JPH0750779B2 - Semiconductor integrated circuit - Google Patents

Description

The present invention relates to a semiconductor integrated circuit in which circuit blocks having different signal frequencies and signal levels such as FM / AM tuners are formed on the same semiconductor substrate.

(B) Conventional technology Electronic equipment such as TV tuners, FM / AM tuners, etc.
Since the audio signal is extracted from the frequency) signal, the frequency of the signal handled by each circuit block divided by function is often different. For example, FM tuners for Japan only handle RF signals of 76 to 90 MHz, intermediate frequency signals of 10.7 MHz, audio signals of 20 to 2000 Hz, and wide range of signals of 20 Hz to 90 MHz.

An example of the FM / AM tuner is shown in FIG. In the figure, (1) is an FM front end that selects an FM broadcast and frequency-converts it to an intermediate frequency by mixing the received frequency signal and the oscillation frequency signal of the local oscillation circuit (2) in the mixing circuit (3). A circuit, (4) is an FM / IF amplifier circuit that amplifies and limits the amplitude of an intermediate frequency signal (IF signal) and detects it to obtain an audio signal (AF signal). (5) is, for example, Japanese Patent Publication No. 62-21461 The noise cancellation circuit having the function as described in (6) is L in the case of stereo broadcasting.
A multiplex circuit for demodulating channel and R channel signals, and (7) is an AM tuner circuit for selecting an AM broadcast and outputting an audio signal. For example, in case of FM broadcast reception,
The FM front end circuit (1) receives the RF signal input from the antenna (8) and high frequency amplified by the RF amplification circuit (9) and the oscillation frequency signal output by the local oscillation circuit (2) of the FM front end circuit (1). The IF signal is output from the FM front end circuit (1) by mixing in the mixing circuit (3) of
The composite signal is output from the FM / IF amplifier circuit (4) by detecting the IF signal in the detector circuit of the FM / IF amplifier circuit (4), and the L channel is output to the output terminal (10) by the multiplex circuit (6). , R channel audio signals are output. An FM tuner circuit having such a structure is described, for example, on page 152 of “'88 Sanyo Semiconductor Data Book Portable Audio Bipolar Integrated Circuit Edition”, issued on Dec. 10, 1987.

By the way, in recent years, electronic devices are required to be smaller and have higher performance, and accordingly, the circuit of FIG. 5 is being integrated into one chip as much as possible. However, in the example of the FM tuner, since the FM front end circuit (1) handles a high frequency signal of several tens of MHz, interference with other circuits due to unnecessary radiation is likely to occur. Further, since the weak level signal from the antenna (8) is handled, the circuit operation is likely to become unstable due to the interference with other circuit blocks, and in a remarkable case, it oscillates. Therefore, it was extremely difficult to integrate the FM front end circuit (1) into one chip.

(C) Problems to be Solved by the Invention As described above, it is extremely difficult to integrate a circuit that handles a high frequency signal such as the FM front end circuit (1) in the related art because circuit interference easily occurs. there were.

(D) Means for Solving the Problems The present invention has been made in view of the above drawbacks, and is a semiconductor integrated having a plurality of electronic block regions in which a plurality of electronic block circuits are respectively integrated on one semiconductor chip. In the circuit, a first electron block region (21) which is one of the electron block regions and which generates or is susceptible to unwanted radiation, and the first electron block region (2
Dummy island region formed around 1) (22)
And the first electrode (23) which is in ohmic contact with the dummy island region (22) and is formed in substantially the same shape.
And a shield electrode (24) which makes ohmic contact with the first electrode (23) and covers the first electron block region (21) and the first electrode (23).
Cutting area formed by cutting 3) into multiple areas (25)
And the wiring (26) provided in the cutting region (25).

(E) Action According to the present invention, the wiring between the elements in the first electron block region (21) is substantially formed in the first layer, and this wiring is formed by the shield electrode (24) and the first electrode ( Since it can be covered with 23), unnecessary radiation from the inside does not go out, and unnecessary radiation from the outside does not enter the inside. Therefore, interference can be prevented.

(F) Embodiments Embodiments of the present invention will be described below with reference to the drawings.
As shown in FIG. 2, there are a P-type semiconductor substrate (31) and an N-type epitaxial layer (32) laminated on the semiconductor substrate (31).

Here, the semiconductor substrate (31) has a rectangular shape, and transistors, diodes, resistors, capacitors, etc. are formed in the epitaxial layer (32), and the P ⁺ -type isolation region (33) and the buried layer are formed. (34) is also built in. A plurality of electronic circuits are integrated in the epitaxial layer (32) on the semiconductor substrate to form a plurality of electronic block regions. Further, one of the electron block regions is formed in the region (21) shown by the broken line in FIG. This region (21) is a first electron block region that particularly emits unwanted radiation or is susceptible to unwanted radiation from the outside. Further, around the first electron block area (21), an N-type dummy island area (22) indicated by a broken line is formed.
Are formed.

Next, the first-layer insulating film (35) coated on the epitaxial layer (32) and the first-layer electrode (shown by a chain line) formed on the first insulating film (35) ( There are 23) and (26).

Here, the first insulating film (35) is formed by, for example, thermal oxidation or CVD.
The first-layer electrodes (23) and (26) are silicon oxide films formed by the method described above and are vapor-deposited with aluminum. First
The electrode of the layer is a normal wiring, which is mainly wiring between semiconductor elements integrated in the block region, a signal line (26) between the block regions, a feedback line (26) and the first electrode (2
3) has been formed. Wiring between the semiconductor elements on the first electronic block region (21) shown in FIGS. 1 to 4 is omitted, and the signal line and the feedback line are (26) and the N-type dummy island region ( The first electrode having substantially the same shape as 22) is indicated by (23) and is indicated by a dashed line in the drawing. The first electrode (23) serves as the first insulating film (3
It is in ohmic contact with the dummy island region (22) via (5). Moreover in the dummy island region (22) where the first diffusion region (3 N ⁺ type to reach the epitaxial layer (32) N ⁺ -type buried layer from the surface (34)
6) is formed, and the first diffusion region (36) is in ohmic contact with the first electrode (23).

On the other hand, the first electrode (23) is cut in a plurality of areas and has a cut area (25). This cutting area (2
There are 4) 5), and the width is such that one on the left side, two on the right side, two on the upper side and three on the lower side and three feedback lines can be wired.

Further, the first-layer insulating film (35), the second-layer insulating film (37) formed so as to cover the first-layer electrode, the first electron block region (21) and the first-electron block region (21). There is a shield electrode (24) that covers one electrode (23).

Here, the second insulating film (37) is, for example, a film of PIX or the like, and the shield electrode (24) is made of aluminum vapor-deposited. In addition, around the semiconductor chip,
Although there are a plurality of pads, one of them, the power supply pad (27), is connected to the shield electrode (24).

Therefore, the shield electrode (24) and the first electrode (23) have the same potential at VCC applied to the power supply pad, and the first diffusion region (36) also has the same potential. Therefore, the electrode having the potential of VCC forms a tunnel shape in the cut region (25), and the signal line and the feedback line are provided in this tunnel and extend to other block regions.

Here, FIG. 3 and FIG. 4 show the BB ′ line, C- in FIG.
It is a cross-sectional view taken along the line C ′ and has the same configuration as that of FIG.

The above configuration can be applied to, for example, an FM / AM stereo tuner circuit or the like. In the first electronic block area (21), a fifth
By integrating the FM front end block (1) shown in the figure, it is possible to prevent interference from other electronic block areas and interference with other electronic block areas.

Further, the FM front end block (1) handles a signal of a very small level of several μV, and thus particularly dislikes the interference from the FM-IF block (4).
It may be applied to the FM-IF block (4).

Moreover, the shield electrode (24) is connected to the power supply pad (27), and the shield electrode (24) is connected to the dummy island (22).
By making ohmic contact with the first diffusion region (36) in, the FM front end block can be integrated into one chip.

(G) Effect of the invention As is apparent from the above description, since the shield electrode (24) and the first electrode (23) shield the signal line, the feedback line, etc. provided under the shield electrode (24). The wiring does not receive unnecessary radiation from the outside, and does not generate unnecessary radiation from the inside to the outside.

