JPS62116786A - Selective surface treatment - Google Patents

Abstract

PURPOSE:To selectively suppress surface chemical reaction in a light irradiated part of a substrate by adsorbing a reaction seed by the chemical reaction of gas on the surface of the substrate and irradiating light thereto so that the adsorbed reaction seed is selectively desorbed from the desired part. CONSTITUTION:The substrate 7 installed in a reaction cell 6 is maintained at a prescribed temp.; further a suitable atmosphere of the gas introduced through a valve 10 from a gas supply source 9 is maintained in the cell 6. The reaction seed of the surface chemical reaction is thereby adsorbed onto the substrate 7 surface. The exit light from a laser 1 which oscillates at a suitable wavelength is passed through a window 5 provided to the cell 6 by a reflection mirror 2 and a lens 4 and is irradiated onto the substrate 7. The image of a mask 3 having a desired irradiation pattern is formed on the surface of the substrate 7 by a lens 4 in order to make selective irradiation. The reaction seed adsorbed on the substrate is selectively eliminated from the substrate by the irradiation of the light in the above-mentioned manner, by which the thin film pattern of a desired negative type is formed with high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for selectively performing surface treatment, and particularly to a surface treatment method that uses light to improve selection accuracy.

(Prior Art) In recent years, photoexcitation process techniques such as CVD and etching using light have been actively developed as a means of lowering the temperature and simplifying the process. However, all conventional photoexcitation process technologies are based on a photochemical reaction between the anti-reactive species on the substrate existing in the light irradiation area and the irradiation light. The non-irradiated areas were left unprocessed. By utilizing this selectivity and patterning the light irradiation onto the substrate, it is possible to form a patterned thin film in a single resistless process using a photoexcitation process. 26445, and its usefulness is highly anticipated. However, such conventionally proposed photoexcitation process techniques cannot necessarily replace all resist processes currently in use 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 extremely high, whereas in the optical excitation process, especially in the optical C'/D, In addition to the photochemical reaction on the substrate surface, the photochemical reaction in the gas phase also contributes to deposition, so that precipitation outside the light irradiation area and from the gas phase also causes bK-based deposition, deteriorating selectivity. For example, 5i
In the case of CVP of an insulating film using n4, in addition to the above factors, the constituent molecules of the deposit are generated by chemical reactions of multiple reactive species, so it is difficult to use a single reactive species such as metal or 81. Compared to the case where the deposition occurs only by decomposition reaction, the deposition pattern spreads further from the irradiation light pattern to the extent of the average collision distance in the gas phase between the participating reactive species.

In addition, in conventional resist processes, since there are positive and negative types of resist, it is possible to freely select whether the light irradiation pattern for resist exposure and the pattern for subsequent processes, such as etching, are the same or complementary. However, existing photoexcitation process techniques have the disadvantage that only positive type process techniques exist, in which only the light irradiated area is processed, and therefore the degree of freedom in the process is narrowed.

Therefore, an object of the present invention is to provide a surface selective treatment method that eliminates the drawbacks of the conventional photoexcitation process techniques described above, has excellent selectivity, and suppresses the induction of photochemical reactions in the light irradiated area.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the surface selective treatment method provided by the present invention uses a gas atmosphere that adsorbs to the surface of a substrate and processes the surface through a surface chemical reaction. By selectively irradiating a desired part of the surface with light, at least one type of adsorption reaction species involved in the surface chemical reaction is desorbed from the desired part, and the adsorption reaction species participating in the surface chemical reaction is desorbed from the desired part. It is characterized in that surface chemical reactions are inhibited at the desired portions.

