JPS62190229A - Vinyl group-containing silane based polymer - Google Patents

Abstract

PURPOSE:A polymer, constituted of specific structural units, highly sensitive to electron rays, ion beams, near infrared rays, etc., having strong resistance to dry etching, capable of forming fine patterns and suitable for resist materials. CONSTITUTION:A silane based polymer having the backbone chain constituted of the formula (R is H or lower alkyl; n is 0 or a positive integer) and having 3,000-1,000,000mol.wt. The polymer is obtained by reacting a dichlorosilane compound with metallic sodium in a nonpolar solvent. An organic film and resist layer consisting of the above-mentioned silane polymer having a given resist pattern and 3,000-1,000,000mol.wt. are formed on a substrate one after another and a pattern is formed by a two-layer structural resist method using the resist pattern as a dry etching mask for the organic film.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention relates to a vinyl group-containing silane polymer particularly suitable for forming fine patterns in semiconductor integrated circuits, magnetic bubble memories, etc., and a resist containing this polymer; This invention relates to a material and a pattern forming method using this polymer.

[Prior Art] When forming fine patterns using optical lithography or electron beam lithography in the manufacture of integrated circuits, bubble memory devices, etc., optical lithography is affected by repulsion waves from the substrate, and electron beam lithography is affected by repulsion waves from the substrate. It is known that the resolution decreases when the resist is thick due to the effects of electron scattering. Dry etching is used to accurately transfer the resist pattern obtained by development to the substrate. However, if a thin resist layer is used to obtain a high-resolution resist pattern, the resist will also be etched by the dry etching and the substrate will be etched. It has the disadvantage that it does not exhibit sufficient resistance for processing. Furthermore, in order to flatten the step portion, it is necessary to apply a thick resist layer, and it can be said that it is extremely difficult to form a fine pattern on such a resist layer.

In order to solve these inconveniences, a three-layer resist was developed by J. H. Horan et al. in the Journal of Vacuum Science and Technology (J. Vacuum 5science).
and Technology), Vol. 16, p. 1620 (1979). In a three-layer structure, a thick organic layer is applied to the first layer (CR'''F layer), and then an intermediate layer such as a silicon oxide film, silicon nitride film, or silicon film is difficult to be etched by dry etching using 02. Forms an inorganic material.

Thereafter, a resist is spin-coated onto the intermediate layer, and the resist is exposed and developed using an electron beam or light.

Using the obtained resist 1 pattern as a mask, the intermediate layer is dry etched, and then, using this intermediate layer as a mask, the first thick organic layer is etched by a reactive sputter etching method using 02. This method allows converting thin high-resolution resist patterns into thick organic layer patterns. However, in such a method, after forming the first layer, an intermediate layer is formed by vapor deposition, sputtering, or plasma CVD, and a patterning resist is further applied, so the process is complicated.
It also has the disadvantage of being long.

If the patterning resist is resistant to dry etching, a thick organic layer can be etched using the patterning resist as a mask, resulting in a two-layer structure and simplifying the process.

[Problems to be Solved by the Invention] It is known that polydimethylsiloxane has excellent resistance to oxygen reactive ion etching (02RIE) and has an etching rate of almost zero (G.N.
Taylor, T.M. Wolff and T.M. Moran.

Journal of Vacuum Science and Technology, 19(4), 872.1981>(G
, N., D., D., H., Wolf.
and J, )1. )Ioran.

J. Vacuum Sci., 19(4), 872. 1981)
However, since this polymer is liquid at room temperature, it is not suitable as a resist material because it tends to attract flakes and is difficult to obtain high resolution.

We have already proposed trialkylsilylstyrene homopolymers and copolymers as the above-mentioned patterning resists [Japanese Patent Application No. 123866/1983
-15419 Publication>, Japanese Patent Application No. 57-123865 (
JP-A No. 59-15243). However, these polymers have excellent sensitivity to far ultraviolet or electron beam exposure and are suitable as resists for far ultraviolet or electron beam exposure, but they do not crosslink when exposed to near ultraviolet or visible light. It could not be used as a photoresist.

In addition, we have already provided silane polymers as the above-mentioned patterning optical exposure regime 1 (Patent Application No. 1983).
-001636, Japanese Patent Application No. 60-001637).

However, in the resist l~ provided here, the silicon atom concentration is about 10 to 13% (W/W) relative to the polymer, so the conditions are such that side etching of the lower layer is difficult to occur during transfer, that is, the anisotropy of etching is large. Conditions, for example pressure crab 3P
a. Acceleration voltage: 0.16 W/cm2. When the W& element rough flow rate is 2 sec and the target is a polymer, there is a problem that the dry etching resistance is insufficient as an upper layer for patterning.

The object of the present invention is to be able to form fine patterns with extremely high sensitivity to electron beams, X-rays, deep ultraviolet rays, ion beams, or near ultraviolet rays in addition to these, and to have greater resistance to dry etching. An object of the present invention is to provide a polymer, a resist material containing the same, and a method for using the same.

