JPS6046534B2 - Method of manufacturing thin film capacitors - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in a method for manufacturing thin film capacitors.

Currently, TM type capacitors with a multilayer structure made of Ta-Ta2O5-Metal are widely used as capacitive elements for hybrid integrated circuits, having low loss, low temperature coefficient, and high reliability.

In order to obtain a capacitor with a particularly large capacitance using this structure, it is possible to make the dielectric thinner or to increase the capacitance area, as is generally known, but the stability of the electrical characteristics and the reliability It has been difficult to obtain thin film capacitors with desired performance in terms of performance and manufacturing yield. To meet this demand, a thin film capacitor called a TMM capacitor was devised.

This capacitor is Ta-Ta. O. -Mn0. One metal (
The withstand voltage of the capacitor is increased by utilizing the self-healing effect produced by inserting manganese dioxide (MnO film) as a semiconductor layer between the Ta2O5 layer and the metal layer of the TM type capacitor. This is an attempt to improve the drawbacks of the TM type capacitor by improving the . The conventional manufacturing method for this TMM type capacitor is to place 5,000 capacitors on a lamic substrate that has been cleaned in advance.
In order to meet this requirement, a Ta thin film having a thickness of Λ is deposited and a part of this Ta thin film is oxidized by an anodic oxidation method.
A thin film capacitor called an MM capacitor was considered.

This capacitor is made by forming a Ta-Ta2O3 dielectric, and then MnO on top of that. Finally, a highly conductive metal is attached to form an electrode. TMM type capacitors obtained by these manufacturing methods generally have high yields and high reliability, but the yield reliability varies depending on the manufacturing rod, and stable manufacturing is not possible. When we investigated the cause of this, we found that MnO was present on the anodic oxide film.

It has been found that during film formation, anodized films are severely degraded by thermal or chemical treatments. For example, Mn
When the O2 film is formed by the thermal decomposition method, the heat and reaction products during the thermal decomposition process of Mn(NO3)O cause many electron conductive defects in the oxide film, resulting in leakage current. It was observed that the withstand voltage J increased and the withstand voltage J also decreased significantly.
Even in the sputtering method, which allows processing at relatively low temperatures, the anodic oxide film is exposed to high temperatures of at least about 250° C., so thermal deterioration of the anodic oxide film is unavoidable. From the above, MnO, which has good adhesion, can be used to prevent damage to the dielectric on the pre-formed anodic oxide film. It is nearly impossible to attach a film, and this has been a major hindrance to improving the electrical characteristics and reliability of TMM type capacitors. The purpose of the present invention was to solve the above-mentioned problems, and it is to provide a method for manufacturing a TMM type capacitor that actively avoids thermal deterioration of the anodic oxide film in the MnO2 film deposition process. . The present invention involves the steps of attaching a manganese oxide film to a metal having a valve action formed on an insulating substrate, and performing anodic oxidation on the manganese oxide film to form an anodized film below the manganese oxide film. 1. A method of manufacturing a thin film capacitor, the method comprising at least the steps of: Next, the present invention will be explained in detail with reference to the drawings.

1 to 6 are cross-sectional views showing the manufacturing process of the present invention.

First, about 50% of
A β-Ta film 2 with a thickness of 0.00 mm is formed, and the β-Ta film 2 is patterned using a known photoetching technique (
Figure 2). Next, Ti3, Pd4, and then AU5 are deposited on the surface of the substrate 1 including the patterned β-Ta film 2 by vacuum evaporation. In this case, Ti and Pd are not added and A
Only u may be suffixed with -. Next, based on a known photoetching technique, Au5, Pd4, and Tj3 are selectively etched away to form the lower electrode of the capacitor (Figure 3).
. Next, a MnO2 film 6 is formed on the substrate surface by a thermal decomposition method, and patterned into a desired shape using a known photoetching technique (FIG. 4). In the thermal decomposition method used here, for example, a 5% diluted aqueous solution of manger nitrate (Mn(NO3)2.6FI20) is mixed at a rate of about 1.8 kg/cl/. is ejected from the nozzle of a spray gun together with air having a pressure of
This was sprayed onto the surface of the substrate heated to a temperature of about 300°C on a hot plate, and the Mn (N
In this method, a MnO2 film is deposited by instantaneously reacting O3)2 on the substrate surface. Next, MnO2 patterning 6
selectively covered with a photoresist film so that it is open;
Anodic oxidation is performed in a citric acid aqueous solution to form an anodic oxide film 7 of about 8000 A on the lower layer of the MnO2 pattern (FIG. 5). Next, NiCr8 and then MU9 are deposited as counter electrode materials, and finally a desired upper electrode pattern is formed (FIG. 6). As explained above in the examples, according to the method of the present invention, an anodic oxide film is generated after MnO2 deposition, so the thermal deterioration of the dielectric film that frequently occurred in the conventional method is eliminated, and the The mechanical characteristics and reliability also showed dramatic improvements.

Therefore, according to the method of the present invention, there is no concern about property deterioration or reliability deterioration that occurs when MnO2 is deposited, and a stable T
It becomes possible to manufacture MM type capacitors. In addition, in the method of the present invention, MnO.

The deposition method is not limited to the thermal decomposition method of manganese nitrate according to this embodiment, but of course sputtering method,
The MnO2 film may be formed by any method such as a chemical reduction method. Further, although this embodiment has been described using a Ta thin film, it is not limited to Ta thin films, and it is clear that the same effect can be obtained even if a metal having the same valve action as this is used.

[Brief explanation of drawings]

1 to 6 are cross-sectional views showing the manufacturing process of a thin film capacitor according to the present invention. 1... Glazed ceramic substrate, 2...
...Ta thin film, 3...Tjl4...P
dl5...AUl6...MnO2 film, 7...
...Anodic oxide film, 8...NiCrl9...
...Au.

Claims (1)

[Claims] 1 A step of attaching a manganese oxide film to a metal having a valve action formed on an insulating substrate, and a step of performing anodization on the manganese oxide film to form an anodized film under the manganese oxide film. A method of manufacturing a thin film capacitor, comprising: