JPS59181031A - Forming method of aerial wiring - Google Patents

Abstract

PURPOSE:To prevent the disconnection of wirings by selectivey removing an insulating film on an element to be crosslinked by aerial wirings covered with an insulating film on a substrate, opening a contacting hole, and forming a resist film with the element exposed on the surface in the hole as a hole. CONSTITUTION:A strip line 2, a capacitor 3, a lower electrode 4, an upper electrode 5 and a dielectric layer 6 are formed on a dielectric substrate 1, and an insulating film 7 is covered. Then, a negative resist film 8 formed on the film 7 as a mask, the film 7 is selectively removed, and a contacting hole 9 is formed on the element to be connected in a bridge. Then, the resist film is selectively removed by the same photomask used in case of patterning the film 8. Thus, the recess 10 is buried by the film 21. Then, a base metal layer 11 made of Cr-Pt-Au layer is formed entirely, Au is further covered to form a conductive metal layer 15. Subsequently, the films 11, 7 are removed.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a method for forming aerial wiring in a semiconductor integrated circuit device, a microwave integrated circuit device, or the like.

(b) Prior art and problems When manufacturing ultra-high frequency semiconductor devices made of gallium arsenide (GaAs) or microwave integrated circuit devices (IG) made using ultra-high frequency GaAs semiconductor elements, circuit elements Aerial wiring is often used to connect between

FIG. 1 is a sectional view of a main part showing the conventional method for forming an aerial wiring (hereinafter referred to as a bridge) in the order of steps, and is an example of manufacturing a microwave integrated circuit device.

In the same figure (al), 1 is a dielectric substrate made of ceramic, sapphire, etc., 2 is a strip line, 3 is a capacitor, and consists of a lower electrode 4, an upper electrode 5, and a dielectric layer 6 made of conductive metal, and 7 is an insulating layer.As shown in the figure, elements such as capacitor 3 and strip line 2
After forming wiring etc., an insulating film 7 of polyimide etc.
Cover the entire surface to make the surface flat.

Next, as shown in FIG. 3B, using the negative resist film 8 selectively formed on the insulating film 7 as a mask, the insulating film 7 is selectively removed, and the elements to be connected to each other by a bridge are removed. A contact hole 9 is formed above. This figure shows an example in which a contact hole 9 is formed on the surface of the strip line 2 and the upper electrode 5 of the capacitor 3. In this step, since the size of each contact hole 9 and the thickness of the resist film 8 on each element directly below it are different, the time required for etching is different for each contact hole. For this reason, a depression as shown in 10 in the same figure is formed.

After the above step, as shown in the same figure (C), the resist film 8
was removed, and chromium (Cr)-platinum (Pt)-gold (Au) was sequentially deposited on the entire surface by vapor deposition to form the base metal [11
, and then a resist film 12 is formed having an opening at the portion where the bridge is to be formed. In this step, if the aforementioned depression 10 exists, a resist pool 13 is formed there. After that, using the resist film 12 as a mask, the base metal layer 11 is plated to a thickness of about 5 [μm].
Although the conductive wiring layer 14 is formed by depositing Au, the Au layer is not formed on the resist pool 13.

Therefore, the resist film 12 is removed and the conductive wiring layer I4 is removed.
Dry etching such as ion milling method (
When unnecessary portions of the base metal layer 11 are removed by a dry etching method and the insulating film 7 is further removed by an ashing method using oxygen plasma, as shown in fd) in the same figure, the portion where the resist pool 13 was present is removed. bridge 15
is not formed, resulting in a disconnection state.

(C1 Purpose of the Invention The purpose of the present invention is to solve the above-mentioned problems and to provide a method for forming an aerial wiring in which disconnection does not occur.

