JPH0350719A - Formation of fine pattern - Google Patents

Abstract

PURPOSE:To form a more fine slit and a hole like pattern by removing selectively an inclined part on the sidewall of an upper resist pattern or a lower resist film directly below an overexposed dot like pattern part by reactive ion etching in a two-layer resist process. CONSTITUTION:A lower resist film 2 is formed on a semiconductor substrate 1 and an upper resist film 3 is formed on the above resist film and then, they are exposed by irradiating them with light 4 through a mask. Further, they are developed to form a positive type pattern 5 and a sputtering inorganic film 6 consisting of a silicon oxide is deposited and formed. Subsequently, the sputtering inorganic film 6 only at the inclined part of the resist pattern 5 is removed completely by reactive ion etching to expose the surface of a resist material and then, the resist pattern other than an exposed surface is covered with sputtering inorganic film 7 that is left selectively. After that, the resist pattern 5 and the lower resist film 2 are dry-etched by using a reactive ion etching device.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method of forming fine patterns on various semiconductor substrates in the production of semiconductor integrated circuits, and particularly relates to a method of forming fine patterns on various semiconductor substrates having steps. .

[Conventional technology]

Conventionally, as a method for forming fine patterns, in addition to using high-resolution exposure equipment and resists, the multilayer resist method is generally known. The present invention also belongs to the method called the multilayer resist method, and is the most A close example is J.
EIectrochem, Soc.

198g, VOl, 135N[Lll, 5pin-On-Glass Image described in P286
There is a Reversal (SOG I R) method.

[Problem to be solved by the invention]

The above-mentioned conventional multilayer resist methods, such as the three-layer resist method and PCM (Portable Conformable
Two-layer resist method called e Mask) and 5OGI
With the R method, it is possible to form a pattern on a stepped substrate while maintaining the same resolution as when forming a pattern on a flat substrate using a resist material used as an upper layer, but it is impossible to obtain higher resolution. It was possible.

In contrast to the conventional multilayer resist method described above, the present invention employs a two-layer resist method in which a positive resist is used as the upper layer resist, and a pattern whose pattern size has become smaller than the mask dimension due to overexposure is transferred to the lower layer resist. The difference is that only the sloped portion of the side wall of the resist pattern is used as a pattern to be transferred to the underlying resist.

[Means to solve the problem]

The method for forming a fine pattern of the present invention includes the steps of forming a first film made of an organic material on a semiconductor substrate directly or through a film of a material different from the substrate, and forming a first film made of an organic material on the first film with a sensitive resin. a step of exposing the second film to light through a mask; and a step of exposing the second film to light through a mask.
A step of developing the film with a developer to form a pattern, and developing a third film made of an inorganic material on the pattern made of the second film.
a step of completely removing only a portion of the third coating; and a step of completely removing only a portion of the third coating, and using the selectively left third coating as a mask using an active ion etching device consisting of parallel plates. and dry etching the first and second coatings.

〔Example〕

FIGS. 1(a) to 1(e) are schematic diagrams showing the method of forming a fine slit pattern according to the first embodiment of the present invention in the order of steps.

In FIG. 1(a), a positive photoresist, such as 0FPR800 manufactured by Tokyo Ohka Co., Ltd., is coated on a semiconductor substrate 1, and then heat-treated in a clean oven at 250° for 60 minutes to form a 2.0 μm thick film. Lower resist film 2
A positive photoresist, such as TSMR8900 manufactured by Tokyo Ohka Co., Ltd., is applied thereon to a thickness of 0.8 μm to form an upper resist film 3.
This figure shows the state of exposure with irradiation light 4 of λ=436 nm).

Thereafter, development was carried out for 60 seconds using a suitable developer, such as NMD-3 manufactured by Tokyo Ohka Co., Ltd., to form a positive resist pattern 5, as shown in FIG. 1(b).

FIG. 1C shows a state in which a film made of silicon oxide, ie, a sputtered inorganic film 6, is deposited to a thickness of 0.3 μm by sputtering.

