Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Making printing plates
Reexamination Certificate
2002-06-07
2003-01-07
Le, Hoa Van (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Making printing plates
Reexamination Certificate
active
06503692
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.
Also, where the underlying material layer is excessively reflective of the imaging radiation used to pattern the resist layer, typically a thin antireflective coating may be applied between the underlying layer and the resist layer. In some instances, the antireflection and hardmask functions may be served by the same material.
While many hardmask and antireflective coating materials exist in the prior art, there is a continued desire for improved 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, and/or high temperature baking. It would be desirable to have antireflective coating/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.
SUMMARY OF THE INVENTION
The invention encompasses novel antireflective coating/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 antireflective compositions are characterized by the presence of an SiO containing polymer having pendant chromophore moieties. The invention also encompasses lithographic structures containing the antireflective coating/hardmask composition of the invention, methods of making such lithographic structures and methods of using such lithographic structures to pattern underlying material layers on a substrate.
In one aspect, the invention encompasses a composition suitable for formation of a spin-on antireflective layer, the composition comprising:
(a) a polymer containing SiO moieties and chromophore 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.
In another aspect, the invention encompasses a lithographic structure on a substrate, the structure comprising:
(a) an antireflective layer comprising a crosslinked polymer containing SiO moieties and chromophore moieties, and
(b) a radiation-sensitive imaging layer over the antireflective layer.
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 layer over the material layer, the antireflective layer comprising a crosslinked polymer containing SiO moieties and chromophore moieties,
(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.
The invention also encompasses methods of making lithographic structures. These and other aspects of the invention are discussed in further detail below.
DETAILED DESCRIPTION OF THE INVENTION
The invention encompasses novel antireflective coating/hardmask compositions which are useful in lithographic processes. These antireflective compositions are characterized by the presence of an SiO-containing polymer having pendant chromophore moieties. The invention also encompasses lithographic structures containing the antireflective coating/hardmask composition of the invention, methods of making such lithographic structures and methods of using such lithographic structures to pattern underlying material layers on a substrate.
The antireflective compositions of the invention generally comprise:
(a) a polymer containing SiO moieties and chromophore moieties,
(b) a crosslinking component, and
(c) an acid generator.
The polymer containing SiO moieties may be a polymer containing SiO moieties in the polymer backbone and/or in pendant groups. Preferably, the polymer contains SiO moieties in its backbone. The polymer is preferably an orga-nosiloxane, more preferably organosilsesquioxane. The polymer should have solution and film-forming characteristics conducive to forming a layer by conventional spin-coating. In addition to the chromophore moieties discussed below, the SiO-containing polymer also preferably contains a plurality of reactive sites distributed along the polymer for reaction with the crosslinking component.
Examples of suitable polymers include polymers having the silsesquioxane (ladder or network) structure. Such polymers preferably contain monomers having structures (I) and (II) below:
where R
1
comprises a chromophore and R
2
comprises a reactive site for reaction with the crosslinking component.
Alternatively, general linear organosiloxane polymers containing monomers (III) and (IV) can be used:
where R
1
and R
2
are as described above. In some cases, the polymer contain various combinations of monomers (I)-(IV) such that the average structure for R
1
-containing monome
Angelopoulos Marie
Aviram Ari
Guarnieri C. Richard
Huang Wu-Song
Kwong Ranee
Le Hoa Van
Steven Capella
LandOfFree
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