JPS5931239B2 - Method for manufacturing thin film circuit elements - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing thin film circuit elements, and in particular to a method for manufacturing metal thin film resistors and thin film capacitors.

Thin films of metals that can be anodized, such as tantalum, titanium, and hafnium, have the advantage that electronic circuit elements such as resistors and capacitors can be formed from the same metal by using the oxides produced by anodizing. Tantalum thin films are especially stable over time. It is being put into practical use because of its excellent performance and reliability.

For example, tantalum nitride thin films having a temperature coefficient of resistance of -90 p.mu.m/.degree. C. are widely used as resistors. However, if a circuit requires a high-precision resistor whose resistance value does not depend on temperature, tantalum nitride thin film resistors are subjected to treatments such as vacuum heat treatment, which improves their characteristics and satisfies the requirement. However, the anodization of a metal thin film that has been subjected to vacuum heat treatment may result in clouding or peeling from the metal thin film due to the effects that are thought to be caused by the reaction between impurity gases in the vacuum chamber and the metal thin film. Therefore, it is difficult to control the properties of the anodized film and the reliability of the anodized film is low.

Because metal thin films subjected to vacuum heat treatment have these drawbacks, it is virtually impossible to manufacture thin film capacitors using anodization of the thin films, and it is difficult to manufacture thin film resistors. However, due to phenomena such as peeling of the anodized film,
It does not function as a sufficient protective film against thermal oxidation, etc.
The stability of the resistor over time is not satisfactory. The object of the present invention is to obviate such conventional drawbacks. It is an object of the present invention to provide a method for manufacturing a thin film circuit element with high precision and stability over time. The method for manufacturing a thin film circuit element of the present invention includes a step of depositing a dielectric thin film on a metal thin film on a substrate on which a circuit element is to be formed, and subjecting the metal thin film to high-temperature heat treatment using the dielectric thin film as a protective film against the surrounding atmosphere. and then removing the dielectric thin film.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

1 to 6 are cross-sectional views showing each step of an embodiment of the present invention, in which a tantalum nitride thin film 2 is deposited at a thickness of about 1600 Å by an active sputtering method on a substrate 1 having a clean surface such as clasp ceramic, glass, alumina, etc. Further, a silicon oxide thin c film 3 was deposited on the tantalum nitride thin film 2 to a thickness of about 10,000 A by high-frequency sputtering (FIG. 1). Next, the substrate was heated to 600°C and 55°C.
By heat-treating at temperatures of 0°C and 500°C for about 5 hours, the temperature coefficient of resistance of the tantalum nitride thin film 2 is -90ppm.
/℃ to approximately +20ppm/℃, 0ppm/℃ respectively
and -20 ppm/°C. Thereafter, a silicon dioxide thin film 3 and a tantalum nitride thin film 2 are formed by photolithography.
was formed into a desired shape (Fig. 2), and unnecessary silicon dioxide thin film 3 on tantalum nitride thin film 2 was removed (Fig. 3).
figure). The substrate is heat-treated in air at 300° C. for about 7 hours to thermally stabilize the tantalum nitride thin film 2, and then the tantalum nitride thin film 2 in the capacitor portion is anodized at 150 V to form an oxide thin film 4. After removing the silicon dioxide thin film 3 (Fig. 5), the tantalum nitride thin film 2, which was to serve as a resistor, was anodized to form an oxide film 4' and the resistance value was adjusted. A thin gold film 5 of about 3,000 layers is deposited on the substrate.
It was deposited by the A vapor deposition method and formed into a desired shape by photolithography to produce a thin film circuit element (FIG. 6). The equivalent circuit of this circuit is shown in FIG. By using the method of manufacturing a thin film circuit element of the present invention, a silicon dioxide thin film is deposited on a tantalum nitride thin film, and the substrate is heat-treated at a high temperature of 400°C or higher in air, thereby performing a process equivalent to vacuum heat treatment. In addition, since the surface of the tantalum nitride thin film is protected by the silicon dioxide thin film during the high-temperature heat treatment, if the method for manufacturing thin film circuit elements according to the present invention is used, it is possible to avoid vacuum heat treatment, which is a problem in the case of vacuum heat treatment. Reaction between the impurity gas inside the tantalum nitride thin film and the tantalum nitride thin film can also be avoided.

Therefore, the high-temperature heat treatment makes it possible to obtain a highly reliable thin film resistor with a zero temperature coefficient of resistance with good reproducibility. In addition, the anodized tantalum nitride thin film that has been subjected to the high-temperature heat treatment is extremely stable, making it possible to manufacture highly reliable thin film capacitors, and making it possible to adjust the resistance value of thin film resistors. The anodized film 4' formed for this purpose functions as a stable protective film, making it possible to provide a highly reliable thin film resistor. In an embodiment of the present invention. Tantalum nitride, which is a composition of tantalum and nitrogen, was used as the metal thin film 2, but even if a low-density tantalum thin film with a high specific resistance, which is extremely unstable without treatment, is used, the present invention provides a thin film circuit that is stable over time. devices can be manufactured.

Furthermore, since metals such as tantalum, titanium, and hafnium have similar properties as poorly soluble metals, the present invention is still applicable even if these metals or at least compounds containing these metals are used as the metal thin film 2. Of course. Also,
The thickness of these poorly soluble metal thin films is not particularly limited. As the oxide film 3 in this embodiment, a thin film of silicon with a dioxylic acid ratio is used, but it may be a thin film of alumina, silicon nitride, etc., but it is practically preferable to use an oxide having a high melting point. Further, the film thickness is not particularly limited, but it is practically desirable to have a thickness of 2000λ or more. Also,
The high-temperature heat treatment temperature is closely related to the heat treatment time, and in consideration of the reproducibility of manufactured thin film circuit elements, the heat treatment temperature is preferably 400° C. or higher and the heat treatment time is 30 minutes or longer. Furthermore, the heat treatment conditions are also related to the thickness of the metal thin film 2, and when the film thickness is large, a longer heat treatment is required.

[Brief explanation of drawings]

1 to 6 are sectional views showing each step of an embodiment of the present invention, and FIG. 7 is an equivalent circuit diagram thereof.

Claims (1)

[Claims] 1 Tantalum, titanium, on the substrate on which the circuit elements are to be formed
A thin film of metal such as hafnium that can be anodized is coated with a thin film of dielectric material such as silicon dioxide, alumina, or silicon nitride.
A method for manufacturing a thin film circuit element, comprising the steps of heat-treating the metal thin film in air using the dielectric thin film as a protective film against the outside atmosphere, and removing the dielectric thin film after the heat treatment.