DE102005014929A1 - Inductor for integrated circuit, has number of vias connecting part of electrically conductive layers with each other to form three-dimensional conductive coil structure, where width of lower conductive strip is n-times width of upper strip - Google Patents

Abstract

The inductor has an electrically conductive layer provided on a substrate and defining a lower conductive strip. Another electrically conductive layer defines an upper conductive strip. A number of vias connect the part of electrically conductive layers with each other in order to form three-dimensional conductive coil structure. The width of the lower strip is n-times the width of the upper strip. An intermediate conductive layer is provided on the electrically conductive layer. An independent claim is also included for a transformer for an integrated circuit.

Description

Territory of invention

The The invention relates to an inductive component for integrated circuits, such as an on-chip inductive element or transformer, which are formed on a semiconductor substrate, substantially with the same process steps that are used in the production of integrated circuits are involved.

On running a chip Inductors and Transformers typically have a very low quality. The main reason is the ohmic resistance (including the skin effects) of the coil and the losses due to currents induced in the substrate. During the Coil resistance by increasing the width and height the metal coil can be reduced, it is very difficult, the substrate losses because every high-frequency magnetic field line, which the semiconductor permeates currents which, due to the resistance of the substrate finally in Heat and so that loss will be transformed. Apart from electrical effects No magnetic shielding on the chip is possible. A magnetic shield would be ferromagnetic Make materials necessary, which in standard CMOS processes not available are.

description of the related art

There are several types of coils and magnetic couplers in the literature. In addition to the very common spiral coils, there are some patents with integrated coils that lie between an upper and a lower metal layer and thus with the magnetic field lines parallel to the chip, z. B.
US 5,936,298 "Method for Realizing Magnetic Circuits in an Integrated Circuit": A coil is disclosed consisting of loops between upper and lower metal, with the turns arranged in a square, so that the field lines are (approximately) limited to this torus, ie in the silica.

US 2003 011 041 "Integrated Toroidal Coil Inductors for IC Devices": A similar coil as in US 5,936,298 is proposed, wherein the shape is closer to a torus.

US 2004 212 038 "Integrated Inductor in Semiconductor Manufacturing": Here, different realizations of pure coils and transformers are shown, with field lines parallel to the substrate The transformers consist of coils along the same axis of symmetry.

US Pat. No. 6,817,087 "Integrated Circuit Inductors": Various realizations of pure coils are shown, and in addition, the use of ferromagnetic materials to increase the inductance is suggested.

US Pat. No. 6,803,848 "Integrated Helix Coil Inductor on Silicon": A coil is proposed between the upper and lower multi-turn metal layers, with the width of the turns growing linearly from the outer to the central turn.

US Pat. No. 6,614,092 "Inducted Inductor in Semiconductor Manufacturing": Various types of coils and concentric transformers with and without a magnetic core are disclosed, the field axis being in the plane of the substrate.

Most magnetic couplers in the literature consist of several turns in different superposed metal layers, or of intertwined turns spiraling around a common center, e.g. B .:
US 6,794,977 "Planar Transformer": Two spiral coils with two turns are twisted into each other to form a transformer, and the field lines are orthogonal to the substrate.

DE 102 61 385 : Integrated Spiral Pentafilar ": Four input windings and one output winding are nested to form a transformer and the field is orthogonal to the substrate.

WHERE 03/03 390 "Mulitple-Interleaved Circuit Transformer ": Four windings are interlaced and form a transformer.

US 2004 195 651 "Center Tap Transformers in Integrated Circuits": Several implementations of transformers are disclosed which consist of concentric windings in different metal layers.

US 2004 207 504 "On-Chip Transformer Balun": A transformer consisting of two spiral coils in different metal layers is disclosed.

US 6,480,086 "Inductor and Transformer Formed with Multi-Layer Coil Turns Fabricated on an Integrated Circuit Substrate": Concentric transformers are disclosed, which are nested inside each other.

US Pat. No. 6,816,012 "Distributed Circular Geometry Power Amplifier Architecture": A magnetic coupler with four inputs and one output disclosed. The exit is a loop (square shape) in the upper metal layer. The inputs include strip conductors that are parallel and close to each side of the square loop. Since the input turns of this structure are strip conductors, the field lines are circular around the strip conductor. Therefore, a part of the input field penetrates into the substrate and causes substrate losses.

epiphany the invention

It the object of the present invention is an inductive component for integrated Circuits in the form of an inductance or a transformer to suggest, with significantly reduced substrate losses.

