JPH06252131A - Method and device for forming oxide film - Google Patents

Abstract

(57) [Summary] [Structure] In the atmosphere of oxygen-containing gas molecules, the processing electrode (2) with a sharp tip is brought close to the material to be processed (1), and the surface of the material to be processed is positive and the processing electrode is positive. A voltage is applied by a DC power source (3) so that the value becomes negative, and the surface of the material to be processed immediately below the processing electrode which is brought into proximity is anodized. [Effect] It becomes possible to form a fine pattern of an oxide film with an extremely high resolution that exceeds the resolution limit of the conventional oxide film manufacturing method. Therefore, it becomes possible to manufacture a semiconductor element having a high degree of integration or a diffractive optical element for light having an extremely short wavelength such as soft X-rays for short wavelengths. Since the oxide film pattern can be directly formed on the surface of the material to be processed, the processing efficiency and the processing flexibility are greatly improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for manufacturing an oxide film. More specifically, the present invention relates to a method for manufacturing an oxide film useful as a microfabrication technique for manufacturing semiconductor elements such as ICs and LSIs, optical elements such as diffraction gratings and zone plates, and a manufacturing apparatus therefor. is there.

[0002]

2. Description of the Related Art Conventionally, in the manufacturing process of semiconductor elements such as IC and LSI, optical elements such as diffraction gratings and zone plates, a fine oxide film pattern is formed on the surface of a material to be processed. A photolithography technique is known as one of the methods for forming the oxide film pattern. This photolithography process is usually carried out by 1) manufacturing a photomask having a predetermined pattern, 2) applying a photoresist to the surface of a material to be processed, and 3) projecting a photomask image on the photoresist surface. Exposure, 4)
This process includes the steps of developing a photoresist and forming a photoresist pattern on the surface of the material to be processed by this photolithography.

However, when an oxide film pattern is to be further formed on the surface of the material to be processed after forming the photoresist pattern, after the material to be processed is oxidized,
The remaining resist had to be stripped off, which required a lot of time and effort. Further, in this photolithography technique, there is a limit in resolution depending on the wavelength of light, and even if ultraviolet rays having a short wavelength are used for exposure, it is impossible to form a pattern finer than 0.2 μm. There was a limit to the fine processing by.

In this photolithography technique,
Not only is it difficult to maintain the quality of the pattern due to the multi-step process, but to form many types of patterns, a photomask must be prepared for each type of pattern, He lacked a lot of freedom. Therefore, the conventional oxide film manufacturing method represented by the photolithography technique is not satisfactory in terms of processing efficiency, processing performance, and processing flexibility because of the formation of a fine oxide film pattern. .

The present invention has been made in view of the above circumstances, and solves the drawbacks of the conventional method for producing an oxide film, and provides a new oxide film excellent in processing efficiency, processing performance and processing flexibility. It is an object of the present invention to provide a manufacturing method and a manufacturing apparatus therefor.

[0006]

In order to solve the above-mentioned problems, the present invention makes an electrode for sharpening work close to a material to be processed in an atmosphere in which an oxygen-containing molecular gas is present, so that the material to be processed is processed. There is provided a method for producing an oxide film, characterized in that a voltage is applied between the working electrode and the surface just below the working electrode to anodize. Further, the present invention provides, as an apparatus therefor, a sharpening processing electrode that can be brought close to a material to be processed, a current detection unit that detects a current flowing between the processing electrode and the surface of the material to be processed, and a processing electrode. Between the processing electrode and the surface of the material to be processed, and the relative position control means for controlling the relative position of the processing electrode and the material to be processed so that the current becomes constant, and the supply of oxygen-containing molecular gas Also provided is an apparatus for producing an oxide film, which includes the control means and the control means.

[0007]

The method for producing an oxide film according to the present invention is a completely new method which has never existed before. In this method, first, a material to be processed is placed in an atmosphere in which an oxygen-containing molecular gas is present, and then, , A sharpened electrode with a sharp tip is brought close to the material to be processed, and the surface of the material to be processed is a positive electrode,
A voltage is applied between the material to be processed and the processing electrode so that the processing electrode becomes a negative electrode. When the processing electrode comes close to the surface of the material to be processed to some extent, a current starts to flow between the processing electrode and the material to be processed. As a result, the surface of the material to be processed causes an electrochemical reaction with the oxygen-containing molecular substance or the oxygen-containing molecular compound adsorbed on the surface, and the surface of the material to be processed is anodized.

Therefore, by using a sharp-edged needle as a processing electrode, the area of the range where the material to be processed is oxidized is made extremely small, and the value of the current flowing between the material to be processed and the processing electrode is reduced. By controlling the position of the processing electrode so that the surface of the material to be processed is traced so as to be constant and moving the processing electrode so as to trace the surface of the material to be processed, a free-form oxide film pattern with high resolution of 0.1 μm or more can be formed. It can be formed on the surface of the material to be processed.

Examples will be shown below to describe the method and apparatus for manufacturing an oxide film of the present invention in more detail.

[0010]

Embodiment 1 FIG. 1 is a schematic diagram illustrating the apparatus configuration for the method of the present invention. For example, as illustrated in FIG. 1, the work material (1) and the work electrode are connected to the DC power source (3) so that the work material (1) becomes the positive electrode and the work electrode (2) becomes the negative electrode. (2) is connected to. The processing electrode (2) has a needle-like shape with a sharp tip. Therefore, a voltage is applied between the work material (1) and the working electrode (2), and the relative position control means (5) is used to move the working electrode (2) to the work material (1). When approaching the surface,
An electric current starts to flow between the processing electrode (2) and the material to be processed (1). This current is detected by the current detection circuit (4), and the relative position between the processing electrode (2) and the material to be processed (1) is controlled by the relative position control means (5) so that the detected current value becomes constant. .

