Semiconductor device manufacturing: process – Having organic semiconductive component
Reexamination Certificate
1999-09-28
2002-08-13
Sherry, Michael J. (Department: 2829)
Semiconductor device manufacturing: process
Having organic semiconductive component
Reexamination Certificate
active
06432739
ABSTRACT:
The invention concerns a method for generating electrical conducting or semiconducting structures in two or three dimensions in a composite matrix, wherein the matrix comprises none or more materials provided in spatially separate and homogenous material structures, wherein the materials in response to the supply of energy can undergo specific and/or chemical changes of state which cause transition from an electrical non-conducting state to an electrical conducting or semiconducting state or vice versa, or a change in the electrical conduction mode of the material, and wherein each material structure is made in the form of a thin layer. The invention also concerns a method for erasing globally electrical conducting or semiconducting structures generated in two or three dimensions in a composite matrix, wherein the matrix comprises two or more material provided in spatially separate and homogenous material structures, wherein the materials in response to the supply of energy can undergo specific and/or chemical changes of state which cause transition from an electrical non-conducting state to an electrical conducting or semiconducting state or vice versa, or a change in the electrical conduction mode of the material, and wherein each material structure is made in the form of a thin layer. Finally, the invention concerns an electric field generator/modulator (EFGM) for patterning and generating electrical conducting or semiconducting structures in two or three dimensions in a composite matrix, wherein the matrix comprises one or more materials respectively provided in one or more spatially separate and homogenous material structures, wherein the materials in response to the supplied energy can undergo specific and/or chemical changes of state which cause transition from an electrical non-conducting state to an electrical conducting or semiconducting state and vice versa, or a change in the conduction mode of the material, and wherein each material structure is made in the form of a thin layer.
More particularly the present invention concerns the fabrication of two- and three-dimensional isolating, resistive, conducting or semiconducting patterns and structures for use in electronic circuits which most particularly consist of a single or several stacked layers of thin films.
The evolution of microelectronic technology shows a steady trend towards smaller dimensions and reduced costs of the devices. Well-substantiated predictions show that the performance is going to increase, while the price per unit or device will decrease. However, today's microelectronic technology is substantially based on crystalline silicon and shows an increasing tendency towards diminishing returns, mainly due to the inherent limitations associated with the complexity of ultra-high resolution lithography and increasing demands of the material processing. Extrapolations of the present technologies based on crystalline silicon may hence not be expected to offer dramatic breakthroughs in regard of either performance or price and future improvements shall require manufacturing plants and manufacturing equipment which are extremely capital-intensive.
Microelectronics based on thin-film technology may on the other hand confidently be predicted to deliver in the near future products representing real breakthroughs in regard of performance as well as of price. The shift from crystalline inorganic semiconductors to microcrystalline, polycrystalline or amorphous inorganic or organic semiconductors will introduce entirely novel boundary conditions with regard to the production of microelectronics and particularly by the blanks having form factors which make large areas possible, i.e. the substrates may be large sheets instead of wafers cut from blanks of limited size, and great flexibility with regard to architectures, something which will be essential factors in the expected development of tomorrow's electronic technology. In the present invention special emphasis will be placed on the use of organic materials due to the ease whereby they may be processed with basis in the use of large areas and multilayer blanks will precisely controllable thickness, as well as their vast potential for chemical tailoring of the desired material properties.
Particularly before the use of electronics based on amorphous materials can fulfill their expected potential, further developments in certain areas are required. In the recent years an effort has been made to improve the semiconducting properties of organic semiconducting thin-film materials, which have given dramatic and rapid increase in the transistor performance up to a point where organic-based transistors may now compete with transistors based on amorphous silicon (see for instance Y. -Y. Lin, D. J. Gundlach, S. F. Nelson ad T. N. Jackson, “Pentacene-Based Organic Thin Film Transistors”, IEEE Transactions on Electron Devices, August 1997). Other on-going projects will lead to coating processes for thin film in order to generate organic and amorphous silicon semiconductors at low temperatures and with compatibility to a broad range of organic and inorganic substrate materials. This has lead to the development of extremely cheap electronic devices with large areas based on the use of high-volume manufacturing methods.
In spite of this development a wholly satisfactory solution to how the fabrication technology shall be adapted and made suitable for a low-cost flexible high-volume production of electrical connections in the thin-film structures forming the electronic circuits is still lacking. Currently thin-film devices are based on amorphous silicon manufactured with current paths and conductors patterned with traditional methods such as lithography and vacuum metallization. The latter method has formerly also been applied to circuits for demonstration of organic-based semiconductor thin-film devices (see for instance A. R. Brown & al. “Logic gates made from polymer transistors and their use of ring oscillators”, Science 270:972-974 (1995)). Alternatively, screen printing with conducting “ink” has been used to make transistors on flexible polymer substrates (see for instance F. Garnier & al., “All-polymer field-effect transistor realized by printing techniques”, Science 265:1884-1886 (1994)). Even though lithography may provide high resolution, it is relatively complex and includes typically wet chemistry steps which are undesirable in high-volume production of multilayer organic thin-film structures. Screen printing with ink is also far from ideal, as it only provides low to moderate resolution besides being a “wet” method.
As examples of prior art such it is evident from available patent literature may also be mentioned U.S. Pat. No. 5,043,251 (Sonnenschein & al.) which discloses a process for three-dimensional lithography of amorphous polymers for generating a momentary permanent pattern in a polymer material and which comprises steps for providing doped non-crystalline layers or films of a polymer in a stable amorphous state under humane operating conditions. In manufacturing the patterns the film is masked optically and is exposed through the mask to radiation with sufficient intensity to cause ablation of the exposed portions such that a distinct three-dimensional imprint is generated in the film. This process has among other been proposed for use in the manufacture of an optical data storage disk. Further it is from U.S. Pat. No. 5,378,916 (Mantell) known a photo-sensitive device in the form of a single-crystal structure, wherein different portions of the structure may have different compositions. Particular the structure forms a two-dimensional array and a first photosensitive portion comprises a material which generates electron-hole pairs when it is exposed to light within a predetermined first wavelength range, while another photosensitive portion comprises a material which is adapted to generate electron-hole pairs when it is exposed to light within another wavelength range distinctively different from the first wavelength range. Yet further it is fro
Gudesen Hans Gude
Leistad Geirr I.
Nordal Per-Erik
Sarkar Asok Kumar
Sherry Michael J.
Thin Film Electronics ASA
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