These Task is by providing an inductive component for integrated Circuits achieved as described in the independent claims is.

Other Features considered characteristic of the invention are in the dependent claims executed which is incorporated herein by reference.

According to the invention is a inductance for integrated Circuits proposed, which includes a substrate, a first electrically conductive layer on the substrate, which at least a lower strip-shaped Head defined, an intermediate layer on the first electrically conductive layer, which at least one insulating and / or dielectric layer comprises a second electrically conductive layer on this intermediate layer, which is at least one upper strip-shaped Conductor defined, and a plurality of vertical electric Ladders, so-called "vias", which are parts of connects first and second electrically conductive layers, to form a 3-dimensional conductive coil structure, wherein the width of the lower strip-shaped Ladder is n times the width of the upper strip-shaped conductor.

One Transformer for integrated circuits according to the invention includes a substrate, a first electrically conductive layer, which comprises at least one lower strip-shaped conductor, a intermediate layer on the first electrically conductive Layer comprising at least one insulating and / or dielectric Layer comprises a second electrically conductive layer on this intermediate layer, which at least one upper strip-shaped conductor includes, and at least two transformer windings, wherein a first winding of one according to the present invention Invention constructed inductance, and a second Winding of a strip-shaped Coil structure arranged in the plane of the second conductive layer is.

By the construction of coils and transformers in line with of the present invention Substrate losses of the coils are completely avoided - at least theoretically - by change the geometry of the coils. This allows a new kind of inductors and Transformers on a chip. The structure uses the height between the bottom and top conductive (metal) layers to 3-dimensional Build up coils and transformers. The concept can be used be to coils, simple transformers (an input and a Output) or transformers higher Order (2 to 1, 4 to 1, 8 to 1). The invention can furthermore for the production of on-chip realizations used by Baluns. Therefore, it offers a good alternative too expensive off-chip baluns.

in the Trap of more than one input coil, with an output coil is coupled, the invention can be used as a power combiner become. On-chip power combiners can be used be to the power of several power amplifiers, four in the case below, to passively merge. Thus, the single amplifier only a quarter of the power needed at the antenna supply. Of Further, the inductance ratio between the entrance and Output coils are used for impedance transformation. One Transformer or coupler according to the invention can also be used as a power divider with an input coil and more than one output coil can be used.

From the literature, coils which lie between a lower and an upper conductive layer are known. The toroidal structures in US 5,936,298 and US 2003 011 041 are shown, the field lines have all limited to the torus, ie in the silicon oxide. Therefore, these concepts have reduced substrate losses like the concept presented here. However, these torus structures are single turns (inductors) and not couplers. Therefore, they do not offer the coupling properties of the present idea. The coils and transformers in US 2004 212 038 . US Pat. No. 6,817,087 . US Pat. No. 6,803,848 and US Pat. No. 6,614,092 are shown to be straight and symmetrical with respect to a plane between the metal layers. Therefore, half of the field lines in the substrate close and produce substrate losses. In this regard, these coils are worse than the coils proposed here. The couplers are collinear. Therefore, the input field does not go completely through the output coil, which is a reduced coupling constant has the consequence. In the solution with magnetic materials, the coupling is improved, but a non-standard CMOS process with magnetic layers is needed.

Other magnetic couplers in the literature consist of concentric spirals in one or more metal layers, see here e.g. B. US 6,794,977 . DE 102 61 385 , WO 03/03390, US 2004 195 651 . US 2004 207 504 and US 6,480,086 , These structures typically have good coupling constants between the coils, but they do not provide isolation between different input coils. Therefore, the crosstalk between different inputs is about the same order of magnitude as the coupling to the output. (For some applications, this may be a desirable feature, but in the case of different input signals, for example, this is certainly a major drawback.) Furthermore, the concentric spirals have field lines perpendicular to the substrate. Therefore, all field lines penetrate the wafer and produce substrate currents and substrate losses.

