Contact structure for semiconductor device having trench shield electrode and method

• US 8,362,548 B2
• Filed: 11/14/2008
• Issued: 01/29/2013
• Est. Priority Date: 11/14/2008
• Status: Active Grant

• Current Assignee: Semiconductor Components Industries LLC (ON Semiconductor Corporation)
• Original Assignee: Semiconductor Components Industries LLC (ON Semiconductor Corporation)
• Inventors: Burke, Peter A., Grivna, Gordon M., Venkatraman, Prasad
• Primary Examiner(s): Toledo, Fernando L
• Assistant Examiner(s): Ingham, John C
• Application Number:
  US12/271,030
• Publication Number:
  US 20100123187A1
• Time in Patent Office: 1,537 Days
• Field of Search: 257/328, 257/330, 257/E29.152, 257/E29.154, 257/332, 438/270
• 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 29/41741 for vertical or pseudo-vertical devices
• CPC Class Codes: H01L 29/41766 with at least part of the source or drain electrode having contact below the semiconductor surface, e.g. the source or drain electrode formed at least partially in a groove or with inclusions of conductor inside the semiconductor H01L29/41733 - H01L29/41758 take precedence
• CPC Class Codes: H01L 29/4238 characterised by the surface lay-out
• CPC Class Codes: H01L 29/4925 with a multiple layer structure, e.g. several silicon layers with different crystal structure or grain arrangement with only a vertical doping structure or vertical doping variation H01L29/4916
• CPC Class Codes: H01L 29/4933 with a silicide layer contacting the silicon layer, e.g. Polycide gate with a barrier layer between the silicide and silicon layers H01L29/4941
• CPC Class Codes: H01L 29/66727 with a step of recessing the source electrode
• 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 29/7397 and a gate structure lying on a slanted or vertical surface or formed in a groove, e.g. trench gate IGBT
• CPC Class Codes: H01L 29/7813 with trench gate electrode, e.g. UMOS transistors trench gate electrodes per se H01L29/4236

Abstract

In one embodiment, a contact structure for a semiconductor device having a trench shield electrode includes a gate electrode contact portion and a shield electrode contact portion within a trench structure. Contact is made to the gate electrode and the shield electrode within or inside of the trench structure. A thick passivating layer surrounds the shield electrode in the contact portion.

Claims

1. A semiconductor device structure comprising:

a region of semiconductor material having a major surface;

a first trench structure formed in the region of semiconductor material, wherein the first trench structure includes a control electrode layer and a shield electrode layer;

a contact structure formed in the region of semiconductor material, wherein the first trench structure terminates in the contact structure, and wherein upper surfaces of both the control electrode layer and the shield electrode layer in the contact structure are recessed within the first trench without overlapping the major surface of the region of semiconductor material in the contact structure;

a first conductive layer coupled to the control electrode layer within the first trench structure; and

a second conductive layer coupled to the shield electrode layer within the first trench structure.

2. The structure of claim 1, wherein the first trench structure includes a gate dielectric layer separating the control electrode layer from the region of semiconductor material, and wherein the shield electrode layer in the contact structure is separated from the control electrode layer at the major surface by an insulator layer that is thicker than the gate dielectric layer.

3. The structure of claim 1, wherein the first and second conductive layers comprise conductive plugs.

4. The structure of claim 1, wherein the structure includes an active region separate from the contact structure, and wherein the structure further comprises a contact region formed within the active region for further contacting the shield electrode layer within the active region.

5. The structure of claim 1, wherein the first trench structure extends from an active region of the semiconductor device to the contact structure, wherein the second conductive layer makes contact to the shield electrode layer adjacent an edge of the semiconductor device, and wherein the first conductive layer is between the active area and the second conductive layer.

6. The structure of claim 1, wherein the control electrode layer is separated from the region of semiconductor material by a first insulator layer, and wherein the shield electrode layer is separated from the region of semiconductor material by a second insulator layer, and wherein the control electrode layer is separated from the shield electrode layer by a third insulator layer, wherein the second and third insulator layers are thicker than the first insulator layer.

7. The structure of claim 6, wherein the third insulator layer is thinner than the second insulator layer.

8. The structure of claim 6, wherein the second and third insulator layers separate the shield electrode layer from the control electrode layer in proximity to the major surface in the contact region.

