JPH0718012B2 - Surface selection treatment method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for selectively performing surface treatment, and more particularly to a surface treatment method in which light is used to enhance selection accuracy.

(Prior Art) In recent years, photo-excited process technologies such as CVD using light and etching have been actively developed to bring about lower temperatures and simplification of processes. However, all of the conventional photoexcitation process technology is based on the photochemical reaction between the reactive species on the substrate existing in the light irradiation section and the irradiation light, and therefore, the processing such as deposition, etching, and doping is performed on the light irradiation section on the substrate. The non-irradiated part was not processed. It is possible to realize the formation of a patterned thin film by a resistless one-time process by a photoexcitation process by patterning light irradiation to a substrate by utilizing this selectivity, for example, Japanese Patent Laid-Open No. The invention was proposed in Okabayashi described in 26445, and its usefulness is highly expected. However, such conventionally proposed photoexcitation process technology cannot necessarily replace all the practical resist processes for the following reasons.

(Problems to be Solved by the Invention) First, in the conventional resist process, the spatial selectivity of processing depending on the presence or absence of resist is very high.
In the photoexcitation process, especially photo-CVD, in addition to the photochemical reaction on the substrate surface, the photochemical reaction in the gas phase also contributes to the deposition, and therefore the deposition around the light irradiation part also occurs due to the accumulation from the gas phase and is selected. Sex deteriorates. For example, in the case of CVD of an insulating film using SiH ₄ , in addition to the above factors, the constituent molecules of the deposit are generated by the chemical reaction of a plurality of reactive species. Compared to the deposition by only the decomposition reaction of the reactive species, the deposition pattern further spreads from the irradiation light pattern to the average collision distance in the gas phase between the involved reactive species.

Further, in the conventional resist process, since the resist has a positive type and a negative type, the light irradiation pattern for resist exposure and the post-process, for example, the etching pattern, can be freely selected to be the same or complementary. However, the existing photoexcited process technology has a drawback in that only a so-called positive process technology in which only the light irradiation portion is processed is present, and thus the degree of freedom of the process is narrowed.

Therefore, an object of the present invention is to eliminate the drawbacks of the conventional photoexcitation process technology described above, to provide a surface selective treatment method having excellent selectivity and suppressing the induction of a photochemical reaction in a light irradiation portion.

(Means for Solving Problems) In order to solve the above-mentioned problems, a surface selective treatment method provided by the present invention is an atmosphere of a gas which is adsorbed on the surface of a substrate and treated on the surface by a surface chemical reaction. In this, by selectively irradiating a desired portion of the surface with light, at least one kind of adsorption reaction species involved in the surface chemical reaction is desorbed from the desired portion, and the adsorption reaction species is involved. It is characterized in that surface chemical reaction is suppressed at the desired portion.

(Operation / Principle of the Invention) The present invention has solved the problems of the prior art by adopting the above method. In the conventional photoexcitation process technology, by irradiating light to a reactive species such as a CVD material or an etchant present in a light irradiation portion on a substrate to cause a photochemical reaction,
The light irradiation area was selectively processed. On the other hand, in the present invention, by selectively desorbing the reactive species adsorbed on the substrate by light irradiation, the chemical reaction involving the adsorbed reactive species is suppressed only in the light-irradiated portion, and by extension, in that portion. Since the processing is stopped, the negative-type photoexcitation process technology, which has been difficult with the conventional photoexcitation process, becomes possible. Also,
In the conventional photoexcitation process, in many cases, the active species generated by the photochemical reaction in the gas phase are adsorbed on the substrate outside the light irradiation region. On the other hand, in the present invention, since the adsorbed species itself involved in the reaction is desorbed from the light irradiation portion on the substrate, the presence or absence of processing on the substrate faithfully reflects the presence or absence of light irradiation, and the selectivity is dramatically increased. .

