Adhesive bonding and miscellaneous chemical manufacture – Differential fluid etching apparatus – With heating or cooling means for apparatus part other than...
Reexamination Certificate
2002-09-06
2004-09-28
Hassanzadeh, Parviz (Department: 1763)
Adhesive bonding and miscellaneous chemical manufacture
Differential fluid etching apparatus
With heating or cooling means for apparatus part other than...
C156S345310, C118S724000, C118S719000
Reexamination Certificate
active
06797109
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to equipment for manufacturing semiconductor devices, and more particularly, to a process chamber used in the manufacture of semiconductor devices, capable of reducing contamination by particulates.
2. Description of the Related Art
In general, integrated circuits (ICs) are manufactured on semiconductor wafers formed of, for example, silicon. During the manufacture of the ICs, a series of steps, for example, photo masking, deposition of material layers, oxidation, nitridation, ion implantation, diffusion and etching, are conducted to obtain a final product. Most of these steps are carried out in a process chamber. Thus, reducing contamination by particulate in the process chamber has been recognized as a critical factor for determining the quality of a semiconductor device. Particulates are generated in a process chamber depending on the structure of the process chamber, the material used to form the chamber, and the types of reaction gases used in the chamber. In general, the process chamber is contaminated by particulates due to the following two reasons.
The first reason, which usually occurs in a process chamber used for etching, is the difference in temperature between edge rings (or focus rings) near a semiconductor wafer and the parts from which the process chamber is constructed. The second reason, which usually occurs in a process chamber used for a deposition process, is the unsmooth flow of a reaction gas near guide rings for guiding the edge of a semiconductor wafer.
FIG. 1
is a view illustrating the generation of particulates in a process chamber during an etching process. In detail,
FIG. 1
is a sectional view illustrating an electrostatic chuck supporting a semiconductor wafer in a conventional process chamber for an etching process using plasma.
FIG. 2
is an enlarged view of the edge (portion A) of the semiconductor wafer shown in
FIG. 1
, and
FIG. 3
is a plan view of FIG.
1
.
Referring to
FIG. 1
, an electrostatic chuck
20
holds a semiconductor wafer
10
using electrostatic adsorption. Although not shown in
FIG. 1
, a power supply for supplying a high voltage is connected to the electrostatic chuck
20
to induce static electricity. Lift pins
21
for moving the semiconductor wafer
10
up and down when loading or unloading the semiconductor wafer
10
, pass through the center of the electrostatic chuck
20
. The lift pins
21
are in contact with a support plate
22
installed below the electrostatic chuck
20
. The support plate
22
moves upwards in response to force applied by an external lifter (not shown), in a direction indicated by an arrow
23
. The lift pins
21
move upwards in response to upward movement of the support plate
22
. Then, the lift pins
21
protrude past the surface of the electrostatic chuck
20
, and the semiconductor wafer
10
supported by the lift pins
21
is separated from the surface of the electrostatic chuck
20
.
Edge rings
24
are installed at the upper edges of the electrostatic chuck
20
to fix the semiconductor wafer
10
. As shown in
FIGS. 2 and 3
, the edge ring
24
is separated from the edge of the semiconductor wafer
10
by a small gap
25
. Also, there is a space
26
between part of the surface of the edge ring
24
and the periphery of the bottom surface of the semiconductor wafer
10
. Also, a coupling ring
27
made of aluminum (Al) is interposed between the edge ring
24
and the electrostatic chuck
20
. The semiconductor wafer
10
is surrounded by a focus ring
28
. The focus ring
28
draws a plasma forming region to the edge of the semiconductor wafer
10
during the etching process, such that the plasma forming region is uniformly formed across the semiconductor wafer
10
.
However, in such a conventional process chamber, plasma enters into the small gap
25
between the edge ring
24
and the edge of the semiconductor wafer
10
, and thus the bottom surface of the semiconductor wafer may be etched. Polymers, which are byproducts generated by the etching, adhere to the bottom surface of the semiconductor wafer
10
and bind the edge ring
24
to the electrostatic chuck
20
. When the edge ring
24
is separated from the electrostatic chuck
20
for repair and maintenance after the process is completed, the edge ring
24
can be broken due to it being bound to the electrostatic chuck
20
by the polymer.
When the etching is repeated several times, the edge ring
24
is etched along its inner circumference, so that the gap between the edge ring
24
and the semiconductor wafer
10
becomes wider. As a result, the edge ring
24
strikes against the edge of a platen zone of the semiconductor wafer (portion B of FIG.
3
), so that a part of the semiconductor wafer
10
can be broken.
FIG. 4
is another view illustrating the generation of particulates in a process chamber used for an etching process. In detail,
FIG. 4
is a sectional view of an electrostatic chuck
20
in which a focus ring
40
is included but not the edge ring shown in FIG.
3
.
Referring to
FIG. 4
, a semiconductor wafer
10
is held by an electrostatic force produced by an electrostatic chuck
20
, through which lift pins
21
are inserted. An annular focus ring
40
is arranged around the edge of the electrostatic chuck
20
. The focus ring
40
draws a plasma forming region to the edge of the semiconductor wafer
10
during the etching process, such that the plasma forming region is uniformly formed across the semiconductor wafer
10
. Further, the focus ring
40
acts as an edge ring, thereby preventing the semiconductor wafer
10
from deviating from its original position.
The upper part of the focus ring
40
is rounded, and the height of the focus ring is higher than the surface of the semiconductor wafer
10
. Most of the polymers generated in the process chamber accumulate on the protruding top of the focus ring
40
. Here, the amount and type of accumulated polymer varies according to the material forming the metal layer to be etched, and the distribution in temperature in the reaction chamber. For example, if a metal layer to be etched is formed of tungsten (W), an etching gas used for etching the metal layer, for example, SF
6
, reacts with the Al component of the process chamber and increases the concentration of Al in the process chamber, thereby generating floating particulates of Al
X
F
Y
. Also, if a metal layer to be etched is formed of Al, an etching gas used for etching the metal layer, for example, Cl
2
or BCl
3
, generates polymers of Al
X
Cl
Y
. Such polymers lie on the protruding portion of the focus ring
40
, which is the farthest away from a heat source (not shown), and may fall onto the semiconductor wafer
10
due to a change in internal pressure, thereby causing the process to fail.
FIG. 5
is a sectional view illustrating the generation of particulates in a process chamber used for a deposition process.
FIG. 5
shows a wafer support portion of a process chamber for chemical vapor deposition (CVD).
FIG. 6
is an enlarged view of the portion C of FIG.
5
.
Referring to
FIGS. 5 and 6
, a semiconductor wafer
10
is seated on a wafer chuck
50
, and a heater
51
is placed below the wafer chuck
50
. The semiconductor wafer
10
is guided by an annular guide ring
52
placed around the edge of the wafer chuck
50
. However, because a space d between the guide ring
52
and the wafer chuck
50
is very narrow, a reaction gas is stagnant in the space d and does not flow smoothly therein. As a result, the reaction gases staying in the space d react with each other abnormally, which results in the growth of an undesirable material layer
53
. The material layer
53
may undesirably contaminate the wafer
10
.
As described above, a process chamber used for etching or deposition produces particulates for various reasons, increasing the likelihood of failure of the semiconductor devices on wafer
10
. Thus, it would be desirable to prevent such a failure by eliminating factors which may cause the generation of pa
Cho Jung-hun
Cho Sung-bum
Choi Jong-wook
Chung Ju-hyuck
Kim Hee-duk
Hassanzadeh Parviz
Lee & Sterba, P.C.
Samsung Electronics Co,. Ltd.
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