(Operation/Principle of the Invention) The present invention has solved the problems of the prior art by employing the method described above. With conventional photoexcitation process technology, the light irradiation area is selectively processed by irradiating light onto reactive species such as C'I/D materials and etchants present in the light irradiation area on the substrate to cause a photochemical reaction. did. In contrast, in the present invention, by selectively desorbing reactive species adsorbed on the substrate by light irradiation, chemical reactions involving the adsorbed reactive species are inhibited only in the light irradiated area, and as a result, in that area Because the process of processing is stopped, negative light excitation process technology, which was difficult to use with conventional optical excitation processes, becomes possible. In addition, in many cases in conventional photoexcitation processes, active species generated by photochemical reactions in the gas phase are adsorbed on the same plate outside the light irradiation area, so processing extends outside the light irradiation area, reducing selectivity. In contrast, in the present invention, since the adsorbed species involved in the reaction are themselves desorbed from the light irradiated area on the substrate, the presence or absence of processing on the substrate faithfully reflects the presence or absence of light irradiation, resulting in a dramatic increase in selectivity. will increase.

The most widely known method for desorbing adsorbed species all at once is to increase the substrate temperature, but basic studies have recently been progressing on desorption by light irradiation. 5c
ience Reports), vol. 3 (p, 1-p.
Chang (T, J., 105).

CHUANG)'s paper provides a detailed explanation of the current situation. In the present invention, light irradiation that causes photodesorption is carried out spatially selectively, and surface chemical reactions by adsorbed species are allowed to proceed in parallel outside the light irradiation region. This significantly improves spatial selectivity compared to the formation of thin film patterns using conventional photoexcitation processes, and enables negative tone processing, which was difficult with conventional photoexcitation processes, greatly increasing the degree of freedom in the process. do.

(Example) Examples of the method according to the present invention will be described below with reference to the drawings. FIG. 3 is a configuration diagram of a surface treatment apparatus to which an embodiment of the present invention is applied.

A substrate 7 placed inside a reaction cell 6 having a window 5 for light incidence is exposed to an atmosphere of a reaction gas introduced from a gas supply system 9 through a valve 10 . The substrate 7 is maintained at an appropriate temperature so that reaction gas adsorption (slightly desired surface reaction occurs) on the surface of the substrate 70. At this time, this adsorption f
, l The emitted light of a laser 1 oscillating at a wavelength suitable for light desorption is irradiated onto a substrate 7 via a reflecting mirror 2 and a lens 4 .

In order to perform selective irradiation, an image of the mask 3 having the desired irradiation/cut pattern is focused onto the surface of the substrate 7 by a lens 4.

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

As a specific example, 810. The case of film formation will be described in more detail. Tetra ethoxy silane (TE01-81(OCgHs)a) is used as the reaction gas. 75
It is well known that an 8i0 film can be formed at once by thermal CVD at about 0°C. This reaction is a decomposition reaction in the gas phase and on the surface, and is 810. is precipitated. In this embodiment, at this time,
Approximately 1070 cr that excites 8i and 00 vibrational states resonantly
rr' or approximately 800cIIL-'' wave number is patterned and irradiated to cause the once adsorbed S10. to detach from the light irradiation area, forming a patterned S10 film that faithfully reflects the light irradiation pattern. .

In the example of forming a 81 film when SiH4 is used as a reaction gas, in normal cases, thermal CVD at about 400°C or plus-r CVD is used to form SIHJp 81) (tD radicals and damage the substrate. 7, and an S1 film is formed through a hydrogen abstraction reaction. In this example, SIH is further produced by patterning and irradiating resonant infrared light of approximately 1970i', which corresponds to the vibrational absorption wavenumber of 8iH. It is desorbed from the irradiated area, and 81H is also desorbed in the same way, thereby suppressing film formation in the irradiated area.

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 81 substrates are etched using reactive gas SF, but S
Since F, is detached from the substrate 7 by irradiating it with light of approximately 950 knee 10 waves, which is its vibration mode, etching proceeds except for the irradiated portion, as in the case of CvD. The state of the substrate 7 at this time is shown in FIG.

