News Column

Researchers Submit Patent Application, "Thin Film Transistor", for Approval

August 27, 2014



By a News Reporter-Staff News Editor at Electronics Newsweekly -- From Washington, D.C., VerticalNews journalists report that a patent application by the inventors Chaji, Gholamreza (Waterloo, CA); Moradi, Maryam (Melrose, MA), filed on April 4, 2014, was made available online on August 14, 2014.

The patent's assignee is Ignis Innovation Inc.

News editors obtained the following quote from the background information supplied by the inventors: "Displays can be created from an array of organic light emitting devices ('OLEDs') each controlled by individual circuits (i.e., pixel circuits) having transistors for selectively controlling the circuits to be programmed with display information and to emit light according to the display information. Thin film transistors ('TFTs') fabricated on a substrate can be incorporated into such displays.

"Mobility characterizes the responsiveness of a charge carrier in the presence of an electric field. Mobility is generally expressed in units of cm.sup.2/V s. For transistors, the mobility of the channel region provides a measure of the performance of the transistor 'on' current, e.g., the current that can be supplied by the transistor. In thin film transistors, a layer of semiconductor material is generally utilized to form the channel region.

"Development of OLED display devices is challenged by the demand for a suitable drive transistor in the pixel circuits. Amorphous silicon (a-Si), the transistor channel material that sources the voltage to switch AM-LCD pixels, has a low mobility (.about.0.1 cm.sup.2 V.sup.-1 s.sup.-1). Organic semiconductor channel materials are attractive for use as pixel circuit drive transistors for their homogeneity, low cost, and the variety of means by which they can be deposited, but their best mobilities are similar to that of a-Si. In a typical TFT architecture, low-mobility channel layers would require a large source-drain voltage to drive the necessary current. This consumes power in the transistor (as opposed to light production in the OLED), compromising the power savings.

"P-type a-Si TFTs can have even lower mobility values, and can be as low as 0.01 cm.sup.2 V.sup.-1 s.sup.-1."

As a supplement to the background information on this patent application, VerticalNews correspondents also obtained the inventors' summary information for this patent application: "According to one embodiment, a thin film transistor comprises a semiconductor layer; first and second dielectric layers disposed on opposite sides of the semiconductor layer; a first metal layer forming first and second terminals on the opposite side of the first dielectric layer from the semiconductor layer, one of said first and second terminals extending through said first dielectric layer into contact with the semiconductor layer, the first and second terminals and the first dielectric layer forming a capacitor; and a second metal layer forming a third terminal on the opposite side of the second dielectric layer from the semiconductor layer. In one implementation, the first and second terminals are source and drain terminals, and the third terminal is a gate terminal. The first metal layer may be divided to form the first and second terminals. The third terminal may be shared with one of the first and second terminals.

"In another embodiment, a thin film transistor comprises a semiconductor layer; first and second dielectric layers disposed on opposite sides of the semiconductor layer, at least the second dielectric layer having openings therein; a first metal layer forming a first terminal on the opposite side of the first dielectric layer from the semiconductor layer; and a second metal layer forming a second terminal on the opposite side of the second dielectric layer from the semiconductor layer, with the second metal layer extending through the openings in the second dielectric layer to contact the semiconductor layer.

"The foregoing and additional aspects and embodiments of the present invention will be apparent to those of ordinary skill in the art in view of the detailed description of various embodiments and/or aspects, which is made with reference to the drawings, a brief description of which is provided next.

BRIEF DESCRIPTION OF THE DRAWINGS

"The foregoing and other advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings.

"FIG. 1 illustrates a block diagram of a bottom gate thin film transistor having a channel region including a nanoconductor layer.

"FIG. 2 illustrates a block diagram of a top gate thin film transistor having a channel region including a nanoconductor layer.

"FIG. 3A is a schematic illustration of a cross-section view of a thin film transistor 110 having a channel region including a nanoconductor layer.

"FIG. 3B is a schematic illustration of a thin film transistor similar to the one illustrated in FIG. 3A, but with a shorter nanoconductor layer.

"FIG. 4A is a schematic illustration of a top view of a nanoconductor layer with a characteristic length exceeding the separation between the drain and source terminals of the TFT.

"FIG. 4B is a schematic illustration of a top view of the nanoconductor layer similar to FIG. 4A, but where the individual nanoconductors are imperfectly aligned with a direction oriented from the drain terminal to the source terminal.

"FIG. 4C is a schematic illustration of a top view of the nanoconductor layer similar to FIG. 4A, but where the characteristic length of the nanoconductor layer is less than the separation of the drain and source terminals of the TFT.

"FIG. 5 is a flowchart illustrating an example process for manufacturing a thin film transistor having a channel region including a nanoconductor layer.

"FIG. 6 is a diagrammatic cross section of a thin film transistor having a channel region including a nanoconductor layer.

"FIG. 7 is a pair of sectional views of two typical Metal-Insulator-Metal (MIM) capacitors.

"FIG. 8 is a sectional view of a structure having a high capacitance value.

"FIG. 9 is a plan view of the structure shown in FIG. 8.

"FIG. 10 is a sectional view of a modified structure having a high capacitance value.

"While the invention is susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and will be described in detail herein. It should be understood, however, that the invention is not intended to be limited to the particular forms disclosed. Rather, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims."

For additional information on this patent application, see: Chaji, Gholamreza; Moradi, Maryam. Thin Film Transistor. Filed April 4, 2014 and posted August 14, 2014. Patent URL: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.html&r=6216&p=125&f=G&l=50&d=PG01&S1=20140807.PD.&OS=PD/20140807&RS=PD/20140807

Keywords for this news article include: Electronics, Semiconductor, Ignis Innovation Inc..

Our reports deliver fact-based news of research and discoveries from around the world. Copyright 2014, NewsRx LLC


For more stories covering the world of technology, please see HispanicBusiness' Tech Channel



Source: Electronics Newsweekly


Story Tools






HispanicBusiness.com Facebook Linkedin Twitter RSS Feed Email Alerts & Newsletters