JPH0362546A - Scanning probe and manufacture thereof - 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 [Object of the Invention] (Industrial Application Field) The present invention relates to a scanning tunneling microscope and an evaluation device using its application technology, and particularly to its scanning probe and its manufacturing technology.

(Prior art) 1982 IBM G, B1nn1g & H, Ro
Hler announced the scanning tunneling microscope (hereinafter abbreviated as STM) (Phys, Rev, Lett, 4
9 (1) 57 (1982)), many researchers and engineers have developed equipment and developed new evaluation application techniques as a high spatial resolution evaluation technology that can measure from the atomic level in the past few years. (IBMJ, Res,
Devlop, vol, 30. no, 4 (19
86) 355).

Tungsten (
Probes made of W) or platinum (Pt) wire with a sharpened tip by electrolytic polishing or the like are widely used.

On the other hand, it is desired to improve measurement throughput and scanning range, but with a single wire probe, the limit is that it can scan a range of at most a few p, and if you try to widen the measurement range, the throughput will drop significantly. do. For this reason, it is desired to introduce multiple probes, but it is extremely difficult to arrange the wire probes with uniform height and accurate positioning with high precision.

(Problems to be Solved by the Invention) The present invention has been made in consideration of the above circumstances, and its first purpose is to arrange the parts with uniform height and accurate positioning with high precision, and to arrange the individual parts individually. The second object is to provide a manufacturing method for realizing the scanning probe simply and with high precision.

[Structure of the invention]

(Means for Solving the Problems) The first feature of the present invention is that a plurality of conductive thin film electrodes are selectively formed on two opposing surfaces of a piezoelectric substrate, and one side on which a probe is formed is formed. A scanning probe is provided with a plurality of probes each having a sharp tip and made of a conductive material on the conductive thin film electrode.

The second is a method for manufacturing the scanning probe, which is constructed based on microfabrication technology and selective growth technology in the semiconductor field. The purpose is to sharpen each probe by performing Taber etching using a resist mask.

That is, the present invention is based on LSI manufacturing technology, and is based on so-called S XM (Scanning
It is characterized by making it possible to use a scanning probe with a plurality of probes for microscopy using a simple technique.

(Function) According to the present invention, a scanning probe having a plurality of probes can be realized with uniform height and arrangement position accuracy within 1 μm.

Furthermore, since a piezoelectric actuator for fine movement is configured by the piezoelectric substrate and the conductive thin film electrodes on the opposing surfaces thereof, the distance between each probe and the sample can be adjusted individually. Therefore, it is possible to realize independent Z-axis servo functions for each probe with a relatively small unit, which simplifies the multi-probe STM structure and allows each probe to perform measurements independently. become.

(Example) Hereinafter, details of the present invention will be explained with reference to illustrated embodiments.

FIGS. 1(a) and (b) show a cross-sectional view and a plan view, respectively, of a scanning probe according to an embodiment of the present invention. FIG. 1(8) shows the P- A partial cross section between Q is shown.

Details of each part in FIG. 1(a) will be explained in the manufacturing method described later. As shown in FIG. 1(b), in the case of this embodiment, four probes are arranged, and each probe pedestal is connected to the extraction electrodes A1-A4, and the piezoelectric material is connected via these electrodes. A specified potential can be supplied to one electrode of the substrate (here, lead zirconate titanate ferroelectric). On the other hand, the opposing electrodes on the back surface of the piezoelectric substrate are connected to the extraction electrodes 81 to B4, and each probe is The nearby piezoelectric substrate expands and contracts. When scanning over the uneven sample surface due to this expansion and contraction, the respective servo functions of each probe (the servo control circuit is not shown) are activated, and the probes TL and T2 follow the unevenness of the sample surface. It can be raised and lowered independently (Figure 2).

Next, with reference to FIGS. 3(a) to 3(k), a method for manufacturing the scanning probe of the embodiment shown in FIG. 1 will be specifically explained. First, the third
In Figure (a), 0.2p of platinum (Pt) is applied as a conductive thin film electrode material 2 on both sides of a lead zirconate titanate ferroelectric substrate 1.
Deposit to some extent. On one side of the probe forming surface, a silicon oxide film 3 with a thickness of 0.3. degree CVD (Chem
ical vapor deposition) method.

