JPS63318739A - Formation of fine pattern - Google Patents

Abstract

PURPOSE:To form the pattern of an organic resist film with high accuracy by suspending development under the state in which the organic resist film is left to all sections or one part when the organic resist film is developed and generating the normal pattern through low-temperature etching by plasma. CONSTITUTION:A thin-film 3 containing organic matter is shaped onto a substrate to be treated 1 or the substrate 1, to at least one part thereon at least one layer of a thin-film 2 is formed, and the specified section of the thin-film 3 containing organic matter is irradiated with beams or charged particle beams. The thin-film 3 containing organic matter is developed so that at least partial patterns 3' are left in the thickness direction of the thin-film 3 including organic matter through development using a solution or dry development. The patterns 3'' of the thin-film containing organic matter are shaped through dry etching by plasma, keeping the substrate at a low temperature of 0-180 deg.C. Said development is executed so that the thin film 3 including organic matter is left in the thickness direction of the film 3 extending over the whole surface of the thin-film 3 containing organic matter after development.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a photoresist film containing an organic substance (hereinafter referred to as
It is called an organic resist film. ) relates to a pattern forming method suitable for forming a fine mask pattern.

[Conventional technology]

Conventional patterning of organic resist films is described, for example, in "Semiconductor Lithography Technology", Sangyo Tosho, edited by Hiro Otori, published in July 1980, page 6.

Conventional photolithography technology uses light, charged particle beams such as X-rays, electron beams, or ion beams to irradiate predetermined areas of an organic resist film to create altered areas in the resist film, which are then removed into a solution. When a positive resist was used, the altered portions were completely removed, and when a negative resist was used, the unaltered portions were completely removed using a developing solution to form the necessary resist mask pattern.

In addition, recently, dry development using heat treatment has been used to
A method of developing by volatilizing a part of the resist film has also been attempted.

[Problem that the invention seeks to solve]

However, with the above-mentioned conventional technology, there are problems such as insufficient pattern precision of the resist film due to differences in developer components and development time during development, and undeveloped resist film remaining. was there.

An object of the present invention is to solve these conventional problems and provide a method for forming an organic resist film pattern with high precision.

[Means for solving the problem] The above-mentioned high-precision pattern formation is achieved by not completely removing the organic resist film during development, but leaving the organic resist film in all or part of the area. This is achieved by stopping development and then performing low temperature etching with plasma at 0 to -180°C to generate a normal pattern.

More specifically, on the substrate to be processed or.

A step of forming an organic resist film (a thin film containing organic matter) on a substrate on which at least one thin film is formed on at least a portion of the substrate, and irradiating a predetermined portion of the organic resist film with light or a charged particle beam. a step of developing the organic resist film using solution or dry development so that at least a part of the pattern remains in the thickness direction of the organic resist film;
While maintaining the substrate at a low temperature of ~-180°C, dry etching the substrate using plasma containing oxygen gas as a main component,
The method is characterized by comprising a step of forming a pattern of the organic resist film.

[Effect]

If the development of the organic resist film is stopped midway through the development, the organic resist film will have irregularities on one surface.

In this case, the depth of development is shallower than in the case of the conventional method in which development is performed up to the base film, so the pattern accuracy of the unevenness on one surface is significantly improved compared to the conventional method.

When this accurately formed organic resist film is etched at a low temperature of 0 DEG to -180 DEG C. using oxygen gas plasma, highly anisotropic etching can be achieved with no side etching and highly selective etching. That is, in low-temperature etching, there is almost no side etching, so the thickness of the highly precisely patterned unevenness is reduced only in the depth direction while maintaining the high precision.

In addition, when the recess reaches the base layer during development,
Furthermore, even if overetching is performed, dimensional accuracy is maintained.

The effect of forming a highly accurate pattern by cooling the substrate to a low temperature of 0 to −180° C. will be described.

In dry etching, high-energy particles such as ions and electrons and neutral particles such as radicals are simultaneously incident on a horizontal surface, while only neutral particles are incident on the sidewall. Material analysis has shown that high-energy particle irradiation creates a pseudo-high-temperature state on the very surface of a solid, which has the effect of greatly activating reactions between gas particles and radicals and surface electrons. .

On the other hand, in the sidewall, reactions between radicals and solids, gas molecules and solids occur on the temperature-controlled substrate.

