JPH02101461A - Material and method for forming fine pattern - Google Patents

Abstract

PURPOSE:To enable a fine exact pattern to be easily formed without causing charging up by preparing the fine pattern-forming material made of a mixture of a polymer to be polymerized or decomposed by irradiation with ionized beams and a conductive polymer. CONSTITUTION:The fine pattern-forming material to be used as an electron beam resist is prepared by mixing the conductive polymer with the polymer to be polymerized or decomposed by irradiation with ionized beams, thus permitting the obtained electron beam resist to have high conductivity, so to prevent charging up during exposure, and to form an exact fine resist pattern freed of butting errors and deviation from an alignment due to the charging up, and a multilayer resist to be easily formed without attaching an aluminum layer by using these conductive polymers for the upper layer of the multilayer resist.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a fine pattern forming material used when patterning and fabricating semiconductor elements and integrated circuits using a charged beam, and a fine pattern forming method using the same material. It is about the method.

2. Description of the Related Art Conventionally, in the manufacture of ICs, LSIs, etc., patterns have been formed by photolithography using ultraviolet rays. With the miniaturization of elements, higher NA of stepper lenses and the use of shorter wavelength light sources are being promoted, but this has the disadvantage that the depth of focus becomes shallower. In addition, electron beam lithography has come to be used as the pattern dimensions of LSI devices become finer and munici (Music ICs) are manufactured. A positive electron beam resist is indispensable for forming fine patterns by electron beam lithography. Among them, polymethyl methacrylate (PMM) is known to have the best resolution, but it has a drawback of low sensitivity. Therefore, in recent years, many reports have been made to improve the sensitivity of positive electron beam resists, such as polybutyl methacrylate,
Copolymer of methyl methacrylate and methacrylic acid, copolymer of methacrylic acid and acrylonitrile, copolymer of methyl methacrylate and isobutylene, polybutene-1-
Positive electron beam resists such as sulfone, polyisopropenyl ketone, and fluorine-containing polymethacrylate have been announced. All of these resists have electron-withdrawing groups in their side chains or easily decomposable bonds in their main chains, making it easy for the main chain to be cleaved by an electron beam. Although this is aimed at increasing sensitivity, it cannot be said that it satisfies both resolution and sensitivity.

In addition, in electron beam lithography, the poor dry etch resistance of the electron beam resist, the impact on pattern accuracy due to the proximity effect of forward scattering and back scattering of electrons, and the impact on pattern writing due to charge-up of exposure electrons. There are drawbacks such as. In order to overcome these drawbacks, a multilayer resist method in which the functions of the resist are divided into a photosensitive layer and a planarization layer is a very effective method. FIG. 3 is a diagram illustrating a multilayer resist process in electron beam lithography. To suppress the proximity effect, an organic film with a thickness of 2 to 3 μm is applied as the lower layer, and 8i is applied as the intermediate layer.
An inorganic film such as 02 or 5oG (spin-on glass) is applied, an electron beam resist is applied as the upper layer, and about 100 aluminum layers are evaporated on top of it to prevent charge-up. Figure 3a). After exposure, the aluminum layer is removed with an alkaline aqueous solution and then developed (Figure 3b)
.

Next, the intermediate layer is dry-etched using this resist pattern as a mask (Figure 3C), and then the lower layer is dry-etched using the intermediate layer as a mask (Figure 3D).
). By using the multilayer resist process as described above, fine patterns can be formed with a high aspect ratio.

However, a multilayer resist in which an aluminum layer is vapor-deposited requires a more complicated process and has problems such as contamination, so it cannot be said to be practical.

Problems to be Solved by the Invention As mentioned above, the multilayer resist process with an aluminum layer is an effective method, but there are problems such as complicated steps and aluminum contamination. Furthermore, a multilayer resist process in which the aluminum layer is removed has problems with charging and build-up. Charge-up is a phenomenon in which exposed electrons accumulate in the resist, intermediate layer, or lower layer, which is an insulator. This charge-up effect causes major problems in electron beam lithography, such as field batting and deterioration of alignment accuracy. Furthermore, this charge-up phenomenon is also observed in single-layer resists, leading to field batting and deterioration of alignment accuracy, just as with three-layer resists.

