METHOD OF FORMING VIAS IN SEMICONDUCTOR SUBSTRATES AND RESULTING STRUCTURES

• US 20070262464A1
• Filed: 07/20/2007
• Published: 11/15/2007
• Est. Priority Date: 08/24/2004
• Status: Active Grant

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Micron Technology, Inc.
• Inventors: Wood, Alan, Akram, Salman, Kirby, Kyle, Farnworth, Warren, Watkins, Charles
• Granted Patent: US 7,855,140 B2
• Time in Patent Office: Days
• US Class Current: 257/774
• CPC Class Codes: H01L 21/76898 formed through a semiconductor substrate

Abstract

Methods for forming through vias in a semiconductor substrate and resulting structures are disclosed. In one embodiment, a through via may be formed by forming a partial via from the active surface through a conductive element thereon and a portion of the substrate underlying the conductive element. The through via may then be completed by laser ablation or drilling from the back surface. In another embodiment, a partial via may be formed by laser ablation or drilling from the back surface of a substrate to a predetermined distance therein. The through via may be completed from the active surface by forming a partial via extending through the conductive element and the underlying substrate to intersect the laser-drilled partial via. In another embodiment, a partial via may first be formed by laser ablation or drilling from the back surface of the substrate followed by dry etching to complete the through via.

Claims

1. A method of forming at least one through via in a semiconductor substrate, comprising:

removing at least one first portion of a semiconductor substrate to form at least one first partial via

extending from a back side of the semiconductor substrate to a location in the semiconductor substrate; and

removing at least a second portion of a semiconductor substrate to form at least one second partial via extending from the location to an active surface of the semiconductor substrate.

2. The method of claim 1, wherein removing at least one first portion of a semiconductor substrate comprises removing at least one first portion of a semiconductor substrate with at laser drilling process.

3. The method of claim 2, wherein removing at least one first portion with a laser drilling process comprises alternately removing a first part of the semiconductor substrate at a first location of the at least one first portion and a second part of the semiconductor substrate at a second location of the at least one first portion.

4. The method of claim 1, wherein removing at least a second portion of a semiconductor substrate comprises removing at least a second portion of a semiconductor substrate with a dry etching process.

5. The method of claim 1, wherein removing at least one first portion of a semiconductor substrate comprises removing at least one first portion of a semiconductor substrate to form at least one first partial via extending from a back side of the semiconductor substrate and terminating 25 μ

m or more from at least one active region in the semiconductor substrate.

6. The method of claim 1, wherein removing at least one first portion of a semiconductor substrate comprises removing at least one first portion of a semiconductor substrate to form at least one first partial via extending from a back side of the semiconductor substrate and terminating at a junction depth of at least one active region in the semiconductor substrate.

7. A method of forming at least one through via in a semiconductor substrate, comprising:

removing at least one first portion of a semiconductor substrate underlying at least one of a plurality of discrete conductive elements to form at least one first partial via extending from an active surface of the semiconductor substrate partially through the semiconductor substrate to at least a depth of at least one active region in the semiconductor substrate; and

removing at least one second portion of the semiconductor substrate to form at least one second partial via extending from a back surface of the semiconductor substrate and partially through the semiconductor substrate.

8. The method of claim 7, further comprising removing at least a portion of at least one dielectric layer formed on the active surface of the semiconductor substrate to form an aperture through the at least one dielectric layer.

9. The method of claim 7, further comprising removing at least a portion of at least one discrete conductive element of the plurality to form an aperture through the at least one discrete conductive element.

10. The method of claim 7, wherein at least one of removing at least one first portion of a semiconductor substrate and removing at least one second portion of the semiconductor substrate comprises using a laser drilling process to remove a portion of the semiconductor substrate.

11. The method of claim 10, further comprising removing at least one of debris and heat damaged material with an isotropic wet etchant after the laser drilling process.

12. The method of claim 10, further comprising smoothing an interior region of the through via with an isotropic wet etchant after the laser drilling process.

13. The method of claim 10, further comprising enlarging a diameter of the through via with an isotropic wet etchant after the laser drilling process.

14. The method of claim 10, wherein using a laser drilling process comprises using a laser drilling process effected below a temperature sufficient to cause damage to the at least one active region.

15. A method of forming at least one through via in a semiconductor substrate, comprising:

forming at least one first partial via extending from a back side of a semiconductor substrate to at least a depth of an at least one active region in a semiconductor substrate; and

forming at least one second partial via extending from the at least a depth of the at least one active region to an active surface of the semiconductor substrate.

16. The method of claim 15, wherein forming at least one first partial via comprises forming at least one first partial via with a laser drilling process.

17. The method of claim 16, wherein forming at least one first partial via with a laser drilling process comprises alternately applying a pulse of laser energy between a first location of the at least one first partial via and a second location of the at least one partial via.

18. The method of claim 16, wherein using a laser drilling process comprises using a laser drilling process so as to prevent damage to the at least one active region.

19. A semiconductor substrate having at least one through via formed therein, comprising:

a semiconductor substrate having at least one active region, an active surface including a plurality of discrete conductive elements thereon, and a back surface; and

at least one through via extending from the active surface to the back surface, wherein the at least one through via includes;

a first portion that extends from the active surface of the semiconductor substrate to at least a depth of the at least one active region; and

a second portion having a tapered cross-section that extends from the back surface of the semiconductor substrate therein.

20. The semiconductor substrate of claim 19, wherein the at least one through via further comprises an aperture formed through at least one discrete conductive element of a plurality and a dielectric layer formed over the active surface.