Furthermore, the embodiment shown in FIG. 1 can also be applied to surface modification such as oxidation. It is well known that a high quality thermal oxide film can be formed by heating Sl in an oxygen atmosphere. On the other hand, it is known that 0°, which is the reactive gas in this case, is desorbed by light from a L85 nm mercury lamp. By irradiating, a pattern can be formed in which oxidation of the light irradiated area is suppressed. This process can significantly shorten the process for forming polysilicon interconnects.

If the above etching process and CVD process are combined, it is natural that the etched portions can be filled with another CVD material.

An embodiment in which the present invention is combined with a conventional optical excitation process to utilize both a negative tone process and a positive tone process will be described with reference to FIG. 4'. First, a deposited film 21 made of, for example, metal is formed on the substrate 7 by direct CVD using mask pattern transfer using a conventional photoexcitation process. In this case, MO(co)s may be used as the CVD material, and KrF excimer laser light onto which a mask pattern has been transferred may be used as the patterning irradiation light 20. Next, by applying the present invention, another deposited film is deposited on the portion where the deposited film 2 is not present. At this time, in a planar process such as an LSI, it is highly necessary to flatten the deposited film, etc., and it is necessary to use an insulating film as the flattened deposited film 22 corresponding to the metal deposited film 21 described above. In that case, the T13:O8 shown in the example above is used as the reactant gas, and the laser 1 is switched to, for example, a laser system that can generate a difference frequency between the Nd:YAG laser beam and the dye laser beam. Approximately 1070 that resonates with the level
CrrL or approximately 800 cm 2 light is irradiated onto the substrate 7 through the same mask as used for metal deposition described above. Although slight focus adjustment is required due to lens 40 chromatic aberration due to the difference in the wavelength of the irradiated light for metal deposition and insulation deposition, the two processes can be performed using the same optical system by simply switching the reactant gas and light source. This creates an advantage. Of course, if the patterning radiation used in two subsequent processes can be of the same wavelength, the process can proceed without any mechanical adjustment simply by switching the reactant gas.

Above, the embodiments of the present invention have been described in detail in several cases, and the advantages of the present invention have been clarified.6 It is understood that the present invention is not limited to the above-mentioned embodiments, and can be modified without departing from the spirit of the present invention. Needless to say.

For example, although the above example shows the case where only one type of patterned irradiation light is used, it is also possible to irradiate the scales with other lights at once as needed, or to transfer multiple lights at the same time through the same mask. Needless to say, it is also used. Furthermore, in the embodiment, the case where infrared light that vibrationally excites the adsorbed species is used as the light for photodesorption is described, but the photoexcitation desorption of the present invention is also possible by electronic excitation. Needless to say, it is also obvious that ultraviolet light or vacuum ultraviolet light can be used accordingly.

(Effects of the Invention) As described in detail above, according to the present invention, a surface selective treatment method that has excellent selectivity and suppresses induction of photochemical reactions in the light irradiation area can be provided.

[Brief Description of the Drawings] Fig. 1 is a configuration diagram of a surface treatment apparatus to which an embodiment of the present invention is applied, and Fig. 2 is a substrate whose surface is subjected to surface treatment according to an embodiment to which the present invention is applied to film formation. FIG. 3 is a cross-sectional view of a substrate surface-treated by an embodiment in which the present invention is applied to etching, and FIG. 4 is a cross-sectional view of a substrate surface-treated by an embodiment in which the present invention is applied to etching. FIG. 2 is a cross-sectional view of a substrate on which two types of films are patterned and formed into flat films. 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. Agent Patent Attorney Shinsuke Honjo Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] By selectively irradiating light onto a desired portion of the surface in an atmosphere of a gas that adsorbs onto the surface of the substrate and processes the surface through a surface chemical reaction, at least one type of gas that participates in the surface chemical reaction is removed. 1. A surface selective treatment method, comprising: desorbing adsorbed reactive species from the desired area, and inhibiting a surface chemical reaction involving the adsorbed reactive species in the desired area.