JPH08298307A - Semiconductor device - Google Patents

Abstract

PURPOSE: To improve the frequency characteristic without increasing the mounting area by forming a decoupling capacitor in the MIM structure. CONSTITUTION: A capacitor in the MIM structure is formed of an upper electrode 5 for a ground electrode connected to a lower layer electrode 2 provided on a silicon substrate 1 in a microwave integrated circuit chip through a contact hole 4 of an insulating film 3 and an upper layer electrode 6 for a power supply electrode opposed on the lower layer electrode 2 through the insulating film 3 so as to allow reduction of a mounting area as compared to a case of an outboard capacitor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device, and more particularly to a decoupling capacitor for a microwave integrated circuit.

[0002]

2. Description of the Related Art When a microwave integrated circuit, especially a wide band amplifier is arranged and used on a substrate, noise such as ripples induced from an external power source affects frequency characteristics and the like, resulting in deterioration of band characteristics. The flatness characteristic may be deteriorated and the original characteristics of the amplifier may not be reproduced on the substrate.

Therefore, conventionally, as shown in FIG. 2, an external capacitor such as a chip capacitor (usually, between a wiring formed on a substrate for connecting an integrated circuit power supply terminal to an external power supply terminal and a ground terminal is used). By connecting and arranging a decoupling capacitor), ripples from the external power supply were dropped to the ground terminal.

As for the arranged capacitors, the wider the integrated circuit is used, the several kinds of capacitance values (10000 pF, 1000 pF, 100 pF) for each frequency band.
It was necessary to combine and arrange capacitors of 10 pF or the like).

[0005]

In this conventional semiconductor device, since the external decoupling capacitor is used, there is a problem that the number of parts is increased at the time of mounting and a large mounting space is required.

[0006]

According to the present invention, there is provided a semiconductor device comprising:
A lower layer electrode formed on a Si substrate, an insulating film formed on the surface of the Si substrate including the lower layer electrode, a contact hole provided in the insulating film to expose a surface of one end of the lower layer electrode, and the contact hole A first upper layer electrode electrically connected to the lower layer electrode exposed inside;
A second upper-layer electrode formed on the lower-layer electrode other than the upper-layer electrode via the insulating film and facing the lower-layer electrode.

[0007]

Next, the present invention will be described with reference to the drawings.

FIGS. 1A and 1B are a plan view and a sectional view taken along the line AA 'showing an embodiment of the present invention.

As shown in FIGS. 1A and 1B, the lower layer electrode 2 is selectively formed on the Si substrate 1 in the microwave integrated circuit chip, and the Si substrate 1 including the lower layer electrode 2 is formed. Then, the insulating film 3 having a thickness of about 400 nm is deposited, and the upper portion of the insulating film 3 on the lower electrode 2 is selectively etched to reduce the thickness to 50 nm. Next, a contact hole 4 is formed in the insulating film 3 at one end of the lower layer electrode 2 to expose the surface of the lower layer electrode 2, and a metal film is deposited on the surface of the insulating film 3 including the contact hole 4 for patterning. It is formed on the first upper layer electrode (ground electrode) 5 electrically connected to the lower layer electrode 2 exposed in the hole 4 and extending on the insulating film 3, and on the lower layer electrodes 2 other than the upper layer electrode 5. As a result, a second upper layer electrode (power supply electrode) 6 facing the lower layer electrode 2 via the insulating film 3 is formed. Next, a passivation film 7 covering the surface including the upper layer electrodes 5 and 6 is formed and patterned, and bonding pads 8 and 9 are formed on the upper layer electrodes 5 and 6, respectively, to form an MIM capacitor.

In this case, the capacitance value C of the MIM capacitor
Is C = ε _O · ε _S · S / d (where ε _O is the dielectric constant of the vacuum, ε _S is the relative dielectric constant of the dielectric film, S is the MIM capacitor area, and d is the thickness of the dielectric film).
Given in.

Here, S = 100 μm × 100 μm, ε
_{If S} = 7, a capacitance value of about 12 pF can be secured.

By incorporating such an MIM capacitor, the chip capacitor for the high frequency region can be eliminated, the influence of ripples from the power source can be eliminated and the high frequency characteristics can be improved without increasing the chip size or mounting area. Becomes

In this embodiment, it is important that the bonding pad 8 for the ground electrode and the bonding pad 9 for the power supply electrode are laid out adjacent to each other. This is because when the bonding pad 8 and the bonding pad 9 are laid out separately and are connected by a single-layer wiring, it is necessary to lay out the outer peripheral portion of the bonding pad, which leads to an increase in the pellet size.

The capacitors used in integrated circuits include:
MIS (Metal-Insulator-Semiic)
There are some types of on-conductor structure, but it is necessary to select various constants for the capacitance value of the built-in capacitor, depending on the operating frequency and application circuit, and the MIS structure may not be able to handle these, whereas the MIM structure. In that case, there is an advantage that a desired capacitance value can be realized only by the metallizing process.

[0015]

As described above, according to the present invention, the decoupling capacitor in the microwave integrated circuit, especially in the wide band amplifier is the MIM structure capacitor (about 10 pF).
In this case, the band characteristic is improved (10% to 20% in the region over 2 GHz) and the flatness is improved (flatness ± 1 dB to ± 0.2 dB) without increasing the mounting area and the chip size. It has the effect that the improvement can be realized.

[Brief description of drawings]

FIG. 1 is a plan view and a sectional view taken along the line AA ′ showing an embodiment of the present invention.

FIG. 2 is a block diagram illustrating an example of a conventional semiconductor device.

[Explanation of symbols]

 1 Si substrate 2 Lower layer electrode 3 Insulating film 4 Contact hole 5,6 Upper layer electrode 7 Passivation film 8, 9 Bonding pad

Claims (1)

[Claims] 1. A lower layer electrode formed on a Si substrate, an insulating film formed on the surface of the Si substrate including the lower layer electrode, and a contact hole provided in the insulating film to expose a surface of one end of the lower layer electrode. A first upper layer electrode electrically connected to the lower layer electrode exposed in the contact hole, and the lower layer electrode formed on the lower layer electrodes other than the first upper layer electrode via the insulating film. Second facing
And an upper layer electrode.