FIELD PLATE TRENCH TRANSISTOR AND METHOD FOR PRODUCING IT

• US 20070138544A1
• Filed: 08/31/2006
• Published: 06/21/2007
• Est. Priority Date: 08/31/2005
• Status: Abandoned Application

• Current Assignee: Infineon Technologies Austria Ag (Infineon Technologies AG)
• Original Assignee: Infineon Technologies Austria Ag (Infineon Technologies AG)
• Inventors: Meyer, Thorsten, Hirler, Franz, Pfirsch, Frank, Klein, Wolfgang, Rieger, Walter
• Application Number:
  US11/469,011
• Publication Number:
  US 20070138544A1
• Time in Patent Office: Days
• US Class Current: 257/330
• CPC Class Codes: H01L 27/04 the substrate being a semiconductor body
• CPC Class Codes: H01L 27/0727 in combination with diodes, or capacitors or resistors
• CPC Class Codes: H01L 29/0696 of cellular field-effect devices, e.g. multicellular DMOS transistors or IGBTs
• 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 29/42368 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 29/732 Vertical transistors
• CPC Class Codes: H01L 29/735 Lateral transistors
• CPC Class Codes: H01L 29/7803 structurally associated with at least one other device assemblies H01L25/00; integrated circuits H01L27/00
• CPC Class Codes: H01L 29/7808 the other device being a breakdown diode, e.g. Zener diode
• CPC Class Codes: H01L 29/7813 with trench gate electrode, e.g. UMOS transistors trench gate electrodes per se H01L29/4236
• CPC Class Codes: H01L 29/861 Diodes

Abstract

A field plate trench transistor having a semiconductor body is disclosed. In one embodiment, the semiconductor has a trench structure and 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. The field plate trench transistor has a voltage divider configured such that the field electrode structure is set to a potential lying between source and drain potentials.

Claims

1. A field plate trench transistor having a semiconductor body comprising:

a trench structure; and

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 and/or alongside the gate electrode structure and electrically insulated from the latter; and

a voltage divider provided in and/or on the semiconductor body, the voltage divider being electrically connected to the field electrode structure or integrated into the latter, the voltage divider being configured such that the field electrode structure is set to a potential lying between source and drain potentials and/or gate and drain potentials.

2. The field plate trench transistor as claimed in claim 1, wherein the field electrode structure is divided into a plurality of field electrode regions arranged vertically one above another and the voltage divider is divided into a plurality of voltage divider regions, each voltage divider region being electrically connected to a field electrode region or integrated into the latter, so that at least two different field electrode regions are at different potentials.

3. The field plate trench transistor as claimed in claim 1, wherein the voltage divider is realized as a series circuit comprising at least one resistor and at least one diode which is forward-biased with respect to the drain potential or as a series circuit comprising a plurality of diodes which are forward-biased with respect to the source potential, which are connected between source and drain potentials.

4. The field plate trench transistor as claimed in claim 3, wherein the at least one diode is a zener diode.

5. The field plate trench transistor as claimed in claim 2, wherein the different field electrode regions within the trench structure are electrically insulated from one another, and the voltage divider is provided outside the field electrode structure.

6. The field plate trench transistor as claimed in claim 2, wherein the different field electrode regions within the trench structure are electrically connected to one another, and the voltage divider is provided within the field electrode structure.

7. The field plate trench transistor as claimed in claim 6, wherein pn diodes are provided between the field electrode regions, in such a way that the pn diodes are interlinked with one another via the field electrode regions to form a vertically running diode series circuit.

8. The field plate trench transistor as claimed in claim 7, wherein the upper end of the diode series circuit directly adjoins a source metallization layer of the transistor, and the lower end of the diode series circuit directly adjoins a drift zone provided within the semiconductor body.

9. The field plate trench transistor as claimed in claim 1, wherein the voltage divider has at least one substrate diode which is connected between source and drain potentials and is forward-biased with respect to the drain potential, the substrate diode being formed by the pn junction between a semiconductor zone of a first conduction type provided in the semiconductor body, in particular within the mesa structure, and the part of the semiconductor body of a second conduction type lying below the semiconductor zone, the semiconductor zone of the first conduction type being produced together with the body zones of the trench transistor in one process.

10. The field plate trench transistor as claimed in claim 9, wherein that end of the substrate diode which faces the source potential is connected to a voltage limiting element connected between substrate diode and source potential, which voltage limiting element prevents the potential of the field electrode structure from exceeding a potential maximum value and/or falling below a potential minimum value in the operating state.

11. The field plate trench transistor as claimed in claim 10, wherein the voltage limiting element is at least partly realized in the form of one or a plurality of series-connected diodes which are forward-biased with respect to the drain potential and are formed within the cell array region or the edge region of the semiconductor body or within the trench structure.

12. The field plate trench transistor as claimed in claim 10, wherein the voltage limiting element is at least partly formed in the form of a MOS transistor, the body zone of which is the semiconductor zone of the first conduction type of the substrate diode.

13. The field plate trench transistor as claimed in claim 9, wherein the voltage limiting element is at least partly formed in the form of one or a plurality of capacitive elements formed within the semiconductor body.

14. The field plate trench transistor as claimed in claim 9, wherein that end of the substrate diode which faces the source potential is connected to a pull-down element connected between substrate diode and source potential or gate potential, which pull-down element prevents the potential of the field electrode structure from drifting, in the off state of the transistor, to drain potential as a result of leakage currents occurring within the substrate diode.

15. The field plate trench transistor as claimed in claim 14, wherein the pull-down element is at least partly realized in the form of a resistance element provided within the mesa structure, the gate electrode structure, the field electrode structure or within a conductive element provided above the semiconductor body and electrically insulated from the latter.

16. The field plate trench transistor as claimed in claim 14, wherein the pull-down element is at least partly realized in the form of a transistor formed within the semiconductor body, in particular within the mesa structure.

17. The field plate trench transistor as claimed in claim 9, wherein the substrate diode has a reduced breakdown voltage compared with the transistor elements provided within the cell array of the transistor.

18. A method for producing a field plate trench transistor, comprising:

forming a trench structure; and

providing an insulation structure lining the trench structure, the remaining free space within the trench structure extending downward toward the semiconductor body;

filling the free space by alternately depositing n- and p-doped semiconducting material and metal-containing material;

or

filling the free space by repeatedly depositing a layer made of semiconducting material of the first conduction type, carrying out a coating process in order to form a zone of the second conduction type in the previously deposited layer, and producing a silicide layer on the previously-formed zone of the second conduction type.

19. The method as claimed in claim 18, wherein that part of the insulation structure which is formed in the upper region of the trench structure is partly etched back into the trench structure, and the gate electrode structure is introduced into the resulting cutout.

20. A field plate trench transistor having a semiconductor body comprising:

a trench structure; and

means for providing an electrode structure embedded in the trench structure, the electrode structure being electrically insulated from the semiconductor body by an insulation structure means and having a gate electrode structure and a field electrode structure arranged below and/or alongside the gate electrode structure and electrically insulated from the latter; and

means for providing a voltage divider in and/or on the semiconductor body, the voltage divider means being electrically connected to the field electrode structure or integrated into the latter, the voltage divider means being configured such that the field electrode structure is set to a potential lying between source and drain potentials and/or gate and drain potentials.