WO1996030717A1 - Micromechanical probe for a scanning microscope - Google Patents

Micromechanical probe for a scanning microscope Download PDF

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Publication number
WO1996030717A1
WO1996030717A1 PCT/EP1996/001321 EP9601321W WO9630717A1 WO 1996030717 A1 WO1996030717 A1 WO 1996030717A1 EP 9601321 W EP9601321 W EP 9601321W WO 9630717 A1 WO9630717 A1 WO 9630717A1
Authority
WO
Grant status
Application
Patent type
Prior art keywords
characterized
layer
scanning
boom
sensor according
Prior art date
Application number
PCT/EP1996/001321
Other languages
German (de)
French (fr)
Inventor
Manfred Weihnacht
Günter Martin
Karlheinz Bartzke
Wolfgang Richter
Original Assignee
Carl Zeiss Jena Gmbh
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date

Links

Classifications

    • GPHYSICS
    • G01MEASURING; TESTING
    • G01QSCANNING-PROBE TECHNIQUES OR APPARATUS; APPLICATIONS OF SCANNING-PROBE TECHNIQUES, e.g. SCANNING PROBE MICROSCOPY [SPM]
    • G01Q60/00Particular types of SPM [Scanning Probe Microscopy] or microscopes; Essential components thereof
    • G01Q60/02Multiple-type SPM, i.e. involving more than one SPM techniques
    • G01Q60/04STM [Scanning Tunnelling Microscopy] combined with AFM [Atomic Force Microscopy]
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01QSCANNING-PROBE TECHNIQUES OR APPARATUS; APPLICATIONS OF SCANNING-PROBE TECHNIQUES, e.g. SCANNING PROBE MICROSCOPY [SPM]
    • G01Q10/00Scanning or positioning arrangements, i.e. arrangements for actively controlling the movement or position of the probe
    • G01Q10/04Fine scanning or positioning
    • G01Q10/045Self-actuating probes, i.e. wherein the actuating means for driving are part of the probe itself, e.g. piezoelectric means on a cantilever probe
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01QSCANNING-PROBE TECHNIQUES OR APPARATUS; APPLICATIONS OF SCANNING-PROBE TECHNIQUES, e.g. SCANNING PROBE MICROSCOPY [SPM]
    • G01Q60/00Particular types of SPM [Scanning Probe Microscopy] or microscopes; Essential components thereof
    • G01Q60/02Multiple-type SPM, i.e. involving more than one SPM techniques
    • G01Q60/06SNOM [Scanning Near-field Optical Microscopy] combined with AFM [Atomic Force Microscopy]

Abstract

The invention addresses the task of designing a universally applicable micromechanical probe for scanning microscopes which will facilitate scanning-microscopic investigations with higher lateral resolution and high measurement speed. The probe comprises a support and connected thereto an extension arm which takes the form of a packet of layers including at least one piezo-layer and several metal layers and at its free end carries a microprobe tip. The multiple-layer extension arm combines the probe functions entailed by atomic force microscopy (AFM), scanning-tunnelling microscopy (STM) and optical near-field microscopy (SNOM) by applying to the piezo-layer(s) an alternating voltage whose frequency matches one of the resonance frequencies of the extension arm, and by providing the extension arm with at least one optical transmission layer which is connected to an optically transparent microprobe tip so as to conduct light. The probe can be used to obtain topological, electrical and optical measured data from surfaces.

Description

Micromechanical probe for scanning microscopes

description

The invention relates to the field of metrology and be¬ making a micromechanical probe for scanning microscopes. The probe is applicable for atomic force microscopy (AFM), the scanning tunneling microscopy (STM) and the optical Nahfeldmikro- microscopy (SNOM) that topological, electrical and optical measurement data can be obtained from surfaces.

In the AFM and the STM probe mounted on a micro-scanning at a distance of a few nanometers is guided over the surface to be examined. are evaluated during the AFM detected by the micro-scanning interatomic forces and in the case of STM, the tunneling current of a few nA. which sets at a voltage of a few mV between the tip and a elek¬ trically conductive surface. Significantly to the technical realization are piezo actuators, the ge with resolutions picometers the probe guide in the near field of the surface equipped. An interaction sensing measurement technique, and a control mechanism Upon scanning the distance between the probe tip and Mikro¬ con- stant surface to be examined on picometers. In the SNOM probe is substantially smaller than the wavelength of light as a rule of an optically transparent tip with an aperture. The probe is run in Nah¬ field over the sample to be examined and serves to send out its aperture outgoing light to the sample. Outside the probe also serves as the light receiver or Total¬ reflection of light at the sample surface in the evanescent field for the suction of photons. Micromechanical sensors for the AFM and STM are already known in various embodiments.

