JPH0489640A - Recording/playback device and its driving method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a large-capacity, high-density recording/reproducing device.

[Prior Art] In recent years, the data recording capacity of recording and reproducing devices has tended to increase year by year, and the size of the recording unit has become smaller (the recording density has become higher. For example, digital
On audio discs, the recording unit size is 1
It extends to about μm2. Behind this is the active development of memory materials, and inexpensive, high-density recording media using organic thin films such as organic dyes and photopolymers have appeared.

On the other hand, recently, a scanning tunneling microscope (hereinafter abbreviated as STM) that can directly observe the electronic structure of surface atoms of a conductor has been developed [G, B1nn1g et al, He1veti
caPhysica Acta, 55726 (19
[82)], it has become possible to measure real space images with high resolution regardless of whether they are single crystal or amorphous, and has the advantage of being able to observe with low power without damaging the medium due to electric current. Among them, it is expected to have a wide range of applications because it works well and can be used with various materials.

STM utilizes the fact that a tunnel current flows when a voltage is applied between a probe electrode and a conductive substance and the probe electrode and a conductive substance are brought close to a distance of about 1 nm. This current is very sensitive to changes in the distance between the two, and surface information in real space can be obtained by scanning the depth needle while keeping the current or the average distance between the two constant. At this time, the resolution in the in-plane direction is 1
It is about the size of a person.

By applying this STM principle, it is possible to perform high-density recording and playback on the atomic order (several people). The recording and reproducing method at this time is to change the surface condition of the appropriate recording layer using particle beams (electron beams, ion beams), high-energy electromagnetic waves such as X-rays, and energy rays such as visible and ultraviolet rays. There are methods for recording and reproducing using STM, and for recording and reproducing using STM, using a thin film layer of materials such as π-electron organic compounds and chalcogenides that have a memory effect on the switching characteristics of voltage and current as the recording layer. Several methods have been proposed.

When recording and reproducing this STM application, it is necessary to control the distance between the probe and the recording medium in order of order, and to perform several two-dimensional scans of the probe in order to record and reproduce information arranged two-dimensionally on the recording medium. Two points are important: control on the order of 10 people. Furthermore, from the viewpoint of improving the functionality of the recording/reproducing system, especially increasing the speed, it has been proposed to drive a large number of probes simultaneously (probe multiplication). In other words, the relative positions of the probes and the recording medium must be three-dimensionally controlled with the above-mentioned accuracy within an area where a large number of probes are arranged.

Conventionally, this control uses a laminated piezoelectric element 9, a cylindrical piezoelectric element, etc. attached to the probe side or the recording medium side. However, although these elements have large displacements, they are not suitable for integration, and are disadvantageous when used in multi-probe type recording/reproducing devices. A method has been considered in which the device is mounted on a cantilever of about 100 μm and the cantilever is driven by a piezoelectric material.

[Problem to be solved by the invention] However, the conventional example has the following problems.

1. Even if the device is installed in the direction where the maximum displacement can be obtained, only a displacement of about IILm can be obtained.

2. When using multiple probes (for example, 100 to 1000 probes), a recording medium surface of at least 1 mm square is required, so due to the influence of heat distribution 1 mechanical stress, etc., the probes It is difficult to reduce the distance between the recording medium and the recording medium to 1 μm or less.

3. To increase the amount of displacement, the dimensions of the cantilene must be increased, and therefore, the rigidity becomes small, making it extremely susceptible to external vibration noise and making integration difficult.

[Means and effects for solving the problem] In order to solve the problem, according to the present invention, a recording medium for recording information and a probe for information recording or detection are each made of a driveable cantilever (cantilever). beam)
/ A recording/reproducing device characterized in that each cantilever is installed so that the surface of the recording medium faces the probe, and the distance between the probe and the recording medium is controlled by displacing each cantilever in the direction. death,
Furthermore, a method for driving a recording/reproducing apparatus is characterized in that a recording bit string is sequentially recorded or detected by driving each cantilever in a direction perpendicular to the above direction, and a method for driving a recording/reproducing apparatus is characterized in that the physical state of a recording medium is determined by molecules. A recording/reproducing device characterized in that a recording bit is produced by changing the electric characteristics in a scale region, and a recording bit is produced by changing the electrical characteristics of the recording medium by applying an electric field to the recording medium. A recording/reproducing device characterized in that it controls the relative displacement of an information detection probe and a recording medium on a molecular scale and detects recorded bits.
Further, there is provided a recording/reproducing apparatus characterized in that recorded information is detected by a change in tunnel current between a conductive probe and a conductive medium or a conductive electrode at the bottom of the recording medium.

