JP2770620B2 - Thermal CVD method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to resist coating, exposure,
The present invention relates to a thermal CVD method capable of patterning with good spatial selectivity by using light without using a process such as resist stripping.

[0002]

2. Description of the Related Art It is widely known that photolithography such as resist coating, exposure, and development is used as a conventional method for patterning a CVD film or the like. To eliminate this complicated photolithography process,
Research on film formation by photochemical CVD that irradiates light in a space-selective manner has been conducted. This study is described, for example, by DJ Ehrlich et al., 969, Journal of Vacuum Science and Technology, J. Vac. Sic.
Details are described in the paper published on pages 984 to 984. However, the problem with this photochemical CVD method is that the types of high quality films that can be grown are limited. Therefore, research on photonucleation-based CVD, in which a thin film is first formed by a photochemical method and then thermal CVD is performed so that a high-quality thermal CVD film is grown only on the thin film formed first. It was conducted. For this, for example,
JYTsao et al., Appl. Phys. Lett., Volume 45 (198).
4) There is a paper published on pages 617 to 619. In this paper, using triisobutylaluminum as a raw material, nucleation patterning was performed directly on a quartz substrate by using the second harmonic of an argon ion laser, and then the nucleation was performed by thermal CVD using a CO ₂ laser. Only the CVD of the Al film is performed.

[0003]

In the above-described CVD method utilizing photonucleus formation, since a desired film-forming portion is drawn with focused ultraviolet light, there is a problem that patterning takes a long time and throughput is poor. In addition, there is a restriction on the type of light source. Nucleation by ultraviolet light irradiation is performed by photochemical decomposition of the adsorbed raw material gas molecules. This is performed by moving the electrons in the bonding orbital to the anti-bonding orbit by the valence electron excitation of the adsorbent, so that the initial state and the final state of photoexcitation are determined, and this energy Is limited to the use of light having a wavelength corresponding to
In addition, when vacuum ultraviolet light having a shorter wavelength is used, ionization of the adsorbent occurs, thereby decomposing the adsorbent. In this case, the energy of the light to be used is only required to be larger than the threshold energy of ionization, so that the wavelength restriction is relaxed as compared with the above method. However, ionization by valence electron excitation has a problem that adsorbent decomposition is still insufficient.

There is also a problem in patterning nucleation due to the diffraction effect of light. The light irradiation region is determined by the shape of the opening of the mask, and the sharpness of the edge shape of the CVD film after patterning is reduced by suppressing the light from flowing into the non-irradiated portion due to diffraction of light at the opening of the mask. It depends on. Since the magnitude of the wraparound is proportional to the wavelength of the light, the use of vacuum ultraviolet light having a short wavelength can suppress the wraparound of light due to diffraction. However, with the wavelengths used so far, the suppression of the diffraction effect is still insufficient.

An object of the present invention is to provide effective nucleation by promoting photochemical decomposition of an adsorbent in a light irradiation part, and
It is an object of the present invention to provide a thermal CVD method which allows a large selection range of a light source to be used and, at the same time, suppresses a light diffraction effect and has good spatial selectivity.

[0006]

According to the present invention, there is provided a method for spatially selective thermal CVD on the same kind of substrate, comprising the steps of:
Prior to the introduction of the VD material gas, among the atoms constituting the substrate, and a step of irradiating light that can excite the inner shell of at least one atom in the substrate, after the process is completed, CVD raw
To be irradiated on the substrate by thermal CVD by introducing a source gas
And the step of forming a film is performed in this order.

[0007]

[0008]

Further, it is possible to provide a thermal CVD method characterized by using dimethyl aluminum hydride (Al (CH ₃ ) ₂ H) as a CVD source gas.

[0010]

The operational feature of the present invention is that excitation or desorption of atoms constituting the substrate by inner shell excitation of at least one of the atoms constituting the substrate or the adsorbent, or decomposition / decomposition of the adsorbent. In promoting desorption.

First, the operation of the first invention of the present application will be described. Surface atoms become unstable multiply-charged ions due to cascaded Auger transition of inner shell holes formed by inner shell excitation of substrate constituent atoms by light, and desorption occurs due to Coulomb repulsion, atoms remaining on the surface A dangling bond is formed, and a chemically active surface is formed. Subsequent to the step of spatially selective surface activation by light irradiation, when the substrate is heated to a temperature at which thermal CVD occurs only in the activated portion and the source gas is supplied, the reaction proceeds only in this portion. Accordingly, thermal CVD can be performed spatially selectively.

