Semiconductor device

• US 9,954,004 B2
• Filed: 05/27/2015
• Issued: 04/24/2018
• Est. Priority Date: 12/28/2010
• Status: Expired due to Fees

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Yamazaki, Shunpei
• Primary Examiner(s): Bell, Lauren R
• Application Number:
  US14/722,236
• Publication Number:
  US 20150279860A1
• Time in Patent Office: 1,063 Days
• CPC Class Codes: C04B 2235/3284 Zinc oxides, zincates, cadmium oxides, cadmiates, mercury oxides, mercurates or oxide forming salts thereof
• CPC Class Codes: C04B 2235/3286 Gallium oxides, gallates, indium oxides, indates, thallium oxides, thallates or oxide forming salts thereof, e.g. zinc gallate
• CPC Class Codes: C04B 35/58 based on borides, nitrides, i.e. nitrides, oxynitrides, carbonitrides or oxycarbonitrides or silicides containing free binder metal C22C29/00
• CPC Class Codes: G11C 13/0004 comprising amorphous/crystalline phase transition cells
• CPC Class Codes: G11C 16/0433 comprising cells containing a single floating gate transistor and one or more separate select transistors
• 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: H10B 41/20 characterised by three-dimensional arrangements, e.g. with cells on different height levels
• CPC Class Codes: H10B 41/70 the floating gate being an electrode shared by two or more components

Abstract

The degree of integration of a semiconductor device is enhanced and the storage capacity per unit area is increased. The semiconductor device includes a first transistor provided in a semiconductor substrate and a second transistor provided over the first transistor. In addition, an upper portion of a semiconductor layer of the second transistor is in contact with a wiring, and a lower portion thereof is in contact with a gate electrode of the first transistor. With such a structure, the wiring and the gate electrode of the first transistor can serve as a source electrode and a drain electrode of the second transistor, respectively. Accordingly, the area occupied by the semiconductor device can be reduced.

Claims

1. A semiconductor device comprising:

a first transistor comprising at least a first gate electrode; and

a second transistor comprising;

an oxide semiconductor layer;

a gate insulating layer over the oxide semiconductor layer; and

a second gate electrode over the gate insulating layer,

wherein the oxide semiconductor layer comprises a pair of regions containing argon, and a channel formation region sandwiched therebetween and overlapping with the second gate electrode,

wherein a resistivity of the pair of regions is lower than that of the channel formation region,

wherein one of the pair of regions is in direct contact with an upper surface of the first gate electrode, and

wherein the channel formation region of the second transistor overlaps with a source or a drain of the first transistor in a direction that is perpendicular to the upper surface of the first gate electrode.

2. The semiconductor device according to claim 1, wherein the gate insulating layer overlaps with the channel formation region.

3. The semiconductor device according to claim 1, wherein the oxide semiconductor layer includes indium, gallium, zinc, and oxygen.

4. The semiconductor device according to claim 1, wherein the second gate electrode includes indium, gallium, zinc, oxygen, and nitrogen.

5. The semiconductor device according to claim 1, further comprising:

a conductive layer electrically connected to the other of the pair of regions.

6. The semiconductor device according to claim 1,

wherein the oxide semiconductor layer includes a crystal which is c-axis aligned, and

wherein the oxide semiconductor layer has a triangular or hexagonal atomic arrangement when seen from the direction perpendicular to an a-b plane, and has a variation in the direction of an a-axis or a b-axis in the a-b plane.

7. The semiconductor device according to claim 1, wherein the second transistor is positioned over the first transistor.

8. The semiconductor device according to claim 1, wherein the first gate electrode includes a metal element selected from aluminum, copper, titanium, tantalum and tungsten.

9. A semiconductor device comprising:

a first transistor comprising at least a first gate electrode;

a second transistor comprising;

an oxide semiconductor layer;

a gate insulating layer over the oxide semiconductor layer; and

a second gate electrode over the gate insulating layer, and

a capacitor,

wherein the oxide semiconductor layer comprises a pair of regions containing argon, a channel formation region sandwiched therebetween and overlapping with the second gate electrode, and a region having higher resistivity than the pair of regions,

wherein a resistivity of the pair of regions is lower than that of the channel formation region,

wherein the capacitor comprises the region,

wherein one of the pair of regions is in direct contact with an upper surface of the first gate electrode, and

wherein the channel formation region of the second transistor overlaps with a source or a drain of the first transistor in a direction that is perpendicular to the upper surface of the first gate electrode.

10. The semiconductor device according to claim 9, wherein the gate insulating layer overlaps with the channel formation region.

11. The semiconductor device according to claim 9, wherein the oxide semiconductor layer includes indium, gallium, zinc, and oxygen.

12. The semiconductor device according to claim 9, wherein the second gate electrode includes indium, gallium, zinc, oxygen, and nitrogen.

13. The semiconductor device according to claim 9, further comprising:

a conductive layer electrically connected to the other of the pair of regions.

14. The semiconductor device according to claim 13, wherein the capacitor further comprises the first gate electrode and the gate insulating layer.

15. The semiconductor device according to claim 9,

wherein the oxide semiconductor layer includes a crystal which is c-axis aligned, and

wherein the oxide semiconductor layer has a triangular or hexagonal atomic arrangement when seen from the direction perpendicular to an a-b plane, and has a variation in the direction of an a-axis or a b-axis in the a-b plane.

16. The semiconductor device according to claim 9, wherein the second transistor is positioned over the first transistor.

17. The semiconductor device according to claim 9, wherein the first gate electrode includes a metal element selected from aluminum, copper, titanium, tantalum and tungsten.