Diode with variable width metal stripes for improved protection against electrostatic discharge (ESD) current failure

• US 6,518,604 B1
• Filed: 09/21/2000
• Issued: 02/11/2003
• Est. Priority Date: 09/21/2000
• Status: Expired due to Term

• Current Assignee: Synaptics Incorporated
• Original Assignee: Conexant Systems Incorporated (Synaptics Incorporated)
• Inventors: Matloubian, Mishel, Worley, Eugene R.
• Primary Examiner(s): Flynn, Nathan J.
• Assistant Examiner(s): Mondt, Johannes P.
• Application Number:
  US09/667,364
• Time in Patent Office: 873 Days
• Field of Search: 257/46, 257/355, 257/481, 257/601, 257/653, 257/654, 257/173-4, 257/362, 257/367, 257/361, 257/653.4
• US Class Current: 257/173
• CPC Class Codes: H01L 27/0255 using diodes as protective elements
• CPC Class Codes: H01L 29/417 carrying the current to be rectified, amplified or switched
• CPC Class Codes: H01L 29/8611 Planar PN junction diodes

Abstract

A diode for improved electrostatic discharge (ESD) protection against current failure includes a plurality of elongate anode and cathode conductor stripes each having first and second end portions of different widths to reduce current densities at feeder bus tie points, thereby reducing the possibility of current failure.

Claims

1. A device, comprising:

a cathode feeder bus;

an anode feeder bus positioned opposite the cathode feeder bus;

a plurality of elongated cathode conductor stripes, each elongated cathode conductor stripe of the plurality of elongated cathode conductor stripes having a first elongate cathode end portion and a second elongate cathode end portion, the first elongate cathode end portion of each of said elongated cathode conductor stripes being connected to the cathode feeder bus, the width of the second elongate cathode end portion of each of said elongated cathode conductor stripes being narrower than the width of the first elongate cathode end portion of each of said elongated cathode conductor stripes; and

a plurality of elongated anode conductor stripes, each elongated anode conductor stripe of the plurality of elongated anode conductor stripes having a first elongate anode end portion and a second elongate anode end portion, the first elongate anode end portion of each of said elongated anode conductor stripes being connected to the anode feeder bus, the width of the second elongate anode end portion of each of said elongated anode conductor stripes being narrower than the width of the first elongate anode end portion of each of said elongated anode conductor stripes, and at least one of the elongated cathode conductor stripes and at least one of the elongated anode conductor stripes being alternately spaced with respect to each other.

2. The device of claim 1, further comprising a semiconductor substrate connected to the cathode and anode feeder buses.

3. The device of claim 2, wherein the semiconductor substrate comprises a plurality of P+ doped regions connected to at least one of the elongated anode conductor stripes.

4. The device of claim 2, wherein the semiconductor substrate comprises a plurality of N+ doped regions connected to at least one of the elongated cathode conductor stripes.

5. The device of claim 1, wherein the elongated anode and cathode conductor snipes comprise metallic stripes.

6. The device of claim 1, wherein at least one of the elongated cathode conductor stripes has a continuously tapered intermediate portion between the first elongate cathode end portion of said at least one of the elongated cathode conductor stripes and the second elongate cathode end portion of said at least one of the elongate cathode conductor stripes.

7. The device of claim 1, wherein at least one of the elongated cathode conductor stripes has a substantially intermediate portion disposed between the first elongate cathode end portion of said at least one of the elongated cathode conductor stripes aid the second elongate cathode end portion of said at least one of the elongated cathode conductor stripes, the substantially intermediate portion of said at least one of the elongated cathode conductor stripes having a width that varies between the width of the first elongate cathode end portion of said at least one of the elongated cathode conductor stripes and the width of the second elongate cathode end portion of said at least one of the elongated cathode conductor stripes.

8. The device of claim 1, wherein the width of the second elongate cathode end portion of said each elongated cathode conductor stripe is about one-half of the width of the first elongate cathode end portion of said each elongated cathode conductor stripe.

9. The device of claim 1, wherein at least one of the elongated anode conductor stripes has a substantially tapered intermediate portion intermediary to the first elongate anode end portion of said at least one of the elongated anode conductor stripes and the second elongate anode end portion of said at least one of the elongated anode conductor stripes.

10. The device of claim 1, wherein at least one of the elongated anode conductor stripes has an intermediate portion disposed between the first elongate anode end portion of said at least one of the elongated anode conductor stripes and the second elongate anode end portion of said at least one of the elongated anode conductor stripes, the intermediate portion of said at least one of the elongated anode conductor stripes having a width that varies abruptly between the width of the first elongate anode end portion of said at least one of the elongated anode conductor stripes and the width of the second elongate anode end portion of said at least one of the elongated anode conductor stripes.

11. The device of claim 1, wherein the width of the second elongate anode end portion of each of said elongated anode conductor stripes is about one-half of the width of the first elongate anode end portion of each of said elongated anode conductor stripes.

18. The device of claim 1, wherein each of said elongated anode conductor stripes has an intermediate portion disposed between the first elongate anode end portion of each of said elongated anode conductor stripes and the second elongate anode end portion of each of said elongated anode conductor stripes, the intermediate portion of each of said elongated anode conductor stripes having a width that varies abruptly between the width of the first elongate anode end portion of each of said elongated anode conductor stripes and the width of the second elongate anode end portion of each of said elongated anode conductor stripes.

