Photography – Fluid-treating apparatus – Fluid application to one side only of photographic medium
Reexamination Certificate
2002-08-09
2004-06-22
Rutledge, D. (Department: 2851)
Photography
Fluid-treating apparatus
Fluid application to one side only of photographic medium
C396S627000, C118S052000, C427S420000
Reexamination Certificate
active
06752545
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an alkali-based treating liquid, a method and an equipment for adjusting the same, and a method and an equipment for supplying an alkali-based treating liquid. More specifically, the present invention relates to an alkali-based treating liquid for use in the development or formation with treatment of an organic film, such as a photoresist or a functional film, applied onto a substrate, a method and an equipment for adjusting this alkali-based treating liquid, and a method and an equipment for supplying the alkali-based treating liquid for the development of the photoresist, the treatment of the functional film or the like.
2. Description of the Related Art
In fields such as manufacturing of micro-devices and microfabrication (micromachining), various kinds of organic films are recently employed for different purposes. Typical examples of such organic films include thin films of organic photosensitive resin compositions called photoresists, which are essential to photolithography, and so-called functional organic films.
Photolithographic techniques are widely used for transferring micropatterns to wafers and other substrates in the manufacturing of semiconductor devices, such as memories and logical circuits, and liquid crystal devices. The photolithographic process is an essential part of the manufacturing processes of the above-described devices, and generally involves applying a thin film of photoresist onto a wafer, for example, by spin coating, and exposing the film through a mask with light, followed by development, thereby transferring the mask pattern to the wafer.
There are many different types of photoresists employed in such photolithographic processes, depending on the applications or requirements. Examples include positive and negative resists, i-line resists, and resists for KrF and ArF eximer lasers. These photoresists can also be classified, in terms of the materials used, into various types, including DQN resists containing the matrix material novolac (N; Novolac) resin and a diazoquinone (DQ)—based photosensitizer added thereto, resists containing a photo acid generator and chemically amplified resists. In the development of these photoresists (especially, the positive resists), alkali-based developing liquids, such as tetramethyl ammonium hydroxide (TMAH) aqueous solution and potassium hydroxide (KOH) aqueous solution, are widely employed.
Generally, in the lithographic process for the manufacturing of semiconductor devices and liquid crystal devices, the development is performed by applying an alkali-based developing liquid to an exposed photoresist by the spray method, paddle method, or dip method. In many cases, the developing liquid used in this process is not reused, that is, a fresh developing liquid is disposed of after one use. This tendency is particularly strong in the manufacturing of semiconductor devices.
Some of the possible reasons are as follows: (1) The amount used of the developing liquid per wafer is small, since the standard size for wafers currently used in the manufacturing of semiconductor devices is 8 inches (200 mm &phgr;); (2) The developing liquid is diluted with rinse water, so that the alkali concentration of the solution is decreased; (3) If the developing liquid is reused, the increase and accumulation of particles, metal ions and the like contained in the solution may have an undesirable effect during the following processes; and (4) The developing liquid is not necessarily controlled sufficiently in a manner suitable for each of the different applications and materials of photoresists and developing liquids described above.
Meanwhile, examples of the functional film include protective films for preventing the degradation and damage of liquid crystal display devices, semiconductor circuit devices and the like; smoothing films for smoothing surfaces of the devices; interlayer insulating films for insulating interconnects disposed in the form of layers; spacers for maintaining a constant interval between two substrates that seal the liquid crystal of a liquid crystal panel; liquid crystal alignment films capable of aligning liquid crystals; light scattering films for achieving a high front brightness for semi-transparent and reflective liquid crystal displays; and low dielectric constant films having low dielectric constants. Examples of the functional organic film include microlenses serving as optical devices. These functional films have superior properties according to their applications, such as electrical insulation, flatness, heat resistance, transparency, chemical resistance and mechanical strength.
In general, these functional films are each composed mainly of an alkali-soluble organic resin. Like photoresists, functional films can be classified roughly into positive and negative types, and the lithographic process is frequently used for the formation treatment of the films. The lithographic process used in the manufacturing of the functional films also involves applying an alkali-based treating liquid onto an exposed functional film by the spray method, paddle method, or dip method. Usually, the treating liquid used in this process is not reused, and, in many cases, a fresh treating liquid is disposed of after one use.
SUMMARY OF THE INVENTION
In recent years, further miniaturization has been accelerating for semiconductor devices, liquid crystal devices, micro-components such as micromachines and the like. In particular, the miniaturization of semiconductor devices, along with the reduction in layer thickness thereof, has been proceeding at a rapid pace that is unexpected from conventional design rules. For instance, the manufacturing of semiconductor memory products by a 0.13 &mgr;m process is already underway, and the photolithography thus plays an increasingly important role in the manufacturing process. Accordingly, it is required to reliably achieve finer line widths than ever in the patterning of photoresists. Under such circumstances, in order to prevent yield loss, it is necessary to further reduce particles and the like entering the developing liquid. For this reason, the developing liquid may continue to be disposed of after one use.
At the same time, an increase in wafer size has also been promoted for increased productivity, along with the miniaturization and the reduction in layer thickness. Accordingly, 300 mm&phgr; wafers produced by single wafer processing are expected to soon become the standard. This will increase the amounts of developing liquid and rinse water to be used, leading to an increase in material cost and in the amounts of liquid wastes of the developing liquid and rinse water to be generated and treated. In addition to the foregoing, the inventors of the present invention acquired the following findings as a result of in-depth research on the conventional photoresist (positive resist) development process employing a fresh developing liquid.
In general, a photoresist applied onto a wafer is pre-baked to be fixed, and is then exposed and developed. In the case of the positive resist, the functional group in the exposed portion is converted to carboxylic acid or other chemical form that reacts readily with alkali, so that the dissolution rate of the exposed portion of the resist in an alkali-based developing liquid becomes significantly higher than that of the unexposed portion. Here, a positive resist is applied onto a metal thin film formed on a wafer, and then, after the photoresist is exposed and developed to perform patterning, the metal thin film is etched. In this case, the metal thin film is etched in the portion exposed under the exposed portion of the photoresist that has been dissolved in the development process.
However, it was found that, under certain conditions, poor etching could occur in the above-described portion of the metal thin film. Such poor etching either reduces the conductivity and results in lower product reliability, or causes conduction failure leading to defective products, t
Hozan Takahiro
Katagiri Yuko
Kikukawa Makoto
Morita Satoru
Nakagawa Toshimoto
Nagase & Co. Ltd.
Osha & May L.L.P.
Rutledge D.
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