SEMICONDUCTOR DEVICE AND METHOD FOR MANUFACTURING THE SAME

• US 20110042667A1
• Filed: 07/17/2010
• Published: 02/24/2011
• Est. Priority Date: 08/21/2009
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Sato, Takeshi, Uchiyama, Hiroyuki, Hatano, Mutsuko, Wakana, Hironori, KAWAMURA, Tetsufumi
• Granted Patent: US 8,314,032 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

Abstract

A method for manufacturing a thin film transistor (TFT) through a process including back exposure, in which oxide semiconductor is used for a channel layer; using an electrode over a substrate as a mask, negative resist is exposed to light from the back of the substrate; the negative resist except its exposed part is removed; and an electrode is shaped by etching a conductive film using the exposed part as an etching mask.

Claims

1. A method for manufacturing a semiconductor device, comprising the steps of:

forming, over a substrate, a source electrode and a drain electrode from a metal film and a channel layer from oxide semiconductor;

forming a gate insulating film over the source electrode, the drain electrode, and the channel layer;

forming a conductive film over the gate insulating film;

coating the conductive film with negative resist;

exposing the negative resist to light from a back of the substrate using the source electrode and the drain electrode as a mask;

removing the negative resist except exposed part of the negative resist; and

forming a gate electrode by etching the conductive film using the exposed part as an etching mask.

2. The method for manufacturing a semiconductor device according to claim 1, further comprising the steps of:

forming a first interconnect from the metal film on the substrate together with the source electrode and the drain electrode;

exposing the negative resist to light from the back of the substrate using, as a mask, the first interconnect as well as the source electrode and the drain electrode;

exposing part of the negative resist just above the first interconnect to light from a front side of the substrate through a photo mask;

removing the negative resist except exposed part of the negative resist; and

forming a second interconnect together with the gate electrode by etching the conductive film using the exposed part as an etching mask.

3. The method for manufacturing a semiconductor device according to claim 1, further comprising the steps of:

forming a first interconnect from the metal film on the substrate together with the source electrode and the drain electrode;

exposing the negative resist to light from the back of the substrate using, as a mask, the first interconnect as well as the source electrode and the drain electrode;

removing the negative resist except exposed part of the negative resist;

forming a second interconnect together with the gate electrode by etching the conductive film using the exposed part as an etching mask; and

forming a third interconnect in an area of division of the second interconnect just above the first interconnect to connect the area.

4. The method for manufacturing a semiconductor device according to claim 1, wherein i rays of a mercury lamp are used as a light source for the back exposure.

5. The method for manufacturing a semiconductor device according to claim 1, wherein the substrate is a plastic film.

6. The method for manufacturing a semiconductor device according to claim 1, wherein the channel layer is made of Zn—

O, In—

O, Ga—

O, Sn—

O, In—

Ga—

Zn—

O, Zn—

Sn—

O, In—

Sn—

O, In—

Zn—

O, Ga—

Zn—

O or In—

Ga—

O.

7. The method for manufacturing a semiconductor device according to claim 1, wherein the gate insulating film is made of Si—

O, Al—

O or Si—

N.

8. The method for manufacturing a semiconductor device according to claim 1, wherein the conductive film is made of In—

Sn—

O, Al—

Zn—

O, or Sn—

O.

9. The method for manufacturing a semiconductor device according to claim 1,

wherein the substrate, the channel layer, the gate insulating film, and the conductive film are transparent;

and

wherein the metal film is opaque.

10. A method for manufacturing a semiconductor device, comprising the steps of:

forming a gate electrode from a metal film over a substrate;

forming a gate insulating film over the gate electrode and the substrate;

forming a channel layer from oxide semiconductor over the gate insulating film;

forming a conductive film over the channel layer;

coating the conductive film with negative resist;

exposing the negative resist to light from a back of the substrate using the gate electrode as a mask;

removing the negative resist except exposed part of the negative resist; and

forming a source electrode and a drain electrode by etching the conductive film using the exposed part as an etching mask.

11. The method for manufacturing a semiconductor device according to claim 10, further comprising the steps of:

forming a first interconnect from the metal film on the substrate together with the gate electrode;

exposing the negative resist to light from the back of the substrate using, as a mask, the first interconnect as well as the gate electrode;

exposing part of the negative resist just above the first interconnect to light from a front side of the substrate through a photo mask;

removing the negative resist except exposed part of the negative resist; and

forming a second interconnect together with the source electrode and the drain electrode by etching the conductive film using the exposed part as an etching mask.

12. The method for manufacturing a semiconductor device according to claim 10, further comprising the steps of:

forming a first interconnect from the metal film on the substrate together with the gate electrode;

exposing the negative resist to light from the back of the substrate using, as a mask, the first interconnect as well as the gate electrode;

removing the negative resist except exposed part of the negative resist;

forming a second interconnect together with the source electrode and the drain electrode by etching the conductive film using the exposed part as an etching mask; and

forming a third interconnect in an area of division of the second interconnect just above the first interconnect to connect the area.

13. The method for manufacturing a semiconductor device according to claim 10, wherein i rays of a mercury lamp are used as a light source for the back exposure.

14. The method for manufacturing a semiconductor device according to claim 10, wherein the substrate is a plastic film.

15. The method for manufacturing a semiconductor device according to claim 10, wherein the channel layer is made of Zn—

O, In—

O, Ga—

O, Sn—

O, In—

Ga—

Zn—

O, Zn—

Sn—

O, In—

Sn—

O, In—

Zn—

O, Ga—

Zn—

O or In—

Ga—

O.

16. The method for manufacturing a semiconductor device according to claim 10, wherein the gate insulating film is made of Si—

O, Al—

O or Si—

N.

17. The method for manufacturing a semiconductor device according to claim 10, wherein the conductive film is made of In—

Sn—

O, Al—

Zn—

O, or Sn—

O.

18. The method for manufacturing a semiconductor device according to claim 10,

wherein the substrate, the channel layer, the gate insulating film, and the conductive film are transparent;

and

wherein the metal film is opaque.

19. A semiconductor device manufactured by:

forming, over a substrate, a source electrode and a drain electrode from a metal film and a channel layer from oxide semiconductor;

forming a gate insulating film over the source electrode, the drain electrode, and the channel layer;

forming a conductive film over the gate insulating film;

coating the conductive film with negative resist;

exposing the negative resist to light from a back of the substrate using the source electrode and the drain electrode as a mask;

removing the negative resist except exposed part of the negative resist; and

forming a gate electrode by etching the conductive film using the exposed part as an etching mask.