Semiconductor device and method for manufacturing the same

• US 20060065934A1
• Filed: 11/29/2004
• Published: 03/30/2006
• Est. Priority Date: 09/29/2004
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Miyano, Kiyotaka, Ishimaru, Kazunari, Okayama, Yasunori
• Granted Patent: US 7,235,469 B2
• Time in Patent Office: Days
• US Class Current: 257/365
• CPC Class Codes: H01L 21/823835 silicided or salicided gate conductors
• CPC Class Codes: H01L 21/823842 gate conductors with different gate conductor materials or different gate conductor implants, e.g. dual gate structures
• CPC Class Codes: H01L 29/4232 with insulated gate
• CPC Class Codes: H01L 29/665 using self aligned silicidation, i.e. salicide formation of conductive layers comprising silicides H01L21/28518

Abstract

A semiconductor device suitable for the miniaturization and comprising properly controlled Si/SiGe gate electrode comprises an insulator formed on a semiconductor substrate, a first gate electrode formed on the insulator and including silicon-germanium, wherein a germanium concentration is higher near an interface to the insulator and lower in a surface side opposite to the insulator, and a second gate electrode formed on the insulator and including silicon-germanium, wherein a germanium concentration is substantially uniform and an n-type dopant of a concentration of above 6×10²⁰ atoms/cm³ is contained.

Claims

1. A semiconductor device comprising:

an insulator formed on a semiconductor substrate;

a first gate electrode formed on the insulator and including silicon-germanium, wherein a germanium concentration is higher near an interface to the insulator and lower in a surface side opposite to the insulator; and

a second gate electrode formed on the insulator and including silicon-germanium, wherein a germanium concentration is substantially uniform and an n-type dopant of a concentration of above 6×

10²⁰ atoms/cm³ is contained.

2. The semiconductor device according to claim 1,

wherein the first gate electrode including the silicon-germanium has a germanium atomic concentration near the interface to the insulator is above 15% but below 50%, a germanium atomic concentration in the surface side is below 5%, and a germanium concentration variation in the first gate electrode is above 10%,

and wherein the second gate electrode including the silicon-germanium has a germanium atomic concentration near the interface to the insulator is below 10%, a germanium atomic concentration in the surface side is below 5%, and a germanium concentration variation in the second gate electrode is below 5%.

3. The semiconductor device according to claim 1, wherein a crystal grain size in the second gate electrode is greater than that in the first gate electrode.

4. The semiconductor device according to claim 1, wherein a width of the first gate electrode in a channel direction at the interface to the insulator is narrower than that at the surface side and a difference between the width at the interface to the insulator and at the surface side in the first gate electrode is greater than that in the second gate electrode.

5. A semiconductor device comprising:

an insulator formed on a semiconductor substrate;

a first gate electrode formed on a semiconductor substrate and including silicon-germanium, wherein a germanium concentration is higher near an interface to the insulator and lower in a surface side opposite to the insulator, and at least one of carbon, nitrogen or oxygen of a concentration of above 1×

10¹⁵ atoms/cm² but below 1×

10¹⁶ atoms/cm² is contained; and

a second gate electrode formed on the insulator and including silicon-germanium, wherein a germanium concentration is substantially uniform and an n-type dopant of a concentration of above 6×

10²⁰ atoms/cm³ is contained.

6. The semiconductor device according to claim 5, wherein the second gate electrode is crystallized after being made into amorphous by implantation.

7. The semiconductor device according to claim 5,

wherein the first gate electrode including the silicon-germanium has a germanium atomic concentration near the interface to the insulator is above 15% but below 50%, a germanium atomic concentration in the surface side is below 5%, and a germanium concentration variation in the first gate electrode is above 10%,

and wherein the second gate electrode including the silicon-germanium has a germanium atomic concentration near the interface to the insulator is below 10%, a germanium atomic concentration in the surface side is below 5%, and a germanium concentration variation in the second gate electrode is below 5%.

8. The semiconductor device according to claim 5, wherein a crystal grain size in the second gate electrode is greater than that in the first gate electrode.

9. The semiconductor device according to claim 5, wherein a width of the first gate electrode in a channel direction at the interface to the insulator is narrower than that at the surface side and a difference between the width at the interface to the insulator and at the surface side in the first gate electrode is greater than that in the second gate electrode.

