JPH023055A - Silicon-containing resist - Google Patents

Abstract

PURPOSE:To improve photosensitivity for extreme ultraviolet rays, etc. and oxygen reactive etching resistance of a resist by incorporating an alkali-soluble polymer having a phenol skeleton and a specified Si-contg. compd. into the resist. CONSTITUTION:An alkali-soluble Si-contg. polymer having a phenol skeleton and a compd. expressed by the formula I are incorporated into a resist compsn. In the formula I, each R1 to R6 may be same or different, expressing H or 1-10C (non)substituted alkyl group; R7 is an Si-contg. org. group; R8 is an H atom. Thus, a fine resist pattern can be formed since the resist has high sensitivity and high definition for extreme ultraviolet rays. Further, resistance to oxygen reactive etching of the resist pattern after development is improved if an Si- contg. compd. expressed by the formula I is used as another component of the resist.

Description

DETAILED DESCRIPTION OF THE INVENTION [Objective of the invention'] (Field of industrial application) The present invention relates to a silicon-containing resist, and more specifically to a silicon-containing resist.
It concerns silicon-containing resists sensitive to pUV.

(Prior Art) In the field of electronic components that require various micro-machinings, including semiconductor integrated circuits, injectors are widely used. In order to achieve high-density integration due to high-density openings, miniaturization of patterns is required.In order to form fine patterns, the shorter the wavelength of the light source, the better the resist sensitive to deep UV. desired.

Furthermore, the conventional single-layer resist method in which a single resist layer is formed on a substrate such as a wafer has various problems that impede the miniaturization. For example, since the vertical dimension of the integrated circuit is not reduced as much as the horizontal dimension of the integrated circuit, the height to width ratio of the resist butter has to be increased. For this reason, it has become more difficult to suppress dimensional changes in resist patterns on wafers having complicated step structures as patterns become finer.

Furthermore, problems have arisen in various exposure methods as the minimum dimension is reduced. For example, in light exposure, the interference effect of reflected light due to the step on the semiconductor substrate has a large effect on dimensional accuracy. On the other hand, in electron beam exposure, there is a problem in that it is not possible to increase the height-to-width ratio of a fine resist pattern due to the proximity effect caused by backscattering of electrons.

A multilayer resist system has been developed as a method to solve the above-mentioned problems. For overcast multilayer resist systems, see Solid State Technology 74
(I981) [5olid StateTech
Nology, 74 (I981)], and many other studies regarding the system have also been published. Currently, the method that is being tried most often in boat fishing is a three-layer resist system, in which the bottom layer has the role of flattening the steps on the semiconductor substrate and preventing reflections on the substrate, and the bottom layer is etched. It consists of an intermediate layer that functions as a mask for the photosensitive material, and an uppermost layer that serves as a photosensitive layer.

However, although the three-layer resist system has the advantage of being able to perform finer patterning than the single-layer resist method, it has the problem of increasing the number of steps required to form a pattern. That is, sensitivity to radiation such as deep UV. Since there is no resist that satisfies both optical property and resistance to reactive ion etching by oxygen plasma, these functions are provided in separate layers, resulting in an increase in the number of steps.

(Problems to be Solved by the Invention) The present invention has been made to solve the above-mentioned conventional problems, and is sensitive to short wavelength radiation such as deep UV and resistant to oxygen reactive ion etching. The present invention aims to provide a silicon-containing resist that has excellent resistance (oxygen RIE resistance) and can be developed with an alkaline aqueous solution.

[Structure of the Invention] (Means for Solving the Problems) The present invention is characterized by containing an alkali-soluble silicon-containing polymer having a phenol skeleton and a compound represented by the following general formula (I). This is a silicon-containing resist.

However, R1 to R6 in the formula may be the same or different and each represents a hydrogen atom or an unsubstituted or substituted alkyl group having 1 to 10 carbon atoms, and R7 is an organic group containing silicon, R
8 represents a hydrogen atom.

The above alkali-soluble polymers having a phenol skeleton include: ■ polysiloxane having phenol in its side chain;
Examples include polysilane having phenol in the side chain, (1) novolac resin synthesized from phenol having silicon in the side chain, and (2) ordinary alkali-soluble resin.

Specific examples of the polysiloxanes mentioned above are shown in Table 1 below. Specific examples of the polysilanes mentioned above are shown in Table 2 below. The above novolak resin (①) is
Examples include those obtained by condensing the silicon-containing phenol monomers shown in the table with phenols with formalin or aldehydes. Examples of phenols used here include phenol, 0-chlorophenol,
-chlorophenol, p-chlorophenol, m-cresol, p-cresol, xylenol, bisphenol A, 4-chloro-3-cresol, dihydroxybenzene, trihydroxybenzene and the like.

