CN1300565C

CN1300565C - Atomic force microscope measuring device based on angular measurement

Info

Publication number: CN1300565C
Application number: CNB2004100940545A
Authority: CN
Inventors: 刘庆纲; 李志刚; 李德春; 匡登峰; 王璐; 李敏
Original assignee: Tianjin University
Current assignee: Tianjin University
Priority date: 2004-12-28
Filing date: 2004-12-28
Publication date: 2007-02-14
Anticipated expiration: 2024-12-28
Also published as: CN1632519A

Abstract

The invention discloses an atomic force microscope measuring device based on angle measurement, which belongs to a probe/cantilever beam signal detection system and device of an atomic force microscope (AFM). The device uses an optical differential angle sensor on the cantilever beam displacement measurement device of the atomic force microscope. The angle measurement device includes a collimated light source, a converging lens, a 1/4 wave plate, a polarizing beam splitter, a beam splitter, two Critical angle prism, two photodiodes, microdriver for Z-direction tracking, in-plane 2D micromotion scanner, probe holder and AFM probe; and sample stage and in-plane 2D micromotion scanner with AFM The probe and the micro-driver for Z-direction tracking are separated, and the distance is adjustable. The advantage of the present invention is that the Z-direction tracking device is separated from the scanning device in the XY plane, which reduces the requirements or restrictions on the size, weight and scanning range of the measured object. The measured object can be more than ten centimeters × ten centimeters × a few centimeters.

Description

Atomic force microscope measurement mechanism based on measurement of angle

Technical field

The present invention relates to a kind of atomic force microscope measurement mechanism, belong to the detection system and the device of the probe/semi-girder signal of atomic force microscope (AFM) based on measurement of angle.

Background technology

When the end of semi-girder was stressed, its end can produce two kinds of distortion, and a kind of is amount of deflection, and another kind is a corner.Atomic force microscope utilizes the probe at micro-cantilever tip, when probe is surperficial near to or in contact with testee, the interaction of meeting generation power between probe and the sample, this acting force can make micro-cantilever produce bending change, therefore, the variation of micro-cantilever amount of bow can detect by dual mode, and the amount of deflection of promptly measuring the micro-cantilever of atomic force microscope changes, and the most advanced and sophisticated corner of perhaps measuring the micro-cantilever of atomic force microscope changes.

It at present is this quasi-instrument that the bending change of passing through to detect micro-cantilever of representative obtains the testee surface information with the atomic force microscope, the amount of deflection of all adopt measuring behind micro-cantilever stressed changes, the position fixed ends of the semi-girder of AFM probe (comprising the semi-girder and the stationary installation thereof that have needle point) must remain unchanged, AFM 3-D scanning driver must be in a side of sample or probe, multi-functional atomic force microscope as U.S. Veeco company, the atomic force microscopes of NSK etc., common three-dimensional micromotion mechanism all is installed in testee one side.When laser is got on the micro-cantilever, because the variation of micro-cantilever amount of deflection, cause catoptrical beat, make that light spot position changes on the photodetector, by detecting the variable quantity of light spot position, thereby obtain the amount of deflection variable quantity of micro-cantilever, and then obtain dynamometry variable quantity and profiling object surface.Though simply be suitable for commodity production on this method structure, but under this type of microscopical constant force mode, in the scanning process,, thereby introduce measurement principle error owing to the change of probe stationary end position, obtain high-precision measurement result, must carry out error correction or strict correction.This method all has the requirement or the restriction of comparison strictness to size, weight and the sweep limit etc. of testee, as 10 millimeters * 10 millimeters * 1～2 millimeter.

Summary of the invention

The object of the present invention is to provide a kind of atomic force microscope measurement mechanism based on measurement of angle, the particularly detection system of the micro-cantilever signal of atomic force microscope class and apparatus structure design enlarges the atomic force microscope range of application.

The object of the present invention is achieved like this: based on the atomic force microscope measurement mechanism of measurement of angle, the semi-girder displacement measuring device that it is characterized in that atomic force microscope adopts optical differences dynamic formula angular transducer, described optical differences dynamic formula angular transducer has comprised the semiconductor laser 6 of convergent lens integrated, the polarisation spectroscope 12 that the light that laser instrument penetrates has been integrated quarter wave plate reflexes to the surface of AFM probe 3, the light that is reflected by detecting probe surface has incided the spectroscope 11 of quarter wave plate integrated, the two-beam that is divided into incides two critical angle prisms 8 respectively, 10, the light that penetrates from critical angle prism is respectively by two photodiodes 7,9 receive; Z is fixed together to following the tracks of with fine motion driver 1 and probe clamper 2, and AFM probe 3 is fixed on the probe clamper, and 2 dimension fine motion scanners 5 link together in sample stage 4 and the plane; Be loaded with that 2 dimension fine motion scanners are separated with the fine motion driver to following the tracks of with the Z that is connected with probe clamper and AFM probe in the plane of sample stage, this distance is adjustable.

