Integrated circuit structure incorporating an inductor, a conductive sheet and a protection circuit

• US 7,750,408 B2
• Filed: 03/29/2007
• Issued: 07/06/2010
• Est. Priority Date: 03/29/2007
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: He, Zhong-Xiang, Voldman, Steven H., Rassel, Robert M.
• Primary Examiner(s): Smith; Bradley K
• Assistant Examiner(s): KARIMY, TIMOR
• Application Number:
  US11/692,948
• Publication Number:
  US 20080237789A1
• Time in Patent Office: 1,195 Days
• Field of Search: 257/355, 257/356, 257/173, 257/E23.114, 257/531, 257/277, 257/E21.022
• US Class Current: 257/355
• CPC Class Codes: G06F 30/36 Circuit design at the analogue level
• CPC Class Codes: H01L 23/5227 Inductive arrangements or effects of, or between, wiring layers other inductive arrangements H01L23/645
• CPC Class Codes: H01L 28/10 Inductors
• 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
• CPC Class Codes: H01L 2924/3011 Impedance

Abstract

Disclosed are embodiments of a circuit (e.g., an electrostatic discharge (ESD) circuit), a design methodology and a design system. In the circuit, an ESD device is wired to a first metal level (e.g., M1). An inductor is formed in a second metal level (e.g., M5) above the first metal level and is aligned over and electrically connected in parallel to the ESD device by a single vertical via stack. The inductor is configured to nullify, for a given application frequency, the capacitance value of the ESD device. The quality factor of the inductor is optimized by providing, on a third metal level (e.g., M3) between the second metal level and the first metal level, a shield to minimize inductive coupling. An opening in the shield allows the via stack to pass through, trading off Q factor reduction for size-scaling and ESD robustness improvements.

Claims

1. An integrated circuit structure comprising:

a substrate;

a first metal level above said substrate;

a functional circuit in said substrate;

a second metal level above and parallel to said first metal level;

an inductor in said second metal level, wherein said inductor comprises a planar conductive coil having a first end at a center of said coil and wherein said coil comprises a metal wire with a predetermined minimum width capable of sustaining a specified electrostatic discharge current density without failure;

a third metal level between and parallel to said first metal level and said second metal level, wherein said third metal level comprises a conductive shield positioned between said substrate and said inductor, wherein said conductive shield comprises an essentially planar sheet of conductive material larger in area than said inductor and further extending laterally beyond all sides of said inductor, wherein said conductive shield is electrically isolated from both said substrate and said inductor by dielectric material and wherein said conductive shield comprises a dielectric-filled opening aligned below said first end; and

a conductor extending vertically through said dielectric-filled opening from said first end to one of said first metal level and said substrate such that said conductor is perpendicular to said inductor and does not contact said conductive shield and such that said inductor is electrically connected to said functional circuit and provides electrostatic discharge protection to said functional circuit.

2. The structure of claim 1, said conductive shield comprising additional dielectric-filled openings so as to minimize inductive coupling.

3. The structure of claim 1, wherein said conductor comprises a via stack.

4. The structure of claim 1, further comprising and input/output pad,

wherein said first end of said coil is further electrically connected to said input/pad and to a negative supply voltage, and

wherein a second end of said coil is electrically connected to a positive supply voltage.

5. The circuit of claim 1, further comprising an electrostatic discharge device in said substrate, wherein said inductor and said electrostatic discharge device are electrically connected via said conductor and comprise a parallel inductor-capacitor (LC) circuit.

6. An integrated circuit structure comprising:

a substrate;

a first metal level above said substrate;

an electrostatic discharge device in said substrate;

a second metal level above and parallel to said first metal level;

an inductor in said second metal level over and substantially parallel to said electrostatic discharge device, wherein said inductor comprises a planar conductive coil having a first end at a center of said coil;

a third metal level between and parallel to said first metal level and said second metal level, wherein said third metal level comprises a conductive shield positioned between said electrostatic discharge device and said inductor, wherein said conductive shield comprises an essentially planar sheet of conductive material larger in area than said inductor and further extending laterally beyond all sides of said inductor, wherein said conductive shield is electrically isolated from both said substrate and said inductor by dielectric material and wherein said conductive shield comprises a dielectric-filled opening aligned below said first end; and

a conductor extending vertically through said dielectric-filled opening from said first end to one of said first metal level and said substrate such that said conductor is perpendicular to said inductor and does not contact said conductive shield and such that said inductor and said electrostatic discharge device are electrically connected and comprise a parallel inductor-capacitor (LC) circuit.

