JP2736362B2 - Method for manufacturing capacitor of microwave integrated circuit - Google Patents

Description

The present invention relates to a method for manufacturing a capacitor in a microwave integrated circuit.

[Prior Art] FIG. 3 shows a conventional typical method for manufacturing a capacitor of a microwave integrated circuit. Hereinafter, the manufacturing method will be described with reference to FIG. First, a first metal wiring 2 such as Au is formed on a semi-insulating substrate such as gallium arsenide (GaAs) or an insulating substrate 1 such as SiO ₂ by a lift-off method or the like (FIG. 3A). Next, after a first insulating film 3 such as SiO ₂ or Si ₃ N ₄ is formed on the entire surface by, eg, plasma CVD, a part of the first insulating film 3 on the first metal wiring 2 is selectively formed. The first metal connection pillar 4 made of Au or the like is formed on the removed portion by a lift-off method or the like (FIG. 3B).

Next, a second metal wiring 5 made of Au or the like is formed by a sputtering method or the like, and a photoresist 6 partially opened is formed thereon by a normal photolithography process (FIG. 3C). ). Next, the second metal wiring 5 is selectively removed by ion beam matching or the like using Ar ions or the like with the photoresist 6 as a mask to separate the portion connected to the first metal connection column 4. The resist 6 is removed by a solvent, and then a _second insulating film 7 such as SiO ₂ or Si ₃ N _{4 is} formed by a plasma CVD method or the like (FIG. 3D).

Next, a second metal connecting column 8 connected to a portion of the second metal wiring 5 connected to the first metal connecting column 4 is formed in the second insulating film 7 in the same manner as the first metal connecting column 4. Formed by the method,
Thereafter, a third metal wiring 9 is formed by the same method as that for the second metal wiring 5 (FIG. 3E).

In the structure of FIG. 3E, the first metal wiring 2 is
And a part of the second metal wiring 5, and the third metal wiring 9 via the second metal connection pillar 8.
The first metal wiring 2 or the third metal wiring 9 is used as a first electrode, the second metal wiring 5 is used as a second electrode, and the intersection of the first metal wiring 2 and the second metal wiring 5 The first insulating film 10 and the second insulating film 11 at the intersection of the second metal wiring 5 and the third metal wiring 9 are made of a dielectric material so that the metal electrode / dielectric / metal electrode Is formed.

[Problem to be Solved by the Invention] In the conventional capacitor manufacturing method described above,
In order to reduce the wiring resistance, the wiring thickness is increased to 1 μm or more in order to use the metal wiring 5 as a wiring connecting the elements constituting the microwave integrated circuit. 0.3 to 0.5 to increase the capacity of
It is necessary to reduce the thickness to about μm. Therefore, when the second insulating film 7 is formed by a normal method such as a plasma CVD method or a sputtering method, the height of the side wall of the second metal wiring 5 is larger than the thickness of the formed insulating film. In the case where the deposition rate of the insulating film attached to the side wall of the second metal wiring 5 is low, the thickness of the insulating film 12 in this portion is reduced, and the film quality is deteriorated such that the density of the film in the side wall is further reduced (No. As shown in FIG. 1 (e) or FIG. 4, the second insulating film 7 does not adhere to the side wall of the second metal wiring 5, and the second metal wiring 5 and the third metal wiring 9 are separated. A contact portion 13 may occur. Therefore, in the former case, the electric breakdown voltage of the capacitor is reduced, and in the latter case, there is a problem that the capacitor is electrically short-circuited and does not work as a capacitor.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method of manufacturing a capacitor for a microwave integrated circuit, which has a high electric withstand pressure and does not lower the yield of the capacitor due to an electric short circuit.

[Means for Solving the Problems] According to the present invention, after forming the second metal connection pillar on the second insulating film, the second metal connection pillar intersects with the third metal wiring at the edge of the second metal wiring. A third insulating film is formed on a portion to be formed, then a third metal wiring is formed, and then the third insulating film is removed.

