Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Forming nonplanar surface
Reexamination Certificate
2000-07-26
2003-05-13
Baxter, Janet (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Forming nonplanar surface
C430S313000, C430S318000, C430S270100, C430S905000, C430S914000
Reexamination Certificate
active
06562554
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATIONS
Filed simultaneously with this application are U.S. patent application Ser. No. 09/266,343, titled “Photoresist Compositions with Cyclic Olefin Polymers and Hydrophobic Non-Steroidal Alicyclic Additives”; U.S. patent application Ser. No. 09/266,342, titled “Photoresist Compositions with Cyclic Olefin Polymers and Additive”; and U.S. patent application Ser. No. 09/266,344, titled “Photoresist Compositions with Cyclic Olefin Polymers and Saturated Steroid Additives”. The disclosures of the above applications are incorporated herein by reference.
BACKGROUND OF THE INVENTION
In the microelectronics industry as well as in other industries involving construction of microscopic structures (e.g. micromachines, magnetoresistive heads, etc.), there is a continued desire to reduce the size of structural features. In the microelectronics industry, the desire is to reduce the size of microelectronic devices and/or to provide greater amount of circuitry for a given chip size.
The ability to produce smaller devices is limited by the ability of photolithographic techniques to reliably resolve smaller features and spacings. The nature of optics is such that the ability to obtain finer resolution is limited in part by the wavelength of light (or other radiation) used to create the lithographic pattern. Thus, there has been a continual trend toward use of shorter light wavelengths for photolithographic processes. Recently, the trend has been to move from so-called I-line radiation (350 nm) to 248 nm radiation.
For future reductions in size, the need to use 193 nm radiation appears likely. Unfortunately, photoresist compositions at the heart of current 248 nm photolithographic processes are typically unsuitable for use at shorter wavelengths.
While a photoresist composition must possess desirable optical characteristics to enable image resolution at a desired radiation wavelength, the photoresist composition must also possess suitable chemical and mechanical properties to enable transfer to the image from the patterned photoresist to an underlying substrate layer(s). Thus, a patternwise exposed positive photoresist must be capable of appropriate dissolution response (i.e. selective dissolution of exposed areas) to yield the desired photoresist structure. Given the extensive experience in the photolithographic arts with the use of aqueous alkaline developers, it is important to achieve appropriate dissolution behavior in such commonly used developer solutions.
The patterned photoresist structure (after development) must be sufficiently resistant to enable transfer of the pattern to the underlying layer(s). Typically, pattern transfer is performed by some form of wet chemical etching or ion etching. The ability of the patterned photoresist layer to withstand the pattern transfer etch process (i.e., the etch resistance of the photoresist layer) is an important characteristic of the photoresist composition.
While some photoresist compositions have been designed for use with 193 nm radiation, these compositions have generally failed to deliver the true resolution benefit of shorter wavelength imaging due to a lack of performance in one or more of the above mentioned areas. Thus, there is a need for photoresist compositions that are imageable with shorter wavelength radiation (e.g., 193 nm ultraviolet radiation) while possessing good developability and etch resistance.
SUMMARY OF THE INVENTION
The invention provides photoresist compositions which are capable of high resolution lithographic performance, especially using 193 nm imaging radiation. The photoresist compositions of the invention possess the combination of imageability, developability and etch resistance needed to provide pattern transfer at very high resolutions which are limited only by the wavelength of imaging radiation. The photoresist compositions of the invention are generally characterized by the presence of (a) cyclic olefin polymers, and (b) a hydrophobic non-steroidal multi-alicyclic component containing plural acid labile links (“HNMP”).
The invention also provides photolithographic methods using the photoresist compositions of the invention to create photoresist structures and methods using the photoresist structures to transfer patterns to an underlying layer(s). The photolithographic methods of the invention are preferably characterized by the use of 193 nm ultraviolet radiation patternwise exposure. The methods of the invention are preferably capable of resolving features of less than about 150 nm in size, more preferably less than about 115 nm in size (using 0.68 numerical aperture optics) without the use of a phase shift mask.
In one aspect, the invention encompasses a photoresist composition comprising:
(a) a cyclic olefin polymer comprising:
i) cyclic olefin units having polar functional moieties, and
ii) cyclic olefin units having acid labile moieties that inhibit solubility in aqueous alkaline solutions,
(b) a photoactive component, and
(c) a hydrophobic non-steroidal multi-alicyclic component containing plural acid labile links.
The cyclic olefin polymers of the invention preferably consist essentially of cyclic olefin monomeric units; more preferably they consist essentially of units i) and ii). Units i) preferably comprise acidic polar moieties having a pK
a
≦13. The HNMP component preferably comprises at least two C
7
or higher alicyclic moieties. Acid cleaving of the HNMP component preferably results in the formation of a compound having plural acidic polar functional groups and/or plural compounds each having at least one acidic polar group.
In another aspect, the invention encompasses a method of creating a patterned photoresist structure on a substrate, the method comprising:
(a) providing a substrate having a surface layer of the photoresist composition of the invention,
(b) patternwise exposing the photoresist layer to radiation whereby portions of the photoresist layer are exposed to radiation, and
(c) contacting the photoresist layer with an aqueous alkaline developer solution to remove the exposed portions of the photoresist layer to create the patterned photoresist structure.
Preferably, the radiation used in step (b) in the above method is 193 nm ultraviolet radiation.
The invention also encompasses processes for making conductive, semiconductive, magnetic or insulative structures using the patterned photoresist structures containing the compositions of the invention.
These and other aspects of the invention are discussed in further detail below.
DETAILED DESCRIPTION OF THE INVENTION
The photoresist compositions of the invention are generally characterized by the presence of (a) a cyclic olefin polymer, and (b) a hydrophobic non-steroidal multi-alicyclic component containing plural acid labile links. The cyclic olefin polymer preferably contains i) cyclic olefin units having polar functional moieties, and ii) cyclic olefin units having acid labile moieties that inhibit solubility in aqueous alkaline solutions. These compositions are especially capable of providing high resolution photolithographic patterns using 193 nm radiation with good developability and pattern transfer characteristics.
The invention further encompasses patterned photoresist structures containing the photoresist compositions of the invention, as well as processes for creating the photoresist structures and using the photoresist structures to form conductive, semiconductive and/or insulative structures.
The photoresist compositions of the invention preferably comprise:
(a) a cyclic olefin polymer comprising:
i) cyclic olefin units having polar functional moieties selected from acidic moieties that promote solubility in aqueous alkaline solutions and non-acidic polar moieties, and
ii) cyclic olefin units having acid labile moieties that inhibit solubility in aqueous alkaline solutions,
(b) a photoactive component, and
(c) a hydrophobic non-steroidal multi-alicyclic component containing plural acid labile links (HMNP).
Cyclic olefin units i) may be any cyclic olefin monomeric unit having an ac
Maniscalco Joseph F.
Varanasi Pushkara Rao
Baxter Janet
Capella Steven
International Business Machines - Corporation
Lee Sin J.
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