JPS61289345A - Resist for lithography - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a resist for beam lithography and a method of using the same.

B. SUMMARY OF THE DISCLOSURE A resist composition comprising at least one polysulfone sensitizer in at least one silicon-containing resin matrix. The method for forming an image using the resist composition includes coating a substrate with a solution of the resist composition;
It consists of baking, imagewise exposing, preferably post-baking, and then developing to remove the desired portions of the resist.

In the case of two-layer phosphorography, after development, the resist pattern is transferred from the paste layer to the substrate, eg, by oxygen-reactive ion etching, followed by a metal deposition and lift-off step.

C1 Prior Art In integrated circuit technology, device densities are increasing (as device densities increase, allowing the formation of smaller images, e.g., 1 micron or less, and with less electron beam, X-ray, ultraviolet, or excimer radiation).
Resist materials that are highly sensitive to radiation such as lasers are required. High-energy, short-wavelength radiation such as deep ultraviolet and IJ (220-290 nm) has little diffraction effect, so
High-resolution images are possible. Therefore, there is increasing interest in the use of deep UV radiation and the design of resist materials that are sensitive to deep UV radiation. For such applications, specially designed new materials are required since conventional resists are optically transparent at wavelengths below 300 nm.

In addition, X-ray lithography technology has negligible diffraction effects, so it has high resolution and high throughput.
It is also widely recognized that there is an advantage in that relatively inexpensive equipment can be used.

X-ray sources used in X-ray phosphorography include electron beam anodes, pulsed plasmas, and electron storage rings that emit synchrotron radiation, but the last one has high parallelism and is a powerful radiation source. Are known. However, the most available and cheapest radiation source based on electron beam evaporation is the relatively weak radiation of X-rays. Therefore, the practical application of X-ray lithography in the fabrication of high-density integrated circuit devices requires high sensitivity and the necessary thermal stability.
It would be desirable to develop resist materials that are resistant to dry processing (reactive ion etching, metal deposition, etc.) and have good adhesion to various organic and inorganic interfaces. Recently, the following research has been conducted regarding the scope and limitations of X-ray sensitive resist materials according to the prior art.

Jeanne Tiller (G, N, Tay 1 or r
)'s "X-ray resist material (X-Ray Re5ist
Materialg)”, Solid State Technology, 23
．． 73 (1980), F.
) “Irradiation of electron beams and X-rays to polymers and their application to microphosphorography (Electron
and X-rayIrradiation of
Polymers and 1tsApp item c
ation for Mlerolithography
y)”.

Microcircuit Engineering (Mleroc)
82nd International Conference on Microlithography ('82nd
International Conference
e on Microlithography, pp.
237-255 (1982): As is well known, the molecular weight of the exposed portion of a positive resist decreases, resulting in an increase in the solubility of the exposed portion.
It is preferentially removed by solvent or dry etching, leaving unexposed areas unremoved. On the other hand, negative
Resist undergoes crosslinking and other chemical changes when exposed to various types of radiation, and when the unexposed areas are removed,
The exposed portions are relatively difficult to remove, for example with solvents.

The multilayer resist method has been found to be ideal for submicron photolithography because it requires only a thin (less than about α 5 am) formation layer with a planarizing polymer layer of about 1 to about 10 μm thick. It is being These conditions produce very high resolution turns in the thin resist layer, minimizing backscattering effects. However, for this method to be practical, the pattern must be effectively It is necessary that the imaged resist resist oxygen-reactive ion etching so that it can be transferred to the polymer layer.

Various known x-ray sensitive positive resists have certain drawbacks. For example, polymethyl methacrylate) (
PMMA) has an extremely high dose (more than 1000mJ/-)
Poly(butene sulfone) is more sensitive than PMMA (94 mJ/cd) but less resistant to oxygen-reactive ion etching.

Various methods have been considered in the prior art to improve the sensitivity to X-rays. One of them is to add heavy metals such as palladium, thallium, lead, and silver, or halogens such as chlorine, bromine, and iodine to the resist. This is a method of adding it to the composition of

From a practical standpoint, all of these materials are processed after dry processing.
This is considered to be undesirable because it results in a residue that cannot be removed and causes a problem with the reliability of the device.

Another method for improving the sensitivity of a resist to X-rays is to match the radiation wavelength of the radiation source to the absorption band of a particular element in the resist.

US Patent No. 5,895,127 discloses the use of certain copolymers of sulfur dioxide and certain olefins as electron beam resists.

U.S. Pat. No. 3,898,350 discloses olefins,
Mata is an electron-sensitive polyolefin sulfone based on a terpolymer obtained by the reaction of a hydrocarbon selected from the group consisting of cyclopentene and bicycloheptene, an acrylic acid monomer, and sulfur dioxide.・Registration is disclosed.