"Embodiment" An embodiment of a method for manufacturing a capacitor of a microwave integrated circuit according to the present invention is shown in FIG. 1, and portions corresponding to those in FIG. 3 are denoted by the same reference numerals. First, a first metal wiring 2, a first insulating film 3, a first insulating film 3, and a semi-insulating or insulating substrate 1 are formed on a semi-insulating or insulating substrate 1 by the same steps as the conventional steps (FIGS.
The first metal connection pillar 4, the second metal wiring 5, the second insulating film 7, and the second metal connection pillar 8 are formed.

Next, in the present invention, a third insulating film such as a photoresist
14 is formed at the edge of the second metal wiring 5 by a normal photolithography process (FIG. 1A). Next, if necessary, a metal film 15 made of Au or the like is formed on the entire surface to a thickness of about 0.1 μm by a sputtering method or the like, and then the third metal wiring made of Au or the like is used as a conductive layer by, for example, an electrolytic plating method. 9 is formed on the entire surface of about 2 to 3 μm (FIG. 1B). Next, a photoresist 16 is formed by a normal photolithography process or the like (FIG. 1C). Next, using the photoresist 16 as a mask, the third metal wiring 9 and the metal film 15 are etched by ion beam etching using, for example, Ar ions, so that a part of the second insulating film 7 and the third insulating film 14 are formed. Is exposed and the photoresist 16 is removed by a solvent, and then the third insulating film 14 is removed by, for example, plasma etching using oxygen gas (FIG. 1 (d)).

By the above-described steps, the second metal wiring 5 and the third metal wiring 9 are separated from each other by the space 17 at the edge of the second metal wiring 5.
Is electrically separated by Therefore, the insulating film 12 on the side wall
Has the characteristic that the electric breakdown voltage of the capacitor is high irrespective of the thickness and film quality of the capacitor. Further, as shown in FIG. 2, the second metal wiring 5 is not completely covered with the second insulating
The feature is that even if 18 occurs, electrical short-circuiting of the capacitor can be prevented. Therefore, there is an advantage that the electrical, withstand voltage and yield of the capacitor can be significantly improved as compared with the conventional case.

[Effects of the Invention] As described above, according to the method for manufacturing a capacitor of a microwave integrated circuit according to the present invention, the electrical breakdown voltage of the capacitor increases, the electrical short-circuit does not occur, and the electrical yield increases. When a relatively low frequency circuit such as a band requires a large number of capacitors having a large capacitance value, there is an advantage that the electrical performance is improved. Also, since the third insulating film 14 has been removed, there is no parasitic capacitance at this portion.
It is possible to easily obtain a capacitor whose design is determined by the facing area between the electrodes. When the third metal wiring 9 is formed by the electrolytic plating method after forming the thin metal film 15 as in the above-described example, the third metal wiring 9 is formed even if the third insulating film 14 has large irregularities. Can be accurately and thickly applied to each part.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a main part of a process of the capacitor manufacturing method of the present invention, FIG. 2 is a cross-sectional view for explaining the effect of the present invention, and FIG. FIG. 4 is a cross-sectional view for explaining a conventional problem.

Claims (1)

(57) [Claims] A first metal wiring, a first insulating film, a second metal wiring, a second insulating film, and a third metal wiring are sequentially formed in multiple layers on an insulating or semi-insulating substrate; First and second connecting the first metal wiring and the third metal wiring via a part of the second metal wiring in the first insulating film and the second insulating film. Metal connection pillars are respectively formed, the first metal wiring or the third metal wiring is used as a first electrode, the second metal wiring is used as a second electrode, and the first metal wiring and the first metal wiring are connected to each other. The first insulating film sandwiched between the intersections of the second metal wiring and the second insulating film sandwiched between the intersections of the second metal wiring and the third metal wiring; A method for manufacturing a capacitor of a microwave integrated circuit including a capacitor comprising a metal electrode / derivative / metal electrode having After the step of forming the first metal wiring, the first insulating film, the second metal wiring, the second insulating film, and the first and second metal insulating columns, the second metal A third insulating film is formed at a portion of the wiring that should cross the third metal wiring, and then the third metal wiring is formed. A method for manufacturing a capacitor of a microwave integrated circuit, comprising selectively removing an insulating film.