Synchronous sampling scanning force microscope
AssigneeTopometrix
InventorsRonald C. Gamble, Paul E. West, Marc R. Schuman
Life of this patent
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Abstract
The synchronous sampling scanning force microscope includes a reflective cantilever arm having a free end which is oscillated at a frequency different from the resonance frequency of the cantilever arm. The motion of the oscillating cantilever arm is measured, to generate a deflection signal indicative of the amplitude of deflection or phase shift of the cantilever arm. Selected portions of cycles of the output signal are sampled, for generating output signal data indicative of deflection of the near and far excursions of the probe. The method and apparatus permit monitoring of compliance of the surface of the specimen by multiple sampling at a rate greater than the period of oscillation of the cantilever probe of the microscope.
Claims57
In a synchronous sampling scanning force microscope for examining surface contours of a specimen, said specimen surface also having an attractive region and a repulsive region, said microscope having a body, a cantilever arm having a first end secured to said body and a free end, said cantilever arm having a fundamental resonance frequency, probe means secured to said free end of said cantilever arm and including a probe tip adapted to follow surface contours of the specimen, scanning means for mounting said specimen for examination by said microscope and adapted to scan said specimen relative to said body, deflection measuring means mounted to said body for measuring deflection of the cantilever arm and generating a deflection signal indicative of deflection of said cantilever arm, the improvement which comprises:
- oscillator drive means connected to said cantilever arm for causing the cantilever arm and probe tip to oscillate toward and away from said specimen surface contours at a desired frequency in cycles of near and far excursions of said probe tip relative to said specimen surface;
- sampling means for sampling selected portions of cycles of said deflection signal corresponding to said cycles of near and far excursions of said probe tip and for generating output signal data indicative of elevation of said surface contours of said specimen;
- phase control means connected to said deflection measuring means for receiving said deflection signals, said phase control means being connected to said sampling means for controlling the sampling of said selected portions of cycles of said deflection signal;
- and
- means for storing said output signal data.
A synchronous sampling scanning force microscope for examining surface contours of a specimen, said specimen surface also having an attractive region and a repulsive region, the microscope comprising:
- a body, said body including a cantilever arm having a first end secured to said body and a free end, said cantilever arm having a fundamental resonance frequency;
- probe means secured to said free end of said cantilever arm, said probe means including a probe tip adapted to follow the surface contours of the specimen with a substantially constant amount of force;
- scanning means for mounting said specimen for examination by said microscope and adapted to scan said specimen relative to said body;
- deflection measuring means for measuring motion of said cantilever arm and for generating an output signal indicative of an amount of deflection of said cantilever arm means;
- oscillator drive means connected to said cantilever arm for causing the cantilever arm and probe tip to oscillate toward and away from said specimen surface contours at a desired frequency in cycles of near and far excursions of said probe tip relative to said specimen surface;
- sampling means for sampling selected portions of cycles of said deflection signal corresponding to said cycles of near and far excursions of said probe tip and for generating output signals indicative of elevation of said surface contours of said specimen;
- phase control means connected to said deflection measuring means for receiving said deflection signal and connected to said sampling means for controlling the sampling of said selected portions of cycles of said deflection signal;
- and
- memory means for storing said output signals.
A method for synchronous sampling detection of an oscillating cantilever of a scanning force microscope for examining surface contours of a specimen, said microscope having a body, a cantilever arm having a first end secured to said body and a free end, said cantilever arm having a fundamental resonance frequency, probe means secured to said free end of said cantilever arm and including a probe tip adapted to follow the surface contours of the specimen with a substantially constant amount of force, scanning means for mounting said specimen for examination by said microscope and adapted to scan said specimen relative to said body, deflection measuring means for measuring deflection of said cantilever arm and for generating a deflection signal indicative of an amount of deflection of said cantilever arm, the method comprising:
- oscillating said free end of said cantilever arm to cause the probe tip to oscillate toward and away from said specimen surface contours at a desired frequency in cycles of near and far excursions of said probe tip relative to said specimen surface;
- sampling selected portions of cycles of said output signal corresponding to said cycles of near and far excursions of said probe tip and for generating output signal data indicative of relative elevation of said surface contours of said specimen;
- controlling the sampling of said selected portions of cycles so that said sampling occurs during predetermined phases of each cycle of said deflection signal;
- storing said output signal data;
- and
- displaying an image of said surface contours of said specimen based upon said output signal data.
In a scanning force microscope for examining surface contours of a specimen, said microscope having a body, a deflection arm having a first end secured to said body and a free end, said deflection arm having a fundamental resonance frequency, probe means secured to said free end of said deflection arm and including a probe tip adapted to follow the surface contours of the specimen, scanning means for mounting said specimen for examination by said microscope and adapted to scan said specimen relative to said body, and deflection measuring means mounted to said body for measuring motion of the deflection arm and generating a deflection signal indicative of deflection of said deflection arm, the improvement which comprises:
- oscillator drive means connected to said deflection arm for causing deflection arm and the probe tip to oscillate toward and away from said specimen surface contours at a desired frequency in cycles of near and far excursions of said probe tip relative to said specimen surface;
- sampling means for sampling selected portions of cycles of said output signal corresponding to said cycles of near and far excursions of said probe tip and for generating output signals representing deflection of said near and far excursions of said probe tip at said selected portions of said cycles;
- control means connected to said deflection measuring means for receiving said deflection signal and connected to said sampling means for controlling the sampling of said selected portions of cycles of said deflection signal;
- and
- means for storing said output signals.
A method for examining surface contours of a specimen using a scanning force microscope, said microscope having a body, a deflection arm having a first end secured to said body and a free end, said deflection arm having a fundamental resonance frequency, probe means secured to said free end of said deflection arm and including a probe tip adapted to follow surface contours of the specimen, scanning means for mounting said specimen for examination by said microscope and adapted to scan said specimen relative to said body, and deflection measuring means mounted to said body for measuring motion of the deflection arm and generating a deflection signal indicative of an amount of deflection said deflection arm, the steps of the method comprising:
- oscillating said free end of said deflection arm to cause the probe tip to oscillate toward and away from said specimen surface contours at a desired frequency in cycles of near and far excursions of said probe tip relative to said specimen surface;
- sampling selected portions of cycles of said output signal corresponding to said cycles of near and far excursions of said probe tip and for generating output signal data representing deflection of said near and far excursions of said probe tip at said selected portions of said cycles;
- controlling the sampling of said selected portions of cycles so that said sampling occurs during predetermined phases of each cycle of said deflection signal;
- and
- storing said output signal data.
Dependencies are inferred from the claim text.