JPH055345B2 - - Google Patents

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a silicon atom-containing styrenic polymer, a resist composition containing this polymer, and a method for using the same, and particularly relates to a silicon atom-containing styrene polymer, a resist composition containing this polymer, and a method for using the same. The present invention relates to a silicon atom-containing styrenic polymer and a resist composition suitable for a pattern forming method, and a pattern forming method.

[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 involves the influence of reflected waves from the substrate and the effects of electron beams. It is known that in beam lithography, resolution decreases when the resist is thick due to electron scattering. Dry etching is used to accurately transfer the resist pattern obtained by development onto the substrate. However, if a thin resist layer is used to obtain a high-resolution resist pattern, the resist will also be etched by 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.M. Moran et al. in the Journal of Vacuum Science and Technology (J. Vacuum Science and Technology).
Science and Technology), Volume 16, Page 1620 (1979). In a three-layer structure, a thick organic layer is applied as the first layer (bottom layer), and then an inorganic layer, such as a silicon oxide film, a silicon nitride film, or a silicon film, which is difficult to be etched by dry etching using O ₂ is used as an intermediate layer. form a substance 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 resulting resist pattern as a mask, dry-etch the intermediate layer, and then
Using this intermediate layer as a mask, the first thick organic layer is exposed to O ₂
Etching is performed using a reactive sputter etching method. This method allows converting thin high-resolution resist patterns into thick organic layer patterns. However, in such a method, after forming the first layer, the intermediate layer is formed by vapor deposition,
Since it is formed by a sputtering method or a plasma CVD method and a patterning resist is further applied, it has the disadvantage that the process is complicated and 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] Polydimethylsiloxane has excellent resistance to oxygen reactive ion etching (O ₂ RIE).
It is known that the etching rate is almost zero (G.N. Taylor, T.M. Wolf and G.M. Moran, Journal of Vacuum Science and Technology, 19(4), 872, 1981) (GNToylor,
TM Wolf and JMMoran, J. Vacuum Sci,
and Tech., 19(4), 872, 1981), but since this polymer is liquid at room temperature, it is not suitable as a resist material because it tends to attract dust and is difficult to obtain high resolution.

We have already proposed homopolymers and copolymers of trialkylsilylstyrene as the above-mentioned patterning resists [Japanese Patent Application No. 57-123866 (Japanese Unexamined Patent Publication No. 59-15419), Japanese Patent Application No. 57-123865 ( JP-A-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.

Furthermore, we have already provided silane polymers as resists for optical exposure for the above-mentioned patterning (Japanese Patent Application No. 60-001636 and Japanese Patent Application No. 60-001637). However, the resist provided here has a silicon atom concentration of approximately 10 to 13% (W/W) relative to the polymer, so if the lower layer is thick, for example, if the thickness of the lower layer is 1.5 μm or more, it may be dry etched as the upper layer for patterning. Resistance was insufficient.

The purpose of the present invention is to form fine patterns with extremely high sensitivity to electron beams, X-rays, far ultraviolet rays, ion beams, or near ultraviolet rays in addition to these.
Moreover, it is an object of the present invention to provide a polymer having stronger resistance to dry etching, a composition containing the same, and a method for using the same.

[Means for Solving the Problems] In view of this situation, the present inventors continued their research and found that a polymer having two or more silicon atoms and an allyl group in the monomer unit of the polymer It is extremely resistant to reactive sputter etching caused by oxygen and can be used as a mask when etching thick organic films, and is extremely sensitive to electron beams, X-rays, deep ultraviolet rays, and ion beams. We also discovered that adding a bisazide compound resulted in extremely high sensitivity to near ultraviolet light.
The present invention has now been accomplished.

That is, the present invention provides a silicon atom-containing styrenic polymer with a molecular weight of 3,000 to 1,000,000, whose main chain is composed of the following structural units, (In the formula, n represents a positive integer of 2 or more) A resist composition made of the silicon atom-containing styrene polymer and bisazide, and a resist layer having an organic film and a predetermined resist pattern are formed in order on the substrate, In a pattern forming method using a two-layer resist method in which this resist pattern is used as a dry etching mask for an organic film, the resist layer is formed of the silicon atom-containing styrene polymer or a composition consisting of this polymer and bisazide. This is a pattern forming method characterized by the following.

