JPH0575029A - Semiconductor device - Google Patents

Abstract

PURPOSE:To make small operation resistance and noise by forming a Zener diode, a transistor, which amplifies a Zener current, and a capacitor, which negatively feeds back noise voltage to the transistor, on a semiconductor substrate. CONSTITUTION:An NPN transistor is provided by forming an n-type region 4 inside a p-type region 3, and a Zener diode of P-N<+> junction is provided by forming an n<+>-type region 5 inside the p-type region 3, and one electrode of a capacitor is provided by forming a P<+>-type region 6 inside the p-type region 3. Next, a thermal oxide film is provided on the surface of the opening part, and the oxide films on the n-type region 4 and the n<+>-type region 5 are removed, and then an aluminum layer is provided selectively to form an electrode 7, and the PNP transistor part, the Zener diode part, and the capacitor part are connected, and an electrode 8 is provided at the rear of an n-type silicon substrate 1. Hereby, operation resistance and noise can be made small.

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 semiconductor device having a constant voltage diode.

[0002]

2. Description of the Related Art In a conventional semiconductor device, as shown in FIG. 6, a silicon oxide film 2 provided on the surface of an N-type silicon substrate 1 is selectively etched to form an opening, and the opening is surrounded by the opening. An acceptor impurity is selectively diffused into the P type diffusion layer 18. Next, inside the P-type region 18, the P-type region 1
A P ⁺ type region 19 having an acceptor impurity concentration higher than that of No. 8 is formed. Next, after forming the N ⁺ type region 20 on the outer periphery of the P type region 18, the silicon oxide film on the P ⁺ type region 19 is removed,
An electrode 7 connected to the P ⁺ type region 19 and the P type region 18 of the opening and an electrode 8 provided on the back surface of the N type silicon substrate 1 are formed to form a constant voltage diode.

[0003]

In this conventional semiconductor device, shot noise is generated in the low current region after breakdown of the PN junction due to local fluctuation of carrier density in the junction. This noise increases as the breakdown voltage increases, and there is a problem that malfunction may occur due to noise when a constant voltage diode having a high Zener voltage is incorporated in the circuit.

Further, the higher the Zener voltage is, the lower the impurity concentration of the semiconductor substrate is, so that there is a characteristic problem that the operating resistance is increased.

[0005]

A first semiconductor device of the present invention comprises a base region of opposite conductivity type provided on the upper surface of a semiconductor substrate of one conductivity type and a collector region of one conductivity type provided in the base region. And a Zener diode of one conductivity type, and an electrode that is connected to the collector region and the Zener diode and that forms a capacitor between the collector region and the Zener diode and the base region.

According to a second semiconductor device of the present invention, an opposite conductivity type base region and a Zener diode are selectively provided on the upper surface of a one conductivity type semiconductor substrate, and one conductivity type emitter region is provided in the base region. And an electrode that is connected to the base region and the Zener diode and forms a capacitor between the base region and the Zener diode and the semiconductor substrate via a dielectric film.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view of a semiconductor chip showing a first embodiment of the present invention.

As shown in FIG. 1, the silicon oxide film 2 provided on the surface of the N-type silicon substrate 1 is selectively etched to form a first opening portion, and the N-type silicon substrate 1 at the opening portion is formed. The acceptor impurities are diffused on the surface to form the P-type region 3. Next, a silicon oxide film is deposited on the surface including the first opening portion, the second opening portion is selectively provided, and the donor impurity is diffused to form the N-type region 4 in the P-type region 3. To form an N ⁺ type region 5 in the P type region 3 and to form a P · N ⁺ junction Zener diode portion to form a P ⁺ type region 6 in the P type region 3. One electrode of the capacitor section is provided. Next, a thermal oxide film is provided on the surface of the opening to remove the oxide film on the N-type region 4 and the N ⁺ region 5, and an aluminum layer is selectively provided to form an electrode 7 to form an NPN transistor portion and The Zener diode part and the capacitor part are connected, and the electrode 8 is formed on the back surface of the N-type silicon substrate 1.
To form a composite element having the equivalent circuit shown in FIG.

