OXIDE SEMICONDUCTOR DEVICE AND METHOD OF MANUFACTURING THE SAME AND ACTIVE MATRIX SUBSTRATE

• US 20100140614A1
• Filed: 12/08/2009
• Published: 06/10/2010
• Est. Priority Date: 12/09/2008
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Uchiyama, Hiroyuki, Wakana, Hironori, Kawamura, Tetsufumi
• Granted Patent: US 8,368,067 B2
• Time in Patent Office: Days
• US Class Current: 257/43
• CPC Class Codes: H01L 21/02554 Oxides
• CPC Class Codes: H01L 21/02565 Oxide semiconducting materials not being Group 12/16 materials, e.g. ternary compounds
• CPC Class Codes: H01L 21/02617 Deposition types
• 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 29/40111 the electrodes comprising a layer which is used for its ferroelectric properties
• 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: H10B 12/05 Making the transistor
• CPC Class Codes: H10B 20/00 Read-only memory [ROM] devices
• CPC Class Codes: H10B 20/20 Programmable ROM [PROM] devices comprising field-effect components H10B20/10 takes precedence
• CPC Class Codes: H10K 50/81 Anodes
• CPC Class Codes: H10K 59/1213 the pixel elements being TFTs
• CPC Class Codes: H10K 59/80517 Multilayers, e.g. transparent multilayers

Abstract

A phenomenon of change of a contact resistance between an oxide semiconductor and a metal depending on an oxygen content ratio in introduced gas upon depositing an oxide semiconductor film made of indium gallium zinc oxide, zinc tin oxide, or others in an oxide semiconductor thin-film transistor. A contact layer is formed with an oxygen content ratio of 10% or higher in a region from a surface, where the metal and the oxide semiconductor are contacted, down to at least 3 nm deep in depth direction, and a region to be a main channel layer is further formed with an oxygen content ratio of 10% or lower, so that a multilayered structure is formed, and both of ohmic characteristics to the electrode metal and reliability such as the suppression of threshold potential shift are achieved.

Claims

1. An oxide semiconductor device comprising an oxide semiconductor layer and an electrode contacting with a first surface of the oxide semiconductor layer, wherein

the oxide semiconductor layer includes:

a first layer provided on the first surface side and having a substantially uniform oxygen concentration at a first concentration; and

a second layer provided on a second surface side opposite to the first surface and having a substantially uniform oxygen oxygen-content concentration at a second concentration, and

the first concentration is higher than the second concentration.

2. The oxide semiconductor device according to claim 1, wherein

the first layer has a thickness of 3 nm or larger.

3. The oxide semiconductor device according to claim 1, wherein

the first concentration is 10²¹ atomic concentration or higher, and

the second concentration is below 10²¹ atomic concentration.

4. The oxide semiconductor device according to claim 1, wherein

there is a 10 times or more difference between the first concentration and the second concentration.

5. The oxide semiconductor device according to claim 1, wherein

the oxide semiconductor layer is configured with any one of zinc oxide (ZnO), indium gallium zinc oxide (IGZO), zinc tin oxide (ZTO), and zinc indium oxide (ZIO).

6. The oxide semiconductor device according to claim 1, wherein

a third layer in which a difference of oxygen concentrations of the first layer and the second layer is gradedly decreased is provided between the first layer and the second layer.

7. The oxide semiconductor device according to claim 1, wherein

a fourth layer having an substantially-uniform oxygen concentration within a range of the oxygen concentration of the first layer to that of the second layer is provided between the first layer and the second layer.

8. The oxide semiconductor device according to claim 1, wherein

the electrode is configured by a plurality of layers including a transparent conductive film on a first layer of the electrode contacting with the oxide semiconductor layer, a transparent conductive film having a lower conductivity than that of a second layer of the electrode not contacting with the oxide semiconductor layer.

9. The oxide semiconductor device according to claim 1, wherein

a transistor of a bottom-gate top-contact type or a top-gate bottom-contact type is configured having:

a gate electrode provided on the second surface side with interposing a gate insulating film; and

a source electrode and a drain electrode contacting with the first surface side.

10. An active matrix substrate including the oxide semiconductor device according to claim 9, wherein

a plurality of gate lines and a plurality of data lines are provided on a substrate, and

the transistor is arranged in each pixel arranged in matrix corresponding to intersections of the plurality of gate lines and the plurality of data lines.

11. The oxide semiconductor device according to claim 1, wherein

a transistor of a top-gate top-contact type or a bottom-gate bottom-contact type is configured having:

a gate electrode provided on the first surface side with interposing a gate insulating film; and

a source electrode and a drain electrode contacting with the first surface side.

12. An active matrix substrate including the oxide semiconductor device according to claim 11, wherein

a plurality of gate lines and a plurality of data lines are provided on a substrate, and

the transistor is arranged in each pixel arranged in matrix corresponding to intersections of the plurality of gate lines and the plurality of data lines.

13. A method of manufacturing an oxide semiconductor device including an oxide semiconductor layer and an electrode contacting with the oxide semiconductor layer, wherein

an inlet flow of oxygen gas introduced into a reactive chamber upon a deposition process of the oxide semiconductor layer contacting with the electrode is larger than that of oxygen gas introduced into a reactive chamber upon a deposition process of the oxide semiconductor layer not contacting with the electrode.

14. The method of manufacturing the oxide semiconductor device according to claim 13, wherein

a ratio of oxygen gas with respect to all introduced gas introduced into the reactive chamber upon the deposition process of the oxide semiconductor layer contacting with the electrode is 10% or higher, and

a ratio of oxygen gas with respect to all introduced gas introduced into the reactive chamber upon the deposition process of the oxide semiconductor layer not contacting with the electrode is 5% or lower.

15. The method of manufacturing the oxide semiconductor device according to claim 13, wherein

the oxide semiconductor layer contacting with the electrode is formed to have a thickness of 3 nm or larger with the inlet flow of the oxygen gas being large than that of forming the oxide semiconductor layer not contacting with the electrode.

16. The method of manufacturing the oxide semiconductor device according to claim 13, wherein,

when the inlet flow of the oxygen gas for forming the oxide semiconductor layer contacting with the electrode is changed to the inlet flow of the oxygen gas for forming the oxide semiconductor later not contacting with the electrode, the deposition of the oxide semiconductor layer is stopped once.

17. The method of manufacturing the oxide semiconductor device according to claim 13, wherein,

upon the deposition of the oxide semiconductor layer,

the inlet flow of the oxygen gas is increased from a surface contacting with the electrode toward an opposite surface, or

the inlet flow of the oxygen gas is decreased from the opposite surface of the surface contacting with the electrode toward the surface contacting with the electrode.