Thus 4,912,822 a designed for the STM arrangement is described for example in US-PS, the static movements in three mutually perpendicular coordinate directions possible. The arrangement, which is constructed by the cantilever auf¬ principle and is manufactured by microelectronics technologies, has the form of a cantilever with befindlicher end micro-scanning. The boom is formed as a layer package consisting of 2 piezoelectric layers and a plurality of metal layers serving as electrodes. The metal layers are above, below and between the piezo layers and also laterally from one another. The micro-scanning is made of tantalum or another electrically conductive material her¬ and arranged perpendicular to the surface of the layer package an¬. The movements of the boom are approaching the micro-scanning the surface to be examined and the side guide over the surface. The movements are made possible by use of the converse piezoelectric effect in thin layers on both sides of electrodes are umge¬ ben. the lamina pack is deformed by applying electric voltages to the electrodes of the layered package. The deformation is possible as longitudinal stretching and bending. This makes it possible to move the micro-scanning in all three directions Raum¬. different electrical DC potentials to be applied to selected electrode pairs as required. These potentials lead to movements in the longitudinal, transverse direction and thickness and for tilting the micro-scanning. In order that the micro-scanning may both define the surface approximated as also moved laterally and tilted. For example, there is provided the micro-scanning to keep up with the help of applied voltages in such a distance to a conductive surface, that the tunnel current between the probe tip and the surface is constant. The possible application of this arrangement is limited to the STM.

Also known is a micromechanical probe, which is composed of a quartz oscillator and a stylus (Intern. Journ. Opto Electronics, 1993, Vol. 8, Nos. 5/6. 669-676). The piezo¬ electrically energized stylus oscillates at a frequency of 1 MHz perpendicular to the to be assayed sample surface and allows a material-saving determination of the repulsive forces from the measurement of the phase behavior of the vibrating the force field of the sample needle tip purely electrically. The use of this probe is limited to the AFM. Your Kraft¬ sensitivity is only in the range of nN and the law applicable to the measurement dynamic time constant τ only in the ms range.

The invention has for its object to provide a universal an¬ reversible micromechanical probe for scanning microscopes, the scanning microscopy with a higher lateral resolution as well as a need in the microsecond range smaller time constant τ enables and guarantees a high measuring speed.

This object is achieved according to the invention with the claims in the Patent¬ shown micromechanical probe.

The probe consists of a carrier and an associated, formed as a multilayer boom which includes at least one piezoelectric layer and a plurality of metal layers, and carrying a micro-scanning at its free end, wherein the multi-layered boom the Sondenfunktioneπ for the implementation of atomic force microscopy (AFM), scanning tunneling microscopy (STM) and the optical near-field microscopy (SNOM) combines in itself by applying an alternating voltage is applied to the piezoelectric layer / s, the frequency of which coincides with one of the resonance frequencies of the cantilever, and by the boom at least includes a light guide layer, which is connected light-conducting with an optically transparent micro-scanning.

According to advantageous embodiments of the invention is an alternating voltage to the piezo layer / s is applied, whose frequency corresponds with the longitudinal resonance of the cantilever and the micro-scanning at the free end of the boom is arranged on the end face of the light guide layer. Conveniently, the package of layers forming the boom may be continued as a layer system on or in the carrier.

The piezo layer / s may be made of zinc oxide (ZnO) or aluminum nitride consist (A1N), or a PZT material.

According to one embodiment of the invention the can Piezo¬ layer / s of the layer package on the fixed end of the cantilever starting extend only over part of the length of the boom. Also, the metal layers of the layer packet to the fixed end of the cantilever may starting extend only over part of the length of the boom.

According to an advantageous embodiment of the invention, the metal layer on the surface of the piezoelectric layer is locally interrupted, so that two strip-shaped, diametrically opposed piezo-resonators are present, which are connected with its one end in a vibration node with each other.

For the STM the probe is one of the Metall¬ may conveniently be performed layers to the end of the micro-scanning.

The optical waveguide layer is made according to the invention of a high optical refractive index material, preferably silicon carbide (SiC).

Conveniently, the optical waveguide layer at the free end of the boom is itself formed tapering towards micro-scanning.