This makes it possible to precisely control the distance and two-dimensional position between the probe and the recording medium, and further expand the control range.

FIG. 1 shows a conceptual diagram of the present invention. First, Si.

A probe 2 for detecting a tunnel current is provided on a probe-side cantilever 1 made of SiN or the like, and a recording medium 4 is provided on a medium-side cantilever 3 facing the probe-side cantilever 1. There is a recording bit string 5 on the recording medium 4, and the cantilevers 1 and 3 are driven in the y- and z-axis directions by piezoelectric force, electrostatic force, etc., and the probe 2 records and detects information on the recording bit string 5. . Here, the cantilevers 1.3 are driven in opposite phases. What is important here is that both the probe 2 and the recording medium 4 are provided on the cantilever. If the length of the cantilever is 4, the resonance frequency f is foc°C2, and the displacement in the y direction Δy
, the z-direction displacement ΔZ is the same size, the rigidity is the same as when only one cantilever is used, but the relative displacement is twice as large.

Therefore, the relative area of the recording medium 4 covered by one probe 2 can be increased, and when a large number of probes are arranged in parallel over a large area, the distance between the probe 2 and the recording medium 4 can be precisely controlled over the entire area. becomes possible.

Furthermore, when recording information of the same area at the same recording/detection speed, the size of the cantilever can be smaller than when only one of the probe 2 or the recording medium 4 is on the cantilever, and therefore high rigidity can be achieved. This makes the system resistant to external noise. Furthermore, as the information recording/detection method, any method may be used as long as it records and detects a two-dimensionally arranged recording bit string 5 on the surface or inside of a recording medium using a three-dimensionally movable probe 2. Any method may be used, such as tunneling current (STM), atomic force (AFM), magnetic force (MFM), etc.

[Example] Hereinafter, the present invention will be explained in detail using examples.

Embodiment 1 FIG. 2 shows a configuration diagram of a memory system according to Embodiment 1. A main frame 6 is installed on the vibration isolation stage IO, and a probe plate 7 on which a group of cantilevers on which the probes 2 are provided is fixed to the upper part of the main frame 6. Further, a medium plate 8 on which a group of cantilevers on which a recording medium is provided is attached to the main frame 6 via a laminated piezoelectric body 9 for two-dimensional coarse movement. Here, the main frame 6 is approximately 1 cm
corner, probe plate 7. Media board 8. are opposed to each other with an interval of about 3 μm. FIG. 3a shows a plan view of the probe plate 7. S i (10
0) On the substrate 11, 24 x 10 probe-side cantilevers 1, a total of 240 probe-side cantilevers 1 manufactured by the process described below are provided, and a probe 2 for information detection is manufactured at the tip of each probe-side cantilever 1. has been done. Next, FIG. 3 shows a plan view of the medium plate 8. 5 mm x 5 m
240 medium-side cantilevers 3 are provided on a Si (100) substrate 1 with a thickness of 0.5 mm, and each medium-side cantilever 3 is shaped to exactly face the probe-side cantilever 1. A recording medium 4 is laminated on the upper surface. The dimensions of each cantilever 1 and 3 on the probe plate 7 and medium plate 8 are 300 μm2 in length.
The width is 50 μm.

Next, the manufacturing process of the cantilevers 1 and 3 will be described. First, on a Si (100) substrate (thickness 0.5 mm),
A 5iaN4 film was formed to a thickness of 0.15 μm using the VD method. The raw material gas used was Si H2Cρ2 :NH
, (1:9), and the substrate temperature was 800°C. Next, the Si3N4 was patterned into a desired shape by photolithography and CF4 dry etching. Subsequently, Cry films of 01 μm and Aug films of 09 μm were formed, and patterned by photolithography and wet etching. Next, AρN was deposited to a thickness of 0.3 μm by sputtering. , using Au2 as the target, A r + N
Sputtering was performed in 2 atmospheres.

