Semiconductor device having a floating semiconductor zone

• US 8,264,033 B2
• Filed: 07/21/2009
• Issued: 09/11/2012
• Est. Priority Date: 07/21/2009
• Status: Active Grant

• Current Assignee: Infineon Technologies Austria Ag (Infineon Technologies AG)
• Original Assignee: Infineon Technologies Austria Ag (Infineon Technologies AG)
• Inventors: Pfirsch, Frank, Cotorogea, Maria, Hirler, Franz, Niedernostheide, Franz-Josef, Raker, Thomas, Schulze, Hans-Joachim, Felsl, Hans Peter
• Primary Examiner(s): Smith, Zandra
• Assistant Examiner(s): GREEN, TELLY D
• Application Number:
  US12/506,844
• Publication Number:
  US 20110018029A1
• Time in Patent Office: 1,148 Days
• Field of Search: 257/135, 257/136, 257/242, 257/329, 257/330, 257/E29.071, 257/E27.095, 257/E27.096, 438/156, 438/173, 438/192, 438/206, 438/212
• US Class Current: 257/330
• CPC Class Codes: H01L 29/0619 with a supplementary region doped oppositely to or in rectifying contact with the semiconductor containing or contacting region, e.g. guard rings with PN or Schottky junction
• CPC Class Codes: H01L 29/0696 of cellular field-effect devices, e.g. multicellular DMOS transistors or IGBTs
• CPC Class Codes: H01L 29/407 Recessed field plates, e.g. trench field plates, buried field plates
• CPC Class Codes: H01L 29/7397 and a gate structure lying on a slanted or vertical surface or formed in a groove, e.g. trench gate IGBT
• CPC Class Codes: H01L 29/7813 with trench gate electrode, e.g. UMOS transistors trench gate electrodes per se H01L29/4236

Abstract

A semiconductor device includes a first trench and a second trench extending into a semiconductor body from a surface. A body region of a first conductivity type adjoins a first sidewall of the first trench and a first sidewall of the second trench, the body region including a channel portion adjoining to a source structure and being configured to be controlled in its conductivity by a gate structure. The channel portion is formed at the first sidewall of the second trench and is not formed at the first sidewall of the first trench. An electrically floating semiconductor zone of the first conductivity type adjoins the first trench and has a bottom side located deeper within the semiconductor body than the bottom side of the body region.

Claims

1. A semiconductor device, comprising:

a first trench and a second trench extending into a semiconductor body from a surface, wherein the first trench and the second trench extend to a same depth into the semiconductor body;

a body region of a first conductivity type adjoining a first sidewall of the first trench and a first sidewall of the second trench, the body region including a channel portion, adjoining a source structure and being configured to be controlled in its conductivity by a gate structure, an insulating structure and an electrode structure being formed in the first trench and the gate structure comprising a gate electrode structure and a gate dielectric structure being formed in the second trench, wherein the channel portion is formed at the first sidewall of the second trench and is not formed at the first sidewall of the first trench; and

an electrically floating semiconductor zone of the first conductivity type adjoining the first trench and having a bottom side located deeper within the semiconductor body than a bottom side of the body region.

2. The semiconductor device of claim 1, wherein a bottom side of the electrically floating semiconductor zone is located deeper within the semiconductor body than the bottom side of the first trench.

3. The semiconductor device of claim 1, wherein the bottom side of the first trench is located deeper within the semiconductor body than a bottom side of the electrically floating semiconductor zone.

4. The semiconductor device of claim 1, wherein the electrically floating semiconductor zone adjoins to the bottom side of the first trench.

5. The semiconductor device of claim 4, wherein the electrically floating semiconductor zone adjoins to a second sidewall of the first trench opposite the first sidewall of the second trench.

6. The semiconductor device of claim 1, wherein a width of the second trench is larger than the width of the first trench.

7. The semiconductor device of claim 1, wherein a width of the first trench is larger than the width of the second trench.

8. The semiconductor device of claim 1, wherein a width of the first trench is equal to the width of the second trench.

9. The semiconductor device of claim 1, wherein the first trench is filled with a dielectric material.

10. The semiconductor device of claim 1, wherein

the source structure adjoins to the first sidewall of the second trench and does not adjoin to the first sidewall of the first trench.

11. The semiconductor device of claim 1, wherein

a dopant density of a body portion adjoining to the first sidewall of the second trench is lower than the dopant density of a body portion adjoining the first sidewall of the first trench.

12. The semiconductor device of claim 1, wherein

a first semiconductor zone of a second conductivity type adjoins to a bottom side of the first trench, the first semiconductor zone having a larger dopant density than a second semiconductor zone of the second conductivity type adjoining to a bottom side of the body region.

13. The semiconductor device of claim 1, wherein

the electrically floating semiconductor zone of the first conductivity type is buried below the surface.

15. An Integrated circuit, including the semiconductor device of claim 1.

14. A semiconductor device, including:

a first trench and a second trench extending into a semiconductor body from a surface wherein the first trench and the second trench extend to a same depth into the semiconductor body, an insulating structure and an electrode structure being formed in the first trench and a gate structure comprising a gate electrode structure and a gate dielectric structure being formed in the second trench;

a body region of a first conductivity type adjoining to a first sidewall of the first trench and to a first sidewall of the second trench;

a source structure that adjoins to the first sidewall of the second trench and does not adjoin to the first sidewall of the first trench; and

an electrically floating semiconductor zone of the first conductivity type adjoining to the first trench and having a bottom side located deeper, within the semiconductor body than the bottom side of the body region.