Measuring and testing – Surface and cutting edge testing – Roughness
Reexamination Certificate
1999-06-21
2001-07-10
Williams, Hezron (Department: 2856)
Measuring and testing
Surface and cutting edge testing
Roughness
C250S306000, C250S307000, C250S442110
Reexamination Certificate
active
06257053
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a scanning probe microscope utilizing a piezoelectric member as a distance control means for the probe.
2. Background Art
Conventionally there has been known, as a scanning probe microscope using a piezoelectric member as a distance controlling means for the probe, a scanning probe microscope using, for example, a tuning fork type quartz oscillator. For example, there are disclosures of scanning probe microscopes using such a tuning fork type quartz oscillator in Appl. Phys. Lett. 66(14), 1995, pp 1842-1844, by Khaled Karrai et al and in a publication of JP-A-9-89911.
FIG. 10
is a schematic view of a principal part of a scanning probe microscope using a tuning fork type quartz oscillator.
400
is an optical fiber probe, and
410
is a tuning fork type quartz oscillator. The optical fiber probe is joined to a quartz oscillator by adhesion, and the quartz oscillator is oscillated by an oscillating piezoelectric member (omitted in FIG.
10
). The piezoelectric oscillator if oscillated generates an electric current due to a piezoelectric effect. By detecting this current, it is possible to measure an oscillation state of the quartz oscillator. If the probe approaches a sample, the probe is acted on by a horizontal force from the sample, i.e. a shear force, and the quartz oscillator joined to the probe is changed in oscillation state. The sample-to-probe distance is adjusted using a Z-axis finely moving element (omitted in
FIG. 10
) in a manner of keeping constant a shear force, i.e. a change amount in amplitude or phase of a quartz oscillator output.
However, the foregoing scanning probe microscope using a conventional tuning fork type quartz oscillator has the following problems.
(1) Because the probe is adhesion-fixed to the tuning fork type quartz oscillator, the state of fixing largely varies due to environmental change such as temperature. Also, the state of the fixing portion is difficult to keep constant due to an amount of adhesive or adhesive method. As a result, vibration parameters, such as probe amplitude or Q value, varies or detection characteristics in force detection varies, resulting in instability in control.
(2) Re-utilization of the tuning fork type quartz oscillator is difficult due to fixing by adhesion.
(3) Because fixing is made such that a longitudinal direction of one surface of the tuning fork type quartz oscillator and an axial direction of the probe are parallel, the probe and the oscillator have an increased contact area. The contact area if increased makes difficult the reproducibility of the attaching state, causing an increase in the variation in vibration parameters such as probe amplitude or Q value or detection characteristic in force detection.
(4) In the tuning fork type quartz oscillator, the vibration piece not joined to the probe has an effect upon a detection signal, possibly causing malfunctioning. That is, in the case of the tuning fork type quartz oscillator, the oscillation piece joined to the probe receives a force from a sample through the probe. However, the other vibration piece maintains its natural vibrating state. In this manner, two vibration pieces are quite different in vibration state. One detects a force and changes, while the other does not change so that a resultant output does not directly reflect a force. Where this output is used as a Z servo feedback signal, there has been a defect that a probe-to-sample distance cannot be accurately controlled.
Therefore, the present invention has the following purposes.
(1) To provide a scanning probe microscope which maintains a state of a fixing portion irrespective of environmental change such as temperature or adhesive amount or adhesion method, obtaining stabilized vibration characteristics and detection characteristics.
(2) To provide a scanning probe microscope with which a detecting piezoelectric element can be reused.
(3) To provide a method of fixing a detecting piezoelectric element and probe by which a variation in vibration parameters such as probe amplitude and Q value or a variation in detection characteristic in force detection.
(4) To provide a scanning probe microscope which can accurately control a probe-to-sample distance by obtaining a detecting piezoelectric element that gives an output signal directly reflecting a force undergoing from a sample.
SUMMARY OF THE INVENTION
In order to solve the foregoing problems in the conventional art, a scanning probe microscope of the present invention is structured as stated below.
(1) A scanning probe microscope comprises a probe having a tip formed in a probe needle form, an oscillation section configured by an oscillating piezoelectric member and an alternating current generating means, a vibration detecting section formed by a detecting piezoelectric member and a current/voltage amplifying circuit, a probe holder for holding the probe and the oscillating piezoelectric member and the detecting piezoelectric member, a coarse movement mechanism for approaching the probe to a sample, a sample-to-probe distance control means formed by a Z-axis finely moving element and a Z servo circuit, a two dimensional scanning means formed by an XY finely moving element and an XY scanning circuit, and a data processing unit for making a measurement signal into a three dimensional image. In the scanning probe microscope according to the present invention the probe and the detecting piezoelectric member are joined by spring pressure of an elastic member.
This method eliminates the necessity of an adhesive for joining between the probe and the detecting piezoelectric member. It is possible to obtain a stable vibration characteristic or detection characteristic without suffering an affection of an adhesive. Also, the detecting piezoelectric element can be reused.
(2) The joining between the probe and the detecting piezoelectric member utilizes elasticity of the probe as it is. In this case, provided in the probe holder is an attaching portion defining an attaching angle of between the probe and the detecting piezoelectric member such that the probe at a tip is perpendicular to a sample surface.
This method eliminates the necessity of an adhesive for joining between the probe and the detecting piezoelectric member. It is also possible to prevent the resolving power from lowering because the attaching angle between the probe and the detecting piezoelectric member is adjusted such that the probe at its tip
1
a
is perpendicular to the sample surface.
(3) The detecting piezoelectric member is arranged with an inclination in a joining plane relative to the probe such that a contact area in the joining portion between the probe and the detecting piezoelectric member is smaller as compared to a case of joining with a probe axial direction and a detecting piezoelectric member beam longitudinal direction taken generally parallel.
This method reduces to a small amount the contact area between the probe and the detecting piezoelectric member as compared to uniform joining in the longitudinal direction. Even where the probe is exchanged, a reduction is made in a variation in vibration parameters such as probe amplitude or Q value, or in a variation in detection characteristic in force detection.
(4) The detecting piezoelectric member was structured by a piezoelectric beam having one vibration member.
This method provides a detecting piezoelectric element that gives an output signal directly reflecting a force undergone from the sample. Thus a probe-to-sample distance can be accurately controlled.
REFERENCES:
patent: 4343993 (1982-08-01), Binnig et al.
patent: 4785177 (1988-11-01), Besocke
patent: 4800274 (1989-01-01), Hansma et al.
patent: 5146690 (1992-09-01), Breitmeier
patent: 5503010 (1996-04-01), Yamanaka
patent: 5900618 (1999-05-01), Anlage et al.
patent: 5990477 (1999-11-01), Tomita
patent: 6006594 (1999-12-01), Karrai et al.
Hasegawa Masao
Iyoki Masato
Tomita Eisuke
Adams & Wilks
Cygan Michael
Seiko Instruments Inc.
Williams Hezron
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