JPH0818075A - Schottky barrier diode and semiconductor integrated circuit - Google Patents

Abstract

PURPOSE:To provide a Schottky barrier diode which has materialized high withstand voltage without raising the resistance value in a forward direction. CONSTITUTION:A cathode region 13 is made by selectively diffusing n<->-type impurities into a p<+>-type substrate 12 to serve as an anode region, and a p<+>-type anode contact region 14 is made outside the cathode region 13 on the substrate 12, and an n<+>-type cathode contact region 15 is made at the inner end of the cathode region 13 on the substrate 12. And, a plurality of p<+>-type impurity- diffused regions 17a are made dispersedly right below the anode electrode 16 extended from the anode contact region 14, being made on the surface of the substrate 12, and also an impurity-diffused region 17b positioned right below the end of the anode electrode 16 is made to partition, in plan view, the cathode region 13 into the side of the cathode contact region 15 and the residual section.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Schottky barrier diode and a semiconductor integrated circuit, and more particularly to a Schottky barrier diode which realizes a high breakdown voltage, and another semiconductor element including a MOS transistor together with the Schottky barrier diode. The present invention relates to an integrated semiconductor integrated circuit.

[0002]

2. Description of the Related Art As an example of a Schottky barrier diode which has realized a high breakdown voltage, for example, Japanese Patent Laid-Open No. 61-88 is available.
There is one disclosed in Japanese Patent No. 560.

[0003] The Schottky barrier diode, on an N ⁺ -type substrate substrate 1 as shown in FIG. 3 N ^-
A type epitaxial layer 2 is formed, P type impurities are selectively diffused on the epitaxial layer 2, and P type impurity diffusion regions 3 are scattered to form a structure.

In the Schottky barrier diode,
When a predetermined voltage is applied in a reverse bias state in which the anode electrode 4 formed on the surface of the epitaxial layer 2 has a negative potential and the cathode electrode 5 formed on the back surface of the substrate 1 has a positive potential, a predetermined voltage is applied to each impurity diffusion region 3 and the epitaxial layer 2. The depletion layer 6 extends from the junction with the layer 2 toward the epitaxial layer 2, and the extended depletion layer 6 is connected between the impurity diffusion regions 3 as shown in the figure. The depletion layer 6 realizes higher breakdown voltage than that of the Schottky junction itself.

[0005]

By the way, in the Schottky barrier diode having the above-described structure, the breakdown voltage in the reverse bias state in which the anode electrode 4 is at the negative potential and the cathode electrode 5 is at the positive potential is about 100 V at most. In order to increase the breakdown voltage, the epitaxial layer 2
Therefore, there is a problem that the resistance value increases in a forward bias state in which the anode electrode 4 is set to a positive potential and the cathode electrode 5 is set to a negative potential.

Therefore, the present invention has been proposed in view of the above problems, and an object of the present invention is to provide a shot capable of realizing a higher breakdown voltage without increasing the resistance value in the forward direction. A key barrier diode and a semiconductor integrated circuit using the same are provided.

[0007]

As a technical means for achieving the above object, a Schottky barrier diode according to the present invention is such that an element region of another conductivity type is formed on a substrate of one conductivity type. One electrode that makes ohmic contact is provided on the surface of the device region, and a first diffusion region of one conductivity type is formed on the surface of the device region to partition the one electrode side and the remaining side in plan view, and the remaining device region is formed. The second diffusion regions of one conductivity type are dispersedly arranged on the side surface, and the first region is formed by Schottky junction with the device region on the remaining side of the device region.
It is characterized in that the other electrode, which makes an ohmic contact with the second diffusion region, is formed by making an ohmic contact with the substrate.

In the semiconductor integrated circuit of the present invention, the Schottky barrier diode and the M conductivity type substrate are provided on the substrate.
In a semiconductor integrated circuit in which another semiconductor element including an OS transistor is formed, the drain electrode of the MOS transistor and the one electrode of the Schottky barrier diode are electrically connected, and the source electrode of the MOS transistor and the Schottky The other electrode of the barrier diode is electrically connected, and the Schottky barrier diode clamps a parasitic transistor formed between the MOS transistor and another semiconductor element so as not to turn on.