19. The device of claim 1, wherein each of said elongated cathode conductor stripes has an intermediate portion disposed between the first elongate cathode end portion of each of said elongated cathode conductor stripes and the second elongate cathode end portion of each of said elongated cathode conductor stripes, the intermediate portion of each of said elongated cathode conductor stripes having a width that varies abruptly between the width of the first elongate cathode end portion of each of said elongated cathode conductor stripes and the width of the second elongate cathode end portion of each of said elongated cathode conductor stripes.

12. A device, comprising:

a semiconductor substrate;

a plurality of elongate P+ doped regions in the semiconductor substrate;

a plurality of elongate N+ doped regions in the semiconductor substrate, the P+ and N+ doped regions alternately spaced from each other;

a cathode feeder bus on the semiconductor substrate;

an anode feeder bus on the semiconductor substrate, the anode feeder bus positioned opposite the cathode feeder bus;

a plurality of elongated cathode conductor stripes disposed on the N+ doped regions respectively, each elongated cathode conductor stripe of the plurality of elongated cathode conductor stripes having a first elongate cathode end portion and a second elongate cathode end portion, the first elongate cathode end portion of each of said elongated cathode conductor stripes being connected to the cathode feeder bus, the width of the second elongate cathode end portion of each of said elongated cathode conductor stripes being narrower than the width of the first elongate cathode end portion of each of said elongated cathode conductor stripes; and

a plurality of elongated anode conductor stripes disposed on the P+ doped regions respectively, each elongated anode conductor stripe of the plurality of elongated anode conductor stripes having a first elongate anode end portion and a second elongate anode end portion, the first elongate anode end portion of said each elongated anode conductor stripe being connected to the anode feeder bus, the width of the second elongate anode end portion of said each elongated anode conductor stripe being narrower than the width of the first elongate anode end portion of said each elongated anode conductor stripe, the elongated cathode conductor stripes and the elongated anode conductor stripes alternately spaced from each other.

13. The device of claim 12, wherein the elongated anode and cathode conductor stripes comprise metallic stripes.

14. The device of claim 12, wherein each of said elongated cathode conductor stripes has a continuously tapered intermediate portion between the first elongate cathode end portion of each of said elongated cathode conductor stripes and the second elongate cathode end portion of each of said elongated cathode conductor stripes.

15. The device of claim 12, wherein each of said elongated cathode conductor stripes bas an intermediate portion disposed between the first elongate cathode end portion of each of said elongated cathode conductor stripes and the second elongate cathode end portion of each of said elongated cathode conductor stripes, the intermediate portion of each of said elongated cathode conductor stripes having a width that varies abruptly between the width of the first elongate cathode end portion of each of said elongated cathode conductor stripes and the width of the second elongate cathode end portion of each of said elongated cathode conductor stripes.

16. The device of claim 12, wherein the width of the second elongate cathode end portion of each of said elongated cathode conductor stripes is about one-half of the width of the first elongate cathode end portion of each of said elongated cathode conductor stripes.

17. The device of claim 12, wherein said each anode conductor stripe has a continuously tapered intermediate portion between the first elongate anode end portion of each of said elongated anode conductor stripes and the second elongate anode end portion of each of said elongated anode conductor stripes.

20. A device, comprising:

a substrate;

a cathode feeder bus disposed on the substrate;

an anode feeder bus disposed on the substrate opposite the cathode feeder bus;

a plurality of elongated cathode conductor stripes, each of said elongated cathode conductor stripe comprising a first end portion, a second end portion, and an intermediate portion disposed between the first end portion of each of said elongated cathode conductor stripe and the second end portion of each of said elongated cathode conductor stripe, the first end portion of each of said elongated cathode conductor stripe being connected to the cathode feeder bus, the width of the second end portion of each of said elongated cathode conductor stripe being narrower than the width of the first end portion of each of said elongated cathode conductor stripe, the width of the intermediate portion of each of said elongated cathode conductor stripe varying between the width of the first end portion of each of said elongated cathode conductor stripe and the width of the second end portion of each of said elongated cathode conductor stripe in a continuous but non-differentiable manner at the locations at which the intermediate portion of each of said elongated cathode conductor stripe is joined to tie first end portion of each of said elongated cathode conductor stripe and to the second end portion of each of said elongated cathode conductor stripe; and

a plurality of elongated anode conductor stripes, each of said elongated anode conductor stripe comprising a first end portion, a second end portion, and an intermediate portion disposed between the first end portion of each of said elongated anode conductor stripe and the second end portion of each of said elongated anode conductor stripe, the first end portion of each of said elongated anode conductor stripe being connected to the anode feeder bus, the width of the second end portion of each of said elongated anode conductor stripe being narrower than the width of the first end portion of each of said elongated anode conductor stripes the width of the intermediate portion of each of said elongated anode conductor stripes varying between the width of the first end portion of each of said elongated anode conductor stripes and the width of the second end portion of each of said elongated anode conductor stripe in a continuous but non-differentiable manner at the locations at which the intermediate portion of each of said elongated anode conductor stripes is joined to the first end portion of each of said elongated anode conductor stripes and to the second end portion of each of said elongated anode conductor stripes, the elongated conductor stripes and the elongated anode conductor stripes being interdigitated with respect to each other.