Adhesive bonding and miscellaneous chemical manufacture – Differential fluid etching apparatus – With radio frequency antenna or inductive coil gas...
Reexamination Certificate
2002-10-29
2004-12-21
Lund, Jeffrie R. (Department: 1763)
Adhesive bonding and miscellaneous chemical manufacture
Differential fluid etching apparatus
With radio frequency antenna or inductive coil gas...
C156S345290, C156S345330, C118S715000, C118S7230IR
Reexamination Certificate
active
06833052
ABSTRACT:
BACKGROUND OF THE INVENTION
One of the primary steps in the fabrication of modem semiconductor devices is the formation of a thin film on a semiconductor substrate by chemical reaction of gases. Such a deposition process is referred to as chemical vapor deposition (CVD). Conventional thermal CVD processes supply reactive gases to the substrate surface where heat-induced chemical reactions can take place to produce the desired film. Plasma CVD processes promote the excitation and/or dissociation of the reactant gases by the application of radio frequency (RF) energy to the reaction zone proximate the substrate surface thereby creating a plasma of highly reactive species. The high reactivity of the released species reduces the energy required for a chemical reaction to take place, and thus lowers the required temperature for such CVD processes.
In one design of plasma CVD chambers, the vacuum chamber is generally defined by a planar substrate support, acting as a cathode, along the bottom, a planar anode along the top, a relatively short sidewall extending upwardly from the bottom, and a dielectric dome connecting the sidewall with the top. Inductive coils are mounted about the dome and are connected to a source radio frequency (SRF) generator. The anode and the cathode are typically coupled to bias radio frequency (BRF) generators. Energy applied from the SRF generator to the inductive coils forms an inductively coupled plasma within the chamber. Such a chamber is referred to as a high density plasma CVD (HDP-CVD) chamber.
In some HDP-CVD chambers, it is typical to mount two or more sets of equally spaced gas distributors, such as nozzles, to the sidewall and extend into the region above the edge of the substrate support surface. The gas nozzles for each set are coupled to a common manifold for that set; the manifolds provide the gas nozzles with process gases. The composition of the gases introduced into the chamber depends primarily on the type of material to be formed on the substrate. For example, when a fluorosilicate glass (FSG) film is deposited within the chamber, the process gases may include, silane (SiH
4
), silicon tetrafluoride (SiF
4
), oxygen (O
2
) and argon (Ar). Sets of gas nozzles are commonly used because it is preferable to introduce some gases into the chamber separately from other gases, while other gases can be delivered to a common set of nozzles through a common manifold. For example, in the above FSG process it is preferable to introduce SiH
4
separately from O
2
, while O
2
and SiF
4
can be readily delivered together. The nozzle tips have exits, typically orifices, positioned in a circumferential pattern spaced apart above the circumferential periphery of the substrate support and through which the process gases flow.
As device sizes become smaller and integration density increases, improvements in processing technology are necessary to meet semiconductor manufacturers' process requirements. One parameter that is important in such processing is film deposition uniformity. To achieve a high film uniformity, among other things, it is necessary to accurately control the delivery of gases into the deposition chamber and across the wafer surface. Ideally, the ratio of gases (e.g., the ratio of O
2
to (SiH
4
+SiF
4
)) introduced at various spots along the wafer surface should be the same.
FIG. 1
illustrates a typical undoped silicate glass (USG) deposition thickness variation plot
46
for a conventional deposition chamber such as the chamber described above. The average thickness is shown by base line
48
. As can be seen by plot
46
, there is a relatively steep increase in thickness at end points
50
and
52
of plot
46
corresponding to the periphery
42
of substrate
20
. The center
54
of plot
46
also dips down substantially as well.
U.S. patent application Ser. No. 08/571,618 filed Dec. 13, 1995, the disclosure of which is incorporated by reference, discloses how plot
46
can be improved through the use of a center nozzle
56
coupled to a third gas source
58
through a third gas controller
60
and a third gas feed line
62
. Center nozzle
56
has an orifice
64
positioned centrally above substrate support surface
16
. Using center nozzle
56
permits the modification of USG deposition thickness variation plot
46
from that of
FIG. 1
to exemplary plot
68
of FIG.
2
. Exemplary deposition thickness variation plot
68
is flat enough so that the standard deviation of the deposition thickness can be about 1 to 2% of one sigma. This is achieved primarily by reducing the steep slope of the plot at end points
50
,
52
and raising in the low point at center
54
of plot
46
.
With the advent of multilevel metal technology in which three, four, or more layers of metal are formed on the semiconductors, another goal of semiconductor manufacturers is lowering the dielectric constant of insulating layers such as intermetal dielectric layers. Low dielectric constant films are particularly desirable for intermetal dielectric (IMD) layers to reduce the RC time delay of the interconnect metallization, to prevent cross-talk between the different levels of metallization, and to reduce device power consumption.
Many approaches to obtain lower dielectric constants have been proposed. One of the more promising solutions is the incorporation of fluorine or other halogen elements, such as chlorine or bromine, into a silicon oxide layer. It is believed that fluorine, the preferred halogen dopant for silicon oxide films, lowers the dielectric constant of the silicon oxide film because fluorine is an electronegative atom that decreases the polarizability of the overall SiOF network. Fluorine-doped silicon oxide films are also referred to as fluoro silicate glass (FSG) films.
From the above, it can be seen that it is desirable to produce oxide films having reduced dielectric constants such as FSG films. At the same time, it is also desirable to provide a method to accurately control the delivery of process gases to all points along the wafer's surface to improve characteristics such as film uniformity. As previously discussed, one method employed to improve film deposition uniformity is described in U.S. patent application Ser. No. 08/571,618 discussed above. Despite this improvement, new techniques for accomplishing these and other related objectives are continuously being sought to keep pace with emerging technologies.
SUMMARY OF THE INVENTION
The present invention is directed toward an improved deposition chamber that incorporates an improved gas delivery system. The gas delivery system helps ensure that the proper ratio of process gases is uniformly delivered across a wafer's surface. The present invention is also directed toward a method of depositing FSG films having a low dielectric constant and improved uniformity. This is achieved by a combination of (1) the uniform application of the gases (preferably silane, fluorine-supplying gases such as SiF
4
or CF
4
, and oxygen-supplying gases such as O
2
or N
2
O) to the substrate and (2) the selection of optimal flow rates for the gases, which preferably have been determined as a result of tests using the particular chamber. In some embodiments, the deposited FSG film has a dielectric constant as low as 3.4 or 3.3. Preferably, the dielectric constant of the FSG film is at least below 3.5.
The improved deposition chamber includes a housing defining a deposition chamber. A substrate support is housed within the deposition chamber. A first-gas distributor has orifices or other exits opening into the deposition chamber in a circumferential pattern spaced apart from and generally overlying the circumferential periphery of the substrate support surface. A second gas distributor, preferably a center nozzle, is used and is positioned spaced apart from and above the substrate support surface, and a third gas distributor delivers an oxygen-supply gas (e.g., O
2
) to the chamber through the top of the housing in a region generally centrally above the substrate. This is preferably achieved
Collins Alan W.
Ishikawa Tetsuya
Li Shijian
Redeker Fred C.
Wang Yaxin
Applied Materials Inc.
Lund Jeffrie R.
Townsend & Townsend & Crew
LandOfFree
Deposition chamber and method for depositing low dielectric... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Deposition chamber and method for depositing low dielectric..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Deposition chamber and method for depositing low dielectric... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3305423