In the structural unit represented by the general formula () of the present invention, n is 2 or more, particularly preferably in the range of 2 to 5. The terminal group is usually an alkyl group such as n-butyl group or a hydrogen atom.

Furthermore, when a polymer is used as a negative resist, if the molecular weight is high, the sensitivity is generally high, but the resolution is impaired due to swelling during development. Generally, if the molecular weight exceeds 100, high resolution cannot be expected. on the other hand,
Decreasing 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 a uniform and firm swelling when the molecular weight is less than 3,000. There is. Therefore, the molecular weight of styrenic polymers is 3000~
A value in the range of 1,000,000 is appropriate.

The styrenic polymer of the present invention can be produced, for example, as follows.

(In the formula, n and X represent positive integers of 2 or more.) As shown in the above formula, the polymer of the present invention can be synthesized in two ways. By this method, it is possible to produce a polymer having a low polydispersity and having any molecular weight ranging from low to high molecular weight. The other is benzoyl peroxide, which can be produced by a radical polymerization method, and a polymer with a narrow dispersity can be produced by molecular weight fractionation using a methyl ethyl ketone/methanol system.

This polymer is soluble in common organic solvents such as benzene, toluene, xylene, chlorobenzene, acetone, chloroform, etc., and insoluble in methanol, ethanol, etc.

Further, the styrene derivative which is the raw material for the styrenic polymer of the present invention can be produced as follows.

(In the formula, n represents a positive integer of 2 or more.) As shown in the formula, twice the molar amount of acetyl chloride is added dropwise to the alkylsilane and twice the molar amount of anhydrous aluminum chloride at room temperature, and the reaction is completed. rear,
1,n-dichloroalkylsilane is produced by distillation. Furthermore, after methoxylating the silyl chloride, it is reacted with an equimolar amount of allyl bromide as a Grignard reagent to produce 1-allyl-n-methoxyalkylsilane. 4-chlorostyrene can then be reacted with a Grignard reagent to produce the monomers shown above.

The resist material in the present invention is extremely sensitive to electron beams, X-rays, and deep ultraviolet rays as it is, but when bisazide, which is known as a photocrosslinking agent, is added, the resist becomes highly sensitive to ultraviolet rays. The bisazide used in the present invention includes:
4,4'-Diazidochalcone, 2,6-di-(4'-
azidobenzal)cyclohexanone, 2,6-di-(4'-azidobenzal)-4-methylcyclohexanone, 2,6-di-(4'-azidobenzal)-4
-Hydroxycyclohexanone and the like. If the amount of the photocrosslinking agent added is too little or too much, the sensitivity to ultraviolet rays will decrease, and if too much is added, the composition will have poor resistance to _O2 dry etching, so it should be 0.1 to 30% by weight based on the polymer. It is desirable to add %.

It is known that the uniformity of molecular weight distribution also affects resolution, and the smaller the polydispersity, the better the resolution. In this regard, when produced by anionic polymerization, a polymer having a small polydispersity, for example, 1.2 or less, can be directly obtained without molecular weight separation, so the resist material has excellent resolution.

[Example] Next, the present invention will be explained with reference to examples.

Raw material production example 1 Production of 1,2-dichlorotetramethyldinran 60.1 g of powdered AlCl ₃ in a 300 ml flask
(0.45 mol), 29.2 g (0.2 mol) of hexamethyldisilane, and 35.0 g (0.45 mol) of acetyl chloride.
was added dropwise over a period of 2 hours. After the dropwise addition was completed, the reaction was continued for another hour at room temperature and distilled to obtain the target compound. The yield was 31g (83%).

Raw material production example 2 Production of 1,2-dimethoxytetramethyldisilane 25.6 g of methanol in the three-neck flask from 1
(0.8 mol), pyridine 63.2g (0.8 mol), benzene
300ml was charged and stirred with a mechanical stirrer. The mixture was cooled in an ice bath, 65 g (0.35 mol) of 1,2-dichlorotetramethyldisilane was added, the reaction was continued for 2 hours, and the mixture was filtered. After distilling off the solvent under reduced pressure, the residue was distilled to obtain the target compound. 44.8
The yield was 72%.