That is, in electron beam lithography, exposed electrons are scattered in the resist, but some of them stop in the resist, and charges accumulate in that region. It was thought that this accumulated charge would bend the electron beam, causing a deterioration in field batting and alignment accuracy.

In order to solve this phenomenon, the present inventors have completed a conductive electron beam resist and a fine pattern forming method using the same.

As a means to solve the problem, the present invention solves the above problem by using as an electron beam resist a mixture of a conductive polymer and a polymer material that polymerizes or decomposes when irradiated with a charged beam. The aim is to solve such problems. Since this electron beam resist exhibits high conductivity, it is possible to prevent charge amplification of electrons during exposure. This resist material consists of two phases: a photosensitive polymer that decomposes or polymerizes when exposed to a charged beam, and a conductive polymer that removes charges during exposure. It can be a line resist. The conductive polymer may also react with the electron beam, in which case the conductive polymer also acts as a dissolution inhibitor during development.

By using a silicon-containing conductive polymer as the conductive polymer, a silicon-containing conductive resist for a two-layer resist with high dry etch resistance can be obtained.

By using these conductive polymer materials as the upper resist layer of a multilayer resist, it is possible to easily form a multilayer resist without adding an aluminum layer, allowing accurate fine resist patterns without batting errors or misalignment due to charge-up. can be formed.

Effect of the Invention The present invention uses the above-described conductive electron beam resist and a resist process using the resist to easily form an accurate fine pattern that does not cause char-up. In particular, there is no need to evaporate an aluminum layer, there is no problem of contamination, the process can be simplified, and accurate fine patterns can be formed by preventing charge build-up due to electrons. Can be done. Therefore, by using the present invention, it is possible to effectively form accurate, high-resolution fine patterns.

Example (Example 1) After dissolving polymethyl methacrylate (PMM) 01f with a molecular weight of about 200,000 in methyl isobutyl ketone 10C, C, add polydibutylthiophene 0.1y with a molecular weight of about 100,000, Insoluble matter was filtered off to obtain a resist solution. This resist solution was dropped onto the semiconductor substrate at 200 O
By spin-coding at rpm and baking at 15'0°C for 30 minutes, a resist film with a thickness of 12 μm could be obtained. Next, the acceleration voltage was 20KV and the irradiation amount was 1. OX10
' After performing c/CXP electron beam exposure, development was performed with a mixture of methyl imbutyl ketone (MIBK) and isopropyl alcohol (IFum), resulting in an accurate positive type image with no field batting errors due to charge-up. I was able to obtain a resist pattern.

There was still almost no film loss in the last irradiated area.

(Example 2) After dissolving fluorine-containing polymethacrylate 01y with a molecular weight of about 100,000 in MIBKlocc, 0.1y of ladder-type dimethyl polysilane with a molecular weight of about 10,000 was added, and insoluble matter was filtered out to obtain a resist solution. . This resist solution was dropped onto the semiconductor substrate and spin coded at 200 rpm.
'C: After baking for 30 minutes, a resist film with a thickness of 12 μm was obtained. Next, acceleration voltage 20KV
, after electron beam exposure with a radiation dose of 10 x 10-6c/(Ga), an accurate positive resist pattern without field batting errors due to charge amplifiers could be obtained when development was performed with an IP person. Ta.

In addition, there was almost no film loss in the end irradiation area.

(Example 3) In Example 2, a resist film was formed by adding persila polyacetylene instead of ladder type dimethyl polysilane. Acceleration voltage of 20KV is applied to this resist film.
After performing electron beam exposure at a dose of 1×10-6 c/i, an accurate positive resist pattern without field batting errors due to charge-up was obtained when development was performed using an IP printer.

(Example 4) A fourth example of the present invention is shown in FIG. A polymeric organic film is coated as a lower layer film 2 on a semiconductor substrate 1, and heated at 220'C.
Bake for 20 minutes. On top of this, SOG was spin-coded as the intermediate layer 3 at 200°C.

