using said first surface height estimate;

and scanning said measurement surface at a plurality of points on said measurement surface, said scanning comprising:

moving said probe tip to a first vertical position over said measurement surface at a second speed greater than said first speed, wherein said position is determined by said determined first settle height; and

measuring said property of said measurement surface with said probe tip, wherein said probe tip is moved vertically relative to said measurement surface at a third speed that is less than said second speed, wherein said determined first settle height functions to provide a reference signal to a controller of said actuator.

2. The method of claim 1 wherein said measurement surface comprises a plurality of surface positions having different surface heights, wherein said bringing said probe tip towards said measurement surface at a first speed is carried out at each of said plurality of surface positions, generating a corresponding plurality of surface height estimates; and wherein determining said first surface height estimate comprises determining an average surface height from said plurality of surface height estimates.

3. A method for a scanning probe microscope for performing a fast surface seek with a scanning probe tip to a measurement surface comprising a plurality of surface heights comprising:

determining a surface height estimate for said measurement surface;

determining a settle height using said surface height measurement; and

performing said fast surface seek to said measurement surface with an actuator coupled to a position sensor, said actuator mechanically coupled to said scanning probe tip wherein said settle height functions to provide a reference signal to a controller of said actuator;

wherein determining said settle height comprises determining a standard deviation of said plurality of surface height estimates.

4. The method of claim 2 wherein determining said first settle height comprises determining a minimum height and a maximum height from said plurality of surface height estimates.

5. The method of claim 4 wherein determining said first settle height comprises determining a difference between said maximum height and said minimum height.

6. A method for a scanning probe microscope for performing a fast surface seek with a scanning probe tip to a measurement surface comprising a plurality of surface heights comprising:

determining a surface height estimate for said measurement surface;

determining a settle height using said surface height measurement; and

performing said fast surface seek to said measurement surface with an actuator coupled to a position sensor, said actuator mechanically coupled to said scanning probe tip wherein said settle height functions to provide a reference signal to a controller of said actuator,

wherein determining said settle height comprises determining an average surface height from said plurality of surface height estimates, determining a standard deviation of said plurality of surface height estimates, determining a minimum height and a maximum height from said plurality of surface height estimates, and determining a difference between said maximum height and said minimum height.

7. The method of claim 1 further comprising determining a second surface height estimate at a second point on said measurement surface that is different from said first point on said measurement surface.

8. The method of claim 1 further comprising determining a second settle height.

9. The method of claim 1 wherein said first surface height estimate depends on said first point on said measurement surface.

10. The method of claim 1 wherein said settle height depends on said first point on said measurement surface.

11. method of claim 1 wherein said actuator is a MEMS actuator.

12. The method of claim 1 wherein said actuator is a piezoelectric actuator.

13. The method of claim 1 wherein said controller comprises a feedback controller.

14. The method of claim 1 wherein said controller comprises a feedforward block.

15. The method of claim 1 wherein said controller comprises a prefilter for said reference signal.

16. The method of claim 1 wherein said controller comprises a state space controller.

17. The method of claim 16 wherein said state space controller comprises an integrator.

18. A method for performing a fast surface seek to a measurement surface comprising a plurality of surface heights for a scanning probe microscope comprising: determining an initial position of a scanning probe tip mechanically coupled to an actuator coupled to a position sensor, said actuator mechanically coupled to a stepper motor of said scanning probe microscope with respect to said measurement surface;

determining a position of said stepper motor when said scanning probe tip is at said scanning measurement surface;

determining a safety margin height from said determined position;

raising said scanning probe tip by said safety margin height with respect to said stepper motor; and

lowering said stepper motor to said position.

19. The method of claim 18 further comprising:

determining a surface height estimate for said measurement surface;

determining a settle height using said surface height measurement; and

performing said fast surface seek with said actuator to said measurement surface,

wherein said settle height functions to provide a reference signal to a controller of said actuator.

20. The method of claim 19 wherein said actuator is a MEMS actuator.