Raw Material Production Example 3 Production of 1-allyl-2-methoxytetramethyldisilane 4.3 g atoms of magnesium and 10 ml of ether were placed in a 300 ml flask. After adding a small amount of ethyl bromide and heating to activate the magnesium, 200 ml of ether was added. 25.5 g (0.14 mol) of allyl bromide was added dropwise over 2 hours. Stirring was continued for an additional 2 hours to complete the reaction. In another 500 ml flask, 25.5 g (0.14 mol) of 1,2-dimethoxytetramethyldisilane and 50 ml of ether were charged, and Grignard reagent of allyl bromide was slowly prepared and added dropwise over about 4 hours.
After filtration, the solvent was removed under reduced pressure and distilled to obtain the target compound. The yield was 16.2g (60%).

Raw material production example 4 Production of 4-allyldimethylsilyldimethylsilylstyrene 2.4g of magnesium in a 300ml three-necked flask
(0.1 gram atom), 10 ml of THF was charged, and after heating a little, a small amount of ethylmagnesium was added to activate the magnesium. After adding 100ml of THF, 12.5g (0.09mol) of 4-chlorostyrene
was added dropwise over a period of 3 hours. After continuing the reaction for an additional 2 hours, 13.7 g (0.072 mol) of 1-allyl-2-methoxytetramethyldisilane was added dropwise over a period of 1 hour. The mixture was heated to reflux and reacted for 2 hours. After the reaction was completed, the mixture was poured into a dilute aqueous HCl solution, and extracted with ether. After adding a small amount of t-butylcatechol, the ether layer was dried with MgSO ₄ , the ether was distilled off, and the residue was distilled to obtain a monomer. Example 1 The yield was 8.0g (43%). The monomer synthesized in Raw Material Production Example 4 and THF were pre-dried with calcium hydride. All polymerization reactions described below were performed under high vacuum. 11 g of the monomer produced in Raw Material Production Example 4 was charged into a 100 ml flask with a branch, the branch was sealed with a rubber septum, and the flask was connected to a high vacuum line. It was frozen in a liquid nitrogen bath and then returned to a liquid state by applying vacuum. After repeating this operation four times to remove air contained in the monomer, 0.5 ml of n-butyllithium (1.6 M in hexane) was added to completely dehydrate the monomer.
It was then distilled into a similar side flask.
50 ml of THF was similarly degassed and dehydrated and distilled into the polymerization flask. At room temperature, 80μ of n-butyllithium (1.6M in hexane) was added through a rubber septum using a microsyringe, and the mixture was immediately cooled in an acetone-dry ice bath to carry out polymerization. After 2 hours, 1 ml of methanol was added using a syringe to stop the polymerization, the pressure was returned to normal, and the polymer solution was poured into 500 ml of methanol. The polymer precipitated out as a white solid and was separated by filtration. Further dissolve in 100ml of benzene and 500ml of methanol.
I invested in it. After repeating this operation three times, it was dried at 50° C. under reduced pressure. Yield of target compound is 10.7g
(almost 100%).

Polymerization average molecular weight (Mw) = 51000 Number average molecular weight (Mn) = 43000 Polydispersity (Mw/Mn) = 1.18 This polymer has two silicon atoms in one unit, so the silicon content is The amount is 21.5% (W/W) of the entire polymer.

10 g of the obtained polymer was dissolved in 500 ml of methyl ethyl ketone, and 70 ml of methanol was added little by little. After leaving the resulting cloudy liquid overnight, it was decanted and the polymer solution that had settled in the lower layer was washed with benzene.
It was dissolved in 100ml and poured into 50ml of methanol.
As a result, a white solid was obtained, which was filtered and dried under reduced pressure to obtain fraction 1. Furthermore, 30 ml of methanol was added to the supernatant liquid after decantation, and a second molecular weight fractionation was carried out in the same manner as above.
Further, the same amount of methanol was added and the same procedure was carried out for a third molecular weight fractionation.

