METHODS OF FORMING AN INTEGRATED CIRCUIT WITH SELF-ALIGNED TRENCH FORMATION

• US 20120108069A1
• Filed: 01/10/2012
• Published: 05/03/2012
• Est. Priority Date: 09/11/2008
• Status: Active Grant

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Micron Technology, Inc.
• Inventors: Juengling, Werner, Lane, Richard
• Granted Patent: US 8,343,875 B2
• Time in Patent Office: Days
• US Class Current: 438/696
• CPC Class Codes: H01L 21/3086 characterised by the process involved to create the mask, e.g. lift-off masks, sidewalls, or to modify the mask, e.g. pre-treatment, post-treatment
• CPC Class Codes: H01L 21/3088 Process specially adapted to improve the resolution of the mask
• CPC Class Codes: H01L 21/31053 involving a dielectric removal step
• CPC Class Codes: H01L 21/76224 using trench refilling with dielectric materials trench filling with polycristalline silicon H01L21/763; together with vertical isolation, e.g. trench refilling in a SOI substrate H01L21/76264
• CPC Class Codes: H01L 29/0649 Dielectric regions, e.g. SiO2 regions, air gaps
• CPC Class Codes: H10B 12/0387 Making the trench

Abstract

Methods for forming a semiconductor device include forming self-aligned trenches, in which a first set of trenches is used to align a second set of trenches. Methods taught herein can be used as a pitch doubling technique, and may therefore enhance device integration. Further, employing a very thin CMP stop layer, and recessing surrounding materials by about an equal amount to the thickness of the CMP stop layer, provides improved planarity at the surface of the device.

Claims

1. A method of forming an integrated circuit, the method comprising:

forming a structure on a substrate, the structure comprising a structural material and an etch stop, the etch stop having an upper surface and a lower surface;

planarizing the structure and stopping planarizing on the etch stop;

selectively recessing the structural material such that an exposed upper surface of the structural material is approximately coplanar with the lower surface of the etch stop; and

selectively removing the etch stop to leave an approximately coplanar surface including the exposed upper surface of the recessed structural material.

2. The method of claim 1, wherein the structural material comprises a form of silicon oxide.

3. The method of claim 1, wherein the etch stop comprises nitride.

4. The method of claim 3, wherein the etch stop comprises Si₃N₄.

5. The method of claim 1, wherein, before selectively removing the etch stop and after planarizing, the etch stop has a thickness between about 10 Å

and 70 Å

.

6. The method of claim 1, wherein selectively recessing the structural material to be approximately coplanar with the lower surface of the etch stop comprises selectively recessing the structural material to a level within ±

20 Å

of the lower surface of the etch stop.

7. The method of claim 1, wherein selectively removing the etch stop exposes an upper surface of a different material than the structural material, and wherein the upper surface of the different material is approximately coplanar with the exposed upper surface of the recessed structural material.

8. The method of claim 1, wherein the approximately coplanar surface left from selectively removing the etch stop includes substantially all materials directly surrounding the exposed upper surface of the recessed structural material in plan view.

9. The method of claim 1, further comprising:

forming a trench in the substrate; and

lining the trench with a liner layer;

wherein the etch stop and an adjacent etch stop are disposed over the substrate on opposing sides of the trench.

10. The method of claim 9, wherein a portion of the liner layer protrudes above the structural material between the etch stop and the adjacent etch stop after selectively recessing the structural material.

11. The method of claim 10, wherein the portion of the liner layer that protrudes above the structural material is selectively removed while selectively removing the etch stop.

12. The method of claim 10, wherein the portion of the liner layer that protrudes above the structural material comprises nitride.

13. The method of claim 12, further comprising lining the trench with at least one oxide liner layer.

14. The method of claim 13, wherein lining the trench with at least one oxide liner includes forming oxide liners on opposing sides of the liner layer.