JPS6196725A - Photo chemical vapor deposition method - Google Patents

Abstract

PURPOSE:To extremely widen the selective range of applicable light source having no depositing effect on the inner wall of reaction chamber including photoirradiating window by a method wherein laser beams are focused on a reactive gas for irradiation in the two different directions while a multiple photon dissociating process to locally decompose the reactive gas is provided. CONSTITUTION:So-called dissociation due to multiple photons may be activated in the reactive gas near a point P on substrate whereon laser lights L1, L2 are focused to accelerate vapor re-action due to chemical decomposition locally depositing an aluminium conductive film. At this time, the reactive gas near the optical path of laser lights being hardly excited, the aluminium conductive film may not be deposited on the inner wall of reaction chamber 1 and the inner member surface of photo irradiating window 2 to prevent the throughput performance form deteriorating due to pollution. Besides, the reactive gas may be made atmospheric with no sensitizer added thereto at all since the laser lights may not be absorbed into the surface whereon they are not focused. A vapor growing film several mum-sub mum thick may be deposited by means of controlling the laser light focused region further easily forming an aluminium wiring pattern around 1mum wide if a laser light scanner is provided.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a photochemical vapor phase growth method using laser light. (Prior Art) The remarkable development of semiconductor integrated circuit devices today is due to the wide variety of thin film forming techniques. This is largely due to improvements in film quality and film quality. The thin films used in this field of semiconductor technology include insulating thin films such as gate insulating films, capacitive insulating films, element isolation insulating films, interlayer insulating films, and films for gate electrodes, ohmic electrodes, etc. For wiring and Shirotki i・
It can be broadly divided into conductive thin films for barrier purposes and the like.

CVD (Chemical Paper Deposition Mending) is a thin film forming technology that has developed rapidly in recent years. All the sources are introduced into the reaction chamber as a gas, and the desired thin film is produced by chemical reaction using so-called vapor phase growth. It is deposited in The CVD method can produce high-purity thin films at low temperatures, and the best choice for cutting materials is thin films of any composition, regardless of whether they are insulating or conductive. A major advantage is that it can be formed uniformly with high precision.

Conventionally, the mainstream CVD method has been the plasma CVD method, in which energy from discharge plasma has been used to decompose reactive gases. However, plasma contains electrons, ions, radiation, etc., and their collisions may cause damage to the formed film or the underlying substrate, so the photo-CVD method is attracting attention as an alternative. . In the photoCVD method, for example, a mercury vapor total sensitizer is added to the reaction gas, and a wavelength of 254
It is one of the CVD techniques in which all reactive gas molecules are chemically dissociated and activated by ultraviolet energy of nm or less. This thin film forming technique is covered by, for example, JP-A No. 56-96704, ``Optical vapor phase deposition method of oxide layer'', published in JP-A No. 54-163.
No. 792 ``Method for manufacturing silicon nitride film'' is detailed in each patent publication specification.

(Problems to be Solved by the Invention) However, there are other patent publications related to this optical CV'D, such as JP-A No. 56-35425 "Photochemical Vapor Phase Deposition Apparatus and Method" or JP-A No. 57-15
As disclosed in No. 4839 "Photochemical Vapor Deposition Apparatus and Method", this photo-CVD method involves the preparation of the inner wall surface of the light irradiation window and the inner wall surface of the reaction chamber as the gas phase reaction progresses. What is the so-called deposition effect phenomenon in which a gas-phase reaction film accumulates and contaminates the reaction chamber?In particular, the deposition effect at the light irradiation window decreases the total amount of ultraviolet irradiation into the reaction chamber as the deposited film thickness increases, and eventually Since the gas phase reaction is completely stopped, the throughput performance deteriorates completely.Also,
Generally, reactive gases have absorption wavelengths in the vacuum ultraviolet region, so the light sources that can cause the gas phase reaction to proceed completely are limited, and the range of selection thereof is extremely limited.

(Object of the Invention) For the purpose of the present invention, in view of the above circumstances, a light irradiation window? What is the optical vapor phase growth method that allows the deposition of a vapor phase reaction film on the inner wall surface of a reaction chamber without producing sound effects and which allows for extremely free selection of the light sources that can be used? It is to provide.

(Structure of the Invention) The optical vapor phase growth method of the present invention irradiates a reactive gas with condensed laser light from two or more different directions. A multiphoton dissociation process that causes local decomposition? include.

(Means for solving the problem At) In other words, if the present invention is applied, will a gas phase reaction be possible? Laser light is used instead of ultraviolet light as a light source for advancing. In this case, the dissociation activation phenomenon by multiphotons is utilized as a means for chemically decomposing the reactive gas.