Examples of the alkali-soluble resins mentioned above are phenol novolac resins, cresol novolac resins, xyresol novolak resins, vinyl phenol resins, isopropenyl phenol resins, combinations of vinyl phenol with acrylic acid, methacrylic acid derivatives, acrylonitrile, styrene derivatives, etc. Copolymers, copolymers of isobuconvex benylphenol and acrylic acid, methacrylic acid derivatives, acrylonitrile, styrene derivatives, etc., acrylic resins,
Examples include methacrylic resin, copolymers of acrylic acid or methacrylic acid with acrylonitrile and styrene derivatives, and copolymers of malonic acid and vinyl ether.

The silicon-containing compound represented by the above general formula (I) is
For example, Gerhard Jager
Ber.

105.137-149 (I972), a method of reacting adipic acid chloride with aldehydes or ketones in the presence of a base, or Her la
r n5tetter and Kurt Kiehs
, Chem, Ber, 98.2099-2102
(I965) and mercury chloride (I
It is synthesized by a method such as heating in the presence of I). Examples of the silicon-containing organic group R7 introduced into general formula (I) include C112CH25i (C1l
3) 3.C! +2 Ctb C)h Cl125l
(C1(3) 3, C112CI2 C112C112
ClI25t(C1(3) 3, CI 2 CIt□C
1hCH□C112□CLCIhC11□C112CI
+□1 (Clhh, C112C1125j (CH3)
2-0-31 (C1!3) 3, - C112C
H25i(Ph,Me)-0-3l(Ph)3, C11
2Cl1(C1l3)Si(Clh)2-0-
3j(C1h) 3, -Ph-C112C112CH
25l(CH3)3, -CI20H25t(P
h) CH3, -CH2ClI2 5iPh(CH)3
, Cl12 CH25t(Ph)20SI(CH3)3
,ClI2Ctl(ClI3)Ph
2 5IO3I(CH3) 3 , CL C)
I(Cll3)Sl(C)h)3,
-Cth C11(C1l3)SiPh2C1
13 etc. can be mentioned. However, in the organic groups listed here, ph represents a phenyl group, and Me represents a methyl group, respectively. Specific examples of silicon-containing compounds represented by the general formula (I) are shown in Table 4 below.

The blending ratio of the silicon-containing compound of general formula (I) to the alkali-soluble polymer having a phenol skeleton is 1 to 200 parts by weight, more preferably 5 to 100 parts by weight, based on 100 parts by weight of the polymer. This is desirable.

The reason for this is that if the amount of the silicon-containing compound is less than 1 part by weight, sufficient photosensitivity cannot be imparted, whereas if the amount exceeds 200 parts by weight, the coating properties may deteriorate. be.

In addition, in the present invention, in addition to the alkali-soluble polymer having a phenol skeleton and the silicon-containing compound of general formula (I), a surfactant as a coating film modifier or an antireflection agent may be used as necessary in the present invention. You may also mix Qin material.

Next, a two-layer renost system using the silicon-containing resist of the present invention will be described.

First, after applying a flattening agent on the substrate,
Baking is performed at a temperature of 30 to 150 minutes to form a textured layer of desired thickness. Examples of the substrate used here include a silicon wafer, a silicon wafer having steps on its surface on which various insulating films, electrodes, and wiring are formed, a blank mask, and the like. The planarizing agent may be of any kind as long as it has a purity that does not cause problems in the manufacture of semiconductor devices and the like. Such planarizing agents include, for example, positive resists made of substituted naphthoquinone diazides and novolak resins, polystyrene, polymethyl methacrylate, polyvinylphenol, novolak resins, polyesters, polyvinyl alcohols, polyethylene, polypropylene, polyimides, polybutadiene, polyvinyl acetate, and Examples include polyvinyl butyral. These resins may be used alone or in the form of mixtures.

Next, after coating the silicon-containing resist of the present invention on the planarizing layer, the temperature is lower than 150°C, preferably 50-120°C.
Dry at ℃ to form a resist film of desired thickness. Examples of the solvent for the silicon-containing resist of the present invention include ketone solvents such as cyclohexanone, acetone, methyl ethyl ketone, and methyl isobutyl ketone, cellosolve solvents such as methyl cellosolve, methyl cellosolve acetate, and ethyl cellosolve acetate, ethyl acetate, butyl acetate, and acetic acid. Examples include ester solvents such as isoamyl. These solvents may be used alone or in the form of a mixture. As the application means, for example, a spin coating method using a spinner, a dipping method, a spraying method, a printing method, etc. can be adopted.