U.S. Pat. No. 3,961,122 discloses synthetic aromatic-based homopolymers, such as copolymers of polystyrene, polycarbonate, and organosiloxanes;
Discloses a method of forming a thin polymer film comprising a solvent and a solvent. Although the use of a resist is not disclosed, films of the same material have been shown to crosslink upon exposure to ionizing radiation.

U.S. Pat. No. 4,267,257 discloses a method for forming shallow surface relief patterns in poly(olefin sulfone) layers. This sulfone is poly(3
-methyl-1-cyclopentenesulfone), a modulated electron beam is used, and development is carried out with a specific mixture of solvents. These materials lack resistance to oxygen-reactive ion etching.

U.S. Pat. No. 4,289,845 discloses a resist composition comprising a matrix polymer in combination with a modified polymer. In one embodiment, the modified polymer (compatible blend) consists of a novolak polymer and poly(2-methylpentene-1-sulfone).

U.S. Pat. No. 4,341,861 discloses 1 positive consisting of 3-methylcyclopentene, 2-cyclopentene-1 acetic acid and sulfur dioxide.

A water-developable poly(olefin sulfone) terpolymer is disclosed for use as a resist recording medium.

U.S. Pat. No. 4,357,369 discloses a method of forming patterns in a substrate by oxygen plasma etching using a poly(silane sulfone) copolymer resist as a mask.

U.S. Pat. No. 4,396,702 discloses a method of forming patterns in a poly(silanesulfone) copolymer-based positive resist medium.

U.S. Pat. No. 4,398,001 discloses a resist composition that combines a Novosic resin and a poly(olefin sulfone) sensitizer consisting of a terpolymer synthesized from sulfur dioxide, an olefinic hydrocarbon, and an unsaturated ether. Disclosed.

US Pat. No. 4,409,317 discloses that the resin components include an alkali-soluble resin and poly(2-methylpentene-
1-sulfone) is disclosed. Isoamyl acetate or a mixture of isoamyl acetate and a compatible solvent may also be used as the resin component.

European Patent Application No. 0005775 discloses the use of certain poly(olefin sulfones) as sensitizers in low molecular weight substituted novolac resins for phosphorography applications.

It is known that certain polysulfones formed by the reaction of olefins with sulfur dioxide can be used as electron beam resists for phosphorography.

However, none of these prior art discloses the radiation-sensitive and at the same time oxygen-reactive ion etching resistant compositions of the present invention or teaches its advantages in application to the fabrication of integrated circuit devices. There is nothing I did.

D3 Problems to be Solved by the Invention The main object of the present invention is to provide a novel resist composition.

Another object of the invention is to provide novel resist compositions exhibiting one or more of the following characteristics. That is, it withstands dry processing conditions, especially 02 etching (plasma or RIE), forms high quality coatings that are virtually non-tacky, is highly sensitive to radiation,
It has excellent adhesion to various substrates and excellent resolution.

SUMMARY OF THE INVENTION Resist compositions made by combining radiation sensitive polysulfone with a silicon-containing resin matrix in a suitable solvent are provided. Thin films of these resists are prepared by a standard process of removing molding solvents by pre-baking after being deposited on the desired substrate.

After conventional contact printing or enlargement printing, imagewise exposure of the dried coating to radiation and optional post-baking, the resist pattern is developed using, for example, a solvent, and the resist becomes positive. Depending on whether the mold is a negative mold or a negative mold, exposed or unexposed areas are effectively and selectively removed according to the image.

When this resist is used in two-layer phosphorography technology,
The resist pattern is then transferred to the underlying polymer layer, such as by 02 reactive ion etching (RIE).

F. EXAMPLE The polysulfones of the present invention are thermally stable, i.e. about 100
There are no particular limitations as long as the material does not decompose significantly at temperatures below .degree. C. and is compatible with the silicon-containing matrix resin in an appropriate solvent. Compatibility of polysulfone sensitizers in polymer blends is not a common phenomenon.

Polysulfones suitable for the present invention are synthesized by copolymerizing olefins (linear, branched, cyclic) or allyl compounds, or both, with sulfur dioxide by the methods described in the following references: be able to. Chapter 1 of the book entitled "PolymerSynthesis", by Sadler and Karo (1980).For the formation of olefin polysulfones from various olefins and allyl compounds, see the journal・Journal of Polymer Science
nce) J, Vol, XXVI, p351-564 (1
957) to RoE, Cook.
) et al., also published in the Journal of Polymer Science.
5science) J, Part A, Vol 1
．． p2965-2976 (1963) and V01
．． 2p3!155~! +563 (1964), N. Takura et al.
Engineering and Science
) J, Vol, 17, No, -5, June1977
described by Himics et al.

The olefin precursors used to form the polysulfones most useful in this invention are linear or branched 1-olefins, 2-olefins, cyclic olefins, and allyl compounds. These are represented as: (1) c) I2=c-R1 having a total of 4 to 12 carbon atoms.