[Means for Solving the Problems] In view of the above situation, the present inventor continued research and found that using a silane-based polymer containing vinyl groups as a resist material is resistant to reactive sputter etching caused by oxygen. It is extremely strong against UV rays, and can be used as a mask when etching thick organic films.It is also extremely sensitive to electron beams, X-rays, deep ultraviolet rays, and ion beams. The present inventors have discovered that the sensitivity is also very high even when compared to other materials, and have come up with the present invention.

That is, the present invention provides a silane polymer with a molecular weight of 13,000 to 1,000,000, whose main chain is composed of the following structural units, CH=C112 (wherein, R is a hydrogen atom or a lower alkyl group, and n is O or a positive integer) A resist material made of the silane-based polymer and a resist layer having an organic film and a predetermined resist pattern are sequentially formed on the substrate, and this resist pattern is used as a dry etching mask for the organic film. A pattern forming method using a layered resist method, characterized in that the resist layer is formed of the silane polymer.

The present invention also includes a resist material made of the silane polymer and bisazide, and the above pattern forming method using this resist material.

The silane polymer according to the present invention has a main chain composed of structural units represented by the formula % (wherein R is a hydrogen atom or a lower alkyl group, and n represents O or a positive integer), of which n is O~1
0 is preferred. When n exceeds 10, resistance to dry etching tends to be insufficient. The terminal group is usually an alkoxy group.

Furthermore, when a polymer is used as a negative resist, it generally has a high sensitivity if it has a high molecular weight, but the resolution decreases by 10% due to the swelling of the developing opening. Generally, if the number of molecules exceeds one million, high resolution cannot be expected. On the other hand, reducing the molecular weight improves resolution, but not only does the sensitivity decrease in proportion to the molecular weight, making it impractical, but it also becomes difficult to form uniform and solid shadows below the molecular weight. There is a problem.

Therefore, the molecular weight of the silane polymer is 3000 to 100.
A value in the range of 0000 is suitable.

The silane polymer of the present invention can be obtained by reacting a dichlorosilane compound and metallic sodium in a nonpolar solvent. The proportion of metallic sodium used is 2 gram atoms or more per mol of dichlorosilane compound,
2.5-3 gram atoms are suitable. Examples of non-polar solvents include benzene, toluene, xylene, etc., with xylene being particularly preferred. Excess metallic sodium and unreacted end groups are treated with alcohol to form alkoxides and alkoxy groups after the polymerization reaction is completed.

The polymer thus produced is soluble in organic solvents such as benzene, toluene, and xylene, and insoluble in methanol, ethanol, isopropyl alcohol, and the like. Further, the weight average molecular weight (MW)/number average molecular weight (Mn) is 2 or more, and the polydispersity is wide, but it can be reduced to 1.5 or less by molecular weight fractionation using a luene-methanol system.

The silane polymer of the present invention is useful as a resist material, and is extremely sensitive to electron beams, Resistance that is highly sensitive to
bawl. The bisazide used in the present invention includes 4,
4'-Diazidochalcone, 2,6-di(4'-andbenzal)cyclohexanone, 2,6-di(4'-azidobenzal)-methylcyclohexanone, 2,6-di(4'-azidobenzal)-4-hydro Examples include oxycyclohexanone. When adding a photocrosslinking agent,
If it is too little or too much, the sensitivity to ultraviolet rays will decrease,
Also, if the composition is added in an excessive amount, it will deteriorate the resistance of 02 to dry etching, so it should be added in an amount of 0.1 to 30% to the polymer.
It is desirable to add % by weight.

In addition, it is generally known that the smaller the polydispersity of a polymer, the better the resolution; however, the silane polymer of the present invention can be easily separated by molecular weight in a toluene-methanol system, and the polydispersity Since a polymer having a small value of 1.5 or less can be obtained, it has excellent resolution.

[Example code] Next, the present invention will be explained by examples.

(Example 1) A silane polymer having Si-CH2-CH=CH2 as a structural unit was manufactured by the following method.

Dichloromethylallylsilane 31 purified by double distillation
．． OCl (0.2 mol) and xylene 200rd were charged to a 500d flask. 11.5 g (0.5 gram atom) of sodium metal was added at once to this solution and heated to reflux the xylene. The reaction was continued under reflux for 6 hours, and after the reaction, the reaction solution was cooled to room temperature. 2
Methanol of No. 07 was added dropwise over 10 minutes to react with the terminal silyl chloride and unreacted sodium metal. The reaction solution was poured into methanol to precipitate a polymer. After filtration, the obtained polymer was dissolved in benzene and poured into a large amount of methanol again to precipitate the polymer. The polymer was filtered and dried under reduced pressure at 50°C. Yield: 16.1 g (yield: 23%). Molecular weight and molecular weight distribution were measured by Gruver mission chroma 1-graphy (GPC). MW =23,000. Mn
=11.000. Mw /Mn = 2.1° The analytical values of the polymer are shown below.

Infrared absorption spectrum (cm-1): 1640.9
00 (vinyl group), 1410 (methyl group), 1
030 (Sin).

