JPS6298731A - Surface processing and apparatus thereof - Google Patents

Abstract

PURPOSE:To perform assisted etching process efficiently by making use of hot molecule to augment inner energy. CONSTITUTION:An Si specimen 4 loaded on a specimen base 6 is arranged in a reaction chamber 3. Sulfun hexaluoride SF6 contained in a gas cylinder 2 is fed to a hot molecule source 10 to be brought into the state of hot molecule and then further fed to the reaction chamber 3. The Si specimen 4 can not be etched at all by thus fed SF6 only but can be etched at the speed around 300nm/min when it is irradiated with argon ion shower from an ion source 1 subject to energy of around 100eV and current density of 0.8mA/cm<2>. This etching speed is almost ten times higher than that in the case of physical sputter etching process using Ar ion shower only.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a surface treatment method and apparatus therefor in a dry process, and more particularly to a surface treatment method and apparatus suitable for manufacturing semiconductor devices.

[Background of the invention]

Traditional dry processes, especially in semiconductor device manufacturing, have used ion beams or plasma (
For example, Takuo Kanno (ed. 2) [Semiconductor Plasma Process Technology], Sangyo Toshoren, 1980).

Also, recently, Yung-Yi T
[Chemical sputtering of fluorinated silico 7] by U) et al.
tering of flu-originated 5i
Licon River, Physical Review B (Phy.

Reu, B) 23 p823 (1981), G. Koren, 1981, 1,000s of Aluminum Metal Films, Ion-Assisted Etcher. Menz (Excimer 1a
ser etching of A/metalfi
lms in chlorine environment
nts) J, Applied Physics Letters (A
ppl, Phys, Lett, ) 46 p 1
Dry processes (etching, surface treatment) that use the interaction of gas molecules with light or ions, such as the optical ansted etching shown in 006 (1985), have also been studied. In addition, when using ions, in addition to ion showers and normal ion beams, ion beams focused to a diameter of 01 μm or less, such as focused ion beams (FIBs), may be used (for example, snowflakes).
Maskless Ion Beam As5i et al.
Stead Etching of SiUsing C
Hlorine Gas) J, Japanese Journal of Applied Physics (Jap, J,
Appl, Phys, ), 24, I) L 169
(1,985)).

FIGS. 6A and 6B are schematic configuration diagrams showing examples of conventional ion-assisted etching and light-assisted etching, respectively. In FIG. 6(A), a sample stage 6 on which a sample 4 is placed is placed in a reaction chamber (vacuum chamber) 3, gas is introduced into the reaction chamber 3 from a gas cylinder 2, and ions are emitted from an ion source 1. Etching is performed by irradiating the sample 4 with the beam 5a. In addition, in FIG. 6(b), the light beam 8 from the light source 7 is used instead of the ion beam.
Etching is carried out by irradiating the sample 4 with the sample 4 through a window 9 provided in the reaction chamber 3.

The above-mentioned assisted etching (or deposition, etc.) is inefficient in exciting or decomposing molecules with ions or light, and often results in thermal decomposition.

Furthermore, in order to perform etching and deposition, it was necessary to considerably increase the molecular gas pressure (10'' Pa or more).

In order to solve the above-mentioned problems, it is better to increase the internal energy of gas molecules so that the reaction is not sufficient on its own, but it can react efficiently with the assistance of light, electrons, and ions. In particular, in etching, if only the areas irradiated with light, electrons, and ions react, the reaction position controllability will be improved, and the etching shape will become vertically suitable for microfabrication, making it a highly effective method. becomes.

[Purpose of the invention]

An object of the present invention is to provide a surface treatment method and an apparatus therefor that can perform dry surface treatment with high efficiency and further enable position control as required.

[Summary of the invention]

In photo-assisted etching and ion-assisted etching, C12 gas and the like have been used until now, but they are inefficient and require a high gas pressure of several Pa or more (at least near the reaction area).