It is desirable that the MOS transistor connected to the Schottky barrier diode has a high breakdown voltage structure.

[0010]

In the Schottky barrier diode of the present invention,
During reverse bias, the depletion layer extends from the junction between the first and second diffusion regions and the element region toward the element region, and the depletion layer also extends from the junction between the substrate and the element region toward the element region. The extended double RESURF structure is formed, and in particular, the second diffusion region is formed by partitioning the element region, so that the pinch-off occurs at that portion based on the extension of the depletion layer from both the first diffusion region and the substrate. Therefore, high breakdown voltage can be realized. Further, the depletion layers extending from the second diffusion region are connected to each other at a voltage lower than the breakdown voltage of the Schottky junction,
Protect the Schottky junction until pinch-off in the first diffusion region.

In a semiconductor integrated circuit in which another semiconductor element including a MOS transistor is formed together with the Schottky barrier diode, even if a reverse voltage is applied between the drain electrode and the source electrode of the MOS transistor, the drain electrode and Since one electrode of the Schottky barrier diode is electrically connected, the parasitic transistor formed between the MOS transistor and another semiconductor element is not turned on by the low forward voltage of the Schottky barrier diode. Can be clamped as

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a Schottky barrier diode and a semiconductor integrated circuit using the same according to the present invention will be described with reference to FIGS.

The Schottky barrier diode 1 of the present invention
1 has a structure as shown in FIG. That is, N ⁻ type [other conductivity type] impurities are selectively diffused on a P ⁻ type [one conductivity type] substrate substrate 12 to form a cathode region [element region] 13, and the cathode region [device region] 13 is formed on the substrate substrate 12. A P ⁺ type anode contact region 14 is formed outside the cathode region 13. On the other hand, the substrate substrate 1
An N ⁺ type cathode contact region 15 is formed at the inner end of the cathode region 13 on the upper part 2. The anode electrode 16 made of aluminum or the like is formed on the substrate substrate 12.
From the anode contact region 14 toward the cathode contact region 15. This anode electrode 16
A plurality of P ⁺ -type impurity diffusion regions [second diffusion regions] 17a are dispersedly formed in the cathode region 13 immediately below. In the present invention, the P ⁺ -type impurity diffusion region [first diffusion region] 17b located immediately below the end of the anode electrode 16 is formed so as to partition the cathode region 13 into the cathode contact region 15 side and the remaining portion in plan view. To do. Incidentally, 18 is a cathode electrode formed in the cathode contact region 15,
19 is SiO ₂ Etc. is an insulating oxide film.

In this Schottky barrier diode 11, the cathode electrode 18 has a positive potential and the anode electrode 16 has a positive potential.
When a predetermined voltage is applied to the cathode region 13 in the reverse bias state with a negative potential, the depletion layer 20 extends from the junction between the impurity diffusion regions 17a and 17b and the cathode region 13 to the cathode region 13, and the extended depletion layer 20 is connected between the impurity diffusion regions 17a and 17b. On the other hand, the depletion layer 21 extends from the junction between the substrate substrate 12 and the cathode region 13 toward the cathode region 13. The cathode region 13 and the substrate 12, the diffusion region 17a, and the diffusion region 1 have a voltage lower than the breakdown voltage of the Schottky junction formed on the junction surface between the cathode region 13 and the anode electrode 16.
Diffusion regions 17a are dispersedly arranged so that the depletion layers 20 formed by the PN junctions formed by 7b are connected at the surface.
Therefore, the Schottky junction does not breakdown in breakdown voltage.

Since it is constructed for the above purpose, the diffusion region 17a
Is preferably as small as possible so as not to interfere with the forward current.