Next, etchback is performed by active ion etching using CHF and 02 gas to completely remove the sputtered inorganic film 6 made of silicon oxide from only the inclined portions of the resist pattern 5 and expose the surface of the resist material.
Areas other than the exposed surface are covered with a selectively left sputtered inorganic film 7. This state is illustrated in FIG. 1(d).

Thereafter, the resist pattern 5 and the lower resist film 2 are etched using the selectively left sputtered inorganic film 7 as a mask using 02 gas or an active ion etching device.
Dry etching.

Through the above process, a fine slit pattern that cannot be obtained with a normal multilayer resist method can be obtained. This situation is shown in Figure 1(e).
Shown below.

FIGS. 2(a) to 2(e) are schematic diagrams showing a method for forming a fine hole pattern according to a second embodiment of the present invention in order of steps.

FIG. 2(a) shows a semiconductor substrate 1 having a step of 1.0 μm.
A lower resist film 2 having a film thickness of 2.0 μm is formed on top as in the first example.

Next, a high-resolution positive photoresist that gives a rectangular shape;
For example, TSMR-V3 manufactured by Tokyo Ohka Co., Ltd. is applied to a thickness of 1.0 μm to form an upper resist film 3, and the state is exposed to irradiation light 4 of ultraviolet g-rays through a mask as shown in FIG. 2(b). It was shown to.

Po5t Exposure Bake (P, E
, B) directly on a hot plate at 120°C.
, for 60 seconds, and then developed for 60 seconds using an organic alkaline developer such as NMD-3 manufactured by Tokyo Ohka Co., Ltd. to obtain resist pattern 5. This situation is shown in FIG. 2(C).

FIG. 3 is a plan view of FIG. 2(c). As shown in FIG. 3, the resist pattern 5 in FIG. 2(C) is a dot-like pattern and has a diameter of 0.4 μm. Such a fine dot-like pattern was obtained by overexposing a pattern of approximately 0.6 μm on a mask using a G-line stepper equipped with a lens having a numerical aperture of 0.5 or more.

Next, a 5i02-based coating film 8, for example, 0CDT manufactured by Tokyo Ohka Co., Ltd.
FIG. 2(d) shows a case in which YPE2 was applied to a film thickness of 0.3 μm and heat treated on a hot plate at 110° C. for 5 minutes.

Figure 2 shows a state in which a fine hole-like pattern is obtained by dry etching the resist pattern 5 and the lower resist film 2 using the SiO□-based coating film 8 as a mask using 0□ gas or active ion etching. (e).

Note that far ultraviolet light, electron beams, X-rays, etc. can also be used as the irradiation light 4 for exposure.

〔Effect of the invention〕

As explained above, in the two-layer resist method, the present invention selectively removes the inclined portion of the side wall of the upper resist pattern or the lower resist film directly under the overexposed dot-shaped pattern portion by reactive ion etching. Compared to patterns obtained with conventional multilayer resists, it has the effect of forming finer slit and hole-like patterns.

[Brief explanation of drawings]

FIGS. 1(a) to (e) are schematic diagrams showing the first embodiment of the present invention in the order of steps, and FIGS. 2(a) to (e) are schematic diagrams showing the second embodiment of the present invention.
Fig. 3 is a schematic diagram showing the example in the process order, and Fig. 2 (c
) is a plan view of DESCRIPTION OF SYMBOLS 1... Semiconductor base, 2... Lower resist coating, 3...
... Upper resist film, 4... Irradiation light, 5... Resist pattern, 6... Sputtered inorganic film, 7... Sputtered inorganic film selectively left, 8... 5i02-based coating film .

Claims (1)

[Claims] forming a first film made of a resist material on the semiconductor substrate; and forming a second film made of a resist material on the first film.
a step of exposing this second film to light through a mask, a step of developing this second film with a developer, and a step of forming a third film made of an inorganic material on this second film. a step of forming a film, a step of removing this third film by a certain thickness, and a step of removing the third film selectively using the remaining third film as a mask using a reactive ion etching device consisting of parallel plates. A method for forming a fine pattern, comprising the step of dry etching a two-layer film consisting of a first and second film.