Thin film transistor having oxide semiconductor layer and manufacturing method thereof

• US 7,566,904 B2
• Filed: 06/07/2006
• Issued: 07/28/2009
• Est. Priority Date: 06/10/2005
• Status: Active Grant

• Current Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Original Assignee: Casio Computer Company Limited
• Inventors: Ishii, Hiromitsu
• Primary Examiner(s): Tran; Minh-Loan T
• Assistant Examiner(s): YEUNG LOPEZ, FEIFEI
• Application Number:
  US11/448,633
• Publication Number:
  US 20060284172A1
• Time in Patent Office: 1,147 Days
• Field of Search: None
• US Class Current: 257/59
• CPC Class Codes: G02F 1/1368 in which the switching element is a three-electrode device G02F1/136277 takes precedence
• 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 29/66969 of devices having semiconductor bodies not comprising group 14 or group 13/15 materials comprising selenium or tellurium in uncombined form other than as impurities in semiconductor bodies of other materials, comprising cuprous oxide or cuprous iodide H01L21/02365
• CPC Class Codes: H01L 29/7869 having a semiconductor body comprising an oxide semiconductor material, e.g. zinc oxide, copper aluminium oxide, cadmium stannate

Abstract

A thin film transistor has a semiconductor thin film including zinc oxide, a protection film formed on entirely the upper surface of the semiconductor thin film, a gate insulating film formed on the protection film, a gate electrode formed on the gate insulating film above the semiconductor thin film, and a source electrode and drain electrode formed under the semiconductor thin film so as to be electrically connected to the semiconductor thin film.

Claims

1. A thin film transistor, comprising:

a semiconductor thin film including zinc oxide;

a protection film formed on an entire upper surface of the semiconductor thin film and having a plan-view shape that is substantially the same as a plan-view shape of the semiconductor thin film;

a gate insulating film formed on the protection film;

a gate electrode formed on the gate insulating film above the semiconductor thin film;

a source electrode and a drain electrode formed under the semiconductor thin film so as to be electrically connected to the semiconductor thin film, the source electrode and the drain electrode having portions protruding at a periphery of the semiconductor thin film and the protection film; and

ohmic contact layers made of n type zinc oxide which are respectively provided on upper surfaces of the source electrode and the drain electrode under the semiconductor thin film,

wherein surrounding end surfaces of the ohmic contact layers have substantially a same shape as surrounding end surfaces of the semiconductor thin film and the protection film except end surfaces of the ohmic contact layers, which face each other, are formed in a same shape as end surfaces of the source electrode and the drain electrode that face each other, and

wherein the gate insulating film covers peripheral side surfaces of the semiconductor thin film, the protection film and the ohmic contact layers, and outer surfaces of the protruding portions of the source electrode and the drain electrode.

11. The thin film transistor according to claim 1, further comprising an overcoat film which covers the gate electrode.

12. The thin film transistor according to claim 11, wherein a pixel electrode is formed on an upper surface of the overcoat film so as to be connected to the source electrode.

13. The thin film transistor according to claim 12, wherein an auxiliary capacitor electrode is formed between the gate insulating film and the overcoat film.

14. The thin film transistor according to claim 13, wherein a data line connected to the drain electrode is formed on a same layer as the drain electrode,

wherein the auxiliary capacitor electrode comprises a portion that overlaps the data line via the gate insulating film, and

wherein a width of the portion of the auxiliary capacitor electrode that overlaps the data line is larger than a width of the data line.

15. The thin film transistor according to claim 14, wherein the auxiliary capacitor electrode overlaps all peripheral edges of the pixel electrode.

16. The thin film transistor according to claim 15, further comprising an insulating film which covers the gate electrode, wherein the auxiliary capacitor electrode is formed on an upper surface of the insulating film.

17. The thin film transistor according to claim 16, wherein a scanning line connected to the gate electrode is formed on a same layer as the gate electrode,

wherein the auxiliary capacitor electrode comprises a portion that overlaps the scanning line via the insulating film, and

wherein a width of the portion of the auxiliary capacitor electrode overlapping the scanning line is larger than a width of the scanning line.

18. The thin film transistor according to claim 16, wherein the auxiliary capacitor electrode is formed on an upper surface of the gate insulating film.

2. A thin film transistor, comprising:

a semiconductor thin film including zinc oxide;

a protection film formed on an entire upper surface of the semiconductor thin film and having a plan-view shape that is substantially the same as a plan-view shape of the semiconductor thin film;

a gate insulating film formed on the protection film;

a gate electrode formed on the gate insulating film above the semiconductor thin film;

a source electrode and a drain electrode formed under the semiconductor thin film so as to be electrically connected to the semiconductor thin film; and

ohmic contact layers made of n type zinc oxide which are respectively provided on upper surfaces of the source electrode and the drain electrode under the semiconductor thin film,

wherein end surfaces of the ohmic contact layers, which face each other, protrude from end surfaces of the source electrode and the drain electrode that face each other.

3. The thin film transistor according to claim 2, further comprising an overcoat film which covers the gate electrode.

4. The thin film transistor according to claim 3, wherein a pixel electrode is formed on an upper surface of the overcoat film so as to be connected to the source electrode.

5. The thin film transistor according to claim 4, wherein an auxiliary capacitor electrode is formed between the gate insulating film and the overcoat film.

6. The thin film transistor according to claim 5, wherein a data line connected to the drain electrode is formed on a same layer as the drain electrode,

wherein the auxiliary capacitor electrode comprises a portion that overlaps the data line via the gate insulating film, and

wherein a width of the portion of the auxiliary capacitor electrode that overlaps the data line is larger than a width of the data line.

7. The thin film transistor according to claim 6, wherein the auxiliary capacitor electrode overlaps all peripheral edges of the pixel electrode.

8. The thin film transistor according to claim 7, further comprising an insulating film which covers the gate electrode, wherein the auxiliary capacitor electrode is formed on an upper surface of the insulating film.

9. The thin film transistor according to claim 8, wherein a scanning line connected to the gate electrode is formed on a same layer as the gate electrode,

wherein the auxiliary capacitor electrode comprises a portion that overlaps the scanning line via the insulating film, and

wherein a width of the portion of the auxiliary capacitor electrode overlapping the scanning line is larger than a width of the scanning line.

10. The thin film transistor according to claim 8, wherein the auxiliary capacitor electrode is formed on an upper surface of the gate insulating film.