CA2034297C - Information record/reproducing apparatus and information recording apparatus - Google Patents

Abstract

An information recording and reproducing apparatus is disclosed. The apparatus has a signal processing unit for signal processing for information recording on and reproduction from an information recording medium and a probe which is positioned opposed to the information recording medium. The signal processing unit is adapted to effect information recording on and reproduction from the information recording medium through the longitudinal end of the probe. The probe includes a supporting member and a rod-shaped projection of which the end is positioned opposed to the medium. The rod-shaped projection protrudes from a partial area of the supporting member.
By the apparatus, it is possible to precisely and accurately record and reproduce information regardless of the surface state of the medium.

Description

2~342i~7 1 Information Record/reproducing Apparatus and Information Recording Apparatus BACKGROUND OF THE INVENTION
Field of the Invention The present invention relates to a record/reproducing apparatus and a recording apparatus for effecting electric recording and/or reproduc-tion on a recording medium, utilizing a probe.
Related sackground Art In recent years, various memory devices are very actively developed, as the nucleus of electronic equipment such as computers, computer-related equipment, video disks, digital audio disks etc.
Though dependent on applications, the general requirements for such memory devices can be summarized as:
1) high density and large recording capacity;

2) high response speed in recording and reproduction;

3) low electric power consumption; and 4) high productivity and low cost.
Conventionally the memory devices have been dominated by semiconductor memories and magnetic memories, but, with the advent of laser technology in recent years, there has been introduced the inexpensive high-density optical memories utilizing an l organic thin film for example of organic dyes or photopolymers.
On the other hand, the recent development of the scanning -tunnel microscope c:apable of directly observing the electron structure of surfacial atoms of conductive materials [G. Binnig et al., Helvetica Physica Acta, 55, 726 (1982)] enables measurement of the real space image with a high resolving power both in the monocrystalline and in the amorphous materials.
Very wide applications are expected for said microscope because it can achieve observation with a low electric power, without damage by current to the observed specimen, and can be used for various materials even in the air.
The scanning tunnel microscope is based on the phenomenon of tunnel current generated when a metal probe electrode and a conductive material are maintained at a very small distance, in the orcler of 1 nm, with a voltage applied therebetween. Said current is very sensitive to the change in said distance. It is therefore possible to observe the surface structure in real space and to obtain various information on the total electron cloud of surfacial atoms from the amount of vertical movement of the probe, by controlling said distance, with vertical movement of the probe electrode, so as to maintain a constant tunnel current.

2~3~297 1 Also there have been proposed various methods of information recording and reproduction utilizing such scanning tunnel microscope, such as forming a record by modifying the surface state of a recording layer of a suitable recording medium with a particle beam (electron beam or ion beam), a high-energy electromagnetic wave such as X-ray or an energy beam such as visible or ultraviolet light and reading such record with the scanning tunnel microscope, or effecting the recording and the reproduction by the scanning tunnel microscope utilizing a recording layer with a memory effect in the voltage-current switching characteristic, such as a thin film of an organic compound with a ~-electron system or a charcogenide compound (as disclosed for example in the Japanese Laid-open Patent Applications 63-161552, 63-161553 and 63-204531).
Fig. 1 shows an example of the probe electrode to be employed in such record/reproducing methods.
Fig. 1 shows a state in which a probe electrode 81 is positioned close to a recording medium 82 with surface irregularities. The resolving power of such probe electrode 81 is generally higher as the radius of curvature at the pointed end becomes smaller.

The probe electrode of small radius of curvature at the pointed end, employed for the above-mentioned purposes, is conventionally produced 9 ~

1 by mechanical working or electrolytic polishing. In mechanical working, a wire-shaped material consisting of fiber-like crystal can be worked with a clock lathe to obtain a probe electrode with a radius of curvature at the pointed end in a range of 5 to 10 ~m, and die drawing can attain a radius of curvature of 10 ~m o.
smaller.
In electrolytic polishing, a straight wire material of a diameter of 1 mm or less, for forming 10 the probe electrode, is vertically held, immersed by 1 - 2 mm in electrolyte solution and intermittently given a voltage at an interval of 0.5 to 2.0 seconds under suitable agitation of the electrolyte solution.
This method can provide a radius of curvature at the 15 pointed end as small as 0.05 ~m.
Also the aforementioned field evaporation method (H. W. Fink, IBM Journal of Research and Development 30, 460 (1986)) is recently utilized for producing a probe electrode with one to several atoms 20 at the pointed end, corresponding to the theoretically smallest radius of curvature (R. Allenspach and A.
Bischof, Applied Physics Letters 54, 587 (1989)).
The probe electrode with such small radius of curvature enables recording and reproduction in the 25 atomic order, namely several Angstroms.
The probe electrode with a very small radius of curvature at -the pointed end, obtained by the 2~3~297 l above-mentioned conventional methods, can exactly record the information with an extremely high density, if the recording medium has a completely flat surface.
In practice, however, such flat recording medium is difficult to obtain, and the surface of the medium often shows significant irregularities.
On such medium, the conventional probe electrode 81 may contact or may be positioned very close to the surface of the recording medium 82 in a position other than the longitudinal end of the probe electrode, as indicated by an arrow in Fig. 1, whereby the probe electrode 81 will record the information in an erroneous position of the recording medium 82.
Consequently, the information recording with such probe electrode with result in drawbacks that the recorded information cannot be reproduced or that a recording density matching the radius curvature of the pointed end of the probe cannot be obtained. Thus the recording yield has been very poor as the surface of the recording medium has been utilized only in a very limited smooth area.
Also in case of a recording medium with tracking grooves as shown in Fig. 5, with the reduction in pitch of the grooves for elevating the recording density, the record bits become more difficult to form in recesses portions which are more resistant to destruction for example by abrasion, and - 6 - 2~2~

