JPH0536599A - Formation method of pattern - Google Patents

Abstract

PURPOSE:To enhance the dimensional accuracy and the dimensional controllability of the title method and to simplify the process of the title method by a method wherein a three-layer-structure resist which is composed of an upper layer, an intermediate layer and a lower layer is formed on a substrate, the intermediate layer is exposed, the image-reversed pattern is formed on the intermediate layer and a reactive ion etching operation is executed. CONSTITUTION:A three-layer-structure resist which is composed of a lower layer 2 by a photoresist, an intermediate layer 3 by a negative resist containing Si and an upper layer 4 by a negative resist is formed on a substrate 1 in this order. Then, the negative resist for the upper layer 4 is patterned by an ordinary light exposure operation and an ordinary developing operation; after that, the intermediate layer 3 which exposes the whole surface collectively is exposed by making use of an upper-layer pattern 4' as a mask. Then, the intermediate layer 3 is developed; the upper-layer pattern 4' is removed; the image-reversed pattern of the upper-layer pattern 4' is formed on the intermediate layer 3. After that, a reactive ion etching(RIE) operation by means of oxygen is executed to the whole surface by making use of an intermediate pattern 3' as a mask.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pattern forming method for manufacturing a semiconductor device.

[0002]

2. Description of the Related Art There is a great demand for miniaturization of semiconductor elements, and various studies have been made on a pattern forming method for achieving such miniaturization. The three-layer pattern forming method that has been widely used in the past is one of them, for example, literature, journal vacuum science technology; J.Vac.Sci.Technol.B, Vol.1.No.4.Oc.
t.Dec.1983, `` Multilayer resist technique for submi
cron opt-ical lithography "

The outline of this three-layer pattern forming method will be described below with reference to FIG. In FIG. 2a, reference numeral 10 is a substrate, which is manufactured by a spin coating method on the substrate 10 under the trade name of AZ-140.
5J (Hoechst) is used for hard baking at 200 to 250 ° C. for 30 minutes to make the lower photoresist layer 11 2.0.
It is formed to a thickness of μm. Then on top of it in the same way 0.15μ
Intermediate layer 1 with m-thick spin-on-glass layer (SOG layer)
No. 2 is formed, and 0.45 μm is formed by the same spin coating method.
Then, an upper layer resist 13 having a trade name of AZ-1450B (Hoechst) is formed.

First, the upper layer resist 13 is exposed to light and developed to form the upper layer pattern 1 as shown in FIG. 2b.
3'is formed. After that, the SOG layer of the intermediate layer 12 is patterned by dry etching with a CF ₄ -based reaction gas using the upper layer pattern 13 ′ as a mask to obtain an intermediate layer pattern 12 ′ (FIG. 2 c). Further, as shown in FIG. 2d, the lower layer resist 1 is formed by using the intermediate layer pattern 12 'as a mask.
1 is patterned by performing reactive ion etching (RIE) with oxygen to obtain a lower layer pattern 11 '.

[0005]

However, the following problems cannot be avoided by the pattern forming method using the three-layer resist as described above. That is, from the upper layer to the intermediate layer,
Also, since pattern transfer from the intermediate layer to the lower layer is performed by etching, dimensional shift easily occurs and dimensional controllability deteriorates. Further, since the intermediate layer is etched to transfer the pattern, a dedicated etching device is required, and further, the upper layer resist is required to have high dry etching resistance to withstand the etching of the intermediate layer, and moreover, the whole process is complicated and throughput is increased. The decline was unavoidable.

According to the present invention, the pattern transfer is repeated as in the conventional three-layer resist method described above to reduce the dimensional accuracy and the dimensional controllability, and further the pattern transfer by etching is repeated twice. It is an object of the present invention to provide a pattern forming method that solves the problem of complexity.

[0007]

According to the present invention, in a method for forming a fine pattern, a three-layer structure resist consisting of a lower layer of an object to be etched, an intermediate layer of a Si-containing negative resist, and an upper layer of a negative resist is formed on a substrate. The steps of forming in this order, the step of patterning the negative resist of the upper layer by ordinary photoexposure and development, and then the step of exposing the intermediate layer to the entire surface with the upper layer pattern as a mask, and developing the intermediate layer Thereby removing the upper layer pattern and forming an image reversal pattern of the upper layer pattern on the intermediate layer, and then using the intermediate layer pattern as a mask, reactive ion etching (R
IE) is included.