To be more specific, what about vapor phase grown films? The surface of the substrate is locally and selectively focused and irradiated with laser beams projected from two or more different directions, and the reactive gas is locally multiphoton dissociated.

(At this point, only the reactive gas near the substrate is dissociated and activated by condensed irradiation of two or more laser beams to match the gas phase reaction conditions.

Laser light with a relatively short wavelength is used to combine silane (S1H4) and nitrous oxide (N20), which are used to form silicon oxide films.
), ammonia (
NH3), silane (8iHQ and hydrazine (N2
If the amount of light is weak, it will hardly be absorbed by reactive gases that are commonly used, such as a mixed gas of hydrogen or trimethyl aluminum gas for forming an aluminum conductor film.

Therefore, no reaction occurs in the vicinity of each optical path of the laser beams projected from two or more different directions, and the laser beams are concentrated in the local vicinity of the substrate such that they satisfy the gas phase reaction conditions and reach the light intensity. Only the reactive gases are dissociated and decomposed.

The present invention will be described in detail below with reference to all the drawings.

(Example) Fig. 1 shows an example of the formation of an all-aluminum conductor film according to the present invention. FIG. 2 is a cross-sectional structural diagram of the vapor phase growth apparatus shown in FIG. This embodiment consists of a reaction chamber 1 and a light irradiation window 2 that constitutes the entire upper surface of the reaction chamber 1.
A silicon substrate 5 on which a vapor-phase growth film is to be entirely deposited is placed in a reaction chamber, and a point P on the substrate is exposed to two laser beams Ll. ↓bi L2
is focused and irradiated from different directions. 1k and 6 are heating wires for heating the substrate, and numerals a and b are their power supply terminals. The reactive gas is trimethyl aluminum (A4(CH3
)3) is used, and is sent into the reaction chamber 1 through the inlet 3 and outlet 4. This reactive gas is a liquid with a low vapor pressure at room temperature, but it can be brought into the reaction chamber 1 by bubbling all of the hydrogen gas.Here,
The silicon substrate 5 is heated with a heating wire 6 if necessary,
The temperature is maintained at 300-400°C. At the stage where the above preparations are complete, the laser beams Ll and L2 are focused on a point P on the substrate. These laser beams have wavelengths that are almost absorbed by the reactive gas trimethyl aluminum [Al(CH3]) (for example, KrF...-248 nm,
eF...-3Q8nm) is used. At this stage, a so-called multiphoton dissociation activation phenomenon occurs in the reactive gas near the point P on the substrate where the laser beam LsL2 is focused, and a gas phase reaction due to chemical decomposition progresses, causing the aluminum conductive film to is deposited locally. At this time, since the reactive gas near the optical path 1 of the laser beam is hardly excited, there is no deposition effect on the inner wall surface of the reaction chamber 1 and the inner surface of the light irradiation window 2, and there is no through-gut performance due to contamination 1c. deterioration is prevented.

Furthermore, since absorption does not occur in areas where the laser beams do not overlap, the reactive gas can be kept at normal pressure, and of course there is no need to add a sensitizer. According to this embodiment, by controlling the entire overlapping area of laser beams, it is possible to
It is possible to deposit a vapor-phase growth film of about 1 μm in width, and if a laser beam scanning means is provided, it is also possible to easily form an aluminum wiring pattern with a width of about 1 μm. It is also suitable for forming fine conductive thin films such as gate electrodes, and can be formed extremely easily.

(Effects of the Invention) The vapor phase growth of aluminum conductor films has been explained above, but if laser light with a relatively short wavelength is used, it can be performed on almost all reactive gases. It is possible to uniformly form fine thin films of any composition with high accuracy regardless of their properties.

Moreover, since the entire interior of the vapor phase growth apparatus is hardly contaminated, the throughput performance will not deteriorate at all. Furthermore, the degree of freedom in selecting the light source is greater than in the past, and vacuum ultraviolet light L can be applied to the light irradiation window! Is it enough to completely transmit the long wavelength laser beam? Or is it normal pressure for the reactive gas? Since there are advantages such as ease of use, the vapor phase growth apparatus can also be easily constructed.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional structural diagram of a vapor phase growth apparatus showing a simple example of forming an aluminum conductor film according to the present invention.

Claims (1)

[Claims] A photovapor phase growth method comprising a multiphoton dissociation step in which a reactive gas is irradiated with focused laser light from two or more different directions to locally decompose the reactive gas.