Example 2 0.42 g of the polymer produced in Example 1 and 0.021 g of 2,6-di-(4'-azidobenzenazal)-4-methylcyclohexanone were dissolved in 6.0 ml of xylene, thoroughly stirred, and then 0.2 μm thick. The solution was filtered through a filter to obtain a sample solution. This solution was spin-coated (3000 rpm) onto a silicon substrate and dried at 80°C for 30 minutes. Ultraviolet exposure equipment (MANN4800 DMW (GCA)
Exposure was carried out using a chrome mask (manufactured by Co., Ltd.).

After developing by immersing in methyl isobutyl ketone (MIBK) for 1 minute, it was developed with isopropanol for 1 minute.
I rinsed it for a minute. After drying, the film thickness of the irradiated area was measured using a stylus method. The initial film thickness is
It was 0.25 μm. Whether fine patterns have been resolved or not can be determined by drawing line-and-space patterns of various dimensions and observing the resist images obtained through development using an optical microscope or scanning electron microscope. Examined.

From the sensitivity curve, it was found that the gel point (D ⁱ _g ) was approximately 0.8 seconds. Shipley MP-1300, a photoresist widely used for ultraviolet exposure
(1 μm thickness), the appropriate exposure amount was 0.38 seconds.

Example 3 Resist material mainly composed of novolac resin (MP-1300 (manufactured by Shippray)) on a silicon substrate
was applied to a thickness of 1.5 μm and baked at 250°C for 1 hour. After that, the solution prepared in Example 2 was applied by spin coating and dried at 80°C for 30 minutes.
A uniform coating film with a thickness of 0.25 μm was obtained. This substrate was exposed to light for 10.0 seconds through a chrome mask using an ultraviolet exposure device (4800 DSW (manufactured by GCA)). MIBK/n
-BuOH (50/100V/V) was immersed for 1 minute for development, and then rinsed for 1 minute with isopropanol. This substrate was etched for 25 minutes using a parallel plate reactive sputter etching device (DEM-451 manufactured by Anelva Corporation) under the conditions of 2 sccm of O ₂ and 0.16 W/cm ² of 3.0 Pa. Observation with a scanning electron microscope revealed that the submicron pattern of the upper layer was accurately transferred to the lower resist material, forming a more vertical pattern.

[Effects of the Invention] As explained above, since the polymer of the present invention has two or more silicon atoms per structural unit,
In the case of a high silicon concentration, for example, two silicon atoms, it is 21.5% (W/W). Therefore, the resist composition is extremely resistant to dry etching, and a film thickness of about 2000 Å can be used as a mask for etching an organic layer as thick as about 1.5 μm. Therefore, the resist film for pattern formation may be thin. Further, if there is a thick organic layer on the base, the proximity effect is reduced in electron beam exposure, and the adverse effect of reflected waves is reduced in optical exposure, so that a pattern with high resolution can be easily obtained. Also, high-resolution patterns can be easily obtained using other exposure methods.

Furthermore, when the polymer of the present invention is synthesized by an anionic polymerization method, a polymer with a small polydispersity of molecular weight distribution can be obtained, and therefore, when a composition of the polymer and bisazide is used as a resist, the pattern obtained is The resolution will be better.

Claims (1)

[Scope of Claims] 1. A silicon atom-containing styrenic polymer having a molecular weight of 3,000 to 1,000,000, whose main chain is composed of the following structural units. (In the formula, n represents a positive integer of 2 or more). 2 Molecular weight where the main chain is composed of the following structural units
A styrenic polymer containing 3,000 to 1,000,000 silicon atoms, (In the formula, n represents a positive integer of 2 or more.) A resist composition comprising bisazide. 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, wherein the resist layer has a main chain is composed of the following structural units and has a molecular weight of 3000~
A method for forming a pattern, characterized in that the pattern is formed from a styrene polymer containing 1,000,000 silicon atoms. (In the formula, n represents a positive integer of 2 or more). 4. 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, wherein the resist layer has a main chain is composed of the following structural units and has a molecular weight of 3000~
A styrenic polymer containing 1,000,000 silicon atoms, (In the formula, n represents a positive integer of 2 or more.) A method for forming a pattern, characterized in that the pattern is formed from a composition made of bisazide.