CIRCUIT BOARD, DISPLAY DEVICE, AND METHOD FOR PRODUCING CIRCUIT BOARD

• US 20130146866A1
• Filed: 03/02/2011
• Published: 06/13/2013
• Est. Priority Date: 04/30/2010
• Status: Active Grant

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Kitagawa, Hideki, Tanaka, Shinya, Imai, Hajime, Murai, Atsuhito, Imade, Mitsunori, Kikuchi, Tetsuo, Morimoto, Kazunori, Shimada, Junya, Nishimura, Jun
• Granted Patent: US 9,111,810 B2
• Time in Patent Office: Days
• US Class Current: 257/43
• CPC Class Codes: H01L 27/1225 with semiconductor materials not belonging to the group IV of the periodic table, e.g. InGaZnO
• CPC Class Codes: H01L 27/1251 comprising TFTs having a different architecture, e.g. top- and bottom gate TFTs
• CPC Class Codes: H01L 27/1259 Multistep manufacturing methods
• CPC Class Codes: H01L 27/1446 in a repetitive configuration
• CPC Class Codes: H01L 27/14632 Wafer-level processed structures
• CPC Class Codes: H01L 27/14678 Contact-type imagers

Abstract

A circuit board (1) includes a plurality of transistor elements on an insulating substrate (2). At least one of the plurality of transistor elements is an oxide TFT (10) including, as a channel layer (11), an oxide semiconductor. At least one of the plurality of transistor elements is an a-SiTFT (20) (i) being different from the oxide TFT (10) in functions as circuit components and (ii) including, as a channel layer (21), an amorphous silicon semiconductor. The oxide TFT (10) is a top gate transistor, and the a-SiTFT (20) is a bottom gate transistor. This provides: a configuration that can (a) enhance the performance of the circuit board equipped with the TFTs differing in their respective functions as circuit components and (b) reduce the area necessary for mounting the TFTs; and a method for producing the circuit board.

Claims

1. A circuit board comprising a plurality of transistor elements on an insulating substrate,

at least one of the plurality of transistor elements being a first thin-film transistor element including, as a channel layer, a semiconductor which has a relatively large mobility and a relatively low sensitivity to light,

at least one of the others of the plurality of transistor elements being a second thin-film transistor element (i) being different from the first thin-film transistor element in terms of functions as circuit components, (ii) including, as a channel layer, a semiconductor which has a relatively small mobility and a relatively high sensitivity to light, and

the first thin-film transistor element being a top gate transistor, and the second thin-film transistor element being a bottom gate transistor.

2. The circuit board as set forth in claim 1, wherein:

the first thin-film transistor element and the second thin-film transistor element are incorporated to configure an optical sensor circuit;

the first thin-film transistor element plays a role of a sensor output of the optical sensor circuit; and

the second thin-film transistor element plays a role of an optical sensor element of the optical sensor circuit.

3. The circuit board as set forth in claim 1, wherein an identical conductive layer forms a gate electrode of the first thin-film transistor element and a drain electrode of the second thin-film transistor element.

4. The circuit board as set forth in claim 3, wherein the gate electrode of the first thin-film transistor element and the drain electrode of the second thin-film transistor element are connected to each other through wiring.

5. The circuit board as set forth in claim 1, wherein:

the channel layer included in the first thin-film transistor element is made from an oxide semiconductor; and

the channel layer included in the second thin-film transistor element is made from an amorphous silicon semiconductor.

6. The circuit board as set forth in claim 5, wherein:

a gate insulating film whose main component is SiO2 is sandwiched between the channel layer of and the gate electrode of the first thin-film transistor element;

a gate insulating film whose main component is SiN_x and a gate insulating film whose main component is SiO2 are (i) stacked together in this order from a channel-layer side and (ii) sandwiched between the channel layer of and a gate electrode of the second thin-film transistor element; and

the gate insulating films, whose main component is SiO2, of the first thin-film transistor element and of the second thin-film transistor element are provided as a layer.

7. A circuit board as set forth in claim 2, further comprising a protection circuit for providing circuitry protection for protecting a first transistor element which is one of the plurality of transistor elements, the protection circuit including a second transistor element which is one of the plurality of transistor elements,

the first transistor element is the first thin-film transistor element, and

the second transistor element is the second thin-film transistor element.

8. A display panel comprising a circuit board as set forth in claim 1.

9. A display device comprising a circuit board as set forth in claim 1.

10. A method for producing a circuit board in which a first thin-film transistor element and a second thin-film transistor element, which differ from each other in their respective functions as circuit components, are provided on an insulating substrate, the respective functions being different due to use of different types of semiconductors from which respective channel layers of the first thin-film transistor element and the second thin-film transistor element are formed,

said method comprising the steps of:

forming an insulating film on both the channel layer of the first thin-film transistor element and a gate electrode of the second thin-film transistor element, which are patterned on the insulating substrate; and

patterning an identical conductive layer on the insulating film into (i) a gate electrode of the first thin-film transistor element, (ii) a source electrode of the second thin-film transistor element, and (iii) a drain electrode of the second thin-film transistor element.