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
2000-10-31
2003-03-04
Baxter, Janet (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
C430S311000, C430S313000, C430S317000, C430S328000, C430S343000, C568S017000, C568S028000, C568S035000, C568S077000
Reexamination Certificate
active
06528232
ABSTRACT:
BACKGROUND OF THE INVENTION
(a) Field of the Invention
The present invention relates to a novel sulfonium salt compound employable as a photo-acid generator for a chemically amplified photoresist material, a chemically amplified photoresist composition using the novel sulfonium salt compound as the photo-acid generator, and a method for patterning by using the photoresist composition. More concretely, the present invention relates to the novel sulfonium salt compound suitably used as the photo-acid generator for the chemically amplified photoresist material having an exposing wavelength in a range from a far ultraviolet ray to a vacuum ultraviolet ray having a wavelength between 130 nm and 220 nm.
(b) Description of the Related Art
Higher density, higher integration or higher speed is required in a highly integrated circuit element represented by a semiconductor device such as a DRAM (dynamic random access memory). Accompanied thereby, the establishment of the fine processing technology in a range of half-micron order, for example, the photolithographic technology for forming fine patterns is required more and more stringently in the field of manufacturing electronic devices.
A process of implementing the fine patterns in the photolithographic technology includes the shortening of a wavelength of an exposing ray used in the formation of the patterned resist. Generally, the degree of optical resolution (R) can be represented by the Rayleighs equation, that is, R=k·&lgr;/NA (wherein &lgr; is a wavelength of an exposing ray, NA is numerical aperture and “k” is a process factor). In order to progress the formation of fine patterns, the higher optical resolution is required in the optical system used therein, or the wavelength “&lgr;” of the exposing ray is shortened for reducing the degree of the resolution “R” of the optical system.
In the manufacture of a DRAM of 256 megabits, for example, the degree of resolution of line-and-space having the minimum pattern dimension of 0.22 &mgr;m is required, and a KrF excimer laser (wavelength: 248 nm) is used as a light source. In the manufacture of an advanced DRAM of 1 gigabit or more, the patterning dimension becomes 0.15 &mgr;m or less requiring the finer processing technique, and an ArF excimer laser (wavelength: 193 nm) and an F
2
excimer laser (wavelength: 157 nm) having a shorter wavelength ray (a far ultraviolet ray and a vacuum ultraviolet ray) are efficiently utilized and required. Currently, the lithography using the ArF excimer laser is extensively researched [refer to Journal of Photopolymer Science and Technology, vol.9, no.3, p.387 to 397 (1996)].
In the use of the ArF excimer laser and the F
2
excimer laser, the higher sensitivity is requested in the development of resist for exposure in addition to the higher resolution responding to the fine processing dimension because the lifetime of a gas used in these lasers is short and the damage of a lens generated by a laser ray is large. A chemically amplified photoresist is well known utilizing a photo-acid generator as a sensitized material for obtaining the higher sensitivity of the resist. A representative example is described in JP-A-2(1990)-27660 showing a resist formed by a combination of poly(p-tert-butoxy carbonyloxy-&agr;-methylstyrene) and triphenylsulfonium hexafluoro-arsenate acting as a photo-acid generator. The chemically amplified photoresist is currently used for the KrF excimer laser [for example, refer to Hiroshi Ito and C. Grantwilson, American Chemical Society Symposium Series, vol.242, p.11 to 23 (1984)].
The chemically amplified photoresist characteristically generates a protonic acid from the photo-acid generator contained therein by means of irradiation of light, and the protonic acid reacts with resist resin under existence of an acid catalyst by a thermal treatment after exposure. By using the acid catalysis, the considerably higher sensitivity can be attained compared with a conventional resist having a photoreaction efficiency (reaction per one photon) of 1 or less. Most of the resists currently developed are chemically amplified ones. An example of the photo-acid generator currently used includes a triphenyl- sulfonium salt derivative developed by J. V. Crivello described in J. Org.Chem., vol.43, no.15, p.3055 to 3058 (1978).
A representative example of the photo-acid generator currently used in the chemically amplified resist for the ArF excimer laser already proposed is the triphenylsulfonium salt derivative [refer to, for example, Nozaki, et al., Journal of Photopolymer Science and Technology, vol.10, no.4, p.545 to 550 (1997) or Yamachika, et al., Journal of Photopolymer Science and Technology, vol.12, no.4, p.553 to 560 (1999)]. Since, however, these triphenylsulfonium salt derivatives strongly absorb light having a wavelength of 220 nm or less, the transparency of the resist is reduced to lower the resolution when the triphenylsulfonium salt derivative is used as the photo-acid generator [refer to, for example, Takuya Naito, 8 th Optical Reaction and Electronic Material Research Course, Lecture Brief, p.16 to 18 (1999)].
Accordingly, one of the technical problems currently researched in the development of the resist material suitable for exposure to a light having a wavelength of 130 to 220 nm representatively used in the ArF excimer laser is the development of the photo-acid generator having a higher photoreaction efficiency (photo-acid generation efficiency) and a higher transparency to an ultraviolet ray of a wavelength of 220 nm or less.
SUMMARY OF THE INVENTION
In view of the foregoing, an object of the present invention is to provide a novel photo-acid generator or a novel sulfonium salt compound utilized in a chemically amplified resist material suitable for a light having a wavelength of 130 to 220 nm representatively used in the ArF excimer laser, and more in detail, to the novel photo-acid generator having a higher transparency to an ultraviolet ray of a wavelength of 220 nm or less and a higher photoreaction efficiency (photo-acid generation efficiency).
Another object of the present invention is to provide a chemically amplified resist composition containing the novel photo-acid generator.
A further object of the present invention is to provide a method for patterning by using the photoresist composition.
The present invention provides, in a first aspect thereof, a sulfonium salt compound designated by a general formula (I),
wherein R
1
and R
2
are independently selected from the group consisting of a linear alkyl group, a branched alkyl group, a monocyclic alkyl group and a cross-linked cyclic alkyl group, or R
1
and R
2
having the saturated alkyl group are linked to each other forming a ring or R
1
and R
2
are linked to each other forming a ring having a substituted oxo group, R
3
, R
4
, R
5
and R
6
are independently selected from the group consisting of a hydrogen atom, a halogen atom, an alkyl group and an alkoxy group having 1 to 4 carbon atoms, X is selected from the group consisting of —CH
2
—, —C
2
H
4
— and —OCH
2
— (wherein an oxy group is bonded to a benzene ring), and Y
−
is a counter ion.
The present invention provides, in a second aspect thereof, a method including the steps of: forming a photoresist layer by application of the sulfonium salt compound of the present invention as described above as a positive photoresist material or a negative photoresist material on an underlying layer to be patterned; transferring a desired pattern to the photoresist film on a photoresist composition by exposing the photoresist layer to light having a wavelength between 130 and 220 nm; baking the photoresist layer: and developing the photoresist layer to form a photoresist pattern.
In accordance with the first and the second aspects of the present invention, the sulfonium salt compound having 1-oxoindan-2-yl group or a similar group can be used as a photo-acid generator which is excellent in transparency in a range from a far ultraviolet ray to a vacuum ultraviolet ray
Hasegawa Etsuo
Iwasa Shigeyuki
Maeda Katsumi
Nakano Kaichiro
Baxter Janet
NEC Corporation
Walke Amanda C.
Young & Thompson
LandOfFree
Sulfonium salt compound, photoresist composition and method... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Sulfonium salt compound, photoresist composition and method..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Sulfonium salt compound, photoresist composition and method... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3003757