RF POWER TRANSISTOR DEVICE WITH METAL ELECTROMIGRATION DESIGN AND METHOD THEREOF

Abstract

An RF power transistor with a metal design (70) comprises a drain pad (72) and a plurality of metal drain fingers (74) extending from the drain pad, wherein at least one metal drain finger comprises one or more sections of metal (74-1, 74-2, 100-1, 100-2, 100-3), each section of metal including of one or more branch (54-1, 54-2, 116-1, 116-2, 116-11, 116-21, 116-41) of metal having a metal width maintained within a bamboo regime.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is illustrated by way of example and not limited by the accompanying figures, in which like references indicate similar elements, and in which:

FIG. 1 is a top down diagram view of a portion of a top metal design for an RF MOSFET known in the art;

FIG. 2 is a cross-section view of the top metal design of FIG. 1, taken along line 2-2;

FIG. 3 is a top down diagram view of a portion of a metal design for an RF power transistor having drain metal finger branch widths within the Bamboo regime according to an embodiment of the present disclosure;

FIG. 4 is a cross-section view of the metal design of FIG. 3, taken along line 4-4;

FIG. 5 is a top down diagram view of a portion of a metal design for an RF power transistor having drain metal finger branch widths within the Bamboo regime according to one embodiment of the present disclosure;

FIG. 6 is an enlarged view of a portion of the top down diagram view of FIG. 5 to illustrate greater detail of the drain metal finger branches; and

FIG. 7 is a top down diagram view of a single finger of a metal design for an RF power transistor having drain metal finger branch widths within the Bamboo regime according to another embodiment of the present disclosure.

Claims

1. An RF power transistor with a metal design comprising: a drain pad; anda plurality of metal drain fingers extending from the drain pad, wherein at least one metal drain finger comprises one or more sections of metal, each section of metal including one or more branch of metal having a metal width maintained within a bamboo regime.

2. The RF power transistor of claim 1, wherein the metal width for the bamboo regime comprises a width that is smaller than an average grain size of the metal of the drain finger.

3. The RF power transistor of claim 1, wherein the at least one metal drain finger comprises a first section of metal and a second section of metal, the first section of metal being distal from the drain pad and the second section being proximate the drain pad.

4. The RF power transistor of claim 3, further wherein the first section of metal comprises a single branch of metal and the second section of metal comprises two parallel branches of metal.

5. The RF power transistor of claim 1, wherein the metal drain finger comprises a number of sections of metal, each section of metal including one or more branch of metal having a metal width maintained within the bamboo regime and wherein for any two succeeding sections, a distal section of the two contains at least one less branch than a proximate section of the two.

6. The RF power transistor of claim 5, further wherein the metal drain finger comprises three sections of metal, a first section having one branch and being coupled to a second section having two parallel branches, the second section further being coupled a third section having three parallel branches.

7. The RF power transistor of claim 6, still further wherein the first section is distal from the drain pad and the third section is proximate the drain pad.

8. The RF power transistor of claim 1, wherein the metal drain fingers comprise a top metal.

9. An RF power transistor with a metal design comprising: a drain pad; anda plurality of metal drain fingers extending from the drain pad, wherein each metal drain finger comprises one or more sections of metal, each section of metal including of one or more branch of metal having a metal width maintained within a bamboo regime, wherein the metal width for the bamboo regime comprises a width that is smaller than an average grain size of the metal of the drain finger.

10. The RF power transistor of claim 9, wherein the metal drain finger comprises a first section of metal and a second section of metal, the first section of metal being distal from the drain pad and the second section being proximate the drain pad.

11. The RF power transistor of claim 10, further wherein the first section of metal comprises a single branch of metal and the second section of metal comprises two parallel branches of metal.

12. The RF MOSFET of claim 9, wherein the metal drain finger comprises a number of sections of metal, each section of metal including one or more branch of metal having a metal width maintained within the bamboo regime and wherein for any two succeeding sections, a distal section of the two contains at least one less branch than a proximate section of the two.

13. The RF power transistor of claim 9, further wherein the metal drain finger comprises three sections of metal, a first section having one branch and being coupled to a second section having two parallel branches, the second section further being coupled a third section having three parallel branches.

14. The RF power transistor of claim 13, still further wherein the first section is distal from the drain pad and the third section is proximate the drain pad.

15. A method of making an RF power transistor with a metal design comprising: providing a drain pad; andextending a plurality of metal drain fingers from the drain pad, wherein at least one metal drain finger comprises one or more sections of metal, each section of metal including one or more branch of metal having a metal width maintained within a bamboo regime.

16. The method of claim 15, wherein the metal width for the bamboo regime comprises a width that is smaller than an average grain size of the metal of the drain finger.

17. The method of claim 15, wherein extending includes extending at least one metal drain finger that includes a first section of metal and a second section of metal, the first section of metal being distal from the drain pad and the second section being proximate the drain pad.

18. The method of claim 17, further wherein the first section of metal includes a single branch of metal and the second section of metal includes two parallel branches of metal.

19. The method of claim 15, wherein extending the metal drain finger comprises extending a number of sections of metal, each section of metal including one or more branch of metal having a metal width maintained within the bamboo regime and wherein for any two succeeding sections, a distal section of the two contains at least one less branch than a proximate section of the two.

20. The method of claim 19, further wherein extending the metal drain finger comprises extending three sections of metal, a first section having one branch and being coupled to a second section having two parallel branches, the second section further being coupled a third section having three parallel branches, still further wherein the first section is distal from the drain pad and the third section is proximate the drain pad.