JPS6286730A - Surface treatment - Google Patents

Abstract

PURPOSE:To promote a surface chemical reaction without damaging surface of a sample and to execute the optimum surface treatment in a semiconductor process by a method wherein a plurality of kinds of particles are irradiated on the sample surface and turning at least one of them into a hot molecular beam. CONSTITUTION:Gas molecules M introduced through a valve 4 are heated in a heating oven 5 and are jetted in a vacuum through a jet nozzle 9, whereby a vibration-excited molecular beam is formed. The jet nozzle 9 is not always needed and may be an aperture having the same diameter as the inner diameter of the heating oven 5. A reactive particle feeding means 16 consists of a valve 10 for supplying reactive particles, a gas reservoir 1 and a jet nozzle 12. Reactive particle gas introduced through the valve 10 is turned into an even flow once in the gas reservoir 11, is jetted in a vacuum through the jet nozzle 12 and is formed into a reactive particle beam. The reactive particles are not always supplied on the surface of a sample as a beam and may be supplied as atmospheric gas having an equal speed distribution in the vicinity of the sample 3. The sample 3 is set up on a sample stand 2 and the sample stand 2 is provided with a temperature control means 13 for controlling the sample tempera ture, as required.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a surface treatment method for treating a solid surface, and particularly to a surface treatment method suitable for semiconductor processing.

[Background of the invention]

In conventional etching for semiconductor processes.

The sample was placed in plasma. In particular, RIE (Reacfive Ion Efc) using RF discharge
The mainstream method was called hing (Takuo Kanno).
Edited and authored [Semiconductor Plasma Process Technology] Sangyo Tosho, 1932
5 years, p p, 153-165). However, this method had the problem of surface damage caused by high-energy ions incident on the sample surface from the plasma (
Varnish, Daburi 21, Panda, “Dry Etching in Deust Damage in Si and GaAs”, Solid State Technology (S, W, Pang
, “Dry Etching Inducedl) am
age Ln Si and GaAs”, 5olid
State Technology) /April
1984. pp. 249-256).

Further, since plasma is similarly used for conventional abrasion, there is a problem of surface damage.

[Purpose of the invention]

An object of the present invention is to provide a surface treatment method that causes less surface damage.

[Summary of the invention]

Etching using plasma (plasma etching) has been used for the effect of promoting surface reactions by high-energy ions incident on the sample surface (ion assisted etching). However, in this case, the ions are incident with a high kinetic energy of 500 to 1000 eV, which easily causes surface damage.

This is due to the displacement energy in the Si crystal.
This can be fully inferred from the fact that (the energy required to shift the S i g particle from the crystal lattice position) is about 12.9 eV. In the present invention, hot molecules (molecules whose vibrational levels are excited) are used instead of high-energy ions to promote surface reactions and perform etching. The vibrational energy of hot molecules is 0.1 to 1 eV, and etching can be performed without causing any surface damage. The method of the present invention can also be used for other surface treatments using surface chemical reactions (eg, surface modifications such as deposition, oxidation, nitridation, etc.).

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIG. The embodiment is comprised of a hot molecular beam generating means 15 installed in a vacuum chamber 1, a reaction grid supplying means 16°, and a sample 3 placed on a sample stage 2. The hot molecular beam generating means 15 is composed of a valve 4 for supplying gas for forming a beam, a heating furnace 5 for heating the gas, a heating heater 6, and a heating power source 7.

The brim 8 prevents contaminants from the heater 6 from flying onto the sample surface. Gas molecules M introduced through the valve 4 are heated in the heating furnace 5.

A beam (M beam) of -C1 vibrationally excited molecules is formed by extruding into a vacuum through the jet port 9. Here, the beam refers to a flow of particles having an anisotropic velocity distribution, and the spout 9 is not necessarily required, and an opening having the same diameter as the inner diameter of the heating furnace 5 may be sufficient. The reactive particle supply means 16 includes a valve 10. for supplying reactive particles (P). Gas reservoir 11. and a spout 12.

The reactive particle (P) gas introduced via valve 1o is
Once it becomes a uniform flow in the gas reservoir 11, it is ejected into the vacuum from the ejection port 12 and becomes a beam of reaction particles. However, one reaction particle does not necessarily need to be supplied to the sample surface as a beam, and may be supplied as an atmospheric gas near the sample 3 having a uniform velocity distribution. Sample 3 is placed on sample stage 2.

A temperature control means 13 is provided to control the sample temperature as necessary. Further, by driving the sample stage 2 and the sample 3, it is possible to surface-treat a large-area sample with good uniformity.

The following is a case where COz is used as the molecule M forming the hot molecule, F2 is used as the reaction particle P, and the S i axis (single crystal, polycrystal, or amorphous) is used as the sample (substance to be etched).

