Patent Application
20080020293
The objectives and advantages of the present invention will become apparent upon reading the following description and upon reference to the accompanying drawings in which:
In addition, the third phase region 62 forms a point connection with the first phase region 52 and the second phase region 58. The first phase region 52 can be triangular, the second phase region 58 includes a triangular portion 56 and a concave-shaped portion 54, and the first phase region 52 and the triangular portion 56 of the second phase region 58 form a rectangular region 53, which is positioned in a rectangular concave of the concave-shaped portion 54. Similarly, the third phase region 62 can be triangular, the fourth phase region 68 includes a triangular portion 66 and a concave-shaped portion 64, and the third phase region 62 and the triangular portion 66 of the fourth phase region 68 form a rectangular region 63, which is positioned in a rectangular concave of the concave-shaped portion 64. As an exposing light penetrates the first phase region 52, the second phase region 58, the third phase region 62, and the fourth phase region 68, there are 90 degrees of phase difference. Therefore, the first phase region 52 can be considered as a 180° region, the second phase region 58 can be considered as a 270° region, the third phase region 62 can be considered as a 90° region, and the fourth phase region 68 can be considered as a 0° region.
The polymer layer 70 may be made of material including silsesquioxane. For example, the silsesquioxane can be hydrogen silsesquioxane (HSQ), and the developing process may use alkaline solution to remove the polymer layer 70 not irradiated by the electron beam 72, wherein the alkaline solution is selected from the group consisting of sodium hydroxide (NaOH) solution, potassium hydroxide (KOH) solution, and tetramethylamomnium hydroxide (TMAH) solution. In addition, the silsesquioxane can be methylsilsesquioxane (MSQ), and the developing process may use an alcohol solution such as an ethanol solution to remove the polymer layer 70 not irradiated by the electron beam 72. Further, the polymer layer 70 can be made of material including hybrid organic siloxane polymer (HOSP), and the developing process may use a propyl acetate solution to remove the polymer layer 70 not irradiated by the electron beam 72.
The irradiation of the electron beam 72 will change the molecular structure of the polymer layer 70, for example, the molecular structure of hydrogen silsesquioxane will transform into a network structure from a cage-like structure and chemical bonds will be formed between the polymer layer 70 and the quartz substrate 52. As a result, it is possible to selectively remove the polymer layer 70 outside the predetermined region 74 by the developing process using alkaline solution.
According to the known phase shifting formula: P=2π(n−1)d/mλ, where, P represents phase shifting angle, n represents the reflection index, d represents the thickness of the phase shifting pattern, m represents an odd number, and λ represents the wavelength of the exposure beam. When the wavelength of the exposure light is set to be 193 nanometer, the corresponding reflection index of the polymer layer 70 is about 1.52, and the thickness of the first phase region 52 calculated according to the phase shifting formula should be 1828 Å. If the tolerance of the phase shifting angle is set to be 177° to 183°, the thickness of the first phase region 52 should be 1797 to 1858 Å.
Referring to
As the exposing light 34 penetrate any two adjacent phase regions of the vortex mask 40, the phase difference is not 1800, i.e., the destructive interference does not occur, and the optical intensity distribution of the vortex mask 40 does not have the L-shaped dark region 24 of the conventional vortex mask 10. In particular, the optical intensity distribution of the vortex mask 40 has only the circular dark region 44 to define the shape of the circular pattern 26, and it is not necessary to perform a second expose process using another mask having an L-shape bright region. In other words, to define the shape of the circular pattern 26, the present invention needs to perform the exposing process only once using the vortex mask 40.
The prior art vortex mask 10 possesses the L-shaped dark region 24 due to destructive interference, which necessitates a second exposing process using another mask having a corresponding L-shaped bright region in addition to the first exposing process using the vortex mask 10. The requirement of performing the exposing process twice raises the alignment issue and reduces the throughput of the lithographic process. In contrast, the optical intensity distribution of the present vortex mask 40 possesses the circular dark region 44 and no L-shaped dark region, and therefore the present invention does not need to perform a corresponding second exposing process. Consequently, the present invention does not have alignment issues and can increase the throughput of the lithographic process.
The above-described embodiments of the present invention are intended to be illustrative only. Numerous alternative embodiments may be devised by those skilled in the art without departing from the scope of the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 095126641 | Jul 2006 | TW | national |