On the other hand, the present inventors previously proposed a method of using molecules with excited molecular vibrational levels (hereinafter referred to as hot molecules) for surface treatment (Japanese Patent Application No. 59-233149, Patent Application No. 60- No. 126023). We have been conducting experiments to apply this low-internal-energy molecular vibrational excitation to surface treatment.

Here, we will give an overview of hot molecules. Dry processes perform etching, deposition, etc. using physical and chemical reactions on the sample surface or in the gas phase, but in this case, chemical reactions rather than physical reactions play a leading role. The energy involved in a chemical reaction is between 0.1 and 1
Since the energy that generates crystal defects is approximately IQ eV, the energy used to perform the dry process is 0.1 to 10
The eV range is optimal. In order to supply this energy of 0.1 to 10e, it is appropriate to use the vibrational level of the molecule (1eV or less). The vibrational level of a molecule has the advantage that its lifetime is on the order of 10-2 seconds, and its energy is almost never lost unless the molecule collides with other atoms, molecules, or surfaces. .

However, it was found that the field of application of hot molecules alone to surface treatment methods may be narrow, partly due to the lack of experiments. Therefore, the idea of an assisted process using these hot molecules was born. In other words, as mentioned earlier, if the internal energy of gas molecules is increased, the reaction will be more efficient with the assistance of light, electrons, and ions, so if hot molecules are used to increase the internal energy, assisted etching will be possible. (or deposition, etc.) can be performed efficiently.

The present invention has been made based on the above findings.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

Example 1: This example is an example that utilizes the interaction between hot molecules and ions. As shown in FIG. 1, inside the reaction chamber 3,
A Si sample 4 placed on a sample stage 6 is arranged.

Gas cylinders 2 to S containing sulfur hexafluoride (SFs)
F6 was sent out, subjected to hot molecularization by the hot molecularization source 10, and then flowed into the reaction chamber 3. With this alone, Sl
Sample 4 was not etched at all, but an ion shower 5 of argon ions (Ar+) was applied from the ion source 1 to an energy of about 100 eV and 0.8 mA/7? )-current density, an etch rate of about 3QQ nm/min was obtained. This value is about one order of magnitude larger than the value in physical sputter etching using only ion shower.

Example 2: This example is an example that utilizes the interaction between hot molecules and light. As shown in FIG. 2, N2 gas was sent out from a gas cylinder 2 containing nitrogen (N2), hot molecularized by a hot molecularization source 10, and flowed into a reaction chamber 3. The sample 4 placed in the reaction chamber 3 was irradiated with ultraviolet light 8a from an ultraviolet light source 7a formed from a high-pressure mercury lamp. As a result, the Si of sample 4 could be nitrided. The formed nitride film was thicker than that formed by simple N2 gas and ultraviolet irradiation.

In addition, in the case of nitriding, it is more effective to add not only hot molecules but also nitrogen radicals.

Example 3: This example is an example that utilizes the interaction between hot molecules and a light beam. As shown in Figure 3 (this is the gas cylinder 2)
A chlorinated gas (e.g. Cl2) from a hot molecularization source 1
0, and the sample 4 was irradiated with an ultraviolet beam 8b from a laser light source 7b.

As described above, using GaAs IC as sample 4,
Chip separation was performed by moving the sample stage 6 in the XY directions. Note that the movement of the beam and the sample is a relative issue, and the same effect can be achieved by moving the beam instead of moving the sample, making it possible to cause a reaction only in the area irradiated by the beam. Furthermore, in areas other than the beam irradiation, there was very little reaction with hot molecules.

Example 4: In Example 3, if a Ga focused ion beam is used instead of the laser beam, even faster etching is possible.

In addition, in cases such as making GaAs chips, the sample stage 6
Better results can be obtained by heating sample 4 by raising the temperature to around 200'C.

Example 5: Instead of heating the sample stage 6 to heat the sample 4 in the case of Example 4, as shown in FIG. Similar results can be obtained with irradiation.