Therefore, when the substrate is cooled to a low temperature below 0°C, the reaction on the sidewalls is suppressed, but on the horizontal surface, the reaction is not suppressed due to the temperature increase due to the incidence of high-energy particles, and etching occurs only in the depth direction. Anisotropic processing in which the process proceeds is achieved.

The upper limit of the above temperature range, 0° C., is the temperature at which the vapor pressure of co, co2, and H2O, which are reaction products of the organic resist film with oxygen plasma, becomes 10-'' Torr.

Under this vapor pressure, reactions on the side surfaces of the pattern of the organic resist film are suppressed, while reactions on the bottom surface are affected by the if? As the etching progresses, grooves perpendicular to the substrate can be formed and highly accurate patterns can be formed.

On the other hand, the lower limit of the above temperature range, -180° C., is the temperature at which the gas pressure of the oxygen plasma becomes the same as the vapor pressure of oxygen. In other words, when the temperature is lower than this, oxygen cannot remain in a gaseous state, and oxygen is selectively adsorbed to the low-temperature surface.
Due to the precipitation, plasma discharge cannot be maintained.

Therefore, by controlling the substrate temperature to 0 to −180° C., a highly accurate fine pattern can be formed.

〔Example〕

Example 1 FIGS. 1(a) to 1(c) are process cross-sectional views showing a method for forming a fine pattern according to a first example of the present invention.

First, as shown in FIG. 1(a), on a substrate 1 having a base layer 2 on its surface, a positive main chain cleavage type organic resist,
For example, PMMA (polymethyl methacrylate (Po
lya+athyl Methacrylate))
3 to a thickness of 1-.

Thereafter, dry development was carried out by heat treatment, and this development was stopped halfway to form a surface uneven resist pattern 3' with a remaining film ratio of 50% as shown in FIG.

Next, the sample in the state shown in FIG. 1(b) was placed in a parallel plate type plasma etching apparatus, and while the substrate temperature was maintained at a low temperature of -20 DEG C. or lower, reactive ion etching was performed using 02 plasma. In this example, the 02 gas pressure is 10 mTorr,
Under the condition that the input power is 500W.

If etching is performed while keeping the temperature below -20°C, a high-precision resist pattern 3 as shown in Figure 1(C) will be created in about 1 minute.
' was formed.

In this example, it was possible to resolve patterns up to 0.5-line and space. Further, even in cases where the underlying surface was extremely uneven, the present method could be applied by making the depth at which the development was stopped midway greater than the level difference in the unevenness of the underlying surface.

In the above embodiments, the resist was developed by dry development, but a development method using a solution may also be used. That is, once the concavo-convex pattern 3' of the organic resist film as shown in FIG. 1(b) is formed, the resist pattern as shown in FIG. 1(c) is faithfully formed by low-temperature etching using oxygen plasma. There is no deterioration in pattern accuracy due to resist swelling, etc.

In addition, in the above example, plasma excited by a gas containing o2 as a main component was used, but fluorine (F), chlorine (C
aZ), a gas containing bromine may be used.

Example 2 In the first example above, an example using a positive resist was shown, but a negative resist, such as MR (manufactured by Tokyo Ohka)
The present invention was effective even when using the above.

The other configurations are the same as those of the first embodiment. In this embodiment, a UV (ultra violet) hardening step in which the organic resist film is hardened by irradiating it with ultraviolet light is performed before the exposure of the organic resist film. Alternatively, a pattern with even higher precision could be formed by adding it later, or before and after.

In the present invention, 0.3. It was possible to realize a line-and-space pattern, and it was also possible to achieve higher precision by forming a thinner resist film.

Example 3 EB (electro beam) resist, for example, N
PR New Positive Resist (New Po5it)
The present invention was also effective when EB irradiation was performed using EB Re5ist)), ○EPR100 (manufactured by Tokyo Ohka), CMS (manufactured by Toyo Sorb), and then development was performed.

In the conventional method, when using such an EB resist,
In particular, when performing dry etching, etching resistance was a good thing, but as in the present invention, low temperature (e.g.
-40℃) improves etching resistance.
High precision pattern formation was possible.

Embodiment 4 FIGS. 2(a) to 2(d) are process cross-sectional views showing a method for forming a thin pattern according to another embodiment of the present invention.