The coupler of in US Pat. No. 6,816,012 discloses uses only made of strip conductors input coils. Therefore, the fields generated by the input are concentric loops around the strip conductors. This results in good isolation between adjacent and opposite input "coils." Furthermore, the strip conductors are located on either side of the output turns so that the input-to-output coupling is quite good, however, since the strip lines do not prevent the field lines from entering the input line Since there is a large number of field lines (approximately less than half because the stripline is in the top metal) in the substrate, there will be a significant amount of substrate loss and the field strength below the strip conductors will be less than Therefore, the coupling between adjacent inputs and the coupling between opposite inputs in the present invention is less uniform since the field lines are not limited from below US Pat. No. 6,816,012 larger than in the present invention, and the coupling between input and output coils is smaller than in the present invention.

Short description the drawings

1 shows a single metal loop made between two conductive layers (prior art).

2 shows a section through a single metal loop according to 1 , and the distribution (simplified) of the magnetic field lines (prior art).

3 shows in inductive component according to the invention.

4 shows a section of the coil of 3 and the distribution (simplified) of the magnetic field lines.

5 shows a section through a symmetrical coil with two windings according to the invention.

6 shows a perspective view of a transformer (coupler) according to the invention with a 3-dimensional structure with four inputs and one output.

7 shows a plan view of the output coil of the transformer in 6 ,

8th shows a plan view of one of the input coils of the transformer of 6 ,

9 shows a section of the transformer of 6 and the distribution (simplified) of the magnetic field lines.

10 shows a plan view of the complete transformer of 6 ,

description of preferred embodiments of the invention

The general structure on which the invention is based is a coil structure between two spaced conductive (metal) layers of a multilayer structure. In the simplest case, as it is in the 1 and 2 (Prior Art), an integrated circuit inductor according to the prior art comprises a substrate 1 , a first electrically conductive layer 2 , z. B. a metal layer on the substrate, the at least one lower strip-shaped conductor 3 defined, an intermediate layer 4 on the first electrically conductive layer, which comprises at least one insulating and / or dielectric layer, and a second electrically conductive (metal) layer 5 on this intermediate layer, which at least one upper strip-shaped conductor 6 Are defined. The ends of the upper and lower strip conductors 3 . 6 are interconnected by "vias" 7, 8, resulting in a 3-dimensional conductive coil structure 2 close in this simple geometry half of the magnetic field lines 9 in the upper half-plane (ie through the air) and half of the magnetic lines 10 close to the bottom ren half-plane, ie through the substrate 1 , and therefore cause substrate loss. Compared to 2-dimensional coils, which are provided in a single conductive plane, this type of 3-dimensional coil avoids half of the substrate losses due to the geometry.

However, the present invention shows a way to completely avoid substrate losses. According to the invention, the symmetry between the lower and upper layers must be refracted to give the magnetic field a preferred direction of closure. Starting from an inductive element according to the 1 and 2 The easiest way to accomplish this is to use the conductive strip 11 the lower layer 2 much wider than the conductive strip 6 in the upper layer 5 close. The width of the lower pipe 11 should be at least 2 times larger, but preferably more than 3 times larger than the width of the top duct 6 , Because the upper metal layer 5 usually made of thick metal, it is anyway a preferred choice in terms of resistance, the lower layer 11 wider than the upper layer 6 close. The ends of the metal ladder 11 . 6 become corresponding by vias 12 . 13 connected with each other. The coil proposed according to the invention now looks like it in the 3 and 4 is shown. The structure of the proposed inductive element is asymmetrical with respect to a reflection in the horizontal plane. The magnetic field lines 14 that are generated by this coil must pass through the intervening layer 4 between the lower and upper metal layers 2 . 5 go through it. However, because the magnetic field lines 14 have a strong tendency to separate, they will do it as soon as possible. In the intermediate layer 4 prevent the currents in the two metal conductors 11 . 6 that they separate from each other. In areas where there is no upper metal but a lower metal, the current in the lower metal still prevents intrusion of the field lines 14 in the substrate 1 , However, since there is no limit to the top, they start to separate upwards, ie all magnetic field lines 14 start to bend upwards. As soon as the field lines 14 bent upwards, they no longer bend down and thus close in the upper half plane, as in 4 sees.

