Method of making an electrode contact structure and structure therefor

• US 8,921,184 B2
• Filed: 05/14/2012
• Issued: 12/30/2014
• Est. Priority Date: 05/14/2012
• Status: Active Grant

• Current Assignee: Semiconductor Components Industries LLC (ON Semiconductor Corporation)
• Original Assignee: Semiconductor Components Industries LLC (ON Semiconductor Corporation)
• Inventors: Grivna, Gordon M.
• Primary Examiner(s): Thai, Luan C
• Application Number:
  US13/471,160
• Publication Number:
  US 20130299996A1
• Time in Patent Office: 960 Days
• Field of Search: 438/270, 438/652, 438/589
• US Class Current: 438/270
• CPC Class Codes: H01L 29/407 Recessed field plates, e.g. trench field plates, buried field plates
• 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 29/4236 within a trench, e.g. trench gate electrode, groove gate electrode
• CPC Class Codes: H01L 29/42368 the thickness being non-uniform
• 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 29/66719 With a step of forming an insulating sidewall spacer
• 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 29/7811 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

In one embodiment, a method for forming a semiconductor device having a shield electrode includes forming first and second shield electrode contact portions within a contact trench. The first shield electrode contact portion can be formed recessed within the contact trench and includes a flat portion. The second shield electrode contact portion can be formed within the contact trench and makes contact to the first shield electrode contact portion along the flat portion.

Claims

1. A method for forming an electrode contact structure comprising the steps of:

providing a region of semiconductor material having a major surface;

forming a contact trench extending from the major surface into the region of semiconductor material;

forming a first dielectric layer along surfaces of the contact trench;

forming a first electrode contact portion adjacent the first dielectric layer, wherein the first electrode contact portion is recessed below the major surface;

forming a second dielectric layer overlying the first electrode contact portion;

forming spacers along upper sidewall surfaces of the contact trench;

forming an opening in the second dielectric layer aligned to the spacers; and

forming a second electrode contact portion within the contact trench adjacent the spacers and contacting the first electrode contact portion within the contact trench.

2. The method of claim 1, wherein the step of forming the first dielectric layer comprises the steps of:

forming a first oxide layer along surfaces of the contact trench;

forming a second oxide layer along surfaces of the first oxide layer, where the second oxide layer comprises a deposited oxide; and

removing upper portions of the first and second oxide layers after the step of forming the first electrode contact portion.

3. The method of claim 1, wherein the step of forming the first electrode contact portion comprises the steps of:

forming a first conductive layer within the contact trench; and

removing portions of the first conductive layer while leaving another portion of the first conductive layer within a lower portion of the contact trench, wherein the removing step forms the first electrode contact portion with a horizontal portion, and wherein the step of forming the second electrode contact portion includes forming the second contact portion so that the second contact portion makes contact to the first electrode contact portion along the horizontal portion.

4. The method of claim 3, wherein the step of removing portions of the first conductive layer comprises the steps of:

planarizing the first conductive layer; and

etching the first conductive layer to recess the first conductive layer within the contact trench.

5. The method of claim 1 further comprising the steps of:

forming a third dielectric layer along upper surfaces of the contact trench and overlying the first electrode contact portion; and

forming oxidation-resistant spacers along the third dielectric layer, wherein the step of forming the second dielectric layer comprises forming the second dielectric layer using localized oxidation.

6. The method of claim 5, wherein the step of forming the oxidation-resistant spacers comprises forming nitride spacers.

7. The method of claim 1 further comprising the step of recessing the second electrode contact portion within the contact trench below the major surface.

8. The method of claim 1 further comprising the steps of:

forming an inter-layer dielectric overlying the major surface;

forming an opening in the interlayer dielectric aligned to the second electrode contact portion; and

forming a conductive plug in the opening and contacting the second electrode contact portion.

9. The method of claim 8 further comprising the step of forming a conductive region in an upper portion of the second electrode contact portion.

10. The method of claim 9, wherein the step of forming the conductive region comprises forming a self-aligned silicide region.

11. The method of claim 1, wherein the step of forming the first electrode contact portion comprises forming the first electrode contact portion configured as a first shield electrode contact portion.

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

providing a region of semiconductor material having first and second opposing major surfaces;

forming a contact trench extending from the first major surface into the region of semiconductor material;

forming a first dielectric layer along surfaces of the contact trench;

forming a first shield electrode contact portion adjacent the first dielectric layer, wherein the first electrode contact portion is recessed below the first major surface and includes a flat portion parallel to the second major surface;

forming a second dielectric layer overlying the first electrode contact portion;

forming an opening in the second dielectric layer; and

forming a second shield electrode contact portion within the contact trench contacting the first electrode contact portion within the contact trench and along the flat portion.

13. The method of claim 12 further comprising the step of forming spacers along upper sidewall surfaces of the contact trench before the step of forming the opening in the second dielectric layer, wherein the step of forming the opening includes forming the opening self-aligned to the spacers, and wherein the step of forming the second electrode contact portion includes forming the second electrode contact portion adjacent the spacers.

14. The method of claim 12, wherein the step of forming the first dielectric layer comprises the steps of:

forming an oxide layer along surfaces of the contact trench; and

removing upper portions of the oxide layer after the step of forming the first electrode contact portion.

15. The method of claim 12 further comprising the steps of:

forming a third dielectric layer along upper surfaces of the contact trench and overlying the first electrode contact portion; and

forming oxidation-resistant spacers along the third dielectric layer, wherein the step of forming the second dielectric layer comprises forming the second dielectric layer using localized oxidation.

16. The method of claim 12 further comprising the steps of:

recessing the second electrode contact portion within the contact trench below the first major surface;

forming a conductive region in an upper portion of the second electrode contact portion;

forming an inter-layer dielectric overlying the major surface;

forming an opening in the interlayer dielectric aligned to the second electrode contact portion; and

forming a conductive plug in the opening and contacting the second electrode contact portion.

17. A method of forming a semiconductor device having a shield electrode comprising:

providing a region of semiconductor material having first and second opposing major surfaces;

forming a contact trench extending from the first major surface into the region of semiconductor material;

forming a first dielectric layer along surfaces of the contact trench;

forming a first shield electrode contact portion adjacent the first dielectric layer, wherein the first electrode contact portion is recessed below the first major surface and includes a portion generally parallel to the second major surface;

forming oxidation-resistant spacers along upper sidewall surfaces of the contact trench;

forming a second dielectric layer overlying the first electrode contact portion using localized oxidation;

forming an opening in the second dielectric layer; and

forming a second shield electrode contact portion in the contact trench contacting the first electrode contact portion within the contact trench and along the portion generally parallel to the second major surface.

18. The method of claim 17 further comprising forming dielectric spacers along the upper sidewall surfaces of the contact trench before the step of forming the opening in the second dielectric layer, wherein forming the opening includes forming the opening self-aligned to the spacers, and wherein forming the second electrode contact portion includes forming the second electrode contact portion adjacent the dielectric spacers.

19. The method of claim 17 further comprising:

forming a third dielectric layer along the upper sidewall surfaces of the contact trench before the step of forming the oxidation-resistant spacers; and

removing the oxidation-resistant spacers before forming the dielectric spacers.

20. The method of claim 17, wherein the step of forming the first dielectric layer comprises the steps of:

forming a first oxide layer along surfaces of the contact trench;

forming a second oxide layer along surfaces of the first oxide layer, where the second oxide layer comprises a deposited oxide; and

removing upper portions of the first and second oxide layers after the step of forming the first shield electrode contact portion.