Field electrode trench transistor structure with voltage divider

• US 7,465,987 B2
• Filed: 08/31/2006
• Issued: 12/16/2008
• Est. Priority Date: 08/31/2005
• Status: Expired due to Fees

• Current Assignee: Infineon Technologies Austria Ag (Infineon Technologies AG)
• Original Assignee: Infineon Technologies Austria Ag (Infineon Technologies AG)
• Inventors: Hirler, Franz, Rieger, Walter, Krumrey, Joachim
• Primary Examiner(s): Pert; Evan
• Assistant Examiner(s): Tran; Tan N
• Application Number:
  US11/468,994
• Publication Number:
  US 20070085136A1
• Time in Patent Office: 838 Days
• Field of Search: 257330-334, 257/E29.201
• US Class Current: 257/330
• CPC Class Codes: H01L 29/407 Recessed field plates, e.g. trench field plates, buried field plates
• CPC Class Codes: H01L 29/7808 the other device being a breakdown diode, e.g. Zener diode
• CPC Class Codes: H01L 29/7811 with an edge termination structure guard regions per se H01L29/0619; field plates per se H01L29/402
• 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 structure having a field electrode arrangement formed in trenches is disclosed. In one embodiment, the field electrode arrangement is conductively connected to subvoltage taps of a voltage divider for the purpose of stabilizing the potentials on a longer time scale than dynamic charge reversal processes.

Claims

1. A trench transistor comprising:

trenches in a transistor array isolated from one another by a mesa region;

a field electrode arrangement, arranged in the trenches, having at least one field electrode which is spaced from the mesa region and the gate electrode by an insulation structure and which is electrically conductive;

a voltage divider having at least one voltage divider element and at least one subvoltage tap is formed in the same or another semiconductor body or in a wiring area, the voltage divider providing a subvoltage, situated between the potential of the source regions and the potential of the drain region, on the at least one subvoltage tap;

a respective field electrode is electrically connected to a respective subvoltage tap, and

wherein the voltage divider elements are in the form of floating spaced apart semiconductor zones, extending to the surface of the semiconductor body, of the second conduction type in the semiconductor body, the semiconductor zones being electrically connected to a respective field electrode, arranged at increasing depth in the semiconductor body, via a subvoltage tap on the semiconductor zone with increasing spacing from the transistor array.

2. The trench transistor structure as claimed in claim 1,

wherein the field electrode arrangement has a plurality of field electrodes which are arranged vertically below one another and which are spaced from one another by the insulation structure;

the voltage divider has a plurality of subvoltage taps which corresponds at least to the plurality of the field electrodes; and

the subvoltage taps are electrically conductively connected to a respective field electrode, arranged at increasing depth in the semiconductor body, in the direction of decreasing potential difference between the subvoltage and drain region.

3. The trench transistor structure as claimed in claim 2, wherein

the voltage divider elements are respectively in the form of a resistor, the voltage divider having series connected voltage divider elements;

and

a potential between interconnected voltage divider elements corresponds to the subvoltage from one of the subvoltage taps.

4. The trench transistor structure as claimed in claim 3, wherein the resistors are respectively in the form of a semiconductor region in the semiconductor body or in the wiring area.

5. The trench transistor structure as claimed in claim 3, wherein the resistors have a respective resistance value of at least 100 MΩ

.

6. The trench transistor structure as claimed in claim 3, wherein the resistors are formed from polysilicon.

7. The trench transistor structure as claimed in claim 1, wherein

the voltage divider elements are in the form of zener diodes, the voltage divider having series connected zener diodes;

and

a potential between interconnected zener diodes corresponds to the subvoltage from one of the subvoltage taps.

8. The trench transistor as claimed in claim 1, comprising:

a drift zone, formed in the mesa region, of a first conductivity type;

a body region, formed above the drift zone, of a second conductivity type, having source regions of the first conductivity type;

a drain region, formed below the drift zone of the first conductivity type;

a gate electrode, which is formed in the trenches and which is spaced from the mesa region by a gate insulation structure.

9. The trench transistor structure as claimed in claim 8, comprising compensation areas of the second conduction type in the drift zone.