As the relative position control means (5), for example, a three-dimensional actuator can be used.
The current detection circuit (4) and the relative position control means (5) may be controlled by, for example, a control circuit (6). Although not shown, this apparatus also includes a gas supply means for making the oxygen-containing molecular gas an atmosphere and a control means thereof. The oxygen-containing molecular gas adsorbed on the surface of the material to be processed causes an electrochemical reaction with the material (1) to be processed with high spatial resolution.

Regarding the control of the molecular gas atmosphere, for example, the material to be processed (1), the processing electrode (2) and the relative position control means (5) are placed inside a glove box or the like, and a nitrogen gas flow or the like is applied to the inside of the glove box or the like. May be replaced by changing the flow rate of the nitrogen gas flow to control the concentration of oxygen-containing gas molecules in the glove box. As the oxygen-containing molecule, water vapor or oxygen molecule containing oxygen can be used. It is also possible to use oxidizing gas molecules such as nitric oxide.

Since the processing resolution depends on the tip shape of the processing electrode (2), the radius of the processing electrode tip is preferably 100 nm or less. Further, as the material of the working electrode, for example, a noble metal such as platinum or gold or an alloy thereof, or an electrochemically stable material such as conductive diamond can be used. Among these materials, conductive diamond is not only electrochemically stable, but also has excellent mechanical strength.
It is a material suitable for stable fine processing.

Then, the method of the present invention comprises titanium,
It can be applied to all materials capable of forming an oxide film by anodic oxidation such as metals such as tantalum, tungsten and aluminum, semiconductors such as silicon, germanium, gallium arsenide and indium phosphide. further,
Even if it is a material that is difficult to anodize like an n-type semiconductor,
Stable processing is possible by means such as oxidation while illuminating with light having energy higher than the band gap of the semiconductor. Example 2 Actually, in the apparatus configuration shown in FIG. 1, the conductive diamond was used as the processing electrode (2), and the temperature 2 in the presence of nitrogen was used.
A titanium substrate placed in a nitrogen atmosphere at 3 ° C. and a relative humidity of 20% was processed.

A voltage of 8 V is applied between the diamond electrode and the titanium substrate, and the current between the diamond electrode and the titanium substrate is controlled to be constant at 100 pA, while a speed of 2 μm / sec on the titanium surface. Then, the diamond electrode was moved to process a diffraction grating (the number of which is about 33,000 per 1 mm) of 30 nm. FIG. 2 shows the result of observing the surface after processing with a general scanning tunneling microscope (STM). The convex portion in FIG. 2 is an oxide film on the surface of titanium formed by the method of the present invention. Water molecules adsorbed on the surface of the substrate and titanium cause an electrochemical reaction, and processing with an extremely high resolution of 30 nm has been achieved.

[0016]

As described above in detail, according to the present invention, it becomes possible to form a fine pattern of an oxide film with an extremely high resolution, which exceeds the resolution limit of the conventional oxide film manufacturing method. It is possible to manufacture a semiconductor element having a high degree of integration and a diffractive optical element for light having an extremely short wavelength such as a short wavelength or soft X-ray. Further, since an arbitrary oxide film pattern can be directly formed on the surface of the material to be processed without going through a multi-step process, the processing efficiency and the processing flexibility are greatly improved.

[Brief description of drawings]

FIG. 1 is a block diagram illustrating a device of the present invention.

FIG. 2 is an STM image diagram showing a cost aspect after processing as an example of the present invention.

[Explanation of symbols]

 1 Work Material 2 Processing Electrode 3 DC Power Supply 4 Current Detection Circuit 5 Relative Position Control Means 6 Control Circuit

Claims (8)

[Claims] 1. An electrode for sharpening processing is brought close to a material to be processed in an atmosphere of oxygen-containing molecular gas, a voltage is applied between the material to be processed and the processing electrode, and the surface immediately below the processing electrode is an anode. A method for producing an oxide film, characterized by oxidizing. 2. The method for producing an oxide film according to claim 1, wherein the sharpening electrode is moved along the surface of the material to be processed to form an oxide film pattern having an arbitrary shape. 3. The method for producing an oxide film according to claim 1, wherein the oxygen-containing molecular gas is water vapor and / or oxygen molecules. 4. Anodizing while detecting a current flowing between the sharpening processing electrode and the surface of the material to be processed and controlling the relative position of the processing electrode and the material to be processed so that the current becomes constant. The method for producing an oxide film according to claim 1. 5. The method for producing an oxide film according to claim 1, wherein the amount of oxygen-containing molecular gas is controlled to carry out anodization. 6. A sharpened machining electrode that can be brought close to the material to be machined, a current detection means for detecting a current flowing between the machining electrode and the surface of the material to be machined, a surface of the material to be machined and the surface of the material to be machined. Between the electrode for processing and the relative position of the material to be processed so as to keep the current constant, and the supply of oxygen-containing molecular gas and its control means. And an oxide film manufacturing apparatus. 7. The oxide film manufacturing apparatus according to claim 6, wherein the conductive diamond is used as the processing electrode. 8. The oxide film manufacturing apparatus according to claim 6, which processes a metal material or a semiconductor material.