If the wavelength of the light used is short enough to be able to excite the inner shell, the intensity of the diffracted light and the wraparound are about two orders of magnitude compared to the ultraviolet light that can be used to excite valence electrons. Since it becomes smaller, it can be activated only at the irradiation part by the light that goes straight, so that the CVD film can be patterned into a desired shape.

Further, when irradiated with light thermal CVD early, the raw material gas molecules adsorbed on the substrate, by a cascade manner Auger transitions inner shell holes formed in the inner core excitation, unstable multivalent ions吸音Ko Nuclei are formed by the decomposition and desorption of. Experimental results of Auger analysis by the present inventors, nuclei formed by photolysis of adsorption Al (CH _{3) 2} H molecules, as shown in FIG. 2 (a), that of Al and C, and, Al Was found to be active in a metallic state. Therefore, even if the light irradiation is stopped,
The thermal CVD reaction continuously proceeds only on this nucleus. That is, thermal CVD is selectively performed only in the portion where the nucleus is formed.
Becomes possible. Further, as described above, since the wavelength is short, the diffraction effect is small, and the CVD film can be patterned into a desired shape.

From the experimental results of Auger analysis by the present inventor, the SiO ₂ surface and the Al (C
It was found that the surface of SiO ₂ was reduced and modified into Si by the light-induced reaction of H ₃ ) ₂ H molecules. This is shown in FIG. 2 (a) and the clean SiO ₂ surface (b)
From the chemical shift of Auger electron energy of Si. Since Al-CVD from Al (CH ₃ ) ₂ H occurs on the Si surface at a lower temperature than on the SiO ₂ surface,
Thermal CV of Al only on the SiO ₂ surface modified to Si
D reaction can occur. Therefore, space-selective thermal CVD becomes possible.

[0015]

【Example】

(Embodiment 1) Hereinafter, the first invention of the present application will be described with reference to FIG. In this embodiment, Al (CH ₃ ) ₂ H
A case where an Al wiring for a Si device is formed on SiO ₂ by using as a raw material will be described.

SiO ₂ film 11 formed by thermal oxidation of Si
Is irradiated with synchrotron radiation (hereinafter referred to as SR) 13 spatially shaped by a mask 12. The wavelength of the SR is white light of a wavelength longer than 4 nm, SiO ₂ film 11
Is heated to 600 ° C. As shown in FIG.
Irradiation desorbs SiO _{2 from the} surface, and later forms a doughling bond region 14 where a doughling bond is formed.
Occurs. In this state, the raw material gas of Al (CH ₃ ) ₂ H
Is supplied, decomposition of Al (CH ₃ ) ₂ H occurs only in the doubling bond region 14 as shown in FIG.
The l film 15 grows.

[0017]

[0018]

[0019]

[0020]

In the above-described embodiment, the case where the SR is used as the light source has been described. However, a tube for generating various X-rays, or an X-ray from an X-ray laser or laser-produced plasma may be used.

[0022]

According to the present invention, resist coating, exposure,
A thermal CVD method capable of patterning with good spatial selectivity can be obtained without a process such as resist peeling.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing a wiring method by a thermal CVD method according to the first invention of the present application.

FIG. 2 is a view showing experimental results on which the operation of the present invention is based.

[Explanation of symbols]

11 SiO ₂ film 12 mask 13 synchrotron radiation 14 Doug ring bond regions 15 Al film

Continuation of the front page (56) References JP-A-63-478 (JP, A) JP-A-2-154421 (JP, A) JP-A-4-144135 (JP, A) The 36th Alliance of Applied Physics Proceedings of the Lectures 2nd volume, p.591 2p-L-4 (Spring 1989) Applied Physics Letters Vol. 55, No. 10, 4 September 1989 pp 1020-1021

Claims (2)

(57) [Claims] 1. Spatial selective heat C on the same type of substrate
In the VD method, prior to the introduction of the CVD source gas,
Irradiating the substrate with light capable of exciting the inner shell of at least one of the atoms constituting the substrate, and performing a thermal CVD by introducing a CVD raw material gas after the step.
A step of forming a film on an irradiated portion of the substrate in this order. 2. The thermal CVD method according to claim 1, wherein dimethyl aluminum hydride (Al (CH ₃ ) ₂ H) is used as a CVD source gas.