10. A trench transistor comprising:

a plurality of trenches in a transistor array extending into a semiconductor body from a surface and which are isolated from one another by a mesa region;

a drift zone, formed in the mesa region for the purpose of picking up a reverse voltage, of a first conductivity type;

a body region, formed above the drift zone, of a second conductivity type, which is the opposite of the first conductivity type, having source regions of the first conductivity type which adjoin the trenches;

a drain region, formed below the drift zone, of the first conductivity type;

a gate electrode, which is formed in the trenches and which is spaced from the mesa region by a gate insulation structure, for controlling the conductivity of channel regions which are formed between the source regions and the drift zone and which adjoin the trenches;

a field electrode arrangement, arranged in the trenches, having at least one field electrode which is spaced from the mesa region and the gate electrode by an insulation structure and which is electrically conductive, wherein

a voltage divider having at least one voltage divider element and at least one subvoltage tap is formed in the same or another semiconductor body or in a wiring area, the voltage divider providing a subvoltage, situated between the potential of the source regions and the potential of the drain region, on the at least one subvoltage tap;

a respective field electrode is electrically connected to a respective subvoltage tap, configured to stabilize potentials on a longer time scale than a dynamic charge reversal process; and

wherein the voltage divider elements are in the form of floating, spaced apart semiconductor zones, extending to the surface of the semiconductor body, of the second conduction type in the semiconductor body, the semiconductor zones being electrically connected to a respective field electrode, arranged at increasing depth in the semiconductor body, via a subvoltage tap on the semiconductor zone with increasing spacing from the transistor array.

11. The trench transistor structure as claimed in claim 10, wherein the field electrode arrangement has a plurality of field electrodes which are arranged vertically below one another and which are spaced from one another by the insulation structure;

the voltage divider has a plurality of subvoltage taps which corresponds at least to the plurality of the field electrodes;

where

the subvoltage taps are electrically conductively connected to a respective field electrode, arranged at increasing depth in the semiconductor body, in the direction of decreasing potential difference between the subvoltage and the drain region.

12. The trench transistor structure as claimed in claim 11, wherein

the voltage divider elements are respectively in the form of a resistor, the voltage divider having series connected voltage divider elements;

and

a potential between interconnected voltage divider elements corresponds to the subvoltage from one of the subvoltage taps.

13. The trench transistor structure as claimed in claim 12, wherein the resistors are respectively in the form of a semiconductor region in the semiconductor body or in the wiring area.

14. The trench transistor structure as claimed in claim 12, wherein the resistors have a respective resistance value of at least 100 MΩ

.

15. The trench transistor structure as claimed in claim 12, wherein the resistors are formed from polysilicon.

16. The trench transistor structure as claimed in claim 10, wherein

the voltage divider elements are in the form of zener diodes, the voltage divider having series connected zener diodes;

and

a potential between interconnected zener diodes corresponds to the subvoltage from one of the subvoltage taps.

17. The trench transistor structure as claimed in claim 10, comprising compensation areas of the second conduction type in the drift zone.

18. A trench transistor structure comprising:

trenches in a transistor array which extend into a semiconductor body from a surface and which are isolated from one another by a mesa region;

a drift zone, formded in the mesa region for the purpose of picking up a reverse voltage, of a first conductivity type;

a body region, formed above the drift zone, of a second conductivity type, which is the opposite of the first conductivity type, having source regions of the first conductivity type which adjoin the trenches;

a drain region, formed below the drift zone, of the first conductivity type;

a gate electrode, which is formed in the trenches and which is spaced from the mesa region by a gate insulation structure, for controlling the conductivity of channel regions which are formed between the source regions and the drift zone and which adjoin the trenches;

a field electrode arrangement, arranged in the trenches having at least one field electrode which is spaced from the mesa region and the gate electrode by an insulation structure and which is electrically conductive,

a voltage divider having at least one voltage divider element and at least one subvoltage tap in the same or another semiconductor body or in a wiring area, the voltage divider providing a subvoltage, situated between the potential of the source regions and the potential of the drain region, on the at least one subvoltage tap, and a respective field electrode being electrically connected to a respective subvoltage tap;

wherein

the voltage divider elements are in the form of floating, spaced apart semiconductor zones, extending to the surface of the semiconductor body, of the second conduction type in the semiconductor body, the semiconductor zones being electrically connected to a respective field electrode, arranged at increasing depth in the semiconductor body, via a subvoltage tap on the semiconductor zone with increasing spacing from the transistor array.