The most widely known method for desorbing adsorbed species at once is to raise the substrate temperature, but desorption by light irradiation has also recently undergone basic studies, for example, the Surf Science Report (Surface). Science Repo
rts magazine, Volume 3 (p.1-p.105)
ANG) 's paper has a detailed explanation of the current situation. In the present invention, light irradiation that causes photodetachment is spatially and selectively performed, and surface chemical reactions due to adsorbed species are allowed to proceed in parallel except in the light irradiation section. As a result, the spatial selectivity is much improved compared to the conventional thin film pattern formation by the photoexcitation process, and the negative-type process, which was difficult with the conventional photoexcitation process, is possible and the process flexibility is greatly improved. To do.

Embodiment An embodiment of the method according to the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a surface treatment apparatus to which an embodiment of the present invention is applied.

The substrate 7 installed inside the reaction cell 6 having the window 5 for light incidence is exposed to the atmosphere of the reaction gas introduced from the gas supply system 9 through the valve 10. The substrate 7 is kept at an appropriate temperature so that the adsorbed species of the reaction gas can cause a desired surface reaction on the surface of the substrate 7. At this time, the substrate 7 is irradiated with the emitted light of the laser 1 which oscillates at a wavelength suitable for desorbing the adsorbed species through the reflecting mirror 2 and the lens 4. An image of the mask 3 having a desired irradiation pattern is formed on the surface of the substrate 7 by the lens 4 in order to perform selective irradiation.

FIG. 2 is a schematic view of a substrate portion when selective film formation is performed by the method of the embodiment using the apparatus of FIG. Adsorption of the reaction gas to the substrate is suppressed in the portion irradiated with the patterned irradiation light 20 in which the mask pattern is transferred to the substrate 7, and the deposited film 21 can be deposited on the unirradiated portion. The resolution of the edge portion of the deposited film 21 is much higher than that of the conventional method.

As a specific example, the case of forming a SiO ₂ film will be described in more detail. Tetra ethoxy silane (TEOS.Si (OC ₂ H ₅ ) ₄ ) is used as the reaction gas. SiO _{2 by} thermal CVD at about 750 ℃
It is well known that a film is formed in a batch. This reaction is a decomposition reaction in the gas phase and on the surface, and SiO ₂ is deposited. In this embodiment, this time, by irradiating by patterning the light of wave number of about 1070 cm ^-1 and about 800 cm ^-1 to resonantly excite a vibration state of Si and O, the light irradiation portion of SiO ₂ which once adsorbed And patterned Si that faithfully reflects the light irradiation pattern.
Form an O ₂ film.

Next, in the example of forming a Si film when SiH ₄ is used as a reaction gas, in a normal case, thermal CVD or plasma CVD at about 400 ° C.
Then, SiH and SiH ₂ radicals are generated and adsorbed on the substrate 7,
A Si film is formed through the hydrogen abstraction reaction. Further, in this embodiment, for example, the vibration absorption wave number of SiH is about 1970 cm.
^-1 by patterning and irradiating the resonance infrared light
H is desorbed from the irradiation region and SiH ₂ is also desorbed in the same manner to suppress film formation in the irradiation region.

On the other hand, an example in which the present invention is applied to etching instead of CVD will be described below. It is well known that the Si substrate can be etched by using the reaction gas SF ₆ , but since SF ₆ is desorbed from the substrate 7 by irradiating the vibration mode of light with a wave number of about 950 cm ⁻¹ , As in the case of CVD, etching progresses except the irradiated part. The state of the substrate 7 at this time is shown in FIG.

Furthermore, the embodiment of FIG. 1 can be applied to surface modification such as oxidation. It is well known that a good thermal oxide film can be formed by heating Si in an oxygen atmosphere. On the other hand, it is also known that O ₂ which is a reaction gas in this case is desorbed by light from a 185 nm mercury lamp, so it is necessary to pattern and irradiate the substrate with 185 nm light during the above thermal oxidation. As a result, it is possible to form a pattern in which oxidation of the light irradiation portion is suppressed.
This process can greatly shorten the process for forming polysilicon wiring.

