JPS60253206A - Thin film capacitor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thin film capacitor that is suitable as a passive element for a hybrid integrated circuit, and particularly has a high manufacturing yield and provides a large capacity with good reproducibility.

Thin films made of tantalum, titanium, hafnium, or alloys of these metals and elements, silicon, aluminum, etc. can be formed into oxides by anodization, and these oxides can be used to manufacture capacitors and It has the advantage that electronic circuit elements such as resistors can be made of the same metal, and is widely applied to hybrid integrated circuits. Additionally, oxides formed by vacuum evaporation or high frequency sputtering are also used in hybrid integrated circuits.

Conventionally, this type of thin film capacitor has had a certificate of commendation, as shown, for example, in a plan view and a sectional view taken along line AA in FIGS. 1 and 2, respectively. That is, a substrate 11 made of aluminum or beryllia or the like, on which a glaze material 12 made of silicon dioxide is partially or entirely formed, is used as a substrate for a thin film capacitor. Its function is to smooth out steep irregularities and prevent defects such as short circuits in the capacitor. On the glaze 12 is a metal thin film 1 that can be anodized.
3 is formed as a lower electrode in a generally linear rectangular shape, and furthermore, an anodized film 14 of a thin metal film is formed on the lower electrode 13 as a dielectric. On the metal thin film 13 on which no dielectric is formed, in order to obtain a good electrical connection with the outside, the capacitance of gold, etc. It is determined by the product of the effective area (referred to as the effective area) and the capacitance density (capacitance per unit area) of the dielectric [L Therefore,
A capacitor with a large capacity can be realized by increasing the effective area of the upper electrode 16. However, since the glaze 12 formed on the substrate 11 is sloped at its edges and has a rough surface with protrusions and depressions, the effect of smoothing the substrate by one glaze 12 is lower than that of the glaze 12. It is usually severely damaged at the ends. Therefore, when manufacturing a capacitor, as shown in FIG.
The effective upper electrode 16 is formed on the glaze 12 which is separated from the glaze 12 (indicated by a I in the figure) to prevent defects such as short circuits in the capacitor, and the effective area of the upper electrode 16 is The capacitance is limited by the area of the capacitor, and the increase in capacitance of the capacitor is naturally limited.

However, capacitors formed in this way have poor reproducibility of capacitance1. For example, when manufacturing the upper electrode 16 of the capacitor shown in FIG. When the dielectric 14 was formed with a capacitance change of only a few percent, the dielectric breakdown voltage was as low as about 150V or less. Dielectric breakdown occurs when the upper electrode 16 leaves the dielectric 14 and the glaze 1
Most of the damage occurs in the part where the voltage transitions to 2 (indicated by bl in the figure).Therefore, in order to obtain a capacitor with a high dielectric breakdown voltage, it is important to make the distance in the part shown by 5lb1 as short as possible. It became clear that In fact, if the upper electrode 16 is formed completely in the form of an island on the dielectric 14, b
If the distance between
As a result of experiments, it became clear that the above-mentioned improvement was achieved.

The poor reproducibility of capacitance and low dielectric breakdown voltage, which are disadvantages of the capacitor with the shape shown in Figure 1, can be improved by shortening the distance of the part indicated by <-gb' as shown in the plan view in Figure 3. For example, when the upper electrode 16 is shifted by about 100 μm in the A-in direction, the capacitance change can be about 1%, and the dielectric breakdown voltage can also be 190 V or more.

However, the capacitance of the capacitor shown in FIG.
The capacitance of the capacitor shown in FIG. It was also small. Note that the cross section along A-AJIK in FIG. 3 is the same as the cross section shown in FIG. 2.

Accordingly, an object of the present invention is to provide a thin film capacitor which has a high dielectric breakdown voltage, has a high manufacturing yield, and is capable of providing a large capacity with good reproducibility.

According to the present invention, a thin film capacitor characterized in that a cutout or a recess is provided in the lower electrode of the thin film capacitor is obtained.

Particularly, according to the present invention, in a thin film capacitor in which a lower electrode, a dielectric material, and an upper electrode are sequentially laminated on a glazed region on a substrate, the upper electrode is formed in a region spaced a predetermined distance inward from the end of the glazed region. A part of the periphery located inside has a protrusion that goes outside the above range, and the lower electrode crosses both sides adjacent to this protrusion so that the part of the periphery does not touch the protrusion of the upper electrode. A thin film capacitor characterized in that a recessed portion is formed, a region surrounded by the recessed portion and the protruding portion constitute a lead-out portion of the upper electrode, and the remainder of the upper electrode is located inside the periphery of the lower electrode. is obtained.