Example 6: As in Example 2, when radicals and hot molecules can coexist, the hot moleculeization source 10 described so far may be a magnetic field microwave discharge type as shown in FIG. . In the figure, 11 is an insulated fractional tube, ]2 is a magnetron, and 1
3 indicates an electromagnetic coil. Note that, in order to eliminate the influence of ions, the discharge section and the reaction chamber 3 are separated by a porous plate.

Example 7: Even if an electron beam is used instead of the focused ion beam in Example 4, GaAs can be etched in the same way. With an electron beam, the position can be controlled using a relatively low-speed electron beam, so it is effective to use for localized etching or deposition of semiconductors through the interaction of hot molecules with the low-speed (accelerating voltage of several hundred electrons) electron beam. be. This method is expected to be effective in producing tertiary elements in the future if surface treatment can be performed within a range with little damage.

Various embodiments have been described above, but the present invention is effective when etching cannot be performed with hot molecules alone (position control is possible), and when etching does not proceed even if radicals coexist. It has the advantage that it is more effective to use interactions with light, electrons, or ions in the coexistence of hot molecules and radicals.

In Example 1, as in the example of Japanese Patent Application No. 59-244444 previously proposed by the inventors of the present invention, by irradiating light with a wavelength longer than the optical absorption edge of the gas-phase raw material gas,
It is also conceivable to enable film formation or etching on or near the sample surface.

Furthermore, the surface treatment referred to in the present invention is not limited to etching, deposition (film formation), and nitriding as shown in the above embodiments, but also oxidation, etc., or a combination of these with ion implantation, etc. This includes surface modification, cleaning, etc. Furthermore, the target substance
It is effective not only for surface treatment of semiconductor materials such as Si and GaAs, but also of general materials such as metals and insulators.

Further, the interaction between the hot molecule and light, electrons, and ions in the present invention does not necessarily have to be direct.

That is, the sample may be irradiated with hot molecules and light in a time-sharing manner to cause a reaction on the surface. Further, hot molecules, light, etc. may be supplied in a constant amount over time, or may be changed periodically over time.

In addition, in the method of the present invention, damage due to light, electrons, and ions can be considered, so care must be taken to suppress these energies as low as necessary and sufficient.

〔Effect of the invention〕

According to the present invention, practical and efficient dry surface treatment can be performed. In particular, the surface treatment according to the invention
It has the ability to compensate for the weaknesses of surface treatment using only hot molecules. That is, since the internal energy of hot molecules is as small as leV or less, the lack of energy can be compensated for by light, electrons, and ions. In addition, since hot molecules are electrically inactive, beam control cannot be performed using electric or magnetic fields. However, in the method of the present invention, there is no need to control the hot molecules themselves for position control, and light, electron, All you have to do is control the ion beam. In the case of light, the beam position can be controlled using a mirror or the like outside of vacuum through a window provided in the reaction chamber.

[Brief explanation of drawings]

1 to 5 are schematic configuration diagrams of an apparatus for carrying out the surface treatment method according to the present invention, and FIG. 6 (A). (b) is the conventional ion assist etching, respectively.
1 is a schematic configuration diagram showing an example of an apparatus for performing optically assisted etching.

Claims (4)

[Claims] (1) A surface treatment method characterized by performing surface treatment by the interaction of molecules with excited molecular vibrational levels and at least one of light, electrons, and ions. (2) A surface treatment method according to claim 1, characterized in that the reaction position is controlled by beam irradiation with at least one of light, electrons, and ions. (3) A surface treatment method according to claim 1 or 2, characterized in that radicals also coexist with molecules in which molecular vibrational levels are excited. (4) A reaction chamber containing a sample, a means for generating molecules whose molecular vibrational levels are excited, and sending them into the reaction chamber, and a means for interacting with the molecules whose molecular vibrational levels are excited. 1. A surface treatment apparatus comprising at least one of a light source, an electron source, and an ion source.