In the lateral Schottky barrier diode 11 having the double RESURF structure, the impurity diffusion region 17b located immediately below the end of the anode electrode 16 is formed.
Is formed to have a certain width, the depletion layer 20 extending from the impurity diffusion region 17b immediately below the end of the anode electrode 16 and the depletion layer 21 extending from the substrate substrate 12 are connected to each other and pinched off. Since it is completely cut off, a breakdown voltage corresponding to the width of the impurity diffusion region 17b can be obtained. Thus, in the lateral Schottky barrier diode 11 having the double RESURF structure, the forward current flowing in the cathode region 13 from the anode electrode 16 to the cathode electrode 18 is forward-biased in the impurity diffusion region 17a. , 17b, and the resistance value in the forward direction does not increase. Further, pinch-off of the depletion layer 20 from the impurity diffusion region 17b immediately below the end of the anode electrode 16 and the depletion layer 21 from the substrate substrate 12 can improve the breakdown voltage up to about 500V.

Next, FIG. 2 shows a semiconductor integrated circuit in which another semiconductor element 23 including a MOS transistor 22 is formed together with the Schottky barrier diode 11 described above.

This semiconductor integrated circuit has a structure in which another semiconductor element 23 including a MOS transistor 22 described later is incorporated in the same substrate substrate 12 on which the Schottky barrier diode 11 described above is formed.
The S transistor 22 is, for example, another MOS not shown.
The H bridge is composed of a transistor and a circuit.

This MOS transistor 22 has a high withstand voltage having a double RESURF structure, and selectively forms an N ^-- type impurity diffusion region 24 to be a drain region on the substrate substrate 12, and further, its surface. Diffusion area 2 on the side
A P ⁻ -type impurity diffusion region 25 is formed so as to divide 5 into two. An N ⁺ -type impurity diffusion region 26 to be a contact region of the drain electrode is formed on one side of the P ⁻ -type impurity diffusion region 25, and on the other side, outside the N ⁻ -type impurity diffusion region 24. P ⁺ type impurity diffusion region 2
7 and an N ⁺ -type impurity diffusion region 28 serving as a source region are formed adjacent to each other, a drain electrode 29 is drawn from the N ⁺ -type impurity diffusion region 26, and a P ⁺ -type and N ⁺ -type impurity diffusion region 27 is formed. , 28 to pull out the source electrode 30. Then, a gate electrode 31 made of polysilicon or the like is formed on the substrate substrate 12 across the N ⁻ type impurity diffusion region 24 and the N ⁺ type impurity diffusion region 28 with a gate oxide film interposed therebetween. According to this structure, a high breakdown voltage M is obtained by the same action as that of the Schottky barrier diode described above.
Obtain an OS transistor. Incidentally, 32 is another semiconductor element 2.
3 is an N ⁻ -type impurity diffusion region in which 3 is formed. Also,
The P ⁻ type impurity diffusion region 25 is electrically connected to the source electrode 30.

In the semiconductor integrated circuit, when a negative surge voltage is momentarily applied to the drain electrode 29 of the MOS transistor 22 with respect to the source electrode 30, the drain electrode 29 is at a negative potential.
When the N ⁻ type impurity diffusion region 34 of the other semiconductor element 23 is at the positive potential, a current flows from the substrate substrate 12 to the N ⁻ type impurity diffusion region 24 toward the drain electrode 29, and the substrate substrate 12 And a drain electrode 29 as an emitter and an N ⁻ -type impurity diffusion region 34 of another semiconductor element 23 as a collector are formed and turned on. Therefore, an element or circuit including the N ⁻ type impurity diffusion region 34 malfunctions.

In the present invention, the MOS transistor 22
By electrically connecting the drain electrode 29 and the source electrode 30 of the Schottky barrier diode 11 to the cathode electrode 18 and the anode electrode 16 of the Schottky barrier diode 11, respectively, the parasitic transistor 35 can be driven by the low forward voltage of the Schottky barrier diode 11. Can be clamped so as not to turn on, and the other semiconductor elements 23 do not malfunction.

In the case of this embodiment, since the anode electrode 16 and the source electrode 30 are connected to each other on the substrate 12, it is not always necessary to wire them outside the substrate, but since the substrate has a high specific resistance, it is a MOS transistor. Depending on the arrangement of 22 and the Schottky barrier diode 11, it is preferable to connect the wiring outside the substrate.

