Trench transistor and method for fabricating a trench transistor

• US 7,414,286 B2
• Filed: 08/31/2006
• Issued: 08/19/2008
• Est. Priority Date: 08/31/2005
• Status: Expired due to Fees

• Current Assignee: Infineon Technologies AG
• Original Assignee: Infineon Technologies AG
• Inventors: Hirler, Franz, Zundel, Markus, Zelsacher, Rudolf, Poelzl, Martin
• Primary Examiner(s): Menz; Douglas M
• Application Number:
  US11/513,969
• Publication Number:
  US 20070114600A1
• Time in Patent Office: 719 Days
• Field of Search: 257/E29.118, 257/328, 257/330
• US Class Current: 257/328
• CPC Class Codes: H01L 29/0878 Impurity concentration or distribution
• CPC Class Codes: H01L 29/404 Multiple field plate structures
• CPC Class Codes: H01L 29/407 Recessed field plates, e.g. trench field plates, buried field plates
• CPC Class Codes: H01L 29/41 characterised by their shape, relative sizes or dispositions
• CPC Class Codes: H01L 29/42368 the thickness being non-uniform
• CPC Class Codes: H01L 29/66734 with a step of recessing the gate electrode, e.g. to form a trench gate electrode
• CPC Class Codes: H01L 29/7813 with trench gate electrode, e.g. UMOS transistors trench gate electrodes per se H01L29/4236

Abstract

A trench transistor having a semiconductor body, in which a trench structure and an electrode structure embedded in the trench structure is disclosed. The electrode structure is electrically insulated from the semiconductor body by an insulation structure. The electrode structure has a gate electrode structure and a field electrode structure arranged below the gate electrode structure and electrically insulated from the latter. There is provided between the gate electrode structure and the field electrode structure a shielding structure for reducing the capacitive coupling between the gate electrode structure and the field electrode structure.

Claims

1. A trench transistor, having a semiconductor body, comprising:

a trench structure; and

an electrode structure embedded in the trench structure;

wherein the electrode structure is electrically insulated from the semiconductor body by an insulation structure and has a gate electrode structure and a field electrode structure arranged below the gate electrode structure and electrically insulated from the latter;

wherein there is provided between the gate electrode structure and the field electrode structure a shielding structure for reducing the capacitive coupling between the gate electrode structure and the field electrode structure; and

wherein the sum of the internal resistances of the shielding electrode and the current/voltage supply of the shielding electrode is less than corresponding internal resistance sums for the gate electrode structure and the field electrode structure.

2. The trench transistor as claimed in claim 1, wherein the shielding structure is a shielding electrode which is at a fixed potential and which is electrically insulated from the gate electrode structure, the field electrode structure and the semiconductor body.

3. The trench transistor as claimed in claim 2, wherein the shielding electrode is at source potential.

4. The trench transistor as claimed in claim 1, wherein the shielding structure is realized by a shielding insulation layer, the thickness of which is greater than the thickness of the insulation structure region which insulates the field electrode structure from the semiconductor body.

5. The trench transistor as claimed in claim 4, wherein the thickness of the shielding insulation layer is greater than double the thickness of the insulation structure region which insulates the gate electrode structure from the semiconductor body, or greater than double the thickness of the insulation structure region which insulates the field electrode structure from the semiconductor body.

6. The trench transistor as claimed in claim 4, wherein the shielding insulation layer is a layer sequence comprising a first oxide layer, a nitride layer and a second oxide layer.

7. The trench transistor as claimed in claim 1, wherein the shielding structure has a shielding insulation layer, the k value of which is less than the k value of the insulation structure.

8. The trench transistor as claimed in claim 1, wherein the shielding structure is a cavity.

9. The trench transistor as claimed in claim 1, wherein the horizontal distances between the shielding structure and the semiconductor body are less than the horizontal distances between the gate electrode structure and the semiconductor body.

10. A trench transistor, having a semiconductor body, comprising:

a trench structure;

an electrode structure embedded in the trench structure;

the electrode structure being electrically insulated from the semiconductor body by an insulation structure and having a gate electrode structure and a field electrode structure arranged below the gate electrode structure and electrically insulated from the latter; and

there being provided between the gate electrode structure and the field electrode structure a shielding structure for reducing the capacitive coupling between the gate electrode structure and the field electrode structure, wherein the sum of the internal resistances of the shielding structure and of the current and/or voltage supply thereof is less than the sum of the internal resistances of the gate electrode structure and of the current and/or voltage supply thereof and/or is less than the sum of the internal resistances of the field electrode structure and of the current and/or voltage supply thereof.

11. A semiconductor device comprising:

a semiconductor body;

a trench structure in the semiconductor body;

an electrode structure in the trench structure;

insulation means for insulating the electrode structure from the semiconductor body;

a field electrode structure below the electrode structure and insulated therefrom;

means for reducing capacitive coupling between the gate and field electrode structures; and

a shielding electrode, wherein the sum of the internal resistances of the shielding electrode and the current/voltage supply of the shielding electrode is less than corresponding internal resistance sums for the electrode structure and the field electrode structure.

12. The semiconductor device of claim 11, further comprising a shielding structure.

13. The semiconductor device of claim 12, wherein the shielding structure is between the gate and field electrode structures.

14. The trench transistor as claimed in claim 12, wherein the shielding structure is a shielding electrode which is at a fixed potential and which is electrically insulated from the gate electrode structure, the field electrode structure and the semiconductor body.

15. The trench transistor as claimed in claim 12, wherein the shielding electrode is at source potential.