JP2006237127A - Capacitance element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a capacitance element in which a capacity value is about several to several tens of fFs. <P>SOLUTION: The tip of a first metallic conductor connected to first metal wiring and the tip of a second metal conductor connected to second metal wiring are made to face on an insulating substrate. At this time, the tips where the first metallic conductor and the second metallic conductor face is separated from the first metal wiring and the second metal wiring and located so that the coupling capacitance between the first metallic conductor and the second metal wiring and the coupling capacitance between the second metallic conductor and the first metal wiring become sufficiently smaller than the coupling capacitance between the first metallic conductor and the second metallic conductor. Moreover, the width of the surface at the tip of the first metallic conductor and the second metallic conductor can also be made large. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a capacitive element, and more particularly to a capacitive element having a very small capacitance value.

  As a capacitive element formed on a semiconductor integrated circuit, a capacitive element having a laminated structure of a lower layer electrode 7 / insulating film 8 / upper layer electrode 9 (FIG. 5, Patent Document 1), semiconductor layer / insulating film / upper layer electrode A capacitive element having a MIS structure having a laminated structure is widely used. These capacitive elements are suitable as a structure of a capacitive element having a small area and a large capacitance value.

On the other hand, the interdigital capacitor arranged so that the two comb-shaped conductors 10 and 11 are combined with each other on the insulating film can easily produce a capacitance element having a small capacitance value with high accuracy (FIG. 6, Patent Document 2). .
JP-A-5-235263 JP-A-7-283075

  Conventionally proposed interdigital capacitors as a method of forming a capacitance element having a small capacitance value are arranged so that comb-shaped conductors are combined with each other, so that a capacitance element of about several pF can be easily manufactured with high accuracy. Although suitable, it is not suitable for forming a capacitive element having a smaller capacitance value of several to several tens of fF. An object of this invention is to provide the capacitive element with a smaller capacitance value than before.

  In order to achieve the above object, the invention according to claim 1 of the present application includes a first metal conductor connected to the first metal wiring and a second metal conductor connected to the second metal wiring on the insulating base. However, the coupling capacitance between the first metal conductor and the second metal wiring and the coupling capacitance between the second metal conductor and the first metal wiring are such that the respective tips are opposed to each other. The opposing tips of the first metal conductor and the second metal conductor are arranged so that the coupling capacity between the first metal conductor and the second metal conductor is sufficiently smaller than the first metal conductor. The metal wiring and the second metal wiring are arranged apart from each other.

  The invention according to claim 2 of the present application is the capacitive element according to claim 1, wherein the opposing ends of the first metal conductor and the second metal conductor are the first metal conductor and the second metal conductor. It is characterized by being wider than the width in the direction perpendicular to the extending direction.

  In the present invention, since the first metal conductor and the second metal conductor are opposed to each other and the capacitive element is formed by the coupling capacitance, the capacitive element having a very small capacitance value can be formed. Further, the first and second metal wirings are arranged in a capacitive element in order to dispose the tip part sufficiently away from the first metal wiring and the second metal wiring that are connected to the first and second metal conductors, respectively. Therefore, it is possible to provide an accurate capacitive element.

  In addition, since the width and the separation distance of the first and second metal conductors formed by the normal manufacturing process of the semiconductor device can be as designed without variation, the capacitance value does not vary.

  Furthermore, by using a capacitor element having a structure in which the wide end portions of the first metal conductor and the second metal conductor face each other, the range of capacitance values that can be formed is preferable.

  Hereinafter, the present invention will be described in detail. 1A and 1B are explanatory views of a capacitive element according to the present invention. FIG. 1A is a plan view, and FIG. 1B is a cross-sectional view taken along the plane A-A ′ of FIG. As shown in FIG. 1, the capacitive element of the present invention is generally formed on an insulator film 2 on a semiconductor substrate 1, and includes a tip 3a of a first metal conductor 3 and a second metal. It arrange | positions so that the front-end | tip 4a of the conductor 4 may oppose. The other end of the first metal conductor 3 is connected to the first metal wiring 5, and the other end of the second metal conductor 4 is connected to the second metal wiring 6.

  Here, the coupling capacitance between the first metal conductor 3 and the second metal wiring 6 and the coupling capacitance between the second metal conductor 4 and the first metal wiring 5 are the first metal conductor. The opposing ends 3a and 4a of the first metal conductor 3 and the second metal conductor 4 are connected to the first metal wiring 5 and the second metal conductor 4 so as to be sufficiently smaller than the coupling capacity between the first metal conductor 3 and the second metal conductor 4. The second metal wiring 6 is sufficiently separated from the second metal wiring 6.

  By disposing in this way, a capacitive element composed of a coupling capacitance between the first metal conductor 3 and the second metal conductor 4 can be formed. Further, the tip of the first metal conductor 3 and the tip of the second metal conductor 4 can be wide tips 3b and 4b as shown in FIG. This will be specifically described below.

