Semiconductor memory device and manufacturing method thereof

• US 8,709,889 B2
• Filed: 05/15/2012
• Issued: 04/29/2014
• Est. Priority Date: 05/19/2011
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Saito, Toshihiko
• Primary Examiner(s): Lee, Calvin
• Application Number:
  US13/471,667
• Publication Number:
  US 20120292615A1
• Time in Patent Office: 714 Days
• Field of Search: 257/288, 257/296, 257/311, 438/239, 438/253
• US Class Current: 438/239
• CPC Class Codes: G11C 11/404 with one charge-transfer gate, e.g. MOS transistor, per cell
• 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 21/02631 Physical deposition at reduced pressure, e.g. MBE, sputtering, evaporation
• CPC Class Codes: H01L 21/84 the substrate being other than a semiconductor body, e.g. being an insulating body
• CPC Class Codes: H01L 27/1207 combined with devices in contact with the semiconductor body, i.e. bulk/SOI hybrid circuits
• 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 29/7869 having a semiconductor body comprising an oxide semiconductor material, e.g. zinc oxide, copper aluminium oxide, cadmium stannate
• CPC Class Codes: H10B 41/70 the floating gate being an electrode shared by two or more components

Abstract

A memory cell therein includes a first transistor and a capacitor and stores data corresponding to a potential held in the capacitor. The first transistor includes a pair of electrodes, an insulating film in contact with side surfaces of the electrodes, a first gate electrode provided between the electrodes with the insulating film provided between the first gate electrode and each electrode and whose top surface is at a lower level than top surfaces of the electrodes, a first gate insulating film over the first gate electrode, an oxide semiconductor film in contact with the first gate insulating film and the electrodes, a second gate insulating film at least over the oxide semiconductor film, and a second gate electrode over the oxide semiconductor film with the second gate insulating film provided therebetween. The capacitor is connected to the first transistor through one of the electrodes.

Claims

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

forming a first conductive layer and a second conductive layer over a substrate;

forming a first insulating film covering the first conductive layer and the second conductive layer;

forming a third conductive layer between the first conductive layer and the second conductive layer with the first insulating film interposed between the third conductive layer and each of the first conductive layer and the second conductive layer;

forming a second insulating film over covering the first insulating film and the third conductive layer;

removing part of the first insulating film and part of the second insulating film so as to expose a top surface of the first conductive layer and a top surface of the second conductive layer, thereby forming a first insulating layer in contact with a side surface of the first conductive layer and a side surface of the second conductive layer and a second insulating layer between the first conductive layer and the second conductive layer with the first insulating layer interposed between the second insulating layer and each of the first conductive layer and the second conductive layer;

forming a first semiconductor layer over the first conductive layer, the second conductive layer, and the second insulating layer, wherein the first semiconductor layer is an oxide semiconductor layer and electrically connected to the first conductive layer and the second conductive layer;

forming a third insulating layer covering the first semiconductor layer;

forming a fourth conductive layer over the third conductive layer with the second insulating layer, the first semiconductor layer, and the third insulating layer interposed therebetween;

forming a fourth insulating layer covering the fourth conductive layer; and

forming a fifth conductive layer over the second conductive layer and adjacent to a side surface of the fourth conductive layer with the fourth insulating layer interposed therebetween.

2. The method for manufacturing a semiconductor device according to claim 1, wherein the part of the first insulating film and the part of the second insulating film is removed so that the top surface of the first conductive layer, the top surface of the second conductive layer, and a top surface of the third insulating layer each have a same level.

3. The method for manufacturing a semiconductor device according to claim 1, wherein the part of the first insulating film and the part of the second insulating film is removed by a CMP method.

4. The method for manufacturing a semiconductor device according to claim 1, wherein the third conductive layer is formed so as to surround the second conductive layer.

5. The method for manufacturing a semiconductor device according to claim 1, wherein the oxide semiconductor layer comprises indium, gallium, and zinc.

6. The method for manufacturing a semiconductor device according to claim 1, wherein the first conductive layer and the second conductive layer are formed so that a length of the first conductive layer is larger than that of the second conductive layer.

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

forming a second semiconductor layer over the substrate; and

forming a fifth insulating layer over the second semiconductor layer,

wherein the fifth insulating layer includes an opening,

wherein the first conductive layer is formed over the second semiconductor layer and in the opening of the fifth insulating layer, and

wherein the second conductive layer is formed over the second semiconductor layer with the fifth insulating layer interposed therebetween.