The invention has the advantages that Z is separated to tracking means and XY plane interscan device, reduced the requirement or the restriction of size, weight and sweep limit etc. to testee, testee can be several centimetres of tens cm x, tens cm x.

Description of drawings

Fig. 1 is the AFM measurement mechanism structural representation based on measurement of angle.

1 is that Z is to following the tracks of with fine motion driver PZT among the figure, 2 is AFM probe clamper, 3 is the AFM probe, 4 is sample stage, and 5 is 2 dimension (XY) fine motion scanning platforms in the plane, 6 semiconductor lasers of convergent lens that have been integrated, 7,9 is photodiode, 8,10 is critical angle prism, 11 spectroscopes of quarter wave plate that have been integrated, the 12 polarisation spectroscopes of quarter wave plate that have been integrated.

Embodiment

AFM measuring method based on measurement of angle, the angle at the semi-girder tip that the AFM probe causes owing to stressed variation in scanning process changes, adopt optical differences dynamic formula angular transducer (dotted line inside among Fig. 1) to detect, its process is: the visible light that laser instrument 6 sends is reflected after quarter wave plate by polarisation spectroscope 12 behind convergent lens, incide on semi-girder/AFM probe 3 reflectings surface of atomic force microscope, the corner change information that is carried semi-girder by the laser of AFM probe reflection enters optical differences dynamic formula angular transducer; Optical differences dynamic formula angular transducer is fixed on the angle adjustable platform, and this platform is fixed on the system base; When initial dynamometry setting value, can think that optical differences dynamic formula angular transducer output signal is " zero "; When dynamometry changes in the scanning process, the angle of bend of semi-girder changes, and promptly with respect to the incident light of optical differences dynamic formula angular transducer, its incident angle also produces corresponding variation to reflected light, this variable quantity is a times of micro-cantilever angle variable quantity, and measured obtaining amplified.

Owing to adopt the variate method, after being divided into two-beam from the reflected light of AFM probe by semi-transparent semi-reflecting lens 11, go into to inject two prisms 8 respectively, 10, when catoptrical angle has beat, the incident angle of the incident light of two prisms increases/reduces Δ θ respectively, the reflectance varies amount also increases respectively or reduces, the light intensity of emergent light is by photodiode 7,9 detect and are converted to photocurrent, the two-way photo-signal is through excess current one voltage transformation and addition, behind subtraction and the division arithmetic, obtain the angle variable quantity after the linearization process, promptly this variable quantity is detected and converts to and the proportional electric signal of angle changing value by optical differences dynamic formula angular transducer.This electric signal again through signal analysis and processing, obtains changing owing to dynamometry the angle variation of the semi-girder that causes after amplifying, and then obtains the dynamometry variation/object surface appearance profile of probe.

AFM scanning is planar carried out under computer control by two-dimensional micromotion scanning platform 5 in the surface level, and sample stage 4 combines with this scanning platform; The Z of AFM drives Z to tracking section by feedback control circuit to carry out with fine motion driver 1 to following the tracks of, probe combines to driver with Z through probe holding frame 2, being Z is undertaken by independent driver to motion, based on this structure, realized Z to XY separating to motion.

Claims

1. The atomic force microscope measuring device based on angle measurement is characterized in that the cantilever beam displacement measuring device of the atomic force microscope adopts an optical differential angle sensor; the optical differential angle sensor includes a semiconductor laser integrated with a converging lens (6) , the light emitted by the laser is reflected by the polarizing beam splitter (12) integrated with a 1/4 wave plate to the surface of the atomic force microscope probe (3), and the light reflected by the probe surface is incident on the beam splitter integrated with a 1/4 wave plate Mirror (11), the two beams of light that are divided into are respectively incident on two critical angle prisms (8, 10), and the light emitted from the critical angle prisms is received by two photodiodes (7, 9) respectively; The moving driver (1) is fixed together with the probe holder (2), the atomic force microscope probe (3) is fixed on the probe holder, the sample stage (4) and the in-plane 2-dimensional micro-motion scanner ( 5) connected together; the in-plane 2-dimensional micro-motion scanner carrying the sample stage is separated from the Z-direction tracking micro-driver connected with the probe holder and the atomic force microscope probe, and the distance is adjustable.