(dl Structure of the Invention The feature of the present invention is that when forming aerial wiring in the main parts between a large number of elements arranged on a predetermined substrate, the substrate is covered with an insulating film, and the aerial wiring is used as a bridge. After selectively removing the insulating film on the element to be connected and opening a contact hole,
The method includes the steps of forming a resist film having an opening on the element whose surface is exposed in the contact hole, and forming a wiring made of a predetermined metal on the resist film and the exposed element. .

tel Embodiment of the Invention An embodiment of the present invention will be described below in the order of manufacturing steps with reference to the drawings.

FIG. 2 is a cross-sectional view of a main part sequentially showing the manufacturing process of the above embodiment. The same figure (al is a reproduction of the above-mentioned figure 1 (bl), and up to this point you can proceed according to the conventional manufacturing process. In addition, in Fig. 2, the same parts as in the above-mentioned Fig. 1 are given the same reference numerals. This is an indication.

In the conventional manufacturing method, a step of depositing a base metal layer 11 made of a Cr-Pt-Au layer was then carried out, but the base metal layer 11 was not formed in the 10 depressions formed by over-etching or the like. There was a problem.

Therefore, as shown in FIG. 2 (bl), in this embodiment, before forming the base metal layer 11, a resist film 21 is selected using the same photomask used for patterning the resist film 8 in FIG. 2(a). By doing so, the depression 10 is filled with the resist film 21 and disappears.

The subsequent steps may proceed according to the conventional manufacturing process again. That is, as shown in FIG. 2(C), the resist film 2
1 is selectively formed, a base metal layer 11 made of a Cr-Pt-'Au layer is formed on the entire surface, and then a resist film 12 is selectively formed with openings in the portion where the bridge is to be formed. Next, the above-mentioned base metal JIIL is coated by plating method.
Au is deposited on the exposed portion of 1 to form a conductive metal [14].

Next, as shown in FIG. 2, the unnecessary portions of the base metal layer 11 are removed by removing the resist layer 2 and applying a dry etching method such as ion milling using the conductive metal layer 14 as a mask. Furthermore, the insulating film 7 is removed by an ashing method using oxygen plasma, etc.The conductive metal layer 14 is slightly thicker than this when deposited so that it has a thickness of approximately 5 μm after the dry etching process is completed. I'll keep it.

Aerial wiring 15 according to this example obtained as described above
Since the base metal layer 11 is formed after filling the depression 10, which was a problem in the conventional manufacturing method, with a resist, there is no lack of the base metal, and therefore, the occurrence of disconnections in the aerial wiring is completely eliminated. Prevented.

if) As described in detail, the present invention provides a method for forming an aerial wiring without causing disconnection, and improves the reliability of an ultra-high frequency microwave integrated circuit device or an ultra-high frequency semiconductor device. Moreover, the manufacturing process is stable.

[Brief explanation of the drawing]

Figure 1 (al ~ (di is a sectional view of the main part for explaining the problems of the conventional method of forming aerial wiring, Figure 2 ta > ~ fd
) is a sectional view of a main part showing an embodiment of the present invention in the order of manufacturing steps. In the figure, 1 is a dielectric substrate, 2 is a strip line,
3 is a capacitor, the lower part 7 made of conductive metal is an insulating layer, and the lower part 8 is an insulating layer.
．． 12 and 21 are all resist films, 9 is a contact hole, 10 is a depression, 11 is a base metal layer, 13 is a resist reservoir, 14 is a conductive metal layer, and 15 is an aerial wiring.

Claims (1)

[Claims] When forming aerial wiring in the main parts between a large number of elements arranged on a predetermined substrate, the substrate is covered with an insulating film, and the insulating film on the elements to be bridged by the aerial wiring is selectively covered. After removing the contact hole to open a contact hole, forming a resist film having an opening over the element whose surface is exposed in the contact hole, and forming a base metal layer made of a predetermined metal on the resist crotch. a step of forming a resist film having an opening in a predetermined area including the top of the element to which the aerial wiring is to be connected; and forming a wiring made of a predetermined metal on the resist film and the exposed element. A method for forming an aerial wiring, comprising the steps of: