SEMICONDUCTOR FILM AND SEMICONDUCTOR DEVICE

• US 20140252345A1
• Filed: 03/04/2014
• Published: 09/11/2014
• Est. Priority Date: 03/06/2013
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: TSUBUKU, Masashi, WATANABE, Ryosuke
• Granted Patent: US 9,829,533 B2
• Time in Patent Office: Days
• US Class Current: 257/43
• CPC Class Codes: G01R 31/2656 using non-ionising electromagnetic radiation, e.g. optical radiation
• CPC Class Codes: H01L 21/02488 Insulating materials
• 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 22/12 for structural parameters, e.g. thickness, line width, refractive index, temperature, warp, bond strength, defects, optical inspection, electrical measurement of structural dimensions, metallurgic measurement of diffusions electrical measurement of diffusions H01L22/14
• CPC Class Codes: H01L 22/14 for electrical parameters, e.g. resistance, deep-levels, CV, diffusions by electrical means
• 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 29/78693 the semiconducting oxide being amorphous
• 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

Abstract

An oxide semiconductor film having high stability with respect to light irradiation or a semiconductor device having high stability with respect to light irradiation is provided. One embodiment of the present invention is a semiconductor film including an oxide in which light absorption is observed by a constant photocurrent method (CPM) in a wavelength range of 400 nm to 800 nm, and in which an absorption coefficient of a defect level, which is obtained by removing light absorption due to a band tail from the light absorption, is lower than or equal to 5×10⁻²/cm. Alternatively, a semiconductor device is manufactured using the semiconductor film.

Claims

1. A semiconductor film comprising:

an oxide,

wherein light absorption of the oxide is observed by a constant photocurrent method in a wavelength range of 400 nm to 800 nm, and

wherein an absorption coefficient of a defect level, which is obtained by removing light absorption due to a band tail from the light absorption, is lower than or equal to 5×

10<sup>−

2</sup>/cm.

2. The semiconductor film according to claim 1, wherein the oxide comprises a crystal part whose c-axis is substantially perpendicular to a surface of the oxide.

3. The semiconductor film according to claim 1,

wherein the oxide is an In-M-Zn oxide, and

wherein M is any one of Al, Ti, Ga, Y, Zr, La, Ce, Nd, and Hf.

4. A semiconductor device comprising:

a gate electrode layer;

a gate insulating film in contact with the gate electrode layer;

an oxide semiconductor layer overlapping with the gate electrode layer with the gate insulating film provided therebetween; and

a source electrode layer and a drain electrode layer in contact with the oxide semiconductor layer,

wherein light absorption of the oxide semiconductor layer is observed by a constant photocurrent method in a wavelength range of 400 nm to 800 nm, and

wherein an absorption coefficient of a defect level, which is obtained by removing light absorption due to a band tail from the light absorption, is lower than or equal to 5×

10<sup>−

2</sup>/cm.

5. The semiconductor device according to claim 4, wherein the oxide semiconductor layer comprises a crystal part whose c-axis is substantially perpendicular to a surface of the oxide semiconductor layer.

6. The semiconductor device according to claim 4,

wherein the oxide semiconductor layer is an In-M-Zn oxide, and

wherein M is any one of Al, Ti, Ga, Y, Zr, La, Ce, Nd, and Hf.

7. The semiconductor device according to claim 4, wherein the oxide semiconductor layer is a multilayer film in which a first oxide semiconductor layer, a second oxide semiconductor layer, and a third oxide semiconductor layer are stacked in this order.

8. The semiconductor device according to claim 7,

wherein an energy difference between an energy at the bottom of a conduction band of the first oxide semiconductor layer and an energy at the bottom of a conduction band of the second oxide semiconductor layer is greater than or equal to 0.05 eV and less than or equal to 2 eV, and

wherein an energy gap between an energy at the bottom of a conduction band of the third oxide semiconductor layer and the energy at the bottom of the conduction band of the second oxide semiconductor layer is greater than or equal to 0.05 eV and less than or equal to 2 eV.

9. The semiconductor device according to claim 7, wherein the second oxide semiconductor layer comprises a crystal part whose c-axis is substantially perpendicular to a surface of the second oxide semiconductor layer.

10. The semiconductor device according to claim 7,

wherein the first to third oxide semiconductor layers are each an In-M-Zn oxide,

wherein M is any one of Al, Ti, Ga, Y, Zr, La, Ce, Nd, and Hf, and

wherein an atomic ratio of M to In in each of the first oxide semiconductor layer and the third oxide semiconductor layer is larger than an atomic ratio of M to In in the second oxide semiconductor layer.

11. The semiconductor device according to claim 4,

wherein each of the source electrode layer and the drain electrode layer comprises a first electrode layer and a second electrode layer over the first electrode layer, and

wherein the second electrode layer is in contact with the oxide semiconductor layer in a region in which the gate electrode layer overlaps with the oxide semiconductor layer.

12. The semiconductor device according to claim 4,

wherein the oxide semiconductor layer has a first region between the source electrode layer and the drain electrode layer, and a second region which overlaps with the source electrode layer or the drain electrode layer, and

wherein a thickness of the oxide semiconductor layer in the first region is smaller than a thickness of the oxide semiconductor layer in the second region.

13. The semiconductor device according to claim 4, further comprising:

a protective film,

wherein the protective film is provided in contact with the oxide semiconductor layer, and

wherein the oxide semiconductor layer is provided between the gate electrode layer and the protective film.