JP3118676B2 - Method of manufacturing probe unit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art In recent years, a scanning tunneling microscope (hereinafter referred to as ST) capable of directly observing the electronic structure of surface atoms of a conductor.
M) (G. Binnig et a).
l. Phys. Rev .. Lett. 49 (1982)
57) It has become possible to measure a real space image with a remarkably high resolution (below nanometers) irrespective of single crystal or non-crystal.

[0003] Such an STM is a metal probe.
When a voltage is applied between the conductive material and the conductive material and the distance is reduced to about 1 nm, a tunnel current flows during that time. Since this current is very sensitive to the change in distance between them and changes exponentially, observe the surface structure in real space with atomic-order resolution by scanning the probe to keep the tunnel current constant. Can be.

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

Conventionally, a semiconductor manufacturing process technique has been used as a technique for forming a probe, and a processing technique for forming a fine structure on a single substrate (KE Peterson, "Silic").
onas a Mechanical Materialia
l ", Proceedings of the IEEE
E, vol 70, P420, 1982) has been proposed in JP-A-61-206148. This is a tongue of a cantilever (cantilever) structure in which a single spring is used as a substrate, a parallel spring that can finely move in a direction parallel to the substrate surface (XY directions) is formed by microfabrication, and a probe is formed on its movable part. A portion is provided, and an electric field is applied between the tongue portion and the bottom portion so as to be displaced in a direction perpendicular to the substrate surface (Z direction) by electrostatic force. Further, Japanese Patent Application Laid-Open No. Sho 62-281138 describes a storage device provided with a converter array in which tongue-shaped portions are arranged in multiples, similar to that disclosed in Japanese Patent Application Laid-Open No. Sho 61-206148. .

[0006]

However, the conventional cantilever probe has the following problems.

In manufacturing a cantilever, a single-crystal silicon is grown thick on a silicon substrate, so that the manufacturing cost is high. Further, since the silicon substrate is processed by anisotropic etching, the processing is time-consuming and productivity is low.

[0008] Since some etching solutions contain alkali ions, there is a problem in that when the driving circuit (IC or the like) is integrally formed, the etching solution is contaminated and the characteristics are deteriorated.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a method of manufacturing a probe unit in which the productivity and reliability of the probe unit are improved and the manufacturing cost is reduced in view of the above-mentioned problems of the prior art.

[0010]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention provides an electrostatic displacement element having a beam-like flexible portion formed on a substrate and a free portion of the flexible portion. In a method for manufacturing a probe unit including a probe provided on an end side, a first step of forming a lower electrode and an extraction electrode on a substrate by film formation and patterning is performed so as to straddle the entire lower electrode and the extraction electrode. A second step of forming a projection of the conductor by film and patterning; a third step of forming a flexible section by pattern electroplating using a resist so as to straddle the projection and the extraction electrode; A method of manufacturing a probe unit, comprising: a fourth step of forming a probe; and a fifth step of removing the protrusion.

Here, the beam-shaped flexible portion refers to a beam structure having one end fixed to one end of the flexible portion on a substrate, that is, a cantilever structure. At this time, the shape of the cantilever is arbitrary.

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

FIG. 1 is a sectional view showing a method of manufacturing a probe unit according to the present invention. In FIG. 1A, first, a substrate 1
Prepare As the substrate 1, a material such as a semiconductor, a metal, a glass, and a ceramic can be used. Subsequently, the lower electrode 2 and the extraction electrode 3 are formed on the substrate.
The extraction electrode 3 is preferably made of a material that does not easily generate surface oxides, such as a metal such as Ni, because it also serves as a plating electrode in a later step.

Next, as shown in FIG. 1B, a projection 4 of the conductor is formed so as to straddle the lower electrode 2 and the extraction electrode 3. Since the convex portion 4 according to the present invention is used as a plating electrode and a sacrificial layer to be removed in a later step, it is sufficient that the convex portion 4 can be plated with a material that can be selectively etched with the flexible portion 7 described later during etching.

Next, as shown in FIG. 1C, the flexible portion pattern 6 is exposed on the protrusion 4 and the extraction electrode 3 by using a photoresist 5 as shown in FIG. continue,
A flexible film 7 is formed by growing a plating film in the flexible pattern 6 by electroplating. Here, it is preferable to use electroplating as the method for forming the flexible portion 7 because a beam-shaped flexible portion is formed in a later step, so that a film having a small stress is preferred. This is because a high-speed growth of 1 μm / min or more is possible by electroplating.

Next, as shown in FIG. 1D, a probe 8 is formed on a side which is to be a free end of the flexible portion 7 in a later step. Here, as a method of forming the probe 8, a conventionally known method, for example, an etching method, a lift-off method, a method of bonding small pieces, or the like can be used. Subsequently, a probe unit having a beam-shaped flexible portion can be formed by removing the convex portion 4 by etching. When such a probe unit is used, a voltage is applied to the lower electrode 2 and the flexible portion 7 to deflect the beam-shaped flexible portion in a direction perpendicular to the substrate surface (Z direction), thereby displacing the probe position in the Z direction. Can be done.