Next, as shown in FIG. 3(b), 20. A square electrode pattern is formed using photoresist 4, as shown in Fig. 3 (
As shown in c), using this as a mask, the silicon oxide film 3 is first selectively etched away (by ammonium fluoride treatment, etc.). Subsequently, using the same mask, the platinum 2 on both sides of the electrode material is removed by etching (by aqua regia treatment, ion milling, etc.). As a result of the etching process, a silicon oxide film 3A is formed under the resist mask 4 on the electrodes 2A, 2B and 2A including the lead-out electrode. After peeling off the resist mask 4 that is no longer needed, an organic insulating film 5 (for example, polyimide, etc.) covering the exposed ferroelectric material is formed on the south side, and a new resist is added as shown in FIG. 3(d). Using a mask 6, a portion of the silicon oxide film 3A is selectively removed by etching (ammonium fluoride treatment, plasma etching, etc.) to open a hole 3c.

Next, as shown in FIG. 3(e), after peeling off the resist mask 6 that is no longer needed, a polycrystalline silicon film 7 of 0.5 - Deposit to a certain extent. Thereafter, a resist mask 8 including an electrode pattern to be taken out and a probe base is formed, and the resist mask 8 selectively selectively removes the polycrystalline silicon film 7.
After removing the resist mask 8 by etching (plasma etching or the like) and peeling off the resist mask 8 which is no longer needed as shown in FIG. 3(f), a probe pedestal electrode 7A is formed on the electrode 2A. Subsequently, as shown in FIG. 3(g), a sufficiently thick resist mask 9 (photosensitive polyimide film, etc.) of about 10 to 100 mm is formed, and has openings 7C in parts of the electrode 2A and the probe pedestal electrode 7A. form.

A conductive material (e.g. tungsten) is inserted into this deep hole.
10 selective growth was performed to fill the opening (Fig. 3 (h)), and then selective growth was performed only on the tip growth area.
Selective resist 1 having approximately the same dimensions as the embedded openings
1 is formed as shown in FIG. 3(i).

Using this resist 11 as a mask, the tip of the tungsten IO is taper-etched by reactive ion etching using chlorine-based gas, taking advantage of the receding of the resist mask 11, thereby obtaining a sharp protruding probe shape. Reactive ion etching ends when the resist mask 11 disappears (Fig. 3 (j)).The thick resist mask 9' left at this time is peeled off and removed by organic solvent treatment or oxygen plasma treatment to form an organic insulator. The membrane 5 is exposed. At this time, if the surface of the tungsten probe and extraction electrode portion is covered with an oxide film, it is preferable to modify the surface by fluorine-based plasma treatment (FIG. 3(k)).

The distance between the probes in the embodiment of the present invention is on the order of several hundred meters (FIG. 1(a)). It is possible to accurately drive the fine movement piezoelectric actuator even at a distance less than that, for example, it is possible to drive the fine movement piezoelectric actuator even at a distance of about 10 μs. Although lead zirconate titanate ferroelectric material was used as the piezoelectric substrate, it is not limited to this material in particular; for example, any existing ferroelectric material such as barium titanate may be used. . In addition, the expansion and contraction of the piezoelectric substrate is approximately from several hundred people to 1 p.
That's about it. for example.