Furthermore, patterning was performed by photolithography and wet etching using an etching solution for AJ2. After that, the above steps were repeated, and finally the Si substrate 11-Au/C
r-Al2N-Au/Cr-A 42 N-A u
/Cr bimorph structure was formed. Further, as a protective layer, a 0.15 μm amorphous SiN film was formed by CVD method. The steps up to this point are the same for the probe plate 7 and the medium plate 8. In the probe plate 7, after producing the W probe by vapor deposition,
Using anisotropic etching of i, the portion to which Si3N4 was not attached was removed, and the probe side cantilever 1 was fabricated. Finally, the W probe side was coated with PT to form an information detection electrode.

On the other hand, in the medium plate 8, after producing the 5iaN4 protective layer,
The medium side cantilever 3 was fabricated by the same SL anisotropic etching as the probe plate 7. Furthermore, Aρ is deposited to a thickness of 0.1 μm from the St substrate 11 side, and the recording medium 4 is deposited on top of it.
Four layers (thickness: 15 layers) of polyimide film B film were formed.

FIG. 4a shows a cross-sectional view when the probe-side cantilever 1 and the medium-side cantilever 3 produced by the above steps are opposed to each other. FIG. 4 is a sectional view taken along line AA' in FIG. 4a. In the figure, 11 is a Si substrate, 15.21, 25.31 are 5
isN4 layer, 1616°, 1g, 20. 2
0', 26. 26°.

28. 30, 30° are electrodes (Cr/A u ) for three-dimensionally driving the bimorph piezoelectric material 17.19
, 27. 29 is a piezoelectric material Al2N, 2 is a W probe, 23
32 is the information detection electrode (Pt), and 32 is the medium side base electrode (A
12), 4 is a recording medium (polyimide).

A recording bit string 5 is arranged on the recording medium 4, and by driving the probe side cantilever 1 and the medium side cantilever 3 in opposite phases, the probe 2 moves on the recording medium 4 and records and detects information. Fig. 5 shows a conceptual diagram of the drive. FIG. 6 shows the movement of the probe 2 on the recording medium 4. The movement indicated by arrow 40 is caused by moving the cantilevers 1.3 on the probe side and medium side in opposite phases, and the movement indicated by arrow 41
．． 42 is for moving the medium plate 8 with the laminated piezoelectric body 9.

In this example, the recording method applies an electric field to the recording medium 4 (polyimide film) using the base electrode 32 and the probe 2, and detects the phenomenon that the resistivity of the recording medium 4 changes (J P
309433, 309434), and a method of detecting a change in the tunnel current flowing between the base electrode 32 and the probe 2 was used for detection.

FIG. 7 shows recording medium 4 of this embodiment. A schematic diagram of controlling the distance between two probes is shown. The probe plate 7 and medium plate 8 are several mm
It has a corner area, and within that plane, the undulation from the plane was more than 5 μm, but the probe side cantilever 1 and
By applying a required voltage to the bimorph piezoelectric material of the medium-side cantilever 3, the distance between the probe 2 and the recording medium 4 could be controlled on the order of six over the entire surface of several mm square.

Moreover, by adopting this configuration, the probe 2. The relative speed of the recording medium 4 was doubled, allowing it to be driven at a lower frequency and preventing resonance of the cantilever.

Example 2 A conceptual diagram of Example 2 is shown in FIG. This is the probe side cantilever 1 manufactured by the same process as in Example 1.
and the medium side cantilever 3 are opposed in a direction perpendicular to each other. With this configuration, the relative movable range between the probe 2 and the recording medium 4 can be increased compared to the case where a cantilever of the same size is used on either the probe side or the medium side.

Example 3 When a system similar to Example 1 is manufactured, and when the voltage for driving the bimorph cantilever is kept constant, the displacement decreases as the voltage approaches the base of the medium-side cantilever 3, and the recording bits become equal. In Figure 9a, the length of both cantilevers 1.3 is β, and the distance between the tip of the medium side cantilever 3 and the probe 2 is X.
Then, the relative displacement amount Δy between the probe 2 and the recording medium 4
The result will be as shown in Figure 9. In other words, the recording bit string on the medium side cantilever 3 becomes as shown in FIG. 9C.

Here, the driving voltage V of the bimorph piezoelectric material is expressed as
If it is changed as Δy changes, Δy becomes the 10th
As shown in figure a, Δy is constant in the shaded area, and x=
If the range from O to Xo is used, the recording bit strings 5 on the medium side cantilever 3 will be equally spaced (FIG. 10b).

