Coating apparatus – Control means responsive to a randomly occurring sensed... – Responsive to condition of coating material
Reexamination Certificate
1998-10-21
2001-04-17
Edwards, Laura (Department: 1734)
Coating apparatus
Control means responsive to a randomly occurring sensed...
Responsive to condition of coating material
C118S693000, C118S694000, C118S712000, C118S600000, C118S610000, C118S052000, C118S056000, C118S319000, C118S320000
Reexamination Certificate
active
06217657
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a resist processing method for coating a resist on a substrate such as a semiconductor wafer and an LCD substrate, and developing the coated resist, and also relates to a resist processing system.
In the photolithographic process of a semiconductor device and a liquid crystal display device, a desired circuit pattern is formed by coating a resist on a semiconductor wafer and a substrate for a liquid crystal display (LCD), exposing the coated resist to light, and developing the exposed resist with a developing solution. In the developing process, a carrier gas (pressurized N
2
gas) is first introduced into a tank containing the developing solution. The developing solution is sent out from the tank by the gas pressure by way of a supply line to a nozzle. Finally, the developing solution is expelled from the nozzle onto the substrate.
In such a developing process, the developing solution must be uniformly supplied over the entire substrate surface in a short time to prevent non-uniform development. If the developing solution is supplied quickly from the tank to the nozzle by increasing the pressure of the carrier gas, a large quantity of the carrier gas dissolves in the developing solution, or ambient air gets involved into the developing solution which is supplied from the nozzle. As a result, air bubbles are readily formed in the developing solution supplied to the substrate. The air bubbles attach to a substrate surface, preventing the exposure of the coated resist to the developing solution. This is a cause of the defect, “undeveloped portion of a resist”. To avoid this, a deaeration apparatus has been used to separate and remove a gaseous component from the developing solution before the solution is supplied to the substrate.
However, conventional methods for removing the gaseous component from the developing solution have problems. First, a liquid component acting as an active ingredient of the developing solution is removed together with the gaseous component. The amount of this liquid component cannot be negligible. As a result, the concentration of the developing solution changes, varying the quality of the developing process. Second, in the case of the developing-solution deaeration apparatuses conventionally used, when a vacuum evacuation line of the deaeration mechanism is contaminated with the liquid component (an active ingredient in the developing solution), the evacuation capacity of the deaeration mechanism decreases, lowering the evacuation rate. Furthermore, the vacuum evacuation line itself becomes contaminated with the liquid component.
BRIEF SUMMARY OF THE INVENTION
An object of the present invention is to provide a resist processing method capable of sufficiently removing a gaseous component from a processing solution such as a developing solution without changing the concentration of the processing solution. Another object of the present invention is to provide a resist processing system capable of efficiently removing a liquid component introduced into a vacuum evacuation line of a deaeration mechanism.
The resist processing method according to the present invention is a method for introducing a pressurized gas into a vessel storing a processing solution, sending the processing solution from the vessel to a nozzle by way of a supply line by means of the pressurized gas, and supplying the processing solution from the nozzle to a substrate,
the method comprising the steps of:
(a) attaching a deaeration mechanism to the supply line, the deaeration mechanism having a gas-liquid separation membrane and a vacuum evacuation line;
(b) introducing the pressurized gas into the vessel to send out a processing solution from the vessel into one side portion of the gas-liquid separation membrane through the supply line;
(c) evacuating the other side portion of the gas-liquid separation membrane through the vacuum evacuation line to set the pressure of the other side portion of the gas-liquid separation membrane within a saturated vapor pressure of the processing solution, permitting a liquid component dissolved in the processing solution to migrate from the one side portion to the other side portion, thereby removing a gaseous component from the processing solution before the process solution is supplied to a substrate (deaeration step);
(d) discharging the processing solution present in the supply line between the deaeration mechanism and the nozzle, and introducing the processing solution deaerated in the deaeration step (c) into the supply line between the deaeration mechanism and the nozzle (processing solution replacing step);
(e) supplying the deaerated processing solution to the substrate by expelling the deaerated processing solution from the nozzle; and
(f) rotating the nozzle relative to the substrate to form a liquid film of the deaerated processing solution between the nozzle and the substrate.
The resist processing method according to the present invention is a method for introducing a pressurized gas into a vessel storing a processing solution, sending the processing solution from the vessel to a nozzle by way of a supply line by means of the pressurized gas, and supplying the processing solution from the nozzle to a substrate,
the resist processing method comprising the steps of:
(A) attaching a deaeration mechanism to the supply line, the deaeration mechanism having a gas-liquid separation membrane and a vacuum evacuation line;
(B) introducing a pressurized gas into the vessel to send out the processing solution from the vessel into one side portion of the gas-liquid separation membrane through the supply line;
(C) evacuating the other side portion of the gas-liquid separation membrane through the vacuum evacuation line to set the pressure of the other side portion of the gas-liquid separation membrane within a saturated vapor pressure of the processing solution, permitting a liquid component dissolved in the processing solution to migrate from the one side portion to the other side portion, thereby removing a gaseous component from the processing solution before the process solution is supplied to a substrate (deaeration step);
(D) discharging the processing solution present in the supply line between the deaeration mechanism and the nozzle, and introducing the processing solution deaerated by the deaeration step (C) into the supply line between the deaeration mechanism and the nozzle (processing solution replacing step);
(E) spinning the substrate; and
(F) expelling the deaerated processing solution from the nozzle to the substrate to form a liquid film of the deaerated processing solution between the nozzle and the substrate.
The present inventors have studied causes of defects produced in developing a resist. As a result, they found that the degree of vacuum of the deaerated process atmosphere is related to the number of defects. They further found the deaeration conditions successfully reducing the number of defects.
In the method of the present invention, a gaseous component can be removed from the developing solution by sending the developing solution without being left in the deaeration mechanism. On the other hand, if the deaeration process time is rather long, not only the gaseous component but also an active ingredient contained in the liquid are removed. As a result, the concentration of the developing solution changes as shown in
FIG. 10
(exhibiting the relationship between the deaeration process time and the number of development defects). For example, when the concentration of the developing solution increases as a result of vaporization of moisture components, the resultant wiring is obtained with an excessively narrow width. This is a kind of defects. Therefore, it is desirable that the deaeration process time be shorter than 24 hours. However, the deaeration time of the developing solution needs to be longer than 10 minutes because if the deaeration time is shorter than 10 minutes, the deaeration will not be sufficiently performed.
For example, when a generally-used devel
Hasebe Keizo
Kiba Yukio
Semba Norio
Edwards Laura
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Tokyo Electron Limited
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