Transistor having oxide semiconductor layer and display utilizing the same

• US 8,389,989 B2
• Filed: 08/26/2010
• Issued: 03/05/2013
• Est. Priority Date: 09/04/2009
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Yamazaki, Shunpei, Sasaki, Toshinari, Sakata, Junichiro, Tsubuku, Masashi
• Primary Examiner(s): Pizarro, Marcos D.
• Assistant Examiner(s): MONTALVO, EVA Y
• Application Number:
  US12/869,278
• Publication Number:
  US 20110057186A1
• Time in Patent Office: 922 Days
• Field of Search: 257/72, 257/43, 257/258, 257/83, 257/84, 257/88, 257/E29.596
• US Class Current: 257/43
• CPC Class Codes: H01L 27/1214 comprising a plurality of TFTs formed on a non-semiconducting substrate, e.g. driving circuits for AMLCDs
• 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 27/1248 with a particular composition or shape of the interlayer dielectric specially adapted to the circuit arrangement
• CPC Class Codes: H01L 27/1255 integrated with passive devices, e.g. auxiliary capacitors
• CPC Class Codes: H01L 29/24 including, apart from doping materials or other impurities, only semiconductor materials not provided for in groups H01L29/16, H01L29/18, H01L29/20, H01L29/22 including organic materials H10K99/00
• CPC Class Codes: H01L 29/42356 Disposition, e.g. buried gate electrode H01L29/42324 and H01L29/4234 take precedence
• CPC Class Codes: H01L 29/45 Ohmic electrodes
• CPC Class Codes: H01L 29/458 for thin film silicon, e.g. source or drain electrode
• CPC Class Codes: H01L 29/4908 for thin film semiconductor, e.g. gate of TFT
• CPC Class Codes: H01L 29/78606 with supplementary region or layer in the thin film or in the insulated bulk substrate supporting it for controlling or increasing the safety of the device H01L29/78642, H01L29/78645 take precedence
• CPC Class Codes: H01L 29/78618 characterised by the drain or the source properties, e.g. the doping structure, the composition, the sectional shape or the contact structure silicide contacts, electrodes in general H01L29/458
• CPC Class Codes: H01L 29/7869 having a semiconductor body comprising an oxide semiconductor material, e.g. zinc oxide, copper aluminium oxide, cadmium stannate
• CPC Class Codes: H01L 29/78693 the semiconducting oxide being amorphous
• CPC Class Codes: H10K 59/1213 the pixel elements being TFTs
• CPC Class Codes: H10K 59/1216 the pixel elements being capacitors
• CPC Class Codes: H10K 59/123 Connection of the pixel electrodes to the thin film transistors [TFT]

Abstract

It is an object to manufacture a highly reliable display device using a thin film transistor having favorable electric characteristics and high reliability as a switching element. In a bottom gate thin film transistor including an amorphous oxide semiconductor, an oxide conductive layer having a crystal region is formed between an oxide semiconductor layer which has been dehydrated or dehydrogenated by heat treatment and each of a source electrode layer and a drain electrode layer which are formed using a metal material. Accordingly, contact resistance between the oxide semiconductor layer and each of the source electrode layer and the drain electrode layer can be reduced; thus, a thin film transistor having favorable electric characteristics and a highly reliable display device using the thin film transistor can be provided.

Claims

1. A transistor comprising:

a gate electrode layer;

a gate insulating layer over the gate electrode layer;

an oxide semiconductor layer over the gate insulating layer;

a source electrode layer and a drain electrode layer over the oxide semiconductor layer; and

an oxide insulating layer in contact with the oxide semiconductor layer,

wherein a peak of a desorption constituent, which is derived from moisture, is not shown in a spectrum of the oxide semiconductor layer, which is shown with thermal desorption spectroscopy in a temperature range of greater than or equal to 200°

C. and less than or equal to 350°

C.

2. The transistor according to claim 1, wherein the oxide semiconductor layer is amorphous.

3. The transistor according to claim 1, wherein the source electrode layer and the drain electrode layer comprise a film including an element selected from Al, Cr, Cu, Ta, Ti, Mo, and W as its main component or an alloy film thereof.

4. The transistor according to claim 1, wherein the oxide insulating layer comprises a material selected from the group consisting of silicon oxide, silicon nitride oxide, aluminum oxide, and aluminum oxynitride.

5. The transistor according to claim 1 further comprising a pair of oxide conductive layers partly overlapping with the oxide semiconductor layer over the gate insulating layer,

wherein the pair of oxide conductive layers includes a crystal region.

10. The transistor according to claim 5,

wherein the pair of oxide conductive layers comprises a material selected from the group consisting of indium oxide, an indium oxide-tin oxide alloy, an indium oxide-zinc oxide alloy, zinc oxide, zinc aluminum oxide, zinc aluminum oxynitride, and zinc gallium oxide.

6. A display device comprising:

a pixel portion and a driver circuit each including a transistor over a substrate, the transistor comprising;

a gate electrode layer over the substrate;

a gate insulating layer over the gate electrode layer;

an oxide semiconductor layer over the gate insulating layer;

a source electrode layer and a drain electrode layer the oxide semiconductor layer; and

an oxide insulating layer in contact with the oxide semiconductor layer,

wherein a peak of a desorption constituent, which is derived from moisture, is not shown in a spectrum of the oxide semiconductor layer, which is shown with thermal desorption spectroscopy in a temperature range of greater than or equal to 200°

C. and less than or equal to 350°

C.

7. The display device according to claim 6, wherein the oxide semiconductor layer is amorphous.

8. The display device according to claim 6, wherein the source electrode layer and the drain electrode layer comprise a film including an element selected from Al, Cr, Cu, Ta, Ti, Mo, and W as its main component or an alloy film thereof.

9. The display device according to claim 6, wherein the oxide insulating layer comprises a material selected from the group consisting of silicon oxide, silicon nitride oxide, aluminum oxide, and aluminum oxynitride.

11. The display device according to claim 6 further comprising a pair of oxide conductive layers partly overlapping with the oxide semiconductor layer over the gate insulating layer,

wherein the pair of oxide conductive layers includes a crystal region.

12. The display device according to claim 11,

wherein the pair of oxide conductive layers comprises a material selected from the group consisting of indium oxide, an indium oxide-tin oxide alloy, an indium oxide-zinc oxide alloy, zinc oxide, zinc aluminum oxide, zinc aluminum oxynitride, and zinc gallium oxide.