Explain the mechanism of etching. When Fz enters the Si surface, it combines with the dangling bonds of Si to form S i F2. That is, the following reaction is performed: Fz+Si (surface)→5iFz (surface). When 2 molecules of Hola 800 (coz"") are incident in this state, 2SiFz (surface) +COz -+S I F'a due to the vibrational energy of one molecule
(Surface)+Fz(Surface)+COx...■ The following reaction is promoted. The reaction product SIF4
In the 0-line method, in which etching progresses by desorption (evaporation) from one surface, COz r becomes S
When reflected from the i surface, C loses its vibrational energy and returns to its ground state, becoming a CO2 molecule.

There is no possibility of etching of the pattern sidewalls by reflected COz, and vertical etching by the COz'' beam can be performed.However, in this case.

Therefore, the direction of incidence of the COx beam on the surface.

It is necessary to make the direction of the perpendicular line of the furnace nozzle 9 perpendicular to the sample surface. This situation is shown in FIG.

The larger the gas flow rate of COZ, the more process treatment becomes possible.
From the relationship with the exhaust system, 0.1 to 101005e is practical. The appropriate temperature in the furnace is 800°C to 1500°C, and the gas pressure in the furnace is 0.1 to 10 Torr.

Further, the appropriate diameter of the jet 09 is O11 to 10-. The furnace material must have heat resistance and corrosion resistance, and quartz or alumina is suitable. The flow rate of F2 is also determined by the exhaust capacity, and is practically 0.1 to 100 seconds.

The reason for using C02 as the molecule M is that it has a strong bonding force between the atoms constituting the molecule, does not easily decompose even when heated to high temperatures, and is chemically stable.

In addition to COz, CFa, SFe, 5iFa, etc.
It can be used as On the other hand, reactive particles P and F
2 was used because it does not etch Si by itself and the surface fIEM is capacitively etched in the presence of a hot molecular beam.
This is because F radicals are formed and Si is etched. In addition to F2, CQzr NFs+ CnF+++
*XeFz etc. can also be used as the reactive particles P. Moreover, regarding the sample, not only Si but also −M ov
Similar etching can be performed on metals such as W g 'ra t Co v N' b and these silicides by appropriately selecting the molecules M and the reactive particles P.

Furthermore, as shown in FIG. 1, the following effects can be obtained by controlling the opening and closing of the gas introduction valves 4 and 10 in accordance with a predetermined program using the valve opening/closing controller 14. In other words, since gas can be supplied to the sample surface intermittently, the same pumping capacity can be used for instant rlI! It is possible to inject a large amount of gas onto the surface. In addition, since the gas M and the reactive particles P can be introduced alternately,
By performing reactions (1) and (2) alternately, it is possible to perform etching with higher precision.

The present invention has been described above in the case of etching, but
The present invention can also be used for deposition1
For example, if COx is used as the gas molecule M and 5iHa is used as the reactive particle P.

S i H4 is decomposed by the vibrational energy of hot Cot (Cox”), and S iHa + COz → Si (surface) + 2 Hz +
COx...■ 0 reaction product Si (surface) is deposited on the surface to perform the deposition of Si (amorphous, multicrystalline, single crystal).

In the embodiments shown in FIGS. 1 and 2, hot molecules (M'') are formed by furnace heating using a heater.

Other methods, such as infrared lasers and infrared lamps.

Hot molecules (M") can also be formed by heating the gas of molecules M by RF heating or the like.

FIG. 3 shows another embodiment of the invention. The differences from Fig. 1 are valve 10.10' and gas reservoir 11.11'.
For example, an oxide film can be deposited by the method of this embodiment, in which a plurality of reactive particle supply means 16, 16' each having a jet orifice 12, 12' are provided.

That is, COz is used as the gas molecule M, S f H4 is used as the reactive particle Pt, and 02 is used as the reactive particle Pz. As a result, following the reaction (■) above, Si (surface) +0
2→5ift (surface)...The reaction (■) occurs and an oxide film is formed on the surface. If Nz is used instead of Ox, a nitrogen film (SisN4) can be deposited.

〔Effect of the invention〕

According to the present invention, surface chemical reactions can be promoted without damaging the surface, so surface treatment optimal for semiconductor processing can be performed.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram showing one embodiment of the present invention, Fig. 2, Fig. 3
The figure is a configuration diagram showing another embodiment of the present invention. 1... Vacuum chamber, 2... Sample stage, 3... Sample, 4...
··valve.

Claims (1)

[Scope of Claims] 1. A method for surface treating a sample in vacuum, characterized in that the surface of the sample is irradiated with a plurality of types of particles, at least one of which is a hot molecular beam. 2. The surface treatment method according to claim 1, which comprises etching the surface of the sample. 3. The surface treatment method according to claim 2, wherein one of the particle beams is a hot molecular beam of CO_2. 4. Claim 3, characterized in that F_2 molecules are supplied to the surface of the sample as a beam or atmospheric gas.
Surface treatment method described in section.