Semiconductor device manufacturing: process – Coating of substrate containing semiconductor region or of... – Insulative material deposited upon semiconductive substrate
Reexamination Certificate
1999-06-11
2001-03-20
Lam, Cathy (Department: 1775)
Semiconductor device manufacturing: process
Coating of substrate containing semiconductor region or of...
Insulative material deposited upon semiconductive substrate
Reexamination Certificate
active
06204201
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to cured dielectric films and to a process for the treatment of the surface of such films to remove moisture and other contaminants therefrom. Such treatment is done by electron beam exposure of the dielectric surface in order to prepare it for a subsequent chemical vapor deposition of oxide, nitride or oxynitride layers. These films are useful in the manufacture of integrated circuits.
2. Description of the Related Art
The field of semiconductor technology continually requires 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 therefore the devices have to be interconnected across these multiple levels.
The interconnects must be electrically insulated from each other except where designed to make electrical contact. Usually electrical insulation requires depositing dielectric films onto a surface. It is known in the art that a variety of resins are useful in the semiconductor fields to provide a dielectric coating to silicon wafers and other microelectronic devices. Such coatings protect the surface of substrates and form dielectric layers between electric conductors on integrated circuits. Semiconductor devices have multiple arrays of patterned interconnect levels that serve to electrically couple individual circuit elements thus forming the integrated circuit.
In the processing of microelectronic devices, dielectric layers are typically subjected to planarizing and etching treatments and hence adjacent layers are usually separated by an etch stop or other separation layer. Etch stop layers usually comprises an oxide, nitride or oxynitride film such as a silicon oxide film formed using chemical vapor deposition (CVD) or plasma enhanced CVD (PECVD) techniques. However, the application of such films to dielectric layers has become a problem. This is due to moisture and contaminants such as organic solvents, hydrocarbons and stray particles on the dielectric surface.
It has now been found that such moisture and contaminants can be eliminated from the surface of dielectric films by exposing the surface of the dielectric to electron beam radiation. Such electron beam exposure effectively removes these contaminants and allows the surface to more readily accept chemical vapor deposited oxide, nitride or oxynitride films.
SUMMARY OF THE INVENTION
The invention provides a process for treating a dielectric layer on a substrate which comprises
(a) heating a surface of the dielectric layer and exposing the dielectric layer to electron beam irradiation under vacuum conditions, for a sufficient time, temperature, electron beam energy and electron beam dose to remove substantially all moisture and/or contaminants from the surface of the dielectric layer; and
(b) chemical vapor depositing a chemical vapor deposit material onto the surface of the dielectric layer while maintaining said vacuum conditions.
The invention also provides a process for producing a support for a microelectronic device which comprises:
(a) applying a dielectric layer onto a substrate;
(b) curing the dielectric layer;
(c) heating a surface of the dielectric layer and exposing the dielectric layer to electron beam irradiation under vacuum conditions, for a sufficient time, temperature, electron beam energy and electron beam dose to remove substantially all moisture and/or contaminants from the surface of the dielectric layer; and
(d) chemical vapor depositing chemical vapor deposit material onto the surface of the dielectric layer while maintaining said vacuum conditions.
The invention further provides a A support for a microelectronic device which comprises:
(a) a substrate;
(b) a cured dielectric layer on the substrate, the surface of which dielectric layer has been exposed to sufficient electron beam radiation to render the dielectric layer surface substantially devoid of moisture and contaminants; and
(c) a chemical vapor deposited chemical vapor deposit material on the surface of the dielectric layer.
The invention also provides a microelectronic device which comprises:
(a) a substrate;
(b) a cured dielectric layer on the substrate, the surface of which dielectric layer has been exposed to sufficient electron beam radiation to render the dielectric layer surface substantially devoid of moisture and contaminants;
(c) a chemical vapor deposited chemical vapor deposit material layer on the surface of the dielectric layer; and
(d) a pattern of conductive lines on the chemical vapor deposit material layer.
DETAILED DESCRIPTION OF THE INVENTION
The first step in conducting the process of the present invention is to form a dielectric composition layer on a substrate. Typical substrates are those suitable to be processed into an integrated circuit or other microelectronic device. Suitable substrates for the present invention non-exclusively include semiconductor materials such as gallium arsenide (GaAs), germanium, lithium niobate, silicon and compositions containing silicon such as silicon germanium, crystalline silicon, polysilicon, amorphous silicon, epitaxial silicon, and silicon dioxide (SiO
2
) and mixtures thereof.
On the surface of the substrate is an optional pattern of raised lines, such as metal, oxide, nitride or oxynitride lines which are formed by well known lithographic techniques. Suitable materials for the lines include silica, silicon nitride, titanium nitride, tantalum nitride, aluminum, aluminum alloys, copper, copper alloys, tantalum, tungsten and silicon oxynitride. These lines form the conductors or insulators of an integrated circuit. Such are typically closely separated from one another at distances of about 20 micrometers or less, preferably 1 micrometer or less, and more preferably from about 0.05 to about 1 micrometer.
The dielectric composition may comprise any of a wide variety of dielectric forming materials which are well known in the art for use in the formation of microelectronic devices. Such may be organic or inorganic. The dielectric layer may nonexclusively include silicon containing spin-on glasses, i.e. silicon containing polymer such as an alkoxysilane polymer, a silsesquioxane polymer such as a hydrogen silsesquioxane polymer, a siloxane polymer, a poly(arylene ether), a fluorinated poly(arylene ether), other polymeric dielectric materials, nanoporous silica or mixtures thereof.
One useful polymeric dielectric materials useful for the invention includes a nanoporous silica alkoxysilane polymer formed from an alkoxysilane monomer which has the formula:
wherein at least 2 of the R groups are independently C
1
to C
4
alkoxy groups and the balance, if any, are independently selected from the group consisting of hydrogen, alkyl, phenyl, halogen, substituted phenyl. Preferably each R is methoxy, ethoxy or propoxy. Such are commercially available from AlliedSignal as Nanoglass™. The most preferred alkoxysilane monomer is tetraethoxysilane (TEOS). Also useful are hydrogensiloxanes which have the formula [(HSiO1.5)
x
O
y
]
n
, hydrogensilsesquioxanes which have the formula (HSiO
1.5
)
n
, and hydroorganosiloxanes which have the formulae [(HSiO
1.5
)
x
O
y
(RSiO
1.5
)
z
]
n
, [(HSiO
1.5
)
x
(RSiO
1.5
)
y
]
n
and [(HSiO
1.5
)
x
O
y
(RSiO
1.5
)
z
]
n
. In each of these polymer formulae, x=about 6 to about 20, y=1 to about 3, z=about 6 to about 20, n=1 to about 4,000, and each R is independently H, C
1
to C
8
alkyl or C
6
to C
12
aryl. The weight average molecular weight may range from about 1,000 to about 220,000. In the preferred embodiment n ranges from about 100 to about 800 yielding a molecular weight of from about 5,000 to about 45,000. More preferably, n ranges from about 250 to about 650 yielding a
Electron Vision Corporation
Lam Cathy
Roberts & Mercanti LLP
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