JPH05145021A - Integrated circuit device - Google Patents

Abstract

PURPOSE:To reduce noise which permeates from the power supply wiring of a digital IC part into the power supply wiring of an analog IC part via a semiconductor substrate, in the power supply wiring structure of a digital-analog mixed mounting IC. CONSTITUTION:The non-earth side power supply wiring layer 14A, of an analog IC part is formed on an insulating film 11 covering the surface of a semiconductor substrate 10, via a conducting layer 20 and an insulating film 22. The conducting layer 20 is connected with an earth side power supply terminal 16A2 of the analog IC part. The non-earth side power supply wiring layer 14D1 of a digital IC part is connected with the substrate 10. Digital system operation noise is to permeate into the power supply wiring layer 14A1 of the analog IC part via the substrate 10. However the conducting layer 20 acts as a shield layer, so that permeation noise is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital-analog mixed type integrated circuit device in which a digital IC (integrated circuit) part and an analog IC part are formed on a common semiconductor substrate, and more particularly to a non-grounded power supply for the analog IC part. By electrically separating the wiring from the semiconductor substrate and electromagnetically shielding it, noise mixed in the analog IC portion from the digital IC portion through the substrate is reduced.

[0002]

2. Description of the Related Art Conventionally, as a digital-analog mixed IC such as a DA converter or an AD converter, a chip structure as shown in FIG. 2 has been proposed.

In FIG. 2, a semiconductor substrate 1 made of silicon or the like is used.
On the surface of 0, digital IC section 12D and analog IC
The portion 12A is formed. The digital IC portion 12D is provided with a pair of power supply wiring layers 14D ₁ and 14D ₂ and power supply terminals (bonding pads) 16D ₁ and 16 connected to these wiring layers 14D ₁ and 14D _2.
D ₂ is provided. Power supply terminals 16D ₁ and 16D _2
Are provided with power supply potentials V _DD and V _SS , respectively, and in this example, a ground potential is provided as the potential V _SS .
The wiring layer 14D ₁ is connected to the substrate 10 at a plurality of points in the same manner as described later with reference to FIG.

In the analog IC portion 12A, a pair of power supply wiring layers 14A ₁ and 14A ₂ are provided, and power supply terminals (bonding pads) 16A ₁ and 16A connected to these wiring layers 14A ₁ and 14A ₂ , respectively.
_Two are provided. Power supply terminals 16A ₁ and 16A _2
Are provided with power supply potentials V _DD and V _SS , respectively, and in this example, a ground potential is provided as the potential V _SS .
The wiring layer 14A ₁ is connected to the N-type substrate 10 at a plurality of points through the connection holes of the insulating film 11 as shown in FIG. This is to suppress an increase in impedance due to wiring.

[0005]

According to the above-mentioned prior art, the power supply wiring (14) on the non-ground side of the digital IC section is used.
D ₁ , 16D ₁ ) and the non-grounded power supply wiring (14A ₁ , 16A ₁ ) of the analog IC section and the substrate 10 are connected to each other, and the same potential V _DD is applied to them.

In such a state, the digital IC
When the potential of the wiring layer 14D _{1 to the} substrate 10 changes due to the operation of the portion 12D, this potential change remains as it is.
₁ is transmitted to the analog IC unit 12A as noise. As a result, in the analog IC section 12A, the analog performance is deteriorated, and particularly in the DA converter or the like, there is a disadvantage that the conversion error increases.

An object of the present invention is to reduce noise mixed from the power supply wiring of the digital IC section to the power supply wiring of the analog IC section through the substrate.

[0008]

According to the present invention, in the integrated circuit device as described above, means for electrically separating the non-grounded power supply wiring of the analog IC portion from the semiconductor substrate and electromagnetically shielding it is provided. It is characterized by that.

[0009]

According to the structure of the present invention, since the non-grounded power supply wiring of the analog IC section is electrically separated from the board and electromagnetically shielded, the digital IC section is mixed into the analog IC section through the board. Noise is greatly reduced.

[0010]

1 shows a power supply wiring structure of an analog IC portion in a digital-analog mixed IC according to an embodiment of the present invention. Parts similar to those in FIGS. Detailed description is omitted.

A conductive layer 20 made of, for example, polysilicon is formed on the insulating film 11 covering the surface of the semiconductor substrate 10, and an insulating film 22 such as silicon oxide is provided on the conductive layer 20. As a result, the non-grounded power supply wiring layer 14A _{1 of} the analog IC section is formed. Wiring layer 14A ₁
Is connected to the power supply terminal 16A ₁ to which the power supply potential V _DD is applied, while the conductive layer 20 is connected to the power supply terminal 16A ₂ to which the ground potential is applied.

A power supply wiring layer 14D ₁ on the non-grounded side of the digital IC section is connected to the substrate 10. Therefore, although the digital system operating noise is to contamination from the substrate 10 to the wiring layer 14A _1, the wiring layer 14A ₁ are electrically isolated by insulating films 11, 22 from the substrate 10 and electromagnetically shielded by the conductive layer 20 Therefore, the mixed noise is greatly reduced.

In order to prevent the wiring impedance from increasing due to the electrical separation of the wiring layer 14A ₁ from the substrate 10, the width of the wiring layer 14A _{1 is} , for example, twice that of FIG. It is better to increase the above. Further, the thickness of the wiring layer 14A ₁ may be increased or the resistivity may be decreased.

[0014]

As described above, according to the present invention, the noise mixed into the analog IC section is reduced by separating and shielding the non-grounded power supply wiring of the analog IC section from the substrate. The effect of improving the S / N ratio or accuracy of is obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a power supply wiring structure of an analog IC section according to an embodiment of the present invention.

FIG. 2 is a perspective view showing an example of a conventional digital-analog mixed IC chip.

3 is a cross-sectional view showing a power supply wiring structure of an analog IC section in the IC chip of FIG.

[Explanation of symbols]

10: Semiconductor substrate, 11, 22: Insulating film, 14A ₁ , 1
4A ₂ , 14D ₁ , 14D ₂ : power supply wiring layer, 16A ₁ ,
_{16A 2, 16D 1, 16D 2} : power supply terminal, 20: shielding conductive layer.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location H01L 27/04 H 8427-4M

Claims (1)

[Claims] 1. An integrated circuit device in which a digital integrated circuit section and an analog integrated circuit section are formed on a common semiconductor substrate and the non-grounded power supply wiring of the digital integrated circuit section is connected to the semiconductor substrate. An integrated circuit device comprising means for electrically separating and electromagnetically shielding the non-grounded power supply wiring of the integrated circuit portion from the semiconductor substrate.