JPH0552509A - Probe unit and its manufacture, information processing device, and scanning tunneling electron miscroscope - Google Patents

Abstract

PURPOSE:To improve a productivity, and secure the reproducibility of a same shape, and further secure reliability and stability of information processing in a probe unit with a cantilever shape. CONSTITUTION:A probe unit has a beam-shaped flexible portion 2 which is formed on a substrate and a probe 4 at a free-edge portion of this flexible portion and is constituted of a drive means for allowing the probe to be displaced in a direction which is at least vertical to a substrate surface. The flexible portion is formed at a position which is higher than the substrate surface and a void portion 3 is provided between the flexible portion and the substrate surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanning tunneling electron microscope or a probe unit for detecting a tunnel current used in an information processing apparatus for high density recording, reproducing and erasing of information by applying the principle thereof, and manufacturing thereof. The present invention relates to a method and the above-mentioned device.

[0002]

2. Description of the Related Art In recent years, a scanning tunneling microscope (hereinafter referred to as ST
Abbreviated as M) was developed (G. Binnig eta
l. , Phys. Rev. Lett. 49 (1982)
57), it has become possible to measure a real space image with extremely high resolution (nanometer or less) regardless of whether it is a single crystal or a non-crystal.

The STM is a metal probe (probe).
When a voltage is applied between the conductive material and the conductive material to bring them closer to a distance of about 1 nm, a tunnel current flows during that time. Since this current is very sensitive to changes in the distance between the two and changes exponentially, observe the surface structure in real space with atomic resolution by scanning the probe so that the tunnel current is kept constant. You can

Although the analysis using this STM is limited to the conductive material, it has begun to be applied to the structural analysis of the insulating film thinly formed on the surface of the conductive material. Furthermore, the above-mentioned device,
Since the means uses the method of detecting a minute current, it has an advantage that it can be observed with low power without damaging the medium. Further, since it can be operated in the atmosphere, it is expected to have a wide range of applications of STM. In particular, JP-A-63-16
As proposed in Japanese Laid-Open Patent Publication No. 1552 and Japanese Laid-Open Patent Publication No. 63-161553, practical application as a high-density recording / reproducing device is being actively promoted. This is for recording by changing the voltage applied between the probe and the recording medium by using a probe similar to the STM, and the recording medium shows a switching characteristic having a memory property in the voltage-current characteristic. Materials, eg chalcogenides, π
A thin film layer of an electronic organic compound is used. On the other hand, reproduction is performed by changing the tunnel resistance between the recorded area and the non-recorded area. As a recording medium using this recording method, recording / reproduction is possible even if the surface shape of the recording medium changes depending on the voltage applied to the probe.

Conventionally, a semiconductor manufacturing process technology has been used as a probe forming method, and a processing technology for manufacturing a fine structure on one substrate (KE Peterson, “Silic”).
onas a Mechanical Material
l ”, Proceedings of the IEEE
E, vol70, P420, 1982), an STM constructed by using the method is proposed in JP-A-61-206148. This is a tongue-shaped structure with a cantilever structure in which a single crystal silicon substrate is used to form a parallel spring that can be finely moved in a direction parallel to the substrate surface (XY direction) by microfabrication, and a probe is formed on the movable part. A portion is provided, and an electric field is applied between the tongue portion and the bottom portion to be displaced in a direction (Z direction) perpendicular to the substrate surface by electrostatic force. Further, Japanese Patent Laid-Open No. 62-281138 discloses a storage device having a transducer array in which a plurality of tongue-shaped portions are arranged in the same manner as disclosed in Japanese Patent Laid-Open No. 61-206148. ..