First, as shown in FIG. 2(a), a positive electron beam resist, RE-5000P (manufactured by Hitachi Chemical), is coated on a substrate 1 to be processed with a coating thickness of 0.5. After forming an organic resist film 3 by applying the organic resist film 3 to a thickness of , a desired pattern was drawn by selectively irradiating the electron beam 5 to form a latent image 4. The acceleration energy of the electron beam was 30 kV, and the irradiation dose was (1 to 100) It was usable at 10-100 keV.

Next, as shown in FIG. 2(b), the m-ray resist 3 was statically developed for 10 seconds using a developer at 16 to 22°C to obtain a 0.
Asperities with a depth of 2p were formed.

Then, using a parallel plate type low temperature dry etching device,
Low-temperature reactive ion etching was performed at -110° C. and an O2 gas pressure of 100 mTorr. As a result, as shown in FIG. 2(c), the resist 3 is etched uniformly, and the convex portion of the resist film 3 corresponding to the step difference during development (shown in FIG. 2(b)) is etched onto the substrate 1. The remaining. That is, the processed substrate 1
An exposed portion and a non-exposed portion of the substrate were formed on top.

Using such a mask, the substrate 1 can be etched as shown in FIG. 2(d).

Note that the following two points are effective for etching the substrate 1.

First, before etching the substrate 1,
This method involves adding a step to remove the oxide film on the surface.

Due to the reactive ion etching of the O8 gas mentioned above, a thin oxide film remains in the exposed area of the substrate 1 as shown in FIG. It may be lost. In this oxide film removal process, removal using a solution, sputtering method, and dry etching method were effective.

When this oxide film removal process is performed, the uniformity of the etched thin film within the plane is ±10% compared to when this process is not performed.
This has been improved from ±5%.

The second point is that the substrate 1 is etched at a low temperature. As shown in FIG. 2(c), the thickness of the remaining resist film 3 is as thin as 0.2 #ll, so it is necessary to perform anisotropic etching under conditions with a high selectivity. Low-temperature reactive ion etching and low-temperature microwave plasma etching are excellent for this purpose. Si substrates and polycrystalline silicon have A
i is 0 to -20°C, W is -10 to -50°C
For Sin, SiN, which is best etched at 0 to -150°C.

In this example, as shown in FIG. 2(d), the selection ratio is set to 2.
It was possible to process the substrate 1 by etching with a value of 0 or more.

Although the embodiments of the present invention have been described above, it goes without saying that the present invention is not limited to the above-mentioned embodiments, and that various modifications may be made within the scope of the claims. [Effects of the Invention] As explained above, According to the method for forming a fine pattern of the present invention, high precision organic resist patterns can be obtained.

Since carbonization can be achieved, it is extremely effective in increasing the density of fine wiring, etc.

[Brief explanation of the drawing]

FIGS. 1(a) to (Q) are schematic process cross-sectional views showing an embodiment of the pattern forming method of the present invention, and FIGS. 2(a) to (d)
1 is a schematic process cross-sectional view showing another embodiment of the pattern forming method of the present invention. 1... Substrate 2... Base material 3... Resist film 3', 3'... Resist pattern 4... Latent image 5... Electron beam

Claims (1)

[Claims] 1. A step of forming an organic substance-containing thin film on a substrate to be processed or a substrate on which at least one thin film is formed on at least a portion of the substrate, and a predetermined portion of the organic substance-containing thin film. The organic matter-containing thin film is developed by irradiating the organic matter-containing thin film with light or a charged particle beam, and performing development using a solution or dry development so that at least a part of the pattern remains in the thickness direction of the organic matter-containing thin film. and a step of dry etching the substrate with plasma while holding the substrate at a low temperature of 0 to -180°C to form a pattern of the organic substance-containing thin film. . 2. The method for forming a fine pattern according to claim 1, wherein plasma excited by a gas containing oxygen as a main component is used as the plasma. 3. The method for forming a fine pattern according to claim 1, wherein the organic substance-containing thin film remains in the thickness direction of the film over the entire surface of the organic substance-containing thin film after the development step. 4. The method for forming a fine pattern according to claim 1, wherein the dry development and the low-temperature dry etching are performed in a continuous vacuum container.