Here, a positive voltage is applied to the cathode (electrode 7) terminal and a negative voltage is applied to the anode (electrode 8) terminal, and when a certain voltage is exceeded, the Zener diode of the P.N.sup. ⁺ Junction breaks down, Current is injected into the base of the NPN transistor, turning on the transistor. Since the transistor amplifies the current, the operating resistance becomes 1 / h _fe .

FIG. 3 is a diagram showing the voltage-current characteristics of the first embodiment of the present invention.

As shown in FIG. 3, the noise voltage of the zener diode can be negatively fed back from the output (collector) of the transistor to the input (base) of the transistor through the capacitor to reduce the noise of the output characteristic.

FIG. 4 is a sectional view of a semiconductor chip showing a second embodiment of the present invention.

As shown in FIG. 4, the silicon oxide film 10 provided on the surface of the P-type silicon substrate 9 is selectively etched to provide a first opening to diffuse the donor impurity, and the N-type region 11a, 11b is formed. Next, the N-type regions 11a, 1
P-type regions 12a and 12b are formed in 1b, respectively, and PN
Make a P-transistor part. Further, the N ⁺ type region 13 is selectively formed on the surface of the P type silicon substrate 9 to provide a Zener diode portion of P · N ⁺ junction, and the P ⁺ type substrate 13 is selectively formed on the surface of the P ⁺ type. A region 14 is formed to provide one electrode of the capacitor section. Next, a thermal oxide film is provided on the surface of the opening to open the oxide film of the P type regions 12a and 12b and the N ⁺ type region 13, and an aluminum layer is selectively provided to form the electrodes 15a, 15b and 15c. Then, the electrode 16 is provided on the back surface of the P-type silicon substrate 9 to form the composite element of the equivalent circuit shown in FIG.

Here, a positive voltage is applied to the cathode (electrode 15c) terminal and a negative voltage is applied to the anode (electrode 16) terminal. When a certain voltage is exceeded, the Zener diode of the P · N ⁺ junction breaks down, A current flows through the base of the PNP transistor, turning on the transistor. Since the transistor amplifies the current, the operating resistance is reduced. Since the noise voltage is negatively fed back to the base of the transistor through the capacitor, noise is reduced.

[0016]

As described above, according to the present invention, the operating resistance and noise are reduced by forming the Zener diode section, the transistor section for amplifying the Zener current and the capacitor section for negatively feeding back the noise voltage to the transistor on the semiconductor substrate. It has the effect of being able to.

[Brief description of drawings]

FIG. 1 is a sectional view of a semiconductor chip showing a first embodiment of the present invention.

FIG. 2 is an equivalent circuit diagram of the first embodiment of the present invention.

FIG. 3 is a diagram showing voltage-current characteristics of the first embodiment of the present invention.

FIG. 4 is a sectional view of a semiconductor chip showing a second embodiment of the present invention.

FIG. 5 is an equivalent circuit diagram of the second embodiment of the present invention.

FIG. 6 is a sectional view of a semiconductor chip showing an example of a conventional semiconductor device.

[Explanation of symbols]

1 N-type silicon substrate 2, 10 Silicon oxide film 3, 12a, 12b, 18 P-type region 4, 11a, 11b N-type region 5, 13, 20 N ⁺ type region 6, 14, 19 P ⁺ type region 7, 8 , 15a, 15b, 15c, 16 electrodes 9 P-type silicon substrate

Claims (2)

[Claims] 1. A base region of opposite conductivity type provided on the upper surface of a semiconductor substrate of one conductivity type, a collector region of one conductivity type and a zener diode of one conductivity type provided in the base region, and the collector region and zener. A semiconductor device, comprising: an electrode connected to a diode and forming a capacitor between the diode and the base region via a dielectric film. 2. A base region of opposite conductivity type and a Zener diode selectively provided on the upper surface of the one conductivity type semiconductor substrate,
An emitter region of one conductivity type provided in the base region,
A semiconductor device comprising: an electrode connected to the base region and the Zener diode and forming a capacitor between the base region and the Zener diode and the semiconductor substrate via a dielectric film.