According to this embodiment, there is an advantage that the Schottky barrier diode 11 and the MOS transistor 22 can be simultaneously formed in exactly the same process. The diffusion region 17b of the Schottky barrier diode 11 and the diffusion region 25 of the MOS transistor 22 may have the same width dimension to have the same high breakdown voltage.
It is also possible to reduce the width dimension of the diffusion region 17b to reduce the breakdown voltage of the Schottky barrier diode 11 and use it as a protection diode against an overvoltage applied to the MOS transistor 22. Further, the formation of the MOS transistor is not limited to this embodiment, and other forms can be applied.

[0024]

According to the Schottky barrier diode of the present invention, at the time of reverse bias, the depletion layer extending from the impurity diffusion region located immediately below the end of the anode electrode and the depletion layer extending from the substrate pinch off, so that the breakdown voltage jumps. It is possible to realize a high breakdown voltage Schottky barrier diode without increasing the resistance value in the forward direction.

Further, according to the semiconductor integrated circuit incorporating the Schottky barrier diode, even if the drain electrode of the MOS transistor has a negative potential, M
Since the parasitic transistor formed between the OS transistor and the other semiconductor element can be clamped so as not to be turned on by the low forward voltage of the Schottky barrier diode, the other semiconductor element does not malfunction and the reliability is greatly improved. Improve to.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a Schottky barrier diode according to the present invention.

FIG. 2 is a sectional view showing an embodiment of a semiconductor integrated circuit according to the present invention.

FIG. 3 is a sectional view showing a conventional example of a Schottky barrier diode.

[Explanation of symbols]

11 Schottky Barrier Diode 12 One Conduction Type Substrate [Substrate Substrate] 13 Element Region [Cathode Region] 14 Anode Contact Region 15 Cathode Contact Region 16 Other Electrode [Anode Electrode] 17a Second Diffusion Region [Other Impurity Diffusion Region] 17b First Diffusion Region [Impurity Diffusion Region Immediately Under Edge of Anode Electrode] 18 One Electrode [Cathode Electrode] 22 MOS Transistor 23 Other Semiconductor Element 29 Drain Electrode 30 Source Electrode 33 Parasitic Transistor

Claims (4)

[Claims] 1. An element region of another conductivity type is formed on a substrate of one conductivity type, one electrode which makes ohmic contact is provided on the surface of the element region, and the one electrode side and the other electrode are left on the surface of the element region. Forming a first diffusion region of one conductivity type that divides the side in a plan view, dispersively disposing second diffusion regions of one conductivity type on the surface of the remaining side of the element region, and A Schottky barrier diode, characterized in that the other electrode, which is Schottky-junctioned to the element region and ohmic-joined to the first and second diffusion regions, is ohmic-joined to the substrate. 2. A cathode region, which is selectively N-type, is formed on a P-type substrate that serves as an anode region, and a P-type anode contact region is formed outside the cathode region on the P-type substrate, and the cathode is formed. An N-type cathode contact region is formed at the inner end of the region, and a plurality of P-type impurity diffusion regions are dispersedly formed immediately below the anode electrode formed on the surface of the P-type substrate and extending from the anode contact region. A Schottky barrier diode characterized in that an impurity diffusion region located immediately below an end of the anode electrode is formed so as to partition the cathode region into a cathode contact region side and a remaining side in a plan view. 3. A semiconductor integrated circuit in which another semiconductor element including a MOS transistor is formed on a substrate of one conductivity type together with the Schottky barrier diode according to claim 1.
The drain electrode of the MOS transistor and the one electrode of the Schottky barrier diode are electrically connected, and the source electrode of the MOS transistor and the other electrode of the Schottky barrier diode are electrically connected, and the Schottky A semiconductor integrated circuit in which a barrier diode clamps a parasitic transistor formed between a MOS transistor and another semiconductor element so as not to turn on. 4. The semiconductor integrated circuit according to claim 3, wherein the MOS transistor connected to the Schottky barrier diode has a high breakdown voltage structure.