Process of using siloxane dielectric films in the...

Details Process of using siloxane dielectric films in the... Process of using siloxane dielectric films in the...

2002-02-13

2003-07-08

Pham, Long (Department: 2814)

Semiconductor device manufacturing: process

Coating with electrically or thermally conductive material

To form ohmic contact to semiconductive material

C438S623000, C438S624000, C438S634000, C438S637000, C438S645000

Reexamination Certificate

active

06589862

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to cured, dual layered dielectric films and to a process for their production. More particularly, the invention pertains to dual layered dielectric films in which a lower layer comprises a non-silicon containing organic polymer and an upper layer comprises an organic, silicon containing polymer. Such films are useful in the manufacture of microelectronic devices such as integrated circuits (IC's).
2. Description of the Related Art
A continuing trend in the field of semiconductor technology is the formation of integrated circuit chips having more and faster circuits thereon. Such ultralarge scale integration has resulted in a continued shrinkage of feature sizes with the result that a large number of devices are available on a single chip. With a limited chip surface area, the interconnect density typically expands above the chip substrate in a multi-level arrangement and so the devices have to be interconnected across these multiple levels.
The interconnects must be electrically insulated from each other except where designed to make contact. Usually electrical insulation requires depositing dielectric films onto a surface. It is known in the art that siloxane resins are useful in the electronic and semiconductor fields to provide a dielectric coating to silicon wafers and other components. Such coatings protect the surface of substrates and form dielectric layers between electric conductors on IC's. Such coatings can be used as protective layers, interlevel dielectric layers, doped dielectric layers to produce transistor like devices, capacitor and capacitor like devices, multilayer devices, 3-D devices, silicon on insulator devices, coatings for superconductors, and the like.
As mentioned above, semiconductor devices often have multiple arrays of patterned interconnect levels that serve to electrically couple individual circuit elements thus forming an integrated circuit. In the past, these interconnect levels have been separated by such insulating dielectric films as a silicon oxide film formed using chemical vapor deposition or plasma enhanced techniques. However, as the size of circuit elements and the spaces between such elements decreases, the relatively high dielectric constant of such silicon oxide films has become a problem.
In order to provide a lower dielectric constant than that of silicon oxide, dielectric films formed from siloxane based resins are becoming widely used. However, while such siloxane films do provide lower dielectric constants than silicon oxide films it has been found that typically the dielectric constants of such films are limited to those of approximately 3.0 or greater. The dielectric constant of such insulating films is an important factor where IC's with low power consumption, crosstalk, and signal delay are required. As IC dimensions continue to shrink, this factor increases in importance. As a result, siloxane based resin materials that can provide insulating films with dielectric constants below 3.0 are very desirable. Furthermore, it would be desirable to have a siloxane based resin which have a high resistance to cracking and low stress when formed in thicknesses of approximately 0.1 &mgr;m to about 1.0 &mgr;m or greater.
In addition, in the production of microelectronic devices, SiO
2
, SiN or SiON are conventionally used as hardmasks or etch stops for the integration of low k organic films. The problem with using these films is that they have relatively high k values (≧4.0) compared with the organic films (<3.0). This invention describes the use of low k, siloxane based polymer films in the integration of low k organic films. This allows the effective dielectric constant to be lower than if conventional films are used.
The different chemical structure of siloxane based polymers compared to non-silicon containing organic polymers require different etch chemistries. Etch chemistries used for low k non-silicon containing organic polymer films typically do not etch siloxane based polymers, SiO
2
, or SiN dielectrics. Integration of organic polymers into subtractive aluminum, damascene or dual damascene schemes typically requires that a SiO
2
, SiN or SiON layer be placed on the organic polymer to act as an etch stop or hardmask to pattern vies and trenches. These layers have high k values (≧4.0) and reduce the effectiveness of using low k organic polymers between metal lines. Using a low k siloxane based organic polymer in a manner similar to conventional SiO
2
, SiON or SiN films as a hardmask or etchstop will reduce effective interline capacitances. According to the invention, a high or low organic content siloxane film is spun onto either baked or cured films of a non-silicon containing low k dielectric film. The high or low organic content siloxane film is used as an etch-stop or a hardmask, similar to standard SiO
2
, SiON or SiN in a variety of integration techniques including subtractive aluminum, and damascene and dual damascene processes.
SUMMARY OF THE INVENTION
The invention provides a dielectric coated substrate such as a microelectronic device which comprises:
(a) a first dielectric composition film on a substrate which comprises a non-silicon containing or substantially non-silicon containing organic polymer; and
(b) a second dielectric composition film on the first dielectric film, which second dielectric composition comprises a polymer having a structure selected from the group consisting of I and II:
[H—SiO
1.5
]
n
[R—SiO
1.5
]
m
,
[H
0.4-1.0
SiO
1.5-1.8
]
n
[R
0.4-1.0
—SiO
1.5-1.8
]
m
,
[H
0-1.0
—SiO
1.5-2.0
]
n
[R—SiO
1.5
]
m
,
[H—SiO
1.5
]
x
[R—SiO
1.5
]
y
[SiO
2
]
z
,  I.
wherein the sum of n and m, or the sum or x, y and z is from about 8 to about 5000, and m and y are selected such that carbon containing substituents are present in an amount of less than about 40 Mole percent; and wherein R, is selected from substituted and unsubstituted straight chain and branched alkyl groups, cycloalkyl groups, substituted and unsubstituted aryl groups, and mixtures thereof;
[HSiO
1.5
]
n
[RSiO
1.5
]
m
,
[H
0.4-1.0
SiO
1.5-1.8
]
n
[R
0.4-1.0
SiO
1.5-1.8
]
m
,
[H
0-1.0
SiO
1.5-2.0
]
n
[RSiO
1.5
]
m
,  II.
wherein the sum of n and m is from about 8 to about 5000 and m is selected such that the carbon containing substituent is present in an amount of from about 40 Mole percent or greater; and
[HSiO
1.5
]
x
[RSiO
1.5
]
y
[SiO
2
]
z
;
wherein the sum of x, y and z is from about 8 to about 5000 and y is selected such that the carbon containing substituent is present in an amount of about 40 Mole % or greater; and wherein R, is selected from substituted and unsubstituted straight chain and branched alkyl groups, cycloalkyl groups, substituted and unsubstituted aryl groups, and mixtures thereof.
The invention also provides a process for forming a dielectric coating on a substrate, such as a microelectronic device, which comprises
(a) forming a first dielectric composition film on a substrate which comprises a nonsilicon containing or substantially non-silicon containing organic polymer; and
(b) forming a second dielectric composition film on the first dielectric film, which second dielectric composition comprises a polymer having a structure selected from the group consisting of I and II:
[H—SiO
1.5
]
n
[R—SiO
1.5
]
m
,
[H
0.4-1.0
SiO
1.5-1.8
]
n
[R
0.4-1.0
—SiO
1.5-1.8
]
m
,
[H
0-1.0
—SiO
1.5-2.0
]
n
[R—SiO
1.5
]
m
,
[H—SiO
1.5
]
x
[R—SiO
1.5
]
y
[SiO
2
]
z
,  I.
wherein the sum of n and m, or the sum or x, y and z is from about 8 to about 5000, and m and y are selected such that carbon containing substituents are present in an amount of less than about 40 Mole percent; and wherein R, is selected from substituted and unsub

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