8. The method for manufacturing a semiconductor device according to claim 7,

wherein the second semiconductor layer comprises a first region overlapping with the first conductive layer and a second region overlapping with the second conductive layer, and

wherein the first region has a lower resistivity than the second region.

9. The method for manufacturing a semiconductor device according to claim 7, wherein the first semiconductor layer comprises silicon.

12. The semiconductor device according to claim 1, wherein a top surface of the first conductive layer, a top surface of the second conductive layer, and a top surface of the second insulating layer each have a same level.

13. The semiconductor device according to claim 1, wherein the third conductive layer surrounds the second conductive layer.

14. The semiconductor device according to claim 1, wherein the oxide semiconductor layer comprises indium, gallium, and zinc.

15. The semiconductor device according to claim 1, wherein a length of the first conductive layer is larger than that of the second conductive layer.

16. The semiconductor device according to claim 1, wherein the semiconductor device is a memory device.

10. A semiconductor device comprising:

a first conductive layer;

a second conductive layer;

a first insulating layer in contact with a side surface of the first conductive layer and a side surface of the second conductive layer;

a third conductive layer between the first conductive layer and the second conductive layer with the first insulating layer interposed between the third conductive layer and each of the first conductive layer and the second conductive layer;

a second insulating layer over the third conductive layer;

an oxide semiconductor layer over the first conductive layer, the second conductive layer, and the second insulating layer, wherein the oxide semiconductor layer is electrically connected to the first conductive layer and the second conductive layer;

a third insulating layer over the oxide semiconductor layer; and

a fourth conductive layer over the third conductive layer with the second insulating layer, the oxide semiconductor layer, and the third insulating layer interposed therebetween,

wherein the second insulating layer is provided between the first conductive layer and the second conductive layer with the first insulating layer interposed between the second insulating layer and each of the first conductive layer and the second conductive layer.

11. The semiconductor device according to claim 10, further comprising:

a fourth insulating layer over the second conductive layer and the fourth conductive layer; and

a fifth conductive layer over the second conductive layer and adjacent to a side surface of the fourth conductive layer with the fourth insulating layer interposed therebetween.

17. A semiconductor device comprising;

a first semiconductor layer;

a first insulating layer over the first semiconductor layer, wherein the first insulating layer includes an opening reaching the first semiconductor layer;

a first conductive layer over the first semiconductor layer and in the opening of the first insulating layer;

a second conductive layer over the first semiconductor layer with the first insulating layer interposed therebetween;

a second insulating layer over the first insulating layer and in contact with a side surface of the first conductive layer and a side surface of the second conductive layer;

a third conductive layer over the second insulating layer and between the first conductive layer and the second conductive layer with the second insulating layer interposed between the third conductive layer and each of the first conductive layer and the second conductive layer;

a third insulating layer over the third conductive layer;

a second semiconductor layer over the first conductive layer, the second conductive layer, and the third insulating layer, wherein the second semiconductor layer is an oxide semiconductor layer and electrically connected to the first conductive layer and the second conductive layer;

a fourth insulating layer over the second semiconductor layer;

a fourth conductive layer over the third conductive layer with the third insulating layer, the second semiconductor layer, and the fourth insulating layer interposed therebetween;

a fifth insulating layer over the second conductive layer and the fourth conductive layer; and

a fifth conductive layer over the second conductive layer and adjacent to a side surface of the fourth conductive layer with the fifth insulating layer interposed therebetween,

wherein the third insulating layer is provided between the first conductive layer and the second conductive layer with the second insulating layer interposed between the third insulating layer and each of the first conductive layer and the second conductive layer.

18. The semiconductor device according to claim 17,

wherein the first semiconductor layer comprises a first region overlapping with the first conductive layer and a second region overlapping with the second conductive layer, and

wherein the first region has a lower resistivity than the second region.

19. The semiconductor device according to claim 17, wherein a top surface of the first conductive layer, a top surface of the second conductive layer, and a top surface of the third insulating layer each have a same level.

20. The semiconductor device according to claim 17, wherein the third conductive layer surrounds the second conductive layer.

21. The semiconductor device according to claim 17, wherein the oxide semiconductor layer comprises indium, gallium, and zinc.

22. The semiconductor device according to claim 17, wherein a length of the first conductive layer is larger than that of the second conductive layer.

23. The semiconductor device according to claim 17, wherein the first semiconductor layer comprises silicon.

24. The semiconductor device according to claim 17, wherein the semiconductor device is a memory device.