The lower electrode 2, the extraction electrode 3, the projection 4
As a method of forming a thin film, a conventionally known technique, for example, a thin film manufacturing technique such as a vacuum deposition method or a sputtering method generally used in the semiconductor industry, a chemical vapor deposition method, a photolithographic technique, and an etching technique can be applied. The manufacturing method does not limit the present invention.

According to the present invention, a flexible portion is formed by pattern electroplating using a resist so as to straddle a convex portion formed on a substrate. Thereafter, the beam-shaped flexible portion is formed by removing the convex portion, so that the manufacturing cost can be reduced.

In the present invention, high-speed etching is possible by selecting the material of the projection. For example,
If Ag is used for the projections 4, a ceric ammonium nitrate-based etchant can be used. In this case, high-speed etching of 1000 ° / sec or more can be performed, and productivity can be improved. Further, since processing can be performed without using an alkaline etching solution, contamination to IC can be reduced.

[0020]

The present invention will be described below in detail with reference to examples.

Embodiment 1 This embodiment will be described with reference to FIG. First, a silicon wafer on which a thermal oxide film is formed at 5000 ° is prepared as a substrate 1. Subsequently, Ni was deposited on the substrate 1 by a vacuum evaporation method at 2000 ° and a pattern was formed by photolithography and etching to form a lower electrode 2 and an extraction electrode 3 (see FIG. 1A).

Next, silver is deposited on the substrate 1 by vacuum evaporation.
A film having a thickness of μm was formed, and a pattern was formed by photolithography and etching to form a convex portion 4 (see FIG. 1B).

Next, a flexible portion 7 was formed on the protrusion 4 and the extraction electrode 3 by pattern electroplating using a photoresist. The size of the flexible portion 7 on the convex portion 4 is 50 width.
μm and length 400 μm. At this time, Ni having a thickness of 2 μm was used for the flexible portion 7 (see FIG. 1C). At this time, the Ni electroplating was performed at a temperature of 50 ° C. using a Watt bath.
The plating was performed under the conditions of a current density of 0.09 A / cm ² and a plating time of 2 minutes. The internal stress of the plating film was 9.8.
× 10 ⁸ dyn / cm ² .

Next, a probe 8 was formed on the side to be a free end of the flexible portion 7 by vapor deposition and a lift-off method. At this time, Au was used for the probe 8. Then, AZ4620
After protecting the probe 8 and the flexible portion 7 by photolithography using (Hoechst), the convex portion 4 was over-etched using a phosphoric acid-based aqueous solution to remove the convex portion 4 (FIG. d)). At this time, the time required for the etching was 10 minutes. The Ni and thermal oxide films were exposed to the etchant, but were not etched.

Subsequently, the photoresist was removed using acetone to obtain a probe unit having a beam-shaped flexible portion having a width of 50 μm and a length of 400 μm. When the displacement of the probe unit manufactured as described above was measured, it was found that the displacement was 0.25 μm / Z in the Z direction (the vertical direction in FIG. 1).
It was found that the displacement was at v.

Example 2 In this example, a probe unit was produced in the same manner as in Example 1 except that the flexible portion 7 was changed to Au and the etching solution for the convex portion 4 was changed to nitric acid.

At this time, the Au and the thermal oxide film were exposed to the etching solution, but were not etched. The internal stress of the Au plating film is 5 × 10 ⁸ dyn / cm ^2.
Met. When the displacement amount of the probe unit manufactured as described above was measured, the Z direction (the vertical direction in FIG. 1) was obtained.
Was found to be displaced at 0.62 μm / v.

[0028]

According to the present invention, there is provided a method of manufacturing a probe unit which does not require single crystal silicon growth and processing by anisotropic etching of a silicon substrate, thereby improving productivity and further reducing manufacturing cost. it can.

[Brief description of the drawings]

FIG. 1 is a sectional view showing main steps of a method for manufacturing a probe unit according to the present invention.

FIG. 2 is a plan view showing a flexible portion pattern area.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Lower electrode 3 Extraction electrode 4 Convex part 5 Photoresist 6 Flexible part pattern 7 Flexible part 8 Probe

────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor: Yu Nakayama 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 41/08 G01B 7/34 G11B 9/00 G01N 37/00

Claims (1)

(57) [Claims] In a method of manufacturing a probe unit including an electrostatic displacement element having a beam-shaped flexible portion formed on a substrate and a probe provided on a free end side of the flexible portion, a method for manufacturing a probe unit is provided. A first step of forming a lower electrode and an extraction electrode by film formation and patterning, a second step of forming a projection of a conductor by film formation and patterning over the entire lower electrode and the extraction electrode, Including a third step of forming a flexible portion by pattern electroplating using a resist so as to straddle the extraction electrode, a fourth step of forming a probe on the flexible portion, and a fifth step of removing the convex portion A method for manufacturing a probe unit, comprising: