Patent Application
20080020324
Aspects of the present disclosure are best understood from the following detailed description when read with the accompanying figures. It is noted that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion.
It is understood that the following disclosure provides many different embodiments, or examples, capable of implementing different features of the invention. Specific examples of components and arrangements are described below to simplify and thus clarify the present disclosure. These are, of course, merely examples and are not intended to be limiting. For example, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed interposing the first and second features, such that the first and second features may not be in direct contact. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.
Referring to
Additionally, the substrate 210 may include a bottom anti-reflecting coating (BARC) layer formed on the material layer(s) to be patterned. The BARC layer is designed to have a proper refractive index and/or a thickness to reduce light reflection during a lithography process and enhance lithography patterning performance. The BARC layer may include an organic material, a nitride material, or an oxide material, and may have a thickness ranging between about 100 angstrom and 1000 angstrom.
A resist layer 220 is formed on the substrate 210. For example, the resist layer 220 may be formed on the BARC layer disposed on the substrate 210. The resist layer 220 may have a thickness ranging between about 50 angstroms and 5000 angstroms. In another embodiment, the resist layer 220 may have a thickness ranging between about 500 angstroms and 2000 angstroms. The formation of the resist layer 220 may be implemented by a technique such as spin-on coating. Additionally, a bake process may be applied to the resist layer 220 to reduce solvent in the resist layer, referred to as a soft baking process.
In the present embodiment, the resist layer is a chemical amplifier resist (CAR). The resist layer 220 includes a polymer material that turns soluble to a developer such as a base solution when the polymer is reacted with acid. Alternatively, the resist layer 220 includes a polymer material that turns insoluble to a developer such as a base solution when the polymer is reacted with acid. The resist layer 220 further includes a solvent filling inside the polymer. The solvent may be partially evaporated due to a prior baking process (such as a soft baking process). The resist layer 220 also includes a photoacid generator (PAG). When absorbing photo energy (or radiation energy), the PAG decomposes and forms a small amount of acid.
Referring to
A top anti-reflective coating (TAR) layer may be additionally formed on the resist layer 220 either over the top coater 230 or interposed between the resist layer 220 and the top coater 230. The TAR layer may be formed by a spin-on coating technique. Alternatively, the TAR may be combined with the top coater 230 such that the top coater 230 can also serve for antireflection during a lithography exposing process.
Referring to
The exposing process may be performed utilizing an immersion lithography technique wherein an immersion fluid is disposed between the lens of the lithography tool and the semiconductor device 200 during an exposing process. For example, de-ionized water (DI water or DIW) may be used as an immersion fluid for exposing processes. Since the resist layer 220 is protected and separated by the top coater 230 from the immersion fluid, PAG diffusion issues are substantially eliminated.
The lithography apparatus to implement an immersion exposing process is described below as an example. The lithography apparatus includes a substrate stage designed to secure a substrate to be processed. The substrate stage is operable to move the substrate relative to the apparatus. For example, the substrate stage is capable of translational and/or rotational displacement for substrate alignment, stepping, and scanning. The substrate stage may include various components suitable to perform precise movement. The lithography apparatus includes one or more imaging lens systems (referred to as a “lens system”). A substrate such as the semiconductor device 200 may be positioned on the substrate stage under the lens system. Each lens element thereof may include a transparent substrate and may further include a plurality of coating layers. The transparent substrate may be a conventional objective lens, and may be made of fused silica (SiO2), calcium-fluoride (CaF2), lithium fluoride (LiF), barium fluoride (BaF2), or other suitable material. The materials used for each lens element may be chosen based on the wavelength of light used in the lithography process to minimize absorption and scattering. The apparatus may include an immersion fluid retaining module designed for holding an immersion fluid and/or other proper fluid such as a cleaning fluid. The immersion fluid retaining module may be positioned proximate (such as around) the lens system and designed for other functions, in addition to holding the immersion fluid. The immersion fluid retaining module may include various apertures (or nozzles) for providing an immersion fluid for an exposure process, and/or performing other proper functions. The lithography apparatus may further include a radiation source. The radiation source may be a suitable ultraviolet (UV) or extra UV(EUV) light source. For example, the radiation source may be a mercury lamp having a wavelength of 436 nm (G-line) or 365 nm (I-line); a Krypton Fluoride (KrF) excimer laser with wavelength of 248 nm; an Argon Fluoride (ArF) excimer laser with a wavelength of 193 nm; a Fluoride (F2) excimer laser with a wavelength of 157 nm; or other light sources having a desired wavelength (e.g., below approximately 100 nm). The apparatus may include a chamber to provide a vacuum environment or a low pressure environment with inert gas for protecting various components and a substrate to be processed. An example of an immersion lithography system is provided in U.S. Ser. No. 60/729,565, filed Oct. 24, 2005, which is hereby incorporated by reference.
Referring to
Alternatively, the top coater 230 may be partially removed. In one example, the top coater 230 may be thinned using a technique similar to that used for removal of the top coater with a controlled period of time. Thus the thickness of the top coater is substantially reduced and the top coater associated defects are also substantially reduced or eliminated. In another example, the top coater 230 includes two layers, a first layer (overlying a second layer) is properly removed by a method capable of selectively remove the first layer from the second layer to eliminate the top coater related defects. When the top coater 230 is removed after the exposing process, the top coater related issues such as water penetration and stains can be substantially eliminated or reduced.
Referring to
Referring to
The method 100 may further include other processing steps after the developing of resist layer 220 at step 112, such as baking, etching/implanting, and/or stripping the resist layer. For example, after an etching process applied to an underlying material layer within the openings of the patterned resist layer and a recessing pattern is formed thereby in the substrate, the resist layer may be removed thereafter by a wet stripping, plasma ashing, or a combination thereof. The present disclosure may have various variations. In one example, the disclosed method is not limited to patterning a semiconductor substrate. Other substrate such as a glass substrate for TFT_LCD devices, or a transparent substrate (such as fused quartz) for photomask may be patterned using the disclosed material, method, and apparatus. In another variation, the exposing process at step 106 may be implemented by an immersion lithography process utilizing another immersion fluid than water. For example, a solution with water and proper additives may be used for immersion lithography processing.
Thus, the present disclosure provides a method for photolithography processing. The method includes providing a substrate coated with a photosensitive layer thereon and a top coater overlying the photosensitive layer; exposing the photosensitive layer to a radiation energy; removing the top coater; and baking the photosensitive layer after the removing of the top coater layer.
The disclosed method may further include developing the exposed photosensitive layer after the baking of the photosensitive layer. The removing of the top coater may include utilizing a developing solution to remove the top coater. The removing of the top coater may include utilizing a water-based solvent containing surfactant to remove the top coater. The photosensitive layer may include chemical amplification resist (CAR). The top coater may include an organic material. The top coater may include a hydrophobic material. The top coater may include a hydrophobic material having a contacting angle greater than about 50 degree for water. The top coater may include a fluorine-containing material. The fluorine-containing material may include fluorine content ranging between about 0.5% and about 30% in weight. The top coater may include a thickness ranging between about 50 angstrom and about 10000 angstrom. The method may further include a cleaning process applied to the photosensitive layer after the removing of the top coater. The cleaning process may utilize de-ionized water (DIW). The exposing of the photo sensitive layer may include performing the exposing in an immersion lithography environment. The substrate may be selected from the group consisting of a semiconductor substrate, a photomask substrate, and thin-film-transistor liquid-crystal-display (TFT-LCD) substrate.
The present disclosure also provides another method for photolithography patterning. The method includes forming a photosensitive layer on a substrate; forming a top coater on the photosensitive layer; exposing the photosensitive layer to a radiation energy; at least partially removing the top coater; baking the photosensitive layer after the removing of the top coater layer; and developing the exposed photosensitive layer.
In the disclosed method, the top coater may be removed by utilizing a solution to reduce a thickness of the top coater. The solution may be selected from the group consisting of a developing solution and a water-based solution. The forming of the top coater may include forming a hydrophobic material disposed on the photosensitive layer.
The present disclosure also provides another method for photolithography patterning. The method includes forming a photoresist layer on a semiconductor substrate; forming a hydrophobic top coater on the photosensitive layer; exposing the photosensitive layer to a radiation energy in an immersion lithography mode; removing the top coater; thereafter baking the photosensitive layer; and developing the photosensitive layer.
The foregoing has outlined features of several embodiments so that those skilled in the art may better understand the detailed description that follows. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions and alterations herein without departing from the spirit and scope of the present disclosure.
