Patent Application
20050156704
Embodiments of the present invention may relate to transformers and inductors. More particularly, embodiments of the present invention may relate to transformers and inductors that may be integrated on a die.
Transformers may be used in many different types of power distribution systems, such as in voltage (or power) converters. Power converters may not be fully integrated on-chip for a variety of reasons. For example, power converters may be designed at 0.1 to 10 MHz operating frequencies. On-chip inductors may not be used because the amount of inductance needed for a circuit such as a Buck converter at these frequencies is large. Additionally, the physical size of inductors may be too large with certain magnetic materials. Still further, in high-frequency inductors, magnetic materials may not be used because their frequency range has been limited to less than 100 MHz.
There are advantages to integrating a power distribution system on the same die as the circuits that are powered by the power distribution system. For example, as processor technology scales to smaller dimensions, supply voltages to circuits within a processor may also scale to smaller values. But for many processors, power consumption has also been increasing as technology progresses. Using an off-die voltage converter to provide a small supply voltage to a processor with a large power consumption may lead to a large total electrical current being supplied to the processor. This may increase the electrical current per pin, or the total number of pins needed. Also, an increase in supply current may lead to an increase in resistivity as well as inductive voltage drop across various off-die and on-die interconnects, and to a higher cost for decoupling capacitors. Integrating the voltage (or power) converter onto the die may mitigate these problems.
The foregoing and a better understanding of the present invention will become apparent from the following detailed description of arrangements and example embodiments (and the claims) when read in connection with the accompanying drawings, all forming a part of the disclosure of this invention. While the foregoing and following written and illustrated disclosure focuses on disclosing arrangements and example embodiments of the invention, it should be clearly understood that the same is by way of illustration and example only and the invention is not limited thereto.
The following represents brief descriptions of the drawings in which like reference numerals represent like elements and wherein:
In the following detailed description, like reference numerals and characters may be used to designate identical, corresponding or similar components in differing figure drawings. Further, in the detailed description to follow, example sizes/models/values/ranges may be given although the present invention is not limited to the same. Where specific details are set forth in order to describe example embodiments of the invention, it should be apparent to one skilled in the art that the invention can be practiced without these specific details.
As will be described below, embodiments of the present invention may provide a transformer (or power converter) that includes magnetic material about a plurality of metal lines. The magnetic material may include a structure to reduce Eddy currents flowing in the surrounding magnetic material. This structure may be a plurality of slots extending perpendicular to the metal lines. The slots may create gaps that may be filled with an insulation material to prevent current from flowing, and thereby reducing the Eddy current. The structure may also be a laminated magnetic structure that includes thinner layers such that it is harder for electrons to flow (i.e., a higher resistance). This higher resistance may result in less Eddy current.
A power supply 70 may provide an input supply voltage to the on-die power distribution unit 16 via a power bus 75. The power supply 70 may provide power to other modules, but for ease of illustration such connections are not shown in
For a transformer to be small enough to be integrated on a die, its operating frequency for example, the frequency of a controller needs to be sufficiently high. Additionally, magnetic material suitable for high frequency operation may be used to increase coupling between windings of the transformer. The magnetic material may be one of amorphous CoZrTa, CoFeHfO, CoAlO, FeSiO, CoFeAlO, CoNbTa, CoZr, and other amorphous cobalt alloys, for example. An amorphous alloy may include various atomic percentages of its constituent elements. For example, the amorphous cobalt alloy CoZrTa may have 4% Zr, 4.5% Ta, with the remainder being Co. For CoZrTa, the range for Zr may be from 3% to 12% and the range for Ta may be from 0% to 10%. The cobalt alloy CoFeHfO may have 19% Fe, 14% Hf, and 22% O, or the Cobalt alloy CoFeAlO may have 51% Co, 22% Fe, and 27% Al. These values are merely examples as other examples and values are also possible. The use of such magnetic material may allow for operating frequencies of 10 MHz to 1 GHz, and higher. Other magnetic materials may also be used.