[0008]

According to the present invention, the above-mentioned steps are introduced in the pattern formation. Therefore, since the pattern transfer from the upper layer to the intermediate layer is performed by batch exposure with light, the characteristics of the upper layer resist are not necessarily high. without requiring resistance to dry etching, and is image reversal during full field exposure of the intermediate layer, will get an intermediate layer pattern obtained by inverting the upper pattern image, the pattern transfer due to etching of the underlying O ₂ RIE one Since it is performed only once, it has high throughput and high dimensional controllability.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. As shown in FIG. 1a, first, a lower layer 2 is formed on a base substrate 1.
As a photoresist, for example, a novolac photoresist is formed to a thickness of 1.0 μm by a spin coating method, and baking is performed at a high temperature, actually 200 to 250 ° C. or higher. Next, a negative Si-containing resist, such as polyallylsilsesquioxane (PACS), is similarly formed as the intermediate layer 3 on the lower layer 2 by the spin coating method to a thin thickness of 0.2 μm.

Next, a negative resist is formed as the upper layer 4 resist on the intermediate layer 3 by a spin coating method to a thickness of 0.5 μm. Next, as shown in FIG. 1b, the upper layer resist 4 is exposed to light and developed by a conventional method to obtain an upper layer pattern 4 '.

When a DUV light resist (trade name) SAL-601 (Shipley Company) is used as the upper layer resist, the exposure dose is about 100 mJ / cm ² .
A post exposure bake (PEB) of 120 ° C. for about 1 min is suitable. As the developing solution, the intermediate layer 3 which is the base
An organic alkali developing solution such as an aqueous solution of tetramethylammonium hydroxide (TMAH), which causes almost no damage to PACS, is suitable.

Next, the entire surface is collectively irradiated with ArF excimer laser light to collectively expose the PACS of the intermediate layer 3 by using the upper layer pattern 4'as a mask and develop the upper layer pattern 4 ', as shown in FIG. 1c. An intermediate layer pattern 3'having a positive / negative reversal with the image of FIG. A of this PACS
In the rF exposure, an exposure dose of about 200 mJ / cm ² is suitable, and spray development using dimethyl isobutyl ketone (DIBK) as a developing solution is suitable. Further, during the development, the above-mentioned upper layer pattern 4'is removed, and the underlayer of the upper layer pattern 4 ', that is, ArF
The portion not irradiated with the excimer laser light is dissolved and removed, and the intermediate layer pattern 3'is formed.

Then, as shown in FIG. 1d, the entire surface is O ₂ RIE.
By doing so, the intermediate layer pattern 3'can be used as a mask for O ₂ RIE to perform pattern transfer to the lower layer to obtain the lower layer pattern 2 '. In the above embodiment, the upper layer is DU
The case of exposing the V light and the intermediate layer with the ArF excimer laser light has been described, but the present invention is not necessarily limited to these. Further, in this embodiment, the novolac photoresist is used as the lower layer to be etched, but the present invention is not limited to this.

[0014]

As described above in detail, the present invention has three advantages.
In the layer resist method, after patterning the upper negative resist by ordinary light exposure and development, an exposure step of an intermediate layer in which the entire surface is collectively exposed using the upper layer pattern as a mask, and the upper layer is developed by developing the intermediate layer. The process includes removing the pattern and forming an image reversal pattern of the upper layer pattern on the intermediate layer, and then performing reactive ion etching (RIE) with oxygen on the entire surface using the intermediate layer pattern as a mask. Therefore, since the pattern transfer from the upper layer to the intermediate layer is performed by collective exposure with light, high dry etching resistance is not necessarily required as the characteristics of the upper layer resist, and the image is inverted when the intermediate layer is collectively exposed. Since the lower layer pattern that is the reverse of the image of the upper layer pattern is obtained and the pattern transfer by etching is performed only once in the lower layer O ₂ RIE, the above problems such as high through top and high dimensional controllability can be solved. ..

[Brief description of drawings]

FIG. 1 is a process drawing of an example of the present invention.

FIG. 2 is a process diagram of a conventional example.

[Explanation of symbols]

 1 substrate 2 lower layer 2'lower layer pattern 3 intermediate layer 3'intermediate layer pattern 4 upper layer 4'upper layer pattern

Claims (1)

Claim: What is claimed is: 1. A lower layer formed of an object to be etched on a substrate,
A step of forming a three-layer structure resist consisting of an intermediate layer of a Si-containing negative resist and an upper layer of a negative resist in this order; and after patterning the upper negative resist by ordinary light exposure and development, the upper layer pattern Exposing the entire surface with the mask as a mask, a step of removing the upper layer pattern by developing the intermediate layer and forming an image reversal pattern of the upper layer pattern on the intermediate layer, and then forming the intermediate layer pattern. A step of performing reactive ion etching (RIE) using oxygen on the object to be etched as a mask.