Wafer spin drying apparatus with a plurality of supply...

Details Wafer spin drying apparatus with a plurality of supply... Wafer spin drying apparatus with a plurality of supply...

2003-05-13

2004-12-28

Rinehart, Kenneth (Department: 3749)

Drying and gas or vapor contact with solids

Apparatus

With apparatus using centrifugal force

C034S059000, C034S187000, C034S241000, C034S582000, C034S523000, C034S222000

Reexamination Certificate

active

06834440

ABSTRACT:

RELATED APPLICATION
This application claims priority to Korean Patent Application 2002-0059555, filed on Sep. 30, 2002, the contents of which are herein incorporated by reference in their entirety.
BACKGROUND OF THE INVENTION
The present invention relates to apparatus for drying wafers, and more particularly, to spin type drying apparatus and methods for using the same.
The integration density, speed and reliability for integrated circuit (semiconductor) devices continues to increase to meet the demands for higher performance products incorporating such integrated circuit devices. As the performance requirements of the integrated circuit devices increase, the demands on manufacturing processes to provide a desirable yield when fabricating such devices may also increase.
The manufacture of semiconductor devices generally includes repeated execution of various individual processing steps, such as a deposition process, a photolithography process, an etching process, a polishing process, a cleaning process, a drying process and so on. The various processes may be repeated in a desired sequence with specified materials to provide a layered structure with the desired characteristics as will be understood by those of skill in the art. In particular, the cleaning process is typically used to remove impurities attached to the surface of a wafer or undesired films formed on the wafer during the other processing operations. The importance of the cleaning process generally increases with higher density and more complicated fabrication patterns for the integrated circuit devices and as the aspect ratios of the patterns increase. The drying process is intended to remove moisture remaining on the wafer from the surface of the wafer after cleaning. However, watermarks may be left on the surface of the wafer after the cleaning and drying process. Such watermarks may cause processing failures during subsequent manufacturing process steps.
Wafer drying apparatus may be divided into batch type wafer drying apparatus and a single type rapid wafer drying apparatus, such as spin type drying apparatus. The batch type wafer drying apparatus can be further divided into a single container type apparatus and a dual container type apparatus. The single container type apparatus generally includes one container in which a wafer is rinsed and dried. Various single container type apparatus dry the wafer by employing, for example, the Marangoni effect or a spray of isopropyl alcohol. In contrast, a dual container type wafer drying apparatus generally has two containers, one for rinsing the wafer and the other for drying the wafer. Typically, for the dual container type wafer drying apparatus, the final rinsing process for the wafer is executed in a lower container and the drying process is performed in an upper container after the wafer is lifted into the upper container from the lower container. The dual container type wafer drying apparatus can dry the wafer using, for example, the Marangoni effect, spray of a liquid isopropyl alcohol, or using vapor of an isopropyl alcohol.
Examples of a batch type wafer drying apparatus are described in U.S. Pat. No. 6,027,574 to Fishkin et al. and U.S. Pat. No. 6,029,371 to Kamikawa et al. Fishkin et al. describes a batch type wafer drying apparatus of the single container type that employs the Marangoni effect. Kamikawa et al. discloses a batch type wafer drying apparatus that uses an isopropyl alcohol vapor.
A single type rapid wafer drying apparatus can dry a wafer using the centrifugal force produced during rotation of the wafer at a high speed, such as with a spin type drying apparatus. While the wafer is being rotated, an organic solvent, such as isopropyl alcohol, can be delivered onto a surface of the wafer to improve the efficiency of the wafer drying process.
An example of a single type rapid wafer drying apparatus is disclosed in U.S. Pat. No. 5,289,156 to Shibasaki et al. Shibasaki et al. describes a rotary (or spin type) wafer drying apparatus including a holder horizontally gripping a wafer and defining a back space positioned under the rear face of the wafer. A driving part rotates the wafer and a gas supply member provides a clean gas to the back space.
A spin type rapid wafer drying apparatus generally dries the wafer utilizing the centrifugal force generated by the rotation of the wafer. The apparatus may provide isopropyl alcohol to the wafer in order to increase the effectiveness of the removal of moisture from the wafer. The isopropyl alcohol can be delivered to the wafer, for example, in a vapor phase and/or in a mist state with a carrier gas.
FIG. 1
is a cross-sectional view illustrating a conventional single type rapid (spin type) wafer drying apparatus. As shown in
FIG. 1
, a wafer W is horizontally supported on rotating chuck
110
. The wafer is held on the rotating chuck
110
by a vacuum provided through the rotating chuck
110
. A rotary shaft
112
connects a driving part (e.g., motor)
114
to a bottom portion of the rotating chuck
110
to spin the rotating chuck
110
during the cleaning/drying operations. A cover
116
is disposed around the rotating chuck
110
to control the escape of de-ionized water dispersed from the wafer W during the cleaning operation. As shown in
FIG. 1
, the cover
116
has a cup shape with an open upper face and the rotary shaft
112
passes through the bottom portion of the cover
116
. The rotary shaft
112
defines the central axis of rotation of the rotary chuck
110
.
A de-ionized water supply member
120
is also shown in
FIG. 1
disposed over the wafer W. In addition, an isopropyl alcohol supply member
130
is disposed over the wafer W. The de-ionized water supply member
120
moves from the central portion of the wafer W to the edge portion of the wafer W while supplying the de-ionized water onto the wafer W. The isopropyl alcohol supply member
130
, like the de-ionized water supply member, also moves from the central portion to the edge portion of the wafer W during cleaning and supplies an isopropyl alcohol onto the wafer W. The isopropyl alcohol is provided to reduce the surface tension of the de-ionized water on the wafer W so that the wafer W may be more efficiently dried due to the centrifugal force generated by rotation of the wafer W.
Various problems may result when using the above-described apparatus
100
. For example, watermarks may occur at the edge portion of the wafer W as the de-ionized water supply member
120
scanning the surface of the wafer W may not supply sufficient de-ionized water onto the edge portion of the wafer W. When the de-ionized water supply member
120
is positioned over the central portion of the wafer W, the moisture at the edge portion of the wafer W may not be properly removed from the wafer W and may, instead, be naturally dried (as contrasted with removed by centrifugal force) at the edge portion of the wafer W. Watermarks generally result when there is naturally dried moisture at the edge portion of the wafer W.
In addition, the de-ionized water dispersed from the wafer W due to centrifugal force may strike and rebound from the cover
116
. As a result, this de-ionized water may fall back onto an already dried portion of the wafer W, generally the central portion. This re-deposited de-ionized water may also not be properly removed and may form additional watermarks on the wafer W. If the spin speed of the wafer W and the scanning speeds of the de-ionized water and the isopropyl alcohol supply members
120
and
130
are reduced to improve the efficiency of the drying process, the time required to dry the wafer W would be expected to increase.
The problems described above generally increase in seriousness as the size of the wafer W increases. However, as a result of potential benefits of working with larger wafer sizes, various manufacturing processes are tending to use larger wafer sizes, thereby increasing the potential benefits of improved wafer drying.
SUMMARY OF THE INVENTION
In some embodiments of the present invention, an apparatus for drying a waf

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