Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Radiation sensitive composition or product or process of making
Reexamination Certificate
2001-03-23
2003-07-15
Ashton, Rosemary (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Radiation sensitive composition or product or process of making
C430S325000, C430S326000, C430S907000, C430S914000, C430S331000, C526S242000, C526S250000, C526S255000, C526S247000, C526S249000, C526S253000, C526S254000
Reexamination Certificate
active
06593058
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention pertains to photoimaging and, in particular, the use of photoresists (positive-working and/or negative-working) for imaging in the production of semiconductor devices. The present invention also pertains to novel fluorine-containing polymer compositions which are useful as base resins in resists and potentially in many other applications.
2. Description of Related Art
Polymer products are used as components of imaging and photosensitive systems and particularly in photoimaging systems such as those described in
Introduction to Microlithography, Second Edition
by L. F. Thompson, C. G. Willson, and M. J. Bowden, American Chemical Society, Washington, DC, 1994. In such systems, ultraviolet (UV) light or other electromagnetic radiation impinges on a material containing a photoactive component to induce a physical or chemical change in that material. A useful or latent image is thereby produced which can be processed into a useful image for semiconductor device fabrication.
Although the polymer product itself may be photoactive, generally a photosensitive composition contains one or more photoactive components in addition to the polymer product. Upon exposure to electromagnetic radiation (e.g. UV light), the photoactive component acts to change the rheological state, solubility, surface characteristics, refractive index, color, electromagnetic characteristics or other such physical or chemical characteristics of the photosensitive composition as described in the Thompson et al. publication supra.
For imaging very fine features at the submicron level is semiconductor devices, electromagnetic radiation in the far or extreme ultraviolet (UV) is needed. Positive working resists generally are utilized for semiconductor manufacture. Lithography in the UV at 365 nm (I-line) using novolak polymers and diazonaphthoquinones as dissolution inhibitors is a currently established chip technology having a resolution limit of about 0.35-0.30 micron. Lithography in the far UV at 248 nm using p-hydroxystyrene polymers is known and has a resolution limit of 0.35-0.18 nm. There is strong impetus for future photolithography at even shorter wavelengths, due to a decreasing lower resolution limit with decreasing wavelength (i.e., a resolution limit of 0.18-0.12 micron for 193 nm imaging). Photolithography using 193 nm exposure wavelength (obtained from an argon fluorine (ArF) excimer laser) is a leading candidate for future microelectronics fabrication using 0.18 and 0.13 &mgr;m design rules. Photolithography using 157 nm exposure wavelength (obtained using an F
2
laser source) may be used for future microelectronics fabrication using 0.100 &mgr;m or less design rules. The opacity of traditional near UV and far UV organic photoresists at 193 nm and shorter wavelengths precludes their use in single-layer schemes at these wavelengths.
Some resist composition suitable for imaging at 193 nm are known. For example, photoresist compositions comprising cycloolefin-maleic anhydride alternating copolymers have been shown to be useful for imaging of semiconductors at 193 nm (see F. M. Houlihan et al,
Macromolecules,
30, pages 6514-6534 (1997); T. Wallow et al, SPIE, Vol. 2724, pages 355-364; and F. M. Houlihan et al.,
Journal of Photopolymer Science and Technology,
10, No. 3, pages 511-520 (1997)). Several publications are focused on 193 nm resists (i.e., U. Okoroanyanwu et al, SPIE, Vol. 3049, pages 92-103; R. Allen et al., SPIE, Vol. 2724, pages 334-343; and Semiconductor International, September 1997, pages 74-80). Compositions comprising addition polymers and/or ROMP (ring-opening methathesis polymerization) of functionalized norbornenes have been disclosed (e.g., PCT WO 97/33198 (Sep. 12, 1997) to B. F. Goodrich). Homopolymers and maleic anhydride copolymers of norbornadiene and their use in 193 nm lithography have been disclosed (J. Niu and J. Frechet, Angew. Chem. Int. Ed., 37, No. 5, (1998), pages 667-670). No resist compositions for imaging at 157 nm have been disclosed.