[0006]

However, the conventional cantilever type probe has the following problems. Since the silicon substrate is deeply processed by anisotropic etching in the production of the cantilever, the processing takes time and the productivity is low. Further, since some etching liquids contain alkali ions, there is a problem that when the drive circuit (IC or the like) is integrally formed, it is contaminated and the characteristics are deteriorated. When the cantilever type probe is used in an STM, a recording / reproducing apparatus, or the like, it is necessary to bring the sample or the medium arranged to face each other in a face-to-face relationship. Therefore, in the case of the probe protruding from the vicinity of the surface of the substrate, there is a problem that the protrusions due to the surface irregularities of both of them and the dust or the like attached to the surface of the substrate come into contact with the probe before the probe, which hinders stable operation. ..

Therefore, the object of the present invention was made in view of the problems of the above-mentioned conventional example, and a probe unit having improved productivity and reproducibility, and a scanning tunnel electron microscope excellent in reliability and stability. , Providing an information processing device.

[0008]

The structure of the present invention for achieving the above object is as follows.

A probe comprising a beam-shaped flexible portion formed on a substrate, a probe on the free end side of the flexible portion, and a drive means for displacing the probe at least in a direction perpendicular to the substrate surface. In the unit, the flexible portion is formed at a position higher than the surface of the substrate, and a probe unit is provided with a gap between the flexible portion and the surface of the substrate.

Furthermore, a first step of forming a convex portion on the substrate by film formation and patterning, a second step of forming the flexible portion so as to extend over the convex portion and the substrate surface by film formation and patterning, A method of manufacturing a probe unit including a third step of forming a probe on a flexible portion and a fourth step of removing the convex portion, and further, one or a plurality of probes facing the medium are independently driven to form a medium. In an information processing device that writes information to and erases the written information,
An information processing apparatus including the probe unit as a probe unit, and an information processing apparatus that independently drives one or a plurality of probes facing a medium to read information from the medium. An information processing device including the probe unit,
Furthermore, in an information processing apparatus that independently drives one or a plurality of probes facing a medium to write, read, and erase information on the medium, an information processing apparatus including the probe unit as a probe unit. A scanning tunneling electron microscope for inspecting a sample by independently driving one or a plurality of probes facing the sample, the scanning tunneling electron microscope including the probe unit as a probe unit; It is characterized by.

That is, according to the present invention, the flexible portion is formed so as to straddle the convex portion formed on the substrate and the substrate surface, and then the convex portion is removed to form the beam-shaped flexible portion. Therefore, the substrate does not have to be processed by anisotropic etching. Further, when this probe unit is used in an STM, an information processing device or the like, the influence of irregularities on the substrate surface, dust, etc. can be reduced because the flexible portion projects from the substrate surface.

Here, the beam-shaped flexible portion refers to a beam structure with one end fixed in which one end of the flexible portion is fixed on the substrate, that is, a cantilever structure. Then, at least a mechanism and wiring for driving, and a wiring region for applying a voltage to the probe are formed on the cantilever. At this time, the shape of the cantilever is arbitrary.

As means for displacing the cantilever, piezoelectric effect, electrostatic force, bimetal, etc. are generally known, but displacement means by electrostatic force is preferably used in view of displacement amount, driving voltage and controllability. ..

Next, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a side view of a probe unit according to the present invention, in which 1 is a substrate, 2 is a flexible portion, 3 is a void portion, and 4 is a void portion.
Is a probe. As shown in the figure, a beam-shaped flexible portion 2 is formed on a substrate 1. A gap 3 is formed between the substrate 1 and the beam-shaped flexible portion. Further, the probe 4 is formed on the free end side of the beam-shaped flexible portion.

FIG. 2 is a sectional view showing the main steps of forming a probe unit according to the present invention. In FIG. 2A, first, the substrate 1 is prepared. As the substrate 1, a material such as semiconductor, metal, glass, ceramics can be used.

Next, as shown in FIG. 2B, the convex portion 5 is formed on the substrate 1. Since the convex portion 5 according to the present invention is used as a sacrificial layer to be removed in a later step, any material that can be selectively etched with the flexible portion 2 during etching may be used. As a method of forming the convex portion 5, a conventionally known technique, for example, a thin film forming technique such as a vacuum vapor deposition method, a sputtering method, a chemical vapor deposition method or the like, which is generally used in the semiconductor industry, a photolithography technique, and an etching technique are used. It can be applied, and its manufacturing method does not limit the present invention.

