Interconnect bus crossover for MEMS

• US 6,727,436 B2
• Filed: 03/15/2002
• Issued: 04/27/2004
• Est. Priority Date: 03/15/2002
• Status: Expired due to Term

• Current Assignee: NeoPhotonics Corporation (Lumentum Holdings Inc.)
• Original Assignee: MEMX, Inc. (Lumentum Holdings Inc.)
• Inventors: Barnes, Stephen Matthew, Rodgers, Murray Steven
• Primary Examiner(s): Pert, Evan
• Assistant Examiner(s): Alcala, Jose H.
• Application Number:
  US10/098,886
• Publication Number:
  US 20030173112A1
• Time in Patent Office: 774 Days
• Field of Search: 174/254, 174/255, 174/261, 174/264, 174/68.2, 174/268, 361/752, 361/800, 361/772-775, 361/816
• US Class Current: 174/255
• CPC Class Codes: B81B 7/0006 Interconnects
• CPC Class Codes: H01L 23/5225 Shielding layers formed together with wiring layers
• 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 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00

Abstract

A shielded interconnect bus crossover useful in interconnecting MEM devices with control signal sources or the like and a method of fabricating such a shielded interconnect bus crossover are disclosed. In one embodiment, a shielded interconnect bus crossover (10) includes a plurality of base pads (44A-C) and a plurality of support columns (74) extending upward from the base pads (44A-C) through holes formed in an interconnect bus shield (78) overlying a plurality of interconnect bus lines (42). The support columns (74) support a two layer elevated crossing line (92/112) in a spaced relation above the interconnect bus shield (78). The two layer elevated crossing line (92/112) is oriented transverse to the direction of the interconnect bus lines (42) and is located within the perimeter of a two layer rectangular crossing line shield wall (96/116).

Claims

1. A shielded interconnect bus crossover comprising:

a substrate;

first, second, and third layers of electrically conductive material overlying and supported by at least a portion of said substrate;

an interconnect bus patterned from said first and second layers of electrically conductive material, said interconnect bus including a plurality of interconnect bus lines, a plurality of interconnect bus shield walls, and an interconnect bus shield supported in a spaced relation above said interconnect bus lines by said interconnect bus shield walls;

a plurality of base pads patterned from said first layer of electrically conductive material, said base pads being located at locations within the footprint of said interconnect bus along an imaginary line extending transverse to an orientation of said interconnect bus lines, at least one of said base pads being in contact with at least one of said interconnect bus lines;

a plurality of support columns patterned from said second layer of electrically conductive material, said support columns overlying said base pads and extending vertically upward through holes formed in said interconnect bus shield; and

at least one elevated crossing line patterned from said third layer of electrically conductive material, said elevated crossing line being supported in a spaced relation above said interconnect bus shield by said support columns.

2. The shielded interconnect bus crossover of claim 1 wherein said first, second, and third layers of electrically conductive material comprise doped polysilicon.

3. The shielded interconnect bus crossover of claim 2 wherein said second layer of electrically conductive material comprises two separately deposited layers of doped polysilicon.

4. The shielded interconnect bus crossover of claim 1 further comprising:

first, second, and third layers of dielectric material deposited over and supported by at least a portion of said substrate;

said first layer of dielectric material being disposed between said interconnect bus lines and said substrate;

said second layer of dielectric material being disposed between said interconnect bus shield and said interconnect bus lines; and

said third layer of dielectric material being disposed between said elevated crossing line and said interconnect bus shield.

5. The shielded interconnect bus of claim 4 wherein said second and third layers of dielectric material comprise one of silicon dioxide and silicate glass.

6. The shielded interconnect bus of claim 4 wherein said substrate is comprised of silicon and said first dielectric layer comprises a lower layer of thermal oxide and an upper layer of silicon nitride.

7. The shielded interconnect bus crossover of claim 1 further comprising:

a fourth layer of electrically conductive material overlying and supported by at least a portion of said substrate; and

at least one elevated crossing line patterned from said fourth layer of electrically conductive material to overlie said elevated crossing line patterned from said third layer of electrically conductive material, said elevated crossing lines patterned from said third and fourth layers of electrically conductive material together comprising a two layer elevated crossing line.

8. The shielded interconnect bus crossover of claim 7 wherein said fourth layer of electrically conductive material comprises doped polysilicon.

9. The shielded interconnect bus crossover of claim 7 further comprising:

at least one crossing line shield wall patterned from said third layer of electrically conductive material; and

at least one crossing line shield wall patterned from said fourth layer of electrically conductive material to overlie said crossing line shield wall patterned from said third layer of electrically conductive material, said crossing line shield walls patterned from said third and fourth layers of electrically conductive material together defining an enclosed area, said two layer elevated crossing line being located within said enclosed area defined by said crossing line shield walls patterned from said third and fourth layers of electrically conductive material.

