JPH04111312A - Method and apparatus for fine processing - Google Patents

Abstract

PURPOSE:To satisfactorily perform fine processing without reducing etching pressure and etching speed and to form a pattern of high quality by applying elastic liquid to electrodes and processing finely it while exciting an elastic wave in a sample by elastic wave generating means provided on the rear surface of a sample base used also as an electrode and as a stage on which the sample is placed. CONSTITUTION:A semiconductor substrate 2 to be processed is first placed on an electrode 4. Then, etching material gas is introduced from a gas nozzle 5 into a vacuum chamber 1 while evacuating the chamber 1. Further, a high frequency voltage is applied between the electrode 4 and an opposed electrode 6 by a high frequency power source 3, etched by the gas introduced into the chamber 1, and the substrate 2 undergoes fine processing. In this case, an ultrasonic wave is further generated from an ultrasonic wave generation source connected to the rear surface of the electrode 4 as elastic wave generating means 9, the ultrasonic wave is applied to the electrode 4, and the substrate 2 is excited by the wave. Accordingly, ions, etc., incident on the substrate 2 have large momentum by the heating, moving and condensing of substance due to the elastic wave, and can enter a fine pattern.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a microfabrication device and method, particularly to a device and method for microfabrication by applying elastic waves to a substrate or a thin film formed on a substrate. 8 [Prior Art] FIG. 5 is a schematic cross-sectional view of a conventional microfabrication device, such as a plasma etching device. In FIG. is located. This semiconductor substrate (2) is, for example, polycrystalline silicon F! This semiconductor substrate (2) is one in which 1M is formed on the surface and a 7-photoresist pattern, which is an etching-resistant mask, is formed on a polycrystalline silicon thin film.
is a sample stage/chamber fi (4) connected to the high frequency power source (3) and supplying high frequency power (hereinafter simply referred to as electrode (4))
is placed on top. At a position facing the semiconductor substrate (2), a counter electrode (6) is provided with a gas nozzle (5) for uniformly supplying a reactive etching material gas such as chlorine gas toward the semiconductor substrate (2). ) is arranged in the vacuum chamber (1).The vacuum chamber (1) includes an exhaust port (7) for evacuating the inside of the vacuum chamber (1) and a reactive gas for supplying etching material gas into the vacuum chamber (1). A supply port (8) is provided.

The conventional microfabrication apparatus is configured as described above, and in order to perform microfabrication, first, a reactive gas is supplied while the inside of the vacuum chamber (1) is evacuated through the exhaust port (7) by an exhaust means (not shown). Etching material gas is introduced into the vacuum chamber (1) through the gas nozzle (5) through the opening (8).Next, a high frequency voltage is applied between the electrode (4) and the counter electrode (6) by the high frequency power source (3). is applied to produce a glow discharge. As a result, the etching material gas introduced into the vacuum chamber (1) is activated and plasma (A
) and generate active neutral molecules, neutral atoms, and ions. Etching of the semiconductor substrate (2) progresses by these molecules, atoms, and ions, and microfabrication is performed.

[Problems to be Solved by the Invention] The conventional microfabrication techniques described above have the following problems.

(1) Uniformity of etching rate In conventional techniques, the in-plane etching rate is particularly high for large-diameter etching samples because a spatial distribution of activated halogen gas or ions that contribute to etching occurs. There is a problem in that the etching chamber needs to be enlarged in order to reduce this in-plane distribution.

(2) Etching selectivity with respect to the underlying film In conventional techniques, the sample to be processed is irradiated with an etchant such as charged particles in an accelerated state, which not only damages the etched surface but also prevents the etching of the underlying film. It is also not possible to obtain sufficient selectivity between the layers.

(3) Decreased etching speed of fine patterns due to microloading effect In the conventional technology, due to poor etchant directionality, the supply of etchant at intervals between fine patterns decreases, and the etching speed decreases. Furthermore, pattern size dependence occurs in the degree of adhesion of reaction products to the sidewalls of etching patterns formed during etching, and the pattern size dependence of anisotropic etching profiles poses a problem.

(4) Due to the above-mentioned problems, there is a problem in that various characteristics of active elements formed by micro-machined evaturns deteriorate.

This invention was made to solve these problems, and it is possible to perform fine microfabrication without lowering the etching pressure or slowing down the etching speed, and to form a high-quality pattern. The purpose is to obtain a microfabrication device and method.

[Means for Solving the Problems] A microfabrication apparatus according to claim (1) of the present invention is one in which an elastic wave generating means is provided on the back surface of a sample stage/electrode on which a sample is placed.

Further, the microfabrication method according to claim (2) of the present invention includes:
Microfabrication is performed while applying elastic waves to the sample using an elastic wave generating means.

[Function] Microfabricated bag according to this invention! In this method, since microfabrication is performed while applying elastic waves to the electrodes and exciting the elastic waves in the sample, good microfabrication is possible and good machining characteristics can be obtained.