For example, in the above formula, R is H or CH3, R1 is a linear hydrocarbon group having 2 to 10 carbon atoms, C0oCH
Ester groups such as 3, or c6H5 and pCH3C6
It can be an aromatic ring such as H4. R1 may also be a branched alkyl group.

(11) Cyclic olefins for polysulfones suitable for the present invention include cyclopentene, 1-methylcyclopentene, 2-methylcyclopentene,
-Methylcyclopentene, cyclohexene, bicyclo [
2,2,1]hept-2-ene and the like.

(111) The allyl compounds most useful for forming polysulfones in this application are allyl ethyl ether and methallyl ethyl ether.

(iv) Representative 2-olefins include 2-butene and 2-pentene.

These can be used alone or in combination with the olefins (1) and Ol) to copolymerize with S02 to form copolymers or terpolymers. can.

Representative polysulfones include, for example, poly(methylpentene-methallylethyl ether sulfone) synthesized by the method of US Pat. No. 45,980.101, incorporated herein by reference. It is a terpolymer formed by the polymerization of sulfur dioxide, olefins, and unsaturated ethers. In addition to this, poly(2-
methylpentene-1-sulfone), poly(butene-1-
sulfone), poly(hexene-1-sulfone), poly(
cyclopentenesulfone), H+)-1-, I'-F-
Also included are A'cyclopentenesulfone, propylene-methyl methacrylate-8O2 terpolymer, and the like.

Poly(butene-1-sulfone) is commercially available; others are synthesized by the methods cited above.

Although the molecular weight of polysulfone can be changed freely,
Weight average molecular weight is about 80,000 to about 300,000
Preferably.

There are no strict limitations on the silicon-containing resin used as the matrix resin in the present invention. Usually glass transition temperature (T,)
is higher than about -25°C, preferably higher than about 50°C,
Most preferably, silicon-containing polymers with temperatures above about 100°C are used. However, the present invention is not limited to these T values. To avoid undesirable phase separation when the composite resin is applied to various substrates to form thin films, it must have the desired solubility in the solvent used and be compatible with the polysulfone additive. If T, there is no upper limit.

In general, the glass transition temperature (T, ) of silicon-containing polymers
It is desirable that the solubility is as high as possible to avoid deformation or flow of the bond during optional pre-exposure firing and subsequent dry treatments such as RIE and metal evaporation using conventional methods. (with consideration).

Preferably, the amount of silicon-containing component in the silicon-containing polymer is about 6% by weight or more, and most preferably about 8% by weight or more, based on the total silicon-containing polymer. The properties of the matrix resin of the present invention are that it has solubility in the solvent used, that it is stable to heat, and that it has good film-forming properties, that is, it does not form a sticky film,
It is desirable that the coating be uniform. As is well known, photoresist compositions used in phosphorography further include:
It is necessary that the film has good adhesion to the substrate to be used so that there is no adhesion failure or pattern lifting when the exposed film is developed using a solvent.

Typical matrix resins for use in the present invention include homopolymers, block or random copolymers, or terpolymers of diorganosiloxanes, silalylene siloxanes, and the silicon-free polymeric components described below. Non-silicon-containing components include polycarbonates, polyesters, polyurethanes, polyamides, polyureas, poly(arale/ethers), poly(alkylene ethers), and polysulfones; Co-authored by J.E. McGrath, “Block Copolymers – Overview and Survey”
ers”, Overview and Cr1ti
calSurv@y ) J, Akademitsu Shuppansha (Ac
Academic Press), p. 156-165.
392-45 (5 (1977)). Another representative matrix resin and K is described in U.S. Pat.
Block copolymerization of bisphenol A-polycarbonate and polydimethylsiloxane containing up to 35% by weight of polydimethylsiloxa 7 (PDMS) as shown in No. 9845 (1961) and No. 5189662 (1965) There is a union. These resin compositions require that the final silicon-containing polymer be prepared by plasma or o2RIE.
, the exposed pattern can be developed with commonly used organic solvents, or it can be dry etched in a CF4-O2 gas mixture under normal plasma etching conditions, and the etched areas are There are no particular limitations as long as the surface is free of residue. Usually 0
A gas mixture containing from about 1096 to about 30 CF4 in 2 is preferred. This percentage represents the flow rate of the gas used in Seem (standard cubic centimeters).

Although it is intended that both random and block copolymers can be used in the present invention, block copolymers are more commercially available and can be easily synthesized by standard methods from commercially available raw materials. can do.

Therefore, in principle, the present invention uses silicon-containing block copolymers that are easy to synthesize or obtain.

The molecular weight of these resins can be changed freely taking into account the above properties. However, silicon-containing polymers,
For example, the block copolymer of bisphenol A polycarbonate and polydimethylsiloxane, and the polymers described below, preferably have a weight average molecular weight of about 100,000 to about 200,000.

