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
2002-04-16
2004-05-04
Huff, Mark F. (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Radiation sensitive composition or product or process of making
C430S271100, C430S272100, C430S311000, C430S313000, C430S510000, C430S512000, C430S950000
Reexamination Certificate
active
06730454
ABSTRACT:
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.
Effective lithographic techniques are essential to achieving reduction of feature sizes. Lithography impacts the manufacture of microscopic structures not only in terms of directly imaging patterns on the desired substrate, but also in terms of making masks typically used in such imaging. Typical lithographic processes involve formation of a patterned resist layer by patternwise exposing the radiation-sensitive resist to an imaging radiation. The image is subsequently developed by contacting the exposed resist layer with a material (typically an aqueous alkaline developer) to selectively remove portions of the resist layer to reveal the desired pattern. The pattern is subsequently transferred to an underlying material by etching the material in openings of the patterned resist layer. After the transfer is complete, the remaining resist layer is then removed.
For some lithographic imaging processes, the resist used does not provide sufficient resistance to subsequent etching steps to enable effective transfer of the desired pattern to a layer underlying the resist. In many instances (e.g., where an ultrathin resist layer is desired, where the underlying material to be etched is thick, where a substantial etching depth is required, and/or where it is desired to use certain etchants for a given underlying material), a so-called hardmask layer is used intermediate between the resist layer and the underlying material to be patterned by transfer from the patterned resist. The hardmask layer receives the pattern from the patterned resist layer and should be able withstand the etching processes needed to transfer the pattern to the underlying material.
While many hardmask materials exist in the prior art, there is a continued desire for improved hardmask compositions. Many of the prior art materials are difficult to apply to the substrate, e.g., they may require use of chemical or physical vapor deposition, special solvents, and/or high temperature baking. It would be desirable to have hardmask compositions which could be applied by spin-coating techniques without need for a high temperature bake. Additionally, it is desirable to have hardmask compositions which can be easily etched selective to the overlying photoresist while being resistant to the etch process needed to pattern the underlying layer, especially where the underlying layer is a metal layer. It is also desired to provide adequate shelf-life and to avoid adverse interaction with the imaging resist layer (e.g., by acid contamination from the hardmask). Additionally, it is desired to have hardmask compositions which possess the desired optical characteristics relative to shorter wavelength (e.g., <200 nm) imaging radiation.
SUMMARY OF THE INVENTION
The invention encompasses novel antireflective hardmask compositions which are useful in lithographic processes. These compositions provide outstanding optical, mechanical and etch selectivity properties while being applicable using spin-on application techniques. The compositions also have good shelf-life and minimal or no acid contaminant content. The antireflective hardmask compositions are characterized by the presence of an SiO-containing polymer having chromophore moieties and transparent moieties. The invention also encompasses methods of using the hardmask compositions of the invention to pattern underlying material layers on a substrate. The invention also encompasses lithographic structures such as a patterned combination of resist layer and hardmask layer.
In one aspect, the invention encompasses a composition suitable for formation of a spin-on antireflective hardmask layer, the composition comprising:
(a) an SiO-containing polymer having chromophore moieties and transparent moieties,
(b) a crosslinking component, and
(c) an acid generator.
The SiO moieties are preferably selected from the group consisting of siloxane moieties and silsesquioxane moieties. The SiO moieties are preferably in a backbone portion of the polymer. The SiO-containing polymer also preferably contains a plurality of reactive sites distributed along the polymer for reaction with the crosslinking component. The acid generator is preferably a thermally activated acid generator. The transparent moieties are preferably bulky (C
2
or higher) or fluorine-containing moieties which are substantially transparent to the desired imaging radiation.
In another aspect, the invention encompasses method of forming a patterned material feature on a substrate, the method comprising:
(a) providing a material layer on a substrate,
(b) forming an antireflective hardmask layer of the invention over the material layer,
(c) forming a radiation-sensitive imaging layer over the antireflective layer,
(d) patternwise exposing the imaging layer to radiation thereby creating a pattern of radiation-exposed regions in the imaging layer,
(e) selectively removing portions of the imaging layer and the antireflective layer to expose portions of the material layer, and
(f) etching the exposed portions of the material layer, thereby forming the patterned material feature.
The material to be patterned is preferably a conductive, semiconductive, magnetic or insulative material, more preferably a metal. The SiO moieties are preferably in a backbone portion of the polymer. The SiO-containing polymer also preferably contains a plurality of reactive sites distributed along the polymer for reaction with the crosslinking component.
These and other aspects of the invention are discussed in further detail below.
DETAILED DESCRIPTION OF THE INVENTION
The invention encompasses novel antireflective hardmask compositions which are useful in lithographic processes. These antireflective hardmask compositions are characterized by the presence of an SiO-containing polymer having chromophore moieties and transparent moieties. The invention also encompasses methods of using the antireflective hardmask compositions of the invention to pattern underlying material layers on a substrate. The invention also encompasses lithographic structures such as a patterned combination of resist layer and hardmask layer.
The antireflective hardmask compositions of the invention generally comprise:
(a) an SiO-containing polymer having chromophore moieties and transparent moieties,
(b) a crosslinking component, and
(c) an acid generator.
The SiO-containing polymer preferably contains SiO moieties in its backbone. The polymer is preferably an organosiloxane, more preferably organosilsesquioxane. The polymer should have solution and film-forming characteristics conducive to forming a layer by conventional spin-coating.
In general, the polymer preferably contains one or more monomers having structures selected from (I)-(III) below:
where x is from about 1 to about 1.5. R
1
comprises a chromophore moiety; R
2
comprises a transparent moiety; R
3
comprises a reactive site for reaction with the crosslinking component. For linear organosiloxane polymers, x would equal about 1. For silsesquioxane polymers, x would equal about 1.5. In some instances, multiple functional moieties may be present on the same monomer (e.g., a reactive group and a chromophore). Generally, silsesquioxane polymers are preferred on the basis of superior etch resistance. If the ordinary organosiloxane polymers are used, then preferably, the degree of crosslinking is increased compared to formulations based on silsesquioxanes.
The chromophore-containing groups R
1
may contain any suitable chromophore which (i) can be grafted onto the SiO-containing polymer (ii) has suitable radiation absorption characteristics, and (iii) does not adversely affect the performance of the layer or
Angelopoulos Marie
Babich Katherina
Brock Phillip
Huang Wu-Song
Mahorowala Arpan P.
Barreca Nicole
Capella Steven
Huff Mark F.
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