Embodiments of the present invention will be described in detail below with reference to FIGS. 4 to 7.

41 In the thin film capacitor according to the present invention, as shown in a plan view in FIG.
2 to be pulled upwards. A recess 20 is provided in the upper electrode 16 on the dielectric near the b1 portion.
4 and the end faces of the cutout portions of the lower electrode 13 extend in the direction in which the upper electrode 16 is drawn out, so that the areas of the dielectric 14 and the effective upper electrode are expanded in the direction in which the upper electrode 16 is drawn out. It is. Therefore, the capacitor according to the invention.

If the effective upper electrode 16 excluding the recess 20 is rounded so that it can be spread out at a constant distance am't from the end face of the glaze 12, the capacitance is 30-
However, it is possible to provide a capacitance that is only a few percent smaller than the capacitance of the capacitor shown in FIG. 1. Moreover, the capacitor according to the present invention also has the characteristics of the capacitor shown in FIG. A-A
The change in capacitance is small even with a shift in the direction. In addition, the fourth
A cross section of the figure is also shown in FIG.

In the first embodiment, the lower electrode 15 has one notch and the upper electrode 16 has one recess 20.
Even if a plurality of recesses 20 and notches are provided, the effects of the present invention are not impaired in any way; for example, in the case of a capacitor having two recesses 20 and two notches as shown in a plan view in FIG. Even if the upper electrode 16 is formed with a deviation in the A-in direction and the direction perpendicular to the A-A direction, the capacitance does not change at all, and it is possible to provide a specified capacitance with high precision and high reproducibility. It also has the advantage of being colored.

In the above embodiment 2') of the present invention, the upper electrode 1
Although the recess 20 of No. 6 is formed in a rectangular shape, the shape of the recess 20 is not particularly limited. For example, as shown in a plan view in FIG. 6, a semicircular recess 21 may be provided in the upper electrode 16. Of course, this is also a good thing.

Further, the concave electrode should not be formed only on the upper electrode 16, but as shown in a plan view in FIG.
Of course, it is also possible to form a recess 20 in the lower electrode 13 and extend the end surface of the upper electrode 16 to the outside of the dielectric from the recess 20.

The present invention provides a thin film capacitor that has a high dielectric breakdown voltage and can be manufactured with high yield and a large capacity with good reproducibility by drawing out the end faces of the electrodes. Therefore,
Naturally, the materials used in the present invention are not particularly limited.

[Brief explanation of the drawing]

FIGS. 1 and 2 show a plan view and a cross-sectional view of a conventional thin film air conditioner, respectively. FIG. 3 is a plan view showing another conventional thin film capacitor. 4 to 7 are plan views showing thin film conditioners according to embodiments of the present invention, respectively. FIG. 2 also shows a sectional view taken along line 0A-A in FIGS. 3 and 4. 11--Cera beam substrate, 12--Glaze, 13--Lower electrode, 14--Dielectric material,
15...-Good conductor thin film, 16...Top electrode, 20.21-...Concavity 3rd mouth 7th 4th Figure Haya 56/l Bad 6th Procedure Amendment Form (Method) ) Showa 60°! U, -4th day 1, Incident indication 1985 Patent application No. 19688 2
, Title of the invention: Thin film capacitor 3, Relationship to the amended person's case Applicant: 5-33-1 Shiba, Minato-ku, Tokyo (423) NEC Corporation Representative: Tadahiro Sekimoto 4, Agent: 108 Minato, Tokyo 5-37-8 Shiba Ward Resident Mita Building 5 Date of amendment order June 25, 1985 (shipment date) 6 Subject of amendment Column 7 for title of invention in the specification Contents of amendment Name of invention in the specification The column is for thin film capacitors. 33-

Claims (1)

[Claims] In a thin film capacitor formed by laminating a lower electrode, a dielectric material, and an upper electrode on a glazed region on a substrate, the upper electrode line is located within a range spaced apart in a predetermined order from an end of the glazed region inward. A part of the periphery of the lower electrode line has a protrusion pointing out of the range, and the lower electrode wire extends inward across both sides adjacent to the protrusion so that a part of the periphery thereof does not touch the protrusion of the upper electrode. A thin film characterized in that a region surrounded by a recess formed on the opposite side and the protrusion constitute a lead-out portion of the upper electrode, and the remainder of the upper electrode is located inside the periphery of the lower electrode. capacitor.