Interdigitated capacitor having digits of varying width

• US 8,941,974 B2
• Filed: 09/09/2011
• Issued: 01/27/2015
• Est. Priority Date: 09/09/2011
• Status: Active Grant

• Current Assignee: Xilinx, Inc. (Advanced Micro Devices, Inc.)
• Original Assignee: Xilinx, Inc. (Advanced Micro Devices, Inc.)
• Inventors: Wu, Zhaoyin D., Upadhyaya, Parag, Jiang, Xuewen
• Primary Examiner(s): Sinclair, David M
• Assistant Examiner(s): Ramaswamy, Arun
• Application Number:
  US13/229,207
• Publication Number:
  US 20130063861A1
• Time in Patent Office: 1,236 Days
• Field of Search: 361/303, 361/305, 361/306.1
• US Class Current: 361/305
• CPC Class Codes: H01L 28/86 having horizontal extensions
• CPC Class Codes: Y10T 29/43 Electric condenser making

Abstract

An interdigitated capacitor having digits of varying width is disclosed. One embodiment of a capacitor includes a first plurality of conductive digits and a second plurality of conductive digits positioned in an interlocking manner with the first plurality of conductive digits, such that an interdigitated structure is formed. The first plurality of conductive digits and the second plurality of conductive digits collectively form a set of digits, where the width of a first digit in the set of digits is non-uniform with respect to a second digit in the set of digits.

Claims

1. A capacitor comprising:

a first plurality of conductive digits;

a second plurality of conductive digits positioned in an interlocking manner with the first plurality of conductive digits such that an interdigitated structure is formed;

wherein the first plurality of conductive digits and the second plurality of conductive digits collectively form a set of digits, and wherein a width of a first digit in the set of digits is non-uniform with respect to a second digit in the set of digits; and

a first bar and a second bar coupled to the interdigitated structure wherein each of the first bar and the second bar has a feeding point at which current is injected;

wherein each digit of the first plurality of conductive digits is coupled to the first bar at a single end;

wherein each digit of the second plurality of conductive digits is coupled to the second bar at a single end;

wherein digits coupled to the first bar and positioned closest to the feeding point of the first bar have widths that are wider than a remainder of the digits coupled to the first bar;

wherein digits coupled to the second bar and positioned closest to the feeding point of the second bar have widths that are wider than a remainder of the digits coupled to the second bar; and

wherein gaps between the digits in the set of digits are substantially uniform in size.

2. The capacitor of claim 1, wherein:

the digits coupled to the first bar and positioned closest to the feeding point of the first bar have widths that are wider than digits coupled to the first bar and positioned farthest from the feeding point of the first bar; and

the digits coupled to the second bar and positioned closest to the feeding point of the second bar have widths that are wider than digits coupled to the second bar and positioned farthest from the feeding point of the second bar.

3. The capacitor of claim 1, wherein digits positioned closest to each feeding point have widths that are three to five times wider than digits positioned farthest from each feeding point of the same bar.

4. The capacitor of claim 1, wherein:

the feeding point of the first bar is located at an end of the first bar that is perpendicular to an end coupled to the first plurality of digits; and

the feeding point of the second bar is located at an end of the first bar that is perpendicular to an end coupled to the second plurality of digits.

5. The capacitor of claim 1, wherein:

for digits coupled to the first bar, the width of each digit gradually tapers from a widest width for the digit positioned closest to the feeding point of the first bar to a narrowest width for the digit positioned farthest away from the feeding point of the first bar; and

for digits coupled to the second bar, the width of each digit gradually tapers from a widest width for the digit positioned closest to the feeding point of the second bar to a narrowest width for the digit positioned farthest away from the feeding point of the second bar.

6. The capacitor of claim 1, wherein the feeding point of the first bar is located at a center of the first bar and the feeding point of the second bar is located at a center of the second.