l have to be formed on the protrucling portions which are more apt to be destructed by abrasion.

SUMMARY OF THE INVENTION
In consideration of the foregoing, an object of the presen-t invention is to provide a probe capable of precise and accurate information recording and reproduction regardless of the surface state of the object, a method for producing such probe, and an information record/reproducing apparatus and an information recording apparatus utilizing such probe.
Other objects of the present invention will become fully apparent from the following detailed description of the embodiments of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a schematic view of a conventional microprobe;
Fig. 2 is a block diagram of an embodiment of the record/reproducing apparatus of the present invention;
Fig. 3 is a cross-sectional view of the probe employed in the record/reproducing apparatus of the present invention, Fig. 4 is a view showing the method for _ 7 ~034297 1 producing the probe shown in Fig. 3;
Fig. 5 is a perspective view showing an example of the shape of the recording medium;
Fig. 6 is a perspective view showing another embodiment of -the probe to be employed in the record/reproducing apparatus of the present invention;
F'ig. 7 is a cross-sectional view showing still another embodiment of the probe to be incorporated in the record/reproducing apparatus of the present invention; and Fig. 8 is a schematic view showing the method for producing the probe shown in Fig. 7.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
~Record/reproducing Apparatus]
~ n the following there will be described a record/reproducing apparatus utilizing a microprobe electrode enabling exact recording and reproduction of information even with a recording medium having surface irregularities.
Said record/reproducing apparatus utilizing microprobe electrode is provided with a microprobe electrode; voltage applying means for applying a voltage through said microprobe electrode to a recording medium showing an electric memory effect;
and reading means for reading the change in current flowing in said recording medium, for effecting - 8 - ~Q342~7 1 information recording and reproduction on said recording medium by scanning said recording medium with said microprobe electrode while maintaining a predetermined distance between the end of said microprobe electrode and said recording medium;
wherein said microprobe electrode has a probe shaft portion showing a variation rate of the cross sectional area thereof equal to or less than 10 ~
continuously over a length of 5 nm along the axial direction of said microprobe electrode, and said end i5 formed at the end portion of said probe shaft portion.
Said probe shaft portion of the microprobe electrode, showing the variation rate of the cross sectional area not exceeding 10 % continuously over a length of 5 nm along the axial direction of said microprobe electrode, may be formed as a cylinder or a polygonal pillar.
The diameter or maximum cross dimension of said probe shaft portion is preferably in a range from 1 nm to 1 ~m.
Also said microprobe electrode may be composed of a single crystal, or formed by crystal growth on a supporting member, or formed by crystal growth by forming a temperature gradient in the supporting member, or by crystal growth in an aperture of a resist layer covering the supporting member.

_ 9 _ ~ ~3~7 l In order to avoid eventual contact or very close positioning of said microp:robe electrode, except the end thereof, to the recording medium having surface irregularities, the cross-sectional shape of the microprobe electrode 33 is maintained identical, as shown in Fig. 3, in the end portion within the height of surface irregularities of the recording medium 32. However, even when the cross sectional shape of the microprobe electrode is not maintained completely identical, the probability of mutual contact or mutual close positioning of the probe and the recording medium, except the end of said microprobe electrode, diminishes if said cross sectional shape is maintained almost identical.
Such condition is attained by a cylinder, a polygonal pillar or a similar shape, namely a rod-shaped projection. As the radius of curvature at the end of the microprobe electrode 33 does not exceed the radius or cross section of the end portion of the microprobe electrode 33 or a half of the maximum cross dimension of said cross section, so that a reduction in the cross section of the area automatically reduces the radius of curvature, thus providing a sufficient resolving power. Consequently, the diameter or maximum cross dimension of the microprobe electrode 33 at the end thereof and in the end portion thereof to be positioned within the height of the surface 2~42g~