7. The structure of claim 6, wherein said coil comprises a metal wire with a predetermined minimum width capable of sustaining a specified electrostatic discharge current density without failure.

8. The structure of claim 6, said conductive shield comprising additional dielectric-filled openings so as to minimize inductive coupling.

9. The structure of claim 6, wherein said conductor comprises a via stack.

10. The structure of claim 6, wherein said inductor has an inductance value that is predetermined based on a capacitance value of said electrostatic discharge device and on a specified application frequency to ensure that said inductor-capacitor circuit has a resonant frequency at said specified application frequency.

11. The structure of claim 6, wherein said inductor has an inductance value that is approximately equal to one over a product of a capacitance value of said electrostatic discharge device and a specified application frequency squared.

12. The structure of claim 6, further comprising an input/output pad,

wherein said first end of said coil and said electrostatic discharge device are further electrically connected to said input/pad,

wherein a second end of said coil is electrically connected to ground, and

wherein said electrostatic discharge device is further electrically connected said to a positive supply voltage.

13. The structure of claim 6, further comprising an input/output pad,

wherein said first end of said coil is further electrically connected to said input/pad,

wherein a second end of said coil is electrically connected to a positive supply voltage, and

wherein said electrostatic discharge device is further electrically connected to said input/output pad and to ground.

14. An integrated circuit structure comprising:

an input/output pad;

a first supply voltage;

a second supply voltage different from said first supply voltage

a substrate;

a first metal level above said substrate;

an electrostatic discharge device in said substrate and electrically connected to said first supply voltage;

a functional circuit for a radio frequency application in said substrate;

a second metal level above and parallel to said first metal level;

an inductor in said second metal level over and substantially parallel to said electrostatic discharge device, wherein said inductor comprises a planar conductive coil having a first end and a second end, wherein said first end is positioned at a center of said coil and is electrically connected to said input/output pad, to said electrostatic discharge device and to said functional circuit, and wherein said second end is connected to said second supply voltage;

a third metal level between and parallel to said first metal level and said second metal level, wherein said third metal level comprises a conductive shield positioned between said electrostatic discharge device and said inductor, wherein said conductive shield comprises an essentially planar sheet of conductive material larger in area than said inductor and extending laterally beyond all sides of said inductor, wherein said conductive shield is electrically isolated from both said substrate and said inductor by dielectric material and wherein said conductive shield comprises a dielectric-filled opening aligned below said first end; and

a conductor extending vertically through said dielectric-filled opening from said first end to one of said first metal level and said substrate such that said conductor is perpendicular to said inductor and does not contact said conductive shield and such that said inductor and said electrostatic discharge device are electrically connected and comprise a parallel inductor-capacitor (LC) circuit.

15. The structure of claim 14, wherein said coil comprises a metal wire with a predetermined minimum width capable of sustaining a specified electrostatic discharge current density without failure.

16. The structure of claim 14, said conductive shield comprising additional dielectric-filled openings so as to minimize inductive coupling.

17. The structure of claim 14, wherein said conductor comprises a via stack.

18. The structure of claim 14, wherein said inductor has an inductance value that is predetermined based on a capacitance value of said electrostatic discharge device and on a specified application frequency to ensure that said inductor-capacitor circuit has a resonant frequency at said specified application frequency.

19. The structure of claim 14, wherein said inductor has an inductance value that is approximately equal to one over a product of a capacitance value of said electrostatic discharge device and a specified application frequency squared.

20. The structure of claim 14, wherein said first supply voltage comprise a positive supply voltage and said second supply voltage comprises a negative supply voltage.

21. The structure of claim 14, wherein said first supply voltage comprise a negative supply voltage and said second supply voltage comprises a positive supply voltage.