Stacked metal inductor
An inductor has a conductor layer formed by multiple concentric co-planar turns of a first metal layer (e.g., ultra-thick metal (UTM)) adapted to receive current at a frequency of at least one gigahertz. The multiple turns of the first metal layer proceed from an innermost turn to an outermost turn, and a stacking layer of a second metal is provided over each of the first metal layer turns except at least the innermost turn, thereby optimizing the Q of the inductor.
1. An inductor, comprising:
a conductor layer including a plurality of concentric co-planar turns of a first metal layer adapted to receive current at a frequency of at least one gigahertz, the plurality of concentric co-planar turns of the first metal layer proceeding from an innermost turn to an outermost turn; and
a second metal layer formed directly over and making electrical contact with each of the first metal layer turns except (i) at least the innermost first metal layer turn, and (ii) at one or more crossovers between each of the plurality of turns of the first metal layer,
wherein the second metal layer has a higher resistance than the first metal layer.
2. The inductor of claim 1 , wherein the first metal layer comprises an ultra-thick metal (UTM) layer.
3. The inductor as claimed in claim 2 , wherein the UTM comprises copper.
4. The inductor as claimed in claim 1 , wherein the second metal layer is formed directly over all of the first metal layer turns except for the innermost first metal layer turn and a next-to-innermost first metal layer turn.
5. The inductor as claimed in claim 1 , wherein only the outermost first metal layer turn has the second metal layer thereon.
6. The inductor as claimed in claim 1 , wherein the plurality of concentric co-planar turns of the first metal layer are octagonal in shape.
7. The inductor as claimed in claim 1 , wherein the plurality of concentric co-planar turns is four first metal layer turns, with the second metal layer being over each of the first metal layer turns except the innermost turn of the four first metal layer turns.
8. The inductor as claimed in claim 1 , wherein the plurality of concentric co-planar turns is three first metal layer turns, with the second metal layer over each of the first metal layer turns except the innermost turn of the three first metal layer turns.
9. The inductor as claimed in claim 1 , wherein the plurality of concentric co-planar turns is three first metal layer turns, with the second metal layer over each of the first metal layer turns except the innermost turn of the three first metal layer turns and a next-to-innermost turn of the three first metal layer turns.
10. An inductor comprising:
a conductor layer comprising at least three concentric co-planar turns of a first metal layer adapted to receive current at a frequency of at least one gigahertz, the at least three turns of the first metal layer proceeding from an innermost turn to an outermost turn; and
a second metal layer formed directly over and making electrical contact with all of the first metal layer turns except (i) the innermost first metal layer turn, (ii) a next-to-innermost first metal layer turn, and (iii) at one or more crossovers between each of the at least three concentric co-planar turns of the first metal layer,
wherein the second metal layer has a higher resistance than the first metal layer.
11. The inductor as claimed in claim 10 , wherein the first metal layer turns and the second metal layer turns form an octagonal shape.
12. The inductor as claimed in claim 10 , wherein the first metal layer comprises a copper ultra-thick metal (UTM) layer.
13. A method for manufacturing an inductor, comprising:
forming a conductor layer having a plurality of concentric co-planar turns of a first metal layer adapted to receive current at a frequency of at least one gigahertz, the plurality of turns of the first metal layer proceeding from an innermost turn to an outermost turn; and
forming a second metal layer directly over the first metal layer to make electrical contact with each of the first metal layer turns except (i) at least the innermost first metal layer turn, and (ii) at one or more crossovers between each of the plurality of concentric co-planar turns of the first metal layer,
wherein the second metal layer has a higher resistance than the first metal layer.
14. The method as claimed in claim 13 , further comprising:
providing the second metal layer over each of the first metal layer turns except the innermost first metal layer turn and a next-to innermost first metal layer turn.
15. The method as claimed in claim 13 , further comprising:
providing only the outermost first metal layer turn with the second metal layer thereon.
16. The method as claimed in claim 13 , further comprising:
forming the first metal layer turns and the second metal layer turns as an octagonal shape.
17. The method as claimed in claim 13 , further comprising:
using a copper ultra-thick metal (UTM) layer as the first metal layer.
18. The method as claimed in claim 13 , further comprising:
forming four of the first metal layer turns, with the second metal layer formed over each of the first metal layer turns except the innermost turn of the four first metal layer turns.
19. The method as claimed in claim 13 , further comprising:
forming three of the first metal layer turns, with the second metal layer formed over each of the first metal layer turns except the innermost turn of the three first metal layer turns.
20. The method as claimed in claim 13 , further comprising:
forming three of the first metal layer turns, with the second metal layer formed over each of the first metal layer turns except the innermost of the three first metal layer turns and a next-to-innermost turn of the three first metal layer turns.