If the above etching process and the CVD process are combined, it is natural that the portion removed by etching can be embedded with another CVD material.

An embodiment in which the present invention and the conventional photoexcitation process are used together to utilize both the negative process and the positive process will be described with reference to FIG. First, a deposition film 21 made of, for example, a metal is formed on the substrate 7 by direct CVD by mask pattern transfer by a conventional photoexcitation process. In this case, M ₀ (CO) ₆ may be used as the CVD material, and KrF excimer laser light with a mask pattern transferred may be used as the patterned irradiation light 20. Then, the present invention is applied to deposit another deposited film on the portion where the deposited film 21 is not present. At this time, it is highly necessary to flatten the film formation in a planar process of LSI or the like, and it is necessary to use an insulating film as the flattening deposited film 22 corresponding to the above-mentioned metal deposited film 21. In that case, the above-mentioned TEOS is used as the reaction gas, and the laser 1 is switched to a laser system capable of generating a difference frequency between the Nd: YAG laser light and the dye laser light, and the oscillation level of SiO ₂ is adjusted. About 1070 cm
⁻¹ or about 800 cm ⁻¹ light is applied to the substrate 7 through the same mask as that for metal deposition described above. Although some focus adjustment is required due to the chromatic aberration of the lens 4 due to the difference in the wavelength of the irradiation light between metal deposition and insulating deposition, two processes can be performed by switching the reaction gas and the light source with almost the same optical system. Benefits are born. Of course, if the patterned irradiation light used in the two subsequent processes can be used at the same wavelength, it is of course possible to proceed with the process without any mechanical adjustment simply by switching the reaction gas.

Although the embodiments of the present invention have been described in detail with respect to some cases and the advantages of the present invention have been clarified, the present invention is not limited to the above embodiments, and modifications can be made without departing from the spirit of the present invention. Needless to say.

For example, in the above examples, the case where only one kind of patterned irradiation light was used was shown, but other lights can be collectively irradiated as needed, and a plurality of lights can be simultaneously transferred through the same mask. Needless to say, it is used. Further, in the examples, as the light for photodesorption, the case of using infrared light that vibratically excites the adsorbed species was described, but the photoexcitation desorption of the present invention can also be performed by electronic excitation. Needless to say, correspondingly, it is obvious that ultraviolet light or vacuum ultraviolet light can be used.

(Effects of the Invention) As described in detail above, according to the present invention, it is possible to provide a surface selective treatment method having excellent selectivity and suppressing the induction of a photochemical reaction in a light irradiation part.

[Brief description of drawings]

FIG. 1 is a block diagram of a surface treatment apparatus to which an embodiment of the present invention is applied, FIG. 2 is a cross-sectional view of a substrate which is surface-treated by an embodiment to which the present invention is applied to film formation, and FIG. FIG. 4 is a cross-sectional view of a substrate which is surface-treated according to an embodiment in which the invention is applied to etching. It is sectional drawing of the board | substrate which formed the film flatly. 1 ... Laser, 2 ... Reflector, 3 ... Mask, 4 ... Lens, 5
... window, 6 ... reaction cell, 7 ... substrate, 9 ... gas supply system, 10 ...
Valve, 20 ... patterned irradiation light, 21 ... deposited film, 22 ... flattened deposited film.

 ─────────────────────────────────────────────────── --- Continued from the front page (56) References JP-A-56-108880 (JP, A) JP-A-52-70991 (JP, A) JP-A-52-127765 (JP, A) JP-A-55- 141568 (JP, A) JP 59-129773 (JP, A) JP 59-129774 (JP, A)

Claims (1)

[Claims] 1. Participation in the surface chemical reaction by selectively irradiating a desired part of the surface with light in an atmosphere of a gas which is adsorbed on the surface of the substrate and treats the surface by a surface chemical reaction. The surface selective treatment method, wherein at least one kind of adsorption reaction species to be desorbed is desorbed from the desired portion to suppress the surface chemical reaction involving the adsorption reaction species in the desired portion.