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
2000-09-21
2002-05-28
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
C430S326000, C430S914000, C430S919000
Reexamination Certificate
active
06395451
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a photoresist composition containing a photo base generator (abbreviated as “PBG”). In particular, the invention relates to a photoresist composition comprising (a) a photoresist resin, (b) a photo acid generator, (c) an organic solvent and (d) a photo base generator. The photo base generator reduces or prevents sloping pattern and I/D Bias due to a higher concentration of acid in the upper portion of the photoresist relative to the concentration of acid in the lower portion of the photoresist.
2. Description of the Background Art
Use of chemical amplification-type photoresists (i.e., photoresist compositions) is currently being investigated in photolithography processes using light source such as KrF, ArF, VUV and EUV to achieve a high sensitivity in a minute image-formation on semiconductor devices. Such photoresist compositions are generally prepared by blending a photoacid generator with a matrix resin polymer (i.e., photoresist polymer or photoresist resin) having an acid labile group.
In a photolithography process, the resolution of an image depends on the wavelength of the light used. Thus, the shorter the wavelength, the higher the resolution, i.e., shorter wavelengths allow smaller pattern formation.
In order to be useful in a photolithography process, a photoresist composition must have an excellent etching resistance, heat resistance, and adhesiveness. Moreover, to reduce the cost of manufacturing semiconductor devices, a photoresist composition should be capable of being developed by a common developing solution, such as 2.38 wt % aqueous tetramethylammonium hydroxide (TMAH) solution. These qualities are particularly important in photolithography processes utilizing a deep ultraviolet light source (i.e., short wavelength light source), including KrF (248 nm), ArF (193 nm), VUV (157 nm) and EUV (13 nm).
However, it is very difficult to synthesize a photoresist composition that satisfies all of these requirements. For example, a photoresist polymer having a polyacrylate backbone is readily available, but it has poor etching resistance and is difficult to develop.
Etching resistance may be improved by adding alicyclic unit to the photoresist polymer; however, the presence of alicyclic unit in the photoresist polymer creates problems during the process for manufacturing semiconductor elements. For example, sloping pattern is formed when photoresist resin comprising the alicyclic units is used. Without being bound by any theory, it is believed that the sloping pattern formation is a result of having more light exposure on the upper portions of the PR composition relative to the lower portion of the PR composition (see FIG.
1
). It is believed that the higher light exposure on the upper portions is due to an aerial image of the PR composition (or absorption of light by the resin). Other problems include a severe CD difference between isolated lines and dense lines (i.e., I/D bias) (see FIGS.
2
and
3
).
The present inventors have found that when a PR composition is exposed to the same amount of light energy, there was more energy around the isolated lines of
FIG. 2
than the dense lines of FIG.
3
. Moreover, it was found that the acid concentration around the isolated lines was generally significantly higher than areas near the dense lines. This acid concentration gradient causes the acid to diffuse relatively easily resulting in narrower isolated lines relative to the dense lines when the PR composition is exposed to the same amount of light energy.
Therefore, there is a need for a photoresist composition which overcomes the above-mentioned disadvantages.
SUMMARY OF THE INVENTION
An object of the present invention is to provide photoresist compositions which significantly reduce or prevent the formation a sloping pattern (and hence a severe I/D bias occurrence) due to a higher concentration of generated acid in the upper portions of the photoresist composition relative to the lower portions of the photoresist composition.
Another object of the present invention is to provide a semiconductor element produced by using the Photoresist composition.
REFERENCES:
patent: 5650261 (1997-07-01), Winkle
patent: 5707776 (1998-01-01), Kawabe et al.
patent: 5928818 (1999-07-01), Mertesdorf et al.
patent: 5942367 (1999-08-01), Watanabe et al.
patent: 0 425 142 (1991-05-01), None
patent: 0 952 489 (1999-10-01), None
patent: 2-269350 (1990-11-01), None
patent: 2-296250 (1990-12-01), None
patent: 4-362642 (1992-12-01), None
patent: 10-77257 (1998-03-01), None
patent: 10-83079 (1998-03-01), None
patent: 11-295895 (1999-10-01), None
patent: 2000-10270 (2000-01-01), None
Translation of JP 2-296250, Dec. 1990.*
Japan Abstract Publication No. 02118650, dated May 1990 (in English).
WPI Abstract No. JP 110295895A.
WPI Abstract No.JP 100077257 A.
WPI Abstract No. JP 100083079 A.
Masamitsu Shirai et al., “Photoacid and Photobase Generators: Chemistry and Applications to Polymeric Materials,”Prog. Polym. Sci, vol. 21, 1996, pp. 1-45.
Baik Ki Ho
Jung Jae Chang
Kim Jin Soo
Kong Keun Kyu
Ashton Rosemary
Hyundai Electronics Industries Co,. Ltd.
Townsend and Townsend / and Crew LLP
LandOfFree
Photoresist composition containing photo base generator with... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Photoresist composition containing photo base generator with..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Photoresist composition containing photo base generator with... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2875160