JPH01166541A - Semiconductor device and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain the mechanical strength of metal wirings without increasing its parasitic capacitance by forming a thin film on the upside of the wiring to reinforce it. CONSTITUTION:After a whole element is covered with an SiO2 film 105, it is coated with photoresist, and etched to selectively remove the film 105 at a predetermined position on a source electrode 103. Then, the whole face is covered with metal wirings 107 made of a 3-layer structure of M-Au-Mo. Thereafter, a predetermined wiring pattern is formed of a thin boron nitride film 108, selectively processed thereby to complete metal wirings. Thereafter, the photoresist used to form the pattern of the metal wirings and the film 105 is removed by ashing, thereby forming air bridge wirings having a cavity 106. Accordingly, a mechanical strength is strengthened by the film 108, and the metal wiring of a thin film can be supported in the air without increasing its parasitic capacitance.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor device, and particularly to a metal wiring structure suitable for ultra-high-speed operation and a method for manufacturing the same.

[Conventional technology]

In the metal wiring of a semiconductor device, reducing the parasitic capacitance of the wiring part is advantageous for high-speed operation of the semiconductor element (for example, T. Enoki et al.: ELECTRONIC: S LETTE).
R5).

van, 22. Nn2. It is known that the so-called air bridge method is effective as a specific method (for example, T. Andrada: Solid State Technology).
y) Magazine, 1985 Edition No. 2, P199).

[Problem that the invention seeks to solve]

In the above-mentioned conventional technology, in order to form metal wiring in the air, a thickness of, for example, at least 1.5 μm is required, and it is necessary to selectively form it in a predetermined portion, so a plating method is usually used. It was getting worse.

As is well known, the Metsuki method has low industrial productivity and
Since raw materials are used inefficiently, costs are high, especially when gold is used. Furthermore, plating baths usually use cyanide compounds, which pose problems such as concerns that they may be harmful to the human body.

The purpose of the present invention is to eliminate the need for the Metsuki method.

The object of the present invention is to provide a structure of a semiconductor device that realizes air bridge wiring using an industrially established method such as dry etching.

[Means for solving problems]

The above object is achieved by providing a structure in which a thin film material for reinforcing the metal wiring is provided on top of the metal wiring in order to ensure the mechanical strength of the metal wiring and to prevent the parasitic capacitance of the wiring from increasing.

[Effect]

The reinforcing thin film formed on the interconnection NiA layer enables air insulation between the half-quad elements formed below or other interconnection layers even if the interconnection layer has a thickness of 1 μm or less.
There is no need to use methods that are difficult for fine wiring, such as Au plating, as in the past.

〔Example〕

An embodiment of the present invention will be explained below with reference to FIG. 1. This embodiment is an example in which wiring to the source electrode 103 of a Schottky junction field effect transistor using Q a A s single crystal is realized by an air bridge. 0 Impurity diffusion layers 102 . The source and drain electrodes 103', gate electrode 104 form a field effect transistor (MH3FE).
The entire primary element formed with T) is Si
After covering with the Oz film 105, the 5iOz 105 at predetermined locations on the source electrode 103 was selectively removed by normal photolithography and dry etching. Next, without removing the photoresist (not shown) used for Sing processing, M was applied to the entire surface by vacuum evaporation.
o -A u -Mo each film thickness 110-700
A metal wiring 107 having a three-layer structure of -10n was deposited. Further, a BN (boron nitride) film 108 with a thickness of 11000 nm was formed by sputtering. Next, a predetermined wiring pattern was formed by ordinary photolithography, and the BN and the upper Mo thin film were selectively processed by fluorine-based plasma.

Next, the Au1L film was processed by Ar ion milling method, and the lower Mo film was further processed by fluorine-based plasma etching, and metal wiring and S i Oz
At the same time, the photoresist film used to form the thin film pattern was removed by ashing. As a result, as shown in the cross-sectional structure in FIG. 1, it was possible to form an air bridge wiring having a hollow portion, for example, at a portion 106. As is well known, the BN thin film has strong mechanical strength, so the thin film metal wiring could be supported in the air without being deformed.

Although this embodiment describes a semiconductor device using a GaAs substrate, the present invention is equally effective in pursuing ultrahigh speed in InP and other compound semiconductor devices, or in Si semiconductor devices. This is clear from the principle of the invention. Also, regarding wiring metal, AQ and W depending on where the element is used.

Various materials can be selected including Ni and the like. In addition to BN, SiN can be used as a reinforcing material for wiring metal.

It can be made of a material commonly used in semiconductor processes, such as 5iOz, to provide lightning resistance. In addition, the shape of the reinforcing material does not need to be the same pattern as the metal wiring layer.

Furthermore, in this embodiment, the wiring layer is M o -A u
-Mo was used, but BaY, which has even weaker mechanical strength,
Of course, the present invention is also effective when using superconducting wiring such as CuO-based wiring.

〔Effect of the invention〕

According to the present invention, since air bridge wiring can be formed without plating, productivity can be improved, and since fine wiring can be formed with higher precision than conventional methods, reliability of semiconductor devices can be improved. This has a significant effect on improving productivity and reducing costs.

[Brief explanation of the drawing]

Figure 1 shows an air bridge wiring material G according to an embodiment of the present invention.
FIG. 2 is a cross-sectional structural diagram of an aAs field effect transistor. 101...G a As substrate, 102... Impurity diffusion layer.

Claims (1)

Claims: 1. A semiconductor device having a metal wiring insulated via air from a substrate on which a semiconductor element is formed, characterized in that a thin film is disposed on the metal wiring. 2. The semiconductor device according to claim 1, wherein the thin film material is an insulator. 3. The semiconductor device according to claim 1, wherein the metal wiring and the thin film have the same shape in a plane parallel to the substrate. 4. The semiconductor device according to claim 3, wherein the metal wiring has a thickness of 1 μm or less. 5. The semiconductor device according to claim 3, wherein the metal wiring contains at least one element from groups Ib, IIIb, and VIa of the periodic table of elements. 6. The semiconductor device according to claim 2, wherein the thin film material is an insulator containing at least one element selected from the group consisting of Si, B, N, and O. 7. The semiconductor device according to claim 2, wherein the thin film material is a polyimide polymer. 8. Forming an organic polymer film on the substrate material on which at least one of the semiconductor element and the metal layer is formed;
A step of forming a hole for electrical connection with the semiconductor element or the metal layer in a predetermined region of the organic polymer film, a step of forming a metal thin film for wiring on the entire surface including the hole, and a step of forming a metal thin film for wiring on the entire surface including the hole. a step of applying a thin film material to reinforce the thin film for use;
A step of processing and forming a predetermined wiring pattern on the thin film material, a step of selectively processing the metal thin film for wiring using the processed thin film material as a mask, and a step of removing the organic polymer film to form a substrate material. 1. A method of manufacturing a semiconductor device, the method comprising the step of forming a cavity between a metal interconnect and a metal interconnect.