Apparatus for drying semiconductor wafer using vapor dry method

Details Apparatus for drying semiconductor wafer using vapor dry method Apparatus for drying semiconductor wafer using vapor dry method

2003-03-04

2004-06-01

Bennett, Henry (Department: 3749)

Drying and gas or vapor contact with solids

Process

With fluid current conveying or suspension of treated material

C034S467000, C034S095000, C034S443000, C034S236000

Reexamination Certificate

active

06742281

ABSTRACT:

BACKGROUND OF THE INVENTION
This application claims the priority of Korean Patent Application No. 2002-53925, filed Sep. 6, 2002 in the Korean Intellectual Property Office (KIPO), which is incorporated herein in its entirety by reference.
1. Field of the Invention
The present invention relates to an apparatus for drying a semiconductor wafer, and more particularly, to an apparatus for drying a semiconductor wafer, using a cleansing vapor and deionized water, which is designed to prevent adhesion of adjacent semiconductor wafers to each other.
2. Description of the Related Art
In general, impurities formed on a semiconductor wafer during manufacture of a semiconductor chip are cleaned in a cleaning process. The cleaning process may include (a) treatment of the semiconductor wafer with a chemical solution, (b) rinsing the chemically treated semiconductor wafer with deionized water (hereinafter, ‘DIW’), and (c) drying the rinsed semiconductor wafer. Typically, a spin-drying method was used to dry the rinsed semiconductor wafer. However, the higher the integration of a semiconductor device, the more complicated is the surface structure of a semiconductor wafer. Accordingly, a solvent vapor drying method is employed in which the DIW is replaced by a solvent vapor of an organic material, such as an isopropyl-alcohol vapor (hereinafter, ‘IPA’), in the spin drying method.
FIG. 1
illustrates a method of drying a semiconductor wafer using a conventional semiconductor wafer drying apparatus that utilizes a solvent vapor drying method. Referring to
FIG. 1
, this semiconductor wafer solvent drying apparatus includes a chamber
110
that performs a drying process on a semiconductor wafer
100
. The chamber
110
is connected to a solvent vapor storage container
130
, in which a solvent solution
132
is stored, via supply line
150
. The solvent vapor storage container
130
is also connected to a nitrogen gas supply pipe
134
through which a nitrogen (N
2
) gas is supplied from an outside source (not shown).
A wafer holder
111
, on which the semiconductor
100
is positioned in the chamber
110
. The wafer holder
111
is movable in the vertical direction within the chamber
110
, and in turn, the semiconductor wafer
100
also can be moved in the vertical direction within the chamber
110
. A waste water drain line
113
is placed below the wafer holder
111
to drain waste water remaining after evaporation of the solvent solution
132
. A heater
115
is attached to the bottom of the chamber
110
. The heater
115
generates heat in the chamber
110
so as to evaporate a solvent solution
132
′ supplied in the chamber
110
. Exhaust lines
117
are installed at an intermediate position B and at an upper position C of the chamber
110
, so as to discharge vapor of evaporated solvent solution to the outside of the chamber
110
. In addition, a filter
119
is attached to the top of the chamber
110
to filter air and the like supplied from outside the chamber
110
.
A process of drying a semiconductor wafer using such a semiconductor wafer drying apparatus will now be described with reference to FIG.
1
. First, the semiconductor wafer
100
cleaned with DIW is placed in the chamber
110
and is held in place by the wafer holder
111
. The semiconductor wafer
100
is originally placed at a position A. When the semiconductor wafer
100
is loaded onto the wafer holder
111
in the chamber
110
, the solvent solution
132
in the storage container
130
is supplied to the inside of the chamber
110
via the supply line
150
.
The solvent solution
132
′ supplied in the chamber
110
is boiled using heat generated by the heater
115
. The waste water remaining after the evaporation of the solvent solution
132
′ is discharged via the waste water drain line
113
. Solvent vapor
132
″ takes the place of the DIW associated with the surface of the semiconductor wafer
100
. Next, after a certain amount of time has passed, the wafer holder
111
is moved upwardly so that the semiconductor wafer
100
is positioned at the position B in the chamber
110
. Solvent vapor associated with the semiconductor wafer
100
at the position B is continuously discharged via the exhaust line
117
at the position B. Next, after a predetermined amount of time, the wafer holder
111
is moved to the position C in the chamber
110
and solvent vapor associated with the semiconductor wafer
100
is completely discharged via the exhaust line
117
at the position C. After the removal of the solvent vapor associated with the semiconductor wafer
100
, the semiconductor wafer
100
is removed from the chamber
100
.
The semiconductor wafer drying apparatus of
FIG. 1
has its disadvantages. For example, it is difficult to precisely control the amount of solventsolution to be evaporated. If the solvent solution is evaporated under extreme conditions in the chamber
100
, a great amount of carbon (C) is detected from the dried surface of the semiconductor wafer. To solve this problem, the surface of the semiconductor wafer is dried by flooding the inside of chamber
100
with DIW, and then supplying nitrogen gas and solvent vapor to the chamber in an upwardly direction of the semiconductor wafer, while discharging the DIW downwardly from the semiconductor wafer.
As the size of a semiconductor wafer increases, a drying process is performed on the semiconductor wafers using a half pitching method. The half pitching method comprises stacking the semiconductor wafers for batch processing of more than 50 sheets of semiconductor wafers of diameters of 200 mm or more. In this case, however, a reduction in the distance between semiconductor wafersis inevitable. Thus, an adverse result is produced, namely, adhesion of adjacent semiconductor wafers. The adhesion of adjacent semiconductor wafers prevents complete removal of DIW adhering to surfaces to semiconductor wafers. Water marks on the semiconductor wafers, due to incomplete removal of the DIW, causes malfunction of the semiconductor devices.
SUMMARY OF THE INVENTION
The present invention provides an apparatus and method for semiconductor wafer vapor drying wherein adhesion of adjacent semiconductor wafers is prevented during the wafer drying process.
According to an embodiment of the present invention, there is provided a semiconductor wafer drying apparatus including a bath which can contain much deionized water so that semiconductor wafers soak in the deionized water; a chamber providing a space where vapor flows over the bath; a vapor supply line supplying vapor to the internal space of the chamber; an exhaust line discharging vapor contained in the chamber to the outside of the chamber; a deionized water exhaust line discharging deionized water in the bath to the outside of the bath; a semiconductor wafer holder supporting the semiconductor wafer in the bath; and pitch guides placed at left and right sides of the semiconductor wafer, movable to a first position and a second position in a vertical direction, wherein the pitch guides are separated from the semiconductor wafer at the first position and contact the semiconductor wafer at the second position thus preventing the movement of the semiconductor wafer.
Preferably, the pitch guides can be moved to a third position where the semiconductor wafer is positioned at a distance from the semiconductor wafer holder.
Preferably, the pitch guides are connected to a motor and provided with a driving force for the vertical movement from the motor. Alternatively, the pitch guides may be connected to a piston and provided with a driving force for the vertical movement from the piston. If necessary, the vertical movements of the pitch guides may be carried out by a driving force due to lifting power of the deionized water.
Preferably a nitrogen gas and isopropyl alcohol (IPA) vapor are supplied into the chamber via the vapor supply line.
Preferably, the pitch guides are moved to the second position when an upper portion of the semiconductor wafer is exposed from the surface of the deionized water.
A

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