Apparatus for microindentation hardness testing and surface imaging incorporating a multi-plate capacitor system

In a scanned probe microscope apparatus having a probe and a scanning head arranged for operative engagement of a surface of a sample for measuring a surface topography thereof, the improvement comprising:

• a. said probe having a hardness greater than a sample to be tested;
• b. a force sensor operatively located to measure the force between said sample and said probe, said force sensor having an output signal, wherein said force sensor includes,
• i. a pair of capacitive transducers, each transducer including a separate drive plate, the first of said drive plates having a hole centrally disposed therethrough, and a shared pick-up plate, said pick-up plate positioned between said separate drive plates and separated from each drive plate by an insulating spacer, said drive plates having spaced opposing conductive surfaces when said pick-up plate is mounted therebetween, said pick-up plate further including a conductive central plate suspended by spring means between said drive plates, wherein said central plate is capable of deflection between the conductive surfaces of each of said drive plates;
• and
• ii. means for transmitting force from a point remote from said central plate to said central portion;
• c. means for measuring the output signal of said force sensor and utilizing said output signal to control a vertical movement of said scanning head to maintain a constant force on a sample as said surface topography is measured;
• and
• d. wherein said probe is mounted on said force sensor and said force sensor is further mounted on said scanning head for operatively engaging said sample on a fixed surface.

In a scanned probe microscope apparatus having a probe and a scanning head arranged for operative engagement of a surface of a sample for measuring a surface topography thereof, the improvement comprising:

• a. said probe having a hardness greater than a sample to be tested;
• b. a force sensor operatively located to measure the force between said sample and said probe, said force sensor having an output signal, wherein said force sensor includes,
• i. a first substrate layer having a metalized inner and a metalized outer surface, said metalized outer surface defining a first exterior surface of said force sensor and said metalized inner surface including a first plate of a first variable capacitor, said first plate further having a hole centrally disposed therethrough;
• ii. a second substrate layer including an insulating layer, said second substrate layer having an open central portion, said second substrate layer further having a first and second surface, said first surface mounted in planar contact with said inner surface of said first substrate layer;
• iii. a third substrate layer having a first and second surface, said first surface mounted in planar contact with said second surface of said second substrate layer, said third substrate layer made from a conducting material and having a central plate which is suspended by spring means;
• iv. a fourth substrate layer including an insulating layer, said fourth substrate having an open central portion, said fourth substrate layer further having a first and second surface, said first surface mounted in planar contact with said second surface of said third substrate layer;
• v. a fifth substrate layer having a metalized inner and a metalized outer surface, said metalized outer surface defining a second exterior surface of said force sensor and said metalized inner surface forming a first plate of a second variable capacitor, said inner surface of said fifth substrate mounted in planar contact with said second surface of said fourth substrate;
• and
• vi. means for transmitting force from a point remote from said central plate to said central plate;
• and
• c. means for measuring the output signal of said force sensor and utilizing said output signal to control a vertical movement of said scanning head to maintain a constant force on a sample as said surface topography is measured.

In a scanning tunneling microscope apparatus having a base for mounting a sample thereon and a piezo actuated head having a probe mounted thereon for operative engagement of a sample mounted on said base for measuring a surface topography, the improvement comprising:

• a. a probe having a hardness greater than a sample to be tested mounted on said piezo actuated head;
• b. a force sensor mounted on said base for mounting a sample, said force sensor having an output signal, wherein said force sensor includes,
• i. a pair of capacitive transducers, each transducer including a separate drive plate, the first of said drive plates having a hole centrally disposed therethrough, and a shared pick-up plate, said pick-up plate positioned between said separate drive plates and separated from each drive plate by an insulating spacer, said drive plates having spaced opposing conductive surfaces when said pick-up plate is mounted therebetween, said pick-up plate further including a conductive central plate suspended by spring means between said drive plates, wherein said central plate is capable of deflection between the conductive surfaces of each of said drive plates;
• and
• ii. means for transmitting force from a point remote from said central plate to said central plate;
• and
• c. means for measuring the output signal of said force sensor and utilizing said output signal to control a vertical movement of said piezo actuated head to maintain a constant force on a sample as said surface topography is measured.

In a scanning tunneling microscope apparatus having a base for mounting a sample thereon and a piezo actuated head having a probe mounted thereon for operative engagement of a sample mounted on said base for measuring a surface topography, the improvement comprising:

• a. a probe having a hardness greater than a sample to be tested mounted on said piezo actuated head;
• b. a force sensor mounted on said base for mounting a sample, said force sensor having an output signal, wherein said force sensor includes,
• i. a first substrate layer having a metalized inner and a metalized outer surface, said metalized outer surface defining a first exterior surface of said force sensor and said metalized inner surface including a first plate of a first variable capacitor, said first plate further having a hole centrally disposed therethrough;
• ii. a second substrate layer including an insulating layer, said second substrate layer having an open central portion, said second substrate layer further having a first and second surface, said first surface mounted in planar contact with said inner surface of said first substrate layer;
• iii. a third substrate layer having a first and second surface, said first surface mounted in planar contact with said second surface of said second substrate layer, said third substrate layer made from a conducting material and having a central plate which is suspended by spring means;
• iv. a fourth substrate layer including an insulating layer, said fourth substrate having an open central portion, said fourth substrate layer further having a first and second surface, said first surface mounted in planar contact with said second surface of said third substrate layer;
• v. a fifth substrate layer having a metalized inner and a metalized outer surface, said metalized outer surface defining a second exterior surface of said force sensor and said metalized inner surface forming a first plate of a second variable capacitor, said inner surface of said fifth substrate mounted in planar contact with said second surface of said fourth substrate;
• and
• vi. means for transmitting force from a point remote from said central plate to said central plate;
• and
• c. means for measuring the output signal of said force sensor and utilizing said output signal to control a vertical movement of said piezo actuated head to maintain a constant force on a sample as said surface topography is measured.