JPS62113136A - Resist composition - Google Patents

Abstract

PURPOSE:To enhance conductivity and to enable slip of pattern position due to accumulation of electrostatic charge to be eliminated and a submicron minute pattern high in precision to be formed by mixing a polymer polycations- tetracyanoquinodimethane salt type complex with an electron beam resist. CONSTITUTION:The electron beam resist is divided into a positive type resist and a negative type resist, and both types can be made electrically conductive by adding an organic conductive compound. As this compound, the polymer polycations-tetracyanoquinodimethane (TCNQ) salt type complex having a high electric conductivity of 10<-9>-10<-10>S.cm<-1> is used. It is added to the electron beam resist to prevent electrification, and the addition of said complex in an amount of 10-50wt% of the resist permits a conductivity of 10<-12>-10<-15>S.cm<-1> to be obtained, and the accumulation of charge at the exposed part to be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] A resist composition imparted with electrical conductivity by mixing a polymeric polycation-tetracyanoquinodimethane salt type complex into an electron beam resist.

[Industrial application field]

The present invention relates to improvements in electron beam resists.

2. Description of the Related Art Semiconductor devices, which form the main body 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 VLSIs, which have a much larger capacity than LSIs, are being 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.

Now, not only semiconductor devices but also all electronic components with fine patterns such as magnetic bubble memory elements and surface acoustic wave filters are patterned using thin film formation technology and photo-etching wave 4Xi (photolithography or electron beam lithography). is being carried out.

That is, physical methods such as vacuum evaporation method and sputtering method, and chemical vapor deposition method (Chemical Vapor Deposition method)
A thin film of metal or insulator is formed on the substrate to be processed using a chemical method such as CVO (abbreviation: 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 is 0.1
Since it is about the size of a human and is more than four orders of magnitude shorter than the wavelength of light, it can be expected to have great resolution, and it is also possible to form patterns with a width of 0.1 μm.

For this reason, 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.

On the other hand, however, there is a problem in that since electrons have a negative charge, charges are accumulated in the electron beam scanning section (hereinafter referred to as the exposure section), and this accumulated charge bleeds, causing pattern positional displacement.

This misalignment is caused by the pattern width and spacing being
Although this is not a problem in the case of m units, 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 an electron beam resist in which conductivity is imparted to the electron beam resist by mixing a salt-type complex consisting of a polymeric polycation and tetracyanoquinodimethane into the electron beam resist. can.

[Effect]

The present invention solves the problem of pattern misalignment by imparting conductivity to the conventionally used electron beam resist.

That is, there are two types of electron beam resists: positive type resists and negative type resists, and conductivity can be imparted to either of these resists by adding a conductive organic compound.

Here, the present invention uses a salt-type complex of a polymeric polycation and tetracyanoquinodimethane (abbreviated as TCNQ) as a conductive organic compound.

The salt type complex used in the present invention is 10-9 to 10" 5-c
m-1, and this salt type complex has a conductivity of 10-1.
By adding it to a conventional electron beam resist exhibiting a conductivity of 6 to 10-''S-cm-', it imparts an antistatic effect.

That is, by adding 10 to 50% by weight of the above salt-type complex, the conductivity can be increased to 10''2 to 10-'' S -cm-'
It is possible to put this electron beam resist into practical use and eliminate charge accumulation in exposed areas.

〔Example〕

Example 1 (Application example for positive resist): Polyvinylbenzyltriethylammonium and lithium (Li
)-TCNQ salts were separately dissolved in ethanol to make a 0.04 mol/1 solution.

Both were mixed and stirred for 1 hour at room temperature in a nitrogen (N2) stream to synthesize a polyvinylbenzyltriethylammonium-TCNQ salt type complex.

Next, 30% by weight of this complex was added to polymethyl methacrylate-1 (abbreviated as PMMA), which is a typical conventional positive resist, and dissolved in cyclohexanone to prepare a resist.

The resist was spin-coded onto a silicon (Si) substrate to a thickness of about 1 μm, and then baked at 140° C. for 30 minutes.

Next, the Si substrate was set in an electron beam exposure device, and a pattern was drawn at an accelerating voltage of 20 KV and an exposure dose of 5 Xl0-5 C/cm2, and then developed with methyl isobutyl ketone for 2 minutes.

The pattern formed in this way is coated with PM as before.
No positional deviation that occurs when patterning is performed using only MA was observed.

Note 1: In the above examples, polyvinylbenzyltriethylammonium was used as the polymeric polycation, but poly-4-vinyl-N-methylpyridium,
polydiallyldimethylammonium, polydiallyldimethylammonium sulfone, poly-N, N, N',
Similar effects can be obtained using TCNQ salts such as N'-tetramethylhexamethylene paraxylene ammonium.

In addition, although PMMA was used as a positive resist in the examples, PMl'lA-MA (methacrylic acid) 1 trichloroethyl methacrylate, trifluoroethyl α-chloroacrylate, etc. were used instead of the above TC.
A similar effect can be obtained when mixed with NQ salt.

In addition, if 10 to 50% of the TCNQ salt type complex of each of the polymeric polycations mentioned above is added to each of the above resist materials, the conductivity will be 10-12 to 10-1'S in any combination.
-cm-' electron beam positive resist can be produced.

Example 2 (Application example to negative resist): Polyvinylbenzyltriethylammonium-TCNQ synthesized by the same method as Example 1 was applied to chloromethylated polystyrene (hereinafter abbreviated as CMS), which is a typical conventional electron beam negative resist. A negative resist was prepared by adding 25% by weight of salt type substances and dissolving them in cyclohexanone.

This resist was spin-coded onto a Si substrate to a thickness of about 1 μm, and then baked at 80° C. for 20 minutes.

Next, place the Si substrate into an electron beam exposure device and apply an acceleration voltage of 2
After pattern writing was performed at an exposure dose of 3 x 10-'C/cm2 at 0 KV, development was performed with acetone for 1 minute, followed by rinsing with IPA.

In the pattern formed in this way, no positional shift that occurs when patterning is performed using only conventional CMS was observed.

Note 2: Although CMS was used as the negative resist material in this example, the same effect could be obtained by using glycidyl methacrylate-ethyl acrylate copolymer (COP) or polydiallyl orthophthalate (PDOP). be.

In addition, in the examples, polyvinylbenzyltriethylammonium was used as the polymeric polycation, but Note 1
Various polymeric polycations can be used as shown in .

If 10 to 50% by weight of each of the above polymer polycation-TCNQ salt type complexes is added to each of the above resist materials, the conductivity of any mixture will be IQ-12 to 1O-15S.
It becomes possible to produce a cllll-1 electron beam negative resist.

〔Effect of the invention〕

As described above, by carrying out the present invention, it is possible to eliminate pattern misalignment due to charge accumulation, and it becomes possible to form submicron fine patterns.

Claims (1)

[Claims] 1. A resist composition characterized in that a conventional electron beam resist is made to have electrical conductivity by mixing a salt type complex consisting of a polymeric polycation and tetracyanoquinodimethane with the electron beam resist.