Photocopying – Projection printing and copying cameras – With temperature or foreign particle control
Reexamination Certificate
2001-05-04
2003-02-18
Adams, Russell (Department: 2851)
Photocopying
Projection printing and copying cameras
With temperature or foreign particle control
C355S053000, C355S072000, C356S340000, C356S365000, C250S492200, C250S548000
Reexamination Certificate
active
06522385
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an exposure device used in the manufacturing of semiconductor devices. More particularly, the present invention relates to an air shower head for producing a shower of air that envelops a wafer during a semiconductor device manufacturing process of exposing photosensitive material on the wafer.
2. Description of the Related Art
Impurities are precisely regulated and are injected into small regions of a silicon substrate to manufacture a fine circuit. Such regions are mutually connected to form a device and a VLSI circuit. A pattern formed by photolithography is used to define the regions. That is, a wafer is coated with a photosensitive resist (photoresist layer), the photoresist layer is irradiated with light (ultraviolet light) projected through a photomask bearing a pattern to thereby expose selected portions of the photoresist layer, and the photoresist layer is then developed. The developing of the photoresist comprises removing the exposed or unexposed portions thereof to produce a photoresist pattern having a form identical to or opposite to that of the pattern of the photomask.
The photoresist protects the substrate in the process of forming a semiconductor device or semiconductor chip. In addition, the substrate is processed, e.g., by chemical and physical deposition and plasma etching, using the photoresist pattern as a mask.
An example of a device for performing the above-described photolithography process is disclosed in U.S. Pat. No. 5,963,324.
The technology of photolithography has been regarded as one of the essential technologies in the manufacturing of semiconductor devices. Recently, high degrees of integration characterized by design rules of less than 0.25 microns have been achieved in semiconductor devices. The processes of manufacturing semiconductor devices must, therefore, have characteristics suitable for accomplishing such high degrees of integration.
However, among the characteristics of semiconductor manufacturing processes, air quality, i.e., contamination in the environment in which the processes are carried out, has been a problem. In particular, in photolithography, a chemical such as ammonia or amine reacts with the compound of the resist that is to be activated by the ultraviolet light and thereby prevents such a reaction from taking place, that is, prevents the resist from being exposed during photolithography. A method of passing air through a chemical filter, producing a shower of the air in the vicinity of a lens of the photolithography equipment, and directing the air towards the wafer has been suggested as a means for preventing such chemicals from contaminating the wafer (see Japanese Patent Laid-Open Pub. No. Hei 9-283401).
More specifically, an air shower head is provided in the vicinity of a lens of the exposure device. Clean air is supplied by the air shower head around the wafer to prevent the wafer from being contaminated.
FIG. 1
shows a prior art air circulation system for supplying air into an exposure device. Referring to
FIG. 1
, cooling water is supplied to one side of an air conditioning device
10
through a cooling water line
12
. Air, on the other hand, is supplied to the other side of the air conditioning device
10
through an air circulation line
50
. The air supplied to the air conditioning device
10
through the air circulation line
50
undergoes a heat exchange with the cooling water, and is then supplied to a filtering device
20
. Chemicals are filtered out of the air by the filtering device
20
. The filtered air is then supplied to an air distributing device
30
comprising first, second, and third air supplying lines
50
a
,
50
b
, and
50
c.
Some of the air is supplied to the exposure device (not shown) via the first supplying line
50
a
of the air distributing device
30
. The air traveling through the second supplying line
50
b
passes through a first filter
32
in which particulates in the air are filtered, and then is supplied to a wafer orienting stage or a wafer feeding system. The remainder of the air travels through the third supplying line
50
c
and from there passes through a heat exchanger
36
and a second filter
34
, whereby the temperature of the humidity of the air are regulated. This portion of the air is supplied to an air shower head disposed above a wafer stage of the exposure device.
Referring to
FIGS. 2 and 3
, the air shower head
100
is disposed under a lens system
140
of the exposure device. More specifically, the air shower head
100
is interposed between a wafer (not shown) and the lens system
140
of the exposure device. The air shower head
100
comprises an upper frame
120
and a porous member bottom
130
attached to the bottom of the upper frame
120
.
The upper frame
120
has an upper wall
126
, an inner side wall
124
and an outer side wall
128
. The inner side wall
124
defines a concavity in the top of the shower head
100
, and the upper side wall
126
defines a flat (horizontal) surface at the periphery of the concavity. The air shower head
100
also has a hole
122
extending through the center of both the upper frame
120
and porous member
130
and by which light transmitted through the lens system
140
can propagate to the wafer. The inner side wall
124
together with the porous member
130
form a tapered portion of the air shower head
100
at an intermediate portion thereof as taken in the radial direction. That is, the thickness of the air shower head
100
increases radially outwardly from the hole
122
to the flat surface defined by the upper wall
126
. The shower head
100
is hollow, i.e., a space therein is delimited by the porous member
130
and the upper wall
126
and side walls
124
,
128
of the frame
120
.
Referring now to
FIGS. 3 and 4
, the bottom end
128
a
of the side wall
128
of the upper frame
120
is bonded to the porous member
130
. Similarly, the bottom end
122
a
of the side wall
124
is bonded at the penphery of the hole
122
a
to the porous member
130
.
The porous member
130
is made of a woven fabric comprising chemical resistant yarn. The yarn is woven in the form of a matrix leaving a plurality of fine holes between individual ones of the yarns.
FIG. 4
shows the state in which the bottom end
122
a
of the side wall
124
of the frame
120
is bonded to the porous member
130
at the periphery of the central hole of the shower head. Specifically, the porous member
130
is attached to the frame
120
using a chemical binder
110
.
The third air supplying line
50
c
shown in
FIG. 1
is connected to one side of the air shower head
100
so that air is supplied into the air shower head
100
. The air is injected through the fine holes of the porous member
130
towards the upper surface of the wafer. Thus, a higher pressure is created in the region of the wafer stage than in the surrounding region. As a result, foreign matter is prevented from being introduced onto the wafer from the surrounding region.
However, the air shower head produces organic contaminants during the manufacturing (photolithography) process. Specifically, organic contaminants are continuously produced in the form of a gas from the binder which is used to bond the upper frame
120
to the porous member
130
. Furthermore, the yarn of the porous member is engaged with the upper frame of the air shower head. Thus, the yarn separates into particles or fibers which adhere to the wafer and thereby contaminate the photoresist film.
The present inventors have confirmed, as follows, that the air shower head of the prior art is a source of contamination for a wafer undergoing photolithography. Using the air supply system of
FIG. 1
, air supplied to a wafer stage of an exposure device through the third air supplying line
50
c
and the prior art air shower head was retrieved and supplied to a first bare wafer. Air supplied to a wafer feeding system through the second air supplying line
50
b
, i.e., without passing through an air shower head, was
Ahn Yo-Han
Choi Jai-Heung
Kim Hyun-Joon
Lee Byung-Moo
Adams Russell
Brown Khaled
Samsung Electronics Co,. Ltd.
Volentine & Francos, PLLC
LandOfFree
Air shower head of photolithography equipment for directing... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Air shower head of photolithography equipment for directing..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Air shower head of photolithography equipment for directing... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3167386