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
2000-08-15
2002-06-18
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
C430S325000, C430S927000
Reexamination Certificate
active
06406829
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a novel and improved chemical-amplification negative-working photoresist composition suitable for the formation of a photoresist layer on an undercoating of an organic anti-reflection film on the surface of a substrate to give a patterned resist layer of high pattern resolution and having an excellently orthogonal cross sectional profile.
Along with the trend in recent years toward higher and higher degree of integration in various semiconductor devices, the photolithographically patterned resist layer on a substrate surface is required to have a pattern resolution of as fine as 250 nm or, as a target in the coming generation, as fine as 200 nm. Needless to say, such an extremely fine pattern resolution of the patterned resist layer cannot be accomplished without an innovative improvement in the performance of the photoresist composition which may be a chemical-amplification negative-working photoresist composition.
The above mentioned chemical-amplification negative-working photoresist composition is typically formulated with an acid-curable alkali-soluble resin such as a phenolic resin, a radiation-sensitive acid-generating agent and a crosslinking agent for the resin such as an addition product of urea or melamine and formaldehyde. While it is essential for the formation of a latent image of the pattern that the pattern-wise exposure of the photoresist layer to actinic rays is followed by a post-exposure baking (PEB) treatment, it is known that the line width of the patterned resist layer is influenced by the temperature of the PEB treatment.
When the temperature of the PEB treatment deviates out of a certain range, an appropriate line width of the patterned resist layer as desired can no longer be accomplished and the troubles thereby are more serious as the fineness of patterning is increased. Accordingly, it is eagerly desired to develop a negative-working photoresist composition of which the patterning process can be performed with a greatly increased temperature latitude for the PEB treatment or, namely, the line width of the patterned resist layer is little affected by an increase or decrease of the PEB temperature.
On the other hand, it is usual that a photoresist layer of a chemical-amplification negative-working photoresist composition is formed not directly on the surface of a substrate but on an undercoating layer of an anti-reflection film of an organic anti-reflection compound formed on the substrate surface in view of the advantage relative to the pattern resolution which can be as fine as 200 nm or even finer.
It is sometimes the case, however, that, when a conventional chemical-amplification negative-working photoresist composition is used in combination with an organic anti-reflection coating compound in the form of a solution such as the most typical commercial products of the DUV Series products (each a product by Brewer Science Co.), an excellently orthogonal cross sectional profile of the patterned resist layer can hardly be obtained and the cross sectional profile is more or less trapezoidal or skirt trailing. Accordingly, it is one of the target problems in the development works for negative-working photoresist compositions to obtain a chemical-amplification negative-working photoresist composition capable of being used in combination with an organic anti-reflection coating compound without being influenced in the pattern resolution and cross sectional profile of the patterned resist layer.
SUMMARY OF THE INVENTION
The present invention accordingly has an object, in view of the above described problems and disadvantages in the conventional negative-working photoresist composition, to provide a novel and improved negative-working photoresist composition capable of giving a photoresist layer on a substrate surface, which exhibits excellent pattern resolution in a wide range of temperature for the formation of a latent image by pattern-wise exposure of the photoresist layer to actinic rays even when used in combination with an organic anti-reflection film.
Thus, the present invention provides a negative-working photoresist composition which comprises, as a uniform solution in an organic solvent:
(A) 100 parts by weight of an alkali-soluble resin;
(B) from 0.5 to 20 parts by weight of an onium salt compound of which the anionic moiety is a fluoroalkyl sulfonate anion as a radiation-sensitive acid-generating agent; and
(C) from 3 to 50 parts by weight of an ethyleneurea compound represented by the general formula
in which R
1
and R
2
are each a hydroxyl group or an alkoxy group having 1 to 4 carbon atoms and R
3
and R
4
are each a hydrogen atom, a hydroxyl group or an alkoxy group having 1 to 4 carbon atoms, as a crosslinking agent.
In addition to the above defined essential ingredients, the composition can further contain (D) from 0.01 to 1.0 part by weight of an aliphatic amine compound and/or (E) from 0.01 to 1.0 part by weight of a compound selected from the group consisting of carboxylic acids, phosphorus-containing oxoacids and esters of phosphorus-containing oxoacids.
The invention also provides a photosensitive patterning material which is an integral layered body comprising (a) a substrate, (b) a layer of an organic anti-reflection composition formed on the surface of the substrate having a thickness of 30 to 300 nm and (c) a photoresist layer formed on the anti-reflection film from the negative-working photoresist composition defined above having a thickness of 200 to 500 nm.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
As is described above, the essential ingredients in the negative-working photoresist composition of the invention include the alkali-soluble resin as the component (A), an onium salt compound as the component (B) which is an acid-generating agent and a specific ethyleneurea compound as the component (C) which is a crosslinking agent for the component (A).
This unique formulation of the photoresist composition has been established as a result of the extensive investigations undertaken by the inventors with an object to develop a photosensitive patterning material of which the total thickness of a negative-working photoresist layer and an organic anti-reflection film does not exceed 800 nm leading to an unexpected discovery that this object can well be accomplished by a negative-working photoresist composition of the above mentioned formulation.
The component (A) in the inventive negative-working photoresist composition is an alkali-soluble resinous compound which is not particularly limitative and can be selected from a variety of alkali-soluble resins conventionally used in chemical-amplification photoresist compositions. Examples of alkali-soluble resinous compound particularly preferable from the standpoint of obtaining a patterned resist layer having excellent photosensitivity, pattern resolution and cross sectional profile of the patterned resist layer include copolymeric resins having a weight-average molecular weight of 2000 to 4000 and consisting of 60 to 97% by moles of hydroxystyrene units and 40 to 3% by moles of styrene units, copolymeric resins having a weight-average molecular weight of 2000 to 4000 and consisting of 60 to 97% by moles of hydroxystyrene units and 40 to 3% by moles of styrene units, of which from 5 to 30% of the hydroxyl groups in the hydroxystyrene units are substituted by alkali-insoluble groups and polyhydroxystyrene resins having a weight-average molecular weight of 2000 to 4000, of which from 3 to 40% of the hydroxyl groups in the hydroxystyrene units are substituted by alkali-insoluble groups. More preferably, the alkali-soluble resin as the component (A) is a copolymeric resin having a weight-average molecular weight of 2000 to 4000 and consisting of 60 to 97% by moles of hydroxystyrene units and 40 to 3% by moles of styrene units when excellent orthogonality of the cross sectional profile of the patterned resist layer is essential.
The alkali-insoluble group mentioned above is a group which has an effect to decrease t
Endo Koutaro
Hirosaki Takako
Kaneko Fumitake
Kubota Naotaka
Miyairi Miwa
Ashton Rosemary
Tokyo Ohka Kogyo Co. Ltd.
Wenderoth Lind & Ponack LLP
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