Semiconductor device with an electrode buried in a cavity

• US 9,171,918 B2
• Filed: 07/16/2014
• Issued: 10/27/2015
• Est. Priority Date: 08/29/2011
• Status: Active Grant

• Current Assignee: Infineon Technologies Austria Ag (Infineon Technologies AG)
• Original Assignee: Infineon Technologies Austria Ag (Infineon Technologies AG)
• Inventors: Ahrens, Carsten, Baumgartl, Johannes, Santos Rodriguez, Francisco Javier, Schulze, Hans-Joachim
• Primary Examiner(s): Oh, Jaehwan
• Application Number:
  US14/332,438
• Publication Number:
  US 20140327103A1
• Time in Patent Office: 468 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: H01L 21/28 Manufacture of electrodes on semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/268 etching for patterning the electrodes H01L21/311, H01L21/3213; multistep manufacturing processes for data storage electrodes H01L29/4011
• CPC Class Codes: H01L 21/743 Making of internal connections, substrate contacts
• CPC Class Codes: H01L 23/535 including internal interconnections, e.g. cross-under constructions internal lead connections H01L23/481
• CPC Class Codes: H01L 29/41 characterised by their shape, relative sizes or dispositions
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00

Abstract

A semiconductor device includes an active device region formed in an epitaxial layer disposed on a semiconductor substrate and a buried electrode disposed below the active device region in a cavity formed within the semiconductor substrate. The buried electrode includes an electrically conductive material different than the material of the semiconductor substrate.

Claims

1. A semiconductor device, comprising:

an active device region formed in an epitaxial layer disposed on a semiconductor substrate;

a buried electrode disposed below the active device region in a cavity formed within the semiconductor substrate, the buried electrode comprising an electrically conductive material different than the material of the semiconductor substrate, and

an electrically conductive contact which extends from the buried electrode to a surface of the semiconductor substrate,

wherein the material of the semiconductor substrate is doped more heavily in a region adjacent the buried electrode than in a region of the semiconductor substrate between the active device region and the more heavily doped region of the semiconductor substrate material.

2. The semiconductor device of claim 1, wherein the buried electrode comprises a metal material.

3. The semiconductor device of claim 2, wherein the buried electrode comprises TiN or Tungsten.

4. The semiconductor device of claim 1, wherein the buried electrode comprises polysilicon.

5. The semiconductor device of claim 1, wherein the buried electrode comprises carbon.

6. The semiconductor device of claim 1, wherein the contact extends vertically from the buried electrode to the surface of the semiconductor substrate on which the epitaxial layer is disposed.

7. The semiconductor device of claim 1, wherein the contact extends vertically from the buried electrode to the opposite surface of the semiconductor substrate on which the epitaxial layer is disposed.

8. The semiconductor device of claim 1, wherein the contact extends laterally from the buried electrode to a side surface of the semiconductor substrate which is disposed between top and bottom surfaces of the semiconductor substrate.

9. The semiconductor device of claim 1, wherein the electrically conductive material of the buried electrode is disposed along sidewalls of the cavity formed in the semiconductor substrate so that a cavity is disposed in an inner part of the buried electrode.

10. The semiconductor device of claim 1, wherein the buried electrode is in low ohmic or Schottky contact with the semiconductor substrate.

11. The semiconductor device of claim 1, wherein the active device region is formed at a surface of the epitaxial layer directly over the cavity such that the cavity is spaced apart from the active device region by a portion of the epitaxial layer in a direction perpendicular to the surface.

12. The semiconductor device of claim 11, wherein the buried electrode is directly underneath the active device region in the cavity.

13. A semiconductor device, comprising:

an active device region formed in an epitaxial layer disposed on a semiconductor substrate;

a buried electrode disposed below the active device region in a cavity formed within the semiconductor substrate, the buried electrode comprising an electrically conductive material different than the material of the semiconductor substrate, and

an electrically conductive contact which extends from the buried electrode to a surface of the semiconductor substrate,

wherein the contact extends vertically from the buried electrode to the opposite surface of the semiconductor substrate on which the epitaxial layer is disposed.