1. Field of the Invention
The present invention relates to an inductor having a high Q value for use in high frequency in a semiconductor integrated circuit (IC).
2. Description of the Related Art
A conventional inductor will be described with reference to FIG. 9. Referring to
That is, in the conventional inductor, the inductor section is constructed of a single layer and the second layer is used for the drawing interconnect for connection with other components.
As one of characteristics of an inductor, it is generally known that in order to obtain a large inductance value, the line length of the inductor must be increased.
With the above conventional construction, however, when the line length is increased in order to obtain a large inductance value, the serial resistance component increases due to the resistance of a wiring material constituting the inductor, resulting in lowering the Q value of the inductor.
Further, the increased line length of the inductor tends to increase the size of the entire inductor.
In view of the above problems, an object of the present invention is to provide an inductor having a high Q value while suppressing the serial resistance from increasing.
Another object of the present invention is to provide an inductor of which size is not increased even when the line length thereof is increased.
A high-Q inductor for high frequency of the first present invention is such inductor that one inductor has a plurality of inductor elements formed in a plurality of IC wiring layers respectively; and the directions of magnetic fields generated by the respective inductor elements are substantially the same.
A high-Q inductor for high frequency of the second present invention according to the first present invention, is such inductor that the plurality of inductor elements are connected in series.
A high-Q inductor for high frequency of the third present invention according to the first present invention is such inductor that the plurality of inductor elements are connected in parallel.
A high-Q inductor for high frequency of the fourth present invention according to the first present invention, is such inductor that the plurality of inductor elements include a serial-connected circuit portion and a parallel-connected circuit portion.
A high-Q inductor for high frequency of the fifth present invention according to the first present invention, is such inductor that at least one of the inductor elements is in a meander shape or a spiral shape.
A high-Q inductor for high frequency of the sixth present invention according to any one of the first to fifth present inventions, is such inductor that a connection between the plurality of inductor elements is formed in an interlayer film disposed between the IC wiring layers in which the inductor elements are formed.
A high-Q inductor for high frequency of the seventh present invention according to the first present invention is such inductor that a drawing interconnect from the inductor element is formed in the IC wiring layer in which one of the inductor elements is formed.
The seventh present invention corresponds to FIG. 1.
A high-Q inductor for high frequency of the eighth present invention according to the seventh present invention is such inductor that the plurality of inductor elements are in a spiral shape respectively and connected in parallel with each other, and one of the drawing interconnect is connected to a spiral center of the inductor element and drawn externally by being formed in one of the IC wiring layers, and
The eighth present invention corresponds to FIG. 3.
A high-Q inductor for high frequency of the ninth present invention according to any one of the first to sixth present inventions is such inductor that a drawing interconnect from the inductor element is formed in a wiring layer which is different from the IC wiring layers in which the inductor elements are formed.
The ninth present invention corresponds to FIG. 2.
A high-Q inductor for high frequency of the tenth present invention according to the ninth present invention, is such inductor that a drawing interconnect and the inductor element to be connected with the drawing interconnect are connected via an connection formed in an interlayer film disposed between a wiring layer in which the drawing interconnect is formed and the IC wiring layer in which the inductor element is formed.
The tenth present invention corresponds to FIG. 2.
A high-Q inductor for high frequency of the eleventh present invention according to the first present invention, is such inductor that the plurality of inductor elements are in a spiral shape respectively,
The eleventh present invention corresponds to FIG. 4 and FIG. 5.
A high-Q inductor for high frequency of the twelfth present invention according to the first present invention, is such inductor that the plurality of inductor elements are in a spiral shape respectively,
The twelfth present invention corresponds to FIG. 6
Embodiments of the present invention will be described with reference to the relevant drawings.
(Embodiment 1)
Each of the connections 15 and 16 is composed of nine contact portions each having a size of about 1 μm square, for example.
In this embodiment, therefore, the inductor section, which is conventionally constructed using only one layer, is of a two-layer structure where two inductor sections are formed in the first and second layers and connected in parallel with each other.
The above construction makes it possible to obtain a high Q-value inductor for high frequency which overcomes the conventional problem of having a large serial resistance component in low frequency and high frequency and thus a lowered Q value, by increasing the cross section and suppressing lowering of the Q value which otherwise occurs due to a skin effect in high frequency.
It should be noted that the first and second layers may be connected in parallel over the entire inductor sections. This construction is also included in the present invention.
(Embodiment 2)
In this embodiment, therefore, the inductor section, which is conventionally constructed using only one layer, is of a two-layer structure where the inductor sections 22 and 23 are respectively formed in the first and second layers and connected in parallel with each other. This construction makes it possible to obtain a high Q-value inductor for high frequency which overcomes the conventional problem of having a large serial resistance component in low frequency and high frequency and thus a lowered Q value, by increasing the cross section and suppressing lowering of the Q value which otherwise occurs due to a skin effect in high frequency.
It should be noted that the first and second layers may be connected in parallel over the entire inductor sections. This construction is also included in the present invention.
In this embodiment, the three-layer inductor was exemplified. It is also possible to construct a similar structure composed of four or more layers with a drawing interconnect being formed in the bottom layer.
(embodiment 3)
The first and second inductor sections 31 and 33 are connected in parallel with each other.
Embodiment 3 is characterized in that the second-layer drawing interconnect 34 is formed using the layer in which the second-layer inductor section 33 is formed. In order to prevent the second-layer inductor section 33 from being in contact with the drawing interconnect 34 in the same layer, the second-layer inductor section 33 is cut off at the positions where the drawing interconnect 34 crosses. The cut-off ends of the inductor section 33 are connected with the first-layer inductor section 31 via the connections 35. By this construction, the second-layer inductor section 33 can serve as one substantially spiral-shaped inductor section.
In this embodiment, therefore, the inductor section, which is conventionally constructed using only one layer, is of a two-layer structure where inductor sections are formed in the first and second layers and connected in parallel with each other. Furthermore, the inductor sections are formed in the layers in which the drawing interconnects are formed. As a result, it is possible, even in a process where a smaller number of wiring layers are used, to obtain a high Q-value inductor for high frequency which overcomes the conventional problem of having a large serial resistance component in low frequency and high frequency and thus a lowered Q value, by increasing the cross section and suppressing lowering of the Q value which otherwise occurs due to a skin effect in high frequency.
Thus, Embodiment 3 is characterized in that one of the drawing interconnects is formed using the wiring layer for the inductor section, which is different from Embodiment 2 where the layer for forming the drawing interconnect is separately provided.
It should be noted that the first and second layers may be connected in parallel over the entire inductor sections. This construction is also included in the present invention.
In this embodiment, the two-layer inductor was exemplified. It is also possible to construct a similar structure composed of three or more layers with a drawing interconnect being formed in any of the layers. In this case, portions of an inductor section at which the drawing interconnect crosses can be connected with an adjacent upper or lower inductor section.
(embodiment 4)
In this embodiment, the adjacent inductor sections are connected with each other. Specifically, the centers or the outer ends of the adjacent inductor sections are connected with each other. These inductor sections are therefore connected in series with each other.
Adjacent inductor sections also overlap one another. Where they overlap can be referred to as a first area. This first area is smaller than a second area defined by the overlap between non-adjacent inductor sections. For example, the (first) area defined by the overlap of adjacent inductor sections 44 in FIG. 4(b) and 41 in FIG. 4(a) (or 46 in FIG. 4(a)) is smaller than the (second) area defined by the overlap or projection of inductor section 48 of FIG. 4(d) on section 44.
In this embodiment, the second-layer and fourth-layer inductor sections have a shape inverted upside down from that of the first-layer and third-layer inductor sections. By this arrangement, the directions of the magnetic fields generated by the respective inductor sections are the same, resulting in effective coupling.
In the conventional structure where the inductor section is constructed using only a single layer, when the entire length of the inductor section is increased to obtain a high Q value, the size of the inductor section also increases. On the contrary, in Embodiment 4, since the length of the inductor sections is increased stereoscopically as a whole, the resultant size is compact.
The four-layer structure was described in this embodiment. However, as shown in
When the number of layers is odd, the drawing interconnect can be arranged in a manner described in
Alternatively, as shown in
In the above case, also, the directions of the magnetic fields generated by the respective inductor sectors are the same, resulting in effective coupling.
Thus, according to the present invention, the inductor section, which is conventionally constructed of a single wiring layer, is of a multi-layer structure. As a result, a high Q-value inductor which has a reduced serial resistance component and is free from an influence of a skin effect can be fabricated in an IC.
Many modifications and variations of the present invention will be apparent to those skilled in the art without departing from the scope and spirit of the invention. It should therefore be understood that the present invention is not limited to the specific embodiments illustrated herein but only defined by the appended claims.
Number | Date | Country | Kind |
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H10-353078 | Dec 1998 | JP | national |
This application is a divisional of Ser. No. 10/043,222, filed Jan 14, 2002, now U.S. Pat. No. 6,664,882, which is a divisional of Ser. No. 09/454,610, filed Dec. 7, 1999, now abandoned, and which are both being incorporated in their entirety herein by reference. A claim for priority for this application is made under Japanese Application JP H10-353,078.
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Number | Date | Country | |
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20040041680 A1 | Mar 2004 | US |
Number | Date | Country | |
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Parent | 10043222 | Jan 2002 | US |
Child | 10667386 | US | |
Parent | 09454610 | Dec 1999 | US |
Child | 10043222 | US |