The thickness of the resist film can be arbitrarily adjusted by adjusting the coating means, the concentration of the silicon-containing compound in the silicon-containing resist, the viscosity, and the like.

Next, by exposing a desired portion of the resist film on the planarization layer to light, the exposed portion has lower solubility in the alkaline aqueous solution than the unexposed portion. The optimum exposure amount during this exposure depends on the types of components that make up the resist film, but is usually I
A range of IIj/c1j to 10J/cIIl is preferred.

Further, for exposure, either a contact exposure method or a projection exposure method can be adopted. Subsequently, the exposed resist film is developed with an alkaline aqueous solution. As a result, the unexposed portions of the resist film are dissolved and removed to form a desired resist pattern. The alkaline aqueous solution used here may be any one that quickly dissolves the unexposed areas of the resist film and has an extremely low dissolution rate for other exposed areas, such as an aqueous solution of tetramethylammonium hydroxide. Examples include tetraalkylammonium aqueous solutions and inorganic alkali aqueous solutions such as potassium hydroxide and sodium hydroxide. These alkaline aqueous solutions are usually used at a concentration of 15% by weight or less. Further, as the developing means, for example, a dipping method, a spray method, etc. can be adopted. After development, the developer is washed away with water.

Next, using the formed resist pattern as a mask, the exposed planarization layer is etched by oxygen reactive ion etching (oxygen RIE). At this time, the resist pattern made of the silicon-containing resist of the present invention is exposed to oxygen RIH, so that silicon dioxide (SiO, +) or a film similar to it is formed on the surface layer, and the exposed planarization layer is It becomes 100 times more resistant to oxygen RIE. Therefore, the planarization layer portion exposed from the resist pattern is selectively removed by the oxygen RIE method, and an optimal pattern profile is obtained.

The substrate is etched using the pattern formed through these steps as a mask. As the etching means, a wet etching method or a dry etching method is employed, and when forming a fine pattern of 3 μm or less, the dry etching method is preferable. Wet etching agents include hydrofluoric acid aqueous solution, ammonium fluoride aqueous solution, etc. when etching a silicon oxide film, and phosphoric acid aqueous solution, acetic acid aqueous solution, nitric acid aqueous solution, etc. when etching aluminum. When a chromium-based film is to be etched, an aqueous solution of cerium ammonium nitrate or the like is used. As dry etching gases, CF4, C2F 6, CCJ! 4, B C
l! 3. CI! 2, HC1, etc., and these gases may be used in combination as necessary. Etching conditions include the concentration of the wet etching agent in the reaction tank, the concentration of the dry etching gas, the reaction temperature, and the reaction time, etc., based on the type of material on which the fine pattern is to be formed and the combination of the silicon-containing resist. However, the method is not particularly limited.

After the above-described etching, the planarization layer and the resist pattern remaining on the substrate are removed using a stripping agent such as J-100 (trade name, manufactured by Nagase Kasei Co., Ltd.), oxygen gas plasma, or the like.

In addition to the above steps, it is also possible to add further steps depending on the purpose. For example, for the purpose of improving the adhesion between a resist film made of a silicon-containing resist and a flattening layer, or a flattening layer and a substrate, a pretreatment process is carried out before applying each liquid, a baking process is carried out before or after development, and a dry etching process is carried out. Examples include the step of re-irradiation with ultraviolet rays.

(Function) According to the present invention, by being composed of an alkali-soluble polymer having a phenol skeleton and a silicon-containing compound represented by the above general formula (I) that acts as a photosensitizer, high sensitivity to deep UV can be achieved. Because it can exhibit high resolution, it is possible to form fine resist patterns. Further, by using an alkali-soluble polymer as a component of the resist, development with an alkaline aqueous solution becomes possible, and a highly accurate resist pattern in which swelling and the like are suppressed can be formed. Furthermore, as other components of the resist, general formula (I
) The resistance to oxygen reactive etching (oxygen RIE resistance) of the resist pattern after development can be improved. Therefore, since a fine resist pattern with excellent oxygen RIE resistance can be formed, it can be effectively applied to a two-layer resist method.

(Example of the invention) Examples of the present invention will be described in detail below.