1 irregularities of the recording medium 32 at the recording or reproduction is desirably from 1 nm to 1 ~m, and more desirably 1 to 10 nm, though it is dependent on the level of surface irregularities of the recording medium 32.
Such microprobe electrode of the above-mentioned -form may be realized by crystal growth on a supporting ~ember. In such case, the growth of a very limited number of crystals only in a desired position of the supporting member is preferable to unlimited crystal growth on the supporting member, in consideration of the subsequent operations. The limitation in the area of crystal growth may be principally achieved in one of following two methods:
i) forming a temperature gradient in the supporting member for the microprobe electrode in such a manner that the crystal growing conditions are realized only in a predetermined area; and ii) covering the surface with a suitable resist material, excluding the desired crystal growing area.
[Preferred Embodiments]
In the following there will be explained certain embodiments of the present invention, with reference to the attached drawings.
[Embodiment 1]
Fig. 2 is a block diagram of an embodiment of - 11- 2~C~2~7 1 the record/reproducing apparatus employing the microprobe electrode of the present invention.
Said record/reproducing apparatus effects information recording on a recording medium 32 by applying a writing voltage across a recording layer 37 which is initially in a high-resistance "off" state thereby selectively forming a low-resistance "on"
area, and information reproduction by applying a voltage smaller than a switching threshold voltage and detecting the tunnel current from a probe 31.
In said apparatus, the recording medium 32 is composed of a substrate 35, a substrate electrode 36 and a recording layer 37, and is placed and fixed on a table 38.
A coarse movement mechanism 19 is provided for coarse control of the vertical position of the recording medium 32, in order to maintain a predetermined distance to a microprobe electrode 33 fixed on a supporting member 34 of the probe 31, and is controlled by a coarse movement drive circuit 40.
Under said coarse movement drive mechanism 39, there is provided an X-Y stage 41 for moving the recording medium in X- and Y-directions.
A pulse power source 42 serves to apply voltages for recording or erasing (by recording of "0"
information) between the microprobe electrode 33 and the substrate electrode 36. A probe current amplifier - 12 - 2~3~9~

l 43 amplifies the probe current between the microprobe electrode 33 and the recording medium 32 under the application of a predetermined voltage, for supply to a servo circuit 44, which controls the movement of a vernier control mechanism 45 in the vertical direction, in such a manner that the current from the probe current amplifier 43 is maintained at a desired level. Means for applying said predetermined voltage is omitted in the drawing. The movement of the vernier control mechanism 45 in the X- and Y-directions is controlled by an X-Y scanning drive circuit 46.
The above-mentioned circuits are collectively controlled by a microcomputer 47, of which process information is displayed on a display unit 48.
In the following there will be explained the probe 31 employed in the present record/reproducing apparatus.
In the probe 31, as shown in Fig. 3, the microprobe electrode 33 was formed by growing a whisker, which an acicular single crystal, on the supporting member 34, and its producing method will be explained in the following with reference to Fig.
4.
At first a tungsten wire of l mm~ was formed as a supporting member 34 with a projection 34a by electrolytic polishing, and said supporting member 34 l with said projection 34a was inserted into a coil-shaped heater 120. Copper, as the whisker forming material 122, is positioned inside and in contact with a tungsten filament 121 positioned above said projection 34a of the supporting member 34.
The supporting member 34 and the whisker forming material 122 were placed in high vacuum (about mmHg) and the supporting member 34 was heated by the heater 120.
The temperature of the supporting member 34 was about 800~C in the vicinity of the heater 120 while about 600~C in the vicinity of the projection 34a, so that a temperature gradient was generated in the supporting member 34.
Subsequently the tungsten filament 121 positioned above the supporting member 34 was heated to about 1,000~C to evaporate copper, which was the whisker forming material 122 positioned in contact with said tungsten filament 121, for about 10 minutes, whereby whiskers 33 were grown in the vicinity of the end of the projection 34a which was lower in temperature than in other areas. The whisker growth was conducted on several supporting members under same conditions, and a supporting member 34 having only one whisker grown upwards similar to the microprobe electrode 33 shown in FigO 11 was selected as the probe 31. Said whisker was about 5 nm in thickness - 14 - 2~3429~