The ratio of polysulfone to silicon-containing polymer can be varied as long as the polysulfone is present in an amount effective to form high contrast turns. Preferably, the amount of polysulfone is about 10 to about 50% of the total amount of polysulfone and silicon-containing polymer.

Additionally, the present invention provides that, unlike novolak matrix-based resists, the silicon-containing polymeric matrix of the resist compositions of the present invention is relatively transparent to a variety of radiation, including in the deep ultraviolet range. , the sensitivity of polysulfone to radiation, including the deep ultraviolet region, can be fully exploited.

The above bisphenol A polycarbonate and PDMS
In addition to block copolymers with silarylene, other resins that can be used in the present invention include copolymers of PDMS/sylarylene or silphenylene (as is well known, the term "sylarylene" generally refers to substituted silphenylenes, Examples include silphenylene (including methyl-substituted silphenylene), polystyrene/PDMS, polyalphamethylstyrene/PDMS copolymer, hexamethyl terephthalate/siloxane block copolymer, and the like. Other silicon-containing polymers suitable for the present invention c. Poly(tetramethyl-p-silphenylene siloxane) (PTMP)
S) and its copolymer with dimethylsiloxane, i.e. R.L.Mer.
Journal of Polymer 5 by Ker) et al.
science) A2.31 (1964), P”~44
PTMPS/PDM synthesized by the method disclosed in
These include S copolymers, PDMS/polyethylene oxide block copolymers, and PDMS/polyurethane copolymers.

Most of these resins are commercially available, such as those manufactured by Petrarch Systems.
ms) [Silicon Compound Register and Review J
(Siticon Compounds Regis
ter and Review),
Alternatively, it can be synthesized by conventional methods.

Preferred types of silicon-containing polymers include poly(methylphenylsiloxane), poly(tetramethyl-p-silphenylene siloxane), polydimethylsiloxane/silphenylene copolymer, polydimethylsiloxane/alphamethylstyrene copolymer, These include bisphenol A polycarbonate/polydimethylsiloxane block copolymers, polydimethylsiloxane/styrene block copolymers, hexamethyl terephthalate/siloxane block copolymers, and polyurethane/siloxane block copolymers.

Preferred types of silicon-containing block copolymers include polysyl-7-enylene siloxanes, polydialkyl siloxanes, polysylallylene siloxanes, and dimethyl siloxanes as the silicon-containing component, and bisphenol A
- Polycarbonate.

polyurethane, polyester, polyimide, polyurea,
Includes combinations with non-silicon-containing components such as poly(alkylene ether) and polysulfone.

As can be seen in the above examples of silylene or siloxane-containing copolymers, such as poly(tetramethylsilphenylene) siloxane and copolymers of sialarylene siloxane and dimethylsiloxane, peripheral components or both blocks in the polymer structure It is also possible to contain silicon. Generally, however, the silicon content, whether from the polydimethylsiloxane component or from other structural units, will generally be at least about 8 Preferably, it is % by weight. However, this number is not limited as long as the T of the silicon-containing resin is not excessively low. When the amount of silicone, for example, the dimethylsiloxane component is increased, T
, tends to be low, and as mentioned above, too low T tends to cause image deformation (flow) during optional pre-exposure firing and RIE processing. Therefore, the silicon content of the silicon-containing polymer is 6 as silicon.
It cannot be expected to use more than 0% by weight.

The resin of the present invention is formed by dissolving one or more types of polysulfone in a solution in which a matrix resin is dissolved in a solvent or a mixed solvent. Usually, the resin component is dissolved at room temperature, but a temperature higher than room temperature may be used as long as the sensitivity of polyurethane to heat is not a problem.

However, at present no advantage can be found in using high temperatures.

The solvent is not limited and is usually an organic solvent or a mixture thereof. Typical examples include chlorobenzene, toluene, isoamyl acetate, cyclohexanone, and dichloromethane (not preferred because its boiling point is too low). Other solvents can of course be used as long as the coating composition of polysulfone and silicone-containing resin is uniform.

The concentrations of polysulfone and silicon-containing resin in the solvent may be selected so as to provide a compatible resist composition, and there are no limitations on the concentrations. The total solids content (relative to the weight of solvent) is approximately 4% polysulfone and matrix resin.
It has been found that a content of from about 10% by weight to about 10% by weight is suitable for coating by spin◆ coating, spray coating, etc.

Of course, all the components dissolve well in the solvent, but there are no particular limitations on the mixing method.

Coating compositions are typically filtered through submicron filters to remove particles and polymer gels that can cause membrane defects before use. This is a well-known method and is usually 0
．． A 2 micron silver film (commercially available) is used to remove such particles.

The dry thickness of the resist coating of the present invention is such that the coating is free of defects such as pinholes and is suitable for royalties requiring transfer of patterns to coatings below a thickness of approximately 1 to 5 microns, for example. However, there are no particular limitations. For example, a thickness of about 2000 to about 8000 angstroms has been found to yield good results for deep ultraviolet lithography followed by 02RI EVC transfer of the image to the underlying layer.

