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
1999-01-27
2001-04-03
Chu, John S. (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
C430S281100, C430S286100, C430S271100
Reexamination Certificate
active
06210856
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a radiation sensitive resist composition and, more particularly to a radiation sensitive resist composition which includes a silicon containing additive, a non-silicon containing base polymer, a photoacid generator and a solvent. The presence of the silicon containing additive in the radiation sensitive resist composition provides high resolution, improved profile control and improved etch resistance in oxygen reactive ion etching. The present invention also provides a film having an enriched surface layer of silicon.
The present invention is also directed to a process of providing a patterned resist film on a substrate, e.g. organic ARC or organic substrate, or other surface utilizing the radiation sensitive resist composition of the present invention.
BACKGROUND OF THE INVENTION
Single layer resists have been the main stream approach for optical lithography. To extend 248 nm optical lithography down to the sub-200 nm regime, high performance resists are required.
One way to extend 248 nm optical lithography to the sub-200 nm regime is to reduce the thickness of the resist film. Another way is to use various wave front engineering techniques, such as phase shift masks. These approaches place stringent lithographic and etch requirements on the single layer resist. These requirements include sub-200 nm resolution, good profile, high etch resistance for bottom ARC (antireflective coating) and substrate etching, and compatibility with phase shift mask technology.
Unfortunately, prior art resists are unable to meet all of these requirements due to several deficiencies which exist with the same. These deficiencies include poor resist profile due to excessive top loss, particularly at small dimensions, and insufficient etch resistance in substrate etch as a result of resist loss during opening of the underlying ARC material. Moreover, the prior art resists tend to give rise to unwanted side slopes when attenuated phase shift masks are used.
Resist compositions containing silicon either in the main resist polymer or by post-exposure surface treatment (e.g., silylation) have either failed to deliver adequate improvement in etch resistance, have had poor processing performance and/or require expensive or undesired process steps.
In view of the deficiencies with prior art resists, there is a need for a resist composition which provides, among other things, high image resolution, good process windows and excellent etch resistance.
SUMMARY OF THE INVENTION
The present invention provides novel radiation sensitive resist compositions which exhibit high image resolution, good image profile and high etch resistance. Specifically, the novel radiation sensitive resist compositions of the invention preferably comprise a silicon-containing polymeric additive, a non-silicon-containing base polymer, a photoacid generator and a solvent, wherein at least one of the polymeric materials contains acid sensitive protecting groups and both polymeric materials are aqueous base soluble after exposure processing, i.e. pre-exposure baking, exposure and post-exposure baking. The pre- or post-baking may be optionally employed herein.
The resist compositions of the invention provide sub-200 nm resolution, good profile, high etch resistance, and no unwanted side slopes when used with attenuated phase shift masks. The high etch resistance property makes the inventive resist compositions particularly suitable for use with organic ARCs.
The resist compositions of the invention are capable of forming a resist film (or layer) having a controlled vertical composition gradient such that the top portion of the unexposed portion of the resist film is less soluble in an aqueous base developer and more etch resistant during bottom ARC etching. The vertical composition gradient provided in the resist film of the invention is achieved by employing a low surface energy silicon-containing polymeric additive which migrates to the surface of the resist film during processing to form a silicon-enriched surface region that is more difficult to etch (e.g., compared to a silicon-free resist or a resist containing a uniform distribution of the silicon-containing polymeric additive). The silicon-containing polymeric additive is preferably hydrophobic.
The radiation sensitive resist compositions of the invention may optionally contain other components such as a base, a photosensitizer and a surfactant.
Another aspect of the invention relates to a film which comprises a silicon-containing polymeric additive and a non-silicon-containing base polymer, wherein the film has a silicon-enriched upper region.
In another aspect, the invention encompasses a method of forming a patterned resist film on a substrate. The method includes applying a layer of the radiation sensitive resist composition of the invention onto a substrate, patternwise exposing the layer to radiation to create regions of enhanced aqueous alkaline solubility, and removing the regions of enhanced aqueous alkaline solubility by application of an aqueous developer having a pH in excess of 7 to provide a patterned resist film having regions of differentially higher silicon content at the upper surface thereof.
The resist compositions of the invention may be used in single layer or multilayer (e.g., so-called bi-layer) resist photolithographic processes.
DETAILED DESCRIPTION OF THE INVENTION
As stated above, the resist compositions of the invention preferably comprise a silicon-containing polymeric additive, a non-silicon containing base polymer, a photoacid generator and a solvent, wherein at least one of the polymeric compounds (i.e., the polymeric additive and/or the base polymer) contains a acid sensitive protecting groups.
The silicon-containing polymeric additive employed in the invention may contain silicon in its polymer backbone, contain silicon as a substituent to a polymer backbone or contain silicon both in the polymer backbone and as a substituent. The silicon containing polymeric additive may additionally contain a acid sensitive protecting groups.
Where silicon is incorporated into the polymer backbone, the silicon-containing polymeric additive employed in the present invention may be a homopolymer or a copolymer. Suitable types of such silicon-containing polymers include homopolymers or copolymers containing at least one monomer selected from the group consisting of a siloxane, a silane, a silsesquioxane and a silyne. Highly preferred silicon-backbone polymers are selected from the group consisting of poly(hydroxyphenyl alkyl)silsesquioxanes and poly (hydroxyphenyl alkyl) siloxanes, wherein alkyl is a C
1-30
moiety. These preferred silicon-containing polymers are preferably fully or partially protected with acid-sensitive protecting groups.
Where the silicon-containing polymeric additive contains a silicon-containing substituent bonded to the polymeric backbone, the silicon-containing polymeric additive may be a homopolymer or copolymer containing at least one monomer having a silicon-containing substituent. The silicon-containing substituent may or may not be acid sensitive. Typically, however the substituent is acid sensitive when containing a C
2
alkyl moiety. Preferably, the silicon-containing substituent is attached to a monomer selected from the group consisting of hydroxystyrene, an acrylate, a methacrylate, an acrylamide, a methacrylamide, itaconate, an itaconic half ester or a cycloolefin. Preferred silicon-containing substituents include: siloxane, silane and cubic silsesquioxanes. The silicon-containing polymer may further include silicon-free monomers such as those selected from the group consisting of styrene, hydroxystyrene, acrylic acid, methacrylic acid, itaconic acid and an anhydride such as maleic anhydride and itaconic anhydride.
Preferred monomers containing silicon-containing substituents are trimethylsilyl alkyl acrylate, trimethylsilyl alkyl methacrylate, trimethylsilyl alkyl itaconate, tris(trimethylsilyl)silyl alkyl acrylate tris(trimethylsilyl)silyl alkyl methacrylate, tris(trimet
Hughes Timothy M.
Jordhamo George M.
Katnani Ahmad D.
Lin Qinghuang
Moreau Wayne M.
Capella, Esq. Steven
Chu John S.
Clarke Yvette M.
International Business Machines - Corporation
Scully Scott Murphy & Presser
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