l and 10 ~m in length, and was formed as a cylinder or a polygonal pillar.
In the present embodiment the microprobe electrode 33 was made of a whisker which an acicular single crystal, in order to enable information recording even in the recessed portion of a recording medium havi.ng surface irregularities, and said whisker has following features:
(a) whisker is a needle-shaped single crystal which is extremely thin and uniform in thickness;
(b) diameter of the whisker can be made as small as 5 - 20 nm under suitable crystallizing conditions, so that the radius of curvature at the end can be made equal to a half of the above-mentioned figure;
(c) whisker can be developed from various metals and insulating materials, including metals frequently utilizes as the electrode, such as Au, Pt or W;
(d) whisker, being single crystal with much fewer lattice defects than in ordinary single crystals, has an extremely high mechanical strength despite of an oblong form; and (e) there is not required any particular means apt to contaminate the probe surface, such as polishing.
In order to evaluate the performance of the - 15 - 203~97 l above-explained record/reproducing apparatus, there were employed recording medium 32 with a groove structure in the recording layer 37 as shown in Fig. 5 with following dimensions;
(1) wid-th of recess = 10 nm;
depth of recess = 10 n~;
width of protrusion = 10 nm;
(2) width of recess = 20 nm;
depth of recess = lQ nm;
width of protrusion = 10 nm;
(3) width of recess = 50 nm;
depth of recess = 20 nm;
width of protrusion - 20 nm;
(4) width of recess = 100 nm;
depth of recess = 30 nm;
width of protrusion = 50 nm.
On each of the four recording media mentioned above, recording was conducted by moving the microprobe electrode 33 of the probe 31 along the 20 recessed portion by means of the X-Y stage 41 and the vernier control mechanism 45 and instantaneously applying a recording pulse voltage to the recording layer 37 while maintaining a constant distance (in the order of a nanometer) between said layer 37 and the 25 end of the microprobe electrode 33 by means of the servo circuit 44 and the vernier control mechanism 15.
Subsequently thus obtained record was re-scanned with 2~3~297 l the microprobe electrode 33, and the control signal of the servo circuit 44 was obtained as the reproduced information signal. In this manner it was evaluated whether the information could be correctly reproduced.
Such method of information recording and reproduction is already well known, for example as described in the Japanese Laid-~pen Patent Publication No. 63-161552.
The obtained results indicate that the record/reproducing apparatus employing the microprobe electrode 33 as explained above is capable, in any of the four recording media mentioned above, of correctly recording information in the recess portion and of reproducing the information recorded in the recessed portion.
The whisker of the microprobe electrode 33 employed in this fourth embodiment was broken at the end portion by an accidental collision with the specimen, but the whisker was regenerated from the remaining part thereof by the application of the aforementioned whisker growing operation to the supporting member 34 and could be used again as the microprobe electrode.
The diameter of the grown whisker may not be equal to the desired value. However, if said diameter is larger than the desired value, it can be reduced to the desired value, utilizing the feature that the whisker is a single crystal, by placing the whisker in ~'.3~7 1 a condition where the lateral crystal face melts or evaporates faster than the crystal face at the end.
Also the end of the whisker is not smooth, but there may be employed a smoothing method such as immersing the end portion of the whisker in an electrolyte solution for a very short period or heating said end portion.
The use of a whisker, which is an acicular single crystal, allows to obtain an extremely thin microprobe electrode with uniform thickness, thereby enabling correct recording and reproduction even on a recording medium with surface irregularities and thus improving the reliability of the record/reproducing apparatus.
Besides the whisker can extent the service life of the microprobe electrode because of its high mechanism strength, and is economical because it can be regenerated even if it is accidentally damaged.
Furthermore the manufacture of the microprobe 2~ electrode is made easier as the whisker can be grown only in a desired area of the supporting member.
[Embodiment 2]
In the following there will be explained a second embodiment of the present invention, with reference to Fig. 6.
The supporting member 54 of the probe 51 employed in this embodiment is composed of a silver 203~29~

1 single crystal, of which upper face 52 is composed of two (111) planes and two (100) planes.
Said supporting member 54 was subjected to a whisker growing operation as in the first embodiment, except that the evaporated whisker forming material 122 was silver and that the tungsten filament 121 was heated to about 800~C.
As the result, at the pointed end, surrounded by said two (111) planes and two (100) planes, of the supporting member 54, there was epitaxially grown a silver whisker of a growing orientation (110), with a thickness of about 10 nm and a length of 15 ~m.
The probe 51 with thus grown whisker was employed as the probe 31 of the record/reproducing apparatus shown in Fig. 2, and the information recording and reproduction were conducted, as in the first embodiment, on four recording media (1) - (4) with different shapes of the grooves.

The probe 51 of the present embodiment was capable of exactly recording the information in the recessed portion and reproducing the recorded information therefrom in the recording media (2), (3) and (4), but was incapable of exact information recording in the recessed portion of the recording medium (1) and was incapable of reproducing the information correctly recorded in the recessed portion of the recording medium (1) with the probe 31 of the 2~3~97 1 first embodiment.
The probe 51 of the present embodiment could be regenerated successfully as in the first embodiment.
[Embodiment 3]
In the following there will be explained a third embodiment of the present invention, with reference to Fig. 7 showing a probe 61.
The probe 61 of the present embodiment is composed of a Si substrate 64 and a microprobe electrode 63 consisting of a whisker having an Au-Si alloy portion 65 at the end. The surface of the Si substrate 64 and of the microprobe electrode 63 is given electroconductivity by an Au-Pd layer 62.