Next, as shown in FIG. 2C, the flexible portion 2 is formed so as to straddle the convex portion 5 and the substrate surface. Here, the flexible portion 2 is configured to use the drive mechanism described above. For example, in the case of electrostatic driving, the electrodes are formed by sputtering or vapor deposition, photolithography and etching by a conventionally known manufacturing method. Then, the probe 4 is formed on the free end side of the flexible portion 2. Here, as a method of forming the probe 4, a conventionally known method such as an etching method, a lift-off method, or a bonding method of micro pieces can be used.

Next, as shown in FIG. 2D, the convex portion 5 is removed by etching to form the void portion 3, whereby a probe unit having a beam-shaped flexible portion can be formed.

By using such a probe unit, it is possible to displace the probe position in the Z direction by applying a voltage to the electrode to bend the beam-shaped flexible portion in a direction perpendicular to the substrate surface (Z method). ..

[0021]

EXAMPLES The present invention will be specifically described below with reference to examples.

(Embodiment 1) FIG. 2 shows a first embodiment of the present invention.
Will be described with reference to. First, a silicon wafer on which a thermal oxide film of 5000 Å is formed is prepared as the substrate 1. Subsequently, Cr was deposited on the substrate 1 by a 2000Å vacuum deposition method, and patterning was performed by photolithography and etching to form the lower electrode 6 ((a) in FIG. 2).

Next, copper is deposited on the substrate 1 by vacuum deposition.
A μm film was formed, and a pattern was formed by photolithography and etching to form a convex portion 5 ((b) in FIG. 2).

Next, the flexible portion 2 was formed so as to straddle the convex portion 5 and the substrate surface. The size of the flexible portion 2 on the convex portion 5 was set to 200 μm in width and 400 μm in length. At this time, 2 μm thick Au was used for the flexible portion 2. At this time, the Au electrode was etched using an aqueous potassium iodide solution. However, in order to improve the adhesion between Au and the thermal oxide film, Cr was formed by a 500Å vacuum deposition method before forming the first layer of Au as an etching protection layer in a later step. The Cr was removed by dry etching using CCl ₂ F ₂ . Subsequently, the probe 4 was formed on the free end side of the flexible portion 2 by vapor deposition and the lift-off method. At this time, Au was used for the probe 4 ((c) in FIG. 2).

Next, using AZ4620 (manufactured by Hoechst), the probe 4 and the flexible portion 2 are photolithographically determined.
After protection, the convex portion 5 was over-etched with an aqueous potassium iodide solution to form the void portion 3 ((d) in FIG. 2). The Cr and thermal oxide films were exposed to the etchant, but they were not etched. Subsequently, the photoresist is removed with acetone to obtain a width of 2
A probe unit having a beam-shaped flexible portion of 00 μm and a length of 400 μm was obtained. When the displacement amount of the electrostatically driven probe unit produced as described above was measured, it was found that the displacement was 0.5 μm / v in the Z direction.

(Embodiment 2) In this embodiment, an information processing apparatus using the probe unit of Embodiment 1 will be described.
The probe unit manufactured according to the present invention is installed in an information processing apparatus having both information recording, reproducing and erasing functions shown in FIG. 3, and a recording medium is disclosed in Japanese Patent Laid-Open No. 63-165152.
Recording, reproducing and erasing experiments were conducted using a laminate of a polyimide LB film (two-layer film) on the Au electrode disclosed in Japanese Patent Laid-Open No. 63-161553 and Japanese Patent Laid-Open No. 63-161553.