[Example] In conventional microfabrication of substrates, etc., technologies that apply high frequencies, microwaves, optical energy, energy beams, etc. have already been invented, but none that apply elastic waves. We will explain microfabrication that applies this.

The microfabrication apparatus and method according to the present invention utilizes the following effects of elastic waves on materials.

(1) Heating of materials by elastic waves During the propagation process, elastic waves are generally attenuated by interaction with a medium. The wave energy lost due to attenuation becomes thermal energy and heats the medium, leading to a rise in temperature.The energy loss per unit volume due to wave attenuation described above is: If the attenuation coefficient is the same, the amplitude of the wave is large. The larger it becomes. In particular, when a resonant structure exists, a standing wave with a sufficiently large amplitude is excited in the structure,
This results in large local energy losses. This also enables local heating.

The following effects on microfabrication characteristics are expected by heating the workpiece and increasing the temperature. −
For boat fishing, ■Increase in microfabrication speed due to promotion of thermal reaction, ■Improvement in etching selectivity due to differences in chemical reactions during local heating, and ■Etchant penetration into the inside of fine patterns becomes easier. Improvements in microprocessability, etc. These effects make it possible to improve microprocessability.

(2) Movement of matter due to elastic waves Elastic waves are caused by the movement of matter due to the restoring force to the equilibrium point that is generated by the movement of matter from its mechanical equilibrium point. The existence of a substance is synonymous with the existence of a displacement of matter. When elastic waves are excited in a material that contributes to etching during microfabrication, the region smaller than the wavelength of the surface depends on the direction of wave propagation and the angle between the change vector and the wave number vector, but in the vertical direction , or perform periodic movement in the direction tangent to the surface.

Such movement improves the microfabrication characteristics as follows. When the velocity excited by the elastic wave is greater than the velocity of the incident particle, the relative velocity of the incident particle increases, and the momentum of the incident particle increases, resulting in ■increased microfabrication speed, and ■direction of the incident particle. ■Improvement of microfabrication by making it easier for etchant to penetrate into the fine pattern, ■Improvement of etch-off performance in areas with thick absolute film thickness at step portions, ■
This includes promotion and improvement of desorption due to the reaction products being vibrated by elastic waves. These effects make it possible to improve microprocessability.

(3) Condensation of matter caused by elastic waves Only minute particles are moved by elastic waves, increasing the chance of collision, which promotes etchant aggregation and etchant dissociation in the plasma, resulting in the following microfabrication characteristics: improved as follows. ■Increasing the microfabrication speed by increasing the etchant density; ■Since the type of etchant can be changed by a dissociation phenomenon that is not caused by the normal discharge action, selective microfabrication becomes possible. These effects make it possible to improve microprocessability.

Next, an embodiment of the present invention will be described with reference to the drawings. 1st
The figure is a schematic diagram showing a microfabrication apparatus, such as a plasma etching apparatus, according to an embodiment of the present invention.
) is exactly the same as that in the conventional microfabrication apparatus described above. In this invention, elastic wave generating means (9)
As such, an ultrasonic generation source is used that generates waves in the so-called ultrasonic region with an elastic wave frequency of 10 KHz or more. That is, piezoelectric vibrators, electrostrictive vibrators,
Physically connect a magnetostrictive vibrator or the like (also serving as a sample stage) to the back surface of the pole (4).

Figure 2 shows the cross-sectional shape of a polycrystalline silicon film on a semiconductor substrate etched by the plasma etching apparatus shown in Figure 1.
) A silicon oxide film (11) is formed on the base material (1o), and a polycrystalline silicon film (12), which is a film to be processed, is formed on the silicon oxide film (11). Further, on the polycrystalline silicon film (12), a photoresist film (13) patterned by a photolithography process is formed as an etching-resistant mask. Also, Figure 3 shows
A semiconductor substrate (2) similar to that shown in FIG. 2 when using a conventional microfabrication device that is not provided with an elastic wave generating means (9).
The cross-sectional shape is shown.

In the microfabrication method using the microfabrication apparatus configured as described above, first, a semiconductor substrate (2) as a workpiece is placed on an electrode (4). Next, while evacuating the inside of the vacuum chamber (1) through the exhaust port (7), a reactive gas, ie, a cutting material gas, is introduced into the vacuum chamber (1) through the gas nozzle (5). Furthermore, a glow discharge is generated by applying a high frequency voltage between the electrode (4) and the counter electrode (6) by the high frequency power source (3), and the vacuum chamber (1) is
The processing/etching material gas introduced into the chamber is activated and turned into plasma, generating active neutral molecules, neutral atoms, and ions. Etching of the semiconductor substrate (2) progresses by these molecules, atoms, and ions, and microfabrication is performed.