The insulating material 130 deposited around the metal lines 110, and in any end gap in the magnetic material 120 if present, may have a smaller magnetic permeability than that of the magnetic material 120. Otherwise, the magnetic coupling between the metal lines 110 may degrade. For example, the relative permeability of the magnetic material 120 may be greater than 100 and the relative permeability of the insulating material 130 may be close to one.
Forming metal lines 110 within one layer, as shown in
For ease of illustration,
Embodiments of the present invention may provide a magnetic film (or magnetic material) around metal lines of a transformer (or power converter). The magnetic material may be made with slots and/or laminations (i.e. a laminated structure). This magnetic material may limit Eddy currents flowing in the magnetic material. More specifically, a microstructure may be provided that includes metal lines surrounded with magnetic material such as amorphous CoZrTa for use as a micro-transformer or micro-inductor on a chip. The structure may be prepared by patterning a plurality of metal lines next to each other that are wide so as to lower the electrical resistance. The metal lines may then be surrounded with the magnetic material. In order to reduce the Eddy currents flowing in the magnetic films, the magnetic material may be made with slots and/or laminations to limit the Eddy currents. As one example, the slots may be formed perpendicular (or substantially perpendicular) to the lengths of the metal lines. The slots therefore may extend perpendicularly (or substantially perpendicularly) to the flow of current in the metal lines. A laminated structure may be formed (or provided) in the magnetic material by adding insulation material between layers of CoZrTa including Co oxide prepared using an oxygen plasma.
Embodiments of the present invention may fabricate a power converting circuit with micro-transformers that are monolithically integrated onto a chip (or die) to convert high voltages (such as 2 volts) to lower voltages (such as 0.7 volts) and thereby reduce the pin count of the chip. The structure may include alternating wide lines deposited next to each other so as to reduce the number of metal levels necessary, while maintaining the resistance low and the capacitance under control. When wide lines are placed next to each other, the mutual inductance may be significantly lower than the self-inductance because of the widths, but by breaking up the wide line into separate narrower lines results in significantly higher mutual inductance. That is, the wide line may be broken up into many segments (such as 12 segments as discussed above) that are connected together at each end to increase the coupling coefficient and mutual inductance. As will be described below with respect to
The magnetic material 220 may include a plurality of slots 225 formed perpendicular to the metal lines 210. The slots 225 may also be perpendicular (or substantially perpendicular) to the flow of current in the metal lines 210 such that the slots 225 do not interfere with the magnetic flux, but rather block (or substantially block) the flow of Eddy currents. Although not shown specifically in
The magnetic material may be a laminated structure 320 formed over the metal lines 310. For example, the laminated magnetic material 320 may include a stack of magnetic layers 322, 324, 328 and 329 and an insulation layer 326 between magnetic layers 324 and 328. The insulation layer 326 may be provided between layers of CoZrTa 324 and 328, for example. The insulation layer 326 may include an oxide or nitride such as a Co oxide prepared using an oxygen plasma. Other numbers of layers and materials are also within the scope of the present invention. The thickness of the magnetic layers can be 100˜200 nm and the insulating layer 10˜100 nm. The magnetic films may be deposited using sputtering, electroplating, or chemical vapor deposition.
Fabricating a power converter onto a chip with an integrated microtransformer may significantly reduce the cost associated with incorporating a power converter and may also reduce a socket pin count. Additionally, the number of socket pins may scale with the processor current. There may be fewer pins as compared to a circuit with a single scaled voltage. The motherboard resistance under the socket may also scale because a larger socket (i.e., more pins) may lead to a larger area under the motherboard.
Any reference in this specification to “one embodiment,” “an embodiment,” “example embodiment,” etc., means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. The appearances of such phrases in various places in the specification are not necessarily all referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with any embodiment, it is submitted that it is within the purview of one skilled in the art to effect such feature, structure, or characteristic in connection with other ones of the embodiments.
Although embodiments of the present invention have been described with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this invention. More particularly, reasonable variations and modifications are possible in the component parts and/or arrangements of the subject combination arrangement within the scope of the foregoing disclosure, the drawings and the appended claims without departing from the spirit of the invention. In addition to variations and modifications in the component parts and/or arrangements, alternative uses will also be apparent to those skilled in the art.