Example 1 70 g of polysiloxane represented by structural formula (A) in Table 5 below and 30 g of a silicon-containing compound represented by structural formula (B) in Table 5 are dissolved in 400 g of ethyl cellosolve acetate. and filtered using a 0.2 μm fluororesin membrane filter to prepare a silicon-containing resist.

Next, a resist made of commercially available novolac resin was applied to a thickness of 2.0 μm on the silicon wafer, and then
A flattening layer was formed by heating at .degree. C. for 30 minutes. Continuing,
The silicon-containing resist is deposited on this planarization layer to a thickness of 0.6 μm.
After pre-baking at 90℃ for 5 minutes,
Exposure using 48 nm KrF excimer laser light (2
00raJ/aj).

Thereafter, it was immersed in a 1.0% by weight aqueous tetramethylammonium hydroxide solution for 1 minute and developed to form a resist pattern. Thereafter, the planarization layer was etched by oxygen RIE using the resist pattern as a mask.

When a cross-section of the pattern of the planarization layer after etching by oxygen RIE was observed using a scanning electron microscope, it was found that the film thickness was 2.3 μm and the line width and line spacing were both 0.3 μm. It was confirmed that the

Example 2 70 g of polysiloxane represented by structural formula (C) in Table 5 below and silicon-containing compound 309 represented by structural formula (D) in Table 5 were dissolved in 400 g of ethyl cellosolve acetate. and filtered using a 0.2 μm fluororesin membrane filter to prepare a silicon-containing resist.

Next, a resist made of a commercially available novolac resin was applied to a thickness of 2.0 μm on the silicon wafer and heated at 200° C. for 30 minutes to form a flattened layer. coating, exposure, development, oxygen RI
When E was performed, a pattern having a film thickness of 2.3 μm, a line width and a line interval of 0.3 μm, and a sharp profile was formed.

Example 3 70 g of a novolac resin synthesized from a phenol having silicon in its side chain, represented by the structural formula (E) in Table 5 below, and a novolac resin represented by the structural formula (F) in Table 5, shown below. Silicon-containing compound 309 to ethyl cellosolve acetate 4
00 g and filtered using a 0.2 μm fluororesin membrane filter to prepare a silicon-containing resist.

Next, a resist made of a commercially available novolac resin was applied to a thickness of 2.0 μm on the silicon wafer and heated at 200° C. for 30 minutes to form a flattened layer. coating, exposure, development, oxygen RI
I did E. However, a 3.0% by weight aqueous tetramethylammonium hydroxide solution was used as the developer. As a result, a pattern was formed having a film thickness of 2.3 μm and a steep profile with a line width and line spacing of 0.3 μm.

Example 4 70 g of poly(p-vinylphenol) and 50 g of a silicon-containing compound represented by the structural formula (G) in Table 5 below
Dissolve g in 400 g of ethyl cellosolve acetate,
A silicon-containing resist was prepared by filtration using a 0.2 μm fluororesin membrane filter.

Next, a resist made of a commercially available novolac resin was applied to a thickness of 2.0 μm on the silicon wafer and heated at 200° C. for 30 minutes to form a flattened layer. coating, exposure, development, oxygen RI
I did E. As a result, a pattern with a film thickness of 2.3 μm and a steep profile with a line width and line spacing of 0.3 μm was formed.

[Effects of the Invention] As detailed above, the silicon-containing resist of the present invention has good sensitivity to deep UV and oxygen resistance R.
It has excellent IE properties, can be developed with an alkaline aqueous solution, can be applied to a two-layer resist system, and has remarkable effects such as being extremely convenient for microfabrication.

No. table (continuation) (continuation) No. table No. table (continuation) H Table 3 C2H5 2H5 No. table (continuation) C2H5CH3 No. table (continuation) No. table (continuation) H H No. table (continuation) C2H5 No. table (continuation) H No. table (continuation) No. table No. Finished ( (continuation) No. table (continuation) H3CH3 No. table (continuation) nest table (continuation) No. table (continuation) No. table [A) [C] No. table (continuation) [E] No. table (continuation) CF3 G.I.

Claims (1)

[Scope of Claims] A silicon-containing resist characterized by containing an alkali-soluble polymer having a phenol skeleton and a silicon-containing compound represented by the following general formula (I). ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (I) However, R_1 to R_6 in the formula may be the same or different, and each represents a hydrogen atom or an unsubstituted or substituted alkyl group having 1 to 10 carbon atoms. R_7 represents a silicon-containing organic group, and R_8 represents a hydrogen atom.