The micromechanical sensor according to the invention is distinguished over the prior art by the fact that it is applicable to a multi-mode scanning probe microscopy by at scanning microscopes universally for the AF _ which can be used in STM and SNOM with which topological, electrical and optical measurement data can be obtained from surfaces. the comparison with the known solutions substantially higher performance parameters are of particular advantage. So solution principle of the invention offers the possibility of a substantial reduction in the probe dimensions. In this way, a reduction of the masses and increasing the operating frequency to values ​​well above 1 MHz, for example in the range of 50 to 100 MHz can be realized, and thus the scanning sensitivity or the lateral resolution of about 50 nm, and the measurement speed significantly elevated.

The involvement of the invention intended for the SNOM light optical means and their configuration is advantageous. Hereinafter, a purely dielectric optical waveguide is used of a particularly high refractive index material to a spatial concentration of light instead of the usual metal-coated probe tip. This optical waveguide guides the light without significant loss of reflection or absorption. Due to the particularly high refractive index of the cross-section of the optical waveguide may be very low, whereby a local illumination of an object with great light intensity or the local detection of the light intensity in the near field of an object is possible with low optical losses. This reduces the time required to scan a microscopic image compared to the conventional arrangements can be shortened.

The invention with reference to an embodiment of the micro-mechanical sensor is explained in more detail. The associated drawing shows the probe in a perspective view.

The illustrated probe combines the microscopy for Kraft¬ that tunneling microscopy and optical microscopy Nahfeld¬ functions required, making for multi-mode-scanning microscopes use.

In this probe protrudes over a carrier 1, a boom 2 which is equipped with two piezoelectric aus¬ Resonatorzungen 3 and 4. FIG. At the end of Resonatorzunge 3 there is a stylus tip 5. The boom 2 consists of a layer package, the layer of an optical waveguide layer 6, a first Metall¬ 7, a piezoelectric layer 8, and a second metal layer 9 composed. The metal layers 7 and 9 have in the area of ​​the support to contact points 10 to. 13 The Resonatorzungen 3 and 4 are excited with the help of the rule piezoelektri¬ layer 8 to the longitudinal vibrations. For this purpose, filters between the metal layers 7 and 9 on the Kontakt¬ 10 and 11 for the Resonatorzunge 3 and via the contact set 12 and 13 for the Resonatorzunge 4 an AC voltage. Its frequency is selected such that the wavelength of the longitudinal vibrations in the Resonatorzungen 3 or 4 occupies four times the value of the length of Resonatorzungen. In this case, the ends of the Resonatorzungen swing of maximum amplitude, and is formed at their junction node of vibration. If the Resonatorzunge not as a reference resonator for Re¬ sonatorzunge 3 are used, the second metal layer 9 is binding site on the Verbin¬ between Resonatorzunge 3 and Resonatorzunge 4 -in deviation for this Ausführungsbeispiel- not executed is interrupted and the AC voltage is, for example, only at the contact points 10 and 11 are applied.

When approaching the oscillating probe tip 5 in the longitudinal direction to the surface of a sample to be examined surface forces act one on the probe tip. This effect influences the vibration behavior of the Resonatorzunge 3 in such a manner that the Re¬ is shifted sonanzfrequenz and the vibration is attenuated. These changes can via the electrical behavior of the pol Zwei¬ Resonatorzunge 3, the filters via the contact is registered 10 and 11 is measured and used tread pattern via a control loop for tracking the probe tip in accordance with the Ober¬. For mechanical decoupling of the two Resonatorzungen 3 and 4, the Resonatorzunge 4 containing no probe tip and, consequently, its resonant frequency does not change when approaching the sample surface is used as a refer- renzresonator can.

The metal layer 7 lying within the layer stack is performed on the micro-scanning 5 to at the end and thus serves at the same time as an electrode for realizing the function of the probe microscopic tunnel¬.

In the optical waveguide layer 6 is across the gap between

Resonatorzunge carrier 1 and 4 coupled light propagating in the direction of the probe tip 5 and passes this on to sample under investigation. The light path may also be in umgekehr¬ ter direction for detecting optical signals from the sample using be¬. Using the procedure to keep the distance of the probe tip to the sample surface constant 5 described above, the sample surface can be visually observed under constant conditions.