7. The capacitor of claim 1, wherein the first plurality of conductive digits and the second plurality of conductive digits are formed from at least one of:

copper, doped polysilicon, aluminum, or titanium nitride.

8. The capacitor of claim 1, wherein the first plurality of conductive digits is formed from a first material, and the second plurality of conductive digits is formed from a second material that is different from the first material.

9. A method for forming a capacitor, the method comprising:

forming a first plurality of conductive digits;

forming a second plurality of conductive digits positioned in an interlocking manner with the first plurality of conductive digits such that an interdigitated structure is formed;

wherein the first plurality of conductive digits and the second plurality of conductive digits collectively form a set of digits, and wherein a width of a first digit in the set of digits is non-uniform with respect to a second digit in the set of digits; and

forming a first bar and a second bar coupled to the interdigitated structure wherein each of the first bar and the second bar has a feeding point at which current is infected;

wherein each digit of the first plurality of conductive digits is coupled to the first bar at a single end;

wherein each digit of the second plurality of conductive digits is coupled to the second bar at a single end;

wherein digits coupled to the first bar and positioned closest to the feeding point of the first bar have widths that are wider than a remainder of the digits coupled to the first bar;

wherein digits coupled to the second bar and positioned closest to the feeding point of the second bar have widths that are wider than a remainder of the digits coupled to the second bar; and

wherein gaps between the digits in the set of digits are substantially uniform in size.

10. The method of claim 9, wherein:

the digits coupled to the first bar and positioned closest to the feeding point of the first bar have widths that are wider than digits coupled to the first bar and positioned farthest from the feeding point of the first bar; and

the digits coupled to the second bar and positioned closest to the feeding point of the second bar have widths that are wider than digits coupled to the second bar and positioned farthest from the feeding point of the second bar.

11. The method of claim 9, wherein digits positioned closest to each feeding point have widths that are three to five times wider than digits positioned farthest away from each feeding point of the same bar.

12. The method of claim 9, wherein:

the feeding point of the first bar is located at an end of the first bar that is perpendicular to an end coupled to the first plurality of digits; and

the feeding point of the second bar is located at an end of the first bar that is perpendicular to an end coupled to the second plurality of digits.

13. The method of claim 9, wherein:

for digits coupled to the first bar, the width of each digit gradually tapers from a widest width for the digit positioned closest to the feeding point of the first bar to a narrowest width for the digit positioned farthest away from the feeding point of the first bar; and

for digits coupled to the second bar, the width of each digit gradually tapers from a widest width for the digit positioned closest to the feeding point of the second bar to a narrowest width for the digit positioned farthest away from the feeding point of the second bar.

14. The method of claim 9, wherein the feeding point of the first bar is located at a center of the first bar and the feeding point of the second bar is located at a center of the second bar.

15. A capacitor comprising:

a single interdigitated layer, wherein the single interdigitated layer comprises;

a first plurality of conductive digits; and

a second plurality of conductive digits positioned in an interlocking manner with the first plurality of conductive digits such that an interdigitated structure is formed;

wherein the first plurality of conductive digits are coupled to a first bar comprising a first electrode;

wherein the second plurality of conductive digits are coupled to a second bar comprising a second electrode;

wherein a subset of the first plurality of digits coupled to the first bar and positioned closest to the first electrode has widths that are wider than a remainder of the first plurality of digits;

wherein a subset of the second plurality of digits coupled to the second bar and positioned closest to the second electrode has widths that are wider than a remainder of the second plurality of digits; and

wherein gaps between the digits in a set of digits formed of the first plurality of conductive digits and the second plurality of conductive digits collectively are substantially uniform in size.

16. The capacitor of claim 15, wherein:

the first electrode is located at a center of the first bar; and

the second electrode is located at a center of the second bar.

17. The capacitor of claim 15, wherein:

the first electrode is located at an end of the first bar that is perpendicular to an end coupled to the first plurality of digits; and

the second electrode is located at an end of the second bar that is perpendicular to an end coupled to the second plurality of digits.