In this embodiment, for growing the whisker constituting the microprobe electrode 63, there is utilized a whisker growing method called VLS method (R. S. Wagner and W. C. Ellis; Applied Physics Letters 4 (1986) 89).

The principle of the VLS method is to make a liquid droplet of fused Au-Si alloy on a Si substrate and to place them in SiC14 atmosphere, whereby Si in gaseous phase is dissolved in the Au-Si liquid droplet to create a supersaturated state and Si is crystallized under said liquid droplet, thus causing whisker growth lifting the liquid droplet.
The probe preparation utilizing said VLS

203~g'7 l method will be explained in the following, with reference to Fig. 8.
A monocrystalline silicon substrate 64 was used as the supporting member and was coated, on the (111) plane thereof, with a resist material to form a resist layer 66. Then holes 67 of about 1 ~m~ were formed, with a pitch of ~ mm, in said resist layer 66 by means of an electron beam and a very small amount of Au was deposited by evaporation from above.
Subsequently the resist layer 66 was stripped off from the Si substrate 64. The amount of deposited Au was measured as 0.2 nm when measured with a film thickness gauge utilizing a quartz crystal oscillator. However the evaporated Au did not form a uniform film of such thickness, but in fact formed particles 68 of an average diameter of 20 nm, and each hole 67 of the resist layer 66 contained one to several particles.
Then the Si substrate was cut into squares of 5 x 5 mm each, and a Si substrate 64 containing only one Au particle 68 of about 10 nm in diameter was selected by the observation under a scanning electron microscope of a high resolving power. Said Si substrate 64 was heated to 1000~C in an oven to fuse the Au particle 68, and SiCl4-H2 gaseous mixture was introduced at about 400~C. Thus, after 3 days, there was grown a whisker of an average thickness of about 10 nm, having the aforementioned Au-Si alloy portion 1 65 at the end. Finally the surface of the Si substrate 64 having said grown whisker was given electroconductivity by forming an Au-Pd layer 62 of as thickness of 5 nm by sputtering. The probe 61 was thus completed.
In the present embodiment, a non-conductive whisker was coated with Au-Pd by sputtering for obtaining electroconductivity, but Au or Pt may also be employed for the same purpose, and the method of coating is not limited to sputtering but can be plating or evaporation.
The probe 61 prepared as explained above was employed as the probe of the record/reproducing apparatus shown in Fig. 2, in the same manner as in the first embodiment, and recording and reproduction were conducted on four recording media with surface shapes (1) - (4) in the same manner as in the first embodiment.

As the result, the record/reproducing apparatus employing the probe 61 of the present embodiment was capable of correct information recording in the recessed portion of the recording media (2), (3) and (4), and of correct information reproduction from the information recording in said recessed portion, but was incapable of correct information recording in the recessed portion of the medium (1) and of reproduction of the information l correctly recorded in said recessed portion by the probe 1 of the first embodiment.
Reference Example For the purpose of comparison with the embodiments 4, 5 and 6, a tungsten wire of 1 mm~ was formed as shown in Fig. 1 by electrolytic polishing, incorporated as the probe 31 of the record/reproducing apparatus shown in Fig. 2, and was subjected to the evaluation of recording and reproduction on the recording media (1) - (4) in the same manner as in the first embodiment.
As the result, the record/reproducing apparatus employing the probe electrode of the present reference example was capable of exact information lS recording in the recessed portion, and of exact reproduction of information therefrom, on the recording medium (4), but was incapable of exact information recording in the recessed portion and of reproduction of the information correctly recorded in said recessed portion with the apparatus of the first embodiment, in case of the recording media (1), (2) and (3), The results of recording and reproduction in the foregoing embodiments 1, 2 and 3, and in the reference example are summarized in Table 1.

- 23 - 203~29~

1 Table 1 Recording medium (1) (2) (3) (4) Embodiment 1 + + + +
Embodiment 2 - + + +
Embodiment 3 - + + +
Reference Example - - - +
wherein: "+": case where exact recording and reproduction were possible;
"-": case where exact recording or reproduction was not possible;

(1) width of recess = 10 nm;
depth of recess = 10 nm;
width of protrusion = 10 nm;
(2) width of recess = 20 nm;
depth of recess = 10 nm;
width of protrusion = 10 nm;
(3) width of recess = S0 nm;
depth of recess = 20 nm;
width of protrusion = 20 nm;
(4) width of recess = 100 nm;
depth of recess = 30 nm;
width of protrusion = 50 nm.
As explained in the foregoing 1st to 3rd embodiments, the end of the probe is continued by a probe shaft portion with a low variation rate in the cross sectional area, so that the cross section of the 203~29~

1 microprobe electrode remains substantially same within the height of surface irregularities of the recording medium. Conse~uently the microprobe electrode does not contact nor is positioned very close to the S recording medium except in the end of said electrode, and exact information recording and reproduction are enabled even on a recording medium involving surface irregularities.

