Active solid-state devices (e.g. – transistors – solid-state diode – With means to control surface effects – Insulating coating
Reexamination Certificate
2002-09-24
2003-11-25
Cuneo, Kamand (Department: 2829)
Active solid-state devices (e.g., transistors, solid-state diode
With means to control surface effects
Insulating coating
C257S914000, C427S487000, C427S488000, C427S489000, C427S495000, C438S758000, C438S778000, C438S780000, C438S788000, C438S789000, C438S790000
Reexamination Certificate
active
06653719
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to a semiconductor technique and more particularly to a silicone polymer insulation film on a semiconductor substrate and a method for forming the film by using a plasma CVD (chemical vapor deposition) apparatus.
2. Description of Related Art
Because of the recent rise in requirements for the large-scale integration of semiconductor devices, a multi-layered wiring technique attracts a great deal of attention. In these multi-layered structures, however, capacitance among individual wires hinders high-speed operations. In order to reduce the capacitance it is necessary to reduce the dielectric constant (relative permittivity) of the insulation film. Thus, various materials having a relatively low dielectric constant have been developed for insulation films.
Conventional silicon oxide films SiO
x
are produced by a method in which oxygen O
2
or nitrogen oxide N
2
O is added as an oxidizing agent to a silicon material gas such as SiH
4
or Si(OC
2
H
5
)
4
and then processed by heat or plasma energy. Its dielectric constant is about 4.0.
Alternatively, a fluorinated amorphous carbon film has been produced from C
x
F
y
H
z
as a material gas by a plasma CVD method. Its dielectric constant ∈ is as low as 2.0-2.4.
Another method to reduce the dielectric constant of insulation film has been made by using the good stability of Si—O bond. A silicon-containing organic film is produced from a material gas under low pressure (1 Torr) by the plasma CVD method. The material gas is made from P-TMOS (phenyl trimethoxysilane, formula 1), which is a compound of benzene and silicon, vaporized by a babbling method. The dielectric constant ∈ of this film is as low as 3.1.
A further method uses a porous structure made in the film. An insulation film is produced from an inorganic SOG material by a spin-coat method. The dielectric constant ∈ of the film is as low as 2.3.
However, the above noted approaches have various disadvantages as described below.
First, the fluorinated amorphous carbon film has lower thermal stability (370° C.), poor adhesion with silicon-containing materials and also lower mechanical strength. The lower thermal stability leads to damage under high temperatures such as over 400° C. Poor adhesion may cause the film to peel off easily. Further, the lower mechanical strength can jeopardize wiring materials.
Oligomers that are polymerized using P-TMOS molecules do not form a linear structure in the vapor phase, such as a siloxane structure, because the P-TMOS molecule has three O—CH
3
bonds. The oligomers having no linear structure cannot form a porous structure on a Si substrate, i.e., the density of the deposited film cannot be reduced. As a result, the dielectric constant of the film cannot be reduced to a desired degree.
In this regard, the babbling method means a method wherein vapor of a liquid material, which is obtained by having a carrier gas such as argon gas pass through the material, is introduced into a reaction chamber with the carrier gas. This method generally requires a large amount of a carrier gas in order to cause the material gas to flow. As a result, the material gas cannot stay in the reaction chamber for a sufficient length of time to cause polymerization in a vapor phase.
Further, the SOG insulation film of the spin-coat method has a problem in that the material cannot be applied onto the silicon substrate evenly and another problem in which a cure system after the coating process is costly.
OBJECT OF THE INVENTION
It is, therefore, a principal object of this invention to provide an improved insulation film and a method for forming it.
It is another object of this invention to provide an insulation film that has a low dielectric constant, high thermal stability, high humidity-resistance and high adhesive strength, and a method for forming it.
It is a further object of this invention to provide a material for forming an insulation film that has a low dielectric constant, high thermal stability, high humidity-resistance and high adhesive strength.
It is a still further object of this invention to provide a method for easily forming an insulation film that has a low dielectric constant without requiring an expensive device.
SUMMARY OF THE INVENTION
One aspect of this invention involves a method for forming an insulation film on a semiconductor substrate by using a plasma CVD apparatus including a reaction chamber, which method comprises a step of directly vaporizing a silicon-containing hydrocarbon compound expressed by the general formula Si
&agr;
O
&bgr;
C
x
H
y
(&agr;, &bgr;, x, and y are integers) and then introducing it to the reaction chamber of the plasma CVD apparatus, a step of introducing an additive gas, the flow volume of which is substantially reduced, into the reaction chamber and also a step of forming an insulation film on a semiconductor substrate by plasma polymerization reaction wherein mixed gases made from the vaporized silicon-containing hydrocarbon compound as a material gas and the additive gas are used as a reaction gas. It is a remarkable feature that the reduction of the additive gas flow also results in a substantial reduction of the total flow of the reaction gas. According to the present invention, a silicone polymer film having a micropore porous structure with low dielectric constant can be produced.
The present invention is also drawn to an insulation film formed on a semiconductor substrate, and a material for forming the insulation film, residing in the features described above.
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patent: 5380555 (1995-01-01), Mine et al.
patent: 5433786 (1995-07-01), Hu et al.
patent: 5494712 (1996-02-01), Hu et al.
patent: 5554570 (1996-09-01), Maeda et al.
patent: 5989998 (1999-11-01), Sugahara et al.
patent: 6051321 (2000-04-01), Lee et al.
patent: 6054379 (2000-04-01), Yau et al.
patent: 6068884 (2000-05-01), Rose et al.
patent: 0826 791 (1998-03-01), None
patent: 10-284486 (1998-10-01), None
ASM Japan K.K.
Cuneo Kamand
Kilday Lisa
Knobbe Martens Olson & Bear LLP
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