JPS589576B2 - Hakumakuyouriyousoshino Seizouhouhou - Google Patents

Description

[Detailed Description of the Invention] This invention is a novel trimming method for adjusting the capacitance of thin film capacitive elements used in electronic components, etc. The present invention relates to a method of manufacturing a thin film capacitive element including the present invention.

Thin film capacitive elements used as electronic components are used for thin film circuits, etc., but these capacitive elements are made of SiOSiO, Zn
It is formed using S or the like as a dielectric material.

When forming a thin film capacitive element on a substrate using the vapor deposition method, it is generally not easy to control the temperature of the substrate, the vapor deposition rate, the degree of vacuum in the vapor deposition tank, etc., so the thickness of the dielectric thin film is controlled so that it always follows the design. It is extremely difficult to manufacture a thin film capacitive element with a capacitance of The capacitance was adjusted to the desired value by peeling off part of the electrode so that the capacitance was adjusted to the desired value.

However, since this method directly changes the area of the electrode, it is difficult to perform the processing work to precisely trim the capacitance value, and often results in defective products due to excessive cutting.

In order to prevent this, it is possible to use many fine patterns to make the work easier, but in reality, there is a risk of damaging the dielectric material or shorting between electrodes during trimming. However, the change in capacitance value occurs in stages, making it impossible to trim continuously in minute amounts.

The present invention was made to eliminate such drawbacks, and involves connecting a trimming electrode made of a material that can be anodized to the main electrode of a thin film capacitor, and then anodizing the trimming electrode to form fine particles. This is a method of manufacturing a thin film capacitor element that performs trimming to obtain a desired capacitance value.

In other words, a trimming electrode is formed in advance from a metal that can be anodized so as to span both the inner upper electrode of the upper and lower electrodes that sandwich the dielectric thin film of the thin film capacitive element and the dielectric thin film and serve as an extension of the upper electrode. However, by anodizing this trimming electrode, the electrode area is continuously changed and the capacitance of the thin film capacitive element is set to a desired value.

The method of the present invention will be explained below with reference to the drawings.

As shown in FIGS. 1 and 2, a lower electrode 12 is formed on a quartz substrate 11 by vapor deposition, a dielectric thin film 13 is formed on this electrode 12, and then an upper electrode is formed on this thin film 13. 1
form 4.

Furthermore, a trimming electrode 15 is formed of a metal that can be anodized so as to span both the upper electrode 14 and the dielectric thin film 13.

In this way, a thin film capacitive element is formed, which is composed of a lower electrode, a dielectric thin film, an upper electrode, and a trimming electrode formed to span the upper electrode and the dielectric thin film and serve as an extension of the upper electrode. .

A bottomed box made of an insulator with a portion of the bottom cut out is used as a container to hold the electrolyte.

The container is arranged so that the opening in the bottom surface is above the trimming electrode.

The container is filled with an electrolytic solution, and a cathode plate is placed so as to be immersed in the solution and facing the end of the trimming electrode.

The anode plate is placed on the outside of the container in contact with the trimming electrode.

When a DC voltage is applied between the anode plate and the cathode plate in this state, the trimming electrode undergoes anodic oxidation and becomes oxide from the solid edge, forming a dielectric thin film in the portion of the trimming electrode that remains in the form of metal. Since the area of the contacting side gradually decreases, trimming is stopped when the thin film capacitive element reaches a desired capacitance value.

Example, as shown in FIGS. 1 and 2, an alumina substrate 11
Thoroughly wash and clean the Cr, then Au to 200 Å.
is deposited to a thickness of 1500λ to form the lower electrode 12,
A dielectric material of SiO is deposited on top of this lower electrode by vapor deposition.
A dielectric thin film 13 is formed by vapor deposition to a thickness of 500 mm, and is patterned to approximately the desired capacitance value.

Next, the upper electrode 14 is formed by depositing Cr to a thickness of 200 layers and Au to a thickness of 1,500 layers.

1 layer of Al is applied across the dielectric thin film 13 and the upper electrode 14.
The trimming electrode 15, which is an extension of the upper electrode, is formed by vapor deposition to a thickness of 1,000 mm.

As shown in FIG. 3, a container 21 containing an electrolytic solution is placed on the trimming electrode 15 of the thin film capacitive element formed as described above.

This container 21 is a box-shaped body with a bottom made of an insulating material such as hard rubber, and the electrolyte is contained in the bottom of the container 21.
An aperture 22 is provided for contacting the.

A container 21 is arranged as shown in the figure, a mixed aqueous solution of sulfuric acid and nitric acid is placed in the container, and a cathode plate 23 made of platinum is placed above the end of the trimming electrode 15 so as to be immersed in the electrolyte.

The anode plate 24 is brought into contact with the trimming electrode 15 as shown on the outside of the container.

A voltage is applied from a DC power source E between the anode plate 24 and the cathode plate 23 to anodize the trimming electrode 15.

Even if the trimming electrode 15 is anodized, its apparent volume does not change, but the closer it is to the end facing the cathode plate 23, the more the trimming electrode 15 is oxidized.

Therefore, the area of the entire metal part of the upper electrode including the trimming electrode facing the lower electrode 12 of the capacitive element becomes smaller continuously over time, so anodization is performed while measuring the capacitance of the capacitive element. The anodic oxidation is then stopped when the capacitive element reaches the desired value.

In this way, a thin film capacitive element having a desired capacitance value is formed.

As described above, according to the method of the present invention, A[ and T] can be anodized without peeling or cutting the electrode.
A trimming electrode is formed with i or Nb, and this trimming electrode is anodized from the end to continuously change the opposing area between the upper and lower electrodes of the capacitive element. It is extremely efficient because the capacitance can be adjusted and trimming can be performed continuously while monitoring changes in capacitance.

[Brief explanation of drawings]

FIG. 1 is a plan view schematically showing a thin film capacitive element for carrying out the method of the present invention, FIG. 2 is a cross-sectional view taken along plane 2-2 of FIG. FIG. 2 is an explanatory diagram showing an outline of the state in which anodic oxidation is performed in order to carry out the method. 11...Substrate, 12...Lower electrode, 1
3... Dielectric thin film, 14... Upper electrode, 15... Trimming electrode, 21...
・Electrolyte solution container, 23...Cathode plate, 24...
・Anode plate.

Claims (1)

[Claims] 1. A step of forming a lower electrode on a substrate, a step of forming a dielectric thin film on this lower electrode, a step of forming an upper electrode on this dielectric thin film, and a step of forming both this upper electrode and dielectric thin film. A step of forming a trimming electrode made of a metal that can be anodized so as to span over the upper electrode and become an extension of the upper electrode, and anodizing the trimming electrode so that the capacitance of the thin film capacitive element reaches a desired value. 1. A method for manufacturing a thin film capacitive element, comprising a step of trimming.