In order to increase the degree of expansion and contraction, it is sufficient to increase the thickness of the piezoelectric substrate, so the selection of the ferroelectric material is not particularly important. In the embodiment, an electrode including a take-out electrode on a substrate,
A probe pedestal electrode is formed on it, and a probe is formed on it, and the electrode including this take-out electrode functions as a barrier. That is, this probe pedestal electrode is made of polycrystalline silicon, but silicon may be in a mixed crystal state with the lead zirconate titanate ferroelectric material, resulting in deterioration of piezoelectric properties (for example, if the piezoelectric constant is 20 ~30% decrease)
. The reaction layer in which this mixed crystal is generated penetrates into the ferroelectric material from the interface to a thickness of several 10 mm. Therefore, the ferroelectric substrate is 100
If the thickness is less than -, this effect will appear, but if the thickness exceeds 200p, there will be little effective effect. Deterioration of piezoelectric properties due to this mixed crystal exists in other materials such as barium titanate, although there are differences in degree. An electrode made of platinum or the like is inserted between the substrate and the probe pedestal electrode mainly for the purpose of preventing this mixed crystal. Although platinum is used for this electrode in this embodiment, it is not limited to this, and any metal that does not mix with silicon can be selected. for example,
Silver is one of them. Electrodes with baked silver paste are particularly famous for their use in ultrasonic transducers. This electrode must be in close contact with the piezoelectric substrate, and an effective way to improve the adhesion is to sandwich a thin layer of chromium, titanium, or the like between platinum or silver and the piezoelectric substrate. It is also possible to intentionally add a small amount of a glass component such as silica or boron oxide in order to improve the adhesion of silver, and to utilize a mixed crystal thereof.

In this example, during selective growth of tungsten.

Although we have shown an example using an organic thick film, selective growth of tungsten is also possible by selective beam irradiation (for example, spot irradiation with an electron beam) in a tungsten hexafluoride gas atmosphere. Since the tip is sharpened at the same time, an organic thick film with holes for selective growth is naturally not used, and the selective resist mask shown in FIG. 3(i) is also unnecessary. Both the method using this beam irradiation and the method using the organic thick film described above are effective for the scanning probe with multiple probes of the present invention, but they cannot be used for the scanning probe with a single probe. This method also has remarkable effects similar to the present invention.

The evaluation device according to the present invention targets a semiconductor substrate such as silicon, but it can also be used as an optical mask. For example, it is possible to observe the interface state of a chrome mask pattern on a mask substrate, and to detect and measure its defects.

Although the application to STM has been described here, AF using a scanning probe may be used without departing from the spirit of the present invention.
Needless to say, it can also be applied to M, MFM, etc.

〔Effect of the invention〕

As described in detail above, according to the present invention, a large number of probes can be used independently as measurement probes, so it is possible to simultaneously carry out measurements at multiple points, and the actual scanning range can be expanded. In other words, it is possible to realize an improvement in measurement throughput. Further, the scanning probe can be easily realized with high precision.

[Brief explanation of drawings]

FIGS. 1(a) and (b) show a partial cross-sectional view and a plan view, respectively, showing the general structure of an embodiment of the scanning probe of the present invention. FIG. 2 shows the present invention for STM scanning. FIG. 2 is a schematic diagram illustrating the relationship between a measurement sample and a scanning probe when used as a probe. FIGS. 3(a) to 3(k) show an embodiment of the process of manufacturing the scanning probe of the present invention. (... Piezoelectric substrate, 2... Conductive thin film electrode material (platinum). 2A, 2B... Electrodes including extraction electrodes, 3.3A.
・Insulating film (silicon oxide film), 4.6, 8, 9, 9'
, 11... Selective resist mask 5... Organic insulating film (polyimide), 7... Polycrystalline silicon film, 7A... Probe pedestal electrode, 7C... Resist mask opening, 10...・Selective growth tip material (tungsten), Tl,
T2... probe, Al-A4. Bl to B4... take-out electrodes.

Claims (2)

[Claims] (1) A piezoelectric substrate, a plurality of conductive thin film electrodes formed on two opposing surfaces of the piezoelectric substrate, and a plurality of conductive thin films formed on one of the two surfaces. A scanning probe comprising a probe provided on each electrode. (2) The method for manufacturing a scanning probe according to claim 1, wherein the probes are formed on each of a plurality of conductive thin film electrodes formed on one surface of the piezoelectric substrate, wherein the probes are formed by selective growth. and forming a selective resist mask on each of the probes, and sharpening each of the probes by taper etching the probes using the selective resist mask. Method of manufacturing a scanning probe.