SEMICONDUCTOR ELEMENT, METHOD FOR MANUFACTURING SAME, AND ELECTRONIC DEVICE INCLUDING SAME

• US 20100044702A1
• Filed: 04/01/2008
• Published: 02/25/2010
• Est. Priority Date: 04/06/2007
• Status: Active Grant

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.), Tohoku University National Universities Corporation
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.), Tohoku University National Universities Corporation
• Inventors: Urayama, Masao, Kawasaki, Masashi, Ohno, Hideo
• Granted Patent: US 8,173,487 B2
• Time in Patent Office: Days
• US Class Current: 257/43
• 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 29/78696 characterised by the structure of the channel, e.g. multichannel, transverse or longitudinal shape, length or width, doping structure, or the overlap or alignment between the channel and the gate, the source or the drain, or the contacting structure of the channel H01L29/78612 takes precedence; transistors having a drain offset region or a lightly doped drain [LDD] H01L29/78621
• CPC Class Codes: Y10S 438/922 Diffusion along grain boundaries

Abstract

A thin-film transistor (1) of the present invention includes an insulating substrate (2), a gate electrode (3) which has a predetermined shape and is formed on the insulating substrate (2), a gate insulating film (4) formed on the gate electrode (3), and a semiconductor layer (5) which is polycrystalline ZnO and is formed on the gate insulating film (4). The semiconductor layer (5) is immersed in a solution in which impurities are dissolved so that the impurities are selectively added to a grain boundary part of the polycrystalline ZnO film. Subsequently, a source electrode (6) and a drain electrode (7) are formed so as to have a predetermined shape. Next, a protection layer (8) is formed on the source electrode (6) and the drain electrode (7). Thus, a thin-film transistor which has a good subthreshold characteristic and has a zinc oxide film as a base of an active layer can be realized.

Claims

1. A semiconductor element comprising

an active layer made of a polycrystalline ZnO film to which impurities are added,

the impurities being added more in concentration to a grain boundary part of the active layer than to a crystal part of the active layer.

2. The semiconductor element according to claim 1, wherein

the impurities are added to the polycrystalline ZnO film so as to have a concentration gradient in a film thickness direction.

3. The semiconductor element according to claim 1, wherein

the impurities are sulfur.

4. The semiconductor element according to claim 1, wherein

the polycrystalline ZnO film has a thickness of less than 50 nm.

5. The semiconductor element according to claim 1, wherein

the semiconductor element is a thin-film transistor.

14. An electronic device comprising, as a switching element, a semiconductor element recited in claim 1.

15. The electronic device according to claim 14, wherein

the switching element is connected to a pixel electrode so that an image signal is written into or read out from a pixel electrode.

6. A method for manufacturing a semiconductor element, comprising the steps of:

forming a polycrystalline ZnO film, and

forming an active layer by adding impurities to the polycrystalline ZnO film so that the impurities are added more in concentration to a grain boundary part than to a crystal part.

7. The method according to claim 6, wherein

the active layer is formed by immersing the polycrystalline ZnO film in a solution containing the impurities which are being ionized so that the impurities are added more in concentration to the grain boundary part than to the crystal part.

8. The method according to claim 6, wherein

the active layer is formed by a chemical bath deposition method so that the impurities are added more in concentration to the grain boundary part than to the crystal part.

9. The method according to claim 7, wherein

the impurities are sulfur.

10. The method according to claim 9, wherein

the solution has pH of 9 to 12.

11. The method according to claim 9, wherein

the solution contains ammonia, ZnSO₄, and thiourea.

12. The method according to claim 6, wherein

the polycrystalline ZnO film is formed by an electroless plating.

13. The method according to claim 6, wherein

formation of the polycrystalline ZnO film and addition of the impurities to the polycrystalline ZnO film are alternated more than once by use of the electroless plating.

16. A semiconductor element comprising

an active layer made of a semiconductor film which contains ZnO as a main ingredient, is in a polycrystalline state and/or in an amorphous state, and to which impurities are added,

the impurities being added more in concentration to a grain boundary part of the active layer than to a crystal part of the active layer.