On the other hand, the wiring extending to the external block area enters and leaves the cutting area (25), which is a limited area, so
Unnecessary radiation generated from the side surface of the wiring in the electronic block region (21) can be prevented.

Secondly, since the potentials of the shield electrode (24), the first electrode (23) and the first diffusion region (36) can be set to the same potential VCC, the generation and penetration of radiation including high frequency components is further increased. It can be firmly prevented.

Thirdly, by providing the N ⁺ -type first diffusion region (36) in the dummy island region (22), PN with the isolation region (33) is formed.
The potential barrier due to the junction can be increased, and the leak current from the outer block region and the leak current from the first electron block region (21) to the outer block region can be prevented.

Moreover, since the first diffusion region (36) has a high concentration, it can be used as an alternating current ground, so that the dummy island
It becomes VCC, and the voltage fluctuation of other block areas is not given to the first electronic block area (21).

Fourth, by integrating the FM front end block in the first electronic block area (21), the FM front end block can be integrated into one chip.

[Brief description of drawings]

1 is a top view of the semiconductor integrated circuit of the present invention, FIG. 2 is a sectional view taken along the line AA 'in FIG. 1, and FIG. 3 is B in FIG.
Fig. 4 is a sectional view taken along line -B ', Fig. 4 is a sectional view taken along line CC' of Fig. 1, and Fig. 5 is a block diagram illustrating an FM / AM stereo tuner circuit. (21) …… first electron block area, (22) …… dummy island area, (23) …… first electrode, (24) …… shield electrode, (25) …… cutting area, (26)… …wiring.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location H01L 27/04 H04B 1/10 N 9298-5K 15/02 9298-5K 9169-4M H01L 21/76 J

Claims (3)

[Claims] 1. A semiconductor integrated circuit having a plurality of electronic block regions in which a plurality of electronic block circuits are respectively integrated in a semiconductor layer of one semiconductor chip, wherein one of the plurality of electronic block regions is provided. The first electron block region which generates unnecessary radiation or is susceptible to unnecessary radiation is surrounded by an island-shaped dummy island region which is surrounded by a separation region of one conductivity type formed in the semiconductor layer, A first insulating film formed on the first insulating film on the semiconductor layer and having substantially the same shape as the dummy island;
The electrode makes ohmic contact with the dummy island region, and in the cutting region formed by cutting the first electrode, an electronic block circuit formed in the first electronic block region and the first electronic block region are formed. A shield electrode provided on the second-layer insulating film on the semiconductor layer is provided with a wiring for electrically connecting to an electronic block circuit formed on other than the power supply pad provided on the periphery of the semiconductor chip. A semiconductor integrated circuit which is connected to the first electrode and makes ohmic contact with the first electrode to cover the first electron block region and the first electrode. 2. FM / A in a semiconductor layer of one semiconductor chip
A semiconductor integrated circuit having a plurality of electronic block regions in which a plurality of electronic block circuits configuring an M stereo tuner circuit are respectively integrated, wherein an FM front end block region which is one of the plurality of electronic block regions is Surrounded by an island-shaped dummy island region surrounded by an isolation region of one conductivity type formed in the semiconductor layer, provided on the first-layer insulating film on the semiconductor layer, and substantially separated from the dummy island. Formed in the same shape
The electrode is in ohmic contact with the dummy island region, and the cutting region formed by cutting the first electrode has the FM
Wiring for electrically connecting an electronic block circuit formed in the front end block region and an electronic block circuit formed in a region other than the FM front end block region is provided, and insulation of the second layer on the semiconductor layer is provided. The shield electrode provided on the film is connected to a power supply pad provided around the semiconductor chip, and makes ohmic contact with the first electrode to cover the FM front end block region and the first electrode. Semiconductor integrated circuit. 3. The semiconductor according to claim 1, wherein the first electrode is formed in the dummy island region and makes ohmic contact with a high-concentration first diffusion region of the same conductivity type as the dummy island region. Integrated circuit.