Based on the single turn of the 3 and 4 we can generalize this idea to coils with several turns. A symmetrical coil with two turns is in 5 shown. In the middle of the two upper conductor strips 6 . 6 ' is a double crossing 15 which can be realized by providing an electrically isolated conductive layer (shown in FIG 8th ) under the upper conductive layer 5 provides. The example of 6 Figure 4 shows a 3-dimensional structure of a 4 to 1 transformer (coupler) constructed in accordance with the present invention and in which most of the advantages of this new structure are exploited, for example the quadratic symmetry of the quadratic coils. The most general form of the proposed coupler includes an output turn 16 , which can be a square (for a maximum of four inputs) or octagonal (for eight inputs). This output winding 16 is in the upper metal finish 5 made, which is preferably thicker than the lower metal layer. In the simplest implementation, the output winding includes 16 just one turn (though that does not necessarily have to be the case) as it does in 7 and simply forms a 2-dimensional metal loop in the top metal layer 5 , Generalizing to multiple loops is easy.

The input windings are made in the insulating material by using the upper and lower metal layers 2 . 5 that is caused by a variety of vias 12 . 13 connected with it, as discussed above 5 has been described. An input coil consists of two upper metal lines 6 . 6 ' on both sides of one side of the output coil 16 (ie one quarter of the square output coil for the 4 to 1 coupler and one eighth of the octagonal 8 to 1 coupler). In the middle of this page, the two metal lines intersect 6 . 6 ' the input coils by means of a short bridge in underlying metals. Under these three upper metal lines 16 . 6 . 6 ' (at each input) are two wide (typically four times wider than the upper lines) lower metal lines 11 . 11 ' provided which has a large array of vias 12 . 13 connected to the two upper metal strips of the input coils. One of these lower metal lines is cut apart in the middle and defines the two connections 17 . 18 the input coil. With this structure results in a symmetrical input coil with two turns and an axis which lies within the silicon oxide, as is apparent from 8th results. In the middle of the two upper conductor strips 6 . 6 ' is a double crossing 15 , which can be realized by two different electrically isolated from each other intermediate conductive layers under the upper conductive layer 5 are arranged. A generalization on coils with many windings is simple. Because the distance between the upper and the lower metal layers 2 . 5 typically much smaller than the typical length of a coil, these input coils are very shallow. All magnetic field lines generated by the input coil must pass through the narrow slot between the two conductive layers 2 . 5 go through what is in magnetic field lines 19 results, which are perpendicular to the side of the output kitchen sink 16 run, and thus parallel to each other (of course, there are slight deviations in the outer regions of the input coils, ie in the vias 12 . 13 ). Because the two turns of the specified input coils are located on both sides of the output coil, it guarantees all the magnetic field lines 19 generated by the input coils crossing the inside of the output coil. 9 shows that all magnetic field lines 19 Contribute from the input side to a flux through the output coil, with only a very small coupling between the various input coils occurs. As the bottom metal strip 11 in the input coil much wider than the upper metal strip 6 is, the magnetic field bends 19 once it has crossed the area between the two conductive layers, substantially upwards. Therefore, all field lines 19 a considered input coil contributes to the flux through the output coil 16 , Therefore, the coupling between input and output is maximum. In addition, the magnetic field lines generate 19 the input coil, as they only through the intervening insulating layer 4 (eg, silica) and air and thrown back by the currents in the lower metal layer, no substrate currents and thus no substrate loss. Therefore, these coils have very low losses.

The coupling between the different input coils is negligible in the case of the 4 to 1 coupler. This is due to the parallel field lines 19 which are generated by each input coil. Therefore, the field generated by a considered input has no flux through one of the two adjacent input coils whose axes are perpendicular to the magnetic field. The coupling between two input coils lying on opposite sides is also negligible since the magnetic field lines 19 bend upwards as soon as they leave the slot of a considered input coil. Thus, very few field lines generated by a given input coil pass through the narrow slot of the opposite input coil.

One possible layout of the transformer structure is in 10 shown. In the case of an octagonal 8 to 1 coupler, the input coils have a relative 45 ° angle to each other, resulting in limited or even small crosstalk between adjacent input coils. The concept can be easily generalized to a coil with multiple turns on the output side. In this case, it is important that the innermost and outermost turns of a considered input coil be inside or outside all sides of the output coil. This guarantees that the entire flow of the entrance goes through the exit.