Copolymers of fluoroolefin monomers and cyclic unsaturated monomers are known (U.S. Pat. Nos. 5,177,166 and 5,229,473 to Daikin Industries, Ltd.). These patents do not disclosure the use of these copolymers in any photosensitive compositions. Copolymers of certain fluorinated olefins with certain vinyl esters and vinyl ethers are known. For example, the copolymer of TFE with cyclohexanecarboxylate, vinyl ester (Japanese Patent Appl. JP 03281664 to Dainippon Ink and Chemicals) and with cyclohexyl vinyl ether (Japanese Patent Appl. JP 54046286 to Asahi Glass Co.) are known. Copolymers of TFE and vinyl esters, such as vinyl acetate, and use of these copolymers in photosensitive compositions for refractive index imaging (e.g. holography) are known (U.S. Pat. No. 4,963,471 to DuPont). All of the prior art on copolymers comprising fluorinated olefins and vinyl esters of formula CH
2
═CHO
2
CR and vinyl ethers of formulae CH
2
═CHOCH
2
R or CH
2
═CHOR, have R groups with a C:H ratio that is relatively low and which is less than 0.58.
Homopolymers and copolymers of certain monomers that possess properties of being both cyclic and fluorine-containing are known as well as their application as components in photodefinable fluorine-containing polymer films (Japanese Kokai No Hei 9(1997)-43856. There is no teaching in this reference of homopolymers or copolymers comprised of polycyclic comonomers as photoresist components. Furthermore, there is no teaching that the compositions disclosed in this Japanese Kokai could be used in photoresists with imaging effected at far UV wavelengths of less than 180 nm.
U.S. Pat. No. 5,665,527 discloses a process for generating a negative tone resist image by coating a silicon wafer with a copolymer resist solution of pentafluoropropyl methacrylate-t-butyl methacrylate in a solvent, and then exposing at 193 nm and developing with a carbon dioxide critical fluid.
—EP 0789 278 A2, published on Aug. 13, 1997, discloses a photoresist comprising a resin containing an alicyclic skeleton selected from general formulas 1 and 2 shown below, and a radiation-sensitive acid-generating agent:
wherein n is 0 or 1, A and B represent independently a hydrogen atom, a halogen atom, a monovalent hydrocarbon group having 1 to 10 carbon atoms or a monovalent halogenated hydrocarbon group having 1 to 10 carbon atoms, and X and Y represent independently a hydrogen atom, a halogen atom, a monovalent hydrocarbon group having 1 to 10 carbon atoms, a monovalent halogenated hydrocarbon group having 1 to 10 carbon atoms or an acid-cleavable group, provided that at least one of X and Y is an acid-cleavable group. A photoresist pattern may be formed by exposing the photoresist to far UV radiation such as KrF excimer laser (wavelength of 248 nm) or ArF excimer laser (wavelength of 193 nm).—
There is a critical need though for other novel resist compositions for use at 193 nm or lower, and particularly at 157 nm, that have not only high transparency at these short wavelengths but also other suitable key properties, including good plasma etch resistance and adhesive properties.
SUMMARY OF THE INVENTION
The present invention in some embodiments comprises
(a) a fluorine-containing copolymer comprising a repeat unit derived from at least one ethylenically unsaturated compound characterized in that at least one ethylenically unsaturated compound is polycyclic and at least one ethylenically unsaturated compound contains at least one fluorine atom covalently attached to an ethylenically unsaturated carbon atoms; and
(b) at least one photoactive component;
wherein the fluorine-containing copolymer does not contain aromatic functionality but contains sufficient functionality to render the photoresist developable so as to produce a relief image, upon imagewise exposure to ultraviolet radiation having wavelength of ≦365 nm.
In one preferred embodiment, at least one ethylenically unsaturated compound is selected from the group consisting of:
wherein:
each of m
Feiring Andrew Edward
Feldman Jerald
Ashton Rosemary
E. I. du Pont de Nemours and Company
Lee Sin J.
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