Claims (66)

1. A probe for effecting, at a longitudinal end thereof, at least one of information reading from an object and information input to an object, comprising:
a supporting member; and a rod-shaped projection of which the end is positioned opposed to said object for at least one of information reading therefrom and information input thereto, wherein said rod-shaped projection protrudes from a partial area of said supporting member, said rod-shaped projection has a variation rate of the cross-sectional area not exceeding 10% continuously over a longitudinal length of at least 5 nm, and the maximum cross-sectional dimension or diameter in the end portion of said rod-shaped projection, positioned within the height of surface irregularities of said object, is within a range from 1 nm to 1 µm.

2. A probe according to claim 1, wherein said rod-shaped projection at least includes a part composed of a single crystal whisker.

3. An apparatus for at least one of information reading from an object and information input to an object, comprising:
a signal processing unit for signal processing for at least one of information reading from said object and information input to said object; and a probe positioned opposed to said object, wherein said signal processing unit is adapted to effect at least one of information reading from said object and information input to said object through a longitudinal end of said probe, said probe includes a supporting member and a rod-shaped projection of which the end is positioned opposed to said object for at least one of information reading therefrom and information input thereto, said rod-shaped projection protrudes from a partial area of said support member, said rod-shaped projection has a variation rate of the cross-sectional area not exceeding 10% continuously over a longitudinal length of at least 5 nm and the maximum cross-sectional dimension or diameter in the end portion of said rod-shaped projection, positioned within the height of surface irregularities of said object, is within a range from 1 nm to 1 µm.

4. An apparatus according to claim 3, wherein said signal processing unit is adapted to measure the surface information of the object based on the information read through said probe.

5. An apparatus according to claim 3, wherein said signal processing unit is adapted to effect at least one of information recording to and information reproduction from an information recording medium, serving as said object, through said probe.

6. An apparatus according to claim 5, wherein said signal processing unit is adapted to effect information recording by applying a voltage between said probe and said information recording medium thereby inducing an electric memory effect therein.

7. An apparatus according to claim 6, wherein said probe is adapted to effect the recording while moving along a recessed groove formed on said information recording medium.

8. An apparatus according to claim 5, wherein said signal processing unit is adapted to effect information reproduction by applying a voltage between said probe and said information recording medium and detecting the current flowing therebetween.

9. An apparatus according to claim 8, wherein said probe is adapted to read data recorded in a recessed groove formed on said information recording medium.

10. An apparatus according to claim 3, wherein said rod-shaped projection at least includes a part composed of a monocrystalline whisker.

11. An apparatus according to claim 10, wherein said monocrystalline whisker is composed of a metal.

12. An apparatus according to claim 10, wherein said monocrystalline whisker is composed of a non-conductive material, and is coated with a conductive material.

13. A probe for effecting at least one of information reading from an object and information input to an object by applying a voltage between said probe and said object, comprising:
a supporting member; and a rod-shaped projection of which the end is positioned opposed to said object for at least one of information reading therefrom and information input thereto;

wherein said rod-shaped projection protrudes from a partial area of said supporting member, said rod-shaped projection has a variation rate of the cross-sectional area not exceeding 10% continuously over a longitudinal length of at least 5 nm and the maximum cross-sectional dimension or diameter in the end portion of said rod-shaped projection, positioned within the height of surface irregularities of said object, is within a range from 1 nm to 1 µm.

14. A probe according to claim 13, wherein said rod-shaped projection at least includes a part composed of a monocrystalline whisker.

15. An apparatus for at least one of information reading from an object and information input into an object, comprising:
a signal processing unit for signal processing for at least one of information reading from said object and information input to said object; and a probe positioned opposed to said object;
wherein said signal processing unit is adapted to effect the at least one of information reading from said object and information input to said object by applying a voltage between said probe and said object, said probe includes a supporting member and a rod-shaped projection of which the end is positioned opposed to said object for at least one of information reading from and information input thereto, said rod-shaped projection protrudes from a partial area of said supporting member, said rod-shaped projection has a variation rate of the cross sectional area not exceeding 10% continuously over a longer length of at least 5 nm and the maximum cross-sectional dimension or diameter in the end portion of said rod-shaped projection, positioned within the height of surface irregularities of said object, is within a range from 1 nm to 1 µm.

16. An apparatus according to claim 15, wherein said signal processing unit is adapted to measure surface information of the object based on the information read through said probe.

17. An apparatus according to claim 15, wherein said signal processing unit is adapted to effect at least one of information recording to and information reproduction from an information recording medium, serving as said object, through said probe.

18. An apparatus according to claim 17, wherein said signal processing unit is adapted to effect information recording by applying a voltage between said probe and said information recording medium thereby inducing an electric memory effect therein.