The resist composition of the present invention can be applied onto a given substrate by conventional methods such as spin coating, dip coating, spraying, and the like. Currently the inventors are using conventional spin coating.

Examples of substrates used in the resist methods of the present invention include various surfaces such as those used in the fabrication of microelectronic devices, such as plasma, low pressure chemical vapor deposition (LPC), etc.
Examples include silicon deposited by VD), plasma enhanced chemical vapor deposition (PECVD), silicon oxide, silicon nitride, and the like. Application of the resists of the present invention in two-layer lithography uses a thick underlayer formed of a polymeric coating composition and requires conventional high temperature baking prior to overcoating the resist composition of the present invention. conduct. The underlying conventional material includes 5H1PL, which withstands metal deposition temperatures.
ey AZ-1350J, ICI Holisulfone, (Ciba Geigy) C1ba 081g1 company's XU-218
and General Electric Co.
There are soluble polyimides such as GEULTEM polyetherimide from Electric Carp. Conventional photoresists are often used as underlayers that are fired at temperatures in excess of 200° C. to render the coating insensitive to optical, dimensional, or other exposures such as ultraviolet radiation. Thus, in the present invention, the term substrate is not limited to conventional inorganic substrates, but also includes polymer surfaces on which the resist composition of the present invention is applied.

One of the applications in which the resist composition of the present invention is particularly useful is
The resist composition of the present invention functions as a 02 etch/etch resistant imaging layer, and the conventional polymer underlayer described above is used to transfer images by dry or wet processing to obtain images of a predetermined depth. ,
It is also a two-layer resist method that functions as a lift-off layer for the conventional metallization method. This will be explained below. For simplicity of explanation, the pre-firing, image-wise exposure and optional post-firing of the present invention will not be discussed in detail. These are of course used in practice. 2
In layered cast systems, the conventional polymeric underlayer is typically subjected to oxygen etching by plasma or RIE. Of course, it is not essential to use the resist composition in the two-layer resist method, and it can be used in the one-layer resist method as well as in the creation of a mask.

Usually, in a two-layer resist method using the resist composition of the present invention on a conventional lower layer, the lower layer is generally heated at 200°C to 200°C.
After baking at 70°C, a resin composition is applied. This temperature is not limited, and the surrounding gas may be, for example, air at low temperatures (less than 100°C), 200°C to 27°C.
If the temperature is 0°C, use an inert gas. for example,
After Sysopray AZ-1350J is coated with Sysp/・ by a conventional method, it is coated with N2, for example, at a temperature up to 230°C.
Firing takes place inside. The firing temperature may simply be selected to ensure the aforementioned insensitivity.

Thus, a typical method involves first spin-coating the lower layer onto a given substrate, baking at 85°C for 20 minutes, followed by 200°C (N2) for 15 minutes, and then 230°C.
Calcination is performed at ℃ (N2) for 30 minutes. Next, the resist composition of the present invention is applied and heated to about 20 to 40°C at about 85 to 115°C.
A one-minute bake (pre-bake) is carried out, followed by a contact bake in a conventional manner using a suitable exposure device, such as a Kasper UV exposure device for deep UV light. Exposure, such as deep UV exposed edges, is carried out at about 80-110° C. for about 10-30 minutes, followed by post-firing, usually at 105° C. for 15-30 minutes, thereby obtaining a high-resolution relief image.

This post-calcination is optional, but preferred.

After solvent development, 02 plasma etching or RIE is then performed to transfer the fully developed pattern to the lower layer where the upper layer acts as a mask for the 02 etch.
I do. After the resist nokturn is copied to the lower layer,
The substrate is cleaned prior to metal deposition and metal deposition is performed by conventional methods, such as sputtering or vacuum deposition. Lift-off is then performed by conventional methods, such as solvent immersion, to obtain an image-wise metal pattern for integrated circuit devices.

Prior to the present invention, there were virtually no high-sensitivity, high-resolution X- or electron-sensitive positive and negative resists and positive deep UV resists with the 02 etch resistance required for dry processing; The above aspects of the invention are of great commercial advantage.

As used herein, the term deep ultraviolet light refers to about 200 to about 3
00 nm range, typically 200 to about 290 nm
means ultraviolet radiation obtained by commonly available exposure equipment in the range of . The resist film of the present invention also includes:
For example, it is also possible to image by an excimer laser with radiation at 248 nm.

In the present invention, the exposure time and intensity can be arbitrarily selected, as long as the polysulfone is activated and the desired difference between exposed and unexposed areas is obtained, regardless of which radiation is used. can. In positive resists, as is well known, crosslinking of the irradiated portions of the resist, i.e., crosslinking that would unduly inhibit removal of exposed portions of the resist, must be avoided. Additionally, as is well known, thicker resists typically require increased exposure time and/or intensity, and vice versa for thinner resists. Although not limited to, we typically use exposure times of about 10 to about 90 seconds with doses of 10 to about 2 QmJ/-.