  A capacitive element is formed on the insulator film 2 made of a nitride film (dielectric constant 6.75) having a thickness of 0.67 μm and laminated on the semiconductor substrate 1 made of semi-insulating GaAs (dielectric constant 12.9). To do. A first metal conductor 3, a second metal conductor 4, a first metal wiring 5, and a second metal wiring 6 made of gold (Au) having a thickness of 3.4 μm and a width of 3 μm are disposed. The distance between the first metal conductor 3 and the second metal conductor 4 is 5 μm. The coupling capacitance between the first metal conductor 3 and the second metal wiring 6 and the coupling capacitance between the second metal conductor 4 and the first metal wiring 5 are the same. The opposite ends (3a, 4a) of the first metal conductor 3 and the second metal conductor 4 are connected to the first metal wiring 5 and the second metal conductor 4 so as to be sufficiently smaller than the coupling capacity between the second metal conductor 4 and the second metal conductor 4. It is necessary to dispose it sufficiently away from the second metal wiring 6. This separation dimension is determined as follows.

  In order to simplify the explanation, when the extension dimension (L1) of the first metal conductor 3 is changed in FIG. 3A, the first metal conductor 3, the second metal conductor 4, and the coupling capacitance (C1). ), How the coupling capacitance (C2) of the second metal conductor 4 and the first metal wiring 5 changes will be described. Since the coupling capacity between the first metal conductor 3 and the second metal wiring 6 is assumed to be negligibly small, the length of the second metal conductor 4 is set to 300 μm or more. It is assumed that the coupling capacitance between the wiring 5 and the second metal wiring 6 is negligibly small.

  FIG. 3B shows the coupling capacity (C1) between the first metal conductor 3 and the second metal conductor 4 and the second metal when the extension dimension (L1) of the first metal conductor 3 is changed. Sum (C1 + C2) of the coupling capacity (C2) of the conductor 4 and the first metal wiring 5, the coupling capacity (C2) of the second metal conductor 4 and the first metal wiring 5, and the ratio (C2 / (C1 + C2)) Is shown. The coupling capacitance (C2) between the second metal conductor 4 and the first metal wiring 5 indicates the coupling capacitance when the first metal conductor 3 is not formed.

  As shown in FIG. 3B, the coupling capacitance (C2) between the second metal conductor 4 and the first metal wiring 5 decreases rapidly as the extension dimension L1 becomes longer. On the other hand, the coupling capacity (C1 + C2) of the second metal conductor 4, the first metal conductor 3, and the first metal wiring 5 is substantially constant. From these results, it can be seen that under the above conditions, it is possible to form a capacitive element having a very small capacitance value of about 4 fF by setting the extension dimension L1 to 200 μm or more.

  It goes without saying that the coupling capacitance between the first metal conductor 3 and the second metal wiring 6 omitted in the above description can be explained in the same manner. Further, if the width and the separation size of the metal conductor are changed, the coupling capacitance can be changed, and a capacitor element having a very small capacitance value of about several fF can be formed.

  FIG. 4 shows a second embodiment of the present invention. Under the conditions described in the first embodiment, the extension dimensions L1 and L2 of the first metal conductor 3 and the second metal conductor 4 are 300 μm, and only the widths L3 and L4 of the respective tips 3b and 4b are 50 μm. In this case, an 8.5 fF capacitive element could be obtained. By changing the dimensions L3 and L4 and the separation dimension, a capacitive element of about several to several tens of fF can be formed.

It is a figure explaining the capacitive element of this invention. It is a figure explaining another capacitive element of this invention. It is a figure explaining the 1st Example of the capacitive element of this invention. It is a figure explaining the 2nd Example of the capacitive element of this invention. It is a figure explaining the conventional capacitive element. It is a figure explaining another conventional capacitive element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1; Semiconductor substrate, 2; Insulator film | membrane, 3; 1st metal conductor, 4; 2nd metal conductor,
5; 1st metal wiring, 6; 2nd metal wiring, 7; lower layer electrode, 8; insulating film,
9: Upper layer electrode, 10, 11; Comb conductor

Claims (2)

  A first metal conductor connected to the first metal wiring and a second metal conductor connected to the second metal wiring are opposed to each other on the insulating base, and the first metal conductor is opposed to the first metal conductor. Between the first metal conductor and the second metal conductor, and a coupling capacitance between the second metal conductor and the second metal conductor, The opposing tips of the first metal conductor and the second metal conductor are spaced apart from the first metal wiring and the second metal wiring so as to be sufficiently smaller than the coupling capacity between them. A capacitive element. 2. The capacitive element according to claim 1, wherein opposing ends of the first metal conductor and the second metal conductor have a width in a direction perpendicular to an extending direction of the first metal conductor and the second metal conductor. A capacitive element characterized by being wider.

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