9. The structure of claim 6, wherein the first trench structure includes a flared portion in the contact structure, and wherein the second and third insulator layers separate the shield electrode layer from the control electrode layer in the flared portion.

10. The structure of claim 1, wherein the first trench structure comprises a first flared portion in the contact structure, and wherein the first conductive layer makes contact to the control electrode layer in the first flared portion.

11. The structure of claim 10, wherein the second conductive layer makes contact to the shield electrode layer in the first flared portion.

12. The structure of claim 10, wherein the first trench structure comprises a second flared portion in the contact structure different than the first flared portion, and wherein the second conductive layer makes contact to the shield electrode layer in the second flared portion.

13. A semiconductor device structure comprising:

a region of semiconductor material having a major surface, an active area, and a contact area;

a trench having a striped shape formed in the region of semiconductor material and extending from the active area to the contact area;

a shield electrode formed in the trench and separated from the region of semiconductor material by a first insulator layer;

a control electrode formed in the trench and separated from the region of semiconductor material by a second insulator layer and separated from the shield electrode by a third insulator layer, wherein shield electrode and the control electrode terminate in the contact area without overlapping the major surface of the region of semiconductor material in the contact area, and wherein the shield electrode and the control electrode are recessed below the major surface of the region of semiconductor material in the contact area;

a first conductive structure contacting the control electrode inside the trench within the contact area; and

a second conductive structure contacting the shield electrode inside the trench within the contact area.

14. The structure of claim 13, wherein the first and third insulator layers are thicker than the second insulator layer, and wherein the first and third insulator layers isolate the shield electrode from the control electrode adjacent the major surface in the contact area.

15. The structure of claim 13, wherein the trench includes a flared portion within the contact area for making contact to at least one of the control electrode and the shield electrode.

16. The structure of claim 13 further comprising a metal silicide layer formed on the control electrode and extending along the control electrode from the active area to the contact area.

17. The structure of claim 13, wherein the first and second conductive structures comprise metal plugs.

18. A semiconductor device structure comprising:

a region of semiconductor material having a major surface, an active area, and a contact area;

a trench having a striped shape formed in the region of semiconductor material and extending from the active area to the contact area;

a shield electrode formed in the trench and separated from the region of semiconductor material by a first insulator layer;

a control electrode formed in the trench and separated from the region of semiconductor material by a second insulator layer and separated from the shield electrode by a third insulator layer, wherein the shield electrode and the control electrode terminate in the contact area without overlapping the major surface of the region of semiconductor material in the contact area, and wherein the control electrode is recessed below the major surface of the region of semiconductor material in the contact area, and wherein the first and third insulator layers are thicker than the second insulator layer, and wherein the first and third insulator layers isolate the shield electrode from the control electrode adjacent the major surface of the region of semiconductor material in the contact area;

a first conductive structure contacting the control electrode inside the trench within the contact area; and

a second conductive structure contacting the shield electrode within the contact area.

19. The structure of claim 18, wherein the trench includes a flared portion within the contact area, and wherein at least the second conductive structure contacts the shield electrode within the flared portion.

20. The structure of claim 18 further comprising:

a source region formed adjacent the trench in the active area; and

a third conductive structure coupled to the source region in the active area and further coupled to the second conductive structure.

21. The structure of claim 18, wherein the shield electrode includes a transition portion where the shield electrode extends towards the major surface in the contact area, wherein the transition portion is rounded.

22. A method for forming a semiconductor device comprising the steps of:

providing a region of semiconductor material having a major surface, an active area, and a contact area;

forming a trench having a striped shape in the region of semiconductor material and extending from the active area to the contact area;

forming a shield electrode in the trench and separated from the region of semiconductor material by a first insulator layer;

forming a control electrode in the trench and separated from the region of semiconductor material by a second insulator layer and separated from the shield electrode by a third insulator layer, wherein the shield electrode and the control electrode terminate in the contact area without overlapping the major surface of the region of semiconductor material in the contact area, and wherein the shield electrode and the control electrode are recessed below the major surface of the region of semiconductor material in the contact area;

forming a first conductive structure contacting the control electrode inside the trench within the contact area; and

forming a second conductive structure contacting the shield electrode inside the trench within the contact area.