These resist materials also have high sensitivity to X-rays and electron beams and are therefore used to form patterns using these techniques in phosphorographic processes.

Due to this high sensitivity and resistance to oxygen etching, the resist composition of the present invention is particularly suitable for forming high-resolution metal patterns in a one-layer or two-layer resist method.

Additionally, the inventors believe that conventional X-ray sources, e.g.
It has been found that using an angstrom x-ray source, the resist coating of the present invention can be used to form positive or negative patterns by varying the exposure dose. For example, a resist film of 5 layers m, thickness Q, of a bisphenol A-polycarbonate-polydimethylsiloxane block copolymer containing 20% by weight of poly(methylpentene metallylethyl ether sulfone) is formed at a dose of 20 to 3 m. Aluminum KaX of Q mJ /-
After exposure to the line, a short bake and development with a solvent yields a positive pattern. Although it is preferred to perform a short firing before exposure, firing is not essential. If the same film is exposed to a dose of 120 mJ/- or more and then developed, a negative pattern is obtained.

Resist coatings according to the present invention can also produce very high resolution images with relatively low doses of electron beam exposure. If a film of less than 0.5 μm is exposed to an electron beam at 1.0 μC/4 to 5 μm/ai and then post-baked for a short time at, for example, 85 to 105°C, the resolution will be reduced to 0.
．． A positive relief pattern of 25 μm is obtained. The image can then be fully developed using development in a suitable solvent or dry etching. About 10.0 μC/d to about 15.0 pc/crd of the same coating
, i or higher doses, followed by development, a negative pattern is obtained.

Resists formed using these resists of the present invention
Because the pattern, whether positive or negative, is resistant to oxygen-reactive ion etching, the image is transferred to an underlying layer, usually organic, by a dry process, with the imaged resist acting as a mask. be able to.

XwJ or electron beam irradiation refers to conventional X-ray or electron beam irradiation used in resist exposure with conventional radiation sources. Depending on the intensity of the X-ray or electron beam, the resist of the present invention exhibits either negative or positive properties. At high doses of X-rays or electron beams, the resists of the present invention exhibit negative properties, and at low doses, the resists of the present invention exhibit positive properties. Usually, the time can be freely selected, but the inventors set it to about 10 to about 90 seconds.

Best results with X-rays are obtained with an average dose of about 10 to about 50 mJ/cr for positive resist properties.
1. It is believed that an average dose of about 120 mJ/- or more is sufficient to obtain the properties of a negative resist. Usually about 200 mJ to obtain negative resist properties.
It is considered undesirable to use an average dose of more than /-.

This is because when a very high dose, for example about 300 mJ/cII, is used, the deviated dose causes crosslinking to occur even in areas where crosslinking is not desired.

As will be apparent to those skilled in the art, about 10-5 Q mJ/- and about 12
The range of 0-200 mJ/- is not absolute, and between about 50-200 mJ/- positive and negative resist properties gradually mix. It is currently most preferred to practice within the above range since generally a resist retention rate of about 70-80% by weight is obtained in the areas where the resist is to be left. Obviously, the higher the resist retention amount, the better. Approximately 50 mJ/- or more or approximately 120 mJ
/- or less, the resist retention rate decreases.

It is also possible to practice outside the above ranges if the practitioner of the invention can accept a lower resist retention rate in the areas where resist is to be left. However, it is our general belief that for precision applications, doses in the above range will give the best results.

Although the above explanation has concerned X-ray irradiation, it is believed that the above principles apply to electron beams with the same effect.

An exception is that in the case of electron beam irradiation, the exposure amount range for positive resist is approximately 1°0 to 5.0 μC/ffl,
Exposure range for negative resist is 10.0
-15.0JIC,/-, good results are obtained. For negative resists, higher doses can be used, but there is currently no benefit to using higher doses.

In general, it has been found that the use of post-exposure baking increases resolution and improves resist performance.

For example, during image-wise exposure to deep ultraviolet light, if a positive resist is involved, radicals are generated in the exposed areas and remain until post-baking; We believe that its removal during the process increases the porosity of the exposed areas, making penetration of the solvent into the exposed areas more efficient, thereby accelerating development with the solvent. For the thicknesses previously exemplified, excellent results are obtained when baked after exposure at temperatures of up to about 80-110° C. for about 10-30 minutes. The post-exposure firing environment is not critical, and to date only heating on a hot plate in air has been done. Therefore, although optional, the use of post-exposure firing is highly preferred.

For complete pattern definition, dry development methods are usually used, such as plasma etching in CF4-'02, and more preferably, development methods are used, typically using conventional solvents after exposure/post-baking. Most of our experience has been with solvent development, but we believe that both solvent development and CF4-O2 plasma etching can yield fully developed submicron patterns with high aspect ratios. .