835 (CH3Si) The silicon content of this polymer was 33.3% (by weight).

A 1% (V/v) toluene solution of the obtained polymer was prepared, and methanol was added little by little. When the mixture became cloudy, 10% (V/V) methanol was added to the colander, and the mixture was allowed to stand overnight, followed by decantation to perform molecular weight fractionation. A second molecular weight fractionation was carried out by adding the same amount of methanol to the colander and carrying out the same procedure. Further, the same methanol was added and the same procedure was carried out for a third molecular weight fractionation. The results of molecular weight dispersion are shown below.

1st fraction Mw = 48,000 Mn = 3
4,000Mw/Mn=1.4 2nd fraction MW =29,000 Mn=2
2,000Mw/Mn=1.3 3rd fraction MW =14,000 Mn=1
1,000Mw/Mn=1.3 (Example 2> Second fraction of polymer produced in Example 1) 0.4
2 CI and 2,6-c(4'-azidobenzalcyclohexanone) 0.042Q to xylene 12.4Id
After stirring thoroughly, the solution was filtered through a 0.2 filtration filter to obtain a sample 11 solution. This solution was spin-coated on a silicon substrate (200 Orl) L, 80'C,
Drying was performed for 30 minutes. Exposure was performed through a chrome mask using an ultraviolet exposure device (Kasbar 2001p). After development was performed by immersing the film in luene for 1 minute, the film was rinsed with isopropanol for 1 minute. After drying, the initial film thickness of the irradiated side was measured using a stylus method and was found to be 0.120%. Whether microscopic patterns have been resolved or not can be determined by drawing line-and-space patterns of various dimensions and observing the resist material obtained by development using an optical microscope or a scanning electron microscope. . From the sensitivity curve, the sensitivity of this example is determined by the gel point (D'
) was found to be approximately 1.8 seconds. The appropriate exposure range for IP-1300 (manufactured by Shipley), a photoresist widely used in the same exposure equipment, is 7 seconds. Furthermore, the resolution of the obtained pattern was sufficiently resolved in the submicron range at 4.5 seconds of exposure, reflecting the fact that the initial film thickness was thin.

(Example 4) Next, a resist material containing novolac resin as a main component was formed on a silicon substrate, and baked at 250° C. for 1 hour.

After that, the solution prepared in this example was spin-coated, and 8
Drying was carried out at 0° C. for 30 minutes to obtain a uniform coating film with a thickness of 0.25#7. This substrate was exposed to light for 4.5 seconds through a chrome mask using an ultraviolet exposure device. Soaked in toluene 1
After developing for one minute, rinsing was performed for one minute with isopropanol. This substrate was etched using a parallel plate reactive sputter etching device (DE manufactured by ANELVA)! -451>, Q255CCIII.

2. Etching was performed for 7 divisions at OPa and 0.16 W/cm2. Observation using a scanning electron microscope revealed that the submicron pattern of the upper layer was accurately transferred to the lower layer.

[Effects of the Invention] As explained above, the silane polymer of the present invention has a high silicon content of 30 to 45%, so if it is used as a resist material, it has extremely high resistance to dry etching, and it can be used by about 1000 to 2000 people. If the film thickness is 1.
It can be used as a mask for etching an organic layer as thick as 5 layers. Therefore, the resist film for pattern formation may be thin. Furthermore, a thick organic layer on the base reduces the proximity effect in electron beam exposure, and reduces the adverse effects of reflected waves in optical exposure, making it easier to form high-resolution patterns. Even with other exposure methods, high-resolution patterns were easily created.

Claims (5)

[Claims] (1) A silane polymer having a molecular weight of 3,000 to 1,000,000, whose main chain is composed of the following structural units. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, R represents a hydrogen atom or a lower alkyl group, and n represents 0 or a positive integer.) (2) Molecular weight 300 with main chain composed of the following structural units
A resist material comprising a silane polymer having a molecular weight of 0 to 1,000,000. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, R represents a hydrogen atom or a lower alkyl group, and n represents 0 or a positive integer.) (3) A pattern forming method using a two-layer resist method in which an organic film and a resist layer having a predetermined resist pattern are sequentially formed on a substrate, and this resist pattern is used as a dry etching mask for the organic film,
A pattern forming method characterized in that the resist layer is formed of a silane polymer having a molecular weight of 3,000 to 1,000,000 and whose main chain is composed of the following structural units. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, R represents a hydrogen atom or a lower alkyl group, and n represents 0 or a positive integer.) (4) Molecular weight 300 with main chain composed of the following structural units
0 to 1,000,000 silane polymer, ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, R is a hydrogen atom or a lower alkyl group, and n represents 0 or a positive integer.) It is characterized by consisting of bisazide. resist material. (5) A pattern forming method using a two-layer resist method, in which an organic film and a resist layer having a predetermined resist pattern are sequentially formed on a substrate, and this resist pattern is used as a dry etching mask for the organic film,
The resist layer is made of a silane polymer with a molecular weight of 3,000 to 1,000,000 whose main chain is composed of the following structural units, n represents 0 or a positive integer) bisazide.