Semiconductor device and method of manufacturing the same

Abstract

A method of manufacturing an MIS semiconductor device includes forming a high dielectric film as a gate insulator on a semiconductor substrate of a first conductivity type, heat-treating the semiconductor substrate in ambient with hydrogen and oxygen gases to form an interface layer between the semiconductor substrate and the high dielectric film, forming a conductive film on the high dielectric film after the interfacial layer is formed, processing the conductive film in a gate pattern to form a gate electrode, and doping the semiconductor substrate with impurities of a second conductivity type using the gate electrode as a mask to form source/drain regions.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

FIG. 1 is a schematic cross sectional view of the structure of an MIS semiconductor device according to the first embodiment;

FIGS. 2A to 2D are cross sectional views showing a process of manufacturing the MIS semiconductor device according to the first embodiment;

FIG. 3A shows a cross sectional TEM photograph of the crystal structure of a gate electrode section obtained when an interfacial layer is formed according to the first embodiment;

FIG. 3B shows a cross sectional TEM photograph of the crystal structure of a gate electrode section obtained when an interfacial layer is formed according to a prior art method;

FIG. 4 shows a graph of variations of the interface state density Dit, S factor, and silicon-oxide-film equivalent oxide thickness (EOT) in an nMISFET when the temperature of processing varies;

FIG. 5 shows a graph of effective field dependency of electron mobility in the nMISFET when the temperature of processing varies;

FIG. 6A is a diagram showing a profile of oxygen density in a gate insulating film;

FIG. 6B shows a graph of a differential value of the oxygen density in the gate insulating film;

FIG. 7 is a schematic cross sectional view of an MIS semiconductor device according to the second embodiment; and

FIGS. 8A to 8D are cross sectional views showing a process of manufacturing the MIS semiconductor device according to the second embodiment.

Claims

1. A method of manufacturing an MIS semiconductor device, comprising: forming a high dielectric film as a gate insulator on a semiconductor substrate of a first conductivity type;heat-treating the semiconductor substrate in ambient with hydrogen and oxygen gases to form an interfacial layer between the semiconductor substrate and the high dielectric film;forming a conductive film on the high dielectric film after the interfacial layer is formed;processing the conductive film in a gate pattern to form a gate electrode; anddoping the semiconductor substrate with impurities of a second conductivity type using the gate electrode as a mask to form source/drain regions.

2. The method according to claim 1, wherein the heat-treating includes heat-treating the semiconductor substrate at a temperature ranging from 800° C. to 1100° C. in ambient with hydrogen and oxygen gases.

3. The method according to claim 2, wherein the heat-treating includes heat-treating the semiconductor substrate at a temperature of 900° C. or higher in ambient with hydrogen and oxygen gases.

4. The method according to claim 1, wherein forming the high dielectric film as the gate insulator includes forming the gate insulating film with a high dielectric film containing hafnium atoms, oxygen atoms, and nitrogen atoms.

5. A method of manufacturing an MIS semiconductor device, comprising: forming a high dielectric film as a gate insulator on a semiconductor substrate of a first conductivity type;forming a conductive film on the high dielectric film;processing the conductive film in a gate pattern to form a gate electrode;heat-treating the semiconductor substrate with the gate electrode in ambient with hydrogen and oxygen gases to form an interfacial layer between the semiconductor substrate and the high dielectric film; anddoping the semiconductor substrate with impurities of a second conductivity type using the gate electrode as a mask, after the interface layer is formed to form source/drain regions.

6. The method according to claim 5, wherein the heat-treating includes heat-treating the semiconductor substrate at a temperature ranging from 800° C. to 1100° C. in ambient with hydrogen and oxygen gases.

7. The method according to claim 6, wherein the heat-treating includes heat-treating the semiconductor substrate at a temperature of 900° C. or higher in ambient with hydrogen and oxygen gases.

8. The method according to claim 5, wherein forming the high dielectric film as the gate insulator includes forming the gate insulating film with a high dielectric film containing hafnium atoms, oxygen atoms, and nitrogen atoms.

9. A method of manufacturing an MIS semiconductor device, comprising: forming a high dielectric film as a gate insulation film on a semiconductor substrate of a first conductivity type;forming a conductive film on the high dielectric film;processing the conductive film in a gate pattern to form a gate electrode;forming a sidewall insulating film on either side of the gate electrode;heat-treating the semiconductor substrate with the gate electrode and the sidewall insulating film in ambient with hydrogen and oxygen gases to form an interfacial layer between the semiconductor substrate and the high dielectric film; anddoping the semiconductor substrate with impurities of a second conductivity type using the gate electrode and the sidewall insulating film as a mask, after the interfacial layer is formed to form source/drain regions.

10. The method according to claim 9, wherein the heat-treating includes heat-treating the semiconductor substrate at a temperature ranging from 800° C. to 1100° C. in ambient with hydrogen and oxygen gases.

11. The method according to claim 10, wherein the heat-treating includes heat-treating the semiconductor substrate is heat-treated at a temperature of 900° C. or higher in ambient with hydrogen and oxygen gases.

12. The method according to claim 9, wherein forming the high dielectric film as the gate insulator includes forming the gate insulating film with a high dielectric film containing hafnium atoms, oxygen atoms, and nitrogen atoms.

13. An MIS semiconductor device comprising: a semiconductor substrate of a first conductivity type;a gate electrode formed on the semiconductor substrate;a high dielectric gate insulating film formed between the gate electrode and the semiconductor and having an oxygen density profile controlled such that the gate insulating film contains at least a region having zero or more differential value of oxygen density with respect to its thickness direction, the region existing within an area defined by a distance of 0.5 nm or more from a first interface toward a second interface and a distance of 0.3 nm or more from the second interface toward the first interface, and the first interface being an interface between the gate electrode and the gate insulating film and the second interface being an interface between the semiconductor substrate and the gate insulating film to the region; andsource/drain regions of a second conductivity type, which are formed on a surface of the semiconductor substrate and between which a channel region is formed under the gate electrode.

14. The device according to claim 13, wherein the gate insulating film is formed of a high dielectric film containing hafnium atoms, oxygen atoms, and nitrogen atoms.

15. The device according to claim 13, wherein the semiconductor substrate is formed of a semiconductor substrate heat-treated at a temperature ranging from 800° C. to 1100° C. in ambient with hydrogen and oxygen gases.

16. The method according to claim 15, wherein the semiconductor substrate is formed of a semiconductor substrate heat-treated at a temperature of 900° C. or higher in ambient with hydrogen and oxygen gases.