Claims

claims
1. A micromechanical sensor for scanning microscopes, comprising a carrier and boom formed an associated, aus¬ as a multilayer comprising at least a piezoelectric layer and a plurality of metal layers, and carrying a micro-scanning at its free end, characterized in that the multilayer boom (2 ), the probe functions to perform the atomic force microscopy (AFM), scanning tunneling-Mikro¬ microscopy (STM) and the optical near-field microscopy (SNOM) combines in itself by applying an alternating voltage is applied to the piezoelectric layer / s (8) , whose frequency corresponds to one of the resonance frequencies of the cantilever (2) and by the boom (2) includes at least one light guide layer (6) which is connected light-conducting with an optically transparent micro-scanning.
2. A micromechanical sensor according to claim 1, gekenn¬ characterized characterized in that s (8) an alternating voltage is applied to the piezoelectric layer / whose frequency coincides with the longitudinal resonance of the Ausle¬ gers (2), and that the micro-scanning (5) at the free end of the boom (2) at the end face of the light guide layer (6) is arranged.
3. A micromechanical sensor according to claim 1, characterized gekenn¬ characterized in that the package-forming layer the boom (2) as a layer system on or in the support (1) is continued.
4. A micromechanical sensor according to claim 1, characterized gekenn¬ characterized in that the piezoelectric layer / s (8) of zinc oxide (ZnO) or aluminum nitride (A1N), or a PZT material exist.
5. A micromechanical sensor according to claim 1, characterized gekenn¬ characterized in that the piezoelectric layer / s (8) of the layer package on the fixed end of the boom (2) extend, starting only over part of the length of the boom (2).
6. A micromechanical sensor according to claim 1, characterized gekenn¬ characterized in that the metal layers (7; 9) of the layer package over only a part of the length of the boom (2) extend.
7. A micromechanical sensor according to claim 1, gekenn¬ thereby characterized, that one of the metal layers (9) is interrupted on the surface of the piezoelectric layer (8) in places, such that two strip-shaped, diametrically disposed piezo resonators (3; 4) are present, with are connected together at one end in an oscillation node.
8. A micromechanical sensor according to claim 1, characterized gekenn¬ characterized in that one of the metal layers (7) is guided to the end of the micro-scanning (5).
9. A micromechanical sensor according to claim 1, characterized gekenn¬ characterized in that said light waveguide layer (6) consists of a high optical refractive index material, preferably silicon carbide (SiC).
10. A micromechanical sensor according to claim 1, characterized gekenn¬ characterized in that said light waveguide layer (6) is tapered towards the free end of the boom (2) to the micro-scanning (5).
PCT/EP1996/001321 1995-03-30 1996-03-26 Micromechanical probe for a scanning microscope WO1996030717A1 (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
DE19511612.7 1995-03-30
DE19511612 1995-03-30
DE19531466.2 1995-08-26
DE1995131466 DE19531466C2 (en) 1995-03-30 1995-08-26 Micromechanical probe for scanning microscopes

Publications (1)

Publication Number Publication Date
WO1996030717A1 true true WO1996030717A1 (en) 1996-10-03

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PCT/EP1996/001321 WO1996030717A1 (en) 1995-03-30 1996-03-26 Micromechanical probe for a scanning microscope

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0480645A1 (en) * 1990-10-09 1992-04-15 Canon Kabushiki Kaisha Cantilever type probe, scanning tunnel microscope and information processing apparatus using the same
US5354985A (en) * 1993-06-03 1994-10-11 Stanford University Near field scanning optical and force microscope including cantilever and optical waveguide
WO1995003561A1 (en) * 1993-07-22 1995-02-02 British Technology Group Limited Intelligent sensor for near field optical device
EP0652414A1 (en) * 1993-11-05 1995-05-10 Seiko Instruments Inc. Scanning near-field optic/atomic force microscope
WO1996003641A1 (en) * 1994-07-28 1996-02-08 Kley Victor B Scanning probe microscope assembly

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0480645A1 (en) * 1990-10-09 1992-04-15 Canon Kabushiki Kaisha Cantilever type probe, scanning tunnel microscope and information processing apparatus using the same
US5354985A (en) * 1993-06-03 1994-10-11 Stanford University Near field scanning optical and force microscope including cantilever and optical waveguide
WO1995003561A1 (en) * 1993-07-22 1995-02-02 British Technology Group Limited Intelligent sensor for near field optical device
EP0652414A1 (en) * 1993-11-05 1995-05-10 Seiko Instruments Inc. Scanning near-field optic/atomic force microscope
WO1996003641A1 (en) * 1994-07-28 1996-02-08 Kley Victor B Scanning probe microscope assembly

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
MOERS M H P ET AL: "PHOTON SCANNING TUNNELING MICROSCOPE IN COMBINATION WITH A FORCE MICROSCOPE", JOURNAL OF APPLIED PHYSICS, vol. 75, no. 3, 1 February 1994 (1994-02-01), pages 1254 - 1257, XP000430030 *
ZENHAUSERN F ET AL: "APERTURELESS NEAR-FIELD OPTICAL MICROSCOPE", APPLIED PHYSICS LETTERS, vol. 65, no. 13, 26 September 1994 (1994-09-26), pages 1623 - 1625, XP000470295 *

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