The currently preferred solvent mixture for developing resists sensitive to deep UV radiation is a 30 volume solution of isoamyl acetate dissolved in Impropatur (equal proportions of isoamyl acetate and tetrahydrofuran) with the best results. or dichloromethane in equal proportions in hexane.Currently preferred solvent mixtures for developing resists sensitive to X-rays and electron beams are hexane-acetone-
Ethyl acetate may optionally contain a small amount of methyl isobutyl ketone acid. Current and preferred ratios are shown in Examples 3 through 5, but other ratios can be used as well, as with resists sensitive to deep ultraviolet light.

Approximately 20 l30 for the total volume of solvent It often gives very good results.

Of course, any solvent system that selectively dissolves the unexposed or exposed areas without excessively removing exposed or unexposed areas can be used, and as pointed out earlier, the resist has positive properties. Approximately 20% of the exposed or non-exposed area, depending on whether it has negative properties.
Currently preferred is one that removes only ~3°. Those skilled in the art will appreciate that for most purposes some of the non-exposed areas may be removed.

Development is usually carried out using a solvent in one ambient environment.

Development according to the present invention does not allow for gentle ultrasonic agitation to aid in resist removal in exposed areas, if desired.

Having thus described generally good embodiments of the invention, the following examples are presented to provide the best presently preferred embodiments for carrying out the invention.

Example 1 Bisphenol A-polycarbonate/boridimersiloxane block copolymer (average molecular weight approx. 15000
0, T, about 160°C, polydimethylsiloxane in the copolymer is about 35% by weight) and poly(methylpentene metallethyl ether sulfone) (molecular weight 200,000).
A solution of a positive resist composition according to the present invention (total solids content: 6 ls based on the weight of the solution) was prepared by dissolving it in chlorobenzene at room temperature in a weight ratio of 1 :1.

The solution was filtered through a 0.2 micron filter.

Next, a thickness of 2 was coated on the silicon substrate.

1μm (calcined at 230°C in N2) 5hipl
This was spin-coded onto the eyAZ-1 35 DJ layer using the usual method.

Following the above application, the whole was pre-baked at 105° C. for 30 minutes in nitrogen to produce a total 2.4 μm resist assembly (resist composition according to the present invention and 5hiplays).
1350 J base layer) was obtained.

Image-wise exposure was then performed for 45 seconds through a contact mask using deep UV light using a conventional Kasper deep UV exposure system. (about 45 seconds, 100mJ/ctl)
.

Following image-wise exposure, the whole was incubated in air at 105°C for 3
Post-baking for 0 minutes resulted in a very clear relief pattern in the resist composition of the present invention.

After the above main baking, the entire body was immersed in a 30% solution of isoamyl acetate in Improper Tool for 3 minutes at room temperature to obtain a fully developed positive image in the resist composition of the present invention.
I got the pattern. Next, a short heat treatment is performed to evaporate the remaining solvent in the film, and the film is heated at 250-350 Watts.
Using the normal 02RIE method with an oxygen flow rate of 11ccfn1, the pattern was 5hipley AZ-1 3 in F.
It was transferred to the substrate into the 5OJ layer.

The final thickness of the fully etched image was approximately 2.3 μm, demonstrating that the resist composition layer according to the present invention remained intact during 02 RIE and the image could be transferred to the 5hlplay AZ-1 350 base layer.

Example 2 Polydimethylsiloxane/alpha methylstyrene block copolymer (molecular weight 8000-120000) obtained from Petrarch Systems.
The deuterated thixylene solution was diluted with toluene to create a resin solution with a resin solids content of about 10% by weight. This solution 2002
, based on U.S. Pat. No. 4,398,001,
Add 2.5 f of poly(methylpentenemetallylethyl ether sulfone) with the same molecular weight as in Example 1 to make a clear solution of positive resist, which was filtered simultaneously with Example 1 and prepared on silicone urethane. was spin-coated to the same thickness as in Example 1, pre-baked in nitrogen at 105° C. for 30 minutes, and exposed to deep UV light through a contact mask as in Example 1. The exposed film was heated in air at 105°C for 10-
After 15 minutes of post-baking, a high-resolution relief pattern appeared, which was developed to the substrate by brief dipping in an isoamyl acetate-isopropanol mixture (30 by volume).

Poly(methylpentene metallethyl ether sulfone)poly(tetramethylsilphenylene siloxane) (
A similar toluene solution (Petr
A similar resin system prepared by mixing with Arch Systems) was processed according to the procedure described above to obtain resist patterns of excellent quality. When used in the two-layer method,
Using the image layer as an effective 02RIE mask, the 02R
The resist image could be transferred into the underlying layer by IE.