Example 4 Example 4 will be described using FIG. 11. In the same configuration as in Example 1, the driving electrodes of the medium-side cantilever 3 are divided into 51, 52, 53°, and 54 parts. Here, the dimensions of each electrode are the same, 20 um x 40 um. For example, the voltage applied to each electrode is set to the electrode 51.
If you set ■ for 54 and 10V for 52.53,
The relative displacement Δy between the probe 2 and the recording medium 4 is shown in Figure 10a.
Δy is constant in the shaded area. Then,
The recording bit string 5 on the medium side cantilever 3 is arranged at equal intervals (
It becomes (b) in Figure 1O.

[Effects of the Invention] As explained above, in a high-density, large-capacity recording device in which a recording medium and an information recording/detection probe face each other, the dimensions can be reduced by installing both the probe and the recording medium on a cantilever. (It is possible to achieve high rigidity, and since the relative displacement between the probe and the recording medium can be increased, the driving frequency can be lowered, resulting in a device that is resistant to external vibration noise.

Furthermore, the fact that the relative displacement is large means that the drive voltage is small for the same amount of displacement, making it possible to save power.

Furthermore, since the distance between the probe and the recording medium can be controlled over a wide range, it is possible to increase the area of the system, that is, to increase the capacity.

[Brief explanation of the drawing]

Fig. 1: Basic conceptual diagram of the present invention Fig. 2: Cross-sectional view of the system of embodiment 1 Fig. 3a...
・Probe plate plan view of Example 1 b... Medium plate plan view of Example 1 Figure 4 a... Cantilever longitudinal sectional view of Example 1
b... Transverse cross-sectional view of the cantilever of Example 1. Fig. 5... Conceptual diagram of operation of Example 1. Fig. 6... Operation diagram of Example 1. Fig. 7... Probe of Example 1. Diagram showing medium distance control FIG. 8... Conceptual diagram of Embodiment 2 FIG. 9 a... Cross-sectional view of cantilever of Embodiment 2 b.
... Relative displacement amount of the probe and the medium in the case of constant voltage driving c... Arrangement diagram of recording bits in the case of constant voltage driving Figure 10 a... Relative displacement of the probe and the medium in the case of voltage driving in Example 2 Displacement amount b... Recording bit arrangement diagram in the case of voltage drive in Example 2 FIG. 11... Drive electrode arrangement diagram in Example 3 1, probe side cantilever 2, probe 3. Medium side cantilever 4, recording medium 5. Recording bit string 6, main frame 7
．． Probe plate 8, medium plate 9. Laminated piezoelectric material 10. Vibration isolation stage 11. Si substrate 15, Si, N4 layer 16, 16', drive electrode (Cr/Au) 17, piezoelectric material (
AI2N) 18, drive electrode (Cr/A u) 19, piezoelectric material (
AI2N) 20.20', drive electrode (Cr/A u) 21
, Si3N4 layer 23, readout electrode (pt) 25, Sia N4 layer 26.26°, drive electrode (Cr/Au) 27, piezoelectric material (
AρN) 28, drive electrode (Cr/A u) 29, piezoelectric material (
AβN) 30.30', drive electrode (Cr/Au) 31
．． 5iaN4 layer 32, base electrode (Al1) 40.41,42. Probe movement 51.52,53,54. Drive electrode LnCD; Place □, -1-9.・°°・ (knee, :jo・ , , , , :, , (V) , to Figure 9 (b) Figure 9 (C)

Claims (1)

[Claims] 1. A recording device characterized in that a recording medium for recording information and a probe for information recording or detection are each provided on a drivable cantilever. playback device. 2. Install each cantilever so that the surface of the recording medium faces the probe, and control the distance between the probe and the recording medium by displacing each cantilever in that direction. A method for driving a recording/reproducing apparatus, characterized in that a recording bit string is sequentially recorded or detected by driving a cantilever. 3. The recording/reproducing apparatus according to claim 1, wherein the recording bits are produced by changing the physical state of the recording medium in a molecular scale region. 4. The recording/reproducing apparatus according to claim 3, wherein the recording bits are produced by changing the electrical characteristics of the recording medium by applying an electric field to the recording medium. 5. The recording/reproducing apparatus according to claim 1, wherein the recording bit is detected by controlling the relative displacement between the information detection probe and the recording medium on a molecular scale. 6. The recording/reproducing apparatus according to claim 5, wherein the recorded information is detected by a change in tunnel current between a conductive probe and a conductive medium or a conductive electrode below the recording medium.