19. An apparatus according to claim 18, wherein said probe is adapted to effect the recording while moving along a recessed groove formed on said information recording medium.

20. An apparatus according to claim 17, wherein said signal processing unit is adapted to effect information reproduction by applying a voltage between said probe and said information recording medium and detecting the current flowing therebetween.

21. An apparatus according to claim 20, wherein said probe is adapted to read data recorded in a recessed groove formed on said information recording medium.

22. An apparatus according to claim 15, wherein said rod-shaped projection at least includes a part composed of a monocrystalline whisker.

23. An apparatus according to claim 22, wherein said monocrystalline whisker is composed of a metal.

24. An apparatus according to claim 22, wherein said monocrystalline whisker is composed of a non-conductive material, and is coated with a conductive material.

25. A probe positioned close to an object for at least one of information reading therefrom and information input thereto, comprising:
a supporting member; and a rod-shaped projection of which the end is positioned opposed to said object for at least one of information reading therefrom and/or information input thereto, wherein said rod-shaped projection protrudes from a partial area of said supporting member, said rod-shaped projection has a variation rate of the cross-sectional area not exceeding 10% continuously over a longitudinal length of at least 5 nm and the maximum cross-sectional dimension or diameter in the end portion of said rod-shaped projection positioned within the height of surface irregularities of said object, is within a range from 1 nm to 1 µm.

26. A probe according to claim 25, wherein said rod-shaped projection at least includes a part composed of a monocrystalline whisker.

27. An apparatus for at least one of information reading from an object and information input into an object, comprising:
a signal processing unit for signal processing for at least one of information reading from said object and information input to said object; and a probe positioned opposed to said object;
wherein said signal processing unit is adapted to effect at least one of information reading from said object and information input to said object through said probe in a state thereof positioned close to said object, said probe includes a supporting member and a rod-shaped projection of which the end is positioned opposed to said object for at least one of information reading therefrom and information input thereto, said rod-shaped projection protrudes from a partial area of said supporting member, said rod-shaped projection has a variation rate of the cross-sectional area not exceeding 10% continuously over a longitudinal length of at least 5 nm and the maximum cross-sectional dimension or diameter in the end portion of said rod-shaped projection, positioned within the height of surface irregularities of said object is within a range from 1 nm to 1 µm.

28. An apparatus according to claim 27, wherein said signal processing unit is adapted to measure surface information of the object based on the information read through said probe.

29. An apparatus according to claim 27, wherein said signal processing unit is adapted to effect at least one of information reading to and information reproduction from an information recording medium, serving as said object, through said probe.

30. An apparatus according to claim 29, wherein said signal processing unit is adapted to effect information recording by applying a voltage between said probe and said information recording medium thereby including an electric memory effect therein.

31. An apparatus according to claim 30, wherein said probe is adapted to effect the recording while moving along a recessed groove formed on said information recording medium.

32. An apparatus according to claim 29, wherein said signal processing unit is adapted to effect information reproduction by applying a voltage between said probe and said information recording medium and detecting the current flowing therebetween.

33. An apparatus according to claim 32, wherein said probe is adapted to read data recorded in a recessed groove formed on said information recording medium.

34. An apparatus according to claim 27, wherein said rod-shaped projection at least includes a part composed of a monocrystalline whisker.

35. An apparatus according to claim 34, wherein said monocrystalline whisker is composed of a metal.

36. An apparatus according to claim 34, wherein said monocrystalline whisker is composed of a non-conductive material, and is coated with a conductive material.

37. A probe for effecting, at a longitudinal end thereof, at least one of information reading from an object and information input to an object, comprising:

a supporting member; and a rod-shaped projection of which the end is positioned opposed to said object for at least one of information reading therefrom and information input thereto, wherein said rod-shaped projection protrudes from a partial area of said supporting member, and wherein said rod-shaped projection at least includes a part composed of a single crystal whisker.

38. An apparatus for at least one of information reading from an object and information input to an object, comprising:
a signal processing unit for signal processing for at least one of information reading from said object and information input to said object; and a probe positioned opposed to said object, wherein said signal processing unit is adapted to effect at least one of information reading from said object and information input to said object through a longitudinal end of said probe, said probe includes a supporting member, and a rod-shaped projection of which the end is positioned opposed to said object for at least one of information reading therefrom and information input thereto, said rod-shaped projection protrudes from a partial area of said support member and said rod-shaped projection at least includes a part composed of a monocrystalline whisker.

39. An apparatus according to claim 38, wherein said signal processing unit is adapted to measure the surface information of the object based on the information read through said probe.

40. An apparatus according to claim 38, wherein said signal processing unit is adapted to effect at least one of information recording to and information reproduction from an information recording medium, serving as said object, through said probe.

41. An apparatus according to claim 40, wherein said signal processing unit is adapted to effect information recording by applying a voltage between said probe and said information recording medium thereby inducing an electric memory effect therein.