At this time, an ultrasonic wave is further generated by the ultrasonic generating source,
Ultrasonic waves are applied to the electrode (4) on which the semiconductor substrate (2) is placed, thereby exciting the ultrasonic waves in the semiconductor substrate (2). At this time, due to the above-mentioned effects of heating, movement, and condensation of the substance by the elastic waves, the ions, etc. that are incident on the surface of the semiconductor substrate (2) have a larger momentum than in the case where they are not excited by the ultrasonic waves. As shown in Figure 2, it is possible to penetrate into the fine pattern. Therefore, the fine machinability of the semiconductor substrate (2) is improved and high-quality pattern formation is possible without reducing the etching pressure and etching speed. On the other hand, in the case shown in Figure 3 which does not use an ultrasonic source, the etching pressure is lowered to lengthen the average life of active ions, and etching is performed using ions with good directionality. Even if it were, the ions would not penetrate sufficiently into the fine holes (turns), making it impossible to perform good fine processing.

In the above embodiment, the elastic wave generating means (9) was provided on the back surface of the sample stage/electrode (4), but as shown in FIG. (14) may also be provided, and the same effect as described above can be achieved.

In the above embodiments, plasma etching was explained as a microfabrication method, but reactive ion etching, magnetic field assisted reactive ion etching, electron cyclotron plasma etching, neutral beam etching, optical excitation etching It is equally applicable to etching, photo-assisted etching or physical ion etching.

Further, although the silicon oxide film (11) is used as the film to be microfabricated, it may be a silicon nitride film, a silicon oxynitride film, or a single crystal silicon film may be used instead of the polycrystalline silicon film (12). good.

Furthermore, the film to be microfabricated may include tungsten, tantalum, molybdenum, zirconium, titanium, hafnium, chromium, platinum, iron, zinc, or tin, and their silicides, nitrides, or carbides, aluminum, copper, gold, silver,
and alloys containing these as main components; films of organic polymer materials such as novolac resins and polyimides may be used.

Further, the film to be microfabricated may be a ferroelectric material such as PZT (lead/zinc tin), a superconductor including an oxide superconductor, or a ferromagnetic material.

In the embodiments described above, the sample, that is, the material to be processed,
Although we have explained the thin film formed on the semiconductor substrate (2) in the manufacturing process of semiconductor integrated circuits, it is also used as a base material in the process of forming storage elements such as magnetic tapes and magnetic disks used in magnetic storage devices, and in optical storage devices. It may be a base material used in the process of forming a storage element such as an optical disk, a formed metal object or a thin film microfabricated on the surface thereof, or a mechanical element such as a screw or a processing tool.

[Effects of the Invention] As explained above, the microfabrication apparatus and method according to the present invention performs microfabrication while applying elastic waves to the electrode on which the sample is placed, so that the microfabrication device and method according to the present invention perform microfabrication without reducing the etching pressure.
In addition, it is possible to perform fine microfabrication without reducing the etching speed, and also to form a high-quality pattern and have good processing characteristics.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view showing a plasma etching apparatus according to an embodiment of the present invention, FIG. 2 is a side cross-sectional view of a semiconductor substrate etched by the apparatus shown in FIG. 1, and FIG.
The figure is a side cross-sectional view of a semiconductor substrate etched by a conventional plasma etching apparatus, and FIG. 4 is a schematic cross-sectional view of a plasma etching apparatus according to another embodiment of the present invention.
FIG. 5 is a schematic cross-sectional view of a conventional plasma etching apparatus. In the figure, (1) is a vacuum chamber, (2) is a semiconductor substrate, (3) is a high frequency power supply, (4) is a sample stage and electrode, (5)
) is the gas nozzle, (6) is the counter electrode, (7) is the exhaust port,
(8) is a reactive gas supply port, (9) and (14) are elastic wave generating means, (10) is a base material, (11) is a silicon oxide film, (12) is a polycrystalline silicon film, (13) is a photoresist film. In each figure, the same reference numerals indicate the same or corresponding parts.

Claims (2)

[Claims] (1) a vacuum chamber; a reactive gas supply means for supplying a reactive gas into the vacuum chamber; and a plasma generation means for generating plasma of the reactive gas in the vacuum chamber; disposed within the vacuum chamber. a sample stand/electrode on which a sample is placed and which is connected to the plasma generating means and serves as an electrode; an elastic wave generating means provided on the back side of the sample stand/electrode; and an exhaust means for evacuating the inside of the vacuum chamber. A microfabrication device characterized by comprising: (2) Place the sample to be microfabricated on a sample stand and electrode in a vacuum chamber, evacuate the vacuum chamber to a predetermined degree of vacuum, supply a reactive gas into the vacuum chamber, and Plasma of the reactive gas is generated in the vacuum chamber by the stage/electrode and the plasma generating means, and then microfabrication is performed while applying elastic waves to the sample by the elastic wave generating means provided on the back side of the sample stage/electrode. A microfabrication method characterized by performing.