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
2000-06-23
2002-07-16
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
C430S313000, C430S326000, C430S277100, C430S278100
Reexamination Certificate
active
06420084
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.), lithography is used to obtain patterned structures of various materials such as insulators, semiconductors and/or metals in a sequence leading to the achievement of the desired structure.
Most lithographic processes (excluding so-called direct-write techniques) typically employ some type of patterned mask through which the imaging radiation is projected onto the resist material to be patterned on the substrate of interest. Typically, the mask itself is formed by a lithographic technique such as direct-write electron beam lithography or in some instances by projection UV lithography (especially deep UV—248 nm) using an appropriate resist material. Typically, the mask comprises a patterned metal layer(s) (e.g., chromium) on a quartz plate (or other transparent plate).
A resist composition must possess desirable radiation response characteristics to enable image resolution upon exposure to a desired radiation development. Thus, a pattern wise exposed positive resist must be capable of appropriate response (i.e. selective dissolution of exposed areas) to a developer to yield the desired resist structure. Given the extensive experience in the lithographic arts with the use of aqueous alkaline developers, it is important to achieve appropriate dissolution behavior in such commonly used developer solutions.
The resist composition must also possess suitable chemical and mechanical properties to enable transfer to the image from the patterned resist to an underlying substrate layer(s). Typically, pattern transfer is performed by some form of wet chemical etching or ion etching. The ability of the patterned resist layer to withstand the pattern transfer etch process (i.e., the etch resistance of the resist layer) is an important characteristic of the resist composition. In the case of typical mask making processes, a chlorine-containing etchant such as combination of Cl
2
and O
2
is generally a preferred etchant. Halogen-based etchants other than fluorine (i.e., Cl, Br, or I) are also a preferred etchant for patterning metals and semiconductor (e.g., polycrystalline silicon) materials.
With demands for finer detailed masks and patterned metals/semiconductor materials, the performance of higher atomic weight halogen-based (i.e., Cl, Br, or I) etching processes has been increasingly problematic due to excessive erosion of the resist during the etching step needed for pattern transfer. Thus, there is a need for improved processes for making patterned metal and/or semiconductor features and especially for making lithographic masks containing patterned metal layers.
SUMMARY OF THE INVENTION
The invention provides improved resist compositions and lithographic methods using the resist compositions of the invention. The resist compositions of the invention are acid-catalyzed resists which are characterized by the presence of an SiO-containing polymer. The invention also encompasses methods of forming patterned material layers (especially conductive, semiconductive, or magnetic material structures) using the combination of the SiO-containing resist and a halogen compound-containing pattern transfer etchant where the halogen is Cl, Br or I.
In one aspect, the invention encompasses a positive resist composition, the composition comprising:
(a) a polymeric component, at least a portion of the polymeric component containing SiO moieties, at least a portion of the polymeric component containing pendant acid labile moieties which inhibit solubility of the resist in aqueous alkaline solutions, and at least a portion of the polymeric component containing pendant polar moieties which promote alkaline solubility of the resist in aqueous alkaline solutions, and
(b) a radiation-sensitive acid generator.
The polymeric component preferably includes a silsesquioxane polymer. The acid labile solubility-inhibiting functionality may be present on the same polymer which contains the SiO moieties or may be present on a separate polymer forming part of the total polymeric component.
In another aspect, the invention encompasses a method of creating a patterned material structure on a substrate, the method comprising:
(a) providing a substrate having material layer thereon to be patterned,
(b) providing a layer of positive resist over the material layer, the radiation-sensitive resist comprising a polymeric component, at least a portion of the polymeric component containing SiO moieties, at least a portion of the polymeric component containing pendant acid labile moieties which inhibit solubility of the resist in aqueous alkaline solutions, and at least a portion of the polymeric component containing pendant polar moieties which promote alkaline solubility of the resist in aqueous alkaline solutions,
(c) pattern wise exposing portions of the resist to imaging radiation,
(d) removing the exposed portions of the resist to form spaces defined by remaining unexposed portions of the resist layer,
(e) removing portions of the material layer at the spaces by contacting the material layer with an etchant compound comprising a halogen atom selected from the group consisting of Cl, Br, and I, and
(f) removing any remaining portions of the resist layer.
The material layer provided in step (a) is preferably selected from the group consisting of metals and semiconductors, more preferably a chromium-containing metal.
These and other aspects of the invention are discussed in further detail below.
DETAILED DESCRIPTION OF THE INVENTION
The invention provides improved resist compositions and lithographic methods using the resist compositions of the invention. The resist compositions of the invention are acid-catalyzed resists which are characterized by the presence of an SiO-containing polymer. The invention also encompasses methods of forming patterned material layers (especially conductive, semiconductive, or magnetic material structures) using the combination of the SiO-containing resist and a halogen compound-containing pattern transfer etchant where the halogen is Cl, Br or I.
The resist compositions of the invention are characterized in part by the presence of a polymeric component where:
(i) at least a portion of the polymeric component contains SiO moieties,
(ii) at least a portion of the polymeric component contains pendant acid labile moieties which inhibit solubility of the resist in aqueous alkaline solutions, and
(iii) at least a portion of the polymeric component containing pendant polar moieties which promote alkaline solubility of the resist in aqueous alkaline solutions.
The portion of the polymeric component containing SiO moieties may have the SiO moieties present as part a polymer backbone or in groups which are pendant from the polymer backbone. Preferably, the SiO moieties form part of a polymer backbone structure. More preferably, the SiO moieties are present as part of an organosiloxane polymer, more preferably a silsesquioxane polymer. Such SiO containing polymers preferably contain monomers of the structure:
where R is a group which contains (i) a polar moiety which promotes alkaline solubility of the resist in aqueous alkaline solutions, (ii) a modulating moiety which increases the glass transition temperature and/or modulates the dissolution rate of the polymeric component, (iii) acid labile moiety which inhibits solubility of the resist in aqueous alkaline solutions, and x is about 1 to 1.5. Where the SiO-containing polymer is a silsesquioxane polymer x is about 1.5.
The SiO-containing polymer preferably contains a combination of such monomers (I) having different R groups selected from (i)-(iii). Thus, the SiO-containing polymer preferably contains one or more monomers selected from the group consisting of:
where R
1
contains a polar moiety which promotes alkaline solubility of the resist in aqueous alkaline solutions, R
2
contains a modulating group which increases the glass transition temperature and/or modu
Angelopoulos Marie
Aviram Ari
Guarnieri C. Richard
Huang Wu-Song
Kwong Ranee
Ashton Rosemary
Capella Steven
International Business Machines - Corporation
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