• – die Verwendung der dritten Dimension für Eingangsspulen in magnetischen Kopplern. Dies erlaubt es, magnetische Koppler mit vernachlässigbarer Kopplung zwischen den verschiedenen Eingangsspulen herzustellen.
• – Verwendung von Eingangswicklungen, die die Ausgangswicklung umgeben. Dies garantiert, dass alle Feldlinien einer Eingangsspule das Innere der Ausgangsspule kreuzen müssen.
• – Verwendung eines breiteren Metalls in der unteren Ebene der Eingangsspulen. Diese Idee zwingt alle magnetischen Feldlinien der Eingangsspule sich nach oben zu biegen und somit einen Fluss durch die Ausgangsspule zu erzeugen. Dies garantiert eine maximal mögliche Kopplung zwischen Eingangs- und Ausgangsspule. Weiterhin erzeugt der schmale Schlitz der Eingangsspule sehr starke und parallele Eingangsfelder im Schlitz, was eine Kopplung mit benachbarten Eingangsspulen vermeidet.

The main advantages of the innovative transformer structure are:

• - the use of the third dimension for input coils in magnetic couplers. This makes it possible to produce magnetic couplers with negligible coupling between the various input coils.
• - Use of input windings surrounding the output winding. This guarantees that all field lines of an input coil must cross the inside of the output coil.
• - Using a wider metal in the lower level of the input coils. This idea forces all of the magnetic field lines of the input coil to bend upward, thus creating a flux through the output coil. This guarantees a maximum possible coupling between the input and output coils. Furthermore, the narrow slot of the input coil produces very strong and parallel input fields in the slot, avoiding coupling to adjacent input coils.

1

substratum

2

first conductive layer

3

ladder

4

between lying layer

5

second conductive layer

6

ladder 6 '

7

vias

8th

vias

9

magnetic field lines

10

magnetic field lines

11

ladder 11 '

12

vias 12 '

13

vias 13 '

14

magnetic field lines

15

crossing

16

output winding (Transformer)

17

connection

18

connection

19

magnetic field lines

Claims (11)

An integrated circuit inductor comprising: a substrate; a first electrically conductive layer on the substrate defining at least one lower strip-shaped conductor; an intermediate layer on the first electrically conductive layer comprising at least one insulating and / or dielectric layer; a second electrically conductive layer on the intermediate layer, which comprises at least one defined upper strip-shaped conductor; a plurality of vertical electrical conductors, vias, interconnecting portions of the first and second electrically conductive layers to form a 3-dimensional conductive coil structure, characterized in that the width of the lower striped conductor is n times the width of the upper striped conductor is. The inductance for integrated Circuits according to claim 1, characterized in that n 2, preferably n 3. The inductance for integrated Circuit according to one of the preceding claims, characterized that the first electrically conductive layer has a plurality of strip-shaped conductors which is electrically connected to a plurality of strip-shaped conductors in the second electrically conductive layer connected to a 3-dimensional conductive coil structure with multiple turns to define. The inductance for integrated Circuit according to one of the preceding claims, characterized that it comprises at least one intermediate conductive layer, which is isolated from the first and second conductive layers and several strip-shaped ones Ladder includes which intersections between the several upper strip-shaped ladders define. The inductance for integrated Circuit according to one of the preceding claims, characterized that the coil structure comprises two terminals, which in the first conductive layer are arranged and with the lower strip-shaped conductor are connected. The inductance for integrated Circuit according to one of the preceding claims, characterized that it is a component of an integrated circuit CMOS. An integrated circuit transformer, which includes: a substrate; a first electrically conductive Layer comprising at least one lower strip-shaped conductor includes; an intermediate layer on the first electrically conductive layer, which at least one insulating and / or dielectric Layer comprises; a second electrically conductive layer this intermediate layer, which at least one upper stripe Head includes; at least two transformer windings, in which a first winding of an inductor according to claims 1 to 6 and a second winding consists of a strip-shaped coil structure, those within the plane of the second electrically conductive layer is arranged. The integrated circuit transformer according to claim 7, characterized in that the second winding at least m Turns and the first winding at least m + 1 turns, with m = 1, 2, 3, .... to M, wherein at least a part of the strip-shaped coil structure the second winding between parts of the two strip-shaped conductors the first winding is located. The integrated circuit transformer according to a the claims 7 or 8, characterized in that it comprises a plurality of windings of first type and a winding of the second type. The integrated circuit transformer according to a the claims 7 to 9, characterized in that it comprises a winding of the first Type and multiple windings of the second type includes. The integrated circuit transformer according to a the claims 7 to 10, characterized in that it is a component of an integrated circuit CMOS is.