In this apparatus, 11 and 12 are a drive section and a displacement mechanism section for performing coarse movement in the Z direction, and fine movement is performed by the flexible range of the cantilever. For driving in the XY directions, 13 acts as a coarse movement and 14 acts as a fine movement mechanism. Z
The directional displacement is servo-controlled, a DC bias voltage is applied between the sample 16 and the probe 4 by the bias power supply 15, the error signal between the current value flowing through the probe and the target value is calculated by the microcomputer 17, and the drive circuit 18 is driven. The cantilever 2 is displaced by.

In such an apparatus, while the probe is scanned in the XY directions, the peak value − is applied to the bias voltage (0.1 V).
Electrical information was written by applying a voltage on which a continuous pulse wave of 6 V and +1.5 V was superimposed between the sample and the probe. Furthermore, as a result of reading the recorded information from the obtained STM image, it was confirmed that the recorded information and the reproduced information match each other with good reproducibility. Moreover, when the probe approached the recorded area on the sample, when the operation of superimposing the pulse voltage of the peak value ЗV on the bias voltage was performed, the recorded information was erased from the reproduced STM image. It was confirmed. Further, during the experiment, no troubles due to the unevenness of the substrate, dust, etc. occurred. Although the probe unit is installed in the information processing apparatus in the present embodiment, it can be applied as a probe unit for a scanning tunnel current detection device such as STM without any change.

[0029]

According to the present invention, since the beam-like flexible portion is formed by etching the sacrificial layer, it is possible to provide a probe unit with improved productivity and reproducibility. Further, in the probe unit of the present invention, since the flexible portion on the beam protrudes from the substrate surface, when used in an information processing device, STM, etc., it is possible to reduce the effects of surface irregularities and dust, etc. sex,
The device has improved reliability.

[Brief description of drawings]

FIG. 1 shows a side view of a first probe unit of the present invention.

FIG. 2 is a cross-sectional view showing the main steps of forming a probe unit of the present invention.

FIG. 3 is a schematic diagram showing a configuration of an information processing device.

[Explanation of symbols]

 1 substrate 2 flexible part 3 void part 4 probe 5 convex part 6 lower electrode 11 Z direction coarse movement drive circuit 12 Z direction coarse movement mechanism 13 XY direction coarse movement mechanism 14 XY direction fine movement scanning mechanism 15 bias power supply and probe current amplifier 16 Sample 17 Microcomputer 18 Servo circuit and probe drive circuit 19 Display device 20 XY direction coarse drive circuit 21 XY stage 22 Scan drive circuit

Front Page Continuation (72) Inventor Yu Nakayama 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (6)

[Claims] 1. A beam-shaped flexible portion formed on a substrate, a probe on the free end side of the flexible portion, and a drive means for displacing the probe at least in a direction perpendicular to the substrate surface. The probe unit according to claim 1, wherein the flexible portion is formed at a position higher than the surface of the substrate, and a gap is provided between the flexible portion and the surface of the substrate. 2. A first step of forming a convex portion on a substrate by film formation and patterning, and a second step of forming the flexible portion so as to straddle the convex portion and a substrate surface by film formation and patterning. A method of manufacturing a probe unit, comprising a third step of forming a probe on a flexible portion and a fourth step of removing the convex portion. 3. An information processing apparatus that independently drives one or a plurality of probes facing a medium to write information to the medium and erase the written information, and uses the probe unit as a probe unit. An information processing apparatus comprising the probe unit described above. 4. An information processing apparatus for independently reading one or a plurality of probes facing a medium to read information from the medium, comprising the probe unit according to claim 1. An information processing device characterized by the above. 5. An information processing apparatus that independently drives one or a plurality of probes facing a medium to write, read, and erase information on the medium, wherein the probe unit is a probe unit. An information processing apparatus comprising the probe unit of. 6. A scanning tunnel electron microscope for inspecting a sample by independently driving one or a plurality of probes facing the sample, comprising the probe unit according to claim 1 as a probe unit. A scanning tunneling electron microscope characterized by the above.