Fluid sprinkling – spraying – and diffusing – Terminal member adjustably or shiftably connected to flow...
Reexamination Certificate
1999-09-23
2002-07-16
Evans, Robin O. (Department: 3752)
Fluid sprinkling, spraying, and diffusing
Terminal member adjustably or shiftably connected to flow...
C239S273000, C239S280000, C239S280500, C239S281000, C239S587200, C239S589000
Reexamination Certificate
active
06419170
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to semiconductor fabrication and, more particularly, to an adjustable nozzle assembly, a spin, rinse, and dry station for spin rinsing a bottom side of a semiconductor wafer including the adjustable nozzle assembly, and a method for spin rinsing a bottom side of a semiconductor wafer.
In the fabrication of semiconductor devices, a variety of wafer preparation operations are performed. In one such preparation operation, deionized (DI) water is sprayed onto the wafer in, e.g., a spin, rinse, and dry (SRD) station, to rinse off the residual chemical solution and to remove particulate contamination. Until recently, efforts to rinse effectively and to control wafer contamination have primarily focused on the top side of wafers. As the semiconductor industry moves to larger, e.g., 300 mm, wafers and to smaller, e.g., 0.18 &mgr;m and smaller, feature sizes; however, it is becoming increasingly more important to rinse effectively and to control wafer contamination on the bottom side, i.e., the backside, of wafers.
FIG. 1A
is a simplified schematic crosssection illustrating one conventional technique used to spray DI water onto the bottom side of a wafer in an SRD station. As shown therein, wafer
10
is supported by rollers
14
, which contact the edge of wafer
10
to avoid introducing particulate contaminants to either top side
10
a
or bottom side
10
b
of the wafer. A nozzle
16
, which is coupled to a source
18
of DI water via liquid supply tube
20
, is positioned at the bottom of bowl
12
. As wafer
10
is spun, nozzle
16
sprays DI water toward the bottom side
10
b
of the wafer.
To thoroughly clean the bottom side of a wafer, it is imperative that the spray of DI water contacts the center of the wafer. If the spray contacts only a peripheral portion of the wafer, then the centrifugal force generated by the rotation of the wafer prevents the DI water from reaching the center of the wafer. As a result, residual chemical solution and contaminants, e.g., particles, may not be removed from the central portion of the bottom side of the wafer. If the amount of particulate contamination on the bottom side of the wafer exceeds acceptable levels, then the yield rate may be decreased significantly.
FIG. 1B
is an enlarged view of nozzle
16
shown in FIG.
1
A. As shown in
FIG. 1B
, nozzle
16
includes a base portion
16
a
from which a pair of generally elbow-shaped outlets
16
b
extend. The upright sections of outlets
16
b
are angled slightly inwardly, i.e., slightly toward base portion
16
a
. Below base portion
16
a
, threaded portion
16
c
and connector portion
16
d
are provided. Threaded portion
16
c
is screwed into a fixture disposed below the bottom of bowl
12
(see
FIG. 1A
) to hold nozzle
16
in place. One end of liquid supply tube
20
(see
FIG. 1A
) is coupled to connector portion
16
d.
As shown in
FIG. 1A
, nozzle
16
is positioned a distance from the center of the bottom of the bowl because a rotatable shaft, which rotates the spindle arm and spindle fingers to which rollers
12
are attached, is positioned at the center of the bottom of the bowl. As a result of this off-center positioning, the DI water sprayed from outlets
16
b
of nozzle
16
is directed toward the peripheral portion of the bottom side
10
b
of wafer
10
. The elbow-shaped outlets
16
b
are formed of rigid plastic and therefore the position of such outlets can be adjusted only to a minimal extent, if at all. Furthermore, once nozzle
16
is fully screwed into the fixture, the height of nozzle
16
is fixed and cannot be raised.
In light of the limited adjustability of the nozzle in a conventional SRD station such as shown in
FIG. 1A
, problems have been experienced in configuring the system so that DI water sprayed from the nozzle contacts the center of the bottom of the wafer. To further complicate the situation, once the wafer is disposed in the bowl, an operator cannot tell where DI water contacts the bottom side of the wafer because the opaque wafer blocks the operator's line of sight. Thus, even if limited adjustments are made, the operator has no reliable way of determining whether the spray of DI water is properly contacting the center of the bottom side of the wafer.
In view of the foregoing, there is a need for a method and device for spin rinsing a bottom side of a wafer that ensures that the spray of DI water contacts the center of the wafer.
SUMMARY OF THE INVENTION
Broadly speaking, the present invention fills this need by providing a nozzle assembly including an adjustable nozzle. By adjusting the position of the adjustable nozzle, the nozzle may be oriented so that liquid sprayed therefrom is directed toward the center of the bottom side of a semiconductor wafer. The present invention also provides a spin, rinse, and dry station including the adjustable nozzle assembly and a method for spin rinsing a bottom side of a semiconductor wafer.
In accordance with one aspect of the present invention, a nozzle assembly is provided. The nozzle assembly includes a connector tube having a first end and a second end. An outer surface of the connector tube is threaded. A first cap having an opening therethrough is threaded onto the first end of the connector tube. A second cap having an opening therethrough is threaded onto the second end of the connector tube. Each of the first and second caps has a top surface and a threaded inner surface. The nozzle assembly further includes a nozzle having a tubular portion defining a channel. The tubular portion is disposed in the opening of the first connector cap so that a position of the nozzle can be axially and rotationally adjusted.
In one embodiment, the nozzle assembly further includes first and second nuts disposed on the connector tube. If desired, one of the first and second nuts may be integral with the connector tube. The threaded inner surfaces of the first and second connector caps preferably have a first diameter and the openings in the top surfaces of the first and second connector caps preferably have a second diameter, with the second diameter being smaller than the first diameter. In this embodiment, tapered surfaces extend between the threaded inner surfaces of the first and second connector caps and the openings in the top surfaces of the first and second connector caps.
In one embodiment, the nozzle further includes a head portion having a channel defined therein. In this embodiment, the channel defined in the head portion of the nozzle is preferably at an angle of about 35 degrees to about 75 degrees relative to a plane perpendicular to the channel defined in the tubular portion of the nozzle.
In one embodiment, first sealing members are provided proximate to the top surfaces of the first and second connector caps, and second sealing members are provided proximate to the first and second ends of the connector tube. In this embodiment, the first sealing members are preferably split ring seals and the second sealing members are preferably bulkhead fitting seals.
In accordance with another aspect of the present invention, a spin, rinse, and dry (SRD) station for spin rinsing a semiconductor wafer is provided. The SRD station includes a bowl having a bottom wall and a sidewall. A rotational member is disposed in the bowl, with the rotational member being attached to a rotatable shaft. A plurality of support members are attached to the rotational member, with the support members being configured to support a semiconductor wafer above the rotational member. The SRD station also includes a motor for rotating the rotatable shaft and an adjustable nozzle assembly mounted in the bowl. The adjustable nozzle assembly is positioned so as to direct a spray of liquid toward a center of a bottom side of a semiconductor wafer supported in the bowl.
The adjustable nozzle assembly preferably further includes a liquid supply tube disposed in the opening of the second connector cap. The liquid supply tube is preferably coupled to a source of deionized water.
Evans Robin O.
Lam Research Corporation
Martine & Penilla LLP
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