10. The shielded interconnect bus crossover of claim 9 further comprising:

a fifth layer of electrically conductive material overlying and supported by at least a portion of said substrate; and

a shield patterned from said fifth layer of electrically conductive material, said shield overlying said enclosed area defined by said crossing line shield walls patterned from said third and fourth layers of electrically conductive material and being positioned in a spaced relation above said two layer elevated crossing line.

11. The shielded interconnect bus crossover of claim 10 wherein said fifth layer of electrically conductive material comprises doped polysilicon.

12. The shielded interconnect bus crossover of claim 1 further comprising:

at least one crossing line shield wall patterned from said third layer of electrically conductive material, said crossing line shield wall defining an enclosed area, said elevated crossing line being located within said enclosed area defined by said crossing line shield wall.

13. The shielded interconnect bus crossover of claim 12 further comprising:

a fourth layer of electrically conductive material overlying and supported by at least a portion of said substrate; and

a shield patterned from said fourth layer of electrically conductive material, said shield overlying said enclosed area defined by said crossing line shield wall patterned from said third layer of electrically conductive material and being positioned in a spaced relation above said elevated crossing line patterned from said third layer of electrically conductive material.

14. The shielded interconnect bus crossover of claim 13 wherein said fourth layer of electrically conductive material comprises doped polysilicon.

15. A method for making a shielded interconnect bus crossover that crosses at least one interconnect bus line of an interconnect bus over other interconnect lines of the interconnect bus, said method comprising the steps of:

depositing a first layer of electrically conductive material above at least a portion of a substrate;

forming a plurality of base pads from the first layer of electrically conductive material, wherein the base pads are formed at various locations within the footprint of the interconnect bus along an imaginary line extending transverse to an orientation of the interconnect bus lines with at least one of the base pads contacting at least one of the interconnect bus lines;

depositing a second layer of electrically conductive material above the first layer of electrically conductive material;

forming a plurality of support columns from the second layer of electrically conductive material, wherein the support columns are formed to overlie the base pads and extend vertically upward therefrom through holes formed in the interconnect bus shield;

depositing a third layer of electrically conductive material above the second layer of electrically conductive material; and

forming at least one elevated crossing line from the third layer of electrically conductive material, wherein the elevated crossing line is formed to be supported in a spaced relation above the interconnect bus shield by the support columns.

16. The method of claim 15 wherein in said steps of depositing first, second, and third layers of electrically conductive material, the electrically conductive material comprises doped polysilicon.

17. The method of claim 15 wherein said step of depositing a second layer of electrically conductive material comprises the steps of:

depositing a lower layer of doped polysilicon;

depositing an intervening layer of sacrificial material;

removing the intervening layer of sacrificial material; and

depositing an upper layer of doped polysilicon.

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

depositing a fourth layer of electrically conductive material above the third layer of electrically conductive material; and

forming at least one elevated crossing line from the fourth layer of electrically conductive material, wherein the elevated crossing line formed from the fourth layer of electrically conductive material is formed to overlie the elevated crossing line formed from the third layer of electrically conductive material such that the elevated crossing lines formed from the third and fourth layers of electrically conductive material together form a two layer elevated crossing line.

19. The method claim 18 further comprising the steps of:

forming at least one crossing line shield wall from the third layer of electrically conductive material; and

forming at least one crossing line shield wall from the fourth layer of electrically conductive material, wherein the crossing line shield wall formed from the fourth layer of electrically conductive material is formed to overlie the crossing line shield wall formed from the third layer of electrically conductive material such that the crossing line shield walls formed from the third and fourth layers of electrically conductive material together define an enclosed area within which the two layer elevated crossing line is located.

20. The method of claim 19 wherein in said steps of depositing first, second, third, and fourth layers of electrically conductive material, the first, second, third, and fourth layers of electrically conductive material comprise doped polysilicon.

21. The method of claim 19 further comprising the step of:

depositing a fifth layer of electrically conductive material above the fourth layer of electrically conductive material; and

forming a shield from the fifth layer of electrically conductive material, wherein the shield is formed to overlie the enclosed area defined by the crossing line shield walls formed from the third and fourth layers of electrically conductive material and be positioned in a spaced relation above the two layer elevated crossing line.

22. The method of claim 21 wherein in said step of depositing a fifth layer of electrically conductive material, the fifth layer of electrically conductive material comprises doped polysilicon.

23. The method claim 15 further comprising the step of:

forming at least one crossing line shield wall from the third layer of electrically conductive material, wherein the crossing line shield wall is formed to define an enclosed area within which the elevated crossing line is located.

24. The method claim 23 further comprising the step of:

depositing a fourth layer of electrically conductive material above the third layer of electrically conductive material; and

forming a shield from the fourth layer of electrically conductive material, the shield being formed to overlie the enclosed area defined by the crossing line shield wall formed from the third layer of electrically conductive material and to be positioned in a spaced relation above the elevated crossing line formed from the third layer of electrically conductive material.

25. The method of claim 24 wherein in said step of depositing a fourth layer of electrically conductive material, the fourth layer of electrically conductive material comprises doped polysilicon.