Coating processes – Direct application of electrical – magnetic – wave – or... – Pretreatment of substrate or post-treatment of coated substrate
Reexamination Certificate
2000-05-25
2002-12-17
Padgett, Marianne (Department: 1762)
Coating processes
Direct application of electrical, magnetic, wave, or...
Pretreatment of substrate or post-treatment of coated substrate
C427S547000, C427S458000, C427S444000, C134S001000, C134S002000, C134S028000, C015S001510
Reexamination Certificate
active
06495215
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field of the Invention
The present invention relates to substrate processing method and apparatus for cleaning substrates to be processed, for example, semiconductor wafers, LCD glass substrates, etc. by immersing the substrates in cleaning liquids, e.g. chemicals, rinsing liquids, etc. and subsequently drying the cleaned substrates.
2. Description of the Related Art
Generally, in the manufacturing process of semiconductor devices, there is a widely-adopted cleaning method by which the substrates to be processed, for example, the semiconductor wafers, the LCD glass substrates, etc. (called “wafers etc.” hereinafter) are successively immersed in a cleaning bath filled up with a processing liquid, for example, the chemical, the rinsing liquid, or the like.
Further, such a cleaning apparatus is equipped with a drying unit which exposes the surfaces of the cleaned wafers etc. to dry gas of volatile organic solvent, such as IPA (isopropyl alcohol). In this unit, the vapor of dry gas is condensed or absorbed on the waters' surfaces so that the moisture can be removed from the wafers etc.
As the conventional cleaning and drying apparatus of this kind, there is a known cleaning/drying apparatus which includes a cleaning bath (cleaning chamber), a drying section and moving means, for example, a wafer boat. In this apparatus, the cleaning bath stores and accommodates the rinsing liquid (cleaning liquid), for example, the chemical of hydrofluoric acid, pure water, etc. in order to immerse the substrates, such as semiconductor wafers W, in the stored liquid. The drying section is positioned above the cleaning bath. The wafer boat carries the plural number (e.g. 50 pcs.) of wafers W to bring them to the interior of the cleaning bath and the drying section.
While, as the conventional drying method, there are known techniques disclosed in Japanese Unexamined Patent Publication (kokai) No. 2-291128 and Japanese Examined Patent Publication (kokoku) No. 6-103686.
In the publications, the drying technique disclosed in Japanese Unexamined Patent Publication (kokai) No. 2-291128 is embodied in a process flow shown in
FIGS. 10A-10E
. That is, wafers W are firstly dipped in a treatment bath
2
overflowing with cleaning liquid, for example, pure water. During the immersion, inert gas, such as N
2
gas, is charged into a processing chamber
3
for atmospheric interchange (FIG.
10
A).
Next, dry gas
4
of volatile solvent vapor, such as IPA (isopropyl alcohol), is charged into the processing chamber
3
to form an IPA membrane on the surface of pure water (FIG.
10
B). Then, the wafers W are pulled up from the treatment bath
2
into the processing chamber
3
by wafer carrying means, for example, a wafer boat
5
.
Consequently, the withdrawn wafers W are brought into contact with the IPA gas and therefore, owing to the Marangoni's effect (difference in surface tension), the vapor of dry gas
4
is condensed or absorbed on the waters' surfaces to remove moisture from the wafers W for dry (FIG.
10
C). Thereafter, N
2
gas is supplied into the processing chamber
3
for removal of IPA gas in the chamber
3
(
FIG. 10D
) and furthermore, the interior of the processing chamber
3
is depressurized to progress the evaporation of residual moisture and IPA adhering to respective grooves of the wafer boat
5
, completing the drying process (FIG.
10
E).
As mentioned above, according to the conventional drying method of this kind, the removal of moisture on wafers and sequential drying are completed by the following steps of: dipping the wafers in the pure water for cleaning; moving the wafers and the pure water relatively thereby to allow the IPA membrane on the pure water surface and dry gas (IPA gas) to contact with the wafers' surfaces; and condensing or absorbing the vapor of dry gas.
In the above drying method using the vapor of volatile organic solvent, such as IPA (isopropyl alcohol), it is preferable in aspect of drying effectiveness. However, it is troublesome to discharge or drain the organic solvent while causing the undesirable situation against the environment. Additionally, in order to ensure the safety, it is necessary that the processing apparatus is equipped with a CO
2
extinguisher or the like.
Further, in the moisture removing method utilizing the Marangoni's effect (difference in surface tension), the drying efficiency is not satisfactory so much.
SUMMARY OF THE INVENTION
Accordingly, it is therefore an object of the present invention to provide a substrate processing method and a substrate processing apparatus, by which it is possible to remove the processing liquid from the substrate without using such an organic solvent, appropriately.
The first feature of the invention resides in a substrate processing method for processing a substrate, comprising the steps of: immersing the substrate in processing liquid; and exposing the substrate out of the processing liquid, while the processing liquid is subjected to both electric field and magnetic field in order to apply an electromagnetic force to the processing liquid; whereby the processing liquid is removed from the surface of the substrate.
That is, the present invention provides the substrate processing method utilizing the electromagnetic force (Lorentz's force) brought by the formation of both magnetic field and flow of electric current in the vicinity of the water surface, the method being different from the conventional substrate processing method, for example, the conventional cleaning/drying method. With the adoption of the “surface-dry” system without using any organic solvent, the present invention has merits to facilitate the handling of the substrate processing apparatus employing the above system and reduce the number of particles sticking to the substrate.
The second feature of the invention resides in that the processing liquid is subjected to the electric field and the magnetic field so that the resultant electromagnetic force has a downward component.
It is supposed that, for example, if drawing up the semiconductor wafer W (as the substrate) from the cleaning chamber (as the processing chamber) to the drying chamber, then the cleaning liquid (as the processing liquid) adheres to the substrate's (wafer W) surface up to its portion somewhat higher than the level of the cleaning liquid due to the inherent surface tension, as shown in FIG.
3
. Therefore, when the downward electromagnetic force F is applied perpendicularly or obliquely to the surface of the cleaning liquid by the adoption of magnetic field B and current I of
FIG. 3
, it is possible to eliminate the cleaning liquid adhering to the surfaces of the substrate effectively.
The third feature of the invention resides in that the processing liquid is subjected to the electric field and the magnetic field so that the resultant electromagnetic force has a downward component and horizontal component which directs from a reverse face to a pattern face of the substrate.
Thus, it is possible to give the processing liquid adhering to the substrate's pattern face a force in a direction to separate the liquid from the face thereby to perform the removal of the processing liquid effectively.
The fourth feature of the invention resides in that the processing liquid is subjected to the electric field and the magnetic field so that the direction of the resultant electromagnetic force is changed as the substrate moves in relative to the surface of the processing liquid.
Therefore, in spite of irregularities on the substrate's surface, it is possible to vary an operative direction of the electromagnetic force in accordance with the profile of the substrate's surface, accomplishing the removal of the processing liquid sufficiently.
The fifth feature of the invention is bringing gas which ionizes the processing liquid to facilitate the flowing of an electric current therein into contact with the processing liquid.
Thus, in spite of pure water as the processing liquid, it is possible to prov
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