Shielded gate trench MOSFET package

• US 8,829,603 B2
• Filed: 08/18/2011
• Issued: 09/09/2014
• Est. Priority Date: 08/18/2011
• Status: Active Grant

• Current Assignee: Alpha & Omega Semiconductor, Ltd.
• Original Assignee: Alpha & Omega Semiconductor, Ltd.
• Inventors: Lui, Sik, Su, Yi, Ng, Daniel, Calafut, Daniel, Bhalla, Anup
• Primary Examiner(s): AHMED, SELIM U
• Application Number:
  US13/212,940
• Publication Number:
  US 20130043527A1
• Time in Patent Office: 1,118 Days
• Field of Search: 257329-331, 257/409, 257/E21.418, 257/E21.419, 257/E29.027, 257/E29.262, 257/E21.41
• US Class Current: 257/330
• CPC Class Codes: H01L 2224/0603 Bonding areas having different sizes, e.g. different heights or widths
• CPC Class Codes: H01L 2224/45015 being circular
• CPC Class Codes: H01L 2224/45099 Material
• CPC Class Codes: H01L 2224/4813 Connecting within a semiconductor or solid-state body, i.e. fly wire, bridge wire
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/4911 the connectors being bonded to at least one common bonding area, e.g. daisy chain
• CPC Class Codes: H01L 2224/49111 the connectors connecting two common bonding areas, e.g. Litz or braid wires
• CPC Class Codes: H01L 23/647 Resistive arrangements H01L23/66, H01L23/62 take precedence
• CPC Class Codes: H01L 24/06 of a plurality of bonding areas
• CPC Class Codes: H01L 24/48 of an individual wire connector
• CPC Class Codes: H01L 24/49 of a plurality of wire connectors
• 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 29/4238 characterised by the surface lay-out
• 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 29/7803 structurally associated with at least one other device assemblies H01L25/00; integrated circuits H01L27/00
• 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
• 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 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/10253 : Silicon [Si]
• CPC Class Codes: H01L 2924/12032 : Schottky diode
• CPC Class Codes: H01L 2924/13091 : Metal-Oxide-Semiconductor Field-Effect Transistor [MOSFET]
• CPC Class Codes: H01L 2924/207 : Diameter ranges
• CPC Class Codes: H01L 2924/3025 : Electromagnetic shielding

Abstract

A shielded gate trench field effect transistor can be formed on a substrate having an epitaxial layer on the substrate and a body layer on the epitaxial layer. A trench formed in the body layer and epitaxial layer is lined with a dielectric layer. A shield electrode is formed within a lower portion of the trench. The shield electrode is insulated by the dielectric layer. A gate electrode is formed in the trench above the shield electrode and insulated from the shield electrode by an additional dielectric layer. One or more source regions formed within the body layer is adjacent a sidewall of the trench. A source pad formed above the body layer is electrically connected to the one or more source regions and insulated from the gate electrode and shield electrode. The source pad provides an external contact to the source region. A gate pad provides an external contact to the gate electrode. A shield electrode pad provides an external contact to the shield electrode. A resistive element can be electrically connected between the shield electrode pad and the source lead in the package.

Claims

1. A shielded gate field effect transistor, comprising:

a) a substrate of a first conductivity type;

b) an epitaxial layer of the first conductivity type supported on top of the substrate;

c) a body layer of a second conductivity type that is opposite the first conductivity type formed above the epitaxial layer;

d) a trench formed within the body layer and epitaxial layer, wherein the trench is lined with a dielectric layer;

e) a shield electrode formed within a lower portion of the trench, wherein the shield electrode is insulated from the epitaxial layer by the dielectric layer;

f) a gate electrode formed within the trench above the shield electrode, wherein the gate electrode is insulated from the shield electrode by an additional dielectric layer;

g) one or more source regions of the first conductivity type formed within a top surface of the body layer, wherein each source region is adjacent a sidewall of the trench;

h) a source pad formed above the body layer, wherein the source pad is electrically connected to the one or more source regions and insulated from the gate electrode and the shield electrode, the source pad providing an external contact to the source region;

i) a gate pad formed above the body layer, wherein the gate pad is electrically connected to the gate electrode and insulated from the one or more source regions and the shield electrode, the gate pad providing an external contact to the gate electrode; and

j) a shield pad formed above the body layer, wherein the shield pad is electrically connected to the shield electrode and electrically insulated from the one or more source regions and the gate electrode, the shield pad providing an external contact to the shield electrode.

2. The shielded gate field effect transistor of claim 1, further comprising:

k) a lumped resistive element having one end contacting the shield pad and another end contacting a source lead in a package.

3. The shielded gate trench field effect transistor of claim 2, wherein the lumped resistive element is a metal layer.

4. The shielded gate trench field effect transistor of claim 2, wherein the lumped resistive element is a doped polysilicon layer.

5. The shielded gate trench field effect transistor of claim 1 further comprising an internal resistive element having one end electrically connected to the shield electrode and another end electrically connected to a shield lead in a package.

6. The shielded gate trench field effect transistor of claim 5, wherein the internal resistive element is a lumped resistor comprising polysilicon within the shield electrode.

7. The shielded gate trench field effect transistor of claim 5, wherein the internal resistive element is a lumped resistor comprising polysilicon within the gate electrode.

8. The shielded gate trench field effect transistor of claim 1, wherein the substrate is n+ doped.

9. The shielded gate trench field effect transistor of claim 1, wherein the epitaxial layer is an n type epitaxial layer.

10. The shielded gate trench field effect transistor of claim 1, wherein the body region is a p doped.

11. The shielded gate trench field effect transistor of claim 1, wherein the source regions are n+ doped.

12. The shielded gate trench field effect transistor of claim 1, wherein the gate electrode is composed of polysilicon.

13. The shielded gate trench field effect transistor of claim 1, wherein the shield electrode is composed of polysilicon.

14. The shielded gate field effect transistor of claim 1, wherein the shield electrode is electrically connected to a shield electrode connection region located between two active regions, wherein the shield electrode connection region includes a plurality of shield electrode pickup trenches with each shield electrode pickup trench having a shield electrode pickup contact formed therein.

15. The shielded gate field effect transistor of claim 14, wherein the lump resistance is implemented using heavily doped polysilicon to fill the shield electrode pickup trenches.

16. The shielded gate field effect transistor of claim 14 wherein the lumped resistance is located outside of a termination trench around one or more of the two active regions.

17. The shielded gate field effect transistor of claim 14, wherein the shield electrode pickup contacts are formed inside a termination region around one or more of the two active regions.