Metal working – Barrier layer or semiconductor device making
Reexamination Certificate
2001-10-17
2004-08-17
Flynn, Nathan J. (Department: 2826)
Metal working
Barrier layer or semiconductor device making
C438S099000, C438S795000, C438S799000
Reexamination Certificate
active
06776806
ABSTRACT:
A method for generating electrically conducting and/or semiconducting structures in two or three dimensions, a method for erasing the same structures and an electric field generator/modulator for use with the method for generating.
BACKGROUND OF THE INVENTION
The invention concerns a method for generating electrically conducting and/or semiconducting structures in two or three dimensions in a composite matrix. The matrix comprises one or more materials provided in spatially separate and homogenous material structures. The materials can undergo specific physical and/or chemical changes of state in response to the supply of energy, which cause transition from an electrically non-conducting state to an electrically conducting and/or semiconducting state or vice versa, or a change in the electrical conduction mode of the of the material. Each material structure is made in the form of a thin layer.
The invention also concerns a method for globally erasing electrically conducting and/or semiconducting structures generated in two or three dimensions in a composite matrix. The matrix comprises two or more materials provided in spatially separate and homogenous material structures. The materials can undergo specific physical and/or chemical changes of state in response to the supply of energy, which cause transition from an electrically non-conducting state to an electrically conducting and/or semiconducting state or vice versa, or a change in the electrical conduction mode of the of the material. 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 conducting and/or semiconducting structures in two or three dimensions in a composite matrix. The matrix comprises one or more materials provided in one or more spatially separate and homogenous material structures, respectively. The materials can undergo specific and/or chemical changes of state in response to the supply of energy, which cause transition from an electrically non-conducting state to an electrically conducting and/or semiconducting state or vice versa, or a change in the electrical conduction mode of the of the material. 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 and/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 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 are not expected to offer dramatic breakthroughs in either performance or price. Future improvements shall require manufacturing plants and manufacturing equipment, which are extremely capital-intensive.
On the other hand, microelectronics based on thin-film technology are predicted to deliver products representing real breakthroughs in both performance and price in the near future. 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 Particularly, the blanks can have form factors, which make large areas possible, i.e., the substrates can be large sheets instead of wafers cut from blanks of limited size, and great flexibility with regard to architectures. These are 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 can be processed. Additionally, organic materials allow for the use of large areas and multilayer blanks with precisely controllable thickness, and provide vast potential for chemical tailoring of the desired material properties.
Before the use of electronics based on amorphous materials can fulfill their expected potential, further developments in certain areas are required. In recent years an effort has been made to improve the semiconducting properties of organic semiconducting thin-film materials. These improvements have dramatic and rapid increase in transistor performance to a point where organic-based transistors can now compete with transistors based on amorphous silicon (see for instance Y.-Y. Lin, D. J. Gundlach, S. F. Nelson and 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 with compatibility to a broad range of organic and inorganic substrate materials. This has lead to the development of extremely electronic devices with large areas based on the use of high-volume manufacturing methods.
In spite of this development a wholly satisfactory solution is still lacking for adaptation of the fabrication technology for low-cost flexible high-volume production of electrical connections in the thin-film structures forming the electronic circuits. 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 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. Gamier & 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 wet chemistry steps that 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, and is a “wet” method.
U.S. Pat. No. 5,043,251 (Sonnenschein & al.) is an example of prior art that discloses a process for three-dimensional lithography of amorphous polymers for generating a momentary permanent pattern in a polymer material. The process comprises steps for providing doped non-crystalline layers or films of a polymer in a stable amorphous state under humane operating conditions. The film is masked optically and is exposed through the mask to radiation with sufficient intensity to cause ablation of the exposed portions to manufacture the patterns such that a distinct three-dimensional imprint is generated in the film. This process is used in the manufacture of optical data storage disks. Further it is from U.S. Pat. No. 5,378,916 (Mantell) discloses a photosensitive device in the form of a single-crystal structure, wherein different portions of the structure may have different compositions. Particularly, the structure forms a two-dimensional array. 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 wave
Gudesen Hans Gude
Leistad Geirr I.
Nordal Per-Erik
Birch & Stewart Kolasch & Birch, LLP
Flynn Nathan J.
Mondt Johannes
Thin Film Electronics ASA
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