Coating processes – Coating by vapor – gas – or smoke – Mixture of vapors or gases utilized
Reexamination Certificate
1999-04-30
2001-11-13
Meeks, Timothy (Department: 1762)
Coating processes
Coating by vapor, gas, or smoke
Mixture of vapors or gases utilized
C427S255600, C438S763000, C438S780000, C438S785000, C438S790000
Reexamination Certificate
active
06316055
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to products comprising oxide films where low temperature deposition is needed. The low-temperature oxide films are used in the manufacture of semiconductor devices and in the food packing industry. The invention relates to the deposition of dielectric layers in the manufacturing of semiconductor thin films. More specifically, this invention relates to the deposition of oxide dielectric thin films at temperatures near or below room temperature. Additionally, this invention relates to the manufacture of diffusion barriers to prevent food oxidation, and barriers to the transmission of ultraviolet radiation to increase the shelf life of food products.
2. Description of Related Art
Conventional methods for depositing dielectric materials such as SiO
2
in semiconductor manufacture involve high temperature chemical vapor deposition (CVD), spin-on-glass (SOG) methods, rf magnetron sputtering, (Kollakowski et al.,
Vac. Sci. Technol. B
. 14(3):1712-1718 (1996); Jones, U.S. Pat. No. 3,442,686, evaporation (Lucovsky et al.
Thin Film Processes II
, Eds. J. L. Vossen & W. Kern, Academic Press, NY, pp: 565 (1991), and plasma processes (Wen-Fa et al.
Appl. Surf. Sci
. 99:237-243 (1996); Lee et al.,
J. Electrochem. Soc
. 143(4):1443-1451)1996); Plais et al.
J. Electrochem. Soc
. 139(5):14989-14995 (1992); Sano et al.,
Mat. Res. Soc. Symp. Proc
. 396:539-543 (1996); Decrosta et al.,
J. Electrochem. Soc
. 143(3):1079-1084 (1996); Samit et al.,
Adv. Mat. Optics Electron
6:73-82 (1996)).
Moreover, in the food packaging industry, oxide films have been used to provide oxidant barriers and ultraviolet barriers to retard spoilage. However, the plasma methods used to deposit SiO
2
or TiO
2
have several disadvantages.
However, each of these processes has major drawbacks in the manufacture of semiconductor devices of sub-micron dimensions. Spin-on-glass processes result in relatively uneven films. Moreover, spin-on glass has high impurity levels and poor gap filling abilities. This results in inherent problems with device reliability. The other methods described all suffer from problems associated with exposing the substrate to high temperatures or high powered plasmas. Subjecting the substrate to the temperatures required for conventional CVD, plasma, or rf magnetron sputtering can cause the breakdown of thermally labile components of the semiconductor devices. Moreover, as newer low dielectric materials with lower thermal stability are being used, the maximum temperatures to which semiconductor devices can be subjected during manufacture decreases. Because SiO
2
and other oxide dielectrics confer desirable properties of dielectric layers, such as thermal stability, mechanical strength, low impurity, good adherence to substrates and good barrier to impurities, there is a need to develop methods for the low-temperature deposition of oxide dielectric materials in semiconductor manufacture.
To be compatible with the low dielectric constant polymer materials, the SiO
2
must be deposited at low temperatures, less than the glass transition temperature (Tg) of polymers. Also, to minimize stress between films, which can cause delamination, and introduce charges at the interface, the films should all be deposited at the same temperatures. The interface charges introduce electronic signal degradation which defeats the purpose of using low dielectric constant materials to minimize cross-talk.
One type of method for the low temperature deposition of SiO
2
is via remote dissociation and deposition. In this process, the precursor for the dielectric material is subjected to dissociating conditions in which reactive intermediates are generated. The intermediates are then transported to another site, where the intermediates can react with each other to form a thin film on the semiconductor substrate. One proposal for remote formation of a relative long-lived reactive intermediate was for a —Si—H and was called HOMOCVD (Scott et al.,
Semiconductors and Semimetals
, Vol. Ed. J. I. Pankove, Academic Press, Boston, Vol. 21A: 123-49 (1984). However, this method is not appropriate for the deposition of oxides, possibly due to high hydrogen content in the films leading to reduced reliability.
To overcome the deficiencies in the prior art, one object of this invention is the manufacture of oxide dielectric materials with high mechanical and thermal stability, high dielectric strength, and high transparency to visible electromagnetic radiation.
Another object of this invention is the manufacture of oxide dielectric materials at temperatures near room temperature.
A further object of the invention is the high efficiency deposition of oxide dielectric films from organometallic precursors.
Yet another object of this invention is the manufacture of integrated circuit chips using oxide dielectric films deposited at near or below room temperature.
A further object of this invention is the manufacture of low-temperature oxide films to reduce the diffusion of oxidants and reduce the transmission of ultraviolet light into food products.
SUMMARY OF THE INVENTION
This invention involves the use of remote thermal dissociation of organometallic precursors to deposit oxide films at a site remote from the site of dissociation. Organometallic precursors can be thermally dissociated at high-temperatures into long-lived reactive intermediates and can be transported to a remote site for near-room temperature deposition and polymerization on a substrate, thereby forming a thin film of the oxide polymer. The substrate can be maintained at a temperature well below that needed for efficient dissociation of precursors. The films deposited using the methods of this invention have unexpectedly low leakage currents, based on the prior art films made using conventional, high-temperature deposition methods.
Thus, one aspect of this invention is the use of alkoxysilane precursors to generate reactive intermediates with a sufficiently low activation energy to form high quality SiO
2
thin films.
A further aspect of this invention is the manufacture of oxide dielectric thin films deposited at near room temperature.
Yet another aspect of this invention is the regulation of the physical properties of the oxide film by controlling the conditions of deposition.
A further aspect of this invention is the regulation of the chemical properties of the oxide film by controlling the conditions of deposition.
Another aspect of this invention is the regulation of the electrical properties of the oxide film by controlling the conditions of deposition.
A yet other aspect of this invention is the regulation of the optical properties of the oxide film by controlling the conditions of deposition.
Another aspect of this invention is the manufacture of semiconductor devices incorporating the oxide dielectric materials deposited at near or below room temperature.
A further aspect of this invention is the manufacture of low-temperature oxide films which inhibit the diffusion of oxidants and the transmission of ultraviolet light for food packaging.
REFERENCES:
patent: 5302555 (1994-04-01), Yu
patent: 5352487 (1994-10-01), Klinedinst et al.
patent: 6086679 (2000-07-01), Lee et al.
Lee, J. “Transport Polymerization of Gaseous Intermediates and Polymer Crystals Growth”, J. Macromol. Sci.-Rev. Macromol. Chem., C16(1), 79-127 (1977-78), no month available.
Desu Seshu B.
Senkevich John J.
Fliesler Dubb Meyer & Lovejoy
Meeks Timothy
Virginia Tech Intellectual Properties Inc.
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