42. An apparatus according to claim 41, wherein said probe is adapted to effect the recording while moving along a recessed groove formed on said information recording medium.

43. An apparatus according to claim 40, wherein said signal processing unit is adapted to effect information reproduction by applying a voltage between said probe and said information recording medium and detecting the current flowing therebetween.

44. An apparatus according to claim 43, wherein said probe is adapted to read data recorded in a recessed groove formed on said information recording medium.

45. An apparatus according to claim 38, wherein said monocrystalline whisker is composed of a metal.

46. An apparatus according to claim 38, wherein said monocrystalline whisker is composed of a non-conductive material, and is coated with a conductive material.

47. A probe for effecting at least one of information reading from an object and information input to an object by applying a voltage between said probe and said object, comprising:
a supporting member; and a rod-shaped projection of which an end is positioned opposed to said object for at least one of information reading therefrom and information input thereto, wherein said rod-shaped projection protrudes from a partial area of said supporting member and said rod-shape projection at least includes a part composed of a monocrystalline whisker.

48. An apparatus for at least one of information reading from an object and information input into an object, comprising:
a signal processing unit for signal processing for at least one of information reading from said object and information input to said object; and a probe positioned opposed to said object;
wherein said signal processing unit is adapted to effect the at least one of information reading from said object and information input to said object by applying a voltage between said probe and said object, said probe includes a supporting member and a rod-shaped projection of which the end is positioned opposed to said object for at least one of information reading therefrom and information input thereto, said rod-shaped projection protrudes from a partial area of said supporting member, and said rod-shaped projection at least includes a part composed of a monocrystalline whisker.

49. An apparatus according to claim 48, wherein said signal processing unit is adapted to measure surface information of the object based on the information read through said probe.

50. An apparatus according to claim 48, wherein said signal processing unit is adapted to effect at least one of information recording to and information reproduction from an information recording medium, serving as said object, through said probe.

51. An apparatus according to claim 50, wherein said signal processing unit is adapted to effect information recording by applying a voltage between said probe and said information recording medium thereby inducing an electric memory effect therein.

52. An apparatus according to claim 51, wherein said probe is adapted to effect the recording while moving along a recessed groove formed on said information recording medium.

53. An apparatus according to claim 50, wherein said signal processing unit is adapted to effect information reproduction by applying a voltage between said probe and said information recording medium and detecting the current flowing therebetween.

54. An apparatus according to claim 53, wherein said probe is adapted to read data recorded in a recessed groove formed on said information recording medium.

55. An apparatus according to claim 48, wherein said monocrystalline whisker is composed of a metal.

56. An apparatus according to claim 48, wherein said monocrystalline whisker is composed of a non-conductive material, and is coated with a conductive material.

57. A probe positioned close to an object for at least one of information reading therefrom and information input thereto, comprising:
a supporting member; and a rod-shaped projection of which an end is positioned opposed to said object for at least one of information reading therefrom and information inputting thereto, wherein said rod-shaped projection protrudes from a partial area of said supporting member and said rod-shaped projection at least includes a part composed of a monocrystalline whisker.

58. An apparatus for at least one of information reading from an object and information input into an object, comprising:
a signal processing unit for signal processing for at least one of information reading from said object and information input to said object; and a probe positioned opposed to said object;
wherein said signal processing unit is adapted to effect at least one of information reading from said object and information input to said object through said probe in a state thereof positioned close to said object, said probe includes a supporting member and a rod-shaped projection of which the end is positioned opposed to said object for at least one of information reading therefrom and information input thereto, said rod-shaped projection protrudes from a partial area of said supporting member, and said rod-shaped projection at least includes a part composed of a monocrystalline whisker.

59. An apparatus according to claim 58, wherein said signal processing unit is adapted to measure surface information of the object based on the information read through said probe.

60. An apparatus according to claim 58, wherein said signal processing unit is adapted to effect at least one of information reading to and information reproduction from an information recording medium, serving as said object, through said probe.

61. An apparatus according to claim 60, wherein said signal processing unit is adapted to effect information recording by applying a voltage between said probe and said information recording medium thereby including an electric memory effect therein.

62. An apparatus according to claim 61, wherein said probe is adapted to effect the recording while moving along a recessed groove formed on said information recording medium.

63. An apparatus according to claim 60, wherein said signal processing unit is adapted to effect the information reproduction by applying a voltage between said probe and said information recording medium and detecting the current flowing therebetween.

64. An apparatus according to claim 63, wherein said probe is adapted to read data recorded in a recessed groove formed on said information recording medium.

65. An apparatus according to claim 58, wherein said monocrystalline whisker is composed of a metal.

66. An apparatus according to claim 58, wherein said monocrystalline whisker is composed of a non-conductive material, and is coated with a conductive material.