JPS63160226A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To enhance the accuracy of a fine pattern by patterning it by a 3-layer resist method using a polystyrene film as a lower layer to improve the dry etching resistance of a 3-layer mask. CONSTITUTION:A polystyrene film 12 is formed as a lower layer on an aluminum silicon alloy film 11 coated on a substrate 10. Then, a silicon compound film 13 is formed as an intermediate layer, and a photosensitive novolac resist film 14 is formed as an upper layer thereon. The film 14 is exposed with a far ultraviolet ray to be patterned, and with the film 14 pattern as a mask the films 13, 12 are sequentially patterned to form a 3-layer mask pattern. Then, with the 3-layer mask pattern as a mask a substrate to be etched is patterned. Thus, the dry etching resistance of the 3-layer mask is improved to form an accurate fine pattern.

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] A mask pattern is formed consisting of three layers: a polystyrene film as a lower layer, a silicon compound film as an intermediate layer, and a photosensitive novolak-based film as an upper layer. The substrate to be etched is patterned using the three-layer mask pattern as a mask. This improves the etching ratio with respect to the substrate to be etched.

[Industrial Application Field] The present invention relates to a method for manufacturing a semiconductor device, and particularly to a patterning method.

One of the most important processes in the manufacturing method of semiconductor devices such as ICs is the so-called photo process, in which patterns are formed using photolithography. Advances in photoprocessing have greatly contributed to this.

For example, the higher the integration and density of an IC, the higher its performance, such as higher speed operation, and therefore, studies have been progressing toward further increasing the integration of ICs. However, if this is done, the unevenness of the surface becomes severe due to multilayer wiring, etc., creating steps, and a difficult problem arises in that fine patterns must be formed on the steps with high precision.

However, in order to achieve high integration of ICs, patterning on such steps is unavoidable, and it is required to form as fine and highly accurate patterns as possible on the uneven surface. There is.

[Problems to be solved by conventional technology and invention] Previously,
When a resist film pattern is formed on a stepped part, the thickness of the resist film (photosensitive resin film) differs between the concave part and the convex part, and when this is exposed and developed, the pattern width of the concave part and the convex part becomes different, etc. However, there was a problem in that highly accurate patterning was not possible. In other words, if both are exposed at the same time, the thicker resist film portions on the concave portions will be underexposed, and if this is developed, the width of the resist film pattern will become narrower, and the thinner resist film portions on the convex portions will become underexposed. becomes overexposed, and when developed, the width of the resist film pattern becomes wider.

FIGS. 2(a) and 2(b) are a plan view and a sectional view showing a negative resist film 2 formed on a substrate 1 to be etched with steps. Specifically, the pattern width is not constant due to the relationship between the exposure wavelength and the resist film thickness, but conceptually, as explained above, the width of the resist film pattern changes in proportion to its film thickness. be.

Therefore, a patterning method has been proposed in which two types of resist film patterns are formed in the portion where there is a step difference.

This is called a two-layer resist method, and FIG. 3 shows a diagram in which two layers, a non-photosensitive resin film 3 and a photosensitive resist film 4, are formed on a substrate 1 to be etched. First, a non-photosensitive resin film 3 is coated thickly until it is flat, and then a photosensitive resist film 4 is coated on top of it.First, the resist film 4 is exposed and developed using a photomask, and then Using the resist film pattern 4 as a mask, the underlying resin film 3 is patterned by dry etching with oxygen (02) gas. For example, the lower thick resin film 3 is made of a non-photosensitive novolak type resin film, and the upper resist film 4 is made of a photosensitive novolac type positive resist film.

However, in this two-layer resist method, the upper resist film pattern 4 is applied thinly to improve resolution.
In addition, there is a problem that the dry etching resistance is poor and the film cannot be held sufficiently until the underlying resin film pattern 3 is formed. Therefore, as an alternative method, recently
A 3N resist method (tri-level method) has been developed.

FIG. 4 shows a pattern formed on the substrate 1 to be etched using the three-layer resist method. For example, first, a non-photosensitive novolak resin film 3 is coated thickly until it becomes flat and solidified, a silicon compound film 5 is coated and solidified, and then a photosensitive novolak resin film 3 is coated on top of it and then a photosensitive novolak resin film 3 is coated and solidified until it becomes flat. A mold resist film 4 is applied and solidified. After the resist film 4 is exposed and developed using a photomask, the intermediate layer silicon compound film 5 is patterned by dry etching with fluorine (F) gas using the resist film pattern 4 as a mask. Next, the silicon compound film pattern 5
Using this as a mask, the lower novolac resin film 3 is dry-etched with oxygen gas, thus forming a three-layer pattern.

In this way, since the silicon compound film 5 has good dry etching resistance, the resin film pattern 3 can be patterned with high precision.Although the three-layer pattern is shown as is in FIG. 4, it is actually When the novolac resin film pattern 3 is formed, the upper resist film pattern 4 has disappeared.