Example 6 A filtered resist composition prepared as a chlorobenzene solution as described in Example 1 was spin-coated onto a silicon substrate and pre-baked in nitrogen at 105°C for 30 minutes to a thickness of approximately 4200^ (dry thickness). made a film of. 2020-3O/- with normal aluminum KaX-ray source
X-ray exposure was performed at , followed by post-calcination at 85° C. for 10 minutes in air. Subsequently, in an ambient environment, about 1% of
A fully developed positive pattern was obtained by soaking for a minute and rinsing with hexane to preferentially remove exposed areas. A short post-development bake (10 minutes) at 85°C in air to remove the trapped solvent results in a residue thickness of 3200-340 OA, loss of non-exposed areas during removal of exposed areas. was about 20 cm.

The above steps were repeated in a bilayer resist layer following the procedure of Example 1 using hard fired AZ1350 photoresist as the thick underlayer. The exposed and developed pattern (as above) was post-fired as above and 2
58e, gas pressure of 14QμTorr at a gas flow rate of 30
Etch transfer was performed to the bottom layer using 0 Watts RF output. Under these conditions, the patterned resist is effective 02
Brought R■E mask.

Example 4 The filtration resist composition described in Example 1 was
The film was spin coated onto a J-Con wafer and pre-baked in nitrogen at 105°C for 30 minutes to produce a film approximately 4200' thick. X-ray exposure at 120-150 mJ/cJ using the same conventional exposure source as in Example 3 followed by post-calcination at 80° C. for 10 minutes in air resulted in a clear relief pattern. This was heated in air at 90℃ for 15 minutes.
After developing for a minute, the film was baked to remove the trapped solvent. The pattern had excellent dry etch resistance to 02 RIE and therefore could be used in RIE masks with bilayer resin.

Example 5 Approximately 0.4 μm thick films of the resist materials of Examples 3 and 4, such as pre-baked, were spin coated onto 1 [K silicon wafers with these examples and then 2.5 pC
/ctl and 5 pC/ad. A post-exposure firing in air at 90° C. for 15 minutes yielded a high-resolution relief pattern with submicron line resolution down to 0.125 μm line width. Microscopic examination showed excellent quality and sharp image definition of up to 0.25 lines in a linear spatial array. The thickness of the exposed and unexposed areas of the patterned resist was measured and the exposed areas were reduced in thickness relative to the unexposed areas, thus resulting in a positive pattern at this low electron dose.

A fully developed pattern was then obtained using solvent immersion or conventional plasma development as in Example 3.

When the electron beam resist pattern yields the required 02 RIE resistant mask, this process was repeated in a two-layer system as described above to produce a high resolution pattern in a relatively thick underlying layer.

Effect of the G0 Invention The resist of the present invention has 02 dry etching resistance,
It has high radiation sensitivity, excellent adhesive strength, and high resolution.

Claims (9)

[Claims] (1) A lithography resist comprising a mixture of at least one radiation-sensitive polysulfone and at least one silicon-containing polymer. (2) The above polysulfone is represented by sulfur dioxide and the following chemical formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (where R is H or CH_3, R_
1 is a linear hydrocarbon group, ester group, aromatic ring, or branched alkyl group having 2 to 10 carbon atoms), 4 to 12
The resist according to claim 1, which is a copolymer formed by polymerization with an olefin having 5 carbon atoms. (3) The polysulfone copolymer is poly(2-methylpentene-1-sulfone), poly(butene-1-sulfone), poly(hexene-1-sulfone), poly(cyclopentenesulfone), and mixtures thereof. The resist according to claim (2), which is selected from among these. (4) The resist according to claim (1), wherein the polysulfone is a terpolymer of sulfur dioxide, olefin, and unsaturated ether. (5) The resist according to claim (4), wherein the polysulfone is poly(methylpentenemethallylethyl ether sulfone). (6) The above at least one silicon-containing polymer,
Poly(methylphenylsiloxane), poly(tetramethyl-p-silphenylenesiloxane), polydimethylsiloxane/silphenylene copolymer, polydimethylsiloxane/alphamethylstyrene copolymer, bisphenol A-polycarbonate/polydimethylsiloxane.
The claimed polymer material is selected from among block copolymers, polydimethylsiloxane/styrene block copolymers, hexamethyl terephthalate/siloxane block copolymers, and polyurethane/siloxane block copolymers. The resist described in scope item (1). (7) The silicon-containing copolymer contains a silicon-containing component selected from polysilphenylene siloxane, polydialkyl siloxane, polysylallylene siloxane, and dimethyl siloxane, and bisphenol A-polycarbonate, polyurethane, polyester, and polyimide. , polyurea, poly(alkylene ether), and polysulfone. (8) The resist according to claim (1), comprising a mixture of a block copolymer of bisphenol A-polycarbonate and polydimethylsiloxane, and poly(methylpentene metallethyl ether sulfone). (9) The resist according to claim (1), which comprises a mixture of a block copolymer of polydimethylsiloxane and alpha methylstyrene, and poly(methylpentene metallethyl ether sulfone).