10. A method for manufacturing a semiconductor device comprising:

forming an insulator on a semiconductor substrate;

forming a first silicon film on the insulator;

forming a semiconductor film containing silicon and germanium on the first silicon film;

forming a second silicon film on the semiconductor film;

introducing an n-type dopant of a concentration of above 6×

10²⁰ atoms/cm³ into at least the second silicon film in a second gate electrode forming area;

forming first and second gate electrodes by processing the first silicon film, semiconductor film and second silicon film; and

heat treating the semiconductor substrate with the first and second gate electrodes formed thereon to allow the germanium in the first and second gate electrodes to be redistributed within each gate electrode to a distribution different each other.

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

wherein the first gate electrode including the silicon-germanium has a germanium atomic concentration near the interface to the insulator is above 15% but below 50%, a germanium atomic concentration in the surface side is below 5%, and a germanium concentration variation in the first gate electrode is above 10%,

and wherein the second gate electrode including the silicon-germanium has a germanium atomic concentration near the interface to the insulator is below 10%, a germanium atomic concentration in the surface side is below 5%, and a germanium concentration variation in the second gate electrode is below 5%.

12. The method for manufacturing a semiconductor device according to claim 10, wherein a thickness of the second silicon film is three times or more thicker than that of the semiconductor film.

13. The method for manufacturing a semiconductor device according to claim 12,

wherein the first gate electrode including the silicon-germanium has a germanium atomic concentration near the interface to the insulator is above 15% but below 50%, a germanium atomic concentration in the surface side is below 5%, and a germanium concentration variation in the first gate electrode is above 10%,

and wherein the second gate electrode including the silicon-germanium has a germanium atomic concentration near the interface to the insulator is below 10%, a germanium atomic concentration in the surface side is below 5%, and a germanium concentration variation in the second gate electrode is below 5%.

14. The method for manufacturing a semiconductor device according to claim 12, further comprising:

introducing at least one of carbon, nitrogen or oxygen of a concentration of above 1×

10¹⁵ atoms/cm² but below 1×

10¹⁶ atoms/cm² into at least the second silicon film in the first gate electrode forming area.

15. The method for manufacturing a semiconductor device according to claim 10, further comprising:

introducing at least one of carbon, nitrogen or oxygen of a concentration of above 1×

10¹⁵ atoms/cm² but below 1×

10¹⁶ atoms/cm² into at least the second silicon film in the first gate electrode forming area.

16. The method for manufacturing a semiconductor device according to claim 15,

wherein the first gate electrode including the silicon-germanium has a germanium atomic concentration near the interface to the insulator is above 15% but below 50%, a germanium atomic concentration in the surface side is below 5%, and a germanium concentration variation in the first gate electrode is above 10%,

and wherein the second gate electrode including the silicon-germanium has a germanium atomic concentration near the interface to the insulator is below 10%, a germanium atomic concentration in the surface side is below 5%, and a germanium concentration variation in the second gate electrode is below 5%.

17. The method for manufacturing a semiconductor device according to claim 10, further comprising:

implanting ions into at least the second silicon film in the second gate electrode forming area to make the second silicon film into amorphous.

18. A method for manufacturing a semiconductor device comprising:

forming an insulator on a semiconductor substrate;

forming a first silicon film on the insulator;

forming a semiconductor film containing silicon and germanium on the first silicon film;

forming a second silicon film on the semiconductor film;

introducing an n-type dopant of a concentration of above 6×

10²⁰ atoms/cm³ into at least the second silicon film in a second gate electrode forming area;

heat treating the semiconductor substrate to allow the germanium in the first and second gate electrodes to be redistributed within each gate electrode to a distribution different each other;

forming first and second electrodes by processing the first silicon film, semiconductor film and second silicon film; and

laterally etching the first gate electrode to make a width in a channel direction near an interface of the gate electrode to the insulator narrower than that at a surface side thereof.

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

wherein the first gate electrode including the silicon-germanium has a germanium atomic concentration near the interface to the insulator is above 15% but below 50%, a germanium atomic concentration in the surface side is below 5%, and a germanium concentration variation in the first gate electrode is above 10%,

and wherein the second gate electrode including the silicon-germanium has a germanium atomic concentration near the interface to the insulator is below 10%, a germanium atomic concentration in the surface side is below 5%, and a germanium concentration variation in the second gate electrode is below 5%.

20. The method for manufacturing a semiconductor device according to claim 18, wherein a thickness of the second silicon film is three times or more thicker than that of the semiconductor film.