JPS62113139A - Negative type resist composition - Google Patents

Abstract

PURPOSE:To prevent accumulation of electrostatic charge and to enable a micropattern to be formed without any slip of its position by partially converting polyvinylbenzyl chloride into quaternary ammonium, reacting it with lithium.tetracyanoquinodimethane (TCNQ) salt to partially form a salt type complex, and using the electrically conductive negative type resist composition thus obtained. CONSTITUTION:Polyvinylbenzyl chloride having a molecular weight of about 40,000, and a dispersion degree of 1.5 is dissolved in 1,4-dioxane, triethylamine is added, stirred with heating until the cloudy solution becomes transparent, and 60% of the chloromethyl groups of the polymer is converted into trimethylammonium groups. The ethanol solution of this polymer and a solution of lithium-TCNQ are mixed and stirred in a nirogen gas stream at room temperature to convert all the cation groups into the TCNQ salt complex. A silicon substrate is coated by the spin coating method with a cyclohexanone solution of this negative type resist material thus prepared, and then it is baked.

Description

[Detailed Description of the Invention] [Summary] Polyvinylbenzyl chloride, which is a negative type resist, is partially treated with polyvinylbenzyltriethylammonium.
A resist that has electrical conductivity by forming a tetracyanoquinodimethane complex.

[Industrial application field]

The present invention relates to a negative resist composition having electrical conductivity.

Semiconductor devices, which are the mainstay of information processing equipment as a means of processing large amounts of information at high speed, are increasing in capacity due to high integration, and VLSI, which has a much larger capacity than LSI,
has been put into practical use.

Here, high integration is achieved by miniaturizing unit elements, and the minimum pattern width is reduced to 1 μm or less.

Here, photolithography (photolithography or electron beam lithography) is used to form the fine pattern.

That is, physical methods such as vacuum evaporation method and spunter method, and chemical vapor deposition method (Che+5ical vapor deposition method) are used.
A thin film of metal or insulator is formed on the substrate to be processed using a chemical method such as CVO method (abbreviated as CVO method), and after coating this with resist, selective exposure is performed by irradiating ultraviolet rays through a patterned mask. When using a positive resist, the light irradiated area becomes soluble in the developer, while when using a negative resist, the light irradiated area becomes insoluble to create a resist pattern, which is then subjected to chemical etching or reaction. Fine patterns are created by performing dry etching such as ion etching.

However, in the pattern forming method using ultraviolet light exposure, the formation of fine patterns is limited to lines with a line width of 1 μm or more due to wavelength limitations, and it is difficult to form fine patterns with a line width smaller than this.

On the other hand, the wavelength of an electron beam varies depending on the accelerating voltage, but it is about 0.1 μm, which is more than 4 orders of magnitude shorter than the wavelength of light, so it can be expected to have great resolution, and it is also possible to form patterns with a width of 0.1 μm. Become.

Therefore, electron beam exposure is used instead of conventional ultraviolet exposure to form fine patterns.

However, when electron beam exposure is performed, since electrons have a negative charge, charge is accumulated on the surface of the resist, which causes a problem in that the position of the pattern is shifted.

[Conventional technology]

As mentioned earlier, since the electron beam has a short wavelength, it is possible to draw resist patterns of 1 μm or less, and since the electron beam can be scanned and drawn directly, there is no need for a mask, which reduces the mask manufacturing time and optics. Cost reduction is achieved along with the elimination of physical defects.

However, on the other hand, since electrons have a negative charge, charges are accumulated in the electron beam scanning section (hereinafter simply referred to as the exposure section), and this accumulated charge bleeds, causing a pattern misalignment.

This misalignment is caused by the pattern width and spacing being
This is not a problem in the case of m units, but it is a problem in the case of so-called sub-micron patterns of 1 μm or less.

However, no effective measures have been taken to date to deal with this problem.

[Problem that the invention seeks to solve]

As described above, when performing electron beam exposure, charge is accumulated in the exposed portion, and the problem is how to solve the positional shift caused by this bleeding.

[Means for solving problems]

The above problem can be solved by using a conductive negative resist composition in which polyvinylbenzyl chloride is partially converted into quaternary ammonium and partially converted into a salt-type complex by reacting with lithium tetracyanoquinodimethane salt. can.

[Effect]

In the present invention, the conductivity of a salt-type complex formed by reacting a polymeric polycation with tetracyanoquinodimethane (abbreviated as TCNQ) is 10''9 to 10''S-cm-', and the conductivity of various resist materials is Rate is 1O-IS ~ 10-”S-c
This was done by focusing on the fact that it exhibits significantly higher conductivity than that of m-'.

As a method for lowering the resistance of a resist, the present invention partially replaces the polymers constituting the resist with polymeric polycations.
By forming a TCNQ salt type complex, conductivity is imparted to the resist.

In this case, the degree of partial W exchange is limited to a range that does not impair the photosensitivity of the resist, and the conductivity of the resist synthesized by the method of the present invention is 10-12 to IQ-155-em-'
becomes.

〔Example〕

Polyvinylbenzyl chloride (molecular weight: 4 x 104,
5g of dispersion degree 71.5) was added to 100m of 1,4-dioxane.
1, add 1.5 g of triethylamine, and heat at 80°C.
The mixture was heated for 2 hours and stirred until the cloudy solution became clear.

In this way, 60% of the chloromethyl groups of the polymer were partially converted into triethylammonium.

0.02 mol/! of such polymer! Ethanol solution and 0.
The 04 morph N lithium (Li).TCNQ solutions were mixed and stirred for 1 hour at room temperature under a nitrogen (N2) stream to convert all the cationic moieties into TCNQ salt complexes.

The negative resist material thus synthesized was made into a 20% by weight cyclohexanone solution, spin-coded onto a silicon (Si) substrate, and then baked at 80° C. for 30 minutes.

This substrate was set in an electron beam exposure device, and the acceleration voltage was 20K.
A pattern was drawn under the conditions of V and exposure amount I x 1O-5C/cm2, and after developing with acetone for 1 minute, it was rinsed with isopropyl alcohol (abbreviated as IPA).

In the pattern formed in this way, no positional shift that occurs when forming using a conventional negative resist was observed.

〔Effect of the invention〕

According to the present invention, since the resist material has conductivity, it is possible to prevent the accumulation of electric charge that occurs during electron beam exposure, thereby making it possible to form a fine pattern without positional deviation.

Claims (1)

[Claims] A negative resist composition characterized in that polyvinylbenzyl chloride is partially converted into quaternary ammonium and reacted with lithium/tetracyanoquinodimethane salt to form a polymeric polycation/tetracyanoquinodimethane salt type complex.