By the way, this 37! When the aluminum film or aluminum alloy film of the substrate to be etched is etched using the resin film pattern formed by the resist method, the silicon compound film 5 in the intermediate layer is also thin and disappears. The pattern 3 must be maintained during etching of the substrate to be etched, but since the dry etching resistance of this novolac resin film pattern 3 is poor, the thin layer of the resin film pattern may be retained during etching of the substrate to be etched. There is a problem that it is not maintained and tends to disappear, making it impossible to pattern with high precision.

In addition, this three-layer resist method is applicable not only to substrates to be etched with steps, but also to substrates to be etched that are relatively flat, where the etching ratio between the photosensitive resist film and the substrate to be etched is not sufficiently large. This three-layer resist method is also applied to this method, and there are similar problems.

The present invention proposes a method of manufacturing a semiconductor device using a novel three-layer resist instead of the three-layer resist that has such problems.

[Means for solving the problem] The purpose is to form a polystyrene film as a lower layer, a silicon compound film as an intermediate layer, and a photosensitive novolac resist film as an upper layer, and then expose the novolac resist film to deep ultraviolet rays. and patterning the silicon compound film and the polystyrene film in sequence using the novolak resist film pattern as a mask,
This is achieved by a method of manufacturing a semiconductor device in which a mask pattern consisting of the three layers is formed and a substrate to be etched is patterned using the three layer mask pattern as a mask.

[In other words, the present invention uses a polystyrene film as the lower layer.]
It proposes patterning using the layered resist method.
This improves the dry etching resistance of the three-layer mask.

[Example code] Hereinafter, embodiments will be described in detail with reference to the drawings.

FIGS. 1(a) to 1(d+) show cross-sectional views in the order of the formation steps of the manufacturing method according to the present invention. First, as shown in FIG. A polystyrene film 12 (molecular weight 40,000 or less; non-photosensitive; film thickness at thick part of about 2 μm) is applied onto the film 11 until flattened, and baked at 120° C. for 30 minutes to solidify. Silicon compound film 1 as a layer
3 (thickness: 0.3 μm) and 200 μm in nitrogen gas.
℃ for 1 hour to solidify, and then
Photosensitive novolac positive resist film 14 as an upper layer
(A film thickness of about 0.4 μm) is coated and baked at 85° C. for 20 minutes to solidify.

This silicon compound film 13 includes, for example, PLO3 (polyladder organosiloxane), 0CD (trade name, PL
The novolak positive resist film 14 is made of TSMR-
8800 (product name) etc. is used.

Next, as shown in FIG. 1(b), a novolac-based positive resist film 14 is formed using a photomask (not shown).
is exposed to deep ultraviolet rays and developed with alkali to form a pattern, and then, using the novolac positive type resist film pattern 14 as a mask, the silicon compound film 13 is dry etched with fluorine gas for patterning.

Next, as shown in FIG. 1(C), using the silicon compound film pattern 13 as a mask, the polystyrene film 12 is
A pattern is formed by dry etching with oxygen gas. At that time, the upper thin novolak positive resist film 1
4 will disappear.

Next, as shown in FIG. 1(d), using the polyvinyl carbazole resin film 12 as a mask, the aluminum silicon alloy film 11 is dry etched using a chlorine-based reactive gas to form an aluminum wiring pattern.

At this time, the intermediate layer silicon compound film pattern 13 has disappeared.

If such a manufacturing method is adopted, the polystyrene film 12 has good dry etching resistance and the polystyrene film pattern is sufficiently retained, so that a highly accurate aluminum wiring pattern can be formed.

Although the above description has been made using examples for chlorine-based etching agents, it is equally effective for other types of etching agents.

[Effects of the Invention] As is clear from the above description, according to the present invention, a fine pattern with even higher precision can be formed using the 3N resist method, and it is possible to form fine patterns with higher precision, such as ■C, which is significantly useful for miniaturization of semiconductor devices. It is.

[Brief explanation of the drawing]

Figures 1 (al to d) are cross-sectional views in the order of steps of the manufacturing method according to the present invention, Figures 2 (a) and tb> are diagrams showing conventional lJi resist film patterns, and Figure 3 is a diagram showing conventional lJi resist film patterns. Figure 4 is a diagram showing a conventional three-layer resist method. In the figure, io is a semiconductor substrate, 11 is an aluminum silicon alloy film, 12 is a polystyrene film, 13 is a silicon compound film, and 14 is a diagram showing a layered resist method. Novolac-based resist film Sawa 1 also 4 force/ka 1 Koken Yukei 1r size Up/It hat heavy H day Figure 1

Claims (1)

[Claims] After forming a polystyrene film as a lower layer, a silicon compound film as an intermediate layer, and a photosensitive novolac resist film as an upper layer, the novolac resist film is patterned by exposing it to deep ultraviolet rays, and the novolac resist film pattern is masked. The silicon compound film and the polystyrene film are sequentially patterned to form a mask pattern consisting of the three layers, and the substrate to be etched is patterned using the three layer mask pattern as a mask. A method for manufacturing a featured semiconductor device.