Thin film transistors

Details Thin film transistors Thin film transistors

1999-11-17

2001-09-04

Smith, Matthew (Department: 2825)

Semiconductor device manufacturing: process

Having organic semiconductive component

C438S099000, C438S197000, C438S199000, C257S350000

Reexamination Certificate

active

06284562

ABSTRACT:

FIELD OF THE INVENTION
The invention relates to thin film transistors (TFTs), and more particularly to TFT devices with new ambipolar semiconductor materials.
BACKGROUND OF THE INVENTION
Over the last decade, IC technologies have been proposed that use organic semiconductor thin film transistors (TFTs). The chief attractions of such circuits stem from the anticipated ease of processing and compatibility with flexible substrates. These advantages are expected to translate into a low-cost IC technology suitable for applications such as smart cards, electronic tags, displays, et al.
TFT devices are described in F. Garnier et al., Science, Vol. 265, pp. 1684-1686; H. Koezuka et al., Applied Physics Letters, Vol. 62 (15), pp. 1794-1796; H. Fuchigami et al., Applied Physics Letters, Vol. 63 (10), pp. 1372-1374; G. Horowitz et al., J. Applied Physics, Vol. 70(1), pp. 469-475; and G. Horowitz et al., Synthetic Metals, Vol. 42-43, pp. 1127-1130. The devices described in these references are based on polymers or oligomers as the active materials, in contrast with the amorphous silicon TFT structures that were developed earlier. The devices are typically field effect transistors (FETs). Polymer active devices have significant advantages over semiconductor TFTs in terms of simplicity of processing and resultant low cost. They are also compatible with polymer substrates used widely for interconnect substrates. Polymer TFTs are potentially flexible, and polymer TFT ICs can be mounted directly on flexible printed circuit boards. They also have compatible coefficients of thermal expansion so that solder bonds, conductive expoxy bonds, and other interconnections experience less strain than with semiconductor IC/polymer interconnect substrate combinations. While MIS FET devices are most likely to find widespread commercial applications, TFT devices that utilize both p-type and n-type organic active materials are also known. See e.g., U.S. Pat. No. 5,315,129. S. Miyauchi et al., Synthetic Metals, 41-43 (1991), pp. 1155-1158, disclose a junction FET that comprises a layer of p-type polythiophene on n-type silicon.
Recent advances in polymer based TFT devices are described in U.S. Pat. No. 5,596,208, issued May 10, 1996, U.S. Pat. No. 5,625,199, issued Apr. 29, 1997, and U.S. Pat. No. 5,574,291, issued Nov. 12, 1996. With the development of both n-type and p-type active polymer materials, as described in these patents, complementary ICs can be readily implemented, as detailed particularly in U.S. Pat. No. 5,625,199. However, following these teachings a true integrated CMOS circuit requires the preparation or deposition of two different materials to form the complementary device.
SUMMARY OF THE INVENTION
We have developed a TFT CMOS device which uses a single, homogeneous, organic semiconductor material, which in the preferred case is tetracene or pentacene. We have discovered that tetracene and pentacene, when properly prepared with the correct crystal form and purity, exhibits ambipolar behavior. Thus a single homogeneous layer of this material can be formed over two MOS gated transistors and can be operated in a complementary mode.


REFERENCES:
patent: 4608097 (1986-08-01), Weinberger et al.
patent: 5155566 (1992-10-01), Nakayama et al.
patent: 5315129 (1994-05-01), Forrest et al.
patent: 5596208 (1997-01-01), Dodabalapur et al.
patent: 5625199 (1997-04-01), Baumbach et al.
patent: 5714394 (1998-02-01), Kadosh et al.
patent: 5849403 (1998-12-01), Aoki et al.
patent: 5936259 (1999-08-01), Katz et al.
patent: 5946551 (1999-08-01), Dinitrakopoulos et al.
patent: 5981970 (1999-11-01), Dimitrakopoulos et al.
patent: WO99/66540 (1998-06-01), None
B. Crone et al. “Novel Fabrication Methods of Organic Complementary Circuits” IEEE 0-7803-5410-9/99 (IEDM 99-115) p. 5.3.1-5.3.4.*
A. Dodabalapur et al. “Organic Heterstructure FET's” 1995 Science vol. 269 p. 1560-62.

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