Bake for 2o minutes. The mixture obtained in Example 1 was applied thereon as electron beam resist 4, and the temperature was increased to 150°C.
, Baking was performed for 20 minutes to form a resist film with a thickness of 0.6 μm. (Figure 1a) Next, the acceleration voltage is 20KV.
, an accurate fine resist pattern 4P was obtained when exposure was performed with an electron beam 5 at a dose of 1×1° C/af and development was performed using an IP film. (Fig. 1b) Since the conductivity was good, no field putting errors due to charge-up were observed. This resist pattern 4P″Ir:
? The intermediate layer 5OG3 was etched as a fabric.

(FIG. 1C) Then, the lower layer film 2 was etched using the intermediate layer as a mask, and an accurate and vertical fine resist pattern 2P could be obtained. (FIG. 1d) (Embodiment 6) A fifth embodiment of the present invention is shown in FIG. A polymeric organic film is coated as a lower layer film 12 on a semiconductor substrate 1, and heated at 220°C.
Bake for 20 minutes. On this, the mixture obtained in Example 2 was applied as an electron beam resist 13, and 15
Baking was performed at 0'C for 20 minutes to form a resist film with a thickness of 0.6 μm. (Figure 2a) Next, an electron beam of 1
4 and development using IP, an accurate fine resist pattern 713P was obtained. (Fig. 2b) Since the conductivity was good, no field putting errors due to charge-up were observed. Using this resist pattern 13P as a mask, the lower film 12 was etched, and an accurate and vertical fine resist pattern 12P could be obtained. (FIG. 2C) Note that the mixture obtained in Example 3 may be used as the electron beam resist 13.

DETAILED DESCRIPTION OF THE INVENTION According to the present invention, when a mixture of a polymer material and a conductive polymer that is polymerized or decomposed by charged beam irradiation is used as an electron beam resist, a resist pattern with high sensitivity and high resolution can be obtained. can be formed.

By using these resists, the influence of charge-up due to exposure electrons is eliminated, and field putting and alignment accuracy can be improved. Also,
By using a silicon-containing conductive polymer as a conductive polymer, it can be used as the upper layer resist of a two-layer resist, easily prevent charge-up, and form an accurate and vertical fine resist pattern. This can greatly contribute to the production of ultra-high density integrated circuits.

[Brief explanation of drawings]

FIG. 1 is a process sectional view of one embodiment of the present invention, FIG. 2 is a process sectional view of another embodiment, and FIG. 3 is a process sectional view of a conventional multilayer resist method. 1... Semiconductor substrate, 2... Lower layer film, 3
...Intermediate layer, 4...Electron beam resist. Name of agent: Patent attorney Shigetaka Awano and one other name
lr! A foil drawing

Claims (4)

[Claims] (1) A fine pattern forming material comprising a mixture of a conductive polymer and a polymer substance that decomposes or polymerizes when irradiated with a charged beam. (2) A fine pattern forming material comprising a mixture of a polymer substance that decomposes or polymerizes when irradiated with a charged beam and a silicon-containing conductive polymer. (3) After applying an organic polymer film on the semiconductor substrate and heat-treating it, applying an inorganic film on the organic polymer film and heat-treating it, and applying a conductive polymer and a photosensitive polymer on the inorganic film. The method comprises a step of applying a mixture with a molecular substance as a resist film and heat-treating it, a step of drawing a pattern on the resist film and developing it, and a step of etching the inorganic film and the polymeric organic film using the resist pattern as a mask. A fine pattern forming method characterized by comprising: (4) A step of applying an organic polymer film on the semiconductor substrate and heat-treating it, and applying a mixture of a photosensitive polymer material and a silicon-containing conductive polymer as a resist film on the organic polymer film and heat-treating it. A method for forming a fine pattern, comprising: a step of drawing and developing a pattern on the resist film; and a step of etching a polymeric organic film using the resist pattern as a mask.